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Biomedical subjects

S C Krishnamurthy

Publications and source records attributed to S C Krishnamurthy.

At least 19 recordsLinked to original sources
PubMed2001

Enhanced sequential expression of G1/S cyclins during experimental epatocarcinogenesis and tyrosine phosphorylation.

It is now widely accepted that cancer development is a multistage process, starting from the original cell population and ending with a malignant tumor. However, the mechanisms involved in the progressive growth of cells from normalcy to preneoplasia, and from preneoplasia to malignancy are not clear. Because tyrosine phosphorylation and dephosphorylation reactions are known to play critical roles during normal and abnormal cellular growth, we have studied the tyrosine phosphorylation, tyrosine phosphorylated proteins, and protein phosphatases during the sequential development of liver cancer. The present investigation indicated that enhanced tyrosine phosphorylation and tyrosine phosphorylated proteins, with no change in the levels of tyrosine protein phosphatases may contribute to abnormal cellular proliferation during liver carcinogenesis. We have also seen an increase in the expression of proliferating cell nuclear antigen and G1/S cyclins during tumor development.

Animals↗
PubMed2001

Effect of metanil yellow and malachite green on DNA synthesis in N-nitrosodiethylamine induced preneoplastic rat livers.

Metanil yellow (MY) and malachite green (MG) are textile dyes, which, despite the ban occurs unsrupulously as food colouring agents. Accordingly they constitute a serious public health hazard and are of sufficient environmental concern. We have earlier reported that both MY and MG have tumor enhancing effects on the development of hepatic preneoplastic lesions induced by N-nitrosodiethylamine in rats. In order to understand the possible mechanisms by which MY and MG enhance tumor development, in this study we have tested the effects of MY and MG on DNA synthesis and PCNA expression in preneoplastic hepatic lesions during N-nitrosodiethylamine (DEN) induced hepatocarcinogenesis in male Wistar (WR) rats. Rats were administered 200 ppm DEN through drinking water for a period of one month. Administration of DEN for a period of one month showed an upregulation of cell cycle regulatory proteins namely cyclin D1, CDK4, cyclin E and CDK2. Accordingly, in other experiments, the animals were further administered MY and MG for a period of one month following one month DEN treatment. The effects of MY and MG were monitored on the basis of cell proliferation markers--DNA synthesis and PCNA expression both by immunohistochemical and immunoblotting. Following DEN administration, MY, MG and PB showed stimulation of DNA synthesis and increased PCNA expression when compared with either the corresponding controls or only DEN treated animals. In the present study, enhancing effect of MY, MG and PB on the cell proliferation markers during DEN-induced hepatic preneoplasia in rats was observed.

Animals↗
PubMed2000

Overexpression of G1/S cyclins and PCNA and their relationship to tyrosine phosphorylation and dephosphorylation during tumor promotion by metanil yellow and malachite green.

Metanil yellow (MY) and Malachite green (MG) are textile dyes, which, despite the ban, occur unscrupulously as food colouring agents. Accordingly they constitute a serious public health hazard and are of sufficient environmental concern. We have earlier reported that both MY and MG have tumor promoting effects on the development of hepatic preneoplastic lesions induced by N-nitrosodiethylamine in rats. In order to understand the possible mechanism(s) by which metanil yellow (MY) and malachite green (MG) promotes liver tumor development, we have studied the tyrosine phosphorylation and protein phosphatases during tumor promotion. We have also investigated the possible overexpression of G1/S cyclins and PCNA during tumor promotion by MY and MG. The present investigation indicates that enhanced tyrosine phosphorylation is associated with no change in levels of tyrosine protein phosphatases. We have also observed an increase in the expression of PCNA and G1/S cyclins during tumor promotion. These factors collectively may contribute to the abnormal cell proliferation during tumor promotion by MY and MG.

Animals↗
PubMed1998

Loss of a putative novel growth inhibitory apoptotic 14 kD polypeptide during progression of rat liver carcinogenesis.

Carcinogenesis is a multistep process involving different stages. However, the biological and biochemical factors responsible for the stepwise transition of cells from one stage to the other remains as important enigmas even today. We have recently isolated a putative novel growth inhibitory apoptotic 14 kD polypeptide from normal rat liver. In order to understand the possible functional relationship between 14 kD polypeptide and liver carcinogenesis, the sequential expression of this polypeptide as a function of tumor progression was studied in the rat liver using diethylnitrosamine (DEN) as a carcinogen. Immunoperoxidase and immunoblotting experiments using polyclonal rabbit antisera revealed a gradual reduction in the levels of this polypeptide with tumor progression. No reduction in the levels of this polypeptide was observed in regenerating rat liver after partial hepatectomy. The findings suggest that the loss or reduction of 14 kD polypeptide is linked selectively to abnormal cell proliferation and appears to be a biologically relevant risk factor for the progression of hepatocarcinogenesis in rats.

Animals↗
PubMed1996

Primary carcinoid tumor of the liver: report of four resected cases including one with gastrin production.

