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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
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↗
PubMed1992

Prediction of steroid responsiveness in the idiopathic nephrotic syndrome using urinary retinol-binding protein and beta-2-microglobulin.

OBJECTIVES: To determine the prevalence of early proximal tubular dysfunction, measured by urinary excretion of retinol-binding protein (RBP) and beta-2-microglobulin (B2M), in patients with the idiopathic nephrotic syndrome and to investigate the value of these tests in predicting steroid responsiveness. DESIGN: Before-after trial with 8-week treatment period. SETTING: Tertiary referral center. PATIENTS: Sequential sample of 37 patients with the idiopathic nephrotic syndrome caused by minimal change disease, focal segmental glomerulosclerosis, or mesangial proliferative glomerulonephritis. INTERVENTION: All patients were treated with prednisone as one dose of 1 to 1.5 mg/kg body weight per day for 8 weeks. MEASUREMENTS: Urinary RBP was measured by an immunoenzymometric assay and B2M, by an enzyme-linked immunosorbent assay. Remission of the nephrotic syndrome after steroid treatment was the main outcome variable. RESULTS: Elevated levels of urinary RBP and B2M before treatment were detected in 65% and 75% of the patients, respectively. Median urinary RBP and B2M, before treatment, were significantly higher in the steroid-unresponsive group than in the responsive group (P less than 0.01). In the steroid-responsive group, urinary RBP and B2M levels decreased significantly after remission (P less than 0.01). In the steroid-unresponsive group, the likelihood ratios for urinary RBP greater than 4000 micrograms/g creatinine and for B2M greater than 3000 micrograms/g creatinine were 3.8 and 3.0, respectively. The probability was 100% that values of RBP of less than 1300 micrograms/g creatinine and B2M of less than 130 micrograms/g creatinine were from steroid-responsive patients. Multivariate analysis confirmed that higher urinary levels of RBP and B2M were associated with a lower likelihood of steroid responsiveness, independent of age and histologic diagnosis. CONCLUSIONS: Proximal tubular dysfunction is frequent in patients with the idiopathic nephrotic syndrome. Pretreatment urinary RBP and B2M levels may be helpful in identifying nephrotic patients who are more likely to be responsive to steroids.

Adolescent↗
PubMed1990

Immunocytochemical features of the vestibular nuclei in the monkey and cat.

Immunocytochemical studies of the vestibular nuclei (VN) were done in the squirrel monkey and cat using polyclonal antisera. Brain stem sections were processed using the Avidin-Biotin peroxidase complex with diaminobenzidine as the chromagen. Choline acetyltransferase immunoreactivity (ChAT-IR) was most prevalent in the caudal medial (MVN), inferior (IVN) and peripheral superior (SVN) VN. Nearly all cells of groups x and z were ChAT-positive. None of the giant cells of the lateral vestibular nucleus (LVN) was ChAT-IR. Glutamate immunoreactivity (GLU-IR) was abundant in all VN and in cells of the vestibular ganglion (VG). Gamma-aminobutyric acid immunoreactivity (GABA-IR), was found in cells of rostral MVN, cell group y and in granules about giant cells in dorsal LVN. Substance P immunoreactive (SP-IR) was present in a small cells in MVN, IVN and the VG and in granules surrounding all large cells in LVN in both monkey and cat; SP-IR granules were most intense in ventral LVN in the monkey. Some cells in the dorsal parts of the fastigial nucleus (FN) were outlined by SP-IR granules in both species. Leucine-enkephalin immunoreactivity (ENK-IR) was identified only in granules surrounding cells of group x in the monkey. GLU was the only immunoreactive substance found in the giant cells of LVN. The disposition of ChAT-IR in the VN suggested participation in commissural systems, as well as projections to spinal cord and/or cerebellum. Small GABA-IR neurons in MVN probably represented both commissural and projection neurons; GABA-IR granules about cells in dorsal LVN and some cells in MVN and SVN appeared to represent Purkinje cell (PC) terminals. SP-IR granules surrounding cells in ventral LVN appeared to represent terminals of small SP-positive VG cells. The source of SP-IR granules around cells in dorsal LVN and some cells in FN and SVN remains unknown, but these fibers may originate from portions of the reticular formation known to contain large numbers of SP-positive neurons.

Animals↗
PubMed1990

Immunoassays of secretory IgA and secretory component.

