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Biomedical subjects

N Bhattacharyya

Publications and source records attributed to N Bhattacharyya.

At least 55 records · Page 3Linked to original sources
PubMed1998

Characterization of cell-associated and soluble forms of connective tissue growth factor (CTGF) produced by fibroblast cells in vitro.

Connective tissue growth factor (CTGF) is a mitogenic and chemotactic factor for cultured fibroblasts that has been implicated in wound healing, fibrotic disorders and uterine function. Although the primary translational products of the mouse, human and pig CTGF (mCTGF, hCTGF, pCTGF) genes are predicted to be secreted and of approximate M(r) 38,000, 10 kDa biologically active forms of pCTGF have recently been described. In this report, we show that human foreskin fibroblasts (HFFs) and mouse connective tissue fibroblasts contained 2.4 kb CTGF transcripts, stained positively with an anti-CTGF[81-94] peptide antiserum, and produced a 38 kDa protein that was immunoprecipitated by an anti-CTGF[247-260] peptide antiserum. While 38 kDa CTGF was readily detected in cell lysates, it was non- or barely detectable in conditioned medium. 38 kDa CTGF remained cell-associated for at least 5 days after synthesis and was not releasable by treatment of the cells with trypsin, heparin, 1 M NaCl or low pH. Purification of CTGF from human or mouse fibroblast conditioned medium resulted in the isolation of 10-12 kDa CTGF proteins that were heparin-binding, bioactive, and reactive with anti-CTGF[247-260] on Western blots. Whereas 10 kDa CTGF stimulated DNA synthesis in 3T3 cells to the same extent as platelet-derived growth factor (PDGF)-AA, -AB, or -BB, it did not compete with 125I-PDGF-BB for binding to alpha alpha, alpha beta or beta beta PDGF receptors (PDGF-R), did not stimulate tyrosine phosphorylation of PDGF-alpha-R or -beta-R, and was not antagonized by a neutralizing PDGF-R-alpha antiserum. These data show that, in cultured fibroblasts, 38 kDa CTGF is principally cell-associated whereas low mass forms of CTGF are soluble and biologically active. They further demonstrate that, contrary to the previously proposed properties of 38 kDa CTGF, 10 kDa CTGF does not bind to PDGF-R and stimulates Balb/c 3T3 cell mitosis via a PDGF-R-independent mechanism.

3T3 Cells↗
PubMed1997

A histone deacetylase inhibitor potentiates retinoid receptor action in embryonal carcinoma cells.

Histone acetylation is thought to have a role in transcription. To gain insight into the role of histone acetylation in retinoid-dependent transcription, we studied the effects of trichostatin A (TSA), a specific inhibitor of histone deacetylase, on P19 embryonal carcinoma cells. We show that coaddition of TSA and retinoic acid (RA) markedly enhances neuronal differentiation in these cells, although TSA alone does not induce differentiation but causes extensive apoptosis. Consistent with the cooperative effect of TSA and RA, coaddition of the two agents synergistically enhanced transcription from stably integrated RA-responsive promoters. The transcriptional synergy by TSA and RA required the RA-responsive element and a functional retinoid X receptor (RXR)/retinoic acid receptor (RAR) heterodimer, both obligatory for RA-dependent transcription. Furthermore, TSA led to promoter activation by an RXR-selective ligand that was otherwise inactive in transcription. In addition, TSA enhanced transcription from a minimum basal promoter, independently of the RA-responsive element. Finally, we show that TSA alone or in combination with RA increases in vivo endonuclease sensitivity within the RA-responsive promoter, suggesting that TSA treatment might alter a local chromatin environment to enhance RXR/RAR heterodimer action. Thus, these results indicate that histone acetylation influences activity of the heterodimer, which is in line with the observed interaction between the RXR/RAR heterodimer and a histone acetylase presented elsewhere.

Animals↗
PubMed1997

A variant of DNA polymerase beta acts as a dominant negative mutant.

