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Biomedical subjects

A Vázquez

Publications and source records attributed to A Vázquez.

At least 19 recordsLinked to original sources
PubMed1997

[Diagnosis of renovascular disease by heart catheterization].

Atherosclerotic renovascular disease is a common entity, particularly in persons older than 50 years of age and especially in those patients with other evidence of atherosclerotic vascular disease. The illness clearly progresses in some patients, and progression rate appears to be highly variable. Taken into account the apparent high prevalence of renovascular disease in older persons, it is possible that this disorder be the cause of end stage renal disease in 5% to 15% of patients currently entering the dialysis program each year. Surgery and percutaneous angioplasty can both improve renal function in patients with renal artery stenosis. We describe a patient in whom the detection of renovascular disease was made accidentally at the time of coronary arteriography. He presented an acute renal failure after use of angiotensin-converting enzyme inhibitors and/or contrast media associated nephrotoxicity, and was treated with percutaneous transluminal balloon angioplasty and had a successful outcome.

Acute Kidney Injury↗
PubMed1997

The tryptophan/histidine interaction in alpha-helices.

Contacts between aromatic and charged residues are often found in proteins. Mutational studies have shown that a tryptophan/charged histidine pair can stabilise a protein by more than 1 kcal mol(-1). We have used circular dichroism and nuclear magnetic resonance to study the helical content of several peptides in which a tryptophan/histidine pair was placed at i, i + 3 or i, i + 4 in either the N to C or the C to N orientation. Our data indicate that the WH i, i + 4 geometry is the most stabilising one (when the histidine is protonated) and gives rise to the highest helical content. Little preference is observed among the three other orientations. The energy of the WH+ i, i + 4 interaction (calculated with AGADIR and SCINT) is about 1 kcal mol(-1). A statistical analysis of the occurrence of tryptophan/histidine pairs in alpha-helices of natural proteins reveals that, although the WH i, i + 4 pairs are not more abundant than the others, in most of the WH i, i + 4 pairs the two side-chains are in contact, but not in the other three orientations. These results suggest that the conformational stability of proteins could be increased by means of solvent-exposed intrahelical i, i + 4 tryptophan-histidine bridges and that these bridges could be useful to tailor the stability of helical peptides at physiological pH.

Amino Acid Sequence↗
PubMed1997

Concentrated ascitic fluid reinfusion in cirrhotic patients: a simplified method.

A new method for ascites filtration and reinfusion, which uses a single Cuprophan filter and is performed in the dialysis unit, is reported. Thirty-one procedures were performed in 17 patients with cirrhosis and massive ascites. A mean volume of 8.6 L of ascitic fluid was removed; from this volume, 5 L were ultrafiltered and a concentrated ascitic fluid was reinfused (x = 359.8 mL). The whole procedure was completed in a mean time of 248 minutes. No relevant method-related complications were detected. Moreover, no significant changes in blood urea nitrogen (BUN), creatinine, plasma and urinary electrolytes, or platelet count were found, even in the case of repeated procedures (two to nine times). The reinfused fluid contained a mean value of albumin of 4.7 g/dL and significant amounts of globulins and complement. The overall cost of the materials used in the procedure ($49.46) offered competitive advantages with respect to other types of frequently used methods. In conclusion, we present a safe, effective, and time- and cost-saving technique for ascites reinfusion that represents an advantageous alternative to more complicated and expensive methods or to the currently used medical therapy.

Ascites↗
PubMed1996

Glanzmann thrombasthenia in children from Argentina.

