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Biomedical subjects

F García

Publications and source records attributed to F García.

At least 91 records · Page 5Linked to original sources
PubMed1999

Endothelial cell activation in muscle biopsy samples is related to clinical severity in human cerebral malaria.

To test the hypothesis of vascular sequestration of parasitized erythrocytes in Plasmodium falciparum malaria in vivo, a pathologic and immunohistochemical study was done of the microvasculature of skeletal muscle biopsy samples from P. falciparum malaria patients at different stages of severity. Parasitized red blood cells sequestered in the skeletal muscle vessels were observed in samples from necropsies but were never demonstrated in biopsy specimens. Vascular cell adhesion molecule-1 and E-selectin expression was consistent only in specimens from cerebral malaria patients. Samples from such patients had strong staining of the constitutive endothelial adhesion molecules tested. The staining intensity gradually decreased in samples from persons with milder forms of the disease. Four of 13 patients with severe malaria had aggregates of red blood cells, occasionally parasitized inside the muscle fibers. These data suggest that skeletal muscle biopsy could be a useful model for the study of the pathogenesis of malaria in vivo.

Adolescent↗
PubMed1999

Meiotic abnormalities and spermatogenic parameters in severe oligoasthenozoospermia.

The incidence of meiotic abnormalities and their relationship with different spermatogenic parameters was assessed in 103 male patients with presumably idiopathic severe oligoasthenozoospermia (motile sperm concentration < or = 1.5 x 10(6)/ml). Meiosis on testicular biopsies was independently evaluated by two observers. Meiotic patterns included normal meiosis and two meiotic abnormalities, i.e. severe arrest and synaptic anomalies. A normal pattern was found in 64 (62.1%), severe arrest in 21 (20.4%) and synaptic anomalies in 18 (17.5%). The overall rate of meiotic abnormalities was 37.9%. Most (66.7%) meiotic abnormalities occurred in patients with a sperm concentration < or = 1 x 10(6)/ml. In this group, total meiotic abnormalities were found in 57.8% of the patients; of these, 26.7% had synaptic anomalies. When the sperm concentration was < or = 0.5 x 10(6)/ml, synaptic anomalies were detected in 40% of the patients. In patients with increased follicle stimulating hormone (FSH) concentrations, total meiotic abnormalities occurred in 54.8% (synaptic anomalies in 22.6%). There were statistically significant differences among the three meiotic patterns in relation to sperm concentration (P < 0.001) and serum FSH concentration (P < 0.05). In the multivariate analysis, sperm concentration < or = 1 x 10(6)/ml and/or FSH concentration > 10 IU/l were the only predictors of meiotic abnormalities.

Adult↗
PubMed1999

Evaluation of ischemic injury during liver procurement from non-heart-beating donors.

UNLABELLED: The aim of this study was to assess liver viability after different periods of cardiac arrest and the predictive value of two markers of ischemia-reperfusion injury. METHODS: A pig liver transplantation model of non-heart-beating donors was studied. Four donor groups were designed; three groups were submitted to different periods of cardiac arrest (20, 30 and 40 min), and the fourth group served as the control group (without cardiac arrest). In the non-heart-beating donor groups, normothermic recirculation was established 30 min prior to total body cooling. Aminotransferase, alpha-glutathione-S-transferase, and hyaluronic acid determinations as well as liver biopsies, were serially performed. RESULTS: Although hepatocellular function could be preserved after 40 min of cardiac arrest, histological lesions at 5 days were considered irreversible due to the presence of a necrotic biliary tract. An overall significant relationship was found between the time period of cardiac arrest (20, 30 or 40 min) and the levels of hyaluronic acid (p = 0.004) or alpha-glutathione-S-transferase (p = 0.01) obtained during liver procurement and transplantation. CONCLUSIONS: The period of cardiac arrest is the determinant factor of liver viability after liver transplantation from non-heart-beating donors. As early markers of endothelial or hepatocellular damage, hyaluronic acid or alpha-glutathione-S-transferase levels may help to evaluate the ischemic injury of a potential donor.

Alanine Transaminase↗
PubMed1999

[131I-treatment of the autonomous toxic nodule. Assessment of a fixed dose protocol].

