Glucocorticoid and mineralocorticoid hormones depress liver delta 5 desaturase activity through different mechanisms.

The effects of 11-deoxycorticosterone and aldosterone on liver delta 5 desaturase activity were examined. Both steroid hormones significantly depressed the conversion of [1-14C] eicosatrienoic acid to arachidonic acid. However, the mechanism of action of each of these hormones was different. The effect of 11-deoxycorticosterone was mediated by a soluble protein present in the liver cytosolic fraction. The biological activity of this protein, having a molecular weight lower than 25 kDa, was impaired by trypsin digestion. To determine whether the inhibitory protein was induced through glucocorticoid or mineralocorticoid receptor occupancy, cultured Morris minimal deviation hepatoma cells were pre-treated with the antiglucocorticoid cortexolone or the mineralocorticoid receptor antagonist spironolactone. The results obtained demonstrated that only glucocorticoid receptor structures were involved in the induction of this regulatory protein. The inhibitory response evoked by aldosterone was mediated by a different mechanism. In the case of aldosterone, the inhibitory action affected the microsomal membranes and was not mediated by a soluble protein messenger.


Effects of various dietary fats on cardiolipin acyl composition during ontogeny of mice.

Cardiolipin (CL) is a unique mitochondrial phospholipid, containing up to 85 wt% 18:2n-6 in mammals. The influence of maternal dietary fatty acids on the acyl composition of offspring CL has not been examined previously. Adult female mice were thus fed diets rich in 18:1n-9 (olive oil), 18:2n-6 (safflower oil), 18:3n-3 (linseed oil) or 20:5n-3 and 22:6n-3 (fish oil/safflower, 9:1, w/w), for a five month period, encompassing two breeding cycles. Offspring from the second breeding cycle were then fed these diets. The acyl composition of CL, phosphatidylcholine and phosphatidylethanolamine from liver and heart was evaluated from mice killed 3, 18 and 42 days after parturition. The primary nutrient sources at these three time points were transplacental nutrients, breast milk and the diet, respectively. Maternal diet was found to influence the acyl composition of CL via both placental transfer of fatty acids and breast milk. Fish oil feeding resulted in replacement of a substantial portion of 18:2n-6 with 22:6n-3; after 42 days, the area% of 18:2n-6 in heart CL was reduced from 62% in safflower oil fed mice to 12%. In comparison to fish oil feeding, linseed oil feeding resulted in a much lower accumulation of 22:6n-3. Olive oil feeding resulted in substantial replacement of 18:2n-6 with 18:1n-9 (18:2n-6 was reduced from 62% to 31%). Physiologically, these findings are relevant because changes in CL acyl composition may influence the activity of associated inner mitochondrial membrane enzymes.


Surface components of chylomicrons from rats fed glyceryl or alkyl esters of fatty acids: minor components.

The lipid class, fatty acid and molecular species composition of the minor polar surface components of rat lymph chylomicrons were determined during absorption of menhaden oil and corn oil or of the corresponding fatty acid ethyl esters. In addition to the previously reported minor polar lipids (sphingomyelin, phosphatidylserine, phosphatidylinositol, phosphatidic acid and lysophosphatidylcholine), we identified phosphatidylglycerol, dimethylphosphatidylethanolamine, ceramide and cholesteryl sulfate in the chylomicrons from both oil and ester feeding. The dietary fatty acids were found to be incorporated to a variable extent into the different phospholipid classes, the proportions of which remained the same during both types of feeding. No evidence was obtained for the presence of the minor glycerophospholipids characteristic of the lysosomal membranes (e.g., bis-phosphatidic, lysobisphosphatidic and semilysobis-phosphatidic acids), although special efforts were made to identify them. These results indicate that the chylomicrons arising from the monoacylglycerol and phosphatidic acid pathways of triacylglycerol biosynthesis become enveloped in closely similar monolayers of phospholipids. Hence, all triacylglycerols may be secreted from the villus cells via a common mechanism as suggested by the previously demonstrated convergence (at the 2-monoacylglycerol stage) of the monoacylglycerol and the phosphatidic acid pathways of mucosal triacylglycerol formation [Yang, Y.L., and Kuksis, A. (1991) J. Lipid Res. 32, 1173-1186].


Increments of dietary linoleate raise liver arachidonate, but markedly reduce heart n-6 and n-3 fatty acids in the rat.

Four diets containing 20% of energy (en%) as fat and with linoleic acid contents of 1.9, 3.1, 7.7 and 10.1 en%, respectively, were fed to one-month-old male rats for three months. The fatty acid profiles and the levels of the major n-6 and n-3 fatty acids in the lipids of plasma, liver, heart and kidney were measured. We found that with increasing concentrations of 18:2n-6 in the diet, linoleic acid rose in plasma and in all organs, but long-chain n-6 and n-3 fatty acids responded differently. In liver, arachidonic acid increased and n-3 fatty acids were not significantly affected; in heart, both arachidonic and docosahexaenoic acids were progressively reduced; and in kidney, there was no change of n-6 and n-3. The results indicate that incremental changes in dietary linoleate affect the levels of polyunsaturated fatty acids in liver and extrahepatic organs differently.


Incorporation of n-3 fatty acids of fish oil into tissue and serum lipids of ruminants.

This study examines the biohydrogenation and utilization of the C20 and C22 polyenoic fatty acids in ruminants. Eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids were not biohydrogenated to any significant extent by rumen microorganisms, whereas C18 polyenoic fatty acids were extensively hydrogenated. The feeding of protected fish oil increased the proportion of 20:5 from 1% to 13-18% and 22:6 from 2% to 7-9% in serum lipids and there were reductions in the proportion of stearic (18:0) and linoleic (18:2) acids. The proportion of 20:5 in muscle phospholipids (PL) increased from 1.5% to 14.7% and 22:6 from 1.0% to 4.2%; these acids were not incorporated into muscle or adipose tissue triacylglycerols (TAG). In the total PL of muscle, the incorporated 20:5 and 22:6 substituted primarily for oleic (18:1) and/or linoleic (18:2) acid, and there was no consistent change in the porportion of arachidonic (20:4) acid.


Comparison of sulfoquinovosyl diacylglycerol from spinach and the purple bacterium Rhodobacter spaeroides by fast atom bombardment tandem mass spectrometry.

Isolated sulfoquinovosyl-diacylglycerol (SQD) from spinach and the purple bacterium Rhodobacter sphaeroides provide two sources of very different molecular species of SQD. We were able to demonstrate by fast atom bombardment-collisionally activated dissociation tandem mass spectrometry in the negative ion mode that the sulfoquinovosyl head group of the plant and bacterial lipids can be characterized by the common fragmentation pattern found in the spectra of both samples. Differences in the acyl functions from the two sources were also identified by this technique. SQD specific fragments are found at m/z 299, 283, 241, 225, 165 and 80 which indicate the presence of the sulfoquinovosyl moiety. The two predominant molecular species found in spinach contain palmitic and linolenic ([M-H]- at m/z 815) or two linolenic acids ([M-H]- at m/z 837) in the sn-1 and sn-2 positions, while the two major species of the bacterial lipid contain palmitic and 18:1 (vaccenic) acids ([M-H]- at m/z 819) or stearic and 18:1 (vaccenic) acids, ([M-H]- at m/z 847), respectively.


Positional analyses of triacylglycerol fatty acids in the milk fat of the antarctic fur seal (Arctocephalus gazella).

The positional distribution of fatty acids has been determined for the milk triacylglycerols of the Antarctic fur seal, Arctocephalus gazella. Of particular interest was the positional distribution of the polyunsaturated n-3 fatty acids in milk triacylglycerols (TG). In adipocytes of pinnipeds, TG are synthesized with the n-3 fatty acids primarily in the sn-1,3 positions. To determine the positional distribution, extracts of enzymatically digested lipids were separated by thin-layer chromatography, and the constituent fatty acids were separated and quantified by gas-liquid chromatography. Monoenoic and saturated fatty acids comprised over 75% of the total, the ratio of monoenoic to saturated fatty acids being 2:1. The percent content of the long-chain n-3 fatty acids, 20:5, 22:5 and 22:6, ranged between 15-20%. The positional analyses revealed that at the sn-2 position of milk TG, saturated fatty acids were in excess (57%), and the content of n-3 fatty acids was less than 5%. More than 80% of the n-3 fatty acids in milk were located in the sn-1,3 positions. The data indicate that in pinnipeds TG are synthesized in the mammary gland and adipose tissue with fatty acids having similar positional distributions.


Ultrastructural aspects of liver injury with special reference to small bile ducts in patients with ulcerative colitis.

Liver tissue specimens taken at colectomy from 29 patients with chronic ulcerative colitis were studied by electron microscope. The fine-structural alterations were correlated with light microscopy and with biochemical liver function tests. The purpose was to identify ultrastructural features which could explain the pathogenesis of sclerosing cholangitis. Severely injured bile-duct epithelial cells were seen in three out of the eight light-microscopically diagnosed cholangitis cases, in the two cases of non-specific reactive hepatitis, and in the two fatty livers. Four cholangitis cases had, in heavily thickened bile-duct basement membranes, translucent areas containing bile-like material. Bile-duct microvilli were often blunted, and reduced in number. Intracanalicular bile thrombi and bile inclusions in hepatocytes were seldom seen, mostly but not exclusively in cholangitis. The fine-structural alterations apparently represent various stages of liver injury. These findings do not appear to be specific, but their prominence seems to correlate with the progression of the disease, at least in the case of histological parameters, but also in serum enzyme activities indicative of cholestasis. The bile-like electron-dense material found in proliferating basement membranes, very possibly regurgitated into the injured bile-duct wall after epithelial injury, could enhance the development of periductal fibrosis, leading to progression of sclerosing cholangitis.


Peripheral blood lymphocyte subsets in patients with chronic hepatitis C--effects of interferon treatment.

