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Biomedical subjects

A Chatterjee

Publications and source records attributed to A Chatterjee.

At least 37 records · Page 2Linked to original sources
PubMed1990

Production of DNA strand breaks by direct effects of heavy charged particles.

A theoretical model has been developed to calculate the yields of single- and double-strand breaks in DNA induced by direct effects of ionizing radiation. In this model, which involves no fitted parameters, elements of track structure and stopping power theory are combined with a detailed geometrical description of DNA to calculate the energy deposited by fast charged particles to DNA molecules. The average energy per interaction with a DNA molecule is estimated to be 30 eV from the available data on oscillator strength measurements. These ideas have been incorporated in a Monte Carlo computer program using Poisson statistics to treat the stochastic nature of the energy deposition processes and thereby determine the excitation and ionization states of the molecule. Each ionization reaction on the DNA backbone is assumed to lead to a DNA strand break. In our model double-strand breaks result from nearby independent breaks on opposite strands. Our calculated single- and double-strand break yields compare well with measured cellular data under conditions such that direct effects are thought to dominate strand break production.

Argon↗
PubMed1989

Bay K8644 like activity of an antibody against a 60 kDa tubular membrane protein.

Partial purification of the dihydropyridine receptor from rat skeletal muscle demonstrated mainly a 60 kDa band in SDS-polyacrylamide gel. An antibody raised against that protein behaved as a calcium channel agonist viz. Bay K8644. The affinity purified antibody, when added to cultured heart cells, increased the beat rate 40-80% depending on the titer of the antiserum. The antibody also woke up the beats of the cells previously blocked with the channel antagonist, nifedipine. Immunoblot analysis indicated that the receptor of this antibody in heart cell membrane is also a 60 kDa protein.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1989

Isolation and characterization of complementary DNA to proliferating cell nucleolar antigen P40.

Proliferating cell nucleolar antigen P40 is a late G1-specific protein, which was found in a variety of human tumors (A. Chatterjee, J. W. Freeman, and H. Busch. Cancer Res., 47: 1123-1129, 1987). Two overlapping complementary DNA clones for antigen P40 were isolated by immunoscreening a lambda gt11 human expression library. The complete nucleotide sequence of the clones was determined. The complementary DNAs encode the Mr 30,000 portion of the COOH-terminal portion of the protein. The mRNA for P40 was 2.8 kilobases long and was expressed maximally in G1 cells in cell cycle. A series of deletion mutants of the expressed peptide was constructed and the deletion mutants were expressed in Escherichia coli. Using these mutants, the epitope region of P40 recognized by a P40-specific monoclonal antibody was identified. The hydropathy plot based on the protein sequence revealed that this region of the protein is largely hydrophilic. This protein is unique and differs in sequence from other proliferating cell nuclear/nucleolar antigen proteins of similar molecular weight such as protein B23 and cyclin.

Antibodies, Monoclonal↗
PubMed1989

Linked scans of peptides and protein digests: amino acid sequence determination of components of complex mixtures.

Two-sector linked-scan analysis of an unpurified proteolytic digest of a pyruvate decarboxylase enzyme (60,000 Da) has allowed the discovery and assignment of an amino-terminal post-translational modification and processing event. A difference in amino acid sequence from that predicted by a recently published nucleotide sequence has also been found. These results illustrate both the use and considerable potential of linked-scan methods for the analysis of complex biopolymer mixtures.

Amino Acid Sequence↗
PubMed1989

Potentiation of bleomycin-induced chromosome aberrations by the radioprotector reduced glutathione.

In this study we investigated whether the radioprotector reduced glutathione (GSH) can reduce the frequency of chromosome aberrations induced by the radiomimetic antitumour drug bleomycin (BLM) in muntjac lymphocytes in vitro. Our results demonstrate that, instead of yielding any protection, the presence of GSH potentiates the clastogenic action of BLM. A significant enhancement in the frequency of rearrangements and deletions was observed and the number of aberrations per metaphase was also enhanced. We suggest that this potentiation may be due to GSH acting as a reducing agent in reactivating oxidised BLM.

Animals↗
PubMed1989

Identification of a novel 80 kDa antigen associated with cell proliferation.

