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Biomedical subjects

A García

Publications and source records attributed to A García.

At least 127 records · Page 7Linked to original sources
PubMed2000

Protein phosphatase 1alpha is a Ras-activated Bad phosphatase that regulates interleukin-2 deprivation-induced apoptosis.

Growth factor deprivation is a physiological mechanism to regulate cell death. We utilize an interleukin-2 (IL-2)-dependent murine T-cell line to identify proteins that interact with Bad upon IL-2 stimulation or deprivation. Using the yeast two-hybrid system, glutathione S-transferase (GST) fusion proteins and co-immunoprecipitation techniques, we found that Bad interacts with protein phosphatase 1alpha (PP1alpha). Serine phosphorylation of Bad is induced by IL-2 and its dephosphorylation correlates with appearance of apoptosis. IL-2 deprivation induces Bad dephosphorylation, suggesting the involvement of a serine phosphatase. A serine/threonine phosphatase activity, sensitive to the phosphatase inhibitor okadaic acid, was detected in Bad immunoprecipitates from IL-2-stimulated cells, increasing after IL-2 deprivation. This enzymatic activity also dephosphorylates in vivo (32)P-labeled Bad. Treatment of cells with okadaic acid blocks Bad dephosphorylation and prevents cell death. Finally, Ras activation controls the catalytic activity of PP1alpha. These results strongly suggest that Bad is an in vitro and in vivo substrate for PP1alpha phosphatase and that IL-2 deprivation-induced apoptosis may operate by regulating Bad phosphorylation through PP1alpha phosphatase, whose enzymatic activity is regulated by Ras.

Animals↗
PubMed2000

Increased cytogenetic damage in outdoor painters.

Painters are exposed to an extensive variety of hazardous substances such as organic solvents, lead-containing pigments and residual plastic monomers. In this particular case, workers used commercially available exterior paints and occasionally gasoline or thinner as solvents. The application or removal of paints was performed without protection (masks or gloves). To determine occupational exposure risk, a monitoring study was designed. Group selection was made after a questionnaire administration, which included questions about lifestyle and medical history to exclude exposure to other potential sources of genotoxics. Smoking and drinking habits were also considered. Blood and buccal cell samples were obtained from 25 public building male painters and from a similar number of age- and gender-matched controls. Lead levels were measured in paint samples and in individuals' blood. Organic solvents and/or its metabolites were also determined in blood. Chromosomal aberrations (CA) and sister chromatid exchanges (SCE) were determined in peripheral blood lymphocyte cultures. Also, the frequency of micronuclei (MN) in buccal cells was investigated. Painters had higher lead levels in blood (p<0.05); CA and SCE in lymphocytes and MN in epithelial cells were also elevated (p<0.05). Cytogenetic damage was significantly associated with occupational exposure time but not with the levels of lead found in blood.

Adolescent↗
PubMed2000

Direct measurement of homovanillic, vanillylmandelic and 5-hydroxyindoleacetic acids in urine by capillary electrophoresis.

Separation conditions in CE, with a neutral coated capillary and reversed polarity, have been optimised to make direct measurement of vanillylmandelic acid, homovanillic acid and 5-hydroxyindoleacetic acid possible in urine samples without pre-treatment. The method developed has been validated, presenting adequate parameters for linearity, accuracy and precision. Detection limits range from 0.03 to 2.5 microM. Finally the method has been applied to urine samples taken from patients, both adults and children, in hospital. Some of them were also measured by immunoassay and HPLC-electrochemical detection and results have been compared.

Adult↗
PubMed2000

Optimization and validation of a method for the determination of caffeine, 8-chlorotheophylline and diphenhydramine by isocratic high-performance liquid chromatography. Stress test for stability evaluation.

