A familial mutation in the testis-determining gene SRY shared by both sexes. A familial mutation in SRY, the gene coding for the testis-determining factor TDF, was identified in an XY female with gonadal dysgenesis, her father, her two brothers and her uncle. The mutation consists of a T to C transition in the region of the SRY gene coding for a protein motif known as the high mobility group (HMG) box, a protein domain known to confer DNA-binding specificity on the SRY protein. This point mutation results in the substitution, at amino acid position 109, of a serine residue for phenylalanine, a conserved aromatic residue in almost all HMG box motifs known. This F109S mutation was not found in 176 male controls. When recombinant wildtype SRY and SRYF109S mutant protein were tested in vitro for binding to the target site AAC AAAG, no differences in DNA-binding activity were observed. These results imply that the F109S mutation either is a rare neutral sequence variant, or produces an SRY protein with slightly altered in vivo activity, the resulting sex phenotype depending on the genetic background or environmental factors.


Analysis of segregation and expression of an identified mutation at the neurofibromatosis type 1 locus. A previously identified complex mutation, affecting exon 28 of the neurofibromatosis type 1 gene, was employed for the analysis of the expression pattern in primary cultures of neurofibroma cells and melanocytes from a café-au-lait macule of the patient, respectively. Reverse transcription and subsequent polymerase chain reaction amplification of the segment carrying the mutation revealed that both alleles were expressed in both cell types analysed, thus excluding loss of heterozygosity in this particular instance. Segregation of the alleles of the intragenic Alu sequence length-polymorphism disclosed the paternal origin of the mutated allele. Detection of this mutation was also used for presymptomatic direct DNA diagnosis in the younger child of the patient.


Bloom's syndrome. XVIII. Hypermutability at a tandem-repeat locus. D1Z2 is a highly polymorphic DNA locus composed of a tandem of repetitive units. Its molecular constitution has been examined in 61 clonal cell lines selected at random from two lymphoblastoid cell lines (LCLs), each of which had been proliferating in vitro for several hundred days. Thirty-three of the cells were selected from an LCL derived from the blood of a person with Bloom's syndrome (BS), and the others from a normal person. A total of 20 distinctive band alterations in D1Z2 were observed, all in BS cells: appearance of a novel band(s); disappearance of a band(s), or alterations in the intensity of a band(s). Unequal sister-chromatid exchange giving rise to intra-locus mutation is considered the most plausible explanation for the accumulation of the changes detected.


Detection of fetal cells with 47,XY,+21 karyotype in maternal peripheral blood. Fetal cells were isolated from the peripheral blood of a pregnant woman at 19 weeks of gestation whose fetus had Down syndrome. An amniocentesis had been performed 2 weeks earlier because of abnormalities detected on an antenatal sonogram. Fetal cells were separated by fluorescence-activated cell sorting using monoclonal antibody to the transferrin receptor (TfR). Fluorescence in situ hybridization studies with probes for chromosomes Y and 21 revealed a small number of 47,XY,+21 cells in the TfR+ sorted fraction. Although preliminary, the results of this study suggest the possibility that one day, fetal chromosome aneuploidy will be routinely diagnosed from maternal venous blood samples.


Complete characterization of a large marker chromosome by reverse and forward chromosome painting. Marker chromosome are small supernumerary chromosomes that are sometimes associated with developmental abnormalities. Hence, the genes involved in such cases provide an interesting approach to understanding developmental abnormalities in man. As a first step towards isolating such sequences, marker chromosomes need complete characterization. By combining chromosome isolation by flow sorting and the "degenerate oligonucleotide primed - polymerase chain reaction", we have constructed a DNA library specific for a marker chromosome found in a child with severe developmental abnormalities. We used fluorescent in situ hybridization of the library onto normal metaphase spreads ("reverse chromosome painting") and were thus able to determine that the marker consists of the centromeric part of chromosome 7, the telomeric region of the long arm of chromosome 5 and the telomeric region of the short arm of the X-chromosome. Subsequently, we hybridized normal chromosome-specific libraries of the relevant chromosomes onto metaphases containing the marker chromosome ("forward chromosome painting") and could in this manner establish the precise location of the different chromosome regions on the marker chromosome itself. This is a general approach suitable for outlining marker chromosomes in detail, and will aid the identification of the genes involved.


Molecular analysis of five independent Japanese mutant genes responsible for hypoxanthine guanine phosphoribosyltransferase (HPRT) deficiency. Five independent mutations in the hypoxanthine guanine phosphoribosyltransferase (HPRT) gene were identified in a partially HPRT deficient patient with gout and in four Lesch-Nyhan patients. Using the polymerase chain reaction (PCR) technique coupled with direct sequencing, the nucleotide sequences of the entire HPRT coding region amplified from the cDNA and also of each exon amplified form the genomic DNA were analyzed. Three independent point mutations in the coding region were detected in the partially HPRT deficient patient (Case 1) and in two Lesch-Nyhan patients (Case 2 and 3), resulting in single amino acid substitutions. The family study of Case 3, utilizing a PvuII restriction site created in the mutant gene, indicated that the mother was a heterozygote, and a sister and a fetal brother had inherited the normal HPRT gene from the mother. In two other mutants causing Lesch-Nyhan syndrome, a portion of the HPRT gene was deleted, and RNA splicing was missing in both mutants. A 4-bp deletion at the 5' end of exon 4 resulted in formation of three different types of abnormal mRNA (Case 4). The other mutant (Case 5) produced abnormal mRNA including 26 bp of intron 8 instead of the deleted 58 bp at the 5' end of exon 9, because of a 74-bp deletion from intron 8 to exon 9.


Variants of the anti-Müllerian hormone gene in a compound heterozygote with the persistent Müllerian duct syndrome and his family. The persistent Müllerian duct syndrome (PMDS) is a rare form of male pseudohermaphroditism, characterized by the persistence of Müllerian derivatives in otherwise normal males. Two mutations, present in the homozygous state, have been previously described in such patients. The present observation is the first example of compound heterozygosity in this condition. DNA was obtained from a 3-month-old patient with PMDS, in whom no serum anti-Müllerian hormone (AMH) could be detected by enzyme-linked immunosorbent assay. Sequencing of cloned polymerase chain reaction amplified fragments of the AMH gene revealed a 14-bp deletion in the second exon of the maternal allele; this deletion disrupted the open reading frame. It occurred at a site containing two 8-bp direct repeats flanking a 6-bp sequence and removed one whole repeat plus all of the intervening sequence. It may be the result of a slipped mispairing at the DNA replication fork. The paternal allele contains a stop mutation in the third exon. These two mutations, impairing both AMH alleles, are consistent with the occurrence of PMDS, and are shared with a phenotypically normal younger sister. In this family, various other mutations, devoid of physiological significance, suggest that the AMH gene is highly polymorphic.


The intron 7 donor splice site transition: a second Tay-Sachs disease mutation in French Canada. Mutations at the hexosaminidase A (HEXA) gene which cause Tay-Sachs disease (TSD) have elevated frequency in the Ashkenazi Jewish and French-Canadian populations. We report a novel TSD allele in the French-Canadian population associated with the infantile form of the disease. The mutation, a G-->A transition at the +1 position of intron 7, abolishes the donor splice site. Cultured human fibroblasts from a compound heterozygote for this transition (and for a deletion mutation) produce no detectable HEXA mRNA. The intron 7 + 1 mutation occurs in the base adjacent to the site of the adult-onset TSD mutation (G805A). In both mutations a restriction site for the endonuclease EcoRII is abolished. Unambiguous diagnosis, therefore, requires allele-specific oligonucleotide hybridization to distinguish between these two mutant alleles. The intron 7 + 1 mutation has been detected in three unrelated families. Obligate heterozygotes for the intron 7 + 1 mutation were born in the Saguenay-Lac-St-Jean region of Quebec. The most recent ancestors common to obligate carriers of this mutation were from the Charlevoix region of the province of Quebec. This mutation thus has a different geographic centre of diffusion and is probably less common than the exon 1 deletion TSD mutation in French Canadians. Neither mutation has been detected in France, the ancestral homeland of French Canada.


Mapping of X chromosome translocation breakpoints in females with Duchenne muscular dystrophy with respect to exons of the dystrophin gene. There are rare female patients who suffer from Duchenne or Becker muscular dystrophy because they carry an X;autosome translocation with a breakpoint in the dystrophin gene. We have defined the positions of seven of these breakpoints with respect to exon-containing HindIII fragments detected by dystrophin cDNA. One breakpoint lies between exon-containing HindIII fragments 7 and 8, five breakpoints between exon-containing HindIII fragments 31 to 41, and one lies close to exon-containing-HindIII fragment 50. The distribution of these and of a further seven translocation breakpoints whose positions are known is compared with that reported for deletions and duplications in affected males.


Identification of a nonsense mutation in the amelogenin gene (AMELX) in a family with X-linked amelogenesis imperfecta (AIH1). A family with X-linked amelogenesis imperfecta (XAI) is described in which the disease is associated with a nonsense mutation in exon 5 of the amelogenin gene. This mutation involves a single base deletion (CCCC-->CCC) in the exon in an affected male, his sister and his mother. The effect of this deletion is to alter the reading frame and to introduce an inappropriate TGA stop codon (an opal mutation) into the exonic sequence of the amelogenin gene immediately 3' of the mutation. The clinical features in the examined members of this family indicate that, in some individuals, the most noticeable defect is of enamel hypoplasia. In others, the hypoplastic changes are subtle and might have been overlooked on cursory examination; the most noticeable change is of enamel colour, indicating a degree of hypomineralisation. We propose that the amelogenin gene is implicated in both the formation of enamel of normal thickness and in the normal mineralisation process.


Molecular characterization of beta-thalassemia in Azerbaijan. We have analyzed the beta-thalassemia mutations in 99 chromosomes of 49 adults with beta-thalassemia major and of one with Hb S-beta-thalassemia, who are regular patients at a large hematology clinic in Bakü, Azerbaijan. A total of 20 different mutants were identified; three [frameshift at codon 8 (-AA); IVS-II-I (G-->A); IVS-I-110 (G-->A)] were present in about two-thirds of all chromosomes. Most alleles are the same as found in Mediterranean populations; a few have an Asian origin or come from Kurdistan, Lebanon, Saudi Arabia, or a black population. One mutant [frameshift at codons 82/83 (-G)] might be specific for the Azerbaijanian population. Nearly all patients were transfused, which made quantitation of Hb F impossible; high G gamma values were present in the Hb F of those patients whose beta-thalassemia chromosome carried the C-->T mutation at position -158 in the promoter of the G gamma-globin gene.


