Biomedical subjects
Publications and source records attributed to M Hasan.
The floor of the rat brain fourth ventricle has been divided into five zones to study the surface ultrastructure of the ependymal cells. Regional variations in the form of dense ciliation, sparse ciliation, central tufts of cilia, solitary cilia, pores, clavate and filiform microvilli have been observed.
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DDVP is an organophosphate pesticide whose neurotoxicity, in the form of cholinesterase inhbition, is well-known. Rats, weighing 200-225 g were given intraperitoneal injections of 3 mg/kg. DDVP daily for 10 days. Following perfusion-fixation, ultrathin sections of the cerebellum and spinal cord were examined with an electron microscope. A large number of electron-dense bodies exhibiting electron-lucid vacuoles were discernible in the perikarya of cerebellar neurons. Aggregations of mitochondria were also seen. Myelin-figures in dendrites and axons of the spinal cord were detected. Evidence of oedema was evident in the spinal cord.
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3-Methoxy-4-hydroxyphenylglycol (MHPG) was measured in lumbar spinal fluid of 20 subjects with hypertension of varied etiology and severity. There was a significant correlation between the concentration of MHPG and the severity of hypertension. However, changes in the concentration of vanillylmandelic acid in the urine of these subjects were insignificant. In six subjects, administration of clonidine or alpha-methyldopa, two centrally acting antihypertensive drugs, was associated with a significant lowering of MHPG concentrations. These data support the hypothesis that central catecholamines are involved in clinical hypertension.
The levels of dopamine, noradrenaline and 5-hydroxytryptamine were estimated in the hypothalamus and limbic areas, corpus striatum, cerebellum and the brain-stem of rats administered thallous acetate (5 mg/kg i.p.) daily for 7 days. Significant decreases in the concentration of dopamine occurred in the hypothalamus, limbic areas and corpus striatum. Noradrenaline did not reveal significant alteration in any of the regions of the brain examined. The concentration of 5-hydroxytryptamine was significantly lowered in the corpus striatum, cerebellum and the brain-stem.
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Fermentation balance studies were carried out on Clostridium tertium grown with and without nitrate in the medium. Nitrate reduction increased the efficiency of energy produced from glucose by permitting the utilization of additional sites of substrate level phosphorylation. The effect was even more dramatic in C. tertium than in C. perfringens, with increased cell yields of about 30% being observed in the former compared with 20% in the latter. Unlike C. perfringens, C. tertium responded to the presence of nitrate in the medium with an increased growth rate. A slight increase in the Y ATP of these cultures was also observed, and quantitatively, this appeared to be consistent with the prediction of Stouthammer and Bettenhaussen that Y ATP will vary with the growth rate. Thus, C. tertium, like C. perfringens, was able to use nitrate as an electron acceptor in conjunction with its energy metabolism, suggesting that this may be widespread among the nitrate-reducing anaerobes.
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Thallotoxicosis following accidental ingestion of thallium in rodenticides and in cases of homicidal and suicidal ingestion are well documented in the literature. The mechanism of action of thallium, in particular the pathogenesis of its neurotoxic manifestations, is not entirely clear. This is the first electron microscopic investigation dealing with the effect of thallium on the oligodendrocytes of the area postrema. The area postrema is devoid of a blood-brain barrier, indicating that the hemoneural transport of thallous ions may be quite substantial in this region. Rats weighing 155-175 g were given intraperitoneal injections of 5 mg/kg thallous acetate for 7 days (35 mg/kg total dose). Following perfusion-fixation, ultrathin sections of area postrema were examined with an electron microscope. The oligodendrocytes exhibited pleomorphic vacuolated dense bodies in their perikaryon. The findings were also suggestive of the fact that either the multiplication of oligodendrocytes or their aggregation to form "giant cell" was operative.
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