DNA-cytophotometry of lymph node imprints from patients with mycosis fungoides.

To obtain objective criteria for early diagnosis of lymph node involvement in patients with mycosis fundoides, Feulgen DNA-cytophotometry was carried out in lymph node imprints from patients with mycosis fungoides. The lymph nodes of 3 patients with lymph nodes, showing partial or total replacement by atypical lymphoreticular tissue histologically, showed a polyploid and aneuploid DNA distribution. Eleven out of 22 patients with dermatopathic lymphadenopathy both with or without early involvement histologically had an abnormal DNA histogram with hypertetraploid DNA values. Four of these 11 died, 5 had a partial remission in response to therapy and 2 had sustained remission during the follow-up period of 5 yr. The other 11 patients had a normal DNA distribution. Of these 11, one died and 10 achieved sustained remission after therapy. There is a good correlation between the DNA-cytophotometric results and histology of the lymph nodes. On the basis of these results DNA-cytophotometry may be considered an additional and objective aid in the diagnosis of lymph node involvement in mycosis fungoides.


Comparison of eumelanogenesis and pheomelanogenesis in retinal and follicular melanocytes; role of vesiculo-globular bodies in melanosome differentiation.

Vesiculo-globular bodies, 40 nm in diameter, are present in melanosomes. The mode of their involvement in melanosomal differentiation was studied by ultrastructural comparison of eu- and pheomelanogenesis occurring in retinal and follicular melanocytes. We found that the number and distribution of these bodies differ significantly with types of melanogenesis and tissues. They were not affected by physical stimuli nor by embryonic origin of melanocytes. The earliest form of melanosomes is identical in eu- and pheomelanogenesis. The vesiculo-globular bodies are involved in organization of melanosomal constituents. In eumelanogenesis, they are more numerous in feather than in retina and hair. They are least numerous in white hair and pink eyes where melanization is blocked. During melanosomal development, they become associated with melanosomal inner lamellae and their outer surface becomes melanized, but their core is hardly melanized, thus leaving small vesicular structures. In pheomelanogenesis, their number is almost equal in feather and hair. Lamellae are not formed, but these bodies fuse with each other to form an amorphous matrix on complete differentiation of melanosomes.


Multiple forms of epidermal alpha-fucosidase.

Two forms of alpha-fucosidase from newborn rat epidermis were separated by gel filtration on Sephadex G-150. These enzymes termed, fucosidase I which was eluted in the void volume and fucosidase II (molecular weight approximately 50,000). Both enzymes had pH optima for 4-methylumbelliferyl-alpha-L-fucoside hydrolysis between 5.5-6.5. Km values for fucosidase I and II with the same substrate were 3.7 X 10(-5) and 5.4 X 10(-5) M, respectively. Three different forms of new born rat epidermal alpha-fucosidase were separated by isoelectric focusing. Evidence is present which indicates that the electrophoretic heterogeneity of alpha-fucosidase is due in part to the binding of sialic acid to the primary gene product.


Kinin-forming enzyme in human skin: the purification and characterization of a kinin-forming enzyme.

A kinin-forming-enzyme in human skin extract was further purified by successive column chromatography on DEAE-cellulose, Hydroxylapatite-cellulose and Sepharose-4B. By these procedures, 2.7 mg of purified enzyme was obtained from 10 gm of original skin. The purified material was homogeneous as ascertained by cellulose acetate membrane electrophoresis, sodium dodecyl sulfate polyacrylamide gel disc electrophoresis and ultracentrifugation. It had an S20,w value of 4.3 and an apparent molecular weight of 104,000 as measured by gel filtration on Sephadex G-200. The purified enzyme was comparatively heat-stable, but was unstable below pH values of 5 and above pH 9. It possessed arginine or lysine esterolytic activity, but not tyrosine or tryptophane esterolytic activity and denatured proteolytic activity. This enzyme was not affected by metal ion, cystein, glutathion or rho-chloromercuribenzoate, but was strongly inhibited by alpha-N-rho-tosyl-L-lysine chloromethyl ketone or soybean-trypsin inhibitor. It was also inhibited by alpha 1-antitrypsin, but not by alpha 2-macroglobulin. This enzyme was confirmed to be immunologically distinct from human plasma, urinary or pancreas kallikrein.


The determination of lipids and proteins in suction blister fluid.

The concentration of 5 different proteins in suction blister fluid and serum was determined by immunotechniques. These proteins, varying in size and molecular weight (6,600-2,300,000) were insulin, albumin, high density lipoprotein determined as apoprotein A-I, alpha 2-macroglobulin and low density lipoprotein measured as apoprotein B. The difference in the blister fluid/serum concentration ratio of the proteins was dependent on the molecular weight and followed mainly the law of diffusion. Moreover, the amounts of insulin, albumin and apoproteins A-I and B in suction blister fluid were the same as those reported in peripheral lymph. The results indicate that the sieve function of the capillary basement membrane remains intact during the formation of the suction blisters. Suction blister fluid might therefore be regarded as representative of interstitial fluid. The concentrations of 4 different lipids (cholesterol, cholesterolesters, triglycerides and phospholipids) were also determined and their blister fluid/serum concentration ratio proved to have a fairly constant value of 0.25.


Local and systemic effects on the epidermal melanocyte population in UV-irradiated mouse skin.

Local and systemic effects of repeated UVB irradiation on the epidermal melanocytes have been studied in the C57Bl mice. A daily dose of 0.1 joule/cm2 for 10 days induced a 4-fold increase in the epidermal melanocyte population of the irradiated right ear. During the first weeks after the irradiation period, there was a gradual increase in the number of melanocytes also in the shielded left ear, up to about 3 times the age control values. Thereafter, the population density slowly decreased in both ears, but it remained well above original values as late as 20 weeks after the irradiation. Thus, a short UVB irradiation period induces a long-lasting increase in the number of epidermal melanocytes in irradiated skin areas, as well as in covered skin regions. It is suggested that the population increase in the shielded ear is initiated by one or more systemic factors originating from the UVB irradiated skin. Such factors may be involved in the regulation of a balanced melanocyte population over the entrie body surface.


Immunization of pregnant women with influenza A/New Jersey/76 virus vaccine: reactogenicity and immunogenicity in mother and infant.

The safety and immunogenicity of inactivated influenza virus vaccines in pregnant women have not been adequately investigated. In this study, 56 women received inactivated influenza A/New Jersey/76 virus vaccine during the second and third trimesters of pregnancy. No significant immediate reactions or increased fetal complications were associated with administration of the vaccine. The antibody response of the pregnant women to the vaccine was similar to that of nonpregnant adults. Forty mother-infant pairs were available for antibody surveillance. At delivery, reciprocal antibody titers of greater than or equal to 20 were present in 11 (42%) newborn (cord) sera and 15 (58%) maternal sera. Three months later, sera from only three infants (12%) contained this level of antibody. At six months, the serum of only one infant contained this level of antibody. At six months, the serum of only one infant contained detectable antibodies. Levels of passively transferred antibodies from prior maternal infection with influenza A/Victoria/75 virus also declined rapidly following birth. It is possible that immunization of pregnant women can provide sufficient protection of the newborn infants by transfer of antibodies through the placenta if (1) a more potent influenza vaccine, possibly used with booster dosing, is administered, and (2) the women deliver just prior to or during the influenza season.


HLA-linked genes and leprosy: a family study in Karigiri, South India.

The evidence for a genetic determination of susceptibility to leprosy is reviewed. To test the hypothesis that an HLA (histocompatibility leukocyte antigen)-linked gene is associated with such susceptibility, the association between the distribution of leprosy within a family and the segregation of HLA haplotypes was investigated among 72 families who lived in Karigiri, Tamil Nadu State, South India. A statistically significant association was found for families in which siblings had tuberculoid leprosy and in which neither parent had leprosy. The findings from the data of this study agree with those of two previous studies carried out among smaller populations is Surinam and Wardha, Maharashtra State, India. Such an agreement suggests that a genetic determinant which is linked to the major HLA locus on chromosome 6 and which is probably recessive affects susceptibility to tuberculoid leprosy in humans.


Immune responses of humans to a human diploid cell strain of rabies virus vaccine: lymphocyte transformation, production of virus-neutralizing antibody, and induction of interferon.

Lymphocyte transformation, production of neutralizing antibody, and interferon activity of 20 healthy volunteers in response to a human diploid cell strain (HDCS) of rabies virus vaccine were studied. Ten vaccines received 1.0 ml of HDCS vaccine on days 0, 3, 7, and 14, and five of these volunteers received, in addition, 20 international units of human rabies immune globulin/kg of body weight on day 0. All 10 volunteers developed high titers of neutralizing antibody, and eight of the 10 had lymphocytes that were immunologically stimulated by HDCS rabies virus antigen. The interferon responses of eight vaccines to 1.0 ml of HDCS vaccine given intramuscularly on days 0 and 28 and of two vaccines to 1.0 ml of vaccine given intradermally in eight body sites on the same days were measured; low levels of interferon-like activity were found in eight of nine volunteers after the first vaccination, and no activity was found upon revaccination. The high titers of neutralizing antibody that developed did not correlate with lymphocyte stimulation or interferon-like activity, but it is true that all 20 volunteers did develop high titers of neutralizing antibody after 1.0 ml of HDCS vaccine was given intradermally.


Selection of small-colony variants of Enterobacteriaceae by in vitro exposure to aminoglycosides: pathogenicity for experimental animals.

Small-colony variants of gram-negative genera of Enterobacteriaceae were selected by in vitro exposure to gentamicin. These variants were shown to have decreased susceptibility in vitro to aminoglycosides. They were lethal for mice following intraperitoneal injection, with the LD50 (50% lethal dose) being the same as, or slightly less than, that for the parent organism. Variants of strain no. 2401 of Proteus mirabilis caused urinary tract infection in mice after implantation into their bladders. Although the variants grew somewhat less rapidly than did parent organisms, both parent and variant colonies alkalinized urine at the same rate. Electron microscopic study showed no differences between colonies of parents and variants. These studies indicated that small-colony variants of Enterobacteriaceae are pathogenic for experimental animals. Further, they may cause disease in humans and should not necessarily be regarded as only laboratory curiosities.


