Biomedical subjects

J O Nnodim

Publications and source records attributed to J O Nnodim.

8 recordsLinked to original sources

PubMed1992

Multiple-choice testing in anatomy.

An analysis of 596 multiple-choice questions (MCQs) on human anatomy given at three First Professional Examinations for medical students is reported. The MCQ paper at each examination was 200 items long and consisted of three item-types: A, K and T/F. Each A-type item comprised a stem and five options, only one of the latter being the correct or best answer. Items of the K-type consisted of a stem and four responses, any number of which may be correct. The T/F items were of the three-response kind, the available options being 'true', 'false' and 'don't know'. Test reliability was computed by internal analysis, using the Kuder-Richardson 20 formula. Measures of concurrent validity were obtained by correlating the scores in the MCQ papers with the overall outcome of the First Professional Examination. Indices of item facility, discrimination and abstention were calculated. The effects of item-type and the availability of the 'don't know' option on examinee performance were also determined. Reliability (alpha) and concurrent validity (Pearson r) coefficients in the ranges of 0.71-0.85 and 0.80-0.93 (P less than 0.05) respectively were recorded. Regression analysis revealed the MCQ papers to be less sensitive predictors of the aggregate performance than the essay papers. The proportion of highly discriminatory and excessively difficult items was highest for the K-type. When the same K-type questions were re-exhibited in the indeterminate format, the examinees performed significantly better. Higher scores were also recorded when candidates were required to respond to all the questions than when they were offered the 'don't know' option and the percentage gain was higher for the low-scoring examinees. The appropriateness of multiple-choice testing as a tool for assessing student achievement in human anatomy is discussed.

Anatomy↗

PubMed1990

Learning human anatomy: by dissection or from prosections?

Two matched groups of first-year preclinical medical students studied the gross anatomy of the lower limb by different methods. One group dissected in the traditional manner (as in the existing curriculum) while the other worked according to an experimental programme which excluded dissection by students. Preparatory study guides were supplied to the experimental group and each of their practical classes on soft tissues began with a priming session at which the structures to be encountered were introduced. The instructor then demonstrated these structures to the group on a prosected wet specimen and bones. Thereafter, the students were allowed to handle and discuss the specimens without staff supervision. At the end of the programme, both groups submitted to a 300-item two-choice paper and a practical test. A debriefing questionnaire was also completed by the experimental group. In both tests, the experimental group performed better than the traditional group and the difference was statistically significant (P less than 0.05) in the theory paper. Further, the experimental programme was completed in about 74% of the time taken by the traditional programme. All the participants commented positively on the experimental programme and expressed the opinion that it had helped them understand the lower limb better than dissection had done for the upper limb. These results suggest that working from prosections is a very effective way of learning human gross anatomy. Such a programme is worthy of consideration by departments having to contend with unfavourable student:cadaver ratios and curtailed teaching time.

Anatomy↗

PubMed1990

The occurrence of brown adipose in man inhabiting the tropics.

Samples of cervical, mediastinal and perirenal fat tissue were obtained from eight subjects (ages: 17 days to 56 years) at necropsy. After formol fixation, the specimens were processed for sectioning and stained with hematoxylin and eosin, periodic acid--Schiff, or Holmes' silver techniques for light microscopy. All the tissue samples showed lobular organisation and a rich vascularity, with argentaffin (putative nerve) fibres at paravascular and parenchymal sites. Three histological forms of brown adipose tissue (BAT) were recognised: homogeneous lobules of multilocular adipocytes (Type I); mixed lobules consisting of islets of multilocular adipocytes surrounded by large unilocular cells (Type II); and lobules consisting mainly of small (less than 40 microns diameter) unilocular adipocytes (Type III). In two subjects (ages 17 days and 52 years), BAT (Types I and II respectively) was observed in tissue samples from all three sites. Perirenal samples from three other donors (ages 26-35 years) showed the presence of Type II or III BAT. Mediastinal BAT (Type II) was found in two subjects (26- and 35-years old). The significance of BAT in man inhabiting a warm environment is discussed.

Adipose Tissue↗

PubMed1988

Neural and vascular provisions of rat interscapular brown adipose tissue.

The innervation of rat interscapular brown adipose tissue has been studied by light and fluorescence microscopy and electron microscopy after treatment with "false" adrenergic neurotransmitters 5- and 6-hydroxydopamine. The vascular markers neoprene latex and thioflavin S were used to define the blood vascular arrangements within the around the tissue. Catecholaminergic innervation was revealed by fluorescence microscopy at both parenchymal and vasomotor sites. In animals injected with 6-hydroxydopamine, this catecholaminergic fluorescence was extinguished in the parenchymal nerve distribution and markedly reduced in the vasomotor plexus. Identification of an extensive network of noradrenergic vasomotor and parenchymal nerve terminals was established by electron microscopy after 5- and 6-hydroxydopamine administration, but unmarked terminals were also observed in both distributions. These unmarked terminals might represent an additional nonnoradrenergic nerve supply to interscapular brown adipose tissue. The thoracodorsal veins draining the fat pads are directly tributary to a large median perforating vein, which joins the azygos vein, and are also continuous with the axillary vein. In addition to the recognized vascular distribution pattern of lobular arteries supplying an abundant capillary plexus drained by lobular veins, direct arteriovenous anastomoses were observed within the interscapular brown fat pad. It is postulated that these additional vascular arrangements are determinant in the phenomenal increase in blood flow through brown adipose tissue during metabolic stimulation.

