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Biomedical subjects

D Brown

Publications and source records attributed to D Brown.

At least 973 records · Page 54Linked to original sources
PubMed1983

Combined effects of propranolol and ethanol on human psychomotor performance.

Twelve male subjects were given placebo or 160 mg propranolol, in divided doses, during a 24-hr period before drinking a beverage containing 0 or 50 ml ethanol/70 kg body weight. Tests designed to measure mental and motor performance were administered 75 min after the last dose of propranolol. The tests performed included the wobble board (WB), pursuit meter (PM), delayed auditory feedback (DAF), pegboard (PB), tapping, time estimation (TE), and a modified Cornell medical index (CMI). A mean blood ethanol concentration of 48.0 +/- 9.1 mg/dl and a mean plasma propranolol level of 33.1 +/- 13.1 ng/ml were achieved. Ethanol alone significantly impaired performance in 12 out of 20 tests (p less than 0.05). Propranolol significantly (p less than 0.05) antagonized the decrement in psychomotor performance induced by ethanol on the PM. In all other tests, there was no significant interaction between ethanol and propranolol. Propranolol alone had no significant effect on the psychomotor tests. When the drugs were combined, the subjective symptoms, as measured by the CMI, showed a trend toward being additive. This study suggests that no adverse interaction occurs between therapeutic doses of propranolol and minimum impairment doses of ethanol.

Adult↗
PubMed1983

Some observations on the behaviour of the sodium efflux in barnacle muscle fibres towards lithium ions.

The behaviour of the Na efflux towards Li+ was studied using single barnacle muscle fibres as a preparation. It is found that the Na efflux into Li+-ASW (artificial seawater) is reduced and that this effect is not fully reversed by returning back to Na+-ASW. Preinjection of 100 mM-EGTA reduces the magnitude of the fall of the Na efflux into Li+-ASW. The remaining Na efflux into Li+-ASW is further reduced by external application of 10(-4) M-ouabain. The remaining Na efflux in ouabain-poisoned fibres is reduced by replacing Nae by Li+. However, some fibres show a rise rather than a fall. Fibres loaded with NaCl (by injection) show a prompt and sustained stimulation of the Na efflux when Nae is replaced by Li+. A similar but less pronounced response is often seen with ouabain-poisoned fibres. Injection of LiCl (e.g. a 2 M-solution), causes a 20% fall in Na efflux. Subsequent replacement of Nae by Li+ fails to bring about a fall in the remaining efflux. It is concluded that the Na efflux in these fibres consists of a Na-Na exchange diffusion component which is not mediated by the Na-K pump and that its operation is interrupted by injecting Li+. The relative size of this component is about one-fifth and not one-half of the Na efflux.

Animals↗
PubMed1983

Further decrease in subclinical hemolysis utilizing 12.7 mm tubing in the arterial roller head.

In a series of 20 consecutive perfusions done for the same surgeon, 9.54 mm tubing was used in 10 coronary artery bypass grafting (CABG) procedures (Group 1), and 12.7 mm (1/2 in) internal diameter tubing was used in 8 CABG operations and 2 single valve replacements (Group 2). Extracorporeal circulation techniques were otherwise identical in all procedures. While no statistically significant differences between Group 1 and Group 2 were noted for pump time or platelet counts, it was observed that the patients undergoing perfusions with 12.7 mm internal diameter tubing showed significantly less hemolysis.

Aged↗
PubMed1983

Regional distribution of N-acetyl-D-galactosamine residues in the glycocalyx of glomerular podocytes.

Helix pomatia lectin (HPL) bound to colloidal gold was used as a specific cytochemical probe for the localization of terminal nonreducing N-acetyl-D-galactosamine residues in thin sections of rat kidney. In the glomerulus, lectin-binding sites were associated only with the podocyte foot process bases and were not found on the free cell surface of podocytes or on any other glomerular components. Gold-particle label was often arranged in the form of clusters which extended from the foot process base to the lamina rare externa and lamina densa of the basement membrane. In contrast, wheat germ lectin (WGL)-binding sites (beta-[1 leads to 4] linked N-acetyl-D-glucosamine residues and N-acetylneuraminic acid residues) were found in all regions of the podocyte plasma membrane and on the cell surface of all other glomerular cell types. In addition, WGL-binding sites were present in all three layers of the glomerular basement membrane (GBM) as well as in the mesangial matrix. A quantitative evaluation of the pattern of labeling for HPL-binding sites together with the sugar specificity of this lectin suggest that a component of the glycocalyx is being detected rather than a basement membrane component. This was confirmed by the absence of H. pomatia lectin-binding sites in preparations of isolated GBM which retained, however, wheat germ lectin-binding sites. These data show that the glycocalyx of the foot process base is a highly specialized cell surface domain with respect to its carbohydrate composition.