Ninety six patients diagnosed of toxic thyroid adenomas received fixed doses of 131I (555MBq) for treatment of hyperthyroidism. The inclusion and exclusion criteria, the patient's characteristics and the advantages of the fixed doses are described. The hypothyroidism rate found at the end of the mean follow-up period (2.46 +/- 1.72 years) which was 27.08% significantly lower to that observed in patients treated for Graves-Basedow disease, is pointed out. No differences were found in the hypothyroidism rate when the patients were differentiated by sex or when this situation was related to pretreatment with the antithyroid drugs. The extensive differences in the hypothyroidism rates observed between the different series that have been published and the variability in the doses administered leads us to think that factors other than the dose of 131I may be responsible for this post-therapeutic hypothyroidism.

Adenoma↗
PubMed1999

[A complete atrioventricular block and polymorphic ventricular tachycardia as the initial manifestation of secondary amyloidosis].

Cardiac injury is a frequent characteristic in primary, senile and myeloma related amyloidosis, but it is unusual in secondary amyloidosis. We report a patient with complete atrioventricular block and polymorphic ventricular tachycardia as the initial manifestation of secondary amyloidosis. Necropsy demonstrated amyloidosis deposits in the specific conduction system.

Adult↗
PubMed1999

[Television publicity and food preferences of school age children of the metropolitan region].

BACKGROUND: There is an alarming increase in the prevalence of child obesity in Chile. Lack of exercise and bad feeding habits strongly strongly contribute to the problem. AIM: To investigate the influence of television publicity on school age children food preferences. MATERIAL AND METHODS: A semi structured interview was applied to a representative sample of 786 school age children aged 6 to 11 years old, living in Metropolitan Santiago. Time watching television during week days and the attitude towards food and beverage commercials was analyzed and related to food preferences. RESULTS: Ninety nine percent of school age children watch television during week days and 20% watches more the three hours daily. Snack commercials such as those about potato chips, chocolates, cookies and ice cream, are preferred by 35% of children. Soda commercials are preferred by 33% and yoghurt commercials by 12%. Eighty five percent of children had money to buy food. Of these, 66% bought snacks, 15% bought sodas and 7% yoghurt. The same tendency was observed in school collations. CONCLUSIONS: The high percentage of children, watching television and the influence of commercials in their food preferences, requires an urgent educational strategy to promote healthy feeding habits.

Adolescent↗
PubMed1998

Predictive factors influencing peak viral load drop in response to nucleoside reverse transcriptase inhibitors in antiretroviral-naive HIV-1-infected patients.

Therapy with two nucleoside reverse transcriptase inhibitors (NRTI), the backbone of triple combinations, is still widely used in early stages of HIV-1 disease. However, factors influencing virologic response need to be further analyzed, to test the hypothesis that the reduction of plasma RNA viremia with NRTI may be greater in patients with higher baseline viral load (BVL) and to analyze the predictive factors of viral load drop below detection (200 HIV RNA copies/ml of plasma). Selected for the study were 169 HIV-1-infected antiretroviral therapy-naive patients with CD4+ T-lymphocyte counts ranging from 6 to 1040/microl coming from three randomized studies comparing the efficacy of monotherapy (zidovudine [ZDV], 250 mg every 12 hours; N=40) versus two-drug therapy consisting of ZDV (250 mg every 12 hours) with dideoxycytidine (ddC, 0.75 mg every 8 hours) or didanosine (ddI, 200 mg every 12 hours; N=129). Viral load was measured at 1, 3, and 6 months by polymerase chain reaction (PCR). A linear regression model was used to analyze the relation between BVL and the peak reduction of plasma RNA viremia. The variables included in a logistic regression model to determine the likelihood of VLs dropping below detection levels were age, gender, risk group for HIV-1 infection, baseline CD4+ lymphocyte count, BVL, clinical status (AIDS versus non-AIDS), HIV-1 phenotype (syncytium-inducing [SI] versus non-syncytium-inducing [NSI]) and type of treatment (monotherapy versus double therapy). The peak reduction of VL was related to baseline level following a linear model in both monotherapy and double-therapy regimens. In the subgroup of patients treated with two NRTIs, the regression line that fitted best with the data was log10 (peak reduction)=1.8-0.36 log10 (BVL) (F=23.5; p < .0001). This indicates that for every increase of 1 log10 of BVL, the peak reduction would be of 0.64 log10 greater. Forty-nine (29%) of the 169 patients dropped to <200 copies/ml. The likelihood of dropping below detection level was significantly greater in those receiving double therapy versus monotherapy (odds ratio [OR]=16.1; 95% confidence interval [CI], 2-128), in those with baseline CD4+ lymphocyte count >350/microl (OR=2.28; 95% CI, 1.1-4.9) and in those with BVL <10,000 HIV-1 RNA copies/ml (OR= 2.25; 95% CI, 1.1-6.1). None of the 13 patients with an SI phenotype at baseline dropped below detection levels. The reduction of VL in response to two NRTIs was greater in those patients with a higher level of BVL. In conclusion, peak reduction below detection in response to NRTI can be predicted and is associated with double therapy, with a baseline CD4+ cell count >350/microl and with a BVL <10,000 RNA copies/ml.