Alport syndrome: a genetic study of 31 families. Thirty one families with Alport syndrome including 3 families with associated syndromes were studied. The location of the COL4A5 gene, responsible for the Alport syndrome, was determined by linkage analysis with eight probes of the Xq arm and by a radiation hybrid panel. Concordant data indicated the localization of the Alport gene between DXS17 and DXS11. Four deletions and one single base mutation of the COL4A5 gene were detected. Homogeneity tests failed to show any evidence of genetic heterogeneity superimposed on clinical heterogeneity for ophthalmic signs and end-stage renal disease age.


New chromosome 21 DNA markers isolated by pulsed field gel electrophoresis from an ETS2-containing Down syndrome chromosomal region. To generate new chromosome 21 markers in a region that is critical for the pathogenesis of Down syndrome (D21S55-MX1), we used pulsed field gel electrophoresis (PFGE) to isolate a 600-kb NruI DNA fragment from the WA17 hybrid cell line, which has retained chromosome 21 as the only human material. This fragment, which contains the oncogene ETS2, was used to construct a partial genomic library. Among the 14 unique sequences that were isolated, 3 were polymorphic markers and contained sequences that are conserved in mammals. Five of these markers mapped on the ETS2-containing NruI fragment and allowed us to define an 800-kb high-resolution PFGE map.


Chromosomal assignment and linkage analysis of the human glutathione S-transferase mu gene (GSTM1) using intron specific polymerase chain reaction. Oligonucleotide primers specific for intron 5 sequences were used to amplify a unique 718 bp fragment in the human GST mu gene. Using DNA from a panel of somatic cell hybrids it was possible to confirm the assignment of the GST1 locus to chromosome 1p and to refine localisation to 1p13 using Southern blot analysis of DNA from three-generation CEPH families and a GST mu specific DNA probe.


A single base pair polymorphism in the WT1 gene detected by single-strand conformation polymorphism analysis. The Wilms' tumor predisposition gene, WT1, was analysed exon-by-exon in a variety of tumours using the single-strand conformation polymorphism (SSCP) technique. A consistent variation in the usual band pattern for exon 7 was detected in this survey. On sequencing, a silent mutation was noted in codon 313 resulting in an A-->G transition in an arginine codon. The A-->G transition destroys an AflIII restriction enzyme recognition site, which provides a rapid means of identifying heterozygotes at this locus. Analysis of the segregation of this polymorphism in families demonstrated a co-dominant inheritance pattern. In an analysis of 21 randomly selected individuals 25% were heterozygous at this locus, which makes this polymorphism useful in a variety of genetic analyses.


Molecular characterization of a 17q11.2 translocation in a malignant schwannoma cell line. Malignant schwannomas are soft-tissue neoplasms that occur at increased frequency with germline alterations of the neurofibromatosis-1 (NF1) gene at 17q11.2. We report molecular and cytogenetic characterization of a malignant schwannoma cell line established from an individual affected with NF1. This cell line has a complex hyperdiploid karyotype with two cytogenetically identical der(13)t(13;17)(p11,q11.2) chromosomes. Using somatic cell hybrids, we mapped twelve chromosome-17 probes to either the der(13)t(13;17) chromosome or a small der(17) chromosome. Two chromosome-17p loci, including the p53 tumor suppressor gene, were present in the schwannoma cell line, but did not map to either of these chromosomes. Loss of heterozygosity studies indicated that the two der(13)t(13;17) chromosomes arose by duplication, presumably after the translocation event. The 17q11.2 translocation break-point maps distal to the NF1 gene, and may not disrupt its functioning. Although NF1 mRNA was detected in this cell line by polymerase chain reaction, Northern blot analysis revealed very little or none of the 13-kb mature NF1 transcript. This suggests that the single remaining allele of the NF1 gene contains a mutation that results in either greatly reduced transcription or message instability.


Genetic studies of antithrombin III with IEF and ASO hybridization. Antithrombin III (AT III) was analyzed by two different methods. Isoelectric focusing was used to screen 3 different populations (southwest Germans, Portuguese, Xavante Indians). The same variant was detected both in the German and the Portuguese populations with frequencies of 0.007 and 0.00024, respectively. Further characterization of this variant was performed by allele specific oligonucleotides. By this means, it was possible to identify the variant as AT III Dublin, originally found in 4 Irish families.


A very conservative region of ApoB-100 in the putative binding region to the LDL receptor in the Toulouse population. The nucleotide sequence of the putative binding site of ApoB-100 was studied in Hypercholesterolemic IIa patients and controls from the Toulouse area. Only one patient possesses the 3,500 mutation, which is responsible for defective familial hypercholesterolemia. The other individuals (including 39 patients and 14 controls) display the same nucleotide sequence although four nucleotide substitutions have been described in this region. This homogeneity of the Toulouse population in the putative binding site of ApoB-100 is discussed.


Analysis of 30 known cystic fibrosis mutations: 10 mutations account for 27% of non-delta F508 chromosomes in southern France. We have analyzed 131 unrelated families from Southern France for 29 known cystic fibrosis (CF) mutations identified in 8 exons of the cystic fibrosis transmembrane regulator gene. All these mutations were detected by amplification of DNA by the polymerase chain reaction (PCR) followed by restriction enzyme digestion or hybridization with allele specific oligoprobes. The most frequent mutations after the delta F508 deletion (frequency: 63%) were G542X (5.3%), delta I507 (1.1%), and N1303K (0.76%). Seven other mutations (621 + 1G --> T, Y122X, R347P, R334W, S549N, G551D, R1162X) were each identified in only one CF chromosome. Apart from G542X, most of the other mutations identified in this study were found to be associated with 7-(GATT)-repeats allele of IVS6A. In Southern France, only 73% of CF chromosomes could be identified by the analysis of 30 mutations.


Aplasia cutis congenita reminiscent of the lines of Blaschko. A male newborn showing congenital symmetrical abdominal skin defects and an alopecia on the scalp following a spiral pattern is described. The pattern of distribution of both skin anomalies was reminiscent of the lines of Blaschko, indicating that somatic mosaicism is the most probable cause for the defects.


Role of rapid imprint cytology in the diagnosis of skin cancer and assessment of adequacy of excision. Imprint cytotechnique was employed in 20 cases of maligant skin tumours (11 squamous cell carcinoma, 4 basal cell carcinoma and 5 malignant melanoma) to evaluate the reliability of the technique by comparing the results with histologic diagnosis. In ten cases margins of the excised tumours were also subjected to imprint and histopathologic studies to assess the clearance of malignancy. All the tumours were correctly diagnosed in imprint smears. Similarly 100% cytohistopathologic correlation was also obtained in the assessment of excisional margins of the tumours. The technique of imprint cytology may be employed for quick diagnosis of skin cancers and in assessment of clearance of surgical field during surgery.


Cytological evaluation of conjunctival scrape smears in cases of conjunctivitis. The present study was conducted on 130 cases of untreated conjunctivitis and 25 control cases to assess the diagnostic value of cytology. Conjunctival scrapings from all cases were stained with Giemsa and Papanicoloau's stain and categorized cytologically and later correlated with the clinical profile. Normal cytologic profile was obtained in 7 cases (5.4%) of the study group and 14 cases (56%) of the control group. Cytologic diagnosis of trachoma was made in 63 cases (48.5%) including 48 out of 51 clinically diagnosed cases of trachoma, 9 cases of allergic conjunctivitis and 6 cases of acute follicular conjunctivitis, positive clinico cytologic correlation being 76.2%. Mucopurulent conjunctivitis was diagnosed in 24 cases (18.5%) both clinically as well as by cytological technique. Viral conjunctivitis was diagnosed in 24 cases (18.5%) including 19 cases (14.6%) of clinically diagnosed viral conjunctivitis and 5 cases (3.9%) of acute follicular conjunctivitis, positive correlation being 79.2%. Only 2 cases (1.5%) out of 15 clinically diagnosed cases of allergic conjunctivitis were confirmed cytologically. In all the 4 cases (3.1%) of spring catarrh and 6 cases (4.6%) of phlyctenular conjunctivitis the cytologic features were found to be consistent with the clinical diagnosis.


Vaginitis in non pregnant women in Haryana. Study was carried out in 100 patients of non-specific vaginitis (NSV) to find out the incidence of vaginitis due to G. vaginalis. Out of a total of 100 subjects 20 were positive for G. vaginalis as compared to only 6 in equal number of normal matched controls. One positive specimen showed concomitant presence of C. albicans and E. coli was found in another positive specimen. Presence of amines and clue cells in the discharge did not correlate with the isolation rate of G. vaginalis, thus emphasizing the necessity of culture to diagnose NSV due to G. vaginalis.


A delayed permeability factor in the culture filtrates and cell lysates of Salmonella weltevreden. Salmonella weltevreden strains produced a delayed permeability factor (PF) when tested on depilated rabbit skin. The PF activity could be demonstrated in freshly concentrated culture filtrates as well as in the cell lysates. The activity varied with strain and preparation. The induration and blueing reactions were associated with well marked balancing zones.


Salmonellosis in Goa.

Salmonellosis in Goa. During the period 1982-86, a total of 657 Salmonella strains were isolated from various clinical samples processed in the Microbiology laboratory of Goa Medical College, Bambolim, Goa. The strains were distributed amongst 23 different Salmonella serotypes. The commonest serotypes encountered were S.typhimurium (66%) and S.typhi (24%), the other serotypes were S.bareilly (5.4%), S.paratyphi B (1.2%), S.newport (1.2%) and S.chester (0.8%). Stool samples yielded the maximum Salmonella isolates of which the S.typhimurium was the highest followed by S.bareilly.


Immunoperoxidase localization of fibronectin in small bowel mucosa. An indirect immunoperoxidase technique was employed to demonstrate fibronectin in cryostat sections of small bowel mucosa. Prior exposure of the sections to a solution of pepsin (4 mg/ml) was not essential to localize antigenicity of fibronectin immunohistologically.