Acetylgalactosamine↗
PubMed1983

Immunological properties of monoclonal antibodies specific for meningococcal polysaccharides: the protective capacity of IgM antibodies specific for polysaccharide group B.

Two IgM monoclonal antibodies, MB32 and MB34 specific for meningococcal polysaccharide group B have been raised. Both were detectable by radioimmunoassay and agglutination, but only MB34 was effective in counter immunoelectrophoresis and complement fixation. MB34 was also far more potent than MB32 when tested for passive protection of mice infected with either Neisseria meningitidis group B or Escherichia coli K1. These data demonstrate that group B-specific antibodies do play a protective role in mice infected with these bacteria.

Animals↗
PubMed1983

Effects of temperature on Vitalograph spirometer readings.

Spirometric variables were obtained from nine symptomless subjects, who performed forced expiratory manoeuvres with three Vitalograph spirometers at three different ambient temperatures (36.5 degrees C, 24.1 degrees C, and - 7.3 degrees C) over three days according to a Latin square design. Analysis of variance showed no significant difference between values at different ambient temperatures when measured at ATPS. Correction of the results to BTPS resulted in a significant difference in values at the three ambient temperatures for all measurements other than the Vmax25. The mean error introduced by conversion to BTPS varied from 7% (SD 5%) for the FVC at 24.1 degrees C to 30% (21%) for Vmax50 at - 7.3 degrees C. Possible explanations for these observations include the increasing compliance of the spirometer bellows with increasing temperature, relatively slow cooling of gases within the spirometer, and a combination of these effects. We conclude that there is no evidence that conversion to BTPS improves the accuracy of measurements made on a Vitalograph spirometer. Further studies on other spirometers are needed to see whether conversion to BTPS is always appropriate.

Evaluation Studies as Topic↗
PubMed1983

Correlation between water flow and intramembrane particle aggregates in toad epidermis.

In abdominal skins of toads (Bufo marinus) challenged with either vasopressin or isoproterenol, the stimulation of transepithelial water flow was accompanied by the appearance of intramembrane particle (IMP) aggregates. These aggregates were found only in the apical plasma membrane of granular cells of the first-reacting cell layer. The effect of vasopressin varied in magnitude and could be selectively blocked by preincubation of the skins with methohexital. This barbiturate also prevented the appearance of IMP aggregates. Preexposure with propranolol had a similar effect in skins challenged with isoproterenol. Linear regression analysis of net water flow vs. the percentage surface occupied by IMP aggregates showed a significant (P less than 0.001) correlation, which applied to data obtained in six different experimental conditions, i.e., vasopressin or isoproterenol alone and either of these agents in combination with methohexital or propranolol. The results reported here in a nonurinary epithelium (toad epidermis) suggest that the appearance of IMP aggregates is a general response in epithelia undergoing adenosine 3',5'-cyclic monophosphate-mediated changes in water permeability.

Animals↗
PubMed1983

Immunohistochemical localization of carbonic anhydrase in postnatal and adult rat kidney.

With use of specific antibodies against human and rat erythrocyte carbonic anhydrase C and human carbonic anhydrase B, only the isozyme C could be detected by immunofluorescence in rat kidney epithelial cells. In the postnatal kidney a few cells were positive after 2 days, but the number of fluorescent cells increased during the first few weeks of life to reach the final adult levels after 3 wk in the cortex and 5 wk in the medulla. In the postnatal and adult kidney a characteristic mosaic pattern of fluorescence was seen in the late distal tubule, the connecting segment, and the collecting tubule, where the mitochondria-rich dark cells were brightly fluorescent. In addition, in later postnatal stages and in the adult, the entire epithelium of the initial portion of descending thin limbs of Henle (long loops) was labeled. Some kidney regions that had previously been shown to contain carbonic anhydrase activity by biochemical and histochemical techniques stained only weakly with the immunocytochemical method. This suggests either that the enzyme in these regions does not cross-react strongly with our antibodies or that these regions contain only low amounts of carbonic anhydrase, at the limit of the detection threshold of our techniques.

