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Biomedical subjects

P Mukherjee

Publications and source records attributed to P Mukherjee.

At least 109 records · Page 6Linked to original sources
PubMed1984

Aggregation and fusion of unilamellar vesicles by poly(ethylene glycol).

Various aspects of the interaction between the fusogen, poly(ethylene glycol) and phospholipids were examined. The aggregation and fusion of small unilamellar vesicles of egg phosphatidylcholine (PC), bovine brain phosphatidylserine (PS) and dimyristoylphosphatidylcholine (DMPC) were studied by dynamic light scattering, electron microscopy and NMR. The fusion efficiency of Dextran, glycerol, sucrose and poly(ethylene glycol) of different molecular weights were compared. Lower molecular weight poly(ethylene glycol) are less efficient with respect to both aggregation and fusion. The purity of poly(ethylene glycol) does not affect its fusion efficiency. Dehydrating agents, such as Dextran, glycerol and sucrose, do not induce fusion. 31P-NMR results revealed a restriction in the phospholipid motion by poly(ethylene glycol) greater than that by glycerol and Dextran of similar viscosity and dehydrating capacity. This may be associated with the binding of poly(ethylene glycol) to egg PC, with a binding capacity of 1 mol of poly(ethylene glycol) to 12 mol of lipid. Fusion is greatly enhanced below the phase transition for DMPC, with extensive fusion occurring below 6% poly(ethylene glycol). Fusion of PS small unilamellar vesicles depends critically on the presence of cations. Large unilamellar vesicles were found to fuse less readily than small unilamellar vesicles. The results suggest that defects in the bilayer plays an important role in membrane fusion, and the 'rigidization' of the phospholipid molecules facilitates fusion possibly through the creation of defects along domain boundaries. Vesicle aggregation caused by dehydration and surface charge neutralization is a necessary but not a sufficient condition for fusion.

Freeze Fracturing↗
PubMed1984

Chemical transformation of Swiss mouse embryo fibroblasts in primary culture.

Trypsinized secondary cultures of various cell systems have been frequently used by different investigators as models to study, in vitro chemical transformation. In the present study, non-trypsinized primary cultures of fibroblasts derived from fetuses of 14 days gestational age have been used to find out the timings of in vitro chemical transformation by 20-methylcholanthrene and has been designated as PMM-14 cells. These PMM-14 cells have been compared with trypsinized cultures of the same cell systems. The criteria for neoplastic transformation considered in the study involved the appearance of morphological changes, indefinite growth in tissue culture, acquisition of tumorigenic potential in vitro as evidenced by in vivo tests and in vivo latency period for palpable tumor formation. The time span of neoplastic transformation of non-trypsinized embryo fibroblasts in culture was remarkably reduced in comparison with trypsinized cultures of same cell systems. Such discrepancy seems to be due to repeated use of trypsin which may replace many of vital cell surface molecules causing a delay in the expression of carcinogen-induced malignancy. Similarly, repeated subculture before transformation may also have a role in the delayed expression of malignancy.

Animals↗
PubMed1981

Effect of medroxyprogesterone acetate contraception on human serum enzymes.

Activities of five enzymes were determined biochemically in the serum of a woman taking the injectable contraceptive, depo-medroxyprogesterone acetate (DMPA), 150 mg every 3 months for 2 years. The specific activities of SGOT, SGPT, and alkaline phosphatase (AP)-the enzymes commonly discerned in tests on the function of the liver-do not show any change with long-term treatment of this steroid contraceptive. Activities of serum acid phosphatase (ACP) and acetylcholinesterase (AChE) in red cells show significant increase. DMPA contraception has no apparent harmful effect on liver function, although the rise in ACP and AChE activities may be related to some pathological condition.

Acetylcholinesterase↗
PubMed1980

Long-term contraception with Depo-Provera: a clinical evaluation.

Depo-Provera has been used as a long-acting injectable contraceptive. The results of the study carried out for more than 2 years indicate that the depot formulation of medroxyprogesterone acetate (DMPA, Depo-Provera) at a dose of 150 mg at 90-day intervals appears to be acceptable to some women of this part of India, though many of them experience menstrual problems. However, irregular and/or excessive menstrual bleeding diminishes with long-term use of the contraceptive and a high percentage of users become amenorrheic. No major adverse reactions were observed and the minor side effects are comparable to those reported for the oral contraceptives. There was a tendency for weight-gain by the patients and the endometrium became atrophic or "resting" with the prolongation of the therapy.

Adolescent↗