Ultrastructural observations on giardiasis in a mouse model. II. Endosymbiosis and organelle distribution in Giardia muris and Giardia lamblia.

Ultrastructural observations of Giardia muris in a mouse model revealed endosymbiotic microbes not previously reported in Giardia. Endosymbionts 240--360 nm wide, 600--1,400 nm long, and with an internal structure similar to that of bacilli were not seen entering Giardia but were found and appeared to divide within Giardia. No evidence was found of digestion of the endosymbionts by the giardia host in either the trophozoite or the cyst form. Endosymbionts were concentrated centrally around the nuclear area and were uncommon in peripheral feeding regions. The same cellular organelles seen in G. muris were found in Giardia lamblia from human jejunal biopsy material, but no endosymbionts were identified in G. lamblia trophozoites from the seven patients examined. Endosymbionts within Giardia may be found to alter trophozoite pathogenicity, metabolism, range of infectivity, antigenic surface characteristics, and host specificity, as they do in other protozoa.


Comparison of responses to influenza A/New Jersey/76-A/Victoria/75 virus vaccine administered intradermally or subcutaneously to adults with chronic respiratory disease.

Serum HAI (hemagglutination inhibition) antibody responses were compared in two groups of 70 age-matched patients (age range, 17 to 82 years) who were vaccinated with bivalent influenza A/New Jersey/76-A/Victoria/75 whole-virus vaccine. The group that was vaccinated intradermally received 40 chick cell-agglutinating units of each viral antigen in 0.1 ml, and the group that was vaccinated subcutaneously received 200 chick cell-agglutinating units of each antigen in 0.5 ml. The serum HAI antibody response to A/New Jersey/76 antigen was significantly higher in the group that was vaccinated subcutaneously; this difference was particularly evident in patients less than or equal to 50 years old. The serologic response to A/Victoria/75 antigen did not differ significantly between the two groups. Levels of antibody before vaccination indicated previous widespread exposure of patients to influenza A/Victoria/75 virus, but not to influenza A/New Jersey/76 virus. Such differences in prior immunologic experience with a particular strain of influenza virus probably determine whether the intradermal route of vaccination is as effective as, or inferior to, the subcutaneous route.


Peritoneal clearances.

Intermittent peritoneal dialysis may provide borderline adequate dialysis in terms of clearance of small solutes. A number of disease processes could decrease clearances. Drug manipulations and other techniques to increase clearances primarily affect larger solutes. Since some small-molecular-weight solutes may be uremic toxins until proven otherwise, small solute clearance decreases during chronic intermittent peritoneal dialysis may require consideration of even more hours of intermittent peritoneal dialysis or initiation of CAPD.


Measurement of peritoneal clearances in self-dialysis patients.

Twelve chronic peritoneal dialysis patients were studied on 20 occasions to measure peritoneal clearances of creatinine, urea, uric acid, and potassium. Two clearance techniques were employed, the classical type using timed collections and a midpoint blood specimen and an experimental type using calculated dialysate flow and predialysis peritoneal fluid solute concentrations. Comparison of the two techniques demonstrated a close correlation between simultaneously measured clearances and also for repeat measurements in the same patient. The new technique is simple and reproducible, does not require blood sampling, and can be performed in the home by patients treated by self-dialysis using automated peritoneal dialysis equipment. The new technique will allow more frequent monitoring of peritoneal permeance in self-dialysis patients, and necessary adjustments in treatment time can be prescribed without requiring hospitalization.


Binding of IgG and complement protein by monosodium urate monohydrate and other crystals.

IgG adsorbed to negatively charged crystals of monosodium urate monohydrate was restricted to cationic species of immunoglobulin. Similar binding of smaller amounts of IgG was observed with crystals other than monosodium urate monohydrate. Heated monosodium urate monohydrate and amorphous sodium urate adsorbed greater amounts of IgG and other proteins. Complement activation as measured by electrophoretic conversion of C3, was not related to the amount of IgG adsorbed by the crystals studied. C1q was also adsorbed to some degree by all crystals studied but did not correlate with complement activation.


Removal of bile acids and bilirubin by plasmaperfusion of U.S.P. charcoal-coated glass beads.

Removal of protein-bound cholephilic substances such as BA by sorbent perfusion might improve the quality of life of patients with severe inoperable cholestasis where the accumulation of BA is thought to be responsible for the often distressing pruritus. Since hemoperfusion is associated with hematological side effects, plasmaperfusion which, in addition, allows the use of novel, possibly more efficient sorbents, might be preferable, provided a substance with a high affinity for these protein-bound anions could be found. A number of sorbents suitable for plasma-perfusion were therefore tested in vitro as to their BA-adsorbing capacity. U.S.P. charcoal coated onto glass beads in order to facilitate perfusion removed BA from human plasma far better than conventional charcoal suitable for hemoperfusion, charged and uncharged resins, and immobilized albumin. The extraction of BA by the coated glass beads exceeded 90% up to a load of 0.18 mumol BA per milliliter of sorbent, and the BA-adsorbing capacity was 20.8 mumol/ml. In addition to BA, the U.S.P. charcoal columns almost quantitatively removed uric acid, creatinine, and corticosteroids and retained substantial amounts of BR and thyroxine, whereas electrolytes, clotting factors, and plasmaproteins were adsorbed only initially.


Micellar properties of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oyl taurine and relationship to in vitro red cell disruption.

Patients with a metabolic block in the conversion of THCA to cholic acid develop cirrhosis and hemolysis. Tauro-THCA has been shown to distort hepatic architecture and cause hemolysis in bile-fistula rats. In this study, the critical micellular concentration of tauro-THCA was found to be one fourth of that measured for the primary human bile salt, taurocholate. In short-term incubations with intact red cells, tauro-THCA was more effective than taurocholate in removing red cell membrane lipid, inducing morphological red cell sphering, and decreasing functional cellular membrane surface area. These detergent biological membrane effects were most apparent at a concentration above the critical micellar concentration, with the membrane toxicity of the two bile salts roughly paralleling their differences in critical micellar concentration. The lower critical micellar concentration, greater hydrophobicity, and enhanced surface-active properties of tauro-THCA are speculated on as possible factors contributing to the bile salt's toxicity in vivo.


Serum amyloid P-component levels in amyloidosis, connective tissue diseases, infection, and malignancy as compared to normal serum.

A highly sensitive radioimmunoassay was developed to measure the serum levels of SAP. Sera from 50 normal individuals ranging in age from 4 to 89 years had a mean level of 7.47 mg/dl and showed no variations with age. Sera from persons with various clinical types of amyloidosis, connective tissue diseases, and bacterial pneumonia did not differ significantly from normal values. A significant difference was noted in the sera from persons with malignancy, where a mean value of 10.79 mg/dl was determined. Although a number of similarities exist between SAP and CRP, SAP does not share the property of being an acute-phase reactant.


A solid-phase radioimmunoassay for bound anti-platelet antibody: studies on 45 patients with autoimmune platelet disorders.

A highly sensitive, solid-phase radioimmunoassay has been developed for detecting platelet-bound immunoglobulin, which employs 125I-staphylococcal protein A. The assay detects platelet IgG at the picogram level, which is 10- to 50-fold more sensitive than currently available procedures. It is relatively simple and can be performed on frozen extracts from as little as 2 X 10(5) platelets. Washed platelets are frozen, thawed, sonicated, and centrifuged at 20,000 X g. The supernatant, which contains 7S IgG, is applied in serial dilution to the wells of a plastic microliter plate capable of adsorbing protein. Commercial rabbit anti-human IgG is added and then "sandwiched" to 125I-staphylococcal protein A. The wells are removed from the plate and assayed for radioactivity. Thirty-two of 35 thrombocytopenic patients (92%) with ATP had platelet IgG values greater than those of controls by 2 S.D. and averaged 150 +/- 145 (S.D.) ng/10(6) platelets; 11 healthy controls, 11.4 +/- 7.4 ng; five "thrombocytopenic" controls, 9.7 +/- 13 ng. The platelet count (X) correlated inversely with IgG/platelet (Y) according to the equation: Log Y = -0.66 log X + 4.8; r = -0.71, p less than 0.001. Elevated platelet IgG levels were also found in 5 ATP patients in "apparent remission"; two of four had evidence for compensated thrombocytolysis (increased megathrombocytes). Elevated platelet IgG levels were also found in six patients with thrombocytopenia secondary to lymphoproliferative disorders.


Effect of erythrocyte destruction on the pulmonary excretion rate of carbon monoxide in adult male Wistar rats.

One of the major contributory factors to hyperbilirubinemia in the human infant is bilirubin production. Determination of the pulmonary excretion rate of carbon monoxide is used to measure indirectly the rate of bilirubin production by estimating the endogenous production of CO, which is formed in equimolar amounts with bilirubin in the catabolism of heme. There has been no study to confirm that complete recovery of CO produced in vivo from the catabolism of known amounts of heme occurs via pulmonary excretion. We report here quantitative determinations of the pulmonary excretion rate of CO in five adult male Wistar rats after injection of known amounts of heme in the form of red blood cells "damaged" by incubation in a solution containing a sulfhydryl inhibitor, NEM. The mean recovery of "extra" CO above baseline production represented as a molar ratio of extra CO to heme was 0.98 +/- 0.02 (S.E.). Control studies showed no extra CO production after starvation, injection of NEM in an amount comparable to that used in the experimental animals, or injection of undamaged red blood cells.


Effects of chemoreceptor and baroreceptor stimulation on the discharge of hypothalamic supraoptic neurones in rats.