Aging↗
PubMed1983

A community model for arthritis rehabilitation.

Arthritis is a widespread chronic disease which can result in severe disability. Arthritis is best managed by a triad of treatment, education, and research. A community model for arthritis rehabilitation, with emphasis on the team approach, is described and illustrated. Central to the design of the model is an arthritis centre which demonstrates exemplary treatment and has a commitment to develop education and research programs. Primary arthritis care is the responsibility of the health professionals in each community, and the arthritis centre provides the support and resources for their programs. The model is suggested as a prototype for the management of other major chronic diseases.

Arthritis↗
PubMed1983

Induction of morphologically abnormal sperm in rats exposed to O-Xylene.

An analysis of sperm abnormalities can be used as a rapid method to determine the mutagenic potential of chemical agents as well as the toxic potential of chemicals on the whole animal. O-Xylene was investigated for its potential mutagenicity by the sperm abnormality assay. Sprague Dawley rats 10-16 weeks old were injected intraperitoneally (ip) with 0.5 and 1.5 ml/kg body weight of o-xylene in corn oil. Five weeks after treatment, animals were sacrificed and sperm examined for morphological abnormalities. Several morphologically abnormal sperm types were observed; among these were those with amorphous heads, and banana-like heads. Animals housed at room temperatures of 20-24 degrees C showed no significant increase in abnormal sperm over the control. Rats housed at temperatures between 24 and 30 degrees C after ip injection with 0.5 ml/kg o-xylene showed a significant increase in abnormal sperm.

Animals↗
PubMed1983

[Ultrastructural detection of the heterogeneity of glycocalyx in convoluted and straight proximal tubules of rat kidney by the lectin-gold complex technic].

A new histochemical technique in which lectin-gold complexes are applied directly to thin and semi-thin sections of tissue was used to determine the distribution of Helix pomatia lectin binding sites in the proximal tubule of Rat kidney. Whereas a strong labeling was seen on the brush border and baso-lateral plasma membranes of convoluted tubules, the plasma membrane of cells from the medullary straight segment was unlabeled. Some profiles at the frontier between cortex and medulla had a mosaic of positive and negative cells. These results show, therefore, considerable segmental variation in the glycocalyx composition of Rat proximal tubules.

Animals↗
PubMed1983

Distribution of filipin-sterol complexes in plasma membranes of the kidney. II. The thin limbs of Henle's loop.

Thin limbs of Henle from the rat kidney were investigated by freeze fracture electron microscopy after incubation of the tissue with the polyene antibiotic, filipin, a morphologic probe for membrane cholesterol. Distinct patterns of distribution of filipin-sterol complexes were found in plasma membranes of epithelial cells from each of the four thin limb regions examined. In particular, adjacent cells in the thin ascending limb had either heavily or poorly labeled apical membranes, whereas in the lower part of long descending thin limbs, all apical membranes were poorly labeled. In contrast, both apical and basolateral membranes of short descending limbs were heavily labeled with filipin-sterol complexes. These results demonstrate the existence of plasma membranes with different properties both within specific segments of Henle's loop (ascending thin limb) and between different thin limb segments (short and long descending limbs).

Animals↗
PubMed1982

Orientation of rat-liver plasma membrane vesicles. A biochemical and ultrastructural study.

Using both biochemical and morphological methods, the membrane orientation of plasma membrane vesicles from rat liver which are capable of catalysing the active transport of amino acids was investigated. In intact vesicles, the plasma membrane enzyme (Na+ + K+)-ATPase displays only a minor portion of its total activity which is greatly increased upon vesicle disruption. The same intact vesicles show an almost maximal binding of ouabain, which binds only to the extracellular side of the plasma membrane. A freeze-fracture analysis of the vesicles shows that a distinct population of relatively large vesicles have predominantly the in vivo membrane orientation. These large vesicles are labelled with numerous filipin-sterol complexes following exposure to the cholesterol probe, filipin, and are therefore assumed to be plasma membrane vesicles. A population of smaller vesicles with mainly an inside-out orientation were not labelled with filipin and are probably microsomes. The data obtained with both biochemical and ultrastructural techniques indicate that the plasma membrane vesicles isolated from rat liver for transport studies are mostly (at least 70%) orientated as in vivo, i.e. inside-in.

Animals↗