Solitary rectal ulcer syndrome and colitis cystica profunda--a clinico-pathological review. Twenty cases of solitary rectal ulcer syndrome (SRUS) and three cases of colitis cystica profunda (CCP) diagnosed between 1985 to 1990 were studied retrospectively. Clinical features, sigmoidoscopic findings and histopathology of the above lesions were reviewed. Haematoxylin and Eosin, Masson's Trichome, and high iron diamine Alcian blue staining was done in all the cases. Histopathologic examination helps in diagnosing the benign condition of the rectum viz. SRUS and CCP which are considered malignant clinically. Since an overlap of histopathological features were seen in SRUS and CCP, both can be considered as one entity, which has been highlighted in our study. Fibromuscular obliteration of lamina propria is the hallmark of the lesion.


Mechanical aids in the prevention of dental diseases in the elderly. Dental practitioners, who are often unaccustomed to treating geriatric patients, should be taught to accept that old people do not necessarily respond to optimal dental treatment as younger patients do. There is an evident need for continuing education in this respect. The many plaque removing mechanical aids available, such as toothbrushes, toothpicks, and dental flosses, have not been studied in the elderly. Since manual dexterity decreases with increasing age, the use of electric tooth cleaning devices and other aids for improving oral hygiene should be encouraged among the elderly. This is particularly so in patients with physical or mental handicaps. Future studies should investigate the benefits of preventive dental procedures in the elderly and to survey their knowledge, attitudes and behaviour related to oral health. Maintaining proper oral hygiene among the institutionalised elderly has been neglected in many cases. Nurses and other staff in institutions need more information about the role of optimal oral health in the patient's general health and well-being. Staff also need to know more specifically how to help the patients in their daily oral hygiene and how to take care of the patient's dentures. The recently discovered association of poor oral health with life-threatening vascular diseases and other medical catastrophes further emphasizes the importance of maintaining good oral hygiene. Diseases of the mouth and the teeth must be diagnosed and treated in the elderly, who are just as entitled to receive individually designed preventive dental care as are the younger generations.


Attitudes and values concerning oral health and utilisation of services among the elderly. Thus, attitudes to oral health and dental utilisation patterns of older adults show great variation and it seems the level of oral health care an individual will seek and accept will depend on their individual: age and their personal experience with dentists, past and present socio-demographic environment, number of remaining teeth, level of education achieved, expectations of family and/or significant others, level of discomfort experienced either with the dental condition or with past dental care, economic ability to pay for care, level of health or functional dependency, level of cognitive impairment, ability to reach dental services which includes distribution of dentists and geographic isolation, the philosophy of the dentists available to care for the individual.


Intravasal injection of formed-in-place silicone rubber as a method of vas occlusion. This report describes the procedure for percutaneous injection of silicone to form plugs in the vas deferens. The injection of 0.1-0.16 ml Chinese-made silicone into 14 men achieved occlusion of a 1-cm length of the vas. Sperm concentrations declined within 1 month of the operation and azoospermia was achieved in all men by 9 months.


Recovery of fertility after removal of polyurethane plugs from the human vas deferens occluded for up to 5 years. The present study reports the outcome of operations to remove MPU plugs from 130 men who had had occlusions of the vas deferens for between 0.5 and 5 years. The female partners of all the men achieved a pregnancy over a period of 0.5-4 years after the reversal operation.


Safety and efficacy of percutaneous injection of polyurethane elastomer (MPU) plugs for vas occlusion in man. This report describes the safety and efficacy of the procedure for percutaneous injection of medical-grade polyurethane elastomer (MPU) to form plugs in the vas deferens. The injection of 0.16-0.22 ml MPU in 53 men resulted in occlusion and azoospermia in 85% of the men after 12 months; 96% achieved azoospermia by 2 years. The success rate of the method and the rate of sperm suppression to azoospermia depended on the shapes of the plugs; this was determined by palpation after insertion. There were few complications and the results are discussed in terms of the reversibility potential of this method.


Semen analysis and fertility prognosis in andrological patients. Semen analyses of 529 men who consulted our department due to infertility problems, were related to the time period prior to conception, with factors adversely affecting the fertility of the female partner taken into consideration. The statistical method used was Cox's proportional-hazard model of regression. Untransformed, logarithmically transformed and dichotomized semen analysis variables were included in the calculations. The relationship between the following parameters and the probability of conception was examined: sperm count, sperm motility, progressive sperm motility, morphology and sperm motility remaining 24 h after ejaculation. All variables co-varied with the probability of conception; however, the exact type of relationship could not be determined by regression analyses. Cox's model assumes an exponential relationship. Our data suggest that this assumption is not suitable for fertility investigations. Using conventionally defined limiting values for normal and pathological semen quality, statistical analysis yielded significant differences in fertility between both categories for all of the variables considered; in the stepwise regression analysis, however, it could be shown that progressive motility and morphology alone were sufficient to discriminate between normal and pathological semen quality. The results are interpreted as indicating that, as a result of semen analysis, it is possible to predict the individual probability of conception if the exact shape of the relationship can be determined, which, up to now, has not been accomplished.


Subnormal sperm parameters in conventional semen analysis are associated with discrepancies between fertilization and pregnancy rates in in-vitro fertilization and embryo transfer. Three hundred and twenty-eight consecutive treatment cycles in 168 couples were analysed retrospectively in order to examine the influence of conventional semen analysis results on the outcome of in-vitro fertilization and embryo transfer with respect to the occurrence of both fertilizations and pregnancies. All treatments were performed under maximally standardized and controlled conditions. Each of the three main determinants of the spermiogram, namely the concentration, motility and morphology of sperm in seminal plasma, was of significant importance for fertilization and subsequent pregnancy. Best correlations were achieved by counting the number of progressively (a+b) motile sperm and the number of normally formed sperm in seminal plasma. The pregnancy rate was reduced significantly in cases in which the sperm concentration was < 10 x 10(6) ml-1 (P < 0.01), or in which there was < 40% progressively motile sperm (P < 0.001), or < 30% normally formed sperm (P < 0.001). If more than one parameter in the spermiogram was abnormal, the fertilization rate depended mainly on the most disturbed sperm parameter. The implantation rate as well as the pregnancy rate was reduced significantly in patients with low progressive sperm motility and normal morphology rates. The difference could only be attributed partially to the lower number of embryos replaced. In conclusion, subnormal sperm quality seems to interfere with developmental stages beyond the process of fertilization.


Migration sedimentation technique as a predictive test for the fertilizing capacity of spermatozoa in an in-vitro fertilization programme. The migration-sedimentation technique (MST) has been proposed as a means of separating high quality motile spermatozoa. The present study was conducted in order to evaluate whether sperm performance following separation by MST predicts their fertilizing capacity in an in-vitro fertilization (IVF) programme. Ninety semen specimens were analysed for use in an IVF-embryo transfer (ET) programme. Each specimens was divided into two parts: one was processed in the IVF programme and was used after sperm swim-up separation for insemination of human ova. The other aliquot (0.2 ml) was separated by MST, and the sperm then characterized by their concentration, motility, degree of motility and morphology. Sperm characteristics after separation by MST were then correlated with the results of the IVF-fertilization rates. In 79 of 90 IVF-ET cycles, at least one oocyte was fertilized. All post-MST sperm characteristics were significantly higher in cycles with fertilizations compared to IVF cycles without fertilization. A larger percentage of the total motile spermatozoa were recovered after MST in semen specimens with fertilization, compared to semen specimens without fertilization (39.9 +/- 3.6 and 20.6 +/- 6.6%, respectively; P < 0.05). This value was correlated with the percentage of fertilized oocytes (r = 0.24; P < 0.02). More IVF cycles with fertilizations were recorded in cases in which the recovery of motile sperm was > 25% (P < 0.005), or when more than 1.5 x 10(6) motile spermatozoa were recovered after MST (P < 0.0001). As sperm characteristics after MST correlated significantly with their fertilizing capacity, the MST test could be used in evaluation of the fertilizing capacity of spermatozoa.


The effects of barometric pressure according to Paul Bert: the question today. The scientific activity of Paul Bert was very diverse, but his main achievements concern the effects of barometric pressure upon life. The fundamental physiological effect of decreasing barometric pressure is due to the concomitant fall of the O2 partial pressure. The effects of lowering or raising the barometric pressure can be countered by increasing or decreasing the O2 fraction in the air. Extreme hyperoxia modifies cellular metabolism of all living beings: this is O2 poisoning, the Paul Bert effect. Rapid decompressions from several atmospheres, or even from sea level to high altitude, can entail the formation of bubbles of N2 dissolved under the high pressure in the tissues and blood. Decompression accidents may be prevented by decompressing slowly. Immediate recompression is the only way to overcome decompression accidents, as the N2 is forced back into solution. These main discoveries were not universally accepted before about 1915. However, since Paul Bert's time, some additional effects of changes of the barometric pressure, for example related to the variation of gas diffusivity and density, have been pointed out. It is also clear that some factors other than low barometric pressure, for instance radiation, temperature, humidity etc. may play important roles in the mechanism of mountain sickness. However, it remains that the main factor is hypoxia, since oxygen inhalation or recompression lead to a quick recovery.


Nutritional aspects of health and performance at lowland and altitude. One of the most important nutritional goals amongst athletes is to maintain adequate energy and fluid balance, since these are subject to relatively rapid changes and are directly related to performance and health. This may especially be the case when exercise intensity is high. Furthermore, when due to exercise and environmental stress food and fluid intake become depressed. In such conditions there may be a dramatic increase in the utilization of carbohydrate (CHO), fluid, and in some instances protein. These increased requirements may then not be covered. Insufficient replacement of CHO may lead to hypoglycemia, altered protein metabolism, central fatigue and exhaustion. Large sweat losses may pose a risk to health by inducing severe dehydration, impaired blood circulation and heat transfer, leading to heat exhaustion and collapse. Inadequate CHO and protein intake leads to a negative nitrogen balance, which over the long term will lead to a loss of muscle mass. In the scope of this presentation we will refer to the most important nutritional factors which are known to affect performance over a short term, at sea level and altitude.


Energy sources for muscular exercise.

Energy sources for muscular exercise. The basic energy yielding mechanisms of muscle contraction are reviewed and the main structural and functional features of human muscle are compared with those of some common athletic animal species. Sex and age related muscle power (alactic) characteristics are examined in both sedentary and athletic subjects. Recent measurements of the kinetics of contraction of the O2 debt by NMR spectroscopy by the human plantar flexors are shown. The main features of anaerobic (lactic) exercise in untrained and trained subjects, as a function of sex, age and environmental conditions (high altitude), are described with particular emphasis on the so-called lactic anaerobic threshold. With regard to aerobic exercise, the main determinants of O2 transport to the tissues are reviewed and an update of the factors limiting human performance is made. The possible causes of arterial O2 desaturation in athletes, both at sea level and at altitude, are discussed. A comparative analysis between man and woman of the progress of the records of some typical competitions is made and possible implications are discussed. The potential role of some commonly used physiological and/or paraphysiological procedures for improving the performance is analyzed.