Experiments have been performed to examine the effects of activating the carotid body chemoreceptors and the arterial baroreceptors on the discharge of neurones within the hypothalamic supraoptic nucleus of the rat. Chemoreceptors were activated by intracarotid injection of 0.9% NaCl solution equilibrated with 100% CO2. The baroreceptors of the carotid sinus and aortic arch were activated by raising the blood pressure with an intravenous injection of phenylephrine. Chemoreceptor stimulation activated and baroreceptor stimulation inhibited the discharge of all the phasically discharging neurones tested. Neither stimulus had any consistent effect on non-phasically discharging neurones, although slight inhibition occasionally occurred. Anaesthesia of the carotid bifurcation abolished the effects of cardiovascular stimulation on the supraoptic neurones. Responses resumed when the anaesthesia wore off. However, the anaesthesia also seemed to alter the phasic pattern of discharge. The results are discussed with reference to the influence of the cardiovascular receptors upon the neurones in the supraoptic nucleus, and with reference to possible roles for the cardiovascular reflexes in control of vasopressin secretion.


Prolactin release in parent ring doves after brief exposure to their young.

A pigeon crop sac radioreceptor assay was used to measure changes in pituitary prolactin levels in parent ring doves of both sexes on the third day after hatching of their young. After a deprivation of 17 h from the squabs, exposure to a 3-day-old squab for 1 h resulted in a significant decrease in the prolactin content of the pituitary gland as compared with levels obtained in control birds deprived of their young for 18 h. No significant sex differences in prolactin levels were observed in either group. Because exposure to the young also promotes prolactin-induced crop sac growth, it appears probable that the squab-induced decrease in prolactin content of the pituitary gland reflects the release of prolactin into the circulation. Accordingly, the environmental regulation of prolactin secretion in parent ring doves appears similar to that observed in lactating mammals.


Oestrogenic effects of catechol oestrogens on secretion of prolactin by the pituitary gland and synthesis of DNA by the mammary gland in ovariectomized rats.

The effects of 2-hydroxyoestradiol-17 beta and 2-hydroxyoestriol (2OH-OE3) on levels of serum prolactin, DNA synthesis by the mammary gland and the weight of the uterus were examined in ovariectomized Sprague-Dawley rats. 2-Hydroxyoestradiol-17 beta had a potent oestrogenic activity in stimulating the secretion of prolactin by the pituitary gland, the synthesis of DNA by the mammary gland and in increasing the weight of the uterus. On the other hand, 2OH-OE3 increased the weight of the uterus only.


Photoperiodic control of seasonal breeding in the ram: participation of the cranial sympathetic nervous system.

Four mature Soay rams, cranially sympathectomized by removal of the superior cervical ganglia, were housed alongside four normal rams controlled lighting conditions of alternating 16 week periods of short days of 8 h light: 16 h darkness (8L : 16D) and long days (16L : 8D). The changes in the concentration of FSH, LH, prolactin and testosterone in the plasma, the size of the testes, the intensity of the sexual flush and the sexual and aggressive behaviour of the animals were recorded. While the control rams were able to respond to the artificial lighting conditions with synchronized cycles of reproductive activity, the ganglionectomized animals failed to respond. The treated rams had well-developed testes and relatively high levels of gonadotrophins and testosterone in the blood throughout the experiment. It is concluded that the cranial sympathetic nervous system is involved in the photoperiodic control of seasonal breeding in the ram, probably through its role in the innervation of the pineal gland.


Hyperaldosteronism in the sodium-depleted rat: mechanism of aldosterone stimulation by peritoneal dialysis with glucose solution.

Peritoneal dialysis with 5% glucose solution was carried out in dexamethasone-pretreated rats. Dialysis brought about a severe loss of sodium and a slight loss of potassium into the peritoneal fluid. This kind of sodium depletion took place without any decrease in total body-water space, thus it evoked a severe fall in plasma sodium concentration. Plasma renin activity and the serum concentration of aldosterone increased in response to dialysis. Peak values in renin activity were attained within 60 min, whereas aldosterone concentrations exhibited a continuous rise until at least 120 min. Despite the correlation of renin and aldosterone values, neither the administration of an angiotensin I converting enzyme inhibitor (SQ 20,881) nor the reduction of plasma renin activity by indomethacin could reduce hyperaldosteronism evoked by peritoneal dialysis. Therefore, it is assumed that there is no causal relationship between renin and aldosterone in this kind of acute, severe sodium depletion.


Inhibitory action of follicular fluid on progesterone and prostaglandin synthesis in bovine follicles.

The present studies examined the inhibitory effect of mid-cycle and preovulatory bovine follicular fluid (bFF) on the secretion of progesterone and prostaglandin F 2 alpha (PGF 2 alpha) by bovine theca and granulosa cells cultured in tissue culture Medium 199. The inhibitory effect of bFF on the secretion of PGF 2 alpha by incubated and cultured hemipituitary glands of male rats was also studied. Addition of 5, 10 or 20% charcoal-extracted, mid-cycle bFF to the culture medium caused a twofold decrease in the accumulation of both progesterone and PGF 2 alpha by the cultured granulosa cells (P less than 0.01). In contrast, when preovulatory bFF was used, there was no inhibitory effect on secretion of progesterone and PGF 2 alpha. The addition of 10% mid-cycle bFF to the culture medium caused a two- to fourfold decrease in the accumulation of both PGF 2 alpha and progesterone by the cultured theca (p less than 0.008). However, in the presence of 1 microgram LH/ml, the inhibitory effect of mid-cycle bFF on progesterone and PGF 2 alpha secretion was abolished. The secretion of PGF 2 alpha was significantly (p less than 0.03) decreased in male rat hemipituitary glands after 5 h of incubation or 18 h of culture. These findings suggest that bFF from mid-cycle follicles inhibits prostaglandin synthetase as well as luteinization. The inhibition disappeared with bFF from preovulatory follicles.


Foetal-maternal production and transfer of cortisol during the last days of gestation in the guinea-pig.

The metabolism and the rate of transfer of cortisol across the placenta in pregnant guinea-pigs and foetuses were studied by constant intravenous infusions of tritium-labelled cortisol. Estimates of endogenous and radioactive plasma cortisol levels were used to calculate the following parameters at four stages before parturition (days 62, 64, 66 and 67; parturition occurring at day 68): metabolic clearance rate; production rate; adrenal secretory rate; transfer rate from mother to foetus and from foetus to mother; irreversible removal rate; the fraction of cortisol derived from the other in the foetal and maternal vascular compartments; the fraction of secreted and recycled cortisol involved in the transfer. The metabolic clearance rate and the rates of production and secretion of cortisol were higher in the mother than in the foetus between days 62 and 67 of gestation. About 90% of the foetal cortisol was of maternal origin. The fraction of maternal cortisol of foetal origin increased in the last days of gestation.


Plasma oxytocin and steroid concentrations during late pregnancy, parturition and lactation in the miniature pig.

Plasma oxytocin concentrations were measured during late pregnancy, parturition and lactation in the miniature pig. Measurements were made of plasma oestradiol, oestrone and progesterone to determine whether there was any relationship between the concentrations of oxytocin and these steroids in the circulation. Plasma oxytocin concentrations were low or undetectable in late pregnancy. Rises of up to 68.8 mum./ml were seen at the time of delivery of the foetuses and at the expulsion of the placenta. The only steroid that seemed to relat to oxytocin release was progesterone. Oxytocin release was consistently seen when progesterone concentrations had fallen to below 10 ng/ml but no increase in concentration was observed while oestrone and oestradiol increased to their maximum concentrations of 3.86--11.6 and 0.43--0.70 ng/ml respectively. During lactation, when both oestrogen and progesterone concentrations were low, suckling caused the levels of oxytocin to increase to 7.4 muu./ml. These increases were greater during the first 2 weeks of lactation than later.


Hyperaldosteronism in the sodium-depleted rat: mode of aldosterone-stimulating action of frusemide.

The mechanism of diuretic-induced hyperaldosteronism was examined in dexamethasone-pretreated rats. The diuretic drug frusemide brought about a rapid increase in plasma renin activity and aldosterone concentration in serum. Half an hour after the administration of frusemide the mean concentration of aldosterone was 25 times higher than in vehicle-treated control animals. Administration of SQ 20,881, an inhibitor of angiotensin converting enzyme, prevented the adrenal response to frusemide. The response of aldosterone was completely blocked by indomethacin. This drug reduced renin release and probably also inhibited the effect on the adrenal glands of angiotensin, released in response to frusemide. Our results indicate that the effects of diuretics on the adrenal glomerulosa cells are mediated by the renin-angiotensin system also in the rat. Hyperaldosteronism is dependent on the maintenance of prostaglandin synthesis. ACTH has no essential role in this response.


Large-scale preparation of highly purified pyrogen-free human growth hormone for clinical use.

A method is described for the large-scale isolation of highly purified human growth hormone for therapeutic use. The hormone was extracted from frozen pituitary glands under mildly alkaline conditions. Purification was effected by gel filtration and ion-exchange chromatography. The final product was pyrogen-free and had a potency of 2.5 i.u./mg measured by bioassay against the current international standard. The yield of growth hormone/gland was approximately 5 mg.


Glucocorticoid and mineralocorticoid pathways in two adrenocortical carcinomas: comparison of the effects of o,p'-dichlorodiphenyldichloroethane, aminoglutethimide and 2-p-aminophenyl-2-phenylethylamine in vitro.

The synthesis of glucocorticoids and mineralocorticoids in vitro was studied in an adrenocortical carcinoma after alblation from an 11.5-year-old boy. This patient had been unsuccessfully treated with high doses of o,p'-dichlorodiphenyldichloroethane (o,p'-DDD) and aminoglutethimide. These in-vitro results were compared with those obtained with another adrenocortical carcinoma removed from a 26-year-old woman who had received no preoperative treatment. The sensitivity of these adrenocortical carcinomas to o,p'-DDD, aminoglutethimide and 2-(p-aminophenyl)-2-phenylethylamine (SKF 12185) was investigated. Synthesis of cortisol (47%) and corticosterone (45%) in control incubations showed that 11 beta-hydroxylase activity was not affected by the treatment. This explains the raised level of plasma cortisol in the treated child. All three compounds inhibited both 11 beta-hydroxylase and 18-hydroxylase activities up to 95%, depending on the inhibitor. This study shows (a) an inhibitory effect of o,p'-DDD on the steroidogenesis of an adrenocortical carcinoma in vitro, an effect not previously reported in man or laboratory animals, and (b) the in-vitro efficacy of o,p-DDD and aminoglutethimide on corticosteroidogenesis by a carcinoma unresponsive to treatment in vivo. This discrepancy between data obtained in vivo and in vitro could possibly be explained by either an insufficient ratio of ingested dose: tumour mass, or a malabsorption of the drugs in this patient.