Exploiting the immunomasking method, a polyclonal antibody has been developed in mice for identification of a novel 80 kDa antigen (P80) in KB cells. The P80 was not detected in normal resting cells but was present in appreciable amount in malignant cells. In a comparative Western transfer the antisera to the immune complexes identified a 80 kDa peptide absent in normal cell extracts. When growth of KB cells were arrested by 48 h of serum starvation the P80 was not detected but after refeeding with serum containing medium, the P80 reappeared within 1 h. This result indicates that the P80 is associated with cell proliferation and appears early in the GI-S phase of the cell cycle.

Antigen-Antibody Complex↗
PubMed1989

Antifertility effect of Piper betle Linn. extract on ovary and testis of albino rats.

Chronic administration (sc) of the extract of the stalk of P. betle at 30 mg/kg body weight daily for 21 days produced significant decrease in oestrogen and androgen dependent target organ weights along with increase in cholesterol in adrenal, ovary and testis. Acid and alkaline phosphatase activities in serum, liver and kidney did not exhibit any toxic effect. There was marked change in morphology of testis and ovary. Vaginal smear showed prolonged dioestrus in treated female. The treated male showed decreased number and motility of sperm. Both male and female remained infertile after treatment suggesting antifertility activity of the extract on both sexes of albino rats.

Animals↗
PubMed1989

Critical evaluation of conventional abdominal closure with single-layer closure in adult and elderly.

Two different techniques of abdominal closure, conventional and single-layer, were studied on comparative basis in 55 cases each. Single-layer closure was found to have definite advantage over conventional closure as regards operating or healing time, feasibility, ease and postoperative morbidity. Single-layer closure took 8-10 minutes in comparison to 18-20 minutes required by conventional method. Incidence of burst abdomen was found to be 3.6% in the former and 7.27% in the latter. In only one case of conventional closure incisional hernia occurred whereas none occurred in case of single-layer closure. Moreover complications of scar and delayed healing were less in single-layer closure.

Abdomen↗
PubMed1988

Characterization of a nuclear antigen (Mr 150,000) associated with cell proliferation.

In the course of development of a "library" of monoclonal antibodies to nucleolar proteins, a monoclonal antibody to a nuclear antigen with a molecular weight of 150,000 was obtained. Using this monoclonal antibody as an immunocytochemical probe, low immunofluorescence was demonstrated in human peripheral blood lymphocytes or HL-60 cells treated with retinoic acid. In contrast, a high degree of immunofluorescence was detected in rapidly proliferating human cells (HeLa, Hep-2, HL-60), in Novikoff hepatoma cells, and in phytohemagglutinin-activated human blood lymphocytes. Immunodot blot analysis indicated there were low levels of Mr 150,000 protein in quiescent lymphocytes and increasing amounts after stimulation with phytohemagglutinin. The increased level of Mr 150,000 protein thus is associated with cell proliferation.

Animals↗
PubMed1988

A comparison of aberration distribution and cell-cycle progression in cells treated with bleomycin with those exposed to X-rays.

The extent of cell-cycle delay and the frequency of aberrant metaphases induced by bleomycin (BLM) and X-rays have been compared at doses which produce similar frequencies of chromosome aberrations by the 2 clastogenic agents (BLM, 40 micrograms/ml and X-rays, 2 Gy) in muntjac lymphocytes. The frequency of aberrant metaphases was low in BLM-treated cells; however, the number of aberrations per metaphase was higher than in cells exposed to X-rays. Thus in contrast to their uniform sensitivity to X-rays, the lymphocytes showed differential sensitivity to BLM. This might be due to differences among the cells in their uptake of BLM and/or its action on the nuclear membrane-DNA complex. In spite of the total number of chromosome aberrations being similar to that induced by X-rays, BLM did not induce a significant delay in cell-cycle progression as observed in the case of X-rays. A possible explanation could be that the DNA damages being limited to fewer cells than in the case of X-irradiation, the BLM-treated cultures had more normal cells allowing faster progression and/or unlike X-rays BLM may not be causing other cellular damages in addition to DNA breaks.

Animals↗
PubMed1988

In vivo adenylate cyclase activity in ultraviolet- and gamma-irradiated Escherichia coli.

