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Biomedical subjects

P Kumar

Publications and source records attributed to P Kumar.

At least 91 records · Page 5Linked to original sources
PubMed2001

Trichloroethylene induced testicular toxicity in rats exposed by inhalation.

Trichloroethylene (TCE) is an organic solvent used in dry cleaning, metal degreasing, thinner for paints and varnishes, anesthetic agent, and so forth. Human beings are appreciably exposed to TCE vapours by inhalation route. The present study has been undertaken to investigate whether TCE inhalation may also bring about testicular toxic effects. Our results indicate that inhalation of TCE by male rats for 12 and 24 weeks brings about significant reduction in absolute testicular weight, and alters marker testicular enzymes activity associated with spermatogenesis and germ cell maturation, along with marked histopathological changes showing depletion of germs cells and spermatogenic arrest.

Animals↗
PubMed2001

Human cyclophilin 40 is a heat shock protein that exhibits altered intracellular localization following heat shock.

The unactivated steroid receptors are chaperoned into a conformation that is optimal for binding hormone by a number of heat shock proteins, including Hsp90, Hsp70, Hsp40, and the immunophilin, FKBP52 (Hsp56). Together with its partner cochaperones, cyclophilin 40 (CyP40) and FKBP51, FKBP52 belongs to a distinct group of structurally related immunophilins that modulate steroid receptor function through their association with Hsp90. Due to the structural similarity between the component immunophilins, FKBP52 and cyclophilin 40, we decided to investigate whether CyP40 is also a heat shock protein. Exposure of MCF-7 breast cancer cells to elevated temperatures (42 degrees C for 3 hours) resulted in a 75-fold increase in CyP40 mRNA levels, but no corresponding increase in CyP40 protein expression, even after 7 hours of heat stress. The use of cycloheximide to inhibit protein synthesis revealed that in comparison to MCF-7 cells cultured at 37 degrees C, those exposed to heat stress (42 degrees C for 3 hours) displayed an elevated rate of degradation of both CyP40 and FKBP52 proteins. Concomitantly, the half-life of the CyP40 protein was reduced from more than 24 hours to just over 8 hours following heat shock. As no alteration in CyP40 protein levels occurred in cells exposed to heat shock, an elevated rate of degradation would imply that CyP40 protein was synthesized at an increased rate, hence the designation of human CyP40 as a heat shock protein. Application of heat stress elicited a marked redistribution of CyP40 protein in MCF-7 cells from a predominantly nucleolar localization, with some nuclear and cytoplasmic staining, to a pattern characterized by a pronounced nuclear accumulation of CyP40, with no distinguishable nucleolar staining. This increase in nuclear CyP40 possibly resulted from a redistribution of cytoplasmic and nucleolar CyP40, as no net increase in CyP40 expression levels occurred in response to stress. Exposure of MCF-7 cells to actinomycin D for 4 hours resulted in the translocation of the nucleolar marker protein, B23, from the nucleolus, with only a small reduction in nucleolar CyP40 levels. Under normal growth conditions, MCF-7 cells exhibited an apparent colocalization of CyP40 and FKBP52 within the nucleolus.

Arsenites↗
PubMed2001

Regulation of the Hsp90-binding immunophilin, cyclophilin 40, is mediated by multiple sites for GA-binding protein (GABP).

Within steroid receptor heterocomplexes the large tetratricopeptide repeat-containing immunophilins, cyclophilin 40 (CyP40), FKBP51, and FKBP52, target a common interaction site in heat shock protein 90 (Hsp90) and act coordinately with Hsp90 to modulate receptor activity. The reversible nature of the interaction between the immunophilins and Hsp90 suggests that relative cellular abundance might be a key determinant of the immunophilin component within steroid receptor complexes. To investigate CyP40 gene regulation, we have isolated a 5-kilobase (kb) 5'-flanking region of the human gene and demonstrated that a approximately 50 base pair (bp) sequence adjacent to the transcription start site is essential for CyP40 basal expression. Three tandemly arranged Ets sites within this critical region were identified as binding elements for the multimeric Ets-related transcription factor, GA binding protein (GABP). Functional studies of this proximal promoter sequence, in combination with mutational analysis, confirmed these sites to be crucial for basal promoter function. Furthermore, overexpression of both GABP alpha and GABP beta subunits in Cos1 cells resulted in increased endogenous CyP40 mRNA levels. Significantly, a parallel increase in FKBP52 mRNA expression was not observed, highlighting an important difference in the mode of regulation of the CyP40 and FKBP52 genes. Our results identify GABP as a key regulator of CyP40 expression. GABP is a common target of mitogen and stress-activated pathways and may integrate these diverse extracellular signals to regulate CyP40 gene expression.