PURPOSE: Glanzmann thrombasthenia is a well-defined inherited disorder of platelet function characterized by a decrease or absence of functional platelet glycoprotein (GP) GPIIbIIIa. The diagnosis must be considered in patients presenting with mucocutaneous bleeding, purpura, a normal platelet count, abnormal platelet aggregation, and a prolonged bleeding time. In most of the patients, the presence of small amounts of either GPIIb or GPIIIa was detected in their platelets. These observations could provide a basis for determining the clinical and laboratory heterogeneity of the disease. PATIENTS AND METHODS: We studied 10 patients of seven unrelated families with the usual methods and an immunoalkaline phosphatase technique (APAAP) to analyze the biosynthesis of GP in megakaryocytes. RESULTS: The results allowed us to classify six patients as GT type I, three as type II, and one as a variant. CONCLUSION: The nature and severity of the bleeding manifestations, in our patients, were not predictible by the laboratory findings. These confirm the clinical and laboratory heterogeneity of the disease.

Adolescent↗
PubMed1995

Association between the oxidative polymorphism and early onset of Parkinson's disease.

The frequency of five cytochrome P450IID6 allelic variants was studied in deoxyribonucleic acid from 123 patients with Parkinson's disease and 150 healthy volunteers. This was achieved by the use of mutation-specific polymerase chain reaction and restriction fragment length polymorphism. The analyses of the CYP2D6 genotype revealed no evidence for a higher prevalence of poor metabolizers among patients with Parkinson's disease. However, increased frequency of patients with Parkinson's disease with the genotype CYP2D6wt/CYP2D6B was observed. This is attributable exclusively to subjects with early onset of the disease (28 to 49 years), with a relative risk ratio of 4.16 (95% confidence limits, 2.0 to 8.3; p < 0.0005). The subjects who had late-onset Parkinson's disease (> or = 50 years) had genotypes and CYP2D6 allele frequencies similar to the healthy subjects. This indicates that the oxidative polymorphism is related to early-onset but not to late-onset Parkinson's disease. A different influence of CYP2D6 genotype on the risk of development of Parkinson's disease is observed in Spaniards, compared with previous findings in British subjects. These results suggest the combined effect of environmental toxins and CYP2D6 in the cause of Parkinson's disease.

Adult↗
PubMed1995

[Alveolar lipoproteinosis treated by bronchopulmonary lavage].

Alveolar lipoproteinosis is a rare disease, a review of the Spanish Medical Index for 1971 to June 1994 showing only 9 reported cases. The intra-alveolar deposit of lipoprotein-type matter produces severe hypoxemia and favors infection by opportunistic germs. Treatment with massive bronchial lavage (MBL) removes the matter from the alveolar space, improves gas exchange and decreases the risk of infection. We report a case of primary alveolar lipoproteinosis treated with MBL in which the patient developed infections by Aspergillus fumigatus before lavage and after starting steroid treatment. The procedure was performed without complications, with significant clinical and gasometric improvement. The natural evolution of this disease is poorly understood. Spontaneous remissions have been observed, and as MBL is not a risk-free procedures, its use in treatment is controversial. We believe that when severe hypoxemia is present, MBL should be used early, when the risk is slight; MBL improves gas exchange and probably reduces the risk of opportunistic infection.

Adult↗
PubMed1995

Bleeding time in normal children.

PURPOSE: Because there is little information on bleeding times (BTs) in children we initiated the following study. MATERIALS AND METHODS: Normal children undergoing elective surgery and adult volunteers had their bleeding times measured with a disposable device (Simplate) with a vertical incision in the forearm. Results in children (four age groups) and adults, male and female, were compared. RESULTS: The mean time in children was 270 s with a 95th percentile of 420 s compared with a mean time in adults of 320 s and a 95th percentile of 480 s (p = 0.001). Although the values in the various age groups and sexes were different, only sex had a statistically different value in adults. CONCLUSIONS: The following reference values should be used for children: 0-4 years, 4 +/- 1 min; boys > 4 years, 5 +/- 1 min; girls > 4 years, 5.5 +/- 1 min. We conclude that results obtained in children are significantly shorter than those obtained in normal adult subjects.

Adolescent↗
PubMed1995

Plasma levels of inorganic sulfates in patients with Parkinson's disease.