In eukaryotic cells, DNA polymerase beta (polbeta) carries out base-excision repair (BER) required for DNA maintenance, replication, recombination, and drug resistance. A specific deletion in one allele in the coding sequence of the polbeta gene occurs in colorectal and breast carcinomas. The 87-bp deleted region encodes amino acid residues 208-236 in the catalytic domain of the enzyme. Here, we report evidence for expression of the wild-type (WT) and the truncated polbeta proteins in colorectal tumors. To elucidate the potential functional consequences of polbeta truncation, stable HeLa cell lines were established from cloned WT and variant polbetaDelta208-236. Cells expressing the variant protein exhibited substantially decreased BER activity. To test our hypothesis that truncated polbeta may disrupt the function of the WT enzyme, we stably transfected mouse embryonic fibroblast 16.3 cells with polbetaDelta208-236 cDNA. Reverse transcription-PCR and Western blot analyses showed that the new cell line, 16.3DeltaP, expresses the WT and the truncated polbeta mRNA and proteins. BER and binding activities were undetectable in these cells. Furthermore, in vivo the 16.3DeltaP cells were more sensitive to N-methyl-N'-nitro-N-nitrosoguanidine than the 16.3 cells. On adding increasing amounts of 16.3DeltaP protein extracts, the BER and DNA binding activities of extracts of the parent 16.3 cell line progressively declined. These results strongly suggest that truncated polbeta acts as a dominant negative mutant. The defective polbeta may facilitate accumulation of mutations, leading to the expression of a mutator phenotype in tumor cells.

Blotting, Western↗
PubMed1997

Early emergence of photoreceptor mosaicism in the primate retina revealed by a novel cone-specific monoclonal antibody.

We have examined the emergence of the photoreceptor mosaic in fetal macaque monkeys by using a novel monoclonal antibody, 7G6, that recognizes all cones in the adult primate retina. In the fetal retina, however, between embryonic (E) day 80 and E130, some opsin-positive cones were not labeled by 7G6. Double-labeling experiments revealed that though long and middle wavelength-sensitive fetal cones are 7G6-positive, a subset of short wavelength-sensitive cones are delayed in their acquisition of 7G6 immunoreactivity. Heterogeneity in cone labeling with 7G6 was evident at all fetal ages. The onset of 7G6 immunoreactivity, surprisingly, precedes both the expression of the cone opsins and the formation of synaptic contacts in the outer plexiform layer. Specifically, a population of cones was labeled in the periphery of the E65 retina, concomitant with ongoing cone genesis. Moreover, early-differentiating 7G6-positive cones are organized into a regular array in immature, peripheral regions of the fetal retina indicating that the spatial arrangement of cones is initiated either during active cone proliferation or the initial differentiation of these cells. These results suggest that the periodic spacing of cones in the primate retina emerges autonomously within the photoreceptor layer, prior to the formation of synaptic connections within the retina or with the brain.

Animals↗
PubMed1997

Successful treatment of esthesioneuroblastoma and neuroendocrine carcinoma with combined chemotherapy and proton radiation. Results in 9 cases.

OBJECTIVE: To study the efficacy of a newly designed treatment strategy for esthesioneuroblastoma and neuroendocrine carcinoma of the paranasal sinuses. DESIGN AND SETTING: Nonrandomized prospective study of a case series in a tertiary referral center. PATIENTS: Nine consecutive patients with newly diagnosed esthesioneuroblastoma or neuroendocrine carcinoma of the paranasal sinuses from June 1992 to October 1995 underwent this treatment protocol. INTERVENTIONS: After histological diagnosis and detailed imaging, 2 cycles of cisplatin and etoposide chemotherapy were instituted. Chemotherapy responders were treated with combined photon and stereotaxic fractionated proton radiation therapy totaling approximately 68 Gy to the primary site, whereas poor responders were treated with surgical resection followed by postoperative radiation. In both cases, therapy was then concluded with 2 additional cycles of cisplatin and etoposide chemotherapy. MAIN OUTCOMES MEASURES: Response to therapy, survival, disease-free survival, and complications of therapy were examined. RESULTS: Nine patients with a median Dulguerov T stage of T3 (range, T2 to T4) completed the treatment protocol, with mean follow-up after diagnosis of 20.5 months. Eight of 9 patients exhibited a dramatic response to therapy with remission of their tumor, and resection was not required. One patient failed to respond to induction chemotherapy and received surgical therapy to be followed by postoperative radiotherapy. There have been no recurrences (mean disease-free interval of 14.0 months). Complications were limited and generally transient. CONCLUSIONS: The use of combined cisplatin and etoposide chemotherapy with proton radiation has demonstrated initial success in treatment of these tumors. Dramatic response from chemotherapy is possible even in bulky or unresectable disease. This protocol has an acceptable complication rate and conveys less morbidity than craniofacial resection and conventional radiotherapy. Further follow-up will be required to determine the long-term success rate of this therapeutic protocol.

Adult↗
PubMed1997

Osseous craniofacial arteriovenous malformations in the pediatric population.

