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G J Huxham

Publications and source records attributed to G J Huxham.

33 records · Page 2Linked to original sources
PubMed1985

Electrical responses of cultured porcine thyroid cells to adrenergic agents.

The membrane potential of cultured porcine thyroid follicular cells depolarized by up to 20 mV from the resting value of about -73 mV on exposure to beta-adrenoceptor agonists. A similar response was induced by TSH or dibutyryl cyclic AMP. alpha-Adrenoceptor agonists were without effect. The receptor subtype was shown to be (at least predominantly) beta 2 by the order of potency for beta-agonists (isoprenaline approximately equal to fenoterol much greater than adrenaline greater than noradrenaline) and by the relative potency of selective beta-antagonists (ICI 118,551 much greater than atenolol). The alpha-agonist phenylephrine had no effect on the TSH response but weakly inhibited the beta-agonist response. Rather than a physiological antagonism between alpha- and beta-adrenoceptor-mediated responses, this effect was shown to be due to the weak beta-antagonist effect of phenylephrine since the alpha-antagonist phentolamine failed to potentiate the depolarizing response to the mixed agonist noradrenaline, and also failed to block the inhibitory action of phenylephrine on the beta-agonist effect. Sensitivity to beta-agonist was enhanced by omission of serum from the culture medium and reduced by exposure to beta-agonists or a high concentration of TSH or dibutyryl cyclic AMP.

Adrenergic beta-Agonists↗
PubMed1985

Electrical responses of cultured thyroid cells to serotonin.

Cultured porcine thyroid cells, maintained in the differentiated state by dibutyryl cyclic AMP, responded to serotonin (5-HT; 10 nmol/l to 1 mumol/l) with a depolarization of the membrane potential, but did not respond to histamine (100 mumol/l) or dopamine (1 mumol/l). The resting membrane potential of these cells was about -71 mV, maximal concentrations of 5-HT (1 mumol/l) inducing a depolarization to approximately -53 mV. Methysergide or phenoxybenzamine, but not propranolol, abolished the response to 5-HT. Sensitivity to 5-HT was reduced by previous exposure of cultures to TSH, the beta-adrenoceptor agonist salbutamol or 5-HT itself.

Albuterol↗
PubMed1984

Predictors of success in a cohort of medical students.

Secondary school results were compared with personality test scores as predictors of achievement in medical school in a study of a cohort of students, using simple correlation and multiple linear regression. The cohort of 151 students completed 28 courses in the 6 years. We have previously reported that the scores obtained could be reduced to five independent factors: 'physical science'; 'biological science'; 'paraclinical science'; 'basic clinical science'; and 'clinical science'. Both secondary school scores and personality test scores correlated with medical school achievement factors, but school scores correlated best with 'physical' and 'biological' science. Considering secondary school scores, English was the best predictor of 'clinical science', physics was the best predictor of 'basic clinical science' and scores obtained in physics and languages were better predictors of medical school 'biological science' than was school biology. Personality factors were better predictors of 'biological', 'paraclinical' and 'clinical science' than secondary school scores and the combined secondary school score (CSS) was the best predictor of 'physical science' and of 'overall achievement'. We conclude that incorporation of personality measurement with school academic achievement could be of value in selection procedures for applicants for medical school.

Achievement↗
PubMed1981

Changes in membrane potential of cultured porcine and human thyroid cells in response to thyrotrophin and other agents.

