Biomedical subjects
Publications and source records attributed to J Nolte.
Techniques of problem-based learning requiring no increase in faculty effort, were applied to a large-group medical neurobiology course. Students were found to learn as effectively, and to enjoy themselves more, when the new format was implemented.
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This paper compares the results of plasma drug level estimations for 30 patients receiving clonazepam and 39 patients taking carbamazepine (assessing total and free carbamazepine concentrations together with carbamazepine epoxide levels) with the clinical features of seizure control. Owing to the small numbers of seizure-free patients, the power of the study was insufficient to justify absolute conclusions being drawn. However there appeared to be a trend which suggested that drug level estimations in both situations had virtually no clinical relevance. This causes one to question the growing reliance on plasma drug level estimation in the treatment of epilepsy and, because of the low power of the study, demands extension of the work to confirm its significance. This type of research in epilepsy, based exclusively on a secondary and tertiary referral source, has inherent difficulty in that a conspicuously low number of well controlled patients is included. Acknowledgement of this fact should lead one to appraise critically other papers giving dogmatic statements regarding therapeutic ranges of anticonvulsant plasma levels.
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The iris of the toad Bufo marinus is directly photosensitive and will constrict in response to light striking only the iris. This is true even when the iris is isolated from the rest of the eye, and therefore from reflex neuronal influences initiated in the retina. This autonomous response is probably mediated by the sphincter pupillae muscle, since no specialized photoreceptors are present in the iris, nor does the sphincter exhibit any specializations likely to subserve a purely photoreceptive function. The photosensitive sphincter appears typical of smooth muscle and, like mammalian sphincters, possesses many intercellular junctions. The iris possesses a well-developed neuronal plexus with fibers projecting into the sphincter muscle layer. Nerve terminals contain small, agranular (30-70nm) and large, dense-cored (80-120nm) vesicles. No consistent postsynaptic specializations are seen on any cells of the iris, including the cells of the sphincter muscle. The anterior pigment epithelial cells of the iris appear specialized and resemble the myoepithelial dilator muscle described by Kelly and Arnold ('72) for the iris of rats.
An electron microscopic examination of the parietal retinas of Anolis carolinensis and Iguana iguana demonstrated within each retina (1) two distinct populations of neurons, (2) two populations of glia, and (3) a population of photoreceptors which could not be subdivided. A small population of very electron-dense cells, in many respects similar to photoreceptors, was also found in the iguana. Correspondingly dark processes were found in the plexiform layer of each retina. Parietal photoreceptors generally resemble cones of the lateral eye. Glial cells were sub-classified on the basis of the location of their somata and the disposition of their processes. Neurons were identified by virtue of their cytology and their reception of axosomatic ribbon synapses from unidentified plexiform layer processes. Neuronal subtypes were located on opposite sides of the plexiform layer. Neurons distal to that layer were found to project the initial segments of their processes into the plexiform layer parallel to its long axis, while neurons central to the plexiform layer projected axons centrally and dendrites radially into the plexiform layer. The existence of at least two neuronal populations and of interphotoreceptor synapses suggests that photosensory processing within the parietal retina may be more complex than previously assumed.
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Freeze-fracture studies of pathologically changed mitochondria in situ from muscle biopsies of a 9.5-year-old girl with a mitochondrial myopathy were correlated with clinical, biochemical and histochemical investigations. In the ultrathin sections giant mitochondria with densely packed cristae membranes - often reoriented to concentric circles - and, in addition, paracrystalline mitochondrial inclusions were found. The freeze fracture faces of such transformed mitochondria and preparations of their inner and outer membranes provided a morphological insight in the macromolecular structure of the mitochondrial membrane under such pathological conditions. The results lead to the hypothesis that part of the transformed mitochondria stay active functionally for an extended period by maintaining the delimitation from the cytoplasm and by preserving the macromolecular membrane architecture. This hypothesis could explain the slow progression of the myogenic symptoms.
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Two sisters with exercise-induced myalgias, muscular weakness and contractures are reported. Neurologic and psychiatric findings were normal, nor did electromyography, serum enzymes and ischemic forearm exercise test reveal specific findings. Under the light microscope multiple muscle fibers contained small vacuoles which stained positive with Oil Red O. No further information resulted from histochemical examinations. In the more seriously affected patient morphometric analysis of electronmicrographs showed a tenfold increase of fat content in comparison to normal controls. Alterations in the enzymatic activities could be demonstrated in glycogenolysis, glycolysis and in fat metabolism, but there were no previously described enzyme defects such as phosphorylase deficiency, phosphofructokinase deficiency, phosphohexoisomerase inhibitor, carnitine or carnitine-palmityltransferase deficiency. Myopathy with lactic acidosis, prolonged muscular relaxation due to deficient reabsorption of sarcoplasmic calcium in the tubular system and dyskalemic paralysis can be ruled out on the basis of the clinical signs. This myopathy may be due to an as yet unknown metabolic disturbances.
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The iris of the grass frog Rana iiens, can respond to light even when isolated from the remainder of the animal. The iris is a three-layered structure, comprising a stromal layer and two layers of pigment epithelium. The sphincter pupillae, which is composed of pigmented smooth muscle cells, is embedded between the two layers of pigment epithelium. There is no dilator pupillae in this species. We have been unable to find any cells or any organelles in the iris which are anatomically specialized for photoreception in any obvious way.
Blocking factors are small polypeptide molecules that may appear in the serum of patients with cancer. These factors block the transformation of lymphocytes in culture to nonspecific mitogens such as phytohemagglutinin or concanavalin A and, therefore, may reflect changes in the immunocompetence of the patient. Blocking factors were monitored during the clinical course of thirty-five patients with cancer. These factors did not develop in patients with response to therapy whereas they did develop in patients without response. A third group of patients without response to therapy after a previous remission showed an absence of lymphocyte responsiveness in culture that was not due to blocking factors, suggesting that immune clone consumption had occurred. Dermal responsiveness to tumor antigen correlated with a favorable clinical course and was usually absent when serum blocking factors were present.
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