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Biomedical subjects

G J Groen

Publications and source records attributed to G J Groen.

18 recordsLinked to original sources
PubMed1991

Effects of conventional and problem-based medical curricula on problem solving.

This study examined the reasoning processes of beginning, intermediate, and senior students in two medical schools with different curricular formats. One school had a conventional curriculum (CC) where basic science was taught one and a half years before the clinical training, and the other had a problem-based learning curriculum (PBLC) where basic science was taught in the context of clinical problems and general problem-solving heuristics were specifically taught. The students were asked to give diagnostic explanations of a clinical case, both before and after being exposed to relevant basic science information. Two distinct modes of reasoning were identified, each reflecting a curriculum type. A predominantly "backward-directed" hypothetico-deductive mode of reasoning was found in the explanations of the PBLC students, and a "more forward-directed" pattern of reasoning was found in the explanations of the CC students. Students in the PBLC produced extensive elaborations using relevant biomedical information, which was relatively absent from the CC students' explanations. However, these elaborations were accompanied by a tendency to generate errors. These results have important implications regarding the strengths and weaknesses of the two types of curricula.

Canada↗
PubMed1991

Developmental accounts of the transition from medical student to doctor: some problems and suggestions.

This paper is concerned with the difficulties in integrating the results of recent cognitive research on expert-novice in clinical reasoning. The focus is on the issue of stage theories as a means of achieving such integration. Objections to the use of such theories in developmental psychology are reviewed. In light of these objections, it is argued that it is important to distinguish between stage theories and stage-like phenomena. It is concluded that a stage theory is not likely to provide adequate integration. Some alternative explanations, which include both cognitive and non-cognitive factors, are discussed.

Clinical Competence↗
PubMed1990

Nerves and nerve plexuses of the human vertebral column.

The origin, distribution, and termination pattern of nerves supplying the vertebral column and its associated structures have been studied in the human fetus by means of an acetylcholinesterase whole-mount method. The vertebral column is surrounded by ventral and dorsal nerve plexuses which are interconnected. The ventral nerve plexus consists of the nerve plexus associated with the anterior longitudinal ligament. This longitudinally oriented nerve plexus has a bilateral supply from many small branches of the sympathetic trunk, rami communicantes, and perivascular nerve plexuses of segmental arteries. In the thoracic region, the ventral nerve plexus also is connected to the nerve plexuses of costovertebral joints. The dorsal nerve plexus is made up of the nerve plexus associated with the posterior longitudinal ligament. This nerve plexus is more irregular and receives contributions only from the sinu-vertebral nerves. The sinu-vertebral nerves originate from the rami communicantes and, in the cervical region, also from the nerve plexus of the vertebral artery. Thick and thin sinu-vertebral nerves are found. Most frequently three types of thick sinu-vertebral nerves are observed, i.e., ascending, descending, or dichotomizing ones. Finally, the distribution of the branches of the ventral and dorsal nerve plexuses and of the sinu-vertebral nerves is described.

Cervical Plexus↗
PubMed1990

Medical expertise as a function of task difficulty.

This paper is concerned with factors that disrupt the pattern of forward reasoning characteristic of experts with accurate performance. Two experiments are described. In the first, the performances of cardiologists, psychiatrists, and surgeons in diagnostic explanation of a clinical problem in cardiology were examined. In the second, the performances of cardiologists and endocrinologists in diagnostic explanation of clinical problems within and outside their domains of expertise were examined. The performances of researchers and practicing physicians are also compared. The results of Experiment 1 replicated earlier results regarding the relationship between forward reasoning and accurate diagnosis. There were no differences in recall as a function of expertise. Experts did not show any bias toward using specific knowledge from their own areas of expertise. The results of Experiment 2 showed that the breakdown of forward reasoning was related to the structure of the task. In particular, nonsalient cues induced some backward reasoning even in subjects with accurate diagnoses. Some differences were also found between the types of explanation used by researchers and practitioners. The practitioners referred more to clinical components in their explanations, whereas the researchers focused more on the biomedical components.

Attention↗
PubMed1988

The innervation of the spinal dura mater: anatomy and clinical implications.

The nerves supplying the spinal dura mater were studied in four human foetuses (16-22 weeks) with the acetylcholinesterase in toto staining method. The ventral spinal dura contains a dense, longitudinally oriented, nerve plexus, which receives its contributions from: (I) the sinuvertebral nerves, (II) the nerve plexus of the posterior longitudinal ligament, (III) the nerve plexus of radicular branches of segmental arteries. Dorsal dural nerves are much smaller in number, do not form an evident plexus and do not reach the medial region of the dorsal dura. The dorsal nerves are derived from the ventral dural plexus at the level of the "intersleeval" parts of the dura mater. The ventral dural nerves may extend up to eight segments, with a great amount of overlap between adjacent nerves. This may provide an anatomical substrate for the understanding of extrasegmentally referred dural pain. The curled bundles of nerve fibres of pathways (I) and (II) provide an adequate adaptation to displacements of the spinal dura mater during flexion and extension. Pathway (III) has not been described before. The described nerve plexuses may be of importance in elucidating the mechanisms of epidural therapies in back pain and peripheral vascular disease.

