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Biomedical subjects

A García

Publications and source records attributed to A García.

At least 19 recordsLinked to original sources
PubMed2001

Dramatic changes in the magnetic coupling mechanism for La-doped CaMnO3.

The exchange interactions in polycrystalline samples of Ca1-xLaxMnO3 (0.00< or =x< or =0.05) are studied by means of Raman scattering and electron paramagnetic resonance. Dramatic reductions in the spin-phonon interactions and magnetic correlations are observed for La doping levels as small as approximately 2%-3%. These results show that the charge carriers play an important role in the overall exchange coupling in the electron-doped manganites, even at very low doping levels.

Journal Article↗
PubMed2001

Multiple mechanisms of immune evasion can coexist in melanoma tumor cell lines derived from the same patient.

Progressive tumor growth may be associated with suppression of the immune response. Many different mechanisms may contribute to immune evasion. We investigated some of these mechanisms in melanoma cells lines generated from two patients. These cell lines show a complex pattern of altered HLA expression; however, the resulting phenotype did not satisfactorily explain the simultaneous evasion of T and NK cell cytotoxicity. Two additional alterations have now been detected in these melanoma cell lines: (1) resistance to FAS-induced apoptosis caused by defective FAS gene expression, and (2) constitutive expression of immunosuppressive cytokines. Our results show that several of the major mechanisms for immune evasion may coexist in a single tumor. This suggests that tumor progression may give rise to an extremely resistant phenotype, which may be an impediment to some immunotherapeutic strategies. We hypothesize that the simultaneous presence of several mechanisms involved in tumor immune evasion must be the result of progressive selection of characteristics that are advantageous for tumor survival in a competent host. Our findings do not support the possibility that FASL expression is a common mechanism of evasion of immune response in melanoma cells.

Apoptosis↗
PubMed2001

[Valaciclovir in the treatment of initial infection by genital herpes virus: comparative study].

BASIS: To know the therapeutic efficiency in the genital herpes of two drugs: acyclovir and valaciclovir. METHODS: There were included in the study 142 patients with diagnostic of clinic first episode by genital herpes in two equal groups of 71 patients each one. The distribution in both groups was random to receive one of the following treatment standards: acyclovir 200 mg by verbal each 5 hours, during 7 days; valaciclovir: 500 mg by verbal each 12 hours during 7 days being valued objective and subjective response to the treatment. RESULTS: The prevailing symptom was the pain (45% and 46.4%), followed by the warmth or burning sensation. The most frequent lesions in both groups were blisters (39.4% and 46.4%). The analysis response to the treatment in relationship to the symptoms as well as in the lesions it could be appreciated that there are not significant differences in the patients treated in both groups (p = 0.3). The adverse effect communicated by the discussed patients were scarce and similar in both groups. CONCLUSIONS: Both drugs are suitable for the treatment of the genital herpes. The advantage observed with the valaciclovir is the dosing comfort and the facility of completing the treatment.

Acyclovir↗
PubMed2001

Individual differences in the recovery of the hypothalamic-pituitary-adrenal axis after termination of exposure to a severe stressor in outbred male Sprague-Dawley rats.

Individual differences in the speed of recovery of the hypothalamic-pituitary-adrenal (HPA) axis response to immobilization in wooden boards (IMO) were studied in two experiments using a normal population of two months old male outbred Sprague-Dawley rats. In a first experiment, rats were subjected to 2 h IMO and were sampled, together with a group of control rats, at various times by the tail-nick procedure. Rats were divided into three groups depending on plasma corticosterone levels observed 2 h after termination of exposure to IMO: fast recovery (FR), intermediate recovery (IR) and slow recovery (SR). When the samples obtained at different times were classified in function of the three groups obtained at 2 h post-stress, no differences among groups were observed just after IMO. However, in the morning on the day after stress, all IMO rats showed higher plasma corticosterone levels than controls, but SR rats showed higher levels than FR rats, whereas IR rats were in between. Neither ambulatory activity in the open-field nor behaviour in the plus-maze was related to the HPA responsiveness to IMO. In a second experiment, there were no between-groups differences in ACTH and corticosterone levels obtained just after IMO. However, at 2 h, post-stress ACTH levels followed the same pattern as corticosterone. These data indicate that individual differences in the speed of recovery of the HPA axis after exposure to a severe stressor are not related either to individual differences in fear/anxiety or to the HPA response during exposure to the stressor. These individual differences in the capability to terminate the activation of the HPA axis after stress might be related to individual differences in the predisposition to develop stress-induced pathology.