Some investigators reported pharmacogenetic differences in the metabolism of sulfur-containing drugs and lower plasma sulfate levels in patients with Parkinson's disease (PD) compared with controls. However, other group did not confirm these findings. We studied the plasma levels of sulfate by indirect atomic absorption spectrophotometry in 55 PD patients and 57 age and sex-matched controls. The plasma sulfate levels did not differ significantly between PD patients and control groups (mean +/- SEM 73 +/- 8 and 75 +/- 7 mg/l, respectively). They were not influenced by antiparkinsonian drugs and they did not correlate with age at onset, duration, Hoehn & Yahr staging or activities of daily living subscale of the Unified Parkinson's disease rating scale. There was a low but significant correlation of plasma sulfate levels with motor examination (r = -0.39, p < 0.05) and total score (r = -0.33, p < 0.05) of this scale in the PD group. These data suggest that plasma sulfate levels are apparently unrelated with the risk for PD.

Aged↗
PubMed1995

Serum and urinary manganese levels in patients with Parkinson's disease.

To elucidate the possible role of manganese in the risk of developing Parkinson's disease (PD), we compared serum levels of manganese, and 24-h manganese excretion by urine in 29 PD patients and in 27 matched controls. We also measured chromium and cobalt in the same samples. All these values did not differ significantly between the groups, they were not influenced by antiparkinsonian drugs, and they did not correlate with age, age at onset and duration of the PD, scores of the Unified PD Rating Scale or the Hoehn & Yahr staging in the PD group. These results might suggest that serum levels and urinary excretion of manganese are apparently unrelated to the risk of developing PD.

Activities of Daily Living↗
PubMed1995

Suppressed proliferative response and interleukin-2 production in hispanic HIV+ and AIDS T-cell subsets.

We find that interleukin-2 (IL-2) production is severely depressed (80-90%) in AIDS T-cells (CD4+ or CD8+) stimulated with anti-CD3 or Con A together with phorbol ester (PMA) or anti-CD28 coactivation. Likewise, the proliferative response of CD4+ T-cells was suppressed, from a mean of 24.6% (HIV+) to 59.1% (AIDS) for PMA with activators OKT3 (anti-CD3), Con A, enterotoxin B or pokeweed mitogen, and 20.2% (HIV+) to 77.8% (AIDS) with anti-CD28 co-activation. Similar degrees of suppression were found with the CD8+ T-cells except for a much greater suppression at the HIV+ stage with anti-CD28 (57.7%), approximately 2.5 times higher than for PMA coactivation. However, when proliferation was induced by the two coactivators combined (PMA plus anti-CD28), much less suppression was observed: 8.5% (HIV+) to 19.0% (AIDS) for CD4+ cells and 8.2% to 26.5%, respectively, for CD8+ cells. The data suggest that during HIV infection the CD28 pathway becomes most defective, but can be bypassed to some extent by the less-impaired PMA pathway. The IL-2 (+PMA) signal in HIV+ and AIDS cells was also significantly less suppressed suggesting that the disregulation in HIV infection is more prominent prior to the IL-2 stage of the mitogenic pathway. It is remarkable that the CD4+ and CD8+ T-cells at both the HIV+ and AIDS stages generally show the same degree of suppression with all the various activators and coactivators used.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1995

N-acetylcysteine (NAC) enhances interleukin-2 but suppresses interleukin-4 secretion from normal and HIV+ CD4+ T-cells.

