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Biomedical subjects

H Marr

Publications and source records attributed to H Marr.

8 recordsLinked to original sources

Factors influencing theoretical knowledge and practical skill acquisition in student nurses: an empirical experiment.

A previous qualitative study [Nurse Education Today 20 (2000) 499] investigated perceptions of nurse teachers, student nurses and preceptors of the theory-practice gap said to exist within nursing. One theme was views of how the theory-practice gap could be closed. A subsequent quantitative study is reported here, in which this theme was translated into three factors. A full factorial experimental design was used to study the effect of these factors on theoretical knowledge and practical skill acquisition in a sample of first year undergraduate student nurses from one institution of higher education (n=19). The effect of whether a nurse teacher or preceptor taught students theoretical elements relating to a clinical specialty, whether the nurse teacher and preceptor collaborated on the content of what was taught to students and whether students went straight to, or delayed the clinical specialty following theoretical input, was examined. The results demonstrated preceptors were more effective than nurse teachers in promoting theoretical knowledge relating to their clinical specialty. Collaboration between the preceptors and nurse teachers on teaching content was ineffective at increasing theoretical knowledge. Delay between theoretical input and clinical experience was not detrimental for medical placements and for rehabilitation placements, resulted in an improved theoretical knowledge.

Analysis of Variance↗

A new assay and solubilization procedure for steroid 17,20-lyase from rat testes.

We report an assay for testicular 17,20-lyase which depends on the use of [21-14C]progesterone as a substrate. The method is made possible by a simplified procedure for the synthesis of [21-14C]progesterone. A chromatographic separation of the unreacted substrate and the 2-carbon by-product on mini silica gel columns permitted a quantitative assay of the lyase activity. The lyase complex from rat testes has been solubilized by treatment with Triton CF-54 detergent. The solubilized enzyme complex catalyzes the formation of androstenedione (4-androstene-3,17-dione) from progesterone without equilibrium with added 17-hydroxyprogesterone and the solubilized enzyme complex responds to the presence of cytosol activator. Both of these characteristics are similar to the properties of the intact microsomes. Thus, solubilization with this detergent preserves the special properties of the microsome bound enzyme complex.

Aldehyde-Lyases↗

Testicular steroidogenesis after human chorionic gonadotropin desensitization in rats.

When a single injection of 500 I.U. of human chorionic gonadotropin (hCG) is given to rats there is an initial acute rise of plasma testosterone and of testicular content for both cyclic AMP and testosterone. This response correlates with an increase in both lyase and 17 alpha-hydroxylase activities. Thereafter both plasma and testicular testosterone decline and do not increase after a second injection of hCG. During this period of desensitization, isolated Leydig cells were insensitive to the steroidogenic stimulatory effect of both hCG and dibutyryl cyclic AMP. The post-cyclic AMP block is not due to an alteration of the cyclic AMP-dependent protein kinase but it is correlated with a decrease in both lyase and 17 alpha-hydroxylase activities of the Leydig cell's microsomes. This decrease is not caused by the absence of the recently described cytosol activator of this enzyme because its addition did not restore the enzymatic activity. Within 60 to 96 h after hCG injection there was a spontaneous increase of both plasma and testicular testosterone and this parallels the recovery of lyase and 17 alpha-hydroxylase activities. These results suggest that both enzymatic activities are regulated, directly or indirectly, by hCG, and that this is partly responsible for the hCG-induced steroidogenic refractoriness of Leydig cells.

Animals↗