Biomedical subjects

S Nandi

Publications and source records attributed to S Nandi.

At least 55 records · Page 3Linked to original sources

PubMed2000

Expression of MAT1/PEA-15 mRNA isoforms during physiological and neoplastic changes in the mouse mammary gland.

MAT1 is a novel transforming gene which was cloned from a mouse mammary tumor induced by N-methyl-N-nitrosourea in vitro in the presence of lithium as a mitogen. Later, it was found to be identical to the 3' untranslated region (UTR) of the 2.5 kb isoform of PEA-15 (phosphoprotein enriched in astrocytes-15 kDa). We re-cloned MAT1/PEA-15 cDNAs and showed 2.5, 2.0 and 1.8 kb isoforms and confirmed MAT1 localization as reported. The 2.0 and 1.8 kb isoforms were produced by alternative splicing and alternative polyadenylation at the 3' UTR, respectively. To analyze the role of MAT1/PEA-15, we examined the expression of MAT1/PEA-15 mRNA in normal mammary tissues and in mammary tumors. The mammary gland during pregnancy, lactation and weaning showed weak but stable expression. Compared with normal mammary gland, mammary tumors showed stronger expression. Aberrant expression of MAT1/PEA-15 isoforms was found in mouse mammary epithelial cell lines, FSK7 and TM6, which lost the 2.5/2.0 and 2.5 kb isoforms, respectively. In contrast to other oncogenes like c-myc, MAT1/PEA-15 mRNA was extremely stable after actinomycin D and cycloheximide treatments suggesting that other protein expression is prerequisite for degradation of MAT1/PEA-15 mRNA. It evoked the possibility of the 3' UTR of MAT1/PEA-15 (designated as MAT1-T) as a riboregulator in mammary tumorigenesis and necessity for further analysis of human breast cancers as well as mouse mammary tumors.

Animals↗

PubMed2000

Psychiatric morbidity of a rural Indian community. Changes over a 20-year interval.

BACKGROUND: Cross-sectional studies give no indication of the changes that may occur in the mental health status of a community in course of times. Studies should be designed to assess these changes. AIMS: To assess the changes, if any, in the prevalence of mental disorders in a rural community after an interval of 20 years in the context of its changing socio-economic conditions. METHOD: A door-to-door survey of the prevalence of psychiatric morbidity in two villages was conducted by a team of psychiatrists. The survey was repeated after 20 years by the same team and by the same method. Changes in the mental health status of the community were compared. RESULTS: Total morbidity per 1000 fell from 116.8 to 105.2. Morbidity in men fell from 86.9 to 73.5 per 1000 and in women from 146.8 to 138.3 per 1000. Rates of anxiety, hysteria and phobia had fallen dramatically and those of depression and mania had risen significantly. CONCLUSION: The level of psychiatric morbidity showed no statistically significant change. The morbidity pattern (relative proportion of type of morbidity), however, showed some interesting changes. Similar studies should be done on a larger sample.

Adolescent↗

PubMed2000

Estrogen receptor variants in epithelial compartment of normal human breast.

Estrogen receptor (ER) splice variants have previously been identified in normal human breast. Normal breast, however, comprises many cell types including fat cells, fibroblasts, endothelial cells, and a variety of inflammatory cells besides breast epithelial cells. The objective of our study was to demonstrate the existence of several variants in the epithelial compartment of the normal human breast. To this end, highly enriched breast epithelial cells from reduction mammoplasty specimens were isolated using Percoll gradient centrifugation. We analyzed the presence of both wild-type (WT) and variant receptors in human breast epithelial cells using the seminested polymerase chain reaction and direct automated sequencing of the amplified products. We demonstrated that a number of spliced variants of the ER coexist with the WT receptor. Variants lacking exons 2, 4, 5, and 7 are detected in the breast epithelial compartment of the normal human breast.

Alternative Splicing↗

PubMed2000

Estrogen receptor variants are present in many normal human tissues.