Adrenal Glands↗
PubMed2001

Validated HPLC method for quantifying permethrin in pharmaceutical formulations.

An isocratic HPLC method for permethrin determination in raw material and pharmaceutical presentations as lotion and shampoo has been developed and validated following ICH recommendations. Cis and trans- isomers, impurities and degradation products are well separated. The chromatographic analysis were performed on a 4 microm particle C-18 Nova-Pak (Waters, Madrid, Spain) column (15 x 0.39 cm) kept in a Biorad column oven at 35 degrees C. Mobile phase consisted of methanol--water (78:22, v/v) at a flow rate of 1 ml/min. UV detection was performed at 272 nm and peaks were identified with retention times as compared with standards and confirmed with characteristic spectra using the photodiode array detector.

Chromatography, High Pressure Liquid↗
PubMed2001

Resolution of a mispaired secondary structure intermediate could account for a novel micro-insertion/deletion (387 insA/del 8 bp) in the PYGM gene causing McArdle's disease.

We report two siblings with McArdle's disease who are both compound heterozygotes for two non-identical frameshift mutations in the PYGM gene; a previously reported 753 delA in exon 18 and a novel 387 insA/del 8 bp in exon 10. The novel mutation is predicted to result in premature termination of translation 33 amino acids downstream of the site of mutation, potentially encoding a severely truncated protein of 419 amino acids instead of 841 amino acids. The complete lack of myophosphorylase activity observed in muscle derived from one sibling suggests that this mutation has deleterious functional consequences. The underlying mechanism of mutagenesis may have been slipped mispairing mediated by the formation of a Moebius loop-like secondary intermediate.

Adult↗
PubMed2001

General binocular disorders: prevalence in a clinic population.

The purpose of this paper was to study the prevalence of nonstrabismic accommodative and binocular dysfunctions in a clinical population. We examined 265 symptomatic patients who were chosen from an optometric clinic. We performed several tests to diagnose any form of refractive, accommodative or binocular dysfunction. Of the 265 subjects examined, 59 patients (22.3%) had some form of accommodative or binocular dysfunction and required not just the correction of the refractive error but a specific treatment for each of the problems diagnosed. The remaining subjects were classed as having refractive anomalies. The frequency of binocular dysfunctions was 12.9%, and 9.4% for accommodative anomalies. Convergence excess (4.5%) was more prevalent than convergence insufficiency (0.8%) and accommodative excess (6.4%) more prevalent than accommodative insufficiency (3%).

Accommodation, Ocular↗
PubMed2001

Effect of internal carotid artery occlusion on vertebral artery blood flow: a duplex ultrasonographic evaluation.

The aim of this study was to evaluate the effect of unilateral internal carotid artery occlusion on blood flow volume and blood flow velocities in both vertebral arteries using duplex Doppler ultrasonography in the cervical segment. Forty patients with unilateral extracranial internal carotid artery occlusion confirmed by angiography were studied, and the results were compared with those obtained in 57 age-matched patients in whom cervical duplex ultrasonography showed no abnormalities. We measured the diameter, flow velocities, and blood flow volume in both vertebral arteries, and the side-to-side differences were also calculated. Eleven patients (27.5%) with an occluded internal carotid artery had increased peak systolic velocity in the ipsilateral vertebral artery, and 6 (15%) had increased peak systolic velocity in the contralateral vertebral artery. The mean peak systolic velocity and the mean blood flow volume were statistically greater in the ipsilateral vertebral arteries than in the same-side vertebral arteries of the control group (P < .05). We also detected a mean increase of 14.29% of the net blood flow volume in the vertebral arteries compared with the control group. Patients with extracranial unilateral internal carotid artery occlusion may have a compensatory increase in both the peak systolic velocity and the blood flow volume in both vertebral arteries.