Thirty-three patients with chronic hepatitis non-A, non-B/C were included in a randomized controlled study of recombinant alpha-2b interferon treatment 3 MU three times weekly for 36 weeks. In lysed whole blood, lymphocyte subpopulations were enumerated by flow cytometry detecting fluorescein or phycoerytrin conjugated monoclonal antibodies directed against seven different epitopes. Patients with chronic active hepatitis were significantly older than patients with chronic persistent hepatitis (p less than 0.05). Before treatment, the proportions of different subsets of lymphocytes were within the normal reference values and the CD4/CD8 ratio was also normal. No increased activation of T-cells was noticed. Patients over 50 years of age, however, had a significantly increased (p less than 0.01) proportion of HLA-DR+ lymphocytes, mainly B-cells. Treatment decreased the absolute number of peripheral blood leukocytes and lymphocytes. There was also a significant decline in the proportion of CD8+ lymphocytes and NK-cells, and a significant increase in the proportion HLA-DR+ cells and of the CD4/CD8 ratio. The increased proportion of HLA-DR+ cells, however, did not reflect peripheral T-cell activation; instead, it was due to increasing B lymphocyte numbers.


Modulation of thioacetamide-induced hepatocellular necrosis by prostaglandins is associated with novel histologic changes.

Cytoprotective effects of the prostaglandins 16,16-dimethyl PGE2 (dmPGE2) and PGF2 alpha tromethamine (PGF2 alpha) were evaluated in the rat model of acute hepatocellular necrosis induced by thioacetamide (TAA). dmPGE2 (100 micrograms/kg SC 8 hourly) did not induce a significant increase in survival when started after the onset of TAA-induced fulminant hepatic failure. However, priming with dmPGE2 (100 micrograms/kg SC 30 min before TAA) reduced TAA-induced elevations in serum ALT (684 +/- 68 (SEM) vs 274 +/- 135 IU/1, p less than 0.01). This phenomenon did not occur if dmPGE2 was administered after TAA or by the IP route. Modulation of TAA-induced centrizonal hepatocellular necrosis by dmPGE2 was associated with a striking increase in centrizonal ballooning of hepatocytes (p less than 0.01), and, as assessed by stereology, less hepatocellular necrosis and degenerative changes. PGF2 alpha, which in contrast to dmPGE2 does not act via cAMP, had no effect on TAA-induced changes in serum ALT or hepatic histology. These findings suggest that dmPGE2 decreases hepatocellular necrosis by activating surface membrane adenylate cyclase and consequently stimulating cAMP. Ballooning of hepatocytes could occur secondary to these membrane events and appears to be a marker of dmPGE2-induced cytoprotection in this model.


Haemodynamic alterations and their morphological basis in biliary obstruction.

The relationship between the haemodynamic alterations and morphological changes in the liver caused by biliary obstruction was investigated in rats after ligation of the common bile duct. In these rats, the portal vein pressure was markedly elevated, and the differences in blood pressure between the portal vein and the terminal portal venule and between the terminal portal venule and the terminal hepatic venule were greater than in the sham-operated rat. The livers showed narrowing of the most peripheral branches of the portal vein due to compression by proliferated bile ductules and sinusoidal stenosis due to enlarged liver cells, but there was no perceptible change in the hepatic vein branches. These data suggest that hepatic circulatory disturbance in biliary obstruction is caused by deformation of the peripheral portal vein branches and sinusoidal stenosis.


An enzyme-linked (alkaline phosphatase) oligonucleotide probe for the detection of serum hepatitis B virus DNA.

Serum HBV-DNA detection represents a new and important diagnostic tool for the hepatologist, as well as a prognostic and therapeutic guide. Though most laboratories use genomic radioactive probes, the appearance of commercially available enzyme-linked oligonucleotide probes, which simplify the method, represents an advance in HBV-DNA detection. In order to verify the value of an enzyme-linked (alkaline phosphatase) oligonucleotide probe in HBV-DNA detection, we have first compared the results of the detection of serum HBV-DNA in 46 patients at different serological stages of HBV infection using this probe and with those obtained using a genomic P32-labeled probe. Fisher's test analysis of the results shows statistical significance; this indicates a high correlation between methods. Secondly, we have tested 296 sera of patients at different serological stages of HBV infection with the enzyme-linked probe; we have found HBV-DNA in 8 patients with acute hepatitis (61.54%), 61 HBeAg (70.12%), and 7 anti-HBe (12.07%) chronic hepatitis. These results show the value of this probe for routine survey of serum HBV-DNA using a simple method which avoids the use of radioactivity.


Intracellular distribution and effect of the antimalarial drug mefloquine on lysosomes of rat liver.

Mefloquine was administered in a single dose (1-30 mg/100 g) to rats in order to study its subcellular distribution and effects on rat liver lysosomal structure and function. Subcellular fractionation showed a significant enrichment of mefloquine in lysosomes. Even repeated administration of mefloquine did not affect the levels of cytochrome-P-450 or its reductase, indicating, although not proving, that it is not metabolized by this mono-oxygenase system. Mefloquine caused an expansion of the lysosomal apparatus, earliest seen by 24 h and lasting for some 7 days. Initially, cytoplasmic constituents were seen inside the lysosomes. Later, the lysosomes harboured myelin-like figures (multilamellar bodies) disappearing after 7-10 days. The proteolytic and lipolytic capacity was assessed in isolated lysosomes. Mefloquine caused increased protein degradation but decreased breakdown of lipids. Concomitantly, all five major phospholipids (phosphatidyl-choline, -ethanolamine, -inositol, -serine and sphingomyelin) increased in the lysosomes. It is concluded that: (1) mefloquine is a lysosomotropic drug that accumulates in lysosomes; (2) mefloquine impairs lipid degradation with ensuing accumulation of lipids in lysosomes; and (3) lysosomal trapping explains the high volume distribution of mefloquine.


Quantitative analysis of activated Kupffer cells in viral hepatitis: application of computer image analysis for lectin histochemistry.

Lectin histochemistry revealed that Kupffer cells in the normal liver bound lectins such as Concanavalin A (Con A), Ricinus communis agglutinin (RCA) and Wheat germ agglutinin (WGA), but did not bind Peanut agglutinin (PNA), Dolichos fibflorus agglutinin (DBA), Ulex europaeus agglutinin I (UEA-I) or Soybean agglutinin (SBA). Kupffer cells in viral liver diseases, however, bound the PNA lectin and the binding was specific to Kupffer cells in liver parenchyma. Computer image analysis was performed using light micrographs of sections stained with immunoperoxidase and diaminobenzidine (DAB). The dark brown area of reaction products was detected by analyzing each color component (red, green and blue) in the picture and was expressed as the percent area in the parenchyma. Quantitative analysis revealed the percent area occupied by Kupffer cells positive for the PNA lectin was as follows: acute hepatitis, 2.83 +/- 0.74; chronic persistent hepatitis, 2.51 +/- 0.88; chronic aggressive hepatitis, activity moderate and severe, 4.71 +/- 2.23 and 3.45 +/- 1.84; and liver cirrhosis, 1.96 +/- 0.99. The percent area of Kupffer cells was significantly higher in CAH2A than that in chronic persistent hepatitis or in liver cirrhosis. These results suggest that the PNA lectin could be used as a marker for activated Kupffer cells and that activated Kupffer cells were increased in volume in chronic aggressive hepatitis.


Breast disease evaluation with fat-suppressed magnetic resonance imaging.

Thirty patients with a variety of pathologically confirmed malignant and benign pathologic lesions of the breast were evaluated with a spectrally selective fat suppression imaging technique to obtain fat-suppressed images of the breast. The technique, a selective partial inversion-recovery (SPIR) method, demonstrated the architectural relationship of malignant and benign tumors with respect to the normal water-containing elements of the breast. These relationships included signs of advanced malignant disease such as tissue retraction, invasive growth, and multicentricity, which appeared on the fat-suppressed images. Fat-suppressed imaging provided useful information for assessing the breasts of both pre- and postmenopausal women, especially in the latter group, where fatty involution of the breast is common. Microcysts, which are normally not visualized by conventional methods, were demonstrated and associated with patients having confirmed fibrocystic disease of the breast. As expected, the SPIR technique did not improve the ability to distinguish between tissues having similar T1 and T2 relaxation time values, such as malignant tumors and normal breast parenchymal tissues. The technique was able to demonstrate that the intense lipid signal, known to be responsible for obscuring the borders of water-fat interfaces and small tumors, could be eliminated in a variety of pathological settings.


Heterogeneous in vivo MR images of soft tissue tumors: guide to gross specimen sampling.

Twelve soft tissue tumors preoperatively studied with magnetic resonance (MR) imaging contained areas of inhomogeneous intralesional signal intensity. The pathologist's selection of biopsy sites from gross specimens was based on specific MR images selected by a radiologist and depended on close cooperation between the radiologist and pathologist. The histopathology so sampled, further depended on the lesion's size, careful gross specimen orientation, discrete sampling, and a specially developed Grid Analysis technique. Our initial experience indicates that (1) histology may vary within different and often neighboring sites of a single soft tissue lesion; (2) that such variability is common in soft tissue tumors; (3) that histological variability within different sites of a single lesion influences signal heterogeneity; and (4) that although differing MR signal intensities per se are not tissue specific, MR may enhance the histopathological accuracy of pathologists who can be directed to particular gross specimen sites by magnetic resonance images. To our knowledge such a specific, detailed effort has not been made.


Magnetization transfer contrast imaging of the human leg at 0.1 T: a preliminary study.

Magnetization transfer contrast imaging is an MR technique that capitalizes on interactions between the protons of mobile and macromolecularly bound water molecules. Studies to date, conducted primarily on 4.7 T and 1.5 T MR systems, have yielded results unique from conventional T1- and T2-weighted imaging studies. In this study, performed on a 0.1 T device, a section of lower leg was imaged in 20 normal human subjects and one patient with muscular dystrophy, using both a standard 500/22 gradient-echo sequence and a 500/22 gradient-echo sequence combined with off-resonance radio frequency irradiation designed to elicit magnetization transfer contrast. Results of the two techniques were compared. Our findings suggest that magnetization transfer contrast imaging is feasible at 0.1 T, and that this technique allows reproducible tissue characterization and improves contrast between certain tissues.


On the relation between the dimensions and resonance characteristics of the vocal tract: a study with MRI.

