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Biomedical subjects

S Mathew

Publications and source records attributed to S Mathew.

At least 55 records · Page 3Linked to original sources
PubMed1996

Synthesis of sulphated proteoglycans by primary cultures of rat hepatocytes--modulation by matrix substratum.

Primary cultures of rat hepatocytes maintained on different matrix proteins such as collagen (Co IV) fibronectin (Fn), Laminin (Ln) or different tissue biomatrices were metabolically labelled with 35[S]-SO4 and the synthesis of sulphated proteoglycans was studied. The incorporation of the label into total glycosaminoglycan (GAG) was significantly higher in cells maintained on Co IV compared to those maintained on Fn or Ln. Similarly the incorporation of label was maximum in those cells maintained on the aortic biomatrix compared to liver or mammary gland biomatrix. About 80-95% of the GAG synthesised and secreted by cells maintained on individual matrix proteins and liver biomatrix was heparan sulphate (HS). But in the case of cells maintained on collagen IV aortic or mammary biomatrix in addition to HS, significant amount of chondroitin sulphate (CS) was also found. Nearly 50% of the total 35[S]-GAG was associated with the cell layer after 24 h in culture in the case of cells maintained on individual matrix protein while those maintained on tissue biomatrix, retained about 70% of the 35[S]-labelled proteoglycans (PG) with the cell layer. Analysis of the cell surface 35[S]-labelled proteoglycans isolated from cells maintained on different biomatrix showed that it is a hybrid proteoglycan consisting of CS and HS. While the PG isolated from cells maintained on liver biomatrix consists of HS and CS in the ratio of 3:2 that from cells maintained on aorta or mammary gland matrix was about 2:3 indicating an alteration in the nature of the cell surface PGs produced by cells maintained on different tissue biomatrix. These results indicate that depending on the nature of the matrix substratum with which the cells are in contact, the nature and quantity of sulphated proteoglycans produced by hepatocytes vary.

Animals↗
PubMed1996

REL proto-oncogene is frequently amplified in extranodal diffuse large cell lymphoma.

Comparative genomic hybridization (CGH) analysis of DNA extracted from a diffuse lymphoma with a large cell component (DLLC) that displayed double minute chromosomes upon conventional karyotypic analysis indicated overt amplification of DNA sequences derived from the 2p13-15 region. Southern blot analysis of this tumor DNA with a cDNA probe for the proto-oncogene REL, previously mapped to 2p14-15, indicated a greater than 35-fold amplification of REL. To determine the incidence of REL amplification and possible clinical or histologic association with DLLC, a panel of 111 tumor DNAs from DLLC specimens was screened for REL amplification by Southern blot analysis. A copy number of > or = 4 was noted in 26 cases (23%). Southern blot analysis of these 26 tumor DNAs with a cDNA probe for TGFA, mapped to 2p13, indicated lack of coamplification except in one case. Another member of the Rel/NF-kappa B family of transcriptional activators, RELA/p65 mapped to 11q13, was amplified in five cases as determined by Southern blot analysis using a cDNA probe. Nineteen of the 26 DLLC (73%) with REL amplification were primary extranodal lymphomas. As a group, the tumors with REL amplification demonstrated an increased frequency of chromosomal aberrations previously associated with tumor progression, suggesting an oncogenic effect of amplified REL in B-lymphoid cells that already contained a transforming genetic lesion. Thus, REL amplification is a frequent event in DLLC, and probably constitutes a progression-associated marker of primary extranodal lymphomas. This study shows the usefulness of the CGH technique in identifying chromosomal regions overrepresented in tumors that can point to amplified genes and may be correlated with clinical features of the disease.

Aneuploidy↗
PubMed1996

Promoter of the canine tracheobronchial mucin gene.

