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Biomedical subjects

S Chakraborty

Publications and source records attributed to S Chakraborty.

At least 73 records · Page 4Linked to original sources
PubMed2000

Neovascularisation offers a new perspective to glutamine related therapy.

Angiogenesis or the generation of new blood vessel, is an important factor in the growth of a solid tumor. Hence, it becomes a necessary parameter of any kind of therapeutic study. Glutamine is an essential nutrient of tumor tissue and glutamine related therapy involves clearance of circulatory glutamine by glutaminase. Therefore, using different murine solid tumor models, the present study was undertaken to find out whether the S-180 cell glutaminase has any effect on angiogenesis of solid tumor, or not. Result indicates that the purified S-180 cell glutaminase reduces tumor volume and restrict the generation of neo blood vessels. Therefore, it can be concluded that this enzyme may be an effective device against the cancer metastasis.

Angiogenesis Inhibitors↗
PubMed1999

Comparative analysis of cytotoxin, hemolysin, hemagglutinin and exocellular enzymes among clinical and environmental isolates of vibrio cholerae O139 and non-O1, non-O139.

The presence of three major virulence genes toxR, tcpA and ctxA as well as expression of several putative virulence factors were compared in 12 Vibrio cholerae O139 and non-O1,non-O139 strains of clinical and environmental origin. All the strains possessed the gene encoding the regulatory protein TOXR. None of the non-O1, non-O139 strains as well as one of the O139 environmental strains carried the genes for ctxA and tcpA. Statistically significant differences in hemagglutinin and hemolysin production were observed amongst the strains depending on the source of their isolation. Expression of extracellular enzymes such as protease, elastase, neuraminidase, phospholipase A and phospholipase C, however, did not vary significantly from the groups of strains isolated from different sources.

Animals↗
PubMed1999

Nucleotide-dependent bisANS binding to tubulin.

Non-covalent hydrophobic probes such as 5, 5'-bis(8-anilino-1-naphthalenesulfonate) (bisANS) have become increasingly popular to gain information about protein structure and conformation. However, there are limitations as bisANS binds non-specifically at multiple sites of many proteins. Successful use of this probe depends upon the development of binding conditions where only specific dye-protein interaction will occur. In this report, we have shown that the binding of bisANS to tubulin occurs instantaneously, specifically at one high affinity site when 1 mM guanosine 5'-triphosphate (GTP) is included in the reaction medium. Substantial portions of protein secondary structure and colchicine binding activity of tubulin are lost upon bisANS binding in absence of GTP. BisANS binding increases with time and occurs at multiple sites in the absence of GTP. Like GTP, other analogs, guanosine 5'-diphosphate, guanosine 5'-monophosphate and adenosine 5'-triphosphate, also displace bisANS from the lower affinity sites of tubulin. We believe that these multiple binding sites are generated due to the bisANS-induced structural changes on tubulin and the presence of GTP and other nucleotides protect those structural changes.

Anilino Naphthalenesulfonates↗
PubMed1999

Enhancement of cation diffusion rates across the 410-kilometer discontinuity in Earth's mantle

Rates of cation diffusion (magnesium, iron, and nickel) have been determined in olivine and its high-pressure polymorph, wadsleyite, at 9 to 15 gigapascals and 1100 degrees to 1400 degreesC for compositions that are relevant to Earth's mantle. Diffusion in olivine becomes strongly dependent on composition at high pressure. In wadsleyite, diffusion is one to two orders of magnitude faster than in olivine, depending on temperature. Homogenization of mantle heterogeneities (chemical mixing) and mineral transformations involving a magnesium-iron exchange will therefore occur considerably faster in the transition zone than at depths of less than 410 kilometers.

Journal Article↗
PubMed1999

Yield, biological activity, and field performance of a wild-type Helicoverpa nucleopolyhedrovirus produced in H. zea cell cultures.

This paper reports studies of the in vitro production of a virus from Helicoverpa armigera (HaSNPV) and its possible use as a specific Helicoverpa/Heliothis larvicide. Growth kinetics of Helicoverpa zea (H. zea) cells and virus occlusion body yields were compared in three SF900II-based media, namely, SF900II (serum-free), SF900II + 1% serum, or SF900II + 10% serum. Viable cell densities were usually higher in the media supplemented with serum than in the serum-free medium; however, in the serum-free medium, cell diameters were 1.7 times greater (i.e., individual cell volumes were five times larger). Both volumetric production of virus occlusion bodies and production per cell were higher in the serum-free medium than in the media supplemented with serum. However, the infectivity of the occlusion bodies from the serum-free medium was less than that with those from the medium supplemented with 10% serum, when compared in bioassays employing newly hatched larvae. The infectivity of the in vitro produced occlusion bodies was also less than that of in vivo produced occlusion bodies in a commercially available virus product, GemStar. High levels of infection of H. armigera larvae obtained in a preliminary field assessment on preflowering tomatoes using the in vitro produced occlusion bodies indicated the suitability of the in vitro process for biopesticide production.