Amino acid metabolism, muscular fatigue and muscle wasting. Speculations on adaptations at high altitude. Recent investigations from our and other laboratories indicate that glycogen is a carbon-chain precursor in muscle for the synthesis of TCA cycle intermediates and glutamine. During intense exercise and in conditions of a relative lack of energy (hypoxia, trauma, sepsis) the metabolism of branched-chain amino acids (BCAA) is accelerated in muscle. In the primary BCAA aminotransferase reaction 2-oxoglutarate is used as amino-group acceptor (putting a carbon-drain on the TCA cycle) under formation of glutamate. Glutamate will subsequently react with ammonia, generated in the AMP deaminase reaction or by deamination of amino acids, under formation of glutamine in a reaction catalysed by glutamine synthetase (glutamate + ammonia + ATP--> glutamine + ADP). Muscle glycogen stores may be smaller or less available at high altitude. It is hypothesized that this will lead to premature fatigue (due to both a lack of fuel and of TCA cycle carbon-precursor) and to a reduction in the synthesis rate of glutamine. A chronic reduction in the synthesis rate of glutamine during a long term stay at high altitude on its turn may lead to gut atrophy, bacterial translocation, endotoxemia, muscle protein catabolism and a weakened immune status.


Role of lipids on endurance capacity in man. A man whose weight is near 70 kg has approximately 15 kg of fat as triglycerides in adipose tissue, representing about 140,000 kcal. With such a quantity of stored fat, the question is to know why triglycerides are not the only fuel for exercise. Probably because this fuel cannot sustain maximal rates of exercise. The ability to sustain maximal exercise is dependent on carbohydrate use. The reason for the limited rate at which energy can be derived from fat store is not clear. We can examine successively: 1) The rate of release from adipose tissue. Hydrolysis of the adipose tissue triglyceride is regulated by hormonal and nervous influence. It has recently been shown that 70% of fatty acids released from adipose tissue at rest are reesterified. This value decreases to 25% at the onset of submaximal exercise at 40% of VO2max. One part of the increase in fat oxidation could therefore result from the reduced reesterification. 2) The capacity of transport and muscle extraction. A close correlation has been shown between the increase in FFA concentration and FFA uptake during increased energy expenditure under the effect of exercise. Exercise increases lipoprotein lipase (LPL) activity in muscle. This causes increase in muscle and cardiac FFA uptake and a decrease in LPL activity in adipose tissue. The control of this enzyme is coordinated by hormonal mechanisms resulting from the reduction of insulin and the increase in catecholamines induced by exercise.(ABSTRACT TRUNCATED AT 250 WORDS)


Enzyme mechanisms for pyruvate-to-lactate flux attenuation: a study of Sherpas, Quechuas, and hummingbirds. During incremental exercise to fatigue under hypobaric hypoxia, Andean Quechua natives form and accumulate less plasma lactate than do lowlanders under similar conditions. This phenomenon of low lactate accumulation despite hypobaric hypoxia, first discovered some half century ago, is known in Quechuas to be largely unaffected by acute exposure to hypoxia or by acclimatization to sea level conditions. Earlier Nuclear Magnetic Resonance (NMR) spectroscopy and metabolic biochemistry studies suggest that closer coupling of energy demand and energy supply in Quechuas allows given changes in work rate with relatively modest changes in muscle adenylate and phosphagen concentrations, thus tempering the activation of glycolytic flux to pyruvate--a coarse control mechanism operating at the level of overall pathway flux. Later studies of enzyme activities in skeletal muscles of Quechuas and of Sherpas have identified a finely-tuned control mechanism which by adaptive modifications of a few key enzymes apparently serves to specifically attenuate pyruvate flux to lactate.


Exogenous substrate oxidation during exercise: studies using isotopic labelling. This presentation summarizes the experimental data on the oxidation of exogenous substrates using isotopic labelling: glucose, fructose, maltodextrins, glucose polymers, starch and FFA. The two main determining factors for the oxidation of exogenous substrates are in this order: power output and amount of ingested substrates. The largest oxidation of exogenous substrate is observed for glucose, maltodextrins, Polycose, and starch. For exercises of one hour duration or more, the average rate of oxidation of these compounds can reach up to 0.5 g/min, which agrees with the indirect estimation of Coyle et al. Fructose is oxidized at a lower rate, except when it is taken before the exercise period. FFA are only oxidized to a small extent.


Carbohydrate feeding during exercise.

Carbohydrate feeding during exercise. During strenuous exercise (i.e. 70% maximal O2 consumption) there is a progressive shift from muscle glycogen to blood glucose oxidation with increasing duration of exercise. By maintaining blood glucose concentration and the rate of carbohydrate oxidation necessary to exercise strenuously, carbohydrate consumption throughout exercise delays fatigue by 30-60 min in endurance-trained subjects. This requires exogenous glucose supplementation at rates in excess of 1 gram/min (i.e., 16 mg/kg/min) as evidenced by the observation that intravenous glucose infusion at this rate is required to maintain blood glucose at 5 mM. Exogenous glucose must be infused at a rate of 2.6 gram/min (i.e., 37 mg/kg/min), which is similar to the total rate of carbohydrate oxidation, in order to maintain blood glucose at 10 mM after 2 h of exercise. However, carbohydrate supplementation during intense exercise does not spare muscle glycogen utilization in people. This suggests that over the course of 2-4 hours of exercise at 70% VO2max, muscle glycogen and blood glucose contribute equally to total carbohydrate oxidation. Furthermore, during the latter stages of prolonged exercise, exogenous blood glucose supplementation may be capable of supplying almost all of the carbohydrate requirements of exercise at intensities up to 70% VO2max.


Nutrition and high altitude exposure.

Nutrition and high altitude exposure. Altitude exposure leads to considerable weight loss. The different hypotheses that have been put forward to explain this phenomenon are discussed reviewing the literature: 1) a primary decrease of food intake due to loss of appetite caused, directly or indirectly, by hypoxia, changes of menus, comfort and habits, 2) a discrepancy between energy intake and energy expenditure due to an increased basal metabolic rate and/or high levels of activity which are not matched by an increased food intake, 3) a loss of body water due to increased insensible loss through increased ventilation in the mountain environment, decreased liquid intake, and/or changes in water metabolism, 4) an impaired absorption of nutrients from the gastrointestinal tract, and 5) a loss of muscle mass due to lack of physical exercise and/or direct effects of hypoxia on protein synthesis. It is concluded that altitude weight loss is due to an initial loss of water and subsequently to loss of fat mass and muscle wasting. Up to altitudes around 5000 m the weight loss from fat and muscle seems to be largely avoidable by maintaining adequate intake in a comfortable setting. Primary anorexia, lack of comfort and palatable food, detraining, and possible direct effects of hypoxia on protein metabolism seem to inevitably lead to weight loss during longer exposures at higher altitudes. In order to minimize losses it is advisable to acclimatize properly, to reduce the length of stay at extreme altitude as much as possible and to maintain a high and varied nutrient intake.


Oxygen transport and cardiovascular function at extreme altitude: lessons from Operation Everest II. Operation Everest II was designed to examine the physiological responses to gradual decompression simulating an ascent of Mt Everest (8,848 m) to an inspired PO2 of 43 mmHg. The principal studies conducted were cardiovascular, respiratory, muscular-skeletal and metabolic responses to exercise. Eight healthy males aged 21-31 years began the "ascent" and six successfully reached the "summit", where their resting arterial blood gases were PO2 = 30 mmHg and PCO2 = 11 mmHg, pH = 7.56. Their maximal oxygen uptake decreased from 3.98 +/- 0.2 L/min at sea level to 1.17 +/- 0.08 L/min at PIO2 43 mmHg. The principal factors responsible for oxygen transport from the atmosphere to tissues were (1) Alveolar ventilation--a four fold increase. (2) Diffusion from the alveolus to end capillary blood--unchanged. (3) Cardiac function (assessed by hemodynamics, echocardiography and electrocardiography)--normal--although maximum cardiac output and heart rate were reduced. (4) Oxygen extraction--maximal with PvO2 14.8 +/- 1 mmHg. With increasing altitude maximal blood and muscle lactate progressively declined although at any submaximal intensity blood and muscle lactate was higher at higher altitudes.


Fluid balance and exercise.

Fluid balance and exercise. The rate of metabolic heat production during prolonged exercise may be increased to 15-20 times that at rest. Evaporation of sweat secreted onto the skin can effectively limit the rise in body temperature which would otherwise occur, but results in the loss of water and electrolytes from the body. Dehydration and an increased thermal load can accelerate the onset of fatigue during exercise. The available evidence supports the idea that ingestion of fluids during prolonged exercise can improve performance. Heart rate and rectal temperature will generally be lower, and plasma volume will be better maintained when fluids are given. There is, however, no general agreement on the optimum formulation nor on the frequency or volume of drinking that is most appropriate. In practice, the ideal solution will depend on a number of factors, including the duration and intensity of the exercise, the environmental conditions and the characteristics of the individual. The variation between individuals is, however, large and the optimum strategy can only be established by subjective experience.


Peptides and exercise at high and low altitudes. Some peptides are released with stress. We therefore examined effects of different exercise stress at low and moderate altitudes and after heat stress on beta-endorphin and endothelin in the human circulation. We also assessed longitudinally the effects of chronic exertion on beta-endorphin and the relationship to melatonin secretion in well-trained athletes. All peptides and melatonin increased after exercise, but the magnitude of this increase was age-dependent. Chronic exertion is associated with a decrease in exercise induced opioid release and in such individuals melatonin secretion is not beta-endorphin related. Long term high altitude exposure is associated with high-beta-endorphin levels at rest. Atrial natriuretic factor and vasopressin is also released with exercise at moderate altitude. Endothelin, a powerful vasoconstrictor, is increased independent of type of exercise, duration and moderate hypoxia.


