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Biomedical subjects

A Gutierrez

Publications and source records attributed to A Gutierrez.

At least 73 records · Page 4Linked to original sources
PubMed1996

Hepatitis C in human immunodeficiency virus-coinfected patients: increased variability in the hypervariable envelope coding domain.

Patients coinfected with the hepatitis C virus (HCV) and the human immunodeficiency virus (HIV) were studied with regard to nucleotide sequence variability in the E2/NS1 first hypervariable region of the HCV genome. The nucleotide variability within individual patients was compared to patients infected only with HCV. The proportion of predicted synonymous and nonsynonymous amino acid changes, and the relationship to putative high-antigenicity sites, were evaluated in the hypervariable envelope domain. Ninety-one clones from 10 patients with HCV/HIV coinfection were sequenced, following polymerase chain reaction (PCR) amplification of the hypervariable region. The control HCV group included 53 clones from 7 patients. Sequence analysis encompassed the region coding for amino acids 384 to 414. Consensus sequences from each patient were used as the internal standard for nonsynonymous amino acid codon variability. Cumulative proportional comparison at each amino acid site revealed increased variability in HCV RNA from patients with HCV/HIV coinfection versus HCV alone (P < .05). The greatest variability was observed at amino acids 386, 397, 400, 402, 405, 407, and 414, with >l0 percent clonal variation at these sites. Jameson-Wolf plots were used to predict putative high-antigenicity domains. Nonsynonymous clonal variation resulted in alteration of putative antigenic sites within the hypervariable region. All clones had at least one high-probability site. Clones with unique predicted antigenic domains were observed more frequently in HIV/HCV coinfected patients, and, independent of viral titer, were consistent with increased sequence variability. These data suggest an accumulation of envelope variants in the HCV/HIV coinfected patients, which could be related to ineffective viral clearance, and may help explain prior reports of interferon (IFN) resistance in this patient group.

Adult↗
PubMed1996

Protein catabolism in maintenance haemodialysis: the influence of the dialysis membrane.

A high prevalence of malnutrition has been reported in dialysis patients. Anorexia and vomiting associated with the uraemic state and increased protein breakdown induced by acidosis are some of the factors suggested to contribute to the development of malnutrition in these patients. There is evidence that the haemodialysis procedure per se promotes increased net protein catabolism. In healthy subjects, the passage of blood through a cuprophane dialyser without circulating dialysate leads to increased efflux of amino acids from muscle tissues, indicating that accelerated protein breakdown may be caused by the interaction between blood and regenerated cellulose membranes. The use of more biocompatible membranes, such as polysulfone and polyacrylonitrile, does not result in increased muscle protein catabolism. Loss of nutrients to the dialysate during clinical haemodialysis has been considered as an additional catabolic factor. Some recent reports indicate that, compared to low flux dialysers, the use of high flux membranes results in greater disturbances of plasma amino acid caused by increased loss to the dialysate. Thus, not only bioincompatibility but also the physical properties of the dialysis membrane seem to be involved in haemodialysis-related protein catabolism.

Amino Acids↗
PubMed1996

Analysis of Lignin-Polysaccharide Complexes Formed during Grass Lignin Degradation by Cultures of Pleurotus Species.

A brown material, precipitable with ethanol, was formed during wheat straw and lignin degradation by liquid cultures of different species of Pleurotus. Fourier transform infrared spectroscopy and cross-polarization and magic-angle-spinning (sup13)C nuclear magnetic resonance spectroscopy showed that most of the precipitable material was formed from exopolysaccharide secreted by the fungus but it also contained an aromatic fraction. The results of acid hydrolysis, methylation analysis, and Smith degradation indicated that the major exopolysaccharide produced by these fungi is a (1(symbl)3)-(beta)-glucan branched at C-6 every two or three residues along the main chain. The presence of lignin or straw in the culture medium had little effect on the composition and structure of the extracellular polysaccharide. Cross-polarization and magic-angle-spinning (sup13)C nuclear magnetic resonance spectroscopy provided an estimation of the aromatic content of the lignin-polysaccharide complexes, assigning 20% of the total (sup13)C signal in the material recovered from cultures of Pleurotus eryngii in lignin medium to aromatic carbon. Analytical pyrolysis indicated that the aromatic fractions of the lignin-polysaccharide complexes were derived from lignin, since products characteristic of pyrolytic breakdown of H (p-hydroxyphenylpropane), G (guaiacylpropane), and S (syringylpropane) lignin units were identified. These complexes cannot be fractionated by treatment with polyvinylpyrrolidone or extraction with lignin solvents, suggesting that the two polymers were chemically linked. Moreover, differences in composition with respect to the original lignin indicated that this macromolecule was modified by the fungi during the process of formation of the lignin-polysaccharide complexes.

