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Biomedical subjects

A Chatterjee

Publications and source records attributed to A Chatterjee.

At least 307 records · Page 17Linked to original sources
PubMed1985

Discrimination of epitopes identified by monoclonal antibodies by competitive binding to nitrocellulose bound antigens.

A new method is described for determining the distribution of epitopes identified by monoclonal antibodies. The method utilizes nitrocellulose membranes as a solid support for antigens which are rapidly adsorbed to nitrocellulose by vacuum-blotting and then used in competitive antibody binding assays. The distribution of epitopes is established by the reciprocal cross-blocking of radiolabeled antibody by increasing concentrations of unlabeled antibody. When unlabeled antibody does not block the binding of labeled antibody to antigen, the 2 antibodies recognize distinct epitopes. When unlabeled antibody blocks the binding of labeled antibody to antigen, the 2 antibodies recognize the same epitope. The method is rapid, sensitive and should be applicable to screening monoclonal antibodies to any epitope.

Antibodies, Monoclonal↗
PubMed1985

Epitope distribution and immunochemical characterization of nucleolar phosphoprotein C23 using ten monoclonal antibodies.

Extractable nucleolar proteins from HeLa cells were used as a source of antigen to immunize mice for monoclonal antibody (MAb) production. Ten of the resulting MAbs shown to identify nucleolar phosphoprotein (110 kD/pI 5.5) were purified and used in immunochemical studies to further characterize protein C23. All ten MAbs showed nucleolar localization by indirect immunofluorescence; one antibody (FR2) also showed some nucleoplasmic localization that was attributed to a shared epitope between protein C23 and a 72 kD nuclear/nucleolar antigen. Reciprocal antibody cross blocking studies indicated that the ten MAbs identified nine distinct epitopes on protein C23. Interestingly, seven of the nine epitopes were shown by immunofluorescence and competitive ELISA studies to be species related. Immunostained patterns of exponentially growing HeLa cells suggest that protein C23 exists in vivo solely as a 110 kD peptide. However, protein C23 was subject to rapid degradation into a number of proteolytic fragments upon extraction or storage of isolated nucleoli. The failure to find protein C23 related peptides with molecular sizes less than 110 kD in exponentially growing cells and the lack of cytoplasmic localization of any of the ten MAbs suggests that protein C23 is not a prepro-protein processed in vivo to form ribosomal proteins as previously suggested (1).

Animals↗
PubMed1985

Chloroquine and premature evacuation of uterine conceptus in rats.

Bilateral spaying on day 18 of pregnancy in rats made the refractory uteri highly reactive to a single injection of chloroquine (25 mg/kg). Complete evaluation of the uterine conceptus resulted by 24-48 hours following chloroquine administration. It was moreover observed that the amount of luteal progesterone which was found to be sufficient to maintain pregnancy until term, failed to reverse the abortifacient efficacy of chloroquine.

Animals↗
PubMed1985

Ultrastructure of cyclic changes in the murine uterus, cervix, and vagina.

The regional and cyclic changes in the murine genital epithelium were studied by transmission and scanning electron microscopy to provide a morphological standard to serve as a basis for investigation of host-parasite relationships in genital infections. Thus, we examined not only mucosal epithelial cell changes, but also surface mucus, normal flora and inflammatory cells. Ultrastructurally, at proestrus/estrus, we found uterine and most cervical epithelial cells covered with microvilli overlaid with mucus-like secretions and evidence of internal secretory activity. There was little normal flora anywhere in the tract. At early metestrus, we found squamous cervicovaginal epithelial cells with low discontinuous microrugae, extensive normal flora and many neutrophils beginning to migrate through the epithelium. The flora and neutrophils could explain the relative lack of susceptibility to infection at that time. At diestrus the appearance of a newly regenerated epithelium and lack of normal flora suggested that initiation of infection could occur at this stage; however, the presence of large numbers of neutrophils ready to phagocytize invading bacteria indicated a deterrent to infection. This study of cyclic changes in flora, mucus, neutrophils and epithelial cells provided ultrastructural evidence to support an earlier hypothesis that the greatest susceptibility to gonococcal infection in mice occurred at proestrus/estrus.

