Biomedical subjects
J Gibson
Publications and source records attributed to J Gibson.
Aplastic anemia in association with gold therapy for rheumatoid arthritis.
Over a ten year period five patients developed aplastic anemia in association with gold therapy for rheumatoid arthritis. None of these patients was suitable for bone marrow transplantation due to the lack of a compatible sibling. Four patients with severe aplastic anemia died, despite intensive haemopoietic support and trials of gold chelating agents. Survival ranged from 22 to 103 days (mean 55 days) with death in each case being due to a combination of bleeding and infection. The remaining patient with moderate aplasia survived, recovering over a period of two to three years.
An analysis of peripheral blood burst forming units-erythroid in the polycythaemic states.
Peripheral blood burst forming units-erythroid (BFU-E) were measured by the plasma clot cell culture technique in patients with the various subtypes of polycythaemia and compared to normal. 10 patients with active polycythaemia rubra vera (PRV) were found to have a mean BFU-E level of 48 +/- 15.8 (SEM) per 5 X 10(5) cultured cells which was significantly different from normals (4 +/- 1.1, P less than 0.02), patients with controlled PRV (7 +/- 1.6, P less than 0.025), secondary polycythaemia (1 +/- 0.3, P less than 0.015) and relative polycythaemia (0, P less than 0.015). Burst forming units were found to fall to normal levels in patients with PRV with appropriate disease control and then to rise again in patients untreated for more than 18 months. Clinical aspects. Measurement of BFU-E levels from the peripheral blood could provide a useful adjunct from an accessible source in the differential diagnosis of polycythaemia as well as being of use in serial monitoring of patients with PRV.
Isolation of the carotenoid-containing cell wall of three unicellular cyanobacteria.
A carotenoid-containing membrane fraction devoid of chlorophyll and phycobiliproteins was isolated from three unicellular cyanobacteria, Synechococcus sp., Synechococcus leopoliensis UTEX 625, and Anacystis nidulans R-2, by aqueous-phase separation, hydrophobic chromatography, and differential centrifugation. The presence of 2-keto-3-deoxyoctonate, muramic acid, and diaminopimelic acid suggests that the preparation is highly enriched in cell wall. Electron micrographs of thin sections of this material showed C-shaped membrane profiles similar to those seen in other gram-negative cell wall preparations. The inactivation of cyanophage AS-1 by this fraction confirmed its identity as cell wall. The cell wall contained approximately equal weights of total carbohydrate and protein. Absorption maxima at 434, 452, and 488 nm indicated the presence of carotenoids. These were in the outer membrane and were not due to contaminating cytoplasmic or thylakoid membranes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the preparations showed a broad band of approximately 50,000 molecular weight which contained 35% of the total outer membrane protein. This band was resolved into at least two components running at approximately 50,000 and 52,000 molecular weight. The smaller of these polypeptides was a glycoprotein. The polypeptide components were unaffected by protease or detergent treatment in either whole cells or isolated cell wall preparations, indicating that the polypeptide components were not exposed to the surface or easily removed from the hydrophobic environment.
Import of proteins into mitochondria. The precursor of cytochrome c1 is processed in two steps, one of them heme-dependent.
The apoprotein of yeast cytochrome c1 is made outside the mitochondria as a larger precursor which is then processed in at least two steps. In the first step, it is transported across both mitochondrial membranes and converted by a matrix-localized protease to an intermediate form whose molecular weight is between that of the precursor and the mature form. The intermediate form is bound to the outer face of the inner membrane. This first step requires an energized mitochondrial inner membrane, but no heme. In the second step, the intermediate form is converted to the mature cytochrome. This second step requires heme; it is blocked in a heme-deficient mutant or in wild type cells treated with an inhibitor of heme synthesis. Import of cytochrome c1 into mitochondria thus proceeds via two distinct heme-free precursors and at least two maturation steps, one of them dependent on heme.
Marked overproduction of low density lipoprotein apolipoprotein B in a subject with heterozygous familial hypercholesterolemia. Effect of portacaval shunting.
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Clobazam in catamenial epilepsy. A model for evaluating anticonvulsants.
The cyclical exacerbations of epilepsy (catamenial epilepsy) were used to assess the antiepileptic effect of a benzodiazepine, clobazam. Doses of 20 mg, and in some cases 30 mg, per day were compared with placebo over predetermined ten-day periods in a double-blind cross-over study. The results were evaluated by preference in a sequential procedure. In 14 of 18 patients who received both treatments clobazam was superior to placebo, and in 4 patients no preference was established. Clobazam completely prevented seizures in most of the patients, and toxic effects were of low frequency and severity.
Imported mitochondrial proteins cytochrome b2 and cytochrome c1 are processed in two steps.