Estrogen receptors (ER) are present in various reproductive tissues as well as in other tissues not considered classical targets for estrogen. A variety of alternatively spliced ER variants which co-exist with the wild-type receptor has also been described in many tissues. We analyzed the presence of both wild-type and variant receptors from normal human tissues of various origin using semi-nested PCR and direct automated sequence of the amplified products. We demonstrate that many normal human tissues of various origin contain a number of spliced variants of the estrogen receptor that co-exist with the wild-type receptor. Variants lacking exons 2, 4, 5, and 7 are detected in a variety of normal human tissues.

Adolescent↗

PubMed1999

Hormonal prevention of breast cancer: mimicking the protective effect of pregnancy.

Full term pregnancy early in life is the most effective natural protection against breast cancer in women. Rats treated with chemical carcinogen are similarly protected by a previous pregnancy from mammary carcinogenesis. Proliferation and differentiation of the mammary gland does not explain this phenomenon, as shown by the relative ineffectiveness of perphenazine, a potent mitogenic and differentiating agent. Here, we show that short term treatment of nulliparous rats with pregnancy levels of estradiol 17beta and progesterone has high efficacy in protecting them from chemical carcinogen induced mammary cancers. Because the mammary gland is exposed to the highest physiological concentrations of estradiol and progesterone during full term pregnancy, it is these elevated levels of hormones that likely induce protection from mammary cancer. Thus, it appears possible to mimic the protective effects of pregnancy against breast cancer in nulliparous rats by short term specific hormonal intervention.

Animals↗

PubMed1999

Isolation of oncogenes from rat mammary tumors by a highly efficient retrovirus expression cloning system.

A majority of mammary tumors induced with N-methyl-N-nitrosourea in rats contain G to A transitional mutation of c-Ha-ras at the 12th codon. Additional oncogene activation is known to be necessary for further tumor progression. To isolate novel oncogenes, we used an expression cloning system utilizing the pMX retroviral vector in combination with BOSC23 packaging cells. First, we elucidated the sensitivity of this system in the NIH 3T3 focus assay; foci were detectable even after 10(-6) dilution using v-Ha-ras, neuT, and beta-galactosidase constructs in pMX vector. This system is sensitive enough to detect low copy number cDNAs. We used the pMX/BOSC23 expression cloning system to clone novel oncogenes from rat mammary tumors harboring an activated c-Ha-ras and isolated several candidate oncogenes that caused transformation of NIH 3T3 cells and/or generated tumors when transplanted to nude mice.

3T3 Cells↗

PubMed1999

Bovine ephemeral fever: a review.

Bovine ephemeral fever is a viral disease of cattle and buffaloes besides subclinical involvement of a variety of ruminant species. The subtropical and temperate regions of Africa, Asia and Australia have experienced the major epidemic of the bovine ephemeral fever but the occurrence in the tropics can not be overlooked. Although the substantial role played by the vectors viz., mosquitoes and culicoides in bovine ephemeral fever perpetuation and dissemination, other vector involvement if any should be extensively studied. The clinical severity of the disease is not apparent and the mortality is low. However, high morbidity, enormous economic losses in terms of significant reduction in production, disruption of national and international trade and finally a variety of complications resulting from the disease have drawn appreciable attention from the researchers around the world to resolve the unsolved questions in this area. In this review, detailed informations of all the aspects of the disease has been provided in a simple, lucid and easily understandable manner.

Animals↗

PubMed1999

Protective effects of pregnancy and lactation against N-methyl-N-nitrosourea-induced mammary carcinomas in female Lewis rats.