Animals↗
PubMed1985

Characterization of hydroxyl radical-induced damage after sparsely and densely ionizing irradiation.

The extent of hydroxyl radical mediated cell inactivation was measured for a variety of particle beams ranging from 8.5 Me V/u neon ions to 570 Me V/u argon ions. In general, the fraction of the total radiosensitivity caused by OH decreases from close to 60 per cent at low ionization density or low linear energy transfer (low LET) to close to 25 per cent at high LET for aerobically irradiated mammalian cells. The extent of OH induced cell lethality can be explained in terms of LET infinity only for low energy or low atomic number particles where fragmentations and complicated track structures do not contaminate the characteristic particle LET. For example, at a calculated LET infinity of 100 ke V/micron, the OH mediated fraction of the total radiation damage is about 25 per cent for low energy carbon but close to 40 per cent for high energy carbon ions. For low energy charged nuclei of approximately the same energy, as the 5.4-13.4 MeV/u He, Li, C and Ne ions in this report, there is a predictable diminution of the OH mediated effect with increasing LET infinity; however, the biological effect cannot be predicted accurately from calculated LET infinity values for high energy particle irradiation, nor indeed from a variety of low energy charged particles of quite different energies (incident velocities). This illustrates the unsuitability of using LET as a unifying parameter, except under specific circumstances. As more is learned about the energy deposition for energized charged particles in terms of track structure (core and penumbra), it may be possible to characterize the radiobiological data with a better physical parameter than LET infinity.

Animals↗
PubMed1985

A comparison of water equivalent thickness measurements: CT method vs. heavy ion beam technique.

The purpose of this study was to evaluate existing X-ray CT methods for determining water-equivalent path length from body surface to a tumour site. In the method, the CT numbers are used to obtain linear attenuation coefficients which provide a measure of the electron density. These numbers are averaged over the energy spectrum of the diagnostic X-ray beam and other parameters which have a dependence on energy. From range measurements with heavy charged particles, it is also possible to obtain an independent and direct measure of electron density along the beam path. In the results reported here, the beam path electron density or water-equivalent path length was measured with charged particle beams, using radiation sensitive diodes as target markers. To minimise error which would be introduced by motion of the target volume, a frozen dog cadaver was used. Comparison was made between the water-equivalent path length measured with high energy particle beams, and the water-equivalent path length estimated from an X-ray CT image of the same target volume by the methods presently used in charged particle therapy (Chen et al. 1979). There was good agreement between the values determined directly with neon or helium ion beams, but when these values were compared with estimated path lengths derived from X-ray CT data, it was observed that the CT range could be in error by as much as 11% for adverse conditions of marked inhomogeneity and the presence of high atomic number bone. Under the best conditions of moderate inhomogeneity and absence of bone, the derived CT range values agreed reasonably well with the direct measurements.

Animals↗
PubMed1985

Alkaptonuria.

Explore the source record for details and available documents.

Adult↗
PubMed1984

Inverse relationship between melanogenesis and endogenous hydroquinone.

Inhibition or stimulation of melanogenesis have been found to occur as a result of the alteration of hydroquinone levels in the body. Substances which stimulate melanogenesis are found to lower the level of hydroquinone in amphibia, and evidence for the relationship is also given by mammalian experiments.

Animals↗
PubMed1984

Comparative evaluation of contraceptive efficacy of norethisterone oenanthate (200 mg) injectable contraceptive given every two or three monthly. Indian Council of Medical Research Task Force on Hormonal Contraception.

A total of 2388 subjects, 1181 for 60 +/- 5-day and 1207 for 90 +/- 5-day treatment regimen with norethisterone oenanthate (NET OEN) 200 mg injection, were observed for 24 months, constituting 28,513 woman-months. This clinical trial represents the largest clinical trial undertaken on NET OEN. The observations indicated that NET OEN given at 60 +/- 5-day intervals provides adequate contraceptive protection. However, as compared to the published studies elsewhere, higher method failures were seen during the first six months of NET OEN usage, when all women were receiving the drug at 60 +/- 5-day intervals. The reasons for this discrepant observation in the present study cannot be explained. The higher method failures reported with 90 +/- 5-day regimen were mainly during the third month following the injection, suggesting reduced contraceptive efficacy of the drug during this period. Thin build women (body weight less than or equal to 40 kg) were at higher risk of involuntary pregnancy. Disrupted menstrual pattern was the major reason for discontinuation ranging between 42-43 per 100 users at the end of 24 months. Amongst these, amenorrhoea was the commonest reason for discontinuation. No change in blood pressure was observed during contraceptive usage. The majority of NET OEN users did not show any change in body weight. The overall continuation rates with NET OEN were lower than those observed in similar conditions with Cu-T 200 mm2 IUCD.