Interaction between inner cell mass and trophectoderm of the mouse blastocyst. II. The fate of the polar trophectoderm.

Selective labelling of polar trophectoderm cells in early mouse blastocysts has allowed the fate of polar cells to be followed during in vitro and in vivo blastocyst development. Results show that there is cell movement from polar to mural regions as blastocysts grow. This indicates that trophectoderm cells directly opposite the inner cell mass are the oldest mural cells. However, after implantation polar cells invaginate into the blastocoelic cavity and contribute to the extra-embryonic ectoderm. It is suggested that the morphogenetic changes occurring in the mouse embryo at implantation result from the maintenance of a balance between (a) regional differences in rates of cellular proliferation, and (b) mechanical constraints on the direction in which growth can occur.


An analysis of the aggregation and morphogenesis of area opaca endoderm cells from the primitive-streak chick embryo.

The aggregative behaviour and subsequent morphogenesis of extra-embryonic endoderm cells from primitive-streak chick embryos have been investigated. A relatively pure population of area opaca endoderm cells was obtained by differential dissociation, which involves partial separation of epiblast and endoderm cell clumps by sieving through Nitex mesh. For aggregation studies cells were cultured in rotating flasks in Leibovitz (L-15) medium, in saline or in saline supplemented with glucose (1 mg/ml). Aggregation was monitored using the Coulter Counter. In these three media aggregation is rapid; by 10 min an average of 61% of the population had aggregated, to reach a plateau at 30 min when an average percent adhesion value of 83% was obtained. The aggregates in L-15 medium were large and compact. After several days in culture, they cavitated and formed smooth hollow vesicles with thin walls composed of one or a few cell layers. Aggregates formed in PCS were smaller and looser in appearance; the addition of glucose resulted in a certain degree of compaction. Some morphogenesis occurred under these conditions with the aggregates developing numerous irregular cavities. These experiments suggest that some of the factors that affect cell adhesion in early embryonic cells can be studied in vitro. The results also indicate that the ability to cavitate is an intrinsic property of the endoderm cells of the area opaca since this occurs in the absence of epiblast or mesoderm.


The ultrastructure of the dorsal yolk-free cytoplasm and the immediately surrounding cytoplasm in the symmetrized egg of Xenopus laevis.

Cytoplasmic segregation and subsequent dorsad displacement of the segregated cytoplasm lead to symmetrization of the egg of Xenopus laevis. At 60 min post-fertilization (p.f.) the 'dorsal yolk-free cytoplasm' (DYFC) is located in the dorso-animal part of the egg. Its ultrastructure and that of the immediately surrounding cytoplasm have been studied with transmission electron microscopy (TEM). The endoplasmic reticulum (ER) within the DYFC consists of single or paired cisternae and many small vesicles, both with moderately dense contents. Numerous particles, presumably ribosomes and glycogen, are present together with many mitochondria and some Golgi structures. The fraction of total yolk-free area occupied by mitochondria in the DYFC is about three times that in the adjacent cytoplasm. The number of cytoplasmic vesicles per unit area of cytoplasm is far larger in the DYFC than in the surrounding area. The morphological characteristics of the DYFC at 60 min p.f. suggest that it represents a region of high metabolic activity. Since it is located in the dorso-animal quadrant of the uncleaved egg, it may be partly responsible for a difference in metabolism between the dorsal and the ventral side of the egg, and hence may play an essential role in the determination of dorso-ventrality.


Cell number in relation to primary pattern formation in the embryo of Xenopus laevis. I. The cell cycle during new pattern formation in response to implanted organizers.

Results are presented which offer strong evidence that extensive alteration of the fates of embryonic Xenopus cells occurs independently of the schedule of cell division, after operations which lead to a doubling of the axial pattern of mesodermal differentiation in the gastrula. The experimental strategy was to make estimates of total mesodermal cell numbers and mitotic index in closely matched sets, each of three synchronous sibling embryos, fixed during the ten hours following the close of gastrulation. Within each set two embryos, an unoperated control and a sham-operated embryo whose own dorsal-lip (organizer) cells had been replaced with an equivalent graft, were developing normally. The third, experimental embryo had received an organizer implant to replace an equivalent number of cells from its ventral marginal zone, and was thus developing two axial mesodermal patterns of differentiation in relation to two dorsal midlines, the extra pattern embracing much host tissue. Mitotic index was also determined, in specific regions and throughout the mesoderm, in similar sets of embryos but at mid-gastrula stages. The conclusions are justified by the results of a control investigation which show that there is normally no difference in cell cycle time along the presumptive dorso-ventral mesodermal, dimension, during the interval between time of operations and the determination of pattern. The lack of any enhancement of mesodermal cell number in late embryos with dual axia patterns, or intervening enhancement of mitotic index in younger operated embryos, thus suggests that new patterns may be determined in the Xenopus gastrula without generation of extra cells. The results are discussed in relation to recent ideas about pattern formation, and the concepts of morphallaxis and epimorphosis.


Bristle patterns and compartment boundaries in the tarsi of Drosophila.

We describe cell lineage of the tarsus of wild-type Drosophila. Large Minute+ clones were made to map the position of the antero-posterior compartment boundary in all three tarsi. The tarsus is mirror symmetric, but the compartment boundary does not coincide with the mirror plane. This boundary runs along the dorsal and the ventral rows of bristles which are immediately posterior to the mirror plane; elements in these rows being made by both anterior and posterior polyclones. The provenance of bristles and bracts suggests that the bristle cells move into their final positions. The homoeotic mutation engrailed affects only the posterior compartments of all three tarsi. The mutations bithorax and postbithorax affect only the anterior and posterior compartments of the third legs, respectively, transforming them into homologous compartments of the second leg. These results support the selector gene model of development (Garcia-Bellido, 1975) and emphasize that collaboration between polyclones is important in pattern formation.


The activity of cholinesterases during the development of Xenopus laevis.

The activity of cholinesterases during the early development of Xenopus laevis has been examined, and the activity of acetylcholinesterase in particular has been distinguished from other cholinesterases. In contrast to some earlier findings, the activity of acetylcholinesterase is low at early stages and gradually increases during development. Possible reasons for the differences between the earlier results and those reported here are discussed.


Factors regulating the degree and extent of experimental chimaerism in the mouse.

The degree of chimaerism of the coat, bone marrow and cornea in mouse chimaeras obtained by aggregation of an albino inbred embryo of A strain with an A X CBA-T6T6 hybrid was investigated. Out of 21 individuals born, 18 were chimaeras. Statistically significant correlation has been demonstrated between chimaerism of the coat, bone marrow and the cornea. The contribution of the two components appears to be affected by two factors: first, variable participation of the two components inthe embryonic ectoderm of the chimaeric egg cyclinder, and second, the rate of proliferation of the two cell lines. A photometric method is described which permits the quantitative evaluation of coat chimaerism. The method is sensitive and reliable.


The mechanism of somite segmentation in the chick embryo.

The segmentation of somites in the chick embryo has been studied by transmission and scanning electron microscopy (stages 8-14). The segmental plate mesoderm consists of loosely arranged mesenchymal cells, whereas the newly formed somites are composed of elongated, spindle-shaped cells arranged radially around a lumen, the myocoele. The diamter of each somite is thus two cells plus the myocoele. Two major factors appear to be responsible for the change in cell shape at segmentation: (1) Each prospective somite cell becomes anchored at one end to the adjacent epithelia (i.e. the neural tube, the notochord, the ectoderm, the endoderm or the aorta) by means of collagen fibrils. These fibrils are already present in the segmental plate before the somites begin to form. (2) A change in cell-to-cell adhesiveness causes the free ends of these cells to adhere to one another. (Bellairs, Curtis & Sanders, 1978). This adhesion is then supplemented by the development of tight junctions proximally in the somite. Because it is anchored at both ends, each somite cell is under tension in much the same way as a fibroblast cell in tissue culture is under tension. Each somite cell therefore becomes elongated and the somite as a whole accommodates its general shape to that of the space available between the adjacent tissues. The arrangement of the cells in the more differentiated somites (stages 17-18) has also been examined and it has been found that the chick resembles Xenopus in that the myotome cells undergo rotation and become orientated in an anteroposterior direction.


Somite formation in the early chick embryo following grafts of Hensen's node.

Quail grafts of Hensen's node were examined for their potential to induce somites in chick blastoderms. The origin of the structures induced depended on the distance of the graft from the host's midline. Nodes placed at the margin of the area pellucida resulted in structures differentiated from the cells of the graft, whereas medially the graft organized host cells to form rows of somites. The results are discussed in terms of competence of graft and host mesenchyme and a positional signal from the node.


Effects of colchicine on spermiogenesis in the mouse.

The effects of colchicine on spermiogenesis in the mouse were examined. Mice were injected intratesticularly with colchicine in concentrations of 10(-4) M to 10(-6) M for various periods of time. The ultrastructure of the testes was examined and abnormal sperm in the epididymis were scored. Colchicine degraded microtubules in the testis and the treatment caused abnormalities of the head and acrosome of testicular spermatids and also resulted in an increase on the number of epididymal sperm showing abnormal head structure by 5 days after treatment of the testes. These results suggest that structurally intact microtubules are essential for the normal morphogenetic processes of spermiogenesis.


[The role of serotonin and catecholamines in the regeneration of the Planaria Polycelis tenvis].

During traumatic regeneration of Planaria Polycelis tenuis, determination of serotonin, noradrenaline and dopamine levels revealed important variations of serotonin and catecholamines from the time of excision. The use of specific inhibitors of these hormones delayed regeneration whereas simultaneous addition of an hormone and its antagonist restores a standard time of regeneration. Serotonin acts through adenylate cyclase system. Results allow us to assume that dopamine acts through the same mechanism. The action of noradrenaline is so far not elucidated although propranolol (beta antagonist) delays or inhibits completely regeneration.