The optimization of a HPLC method for caffeine, 8-chlorotheophylline and diphenhydramine separation with UV detection at 229 nm is described. The conditions studied included: stationary phase, compositions of mobile phases with pH modulators. Optimal conditions were: SymmetryShield RP8 column and acetonitrile-(0.01 M H3PO4-triethylamine, pH 2.8) (22:78, v/v). Validation was performed using standards and a pharmaceutical preparation containing the compounds described above. Results from both standards and samples show suitable validation parameters. The pharmaceutical grade substances were tested by factors that could influence the chemical stability. These reaction mixtures were analyzed to evaluate the capability of the method to separate degradation products. Degradation products did not interfere with the determination of the substances tested by the assay.

Caffeine↗
PubMed2000

Retention of permanent incisors by mesiodens: a family affair.

The term mesiodens refers to a supernumerary tooth that is present in the midline of the maxilla between the two central incisors. One or two mesiodentes may be present. We present a rare case of two sisters, in both of whom a pair of mesiodentes caused the retention of permanent incisors. They were referred to our hospital with asymptomatic delayed eruption of upper incisors. This article is written to point out genetic factors as the possible origin of supernumerary teeth.

Adolescent↗
PubMed2000

Identification of novel mutations in Spanish patients with muscle carnitine palmitoyltransferase II deficiency.

Carnitine palmitoyltransferase II (CPT II) deficiency is the most common recessively inherited disorder of lipid metabolism affecting skeletal muscle and the most frequent cause of hereditary myoglobinuria. We studied 5 Spanish patients with CPT II deficiency from four unrelated families. Four patients had the typical clinical phenotype of muscle CPT II deficiency with recurrent episodes of myoglobinuria, triggered by prolonged exercise, fasting, or fever, and marked elevation of creatine kinase values during metabolic crisis. One patient had exercise-related myalgia, cramps and moderate elevation of serum CK values, but had never had myoglobinuria. Molecular analysis showed that three patients were heterozygous for the S113L mutation and one patient heterozygous for the P50H substitution. To identify the mutations in the other alleles of our patients we amplified and sequenced genomic DNA fragments encompassing the entire coding region and intron/exon boundaries of the CPT2 gene. We found the recently reported 178 insT/del 25 bp in one patient. Three novel mutations were identified: a Y120C substitution that leads to a nonconservative amino acid replacement; a 36-38 insGC mutation that results in premature termination of the translation; and an I502T substitution that affects a conserved amino acid residue in the CPT II protein. Our data confirm the molecular heterogeneity of patients with CPT II deficiency, and suggest that the ethnic origin has to be taken into account before performing mutation analysis in these patients.

Adolescent↗
PubMed2000

Microsatellite instability analysis in tumors with different mechanisms for total loss of HLA expression.

Down-regulation of the expression of major histocompatibility complex molecules is a frequent event that is associated with the poor immunogenicity of tumor cells. Acquired resistance to T-cell-based immunotherapy has been associated with loss of functional beta2-microglobulin expression. This anomaly appears to be particularly relevant in tumors exhibiting a defect in DNA-mismatch repair, and induces structural abnormalities in HLA cell-surface expression that are not reversible by cytokine treatment. We examined HLA expression in 118 melanoma, colon or larynx tumors to identify total loss of HLA class I expression with or without somatic beta2-microglobulin gene mutation. Microsatellite instability was investigated in these tumors to determine whether a replication error phenotype (RER+) implied a particular alteration in HLA phenotype. A total of 7.6% of the tumors showed the RER+ phenotype, and 12.7% were HLA-ABC-negative. In the RER+ group, only one tumor was HLA-ABC-negative and no beta2-microglobulin mutation was identified. In contrast, in the HLA-ABC-negative group, only one tumor showed microsatellite instability. None of the three melanomas that contained beta2-microglobulin mutation exhibited the mutator phenotype. These findings suggest that beta2-microglobulin mutation in human melanoma tumors may arise through a mechanism that does not necessarily involve microsatellite instability. Our results also indicate that somatic mutations of the beta2-microglobulin gene are not the main mechanism of total loss of HLA expression.

Adenocarcinoma↗
PubMed2000

Migration pathways of hypodermically injected technetium-99m in dogs.