Osseous craniofacial arteriovenous malformations are rare and challenging entities. A 20-year retrospective review at our institutions identified 47 cases of craniofacial arteriovenous malformations, 3 of which were in children with extensive osseous facial structure involvement. Diagnostic evaluation included computed tomography, magnetic resonance imaging, and angiography. A 3-stage treatment protocol employed both transarterial embolization and direct intralesional puncture embolization followed by complete surgical resection. Mean intraperative blood loss was limited to 1000 mL. There were no complications during therapy. All 3 patients are without recurrence at 2- to 4-year follow-up. Osseous craniofacial arteriovenous malformations should be approached with multimodality therapy, incorporating interventional neuroradiologic and surgical management. Using the outlined protocol, these lesions can be treated safely and effectively.

Adolescent↗
PubMed1997

Alimentary tract malignancies in children.

Alimentary tract malignancies in children are unusual. From 1952 to 1996, 54 patients (55 cases) underwent surgery at The Children's Hospital, Columbus for intestinal malignancy. Their records were reviewed retrospectively. The mean age at diagnosis was 9.3 years (range, 1 to 17 years). There were 35 boys and 19 girls (M:F ratio, 1:8). Mean follow-up was 108 months. Laparotomy was performed in all but one child. The primary tumor sites included the colon (31 cases), small bowel (12 cases), appendix (9 cases), and stomach (3 cases). Seventy-five percent of the tumors were non-Hodgkin's lymphomas (41 cases), followed by appendiceal carcinoid (9 cases), colon adenocarcinoma (3 cases), and gastric sarcoma (2 cases). Lymphoma occurred in 28 of 31 nonappendiceal large bowel tumors and was the only tumor type seen in the small intestine. There were 21 Burkitt's, 11 lymphoblastic, 6 small cell, and 5 large cell lymphomas. There was a statistically significant increase in the frequency of small bowel lymphoma after 1982 (10 of 20) in comparison with that before 1982 (2 of 21), P < .05. This coincided with an increase in Burkitt's lymphoma from 5 of 21 (pre-1982) to 16 of 20 (post-1982), and a decrease in lymphoblastic lymphomas from 7 of 21 (pre-1982) to 2 of 20 (post-1982), P < .05. Localized disease and complete resection favored survival in lymphoma, whereas age, sex, and urgency of operation had no influence on survival. This study highlights the predominance of lymphoma as the most common small and large bowel tumor and highlights the emergence of nonendemic Burkitt's as a major entity in pediatric intestinal malignancy.

Adenocarcinoma↗
PubMed1997

Retinoid-induced chromatin structure alterations in the retinoic acid receptor beta2 promoter.

Transcription of the retinoic acid receptor beta2 (RARbeta2) gene is induced by retinoic acid (RA) in mouse P19 embryonal carcinoma (EC) cells. Here we studied RA-induced chromatin structure alterations in the endogenous RARbeta2 promoter and in an integrated, multicopy RARbeta2 promoter in EC cells. RA markedly increased restriction site accessibility within the promoter, including a site near the RA responsive element (RARE) to which the nuclear receptor retinoid X receptor (RXR)-RAR heterodimer binds. These changes coincided with RA-induced alterations in the DNase I hypersensitivity pattern in and around the promoter. These changes became undetectable upon removal of RA, which coincided with the extinction of transcription. Analyses with receptor-selective ligands and an antagonist showed that increase in restriction site accessibility correlates with transcriptional activation, which parallels the RA-induced in vivo footprint of the promoter. Despite these changes, the micrococcal nuclease digestion profile of this promoter was not altered by RA. These results indicate that concurrent with the binding of the RXR-RAR heterodimer to the RARE, the local chromatin structure undergoes dynamic, reversible changes in and around the promoter without globally affecting the nucleosomal organization.

Animals↗
PubMed1997

Retinoid X receptor (RXR) within the RXR-retinoic acid receptor heterodimer binds its ligand and enhances retinoid-dependent gene expression.

Retinoic acid receptor (RAR) and retinoid X receptor (RXR) form heterodimers and regulate retinoid-mediated gene expression. We studied binding of RXR- and RAR-selective ligands to the RXR-RAR heterodimer and subsequent transcription. In limited proteolysis analyses, both RXR and RAR in the heterodimer bound their respective ligands and underwent a conformational change in the presence of a retinoic acid-responsive element. In reporter analyses, the RAR ligand (but not the RXR ligand), when added singly, activated transcription, but coaddition of the two ligands led to synergistic activation of transcription. This activation required the AF-2 domain of both RXR and RAR. Genomic footprinting analysis was performed with P19 embryonal carcinoma cells, in which transcription of the RARbeta gene is induced upon retinoid addition. Paralleling the reporter activation data, only the RAR ligand induced in vivo occupancy of the RARbeta2 promoter when added singly. However, at suboptimal concentrations of RAR ligand, coaddition of the RXR ligand increased the stability of promoter occupancy. Thus, liganded RXR and RAR both participate in transcription. Finally, when these ligands were tested for teratogenic effects on zebra fish and Xenopus embryos, we found that coadministration of the RXR and RAR ligands caused more severe abnormalities in these embryos than either ligand alone, providing biological support for the synergistic action of the two ligands.