The incorporation of [14C]adenine into the cyclic AMP fraction by whole cells of Escherichia coli B/r was taken as a measure of the in vivo adenylate cyclase activity. This activity was significantly inhibited by irradiation of the cells either with 60Co gamma-rays or with UV light from a germicidal lamp, suggesting inhibition of cyclic AMP synthesis. The incubation of cells after irradiation with lower doses (50-100 Gy) of gamma-rays produced a significant increase of in vivo adenylate cyclase activity, whereas there was no significant change after higher doses (150 Gy and above). Dark incubation of cells after irradiation with UV light (54 J m-2) led to recovery of enzyme activity to the level measured in unirradiated cells. Thus it appears that the catabolite repression of L-arabinose isomerase induced by UV light, as well as gamma-irradiation, is due to reduced cyclic AMP synthesis in irradiated cells.

Adenylyl Cyclases↗
PubMed1987

Identification and partial characterization of a Mr 105,000 nucleolar antigen associated with cell proliferation.

This study reports the identification and partial characterization of a novel Mr 105,000 nucleolar antigen (P105) identified by a monoclonal antibody. This monoclonal antibody was obtained when a nucleolar protein extract separated from the immunodominant protein C23 was used as the immunogen. Nucleolar antigen P105 was not detected in normal (resting) human liver, kidney, or peripheral blood lymphocytes but was present in a variety of human malignant cells and tissues. Lymphocyte nucleoli also exhibited specific P105 staining after 72 h of phytohemagglutinin stimulation. Nucleolar antigen P105 was detected in growing and dividing HL 60 cells but was not detected in retinoic acid-induced differentiated HL 60 cells. When HeLa cells were made quiescent by 48 h of serum starvation, the P105 antigen was not detected, but after refeeding with serum-containing medium, the antigen P105 was detected in the HeLa nucleoli within 2 h. These results indicate that nucleolar antigen P105 is a proliferating cell nuclear and nucleolar antigen-like molecule which appears early in the G1-S phase of the cell cycle.

Animals↗
PubMed1987

Identification and partial characterization of a Mr 40,000 nucleolar antigen associated with cell proliferation.

The present study reports the identification and partial characterization of a novel Mr 40,000 nucleolar antigen (P40) by monoclonal antibodies. Monoclonal antibodies to this protein were obtained when a nucleolar protein extract separated from the immunodominant protein C23 was used to immunize BALB/c mice; 12 hybridoma clones produced antibodies to this protein. P40 was not detected in normal human kidney, liver, and leukocytes but was readily demonstrable in a variety of human malignant tissues. This newly identified P40 antigen differs in its specific nucleolar localization from cyclin (proliferating cell nuclear antigen), a Mr 35,000 antigen which is largely in the nucleoplasm. In addition, cyclin appears in the nucleolus in S-phase; P40 appears in the nucleolus 6 h after refeeding serum-starved HeLa cells.

Animals↗
PubMed1987

Purification and immunological characterization of catfish (Heteropneustes fossilis) metallothionein.

Catfish hepatic metallothionein was purified to homogeneity by Sephadex G-75 gel filtration, DEAE-Sephadex A-25 column chromatography and preparative polyacrylamide gel electrophoresis. Induction by cadmium and zinc, characteristic UV spectrum, cadmium binding property and its low MW established that it was a metallothionein. Antibody was raised in rabbit against catfish metallothionein. Catfish antimetallothionein cross-reacted with other fish metallothioneins but not with chicken or rodent metallothionein. Catfish metallothionein is more electronegative as compared to mouse, rat, chicken or hamster metallothionein. Catfish MT appeared to aggregate readily on storage and to be less electronegative.

Animals↗
PubMed1987

Novel nucleolar antigens in autoimmune disease.

Antinucleolar antibodies are of interest in 2 important areas, namely, autoimmune diseases and specific products involved in the "mitogenic cascade." The former have delineated a series of novel nuclear and nucleolar elements including the recently described proliferating cell nuclear antigens (PCNA), some of which are present in the nucleolus only at specific times in the G1-S phase of the cell cycle. Important new proteins such as "fibrillarin" (34 kD/pI 8.5) and a 125 kD nucleotide containing protein have been identified with antinucleolar antibodies. Protein p145 is a nucleolar PCNA that is present in growing and dividing cells but not in normal resting tissues. Antinucleolar antibodies offer powerful tools, not only for identification of specific nucleolar proteins important in the cell cycle, but also for purification of their genes and analysis of mechanisms of gene control that operate the "time windows" of the cell cycle.

Amino Acid Sequence↗