The relation between the spatial configuration of the vocal tract as determined by magnetic resonance imaging (MRI) and the acoustical signal produced was investigated. A male subject carried out a set of phonatory tasks, comprising the utterance of the sustained vowels /i/ and /a/, each in a single articulation, and the vowel /epsilon/ with his larynx positioned variously on a vertical axis. Two- and three-dimensional measurements of the vocal tract were performed. The results of these measurements were used to calculate resonance frequencies, according to predictions from acoustical theory. Finally, calculated frequencies were compared with actually measured resonance frequencies in the audio signal. We found a strong relation between the acoustical signal produced and the spatial configuration for the first resonance frequencies of the articulations of the vowel /epsilon/, and first two resonance frequencies of the vowels /a/ and /i/. The capability to determine accurately vocal tract dimensions is a major advantage of this imaging technique.


Thymidine-modulated 5-fluorouracil metabolism in liver and RIF-1 tumors studied by 19F magnetic resonance spectroscopy.

19F Magnetic resonance spectroscopy was used to study the impact of the biochemical modulator thymidine (TdR) on the 5-fluorouracil (5FU) metabolism in the livers and radiation-induced fibrosarcoma (RIF-1) tumors of 5FU-treated C3H mice. The liver spectra measured after administration of 5FU (65 or 130 mg/kg IP) showed the 5 FU resonance and its catabolites alpha-fluoro-beta-ureidopropionic acid and alpha-fluoro-beta-alanine. At the latter dose, fluoronucleotide signal was also detected. The liver spectra of TdR-pretreated (500 mg/kg, IP) mice showed additional signals of fluoronucleotide and fluoronucleoside at both 5FU doses, while alpha-fluoro-beta-alanine was not detected. TdR pretreatment increased the half-life of 5FU in livers from 24 +/- 2 to 126 +/- 46 SEM min at the 5FU dose of 65 mg/kg and from 28 +/- 2 to 95 +/- 22 min at the 130 mg/kg dose (P less than .1 and P less than .01, respectively). TdR-pretreated mice had higher 5FU anabolite (fluoronucleotide + fluoronucleoside) levels in their RIF-1 tumors than nonpretreated mice that received the same 5FU doses (56 +/- 15 SEM vs. 0 arbitrary units at the 5FU dose of 65 mg/kg, and 88 +/- 21 vs. 10 +/- 3 arbitrary units at 130 mg/kg 5FU; P less than .0001). The percentage drop in tumor volume was enhanced in the mice that received TdR, from 27 +/- 4 SEM to 52 +/- 2 at the 5 FU dose of 65 mg/kg and from 24 +/- 3 to 65 +/- 4 at the 130-mg/kg dose (P less than .0001, both).


In vitro NMR investigation of controlled single and repeated isoflurane anesthesia.

Immobilization of laboratory animals is a basic requirement for experimental in vivo NMR measurements. The effect of single and repeated isoflurane anesthesia on proton NMR relaxation times T1 and T2 in rat liver was studied. Furthermore, physiological monitoring was performed to evaluate the influence of isoflurane anesthesia (up to 2 hr) on biological parameters. Neither single nor repeated isoflurane application over the observed time produce relevant alterations of physiological parameters or relaxation times, compared with untreated control groups. Therefore, we conclude that isoflurane anesthesia is appropriate for in vivo NMR investigations, especially of the liver.


Explicit treatment of mutual inductance in eight-column birdcage resonators.

A formulation has been developed for the determination of self and mutual inductances in unloaded, eight-column symmetric birdcage coils using their expected resonant mode current patterns and well-known inductance formulas. The average frequency differences between theory and experiment for mode one resonances for nine low-pass coils were 0.66 (+/- 0.57) MHz and 2.14 (+/- 2.08) MHz using effective (self plus mutual) and self inductances, respectively, and similarly, for three high-pass coils, 1.19 (+/- 0.56) MHz and 2.79 (+/- 2.20) MHz. These frequency differences were more pronounced for the higher modes; for mode four, the differences neglecting mutual inductance were 14.30 (+/- 11.10) MHz and 10.42 (+/- 4.60) MHz for the low- and high-pass coils, respectively. This analysis provides the first explicit evaluation of the total end-ring and column inductances L1 and L2 within each birdcage section at resonance with resulting excellent agreement in resonant frequencies between theory and experiment.


Purpose-designed probes and their applications for dynamic NMR microscopy in an electromagnet.

The electromagnet provides a favorable environment for certain applications of NMR microscopy. These include plant imaging experiments and measurements of slow molecular diffusion, where high magnetic field gradients for the pulsed gradient spin echo (PGSE) technique are required. In this paper, two probes designed specifically for these two applications are described. In the first case, the open space within the probe has been maximized in order to incorporate environmental support systems for the plant, while in the second the smallest possible PGSE gradient coil former has been used to maximize the gradient strength. Examples are given of Dynamic NMR Microscopy experiments on a castor bean stem and on poly(ethylene oxide)/water solutions under shear thinning conditions.


Compression and reconstruction of MRI images using 2D DCT.

In magnetic resonance imaging (MRI), the original data are sampled in the spatial frequency domain. The sampled data thus constitute a set of discrete Fourier transform (DFT) coefficients. The image is usually reconstructed by taking inverse DFT. The image data may then be compressed using the discrete cosine transform (DCT). We present here a method of treating the data that combines two procedures, image reconstruction and data compression. This method may be particularly useful in medical picture archiving and communication systems (PACS) where both image reconstruction and compression are important issues.


Fetal development of mice following intrauterine exposure to a static magnetic field of 6.3 T.

The study was undertaken to investigate possible teratogenic effects of a high magnetic field on fetal development in mice. Eighty-four pregnant CD-1 mice (ICR) were exposed to a static magnetic field of 6.3 T for 1 hr a day from day 7 through day 14 of gestation, a period corresponding to major organogenesis. Fifty mice served as controls. Dams were sacrificed on day 18 of gestation. Fetuses were examined for both external and skeletal abnormalities. No significant differences between exposed and control groups were observed regarding litter size, fetal weight, intrauterine mortality rate, or external and skeletal anomalies. The effects of static magnetic field of 6.3 T on the parameters studied appear negligible.


Evaluation of nonionic nitroxyl lipids as potential organ-specific contrast agents for magnetic resonance imaging.

Considering their intrinsic properties of accumulation in the hepatic tissue, we have synthesized nitroxyl-containing lipids as potential organ-specific contrast agents for magnetic resonance imaging (MRI). Their resistance to reduction by ascorbate and in liver homogenates, and their relaxivity in different media were investigated and compared to those of free carboxyl-Proxyl (3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl) and Tempamaine (4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl). With respect to the reduction rates by ascorbate, the lipid derivatives show the same well-known order of reactivity as carboxy-Proxyl and Tempamine, the five-membered nitroxyls being more stable than the six-membered compounds. However the binding of the piperidinoxyl compounds to the fatty acids confers to those lipid derivatives a markedly increased stability. Similarly, in liver homogenates, the nitroxyl lipids remained unchanged more than 20 min, contrarily to carboxy-Proxyl and Tempamine. The measurements of spin-lattice relaxation time (T1) in biological media have demonstrated a higher relaxivity of nitroxyl lipids, which can be related to their interaction with proteins. Tested in vivo, one of the synthesized compounds (0.75 mmol/kg) produced an enhancement of 44 +/- 12% of the hepatic signal 5 min after intraportal injection in T1-weighted images. The potential applicability of the other nitroxyl lipids as contrast agents for MRI was limited in the in vivo studies by an unexpected toxicity. Work is currently in progress to improve the therapeutic index of the present class of nitroxyl lipids.


Motion-triggered cine MR imaging of active joint movement.

MRI cine studies of active physiological joint movement can provide additional functional information as a supplement to standard examinations. With the ankle joint as an example, it is shown that it is possible to measure kinematic MRI presentations of active joint movement. A pneumatic pressure transducer, a respiratory monitor, and an active differentiator transformed the skin muscle shifting of periodically performed joint movement to a pseudo-ECG, which finally triggered the MRI scanner as in cardiac cine MR imaging.


Gradient amplifier imperfections in NMR imaging.

This paper describes the influence of the transition distortion of gradient amplifiers on direct Fourier NMR imaging techniques. We demonstrate artifacts arising in the real measurement of the spin density images. Image artifacts are compared with artifacts obtained by computer simulations of the transition distortion of gradient amplifiers.


Optimization schemes for selective excitations: application to the DIGGER pulses.

In this work, two distinct approaches to the tailoring of selective radiofrequency (RF) pulses were applied to a cos-sinc pulse of the DIGGER sequence used in localized spectroscopy. Ideally, three such pulses combined with a gradient in each direction destroy the Mz component of the magnetization everywhere but in the volume of interest. In the first approach, the optimal RF amplitude modulation is found by minimizing the difference between the ideal and the computed Mz profiles. In the second strategy, the RF pulse envelope is adjusted by optimization of the tip angle profile. Computed slice profiles optimized by each of these methods have been compared to experimental results. Simulations as well as experiments show that the second approach, which optimizes tip angles, is the most efficient.


Spectroscopic imaging display and analysis.

A system for display of magnetic resonance (MR) spectroscopic imaging (SI) data is described which provides for efficient review and analysis of the multidimensional spectroscopic and spatial data format of this technique. Features include the rapid display of spectra from selected image voxels, formation of spectroscopic images, spectral and image data processing operations, methods for correlating spectroscopic image data with high resolution 1H MR images, and hardcopy facilities. Examples are shown for 31P and 1H spectroscopic imaging studies obtained in human and rat brain.


CT and MR appearance of subureteric Teflon and periuretral Teflon migration: a case report.

We present the computed tomography (CT) and magnetic resonance (MR) findings of a case in which an adult patient underwent subureteric injection of polytetrafluoroethylene (PTFE; Teflon) (STING) to correct vesicoureteral reflux. We report the appearance of periureteral PTFE migration mimicking cystic pathology.


Skeletal muscle lymphoma: MRI evaluation.

The magnetic resonance imaging (MRI) features of two cases of malignant lymphoproliferative disease involving skeletal muscle are presented. In both cases involved muscles were quantitatively and subjectively hypointense to fat on T1-weighted spin echo images, hypointense or isointense on T2-weighted spin echo images, and hyperintense on short tau inversion recovery (STIR) images. The findings suggest that lymphoproliferative disease should be considered as an etiology of a skeletal muscle lesion that is hypointense or isointense to fat on T2-weighted spin echo magnetic resonance images.