Journal Article↗
PubMed1996

Traumatic aneurysm of the basilar artery.

We report a case in which a "false" aneurysm of the basilar artery developed after an assault on a patient resulting in head injuries. Diagnostic imaging and endovascular treatment are described. Formation mechanisms of traumatic intracranial aneurysms are discussed and the literature is reviewed.

Adult↗
PubMed1995

Prediction of recurrence in B-C stages of colorectal cancer by p53 nuclear overexpression in comparison with standard pathological features.

This study investigated the predictive value of p53 nuclear overexpression on recurrence of colorectal adenocarcinomas compared with established prognostic pathological features. Sixty-one paraffin-embedded sections from primary tumours were examined by immunohistochemistry. Specific nuclear staining was detected in 27 (44.2%) cases. Positivity was more frequent in tumours with venous invasion (76.9%) (P = 0.06) and in rectal cancer (68.4%) (P = 0.06). After a median observation time of 46 months, p53-positive tumours exhibited a higher percentage of recurrence (40.7% vs 11.7%) (P = 0.03), and a higher likelihood of relapse at 5-year follow-up (46% vs 13%) (P = 0.006). Among the pathological variables analysed, only the extent of bowel wall invasion showed a relationship with recurrence. After adjustment for the other covariates in a Cox's regression model, p53 overexpression was the only factor showing independent prognostic significance (hazard ratio: 4.96; 95% Confidence Interval (CI): 1.47-16.71) (P = 0.012). The results of this study show that nuclear p53 protein overexpression has higher predictive value than standard pathological variables.

Adenocarcinoma↗
PubMed1995

Association between HLA class II antigens and primary antiphospholipid syndrome from the south of Spain.

Recent studies have suggested an association between primary antiphospholipid syndrome (PAPS), antiphospholipid antibodies and some major histocompatibility complex (MHC) antigens. We have studied the relationship between MHC class II antigens and PAPS in 19 patients from the south of Spain. Univariant analysis showed an association between PAPS and HLA-DQ7 (47% vs 25%l P = 0.3), DR4 (32% vs 16%; P = 0.08) and DQ3 (63% vs 39%; P = 0.04). However, multivariant analysis confirmed the association with DQ7 (RR = 2.5; CI 80%: 1.3-4.7) and DR4 (RR = 2.2; CI 80%: 1.1-4.4) but not with DQ3. When we introduced DRw53 into this analysis, we noticed a DR4 confounding effect, with DQ7 (RR = 3.1; CI 80%: 1.7-5.8) and Drw53 (RR = 2.3; CI 80%: 1.2-4.4) remaining as the most important HLA antigens related to PAPS. In conclusion, in PAPS patients from the South of Spain, HLA-DQ7 antigen showed the highest relative risk for PAPS, followed by DRw53.

Abortion, Spontaneous↗
PubMed1994

Hemodialysis-associated protein catabolism with and without glucose in the dialysis fluid.

The effects of hemodialysis on protein and energy metabolism were studied in eight hemodialysis patients. The leg exchange of amino acids (AA) was measured during hemodialysis using a dialysis fluid with 10 mmol/liter glucose (GD) or without glucose (GFD). Arterial AA concentrations decreased by about 30% in GD and GFD. During dialysis, similar increases in the efflux of AA from leg tissues (mainly muscle) were observed in GD and GFD (basal 105 +/- 104, vs. 71 +/- 62 nmol/min/100 g tissue; dialysis 295 +/- 46 vs. 289 +/- 60 nmol/min/100 g tissue). The efflux of AA remained largely unchanged at one hour after the end of GD and GFD. Losses of AA to the dialysate were similar during GD (8.3 +/- 0.9 g) and GFD (7.9 +/- 0.4; NS). GFD resulted in a loss of 26 g of glucose whereas 30 of glucose was absorbed during GD. The amount of urea removed by dialysis and the post-dialysis increase in plasma urea were similar in GD and GFD. In conclusion, the addition of glucose to the dialysis fluid may help the energy balance, but it does not appear to reduce the negative effects of hemodialysis on protein metabolism.

Aged↗
PubMed1994

The subunit composition of a GABAA/benzodiazepine receptor from rat cerebellum.

The pentameric subunit composition of a large population (36%) of the cerebellar granule cell GABAA receptors that show diazepam (or clonazepam)-insensitive [3H]Ro 15-4513 binding has been determined by immunoprecipitation with subunit-specific antibodies. These receptors have alpha 6, alpha 1, gamma 2S, gamma 2L, and beta 2 or beta 3 subunits colocalizing in the same receptor complex.

