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Biomedical subjects

A García

Publications and source records attributed to A García.

At least 91 records · Page 5Linked to original sources
PubMed2001

Measurement of nephrolithiasis urinary markers by capillary electrophoresis.

A previously developed method for screening organic acidurias by capillary electrophoresis has been validated for oxalate and citrate measurement in urine. Sample pretreatment is minimum, just acidification and centrifugation. Detection is by direct UV. Validation parameters of the method can be considered adequate. Response is linear for both analytes in standards and samples. The assayed ranges were 200-1,000 mg/l for citrate and 10-200 mg/l for oxalate. Recoveries ranged from 99.4+/-3 to 101.7+/-2.4%, maximum imprecision in oxalate concentration was of 7.6% RSD and limits of detection in samples were 0.67 mg/l for oxalate and 25.9 mg/l for citrate, both lower than the measured values in samples. Identification of increased glyoxylic (oxoacetic acid) and glyceric acids (2,3-dihydroxy propanoic) are also included to facilitate the diagnosis.

Biomarkers↗
PubMed2001

Diagnostic strategy for familial and sporadic cases of neuropathy associated with 17p11.2 deletion.

Clinical, electrophysiologic and molecular studies were performed on at-risk members of 14 families with hereditary neuropathy with liability to pressure palsies (HNPP), in order to detect asymptomatic carriers of the 17p11.2 deletion. Sporadic cases due to de novo deletion accounted for 21% of the investigated HNPP families. Approximately one half of deletion carriers were asymptomatic and did not display significant signs on clinical examination. The electrophysiologic hallmark in both symptomatic and asymptomatic deletion carriers was the presence of a nonuniform sensorimotor demyelinating polyneuropathy with conduction abnormalities preferentially located at common entrapment sites and distal nerve segments. A perfect correlation was found between the molecular and electrophysiologic analyses. A reliable screening method to detect clinically unaffected carriers of the deletion in families with HNPP was the evaluation of motor conduction in at least two nerves across usual entrapment sites, especially the ulnar nerve at the elbow, and evaluation of sensory conduction in the sural nerve. In sporadic cases due to a de novo deletion, electrophysiologic studies were suggestive but not sufficient for the diagnosis, and molecular analysis represented the most sensitive diagnostic tool.

Adult↗
PubMed2001

Mutagenicity and antioxidant assessment of Stachitarpheta jamaicensis (L.) Vahl.

Stachitarpheta jamaicensis (L.) Vahl. is a member of the Verbenaceae commonly used in Cuba, mainly as vermifugue and against diarrhoea. The mutagenic potential of a hydroalcohol extract of its aerial parts was assessed in vitro using the Salmonella/microsome assay and in vivo in the mouse bone marrow micronucleus test. No positive response was observed in a battery of four Salmonella typhimurium strains employed: TA 1535, TA 1537, TA 98 and TA 100, when exposed to concentrations up to 5 mg/plate, with and without mammalian metabolic activation. In the same way, no increase in the micronucleus frequency in mitotic erythropoietic tissue was observed when animals were administered the extract orally in doses of 500, 1000 and 2000 mg/kg. The extract inhibited lipid peroxidation in the rat liver microsomal fraction (IC(50) = 3.6 microg/mL) but it does not seem to be an effective.OH radical scavenger (IC(50) = 76.7 microg/mL). Noteworthy, it increased in a dose dependent way the level of revertant colonies in E. coli IC 203, a strain sensitive to oxidative mutagenesis, when assayed together with hydrogen peroxide and ferrous sulphate, which suggests a pro-oxidant action.

Animals↗
PubMed2001

Neuroendocrine cervical carcinoma: a diagnostic and therapeutic challenge.

OBJECTIVE: The aim of this study was to analyze diagnostic criteria, response to chemotherapy, rate and site of relapse, and overall survival (OS) in neuroendocrine cervical carcinoma. METHODS: Twenty patients were included. Stage was Ia(2) in 1 case, Ib(1) in 4, Ib(2) in 4, II in 5, IIIb in 2, IVa in 2, and IVb in 2. Patients with stage Ib(2) or greater received neoadjuvant chemotherapy (NCH). Eighteen patients were operated on. Immunohistochemistry was performed on the surgical specimens. Statistical analysis included the Kaplan-Meier method and the chi(2) and log-rank tests. RESULTS: The response to NCH was <50% in 2/13 cases (15.3%), >50% in 9/13 (69.4%), and complete in 2/13 (15.3%). Cytokeratin was positive in 17/18 cases, neuron-specific enolase in 15/18, chromogranin in 9/18, and synaptophysin in 8/18. Tumor was pure in 12 cases. Two cases had simultaneous ovarian carcinoma. Positive nodes were observed in 9/20 pts (45%). Tumors <4 cm had no recurrences. Pure tumors >4 cm had distant relapses (6/11). Mixed tumors >4 cm had 2/6 pelvic and 3/6 lung metastases. OS was 39%. When the initial tumor volume was <4 cm OS was 76%, and it was 18% for tumors >4 cm (P < 0.05). OS was 58% when the residual tumor after NCH was <2 cm and 21% when it was >2 cm (P < 0.05). When the tumor was pure OS was 54% and 19% when it was mixed (P < 0.05). OS was 72% among pts with negative nodes and 11% for those with positive nodes (P < 0.01). CONCLUSIONS: (1) Stage IV was frequent (20%); (2) Response to NCH was high; (3) The pattern of relapse differs for mixed tumors; (4) For tumors <4 cm outcome is similar to that of squamous carcinoma.