Medical students' perceptions of themselves and residents as teachers.

Eighty-three medical students from one class at the University of Vermont College of Medicine were surveyed as to their perceptions of both themselves and residents as teachers. Sixty seven percent of the students felt that residents played a significant role as teachers during the first clinical year. Students estimated that one-third of their knowledge could be attributed to housestaff teaching. A large majority of students wanted to teach students during medical school (80%) and residency (93%). Ninety percent of students surveyed would participate in a workshop to improve teaching skills prior to beginning residency; of this group, forty nine students ranked the importance of components of a teaching skills workshop. The findings suggest that medical students are interested both in learning teaching skills and teaching during medical school and during residency.


How we use questionnaires for learner evaluation of clinical experiences.

The use of questionnaires incorporating quantitative and qualitative analysis are an integral part of practice when monitoring the learning experience for student nurses on clinical placement. This paper outlines this system in the belief that the information could be helpful to other health professionals who are responsible for monitoring the clinical learning experiences of their students. Reference is made to other systems, such as educational audit, and some of the trends identified in analysing data collected is discussed. Finally, the potential for further developing this system is noted.


Postgraduate teaching audit by peer review of videotape recordings.

The effectiveness of peer review in postgraduate medical teaching by hospital consultants using videotape recordings of teaching sessions has been assessed. The technique is useful for routine, infrequent and for 'one off' self-tuition. Participants' assessment of the 'clarity of structure' of teaching sessions and 'abilities to self-analyse' did change but 'mannerisms' did not.


How to evaluate educational programmes in the health professions.

This paper advocates an alternative approach to the evaluation of educational programmes in the health professions. In the past, effectiveness of programmes has been judged by casual observations, visitation reports by outside experts, student performance at nationwide examinations, systematic surveys and experimental research. Decisions have been made based on either one or more of the above methods. It is being argued that these methods are not always appropriate and mostly inadequate in providing a holistic description and judgement of the educational programme. Social science disciplines have contributed to the development of case study, an alternative methodology, for evaluating educational programmes. The case study design is emerging as a legitimate approach for evaluating educational programmes. Qualitative methods such as participant observation, interviewing and documentary analysis have been found to bring new insights in evaluating short-term and long-term programmes in medical and allied professions. Although qualitative methods are emphasized in case studies, quantitative data from survey instruments can increase the credibility and understanding of the evaluation results. Different measures have been suggested to deal with questions of validity and reliability in case study evaluation.


Senior medical students as simulated patients in an objective structured clinical examination: motivation and benefits.

Third and fourth year medical students were recruited to participate as simulated patients and examiners in an Objective Structured Clinical Examination (OSCE) administered for second year medical students. Students reported they were motivated to participate, not only by the honorarium, but because they believed the OSCE would be fun and interesting and because they were interested in medical education and in improving clinical evaluation. The third and fourth year medical students benefitted academically and financially from participation. Faculty benefitted by having a readily available source of enthusiastic and knowledgeable simulated patients.


An examination of the examinations: the reliability of the objective structured clinical examination and clinical examination.

This study evaluates the correlation that exists between the objective structured clinical examination and the traditional clinical examination. An analysis is performed on the results of four groups of students assessed by these two methods. The internal consistency of the OSCE is also described by correlating the results by rank difference correlation using the split-half method of grading the even and odd numbered stations separately. Also 46 surgical interns were asked to indicate their preference regarding the efficacy of five different methods of assessment of clinical competence. The results indicate a high reliability of OSCE and traditional clinical examination. In the opinion of surgical interns, the OSCE and clinical examination both scored high for their ability to assess clinical competence.


Faculty evaluation of student performance: a step toward improving the process.

Most clerkship evaluation systems give the greatest evaluative weight in deriving grades to some form of evaluation by faculty and housestaff, although few studies have been reported concerning which elements of performance are most important or which discriminate best. The results of this study show that a select group of faculty, heavily involved with assessment of student performance, agreed that certain aspects of performance were more important and/or discriminated better between average and superior medicine clerks. We suggest that those aspects of performance be given more consideration when designing curricula, providing student feedback, and assigning grades for medicine clerkships and that medical educators engage faculty and housestaff in the formal discussion of issues surrounding evaluation.


Profile-based assessment of student project reports.

During their final year, medical students at Sheffield University are required to undertake a research or audit project. The students' project reports are assessed using a grid-style criterion-based profile. This is described, and the validity and reliability of this method of summative assessment are discussed.


Weightage of formative examinations in certifying examination of pharmacology: an opinion poll and relative performance of learners.

A study was carried out to obtain the view points of 186 graduate students regarding formative examination, it's frequency, weightage in certifying examination, feedback about progress made or lack of it and the planning of learning activities. Majority of students were of the opinion that the class tests and tutorials should be conducted frequently and sufficient weightage of formative examinations should be given in the certifying examination. They were able to get feed back and plan out the learning activities accordingly. The performance in both theory and practicals of formative and certifying examinations in Pharmacology was analyzed. The average percentage marks secured by the students in both theory and practical of the certifying examination were higher than those secured in the formative examination. However, the reliability of theory examinations was more than the practical examinations. A positive correlation was observed between the marks of formative and certifying examination between theory as well as of practicals. The Pearson's Correlation Coefficient gamma was +0.932 and +0.715 while Spearman's rank order Coefficient rho was +0.792 and +0.649 for theory and practicals respectively suggesting positive and strong correlation.


The multiple choice true/false question: what does it measure and what could it measure?

Multiple choice questions of the true/false type are widely used in medical education. Evidence is given which suggests that they only tap a low level of intellectual skill. By using them in a slightly different manner it is suggested that they could be ideal techniques for measuring concept mastery. Some of the consequences of this idea are discussed.


Learning contracts in clinical education: evaluation by clinical supervisors.

Learning contracts can be a useful learning and evaluation tool within a clinical setting provided the supervisor shifts their role from one of imparter of knowledge to facilitator of learning. If this role is not assumed then a student's learning experience could be jeopardized. In a survey of 59 student supervisors, 90 percent found the learning contract to be a useful evaluation and teaching tool. Advantages stated suggest that the learning contract promotes negotiation between student and teacher, provides a flexible learning environment and promotes acquisition of self-directed learning skills. These qualities are important in a clinical or practical setting where learning experiences cannot be standardized.


The survival game.

This paper describes a flexible and enjoyable learning game and summarizes our experiences of using it (including the medical students' own evaluation of the game). The description is sufficiently detailed to encourage readers to reproduce and adapt the game to fit their own requirements.


Learning objectives in training residents in general surgery in Kuwait.

An opinion survey of a five-year postgraduate training programme in general surgery was conducted using a questionnaire. The residents who responded indicated that the use of learning objectives needed to be given greater emphasis. They felt that learning objectives should be more clearly defined and be communicated with the learners and the instructors at an early stage in the programme. While the opportunity for learning theoretical concepts in surgery was rated as a strong feature of the programme, learning practical skills, it was pointed out, needed augmenting.


Primary care residency programme evaluation: an analysis of three resident cohorts.

The purpose of this study was to conduct a longitudinal evaluation of a university primary care (PC) medical residency programme and use the results to plan for future curriculum development. Overall performance and the ambulatory medical care of three consecutive resident cohorts training from 1982 to 1987 was assessed by attending physicians. PC residents' performance in ambulatory continuity practice was also compared to that of traditional residents' performance in 1985-86. The scoring profile of primary care attendings was compared to that of other attendings. Residents received lowest scores in diagnostic evaluation, leadership and administration. Their best evaluations were in medical care, personal attributes and communication. Two of the three primary care cohorts received lower medical care scores in ambulatory continuity practice compared to other rotations, but had higher overall scores in ambulatory continuity practice than did traditional residents in 1985-86. Primary care attendings gave lower scores to primary care residents than did other faculty.


How I teach medical students as an attending physician.

The General Professional Education of the Physician (GPEP) Report (1984) recommended a major re-examination of the clinical clerkship, so that medical students could master the basic skills of medicine before graduation. These include clinical observation, interviewing, physical examination, and problem-solving skills. This essay discusses the teaching approach of one attending physician during the third year ward clerkship in pediatrics. It describes how many of the goals of clinical medical education can be accomplished during the clerkship in a practical, realistic way. It is the only description about what happens during the teaching sessions of a clinical clerkship on a day by day basis in the medical literature. This approach may serve as a model for clinical teachers of medicine in the organization and planning of the clerkship experience.


Does incourse assessment and counselling improve exist performance?

Based on an incourse MCQ test in obstetrics and gynaecology, 60 final year medical students were individually advised, according to their performance, whether or not they needed to work harder at the subject to avoid the risk of failure at the final medical examination. Nobody who performed well at the MCQ failed or was borderline at the final examination. Half of those who were advised to work harder occupied the lowest marks at the final examination. The incourse MCQ was sensitive in selecting out those candidates at risk in their final examination but the advice they were given failed to deal with the deficiencies in half of the students involved. After graduating, these doctors will presumably need special help to maintain their knowledge as they are either incapable of self-motivation or are otherwise deficient. The incourse assessment feedback may have helped another small groups of students to work harder but this study cannot confirm that. The exercise seems worthwhile in that the outlay in time is small, there may be a positive advantage for some students and the medical teacher can feel free of any guilt for failing to advise those students who were at risk of poor performance in the final examination.


[The stability of the properties of electroradiographic plates for medical x-ray diagnosis].

The properties of selenium electrocardiographic plates used for the purposes of medical diagnosis are under discussion. The plates are observed to reveal no noticeable traces of fatigue and to retain constant sensitivity to radiation and radiography in the case of the 5 to 10 minutes' interval between obtaining electroradiograms (ERG) during working hours (7 hours). After the technical resource which is equal to 2000 ERG is over, the radiation sensitivity decreases to 10% and defectiveness does not exceed 25%. The actual expiration date of the plates is between 7 and 9 years without worsening of their properties. The quality of the plates stored for a longer time might deteriorate due to the defect which is attributed to crystallization of the selenium layer.


