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Biomedical subjects

A B Pereira

Publications and source records attributed to A B Pereira.

At least 19 recordsLinked to original sources
PubMed2006

Determination of renal function in long-term heart transplant patients by measurement of urinary retinol-binding protein levels.

Significant improvements have been noted in heart transplantation with the advent of cyclosporine. However, cyclosporine use is associated with significant side effects, such as chronic renal failure. We were interested in evaluating the incidence of long-term renal dysfunction in heart transplant recipients. Fifty-three heart transplant recipients were enrolled in the study. Forty-three patients completed the entire evaluation and follow-up. Glomerular (serum creatinine, creatinine clearance measured, and creatinine clearance calculated) and tubular functions (urinary retinol-binding protein, uRBP) were re-analyzed after 18 months. At the enrollment time, the prevalence of renal failure ranged from 37.7 to 54% according to criteria used to define it (serum creatinine > or = 1.5 mg/dL and creatinine clearance <60 mL/min). Mean serum creatinine was 1.61 +/- 1.31 mg/dL (range 0.7 to 9.8 mg/dL) and calculated and measured creatinine clearances were 67.7 +/- 25.9 and 61.18 +/- 25.04 mL min-1 (1.73 m(2))-1, respectively. Sixteen of the 43 patients who completed the follow-up (37.2%) had tubular dysfunction detected by increased levels of uRBP (median 1.06, 0.412-6.396 mg/dL). Eleven of the 16 patients (68.7%) with elevated uRBP had poorer renal function after 18 months of follow-up, compared with only eight of the 27 patients (29.6%) with normal uRBP (RR = 3.47, P = 0.0095). Interestingly, cyclosporine trough levels were not different between patients with or without tubular and glomerular dysfunction. Renal function impairment is common after heart transplantation. Tubular dysfunction, assessed by uRBP, correlates with a worsening of glomerular filtration and can be a useful tool for early detection of renal dysfunction.

Biomarkers↗
PubMed2003

Predictive value of urinary retinol binding protein for graft dysfunction after kidney transplantation.

UNLABELLED: High concentrations of retinol binding protein (RBP) are found in the urine of patients with tubulointerstitial injury. We evaluated the predictive value of urinary RBP (RBPu) for development graft dysfunction after kidney transplantation. METHODS: Serum creatinine and RBPu were prospectively measured at months 3, 6, and 12 in 221 kidney transplant patients. Baseline graft function was defined as the lowest serum creatinine value during the first 3 months after transplantation. Graft dysfunction was assessed at 1 year as a >-20% or >-30% change in the inverse creatinine ((Delta)1/Cr) compared to baseline value at month 3. RESULTS: Among 183 patients with normal graft function (Cr </= 1.6 mg/dL) the mean (Delta)1/Cr from month 3 to 12 was -17 +/- 22% (-80% to + 44%). Using a receiver operating characteristic (ROC) analysis, concentrations higher than 0.6 mg/L showed the best predictive value for diagnosis of graft dysfunction at 1 year. Mean (Delta)1/Cr from month 3 to 12 was -13 +/- 20% for those with RBP < 0.6 mg/L vs -20 +/- 23% in those with RBPu > 0.6 mg/L (95% CI = -13% to -1.3%, P =.018). The percentage of patients with >-20% or >-30% (Delta)1/Cr was higher among patients with RBPu > 0.6 mg/L (34% vs 47%, P =.042; 21% vs 34%, P =.035). RBPu > 0.6 mg/L was the only variable independently associated with >-30% (Delta)1/Cr at 1 year, with an odds ratio (OR) of 1.95 (95% CI 0.99 to 3.80, P =.05). CONCLUSIONS: RBPu may serve as a surrogate marker for graft dysfunction early after transplantation for patients with normal graft function, allowing early institution of intervention therapies to prolong allograft survival.

Adolescent↗
PubMed2001

Early detection of heart transplant patients with increased risk of ciclosporin nephrotoxicity.

Chronic nephrotoxic effects from ciclosporin are a common clinical complication after heart transplantation and frequently lead to progressive renal failure. There is no laboratory test to predict development of chronic renal failure in heart transplant patients. We analysed urinary retinol-binding protein (uRBP) concentration, to assess proximal tubular dysfunction, in 36 clinically stable heart transplant patients. We detected a subgroup of 13 patients who had high concentrations of uRBP, good renal function, and a high risk of developing progressive renal failure compared with patients with normal uRBP (relative risk 3.87, p=0.003).

