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S Pathak

Publications and source records attributed to S Pathak.

At least 37 records · Page 2Linked to original sources
PubMed1998

Reduced telomeric signals and increased telomeric associations in human lung cancer cell lines undergoing p53-mediated apoptosis.

Transduction of a p53-negative H1299 human non-small cell lung cancer cell line with an adenoviral vector containing wild-type p53 (Ad5p53) induced apoptosis. Analysis of the Ad5p53-infected H1299 cells showed high levels of telomeric association prior to apoptotic nuclear fragmentation. Similar telomeric association was observed in stably transfected clones of the wtH226b cell line, which expressed exogenous wild-type p53 protein and also showed complex chromosomal abnormalities including dicentrics, rings and fragments. Fluorescence in situ hybridization (FISH) analysis using a human telomeric DNA probe indicated reductions in telomere signals in both Ad5p53-infected H1299 cells and wtH226b-S cells. In contrast, stably transfected wtH226b-AS clones expressing antisense p53 cDNA showed no telomeric association and had high levels of telomeric signals associated with a faster growing phenotype. These results suggest that wild-type p53 is involved in shortening telomeres, a possibly early event in the p53-mediated apoptotic process and in the subsequent telomeric association that predisposes a cell to genetic instability and DNA fragmentation resulting in apoptotic cell death. Moreover, loss of telomeric signals may indicate a cell's decision to undergo programmed cell death and, if so, could, serve as a sensitive marker of p53-mediated apoptosis.

Adenoviruses, Human↗
PubMed1998

Induction of apoptosis by the N-acetyl-galactosamine-specific toxic lectin from Viscum album L. is associated with a decrease of nuclear p53 and Bcl-2 proteins and induction of telomeric associations.

The ribosome-inhibiting proteins from Viscum album L., i.e. the mistletoe lectins (ML), were recognized to induce apoptosis in various tumour cell lines and human lymphocytes. However, several aspects of ML-induced cell death are unclear. We report that the galNAc-binding ML III incubated with human lymphocytes mediates a very effective death signal resulting in the binding of Annexin-V and expression of mitochondrial membrane proteins Apo2.7, but also in an influx of the DNA intercalating dye propidium iodide. The addition of the ribosome-inhibiting protein Volkensin also induced Apo2.7 molecules, while Momordin, lacking a carbohydrate-binding chain, did not enter the cell membrane and thus did not affect the cells. However, we observed ML III to preferentially affect CD8+ cells with a memory phenotype (CD62L(lo)) as compared to their CD8+ CD62L(hi) counterparts, CD4+ T cells and CD19+ B cells. Furthermore, ML III did not induce sister chromatid exchange-inducing DNA lesions but reduced the intensity of telomeric signals, increased the frequencies of telomeric associations and C-anaphases and reduced nuclear Bcl-2 and p53 proteins. Whatever the exact mechanisms are, our results provide strong evidence that the ML III-mediated cytotoxicity involves distinct killing pathways, i.e. (1) primary cell death via an induction of apoptosis which may not be dependent on protein and/or RNA synthesis and may not involve p53 and Bcl-2 proteins and (2) a loss of telomeres resulting in chromosomal instability in the surviving cells which is incompatible with life. However, we cannot exclude the possibility that this effect is due to a decrease in nuclear p53 proteins.

Apoptosis↗
PubMed1998

Reduction of telomeric signals in murine melanoma and human breast cancer cell lines treated with 3'-azido-2'-3'-dideoxythymidine.

The purpose of this study was to determine, using fluorescence in situ hybridization (FISH), whether treatment of cancer cells with 3'-azido-2'-3'-dideoxythymidine (AZT) has any effect on telomere length as determined by the telomeric signal intensity. To do so, we treated a metastatic murine melanoma cell line (K-1735 clone X-21) and a human breast cancer cell line (MCF-7) with three concentrations of AZT for 72 h at 37ûC. FISH preparations processed using an all-human telomeric DNA probe showed a significantly reduced, concentration-dependent telomeric signal intensity in interphase and metaphase spreads of AZT-treated cells as compared with the signal intensity in untreated controls, which showed no reduction. We conclude from these preliminary results that AZT has the potential of targeting the telomeric ends of chromosomes in cancer cells and promoting cell death and could well be tested along with other chemotherapy drugs given to cancer patients for this purpose.

