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Shashi K Ramaiah

Publications and source records attributed to Shashi K Ramaiah.

7 recordsLinked to original sources
PubMed2006

The temporal expression of osteopontin (SPP-1) in the rodent model of alcoholic steatohepatitis: a potential biomarker.

Previous studies from our laboratory have shown that osteopontin (OPN) mediates neutrophil infiltration into the liver in a rodent model of alcoholic steatohepatitis (ASH). The objective of this study was to investigate the temporal and spatial pattern of hepatic OPN mRNA and protein expression during the progression of alcoholic liver disease. OPN mRNA and protein expression were evaluated using real time PCR, in situ hybridization, Western blot and immunohistochemistry respectively. ASH was induced in male Sprague-Dawley rats by feeding EtOH-containing Lieber-DeCarli diet for 6 weeks, followed by a single injection of lipopolysaccharide (LPS, 10 mg/kg, ip). Rats were sacrificed 2-, 12-and 24-hour post LPS injection. A progressive induction of OPN mRNA was observed that preceded hepatic neutrophil infiltration and the increase in OPN mRNA correlated with increases in OPN protein expression. OPN mRNA was localized primarily to the biliary epithelium. The data indicates that OPN is transcribed and translated within the biliary epithelium. These findings suggest a potential role of OPN as an early biomarker in predicting inflammatory liver diseases such as ASH.

Alanine Transaminase↗
PubMed2006

Calpain inhibition attenuates iNOS production and midzonal hepatic necrosis in a repeat dose model of endotoxemia in rats.

Systemic exposure to bacterial lipopolysaccharide (LPS, endotoxin) induces hypotension, disseminated intravascular coagulation and neutrophil infiltration in various organs including the lung, kidney and liver. A rat endotoxemic neutrophilic hepatitis model (repeat dose LPS, 10 mg/kg, i.v. 24 hours apart) was developed exhibiting hepatic neutrophil infiltration and mid-zonal hepatic necrosis. The goal of the study was to investigate the role of the intracellular enzyme calpain in the development of neutrophilic hepatitis with midzonal necrosis in this model. A second goal was to compare the observed protective effects of calpain inhibition with a relatively selective inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (AG) and an inhibitor of coagulation, heparin. When compared to rats administered LPS alone, administration of calpain 1 inhibitor prior to LPS significantly reduced hepatic iNOS expression, hepatic neutrophil infiltration and attenuated midzonal hepatic necrosis. Administration of AG or heparin prior to LPS also decreased liver iNOS expression, hepatic neutrophil infiltration and liver pathology comparable to calpain inhibition. Blood neutrophil activation, as measured by the neutrophil adhesion molecule CD11b integrin, was upregulated in all the LPS treated groups regardless of inhibitor administration. We conclude that amelioration of liver pathology via calpain inhibition is likely dependent on the down-regulation of iNOS expression in the rat model of LPS-mediated hepatitis.

Animals↗
PubMed2005

Role of osteopontin in hepatic neutrophil infiltration during alcoholic steatohepatitis.

Alcoholic liver disease (ALD) is a major complication of heavy alcohol (EtOH) drinking and is characterized by three progressive stages of pathology: steatosis, steatohepatitis, and fibrosis/cirrhosis. Alcoholic steatosis (AS) is the initial stage of ALD and consists of fat accumulation in the liver accompanied by minimal liver injury. AS is known to render the hepatocytes increasingly sensitive to toxicants such as bacterial endotoxin (LPS). Alcoholic steatohepatitis (ASH), the second and rate-limiting step in the progression of ALD, is characterized by hepatic fat accumulation, neutrophil infiltration, and neutrophil-mediated parenchymal injury. However, the pathogenesis of ASH is poorly defined. It has been theorized that the pathogenesis of ASH involves interaction of increased circulating levels of LPS with hepatocytes being rendered highly sensitive to LPS due to heavy EtOH consumption. We hypothesize that osteopontin (OPN), a matricellular protein (MCP), plays an important role in the hepatic neutrophil recruitment due to its enhanced expression during the early phase of ALD (AS and ASH). To study the role of OPN in the pathogenesis of ASH, we induced AS in male Sprague-Dawley rats by feeding EtOH-containing Lieber-DeCarli liquid diet for 6 weeks. AS rats experienced extensive fat accumulation and minimal liver injury. Moderate induction in OPN was observed in AS group. ASH was induced by feeding male Sprague-Dawley rats EtOH-containing Lieber-DeCarli liquid diet for 6 weeks followed by LPS injection. The ASH rats had substantial neutrophil infiltration, coagulative oncotic necrosis, and developed higher liver injury. Significant increases in the hepatic and circulating levels of OPN was observed in the ASH rats. Higher levels of the active, thrombin-cleaved form of OPN in the liver in ASH group correlated remarkably with hepatic neutrophil infiltration. Finally, correlative studies between OPN and hepatic neutrophil infiltration was corroborated in a simple rat peritoneal model where enhanced peritoneal fluid neutrophil infiltration was noted in rats injected OPN intraperitoneally. Taken together these data indicate that OPN expression induced during ASH may play a significant role in the pathogenesis of ASH by stimulating neutrophil transmigration.

