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Biomedical subjects

F Olavarría

Publications and source records attributed to F Olavarría.

18 recordsLinked to original sources
PubMed1998

Antibody to streptococcal zymogen in the serum of patients with acute glomerulonephritis: a multicentric study.

BACKGROUND: Cationic streptococcal proteinase (erythrotoxin B) and its precursor, zymogen, are putative nephritogenic antigens. The present study was designed to test whether serum titers to these antigens were good markers of streptococcal infection associated with glomerulonephritis. METHODS: We studied 153 patients (male/female = 104/49, age range, 2 to 23 years old) with acute poststreptococcal glomerulonephritis (APSGN) from three countries (Venezuela, Chile and Argentina). The site of the initial infection was the skin in 84 patients, the throat in 55 patients and was unknown in 14 patients. In addition, we studied 23 patients (1 to 24 years old) with streptococcal infection not associated with glomerulonephritis (14 patients with impetigo and 9 patients with pharyngitis). As control group, 93 healthy individuals (54 males, 2 to 19 years old) were studied. Anti-zymogen and anti-proteinase titers were determined in a single laboratory by ELISA, and the intra- and interassay coefficients of variation were 5.3% and 8.5%, respectively. ASO titers and anti-DNAse B titers were also done. RESULTS: Anti-zymogen titers of 1:800 to 1:3200 had likelihood ratios (sensitivity/1-specificity) for detection of streptococcal infection in APSGN patients ranging from 2.00 to 44.2 in Argentina, Chile and Venezuela. Anti-zymogen titers decreased one to two months after APSGN and they were 1 to 3 log2 dilutions higher that anti-proteinase titers. Receiver operating characteristic (ROC) curves showed that anti-zymogen titers were consistently superior to anti-streptolysin O and anti-DNAse B titers as markers for streptococcal infection in APSGN. CONCLUSIONS: These results suggest that increased anti-zymogen antibody titers are the best available marker for streptococcal infection associated with acute glomerulonephritis.

Acute Disease↗
PubMed1998

Anticardiolipin antibodies in classic pediatric hemolytic-uremic syndrome: a possible pathogenic role.

Anticardiolipin (aCL) antibodies have been associated with thrombocytopenia, hemolytic anemia and an increased risk of thrombosis in different vascular locations, even in the absence of lupus. The classic hemolytic-uremic syndrome is a postinfectious acute renal failure characterized by hemolytic anemia, thrombocytopenia and the presence of widespread glomerular thrombosis in the kidney, with pathogenic mechanisms that remain to be identified. In order to establish the frequency of aCL antibodies in this syndrome and to identify a possible role in the pathogenesis and clinical manifestations, 17 patients were studied during the reactant phase of the disease looking for an association between the presence of aCL antibodies (isotypes IgG, IgA and IgM) and the main clinical variables of the syndrome. In 8 patients IgG aCL was present, 2 patients had IgM aCL, and 1 had IgA antibodies on the solid-phase ELISA aCL assays, but no association could be demonstrated with the clinical variables studied. Although it might correspond to an epiphenomenon related to the triggering intestinal infection, a pathogenic role cannot be discarded and additional studies should be performed.

Antibodies, Anticardiolipin↗
PubMed1997

Immunohistochemical localization of IL-8 and TGF-beta in streptococcal glomerulonephritis.

Acute poststreptococcal glomerulonephritis (APSGN) is characterized by diffuse glomerular hypercellularity, primarily as a result of accumulation of neutrophils (exudative glomerulonephritis), increase in intrinsic glomerular cells, and transient pathological mesangial matrix expansion. Cytokines and growth factors are supposed to play an important role as mediators of inflammation and as progression factors in various renal disorders. Interleukin-8 is a recently described cytokine, defined as a selective activator and chemoattractant of polymorphonuclear leukocytes (PMNL) and transforming growth factor (TGF)-beta plays a central role in the accumulation of pathological extracellular matrix in glomerulonephritis. This study analyzed the biopsies of ten patients with APSGN, using immunohistochemistry (avidin-biotin complex/horseradish peroxidase method) using monoclonal antibodies anti-IL-8, anti-TGF-beta 1, beta 2, beta 3. Controls consisted of non-immune mouse serum, or anti-TGF-beta preabsorbed with human recombinant TGF-beta. Compared with normal renal tissue, and minimal change disease, an increased glomerular IL-8 and TGF-beta staining was observed in all of the biopsies. Furthermore, in one patient, we observed a weak deposit of TGF-beta in tubulointerstitium. Immunoreactive IL-8 and TGF-beta in glomeruli was correlated with light microscopic and clinical features. There was a significant association (P < 0.05), between IL-8 glomerular immunoreactivity and neutrophil infiltration and between TGF-beta glomerular staining and mesangial matrix expansion. Otherwise, there was no correlation with the mesangial cellularity. It was concluded that increased protein expression of IL-8 and TGF-beta are observed in APSGN and may play a role in the acute glomerular inflammation.

Adolescent↗
PubMed1995

Decreased platelet counts and decreased platelet serotonin in poststreptococcal nephritis.