[Leakage radiation from the RUM-17 x-ray apparatus outside the main beam].

The leakage radiation exposure rate was measured outside the main beam of the RUM-17 orthovoltage therapeutic x-ray unit by a 1000 cm3 ionization chamber. The results were corrected according to the detector volume averaging. It has been shown that the relative exposure rate normalized to the beam axis exposure rate does not depend on voltage and filter thickness. It can be represented by the same equation. The most important sources of non-used radiation are leakages from the shield (near the treatment cone connection) and scattering in the plexiglass window of the treatment cone.


[The EOL trainer for respiratory muscles].

A training equipment for respiratory muscles is suggested. It may create peak load at the initial phase of inspiration and expiration, thereby ensuring less fatiguability of respiratory muscles. The efficacy of the training equipment was estimated by clinical and instrumental methods in a group of 43 patients suffering from chronic bronchitis and compared to that of the throttle type trainer in 36 control patients. External respiratory function, acid-base balance and myocardial contractility were found to be significantly improved in the experimental group as compared to the controls.


[The use of a magnetically abrasive finishing for sharpening the blades of medical instruments].

The method of magnetically abrasive working was first tried in medical industry as a finishing operation for the sharpening and removing of burrs from half-finished blades manufactured by means of vibration forging. The use of the sets for MAO-M-473 and EU-5 makes it possible to manufacture blades with the cutting edge less than or equal to 3 microns in width. The use of magnetically abrasive sharpening enables one to eliminate electrochemical polishing; excludes the appearance of superficial defects on the worked surface; raises corrosion stability and cyclic longevity of the articles.


[An automated method of measuring the area of contrasted bronchi].

An automated method for measuring the area of the contrasted bronchi is described. The method involves two research stages. The first one consists of routine bronchography provided to patients suffering from pulmonary diseases according to indications. The second stage is reduced to the digital treatment of the bronchograms to measure the area of the contrasted bronchi. The method is used for the diagnosis of functional bronchial disorders. The bronchial area was measured on the bronchograms taken at the height of inspiration and expiration. Using the data obtained and the appropriate formula, the so called integral coefficient of bronchial constriction was calculated. It allows functional disorders of bronchial patency to be diagnosed and a quantitative expression of that pathology to be evaluated.


[Borderline pathology: follow-up study. Preliminary report].

The work is based on the frequent use of the term "borderline" in clinical practice, in spite of the fact that this word still tends to have a controversial and ambiguous meaning. Patients who were admitted to the Psychiatric Clinic at the University of Turin between 1974 and 1980 with diagnoses of borderline pathologies or marginal psychoneurosis were followed-up in the study. The subjects in question were reexamined after an interval of between 8 and 14 years (the majority between 10-12 years). An attempt was made to compare the two diagnoses using DSM III R criteria. Family status and employment were also taken into account. It was observed that the diagnosis of marginal syndromes recorded in the patient's clinical records did not correspond to the DSM III R borderline diagnosis, and rather than referring to a precise syndrome it reflected an area of diagnostic uncertainty. This raises various questions both with regard to the role of psychiatry, and in relation to the incidence of cultural factors in influencing observations.


[Problems of the design of turbine stomatologic tips with light guides].

The systems of turbine stomatologic tips with light guides for local illumination of the tooth area to be treated are analyzed. The basic problems that arise in the elaboration of such systems and the results obtained are specified. The technical characteristics of a halogen mini-lamp to be employed in turbine stomatologic tips are provided.


[Clinico-diagnostic criteria of hypochondriac syndromes].

The aim of this study was to examine the vast field of hypochondriac symptoms and to put forward diagnostic criteria following the analysis of recent studies on this topic. The "descriptions" based on DSM III trace a partial and selective picture of hypochondriac disorders which is only applicable to a small group of patients in which "somatic complaints" are emphasised in comparison to other less evident psychological variables. The symptom therefore becomes a sign of a pathology which is not defined according to the same complex of symptoms from which it arose. There is in fact no nosological model of hypochondria: we are only likely to meet a "potential hypochondriac" whose pathological expression is limited to part of the population.


Introduction: exercise and allergy.

At a time when the American public is committed to health through exercise, a variety of allergic conditions related to activity are being recognized with increasing frequency. Conditions such as cholinergic urticaria, bronchospasm, and even anaphylaxis have occurred as a consequence of exercise. Thus, a symposium has been developed to examine the role of exercise in association with such conditions. Several of the physical allergies are discussed in overview fashion. Exercise-induced anaphylaxis, the most serious form of allergic response to exercise itself, is considered in greater detail. The etiology, clinical features, and therapy for these physical allergies are addressed. Exercise-induced bronchospasm (EIB) has been well categorized in the literature. This is another exercise-related condition with an allergic component. The current concepts with respect to proposed etiology, epidemiology, and clinical features are discussed. EIB is an important condition to screen for, and techniques for identifying patients who should be screened are also addressed. Allergic rhinitis may also affect athletes. Accurate diagnosis and effective management of all these conditions may help greater numbers of people to enjoy the full benefits of exercise.


Physical allergies.

Allergic responses that occur as a result of exposure to physical stimuli are discussed. Most of these conditions are mediated by vasoactive substances, resulting in urticaria and/or angioedema. Susceptible individuals who engage in athletic activities may place themselves at particular risk for these problems. The physical allergies include cholinergic urticaria, exercise-induced anaphylaxis, cold urticaria, dermatographism, solar urticaria, and aquagenic urticaria. Management of these conditions includes patient education, selective avoidance, antihistamines, and, in some cases, induction of tolerance.


[Relationship between type A behavior and the other risk factors in chronic disease].

The relationship between psychological features and coronary heart disease (CHD) have long been investigated. Type A behaviour consists of psychological, behavioral and cognitive features and represents an important risk factor for CHD. The present report is a review of the international literature on the subject. In particular we have taken into account the relationships among type A and other risk factors and the possible biological mechanisms through which type A behaviour may promote CHD.


[Neuroleptic malignant syndrome].

The paper defines neuroleptic malignant syndrome and analyses its incidence, predisposing factors, etiology, pathological anatomy and pathogenetic hypotheses. Symptomatology consists of three principal symptoms: extrapyramidal symptoms, hyperthermia, deregulation of the autonomic nervous system. The differential diagnosis of other similar conditions is outlined together with a proposal for a treatment protocol. Emphasis is laid on the importance of prevention.


Exercise-induced anaphylaxis.

Exercise-induced anaphylaxis (EIA) is a unique form of physical allergy that has been recognized with increasing frequency in recent years. The hallmarks of this syndrome are generalized pruritus with a flushing sensation, a feeling of warmth, and the development of urticaria in association with vigorous physical exertion. These symptoms tend to occur variably with exercise, but not with passive warming. Most patients report typical giant urticarial eruptions. Skin mast cells degranulate, and serum histamine increases during symptomatic attacks. Treatment is often problematic, but cessation of exercise with onset of symptoms and self-administration of epinephrine are recommended.


[Evaluation of effectiveness and tolerance of the long-term treatment with bromoperidol decanoate in psychotic disorders].

An open study in 20 patients (7 M, 13 F, mean age 40 years) has been performed in order to evaluate the effectiveness and the safety of bromperidol decanoate in the long-term treatment of psychotic disorders. Patients were selected according to DSM-III-R diagnostic criteria (schizophrenia, residual type: 6 patients; disorganized type: 4; paranoid type: 5; undifferentiated type: 2; atypical psychosis: 3) and treated with bromperidol decanoate 150 mg i.m. (single administration) every month for 6 months. The BPRS scores significantly decreased at the end of the therapy with respect to the beginning (-39.5%; p less than 0.01 Friedman analysis between times); this improvement was already significant at the first month control. The results obtained from a clinical global impression, evaluated from the Visual Analogical Scale (VAS), showed that all patients improved at the end of the therapy (p less than 0.01 ANOVA between times). The side effects, mainly extrapyramidal ones, were mild and did not interfere with the therapy; in fact none patient dropped-out from the treatment. Bromperidol decanoate showed to have a good efficacy and safety in the therapy of psychotic disorders, with a stabilizing effect on the depressive mood.


Exercise-induced bronchospasm: epidemiology, pathophysiology, and therapy.

Exercise induced bronchospasm (EIB) is a common clinical problem seen in most individuals with chronic asthma and in nearly half the allergic population. Bronchospasm is typically present 5-15 min after cessation of activity, with spontaneous resolution usually occurring within 20-60 min. The stimulus for EIB is apparently a combination of airway cooling and drying, which results in pulmonary mast cell mediator release. Bronchospasm is generally more severe if there is greater baseline bronchial hyperreactivity or higher intensity of exercise. The treatment of choice for EIB is preexercise administration of a beta-adrenergic agonist. Other useful therapies may include cromolyn, theophylline, calcium channel blockers, anticholinergics, and antihistamines. The crucial step for clinicians caring for these patients is making the diagnosis of EIB. The condition responds well to therapy, and treatment may allow for greater enjoyment of activity and enhanced athletic performance.


[Discussion groups with chronic psychotics in the context of community therapy].

The paper describes the Authors clinical experience of "discussion groups" with psychotic patients. Attention is focused on the problems arising from the community therapy context, the general layout of the setting, the definition of objectives and methods, and in particular the attitude of group leaders.


[Nosographic problems and clinico-phenomenal characteristics of psychoses in epilepsy].

A critical analysis is made of the published reports on the epidemiologico-clinical and etiopathogenetic aspects of psychoses in epilepsy. Having underlined the principal characteristics of this pathology together with the main methodological and descriptive problems which emerge from the studies examined, the paper concludes by stressing the need for an approach based on a multifactorial understanding of the causes of these psychoses. In operative terms it is also necessary to evaluate the role of the predominant risk factors in each individual case.


Exercise-induced bronchospasm in the young athlete: guidelines for routine screening and initial management.

