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Biomedical subjects

J Herrera

Publications and source records attributed to J Herrera.

At least 55 records · Page 3Linked to original sources
PubMed1998

Clinical, cytogenetic, and molecular testing of Argentine patients with retinoblastoma.

PURPOSE: The purpose of this study is to determine the clinical, chromosomal, and molecular characteristics of Argentine patients with unilateral and bilateral retinoblastoma. STUDY DESIGN: Eighty-six patients belonging to 82 families were studied; 59% of them were examined during the first year of life. Leukocoria was the most common reason for consultation. Other presenting signs were strabismus and glaucoma. Enucleation of the affected eye was performed in 85% of the cases and the complication rate was 13%. RESULTS: An appropriate therapy allowed the survival of 84 of the 86 patients. Two children with malformations and growth retardation had an abnormal karyotype with a deletion in 13q14. Segregation analysis of polymorphic sites within the retinoblastoma gene and the parental origin of the allele lost in the tumor were analyzed in 30 of the 82 families. Five mutant alleles transmitted through the germline and six de novo germline mutant alleles were identified in 12 patients with hereditary retinoblastoma. Most de novo germline mutant alleles were paternally derived. Molecular analysis of nonhereditary retinoblastoma showed loss of heterozygosity in three of eight cases. From these, two maternal alleles and one paternal allele were lost, thus not indicating a significant difference in the parental origin for the lost allele. CONCLUSIONS: These data are useful for deoxyribonucleic acid diagnosis of susceptibility to retinoblastoma in relatives of hereditary patients, even if mutations have not been identified.

Alleles↗
PubMed1998

Stimulation of tubular secretion of creatinine in health and in conditions associated with reduced nephron mass. Evidence for a tubular functional reserve.

BACKGROUND: The increment in glomerular filtration rate (GFR) after a protein load has been taken to reflect the renal reserve capacity; however, this response is preserved in end-stage kidney disease. Tubular secretion of creatinine is increased in relation to the GFR in renal failure, but little is known about the tubular functional response to stimulation despite the fact that tubulointerstitial lesions are always pre-eminent in chronic renal damage. Therefore we decided to compare the urinary creatinine excretion (UcrV) and tubular secretion of creatinine (TScr) induced by a test meat meal in normal individuals and in individuals with reduced nephron mass. METHODS: We studied 12 normal subjects, seven healthy uninephrectomized (kidney donors) and eight patients with chronic renal disease (serum creatinine ranging from 212.2 to 486 micromol/l). They had been on a standard diet for 5 days before the studies. The test meal provided 80 g of animal protein. Three baseline and four stimulated (post-meal) 30-min simultaneous inulin and creatinine clearances were carried out. RESULTS: We found that normals increased more than twice the UcrV (post-meal=329.5 +/-SEM 13.1 nmol/min/kg) and 3.4 times the TScr (114.4+/-12.7 nmol/min/kg) after the test meal. In contrast, patients were unable to raise their baseline values (P<0.001), despite a normal increment in GFR. The data in kidney donors fell between normals and patients. Strong correlation existed between the stimulated (but not the baseline) TScr (P=0.003) and GFR and between UcrV post-meal/pre-meal ratio and GFR (P<0.0001). CONCLUSION: The increment in TScr resulting from a protein meal is related to the functioning nephron mass. Evaluation of this increment could have potential clinical relevance.

Adult↗
PubMed1998

[Molecular diagnosis in an Argentinian family with multiple endocrine neoplasia type-1 (MEN-1)].

MEN-1 is a hereditary autosomal dominant syndrome characterized by the involvement of parathyroid glands, pancreatic islet cells and anterior pituitary gland. Today molecular genetics permit gene carrier analysis to compare the data obtained with the clinical biochemical tests. The twenty living members of the first, second and third generation of a family with MEN-1 were studied to determine the presence of genetic markers in MEN-1 loci 11q13, by linkage analysis and in affected individuals by biochemical tests and clinical examination. Two very informative polymorphic markers immediately flanking the MEN-1 gene on chromosome 11 band q13 were detected: PYGM and D11S987, haplotypes segregated by two members of the second generation, inherited from their father and two of the third generation: the affected one and one presymptomatic. The third generation had the affected member with renal stones and elevated PTH, PRL and glucagon. The presymptomatic carrier of MEN-1 allele showed elevated PTH. Among the members who inherited the normal allele we found one with elevated gastrin, one with elevated glucagon and one with elevated PTH, all asymptomatic. Of one Argentine family studied, molecular diagnosis allowed us to detect one presymptomatic carrier in the members at risk. As suggested by the available literature, accuracy of molecular diagnosis seems to make it the test of choice to exclude those members at risk for MEN-1 inheriting the normal allele.