Animals↗
PubMed1998

Accuracy of clinical manoeuvres in detection of minimal ascites.

A study was conducted to assess the clinical accuracy of various clinical manoeuvres and signs used routinely for detection of ascites. Sixty-six patients admitted in medical ward of a teaching hospital after initial screening by a consultant were selected. Exclusion criteria were; cases with previous history of ascites, who had undergone paracentesis in the recent past or with evidence of ascites from history. Another clinician blind to history and clinical details assessed the presence of ascites by the selected methods a sonographer blind of clinical and historical details assessed the cases for presence of ascitic fluid. The clinical findings were compared using ultrasonographic (USG) findings as gold standard. Ascites was detected in 35 patients by USG. the mean weight and abdominal girth of study subjects with or without ascites were comparable (p > 0.05). Sensitivity of auscultatory percussion was highest (65.7%) followed by flank dullness (57.1%) and least for fluid wave sign (20.0%). Fluid wave sign had the highest specificity (100%). We found that none of the manoeuvres studied for detection of ascites was both highly sensitive and specific. However, auscultatory percussion could be useful for initial screening of patients to detect ascites.

Adult↗
PubMed1998

DNA repair and mutagen sensitivity in patients with triple primary cancers.

The purpose of this study was to measure DNA repair capacity and mutagen sensitivity in patients who have had three or more primary forms of cancer. It was hypothesized that, if abnormalities in DNA repair and mutagen sensitivity were cancer susceptibility factors, such findings would be seen with regularity in individuals with multiple primary cancers. DNA repair capacity was measured by determining repair of UV-irradiated plasmid DNA (pCMVCAT) transfected into peripheral blood lymphocytes. Results from 18 patients and a like number of age- and sex-matched controls demonstrated a significant difference in DNA repair capacity (P < 0.0001; odds ratio = 14). Mutagen sensitivity was measured by determining the mean number of chromatid breaks per cell after in vitro exposure to either bleomycin or 4-nitroquinoline-1-oxide. The difference in mean bleomycin- or 4-nitroquinoline-1-oxide-induced mutagen sensitivity between cases and controls was not statistically significant. Fourteen of the 18 patients had positive family histories of cancer; in 10, the history was compatible with cancer susceptibility syndromes. Although the numbers were small, there was no suggestion in this study that treatment or the presence of cancer was the cause of the DNA repair abnormalities encountered. These findings support the concept of diminished DNA repair capacity as an underlying feature in the development of a mutator phenotype.

4-Nitroquinoline-1-oxide↗
PubMed1998

Amplification of telomeric DNA and the extent of karyotypic evolution.

The distribution of telomeric DNA in the genomes of the antelope ground squirrel, Ammospermophilus harrisii (family Sciuridae; 2n = 32) and the African black-footed cat, Felis nigripes (family Felidae; 2n = 38) were compared by fluorescence in situ hybridization (FISH) technique. These two mammalian species have the highest and the lowest amount of C-banded regions, respectively. FISH preparations with the human telomeric DNA probe showed that all C-banded segments in the A. harrisii chromosomes, except a few intercalary segments, were hybridizing with this DNA. F. nigripes showed hybridization only on the termini of each chromosome, and the C-banded regions did not hybridize with telomeric DNA on FISH analysis. The C-banded chromosomal arms in another rodent species, Peromyscus eremicus (family Cricetidae; 2n = 48), when hybridized with human telomeric DNA showed signals only in the termini of chromosomes but not in the heterochromatic arms. These observations indicate that not all C-banded regions in rodent species are telomeric DNA. The amplification of telomeric DNA in relation to speciation is discussed.