Animals↗
PubMed1999

Serial passage of a Helicoverpa armigera nucleopolyhedrovirus in Helicoverpa zea cell cultures.

The serial passaging of baculoviruses in cell lines numerous times can result in a variety of mutations or defective viral populations becoming predominant in the cultures. The generation of these mutants during cell culture passage, also known as "the passage effect," can seriously hinder the use of in vitro methods for large-scale production of baculoviruses for use as biopesticides. In an effort to develop a large-scale in vitro method of producing Helicoverpa armigera singly enveloped nucleopolyhedrovirus (HaSNPV), it was essential to determine whether or not the passage effect was evident when this virus is serially passaged in cell cultures. An isolate of HaSNPV was serially passaged in Helicoverpa zea cell cultures up to 10 times. The production of occlusion bodies decreased with increasing passage number and there was evidence of defective viruses becoming predominant in cultures after 5 passages. The number of virions present within cross sections of passage 3 occlusion bodies was 1.5 times higher than those from passage 10 occlusion bodies when quantified using electron microscopy. A laboratory bioassay showed that potencies of passage 3 isolates against H. armigera larvae were 8 times higher than potencies of passage 10 isolates. This study indicated that changes typical of the passage effect were evident when HaSNPV was serially passaged in H. zea cell cultures up to 10 times.

Animals↗
PubMed1999

Angiogenesis a putative new approach in glutamine related therapy.

Angiogenesis or the generation of new blood vessels, is an important factor regarding the growth of a tumor. Hence, it becomes a necessary parameter of any kind in therapeutic studies. Glutamine is an essential nutrient of tumor tissue and glutamine related therapy involves clearance of circulatory glutamine by glutaminase. So, whether this enzyme has any effect on angiogenesis of a tumor or not becomes an obvious question. To address this question, this study has been carried out with different murine tumor models. The results indicate that purified glutaminase reduces tumor volume as well as restricts the generation of new blood vessels. Glutaminase is effective in the case of solid as well as ascites tumor models. In the case of induced cancer, the host exhibits delayed onset of neoplasia following enzyme treatment and tumor host interactions determine the intensity of the neovascularisation process. Therefore, it can be concluded that this enzyme might be an effective agent against cancer metastasis.

Animals↗
PubMed1999

Postatrophic hyperplasia of the prostate: lack of association with prostate cancer.

Postatrophic hyperplasia (PAH) of the prostate is a non-neoplastic glandular alteration sometimes confused with prostate carcinoma (PCa) histologically. Although atrophy had long been considered a possible precursor lesion for PCa, a theory that has been largely dismissed, the topographical relationship of PAH to PCa has not been studied systematically. Whole mount sections from 272 randomly selected radical prostatectomy (RP) specimens (T1c, 2, 3, N0, 1) and 44 cystoprostatectomy (CP) specimens (28 with incidental PCa) were assessed for the presence, location, and number of foci of PAH, and then were correlated with the presence and location of PCa foci. PAH was identified in 86 (32%) RP and in 12 (27%) CP specimens. The distribution of PAH foci: peripheral zone (91%), transition zone (8%) and central zone (1%), and apex (49%), mid (39%), and base (12%). For RP specimens, 183 foci of PAH showed no atrophy in a mirror image area of the prostate opposite the focus of PAH. Of the foci, 33% showed PCa either within or within 2 millimeters of the focus of PAH. For the mirror image area without PAH, PCa was identified either within or within 2 millimeters of the area in 40% (p = 0.19). The frequency of PAH in CP specimens and its relationship to incidental PCa was not significantly different from that of RP specimens (p = 0.60, chi square). Therefore, PAH is a relatively common lesion, most often seen in the peripheral zone of the apical third of the gland. PAH does not appear to have any association with PCa.

Adenocarcinoma↗
PubMed1999

Phylogenetic relationships among members of the Comamonadaceae, and description of Delftia acidovorans (den Dooren de Jong 1926 and Tamaoka et al. 1987) gen. nov., comb. nov.

The phylogenetic relationships among members of the family Comamonadaceae and several unclassified strains were studied by direct sequencing of their PCR-amplified 16S rRNA genes. Based on the 16S rRNA gene sequence analysis, members of the family formed a coherent group. The closest relatives are species of the Rubrivivax sub-group: Leptothrix discophora, Ideonella dechloratans and Rubrivivax gelatinosus. The genus Hydrogenophaga formed two subclusters, as did the species of Acidovorax, whereas the five species of the genus [Aquaspirillum] were polyphyletic. Comamonas acidovorans was phylogenetically distant from the type species of Comamonas, Comamonas terrigena. On the basis of this work and previous studies, Comamonas acidovorans is removed from the genus Comamonas and renamed as Delftia acidovorans gen. nov., comb. nov. Descriptions of the new genus Delftia and of the type species Delftia acidovorans, for which the type strain is ATCC 15668T, are presented.