Latent effects on in vitro development following cytochalasin B treatment of 8-cell mouse embryos.

Eight-cell mouse embryos when treated with 4.0 microgram/ml cytochalasin B (CB) in vitro undergo a reversible developmental arrest. Upon rinsing of embryos and subsequent culture in control medium, normal morphogenetic processes such as compaction of 8-cell embryos, cavitation, and post-blastocyst attachment and outgrowth are restored. However, the effects of CB on mouse embryos are not completely reversible; latent post-blastocyst defects become increasingly more prevalent as CB treatment duration increases. The present study was conducted to quantitatively determine latent effects of CB on post-blastocyst embryos by comparing their ability to attach and to sustain the growth and differentiation of ICM and trophoblast tissues. Groups of 8-cell embryos were cultured in Brinster's BMOC-3 medium containing 4.0 microgram/ml cytochalasin B for 6, 12, 18, and 24 h. Following treatment, embryos were rinsed and cultured until 190 h post coitum (h.p.c.) in Eagle's MEM/10% fetal calf serum modified to contain optimal levels of essential amino acids. Blastocysts generally attached to the surface of the plastic substratum by 120 h.p.c. At selected time periods after attachment (130, 160, and 190 h.p.c.), embryos were scored for outgrowth size, ICM size, extent of peripheral hyaloplasmic fan, and number of trophoblast nuclei per outgrowth. Analyses of variance (ANOVAs) were conducted for each of the four parameters listed above. Rates of attachment were analyzed by chi2 test. Results show that the treatments affect (P less than 0.01) embryo attachment, number of trophoblast nuclei per outgrowth, hyaloplasmic fan production, and ICM growth in a duration-dependent manner. Interestingly, since treatment effects on outgrowth areas are nonsignificant apparently CB does not significantly change total outgrowth area. But CB treatment does cause abnormal fan production and decreased trophoblast nuclei numbers. However, trophoblast cells are apparently more resistant than ICM to CB as is evident by the high incidence of trophoblast outgrowths devoid of ICM. CB (4.0 microgram/ml) treatments at 8-cell stages for relatively short durations (6 and 12 h) induce latent effects on post-blastocyst embryos. Finally, there exists a definite 4.0 microgram/ml CB duration response over the 68-190 h.p.c. observation interval.


The role of monocytes in serum sickness nephritis.

We have investigated the pathogenesis of glomerular hypercellularity seen in acute serum sickness nephritis induced in rabbits with bovine serum albumin (BSA). The increase in cellularity began with the first stages of immune clearance of BSA, with a peak cellularity occuring at the time of onset of proteinuria. Although there was a significant increase in the fraction of glomerular cells incorporating [3H]thymidine, first seen at the onset of proteinuria, this increase occurred too late and was too small to explain the observed rate of increase in glomerular cellularity. On the other hand, a striking monocytic infiltration of the glomeruli was documented by electron microscopy and by staining for nonspecific esterase. This monocytic infiltration paralleled the observed course of glomerular hypercellularity and was quantitatively sufficient to explain the total increase seen. It appears, therefore, that glomerular hypercellularity seen in this model is principally a result of monocyte infiltration.


Tumor necrosis serum induces a serologically distinct population of NK cells.

Murine spleen cells generate nonspecific cytotoxic cells, referred to as natural killer (NK) cells, within 4 d of incubation in Mishell-Dutton cultures. This NK cell type does not arise in cultures of BALB/c.nu spleen cells or in cultures of T-cell depleted C57BL/6 spleen cells, indicating that its activation depends on T cells. Another type of NK cells is induced by tumor necrosis serum in murine spleen-cell cultures. It arises within 24 h and its activation does not depend on T cells. This cell type (and its precursor) expresses the recently discovered cell-surface marker Qa5 (controlled by the Q region of chromosome 17) that distinguishes this NK cell from the NK cell that depends for its activation on thymic function. Qa5+ NK cells are also induced by interferon.


Lysis of measles virus-infected cells by the purified cytolytic alternative complement pathway and antibody.

The dependence of antibody-and-complement-mediated lysis of virus-infected cells on the alternative pathway was examined utilizing the isolated cytolytic alternative pathway--a system consisting of the six purified proteins of the alternative pathway of activation (C3, factors B and D, beta 1H, C3b inactivator and properdin), and the five proteins of the membrane attack pathway (C5--9) of complement. HeLa cells acutely infected with measles virus were lysed by anti-viral IgG and the isolated cytolytic alternative pathway with an efficiency comparable to whole human serum. IgG and its F(ab')2 fragment were equally effective in inducing lysis by the isolated cytolytic alternative pathway, binding of approximately equal to 5 X 10(7) molecules per cell being required for 50% lysis; in contrast, no lysis occurred when equivalen or greater amounts of Fab' were bound to the virus-infected cell. Properdin was required for lysis. No lysis occurred if properdin was deleted from the isolated cytolytic alternative pathway, and lysis was diminished by 80% in properdin-depleted serum. Uptake of [125I]C3b from the isolated alternative pathway onto measles virus-infected cells occurred in the absence of properdin, but was accelerated in the presence of properdin. The 11 proteins of the isolated cytolytic alternative pathway are thus sufficient for lysis of measles virus-infected cells bearing anti-viral IgG or F(ab')2 without any other serum protein.


Target-effector interaction in the human and murine natural killer system: specificity and xenogeneic reactivity of the solubilized natural killer-target structure complex and its loss in a somatic cell hybrid.

Preincubation of natural killer (NK) cells with electrophoresis purified proteins from a variety of NK-sensitive murine and human tumor cells specifically prevented subsequent binding to the intact, homologous target cell. The NK-target structures (NK-TS) consisted of some or all of four characteristic molecular species, tentatively assigned molecular weights of 140K, 160K, 190K, and 240K (+/-10K) based on electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels. When these NK-TS molecules were compared in cross-inhibition assays, the large 240K molecule most often carried the unique NK specificity, whereas the smaller 140K molecules cross-reacted between YAC, 136-6 and X-63 in the mouse and between Molt-4 and K562 in the human. Mouse NK cells recognised a different spectrum of NK-TS molecules than human NK cells. The control of NK-TS expression was partially revealed in a cloned, somatic cell hybrid bwtween an NK sensitive (YAC-IR) and insensitive (A9HT) cell line. The hybrid did not express NK-TS and did not bind to NK cells which is in accordance with negative NK cytolytic results previously reported. Although unique specificities are carried by some of the multiple NK-TS protein molecules, cross-reactions were widespread. These observations taken together suggest that the NK cell is polyspecific and has some heterogeneity in the recognition structure although much less than would be expected of an antibody-combining site.


Cell surface antigens of human renal cancer defined by autologous typing.

Sera from 28 patients with renal cancer were tested for reactivity with surface antigens of cultured autologous renal cancer cells. Four serological assays were used to survey sera for autologous antibody. Immune adherence, protein A, and C3-mixed hemadsorption assays detected reactivity in a high percentage of patients (80-100%), whereas mixed hemadsorption assays were negative with sera from all but one patient. Reactive sera from six patients were analyzed by absorption tests with autologous, allogeneic, and restricted to autologous renal cancer cells; class 2 antigens, present on certain allogeneic renal and nonrenal cancer cells; and class 3 antigens, found on a wide variety of normal and malignant cell types. The sera of one patient detected class 1, 2, and 3 antigens, the sera of three patients detected class 2 antigens, and the sera of two patients detected class 3 antigens. This analysis of renal cancer, with the recognition of three classes of surface antigens recognized by autologous sera, resembles the results of autologous typing of three other human malignancies: malignant melanoma, acute leukemia, and astrocytoma. Evidence provided by autologous typing of these cancers indicates that class 1 and class 2 antigens are tumor-restricted and that under certain circumstances these antigens are immunogenic for the autologous host.


Detection of a mediator derived from endotoxin-stimulated macrohpages that induces the acute phase serum amyloid A response in mice.

The mechanism by which LPS stimulates an acute phase serum amyloid A (SAA) response in C3H mice has been studied. A factor (SAA inducer) appears in the blood of C3H/HeN (lipopolysaccharide [LPS]-sensitive) mice approximately 1 h after administration of LPS, which, when passively administered, can induce C3H/HeJ mice to produce SAA although they are resistant to the LPS itself. SAA inducer has been detected in the culture medium of LPS treated C3H/HeN macrophages but not spleen cells. Thus, two stages in the induction of the acute phase SAA response are now recognized: a latent period of 2-3 h during which the SAA concentration remains at baseline values and in which SAA inducer appears, and the period of synthesis of SAA which lasts for approoximately 24 h past induction. It is proposed that a macrophage response to LPS is responsible for production of the serum mediator which induces SAA synthesis.


Human complement in thrombin-mediated platelet function: uptake of the C5b-9 complex.

Thrombin-mediated platelet aggregation and release is enhanced by the presence of C3, C5, C6, C7, C8, and C9 of human complement. The interaction of thrombin with its receptor on the platelet membrane initiates activation of complement on the platelet surface. Trypsin-mediated platelet function is not enhanced by the addition of complement, probably because trypsin has no receptor on the platelet surface so activation of complement is triggered in the fluid phase and not on the platelet surface. Activation of complement by thrombin led to production of dimers of the C5b-9 complex on the platelet surface. These complexes were eluted from the platelet membrane and were identified physicochemically and morphologically. The mechanism of complement-induced enhancement of platelet function is not clear, however, it probably is mediated via the arachidonic acid transormation pathway because this activity was blocked by known inhibitors of cyclo-oxygenase, namely, aspirin and indomethacin.


Site of binding of mouse IgG2b to the Fc receptor on mouse macrophages.

