Expansion of peripheral blood CD5+ B cells is associated with mild disease in chronic hepatitis C virus infection

BACKGROUND/AIMS: Hepatitis C virus (HCV) infection is associated with the development of chronic liver disease and extra-hepatic manifestations, which include autoantibody production, immune-mediated diseases such as cryoglobulinaemia and B-cell lymphoproliferation. Recent identification of intra-hepatic clonal B cells capable of rheumatoid factor production, selective infection of B cells over T cells and of an HCV receptor on B lymphocytes strongly supports a central role for these cells in the immune response to HCV infection. In particular, CD5+ B cells which are capable of producing natural antibodies with autoreactive specificities are likely to be important in the development of HCV-associated autoimmunity and lymphoproliferation. METHODS: We have investigated the presence of CD5+ B cells in a unique cohort of HCV-infected women who were infected with a single inoculum of HCV genotype 1b following immunisation with contaminated anti-D immunoglobulin in 1977. RESULTS: CD5+ B cells are significantly increased in chronic HCV infection (37.66+/-1.92%) as compared with those with resolved infection (25.33+/-1.90%). High levels of CD5+ B cells were associated with the production of rheumatoid factor. The number of peripheral blood CD5+ B cells correlated negatively with histological activity index. CONCLUSIONS: The expansion of this B cell population in patients with active HCV infection may give rise to immune-mediated sequelae associated with HCV infection. This expanded population of CD5+ B cells may protect against the development of progressive liver disease.     

Cytoprotective effects of nitrates in a cellular model of hydronephrosis

BACKGROUND: The earliest insult to the kidney following the onset of ureteral obstruction is a marked elevation in collecting system pressure. This imparts a mechanical stress that is transmitted directly from the collecting system to the kidney substance. Renal tubular injury is the principal functional and histological change encountered, with glomerular changes being less marked and occurring later. Nitric oxide (NO) has been shown to protect against renal injury in UO, but its mode of action has not been clearly defined. METHODS: MDCK (canine) and HK-2 (human) renal tubular cells were grown under control conditions or subjected to mechanical strain for periods of 24 and 48 hours. Cells were studied treated with or without Fas-antibody, etoposide or diethyl maleate (DEM) alone or in combination with NG-monomethyl l-arginine (L-NMMA), sodium nitroprusside (SNP) or l-arginine. Cell proliferation and apoptosis was determined using propidium iodide DNA staining. NO production and inducible NO synthase (iNOS) expression were measured by the Griess reaction and Western blotting, respectively. RESULTS: Cells subjected to mechanical strain displayed a decrease in the proportion of cells undergoing cell division. They also showed an increased susceptibility to apoptosis. Associated with this was a decrease in Bcl-2 expression. An increase in iNOS expression was seen in cells subjected to mechanical strain, but no increase in NO production. The cellular effects of mechanical strain were reversed by SNP and l-arginine. CONCLUSIONS: Culture of renal tubule cells in an environment of mechanical strain results in an imbalance in homeostasis and a net cell loss. This can be reversed by the administration of an NO donor or precursor.     

Increased efficiency of fatty acid uptake contributes to lipid accumulation in skeletal muscle of high fat-fed insulin-resistant rats

In humans and animal models, increased lipid content of skeletal muscle is strongly associated with insulin resistance. However, it is unclear whether this accumulation is due to increased uptake or reduced utilization of fatty acids (FAs). We used (3)H-R-bromopalmitate tracer to assess the contribution of tissue-specific changes in FA uptake to the lipid accumulation observed in tissues of insulin-resistant, high fat-fed rats (HFF) compared with control rats (CON) fed a standard diet. To study FA metabolism under different metabolic states, tracer was infused under basal conditions, during hyperinsulinemic-euglycemic clamp (low FA availability) or during the infusion of intralipid and heparin (high FA availability). FA clearance was significantly increased in the red gastrocnemius muscle of HFF under conditions of low (HFF = 10.4 +/- 1.1; CON = 7.4 +/- 0.5 ml x min(-1) x 100 g(-1); P < 0.05), basal (HFF = 8.3 +/- 1.4; CON = 4.5 +/- 0.7 ml x min(-1) x 100 g(-1); P < 0.01), and high (HFF = 7.0 +/- 0.8; CON = 4.3 +/- 0.5 ml x min(-1) x 100 g(-1); P < 0.05) FA levels. This indicates an adaptation by muscle for more efficient uptake of lipid. Associated with the enhanced efficiency of FA uptake, we observed increases in CD36/FA translocase mRNA expression (P < 0.01) and acyl-CoA synthetase activity (P < 0.02) in the same muscle. FA clearance into white adipose tissue was also increased in HFF when circulating FA were elevated, but there was little effect of the high-fat diet on hepatic FA uptake. In conclusion, insulin resistance induced by feeding rats a high-fat diet is associated with tissue-specific adaptations that enhance utilization of increased dietary lipid but could also contribute to the accumulation of intramuscular lipid with a detrimental effect on insulin action.     

Specific c-K-ras Gene Mutations as a Tumor-Response Marker in Locally Advanced Rectal Cancer Treated With Preoperative Chemoradiotherapy

Background: Forty percent of patients with colorectal cancer develop mutations in the K-ras gene.Objective: Our objective was to evaluate whether the presence of c-K-ras gene mutations is a useful tumor-response marker in patients with locally advanced rectal cancer treated with preoperative chemoradiotherapy.Material and Methods: Thirty seven patients with locally advanced rectal cancer were treated with preoperative chemoradiotherapy. Four to six weeks later, surgery was performed. Specimens were classified according to the UICC-AJC classification. A segment of the tumor was obtained to analyze specific c-K-ras gene mutations. Restriction fragment length polymorphism (RFLP) and single strand confirmation polymorphism (SSCP) techniques were used with a set of probes to detect specific c-K-ras mutations in codons 12, 13, and 61. The 37 patients were divided into Group A (with mutations) and Group B (without mutations).Results: All 37 patients completed the scheduled treatment. Group A consisted of 12 patients, whose tumors were classified and specific c-K-ras mutations were located as follows: eight in codon 12, two in codon 13, and one in codon 61. Group B consisted of 25 patients. The tumors were classified and there were more early-stage tumors in Group A, whereas in Group B there were more advanced-stage tumors (P 5 .05, respectively). The mean follow-up was 36.2 6 18.3 months. All Group A patients survived, whereas 8 of the 25 patients in Group B died due to progressive metastatic disease. Survival in Group A was 100%, whereas in Group B it was 59% (P 5 .03).Conclusions: The presence of specific c-K-ras mutations is an indicator of tumor response in patients with locally advanced rectal cancer treated with preoperative chemoradiotherapy and surgery. Therefore, responding patients may be more amenable to less radical surgical procedures based on c-K-ras mutations.