Adult↗
PubMed1998

Lack of evidence of a stable viral load set-point in early stage asymptomatic patients with chronic HIV-1 infection.

OBJECTIVE: To address the question of whether individuals with chronic HIV-1 infection have a stable viral load set-point and to assess the influence of host and viral factors on the evolution of viral load in a subset of stable asymptomatic patients with a baseline viral load below 5000 copies/ml and CD4+ T-cell count above 500 x 10(6)/l. METHODS: Medical visits were performed at least every 6 months including routine blood analysis, viral load and CD4+ T-cell count. HIV-1 RNA was measured in frozen (-70 degrees C) plasma samples using PCR. Patients were classified into three groups according to baseline viral load: group A, < 200 copies/ml (undetectable); group B, 201-2000 copies/ml; group C, 2001-5000 copies/ml. A survival analysis and a Cox regression model were performed to assess the influence of viral and host factors in the increase of baseline viral load. The endpoint was the time to increase viral load to a stable level > 0.5 log10 copies/ml above baseline viral load in groups B and C and to a stable detectable viral load (> 200 copies/ml) in group A. RESULTS: A cohort of 114 patients with viral load below 5000 copies/ml was followed for a median of 12 months (6-42 months). Overall, 22 (19%) out of 114 patients had an increase > 0.5 log10 copies/ml of baseline viral load. Baseline viral load increased in two (5%) out of 37 patients in group A, four (12%) out of 33 patients in group B, and 16 (36%) out of 44 patients in group C (survival analysis, P<0.002). Patients of group C had a eightfold higher risk of increasing baseline viral load than patients in the other two groups pooled together (hazards ratio, 8.28; 95% confidence interval, 1.78-38; P = 0.006). Patients with an increase of viral load to the virological endpoint had a threefold higher risk of decreasing baseline CD4+ T-cell counts > 100 x 10(6)/I than patients with stable viral load (hazards ratio, 2.78; 95% confidence interval, 1.12-14; P = 0.03). CONCLUSIONS: In our cohort of chronically HIV-1-infected asymptomatic patients with a baseline viral load < 5000 copies/ml and CD4+ cell count > 500 x 10(6)/l, a true viral load set-point did not seem to exist. Patients with baseline viral load of 2000-5000 copies/ml had an eightfold higher risk of increasing the level of viral load than patients with a baseline viral load below 2000 copies/ml.

Adult↗
PubMed1998

Hepatic blood flow and oxygen extraction ratio during normothermic recirculation and total body cooling as viability predictors in non-heart-beating donor pigs.

BACKGROUND: Our aim was to evaluate the hepatic blood flows and oxygen metabolism of non-heart-beating donor (NHBD) pigs, with the use of cardiopulmonary bypass (CPB) and normothermic recirculation (NR) before total body cooling, and its relationship with recipient survival. METHODS: Thirty-five pigs were transplanted with an allograft from NHBDs. After warm ischemia (WI) time (20, 30, or 40 min), CPB and NR were run for 30 min. After this period, the animals were cooled to 15 degrees C. In the control group (20 min of WI), the period of NR was excluded. Liver procurement was then performed. RESULTS: Survival rate was 100% in the 20WI, 70% in the 30WI, and 50% in the 40WI. Control group survival rate was 0%. Hepatic artery blood flow and portal blood flow recovered during NR. Pump blood flow during CPB increased rapidly during NR and was significantly higher in the 20WI. When donors of the livers transplanted in "surviving pigs" (DSP) were compared with donors of the livers transplanted in "nonsurviving pigs" (DNSP), hepatic artery blood flow, portal blood flow, and pump blood flow were higher in the DSP. Hepatic oxygen extraction ratio increased in the three groups with respect to baseline values. Hepatic oxygen extraction ratio was lower in the 20WI than in the other groups and was lower in the DSP than in the DNSP. CONCLUSIONS: The use of a NR period before total body cooling improves survival of liver transplantation in NHBDs. Portal blood flow and pump blood flow measurements can predict the viability of the grafts.