Mean platelet survival time in patients with acute poststreptococcal glomerulonephritis (APSGN) is reduced to 50-60% of the control values, and glomerular deposits of platelet factor 4 are found in these patients. In order to investigate further systemic platelet changes of pathogenic, clinical or prognostic significance, we measured the platelet serotonin (5-HT) content and the blood platelet counts during the 1st week of the disease in 27 patients with APSGN. Platelet 5-HT was significantly reduced in patients with APSGN as compared with patients with impetigo without glomerular involvement (785 +/- 54 vs. 1,329 +/- 94 ng 5-HT/10(9) platelets; p < 0.001). Similarly, the mean blood platelet count was reduced to 247 +/- 16 x 10(3) as compared with 303 +/- 14 x 10(3) in the controls (p < 0.05). Thirteen (48%) of these patients had individual values of platelet 5-HT lower than the 95% confidence interval calculated in the control group. No significant correlation was observed between the concentration of 5-HT and either the severity of the disease judged by the amount of urinary protein excretion and the serum creatinine value or the presence of circulating immune complexes. Significant correction of the platelet 5-HT content (to 1,180 +/- 111 ng/10(9) platelets; p < 0.01) and of the platelet counts (to 309 +/- 21 x 10(3); p < 0.01) were observed in the longitudinal study at least 2 weeks later. Platelet activation, with secretion of granular content and increased consumption, may explain these findings. Additionally, the reduced mean age of the circulating platelets could contribute to their decreased 5-HT levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

[Hemolytic uremic syndrome in childhood: study of several factors potentially related with its genesis].

We measured circulating immune complexes, tumor necrosis factor and antineutrophil cytoplasmatic antibodies in sera coming from 25 patients during the acute reactant phase of the classical form of hemolytic uremic syndrome, aiming to elucidate a potential participation of these parameters in the pathogenesis of the disease. Circulating immune complexes were elevated in the 18 patients in whom they were measured. Tumor necrosis factor was not elevated and antineutrophil cytoplasmatic antibodies were not detected. It is concluded that these results rule out the participation of antineutrophil cytoplasmatic antibodies in the pathogenesis of the disease and that the role of circulating immune complexes, although elevated, remains undefined.

Antigen-Antibody Complex↗
PubMed1987

Renal function in full-term newborns following neonatal asphyxia. A prospective study.

A prospective study of full-term infants with neonatal asphyxia was performed to evaluate possible alterations in renal function. Twenty-one newborns with an Apgar score less than or equal to 3 at 1 minute after birth and a control group of 20 normal infants were included. Oliguria of 12 hours or more (less than 1 ml/Kg/h) during the first 24 hours after birth was considered indication for a volume challenge test and use of diuretic. The study of renal function was effected between 24 and 48 hours after birth for asphyxiated and control infants (Period I), and was repeated between 48 and 72 hours (Period II) for the asphyxiated group only. Intrinsic acute renal failure was diagnosed in two patients, one of whom died. In 10 cases, prerenal oliguria responded promptly to volume expansion with improvement of biochemical indices in Period II. In nine cases, urine volume was not altered, and all functional parameters were comparable with those of control.

Acute Kidney Injury↗
PubMed1986

Incidence of circulating immune complexes in patients with acute poststreptococcal glomerulonephritis and in patients with streptococcal impetigo.

In an attempt to further study the possible contribution of circulating immune complexes (CIC) in the pathogenesis of acute poststreptococcal glomerulonephritis, 61 patients with APSGN were studied during the first three weeks of the disease, and 13 patients with noncomplicated streptococcal impetigo as a control group. C1q solid phase ELISA and Conglutinin (K) solid phase ELISA were used to measure the levels of immune complexes. The incidence of CIC in a single serum sample from patients with APSGN was 48%. Elevated levels of immune complexes were found in 46% of the patients with streptococcal impetigo. The absolute levels of CIC were comparable in both groups of patients. No correlation was found among the presence of CIC and the clinical, immunoserological or pathological findings of the disease. Our results do not support the hypothesis that trapping of the circulating immune complexes play an important role on the renal injury poststreptococcal infection. Instead, we suggest that CIC are an epiphenomena present in APSGN, and may represent rather a systemic inflammatory immune response in patients with group A streptococcal infection.

Acute Disease↗
PubMedDate not supplied

[Influence of gestational age and postnatal kidney maturation on the kinetics of gentamicin].

The current schedule for gentamicin administration to newborn infants, in doses of 2.5 mg/kg every twelve hours during the first week of life was evaluated in pre-term newborns under 35 weeks of gestational age (GA). Pharmacokinetic studies in steady state conditions were performed at the third and seventh days of therapy (periods A and B respectively) in nine pre-term (GA 30 to 34 weeks) and ten full-term newborns. Minimal gentamicin blood concentrations at period A were 1.96 +/- 0.32 micrograms/ml in term newborns and 2.51 +/- 0.48 micrograms/ml in pre-term infants (p less than 0.005) and, at period B, 1.49 +/- 0.37 micrograms/ml and 2.33 +/- 0.34 respectively (p less than 0.001). Gentamicin excretion showed good correlations with gestational age (r: 0.654; p less than 0.005) and creatinine clearance (r: 0.628; p less than 0.005).

Creatinine↗