Animals↗
PubMed1997

Increasing metastatic potential is associated with induced chromosome 14 translocations in a previously nonmetastatic murine melanoma cell line.

The purpose of these studies was to demonstrate causal effects of abnormalities induced in mouse chromosome 14 on tumorigenicity and metastasis using the K-1735 murine melanoma cell line. Because anomalies in chromosome 14 have previously been associated with increases in metastatic potential, we induced chromosome 14 anomalies in a nonmetastatic K-1735 clone 10 cells initially containing two normal copies of chromosome 14 by treatment with mitomycin C. Clone 10-M1, in which a small population of cells (approximately 4%) contained translocations involving chromosome 14, was isolated and injected into athymic nude mice. Unlike the parental C-10 cells, C-10 M1 cells produced experimental lung metastases. Chromosomal analysis of cell cultures established from both subcutaneous tumors and lung metastases indicated that approximately 35% of the cell population contained chromosome 14 anomalies suggesting that this chromosome may play a role in tumor growth and metastasis.

Animals↗
PubMed1997

Low-level c-myc amplification in human colonic carcinoma cell lines and tumors: a frequent, p53-independent mutation associated with improved outcome in a randomized multi-institutional trial.

Human colonic cancer is associated with multiple genetic deletions, mutations, and alterations in gene expression; in contrast, gene amplification has not been recognized as a prominent characteristic of human colonic tumors. Although the c-myc gene is overexpressed in approximately 70% of human colonic cancers, previous studies have not detected frequent gene amplification or rearrangement of c-myc in these tumors, although such amplification has been reported in chemically induced rodent colon cancer and quantitative analysis of gene copy number has shown the gene to be amplified at a low level in mucinous and poorly differentiated human colon carcinomas. Using rigorously controlled blot methodology, we have established that the c-myc gene, located at 8q21, exhibited amplification of 87% to 35-fold in 7 of 10 human colonic carcinoma cell lines. This was highly significant even at a low level of amplification in HT29 cells (P < 0.0001). Cytogenetic analysis by G-banding did not detect aneuploidy involving chromsome 8q, suggesting that the amplification for the c-myc gene on 8q was relatively specific, and this was consistent with a lack of amplification detected for the c-mos gene on 8q24, which was assayed similarly. The same methodology then revealed amplification of c-myc from 1.5-fold to 5-fold in 32% of tumors from 149 patients entered into a multi-institutional Phase III study of adjuvant therapy for colon cancer. c-myc status was not related to time to recurrence or death, but low levels of c-myc amplification identified a subset of patients who showed a statistically significant increase in disease-free survival, and a corresponding trend to longer overall survival, in response to adjuvant therapy with 5-fluorouracil plus levamisole. Presence of c-myc amplification was not related to incidence of p53 mutations.

Carcinoma↗
PubMed1997

Lung carcinoma patients with a family history of cancer and lymphocyte primary chromosome 9 aberrations.

BACKGROUND: Deletion of chromosome 9p has been reported in numerous tumor types. The authors demonstrated in an earlier study that spontaneous chromosome aberrations on chromosome 9 in peripheral blood lymphocytes (PBLs) were a significant risk predictor for lung carcinoma. METHODS: The current study evaluated the relationship between self-reported family history of cancer and spontaneous chromosome aberrations in the PBLs of 97 previously untreated lung carcinoma patients. The authors' hypothesis was that individuals exhibiting specific chromosome aberrations might have inherited genetic instability and thus be more likely to report a family history of cancer. For each individual, a personal interview was conducted to construct a detailed family history, and 100 metaphases from PBLs were analyzed for spontaneous aberrations by G-banding. RESULTS: The patients reported having 829 first-degree relatives, including 74 (8.9%) with cancer. A significantly elevated odds ratio (OR) of 2.7 was noted in smokers for having chromosome 9 aberrations and a first-degree relative with cancer. When the family history of cancer was dichotomized into lung carcinoma or other cancers, the OR associated with chromosomal aberrations was 8.5 for lung carcinoma but only 2.3 for other cancers. In addition to chromosome 9 aberrations, other spontaneous chromosome aberrations and family history of cancer were also evaluated, but no associations were found. There were no associations between age, gender, ethnicity, or smoking status and the chromosome 9 aberration profile. CONCLUSIONS: The findings of this study suggest that chromosome 9 aberrations may be a marker of cancer susceptibility and may be associated with familial aggregation of cancer.