Hypodermic injection of technetium-99m (99mTc-pertechnetate) at points of low electrical resistance give rise to rapid, longitudinal, and progressive diffusion of the radioactive tracer. We assessed the effect of cutaneous incisions that did not intersect the migration trajectory of 99mTc-pertechnetate and the re-establishment of pathways after the suture of incisions that intersected the migration trajectory. Linear and rapid migration of 99mTc-pertechnetate was not altered or prevented by incisions that did not intersect the migration pathway. Different patterns of 99mTc-pertechnetate spread were found when incisions intersected the radioactive pathways until restoration of the normal migration pathway observed in undamaged skin occurred. In all experiments in which migration of 99mTc-pertechnetate was observed, lavage of surgical wounds was followed by disappearance of the 99mTc-pertechnetate migration observed around the suture. Linear migration of the tracer was not observed when the incision was left uncovered, filled with petroleum jelly, or with a solid silicone sheet, but it was seen when non-sutured incisions were filled with transonic or silicone gel or covered with a solid silicone sheet parallel to the cutaneous plane. These data show that after a cutaneous incision that intersected the diffusion trajectory of the radioactive tracer, linear migration of 99mTc-pertechnetate hypodermically injected at points of low electrical resistance was restored before healing of the cutaneous incision and was independent of incisions made on the skin not overlying the radioactive pathway. A mechanism similar to that of capillary electrophoresis is suggested to explain the hypodermic diffusion of inert particles through specific and constant linear pathways.

Animals↗
PubMed2000

Clinical evaluation of an in-house IS6110 polymerase chain reaction for diagnosis of tuberculosis.

The aim of this study was to clinically validate a heminested polymerase chain reaction (PCR) method, based on the IS6110 insertion segment of Mycobacterium tuberculosis complex, for the diagnosis of tuberculosis. Samples of pulmonary, extrapulmonary and blood origin were collected prospectively from 331 patients. All samples were processed to detect acid-fast bacilli by direct stain, culture and PCR. The gold standard comparison was a clinically based final case definition of tuberculosis corresponding to group 3 of the American Thoracic Society's classification system. The sensitivities of stain, culture and PCR were 41%, 65% and 59%, respectively. Overall specificity exceeded 97% for all techniques. The combination of PCR and direct stain achieved a sensitivity similar to that of culture alone. The PCR method detected 74 of 95 (78%) culture-positive results. In a hospital setting, PCR could be a useful, reliable tool for diagnosis of tuberculosis and may be introduced as a complementary routine diagnostic laboratory method.

Culture Media↗
PubMed2000

Rotavirus and concurrent infections with other enteropathogens in neonatal diarrheic dairy calves in Spain.

Faeces samples from 218, one to 30 days old, diarrheic dairy calves in 65 dairy herds were screened for the presence of rotavirus and concurrent infections with coronavirus, Cryptosporidium, F5+ Escherichia coli and Salmonella spp. Calves were grouped according to their age as follows: 1-7, 8-14, 15-21 and 22-30 days. Rotavirus infection was detected in 46.9%, 45.6%, 33.8% and 48.3% of the calves in the respective age-groups. No significant differences in the detection rate of rotavirus were found among calves on the different age-groups. Rotavirus was the only enteropathogen detected in 39 of the 93 (41.9%) diarrheic calves positive to this agent. Concurrent infections with other enteropathogen(s) were detected in 31.3%, 33.3%, 20.6% and 3.4% of the rotavirus infected calves in the age-groups 1-7, 8-14, 15-21 and 22-30 d, respectively. A significant age-associated decrease in the detection rate of mixed infections (p < 0.01) was found. The detection rates of the other enteropathogens considered in calves with rotavirus infection were 20.4% for coronavirus, 85.2% for Cryptosporidium, 16.7% for F5+ E. coli and 1.8% for Salmonella.

Animals↗
PubMed2000

[Recurrent ventricular fibrillation during a febrile illness in a patient with the Brugada syndrome].