DNA, Bacterial↗
PubMed1999

Climate change and plant disease management.

▪ Abstract Research on impacts of climate change on plant diseases has been limited, with most work concentrating on the effects of a single atmospheric constituent or meteorological variable on the host, pathogen, or the interaction of the two under controlled conditions. Results indicate that climate change could alter stages and rates of development of the pathogen, modify host resistance, and result in changes in the physiology of host-pathogen interactions. The most likely consequences are shifts in the geographical distribution of host and pathogen and altered crop losses, caused in part by changes in the efficacy of control strategies. Recent developments in experimental and modeling techniques offer considerable promise for developing an improved capability for climate change impact assessment and mitigation. Compared with major technological, environmental, and socioeconomic changes affecting agricultural production during the next century, climate change may be less important; it will, however, add another layer of complexity and uncertainty onto a system that is already exceedingly difficult to manage on a sustainable basis. Intensified research on climate change-related issues could result in improved understanding and management of plant diseases in the face of current and future climate extremes.

climate variability↗
PubMed1999

Embolization of iatrogenic venous pseudoaneurysm.

A case is described where a patient on long-term anticoagulation developed a venous pseudoaneurysm in the antecubital fossa following venepuncture. This venous pseudoaneurysm was successfully treated with coil embolization.

Aneurysm, False↗
PubMed1999

Isolation and purification of phosphate dependent glutaminase from sarcoma-180 tumor and its antineoplastic effects on murine model system.

High rate of glutamine use is a characteristic of tumor cell both in vivo and in vitro and experimental cancer therapies have developed by depriving tumor cells of glutamine. In several investigations, bacterial glutaminase was found to be a potent therapeutic agent against varieties of tumor, but it showed suppressive effects on haematopoietic systems and inhibitory effects on normal lymphocytic blastogenesis. No antineoplastic study has nevertheless been undertaken with glutaminase enzyme purified from mammalian source. In the present study we report the purification of glutaminase enzyme from mitochondria of highly malignant S-180 cell using ion exchange chromatography and affinity column chromatography of glutamine. Purified enzyme is a kidney type phosphate dependent glutaminase with Mr 64 KD. Effect of enzyme therapy has been investigated in transplantable as well as induced tumor model in both ascites and solid form. It has been observed that the enzyme at the total dose of 10 unit/mouse successfully inhibited the tumor burden both in ascitic and solid tumor and subsequently increases the host's life span. There was no significant toxic effect on the peripheral blood cells.

Animals↗
PubMed1998

A receptor for the lipocalin placental protein 14 on human monocytes.

Human placental protein 14 (PP14), a member of the lipocalin structural superfamily, is an abundant amniotic fluid glycoprotein with documented immunoinhibitory activities. While receptors have been characterized for several other lipocalins, none have been reported to date for PP14. In the present study, two-color immunofluorescence and flow cytometry was used to screen peripheral blood mononuclear cell subpopulations for their capacity to engage fluoresceinated recombinant PP14. The tagged PP14 bound strongly in a specific and saturable fashion to CD14+ (monocyte lineage) cells, but not to CD20+ (B cell lineage) or CD3+ (T cell lineage) cells. This binding was both pH- and temperature-sensitive, and was reduced by proteolytic pre-digestion of the cells with trypsin or proteinase K. Scatchard analysis demonstrated a single class of receptors on CD14+ cells, with a K(D) of approximately 1 x 10(-8) and approximately 10-35,000 receptors per cell. These findings constitute the first report of a cell surface-associated binding protein for PP14 and set the stage for exploring the molecular mechanisms of PP14-mediated signaling and immunomodulation.

Antigens, CD↗
PubMed1998

Control of mouse hepatocyte proliferation and ploidy by p53 and p53ser246 mutation in vivo.