Black People↗
PubMed1997

Can cancer cells transform normal host cells into malignant cells?

A human prostate tumour cell line, LNCaP C4-2, when injected into athymic male nude mice, produced tumours containing: (1) only human cancer cells similar to those injected; (2) only murine stromal cells containing abnormal chromosome constitutions; or (3) both human prostate cancer cells similar to those injected and the transformed murine stromal cells with altered chromosome constitutions. Karyotypic analysis of murine metaphases from all the host-derived tumours showed mostly pseudodiploid chromosome constitutions, with multiple copies (amplification) of mouse chromosome 15 and the absence of a typical Y chromosome. Fluorescence in situ hybridization analysis of these murine cells, using a biotin-labelled total human DNA painting probe, further demonstrated the absence of human DNA and the presence of only mouse metaphase and interphase cells in these transformed stromal cells. These results suggest that cancer cells are capable of inducing neoplastic transformation in stromal cells of the host organ by some, as yet unknown, epigenetic mechanism(s).

Animals↗
PubMed1997

Specific histologic and cytogenetic evidence for in vivo malignant transformation of murine host cells by three human prostate cancer cell lines.

The chromosomal constitutions of three murine cell lines that developed in vitro from tumors that grew in nude mice after orthotopic and ectopic injections of three human prostate tumor cell lines were examined by histopathology, conventional G-banding, and with fluorescence in situ hybridization techniques. All three murine cell lines showed unique marker chromosomes involving mouse chromosome 12, with a common break point. Histopathologic evidence from a murine prostate gland into which SP 3031 cells had been injected indicated dysplastic glandular epithelium and carcinomatous areas. These observations further indicate that: (a) human prostate tumors are capable of transforming host organ cells, (b) host cells have specific chromosomal alterations that may be associated with transformation, and (c) the process of host cell transformation can be demonstrated in histological sections. Although cancer cell heterogeneity and drug-resistant phenotypes are caused by additional genetic alterations and clonal evolution of the original tumor, transformation of the host's distant organ cells may also contribute because most therapies are directed only to the original cancer cells.

Animals↗
PubMed1997

Accuracy of palpation and percussion manoeuvres in the diagnosis of splenomegaly.

A study was conducted on 80 patients admitted in a teaching hospital to see the accuracy of two palpatory methods (Supine palpation and Middleton's manoeuvre) and three percussion methods (Traube's space percussion, Castell's and Nixon's manoeuvres) in the diagnosis of splenomegaly. Ultrasonographic findings were considered as gold standard for diagnosing splenomegaly. Mean age of study subjects was 31.5 years and mean Quetelet's index was 17.8 +/- 2.6 kg/m2. Sensitivity of Middleton's and Castell's manoeuvres was similar (85.7%) and higher than other manoeuvres. Nixon's manoeuvre had the least sensitivity (66.7%). Specificity was highest (92.1%) with supine palpation and least (31.6%) with Castell's manoeuvre. Supine palpation showed highest positive predictive value (91.7%). Receiver Operating Characteristics curves showed greater area with middleton's manoeuvre (0.93) followed by supine palpation (0.92), Castell's manoeuvre (0.75) and Traube's space percussion (0.74), the findings of the study suggests that palpatory methods like Middeton's manoeuvre and Supine palpation should be routinely used for diagnosing splenomegaly among non-obese individuals.

Adolescent↗
PubMed1997

Interobserver variations in clinical signs for diagnosis of pleuritis.