Exercise induced bronchospasm (EIB) commonly occurs several minutes into or following an exercise event. Respiratory heat loss and respiratory water loss have been suspected as the precursor to exercise-induced bronchospasm. Obstructive EIB has been reported in elite Olympic athletes as well as the recreational athlete. Although exercise-induced bronchospasm presents as wheezing, chest tightness, or dizziness during or after exercise, cough post-exercise is a common and an easily detected characteristic of EIB. When exercise induced bronchospasm is suspected in the young athlete, an exercise challenge test should be performed. A 10% or more decrease in the peak expiratory flow rate in the post-exercise period is diagnostic of EIB. Once the diagnosis of EIB has been made, both nonpharmacological and pharmacological interventions are beneficial in reducing the airway responsiveness. Nonpharmacological measures include extensive education and cardiovascular fitness evaluation. Initial pharmacological management should consist of a trial of albuterol inhaler use 15 min prior to exercise. Early identification and treatment of EIB may enhance sports performance as well as enjoyment.


Breathlessness predicts perceived exertion in young women with mild asthma.

We examined ratings of breathlessness (BRE) as a predictor of perceived exertion (RPE) during incremental cycling at power outputs of 50, 75, and 100 W. Young females (21 yr +/- 1.9) diagnosed with mild asthma (N = 25) were compared with females having normal lung function (N = 25) matched for age, VO2peak, trait anxiety, activity history (7-d recall), and BMI (kg.m-2). Relative oxygen consumption (%VO2peak), blood lactate concentration, VE.VO2(-1), and state anxiety were statistically controlled in hierarchical multiple linear regression analyses. For each group, %VO2peak explained 60% of the variance in RPE across power outputs (P less than 0.001); R2 was unchanged (P greater than 0.10) with the addition of blood lactate, VE.VO2(-1), and state anxiety. Absolute RPE and BRE did not differ between groups at any power output, but partial standardized (beta) and unstandardized (b) regression coefficients and increases in R2 showed that BRE had a greater effect (P less than 0.01) on RPE for asthmatics [adjusted R2 increased to 0.89; (beta) = 0.75; (b) = 0.79 +/- 0.06] than for controls [adjusted R2 increased to 0.74; (beta) = 0.52; (b) = 0.51 +/- 0.09]. The standard error of the prediction was 0.79 for asthmatics and 1.16 for controls. The prediction of RPE by BRE was not moderated by variation in forced expiratory volume for 1 s (FEV1), forced vital capacity (FVC) or peak inspiratory flow (VI). Physiological responses were similar for the groups, but blood lactate was higher in asthmatics at rest, at each power output, and at VO2peak.(ABSTRACT TRUNCATED AT 250 WORDS)


[First applications of a new projective-semantic test. Various considerations on standardization in a sample of adolescents].

Giuseppe R. Brera's B-test was used in a group of students from upper secondary school (102 male adolescents and 86 females) in order to carry out a preliminary standardisation in centiles and to assess the pattern of the seven scales of the test: mood, anxiety, interpersonal affectivity, sociability, autonomy of ego, strength of ego and guilt in adolescents. Factorial analysis by multiple correspondence was used in the same group of adolescents, with the exception of a subgroup of 20 14-year-old students from lower secondary school. The latter was carried out to assess the efficacy of the test in identifying groups of adolescents using the standard association of positive or negative methods of presenting the 44 variables and the free replies to the questions: what do you dream about, what do you look at, what do you advise. Standardisation in centiles allowed indicative risk scores for mental health to be defined for each factor, with the exception of the anxiety factor in males which appears to be a relatively widespread phenomenon in adolescent. Fewer adolescent females suffer from problems of depression, anxiety, interpersonal affectivity and sociability, whereas adolescent males present a smaller number of problems related to the autonomy of the ego, the strength of the ego and guilt. In line with previous works, the test identified 26% of adolescent males and 23% of adolescent females suffering from various in terms of the mean scores from the different factors. For the first time to our knowledge, multiple correspondence analysis identified nine groups of adolescents distributed along two factorial axes: 1 = mood, 2 = interpersonal affectivity. Groups 1 and 2 were characterized by being contrary to the other negative methods.(ABSTRACT TRUNCATED AT 250 WORDS)


Maternal respiration and blood gases during aerobic exercise performed at moderate altitude.

We studied whether maternal acid-base status during aerobic exercise performed at moderate altitude is affected by pregnancy. Seven primiparus women were tested at 37 wk gestation and 12 wk postpartum. Subjects were studied at rest, and during two cycle (50 W, 75 W) and two treadmill (67 m.min-1; 2.5% grade, 67 m.min-1; 12% grade) protocols. Exercise bouts lasted 6 min with a 10-min rest between sessions. Minute (VE) and alveolar (VA) ventilation, tidal volume (VT), and ventilatory equivalent for carbon dioxide (VE/VCO2) were significantly (P less than 0.01) greater when exercise was performed during pregnancy. Physiological dead space (VD) was not affected by pregnancy status and did not differ between rest and exercise. Decreases (P less than 0.01) in arterial pH during exercise averaged 0.04 units in both pregnancy and postpartum. Despite similar change in maternal pH, carbon dioxide tension (PaCO2) remained unchanged during exercise at 37 wk gestation but decreased at 12 wk postpartum. Decreases in arterial bicarbonate [HCO3-] associated with exercise were smaller during pregnancy. Our findings indicate that pregnancy did not compromise maternal acid-base status during aerobic exercise.


[Art therapy and chronic schizophrenia. Reflections on various aspects of social feelings and the creative self].

The Authors comment on the use of art therapy in a group of institutionalised chronic schizophrenic patients. The aim of these "group interventions" was to encourage the "feeling of belonging" and "creative participation". Artistic expression appears to represent an advantageous method of restoring communication to the schizophrenic.


Substrate oxidation and GH responses to exercise are independent of menstrual phase and status.

The purpose of this study was to determine the extent to which growth hormone (GH) and energy substrate utilization are influenced by basal sex steroid levels during prolonged submaximal exercise across menstrual phase and status. Also the 17 beta-estradiol (E2) and progesterone responses during prolonged exercise were compared according to menstrual phase and menstrual status. Six amenorrheic (AMc) athletes and seven eumenorrheic (EUc) athletes ran at 60% VO2max for 90 min and serial blood samples were taken at rest, every 10 min throughout exercise, and 5 and 15 min post-exercise. The EUc athletes were tested in the early follicular phase (EF) (days 3-5), the late follicular phase (LF) (days 14-16) and the mid-luteal phase (ML) (days 22-25). The incremental GH response to exercise, measured by area under the curve, was consistent with previous reposts and was not altered according to menstrual phase or status (EF-37.5 +/- 11.5, LF-61.9 +/- 11.5, ML-48.1 +/- 12.8 micrograms.1-1.90 min-1). Furthermore, carbohydrate and fat utilization during exercise were not influenced by basal sex steroid levels associated with menstrual phase or status. The incremental E2 response to exercise in AMc athletes was significantly smaller than seen in EUc athletes (AMc-208.1 +/- 44.0, EF-383.0 +/- 116.4, LF-204.7 +/- 84.1, ML-45.1 +/- 18.4 pmol.1(-1).90 min-1), although the pattern of release is similar between groups. In conclusion, GH levels and substrate utilization are independent of both menstrual phase and status; hence, menstrual phase has no negative ramifications on metabolism during exercise. Amenorrhea does not result in metabolic consequences during prolonged exercise by influencing substrate utilization.


A weight-lifting exercise model for inducing hypertrophy in the hindlimb muscles of rats.

A new method for strength-training of rat hindlimb muscles, comparable to human weight lifting, is compared with sprint training by a treadmill. The new training apparatus that can induce rats to perform human squats was designed. Squat training was composed of isotonic high-intensity, short-duration, and graded overload exercises. After 60 min of one bout of all-out squat and sprint training, serum creatine kinase activities were markedly increased in the squat group (P less than 0.001), but no significant changes were observed in the sprint group. These responses were reflected in the histological sections of the muscles. Some splitting and small fibers were observed only in the squat group, suggesting that different stimulations were applied to the muscles of both the squat and sprint groups. At the end of 12 wk of both types of training, performed 4-5 d.wk-1, the number of fibers in the plantaris muscles of the squat group was greater by 14% than that in the control and sprint groups (P less than 0.001), suggesting hyperplasia following hypertrophy. These results indicated that the muscle strength-training model presented here may provide a new insight into the muscle hypertrophy associated with hyperplasia induced by heavy resistance training.


Adrenergic responsiveness and intrinsic sinoatrial automaticity of exercise-trained rats.

The purpose of this study was to test the hypothesis that bradycardia in exercise-trained rats results from decreased intrinsic automaticity of the sinoatrial (SA) node and/or alterations in the responsiveness of the beta-receptors of atrial pacemaker cells. Male Sprague-Dawley rats were divided into exercise trained (ET) and sedentary (SED) groups. ET rats underwent a 12-16 wk program of progressive treadmill training, during which time the SED rats were cage confined. In vivo, resting heart rates were significantly less (P less than 0.05) in ET rats (301 +/- 8 bpm) compared with the SED group (320 +/- 6 bpm). In vitro experiments were conducted on atria isolated from ET and SED rats, and the beta-adrenoceptor agonist isoproterenol was used to investigate cardiac adrenergic control of chronotropic mechanisms in spontaneously beating right atria and inotropic mechanisms in electrically paced (1 Hz) left atria. There were no significant differences between ET and SED cardiac preparations in either the efficacy (maximal response) or potency (EC50) of isoproterenol dose-response relationships for chronotropic or inotropic responses. Intrinsic right atrial beating frequency, measured in the presence of beta-adrenoceptor block by propranolol and cholinergic muscarinic block by atropine, was lower in ET rats. We conclude that training-induced bradycardia in rats is related, at least in part, to alterations in intrinsic automaticity of SA nodal pacemaker tissue, but does not appear to be associated with changes in the properties of the beta 1-adrenoceptors or their affiliated signal transduction mechanisms in either SA pacemaker cells or atrial myocytes.


The effects of smokeless tobacco on performance and psychophysiological response.