Exercise and neuromodulators: choline and acetylcholine in marathon runners. Certain neurotransmitters (i.e., acetylcholine, catecholamines, and serotonin) are formed from dietary constituents (i.e., choline, tyrosine and tryptophan). Changing the consumption of these precursors alters release of their respective neurotransmitter products. The neurotransmitter acetylcholine is released from the neuromuscular junction and from brain. It is formed from choline, a common constituent in fish, liver, and eggs. Choline is also incorporated into cell membranes; membranes may likewise serve as an alternative choline source for acetylcholine synthesis. In trained athletes, running a 26 km marathon reduced plasma choline by approximately 40%, from 14.1 to 8.4 uM. Changes of similar magnitude have been shown to reduce acetylcholine release from the neuromuscular junction in vivo. Thus, the reductions in plasma choline associated with strenuous exercise may reduce acetylcholine release, and could thereby affect endurance or performance.


Magnetic resonance spectroscopy and imaging of muscle--a physiological approach. Magnetic resonance spectroscopy (MRS) and imaging (MRI) are now well established techniques for the study of cellular metabolism and gross structure of muscle. Using non-ferrous materials, we have constructed a system for the measurement of isometric force of quadriceps in response to percutaneous electrical stimulation and voluntary effort within the bore of a 48 cm diameter 1.5 T General Electric SIGNA whole body MR system. Using this system we have been able to study the relationship between electromechanical coupling and chemistry of muscle, with 31P MRS for the measurement of high-energy phosphates and pH, during electrically stimulated activity. Image analysis using the Context Vision system enables a distinction to be made, in 1H MRI by T1/T2 mapping, of muscle, fat and connective tissue to give force per unit cross sectional area of muscle. The combination of MR and functional measurements provide a valuable tool for further detailed analysis of human muscle weakness and fatigue.


Measuring exercise-induced adaptations and injury with magnetic resonance spectroscopy. We compared the metabolic capacity of calf muscles in young normal subjects who performed endurance training to highly trained track athletes, older subjects, and subjects with several metabolic diseases. Metabolic capacity was measured as the rate of phosphocreatine (PCr) recovery following submaximal exercise. PCr levels were measured using magnetic resonance spectroscopy (MRS). Exercise consisted of repeated plantar flexion against resistance. MRS calculated metabolic capacity agreed well with rates from muscle biopsies. Short term endurance training resulted in a 14% increase in metabolic capacity. This adaptation was small compared to the metabolic capacities of endurance athletes (70% greater than control subjects), and changes due to aging (20% and 55% declines by 66 and 80 years of age, respectively). Exercise training is also associated with muscle injury. Muscle injury was seen as a transient elevation of Pi/PCr at rest in response to an acute bout of exercise. The elevation of resting Pi/PCr persisted during continued training. Metabolic capacity as measured by the rate of phosphocreatine recovery increased with endurance training and decreased with normal aging and metabolic disease. Small levels of persistent muscle injury is a natural by product of strenuous endurance training.


Muscle bioenergetics in skiers: studies using NMR spectroscopy. Sedentary human subjects (n = 6) and two homogeneous groups of athletes, trained for down-hill skiing (n = 5) and cross-country skiing (n = 7), were subjected to cardiorespiratory testing and to evaluation of the bioenergetics of calf muscles by means of Phosphorus Nuclear Magnetic Resonance Spectroscopy. The exercise consisted of successive plantar flexions performed at graded fractions of the maximal voluntary contraction force. It appears from this study that the decrease in phosphocreatine level induced by exercise at 80% of maximal voluntary contraction, was smaller in the muscles of athletes who trained for cross-country skiing, than in the muscles of down-hill skiers and control subjects. Intracellular acidosis was virtually absent in cross-country athletes. The rate of restitution of phosphocreatine, after the exercise, was higher in both groups of skiers, compared to sedentary subjects. The maximal oxygen consumption and the maximal alactic power were higher in athletes than in sedentary subjects. NMR data and mechanical measurements are used in consideration with functional systemic indexes to characterize the capabilities of skiers.


Myoelectrical and metabolic changes in muscle fatigue. In isometric contraction-induced fatigue force loss has been related to mostly myoelectrical or intramuscular events. However, some factors potentially involved may interfere at more than one site in these events and it has proven difficult to distinguish between those influences. The study of the relationships between force generating capacity, the metabolic state of a muscle and its myoelectrical properties may therefore help broaden our understanding of the fatigue process. In order to investigate these relationships, we have evaluated changes in force-generating capacity, NMR-determined metabolic variables, and myoelectrical activity, as measured from surface EMG, simultaneously in brachial biceps muscle of healthy subjects, during different types of fatiguing isometric exercise and during recovery. Factors studied include intramuscular pH, inorganic phosphate and its diprotonated form concentrations, root-mean square and mean power frequency of the EMG power spectrum, and neuromuscular efficiency index. Results show that different mechanisms are likely to contribute to force loss in fatiguing muscle and during different phases of recovery from fatigue. Indeed, relationships between variables from the three groups differed according to exercise protocol as well as in fatiguing and recovering muscle.


Metabolic transient studies by NMR.

Metabolic transient studies by NMR. The time course of phosphocreatine (PC) hydrolysis in humans was measured by 31P-NMR spectroscopy (31P-NMRS) with a time resolution of 10.8 s in the gastrocnemius muscle and a relationship between muscle O2 consumption (VO2) and [PC] was derived from a bioenergetic model. This allowed a direct estimate of the half-time of the intracellular VO2 kinetics (t1/2 VO2) of the contracting human gastrocnemius in aerobic conditions. t1/2 VO2 was found to be approximately 16 s and independent of the work load. This value corresponds to the shortest t1/2 VO2 determined at the mouth of the subject in the absence of lactate accumulation in the rest to work transient. t1/2 VO2 may now be assessed in man at low muscle temperatures. To this aim a procedure was developed allowing corrections of the 31P-NMR spectra based on the muscle temperature profiles obtained by a simultaneously acquired proton image.


Non-invasive measurements of O2 availability in human skeletal muscle with near-infrared spectroscopy. The availability of O2 in the human vastus lateralis muscle has been investigated with non-invasive near-infrared spectroscopy (NIRS) using a commercially available unit (RunMan, NIM Inc. Philadelphia). The measuring probe placed above the skin illuminates the underlying tissue and measures the reflected light at two wavelengths (760 and 850 nm). Due to differences in the absorption spectra between HbO2 and Hb the difference in light intensity at these two wavelengths will be a relative index of tissue oxygenation. Prolonged arterial occlusion and static contraction have been studied. Arterial occlusion resulted in a decreased O2 saturation with a half-time of 2.3 +/- 0.2 min (mean +/- SE, n = 4). Restoration of blood flow resulted in a rapid tissue reoxygenation with a half-time of 24 +/- 2 s. Reoxygenation after static contraction occurred with a half time of 19-37 s. The half-time of reoxygenation subsequent to exercise and/or ischemia may be a valuable parameter in sports medicine and in the evaluation of peripheral vascular disease.


Injury to skeletal muscle during altitude training: induction and prevention. A contracting skeletal muscle will shorten, remain isometric, or lengthen depending on the interaction between external load and the force developed by the muscle. Most physical activities involve shortening, isometric and lengthening contractions. The fluctuations in terrain encountered at altitude, increase both the likelihood that lengthening contractions will occur and the severity of the stretches. When performing a given amount of work, muscles lengthened during contractions expend less energy and fatigue less rapidly than muscles that shorten. Conversely, with equal activation, displacement, and velocity, the work done on a muscle during lengthening contractions is greater than the work performed by a muscle during shortening contractions, but force decreases more rapidly during lengthening. Furthermore, muscles are more likely to be injured during lengthening contractions than during shortening or isometric contractions. The occurrence of contraction-induced injury can be eliminated, or minimized, by prior training specific for the performance of lengthening contractions.


Muscular adaptations at extreme altitude: metabolic implications during exercise. Residence at extreme altitude results in pronounced reductions in muscle mass and the cross-sectional area of the slow and fast twitch fibre types. The reductions in muscle contractile proteins appear not to be accompanied by significant alterations in the proportion of the major fibre types and consequently in the myosin heavy chain isozymes. Acclimatization to extreme altitude is also accompanied by a marked reduction in mitochondrial potential that occurs regardless of activity status. At least during mountaineering expeditions, the maximal activity of cytosolic enzymes involved in anaerobic function appear to be unaffected. In contrast, extreme hypobaric hypoxia with low exercise appears to result in loss of the activities of cytosolic enzymes. The attenuation of glycolysis during exercise accompanying acclimatization does not appear to be due to adaptations in fibre size, capillarization or mitochondrial potential. Rather, evidence from both acclimatization and training at sea level suggests that a depressed blood epinephrine concentration is involved.


Muscle structural modifications in hypoxia. The effects of prolonged severe hypoxia on human performance capacity and muscle structure and function have recently been studied during real and simulated ascents to Mt. Everest. The results of several independent research teams, using different techniques, are broadly compatible. It is found that body and muscle mass is significantly reduced after exposure to hypoxia. As a consequence, muscle fiber size is also reduced. The capillary density of muscle tissue is increased, not because of capillary neoformation, but because of the reduction in muscle fiber size. The activities of enzymes of the oxidative pathways are decreased in skeletal muscle tissue. A loss of mitochondria is the structural evidence of the diminished potential for muscle oxidative metabolism. In contrast to these results, recent experimentations with hypoxia in human exercise settings have demonstrated that if hypoxia is only present during a limited daily period of an endurance training session, hypoxia has a different effect on muscle tissue. It is found that muscle fiber size, capillarity, myoglobin concentration and muscle oxidative capacity are all enhanced with training in hypoxia. These controversial findings raise questions regarding the nature of the adaptational mechanisms triggered by the different hypoxic stimuli to which subjects had been subjected and thus offer important new venues for further studies on the control of protein metabolism in muscle tissue.


Mechanisms of adaptation to cold.

Mechanisms of adaptation to cold. The animal model used the most frequently for understanding the mechanisms of adaptation to cold in humans has been the rat. It has been established that rats kept in the cold for a few weeks stop shivering while preserving a normal internal temperature because of an enhanced thermogenic capacity of the brown adipose tissue (BAT) mediated by the sympathetic nervous system. Studies on groups of humans exposed to cold have shown that shivering is also attenuated but without compensatory increased in heat production possibly because of non-significant contribution of the BAT. However when humans and laboratory animals are exposed repeatedly to short severe cold evidence for adaptation has been described. This adaptation is not metabolic; instead it is related to the phenomenon of habituation. When exposed to a novel stress such as cold, the alarm reaction is initiated as evidenced by the activation of the sympathetic nervous system which opposes the stressing situation. However with time, when it is realized that the normal functioning of the body is not endangered the responses are attenuated and enhanced tolerance is observed. This type of adaptation was observed in Eskimos, fishermen, outdoor workers, etc.