Different situations have been involved in the origin of ventricular arrhythmic events in patients with the Brugada syndrome such as bradycardia, alcohol consumption and mental stress. We present a 30 year old male with recurrent ventricular fibrillation due to a febrile illness with intense sweating. He had been previously studied at our Unit in 1995 because of an episode of resuscitated cardiac arrest due to ventricular fibrillation. The twelve-lead electrocardiogram showed the typical characteristics of a patient with the Brugada syndrome. Different invasive and non-invasive tests performed were normal. He received a defibrillator and had no recurrences during 4 years of follow up. In March,1999, after an upper respiratory tract infection he had high fever treated with paracetamol but at down he had sweating and chills, followed by 3 defibrillator shocks. Late interrogation showed 5 episodes of ventricular fibrillation, two of them non-sustained, and the rest adequately treated by the defibrillator. Activation and inactivation kinetics for early INa are twofold faster at higher temperature, and shift activation and steady-state inactivation. This may explain the role of the temperature as a trigger for ventricular arrhythmias in our patient.

Adult↗
PubMed2000

A mitochondrial tRNA(Lys) gene mutation (T8316C) in a patient with mitochondrial myopathy, lactic acidosis, and stroke-like episodes.

We studied a patient with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes who had morphologically and biochemically abnormal muscle mitochondria. Molecular analysis revealed a T8316C transition in the mitochondrial DNA tRNA(Lys) gene. The mutation was homoplasmic in muscle from the proposita, heteroplasmic in her blood, and still less abundant in blood from her asymptomatic maternal relatives. The T8316C mutation affects a highly conserved base pair and was not found in controls, thus satisfying the accepted criteria for pathogenicity. Our data document the genetic heterogeneity in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes syndrome, underlining that the same syndrome may be associated with mutations of different genes.

Acidosis, Lactic↗
PubMed2000

Clinico-electrophysiological correlation of extensor digitorum brevis muscle atrophy in children with charcot-marie-tooth disease 1A duplication.

The purpose of the study is to describe the electrophysiologic abnormalities accounting for the appearance and progression of extensor digitorum brevis (EDB) muscle atrophy in Charcot-Marie-Tooth-disease type 1A (CMT-1A) children. Twelve children with CMT-1A duplication were serially evaluated. Initial ages of clinico-electrophysiological exams ranged from 1 month to 4 years (mean: 2 years) and final ages from 6 to 23 years (mean: 13). All subjects had two or more electrophysiological studies of the peroneal nerve. EDB atrophy was observed in two out of 12 (17%) patients by the age of 5, in eight out of ten (80%) examined between 5 and 9 years, and in all eight (100%) patients who had reached the second decade at the end. Nerve conduction maturation was systematically abnormal, but by age of 5 the mean values of nerve conduction parameters of peroneal nerve did not significantly differ from those in older patients. Compound muscle action potential (CMAP) amplitudes of EDB were reduced in 42% of cases initially and 100% upon last exam. Furthermore, a constant finding throughout the study was progressive attenuation of CMAPs, these becoming unobtainable in four cases. EDB muscle atrophy in CMT-1A children is an age-dependent sign which is accounted for by gradual reduction of the distal peroneal nerve CMAP amplitudes.

Action Potentials↗
PubMed2000

Ten-year review of invasive pneumococcal diseases in children and adults from Uruguay: clinical spectrum, serotypes, and antimicrobial resistance.