1. A sandwich-type enzyme-linked immunosorbent assay (ELISA) is described for quantitation of secretory IgA (sIgA) in human serum, as well as an ELISA and a radioimmunoassay (RIA) for measurement of secretory component (SC) in human serum. Samples were reduced and alkylated prior to the measurement of SC. 2. Healthy individuals (N = 53) presented low levels of SC (median, 0.9 mg/l). The protein levels were significantly elevated when compared with the controls, in sera of women during the second (N = 31; median, 1.5 mg/l) and third (N = 35; median, 4.2 mg/l) trimesters of pregnancy and in sera of patients with alcoholic cirrhosis (N = 38; median, 2.4 mg/l) and acute viral hepatitis (N = 25; median, 2.4 mg/l). SC levels of women in the first trimester of pregnancy (N = 24; median, 0.5 mg/l) did not differ from the controls. 3. sIgA levels were also significantly elevated when sera of women in the third trimester of pregnancy (N = 41; median, 25.4 mg/l) and sera of patients with alcoholic cirrhosis (N = 32; median, 75.0 mg/l) or acute viral hepatitis (N = 38; median, 28.5 mg/l) were compared with controls (N = 49; median, 9.0 mg/l). Women in the first (N = 25; median, 7.7 mg/l) and second (N = 29; median, 10.2 mg/l) trimester of pregnancy did not present levels statistically different from the controls. 4. The results obtained for SC by RIA and ELISA were positively correlated (rs = 0.88; P less than 0.001). sIgA levels determined by ELISA were also positively correlated with the results of RIA-SC (rs = 0.77; P less than 0.001) or ELISA-SC (rs = 0.79; P less than 0.001). 5. The assays described are specific, relatively simple to perform, and can be useful for the study of the secretory immune system.

Adult↗
PubMed1990

Exposure to hydrocarbons and rapidly progressive glomerulonephritis.

1. A case-control study of the relationship between the regular exposure to hydrocarbons and rapidly progressive glomerulonephritis (GN) was carried out in São Paulo, Brazil. Regular exposure was defined as 1 h or more weekly for 3 consecutive months or longer. We studied 17 patients with rapidly progressive renal failure and biopsy-proven crescentic GN and 34 matched hospital controls. 2. We found an increased risk of rapidly progressive GN associated with exposure to organic solvents (relative risk = 5.00; 95% confidence interval = 1.14 to 22.00). The frequency of exposure to solvents was 52.9% among the patients and 17.7% among the control subjects (P less than 0.05). However, no statistically significant increased risk was detected in those patients who had been exposed to fuels (relative risk = 3.25; 95% confidence interval = 0.76 to 13.89); the proportion of exposure to fuels was 47.1% among the patients and 20.6% among the control subjects. 3. Renal histologic findings suggest that immune complex mediated injury as well as a direct glomerular toxic effect may participate in the pathogenesis of rapidly progressive GN associated with hydrocarbon exposure.

Adolescent↗
PubMed1988

Characterization of circulating immune complexes detected by monoclonal rheumatoid factor and conglutinin radioimmunoassays in SLE nephritis.

By utilizing a monoclonal rheumatoid factor (mRF) and bovine conglutinin (K) in radioimmunoassays, ICs detected in sera of patients with lupus nephritis were partially characterized. The mRF-RIA detected high levels of ICs in 86.9% of patients with active SLE and in only 22.7% of patients with inactive disease. Positive association was observed with clinical scores and significant negative correlation was found with serum levels of C1q, C3 and C4. The mRF-reactive ICs were shown to be cryoprecipitable and analysis by gel filtration through Sephacryl S-300 disclosed a material eluting between IgM and IgG, being dissociated in acidic pH. On the other hand, no association could be demonstrated between levels of ICs detected by K-RIA and clinical activity. Positivity in this assay was only 8.7% and 31.8% for active and inactive groups. Differently from the ICs detected by mRF-RIA, the K-reactive material was not precipitated by 3.5% PEG, nor by centrifugation in the cold, and EDTA did not reduce the binding of IgG to K in positive sera. The reactive IgG in Sephacryl S-300 chromatography eluted in the same position as monomeric IgG both in neutral and dissociating conditions. No C3 could be detected in ICs reactive in both assays.

Antibodies, Monoclonal↗
PubMed1988

Glomerular hematuria in diabetics.

