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Biomedical subjects

A Taylor

Publications and source records attributed to A Taylor.

At least 721 records · Page 40Linked to original sources
PubMed1983

Actin filaments and vasopressin-stimulated water flow in toad urinary bladder.

Vasopressin increases the water permeability of the apical membrane of the granular epithelial cells of the toad urinary bladder. Cytochalasin B inhibits this action of the hormone, indicating that microfilaments may play a role in the water permeability response. We have extended previous functional studies with cytochalasin B and have demonstrated that dihydrocytochalasin B, a more specific inhibitor of actin filament elongation, similarly diminishes the hydrosmotic response to vasopressin. Biochemical studies of isolated epithelial cells indicate that an actin-like protein accounts for about 10% of the soluble protein of the epithelium. Morphological studies of whole toad bladders incubated with heavy meromyosin conclusively demonstrate that actin is a component of the epithelial cells and that actin-containing filaments are associated with both plasma membranes and cytoplasmic organelle membranes. Taken together, these findings provide strong, albeit indirect, evidence that actin microfilaments play a functional role in the hormone-induced increase in water permeability in the toad urinary bladder.

Actins↗
PubMed1983

pH effect on osmotic response of collecting tubules to vasopressin and 8-CPT-cAMP.

The effect of peritubular and luminal pH changes on hydraulic conductance, (Lp, 10(-7) cm X s-1 X atm-1) in the isolated perfused rabbit cortical collecting tubule (CCT) was tested at 37 degrees C before and after administration of 20 microU/ml vasopressin or 10(-4) M 8-[p-chlorophenylthio]-adenosine cyclic monophosphate (8-CPT-cAMP). In vasopressin experiments when bath pH was changed from 7.58 to 7.16 or from 7.58 to 6.70, mean Lp decreased from 249 +/- 32 to 199 +/- 23 (n = 5; P less than 0.01) and from 231 +/- 38 to 201 +/- 36 (n = 5; NS), respectively. In contrast, in 8-CPT-cAMP experiments when bath [HCO3] was kept constant while CO2 was elevated the hydroosmotic response was increased. Using 2.5 mM HCO3, Lp at 0.4% CO2 was 275 +/- 15 and at 6% CO2 it was 352 +/- 50 (n = 4; paired t test; P less than 0.05). At 8.5 and 21.5 mM HCO3 raising CO2 from 2 to 13% and from 4 to 32% increased Lp from 237 +/- 71 to 410 +/- 32 (n = 4; paired t test; P less than 0.05) and from 282 +/- 45 to 449 +/- 63 (n = 6; paired t test; P less than 0.001), respectively. Reducing luminal pH from 7.40 to 5.40 had no effect on either vasopressin- or cAMP-induced changes in Lp. Accordingly, lowering the bath pH by increasing the PCO2 at constant [HCO3] markedly stimulates the response to 8-CPT-cAMP, whereas lowering the bath pH by reducing [HCO3] inhibits the vasopressin response.

Animals↗
PubMed1983

Hypercupraemia induced by antiepileptic drugs.

Serum copper and zinc levels were measured in 84 treated male epileptics, aged between 6 and 18 years, by an atomic absorption spectroscopic method. These patients were selected randomly from a residential special school. Twenty drug-free healthy but educationally subnormal (ESN) male subjects of similar age group from the same school acted as controls. No abnormality in serum zinc level was observed. In nineteen (22.6%) epileptics, copper levels were above the upper level of normal range (20.5 mumol/l), whereas this was only marginally elevated (20.8 mumol/l) in one (5%) ESN subject. The mean copper level in all epileptics was higher than the controls (P less than 0.01), but there was no difference between the epileptics treated with sodium valproate alone and the ESN group. The patients who were receiving carbamazepine either as monotherapy or in combination with other drugs except phenytoin, had higher mean copper levels than the controls (P less than 0.01). A similar observation was made in relation with phenytoin polytherapy (but excluding carbamazepine). There also appeared to be an association between the high serum copper levels and diffuse/generalized electroencephalographic changes (P less than 0.001). Some antiepileptic drugs, particularly carbamazepine, can produce such electroencephalographic abnormalities. It is concluded that hypercupraemia observed in these treated epileptics were related to the induction of caeruloplasmin synthesis by phenytoin and carbamazepine.

Adolescent↗
PubMed1983

Conceptions of masculinity and femininity as a basis for stereotypes of male and female homosexuals.

To date the majority of research published in relation to homosexuality has been concerned with the homosexual's problems, and with the etiology of homosexuality. As little as 8% of published research has dealt with attitudes toward homosexuals, and less still has been concerned with perceptions of and beliefs about homosexuals. Existing research on the latter is reviewed, and research is outlined that investigates perceptions of homosexuals. Stereotypes of male and female homosexuals are examined in the context of masculine-feminine traits using the Personality Attributes Questionnaire. Results strongly support the view that sex role definitions are a highly salient reference point for the public definition of homosexuals.

Adolescent↗
PubMed1983

Two forms of the Stroop test.