OBJECTIVES: Since 1987, the Reference Laboratory of the Ministry of Health of Uruguay has been monitoring infections due to Streptococcus pneumoniae in patients under 5 years of age, in those between 5 to 14 years of age, and in adults. The purpose of the present study was to retrospectively analyze a 10-year collection of invasive S. pneumoniae isolates from children 5 to 14 years of age and adults. METHODS: The Reference Children's Hospital, Pasteur Hospital, and two private hospitals in Montevideo as well as four hospitals located in other representative areas of the country participated in the pneumococcal surveillance program. Based on the information available at the Microbiology Department of the Central Public Health Laboratory (demographic data, date and site of isolate, and clinical diagnosis), all patients with an invasive pneumococcal disease were recorded. Pneumonia was clinically and radiologically diagnosed and etiology was assessed by isolation of S. pneumoniae from blood or pleural fluid. All specimens were collected at the Emergency Service. Capsular serotyping and antimicrobial susceptibilities were determined for each isolate. RESULTS: During the 10-year period, 228 invasive S. pneumoniae were identified and included in the study (blood, n = 129; cerebrospinal fluid [CSF], n = 73; pleural fluid, n = 20; peritoneal fluid, n = 3; synovial fluid, n = 1; pericardic fluid, n = 1; abscess, n = 1). The most frequent clinical presentations were pneumonia (n = 71) and meningitis (n = 69). Thirty-five adults had an underlying condition including, four with malignancies, four with lupus, two with human immunodeficiency virus (HIV)-infected, and two patients in hemodialysis among others. Eighteen of the 228 patients died (7.9% fatality rate), but only four of these had an underlying condition. Eleven fatal cases were attributable to meningitis (2 children, 9 and 11 years old; 9 adults, mean age, 59 y). Four patients with pneumonia and three with sepsis died, including a splenectomized woman. Nine different capsular serotypes (1, 5, 7, 9, 12, 15, 19A, 20, and 23A) were identified among the 18 fatal cases. Resistance to penicillin, generally combined with trimethoprim-sulfamethoxazole, fluctuated annually, not surpassing 10%. CONCLUSIONS: The study results indicated that 96% of the serotypes involved in severe pneumococcal diseases were included in the 23-valent vaccine and that S. pneumoniae resistance to penicillin was moderate.

Adolescent↗
PubMed2000

Peripheral motor and sensory nerve conduction studies in normal infants and children.

OBJECTIVE: There are few data on electrophysiological data of motor and sensory fibres during nerve maturation. The aim of this study is to investigate the evolution of nerve conduction in the upper and lower limbs during the first years of life. METHODS: The study comprised 92 normal infants and children aged from 1 week to 6 years. Using surface electrodes, the investigation included the following data: (1) motor conduction velocity (MCV), corrected distal motor latency (DML) to a standard distance, and F-waves of the median, ulnar, peroneal and tibial nerves; (2) sensory conduction velocity (SCV) of the median and tibial nerves; and (3) amplitude and morphology of the muscle and sensory action potentials. RESULTS: Maximal MCV and SCV in the neonatal period was about half of adults; there was a steep conduction increase during the first year of life, adult values being reached around age 4. In the neonatal period corrected DML was greater than in adults with a further decrease during the first year. F-wave latencies also decreased during the first year with increase at the end of the study. CONCLUSIONS: This study corroborates the fact that 'maturation' of MCV and SCV occurs during the first 5 years of life, especially in the former. Evolution of DML is accounted for using correction. F-wave latency changes are explained both by an increase in MCV, and extremity growth.

Action Potentials↗
PubMed2000

Rapid and complete extraction of phenols from olive oil and determination by means of a coulometric electrode array system.

Extraction methods to determine olive oil phenols are not exhaustive. A procedure to test their effectiveness, based on the treatment of the extracted oil with 2 N HCl followed by analysis of phenols in the aqueous phase, has been developed. It was concluded, using this test, that 15-40% of phenols remained unextracted when the liquid/liquid extraction method with 80% methanol was applied. Solid phase extraction (C(18) cartridge) succeeded in retaining most of the phenols in the cartridge, but the recovery yield from the sorbent material was low. However, a new extraction method, based on the use of N,N-dimethylformamide (DMF) as an extraction solvent, achieved a complete extraction of phenols from oils. The proposed method requires a lower amount of oil, solvents, energy, and labor than the traditional ones. Because of the low concentration of phenols in the DMF extract, the highly sensitive electrochemical detector (EC) technique was studied. All of the phenols detected by the traditional UV detectors were also detected by EC using a coulometric array system. A rapid and complete analytical methodology of phenols in olive oil has been proposed based on coupling DMF extraction and EC detection.

Chromatography, High Pressure Liquid↗