The different types of general cold adaptation in man. Different types of general cold adaptation have been described over the last 50 years. Metabolic adaptation (Alacaluf Indians, Arctic Indians Eskimos), insulative adaptation (coastal Aborigines of tropical northern Australia), hypothermic adaptation (bushmen of the Kalahari desert, Peruvian Indians) and insulative hypothermic adaptation (Central Australian Aborigines, nomadic Lapps, Korean and Japanese diving women). These different types of cold adaptation are related to the intensity of the cold stress and to individual factors such as diet, the level of physical fitness and body fat content. Thus, in natural environments, man develops a strategy of adaptation to cold, which takes into account environmental and individual factors. This strategy is susceptible to be modified when these conditions change. Caloric intake deficit could have been responsible for the hypothermic adaptation observed after J.-L. Etienne's journey to the North Pole. Physiological responses were adapted to maintain an acceptable level of energetic reserves with a moderate hypothermia, which was not life threatening for the climatic conditions encountered by the polar explorer.


Cold, fitness and the exercise electrocardiogram. A 20 year longitudinal study of Canadian Inuit. A 20 year longitudinal study has examined fitness, lung function and exercise electrocardiograms in the Inuit of Igloolik (NWT, 69 degrees 40' N). When first examined (1969/70), an energy expenditure of up to 16 MJ/day was estimated from Kofranyi-Michaelis respirometry. Step test predictions of maximal oxygen intake were also high initially, but values declined progressively with acculturation to a sedentary lifestyle. Throughout the 20 years, right-branch bundle block (RBBB) has been somewhat more prevalent than in southern Canada. The majority of those affected have shown no more than slight R-wave notching. In 1969/70, a few of the more marked cases of RBBB may have been attributable to chronic respiratory disease, but the majority of cases have shown high normal values for both lung function and maximal oxygen intake. We thus conclude that the major cause of RBBB in this community is a ventricular hypertrophy due to the vigorous physical demands of the traditional lifestyle.


Cold exposure and ischemic heart disease. Exposure to cold causes a vasoconstriction and a tachycardia, both resulting in a rise of blood pressure and cardiac work. This last effect may have a deleterious influence on people suffering from ischaemic heart disease (IHD). Moreover, coronary artery spasm could occur if vasoconstriction extends to the heart vessels. Epidemiologic studies have shown that mortality from IHD was correlated to the ambient temperature. There will be more deaths per day in the winter, and fewer in the summer. However, the daily number of deaths also increases during the heat waves. During a cold test, the coronary blood flow remains normal or slightly increased in normal subject. There is never a coronary artery spasm. Subjects who suffer from angina but have normal coronary arteries behave in the same way as normal subjects. Patients with IHD show a decrease in coronary blood flow. In a few cases, those patients may exhibit a coronary spasm with chest pain and even myocardial infarction. It is concluded that people with normal cardiovascular function are unaffected by cold stress whereas those with IHD may be crippled, although rarely, by exposure to cold, especially if they perform a physical work.


Increased arterial pressure after acclimatization to 4300 m: possible role of norepinephrine. Both systemic arterial pressure and sympathetic activity increase at high altitude, but neither the time course of these increases nor the relationship between them are known. Examination of resting and exercising data from our prior studies at sea level and on Pikes Peak indicated that blood epinephrine concentrations either showed little change (from sea level) or rose early in altitude exposure and then declined with acclimatization. By contrast, norepinephrine concentrations in blood and urine were not increased on arrival but consistently rose later in the acclimatization process. Also with altitude exposure, arterial pressure also increased concomitantly with the increase in norepinephrine concentrations. The study designs were not adequate to establish cause and effect, but the results were consistent with the concept that arterial pressure increments at altitude were associated with increased alpha adrenergic-mediated vascular tone.


Cold and the airways.

Cold and the airways. Physiological and pathological respiratory responses are triggered by various conditions of exposure to cold climates. Beside airway smooth muscle, both the pulmonary and the tracheobronchial vasculatures are major effectors of respiratory responses to cold. General exposure to cold causes pulmonary vasoconstriction known as "Raynaud's phenomenon of the lung" in subjects with primary Raynaud syndrome and favors acute pulmonary oedema in subjects with congestive heart failure. In healthy subjects acute hyperventilation of very cold air has led to acute respiratory failure closely similar to hypoxic pulmonary oedema. In outdoor exercising people years long repetition of hyperventilation of subfreezing air causes "eskimo lung" made of obstructive lung disease and increased wall thickness of pulmonary arteries. At a lesser degree hyperventilation of dry air cools the central airways and triggers subclinical bronchial obstruction in healthy subjects. In asthmatic subjects hyperventilation of dry air causes asthma attacks. Results of recent animal and human experiments point to a key role of mucosal vessels in thermal balance of the airways. Simultaneously, there is increasing evidence that hyperventilation-induced asthma is triggered by a thermal stimulus.


Cold and muscle performance.

Cold and muscle performance. The effects of muscle temperature on the development of muscular power are discussed. Temperature influences power (both metabolic and mechanical) by means of its effects on the rate of ATP hydrolysis and/or resynthesis. One would therefore expect reduced power outputs at cold muscle temperatures in humans. However, this is not the case during submaximal aerobic exercise. In fact, no changes in metabolic power output at any given submaximal work load were found at cold muscle temperatures, despite the reduced rate of ATP resynthesis and/or splitting. To explain this, it has been postulated that the fraction of active muscle mass at any given time instant could increase in the cold, thus compensating for the reduced ATP splitting rate. This means that the aerobic ATP resynthesis in the cold may be carried out at a slower rate by a greater activated muscle mass. This compensation cannot be operational when maximal power is attained, for in this case the instantaneously activated muscle mass is constant and limited. In fact the maximal aerobic power and the maximal instantaneous anaerobic power decrease with decreasing muscle temperature, as indicated by an average Q10 of 1.4 in the physiological muscle temperature range. The reduction in maximal aerobic power in the cold may be the consequence particularly of a decrease in O2 supply associated with reduced maximal cardiac output and muscle blood flow. On the other hand, the Q10 of the maximal anaerobic power should strictly depend on the reduced rate of ATP hydrolysis. The Q10 of the latter, however, according to Arrhenius law, should be 2 to 3 instead of 1.4.(ABSTRACT TRUNCATED AT 250 WORDS)


Acute exposure to cold air and metabolic responses to exercise. Acute exposure of the whole body to cold air activates thermoregulatory mechanisms which may influence the physiological responses to exercise. Interactions between cold stress and exercise greatly depend on the intensity of cold stimulation. During exposure to moderate cold (MC) peripheral vasoconstriction shifts part of the blood from the periphery to the core, increasing the central volume and the ventricular filling. When an incremental exercise is performed in MC, the persistence of cutaneous vasoconstriction alters the cardiovascular pattern. Moreover, a delayed onset of the increase in plasma lactate concentration (LA) is found and LA remains lower for submaximum exercise intensities. Simultaneously a greater plasma norepinephrine (NA) response is observed. In addition to cutaneous vasoconstriction shivering thermogenesis occurs during exposure to severe cold (SC) which increases heat production. During incremental exercise, the oxygen consumption (VO2) and the expired minute ventilation (VE) are higher for each exercise intensity. However the ventilatory equivalent (VCO2/VO2) does not change significantly. The increased ventilatory response seems to remain a pure reaction to increasing metabolic demand. The ventilatory threshold occurs at the same exercise intensity but at a higher VO2 and VE than in warm conditions. According to the intensity of cold stress the VO2 level may be similar, increased or decreased at exhaustion. The LA is higher for light exercise intensities, lower for heavy exercise intensities and recovery. Simultaneously a greater NA was found with no change in plasma epinephrine response.


Energy metabolism during cold exposure.

Energy metabolism during cold exposure. Recent advances on the influence of cold exposure on energy metabolism in animals and humans are summarized. Although the cold-induced enhancements in carbohydrate metabolism have been the focus of numerous studies, it was only recently that pieces of evidence from animal studies have suggested that cold exposure exerts an insulin-like effect on peripheral tissue glucose uptake, which appears to proceed primarily via insulin-independent pathways. Interestingly, this phenomenon was observed in insulin-sensitive tissues of warm- a well as cold-adapted rats. Whereas previous human studies have concentrated on the cold-induced changes in basal levels of hormones and metabolic substrates, recent work from our laboratory has demonstrated that exposure to cold at rest shifts substrate utilization from mainly lipids at thermal neutrality to carbohydrates, representing the main fuel for shivering thermogenesis. Further investigation has revealed that the marked increment in carbohydrate oxidation in cold-exposed humans is derived from a greater utilization of both circulating glucose and intramuscular glycogen. With respect to lipid metabolism, recent studies have shown that the cold-induced increase in lipid oxidation in man is fuelled primarily by the fatty acids released from white adipose tissue triglycerides (TG) and possibly intramuscular TG, not plasma TG. One practical application of this work on energy metabolism in the cold resides in the pharmacological approach to improve cold tolerance, where pharmacological agents that alter energy metabolism and substrate utilization could be used to enhance cold thermogenesis and produce warmer body temperatures.


Mountain frostbite. Current trends in prognosis and treatment (from results concerning 1261 cases). From an experience of a large number (1261) of cases of mountain frostbite, an attempt is made to explain its pathophysiological mechanisms and describe the different modalities which to now allow early prognosis to be made. Laser-Doppler, microwave thermography, nuclear magnetic resonance (31P spectroscopy) and bone scintigraphy (technetium 99) are some of the investigations which deserve a special attention. Treatment is discussed, which still appears to be limited to saving viable tissue, especially for severe frostbite lesions, the only ones which pose problems. Rapid rewarming is a keystone of therapy. The role of haemodilution, vasodilators, sympathetic blockade and surgery is also discussed.


The cause of death after rescue.

The cause of death after rescue. It is recognized that some people die from hypothermia even though they are alive and uninjured when rescued. The traditional explanation is that this is due to ventricular fibrillation resulting from the afterdrop of core temperature. This hypothesis was based on inadequate measurement and failure to consider the physiology of cold. It should now be discarded. Most deaths after rescue occur through an imbalance between the active vascular capacity and the circulating fluid volume i.e. relative hypovolaemia or fluid overload. The actual mechanism in any individual case depends both on the history of the cooling and the method of rewarming used. Some deaths will however occur due to continued cooling of the body or to ventricular fibrillation precipitated by rough handling.