Three mouse immunoglobulins with altered heavy chains have been used to study the specificity of the mouse IgG2b Fc receptor on mouse macrophages. These immunoglobulins were synthesized by variant clones derived from the MPC 11, IgG2b-producing mouse myeloma cell line. One variant, whose Fc receptor. A second variant, which makes a short heavy chain lacking the CH3 domain, binds specifically to the IgG2b Fc receptor. The third variant makes a hybrid IgG2b-IgG2a heavy chain whose CH3 domain is enterely IgG2a-like and binds to both IgG2a and IgG2b Fc receptors. These data suggest that the binding of mouse IgG2b immunoglobulins to the mouse macrophage Fc receptor involves a site within the CH2 domain and indicate that immunoglobulins with altered heavy chains are a useful tool to probe Fc receptors.


[Determination of Fe, Cu and Zn by a mechanised micro-method of flame photometry (author's transl)].

By sample application in measured quantities ("injection method") the quality of serum required for the determination of trace elements can be considerably decreased with essentially no loss in sensitivity. The volume of solution, 50 or 100 microliters, required for a single measurement is added to the nebulizer of the AAS apparatus manually with a bulb pipette, or automatically by a suitable sample changing system. A total of 500 microliters serum is sufficient for the determination of traces of Fe, Cu, and Zn. It was shown that under suitable conditions a total volume of 25 microliters serum is sufficient for the determination of Cu and Zn by flame atomic absorption-atomic emission photometry.


Collagen heterogeneity in systemic scleroderma and other diseases.

Proportions of collagen type I and type III were investigated in different tissues (kidney, liver, heart muscle, esophagus, lung and skin) in a single case of malignant systemic scleroderma. The proportion of collagen type III was higher than in healthy controls. Similarly, an increase in the proportion of collagen type III was shown in tissues affected by other inflammatory diseases. Further the authors suggest that the increase in total kidney collagen, especially type III, has important consequences for kidney function; in the described case it had the critical influence on the fatal course of the disease, and the patient died from uremia.


A homestyle delivery program in a university hospital.

The Homestyle Delivery Program, an alternative birth service at the University of California Davis Medical Center, Sacramento, is presented. The program was developed jointly by the departments of family practice, obstetrics, and pediatrics, in response to the needs and desires of patients and physicians to participate in a more natural family centered birthing process. A brief description of the program and data from the first 1 1/2 years of operation is given. This program, in contrast to many other alternative birthing programs, involves physicians in training; that is, residents in family practice and obstetrics who are being taught during their obstetrical training how to create and facilitate an intimate family oriented home-like birthing. Satisfaction with the program on the part of the participating families as well as physicians and program staff has been very high. Today, more families in this society are demanding this kind of alternative birthing experience; the Homestyle Delivery Program meets their needs and to data has demonstrated no increased risk to mother or infant.


Hypertension and ischemic heart disease in a rural family practice in Israel.

Prevalence rates of hypertension and ischemic heart disease in a rural community in Israel in 1976 were 9.3% and 2.3%, respectively. The rates were related to age, sex, country of origin, education, occupation, marital status, household crowding, and smoking habits. A multiple regression analysis of all variables showed a significantly positive association between the prevalence of hypertension and age, number of children, Cochin or Moroccan origin, and divorce or widowhood. A negative association was found with agricultural work. The prevalence rate of ischemic heart disease correlated positively with age, Cochin origin, and divorce or widowhood. A stepwise linear regression analysis revealed that these variables accounted for 11.3% and 2.8% of the total variance observed, in hypertension and ischemic heart disease respectively.


The physician's duty to report the battered child syndrome.

All US jurisdictions require that physicians file formal reports of suspected cases of child abuse and/or child neglect. Most states expressly grant civil immunity from lawsuits to all reporting physicians. The physician who fails to file such a report will be exposed to civil liability for professional malpractice when failure to report leads to continued child abuse. At least 37 states provide for criminal penalties for physicians who fail to report battered children. This paper examines procedures for minimal compliance with any state's reporting statute and details the precise reporting procedure for each US jurisdiction.


Assessing counseling skills and attitudes in family practice residents.

This is the second of two papers describing portions of the behavioral science orientation curriculum that focuses on assessing changes in counseling skills and attitudes in Charleston family practice residents. The measurement of counseling skills and attitudes is accomplished through a 38-item multiple choice instrument. The basic types of items composing the instrument are delineated. Pre and post-testing data are presented over a five-year period, 1973-1977. Three-year follow-up data are presented for the residency class entering in 1975. These data are discussed from two perspectives: (1) their function in teaching physician awareness of counseling style, and (2) their function in assessing changes in physician counseling profiles.


Effectiveness of faculty development workshops in family medicine.

Family medicine programs need faculty well trained in the roles of educator, administrator, researcher, and clinician. While the need for faculty development is recognized in all colleges and departments, it is a particular problem in family medicine due to the shortage of faculty, diverse backgrounds of existing faculty, and current pressures to develop the research base for the discipline of family medicine. This study was conducted to gather information about the effectiveness of the two-to-three day workshop format for faculty development in family medicine. In a pre-post comparison and a nine-month follow-up of four faculty development workshops, significant and persistent changes were found in participants' ratings of their abilities to do faculty related skills. The three-day residential workshop was found to be an effective means for promoting faculty development.


Three approaches to problem solving in medicine and some problems they create.

Three general approaches to problem solving in medicine are examined: Basic Science Problem Solving, Clinical Medicine Problem Solving, and Human Values Problem Solving. These three approaches employ different--indeed contradictory--search strategies. Not infrequently, students of medicine become versed in one or another problem solving approach only to flounder when they try to apply it inappropriately. Recognition of this problem may help to solve it.


The effect of relocation of a family practice center on one resident's experience in continuity of care.

In July 1977, the Hollywood Family Practice Unit of the University of Miami Department of Family Medicine was relocated eight miles from its former structure. Analysis of patient encounter data gathered by one resident during the 2 six-month periods prior to and following the move showed little effect of the relocation on five indexes of continuity of care. According to four indexes (percentage of revisits, percentage of revisits for new problems, percentage of revisits for previously recorded problems, and percentage of families with more than one member attending), the author experienced a gradual and uninterrupted increase in continuity of patient care. A fith index, percentage of psychosocial diagnoses, dropped slightly during the third study period. Overall continuity was low, however, when compared with established practices. Although family practice residencies should accept disruption in continuity of patient care due to their structure and purposes, steps are noted which can be taken to improve continuity of care.


Maximal exercise testing--Bruce protocol.

Maximal treadmill exercise testing is feasible for the family physician's office especially in a group setting. The Bruce Exercise Test is described in detail and is helpful in the diagnosis of asymptomatic coronary heart disease, following the course of coronary heart disease, diagnosis of other cardiac disease, and in preventive testing and exercise prescription. Sensitivity and specificity of ST changes may be improved by recognizing factors which cause false positive and negative ST responses. The Bruce Test is safe when the procedure is followed meticulously. There have been 2,490 tests performed in the laboratory of three family physicians without serious morbidity. The screening exercise test with preventive exercise prescription is particularly pertinent to the present day concepts of family practice.


Rubella seroconversion following immunization in a rural practice.

One hundred two consecutive patients with verifiable immunization to rubella were studied in a rural West Virginia county. Hemagglutination Inhibiting (HI) antibody titres, age at immunization, and elapsed time since immunization were recorded. Twenty-three (22.5 percent) had HI titres less than 1:8. There was no statistically significant difference in whether immunization at less than 15 months or more than 15 months of age resulted in a titre of greater than or equal to 1:8. There was no evident change in group proportion of seroconversion with time; either the child initially had a seroconversion with immunization, or he/she did not. A relatively large number of children with verified immunization to rubella do not have a titre currently considered protective to rubella. This does not seem to vary with time since immunization or age at immunization.


Post-abortion attitudes and patterns of birth control.

Among 63 women questioned one year after a first trimester abortion at an outpatient clinic, over 75 percent had mature, well-considered reasons for having chosen abortion and felt secure in their decision. Their feelings and attitudes toward themselves and abortion were strongly positive, with a few expressions of unresolved guilt, regret, or depression. They had become more responsible about contraceptive use, more interested in planning future pregnancies, and had experienced little change in sexual habits. Although only 21 percent (13 women) had employed contraception when they became pregnant, 76 percent (48 women) were using effective methods of birth control one year after abortion. Furthermore, over one third felt they were better able to deal with problems and had learned more about their coping capacity as a result of the crisis.


Comparative content of three family practice residency programs.

A method of collecting physician-patient encounter data is described and applied to the comparison of the clinical content of residents' experiences in the family practice office. Comparisons were made of over 1,000 consecutive unselected encounters in each of the three family practice residency programs. Considerable differences between the patients encountered by the three programs were observed and between program patients and patients attending family physicians in Iowa. It is important to monitor the demography and diagnostic status of patients attending family practice residency programs to ensure the authenticity of the residents' experience.


Recognition of depression in a university-based family medicine residency program.

Physicians diagnosed depression in 4.5 percent (59/1,321) of all patient encounters in this study conducted in a university based family medicine residency program. A subset of residents permitted the investigators to interview those patients who were diagnosed as depressed or who were judged to be at high risk for a missed diagnosis of depression. Of the six patients whom the residents diagnosed as depressed and who agreed to be interviewed, two did not meet the criteria for depression but in neither case was this discrepancy judged clinically significant. Of the 24 patients at high risk for a missed diagnosis who agreed to be interviewed, four met the diagnostic criteria and three of these four missed diagnoses were judged as possibly of clinical significance. While the physicians in this study diagnosed depression more frequently than in previous similar studies, this does not appear to represent over-diagnosis, although the small number of patients interviewed requires that interpretations be made cautiously. The authors suggest that if a primary care physician diagnoses depression in less than 2 percent of patient encounters, he or she should consider the possibility of missed diagnoses.


Group process in teaching family dynamics to family practice residents.

Behavioral science training in family practice at Madigan Army Medical Center, Tacoma, Washington, has used small group seminars to teach family dynamics on an experiential level. The group process is similar enough to dynamics within families to facilitate understanding by introspection. Small groups are an efficient method for teaching, and allow experiential learning to occur spontaneously as well as on a planned basis.


Clinical experience of medical students with primary care career goals.