The role of parity before and after N-methyl-N-nitrosourea (MNU) treatment in protection against mammary carcinogenesis was investigated. The effect of lactation on reduction in the incidence of mammary carcinoma was also examined. Parous rats were compared with respective age-matched virgins (AMVs). Pregnancy and lactation prior to MNU exposure significantly reduced both the incidence of mammary carcinoma (22 versus 72%) and the average number of mammary carcinomas per rat (0.22 versus 0.86) and significantly prolonged the latency of the carcinomas (247 versus 215 days). Pregnancy and lactation following MNU exposure also significantly reduced both the incidence of mammary carcinoma (25 versus 94%) and the average number of mammary carcinomas per rat (0.25 versus 1.50) and significantly prolonged the latency (240 versus 155 days). Lactation showed an additive effect on the reduction in mammary cancer. Pregnancy suppressed the number of estrogen receptor (ER)- and progesterone receptor (PgR)-positive cells and lowered the cell proliferation rate in the non-tumoral mammary glands. Since the majority (>76%) of the mammary carcinomas was hormone dependent in both the parous and AMV rats, pregnancy and lactation appear to decrease the ER- and/or PgR-positive cells presumed to be the progenitors of hormone-dependent carcinomas and they lowered the cell turnover necessary for tumor promotion in parous rats, resulting in a lower mammary carcinoma yield.

Animals↗

PubMed1999

Induction of mammary carcinomas by N-methyl-N-nitrosourea in ovariectomized rats treated with epidermal growth factor.

The importance of epidermal growth factor (EGF) in both normal and malignant mammary gland development are presented in these studies. Initial findings demonstrated that in the absence of ovarian hormones, EGF had a significant proliferative effect on mammary epithelial cells. To determine whether mammary epithelial cells grown with EGF, in the absence of ovarian hormones, could be transformed by N-methyl-N-nitrosourea (MNU), female ovariectomized Lewis rats were implanted with pellets containing EGF for 1 week and then treated with MNU for initiation. Two days after MNU treatment, ovaries were implanted and EGF pellets were removed from all ovariectomized groups in order to promote carcinogenesis. The mammary carcinoma incidence of the EGF-stimulated group (90%) was not significantly different from the intact group (100%). The mammary cancer morphology of EGF-treated carcinomas was either ductal carcinoma or cribriform adenocarcinoma, whereas intact animals developed mainly papillary and occasional cribriform carcinomas. Fifty-eight percent of the carcinomas from the EGF group were ovarian hormone-independent compared with 10% of carcinomas from the intact group. These results demonstrate that EGF-induced proliferation during initiation with MNU was sufficient to induce the transformation of mammary carcinomas in the absence of ovarian hormones. The hormonal dependency of these EGF-induced carcinomas were different compared with MNU-initiated mammary carcinomas in intact rats.

Adenocarcinoma↗

PubMed1999

Germ cell apoptosis in the testes of Sprague Dawley rats following testosterone withdrawal by ethane 1,2-dimethanesulfonate administration: relationship to Fas?

Germ cell apoptosis, which occurs normally during spermatogenesis, increases after testosterone withdrawal from the testis. The molecular mechanism by which this occurs remains uncertain. The Fas system has been implicated as a possible key regulator of apoptosis in various cells: binding of Fas ligand (FasL), a type II transmembrane protein, to Fas, a type I transmembrane receptor protein, triggers apoptosis in cells expressing Fas. Recently, Fas has been localized to germ cells, and FasL to Sertoli cells, within the rat testis. We hypothesized that Fas protein content would rise in response to reduced levels of testosterone as part of a suicide pathway that would result in germ cell apoptosis. To test this hypothesis, ethane 1,2-dimethanesulfonate (EDS), a Leydig cell toxicant, was used to kill Leydig cells and thus reduce intratesticular testosterone levels in Sprague Dawley rats. Apoptosis was examined in situ and biochemically, and Fas protein content in the testis was monitored by Western blot analysis. We show that EDS injection results in the following sequence of events: apoptotic death of Leydig cells by a mechanism that does not involve Fas; reduced testosterone; increased testicular Fas content; and germ cell apoptosis. These results suggest that Fas may play a role in the apoptotic death of germ cells that results from reduced intratesticular testosterone levels, and that testosterone may play a role in germ cell survival via its suppression of Fas.