The effects of smokeless tobacco (ST) on psychophysiological response and performance were examined in two studies. Study 1 compared heavy and moderate ST users on psychomotor tasks (simple reaction time/anticipation time and choice reaction time/movement time) in ST (2 g amount) and no smokeless tobacco (NST) conditions. Moderate users performed significantly better than heavy users; there were no significant psychomotor performance differences comparing ST/NST conditions. Heart rate and blood pressure were elevated equally for both groups with the use of ST. Heavy users reported significantly less state anxiety in both ST and NST conditions than moderate users. Study 2 replicated the psychomotor performance results of study 1 when comparing nonusers and ST users who were given four dose amounts of ST (NST, 1/3 mean dose, mean dose, and 5/3 mean) over 4 d. For the math and Stroop tasks, ST use resulted in 12.1% and 10.4% better performance than the NST condition. Physiological measures showed significant elevations during the ST conditions. No differences between dose amounts of ST were apparent for any of the measures. These studies demonstrate that ST users perform better than nonusers when having to react to cognitively challenging task situations.


Failure to generalize determinants of self-reported physical activity to a motion sensor.

We hypothesized that the prediction of physical activity from psychological determinants would differ when free-living physical activity was assessed by electromechanical or self-report methods. We assessed outcome-expectancy values and perceived barriers for physical activity (OE Values/P Barriers) and physical self-efficacy in 44 young (24 yr +/- 4.8) Caucasian men (N = 13) and women (N = 31). Two weeks later, subjects kept a daily diary and wore a Caltrac motion sensor during all ambulation for seven consecutive days. Reliability (PI) across days was high for MET.h of activity estimated by the diary (0.82) and for Caltrac counts (0.87). Canonical correlation analysis yielded one significant linear combination (Rc = 0.55, P less than 0.01; redundancy = 0.19 to 0.24) of the set of psychological variables [OE Values/P Barriers (beta = 0.76) and physical self-efficacy (B = 0.33)] and the set of physical activity estimates [7-d diary (B = 0.89) and Caltrac (beta = 0.24)]. Multiple correlations indicated that the linear combination of OE Values/P Barriers and physical self-efficacy explained 26% of the variation in MET.h reported in the 7-d diary (P less than 0.01) but was unrelated to Caltrac counts (P greater than 0.05). The strongest bivariate model included the 7-d diary and OE Values/P Barriers (r = 0.51, P less than 0.01). Caltrac counts were weakly related to OE Values/P Barriers (r = 0.34, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)


Effect of manipulation of plasma lactate on integrated EMG during cycling.

This investigation was undertaken to record electromyographic activity of the vastus lateralis muscle during incremental cycling exercise and to determine whether it would be sensitive to altered dynamics of plasma lactate increases seen with intense exercise. Trained cyclists (N = 6) performed two progressive, stepwise exercise tests (23.5 W.min-1) to fatigue on a cycle ergometer at 90 rpm. One of the exercise tests was preceded by arm ergometer exercise in an attempt to elevate the circulating plasma lactate levels prior to starting the criterion exercise test. The starting mean plasma lactate values were 4.59 and 26.69 mmol lactate.-1 for the two exercise sessions. Cardiorespiratory values did not differ significantly between exercise sessions completed in the absence and presence of increased circulating plasma lactate. The no-arm trial (i.e., nonelevated plasma lactate condition) was associated with a plasma lactate inflection point (Tlac) at 72.6% VO2max. Previous arm exercise elevated the lactate such that during the criterion exercise plasma lactate values were decreasing with increasing power output at lower exercise intensities. As exercise intensity increased lactate values also increased beginning at a power output of about 76% VO2 max. Mean per cycle integrated EMG (CIEMG) increased linearly with increased power output in both exercise sessions. The slopes of the EMG-power output curve were not significantly different (P less than 0.05). There were no inflection points in these curves. The absence of an inflection point show that surface EMG does not provide an indication of Tlac.


Propulsive and gliding phases in four cross-country skiing techniques.

The purpose of this study was to compare the relative durations of the propulsive and gliding phases between three skating techniques (1-skate, 2-skate, and offset) and the diagonal stride technique in elite cross-country skiers. Nine skiers of provincial and national level were videotaped with a Panasonic AG 170 camera. The camera speed was set at 30 frames.s-1 and the shutter speed at 1/500 s. The athletes were asked to ski at approximately 80% of their maximal skiing speed on a flat (50 m long) and on an uphill course (35 m long, 5 degrees grade). The relative propulsive phases of the skating techniques were significantly longer than those of the diagonal stride. The relative gliding phases were also longer with the skating techniques. In addition, velocities obtained while skiing with the diagonal stride were about 16% slower than those attained with the skating techniques, principally related to the longer cycle lengths observed with the skating techniques, while cycle rates were quite similar between all four techniques. The results of this study suggest that the longer relative phases of propulsion with the skating techniques may explain the greater speed attained with these techniques in comparison with the diagonal stride.


Strength after bouts of eccentric or concentric actions.

This study examined the influence of an initial bout of eccentric or concentric actions and a subsequent bout of eccentric actions on muscular strength. Twenty-four healthy males, 24-45 yr old, were placed in three groups that performed eccentric actions in bouts 1 and 2 (ECC/ECC, N = 8), concentric actions in bout 1, and eccentric actions in bout 2 (CON/ECC, N = 8) or served as controls (N = 8). Bouts involved unilateral actions with the left and right quadriceps femoris. Ten sets of 10 repetitions with an initial resistance equal to 85% of the eccentric or concentric one repetition maximum (1 RM) were performed for each bout. Three minutes of rest were given between sets and 3 wk between bouts. Two weeks before bout 1 and 1, 4, 7, and 10 d after bouts 1 and 2, eccentric and concentric 1 RM were measured for the right quadriceps femoris and a speed-torque relation established for the left quadriceps femoris. Eccentric and concentric 1 RM decreased (P less than 0.05) 32% 1 d after bout 1 for group ECC/ECC. The speed-torque relation was down-shifted (P less than 0.05) 38%. Eccentric 1 RM and eccentric and isometric torque returned to normal 6 d later. Concentric 1 RM and torque at 3.14 rad.s-1 had not recovered on day 10 (-7% for both, P less than 0.05). Decreases in strength after bout 2 for group ECC/ECC only occurred on day (-9% for concentric 1 RM and 16% downshift of the speed-torque relation).(ABSTRACT TRUNCATED AT 250 WORDS)


Carbohydrate-electrolyte replacement improves distance running performance in the heat.

The effects of a 7% carbohydrate-electrolyte drink (CE) and an artificially sweetened placebo (P) on performance and physiological function were compared during a 40-km run in the heat. Eight highly trained male runners completed two runs on a measured outdoor course. The first 35 km of each run was performed at self-selected training pace and the last 5 km at race effort. Under a counterbalanced, double-blind design, subjects consumed 400 ml of either CE or P 30 min prior to exercise, and 250 ml every 5 km thereafter during the run. Rectal temperature, heart rate, rating of perceived exertion, sweat rate, and respiratory exchange ratio were similar during the run for CE and P. Serum Na+, K+, Cl-, total protein, osmolality, blood lactate, urea nitrogen, and % change in plasma volume were also similar for both drink conditions; however, blood glucose was significantly higher (P less than 0.01) with CE. Running performance in the last 5 km was significantly faster (P less than 0.03) during CE (21.9 min) compared with P (24.4 min). Subjects reported no differences in stomach upset, bloating, or nausea between P and CE. Results indicate that CE replacement elicits similar thermoregulatory and physiological responses during prolonged running in the heat but increases run performance and blood glucose when compared with P.


Validity of a cardiorespiratory fitness test for men with mental retardation.

The purpose of this study was to validate a field test of cardiorespiratory fitness for men with mental retardation. The subjects were 19 healthy young men (26 +/- 6 yr) with moderate mental retardation (IQ = 48 +/- 11). Each subject underwent a maximal treadmill test after a three-phase familiarization process. Each subject also completed a 1-mile walk test twice (Rockport Fitness Walking Test = RFWT). The correlation coefficients between peak VO2 on the treadmill and the two 1-mile walks varied from 0.78 to 0.83. When weight, height, age, heart rates of 1-mile walks, and their combinations were held constant, the correlations were strengthened. Using multiple correlation analysis the best equation for predicting peak VO2 was: Peak VO2 = 101.92 - 2.356(mile-1 time) - 0.42(weight). This model accounted for 85% of total variance. The standard error of estimate was 4.06 ml.kg-1.min-1. The test-retest reliability of the RFWT for the 19 subjects used in this study was very high (R = 0.97). This finding suggests that the RFWT is a valid and reliable field test for this population and appears to be a valid indicator of cardiorespiratory fitness for these men with mental retardation.


A comparison between two forms of aerobic dance and treadmill running.

Aerobic dance has been reported to result in a disproportionately higher heart rate than running at a similar percent of VO2max. It has been suggested that the extensive use of the arms overhead during aerobic dance results in an increase in sympathetic outflow thereby disproportionately increasing the heart rate. To compare the hemodynamic and sympathetic nervous system activity responses during aerobic dance and treadmill running, nine healthy females exercised at approximately 50% of their VO2max during each of the following three exercise trials: aerobic dance where the arms were used extensively overhead (ABOVE), aerobic dance where the arms were kept below the shoulders (BELOW), and treadmill running (TR). Mean heart rate values during the ABOVE, BELOW, and TR trials were 136 beats.min-1 for all three trials. Mean VO2 values during the ABOVE, BELOW, and TR trials were 1.48, 1.51, and 1.47 l.min-1, respectively, and were not significantly different. Mean cardiac output for the ABOVE, BELOW, and TR trials were 13.5, 14.0, and 13.0 1. min-1, respectively, and were not significantly different. Postexercise blood lactate and norepinephrine values were not significantly different among the three trials. These results suggest a similar relationship between heart rate and VO2 during low intensity aerobic dance and running and do not support the contention that the use of the arms overhead during aerobic dance exercise elicits a disproportionately greater increase in heart rate as compared with running. Additionally these results demonstrate similar cardiovascular and sympathetic nervous system responses between aerobic dance exercise and running.


Scientific basis of competitive cross-country skiing.

The sport of cross-country skiing had its origins as a utilitarian mode of travel more than 4000 yr ago. From hunters carrying weapons and moving about on carved wooden skis, the sport has evolved to spandex-clad competitors carrying reinforced fiberglass poles while gliding on high-tech composite skis. The widespread use of ski-skating techniques coupled with the technological innovations of the last decade have profoundly changed the nature of competitive cross-country skiing. This symposium is intended to summarize the current state of scientific knowledge about the sport.