Cytochrome b2 of yeast is located in the space between the inner and outer mitochondrial membranes whereas cytochrome c1 is bound to the outer face of the mitochondrial inner membrane. Both proteins are made outside the mitochondria as larger precursors that are processed to their mature forms in two steps. In the first step, at least a segment of the precursor polypeptide chain penetrates into the mitochondrial matrix and is cleaved to an intermediate form by a matrix-localized soluble protease. This step requires an electrochemical gradient across the mitochondrial inner membrane. In the second step, the intermediate form is converted to the mature form. For cytochrome c1, this second step requires heme. Import of these two cytochromes thus involves a "detour" across the inner membrane.
Interstitial deletion of chromosome 7: a case report and review of the literature.
A de novo deletion 7q11 leads to q21.2 was identified in a newborn with genital and other minor clinical abnormalities and some degree of psychomotor retardation. A review of the literature revealed a number of cases of deletion 7q, which can be categorized into three groups according to their breakpoints. Attempts to correlate phenotype with genotype in these cases have been only moderately successful, and as yet only deletion 7q32 leads to qter can be associated with a definite clinical syndrome, although a tentative syndrome may be postulated in association with deletion of region 7q22 leads to 7q31.
Proximal tubular necrosis associated with maleic acid administration to the rat.
Administration of maleic acid to the rat is used as an experimental model of Fanconi's syndrome. To determine the site and extent of morphologic injury within the kidney after maleic acid administration, we systematically examined renal tissue using light, transmission electron, and scanning electron microscopy. Tissue was studied either immediately or 24 hours after rats received maleic acid, 200 mg. or 400 mg. per kg. of body weight, and was compared with tissue from controls. In kidneys of maleic acid-treated rats, evidence of injury was observed only in cells of the late pars convoluta and the pars recta in the medullary rays of the cortex and in the outer stripe of the medulla. Injured cells were characterized by an increase in cytoplasmic density, accumulation of numerous small vesicles in the apical region of the cells, abnormal-appearing mitochondria with compressed cristal membranes and flocculent densities, and focal loss of microvilli. Injury was apparent immediately after maleic acid administration and progressed to extensive necrosis by 24 hours after either the 200- or 400-mg. per kg. dose. Except for the presence of granular and hyaline casts in the lumena, the loops of Henle and distal convoluted tubules were normal. Collecting ducts in the outer medulla, but not in the cortex, medullary rays, or inner medulla, had significantly increased numbers of dark cells per total cell population when compared with controls (p less than 0.005). This increase in dark cells may represent an adaptive response of the medullary collecting duct to the functional abnormalities of maleic acid-induced Fanconi's syndrome. Collecting ducts showed no evidence of cell injury or necrosis. These observations provide evidence that maleic acid, like many other renal toxins, produces tubular injury and necrosis only in the proximal tubules, primarily in the medullary rays, and outer stripe of the medulla, and not in the distal tubules.
The use of rotating gratings for the treatment of amblyopia: a clinical trial.
The use of rotating gratings for the treatment of amblyopia was subjected to a controlled clinical trial. A treatment group (N = 19) observed rotating gratings for 15 min per week for 10 weeks and a control group (N = 19) observed a blank rotating disk for the same period. Both groups of amblyopes performed visually guided tasks to maintain their interest during treatment. Data were acquired in a double-masked manner. A second control group (N = 4) underwent weekly acuity evaluation without any form of treatment. Visual acuity was evaluated before and after each session and analyzed with a linear regression fit to a probit transform by a minicomputer. By using a criterion change in acuity of 10% Snell Sterling, we found no significant change of acuity in any group or between groups. These results demonstrate that rotating gratings are an insignificant variable in the treatment of amblyopia.
Chemical test papers for the clinical laboratory: the new frontier of "solid solution chemistry".
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Congress passes Health Science Promotion Act; clarifies and amends health planning law.
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Competition component of planning considered in national conference.
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The phylogeny of prokaryotes.
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Bureau of Health Planning clarifies definition of provider: new interpretation will benefit hospitals as HSAs fill board vacancies.
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Exchange transfusion.
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Do genealogical patterns in purple photosynthetic bacteria reflect interspecific gene transfer?
It is generally thought that interspecific (lateral) transfer of genes is so extensive among bacteria that it is difficult, and perhaps impossible, to determine their phylogenetic relationships. Ambler and coworkers reflect this in their suggestion that the relationships seen among cytochrome c sequences of the Rhodospirillaceae are merely the result of a haphazard lateral transfer of the particular gene, and give no indication of the true bacterial phylogenies. However, if comparative analysis of several unrelated macromolecules yields essentially the same phylogenetic tree, then that pattern is extremely unlikely to reflect the lateral transfer of genes. We have also determined 16S ribosomal RNA catalogues for many of the Rhodospirillaceae in investigated by Ambler et al. and here we use these two sets of data to compare molecular phylogenies for these bacteria.