Adult↗
PubMed2000

Urinary retinol-binding protein as a prognostic marker in the treatment of nephrotic syndrome.

We studied the urinary levels of retinol-binding protein (urRBP), an index of proximal tubular dysfunction, in patients with nephrotic syndrome before and approximately 2 months after the beginning of steroid therapy as a predictor of response to therapy which included for some patients courses of immunosuppressive drugs. Those patients with minimal-change disease, mesangial proliferative glomerulonephritis, and focal-segmental glomerulosclerosis who had normal pretreatment urRBP levels were responsive to treatment; occasionally, responsive patients had an initially elevated urRBP level which normalized during treatment. Contrariwise, those patients with abnormally high levels of urRBP which did not normalize during treatment did not respond to treatment. The chance of a patient with minimal-change disease, mesangial proliferative glomerulonephritis, or focal-segmental glomerulosclerosis and a pretreatment urRBP level equal to or >1.0 mg/l being resistant to steroid treatment is 30 times that of a patient with a urRBP level <1.0 mg/l and even higher, if we consider the levels obtained during treatment.

Adolescent↗
PubMed1998

Prevalence of hepatitis C virus antibodies in primary glomerulonephritis in Brazil.

The association between hepatitis B virus and membranous glomerulonephritis and membranoproliferative glomerulonephritis (MPGN) was first described in 1971. Recently, a similar association between hepatitis C virus (HCV) and glomerulonephritis (GN) has been reported. We investigated the prevalence of hepatitis C serum antibodies (anti-HCV) in patients with primary GN followed up at our Nephrology Outpatient Clinic between March 1993 and November 1995. The diagnosis of primary GN was established after excluding the presence of connective tissue disease, diabetes, infectious disease, and malignancy. Anti-HCV antibodies were detected by a second-generation enzyme immunosorbent assay and HCV RNA by polymerase chain reaction. Of 81 patients with primary GN, 24 had membranous glomerulonephritis, 17 MPGN, 15 minimal-change disease, 12 focal-segmental glomerulosclerosis, 9 diffuse proliferative GN, and 4 IgA nephropathy. Anti-HCV were detected in 2 cases (2.5%), both were HCV RNA positive and had a polyclonal mixed cryoglobulinemia (IgM-IgG). These 2 cases both came from the group of 17 patients with MPGN. Biochemical investigation in these patients revealed persistent elevation of serum aminotransferase activity, and a liver biopsy specimen in 1 of them showed evidence of chronic active hepatitis. We conclude that in our setting the prevalence of anti-HCV among patients with primary GN is low, being higher (11.8%) only if we consider the patients with MPGN as the reference group. Further studies are necessary to clarify this association and to determine appropriate therapy for these patients.

Adolescent↗
PubMed1997

Heterogeneity of glomerular perfusion and filtration induced by epinephrine and norepinephrine.

The role of catecholamines in the distribution of intrarenal blood flow and in single-nephron glomerular filtration rate (SNGFR) was evaluated in anesthetized Wistar rats by the Hanssen technique. Epinephrine (EPI) and norepinephrine (NOR) were infused to produce elevations of 20-30 mmHg in mean arterial pressure. Superficial and juxtamedullary nephron perfusion and filtration were determined by the presence of Prussian blue dye. In the control group, 100% of the nephrons presented a homogeneous pattern of perfusion and filtration. In contrast, a heterogeneous distribution of the dye was found even in the larger arteries (arciform and radial), indicating variable perfusion and filtration in both superficial and juxtamedullary nephrons. The effects of EPI and NOR were also evaluated in the superficial cortex by the micropuncture technique in two additional groups of Munich-Wistar rats. Mean SNGFR was 27% and 54% lower in the EPI- and NOR-treated groups, respectively. No change in mean intraglomerular hydraulic pressure was observed after EPI or NOR infusion in spite of a highly scattered pattern, indicating an important variability in perfusion along the superficial cortex, and/or different sensitivity of the pre- and post-glomerular arterioles. The present data suggest that EPI and NOR may affect intrarenal hemodynamics by modifying perfusion and filtration in both superficial and juxtamedullary glomeruli and not by shifting blood flow from superficial to juxtamedullary nephrons. The heterogeneous pattern of perfusion was a consequence of differential vasoconstriction along the intrarenal arteries, probably due to different density and/or sensitivity of the adrenergic receptor subtypes present in the intrarenal vascular tree.

Animals↗
PubMed1994

Serum levels of prostate-specific antigen in normal boys throughout puberty.