Aged↗
PubMed2001

Evidence that a single exposure to aversive stimuli triggers long-lasting effects in the hypothalamus-pituitary-adrenal axis that consolidate with time.

Because of its use as a negative reinforcer in animal studies and its potential pathological impact (e.g. post-traumatic stress disorder and depression), exposure to aversive stimuli is a relevant model for studying CNS plasticity. We present evidence that a single exposure to two predominantly emotional stressors [restraint in tubes and immobilization on wooden boards (IMO)] can modify the response of the hypothalamo-pituitary-adrenal (HPA) axis to a subsequent exposure to the same stressor days later in that a more rapid return to the baseline was observed in the poststress period. In addition, the effect was greater with IMO, the more severe stressor. Using IMO, we have further demonstrated that the effect of a previous single exposure to the stressor (i) increased with days elapsed between the two exposures; (ii) was specific for the previously experienced stressor; and (iii) was mediated via central-mediated effects [corticotropin-releasing factor (CRF) mRNA in the paraventricular nucleus of the hypothalamus]. These data suggest that animals retain memory about a single experience with stressors, resulting in an acceleration of the poststress recovery of the HPA axis that enhances progressively over a period of weeks. The extent to which the present data are relevant regarding post-traumatic stress disorders is unclear, but the study of the HPA response to severe stressors may be suitable for the study of the neurobiological basis of the progressive consolidation of learning over a long period of time (days to weeks).

Animals↗
PubMed2001

In vitro antibacterial activity of Chilean red wines against Helicobacter pylori.

The antibacterial activity of sixteen Chilean red wines (Cabernet Sauvignon, Cabernet Merlot, Cabernet Organic and Pinot Noir), and the active extracts of two randomly selected wines were assayed for their antibacterial activity on six strains of Helicobacter pylori isolated from gastric biopsies. The active fraction of the wines was obtained by dichloromethane extraction, and the antibacterial activity of the wines and extracts was evaluated by an agar diffusion method. All the red wines studied showed some antibacterial activity on the six strains of H. pylori, although the strains were heterogeneous in their susceptibility to each particular wine. The active fraction of the two wines selected also showed good activity against the strains tested. The main active compound was identified as resveratrol. The results presented indicate that Chilean red wines have antibacterial activity against H. pylori, which depends mainly on the presence of resveratrol.

Anti-Bacterial Agents↗
PubMed2001

[Minimally deviated adenocarcinoma (malignant adenoma) of the cervix uteri].

Minimal deviation adenocarcinoma (adenoma malignum) is a rare well-differentiated form of invasive cervical adenocarcinoma. Because of its rarity and cytologic changes are subtle there are only a few reports of this pathology, been necessary the realization of large biopsy of the cervical tissue for it histological diagnosis. We made a review in the period 1994-2000, of the clinical, cytological, histological features, treatments and follow-up of 4 patients in the Gynecologic Oncology Department of the University Hospital Vall d' Hebron, Barcelona, Spain.

Adenocarcinoma↗
PubMed2001

[Serological certification of the interruption of the vectorial transmission of Chagas disease in Chile].

BACKGROUND: In 1999 an International Commission of Experts evaluated the sanitary interventions that started in 1980 to eliminate Triatoma infestans, the biological vector of Chagas disease, to certify if the conditions needed to interrupt the transmission, were achieved. AIM: To report the data used by the International certification commission to certify the interruption of vectorial transmission of Chagas disease in Chile. MATERIAL AND METHODS: A comparative evaluation of the prevalence of Trypanosoma cruzi antibodies in children surveyed between 1994 and 1995 and between 1995 and 1999. RESULTS: In the first period, 5,948 children were surveyed and in the second, 5,069 children were studied. Twenty children (0.4%) were positive for Trypanosoma cruzi antibodies in the second survey. These figures were significantly lower than the 1.1% prevalence detected between 1994 and 1995. In only three of the 20 cases, the transmission through vectors was confirmed, which represents a 99.4% reduction of this way of transmission. CONCLUSIONS: Based on these findings, the Commission certified that Chile is the second country in Latin America to interrupt the vector transmission of Chagas disease. The successful public health program for Chagas disease will have a positive impact improving the quality of life of rural populations, that are most exposed to the disease.