Amino Acid Sequence↗
PubMed1994

Water and urea diffusive permeabilities in isolated proximal tubule cells.

We measured the water (3H2O) and urea ([14C]urea) diffusive permeabilities (Pd) in intact proximal tubule cells (PTC). Isolated rabbit PTC were packed in polyethylene tubes to measure the diffusion coefficients for 3H2O and [14C]urea at 14 degrees C. Pd values for water and urea were estimated from the diffusion coefficients in intact cells, in extracellular and in intracellular media using a model of parallel and series diffusion in the packed PTC. Pd was 65 +/- 8 and 18 +/- 3 microns/s for water and urea, respectively. We examined the effect of different pharmacological agents on the Pd values for water and for urea. p-Chloromercuribenzenesulfonate at 2 mM markedly inhibited the Pd of water and urea. Phloretin (1 mM) inhibited the Pd for urea, whereas it increased Pd for water. KMnO4 (30 microM) markedly inhibited urea Pd but did not alter water Pd. The values for energy of activation of Pd for water and for urea were 2.9 +/- 2 and 7.3 +/- 4 kcal/mol, respectively. These results show that water and urea do not share the same pathway across the PTC membrane.

Animals↗
PubMed1994

Biocompatibility of hemodialysis membranes: a study in healthy subjects.

The effect of blood-membrane interaction on several biocompatibility parameters has been investigated. Four groups of healthy subjects underwent sham hemodialysis, i.e. the establishment of blood-dialysis membrane contact, but without circulating dialysate, using cellulose-based membranes (regenerated cellulose and cellulose acetate) or synthetic membranes (polysulfone and polyacrilonitrile). Contact between blood and cellulose-based membranes resulted in pronounced complement activation and leukopenia whereas contact between blood and synthetic membranes induced weak complement reaction. The release of granulocytic elastase comparable to that obtained during clinical dialysis seemed to correlate directly with the types of membrane used. The gradual increase in the level of plasma elastase during blood-membrane contact, as opposed to the transient nature of the increase in the levels of complement, suggests that different mechanisms are responsible for these reactions. Nutritional implications of dialysis membrane bioincompatibility are discussed in the light of recently published metabolic data obtained in these subjects.

Acrylic Resins↗
PubMed1994

Lymphocyte subpopulations in patients with primary fibromyalgia.

OBJECTIVE: Fibromyalgia (FM) is a clinical entity of unknown etiology frequently diagnosed in rheumatology. The potential involvement of the immune system in its pathogenesis has been suggested. Studies of abnormal T cell subpopulations often have been inconclusive. We attempted to clear this point by comparing lymphocyte subpopulations, including some of the newer activation markers, in patients with FM and healthy controls. METHODS: Sixty-five patients with FM and 56 healthy controls were studied. Flow cytometry was used as a quantification technique to measure lymphocyte subpopulations, CD3 (T cells), CD19 (B cells), CD16 (natural killer cells), CD4 (T helper/inducer cells), CD8 (T cytotoxic/suppressor cell), CD25 (interleukin 2 receptor), CD69 (activation inducer molecule marker), CD71 (transferrin receptor) and CD54 (ICAM-1); CD4/CD8 ratios were also estimated. RESULTS: The number of T cells expressing activation markers CD69 and CD25 was decreased in patients with FM; the other subpopulations were similar in patients and controls. CONCLUSION: Our results suggest a defect in T cell activation in patients with FM.

Adolescent↗
PubMed1994

Preliminary clinical experience with a thermal balloon endometrial ablation method to treat menorrhagia.

OBJECTIVE: To evaluate the clinical effectiveness and safety of a thermal balloon system to ablate the endometrium. METHODS: All 18 patients were candidates for hysteroscopic endometrial ablation or hysterectomy for menorrhagia and consented to a trial of the balloon technique of ablation. All procedures were done in the operating room under general anesthesia, except in one patient who had regional and another who had local anesthesia with analgesia. Follow-up of 6-34 months is reported. RESULTS: Fifteen subjects (83%) reported significant reduction in bleeding or amenorrhea. Two patients underwent subsequent hysterectomy and one a follow-up hysteroscopic examination with biopsy. Histology in these three cases showed areas of scar as well as areas of normal endometrial histology. In one uterus, the entire cavity and the endometrium were normal. The others had endometrial bands of scar and some contraction of the cavity. CONCLUSIONS: Based on follow-up results, the frequency of successful reduction of bleeding and/or amenorrhea in this small series is comparable to hysteroscopic methods of endometrial ablation. There were no complications. A larger trial is warranted to compare this method to hysteroscopic endometrial ablation.

Catheter Ablation↗