Adult↗
PubMed1984

Conformation and hydrogen bonding of N-formylmethionyl peptides. Parallel beta-sheet in the crystal structure of N-formyl-L-methionyl-L-valine.

Crystals of N-formyl-L-methionyl-L-valine (C11H20N2O)4S, M.W. = 276.3) are orthorhombic, space group )2(1)2(1)2(1) with cell constants at 294K of a = 4.851 (1), b = 14.925 (1), c = 19.745 (3) A, V = 1429.8 (1) A3, Z = 4 and observed (Dm) and calculated (Dx) of 1.49 and 1.488 g x cm-3, respectively. The crystal structure was solved using automatic diffractometer data (1260 reflections larger than or equal to 3 sigma) and refined to a final R-value of 0.035. This structure contains a short (2.626 (3) A) intermolecular hydrogen bond between the carboxyl OH and the N-acyl oxygen, a feature common to most N-acylamino acids and N-acylpeptides. The peptide is nearly planar (omega = 174.6 (5)); the values of psi 1, phi 2, psi 1T and psi 2T are, respectively, 131.8 (4) degrees, -139.9 (5) degrees, -39.3 (4) degrees and 142.1 (4) degrees. The methionine side chain is not zig-zag transplanar; the side chain torsion angles are: chi 1(1) = -60.0 (4) degrees, chi 2(1) = 176.0 (4) degrees and chi 3(1) = 71.8 (4) degrees. The two C gamma's for valine have psi 1-values of -64.4 (5) degrees and 173.7 (5) degrees. The formation of the parallel rather than antiparallel beta-sheet structure, the participation of the N-formyl group in the parallel beta-sheet and the use of C-H ... O hydrogen bonds to stabilize the beta-sheet are novel features found in this structure.

Chemotactic Factors↗
PubMed1983

Isolation of dermatophytes from rural and urban soil samples in premises of infected and non-infected animals.

Animal houses wherein animals infected with ringworm were detected were considered as premises of infected and infection free houses were considered as premises of the non-infected. Fifty soil samples from each of the premises in each of rural and urban areas were examined for the presence of dermatophytes. The premises of the infected showed higher Isolation Rate of dermatophytes. Of the four species of dermatophytes isolated, T. mentagrophytes (granular) was present in the soil of the infected premises only, while T. terrestre, M. nanum and M. gypseum were present in both the premises in both the rural and urban areas.

Animals↗
PubMed1982

Inhibition of ovulation by indomethacin in rats.

Indomethacin, a specific prostaglandin synthetase inhibitor, was found to block ovulation in rats when scheduled at 1200h on day 4 of the cycle. The same regimen was ineffective at 1800h, but its antiovulatory efficacy was estimated to be about 50% when given at 1600h. An injection of indomethacin given concurrently with prostaglandin F2a allowed ovulation in 80% of the test animals. None of the animals, irrespective of the drug schedule, became pregnant on mating with the fertile males but showed a remarkable decidual cell reaction (DCR) in response to unilateral uterine traumatization. The anti-ovulatory or intinidation effect of indomethacin is discussed.

Animals↗
PubMed1982

Blockade of ovulation by clomiphene citrate and its reversal by human chorionic gonadotropin or prostaglandin F2 alpha in rats.

Clomiphene citrate (clomid), a nonsteroidal estrogenic compound, was found to be effective in blocking ovulation in rats when scheduled at a dose of 3.0 mg/kg on day 2 or late day 4 of the estrus cycle. Treatment with hCG or prostaglandin F2 alpha (PGF2 alpha) concurrently with clomid consistently reversed the antiovulatory effect of clomid. The possible mode of action of clomid in the interruption of ovulation has been discussed.

Animals↗