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Biomedical subjects

N Roy

Publications and source records attributed to N Roy.

105 records · Page 6Linked to original sources
PubMed1979

Structure of Klebsiella type 61 capsular polysaccharide.

An aldotriouronic acid was isolated from the acid hydrolyzate of the polysaccharide from Klebsiella Type 61 (K-61), and its structure was established. Degradation of the permethylated polysaccharide with base established the identity of the sugar unit preceding the glucosyluronic acid residue. The modes of linkage and the sequence of different sugar residues were further confirmed by Smith degradation of K-61. The anomeric configurations of the different sugar residues were determined by oxidation of peracetylated native, and carboxyl-reduced, polysaccharides with chromium trioxide. The anomeric configuration of nonreducing D-galactosyl side-chains was further confirmed by enzymic degradation of K-61. Finally, gentiobiose was identified in the partial, acid hydrolyzate of K-61. Based on these results, the structure assigned the repeating unit of K-61 was as follows.

Carbohydrate Conformation↗
PubMed1978

An improved 11 alpha-hydroxylation of progesterone by Aspergillus ochraceus TS.

1. The stereospecific hydroxylation of progesterone exclusively to its 11 alpha-hydroxy derivative by Aspergillus ochraceus TS is reported. 2. There is no secondary metabolite (6beta, 11 alpha-dihydroxyprogesterone) formed even when the transformation was attempted with different concentrations of the substrate (200 microgram/ml-200 mg/ml) for prolonged with Zn2+ at a concentration of 50 microgram/ml identical results were obtained. 3. Similar results were also obtained at different pH values of the culture medium.

Aspergillus↗
PubMedDate not supplied

A 61-kb ring chromosome shows an ARS-dependent increase in its mitotic stability in the mcm2 mutant of yeast.

We have studied the effects of ARS addition and deletion on the maintenance of a 61-kb ring derivative of chromosome III in a minichromosome maintenance mutant of yeast carrying the mcm2-1 mutation. When this ring chromosome, CIIIR, had either of its two strong origins deleted, the resultant chromosome showed a much greater instability in the mutant as compared to that of the wild-type strain. Integration of more ARSs improved the maintenance of CIIIR in the mutant but not in the wild-type strain. Increase in the size of CIIIR, without any ARS addition, did not improve the stability in either strain. A spontaneous revertant for improved growth at 35 degrees C also co-reverted for minichromosome and CIIIR maintenance. The results suggest that ARS malfunctioning leads to minichromosome and chromosome loss from mutant cells, affecting their growth at higher temperatures.

Adenosine Triphosphatases↗
PubMedDate not supplied

Sensitive biomarker of polycyclic aromatic hydrocarbons (PAHs): urinary 1-hydroxyprene glucuronide in relation to smoking and low ambient levels of exposure.

The study was conducted in a Chinese population with occupational or environmental exposures to polycyclic aromatic hydrocarbons (PAHs). A total of 106 subjects were recruited from coke-oven workers (workers), residents in a metropolitan area (residents) and suburban gardeners (gardeners). All subjects were monitored twice for their personal exposures to PAHs. The biological samples were collected for measurements of 1-hydroxypyrene (1-OHP) and cotinine in urine. The geometric means of personal exposure levels of pyrene, benz(a)anthracene (BaA) and benzo(a)pyrene (BaP) in workers were 1.470, 0.978 and 0.805 microg m-3, respectively. The corresponding levels in residents were 0.050, 0.034 and 0.025 microg m-3; and those in gardeners were 0.011, 0.020 and 0.008 microg m-3, respectively. The conjugate of 1-OHP with glucuronide (1-OHP-G) is the predominant form of pyrene metabolite in urine and it showed strong associations with exposures not only to pyrene, but also to BaA, BaP and total PAHs. Most importantly, a significant difference in 1-OHP-G was even detected between the subgroups with exposures to BaP at < 0.010 and > 0.010 but < 0.020 microg m-3, suggesting that 1-OHP-G is a good marker that can be used for the risk assessment of BaP exposure at levels currently encountered in ambient air. Furthermore, multiple regression analyses of 1-OHP-G on PAHs exposure indicated that cigarette smoke was a major confounding factor and should be considered and adjusted for while using 1-OHP to estimate PAHs exposure.

Air Pollutants↗
PubMedDate not supplied

Occurrence of specific glycoprotein factor(s) in goat epididymal plasma that prevent adhesion of spermatozoa to glass.

Highly motile goat cauda-epididymal spermatozoa, when diluted markedly with a modified Ringer's solution, bind (approx. 100%) rapidly to the glass surface of haemocytometer. However, presence of epididymal plasma (EP, 2 mg protein/ml) in the dilution medium prevents nearly completely sticking of cells to the glass surface. The anti-sticking factor (ASF) of EP that prevents adhesion of spermatozoa to glass is nondialysable, heat-stable and sensitive to the action of trypsin. ASF is a glycoprotein that binds with high affinity to concanavalin a-agarose. EP-proteins (approx. 85%) that did not bind to the affinity column had little antisticking activity, indicating high protein specificity for ASF. Addition of exogenous Ca++ (1 mM) and Mg++ (4 mM) had no effect on the activity of ASF.

Animals↗