Animals↗
PubMed1998

Molecular cloning and characterization of the human p44 mitogen-activated protein kinase gene.

The complete genomic structure of the human p44(mapk) gene (HMGW-approved symbol PRKM3) has been determined. The gene covers 9 kb and is composed of nine exons and eight introns. This structure is identical to the previously reported mouse p44(mapk) gene, indicating a high degree of evolutionary conservation. A sequence differing by one nucleotide from the consensus TATA box is present 132 positions upstream of the main transcription initiation point. This point has been located 415 nucleotides upstream of the translation initiation codon ATG and perfectly meets the consensus criteria for an initiator element (Inr). Multiple consensus sequences for factors that regulate either basal transcription or gene expression during cell differentiation and proliferation can be found in the putative promoter region. Some of them, such as several G/C boxes located downstream from the transcription initiation point, are also present in the homologous mouse gene, where they were shown to be functional.

5' Untranslated Regions↗
PubMed1998

The effects of sensory stimulation on REM sleep duration.

Previous experiments have demonstrated that auditory (AS) and/or somatosensory (SS) stimulation can increase the duration of REM sleep periods in rats, cats and humans. The objectives of this study were to determine whether repeated AS stimulation causes habituation to the stimulus and whether any additive effects could be obtained with the simultaneous application of AS and SS. Three experimental procedures were used in this study. In experiment 1, animals were recorded for 4 consecutive days with AS, followed by a post-stimulus session. In experiment 2, they were recorded for 24 hours with AS applied at each REM period, followed by a subsequent 24-hours-post-stimulus recording. In experiment 3, animals underwent AS, SS stimulation, or simultaneous application of both in a random fashion at each REM period. The results of all experiments confirm previous findings showing that auditory or somatosensory stimuli significantly increase REM sleep period duration. In addition, AS--applied with different presentations during REM and throughout the sleep-wake cycle--are capable of increasing REM duration regardless of the manner in which they were presented. However, the effects of the stimuli were not additive. It is worth noting that although REM duration increased, REM period frequency decreased, resulting in no net change of total REM sleep through time. Furthermore, no changes were observed in other sleep-wake variables. These experiments clearly demonstrate that repeated auditory stimulation does not cause habituation, and there are no evident side effects on the sleep-wake cycle. These results confirm that the mechanisms involved in REM generation and maintenance can be modulated by sensory modalities.

Animals↗
PubMed1998

Effect of heat treatment on pulsed laser deposited amorphous calcium phosphate coatings.

Amorphous calcium phosphate coatings were produced by pulsed laser deposition from targets of nonstoichiometric hydroxyapatite (Ca/P = 1.70) at a low substrate temperature of 300 degrees C. They were heated in air at different temperatures: 300, 450, 525 and 650 degrees C. Chemical and structural analyses of these coatings were performed using X-ray diffraction (XRD), FTIR, and SEM, XRD analysis of the as-deposited and heated coatings revealed that their crystallinity improved as heat treatment temperature increased. The main phase was apatitic, with some beta-tricalcium phosphate in the coatings heated at 525 and 600 degrees C. In the apatitic phase there was some carbonate substitution for phosphate and hydroxyl ions at 450 degrees C and almost solely for phosphate at 525 and 600 degrees C as identified by FTIR. This was accompanied by a higher hydroxyl content at 525 and 600 degrees C. At 450 degrees C a texture on the coating surface was observable by SEM that was attributable to a calcium hydroxide and calcite formation by XRD. These phases almost disappeared at 600 degrees C, probably due to a transformation into calcium oxide.

Calcium Phosphates↗
PubMed1998

Liver conditioning after cardiac arrest: the use of normothermic recirculation in an experimental animal model.