Three hundred and twenty outpatients with diabetes mellitus (DM) were studied to evaluate the prevalence, origin (glomerular or nonglomerular), significance and possible association of glomerular hematuria (GH) with other clinical and laboratory features. In patients with 24 h proteinuria equal or superior to 500 mg, hematuria was seen in 16 out of 22 (72.7%); for those with 24 h proteinuria between 150 and 500 mg 5 out of 23 (21.7%) had hematuria, and in the general population of diabetics studied hematuria was present in 47 patients (14.7%). It was glomerular in 43 (13.4%) patients and nonglomerular in 4 (1.3%). Red blood cell casts were observed in 15 (34.9%) out of the 43 patients with GH. Ten out of 31 patients (32.3%) with GH, for whom 24 h proteinuria was available, had negative proteinuria in a 24 h urine when analyzed by routine methods. In 18 patients with GH, clinical and laboratory findings that could suggest a second form of glomerulopathy--nondiabetic--were negative. Renal biopsy in 9 of them showed only diabetic glomerulosclerosis. We have observed a significant association between GH and the male sex (p less than 0.001), high serum creatinine levels (p = 0.0002) and 24 h proteinuria greater than 150 mg (p less than 0.001). GH was more frequent among males with DM lasting more than 10 years (p less than 0.001) and among those with retinopathy (p less than 0.001). There was no association between GH and age, type of DM, insulin requirement or hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Inherited C3 deficiency of the complement system.

1. We report a patient homozygous for C3 deficiency and several heterozygotes from the same family. Upon follow-up, the homozygote was found to suffer several severe bacterial infections, whereas all the heterozygotes were clinically healthy. 2. C3 was undetectable in the homozygous patient, CH50 was very low and factor I was present. Serum capacity to generate chemoattractant stimuli for peripheral leucocytes was similar to that of normal adults as was also observed for one of the heterozygotes. Serum capacity to opsonize yeast was reduced in the presence of autologous and homologous (normal adult) cells. The CH50 levels of heterozygous patients were within the lower range of normality. 3. The parental consanguinity and the homozygosis state observed here are classical signs of recessive autosomal inheritance. However, the lower or below normal C3 levels detected in parents and relatives point to a co-dominant inheritance of gene S with respect to the "null" gene. 4. C3 polymorphism presented a predominantly "slow" pattern in most family members, which, together with the low C3 levels, indicates the expression of S-allotypes.

Antibodies, Anti-Idiotypic↗
PubMed1987

Comparisons of the immunocytochemical localization of choline acetyltransferase in the vestibular nuclei of the monkey and rat.

Immunocytochemical studies of the brainstem were done in the squirrel monkey and rat using the same polyclonal antisera for choline acetyltransferase (ChAT). Cells immunoreactive for ChAT (ChATir) were evident in large numbers in visceral and motor cranial nerve nuclei in both species, but virtually no ChATir cells were seen in the vestibular nuclear complex of the rat. In the monkey ChATir cells were distributed in caudal parts of the medial (MVN) and in dorsal parts of the inferior (IVN) vestibular nuclei. Only a few immunoreactive cells were seen in the rostral MVN and none were found in cell group f of the IVN. Nearly all cells of group z and x, which do not receive primary vestibular afferents, were immunoreactive to ChAT. None of the cells in the superior and lateral vestibular nuclei, cell group y, the infracerebellar nucleus or the interstitial nucleus of the vestibular nerve were immunoreactive for ChAT. Cells immunoreactive to ChAT were present in large numbers in the rostral part of the nucleus prepositus in the monkey, but not in the rat. The relatively small number and distribution of ChATir cells in the MVN suggested they could constitute only a small fraction of the MVN neurons that contribute to a massive commissural system. Significant differences in cholinergic vestibular neurons appear to exist between the rat and the monkey.

Animals↗
PubMed1987

Vestibular and cochlear efferent neurons in the monkey identified by immunocytochemical methods.