Thyrotrophin (TSH), cyclic AMP, cyclic GMP and 1-methyl-3-isobutyl-xanthine (MIX) promoted the reassociation of isolated porcine and human thyroid cells into follicular structures in culture and stimulated the uptake of radio-iodide. Monolayer cells were present in all cultures, but in decreasing proportions as the concentration of stimulator was increased. The resting membrane potential of porcine thyroid cells cultured for 4 days in the presence of TSH was -54 +/- 3.6 (mean +/- S.D.) mV for follicular cells and -31 +/- 2.6 mV for monolayer cells. In the absence of TSH, only monolayer cells were present and their membrane potential was -24 +/- 2.0 mV. Removal of hormone by washing resulted in hyperpolarization to -70 +/- 2.9 mV (follicular cells) or -59 +/- 3.4 mV (monolayer cells). Subsequent replacement of TSH, or addition of cyclic AMP, MIX, prostaglandin E1 (PGE1) or long-acting thyroid stimulator immunoglobulin resulted in depolarization of previously hyperpolarized cells, to approximately the membrane potential observed before washing. Incubation in MIX resulted in enhanced sensitivity to the depolarizing effect of TSH. Cells cultured in the absence of TSH were unresponsive to TSH or other stimulators. The membrane potential of human thyroid cells behaved similarly in response to TSH, to hormone removal and replacement, and to MIX and PGE1.

1-Methyl-3-isobutylxanthine↗
PubMed1980

Is Bloom's Taxonomy reflected in the response pattern to MCQ items?

The purpose of this study was to find out whether taxonomic classification of MCQ items reflected differences in student behaviour. The data from one of this University's official open-book exams, in which students answer sixty MCQ items distributed over twelve content-areas of physiology were examined. The responses from all 153 candidates were then subjected to factor analysis. Analysis of individual item scores was unrewarding. Analysis of scores for item-groups based on taxonomy and content resulted in the identification of three factors, which carried predominant loadings from recall or look-up items, interpretation items, and problem-solving items, respectively.

Analysis of Variance↗
PubMed1976

Student test type preference and its relation to personality and achievement.

1. Test type preference of 227 medical students was investigated by means of a questionnaire. 2. A majority of students believed that MCQ examinations gave rise to less advance anxiety than other forms of examination. 3. There was a highly significant correlation between preference and performance, probably as a result of reciprocal reinforcement between them. 4. A multiple linear regression analysis revealed than the scales stability/neuroticism, extraversion/introversion, general mental ability and native language had a significant influence on test preference. There was a significant trend for confident, stable students to demonstrate preference for MCQ while tense, anxious students tended to prefer other test types. 5. We conclude that a mixed examination format is desirable not only on theoretical grounds, but was also preferred by these students.

Achievement↗
PubMed1975

Influence of personality on achievement of medical students.

In this study second year medical students completed a battery of psychometric tests which measured both cognitive and non-cognitive personality traits. Personality profiles obtained have been compared with reported norms from some other published sources. The scores obtained from factor analyses of these tests were used as predictors of total achievement in cellular biology and physiology over two years. In agreement with reports by other authors we found that the most important trait contributing to achievement was introversion/extra-version with introversion correlating with high achievement particularly in multiple choice tests. Emotional maturity was also a major factor especially as a predictor of success in essay tests. General mental ability, verbal skills, and reading comprehension appeared as significant predictors of achievement, and these were apparently of comparable importance in both kinds of test. Students of foreign origin whose first language was other than English tended to perform better in essay than multiple choice tests but their overall performance was lower than would have been expected from their other personality traits including their verbal skills. On the other hand, students resident in college halls tended to have better overall performance than expected.

Achievement↗
PubMed1975

Reasons for differential performance in multiple choice and essay tests.

1. Previous studies with preclinical students demonstrated that there were factors other than topic content which produced significant differences in performance in multiple choice (MC) and essay (E) tests. 2. In this study second year medical students completed a battery of psychometric tests measuring both cognitive and non-cognitive personality traits. 3. The scores obtained after factor analyses of these tests were used as predictors of the difference in performance in 6 matched pairs of MC and E achievement tests over 2 years. 4. Students with high scores in a factor associated with introversion achieved better results in MC tests than would have been expected from their performance in E tests. On the other hand, students whose first language was not English did not perform as well in MC as they did in E tests. 5. Students with high scores in a factor associated with emotional maturity and illegible writing performed better in E tests than would have been expected from their MC results.

Analysis of Variance↗