Adult↗
PubMed1997

The continuous performance test, identical pairs version (CPT-IP): III. Brain functioning during performance of numbers and shapes subtasks.

The numbers and shapes subtasks of the CPT-IP are difficulty-matched measures of independent aspects of attentional skill that have been used to differentiate the impairments of schizophrenics and major depressives. Previous studies suggest that they tap into lateralized aspects of attentional performance. To investigate this hypothesis, seven subjects free of psychiatric illness were presented with these CPT-IP subtasks during a SPECT procedure. Subtasks--4-digit number strings and nonsense shapes--were administered on successive weeks, in counterbalanced order, simultaneous with administration of 10 mCi 99mTc HMPAO. Scanning took place after 10 min of test performance. Quantitative data were extracted from each scan via a semi-automated region of interest (ROI) analysis which defined eight cortical and four subcortical ROI on each of five transverse slices. Data for each ROI were normalized and compared between task conditions. Results indicate that the two tasks produce different patterns of functioning within two general areas of the brain. First, during Numbers task performance, left-sided activity was increased on multiple transverse slices in an anterior subcortical region that incorporated the anterior cingulate, frontal white matter, and much of the basal ganglia. Left-sided activity was also increased in a posterior subcortical region including the left side of the thalamus. Lateralization of function, defined as relative activity on the left and right sides, changed within these regions across tasks, but primarily as a result of the contribution of increased or decreased activity on the left side alone. Second, relative perfusion to occipital regions, bilaterally, was more extensive during the Shapes task. These results suggest that subtle alterations in stimulus parameters can affect activation patterns in regions that are critically associated with task performance. They also suggest that the Numbers task may provide more robust activation of anterior attention systems, that may better discriminate the functioning of these systems in normal and psychopathological groups.

Adult↗
PubMed1997

[Giant gastric stromal tumor simulating a focal hepatic lesion].

Gastrointestinal stromal tumors (GIST), are unusual malignancies regarded for many years as being basically of smooth muscle nature and designated as leiomyomas, leiomyosarcomas or leiomyoblastomas. Histogenesis has been debated, though it is presently accepted that they are characterized by poorly differentiated cells, including tumors showing differentiation towards smooth muscle, neural elements, dual differentiation or lack of differentiation. Another group with ultrastructural and immunohistochemical features similar to those of gastrointestinal autonomic plexus has been described and designated as GAN tumors. Diagnosis and classification of these tumors are not possible using conventional pathological techniques, making ultrastructural and immunohistochemical studies necessary. Accurate classification is clinically essential due to prognostic implications. GIST present with few clinical symptoms even in cases of large tumors and are quite often incidentally found during surgical procedures or in postmortem studies. We report a case of a giant gastric stromal tumor showing differentiation towards smooth muscle which presented as a focal hepatic lesion.

Adult↗
PubMed1996

Genotoxic effects of metronidazole.

Metronidazole (MTZ) is an effective agent used in the treatment of parasitic infections. Its genotoxic effects have been shown in a variety of prokaryotic systems; however, negative results have been reported in human in vivo studies. Due to its wide spread use, a study was performed to evaluate the chromosomal aberration frequencies in peripheral blood lymphocyte cultures from 10 individuals, before and after metronidazole treatment. A significant increase in the percentage of cells with chromatid and isochromatid breaks was observed after metronidazole treatment (1500 mg per day for 10 days). The percentages of cells with aberrations did not correlate with the levels of MTZ found in plasma. Individual variability was observed with respect to both the induction of aberrations and the concentration of MTZ in plasma. They could represent differences at the metabolic level, since metronidazole is known to be biotransformed by a polymorphic P450 cytochrome, and its metabolites have shown mutagenic activity.