16 subjects performed a conventional chart-form and a card-sorting form of the Stroop color-word interference test. Interference scores on the two forms were positively and significantly correlated, while neither word reading nor color naming scores showed a significant correlation. It is suggested that the 'Stroop effect' has some, but limited, generality and that forms not requiring verbal response may be more useful than the traditional chart version in providing a general measure of interference proneness.

Adult↗
PubMed1983

Localization of leucine aminopeptidase in normal hog lens by immunofluorescence and activity assays.

Rabbit antisera to purified bovine lens leucine aminopeptidase (EC 3.4.11.1, LAP) were prepared and shown to be specific for leucine aminopeptidase alone (Taylor et al Cur Eye Res 2:47-56, 1982). When whole hog lens thin sections were treated first with these antisera and then with fluorescein conjugated goat anti-rabbit gamma globulin, greatest fluorescence was observed in the elongating epithelium and outer cortex, and significantly less fluorescence was observed in the lens core. That largest amounts of LAP are present in the epithelium is supported by activity measurements using leucylamide as substrate. The specific activity of LAP in the epithelium/outer cortex is 83 times that of LAP in the inner cortex. The concentration of posttranslationally (postsynthetically) modified and oxidized crystallins is greatest in the core, yet in this zone there is a paucity of aminopeptidase activity, possibly due to age-related degradation of the enzyme. It is possible that LAP is in association with membranes and present in nucleoplasm of rapidly metabolizing, elongating epithelial cells. These observations are discussed in relation to the possible role of proteolysis in cataractogenesis.

Absorption↗
PubMed1983

Technetium-99m(Sn2+)pyrophosphate in ischemic and infarcted dog myocardium in early stages of acute coronary occlusion: histochemical and tissue-counting comparisons.

We have investigated the pattern of accumulation of Tc-99m(Sn2+)pyrophosphate (Tc-99m PPi) in myocardial tissue of dogs during the early stages of acute occlusion of the left anterior descending coronary artery. Three groups were studied after: (a) 40 min occlusion followed by 6 hr reperfusion (n = 6); (b) 6 hr occlusion followed by one hour reperfusion (n = 5); and (c) 7 hr occlusion with no reperfusion (n = 4). Areas of myocardial infarction were defined with triphenyl-tetrazolium chloride (TTC) staining, and blood flow was determined with 9-mu radioactive microspheres. In Group C uptake in infarcted and peri-infarct areas was not enhanced, most likely owing to low flow. In Group B, with late reperfusion, Tc-99m PPi sequestration was increased in both infarcted and peri-infarcted tissues. In Group A, areas ischemic during occlusion but with normal flow and viability by TTC after 6 hr of reperfusion showed significant uptake of Tc-99m PPi (twice the uptake of nonischemic regions).

Animals↗
PubMed1982

A micromethod for the analysis of zinc in plasma or serum by atomic absorption spectrophotometry using graphite furnace.

A micromethod is described for the analysis of zinc in plasma or serum by electrothermal atomisation and graphite furnace utilising less than 20 microliters sample volume. The sample matrix introduced an error when aqueous standards were used. Therefore standards were made up in serum which had been treated with Chelex 100 to remove as much zinc as possible. The residual zinc (less than 0.125 mg/l) was determined by flame analysis using the method of additions and each standard assigned a value equal to the sum of the residual zinc and the amount added. Furnace analyses using standards made up in Chelex-treated serum compared favourably with flame analyses over the whole range, and recovery experiments gave 98 +/- 2% of the expected value with 95 +/- 6% recovery of the added zinc. The within-batch coefficient of variation was 2.5%, day-to-day variation 5.6%. The mean concentration of zinc in paired samples of plasma and serum from 50 adults analysed by flame with viscosity-matched aqueous standards were: plasma (mean +/- SD) 0.821 +/- 0.085 mg/l; serum 0.821 +/- 0.07 mg/l. The same samples were analysed in the graphite furnace using serum standards, and the results were: plasma 0.812 +/- 0.082 mg/l; serum 0.815 +/- 0.08 mg/l. In contrast to earlier reports we were unable to demonstrate a significant difference between plasma and serum zinc concentration in the paired samples.

Adult↗
PubMed1982

Evaluation of renal ischemia with 99mTc-pyrophosphate.

Renal ischemia injury was induced by transient 30-min occlusion of the main artery in five rabbits and by transient 60-min occlusion in four rabbits. The vessels to the contralateral kidneys were ligated in all nine animals and in six additional control rabbits. Renal blood flow was restored immediately following the transient ischemia. Twenty-four hours later, 99mTc-pyrophosphate was injected and renal uptake was monitored for 100 s and 10-min intervals for 90 min following injection. At 90 min postinjection, the animals were killed and the percent injected dose remaining in the kidneys was calculated for three animals in each group. At 60 min postinjection, in vivo activity in the 30-min ischemic kidneys was 2.3 times greater than that of controls, and activity in the 60-min ischemic kidneys 4.6 times greater than that of controls. These results suggest that 99mTc-pyrophosphate scanning may be useful in assessing slight ischemic damage to the kidney.

Animals↗