Four cases of primary hepatic carcinoid were identified during a retrospective study of liver resections for primary tumor. The cases included two adult males, one adult female, and a 9-year-old boy in whom gastrin levels were documented. The estimation of gastrin levels was prompted by symptoms suggestive of acid-peptic disease. One patient died postoperatively. The other three are alive and well at 3 years, 2 years, and at 1 year, respectively, after surgery, outcomes distinctly different from hepatocellular carcinomas. Diagnostic difficulties may be experienced in histologic assessment, and this may require recourse to immunohistochemistry and electron microscopy. Long-term follow-up and careful exclusion of a possible primary elsewhere are necessary for establishing the primary nature of liver carcinoids.

Adult↗
PubMed1993

Differential distribution of inhibin in the anatomical regions of monkey stomach.

Inhibin, a 10.7 kD FSH (follicle-stimulating hormone) suppressing prostatic peptide has been shown to be synthesized and localized in stomach specimen of monkey. In vitro incorporation of labelled amino acid (3H-leucine) into inhibin followed by specific immunoprecipitation by antiserum to inhibin demonstrated an in vitro de novo biosynthesis of inhibin by monkey stomach. Moreover, the synthesis of inhibin was found to be maximum in fundic zone of gastric mucosa compared to cardiac and antral zone. This was supported by immunohistochemical study of three anatomically different regions, especially wherein fundic zone showed intense positive staining for inhibin. Furthermore, the above data was supplemented by quantitative study of tissue inhibin content by RIA which revealed that the fundic zone of gastric mucosa has a much higher concentration of inhibin than cardiac and antral region. The relationship of zonal concentration of inhibin to gastric anatomy appears to be a noteworthy observation and may serve as an useful tool in our understanding of gastric metabolism and activity.

Animals↗
PubMed1993

Heterotopic ossification in colorectal adenocarcinoma [corrected].

Heterotopic ossification in Adenocarcinomas of the colon is uncommon. The clinical presentation of these patients is similar to those without osseous metaplasia. Its importance lies in the fact that it may be misdiagnosed for a carcinosarcoma. Which has a poorer prognosis. These two cases are reported because of its rarity.

Adenocarcinoma↗
PubMed1993

Intraoperative fine needle aspiration cytology of pancreas: a study of 97 cases.

Intraoperative fine needle aspiration cytology (FNAC) for pancreatic and ampullary lesions was carried out under direct vision using transduodenal approach in 97 patients. Cytological findings were classified as follows: positive for malignancy, suspicious for malignancy, benign (normal) cells from duodenum or pancreas, inflammatory and non-representative smears. Suboptimal smears (non-representative, suspicious and inflammatory) were excluded for calculating decision analysis values. Sensitivity for malignancy was 90.5% and specificity 100%. Positive and negative predictive values were 100% and 50% respectively. We conclude that intraoperative FNAC is useful in diagnosing malignant lesions of the pancreas.

Biopsy, Needle↗
PubMed1992

Intrahepatic cholangiocarcinoma: report of a surgically resected case.

We report a middle aged female with intrahepatic cholangiocarcinoma which was resected successfully. Because of an unusual histology, a microscopic diagnosis could not be established pre-operatively. The tumor recurred locally 21 months after surgery. The case is reported mainly for the diagnostic problems it created.

Adenoma, Bile Duct↗
PubMed1991

Familial polyposis coli with villous adenoma of ampulla of Vater.

Adenoma of the ampulla of Vater is one of the extracolonic manifestations of familial polyposis coli (FPC). We report three patients with FPC in whom villous adenoma of the ampulla was detected. An adenoma carcinoma sequence has been suggested in such lesions.

Adenoma↗
PubMed1990

Extra-adrenal non-functioning paraganglioma.

Extra-adrenal non-functioning retroperitoneal paragangliomas are rare tumors. We herein report a case of retroperitoneal tumor which posed a diagnostic and management problem. Review of the literature shows only 16 previously reported cases of extra-adrenal paraganglioma which underwent complete surgical excision.

Adult↗
PubMedDate not supplied

Fine needle aspiration cytology of undifferentiated (embryonal) sarcoma of the liver: a case report.

BACKGROUND: Undifferentiated sarcoma of the liver is a rare tumor of childhood. The histology has been well documented, but the histogenesis is controversial. The cytologic characteristics of this neoplasm in aspiration material have not been previously documented. CASE: The cytologic features in a 9-year-old male were pleomorphic malignant cells, multinucleate giant cells, numerous hyaline globules and myxoid matrix. CONCLUSION: The cytologic features of undifferentiated sarcoma of the liver are distinctive and different from those of other childhood liver tumors. Awareness of the tumor's cytomorphology can result in a confident preoperative diagnosis.

Biopsy, Needle↗
PubMedDate not supplied

Intra-abdominal follicular dendritic cell tumor: report of two cases.

Follicular dendritic cell (FDC) tumor is an uncommon entity described mainly in the lymph nodes. We report two men with intra-abdominal FDC tumors--one arising from the colon and other presenting as a mesenteric mass. Both patients underwent successful surgical excision of the tumor.

Abdominal Neoplasms↗