5' Untranslated Regions↗
PubMed2001

M cells and associated lymphoid tissue of the equine nasopharyngeal tonsil.

The aim of this study was to characterise the morphological and histochemical features of equine nasopharyngeal tonsillar tissue. Nasal and oropharyngeal tonsillar tissue has been described as the gatekeeper to mucosal immunity because of its strategic location at the entrance to the respiratory and alimentary tracts. A combination of light, scanning and transmission electron microscopy has revealed the presence of follicle-associated epithelium (FAE) overlying lymphoid tissue of the equine nasopharyngeal tonsil caudal to the pharyngeal opening of the guttural pouch. Membranous microvillus (M) cells were identified in the FAE on the basis of short microvilli, an intimate association with lymphocytes, cytoplasmic vimentin filaments and epitopes on the apical surface reactive with lectin GS I-B4 specific for alpha-linked galactose. CD4-positive lymphocytes were scattered throughout the lamina propria mucosae as well as forming dense aggregates in the subepithelial part. The central follicular area was heavily populated with B lymphocytes and the dome and parafollicular areas contained both CD4- and CD8-positive lymphocytes. CD8-positive lymphocytes were also present in the epithelium and, together with B lymphocytes, in small numbers in the lamina propria mucosae. These observations indicate that the nasopharyngeal tonsil is potentially an important mucosal immune induction site in the horse and an appropriate target for intranasally administered vaccines.

Animals↗
PubMed2001

State-of-the-art prostate cancer treatment and research. A report from the Cancer Institute of New Jersey.

Prostate cancer is a devastating disease that will be diagnosed in approximately 200,000 men in 2001. New methods for screening, prevention, and treatment are being developed. In addition, novel agents for the treatment of resistant prostate cancer are being developed in clinical trials. This review summarizes the recent efforts in diet, screening, novel systemic therapies, and alternative medicine for prostate cancer.

Adult↗
PubMed2001

Mumps with cerebellar encephalitis.

A 30 years male patient, having typical symptoms of mumps, presented with acute cerebellar ataxia two days after the onset of parotid enlargement. The neurological symptoms showed complete recovery over the subsequent six weeks, suggestive of para-infectious cerebellar demyelination due to mumps.

Adult↗
PubMed2001

Light and electron microscope studies on the nasopharynx and nasopharyngeal tonsil of the horse.

Light and electron microscope studies were conducted on the nasopharynx and the nasopharyngeal tonsil of 15 young horses. The nasopharynx and nasopharyngeal tonsil was lined with pseudostratified columnar ciliated epithelium and goblet cells. The lymphoepithelium of the nasopharyngeal tonsil was folded forming crypts, the mucosa of which was modified into follicle associated epithelium characterized by stratified cuboidal epithelium, loss of cilia, absence of goblet cells and infiltration of lymphocytes. The lamina propria mucosae of the nasopharyngeal tonsil contained well-developed lymphoid tissue and clusters of seromucus acini. Scanning electron-microscopy revealed a dense mat of cilia covering the nasopharynx and nasopharyngeal tonsil. The follicle-associated epithelium consisted of different populations of microvillus cells in addition to M cells with very short microvilli and a few squamous and intermediate cells. Microvillus cells in the deeper part of the FAE had larger microvilli and their cytoplasm contained a dense population of mitochondria, smooth and rough endoplasmic reticulum, Golgi complexes and lysosomes. The flat surfaced M cell had a more electron-dense cytoplasm and contained small supranuclear vacuoles in addition to the organelles seen in microvillus cells.

Adenoids↗
PubMed2001

Comparative functional characterization of mouse bone marrow-derived mast cells and peritoneal mast cells in response to non-immunological stimuli.

The cultured mouse mast cells that are dependent on spleen-derived factor for their proliferation and maintenance and have been shown to be similar to mucosal mast cells in terms of their T-cell dependence and histochemical staining characteristics. Mast cell heterogeneity has been confirmed by functional characterization of mouse bone marrow-derived mast cells (MBMMC) and mouse peritoneal mast cells (MPMCs). MPMCs released around 30% of histamine when stimulated with compound 48/80 whereas MBMMC were almost unresponsive to the same stimulus. Calcium Ionophore A23187 on the other hand, released histamine in dose-dependent manner from MBMMC. The study was undertaken to investigate the effect of antiallergic drug, disodium cromoglycate (DSCG), a synthetic cromone and quercetin, a plant-derived flavonoid on Ca ionophore A23187 induced histamine release from MBMMC. MBMMCs were almost unresponsive to DSCG whereas Ca Ionophore induced histamine release was blocked by Quercetin. The results indicate that response of mast cells at one anatomic site to a given stimulus does not necessarily predict the response of mast cells at a different anatomic location to the same stimulus. It shows functional heterogeneity within a single species. So, it cannot be assumed that antiallergic compounds stabilizing mast cells in one tissue site or organ will be equally efficacious against mast cells in other sites.