Animals↗
PubMed1997

Open heart surgery in patients with end-stage renal disease.

This case-control study evaluated the mortality and morbidity in patients with end-stage renal disease (ESRD) who underwent open heart surgery, as compared with matched control patients. Outcome measures included length of use of ventilators, vasopressor agents, number of blood units transfused, chest tube output, and length of stay. Hospital length of stay was longer in patients with renal failure, but overall morbidity and mortality were not statistically different. Conclusions include that elective open heart surgery can be performed safely in ESRD patients using routine perioperative management.

Aged↗
PubMed1997

Endoscopic excision of a giant pyogenic granuloma of the nasal cavity caused by nasal packing.

A case of a giant pyogenic granuloma of the inferior turbinate secondary to nasal packing is presented and its removal via an endoscopic approach is detailed. The sinus endoscope provides excellent visualization and operative control during excision, obviating the need for a lateral rhinotomy. Pyogenic granulomas of the posterior nasal cavity are rare, and should be considered when a nasal mass is detected after packing for epistaxis.

Adult↗
PubMed1996

An in vitro qualitative assay for the detection of antibodies to HIV type 1/2 contained in human saliva.

There is ample evidence that saliva contains secretory antibody against most infections. Therefore, saliva has been recommended as a non invasive, safe and effective alternative to serum, for HIV antibody testing. The present study attempted comparative evaluation of antibody detection by serum and saliva specimens in laboratory by ELISA and Western Blot for diagnosis of HIV infection in the Indian situation. From a study of 42 test sera it is concluded that test apart from its simplicity and reproducibility, is almost free from any false positive and false negative reactions.

Blotting, Western↗
PubMed1995

Response of colon cancer cell lines to the introduction of APC, a colon-specific tumor suppressor gene.

The APC gene, mutations in which are responsible for the inherited colon cancer syndrome adenomatous polyposis coli (APC), is described as a tumor suppressor gene. A full-length, wild-type APC gene was introduced by transfection into three human colon carcinoma cell lines, each characterized for mutations at loci involved in colon tumor formation. The response of each cell line to the introduction of APC differed with the genotype of the cell line. Some of the cell clones derived from these transfections displayed altered morphologies; some showed suppression of tumorigenicity based on growth in soft agar and tumor formation in nude mice. One cell line, SW480, could not be stably transfected with the APC gene. These results provide the first direct evidence that the APC gene can alter the transformation properties of colon carcinoma cells.

Animals↗
PubMed1994

A bacteriologic basis for the evolution and severity of empyema.

The management of pediatric empyema remains controversial. An experimental study was undertaken to evaluate the role of bacteria in the evolution and severity of empyema, using specific bacteria that are pathogens of empyema in children. A rabbit model was used. The groups were Haemophilus influenzae (n = 9), Bacteroides fragilis (n = 8), the combination (n = 12), Staphylococcus aureus (n = 6), and control (n = 6). The total bacterial inoculum (10(8)) was constant. Diagnostic thoracentesis was performed at regular intervals. Characteristics of the empyema were evaluated when the rabbits were killed (at 4, 7, and 10 days). Most rabbits other than those of the mixed-bacteria group cleared the bacteria from their pleural cavities. Eleven of 12 mixed-bacteria animals had multiloculated empyemas; only one resolved spontaneously. In the other groups, the tendency was toward unilocular empyemas, which resolved by the 10th day in one third of the H influenzae animals, two thirds of the Bacteroides fragilis animals, and half the S aureus animals. The empyemas that persisted until the 10th day were in the exudative or fibrinopurulent stage, except for those of the mixed-bacteria group, all of which were in the advanced organizing stage. The amount of pleural debris and the degree of organization were significantly greater for the mixed bacteria group (P > .01). These findings support the clinical management of monobacterial empyema by simple drainage, whereas mixed aerobic-anaerobic empyemas may require more aggressive drainage procedures.

Animals↗
PubMed1994

Protooncogene, growth factor, growth factor receptor, and estrogen and progesterone receptor gene expression in the immature rat uterus after treatment with estrogen and tamoxifen.