The effect of expression of the p53 gene, in the presence or absence of the p53ser246 mutation (p53*), on ploidization (image cytometry), proliferation (expression of proliferating cell nuclear antigen and radioactive thymidine histoautoradiography), and apoptosis (in situ detection of DNA fragments) is determined in hepatocytes of p53-null and p53*-transgenic mice. The mouse p53ser246 mutation is equivalent to the p53ser249 mutation found in human hepatomas associated with hepatitis B virus infection and aflatoxin exposure. The hepatocytes of heterozygous or homozygous p53-knockout mice (p53+/-; p53-/-), as well as knockout mice expressing one allele of p53ser246 (p53+/-, p53*; p53-/-, p53*), do not undergo normal polyploidization with aging and show an increase in the number of cycling (G1-, S-, and M-phase) cells. In addition, p53ser246-transgenic mice (p53+/+, p53*; p53+/-, p53*; and p53-/-, p53*) have a greatly increased number of hepatocytes in the G1 phase. No differences in rates of apoptotic hepatocytes are found among any of the mouse groups studied, so the increased proliferation results in a hyperplasia manifested by a increased number of small periportal cells. We conclude that loss of p53 removes blocks in the cell cycle, leading to increased proliferation, whereas expression of the p53ser246 mutation stimulates G0 to G1 and/or M to G1 transition of hepatocytes. Increased proliferation of hepatocytes, combined with no concomitant increase in apoptosis, may in part explain the enhanced development of hepatocellular carcinomas in p53-knockout and p53*-transgenic mice exposed to aflatoxin.

Amino Acid Sequence↗
PubMed1998

Visually evoked cortical potentials in awake cats during saccadic eye movements.

Visually evoked potentials (VEPs) measured under conditions of retinal image stabilization that minimized the influences of visual masking and smearing were averaged from electroencephalographic records measured from striate cortex of three cats. The amplitudes of the VEPs increased around saccade initiation. The grating-evoked potentials obtained at different times relative to the saccade exhibited changes in waveform shape that could be attributed to a saccade-evoked potential. The changes in the shape of the waveform were reasonably accounted for by the summation of the grating-evoked potential (produced when the cat did not make a saccade) and an appropriately timed saccade-evoked potential. The fundamental amplitudes of the residual potentials were computed and found to vary across the time course of the saccade. These observations suggest that there are other influences besides visual masking that are exerted early in the visual pathway to modulate visual processing during saccadic eye movements. A corollary discharge process is the most likely candidate to exert these influences.

Animals↗
PubMed1998

Patterns of high-grade prostatic intraepithelial neoplasia associated with clinically aggressive prostate cancer.

High-grade prostatic intraepithelial neoplasia (PIN) is the only widely accepted precursor lesion for prostatic adenocarcinoma (PCa). However, the spread of established PCa within prostatic ducts may be indistinguishable morphologically from high-grade PIN. By convention, all cytologically malignant cellular proliferations within prostatic ducts have been lumped into a PIN category, although there have been recent attempts by McNeal to develop reproducible criteria to separate high-grade PIN from the spread of established PCa within prostatic ducts--intraductal carcinoma (IDCa). Using McNeal's criteria for IDCa, we studied whole-mount sections from 252 patients with pT3NO PCa for the presence of IDCa and correlated the presence or absence of IDCa with Gleason score, total tumor volume, surgical margin status, seminal vesicle involvement, and disease progression. Patients with IDCa had higher Gleason score and total tumor volume and were more likely to show seminal vesicle involvement and disease progression than those patients without IDCa. In addition, IDCa was of independent prognostic significance. Total tumor volume and surgical margin status had no independent prognostic significance in this data set.

Adenocarcinoma↗
PubMed1998

The significance of intraluminal prostatic crystalloids in benign needle biopsies.

Intraluminal prostatic crystalloids (IPC) are more common in prostate cancer acini than in benign acini. This study was undertaken to evaluate the hypothesis that crystalloids seen in a benign biopsy may indicate an increased risk of a concomitant prostatic carcinoma. A total of 600 patients underwent more than one prostate biopsy. For 394 patients the results of the biopsy were either negative or positive for prostate cancer. After exclusion of patients whose biopsy results were considered negative but coded as high-grade prostatic intraepithelial neoplasia or were suspicious for cancer or whose slides were unavailable for review, 331 patients remained. Biopsy results for these patients were evaluated for the presence of IPC. Also, 18 completely-embedded benign prostates from cystoprostatectomy specimens from patients with bladder cancer were evaluated for the presence of IPC. Seven hundred twenty-five biopsy specimens were reviewed; 51 (7%) contained crystalloids. Thirty-two of 634 (5%) benign biopsy specimens and 19 of 91 (21%) prostatic carcinoma biopsy specimens contained crystalloids. Sixteen of 331 patients (5%) had crystalloids in the initial benign biopsy specimen; 6 patients subsequently were determined to have carcinoma (38%), and 10 continued to have negative results (62%). Three hundred fifteen initial benign biopsies did not show crystalloids; 83 (26%) patients were subsequently diagnosed as having prostatic carcinoma (p = 0.238, Fisher's Exact Test, chi-square test). The IPC were found in 5 of 18 cystoprostatectomy prostates (28%). In this study, the presence of IPC on the initial biopsy specimens was not a significant risk factor for a subsequent diagnosis of prostate cancer. The IPC were not uncommon in prostates without cancer.

Adenocarcinoma↗