Mechanical constraints on Nordic ski performance.

Skiers, coaches, and sports scientists must work within mechanical constraints to improve performance. If Nordic skiing is to be improved by mechanical means, it will be achieved by affecting one or more of the major constraints: gravity, mass, friction, aerodynamic or hydrodynamic lift and drag, and centripetal force. For example, the skier who assumes a tucked position, drafts a competitor, and wears a drag-reducing hood and body suit is reducing aerodynamic constraints. Sliding friction may also be reduced by using specially prepared skis and by selecting skis appropriate for the snow characteristics of the race course. Skin friction hydrodynamic drag may also be affected by ski selection and by special base preparations. Gravity and mass constraints are diminished by using lightweight components, by carrying them in the least costly way, and by minimizing swing weight. The toppling effect of centripetal forces is addressed by leaning into turns. All of these examples address mechanical constraints in a way that reduces physical power requirements, and thus decrease the metabolic power required to ski at a given speed, as well as increasing the maximal speed attainable.


Biomechanical analysis of cross-country skiing techniques.

The development of new techniques for cross-country skiing based on skating movements has stimulated biomechanical research aimed at understanding the various movement patterns, the forces driving the motions, and the mechanical factors affecting performance. Research methods have evolved from two-dimensional kinematic descriptions of classic ski techniques to three-dimensional analyses involving measurement of the forces and energy relations of skating. While numerous skiing projects have been completed, most have focused on either the diagonal stride or the V1 skating technique on uphill terrain. Current understanding of skiing mechanics is not sufficiently complete to adequately assess and optimize an individual skier's technique.


Physiological comparisons of cross-country skiing techniques.

Since the popularization of ski skating, several investigations have compared the physiological responses of various cross-country skiing techniques. While this work is incomplete in fully characterizing the relative physiological demands of the different skiing techniques, some conclusions can be made. The diagonal stride technique is the least economical technique for skiing on flat ground. The magnitude of the difference in economy between the diagonal stride and skating techniques for skiing on flat terrain compares well with the 10-30% faster race velocities with the skating techniques. Nevertheless, it appears that the heart rates, blood lactate concentrations and perceived efforts elicited at a given oxygen uptake are similar between the diagonal stride and skating techniques. Therefore, the cardiorespiratory training benefits from classical skiing and ski skating should be similar if performed at the same heart rates or perceived efforts. Several studies have demonstrated that the double pole technique is the most economical cross-country skiing technique on flat terrain. Extended use of the double pole technique, however is probably limited by its greater anaerobic demands.


Influence of body mass on cross-country ski racing performance.

The influence of body mass on cross-country skiing performance was evaluated by (i) a theoretical analysis of the relationship between body mass (M) and on one hand the maximal aerobic power and on the other the power expense of skiing, (ii) timing skiers in varied terrain during ski racing, (iii) comparing racing success between light and heavy skiers, and (iv) relating maximal aerobic power of skiers and power expense of skiing to body mass. The theoretical analysis indicated that the maximal aerobic power scaled with M2/3, while the mass exponent for the power expenses ranged from 1/3 to 1. The net result was that heavy skiers appear to be favored in all types of terrain but the steep uphills. During ski racing, heavy skiers displayed a tendency to be faster in all types of terrain, although no statistically significant effect was found. The racing success tended to be greater in heavy skiers among males but not among females. During skiing, maximal aerobic power and the power expense of skiing scaled with M0.7 and M0.4, respectively, indicating an advantage for the heavy skier. Altogether, these observations indicate that heavy skiers are favored, but also that other factors are more important than body mass for cross-country ski racing performance.


Development of aerobic power in relation to age and training in cross-country skiers.

In most of the training studies on different populations the effects of training have been investigated up to a frequency of five to six times per week and a duration of 45 min per session. These correspond to the training regimens of 15-yr-old cross-country skiers and, consequently, the results cannot be applied to older athletes. The maximal oxygen uptake (VO2max) of cross-country skiers increases with age and training from about 55-60 to 75-80 ml.kg-1.min-1 between 15 and 25 yr of age. After 20 yr of age VO2max starts to level off, but elite skiers are able to increase VO2max further concomitantly with an increase in the volume of training and the volume of intensive training. The activity of oxidative enzymes in muscles of skiers is increased with training, but distance runners have had a higher oxidative capacity in their leg muscles. Although widely used by cross-country skiers, the training effects of roller skiing, skiwalking-skistriding, and long-distance training on skis are to a large extent unknown. However, intensive training at the intensity of "anaerobic threshold" or higher seems to be most effective in inducing improvements in maximal oxygen uptake; distance training at relatively low intensity seems to be most effective in producing improvements in the determinants of submaximal endurance.


Technological advances in cross-country ski equipment.

Nordic skiing has a long history dating back to at least 2500 B.C. It is not surprising then that skiing equipment has undergone many changes. Today's skis, poles, and boots use the latest in space-age synthetics including carbon and Kevlar fibers, which has resulted in an unprecedented advance in ski equipment technology, producing ultralight yet strong equipment. These changes have played an important role in bringing about an improvement in racing performance with today's skiers being able to ski a course in half the amount of time that it would have taken just 60 yr ago. Estimates indicate the change in mass of racing equipment accounts for a relatively small amount (12%) of the improvement in race performance with changes in the functional characteristics of equipment, track preparation, and training practices being responsible for the remaining 88%. In addition to improvements in ski equipment, advances are being made in developing laboratory equipment used to assess an athlete's upper body power and endurance capacities. Lab testing with an arm ergometer showed its utility when it exposed a glaring deficiency in upper body power among a group of U.S. developmental skiers. Further improvement in ski equipment and lab testing tools are expected in the future as the worldwide technological revolution continues and Olympic Teams and sports science groups continue to work cooperatively.


Factors affecting the oxygen cost of stepping on an electronic stepping ergometer.

The purposes of this study were to evaluate (a) the effects of step rate and upper body support on the VO2 and HR responses to fixed work rates on the StairMaster 4000 (SM), (b) the accuracy of the SM settings, and (c) how HR compared with that measured during grade-walking on a treadmill. Six subjects worked at a slow step rate for 6 min and then a faster step rate for the last 6 min of a 12-min test at SM settings of 4, 7, and 10 METs. Gas exchange and HR measurements were made at minutes 4-6 and 10-12. Variations in step rate had no effect on HR (P = 0.45) or VO2 (P = 0.84). The effect of using the arms and hands for support was studied using 6 subjects who worked for 12 min at 4, 7, and 10 METs; the first 6 min without support, and the second 6 min with support. Support resulted in lower HR (P = 0.017) and VO2 (P = 0.002) values at 10 METs. The measured MET values were about 20% lower than those specified by machine settings: True MET values = 0.556 + 0.745 (SM setting). Finally, at the same VO2, systematically higher (7-11 b.min-1) HR values were observed for the SM relative to the treadmill.


The effect of trial size on statistical power.

Many research studies produce results that falsely support a null hypothesis due to a lack of statistical power. The purpose of this research was to demonstrate selected relationships between single subject (SS) and group analyses and the importance of data reliability (trial size) on results. A computer model was developed and used in conjunction with Monte Carlo procedures to study the effects of sample size (subjects and trials), within- and between-subject variability, and subject performance strategies on selected statistical evaluation procedures. The inherent advantages of the approach are control and replication. Selected results are presented in this paper. Group analyses on subjects using similar performance strategies identified 10, 5, and 3 trials for sample sizes of 5, 10, and 20, respectively, as necessary to achieve statistical power values greater than 90% for effect sizes equal to one standard deviation of the condition distribution. SS analyses produced results exhibiting considerably less power than the group results for corresponding trial sizes, indicating how much more difficult it is to detect significant differences using a SS design. These results should be of concern to all investigators especially when interpreting nonsignificant findings.


Stress fractures in young athletic women: case reports of unsuspected cortisol-induced osteoporosis.

Stress fractures in the female athlete are common events, usually occurring in the lower limb and less often in the pelvic girdle. Two cases are presented of young women athletes who presented with initial lower limb stress fractures, but subsequently fractures of the pelvis and hip thought to be associated with their athletic activity. After careful medical evaluation, they were diagnosed with Cushing's syndrome. One patient had a microadenoma of the pituitary gland secreting excessive amounts of ACTH, and the other had a benign adenoma of the left adrenal gland. Both women had significant decreases in their spinal mineral density. After treatment, partial reversal of these spinal losses occurred. Although stress fractures in the female athlete might be common and thought to be associated with problems of amenorrhea, presentation of unusual anatomical sites for these fractures necessitates a more thorough evaluation for correctable secondary causes.


Thigh compartment syndrome in a football athlete: a case report and review of the literature.

Although contusions of the thigh are common in all sports, a compartment syndrome from closed blunt trauma without a femur fracture is rare. Thigh compartment syndrome is unusual due to increased compliance of the thigh to accommodate increased expansion from hematoma or third space fluid. Compartment syndrome of the thigh is characterized by unrelenting pain, swelling, and limited knee range of motion. A single case of a thigh compartment syndrome caused by a direct blow to the anterior aspect of the thigh from a football helmet during kickoff occurred. Immediate thigh fasciotomy was performed. Early diagnosis with appropriate emergency treatment can avoid serious and permanent complications.


Etiology of low back pain in elite boardsailors.

Seven elite boardsailors reporting nonradiating low back pain without leg pain during sailing volunteered for detailed examination. In these subjects, the onset of pain was limited to those occasions when sailing positions were held for a significant period of time, e.g., close hauled sailing or in light winds. No pain was described at any other time. The determination of possible antecedent factors was based on the results of clinical assessment, radiological evaluation, and computer tomography (CT) scanning. Apart from limited flexibility in some subjects, the clinical examination of these athletes was normal; CT changes in this group were limited to disc protrusions and bulges, and pars interarticularis defects. Despite the small number of subjects in the present report, it appears that the frequency of these problems exceeds that in the normal population. It may be possible to suggest that risk factors such as body position during prolonged sailing, particularly under light wind conditions without a harness, and limited flexibility may be associated with the radiological findings and may be implicated in the presence of low back pain, although further investigations appears warranted.