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Biomedical subjects

F Ortega

Publications and source records attributed to F Ortega.

At least 55 records · Page 3Linked to original sources
PubMed1999

Immunogenetics of atopic asthma: association of DRB1*1101 DQA1*0501 DQB1*0301 haplotype with Dermatophagoides spp.-sensitive asthma in a sample of the Venezuelan population.

BACKGROUND: Genes linked to the major histocompatibility complex (MHC), have been implicated in atopic asthma. Asthma is highly prevalent in the Venezuelan population (estimated at 20%) and genetic markers are needed to identify populations at risk and plan intervention strategies. OBJECTIVE: To study the influence of the MHC class I and class II genes in the susceptibility to atopic asthma. METHODS: MHC-class I HLA-A, -C, -B and MHC-class II HLA-DR, -DQ, -DP gene haplotype frequencies were determined in 135 Venezuelan mestizos, 71 belong to 20 atopic asthmatic families and 64 unrelated controls. The index cases were 20 atopic asthmatics with positive skin-prick tests and specific serum immunoglobulin E (IgE) for Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f). To ascertain the genes associated with susceptibility to atopy and/or asthma, two control groups were studied, 41 non-atopic subjects with skin-prick negative test, and undetectable levels of specific IgE and 23 non-asthmatic atopic subjects with detectable specific IgE to Der p and Der f. A linkage analysis was performed in those families with two or more atopic siblings (with or without asthma). RESULTS: MHC-class I genes analysis showed that HLA-Cw7 was absent in the asthmatic patients studied, whereas the frequency of this allele was 14.3% in non-atopic controls (P = 0.0 17, PC = 0.19) and 20.8% in the atopic controls (P = 0.0066, PC = 0.07). MHC-class II gene analysis showed a significant increase of the HLA-DRB1*11 in the asthmatic patients compared with non-atopic controls (allele frequencies of 25.6 vs 4.4% P = 0.0017, PC = 0.02). There were no significant differences among asthmatic and atopic controls in the frequency of HLA-DRB1*11 (25.6 vs 17.4%). In contrast, the HLA-DRB1*1101+ haplotypes were significantly higher in asthmatics compared with atopic and non-atopic controls (19.6% vs 2.2% vs 2.3%, PC<0.05). The HLA-DRB1*1101, DQA1*0501, DQB1*0301 haplotype was found significantly increased in the patients vs non-atopic controls (15.4 vs 1.1%, PC< 0.01). The serum levels of specific IgE were detectable in both atopic asthmatics and atopic controls; however, it was higher in atopic asthmatics vs atopic controls Der p (median, 58.7 vs 2.7 kU/L, P<0.001) and Der f (median, 46.9 vs 2.7 kU/L, P<0.001). No linkage between MHC genes and mite-atopy could be documented on informative families with two or more atopic siblings. CONCLUSIONS: We have identified an association between the haplotype HLA-DRB1*1101, DQA1*0501, DQB1*0301 and atopic asthma that confers susceptibility to develop mite-sensitive asthma to atopics (relative risk, RR 8.2), and to non-atopic controls (RR = 15.8) that carry this haplotype. Conversely, the allele HLA-Cw7 was absent in the asthmatics studied and had higher frequencies in the atopic (RR = 0.05) and non-atopic (RR = 0.08) controls. Thus, it may have a protective role for developing atopic asthma in the population studied.

Adolescent↗
PubMed1999

Distortion product oto-acoustic emissions in Andean children and adults with chronic lead intoxication.