A study was conducted on 150 patients admitted in a teaching hospital to find out reliable clinical signs for diagnosing pleuritis. Cases were selected based on suspicion of pleural involvement by history and examination. Final diagnosis was made by correlations with radiographic and ultrasonographic reports. Reliability of the signs was determined on the basis of high concordance of independently observed variations between two medical consultants. Inflammatory involvement of pleura was seen in 69.3% cases and 30.7% were due to oedema disorders. Concordance between observers was high for crepitations (95.5%) and pleural rub (93.8%) followed by vocal resonance (87.6%), dull percussion note (76.9%) and mediastinal shift (76.9%).

Adult↗
PubMed1997

Establishment of two human prostate cancer cell lines derived from a single bone metastasis.

Human prostate cancer cell lines are particularly difficult to establish, and most existing cell lines do not exhibit features commonly seen in human prostate cancer. Most available models either grow only in vivo as xenografts or are androgen insensitive and fail to express prostate-specific antigen (PSA). The lack of functionally relevant model systems of advanced prostate cancer has limited prostate cancer research and therapy development. Of 30 processed samples derived from patients with prostate cancer, we established two cell lines (MDA PCa 2a and MDA PCa 2b) that express PSA and androgen receptor, grow in vitro, and are androgen sensitive. Cells from these lines produced tumors in nude mice when injected either s. c. or orthotopically (intraprostatic). Both cell lines were established from a bone metastasis of a patient whose cancer was exhibiting androgen-independent growth. Although both were derived from two samples of the same specimen, they have different genetic features (as assessed by karyotype analysis) and different phenotypes (e.g., morphology and growth rate). It is likely that they are distinct clones isolated by the use of different culture procedures and reflect the genetic heterogeneity of the tumor. These new cell lines are the first available derived from a bone metastasis of an androgen-independent prostatic adenocarcinoma that grow both in vivo and in vitro and have retained PSA expression and androgen sensitivity. They therefore constitute important model systems to address critical questions related to the androgen-independent growth of human prostate cancer and to the complex process of bone metastasis.

Androgens↗
PubMed1996

Three siblings with Harlequin Ichthyosis in an Indian family.

The Harlequin fetus is a distinct genetic entity with a strikingly grotesque appearance. Three siblings (two males, one female) with Harlequin Ichthyosis, a rare form of congenital disorder, born to the same parents are presented. The genetic aspects are discussed and the relevant literature is reviewed.

Abnormalities, Multiple↗
PubMed1996

Predominance of the metastatic phenotype in hybrids formed by fusion of mouse and human melanoma clones.

The fusion of mouse and human melanoma cells that were tumorigenic but had different metastatic capabilities resulted in hybrids that were metastatic when injected intravenously or subcutaneously into nude mice, regardless of whether it was the mouse or the human melanoma clone that was metastatic. The H7 hybrid line, formed by fusing murine nonmetastatic K1735 C19 cells with human metastatic A375 C15 cells retained high metastatic potential over more than 50 sub-culture passages, suggesting that the dominant metastatic phenotype in these hybrid cells was stable. Using fluorescent in situ hybridization (FISH), human chromosome 17 was consistently identified as the predominant human chromosome in the majority of H7 cells tested between passages 20 and 60. Western blot analysis showed that the hybrid cells expressed human nm23 protein, indicating that at least one gene on the human chromosome 17 was functional. Immunocytochemistry and immunoprecipitation showed that the metastatic A375 C15 and H7 cells expressed p53 protein, but that the nonmetastatic K1735 C19 melanoma cells did not. Sequencing the human p53 gene in A375 C15N and H7 showed mutations in exon 7. Using a bioassay technique, we showed that K1735 C19 cells can spread from subcutaneous tumors to the lungs of nude mice yet fail to form metastases. With the addition of human chromosome 17 from A375 C15 cells, which carries a mutant p53 gene, the cells readily formed lung metastases. In this melanoma hybrid, a mutant p53 gene appears to confer a survival advantage on cells arrested in the lungs of nude mice and thus contributes to the growth of metastatic cells.

Animals↗