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Biomedical subjects

R Coleman

Publications and source records attributed to R Coleman.

At least 163 records · Page 9Linked to original sources
PubMed1995

Cloning of a new "finger" protein gene (ZNF173) within the class I region of the human MHC.

The human major histocompatability complex contains genes of both immune and nonimmune importance. Recently, several genes encoding novel, non-HLA products have been described in this area. We have performed positional cloning of short fragment cDNA sequences from the class I region of the human MHC using a hybridization selection approach. This report describes isolation of full-length cDNA clones and partial genomic clones that encode a protein that contains two domains rich in cysteine and histidine similar to those characteristic of metal-dependent DNA binding proteins (C3HC4). The predicted protein also contains a domain thought to form a coiled-coil that may promote dimerization. A third feature is a polyglutamic acid region near the carboxyl terminus of the conceptual protein. Because of these properties, we have named this gene product acid finger protein (AFP). Although the biological role of AFP is unknown at present, one potential function is binding of nucleic acids. The gene (ZNF173) is expressed in multiple tissues and is conserved among mammals. In particular, the mouse and human coding regions are highly conserved. In addition to AFP, other related sequences have been localized to the MHC, suggesting that multiple AFP-like genes exist in this area.

Amino Acid Sequence↗
PubMed1995

Fractionation of livers following diosgenin treatment to elevate biliary cholesterol.

The plant saponin, diosgenin, is known to induce a marked increase in biliary cholesterol/phospholipid ratio. We reasoned that putative biliary lipid supply vesicles might be similarly enriched with cholesterol. Seven-day diosgenin feeding to rats resulted in significantly increased biliary cholesterol and cholesterol/phospholipid ratio, but had no effect on total cholesterol or phospholipid content of the liver. Subcellular fractionation of livers showed no selective increase in any fraction (nuclear, mitochondrial, lysosomal, microsomal) of the homogenate. Further subfractionation of microsomal or nuclear (plasma membrane) fractions also showed no difference between control and diosgenin groups. Thus, no intracellular vesicle fraction has been identified with the provision of the enhanced biliary cholesterol and the results are discussed in terms of the possible involvement of cytosolic lipid-binding proteins as putative lipid carriers to the canalicular membrane as an alternative to the presence of the lipid in lipid supply vesicles.

Animals↗
PubMed1995

Reducing the levels of formaldehyde exposure in gross anatomy laboratories.

BACKGROUND: A method is described in which formaldehyde levels are greatly reduced in our gross anatomy laboratory in order to comply with increasingly severe safety and health regulations. METHODS: A novel type of dissection "bed" has been introduced which incorporates an internal motor that causes a downflow of formaldehyde-rich vapors, which are absorbed by a replaceable active carbon filtration system. RESULTS: Use of the new dissection "beds" has resulted in the recirculated air being virtually formaldehyde-free. Formaldehyde vapor levels in our gross anatomy laboratory have been greatly reduced and are typically in the range of 0.03-0.09 ppm. CONCLUSIONS: The new system allows us to comply with safety and health regulations and provide a dissection room with an excellent working environment.

Air Pollution, Indoor↗
PubMed1995

Hepatobiliary function and toxicity in vitro using isolated hepatocyte couplets.

1. Hepatocyte couplets can be routinely prepared from rat liver to produce a suitable in vitro model for polarized primary cells. 2. Centrifugal elutriation provides a means of producing enriched subpopulations of periportal and perivenous couplets from the same liver, thus providing a means of studying the influence of zonal heterogeneity on hepatobiliary function. 3. The maintenance of structural and secretory polarity demonstrated by hepatocyte couplets provides a convenient in vitro system for mechanistic studies of factors both regulatory and adversely affecting hepatobiliary functions. 4. Couplets are also uniquely appropriate for specific studies of regulation at the biliary pole, on the performance of junctions and on the maintenance and rate of transcytotic movement. 5. The possibility also exists that effects of an in vivo pre-exposure to agents causing hepatobiliary dysfunction can be assessed in couplets ex vivo.

Animals↗
PubMed1995

Depletion of total salivary gland protein in blood-fed Anopheles mosquitoes.

Reduction in total salivary gland protein from four anopheline vectors of human malaria, Anopheles stephensi Liston, An. albimanus Wiedmann, An. gambiae Giles, and An. freeborni Aitken, was quantified after mosquitoes blood-fed to repletion on human volunteers, hamsters or through a Baudruche artificial membrane. Total salivary gland protein from pools of six unfed mosquitoes ranged from 4.33 to 7.91 micrograms/ml. The difference between the total protein of glands from unfed and blood-fed mosquitoes for all species ranged from 1.77 to 3.12 (micrograms/ml for six pooled salivary glands. Total salivary gland protein for mosquitoes blood-fed to repletion was significantly less than that of unfed controls from the same cohort. Reduction in total salivary gland protein for An. freeborni and An stephensi blood fed to repletion on human volunteers, hamsters, and a Baudruche membrane ranged from 24 to 46%, from 43 to 56%, and from 24 to 51%, respectively. An. stephensi mosquitoes were allowed to blood feed on humans for 0 (unfed), 0.5-, 1.0-, 2.0-min time periods or to repletion (> 2-5 min). As feeding time increased, there was a significant decrease in total amount of protein in the salivary glands. This decrease was proportional over time, indicating that salivation occurred continuously from the beginning (probing) of blood feeding to withdrawal of the mosquito mouthparts at repletion. These data indicate that during blood feeding there difference between species in the salivary gland output measured as amount of protein depleted from the salivary glands and that depletion of salivary protein from the glands occurred continuously as mosquitoes fed to repletion.