Two medical students with primary care career goals, in a medical school based at a university medical center, recorded demographic and medical problem information from their patients. They saw a total of 3,391 problems in 2,265 different patients, resulting in a clinical experience similar to that of students from a medical school not based at a university medical center and residents in two family medicine residency training sites. Almost 62.0 percent of problem contacts were seen outside of the medical center hospital, 66.7 percent on ambulatory patients, and 47.3 percent on non-credit rotations, reflecting the intensity of their personal motivation, the support of faculty with primary care backgrounds, and the flexibility of a clinical curriculum offering 50 percent electives. The study demonstrates that it is possible for students in a university medical center to obtain clinical experience with patient problems of the type encountered in the community.


Teaching physicians to teach: a three-year report.

To meet the needs for an expanded preceptor faculty, the Department of Family Medicine at the College of Medicine and Dentistry of New Jersey-Rutgers Medical School has for three years conducted yearly training programs designed to prepare practicing family physicians for the teaching role. Thirty-six physicians have completed the program, which consists of four group seminars and three individual learning site visits spent in the office of an experienced preceptor while a fourth year student is present. Many lessons were learned in the course of these yearly programs which may be useful to others who plan to undertake similar faculty development activities. Therefore, detailed, practical, experiential information is presented regarding recruitment, orientation, the educational program of seminars and individual learning experiences, evaluation, and required resources. Some problems proved to be particularly difficult, such as the uneven quality of the individual learning visits and the attrition of some participants from the program. Feedback from participating physicians has been extremely positive.


Concerns and challenges facing social workers in family practice.

Twenty-five social work members of the Society of Teachers of Family Medicine responded to a survey in which they identified their chief concerns and challenges encountered in family practice. Of nine areas of concern to social workers in interdisciplinary practice identified from the literature, respondents viewed as most important the achievement of acceptance and regard among other disciplines for the social worker and the value of his/her contribution to family practice. This was followed closely by the associated challenges of developing interdisciplinary relationships and fostering an accurate understanding of the role functions of the social worker in family practice. To confront these and other concerns, careful attention to three major needs suggested by the survey results is advocated: (1) the need for social workers to maintain high standards of performance in family practice, (2) the need for family physicians and other health care personnel to understand the role functions of the social worker and examine their attitudes toward collaboration with social workers, and (3) the need for regular and constructive dialogue between all personnel in family practice.


Specialty preference and attitudes toward the aged.

The relationship between the attitudes and knowledge regarding the aged and specialty preference of undergraduate medical students at three medical schools was studied. No significant differences in attitudes were found when students were classified by class (freshman, sophomore, junior, or senior) or by sex. A significant though weak relationship between class and level of cognitive knowledge was found. Students indicating a preference for family practice as a specialty demonstrated levels of cognitive knowledge which did not differ significantly from all other students. Similarly, attitudes of family practice students did not differ significantly from attitudes expressed by other students. However, when all students expressing a preference for a primary care specialty were compared to students expressing preferences for non-primary care specialties, primary care students had significantly more positive attitudes toward the aged than their peers. Levels of cognitive knowledge did not differ significantly. The data appeared to suggest that students selecting primary care specialties are somewhat more humanistic and empathetically oriented, at least in regard to the aged, than their peers while exhibiting essentially identical levels of cognitive knowledge. The implications of these findings for family practice education are discussed.


Referral patterns of family physicians in an underserved rural area.

This paper examines the rates and patterns of referral of four family physicians in an underserved rural area of Washington State. The majority of referrals made by the family physicians were for management of a particular problem outside the scope of practice of the physician. The referral rates ranged from 1.8 to 3.2 percent of all patient visits and were comparable with those previously reported. A National Health Service Corps physician had the highest rate of referral and a foreign medical graduate had the lowest rate of referral. These results may be explained by practice building incentives as well as the ability to establish ties with the referral network.


The oscillatory responses of skate electroreceptors to small voltage stimuli.

Tonic nerve activity in skate electroreceptors is thought to result from spontaneous activity of the lumenal membranes of the receptor cells which is modulated by applied stimuli. When physiological conditions are simulated in vitro, the receptor epithelium produces a current which flows inward across the lumenal surface. This epithelial current exhibits small spontaneous sinusoidal fluctuations about the mean that are associated with corresponding but delayed fluctuations in postsynaptic response. Small voltage stimuli produce damped oscillations in the epithelial current similar in time-course to the spontaneous fluctuations. For lumen-negative, excitatory stimuli, these responses are predominantly an increase over the mean inward current. For inhibitory stimuli they are predominantly a decrease. Increased inward current across the lumenal membranes of the receptor cells increases depolarization of the presynaptic membranes in the basal faces leading to increased release of transmitter and an excitatory postsynaptic response. Decreased inward current decreases depolarization of the presynaptic membranes leading to a reduction in transmitter release and an inhibitory postsynaptic response. Clear changes in postsynaptic response are detectable during stimuli as small as 5 microV with saturation occurring at +/- 400 microV. The evoked oscillations in epithelial current are damped and the postsynaptic responses decline during maintained stimuli with large off-responses occurring at stimulus termination. The initial peak of the off-response is similar to the response produced by onset of an oppositely directed stimulus. These observations substantiate the role of receptor cell excitability in the detection of small voltage changes.


The ionic basis of oscillatory responses of skate electroreceptors.

When physiological conditions are simulated, skate electroreceptors produce small maintained oscillatory currents. Larger damped oscillations of similar time-course are observed in voltage clamp. Subtraction of leakage in voltage clamp data shows that the oscillations involve no net outward current across the lumenal surface of the epithelium. The oscillations are much faster than the late outward current generated by the lumenal membranes of the receptor cells. Treatment of the basal surface of the epithelium with tetraethyl ammonium (TEA), high K, Co, or EGTA reversibly blocks the oscillations in voltage clamp, but has little or no effect on the epithelial action potential in current clamp or on the current-voltage relation. The TEA sensitivity of the oscillations indicates that they involve a potassium conductance in the basal membranes of the receptor cells. Treatment of the basal membranes with TEA and high calcium, with strontium, or with barium causes these membranes to produce large regenerative responses. Direct stimulation of the basal membranes then elicits a lumen-positive action potential whereas stimulation of the lumenal membranes elicits a diphasic action potential. Excitability of the basal membranes is abolished by extracellular Co, Mn, or La. Modulation of the lumenal membrane calcium conductance by the basal membrane conductances probably gives rise to the oscillatory receptor currents evoked by small voltage stimuli. The slower calcium-activated late conductance in the lumenal membranes may be involved in sensory accommodation.


Nonlinear cable equations for axons. I. Computations and experiments with internal current injection.

Steady-state potential and current distributions resulting from internal injection of current in the squid giant axon have been measured experimentally and also computed from nonlinear membrane cable equation models by numerical methods, using the Hodgkin-Huxley equations to give the membrane current density. The solutions obtained by this method satisfactorily reproduce experimental measurements of the steady-state distribution of membrane potential. Computations of the input current-voltage characteristic for a nonlinear cable were in excellent agreement with measurements on axons. Our results demonstrate the power of Cole's equation to extract the nonlinear membrane characteristics simply from measurement of the input resistance.


Nonlinear cable equations for axons. II. Computations and experiments with external current electrodes.

We have investigated the steady-state potential and current distributions resulting from current injection into a close-fitting channel into which a squid axon is placed. Hybrid computer solutions of the cable equations, using the Hodgkin-Huxley equations to give the membrane current density, were in good agreement with experimental observations. A much better fit was obtained when the Hodgkin-Huxley leakage conductance was reduced fivefold.


Organotin-mediated exchange diffusion of anions in human red cells.

Organotin cations (R3Sn+) form electrically neutral ion pairs with monovalent anions. It is demonstrated that the tin derivatives induce exchange diffusion of chloride in red cells and resealed ghosts, without any detectable increase of membrane permeability to net movements of chloride ions. The obligatory anion exchange is believed to be due to the permeation of electroneural ion pairs, whereas the organic cation (R3Sn+) has an extremely low membrane permeability. Exchange fluxes of chloride increased with the lipophilicity of the substituting group (R3). At the same molar concentration of organotin, the relative potencies of the tin derivatives as anion carriers (with trimethyltin as a reference) were: methyl 1, ethyl 30, propyl = phenyl 1,00, and butyl 10,000. Tributyltin-mediated anion exchange was studied in detail. The organotin-induced anion transport increased through the sequence: F- less than Cl- less than Br- less than I- = SCN- less than OH-. Partitioning of tributyltin into red cell membranes was greater in iodide than in chloride media (partition coefficients 6.6 and 1.7 x 10(-3) cm, respectively). Bicarbonate, fluoride, nitrate, phosphate, and sulphate did not exchange with chloride in the presence of tributyltin. Chloride exchange fluxes increased linearly with tributylin concentrations up to 10(-5) M, and with chloride concentrations up to at least 0.9 M. The apparent turnover number for tributyltin-mediated chloride exchange increased from 15 to 1,350 s-1 between 0 and 38 degrees C. These figures are minimum turnover numbers, because it is not known what fraction of the organotin in the membrane exists as chloride ion pairs.


Tributyltin-mediated exchange diffusion of halides in lipid bilayers.

This paper describes the effect of tributyltin (TBT) on the inorganic anion permeability of lipid bilayers. When this compound is added in micromolar concentrations to one or both sides of a phosphatidyl ethanolamine (PE) membrane formed in 0.1 M NaCl or KCl (pH 7), there is no change in the electrical conductance. Under these circumstances, the Cl self-exchange flux measured with 36Cl (MCl) increases from a value of approximately 10(-12) mol.cm-2.s-1, to approximately 10(-8) mol.cm-2.s-1. It was further found that the relation between chloride flux and [TBT] and [Cl] can be described as: MCl = B[TBT] [Cl]. When chloride was replaced by an equimolar concentration of different univalent anions in the trans compartment, the heteroexchange flux of chloride followed the sequence: I greater than Br greater than Cl greater than F greater than NO3. Under all experimental conditions tested, the chloride flux was always more than 10(3) times the maximum flux predicted from the value of the membrane conductance, and at least 100 times higher than the expected fluxes of ion pairs (TBT-Cl) diffusing across the unstirred layers. Thus, the mechanism by which tributyltin increases anion permeability in bilayers seems to be that of an obligatory exchange diffusion, with the reaction between tributyltin and the halides occurring at the membrane surface. Measurements of interfacial potentials indicate that tributyltin chloride lowers the positive intrinsic dipole potential of PE membranes by approximately 70 mV (at a TBT concentration of 30 microM) without substantial alteration of other parameters of the bilayer. The estimated adsorption coefficient of TBT-Cl was found to be 3 x 10(-4) cm.