Adipose Tissue, Brown↗

PubMed1988

Stereological assessment of age-related changes in lipid droplet surface area and vascular volume in rat interscapular brown adipose tissue.

The surface area of stored triglyceride and the volume of capillaries in the interscapular brown fat pad of the rat have been adopted as morphological indices of the overall thermogenic capability of the tissue. The present study examines the relationship between the chronological profiles of these parameters and reported senile changes in the biochemical and physiological characteristics of brown adipose tissue. Lipid droplet surface density and vascular volume density were estimated by computer-assisted planimetry with electron micrographs prepared from interscapular brown adipose tissue samples obtained from rats of various ages. The volumes of the fat pad at these ages were also determined and used to calculate droplet surface areas and vascular volumes. Triglyceride surface area showed a 20-fold enhancement in the early postnatal period (0.44 X 10(2) cm2 at birth; 9.43 X 10(2) cm2 at 4 weeks). A further but less remarkable increase occurred in adulthood (11.67 X 10(2) cm2 at 6 months) and, in old age, only a slight fall was noted (9.66 X 10(2) cm2 at 2 years). Intralobular capillary volume also rose sharply early during the first week after birth, reaching a peak at 4 weeks (2.40 X 10(-2) cm3). The values recorded in adulthood and old age (1.90 X 10(-2) cm3 at 6 months; 1.76 X 10(-2) cm3 at 2 years) were not significantly different from that obtained at 4 weeks of age. These results show that the attainment of maximum values of lipid droplet surface area and vascular volume in rat interscapular brown adipose tissue coincides with the period of the tissue's peak metabolic capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue, Brown↗

PubMed1988

Learning human anatomy: does learning occur during a lecture?

Information uptake during a formal lecture was evaluated using a sample of 43 second-year medical students to whom a topic on human developmental anatomy was presented. The sample was divided into two groups: Blue (group B) (21 students) and Red (group R) (22 students). Prior to the lecture, a pre-test of 20 multiple choice questions was administered to each group. The lecture was then delivered over 50 minutes. Both in its preparation and presentation, the lecture conformed to the principles of programmed instruction. After a 10-minute students' question-and-answer session, a post-test was served. For group B, this was group R's pretest while group R, in turn, received group B's pretest. No question in the pre-test was repeated in the post-test. Intergroup comparisons of pre-test scores and of post-test scores revealed non-significant differences (P greater than 0.05), thus confirming that the pre- and the post-tests were of comparable difficulty. In each group, the mean post-test score was significantly higher than the pre-test score (P less than 0.001). The pooled scores indicated that the percentage mastery of material presented during the lecture increased from -1.8% to 58.4%. These results demonstrate that significant learning can occur during a lecture prepared and delivered in accordance with sound pedagogical principles.

Anatomy↗

PubMed1988

Learning human anatomy: student preferences of methods in a Nigerian medical school.

The present study evaluates the usefulness, as perceived by students, of the various methods by which anatomical information is presented during the preclinical part of the medical course. Assessments of these learning methods were elicited from a cohort of medical students at the University of Benin by a questionnaire based on their selection of questions to attempt in Anatomy Paper 2 (Essays) of the First Professional examination (= 2nd MB). An algorithm was provided to enable the quantification of the preferences expressed and hence the derivation of a utility index for each learning method. The results showed that reading/private study, formal lectures, informal discussions with peers and practical work were the learning methods from which the students had benefited, in descending order of usefulness. These findings are discussed in the context of the teaching and learning of human anatomy in the particular circumstances studied.

Anatomy↗

PubMed1987

Development of adipose tissues.

Studies on the development of brown and white adipose tissues and their relationship to ordinary connective tissue are the subject of the present review, which is updated to the fall of 1985. Primordial entities described as "primitive organs" have been noted at sites of adipose tissue development by numerous investigators. These "primitive organs" are clearly delineated from surrounding connective tissue and possess a well-defined vascular network in the interstices of which cellular organization takes place. The precursor cells of brown and white adipocytes appear to acquire their distinctive cytogenetic properties at a very early stage in the embryo. These progenitor cells temporarily exhibit structural similarities to fibroblasts and endothelial cells. This resemblance has led to speculation that fibroblasts and/or endothelial cells may be ancestral to adipocytes. However, recent in vivo and in vitro observations suggest that the brown adipose precursor cell is morphogenetically distinct from the white adipose precursor cell on one hand, and from fibroblasts and endothelial cells on the other. In vitro studies have also shown that the pericytic elements present in both brown and white adipose tissue depots in the adult are quiescent precursor cells that may be recruited under certain circumstances. Areas for further inquiry by means of recently developed techniques are indicated.

Adipose Tissue↗