The mucin gene is up-regulated in diseases such as cystic fibrosis (CF) and asthma. To understand the mechanisms involved in transcriptional regulation of mucin gene expression we have characterized the region of the mucin gene up-stream of the transcriptional start site and analysed the cis-acting elements required for mucin promoter activity. We isolated clones from a dog genomic library containing the promoter region for the tracheobronchial mucin gene (TBM). The authenticity of the promoter was tested by nucleotide sequencing, primer extension analysis, electrophoretic mobility shift assay (EMSA) and reporter gene expression analysis. The canine TBM promoter is different from housekeeping gene promoters (as it is not rich in GC content and contains TATA- and CAAT-like sequences) and different from that of regulatory genes (because it contains many TATA- and CAAT-like sequences and multiple transcriptional initiation sites). Reporter gene analysis using canine TBM promoter-chloramphenicol acetyltransferase (CAT) fusion plasmids established the regions responsible for promoter activity and verified the positions of the major mucin transcriptional initiation sites. Reporter gene analysis also established that a region of the canine TBM promoter and first exon containing all of the transcriptional initiation sites is more active in mucin expressing cells (e.g. CT1 cells-immortalized canine tracheal epithelial cells, human CFT1 cells-immortalized tracheal epithelial cells from a CF subject, or HBE1 cells-immortalized tracheal epithelial cells from non-CF subject) than in mucin non-expressing cells (COS7, 3T3), suggesting cell specificity. The promoter region contained cAMP response element (CRE) sequences, and the TBM gene transcription was enhanced when cAMP analogs were added to transfected cells. EMSA indicated the presence of at least two DNA binding proteins in CT1 cells. This is the first report describing the characterization of a TBM gene promoter. The information obtained in the present studies will be valuable in understanding mucin gene regulation in normal and pathological conditions.

Animals↗
PubMed1996

Ochratoxin induced hemolysis in rabbits.

A saline suspension of RBC when incubated with an increasing concentration (1 to 10 micrograms/ml) of crude ochratoxin at 37 degrees C for 16 hr showed a marked alteration in morphological characters followed by hemolysis. The effect was more pronounced with higher concentration of toxin. The result suggests extreme cytotoxic effect of ochratoxin on RBC leading to its lysis.

Animals↗
PubMed1996

Mediastinal enterogenic cyst presenting as paraplegia--a case report.

A rare case of a mediastinal enterogenic cyst with an intraspinal extension through a anterior vertebral defect presenting with paraplegia in a 10 year boy is presented. Laminectomy and the trans-thoracic excision of the cyst resulted in the complete recovery of the neural deficit.

Abnormalities, Multiple↗
PubMed1996

Selection for high and low number of sternopleural bristles in Drosophila ananassae: correlated response in the frequency of chromosome inversions.

Directional selection for high and low number of sternopleural bristles in Drosophila ananassae was applied for 13 generations. The selection produced a rapid divergence in the mean number of sternopleural bristles in the replicates high and low lines: i-high (H1 -25.75, H2 -25.69); ii-low (L1 -14.16 L2 -13.55); iii-control (17.21) lines in G13. Regression coefficients for the high and low lines were significantly different from zero. The realized heritability over thirteen generations was 21-23 for the high lines and 14-18 for the low lines. The results suggest that the number of sternopleural bristles in D. ananassae is under polygenic control, with a substantial amount of additive genetic variation. Flies of the base population had three chromosome inversions: AL (2L), ZE (2R) and DE (3L). The comparisons of chromosome arrangement between high and low lines (the G13 generation of selection) indicates significant changes in the inversion frequency during the course of selection, providing evidence for correlation between the bristle number and particular chromosome arrangements.

Animals↗
PubMed1995

Chromosomal assignment of human ID1 and ID2 genes.

The Id (inhibitor of DNA binding) proteins regulate transcription during development by interacting with transcription factors. Three human genes, ID1, ID2, and ID3, have been identified that belong to this family of transcription regulators. We show, by somatic cell hybridization and fluorescence in situ hybridization experiments, that ID1 and ID2 are localized at 20q11 and 2p25, respectively.

Blotting, Southern↗
PubMed1995

Structure and mapping of the human thymopoietin (TMPO) gene and relationship of human TMPO beta to rat lamin-associated polypeptide 2.

Thymopoietins (TMPOs, previously abbreviated TPs) alpha (75 kDa), beta (51 kDa), and gamma (39 kDa) are related nuclear proteins expressed in many or all tissues. TMPO alpha is present diffusely throughout the nucleus, while TMPOs beta and gamma are localized to the nuclear membrane. Here we report the cloning and analysis of a single TMPO gene encoding TMPOs alpha, beta, and gamma, which are produced by alternative mRNA splicing, as previously inferred from cDNA sequences. The eight exons of the TMPO gene are spread over approximately 35 kb. Exon 4, which is spliced into TMPO alpha mRNA, contains sequences that encode a putative basic nuclear localization motif. Exon 8, which is spliced into TMPO beta and gamma mRNAs, encodes a hydrophobic putative membrane-spanning domain that is thought to target TMPOs beta and gamma to the nuclear membrane. TMPO beta appears to be the human homologue of the recently described rat protein LAP2 (lamina-associated polypeptide 2), which is thought to play an important role in the regulation of nuclear architecture by binding lamin B1 and chromosomes in a manner regulated by phosphorylation during mitosis (K. Furukawa and L. Gerace, La Jolla, pers. comm., 22 Nov. 1994). The human TMPO gene maps to chromosome band 12q22.