Animals↗

PubMed1999

Resurgent Vibrio cholerae O139: rearrangement of cholera toxin genetic elements and amplification of rrn operon.

The unprecedented genesis of a novel non-O1 Vibrio cholerae strain belonging to serogroup O139, which caused an epidemic in late 1992 in the Indian subcontinent, and its subsequent displacement by El Tor O1 vibrios after 18 months initiated a renewed investigation of the aspects of the organism that are related to pathogenesis. The reappearance of V. cholerae O139 with altered antibiotic sensitivity compared to O139 Bengal (O139B) in late 1996 has complicated the epidemiological scenario of V. cholerae and has necessitated an examination of possible rearrangements in the genome underlying such rapid changes in the phenotypic traits. With a view to investigating whether the phenotypic changes that have occurred are associated with alteration in the genome, the genome of the resurgent V. cholerae O139 (O139R) strains were examined. Pulsed-field gel electrophoresis analysis of NotI- and SfiI-digested genomic DNA of O139R isolates showed restriction fragment length polymorphism including in the cholera toxin (CTX) genetic element locus and with O139B isolates. Analyses of the organization of the CTX genetic elements in O139R strains showed that in contrast to two copies of the elements connected by two direct-repeat sequences (RS) in most of the genomes of O139B isolates, the genomes of all O139R strains examined, except strain AS192, have three such elements connected by a single RS. While the RS present in the upstream of the CTX genetic elements in the genome of O139R is of O139B origin, the RS connecting the cores of the elements has several new restriction sites and has lost the BglII site which is supposed to be conserved in all O1 strains and O139B. The endonuclease I-CeuI, which has sites only in the rrn operons in the genomes of all organisms examined so far, has 10 sites in the genomes of O139R strains, compared to 9 in the genomes of O139B strains. The recent isolates of V. cholerae O139 have thus gained one rrn operon. This variation in the number of rrn operons within a serogroup has not been reported for any other organism. The results presented in this report suggest that like the pathogenic El Tor O1 strains, the genomes of O139 strains are undergoing rapid alterations.

Cholera Toxin↗

PubMed1999

Clonal diversity among recently emerged strains of Vibrio parahaemolyticus O3:K6 associated with pandemic spread.

The genomes of the O3:K6 strains of Vibrio parahaemolyticus which abruptly emerged in Calcutta, India, in February 1996 and which demonstrated an unusual potential to spread and an enhanced propensity to cause infections were examined by different molecular techniques to determine clonality. No restriction fragment length polymorphism (RFLP) in the gene encoding the thermostable direct hemolysin was observed among the O3:K6 isolates of V. parahaemolyticus. Clonal diversity among the O3:K6 strains became evident by examining the RFLPs of the rrn operons and by the use of pulsed-field gel electrophoresis. Five ribotypes were distinguished among the O3:K6 strains examined, with ribotype R4 constituting the major type. Strains of O3:K6 isolated between June and August 1996 showed different pulsotypes compared to the pulsotypes of strains isolated before and after this period, indicating genetic reassortment among these strains, but those isolated between August 1996 and March 1998 showed identical or nearly similar pulsotypes. It is clear that there is a certain degree of genomic reassortment among the O3:K6 clones but that these strains are predominantly one clone.

Bacterial Typing Techniques↗

PubMed1998

Defective retrovirus insertion activates c-Ha-ras protooncogene in an MNU-induced rat mammary carcinoma.

Endogenous retrovirus sequences are present in the genome of a wide variety of animal species. The activation of the proto-oncogenes of the ras family, particularly c-Ha-ras, by either point mutation or overexpression, has been shown to be associated with a vast number, of different cancers. here we report that the insertion of a defective retrovirus in the -1 intron of rat c-Ha-ras is responsible for the activation of the gene by over 10-fold overexpression in an MNU-induced rat mammary cancer. A portion of the 3' end of the retroviral sequence is expressed as a part of the c-Ha-ras transcript in the carcinoma tissue, indicating the direct involvement of this element in the transcription of the c-Ha-ras gene. The c-Ha-ras structural gene transcribed by the promoter of the defective retroviral element can neoplastically transform the NIH 3T3 cell line upon transfection.