Animals↗
PubMed2000

Surfactant protein genetic marker alleles identify a subgroup of tuberculosis in a Mexican population.

Pulmonary surfactant and its components are essential for normal lung function and are involved in local host defense. Surfactant protein (SP)-A and SP-D bind to and modulate phagocytosis of Mycobacterium tuberculosis by macrophages. Frequency comparisons of SP marker alleles in tuberculosis patients and healthy control subjects (tuberculin-skin test positive or general population) were performed. Regression analyses of the tuberculosis and the tuberculin-skin test positive groups revealed, on the basis of odds ratios, tuberculosis susceptibility (DA11_C and GATA_3) and protective (AAGG_2) marker alleles. Similarly, between tuberculosis patients and general population control subjects, susceptibility 1A(3), 6A(4), and B1013_A and protective AAGG_1, and AAGG_7 marker alleles were observed. Moreover, interactions were seen between alleles 6A(2) and 1A(3) (P=.0064) and between 1A(3) and B1013_A (P=. 036). The findings indicate a possible involvement of SP alleles in tuberculosis pathogenesis.

Adult↗
PubMed2000

Shape of the 8B alpha and neutrino spectra.

The beta-delayed alpha spectrum from the decay of 8B has been measured with a setup that minimized systematic uncertainties that affected previous measurements. Consequently the deduced neutrino spectrum presents much smaller uncertainties than the previous recommendation [J. N. Bahcall et al., Phys. Rev. C 54, 411 (1996)]. The 8B nu spectrum is found to be harder than previously recommended with about (10-20)% more neutrinos at energies between 12-14 MeV. The integrated cross sections of the 37Cl, 71Ga, 40Ar, and Super-Kamiokande detectors are, respectively, 3.6%, 1.4%, 5.7%, and 2.1% larger than previously thought.

Journal Article↗
PubMed2000

Perineurium contributes to axonal damage in acute inflammatory demyelinating polyneuropathy.

OBJECTIVE: To assess if axonal damage in severe acute inflammatory demyelinating polyneuropathy (AIDP) correlates with the appearance of epiperineurium in nerve trunks. BACKGROUND: Increase of endoneurial fluid pressure in nerve trunks possessing epiperineurium may be an important mechanism of axonal damage in AIDP. METHODS: A 79-year-old man had a 2-day history of acroparesthesias and ascending paralysis culminating in quadriplegia, bilateral facial palsy, and mechanical ventilation. Five intravenous immunoglobulin cycles were given without response. He died on day 60. Electrophysiologic studies (days 4, 17, and 50) initially showed normal nerve conduction velocities with further slowing, progressive attenuation of compound muscle action potentials, and profuse denervation. The authors studied the preforaminal anterior and posterior L3 and L5 spinal roots, third and fifth lumbar nerves and their branches, and femoral and sural nerves. RESULTS: Density of myelinated fibers was preserved in L5 ventral and dorsal roots and reduced in sural nerve. Mild de-remyelination was observed in lumbar roots. In both lumbar nerves and their branches, there were extensive de-remyelination and centrofascicular or wedge-shaped areas with marked loss of large myelinated fibers. Axonal degeneration was the predominant lesion in sural nerve. CONCLUSION: The presence of epiperineurium correlates with a drastic change of pathology with superimposed ischemic lesions and distally accentuated axonal loss, suggesting that endoneurial fluid pressure increase could cause axonal damage in AIDP.

Action Potentials↗
PubMed2000

Development and validation of a capillary electrophoresis method for direct measurement of isocitric, citric, tartaric and malic acids as adulteration markers in orange juice.

Fruit juices each have very distinct organic acids profiles that can be used as fingerprints for establishing authenticity. A method has been developed, optimised and validated for measuring by capillary electrophoresis citric, isocitric, malic and tartaric acids as authenticity markers in orange juices, without any sample treatment other than dilution and filtration. Final conditions were phosphate buffer 200 mM, pH 7.50, -14 kV as applied potential, and 57 cm length neutral capillary. Detection was direct UV at 200 nm. Different kinds and marks of orange juice, chosen from the great variety existent in the market, were analysed and clear differences could be found between them and just pressed orange juice.

Beverages↗