Amino Acid Sequence↗
PubMed1995

p27Kip1: chromosomal mapping to 12p12-12p13.1 and absence of mutations in human tumors.

The p27Kip1 gene codes for a cyclin-dependent kinase inhibitor implicated in G1 arrest by transforming growth factor beta, cell-cell contact, agents that elevate cyclic AMP, and the growth-inhibitory drug rapamycin. p27 binds to and inhibits complexes formed by cyclin E-cdk2, cyclin A-cdk2, and cyclin D-cdk4. The involvement of p27 in the negative regulation of cell proliferation suggests that it may also function as a tumor suppressor gene. Using a combination of somatic cell hybrid panels and fluorescence in situ hybridization p27Kip1 has been mapped to the short arm of chromosome 12 at the 12p12-12p13.1 boundary, reported to harbor deletions and rearrangements in leukemia and mesotheliomas. In order to assess potential p27Kip1 gene alterations, we have screened a total of 147 human primary solid tumors and found no detectable cancer-specific mutations. These results argue that the often observed loss of antimitogenic transforming growth factor beta responsiveness in human cancer cells is not due to structural defects in p27Kip1.

Base Sequence↗
PubMed1995

Cytogenetics of gastric and esophageal adenocarcinomas. 3q deletion as a possible primary chromosomal change.

We report clonal chromosome abnormalities in short term cultures of seven gastric or esophageal adenocarcinomas and two squamous carcinomas of the esophagus and EG junction. The most consistent aberration encountered was a del(3) (q13.2q23) seen in six of nine tumors. This finding, together with a survey of published cytogenetic literature, suggested that del(3q) is the most common cytogenetic abnormality, and hence possibly of primary significance, in these tumors. In addition to del(3q), rearrangements affecting 1p13 (two cases), 6q15-q23 (two cases), 7p22 (two cases), 7q22 (two cases), and 11p11.2-p14 (three cases) were seen. Cytogenetic evidence for gene amplification in the form of homogeneously staining region (hsr) was seen at 9q13 in two cases.

Adenocarcinoma↗
PubMed1995

Alternative splicing of a 48-nucleotide exon generates two isoforms of the human calcitonin receptor.

A portion of the human calcitonin receptor (hCTR) gene corresponding to the region of the porcine gene at which alternative splicing generates two CTR isoforms was isolated by polymerase chain reaction amplification of placental DNA. In contrast to the porcine CTR gene, in which two acceptor sites in exon 8 are separated by 48 nucleotides, we found a distinct 48-nucleotide exon in the hCTR gene that is present approximately 6400 basepairs from the up-stream exon, which corresponds to porcine exon 7, and approximately 1100 basepairs from the down-stream exon, which corresponds to porcine exon 8. Splicing of this exon accounts for the two isoforms of hCTR, containing or not containing a 16-amino acid insertion in the first putative intracellular loop. A region similar to the intron 7-exon junction in the porcine CTR gene is present in the human gene, but contains four extra nucleotides that shift the reading frame. Using probes derived from these introns in somatic cell and in situ hybridization analyses, we assigned the CTR gene to human chromosome band 7q21.2-q21.3. Thus, human and porcine species have evolved distinct mechanisms to generate two similar CTR isoforms.

Alternative Splicing↗
PubMed1995

Vancomycin for controlling contamination of selective Kirchner's liquid medium in the culture of gastric lavage for tubercle bacilli.

Gastric lavage (GL) was collected for culture of tubercle bacilli from children too young to expectorate sputum. The selective Kirchner's liquid medium (SKLM), routinely used as one of the media for culture of all extrapulmonary specimens, was found to often get contaminated when cultured with GL. We have shown that vancomycin at a concentration of 10 mg/l successfully reduced the contamination from about 60 to 20 per cent, and enhanced the isolation rate of tubercle bacilli from 3 to 6 per cent. Decontamination of the liquid culture before subculture on solid medium also helped to reduce the contamination rate. Vancomycin was found to be an effective selective drug for use in the Kirchner's liquid medium for culture of tubercle bacilli.