We find that purified CD4+ T cells from 30 HIV+ individuals have a suppressed Interleukin-4 (IL-4) production compared to normal controls regardless of activator (anti-CD3 or Con A) or co-activator [phorbol ester (PMA or anti-CD28)], generally by 2-4 fold. In every case, the cells producing IL-4 respond more strongly to anti-CD28 co-activation than to PMA, ie, 1150 pg/ml compared to 2070 pg/ml for controls and 398 pg/ml compared to 1250 pg/ml for HIV+ cells, respectively. In contrast, anti-CD3 with PMA gives a more vigorous IL-2 response than with anti-CD28, ie, 37.3 ng/ml compared to 12.3 ng/ml for controls and 28.5 ng/ml versus 15.1 ng/ml for HIV+ cells, respectively. These data are not compatible with the TH1/TH2 switch hypothesis since IL-4 production is decreased, not increased for CD4+ HIV+ T-cells and while IL-2 production is decreased with PMA, it is not decreased significantly with anti-CD28. Interestingly, 5 mM N-acetylcysteine (NAC) acts as an immunoenhancer; mitogenesis was enhanced 2 fold or more in general for control and HIV+ CD4+ T-cells and IL-2 production was enhanced 2-3 fold for anti-CD3 (with PMA or anti-CD28) for both controls and HIV+ CD4+ cells. However, NAC suppressed IL-4 production induced by anti-CD3 and anti-CD28 in both control and HIV+ CD4+ T cells. In the other cases, it produced in general no significant change.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcysteine↗
PubMed1994

Plasma levels of nitrates in patients with Parkinson's disease.

It has been suggested that nitric oxide (NO) could be implicated in the neuronal degeneration of substantia nigra compacta in patients with Parkinson's disease (PD). To ascertain the possible role of NO as risk factor for PD, we studied the plasma levels of nitrate (oxidation product that provides an indirect estimation of NO), in 68 PD patients and 68 matched-controls. The plasma levels of nitrate did not differ significantly between PD patient and control groups (44.5 +/- 2.46 and 44.8 +/- 2.67 mumol/l, respectively). They were not influenced by antiparkinsonian drug and they did not correlate with age at onset, duration, scores of the Unified Parkinson's Disease Rating scales and Hoehn and Yahr staging in the PD group. These data suggest that plasma levels of nitrate are apparently unrelated to the risk for PD.

Aged↗
PubMed1994

Overexpression of ferredoxin I in Azotobacter vinelandii.

Azotobacter vinelandii has recently been used for a variety of genetic experiments which take advantage of its facile transformation system and its high-frequency homologous recombination. One gene that has been cloned and sequenced is the fdxA gene that encodes a small Fe-S protein called A. vinelandii ferredoxin I (AvFdI). Because this protein has been extensively characterized by X-ray crystallography and spectroscopic methods, we are using it as a model to address some general questions in Fe-S biochemistry. AvFdI is not a very abundant protein in wild-type cells, so to facilitate our biochemical studies we have developed the overexpression system described herein. The results show that AvFdI can be easily overproduced ca. 50-fold in its native background, by introducing multiple copies of the fdxA gene into A. vinelandii, on the broad-host-range multicopy plasmid, pKT230. The protein can be expressed from its own constitutive promoter or from the controlled nifH promoter. The overproduced protein has no deleterious effects on the organism and is identical to the protein produced by wild-type cells. This A. vinelandii-based system should be generally useful for the overproduction of other A vinelandii proteins or for the expression of genes from thermophilic or other organisms with similarly high G-C contents, or for the expression of O2-sensitive metalloproteins that are unstable in other systems.

Azotobacter vinelandii↗
PubMed1994

Peripheral iron metabolism in patients with Parkinson's disease.

To elucidate the possible role of peripheral metabolism of iron in the risk for developing Parkinson's disease (PD), we compared serum levels of iron, transferrin and ferritin, and 24-h iron excretion in urine after a single intramuscular dose of 1 mg/kg desferrioxamine, in 68 PD patients and their spouses as the control group. All these values did not differ significantly between the groups, they were not influenced by antiparkinsonian therapy, and they did not correlate with age, age at onset and duration of the disease, scores of the Unified PD Rating Scale or the Hoehn and Yahr staging in the PD group, with the exception of the 24-h urinary iron excretion with the duration of the disease (r = 0.32, p < 0.05). These results suggest that peripheral metabolism of iron is apparently unrelated to the risk of developing PD.

Aged↗