Field care of the hypothermic patient.

Field care of the hypothermic patient. The world literature of sports medicine and mountain medicine has been much concerned with early recognition, emergency on-site care, and rescue transportation of the cold-injured patient. Considerable problems exist for the initial rescuer and first responder, particularly if that person is alone. Thoughts of initial approach and care, are presented, particularly for the first, often untrained in-field rescue responders. The site of rescue and field variables found at that site are presented. Methods in aiding field assessment of the state of hypothermia are listed, particularly the evaluation of signs and symptoms of the victim. Early care and avoidance of further heat loss is discussed. The consideration for the rescuer (and victim) is to 'think heat'. Basic principles of care are stated, particularly for care of the victim 'with no apparent signs of life'.


Training at altitude in practice.

Training at altitude in practice. There can be little doubt that training at altitude is fundamental to preparing an athlete for competition at altitude. However the value of training at altitude for competition at sea level appears on the one hand to lack total acceptance amongst sports scientists; and on the other to hold some cloak of mystery for coaches who have yet to enjoy first hand experience. The fact is that very few endurance athletes will ignore the critical edge which altitude training affords. Each fraction of a percentage of performance advantage gained through methods which are within the rules of fair play in sport, may shift the balance between failure and achievement. Moreover, there is growing support for application of training at altitude for speed-related disciplines. This paper aims to demystify the subject by dealing with practical aspects of training at altitude. Such aspects include a checklist of what should and should not be done at altitude, when to use altitude relative to target competitions, and specific training examples.


Altitude training and muscular metabolism. To study the effects of training at moderate altitude on muscle metabolism; we defined the lowest altitude which affected the aerobic capacity in man, and we studied the differences between training at an altitude of 2300 m and at sea level, both at the same relative (to the VO2max) and absolute intensity of work. We confirmed that at 1200 m the VO2max is decreased in sedentary and well-trained persons. Elite athletes already at 900 m decrease their VO2max. We have found an increase in myoglobin, oxidative enzyme activities and endurance capacity and a decrease in some glycolytic enzyme activities associated with simulated altitude training. We conclude that when the amount of training performed at altitude is similar to the amount at sea level, the stimulus of hypoxia associated with the training stimulus induces improvements in the muscle oxidative enzymes and myoglobin.


A practical approach to altitude training: where to live and train for optimal performance enhancement. Altitude training may improve performance by a number of mechanisms. Acclimatization may improve both oxygen delivery and extraction. Hypoxic exercise may increase the training stimulus thus magnifying the effects of endurance training. Conversely, high altitude decreases VO2max and reduces the workloads at which training occurs. At altitude, base training is performed at a slower velocity and lower oxygen uptake (lower absolute workload) compared to sea level, though heart rate is similar and lactate is higher (probably greater relative workload). Interval workouts are performed at a lower absolute workload at altitude and are associated with lower peak heart rates and blood lactate concentrations. Red cell volume is increased during altitude training, as long as iron stores are normal. We suggest that for performance at altitude, acclimatization and/or hypoxic exercise is preferable; for performance at sea level, living at altitude (acclimatization) with sea level training may be the optimal strategy. However neither approach is a substitute for a carefully designed training program including appropriate rest and nutrition.


Pre-acclimatization to high altitude using exercise with normobaric hypoxic gas mixtures. Pre-acclimatization was conducted using a new method elaborated in our laboratory, combining high intensity exercise while breathing hypoxia normobaric gas mixtures. The training consisted in a daily training during three weeks, 6 days a week, two hours a day, on bicycle ergometer. Eighteen subjects aging 22.2 +/- 1.4 years (11 males, 7 females) were matched in two similar groups: one group trained in normoxic conditions (NG) while the other group (HG) trained with a progressive decrease of the fraction of inspired oxygen (from 12.2% to 10.0%). Maximal oxygen uptake (VO2max) were measured before and after the protocol period in both hypoxic (VO2max H, FIO2 = 10.4%) and normoxic (VO2max N) conditions, for the 2 groups. Training induced a similar O2max N increase in the two groups. The ratio VO2max H/VO2max N was calculated. As expected, in NG group, this ratio decreased significantly (from 63.9 +/- 4.3 to 57.5 +/- 3.1%, p < 0.01) after the training period compared to the initial value, diminution associated with an elevation of VO2max N (from 48.4 +/- 9.0 to 52.9 +/- 9.0 ml.min-1 x kg-1, p < 0.01). Conversely, in HG group, this ratio was not significantly diminished (from 61.7 +/- 3.8 to 60.5 +/- 5.2%, NS) in spite of a similar increase of VO2max N (from 47.5 +/- 5.5 to 50.7 +/- 4.9 ml.min-1 x kg-1, p < 0.01). This does not follow the diminution of the ratio usually described when VO2max N reach higher values.(ABSTRACT TRUNCATED AT 250 WORDS)


Use of a hypobaric chamber for pre-acclimatization before climbing Mount Everest. Climbing Mount Everest needs an acclimatization period of 3 to 4 weeks between 3000 and 6000 m. In order to reduce this period of time spent in dangerous conditions, an experience of pre-acclimatization was performed with 5 elite alpinists (4 male, 1 female), aged 30 +/- 4 yrs (mean +/- SD), before their attempt to climb Mount Everest. Subjects first remained one week on Mont-Blanc (between 4350 and 4807 m), then spent a total of 38 hours in a hypobaric chamber (in 4 consecutive days) from 5000 to 8500 m standard altitude. Then, they flew to Kathmandu and reached 7800 m five days only after leaving the base camp. The pre-acclimatization period showed a 12% increase in hemoglobin concentration, and no change in ventilatory response to hypoxia. Arterial oxygen saturation at submaximal exercise in hypoxia (FIO2 = 0.115) increased from 75 +/- 4 to 82 +/- 3%, probably because of an efficient ventilatory acclimatization. On Mount Everest, the speed of ascent was very high (5600 m of altitude gain in 6 days), knowing that in conventional expeditions, 12 to 32 days are generally necessary to reach, safe, the same altitude. In conclusion, pre-acclimatization seems to have triggered efficient mechanisms which allowed climbers to save 1 to 3 weeks of time in mountain conditions.


Reflex control of the circulation during exercise. Current theory is that circulatory control in exercise is governed by central command which sets basic patterns of effector activity that is modulated by arterial baroreflexes and chemo- and mechanoreflexes from active muscle. Because central command acts on vagal activity rather than sympathetic nerve activity (SNA), and because muscle chemoreflexes are not normally active during mild to moderate dynamic exercise, current theory cannot explain why SNA to virtually all organs, including active muscle, increases even during mild exercise. Are arterial baroreflexes involved? Baroreflex sensitivity is maintained during exercise, and most importantly, the reflex is reset to higher blood pressure (BP). A new hypothesis is that central command works by resetting the baroreflex to a higher BP and withdraws vagal activity to raise heart rate, cardiac output and BP at the onset of exercise. The key to the hypothesis is that the rise in cardiac output at exercise onset must be fast enough to raise BP to its new reset level immediately, otherwise a BP error occurs that must be corrected by baroreflex and SNA.


Pulmonary circulation in hypoxia.

Pulmonary circulation in hypoxia. Hypoxia constricts the pulmonary vessels. An increase in pulmonary vascular resistance is seen in normal subjects during hypoxic breathing at sea level, in acclimatized lowlanders and in high altitude natives. Hypoxic pulmonary hypertension in all these circumstances is most generally moderate, except in high altitude natives at exercise. However, in the absence of high altitude pulmonary edema (HAPE) or chronic mountain sickness, a right heart failure that would be the human counterpart of brisket disease described in cattle, apparently never occurs. In adult patients with HAPE, reported mean pulmonary artery pressures (Ppa) measured during a right heart catheterization range from 22 to 63 mmHg with an average of 39 mmHg. Recent echo-Doppler estimates of systolic Ppa in patients with a HAPE are at an average of 53 mmHg, only moderately higher than in healthy subjects exposed to comparable normobaric or hypobaric hypoxia. Subjects with a previous HAPE often present with an enhanced pulmonary vascular reactivity to hypoxia compared to controls when tested at sea level, but the overlap is great. Non invasive echo-Doppler pulmonary hemodynamic studies at sea level have not been reported to reliably discriminate subjects susceptible to HAPE.


Chemosensitivity and regulation of ventilation during sleep at high altitudes. The paper presents new observations on young high altitude natives (Andes and Himalayas), testing the hypothesis that periodic breathing with apnea during sleep is determined by their ventilatory sensitivity to hypoxia and its interaction with the sleep state. The hypothesis is in general supported by the evidence. But, contrary to expectation, the ventilatory sensitivity to hypoxia in the Sherpa children was significantly lower than those in the Andes. Despite that departure, the magnitude of ventilatory periodicity among the subjects was internally consistent with their ventilatory sensitivity to hypoxia. Although the carotid chemosensory input is the pacesetter for the reflexive periodicity, mechanisms in the central nervous system can influence it significantly.


Sleep apneas and high altitude newcomers. Sleep and respiration data from two French medical high altitude expeditions (Annapurna 4,800 m and Mt Sajama 6,542 m) are presented. Difficulties in maintaining sleep and a SWS decrease were found with periodic breathing (PB) during both non-REM and REM sleep. Extent of PB varied considerably among subjects and was not correlated to the number of arousals but to the intercurrent wakefulness duration. There was a positive correlation between the time spent in PB and the individual hypoxic ventilatory drive. The relation between PB, nocturnal desaturation, and mountain sickness intensity are discussed. Acclimatization decreased the latency toward PB and improved sleep. Hypnotic benzodiazepine intake (loprazolam 1 mg) did not worsen either SWS depression or apneas and allowed normal sleep reappearance after acclimatization.


Control of anxiety and acute mountain sickness in Himalayan mountaineers. This investigation explores the relationship between psychological factors and acute mountain sickness (AMS). AMS occurs in most people staying more than a few hours above 3500 m. Symptoms include headache, nausea, vomiting, insomnia, anorexia, etc. Subjects studied were climbers preparing for an expedition to the Himalayas (80 men and 20 women). The psychological investigation consisted in two mono-factorial tests: STAI (anxiety inventory) and Bortner stress scale. After the expedition, subjects were classified into two groups: those who were susceptible to AMS and those who were not. Results indicated that the two groups differed for trait-anxiety on one hand, and for the level of anxiety before the final ascent on the other hand. In both cases, subjects susceptible to AMS were significantly more anxious than those who were not.