Adult↗
PubMed2001

Determination of trace amounts of lead in mussels by flow-injection flame atomic-absorption spectrometry coupled with on-line minicolumn preconcentration.

A minicolumn packed with poly(aminophosphonic acid) chelating resin incorporated in an on-line preconcentration system for flame atomic-absorption spectrometry was used to determine ultratrace amounts of lead in mussel samples at microg L(-1) level. The preconcentrated lead was eluted with hydrochloric acid and injected directly into the nebulizer for atomization in an air-acetylene flame for measurement. The performance characteristics of the determination of lead were: preconcentration factor 26.8 for 1 min preconcentration time, detection limit (3sigma) in the sample digest was 0.25 microg g(-1) (dry weight) for a sample volume of 3.5 mL and 0.2 g sample (preconcentration time 1 min), precision (RSD) 2.3% for 25 microg L(-1) and 2.0% for 50 microg L(-1). The sampling frequency was 45 h(-1). The method was highly tolerant of interferences, and the results obtained for the determination of lead in a reference material testify to the applicability of the proposed procedure to the determination of lead at ultratrace level in biological materials such as mussel samples.

Animals↗
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

Assessment of mutagenicity in Parthenium hysterophorus L.

The mutagenic potential of a crude extract of Parthenium hysterophorus L. was assessed in the Salmonella/microsome (Ames) assay and the mouse bone marrow micronucleus test. Results in the bacterial mutagenicity assay were negative for the five strains employed, e.g. TA 1535, TA1537, TA 98, TA 100 and TA 102, while cytotoxicity was evident in all cases at 5000 microg per plate, the highest concentration assayed. A decrease in toxicity was observed with exogenous mammalian metabolic activation (S9) or glutathione (5 micromol per plate). When mutagenicity was monitored after column chromatography fractionation of the crude, fraction 1 was mutagenic in strain TA 98 (+S9). Besides, cytotoxicity was found in fraction 5, where parthenin was eluted. The micronucleus test was negative in mice upon oral administration, at doses up to 96 mg of crude per kg. Bone marrow toxicity was not observed. The crude extract exhibited some in vitro pro-oxidant activity. It also inhibited lipid peroxidation (IC(50)=4.1 microg/ml) but failed to act as .OH scavenger.

Animals↗
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

A new mtDNA mutation in the tRNA(Leu(UUR)) gene associated with ocular myopathy.

We studied a patient with ptosis, ophthalmoparesis, and exercise intolerance who showed in her muscle biopsy ragged-red fibers and combined defects of the complexes I and IV of the mitochondrial respiratory chain. Molecular analysis revealed a T3273C transition in the mitochondrial DNA tRNA(Leu(UUR)) gene. The mutation was heteroplasmic and very abundant in muscle from the proposita, less abundant in her other tissues studied, and still less abundant in blood from her maternal relatives. Single muscle fiber analysis showed significantly higher levels of mutant genomes in ragged-red fibers than in normal fibers. The T3273C mutation affects a strictly conserved base pair in the anticodon stem and was not found in controls, thus satisfying the accepted criteria for pathogenicity.

Base Sequence↗
PubMed2001

Acid hydrolysis of secoiridoid aglycons during storage of virgin olive oil.

The main change found in the phenolic composition of virgin olive oils of Arbequina, Hojiblanca, and Picual varieties during storage in darkness at 30 degrees C was the hydrolysis of the secoiridoid aglycons. This reaction gave rise to an increase in the free phenolics hydroxytyrosol and tyrosol in the oil. Filtration of oil and acidity influenced the hydrolysis to a large extent. Thus, the addition of commercial oleic acid to Hojiblanca and Picual oils increased the hydrolysis rate of the secoiridoid aglycons. In contrast, the concentration of lignans 1-acetoxypinoresinol and pinoresinol remained constant during storage. It must also be stressed that the total molar concentration of the phenolic compounds analyzed in the oils changed slightly (<20% reduction) after one year of storage, which is important from a nutritional point of view. However, the transformation of the secoiridoid aglycons into free phenolics may have consequences on oil taste and antioxidant capacity.

Acids↗
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

Field sample preconcentration of copper in sea water using chelating minicolumns subsequently incorporated on a flow-injection-flame atomic absorption spectrometry system.

A field flow preconcentration system for copper determination in seawater is described. Seawater samples are collected and preconcentrated in situ by passing them using a peristaltic pump through a minicolumn packed with Amberlite XAD-4 impregnated with the complexing agent 1-(2-pyridylazo)-2-naphthol. Thus, copper is preconcentrated without the interference of the saline matrix. Once in the laboratory, the minicolumns loaded with copper are incorporated on a flow injection system and eluted with a small volume of a 20% (v/v) ethanolic solution of 0.5 mol L-1 hydrochloric acid into the nebuliser-burner system of a flame atomic absorption spectrometer. The analytical figures of merit for the determination of copper are as follows: detection limit (3s), 0.06 microgram L-1; precision (RSD), 1.2% for 2 micrograms L-1; enrichment factor, 30 (using 25 mL of sample and 83 microL of eluent). Analysis of certified reference materials (SLEW-3 and NASS-5) showed good agreement with the certified value. This procedure was applied to the determination of copper in seawater samples from Galicia (Spain).

Copper↗
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↗