Animals↗
PubMed2002

Upregulated promitogenic signaling via cytokines and growth factors: potential mechanism of robust liver tissue repair in calorie-restricted rats upon toxic challenge.

Previously we reported that moderate calorie restriction or diet restriction (DR, calories reduced by 35% for 21 days) in male Sprague-Dawley rats protects from a lethal dose of thioacetamide (TA). DR rats had 70% survival compared with 10% in rats fed ad libitum (AL) because of timely and adequate compensatory liver cell division and tissue repair in the DR rats. Further investigation of the mechanisms indicate that enhanced promitogenic signaling plays a critical role in this stimulated tissue repair. Expression of stimulators of promitogenic signaling interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), hepatocyte growth factor (HGF), transforming growth factor-alpha (TGF-alpha), and epidermal growth factor receptor (EGFR) were studied during liver tissue repair after TA-induced liver injury. Plasma IL-6 was significantly higher in the DR rats, with 6-fold higher expression at 48 h after TA administration. Immunohistochemical localization revealed significantly higher expression of IL-6 in the hepatic sinusoidal endothelium of DR rats. Expression of TGF-alpha and HGF was consistently higher in the livers of DR rats from 36 to 72 h. EGFR, which serves as a receptor for TGF-alpha, was higher in DR rats before TA administration and remained higher till 48 h after TA intoxication. DR-induced 2-fold increase in hepatic iNOS activity is consistent with early cell division in DR rats after TA challenge. These data suggest that the reason behind the higher liver tissue repair after TA-induced hepatotoxicity in DR rats is timely and higher expression of the growth stimulatory cytokines and growth factors. It appears that the physiological effects of DR make the liver cells vigilant and prime the liver tissue promptly for liver regeneration through promitogenic signaling upon toxic challenge.

Animals↗
PubMed2002

Biclonal gammopathy associated with immunoglobulin A in a dog with multiple myeloma.

A 10-year-old neutered male Airedale Terrier was evaluated for inappetance, weight loss, and lameness. Multiple myeloma was diagnosed based on bone marrow plasmacytosis, multiple lytic bone lesions, and hyperglobulinemia with a clonal gammopathy on serum protein electrophoresis. Splenic plasmacytosis, and retinal lesions consistent with hyperviscosity syndrome also were found. Temporary responses to 2 different chemotherapy protocols (melphalan and prednisone, and cyclophosphamide and prednisone) were seen, with remission of clinical signs and a decrease in the biclonal gammopathy but no resolution of the splenic mass. Eventual return of clinical signs led to euthanasia at 175 days postdiagnosis. Necropsy examination confirmed multiple myeloma involving bone marrow and spleen, and glomerulonephritis. An immunoglobulin-A (IgA) gammopathy was demonstrated by immunoelectrophoresis; biclonality was ascertained by immunofixation electrophoresis. The clonal components consisted of intact Ig with heavy chain of the alpha class and light chain of an undetermined class. To our knowledge, this is the first report of undimerized biclonal gammopathy in a dog caused by a single heavy chain class involving IgA.

Animals↗
PubMedDate not supplied

Hepatocyte proliferation is the possible mechanism for the transient decrease in liver injury during steatosis stage of alcoholic liver disease.

Steatosis is a frequent pathologic stage in alcoholic liver disease (ALD). Although the mechanisms for increased susceptibility of steatotic liver to injury have been postulated, the ability of these hepatocytes to proliferate and withstand injury is unknown. There are conflicting reports on the status of hepatocyte regeneration following chronic alcohol ingestion. Hence, the objective of this study was to investigate the temporal dynamics between the pattern of liver injury and hepatocyte proliferation during the steatosis stage of ALD. Alcoholic steatosis was induced in male Sprague-Dawley rats by feeding an ethanol (EtOH)-containing Lieber-DeCarli liquid diet for a period of 5 weeks. Microvesicular steatosis was evident in H&E sections by three weeks in the EtOH-treated rats, which further developed into panlobular macrovesicular steatosis by 5 weeks. Plasma transaminase activities indicated progressive increase in liver injury peaking at 3 weeks with significant but mild decrease at 4 and 5 weeks. CYP2E1 protein and activity was significantly increased in EtOH-fed rats as measured by Western blot and pNP hydroxylation assay. PCNA analysis of liver sections indicated that EtOH-treated rats had a significantly higher number of cells in S phase of cell division at weeks 1 (3.20 +/- 0.19), 2 (7.03 +/- 0.92), and 3 (4.23 +/- 1.41) when compared to controls (1.5 +/- 0.22). NF-kappaB DNA binding and Cyclin D1 proteins increased significantly in the EtOH-treated rats corresponding with enhanced hepatic proliferation. These data suggest the transient decline in liver injury during alcoholic steatosis is due to enhanced NF-kappaB-dependent hepatocyte proliferation.

Alanine Transaminase↗