Adolescent↗
PubMed1996

Pseudoaneurysm of the inferior epigastric artery. Pathogenesis, diagnosis, and treatment.

We present a new case of pseudoaneurysm of the abdominal wall, subsidiary to the inferior epigastric artery, associated with the use of discharge sutures. Pseudoaneurysms are a well-known complication of surgery, puncture, or trauma. Pseudoaneurysms of the inferior epigastric artery are very infrequent. We know of only two cases in the literature. In both cases, the pseudoaneurysm was associated with the use of discharge sutures. We discuss its pathogenesis, diagnosis, and treatment.

Adult↗
PubMed1995

Heroin addicts and methadone treatment in Albuquerque: a 22-year follow-up.

All heroin addicts who registered for methadone treatment in Albuquerque in 1969-1971, 1019 in all, were the subjects of this follow-up study, conducted in 1991-1993. The cohort was almost entirely of Hispanic (Chicano) ethnicity, 86% male, with median age 27 at entry. We located 776, dead or alive, and we were able to interview 243 concerning many aspects of their lives. At least one-third of the original group had died during the 22-year period, representing standard mortality ratios 4.0 for males and 6.8 for females. Drug overdose, violence, alcohol, or suicide accounted for nearly all deaths of which the causes were known. Despite the availability of treatment, including methadone maintenance, both heroin use and criminality continued at a high rate. Of the 428 known survivors, 48% were currently enrolled in a methadone program after 22 years. They were using significantly less heroin, alcohol, and other drugs (except nicotine) than those not on methadone. Similar beneficial effects of methadone maintenance were reported retrospectively at interview. Our findings offer an insight into heroin addiction as a chronic lifelong relapsing disease with a high fatality rate.

Adolescent↗
PubMed1995

The therapeutic approach to the control of hypertension. Its impact on health policy.

The pharmacologic approach to the control of hypertension must consider both the clinical perspective and the Public Health approach policy in which social costs have to be balanced against benefits to the entire population. Cost-effectiveness analysis are at the core of decisions taken within this frame of reference. The issue of cost-effectiveness of preventive and therapeutic measures are crucial in the case of less developed countries. An analysis of studies undertaken in Mexico leads to the conclusion that, from a Public Health perspective, a program for the control of hypertension with a strong emphasis on drug therapy is likely to require a significant proportion of the health budget. Therefore, more emphasis must be placed on primary prevention based on modifications of life style.

Antihypertensive Agents↗
PubMed1995

[Safety in the switching traditional cyclosporin to microemulsion cyclosporin in stable renal transplant patients: cooperative study].

In an open clinical trial we assessed the tolerance and safety of the 1:1 conversion of traditional cyclosporine A (CyA) to a new cyclosporine formulation based on a microemulsion technology (CyN) in 18 patients with stable renal allografts. 56% patients were female. Median patient age was 40.9 +/- 3.2 years (range 18 to 65). Renal transplantation was performed in 24.1 +/- 4.6 months (range 6 to 67 months), prior to the beginning of the study, and 67% of the transplants were from cadaveric donor. The most frequent underlying renal disease was glomerulonephritis (44.4%). None of the patients entering the study were withdrawn prematurely. After 2 weeks of observation for graft function stability, the study was divided in two phases: I: during 4 weeks the patients received CyA traditional at fixed doses (Mean dose administered 3.056 +/- 0.25 mg/Kg/d) and II: during the consecutive 6 weeks with conversion to CyN, with doses adjustment as required (Mean dose 2.887 +/- 0.21 mg/Kg/d). Clinical events, adverse reactions and laboratory parameters were evaluated. Levels of 100-200 ng/ml measured by monoclonal specific fluorescence polarization immunoassay were considered appropriate. There were no significant changes in physical examination and laboratory parameters between phases. The incidence of adverse reactions reported in phase I was only gingival hypertrophy (5%) which persisted in phase II, qualified as probably related to the cyclosporine, and in phase II tremor in 17%, qualified as definitively related. Both drugs were well tolerated and there was no report of acute rejection during the study. We conclude that the tolerance and safety of the 1:1 conversion of CyA to CyN were confirmed by our results, and considering the improved pharmacokinetic properties of the second, the microemulsion presentation will be used preferentially as immunosuppressive drug in the treatment of stable kidney transplant patients.

Adolescent↗