Attempts were made to identify vestibular (VEN) and cochlear (CEN) efferent neurons in the squirrel monkey using retrograde transport of horseradish peroxidase (HRP) and immunocytochemical methods. HRP implants in the ampulla of the lateral semicircular duct retrogradely labeled cells of VEN bilaterally and some cells of CEN. VEN located lateral to the rostral part of the abducens nucleus formed a compact collection of cells, all of which were immunoreactive only to antisera for choline acetyltransferase (ChAT). CEN, identified by immunoreactivity to ChAT were located at the hilus of the lateral superior olive (LSO), along the lateral border of the LSO and sparsely near lateral parts of the ventral trapezoid nucleus (VTN). A small number of cells and fibers near the border of the VTN and lateral to the LSO were immunoreactive for leucine enkephalin (L-ENK). Fibers immunoreactive for L-ENK also were identified in the hilus of the LSO. No cells of the superior olivary complex were immunoreactive for antisera to ChAT, L-ENK, substance P, gamma-aminobutyric acid or glutamic acid decarboxylase. Cells of VEN and CEN can be identified by their immunoreactivity to ChAT, and some cells and fibers of CEN also contain L-ENK.

Animals↗
PubMed1986

Radioimmunoassay for IgG and IgM rheumatoid factors.

The present paper describes two solid phase radioimmunoassays for detecting IgG and IgM rheumatoid factors (RF). Basically, serum rheumatoid factors were bound to rabbit IgG previously adsorbed to wells of flexible microtiter plates and quantitated after the addition of 125I-Fab anti-human gamma Fd for the IgG-RF assay or 125I-IgG anti-mu chain for the IgM-RF assay. The IgG and IgM rheumatoid factor assays were tested on 56 and 30 control sera, respectively. The upper normal limits for these assays were taken for cpm test serum/cpm control pool as 1.00 (0.76 + 0.24; X + 2SD) and 1.39 (0.73 + 0.66; X + 2SD) for IgG-RF and IgM-RF, respectively. When applied to sera of patients with rheumatoid arthritis, IgM-rheumatoid factor was detected in 15 of 15 (100%) patients, and IgG-rheumatoid factor in 15 of 17 (88%). The radioimmunoassay results for both rheumatoid factors were significantly higher for these patients than for the normal control sera (P less than 0.01).

Animals↗
PubMed1986

Detection of IgG-rheumatoid factor in sera of patients with acute poststreptococcal glomerulonephritis and its relationship with circulating immunecomplexes.

Rheumatoid factors (RF) were measured in sera from 75 patients with acute poststreptococcal glomerulonephritis (APSGN) and compared with normal controls, patients with rheumatoid arthritis in activity and acute rheumatic fever. Using two sensitive and specific solid phase radioimmunoassays, IgM-RF and IgG-RF were detected, respectively, in 15% and 32% of the patients with APSGN. A positive correlation (r = 0.37, n = 75, p less than 0.05) was obtained between serum levels of IgG-RF and circulating immune complexes determined by conglutinin assay. Chromatographic studies in serum from two patients with APSGN demonstrated that the circulating IgG-RFs were mainly free, not complexed. It is suggested that RFs, particularly of the IgG class, may participate in the pathogenesis of the renal injury in some patients with APSGN.

Acute Disease↗
PubMed1984

Egg yolk as a source of antibodies for human parathyroid hormone (hPTH) radioimmunoassay.

Chickens were immunized with synthetic hPTH peptides 1-34 and 53-84. Serum from the best responder of each group was compared with IgG obtained from yolk of eggs layed by the same chicken, showing similar properties. A simple method for purification of IgG from yolk is described, allowing the obtaining of substantial amounts of anti-hPTH IgG without the need for bleeding the animals. We conclude that: 1) egg from chickens immunized with synthetic hPTH peptides are a convenient source of antibodies against these peptides; 2) this principle should apply to any other antigen to which chickens are good responders.

Animals↗
PubMed1984

[Simultaneous determination of 4 anticonvulsant drugs by high pressure liquid chromatography (HPLC)].

We describe a sensitive and precise method for the simultaneous high pressure liquid-chromatography determination of phenobarbital, diphenylhydantoin, primidone, and carbamazepine in serum. The drugs are extracted into chloroform, dried and dissolved in the mobile phase. The drugs are eluted from a reverse-phase column with methanol/water and detected by their absorption at 214 nm. Concentrations are estimated from their peak heights. The results, when compared with those by enzyme-immunoassay, gave correlation coefficients of 0.990 for phenobarbital, 0.993 for diphenylhydantoin, 0.992 for primidone and 0.994 for carbamazepine.

Carbamazepine↗