Animals↗
PubMed2001

Increased hepatic VLDL secretion, lipogenesis, and SREBP-1 expression in the corpulent JCR:LA-cp rat.

The corpulent JCR:LA-cp rat (cp/cp) is a useful model for study of the metabolic consequences of obesity and hyperinsulinemia. To assess the effect of hyperinsulinemia on VLDL secretion in this model, we measured rates of secretion of VLDL in perfused livers derived from cp/cp rats and their lean littermates. Livers of cp/cp rats secreted significantly greater amounts of VLDL triglyceride and apolipoprotein, compared with lean littermates. The content of apoB, apoE, and apoCs in both perfusate and plasma VLDL was greater in the cp/cp rat, as was the apolipoprotein (apo)C, apoA-I, and apoA-IV content of plasma HDL. Triglyceride content was also greater in cp/cp livers, as was hepatic lipogenesis and expression of lipogenic enzymes and sterol regulatory element binding protein-1 (SREBP-1). Hepatic mRNAs for apoE, and apoA-I were higher in livers of cp/cp rats. In contrast, the steady state levels of apoC-II, apoC-III, and apoB mRNAs were unchanged. Thus, livers of obese hyperinsulinemic cp/cp JCR:LA-cp rats secrete a greater number of VLDL particles that are enriched in triglyceride, apoE, and apoC. Greater secretion of VLDL in the cp/cp rat in part results from higher endogenous fatty acid synthesis, which in turn may occur in response to increased expression of the lipogenic enzyme regulator SREBP-1c.

Animals↗
PubMed2001

Hepatoxic alterations induced by inhalation of trichlorethylene (TCE) in rats.

OBJECTIVE: Trichlorethylene (TCE) is one of the most potent organic unsaturated solvents being used in dry cleaning, metal degreasing, thinner for paints varnishes and electroplating, etc. and has been reported to be a hepatoxicant through oral and dermal exposure. However, its inhalation toxicity data is very limited in the literature due to the fact that the exposure levels associated with these effects were usually not reported. Hence, inhalation toxicity study was carried out for hepatotoxic studies. METHODS: Inhalation toxicity studies was carried out by exposing rats to TCE for 8, 12 and 24 weeks in a dynamically operated whole body inhalation chamber. Sham treated control rats were exposed to compressed air in the inhalation chamber for the same period. RESULTS: Significant increase in liver weight (liver enlargement) appeArance of necrotic lesion with fatty changes and marked necrosis were observed after longer duration (12 and 24 weeks) of TCE exposure. The lysosomal rupture resulted in increased activity of acid and alkaline phosphatase alongwith reduced glutathione content and total increased sulfhydryl content in liver tissue. CONCLUSION: TCE exposure. through inhalation route induces hepatotoxicity in terms of marked necrosis with fatty changes and by modulating the lysosomal enzymes.

Animals↗
PubMed2001

Pulmonary toxicity of a formulated preparation of fenvalerate in rats subchronically exposed by nose only inhalation for 90 days.

OBJECTIVE: The pulmonary toxicity of a commercially available formulated preparation of Fenvalerate (Fen), a synthetic pyrethroid has been studied in rats following subchronic nose only inhalation exposure route. METHOD: Adult male rats were exposed to Fen for 4 h/day, 5 days a week for 90 days by using Flow Past Dynamic Nose only Inhalation Chamber. RESULTS: Fen exposed rats showed a significant increase in enzymatic activities of lactate dehydrogenase (LDH), acid phosphatase (ACP), alkaline phosphatase (ALP) and gamma-glutamyl transferase (gamma-GT) which are considered as biochemical indicators of pulmonary damage. The concomitant histopathological examination of Fen exposed rats' lung revealed inflammatory changes viz., influx of mononuclear cells admixed with a few giant cells in alveolar lumen, hypetrophied bronchiolar and alveolar epithelial lining cells and presence of edematous fluid in alveolar lumen alongwith congested parenchymatous blood vessels. CONCLUSION: These results for the first time indicate the pulmonary toxic effects of a commonly used formulated Fen preparation by using rat model and nose only inhalation as the route of exposure.

Animals↗
PubMed2001

Solid--cystic papillary tumor of pancreas.

A case of Solid and Cystic Papillary Epithelial Tumor of Pancreas displaying low grade malignancy occurring in a 38 years old female is presented. It is a rare condition and could be diagnosed histopathologically after complete excision.

Adult↗