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Biomedical subjects

N Chowdhury

Publications and source records attributed to N Chowdhury.

At least 37 records · Page 2Linked to original sources
PubMed1991

Trends of HIV-1 risk reduction among initiates into intravenous drug use 1982-1987.

To assess how injection practices may have changed during the course of the AIDS epidemic, active intravenous drug users (IVDUs) recruited from the community were asked to report year of first injection as well as specific details about the first 3 months after initial injection: frequencies of injection, using sterile needles, sharing needles and other equipment. For the analysis, the users were sorted into successive cohorts of initiation (by year of first injection), and tests for trends were completed using Mantel-Haenszel statistics. Among the 421 IVDUs who reported first injection between 1982 and 1987, the use of new sterile needles to self-administer drugs increased (p less than .05) along with its corollary behavior (i.e., using equipment one is sure that no one else had used before). Conversely, there was a decrease in the proportion of those who always used equipment previously used by another IVDU (p less than .05) and a decrease in the number of needle-sharing partners (p less than .01). Over the 6 years, heroin as first drug decreased and cocaine increased (p less than .01). Although these data are from a cross-sectional interview study, they suggest a shift toward lower risk practices among new IVDUs between 1982 and 1987. The shift from heroin to cocaine is compatible with other evidence on the cocaine epidemic.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Enzymatic evaluation of riboflavin status of infants.

Riboflavin status of solely breast-fed (SBF) infants aged 1-6 months (study 1) and solely or partially breast-fed (PBF) and weaned infants aged 6-24 months (study 2) was examined by the erythrocyte glutathione reductase activation test. Maternal riboflavin status and milk riboflavin content were also measured in study 1. Riboflavin status of the infants was significantly superior to that of their mothers. However, 35 per cent of SBF infants examined suffered from biochemical riboflavin deficiency as judged by the glutathione reductase test. Supplementary feeding of 6-8-month-old infants and weaning of older infants had positive effect on riboflavin status. There was no obvious relationship between riboflavin status and anthropometric status. Milk riboflavin concentration was comparable or only slightly lower than values reported for Western women, despite marked deficiency in the mothers.

Breast Feeding↗
PubMed1989

Distribution of zinc in parasitic helminths.

The distribution of zinc in representative groups of parasitic helminths was determined by the use of the atomic absorption spectrophotometer. The results of these analyses have shown that growing flukes (smaller forms) with active oogenesis and spermatogenesis contained more zinc than old (large) or very old adults with an empty uterus and large lobulated testes. In cestodes, the neck region and immature proglottids showed more zinc concentration than mature and gravid proglottids and fully grown cyst walls. Similarly, the youngest endogenous daughter cysts of Echinococcus granulosus contained more zinc in their walls than those of larger/older forms. Zinc was concentrated more in nematode eggs than in adult females.

Animals↗
PubMed1984

Effects of ox bile on the growth and organogenesis of Hymenolepis microstoma in vitro.

Hymenolepis microstoma has been cultured in vitro from 4 to 11 days of age using Eagle's medium (BME) supplemented with horse serum, lamb's liver extract and ox gall (dehydrated bile) in five different concentrations (0.025%, 0.1%, 0.2%, 0.5% and 1% all in BME) including a control without the added ox gall. The results of these experiments demonstrated that growth is related inversely to the concentration of ox gall in the media. However, the number of proglottids containing fertilized ova in the "lateral sacs" becomes higher in worms grown in the medium containing 0.025% ox bile than in those grown in the control medium. This number increases with the bile concentration up to 0.2%. It is concluded that bile stimulates oogenesis and in higher concentrations retards the growth of worms.

Animals↗
PubMed1976

Qualitative distribution of neutral lipids and phospholipids in Hymenolepis microstoma from the cysticercoid to the egg producing adult.

The distribution of neutral lipids and phospholipids in Hymenolepis microstoma has been studied using Fettrot, Sudan Black B, Sudan IV and copper phthalocyanin staining techniques. In the cysticercoid, neutral lipids are found in the outer membrane, the lining of the cysticercoid cavity, the tegument of the larval worm and the calcareous corpuscles. A decreasing gradient of phospholipids is found starting from the acellular layer, through the circular fibrous layer, the longitudinal fibrous layer, the adjacent dense zone and ending with the lining of the cysticercoid cavity. Phospholipids are also found in the calcareous corpuscles and the tegument of the larval worm. In the young adult (3 days p.i.) fat globules are first seen to accumulate in the last 2-3 proglottids. Until the 6th day p.i. they are found in the posterior third of the worm, surrounding developing gonads, but mostly concentrated along the transverse line. The mature proglottids contain fat, (a) in both granular and globular forms: in the folds of the uterus, sperm ducts, cirrus pouch and tegument (proximal cytoplasm), (b) in a diffuse form: in the vitellaria, ovary, testes and the tegument (distal cytoplasm). Pre-gravid and gravid proglottids show the largest fat globules. From the cleaving embryo to the fully developed oncosphere the concentrations of neutral lipids and phospholipids vary in form, intensity and location. In all strobilar forms of the parasite neutral lipids and phospholipids are found in the tegument and calcareous corpuscles. Although in H. microstoma lipid droplets are found in the excretory canals, all lipids in the proglottids are not absolutely waste products. From the results it would appear that they play a role in the maturation of gonads and transformation of the fertilized ovum to the oncosphere.

Animals↗
PubMedDate not supplied

A hepatocyte-targeted conjugate capable of delivering biologically active colchicine in vitro.

A derivative of colchicine was synthesized, in a manner that preserved its important structural features, and conjugated to an asialoglycoprotein. The conjugate was characterized by ultraviolet-visible spectrophotometry and protein analysis. An average coupling ratio of 2 mol of colchicine per mole of asialoglycoprotein was achieved. The conjugate was stable to incubation in serum but was split into its separate components under chemically reducing conditions. Incubation with cells in culture revealed that the conjugate had antiproliferative activity similar to that of colchicine, but only in asialoglycoprotein receptor-containing cells. There was no effect at all on asialoglycoprotein receptor (-) cells. Furthermore, the antiproliferative effect of the conjugate on receptor (+) cells was blocked by addition of a large molar excess of free asialoglycoprotein. Immunofluorescence microscopy revealed disruption of microtubules in cell cultures that were pretreated with the conjugate. These results indicate that a colchicine conjugate that is taken up specifically into cells by asialoglycoprotein receptors and released intracellularly in a biologically active form can be prepared.

Asialoglycoprotein Receptor↗