3T3 Cells↗

PubMed1998

Influence of cumulus cells and sperm concentration on cleavage rate and subsequent embryonic development of buffalo (Bubalus bubalis) oocytes matured and fertilized in vitro.

The objective of the present study was to investigate the effects of sperm concentration and presence or absence of cumulus cells on fertilization, cleavage rate and subsequent embryonic development upto the blastocyst stage in buffalo. Cumulus-oocyte-complexes (COCs) obtained from slaughterhouse ovaries were matured in vitro in TCM-199 + 10% FBS + 5 micrograms/mL FSH-P for 24 h. After maturation the COCs were either used as such (cumulus-intact) or freed from attached cumulus cells by repeated pipetting (cumulus-free). Frozen-thawed buffalo spermatozoa were treated with 10 micrograms/mL heparin and 2.5 mM caffeine for sperm capacitation. Oocytes were fertilized in vitro with 1 to 2, 4 to 5 or 9 to 10 million sperm/mL and the cleavage rate was recorded 42 to 44 h post insemination. The cleaved embryos were co-cultured with buffalo oviductal epithelial cells for 10 d post insemination, and the uncleaved oocytes were fixed and stained with aceto-orcein for determination of the penetration rate. The cleavage rate and the proportion of cleaved embryos that developed to morula and blastocyst stages were significantly higher (P < 0.05) whereas the proportion of degenerated oocytes and those that became arrested at the 2 to 16-cell stage were significantly lower (P < 0.05) with cumulus-intact than with cumulus-free oocytes at the 3 sperm concentrations. Increasing the sperm concentration increased the cleavage rate significantly (P < 0.05) from 1 to 2 million through 9 to 10 million sperm/mL but had no effect on the proportion of cleaved embryos that developed to morula and blastocyst stages. In conclusion, the results of the present study suggest that cumulus cells have a positive influence on fertilization, cleavage and subsequent embryonic development. Increase in sperm concentration increases cleavage rate without affecting subsequent embryonic development.

Animals↗

PubMed1998

Portal hypertensive gastropathy and gastric varices before esophageal variceal sclerotherapy and after obliteration.

OBJECTIVES: To evaluate the frequency and clinical importance of portal hypertensive gastropathy (PHG) and gastric varices (GV) before endoscopic sclerotherapy (EST) and after esophageal variceal obliteration. METHODS: Patients with portal hypertension (PHT) with variceal bleed were prospectively evaluated for PHG and GV before EST with intravariceal injection of absolute alcohol and after esophageal variceal obliteration. Gastric varices and PHG were characterized and graded according to previously established criteria. Patients were followed up for 12-48 (mean 37) months after variceal obliteration. RESULTS: Of 70 patients with PHT 26 had PHG before (severe in two) [18/37 in cirrhosis, 6/20 in non-cirrhotic portal fibrosis (NCPF), and 2/13 in extrahepatic portal vein obstruction (EHPVO)] and 50 had PHG after variceal obliteration (severe in 22) (27/37 in cirrhosis, p = 0.03 before versus after esophageal variceal obliteration; 16/20 in NCPF, p < 0.01; and 7/13 in EHPVO, p = ns). Type I GV (continuation of esophageal varix into the stomach) was found in 25/70 before and 5/70 after esophageal variceal obliteration (p < 0.001); in contrast, other types of GV were seen in 14/70 before and 29/70 after (p < 0.01). Overt bleeding from GV and PHG during follow-up after variceal obliteration occurred in 6 and 4 patients, respectively. CONCLUSIONS: Esophageal variceal obliteration by EST increases the frequency of PHG and GV (except type I GV which get obliterated); both PHG and GV have potential to cause rebleeding.