The mechanism(s) by which estrogen regulates cell growth in target cells and the cascade of biochemical changes associated with growth have not yet been fully determined. Equally undetermined is an understanding of the mechanism(s) by which tamoxifen blocks estrogen-regulated growth. This study, therefore, attempts to define and correlate the physiological processes in the rat uterus following estrogen and tamoxifen administration with temporal events manifested by mRNA expression of protooncogenes (m-myc, c-ras, c-fos, c-jun), growth factors and/or inhibins (IGF-1, IGF-2, IGF-2 Exon 1 and Exon 2), EGF, TGFB-1, -2, -3), growth factor or inhibin receptors (EGFr, TGFB-2r, TGFB-3r), and estrogen-induced differentiative proteins including estrogen receptor (ER), progesterone receptor (PR). In this study, mRNA was isolated from hormone and antagonist-treated rat uteri at 0', 15', 30', 1 h, 6 h, 24 h, 48 h and 72 h. Expression studies were analysed by dot/Northern blot hybridization with cDNA or oligonucleotide probes for the RNAs mentioned above. Nuclear runoff transcriptional assays were also performed. Our data suggest that fos, myc, ras and jun protooncogenes were expressed from 15' to 48 h after treatment with either estrogen or tamoxifen. Tamoxifen treatment resulted in diminished expression, but incomplete inhibition of the protooncogene mRNAs. Estrogen treatment resulted in rapid elevation of both EGF and EGFr mRNA levels, both of which were suppressed after tamoxifen treatment. Tamoxifen may exert its antiestrogenic effects by inhibiting EGF and EGFr, and myc protooncogene activity on the one hand, and by overexpression of the TGFB isotypes and their receptors on the other hand. With the proliferation cycle short circuited, tamoxifen-treated cells hypertrophied and differentiated to terminal cells by 24-48 h. Working hypotheses for the mechanisms of action of estrogen and tamoxifen are presented based on our data.

Animals↗
PubMed1994

Estrogen induced peroxidase secretion from the endometrial epithelium: a possible function for the luminal enzyme.

Estrogen induced peroxidase (EIP) activity revealed as a diaminobenzidine-H2O2 product in electron micrographs is apparent within cisternae of the RER and in large dilated apical vesicles, of which only a few have been seen to open into the uterine lumen. EIP activity is infrequently present in the trans cisternae of the rather diminutive Golgi complex in uterine epithelial cells from 12-72 h after treatment with estrogen. EIP activity is, however, prominent on the surface of microvilli of epithelial cells and as deposits in the lumen. Desalted uterine fluid (72 h) isolated by rotofor (Biorad) and analysed on isoelectric focusing gels that were stained with the diaminobenzidine-H2O2 reaction, reveal the existence of at least 6 peroxidase isoelectric variants with isoelectric points between pI 3.5 and pI 5.0. In similar preparations doubly-stained by diaminobenzidine-H2O2 and silver, peroxidase positive bands are enhanced, along with other isoelectric variants in the acidic pI range. In SDS-PAGE preparations, five prominent proteins ranging from 29-115 kD are present in 72 h uterine fluid. Luminal EIP coats the surface microvilli of the reproductive tract cells, and of viable spermatozoa incubated in uterine fluid. Peroxidase coated bacteria appear to be in the process of decay, and enzyme activity is present on the surface of most spermatozoa. It is not yet determined if EIP has bactericidal, spermicidal or capacitation functions.

Animals↗
PubMed1993

Transcriptional regulation of the gene encoding apolipoprotein AI in chicken LMH cells.

Previous studies indicated that the differential expression of the chicken gene (ApoAI) encoding apolipoprotein AI (ApoAI) in the QMLA-29 and LMH cell lines may be the result of altered cis-elements and/or trans-acting factors. To examine the cis-elements, LMH DNA was used as a template and the 5'-upstream region of ApoAI was PCR amplified. The nucleotide sequence of the LMH ApoAI upstream region was identical to that obtained from young chicken liver DNA. Band shift analyses of the -87 to +90 bp upstream DNA of ApoAI showed differences in the shifting patterns when nuclear proteins from LMH and liver cells were used. Southwestern blots with the same DNA fragment and nuclear proteins from liver and LMH also showed differences. There was one common band of approx. 65 kDa. In addition, LMH had a trans-acting factor of approx. 26 kDa, while liver had an approx. 46-kDa protein. These data suggest that LMH has a different trans-acting factor which may downregulate ApoAI expression.

Animals↗