Neuroauditory disorders and sensory-neural hearing loss have been suggested as possible etiologic factors in the neurodevelopmental learning disabilities attributed to lead (Pb) intoxication. However, studies relating hearing loss to Pb poisoning have presented disparate results, suggesting that auditory sensitivity may not be a reliable marker of Pb intoxication. Oto-acoustic emissions, sounds that can be recorded non-invasively from the ear canal and are preneural responses of the outer hair cells of the inner ear, have been found to be diminished in ears exposed to some toxic agents. In the current study, distortion product oto-acoustic emissions (DPOAEs) were obtained from 28 ears of 14 children and 10 ears of 5 adults living in a highly Pb-contaminated environment in remote villages in the Andes Mountains of Ecuador. Blood lead (PbB) levels for the children (ages: 5-14 years) ranged from 33.4 to 118.2 microg/dl (mean: 51.5; SD: 22.9 microg/dl), or 3-12 times higher than the U.S. Centers for Disease Control and Prevention's toxic level of 10 microg/dl. The PbB levels for the adults ranged from 19.2 to 55.7 microg/dl. Despite the high PbB levels, the children had normal hearing thresholds, and DPOAEs were present for the children at the following f2 frequencies: 1187, 1500, 1906, 2406, 3031, 3812, 4812 and 6031 Hz. Although there was a tendency for the children to have diminished DPOAEs, no consistent correlation of DPOAEs with PbB level was found. The adults had diminished DPOAEs that were consistent with their observed, probably noise-related hearing loss. Contrary to some reports in the literature, the current results show no unequivocal clinical or subclinical evidence that high PbB levels have a toxic effect on the cochlea.

Adolescent↗
PubMed1999

[PET-FDG in thyroid cancer with high thyroglobulin levels and negative 131-I scan. A case report].

The value of whole body PET-FDG in the evaluation of metastases has been demonstrated in a wide variety of tumors. In this report, we present the case of a patient with antecedent of papillary thyroid carcinoma, who was operated twelve years ago, and submitted to an ablative dose of residual thyroid tissue through 131I, being the levels of thyroglobulin normals. After twelve years of evolution, the patient refers bag pain and respiratory trouble, appearing in the CT image suspicious of metastases in right pulmonary base. The levels of thyroglobulin were shown increased, being the 131I scan negative. A whole body PET-FDG study was performed in order to exclude metastases of his malignant process, showed multiple high FDG uptake focus in brain, cerebellum, neck, chest, lymphatic nodes and bone, suggestive of dedifferentiated disease These findings were confirmed subsequently in the clinic evolution. Therefore, whole-body PET-FDG is a complementary diagnostic technique for study patients with CDT (Thyroid Differentiated Carcinoma) with 131I scan negative and rising thyroglobulin levels.

Aged↗
PubMed1999

Immunophenotypic and DNA content characteristics of plasma cells in multiple myeloma and monoclonal gammopathy of undetermined significance.

In the present paper we review the immunophenotypic characteristics of plasma cells (PC) and the PC DNA contents from multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS), and its value for the differential diagnosis between both entities. The strong reactivity for CD38 and the positivity for CD138 are the two best markers for identifying PC. Myelomatous PC display an heterogeneous phenotype consistent with the fact that the neoplastic clone is able to undergo a certain degree of differentiation. In addition, PC from MM patients usually lack surface expression of B-cell associated antigens and frequently display reactivity for markers which are not restricted to the B-cell lineage. In MGUS patients, two clearly defined and distinct PC subpopulations can be identified. One of these PC subpopulations shows phenotypic characteristics identical to those of normal PC, including a very strong reactivity for the CD38 antigen, intermediate/low light scatter characteristics and positivity for CD19, in the absence of CD56, and corresponds to the residual normal bone marrow PC. The second PC subpopulation shows an immunophenotype similar to that of myelomatous PC, characterized by a slightly lower reactivity for CD38 and strong CD56 expression, on the absence of positivity for CD19, these PC corresponding to the clonal counterpart. Using a simultaneous staining for PC and DNA, around 60% of MM and 73% of MGUS patients display DNA aneuploidy, the majority of them being hyperdiploid. However, in contrast to MM patients, in MGUS patients two clearly different PC subsets can be discriminated in most cases (73%): a diploid and an aneuploid (hyperdiploid) subset, corresponding to normal and clonal PC, respectively. Upon comparing hyperdiploid with diploid patients in MM, the former display a better prognosis, in line with the higher incidence of DNA hyperdiploidy in MGUS. A clear correlation between the percentage of S-phase PC and several prognosis features of MM has been found. In spite of these findings, no significant differences in the percentage of pathological S-phase PC are detected between MM and MGUS patients. Regarding the differential diagnosis between MGUS and MM, multivariate analysis shows that the ratio between the number of clonal and normal residual PC is the best single parameter.

Antigens, Neoplasm↗
PubMed1999

[Peripheral muscle strength in stable COPD patients: correlation with respiratory function variables and quality of life].