Adolescent↗

PubMed1997

Synergistic effect of MNU and DMBA in mammary carcinogenesis and H-ras activation in female Sprague-Dawley rats.

The combined application of N-methyl-N-nitrosourea (MNU) and 7,12-dimethylbenz[alpha]anthracene (DMBA) was compared with the administration of each carcinogen alone as to the effectiveness of the induction of mammary carcinomas and the influence of H-ras oncogene activation in female Sprague-Dawley rats. At 50 days of age, group 1 received 30 mg/kg MNU intraperitoneally (i.p.), group 2 received 30 mg/kg DMBA i.p., group 3 received 60 mg/kg MNU i.p., group 4 received 60 mg/ kg DMBA i.p., group 5 received 30 mg/kg MNU followed by 30 mg/kg DMBA i.p., group 6 received 30 mg/kg MNU i.p. and then 30 mg/kg DMBA intravenously (i.v.) and group 7 remained untreated. Animals were killed when the largest mammary tumor reached 1-2 cm in diameter or were necropsied when they were 30 weeks of age. MNU i.p. produced no deaths (groups 1 and 3), however, the i.p. administration of DMBA induced death due to peritonitis (groups 2, 4 and 5), whereas the i.v. administration of DMBA suppressed the death (group 6). All of the tumors produced by MNU were adenocarcinomas of mammary origin. In contrast, DMBA produced tumors of other than mammary origin. The combined treatment with DMBA and MNU increased the mammary carcinogenic effect; it significantly increased the mean number of mammary cancers per rat. With either carcinogen alone and in combination, the mammary carcinomas produced identical adenocarcinoma histology. Of the mammary carcinomas induced by the combined application of MNU and DMBA (group 6), all 11 tumors from five rats showed the GGA to GAA transitional mutation in H-ras codon 12 (38%) and all 18 tumors from the other 10 rats remained as wild-type. An H-ras point mutation at codon 61 was not detected.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1997

Mapping QTLs for submergence tolerance in rice by AFLP analysis and selective genotyping.

By combining the amplified fragment length polymorphism (AFLP) technique with selective genotyping, we constructed a linkage map for rice and assigned each linkage group to a corresponding chromosome. The AFLP map, consisting of 202 AFLP markers, was generated from 74 recombinant inbred lines (RIL) which were selected from both extremes of the population (250 lines) with respect to the response to complete submergence. Map length was 1756 cM, with an average interval size of 8.5 cM. To assign linkage groups to chromosomes, we used 50 previously mapped AFLP markers as anchor markers distributed over the 12 chromosomes. Other AFLP markers were then assigned to specific chromosomes based on their linkage to anchor markers. This AFLP map is equivalent to the RFLP/AFLP map constructed previously as the anchors were in the same order in both maps. Furthermore, tests with two restriction fragment length polymorphism (RFLP) markers and two sequence-tagged site (STS) markers showed that they mapped in the expected positions. Using this AFLP map, a major gene for submergence tolerance was localized on chromosome 9. Quantitative trait loci (QTL) associated with submergence tolerance were detected on chromosomes 6, 7, 11, and 12. We conclude that the combination of AFLP mapping and selective genotyping provides a much faster and easier approach to QTL identification than the use of RFLP markers.

Chromosome Mapping↗

PubMed1997

Biochemical characterization of FMDV A10 and A22 subtypes by PAGE and IEF.

Both polyacrylamide gel electrophoresis (PAGE) and iso-electric focusing (IEF) have been standardized using the sucrose density gradient purified 146S particles of FMD virus subtypes A10 and A22. Differences in the molecular weights of structural proteins (VP1, VP2 and VP3 of two subtypes (A10 and A22) of FMDV have been revealed in PAGE but no appreciable differences in the pI of VP1, VP2 and VP3 is found in IEF.

Aphthovirus↗