Sleep apneas in high altitude residents (3,800 m). The question is: to what extent periodic breathing usually observed in translocated subjects at high altitude affects normal and polycythemic residents of high altitude? Standard sleep parameters, chest wall movements, temperature of ventilated gas and arterial O2 saturation (SaO2) were continuously recorded in 7 normal highlanders (mean hematocrit: 51%) and 14 polycythemic highlanders (mean hematocrit: 68%) during one night in La Paz, 3,850 m, Bolivia. The patterns of breathing instability were analysed by two ways: measuring duration of apneas and counting all the oscillations of SaO2 greater than 1%. Normal and polycythemic highlanders displayed a wide intersubject variability with regard to breathing instability, hence no significant difference in the total number of apneas and oscillations of SaO2 could be evidenced between the 2 groups. However, the longest apneas and the highest number of oscillations of SaO2 were found in the polycythemic highlanders.


Long term effects of high altitude on brain function. Absence of oxygen to the brain for even a very few minutes results in loss of consciousness and can cause permanent injury. Can the wanderer to the limits of earth-bound hypoxia suffer similar harm from more prolonged exposure to milder hypoxia that does not cause loss of consciousness? I shall review the results from studies where neurobehavioral function has been compared in mountaineers before and after return from great heights and in individuals with chronic pulmonary disease before and after prolonged, continuous oxygen therapy. Many (although not all) of these studies report mild impairment of neurobehavioral function after fairly prolonged hypoxic exposure. Impairment was manifest by deficits in memory storage and recall, aphasia, concentration, and finger tapping speed; the last deficit was still detectable a year later in one group of mountaineers. Limited evidence suggests that climbers with a high ventilatory response to hypoxia (HVR) may be more susceptible to impairment than those with a lower HVR.


The blood-brain barrier in hypoxia.

The blood-brain barrier in hypoxia. The concept of blood-brain barrier has moved over the past years from a passive and relatively immutable structure to a more dynamic interface between blood and brain tissue. The transport mechanisms regulating this adaptative interface might be considered as the most sensitive elements to change such as hypoxia. Among various carrier mediated transports existing at the blood-brain barrier, glucose transport seems to play a predominant role. In severe hypoxia, progressive changes in glucose transport are occurring. These modifications associated with hypoxia can lead to deleterious events when reaching critical threshold. In addition the appearance of vasogenic edema due to changes in cerebral-blood flow, can possibly be prevented by some pharmacological interaction such as the use of selective brain calcium channel blockers.


Increase of cerebral blood flow at high altitude: its possible relation to AMS. CBF increases with acute hypoxia despite the opposing vasoconstrictor effects of the drop in pCO2 caused by hyperventilation. Maintaining normocapnia by adding CO2 the hypoxic CBF responsiveness about doubles. As we have shown recently by this test, the hypoxic CBF response is not blunted but rather somewhat sharpened over five days at almost 4000 meters of altitude. This, along with other evidence, shows that CBF does not in itself adapt to chronic hypoxia. Nevertheless, a decrease in CBF is seen over days at constant altitude primarily due to increase in the hematocrit. The cerebral vasodilatation cannot explain the usual (mild) form of AMS. But it may well be involved in the pathogenesis of the rare but severe cerebral form of AMS, as prolonged increased capillary pressure in vasodilated areas could lead to vasogenic cerebral edema.


Haemostasis at high altitude.

Haemostasis at high altitude. Haemostasis has been studied by several authors during exposure to altitude hypoxia. On acute induction to hypoxia, platelet count, platelet aggregability and bleeding time are normal; an increase of thromboxane released from platelets and of prostacyclin, released from endothelial cells is observed; coagulation factors are unchanged except of F. VIII which is increased; modified antithrombin III (ATm) are normal; fibrinopeptide A is increased in subjects with pulmonary edema and fibrinolytic activity after venous occlusion is normal. In chronic hypoxia, during a stay at 6542 m (Mt. Sajama), we found in 7 subjects an important increase in D. Dimer (p < 0.001) that seems to correspond to an activation of coagulation and a decrease of F. VIII R. Cof/F. VIII R. Ag ratio which suggests an endothelial cell damage.


Microcirculation and high altitude edema. Physiological functions are a conglomeration of cell functions, and all cells are regulated by information processing and energy distributing systems. The former consists of nervous systems and the latter consists of respiro-circulatory systems. Defensive reactions appear in response to local cold stress which can induce frostbite or edema. We analyzed the cold vasoreaction time course in which rhythmical changes and trends were found using rabbit's ear blood vessels. In sheep, hypobaric hypoxia corresponding to 6600 m altitude was applied for 3 hrs. Lung lymph volume increased in response to this stress. Most sheep exposed recovered later. The factors influencing the increase in lung lymph flow and the conditions to induce interstitial edema were analyzed. Simulated-altitude symptoms were, then, analyzed by Sampson's method. In eight subjects exposed to 3700 m condition, the nervous system symptoms were well correlated with the respiro-circulatory symptoms. Thus we concluded that the distinction between system-specific diseases, viz., that between acute mountain sickness cerebral type (AMS-C) and respiratory type (AMS-R) was somewhat fuzzy. A common AMS condition, AMS-general, exists. Lastly, a case of 22-year-old male who died of lung and cerebral edema on a winter mountain was reported. The lung weighed 1506 g and the brain 1610 g.


High altitude pulmonary edema is caused by stress failure of pulmonary capillaries. The pathogenesis of high altitude pulmonary edema (HAPE) is disputed. We propose that the mechanism is stress failure of pulmonary capillaries. The main features to be accounted for are the strong association with pulmonary hypertension, the high permeability characteristics of the edema, and the presence of inflammatory markers in the lung lavage fluid. When the capillary pressure is raised to about 40 mmHg in anesthetized rabbits, ultrastructural damage to the capillary walls is seen including breaks in the capillary endothelial layer, alveolar epithelial layer, and sometimes all layers of the wall. This results in a high permeability form of edema with the escape of high molecular weight proteins and blood cells into the alveolar spaces. In addition the basement membrane of the endothelial layer is frequently exposed, and we suggest that this highly reactive surface attracts and activates platelets and neutrophils. The result is the formation of small thrombi which are frequently seen in HAPE, and the presence of inflammatory markers such as leukotriene B4 and the complement fragment C5a in the lung lavage fluid. Hypoxic pulmonary vasoconstriction raises the pressure in some capillaries because the constriction is uneven. Since HAPE has its origin in the high pulmonary artery pressure, the objective of treatment should be to reduce the pressure by descent, administering oxygen, or giving drugs such as calcium channel blockers (e.g. nifedipine) which relax pulmonary vasoconstriction. Stress failure of pulmonary capillaries satisfactorily accounts for the features of HAPE.


The quest for an animal model of high altitude pulmonary edema. The understanding of the mechanisms underlying certain human diseases usually requires an animal model which can be manipulated in a way that will allow dissection of the pathophysiologic events which lead to the disease. High altitude pulmonary edema (HAPE) occurs in some healthy individuals who ascend from low to high altitude. The disease is characterized by a high protein leak into the lungs and is associated with accentuated pulmonary hypertension. Attempts to find an animal model for HAPE have been made in a number of animal species, including rats, rabbits, sheep, dogs and ferrets. None has been consistently successful. Utilizing the physiologic characteristic of an accentuated hypoxic pulmonary vascular response, we studied both pigs and rats during the stresses of hypoxia and exercise (rats) and examined the lungs for the cellular, protein, and morphologic changes. Protein and cell contents in the lung lavage of the hypoxic animals were slightly higher than the controls while the presence of von Willebrand factor in the hypoxic animals suggests early epithelial damage. This presentation will review previous attempts to find an animal model of HAPE and will discuss the preliminary results of our studies with their suggestive but not confirmatory results.


From the mountains to the labs. A brief summary of the people and their studies on which rests most of what we know today. The science of mountain medicine is less than 150 years old, partly because mountaineering became popular only in the middle of the 19th century. In the last 30 years there has been an explosion of activity on very high mountains, in laboratories, and in simulated high altitude environments. Our knowledge and understanding of high altitude hypoxia has been built slowly and painfully over many centuries. First came recognition that pure air was essential to health. Then the physical properties of the atmosphere were demonstrated 300 years ago. Slowly the vital ingredient in air was identified, and even more recently the relationship between barometric pressure, oxygen, and the sicknesses that affect men at altitude was appreciated. In this paper, will be described how some of the most important advances were made, and where the explorers sometimes went astray. I will mention some of the people whose major contributions have been forgotten, to remind us that fame or fortune does not necessarily go to those who deserve it most. Remember that not until the middle of the 18th century did men climb high mountains. The intrepid prehistoric hunter (Otzi) who was lost on a high mountain 5000 years ago and found last year was certainly an exception. Only recently have mountaineer-scientists begun to study in the laboratory what they observed on the summits. By knowing how we came to know what we believe to be true today, perhaps we may understand better how knowledge grows, not only in a steady flow but now and then by brilliant leaps.(ABSTRACT TRUNCATED AT 250 WORDS)


Salt and water control at altitude.

Salt and water control at altitude. The physiological effect of altitude hypoxia, in the absence of exercise, is a sodium and water diuresis with decrease in plasma and extra-cellular volumes. Plasma aldosterone concentrations (PAC) are reduced but plasma atrial natriuretic peptide (ANP) levels are modestly increased. Day-long exercise at low altitude has almost opposite effects on fluid balance. There is an anti-diuresis, sodium retention, expansion of the plasma and extra-cellular compartments, elevation of PAC and ANP. Subjects who develop acute mountain sickness (AMS) show a pathological response to hypoxia even before the development of symptoms. There is an anti-diuresis, sodium retention, increased plasma and extra-cellular volumes and increased PAC compared with subjects resistant to AMS. Plasma ANP tends to be elevated compared with sea level values but the relation of ANP levels to AMS is variable. In general therefore, the pathological response to altitude hypoxia parallels that of exercise at low altitude and is opposite to the physiological response. Both exercise and the pathological response predispose the subject to edema and are probably important in the genesis of AMS.