The aim of this study was to assess peripheral muscle strength in patients with chronic obstructive pulmonary disease (COPD) using a simple test and to look for correlation with function variables, physiological strength variables and quality of life parameters. Twenty-three COPD patients with moderate to severe air-flow limitation (FEV1 = 39 +/- 12%) in stable phase but displaying inability to carry out daily tasks were enrolled. Peripheral muscle strength was assessed in all patients by measuring the maximum load in a single repetition of five simple upper and lower extremity exercises performed at a multi-gymnastics station. Results were compared to respiratory function variables (FVC, FEV1, FEV1/FVC and gasometry), to results of an exercise test on a cycle ergometer with monitoring of respiratory gases (VEmax, VO2max and Wmax), to endurance (minutes) to dyspnea (Mahler's scale) and to quality of life (Chronic Respiratory Disease Questionnaire-CRDQ). No relation between functional parameters and endurance in minutes was found. Minute ventilation (VE) proved to be significantly related to oxygen intake (VO) and maximum work in the stress test. Dyspnea on Mahler's scale was unrelated, but fatigue variables and emotional function variables on the CRDQ were related. We conclude that peripheral muscle strength is unrelated to level of flow limitation or exercise tolerance in COPD patients. Peripheral muscle strength is related, however, to maximum work load and some aspects of quality of life.

Aged↗
PubMed1998

Neurocognitive effects of chronic lead intoxication in Andean children.

Lead (Pb) intoxication in children has been associated with neurodevelopmental disabilities which may result in motor and cognitive impairment. We conducted blood lead (PbB) measurements, neurological examinations and cognitive tests on children living in Ecuadorian villages where Pb is used extensively in the glazing of ceramics. Group I consisted of 55 children with a mean PbB level of 48.0 microg/dl (SD: 26.4, range: 9.2-119.1 microg/dl) who received PbB tests and complete neurological examinations. An appreciable number of the children with elevated PbB levels were normal on specific components of the neurological examination. Among the children who showed neurological deficits, higher PbB levels were associated with abnormal tendon reflexes, finger tapping, visual pursuit, size discrimination, draw-a-person, and math calculation skills. Group II consisted of 41 children with a mean PbB level of 47.4 microg/dl (SD: 22.0, range: 6.6-84.7 microg/dl) who were administered Raven's Coloured Progressive Matrices (RCPM) non-verbal reasoning test. Performance on RCPM was abnormal in 22 (53.7%) of 41 children. Children with abnormal RCPM scores had higher PbB levels (t-test: P=0.030). There was a significant inverse correlation between RCPM scores and PbB levels for children ages 9 years and older (r=-0.618, P=0.011). Males had higher mean PbB levels as a function of age than females (t-test: P=0.037), and more males showed neurocognitive deficits. The results demonstrate a range of neurological responses in children with chronically elevated PbB levels from apparent exceptional neuro-physiological tolerance of PbB intoxication, to some fine motor and cognitive deficits.

Ceramics↗
PubMed1998

Optimal metabolic control design.

In a previous work [Acerenza, L. (1993). Metabolic Control Design. J. theor. Biol. 165, 63-85] we devised a procedure to design metabolic systems that respond according to pre-established patterns. This procedure includes the mandatory structural and kinetic constraints that narrow the spectrum of responses. In an evolutionary context, the structural and functional features shown during the history of the system would also be conditioned by other factors. Here we incorporate to the Metabolic Control Design procedure two additional requirements that could have influenced metabolic evolution. These are constraints that result from the adaptation to the environment (represented by independent control coefficients that take fixed values) and optimization of metabolic variables at constant total enzyme concentration. To illustrate the general strategy we consider metabolic systems consisting of r reaction steps where the variables are the fluxes, internal metabolite concentrations, enzyme concentrations and control coefficients. In our conditions the number of degrees of freedom, calculated as number of variables minus number of number of relationships, is r - 1. A detailed analysis of three particular schemes, unbranched chain of two and three steps and branch point, with simple linear rate laws is given. Novel results are obtained for the optimization of the input flux of the simple branch point. In the well studied case where there are no evolutionary constraints one of the limbs of the branch point disappears. However, for particular independent control coefficients, when we impose to the control coefficient a fixed value, the branched structure may or may not persist depending on the range to which the fixed value belongs.