Chloride and sodium influx: a coupled uptake mechanism in the squid giant axon.

The squid giant axon was internally dialyzed while the unidirectional fluxes of either Cl or Na were measured. The effects of varying the internal or external concentration of either Na or Cl were studied. Chloride influx was directly proportional to the external Na concentration whereas Cl efflux was unaffected by changes of the external Na concentration between 0 and 425 mM. Neither Cl influx nor efflux were affected by changes of internal Na concentration over the range of 8-158 mM. After ouabain and TTX treatment a portion of the remaining Na influx was directly dependent on the extracellular Cl concentration. Furthermore, when the internal Cl concentration was increased from 0 to 150 mM, the influxes of Cl and Na were decreased by 14 and 11 pmol/cm2.s, respectively. The influx of both ions could be substantially reduced when the axon was depleted of ATP. The influxes of both ions were inhibited by furosemide but unaffected by ouabain. It is concluded that the squid axolemma has an ATP-dependent coupled Na-Cl co-transport uptake mechanism.


Electrogenic sodium extrusion in cardiac Purkinje fibers.

Thin canine cardiac Purkinje fibers in a fast flow chamber were exposed to K-free fluid for 15 s to 6 min to initiate "sodium loading," then returned to K-containing fluid to stimulate the sodium pump. The electrophysiological effects of enhanced pump activity may result from extracellular K depletion caused by enhanced cellular uptake of K or from an increase in the current generated as a result of unequal pumped movements of Na and K, or from both. The effects of pump stimulation were therefore studied under three conditions in which lowering the external K concentration ([K]0) causes changes opposite to those expected from an increase in pump current. First, the resting potential of Purkinje fibers may have either a "high" value of a "low" (less negative) value: at the low level of potential, experimental reduction of [K]0 causes depolarization, whereas an increase in pump current should cause hyperpolarization. Second, in regularly stimulated Purkinje fibers, lowering [K]0 prolongs the action potential, whereas an increase in outward pump current should shorten it. Finally, lowering [K]0 enhances spontaneous "pacemaker" activity in Purkinje fibers, whereas an increase in outward pump current should reduce or abolish spontaneous activity. Under all three conditions, we find that the effects of temporary stimulation of the sodium pump are those expected from a transient increase in outward pump current, not those expected from K depletion.


Structural changes in single muscle fibers after stimulation at a low frequency.

Direct stimulation of single muscle fibers from Xenopus laevis at a frequency of 1 Hz results in a decline of the peak isometric twitch tension after about 200 twitches. Fibers were chemically fixed in glutaraldehyde after a varying number of twitches and at several fatigue levels, and the ultrastructural appearance was compared with that of resting fibers treated by identical fixation methods. No gross structural abnormalities were observed but subtle changes occurred. The mitochondria of stimulated fibers contain granules of normal size and number. The inner crista width is constant but the matrix width is increased on stimulation. These changes would not compromise ATP production. The myofibrils are normal except for a slight swelling in the myosin lattice. The transverse system (T system) and sarcoplasmic reticulum are intact. The minor diameter of the transverse tubule (T tubule) is increased slightly in stimulated fibers. The gap between the T-TC membranes stays constant at about 110 A, but tiny connecting pillars are seen to cross this gap more frequently in stimulated fibers (21 +/- 5% triads) than in resting fibers (8 +/- 6%). In stimulated fibers there is a marked increase in the electron dense content of the terminal cisternae (TC). Inasmuch as the observed structural changes correlate with the number of twitches but not with the fatigue level, it is concluded that TC density and T-TC pillar formation are related to the normal mechanisms of excitation-contraction coupling.


Temporal patterns and selectivity in the unitary responses of olfactory receptors in the tiger salamander to odor stimulation.

Temporal patterns and selectivity in unitary responses of 100 single olfactory receptors in the tiger salamander to odor stimulation were investigated. An olfactometer which permitted control of stimulus concentration, duration, and flow rate was calibrated with a gas chromatograph. Stimulus pulses were monitored by recording the electroolfactogram from the surface of the olfactory epithelium. Both diphasic and triphasic spikes were recorded extracellularly. No discernible differences in types of responses, reproducibility of responses, and cross-unit distribution of spontaneous rates distinguished diphasic from triphasic units. The cross-unit selectivity in responses to the seven olfactory stimulants used and the range of odorant concentrations which effectively evoked these responses suggest variations in types and number of types of receptive sites on each cell. Temporal patterns in the unitary responses were generally less complex than those observed in the olfactory bulb. Phasic stimulations evoked phasic patterns. Tonic stimulations evoked phasic/tonic patterns. Occasionally poststimulus depressions or elevations in firing rates were observed. The nature of these patterns varied somewhat with odorant concentration for a particular unit.


Adaptation and cross-adaptation to odor stimulation of olfactory receptors in the tiger salamander.

We have used the effects of self- and cross-adaptation on the unitary responses of olfactory receptors of the tiger salamander to odor stimulation to investigate the stimulus-specific components of these responses and to provide information about the cross-cell variations in the numbers and numbers of types of constitutent receptive sites. An olfactometer delivered sequential odorous pulses, either juxtaposed or separated by a variable time delay. We used four pairs of odorants judged to be similar within a given pair. The unitary response to the test stimulation relative to that of the conditioning stimulation varied from being unchanged to being completely eliminated. We sometimes observed substantial poststimulus increases in the firing rate following stimulation with juxtaposed odorous pulse. Except in the case of one odorant pair, cross-adaptation occurred both with juxtaposed pulses and with pulses separated in time. With the methyl butyrate/ethyl butyrate odorant pair, however, statistically significant cross-adaptation appeared only with juxtaposed pulses. We propose a simple model to aid in explaining these phenomena. The experimental observations in conjunction with this model are used to obtain estimates of the maximal and minimal number of receptive site types available for interaction with the chosen odorants.


Sodium and calcium interactions in vascular smooth muscle cells of the rabbit ear artery.

The effects of Na-free and of K-free solutions on the membrane potential, on tension development, and on 45Ca exchange have been investigated in rabbit ear artery. The contraction induced by Na-free solutions and the tension which develops in K-free solutions after a delay of about 1 h are both submaximal. Exposure for 4 h to K-free solutions does not affect the membrane potential, whereas Na-free solutions depolarize the cells by 10-20 mV, depending on the Na-substitute. Neither the amplitude nor the rate constant of the slowly exchanging 45Ca-fraction is affected by these experimental procedures. Substituting external Na by choline or TMA induces a transient increase of the 45Ca-efflux rate which does not occur in a Ca-free efflux medium, and which can be blocked with La. K readmission to Na-enriched tissues hyperpolarizes the cells up to -100 mV and induces a relaxation, without exerting any effect on the 45Ca efflux rate. The release of Ca from intracellular stores, induced by histamine and FCCP, and its subsequent extrusion through the plasma membrane produce a transient stimulation of the 45Ca efflux, which is not affected by the reduction of the Na gradient. The transient contraction induced by histamine in Ca-free solutions is affected in a different way by different Na substitutes. The results do not fit the Na-Ca exchange hypothesis but are consistent with an effect of the Na gradient on the passive Ca influx.


The effect of strychnine, bicuculline, and picrotoxin on X and Y cells in the cat retina.

The effect of intravenous strychnine and the GABA antagonists picrotoxin and bicuculline upon the discharge pattern of center-surround-organized cat retinal ganglion cells of X and Y type were studied. Stimuli (mostly scotopic, and some photopic) were selected such that responses from both on and off-center cells were either due to the center, due to the surround, or clearly mixed. Pre-drug control responses were obtained, and their behavior following administration of the antagonists was observed for periods up to several hours. X-cell responses were affected in a consistent manner by strychnine while being unaffected by GABA antagonists. All observed changes following strychnine were consistent with a shift in center-surround balance of X cells in favor of the center. For Y-cell responses to flashing annuli following strychnine, there was either no shift or a relatively small shift in center-surround balance. Compared to X-cell responses to flashing lights, those of Y cells were very little affected by strychnine and in most cases were unaffected. It thus appears that glycine plays a similar role in receptive field organization of X cells as does GABA in Y cells (Kirby and Enroth-Cugell, 1976. J. Gen. Physiol. 68:465-484).


The active tension-length curve of vascular smooth muscle related to its cellular components.

The active and passive isometric tension-length (internal circumference) relation of vascular smooth muscle has been investigated using a 100-200-micron lumen diameter artery from the rat mesenteric bed. Conditions were established under which maximal activation was obtained at all lengths. Below L0 (the length at which maximum tension, delta T0, was developed) the active tension fell with decreasing length along a line which extrapolated to 0.38 L0; below 1.1 L0 the relation was reversible regardless of the protocol used. Above L0 the active tension fell linearly with increasing length along a line which extrapolated to zero tension at 1.82 L0. At the longer lengths investigated (up to 1.6 L0) the passive tension upon which the active responses were superimposed was as high as 4.4 delta T0. However, measurements of the dynamic characteristics of the preparation (with a time resolution of 2 ms) suggest that the active tension measured is nevertheless a measure of the active properties of the contractile apparatus. Direct light microscopic observation of the effect of length change on the cells within the walls of the preparation showed that changes in vessel length produced, on average, the same percentage change in cell length. Histological examination showed no signs of cell destruction following large extensions. The results suggest that the decrease in tension with extension above L0 is due to changes in the properties of the contractile apparatus, rather than to cellular damage.