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Biomedical subjects

A Chatterjee

Publications and source records attributed to A Chatterjee.

At least 271 records · Page 15Linked to original sources
PubMed1991

Measurements of nucleic bases released after gamma irradiation of DNA in solution in air.

The release of unaltered nucleic bases from gamma-irradiated DNA in a dilute buffered aqueous solution was studied in both salmon sperm and superhelical viral DNA. Analyses of freed bases were made by high-performance liquid chromatography. An elution protocol was developed for maximum separation of the four nucleic bases and nucleosides with a sensitivity of 10-20 pmol of nucleic base. It was found that: (i) both prompt and delayed release of bases postirradiation occur in both types of DNA; (ii) these yields (G-values) were measured to be 10-15 times higher for the salmon sperm DNA in comparison to the SV40 DNA; (iii) the A-T/G-C ratio in the DNA was not reflected in the ratios of the released base; and (iv) based on measurements made by us of DNA strand breaks in SV40 DNA (unpublished results), less than half of all breaks result in the release of an undamaged base.

Adenine↗
PubMed1990

Comparison of the immunological properties of mammalian (rodent), bird, fish, amphibian (toad), and invertebrate (crab) metallothioneins.

Immunoassays such as rocket immunoelectrophoresis, western dot blot hybridization, and competitive ELISA analysis were used to estimate and compare homology among fishes (several species), crab, toad, chicken and rodent metallothioneins. The relative abundance of tissue-specific metallothionein in catfish was highest in liver followed by kidney and pancreas like mammalian systems. Immunologically, considerable homology exists among fish metallothioneins, although the extent of homology differs to some extent. No homology was found between fish or chicken metallothioneins. The amphibian (toad) and invertebrate (crab) metallothioneins showed only partial homology with fish metallothioneins in antigenic determinants.

Amphibians↗
PubMed1990

The formation of strand breaks in DNA after high-LET irradiation: a comparison of data from in vitro and cellular systems.

This paper presents a summary of our understanding to date of the formation of DNA strand breaks induced by highly energetic particle beams (high-LET radiation). We have compared our own recent data on the formation of strand breaks induced in DNA in an aqueous solution with our previous data and those of others available from the literature for similar lesions made in cellular DNA. When the strand break induction frequency, as number of breaks per Gy per unit DNA, is plotted against LET, a series of biological effect curves (one for each particle atomic number Z) is obtained. The frequency of the formation of single-strand breaks has an RBE of less than 1 for DNA in solution and for DNA in the cell; the frequency of the formation of double-strand breaks (dsb) also has an RBE of less than 1 for DNA in a solution containing low amounts of free radical scavenger(s), while the RBE can be greater than 1 in the 50-200 keV/microns range for cellular DNA. RBE values are with respect to X-rays or cobalt gamma-rays. In cells the level of unrejoined strand breaks is also highest in the 50-200 keV/microns range and may reach 25-35% of the initial break yield depending on particle energy and Z-value. These irreparable lesions include double-strand scissions and some form(s) of single-strand breaks. The data presented cover results obtained for helium to uranium particles, with an LET range of 16 to 160,000 keV/microns. When different biological end-points are compared a strong correlation is found between induction of dsb, chromosomal abnormalities and mutation induction.

DNA↗
PubMed1990

Characterization of transposon insertion out- mutants of Erwinia carotovora subsp. carotovora defective in enzyme export and of a DNA segment that complements out mutations in E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Erwinia chrysanthemi.

Soft-rotting Erwinia spp. export degradative enzymes to the cell exterior (Out+), a process contributing to their ability to macerate plant tissues. Transposon (Tn5, Tn10, Tn10-lacZ) insertion Out- mutants were obtained in Erwinia carotovora subsp. carotovora 71 by using plasmid and bacteriophage lambda delivery systems. In these mutants, pectate lyases, polygalacturonase, and cellulase, which are normally excreted into the growth medium, accumulated in the periplasm. However, localization of the extracellular protease was not affected. The Out- mutants were impaired in their ability to macerate potato tuber tissue. Out+ clones were identified in a cosmid library of E. carotovora subsp. carotovora 71 by their ability to complement mutants. Localization of cyclic phosphodiesterase in the periplasm indicated that the Out+ plasmids did not cause lysis or a nonspecific protein release. The Out+ derivatives of the E. carotovora subsp. carotovora 71 mutants regained the ability to macerate potato tuber tissue. Our data indicate that a cluster of several genes is required for the Out+ phenotype. While one plasmid, pAKC260, restored the Out+ phenotype in each of the 31 mutants of E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Erwinia chrysanthemi, it failed to render Escherichia coli export proficient. Homologs of E. carotovora subsp. carotovora 71 out DNA were detected by Southern hybridizations in subspecies of E. carotovora under high-stringency conditions. In contrast, E. chrysanthemi sequences bearing homology to the E. carotovora subsp. carotovora 71 out DNA were detectable only under low-stringency hybridization. Thus, although the out genes are functional in these two soft-rotting bacterial groups, the genes appear to have diverged.

Biological Transport↗
PubMed1990

Effect of gamma-irradiation of Escherichia coli on cyclic AMP binding activity.

Cyclic AMP binding in the extract of E. coli was taken as a measure of cAMP receptor protein (CRP) present in the cells. The gamma-irradiation of cells caused a dose-dependent inhibition of cAMP binding activity indicating that CRP gene is affected by gamma-irradiation. The binding activity in cells irradiated with 240 Gy gamma-ray dose remained unaltered by post-irradiation incubation. This supports previous finding that the enhanced inhibition of the L-arabinose isomerase synthesizing capacity, following incubation of gamma-irradiated cells at higher doses, must be due to a different cause than the catabolite repression.

Cyclic AMP↗
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

The influence of radiation quality on the formation of DNA breaks.

We have aimed to present a comprehensive review of our understanding to date of the formation of DNA strand breaks induced by high LET radiation. We have discussed data obtained from DNA in solution as well as from the formation and "repair" of strand breaks in cell DNA. There is good agreement, qualitatively, between these two systems. Results were evaluated for two parameters: (1) effectivity per particle, the cross section (sigma) in micrometers 2/particle; and (2) the strand break induction frequency as number of breaks per Gy per unit DNA (bp or dalton). A series of biological effects curves (one for each Z-number) is obtained in effectivity versus LET plots. The relationships between induction frequencies of single-strand breaks, or double-strand breaks, or the residual "irrepairable" breaks and LET-values have been evaluated and discussed for a wide spectrum of heavy ions, both for DNA in solution and for DNA in the cell. For radiation induced total breaks in cell DNA, the RBE is less than one, while the RBE for the induction of DSBs can be greater than one in the 100-200 keV/micrometers range. The level of irrepairable strand breaks is highest in this same LET range and may reach 25 percent of the initial break yield. The data presented cover results obtained for helium to uranium particles, covering a particle incident energy range of about 2 to 900 MeV/u with a corresponding LET range of near 16 to 16000 keV/micrometers.

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↗