Mathematics↗
PubMed1998

Electrochemical immunosensor for the detection of atrazine.

An amperometric immunosensor for the detection of the herbicide atrazine has been developed. A redox polymer PVPOs(bpy)2Cl was co-immobilized with the specific antibody on the surface of the electrode by crosslinking with PEGDGE to form an electron-conducting hydrogel. In a competitive assay the occurrence of the antibody-antigen reaction on the surface of the sensing film was detected through the 'electrical wiring' of the redox centres of antigen-labelled horseradish peroxidase and the electrode surface in the presence of H2O2 at 0.1 V (vsAg/AgCl).

Animals↗
PubMed1998

[Efficacy of a program for tobacco use cessation with a combined substitution treatment of nicotine (patches plus chewing gum) at 6 months of follow-up].

Our aim was to assess the efficacy after 6 months of combined smoking cessation therapy using nicotine substitution with both chewing gum and patches. Sixty-six (25 women, 41 men) heavy smokers (38.04 packs/year and 8.42 mean score on Fagerström test) were followed between September 1995 and March 1997. Most patients were referred by respiratory, cardiology or ear-nose-and-throat outpatient clinics. The patients were prescribed 24-hour nicotine substitution therapy with 21 mg patches, plus chewing gum providing 2 mg of nicotine (3 to 10 per day) for a minimum of 8 weeks and a maximum of 12, with gradually decreasing doses. The patients were checked 1, 2, 4, 8, 12 and 24 weeks after enrollment. Expired air carbon monoxide was measured to confirm abstinence at each checkup and a simple questionnaire was filled in to assess abstinence syndrome and detect the presence of treatment side effects. Rate of abstinence achieved with this protocol after six months of follow-up was 37.9%. The failure rate was highest in the first week (33%) but gradually decreased until week 12. No patients had to abandon treatment due to side effects.

Administration, Cutaneous↗
PubMed1998

Health-related quality of life (HRQOL) in end stage renal disease (ESRD) patients over 65 years.

OBJECTIVES: The aim of the study was to assess Health Related Quality of Life (HRQOL) of elderly patients on renal replacement therapy (RRT) of our region, and to identify socio-demographic and clinical variables which influence it. We also attempted to compare HRQOL of transplant patients, with that of chronic hemodialysis patients. DESIGN: Cross-sectional study. SETTING: Institutional Hospital Nephrology Unit. PATIENTS: All patients from 9 of the 10 hemodialysis centres in our region, aged 65 years or more, who had been on RRT (chronic hemodialysis and kidney transplantation) for at least three months, showing no cognitive problems, were included. The sample included 124 patients. INTERVENTIONS: These patients participated in a structured interview using two generic HRQOL questionnaires: Sickness Impact Profile and SF-36 Health Survey. Karnofsky Scale, Comorbidity Index, socio-demographic and clinical data, were also collected. RESULTS: The median age was 71 years (range 65-75); 55.6% of the patients were male; 19.8% of the sample were transplant patients and 80.2%, hemodialysis patients (only 2% on renal transplant waiting list); 69.2% had a low-intermediate socio-economic level, 52.9% had elementary studies, and 10.6% lived alone. Transplant patients had higher HRQOL than hemodialysis patients. Women had lower HRQOL than men. A higher economic level, higher educational level, higher Karnofsky Performance Scale, and lower Comorbidity Index score, were associated with higher HRQOL. CONCLUSIONS: The good HRQOL of elderly transplant patients, in comparison with hemodialysis patients, is an important reason for advising kidney transplants in elderly patients. Economic and educational levels, functional status and comorbidity are variables which influence the HRQOL of these patients.

Aged↗
PubMed1998

Hyperthyroidism in a renal transplant recipient.

We report a case of toxic multinodular goiter with severe symptomatic hyperthyroidism in a female diagnosed 5 months after successful renal transplantation. To our knowledge, this is the first well-documented case of hyperthyroidism in a renal transplant recipient that responded well to methimazole. Special attention should be made to the use of methimazole and the possible interaction with immunosuppressive drugs.

Adult↗