Animals↗
PubMed1995

Generalized endemic Kaposi's sarcoma.

Kaposi's sarcoma (KS) is a multicentric neoplasm thought to arise from both vascular and lymphatic endothelium. It is subdivided into four main categories on the basis of clinical features, course and prognosis. We report a 54-year-old Afro-Caribbean male, living in the UK for the past 26 years, with classic features of generalized endemic KS. Because he has never lived on the African continent, the role of genetic rather than environmental factors is favoured in the aetiology of KS in this individual. This disorder is rarely seen in Afro-Caribbeans living in the UK, who have never actually lived in Africa.

Africa↗
PubMed1995

Ultrastructural changes in mitochondria of the adrenal cortex of iron-deficient rats.

Male Sprague-Dawley rats aged 3 weeks that were maintained on an iron-deficient diet for 4-5 weeks developed severe anemia with markedly reduced hemoglobin levels (4.11 +/- 0.20 Hb g% versus controls 12.74 +/- 0.15 Hb g%). On sacrifice, the adrenal glands were removed and processed for light and transmission electron microscopy and enzyme cytochemistry. The major histological and ultrastructural changes in the adrenal cortex in response to the iron deficiency were seen in cells of the zona fasciculata, especially in its outer region, and to a lesser degree in cells of the zona reticularis. Structural changes were seen in the mitochondria of these cells, which often became grossly enlarged and developed unusual electron-dense inclusions. In addition, the lipid droplets in the iron-deficient cells of these regions were much less developed and less prominent compared with controls. Quantitative cytochemical localization of succinic dehydrogenase (SDH) activity in the adrenal glands showed that in iron-deficient rats there was an increase in SDH activity in the zona fasciculata (46%) and in the zona reticularis (74%), whereas there was a reduction of approximately 41% in SDH activity in the zona glomerulosa. Serum corticosterone levels were significantly raised in the iron-deficient rats compared with the control rats. Our results indicate that severe nutritional iron deficiency in rats causes ultrastructural and cytochemical changes in the mitochondria of the adrenal cortex accompanied by increased secretion of corticosterone.

Adrenal Cortex↗
PubMed1994

Disruption of canalicular function in isolated rat hepatocyte couplets caused by cyclosporin A.

Isolated rat hepatocyte couplets were used to study the effects of different concentrations of cyclosporin A in relation to canalicular function. Canalicular function was assessed by counting the percentage of couplets which were able to accumulate the fluorescent cholephile cholyl lysyl fluorescein (CLF) into the canalicular vacuole between the two cells, i.e. canalicular vacuole accumulation (CVA). At lower doses, the immunosuppressor increased the CVA, reaching 121 +/- 3.86% of control at 25 nM cyclosporin A. However, higher doses of cyclosporin A induced a concentration-dependent inhibition of CVA to 64.0 +/- 3.51% of control at 100 nM. Modifications in canalicular area (as % couplet area) were also observed. Image analysis of the fluorescent image showed that cyclosporin A (25 nM) increased canalicular area by 25% (of control); however, this parameter decreased to 36% of control at 100 nM cyclosporin A. In addition, at 100 nM, cyclosporin A reduced the proportion of couplets retaining CLF within the canaliculus to 75.0 +/- 6.59% of control. Treatment of couplets with cyclosporin A (0-2 microM) for 15 min revealed that reduced glutathione (GSH) intracellular content does not change significantly at these doses. However, alteration in pericanalicular F-actin at 100 nM cyclosporin A may be an important factor in the disruption of the canalicular function induced by higher doses of the immunosuppressor.

Actins↗
PubMed1994

Ultrastructural and cytochemical changes in the heart of iron-deficient rats.

Male Sprague-Dawley rats aged 3 weeks that were maintained on an iron-deficient diet for 4-5 weeks developed severe anemia with markedly reduced hemoglobin levels (3.94 +/- 0.14 Hb g% versus controls 12.9 +/- 0.11 Hb g%). Iron-deficiency resulted in marked cardiac hypertrophy (cardiomegaly). On sacrifice, the hearts were processed for light and transmission electron microscopy. The major ultrastructural changes were found in the hypertrophied left ventricle and left papillary muscles. Iron-deficiency caused marked edema in myocytes, sarcomeres were out of register, and degeneration and discontinuities in myofilaments were common. Iron-deficiency resulted in the enlargement of the interfibrillar mitochondria, changes in the matrix and the formation of electron-dense amorphous bodies. The ultrastructural changes in myocytes in response to experimental iron-deficiency were similar to those described by others in cases of experimental ischemia or hypoxia. Mitochondrial changes were also found in the atria of iron-deficient rats. Quantitative cytochemical measurement of succinate dehydrogenase activity was determined and was shown to be substantially reduced in the iron-deficient heart. In severely iron-deficient rats restored to a normal iron-sufficient diet for two weeks, hemoglobin levels recovered, however the myocytes of the hypertrophied left ventricles and papillary muscles continued to show severe degenerative changes.

Animals↗