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R Peces

Publications and source records attributed to R Peces.

At least 55 records · Page 3Linked to original sources
PubMed1997

Prospective analysis of the factors influencing the antibody response to hepatitis B vaccine in hemodialysis patients.

Hepatitis B vaccine is effective in producing protection against hepatitis B virus (HBV) infection in hemodialysis (HD) patients, but the antibody response is variable. To identify those factors implicated in the vaccine response, in a prospective study over a 24-month period, we vaccinated 80 seronegative patients on HD (group A) and monitored clinical, biochemical, and immunologic parameters. The protective immunity acquired by vaccination was compared with that developed through HBV infection in 22 age-matched HD patients (group B). The anti-HBs antibody-seronegative patients followed a four-dose vaccination schedule (0, 1, 2, and 6 months) with 40 microg DNA-recombinant hepatitis B vaccine. One month after vaccination, 77.5% of the patients had seroconverted, and 72.5% achieved high antibody response, whereas 22.5% were nonresponders. Patients aged younger than 40 years seroconverted 100%; those aged 40 to 60 years, 75% (P < 0.01); and patients older than 60 years, 74% (P < 0.001). No differences between responders and nonresponders concerning sex, time on HD, HD dose, nutritional status, hemoglobin level, HD membrane, iPTH level, calcitriol treatment, or number of transfusions during vaccination were found. The presence of other factors, such as recombinant human erythropoietin (rHuEPO) therapy or hepatitis C virus (HCV) infection, did not significantly influence antibody responses to hepatitis B immunization. A greater frequency of DR3 (53.8% v 25.7%, P < 0.05), DR7 (53.8% v 18.6%, P < 0.01), and DQ2 (76.9% v 44.1%, P < 0.05), and a lesser frequency of A2 (7.7% v 37.2%, P < 0.05) were found in nonresponders compared with responders. Eighteen months after vaccination, the analysis showed similar antibody titers but lower seroconversion rates in group A as compared with group B. In conclusion, unresponsiveness to hepatitis B vaccine in HD patients was related to factors such as older age, the presence of DR3, DR7, and DQ2, and the absence of A2 alleles. Although the seroprotection produced by the vaccine was less than that achieved through natural HBV infection, our protocol of vaccination was sufficiently immunogenic and provided lasting protection.

Adult↗
PubMed1995

Influence of HLA-DR phenotype on tumor necrosis factor-alpha production in renal-transplant recipients.

In healthy subjects, previous studies have demonstrated a great interindividual variability in the ability for tumor necrosis factor-alpha (TNF-alpha) production. The gene for TNF-alpha is closely linked to and located in the major histocompatibility complex (MHC) and it has been suggested that these interindividual differences may be HLA related. Since TNF-alpha is likely to be an important mediator in renal allograft rejection, we investigated the role of HLA antigens on TNF-alpha production rates by peripheral blood mononuclear cells (PBMC) from renal transplant recipients during stable graft function. HLA-DR2-positive recipients showed significantly lower spontaneous TNF-alpha production than DR2-negative patients (p < 0.001). Upon stimulation with OKT3, HLA-DR2-positive patients also showed significantly lower TNF-alpha production than DR2-negative subjects (p < 0.001). HLA-DR3-positive recipients, however, showed significantly higher spontaneous TNF-alpha production than DR3-negative individuals (p < 0.05). These results suggest that differences in TNF-alpha production, both spontaneous and induced, may be due to the expression of certain DR allotypes.

Cyclosporine↗
PubMed1995

Effect of calcium-channel blocker on tumour necrosis factor alpha (TNF alpha) production in cyclosporin-treated renal transplant recipients.

PURPOSE OF THE STUDY: The influence of calcium-channel blocker treatment on in-vitro TNF alpha production by peripheral blood mononuclear cells (PBMC) from renal transplant recipients treated with cyclosporin was studied. DESIGN: We compared spontaneous and OKT3-induced TNF alpha production of 12 renal transplant recipients treated with calcium-channel blocker therapy with that of 18 renal transplant recipients who were never treated with a calcium antagonist. RESULTS: The two groups were similar with regards to age, time after transplantation, dosage of immunosuppressive drugs, and blood cyclosporin levels. Spontaneous (481 +/- 161 versus 319 +/- 74 pg/ml, n.s.) and OKT3-induced (745 +/- 182 versus 632 +/- 112 pg/ml, n.s.) TNF alpha production were similar in both groups. CONCLUSIONS: The results indicate that in cyclosporin-treated renal transplant recipients calcium-channel blockers do not affect TNF alpha production.

Adult↗
PubMed1994

Pituitary-testicular function in cyclosporin-treated renal transplant patients.

The aim of this study was to investigate the differences in LH, FSH, PRL and testosterone levels in 20 men on haemodialysis and 26 men following renal transplantation. Nineteen of the renal transplant recipients were receiving cyclosporin, azathioprine, and prednisone, while the seven remaining individuals received azathioprine and prednisone. A subgroup of eight patients were also studied longitudinally while undergoing maintenance haemodialysis and after transplantation. The results show that successful renal transplantation resulted in a normalization of hormone levels in either the cross-sectional or longitudinal groups, the degree of which was unaffected by treatment modality. Cyclosporin given in therapeutic doses does not alter the pituitary-testicular function in renal transplant recipients.

Adult↗
PubMed1993

Cytosolic free calcium regulation in response to acute changes in intracellular pH in vascular smooth muscle.

This study examined the mechanisms whereby alterations of intracellular pH (pHi) impact on free cytosolic calcium (Cai2+) in cultured rat aortic vascular smooth muscle cells (VSMC) assayed in the presence of HCO3/CO2. Rapid cell alkalinization, effected by the exposure to NH4Cl or removal of CO2 from the superfusate, produced a rapid increase in Cai2+. The rise in Cai2+ was markedly diminished when sarcoplasmic reticulum (SR) Ca2+ stores had been depleted by prior exposure to arginine vasopressin (AVP) in Ca(2+)-free media or when SR release and reuptake of Ca2+ were blocked by the addition of 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester (TMB-8), but was unaffected by the removal of external Ca2+ or inhibition of Ca2+ entry using NiCl2. Cell acidification also resulted in a rapid increase in Cai2+. This Cai2+ increase was most apparent when pHi was very low (< 6.6) and was unaffected by removal of external Ca2+ or NiCl2 addition. Unlike the effect of cell alkalinization, the increase in Cai2+ associated with cell acidification was not prevented by pretreatment with AVP or TMB-8. We conclude that, in cultured VSMC, acute intracellular alkalinization and, to a lesser extent, acidification result in release of Ca2+ from internal stores. Alkalinization increases Cai2+ by promoting its release from a store which is AVP and TMB-8 sensitive, most likely the SR. Cell acidification increases Cai2+ from an intracellular store(s) that is neither AVP nor TMB-8 sensitive. The increase in Cai2+ produced by cell acidification may be explained on the basis of cell buffering such that, as cytosolic H+ increases, it displaces Cai2+ from internal buffers with similar affinities for Ca2+ and H+.

Ammonium Chloride↗