Serum levels of prostate-specific antigen (PSA) were measured in a group of 132 normal boys distributed in stages 1-5 of puberty. A highly sensitive (0.005 ng/mL) immunofluorometric assay was developed and used in the study. PSA levels were generally undetectable in state I and rose sharply from stage II to III and from stage III to IV. A significant positive correlation was found between PSA and testosterone levels, PSA and LH levels, PSA and age, PSA and testicular volume, as well as PSA and pubertal stage. Our findings indicate that PSA levels measured with highly sensitive assays can be of utility in the hormonal evaluation of puberty in boys.

Adolescent↗
PubMed1994

Assessment of glomerular filtration rate utilizing subcutaneously injected 51Cr-EDTA.

1. 51Cr-EDTA injected with lidocaine and epinephrine, as a subcutaneous button, is slowly absorbed, and a plasma level that is relatively stable can be maintained for a time sufficient to permit measurement of the renal clearance of EDTA, which is a measure of glomerular filtration rate (GFR). We studied this procedure in 32 normal volunteers and 24 patients with different glomerulopathies, comparing EDTA and creatinine clearances. In 20 patients these measurements were also compared with inulin clearance. 2. Creatinine clearance overestimates GFR due to tubular secretion of creatinine. This secretion is present even in patients with significantly reduced glomerular filtration rates. As a consequence, the lower the GFR the higher the overestimation will be. 3. A good correlation was obtained between the 51Cr-EDTA and inulin clearance: y(EDTA) = 4.21 + 0.88 x (inulin), r = 0.98. The procedure is simple to perform, and the radiotracer utilized is significantly less expensive than iothalamate.

Adolescent↗
PubMed1994

Assessment of lupus nephritis activity using urinary retinol-binding protein.

We evaluated the presence of proximal renal tubular dysfunction as measured by urinary retinol-binding protein (RBP) in 70 patients with systemic lupus erythematosus. Renal disease activity was assessed using the British Isles Lupus Assessment Group (BILAG) index. This is a clinical-laboratory score based on the principle of the physician's intention to treat. Increased urinary RBP (> 400 micrograms/l) was detected in 17 of 22 (77%) patients with active nephritis, six of 18 (33%) patients with probably active nephritis, one of nine (12%) cases with stable renal disease, and one of 21 (5%) cases without apparent renal disease (P < 0.01). Compared to initial values, mean urinary RBP decreased significantly in six patients evaluated after improvement of the exacerbation of renal disease. There was a positive correlation between urinary RBP and 24-h proteinuria (r = 0.40, P < 0.01), and an inverse correlation between urinary RBP and creatinine clearance (r = -0.60, P < 0.01). In a multivariate analysis adjusting for duration of disease, blood pressure, 24-h proteinuria, and creatinine clearance, mean urinary RBP continued to be significantly and progressively greater for patients with no renal disease, stable renal disease, probably active and active nephritis. Proximal tubular dysfunction is frequent in patients with active lupus nephritis. This association cannot be completely explained by the effects of increased total proteinuria, reduced glomerular filtration rate, and systemic hypertension. Urinary RBP seems to be a marker of renal disease activity. This test may be clinically useful to differentiate patients with active lupus nephritis from those with stable or absent renal disease.

Adolescent↗
PubMed1994

Specific and nonspecific aspects of humoral immune response in leprosy.

1. We have studied some generic and specific aspects of the humoral immune response in 96 patients with leprosy (29 paucibacillary and 67 multibacillary individuals). We determined serum immunoglobulins (IgM, IgG and IgA), CH50, C1q, C3 and C4, circulating immune complexes (CIC), C-reactive protein (CRP), rheumatoid factor (RF) and antinuclear antibodies. No specific pattern of general humoral immune changes could be observed. 2. The specific immune response was studied by the detection of specific IgM anti-M. leprae antibodies. An immunoradiometric assay (IRMA) and an ELISA were compared for clinical effectiveness. IRMA showed greater sensitivity for the serodiagnosis of leprosy as compared to ELISA (88.1% vs 58.2% for multibacillary patients and 20.7% vs 10.3% for paucibacillary leprosy patients). Specificity was 96% for IRMA and 97% for ELISA. 3. Our results indicate that nonspecific changes in the humoral immune response are of little value in assessing leprosy patients and that immune assays for the detection of specific anti-M. leprae antibodies may be of value in the diagnosis, study and follow-up of these patients.

Adolescent↗