Bacteriological Techniques↗
PubMed1995

A direct rifampicin sensitivity test for tubercle bacilli.

A direct sensitivity test for rifampicin has been standardised for early detection of resistance for the mycobacterium tuberculosis smear positive sputum samples. Indirect sensitivity tests set up from primary cultures of the same samples served as controls. The direct test showed 95 per cent agreement with the standard indirect test and as such 74 per cent and 90 per cent of the resistant strains were detected by the fourth week and fifth week, respectively, with an overall gain of 4-5 wks time. Resistance could be detected earlier for multibacillary specimens. This direct sensitivity test on Lowenstein Jensen (LJ) medium offers a feasible alternative for laboratories which lack facilities to perform drug susceptibility tests by the rapid but sophisticated and costly BACTEC method. The method is simple to perform, economic, reliable and amenable to confirmation by the indirect test, if needed.

Drug Resistance, Microbial↗
PubMed1995

Inversion polymorphism in Drosophila ananassae: persistence of inversions, heterosis and intra- and inter-chromosomal associations in experimental populations of mixed geographic origin.

Two experimental populations of D. ananassae were synthesised by making reciprocal crosses among five geographic strains and mixing the hybrids. Each of the two populations of mixed geographic origin was maintained as mass cultures in food bottles. After five generations chromosomal analysis of these two populations was made by squashing a large number of larvae. The results showed that both experimental populations remained polymorphic due to the persistence of AL, (2L), ZE (2R) and DE (3L) inversions in population A and AL, ZE, DE and ET (3R) inversions in population B. Persistence of inversions in considerable frequency and significant deviation from Hardy-Weinberg equilibrium showed that heterosis is associated with these four inversions in D. ananassae. Further, there is non-random association (linkage disequilibrium) between linked inversions in second (AL-ZE) chromosome. However, the inversions of the different chromosomes are associated randomly indicating no interchromosomal interactions in D. ananassae. The results of these studies on population dynamics of inversion polymorphism in experimental populations are attributable to selection, genetic drift and Founder effect.

Animals↗
PubMed1994

Loss of heterozygosity identifies multiple sites of allelic deletions on chromosome 1 in human male germ cell tumors.

Cytogenetic analysis of human male germ cell tumors (GCTs) and derived cell lines revealed frequent deletions and rearrangements of chromosome 1. However, no detailed molecular analysis of these aberrations has thus far been performed. We undertook loss of heterozygosity (LOH) analysis utilizing a panel of 48 GCTs at 22 subregionally mapped polymorphic loci on both arms of chromosome 1. Eight probes, for which precise mapping data were unavailable, were subregionally mapped to specific regions by fluorescence in situ hybridization. Allelic losses were observed in 46% of cases on 1p and in 23% of cases on 1q. Teratomas showed higher frequency of allelic losses compared to embryonal carcinomas, yolk sac tumors, and seminomas, consistent with the results of our previous allelotype analysis, which showed overall higher genetic loss in teratomas compared to embryonal carcinomas. Our LOH study of chromosome 1 identified 4 sites of frequent deletions, 3 in the short arm (1p13, 1p22, and 1p31.3-32.2) and 1 in the long arm (1q32). Of these, 38.5% LOH at 1p22 (D1S16) identifies the site of a novel candidate tumor suppressor gene (TSG), possibly associated with GCTs. LOH at the remaining sites (1p13, 1p31.3-32.2, and 1q32) has also been reported in breast carcinomas, suggesting the involvement of TSGs common to both tumor types.

Alleles↗
PubMed1994

Characterization of the promoter region of the gene for the rat neutral and basic amino acid transporter and chromosomal localization of the human gene.

The promoter region of the rat kidney neutral and basic amino acid transporter (NBAT) gene has been isolated and sequenced. The major transcription initiation site was mapped by primer extension. The entire promoter region and a set of 5' deletions within it were expressed at a high level in LLC-PK1 cells using the luciferase indicator gene. Positive and negative regulatory elements in the promoter region were observed. A human genomic clone of the transporter was also obtained and was used to localize the NBAT gene at the p21 region of chromosome 2.

Amino Acid Sequence↗