Acetylcholinesterase↗
PubMed1988

Biomedical knowledge in explanations of clinical problems by medical students.

This paper was motivated by a controversy concerning the role of basic sciences in medical education. A problem underlying this issue is that it is unknown how basic science is used in clinical reasoning. The experiment was designed to address this issue. Three texts were constructed dealing with basic science knowledge relevant to a clinical problem. Subjects were asked to read and recall the texts. Next, the subjects were required to read and recall the clinical text describing a patient problem. Finally, they were asked to provide a diagnosis and an explanation of the underlying pathophysiology. Subjects were first-, second- and fourth-year medical students. Detailed analysis of subjects' protocols are presented. In general, the results show that when basic science information is given before the clinical problem, the basic science knowledge is used either incorrectly or inconsistently in explaining the clinical problem by all subjects. The authors interpret these results to indicate that the basic sciences and the more practical clinical knowledge form two separate domains with their own individual structures and the clinical information cannot be embedded into the basic science knowledge structure.

Biology↗
PubMed1987

Branches of the thoracic sympathetic trunk in the human fetus.

The segmental organization of the thoracic sympathetic trunk and all its ramifications was studied in 6 human fetuses (16-22 weeks) by means of the acetylcholinesterase in toto staining method. Each trunk was divided into 12 sympathetic segments. A segment is defined as that part of the sympathetic trunk which is connected via its rami communicantes with one spinal nerve, without discriminating between grey and white rami. The diameter of the rami communicantes and their direction towards the spinal nerves are variable. The number of peripheral segmental ramifications of the trunk is much larger than assumed previously. Each thoracic sympathetic segment gives off at least 4-5 nerves. Three categories of nerves are discerned: (1) large splanchnic rootlets confined to the greater, lesser and least thoracic splanchnic nerves, (2) medium-sized splanchnic nerves directed towards thoracic viscera, some of which give off branches towards costovertebral joint plexuses and, described for the first time in man, (3) small nerves which ramify extensively and form nerve plexuses in the capsule of the costovertebral joints. The majority of the ramifications is formed by the nerves of the third category. The existence of Kuntz's nerve, connecting the 2nd intercostal nerve and 1st thoracic spinal nerve, is confirmed in four specimens. The nerve plexuses of the costovertebral joints receive a segmentally organized innervation: they receive their input from the neighbouring sympathetic segment and the one cranial to it. It is concluded that the thoracic sympathetic branches in man show a complex, segmentally organized pattern and may have a considerable component of somatosensory nerve fibers. The complex relationships must be taken into account in surgical sympathectomies.

Female↗
PubMed1987

The extrinsic innervation of the rat kidney.

The anatomy of the extrinsic renal nerves is described making use of an in toto staining procedure for acetylcholinesterase activity. Nervous connections between the kidney and the celiac plexus, major and minor splanchnic nerves, the lumbar splanchnic nerves and the intermesenteric nerve plexus have been established. Bundles of nerve fibers enter or leave the kidney in the (peri-) hilar region. The occurrence of inter- and intraindividual variability is emphasized. Implications of these findings for the use of the rat as an experimental animal in denervation experiments are discussed.

Animals↗
PubMed1986

Differences between medical students and doctors in memory for clinical cases.

Many studies dealing with differences between students' and doctors' memory for clinical cases have yielded puzzling results. In this paper it is claimed that these are due to the use of inadequate techniques for isolating chunks inherent in the stimuli and the data. The purpose of this paper is to investigate whether the techniques of propositional analysis yield a clearer picture. Using this technique, the analysis of two sets of data is presented. The results show a clear difference between doctors and students when relevant clinical information is isolated from irrelevant information. This supports the notion that the process involved in the memory for clinical cases is far more complex and involves the ability to make inferences from a highly developed knowledge base.

Clinical Competence↗
PubMed1986

Some aspects of the peripheral nervous system in the human fetus as revealed by the acetylcholinesterase in toto staining method.