The aim of this study was to compare the possible role of normothermic recirculation with the role of liver transplants from non-heart-beating donor pigs after 20 min of cardiac arrest. Three groups were studied, of which two were control groups: group 1, in which the liver was harvested from a heart-beating donor; group 2, in which the liver was harvested after a period of cardiac arrest followed by total body cooling; and group 3, in which the liver was procured as in group 2, but including a period of 30 min of cardiopulmonary bypass and tissue oxygenation at 37 degrees C before total body cooling. Survival at 5 days; endothelial (hyaluronic acid) and hepatocellular damage (AST, ALT, and alpha-GST); adenine nucleotides (energy charge), and histological changes were evaluated. Normothermic recirculation during 30 min showed a significant effect on survival (p = .03), endothelial damage (p < .05), and histological changes after reperfusion (p = .04). Cardiopulmonary bypass significantly increased the energy charge during the normothermic recirculation period (p = .001). Moreover, this study shows that a significant survival (100%) can be achieved with a liver allograft after 20 min of cardiac arrest. Although the liver suffers a major insult in terms of endothelial damage and hepatocellular damage, lesions caused by the ischemic injury are reversible. Histological changes also indicate lesion reversibility, since they almost disappear after 5 days.

Adenine Nucleotides↗
PubMed1998

Dermatophagoides sp. and IgE anti-D. pteronyssinus and D. farinae detection in a Venezuelan community at more than 2000 m above the sea level.

BACKGROUND: It has been reported that the concentration of Dermatophagoides sp. population, the main trigger of asthma in sensitized atopic subjects, is inversely related with altitude and probably directly with humidity and that this population are scarcely found over 1750 m above sea level. OBJECTIVE: We studied the presence of Dermatophagoides sp. in a Venezuelan community between 2040 and 2600 m above sea level, and also the IgE response to D. pteronnyssinus and D. farinae in atopic subjects living on that region. METHODS: The presence of Dermatophagoides sp. was determined by microscopic identification of mites in dust, obtained by brushing the mattresses surface in 93 randomly selected houses between 2040 and 2600 m above sea level. The indoor relative humidity was also measured. The specific IgE serum levels were studied in 65 subjects classified as asthmatics, allergic non-asthmatics and non-allergic. RESULTS: A mean concentration of 188 mites/g of room dust was determined in 82.4% of houses with an indoor relative humidity ranging from 89% and 92% independently of altitude. The density of Dermatophagoides sp. was sufficiently high to sensitize the atopic subjects, IgE levels were 6.8 PRU mean value for asthmatic, against 0.38 PRU in non-atopic. CONCLUSIONS: We conclude that: (a) Dermatophagoides sp. can be found up to 2600 m above sea level in a Venezuelan neotropical region where a high indoor relative humidity is characteristic of most dwellings; (b) sensitization by D. pteronyssinus and D. farinae were demonstrated in atopic subjects resident at that region.

Allergens↗
PubMed1998

An HLA-B27 polymorphism (B*2710) that is critical for T-cell recognition has limited effects on peptide specificity.

The B*2710 subtype differs from the HLA-B27 prototype (B*2705) only by having Glu instead of Val at position 152, in the alpha2 helix of the peptide-binding site. In spite of its structural similarity most alloreactive CTL raised against B*2705 fail to cross-react with B*2710. Indeed, of the residues that are polymorphic among HLA-B27 subtypes, the Val>Glu152 change has the greatest influence on HLA-B27 T-cell antigenicity. The molecular basis for this antigenic disparity was analyzed in this study. Sequence analysis indicated that B*2710-bound peptides have very similar motifs to B*2705-bound ones both at the main and auxiliary anchor positions. In addition, most of the individual ligands sequenced from B*2710 were previously found in B*2705. Together these results indicate that both subtypes have largely overlapping peptide repertoires. Molecular dynamics simulations of a common ligand in complex with either B*2710 or B*2705 failed to detect significant conformational changes in the peptidic main chain or in solvent accessibility of the side chains. In addition, modeling of the Val>Glu152 change into the MHC-peptide-TCR structure suggested a direct role of residue 152 in interaction with the TCR. Thus, the large differences in T-cell recognition between B*2710 and B*2705 are not explained by an effect of the Glu152 change on peptide specificity or conformation, but by different direct interactions with the TCR.

Binding Sites↗