By means of the AChE in toto staining method (Baljet and Drukker 1975) the peripheral nervous system in several human fetuses has been investigated. Especially concerning the peripheral autonomic nervous system some striking results were found. In the human fetus there exists a large variability in number and diameter of the communicating rami. Many ganglia in the sympathetic trunks are fused. The major splanchnic nerve arises at various levels from the thoracic sympathetic trunks as well as many smaller thoracic sympathetic nerves. Furthermore various visceral nerves and nerve related elements are presented in this study.

Acetylcholinesterase↗
PubMed1985

Medical problem-solving: some questionable assumptions.

This paper questions the idea that expert doctors use the hypothetico-deductive method when developing diagnoses of routine clinical cases. Up to now, this has not been justified by empirical evidence but by two indirect arguments. The first is that it is the standard procedure of scientific method. The second is that it is supported by research in cognitive psychology comparing the problem-solving behaviour of experts and novices. It is argued in this paper that both areas have been misinterpreted. In particular, the evidence from research in cognitive psychology on expert-novice comparisons indicates that the use of the hypothetico-deductive method is a characteristic of novices rather than experts. Experts use what are called strong methods, which are dependent on a highly elaborated and structured knowledge base. It is concluded that a considerable amount of research on the nature of such strong methods in expert clinical reasoning is needed before any confident claims can be made regarding the use of the hypothetico-deductive or any other method.

Cognition↗
PubMed1985

Retroperitoneal paraganglia and the peripheral autonomic nervous system in the human fetus.

By means of the AChE in toto staining method retroperitoneal paraganglia and the peripheral autonomic nervous system in human fetuses have been investigated. Many small retroperitoneal paraganglia are present near the sympathetic trunks close to the sympathetic trunk ganglia. In the thoracic region small paraganglia are present in the intercostal spaces. Small splanchnic nerves entering small paraganglia have been described. In the lower sacral region no paraganglia are present. The major splanchnic nerve arises at various levels from the sympathetic trunks as well as many smaller thoracic splanchnic nerves. Intermediate ganglia are present in the major splanchnic nerve, the smaller splanchnic nerves and the communicating rami. In the sympathetic trunks many ganglia are fused. In the human fetus there exists a large variability in number and diameter of the communicating rami. Interconnecting bundles of nerve fibers between the left and right sympathetic trunks are present at all levels, but most numerous at the sacral level.

Autonomic Nervous System↗
PubMed1985

The development of the peripheral autonomic nervous system in relation to the gastro-intestinal tract.

In this study the development of vagus nerves and the development of sympathetic nerves related to the development of the upper gastro-intestinal tract was studied in the rat from 12.5 days p.c. until birth by means of enzyme histochemical methods applied to sections and toto preparations. A striking time relation between the ingrowth of the vagus nerves as well as the sympathetic nerves and the appearance of acetylcholinesterase (AChE)-positive cells in the wall of the upper gastro-intestinal tract is established. The maturation of the upper enteric ganglion cells is dependent on the presence of a vagal influence. The vagal ingrowth of the stomach starts at about day 12.5 p.c. In AChE toto preparations it is established that the basic distribution pattern as described in the adult rat is complete at day 15 p.c. However, in contrast with the adult state, gastric branches can be traced up to the pylorus and the greater curvature until day 18 p.c. During the 18th day p.c. there is a tremendous increase in the surface area of the stomach. This increase in surface area of the gastric wall and relative decrease in vagal outgrowth leads to the adult configuration of vagal ramifications in relation to the wall of the stomach which can already be observed on the 19th day p.c.

Acetylcholinesterase↗
PubMed1985

A mesoscopic technique for the study of the development of the peripheral system in rat foetuses.

UNLABELLED: In order to study the morphogenesis of the nervous system in the rat an acetylcholinesterase in toto method for staining nervous tissue in rat foetuses was developed. PROCEDURE: Rat foetuses of 14-22 days are fixed "en bloc" for 24 hours in a cold sucrose-formol solution. Fixed specimens are rinsed for 2 days in cold 0.22 M sucrose in a sodiumcacodylate buffer (pH 7.2). The specimens are cut (mid-)sagittally with the aid of a razor-blade, and incubated in a medium of acetylthiocholine iodide in acetate buffer (pH 5.0). Then, dehydration in glycerine/water mixtures of increasing glycerine content follows. The specimens may be stored in pure glycerine or embedded in epoxy-resin blocks and can be studied under a binocular dissecting microscope. In using this in toto staining method both the continuity of the central and peripheral parts of the nervous system as well as details up to the level of individual perikarya and motor endplates are preserved. With this mesoscopic method the three-dimensional architecture of the peripheral nervous system and its topological relations to other structures can be studies in one specimen. The exact procedure and the results as well as a method for embedding specimens in epoxy-resin blocks for teaching purposes are described. The advantages of this mesoscopic staining method for foetuses are discussed.

Acetylcholinesterase↗