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Biomedical subjects

G Vázquez

Publications and source records attributed to G Vázquez.

At least 19 recordsLinked to original sources
PubMed2002

Preliminary studies on TCF bleaching of Pinus pinaster acetosolv pulps.

Oxygen pre-treatment of Pinus pinaster acetosolv pulps has been studied as a first step towards TCF bleaching. Using a 2(3) factorial design, the influence of temperature (80-120 degrees C), time (1-2 h) and NaOH concentration (1.5-3%) on pulp yield in the oxygen stage, chemical composition and physical properties of the pulps obtained was studied. Pulps pre-bleached with oxygen in the conditions selected as optimal (80 degrees C, 1 h with 2.25% NaOH) have been bleached with TCF sequences which included stages with hydrogen peroxide or hydrogen peroxide-oxygen under pressure. Even if high degrees of delignification were reached, with a reduction in Kappa number up to 95% and without important loss of viscosity, the carbohydrates degradation, especially hemicelluloses in the acetic acid delignification, reduces the strength potential of the pulps.

Acetic Acid↗
PubMed2002

Removal of cadmium and mercury ions from aqueous solution by sorption on treated Pinus pinaster bark: kinetics and isotherms.

Formaldehyde pretreated Pinus pinaster bark was used to sorb Cd2+ and Hg2+ from aqueous solutions. The sorption kinetics showed hyperbolic dependence of the proportion of cation adsorbed on time, and the sorption isotherms were satisfactorily fitted by Freundlich equations, with k and n values showing Hg2+ to be more efficiently sorbed than Cd2+. Except for low cation concentrations, for which sorption was practically total at all initial pH > or = 6, sorption increased in this range, in keeping with a mechanism based on ion exchange with the hydroxyl protons of ring B of the procyanidin units of the tannins in the bark.

Absorption↗
PubMed2001

Switching to nevirapine decreases insulin levels but does not improve subcutaneous adipocyte apoptosis in patients with highly active antiretroviral therapy-associated lipodystrophy.

Subcutaneous adipocyte apoptosis occurs in lipotrophic areas of patients with highly active antiretroviral therapy (HAART)-associated lipodystrophy. Fourteen patients with HAART-associated lipodystrophy had 2 subcutaneous biopsies for evidence of adipocyte apoptosis, the second after a randomized change to nevirapine (n=8) or after remaining on a regimen of indinavir-based HAART (n=6). Apoptosis was assessed by the terminal deoxynucleotidyl transferase dUTP-digoxigenin nick end-labeling method. Patients who were switched to nevirapine had a significant decrease in insulinemia and a significant increase in the glucose:insulin ratio. Overall, subcutaneous adipocyte apoptosis increased in 3 patients who were switched to nevirapine and in 3 who continued to receive indinavir but decreased in 2 patients switched to nevirapine and another 2 who continued to receive indinavir. Subcutaneous adipocyte apoptosis continues to occur in lipotrophic areas of patients with HAART-associated lipodystrophy despite switching from indinavir to nevirapine, suggesting that such a strategy will be useless for reversal of lipoatrophy.

Adipocytes↗
PubMed2001

Blood flow rate and energy charge in the isolated perfused canine liver.

Background. Liver viability depends on blood flow rate, which varies among isolated perfused livers used in different studies. We aimed to identify the minimal blood flow capable of keeping the energy charge compatible with liver viability. Materials and methods. Isolated canine livers were assigned to different groups (n = 4) with blood flow rates of 0.5 (Group I), 1.0 (Group II), and 1.5 ml/g/min (Group III). Blood gases, hematocrit, and glucose were measured over 180 min. Nucleotides, serum osmolarity, and electrolytes were also measured. Morphological changes were recorded at the end of each experiment. Results. Acid-base balance was better in livers from Group III. Electrolytes, osmolarity, hematocrit, and glucose showed no differences. Higher energy charges correlated with higher blood flow rates. On histopathology, there was evidence of more hydrostatic pressure-related changes in Group III, with no difference in necrosis or inflammatory-related alterations. Conclusions. (1) Energy charge correlates strongly with blood flow rate. (2) A rate of 1.5 ml/g/min allows for a better electrolyte, osmolarity, and acid-base balance. (3) Morphological analysis is not a sensitive predictor of organ viability as assessed by energetic potential. (4) The minimal blood flow rate required to attain an energy charge above 0.75 is 1.33 ml/g/min.

Acid-Base Equilibrium↗
PubMed2001

[Clinical profile of idiopathic paroxsysmal atrial fibrillation. (FAP registry)].

OBJECTIVE: To assess the relative frequency and clinical profile of paroxysmal lone atrial fibrillation in comparison with that of secondary atrial fibrillation. PATIENTS AND METHOD: A prospective multicenter study (FAP Register) was designed to include 300 patients with symptomatic paroxysmal atrial fibrillation admitted to the emergency ward of 11 secondary hospitals of Catalonia. RESULTS: Lone atrial fibrillation was found in 67 patients (22.3%) while systemic hypertension was present in 33.7% of the cases; mitral or aortic valvular disease in 12% and coronary heart disease in 9.7%. As compared with patients with evidence of cardiac or systemic etiology, patients with isolated paroxysmal atrial fibrillation were younger (mean age of 55 vs 65 years of age; p = 0.0001), dyspnea was less frequent (p = 0.007); had a tendency to appear at night; left atrial size was smaller (p < 0.001) and response to treatment of sinusal rhythm was not different. CONCLUSIONS: Relative frequency of paroxysmal lone atrial fibrillation was only second to hypertension, which appears to be the most important pathogenic factor in our population. The clinical profile shows similarities in secondary fibrillation

Adult↗
PubMed2001

Group B Streptococcal sacroiliitis: case report and review.

Streptococcus agalactiae, or group B Streptococcus (GBS), is the major cause of neonatal meningitis and sepsis but is an uncommon infection in adults. GBS arthritis is rare, and axial involvement with sacroiliitis is even more uncommon. Microbiological diagnosis frequently relies upon positive blood cultures as synovial fluid cultures are usually negative. Severe joint damage may result due to delay in the initiation of antibiotic treatment.

Adult↗
PubMed2001

Characterization of GFAP expression and cell proliferation in the rat median eminence following hypophysectomy.

To analyze whether the reorganization of the rat median eminence after hypophysectomy might be related to changes in glial fibrillary acidic protein (GFAP)- and cellular proliferation, the distribution of cells immunoreactive for GFAP and the proliferation rate of such cells were analyzed at 20, 40 and 60 days posthypophysectomy. For this study, four rostro-caudal regions of the median eminence were differentiated: the retrochiasmatic, preinfundibular, infundibular and postinfundibular regions. In each of these regions, three layers were studied: the ependymal, the internal and the external. At 20 and 40 days after hypophysectomy, significant increases in cellular proliferation affecting all three layers studied in the preinfundibular and infundibular regions were found. At the same time points, increases in GFAP expression were also observed. However, after 60 days, GFAP and proliferative cellular nuclear antigen (PCNA) expression decreased. Although variations of PCNA and GFAP levels were evident, no colocalisation of PCNA and GFAP was found in the cells of the median eminence in untreated or hypophysectomized rats when sections were analyzed by double immunohistochemical staining. Our results suggest that reorganization of median eminence involves alterations (or modulation) of GFAP-immunoreactive cells together with a proliferation of cells that are not GFAP-immunoreactive. This study also demonstrates that this reorganization is completed within the first two months after hypophysectomy.

Animals↗
PubMed2000

[Aplasia after azathioprine administration: role of the thiopurine methyltransferase genetic polymorphism].

BACKGROUND: Azathioprine is an immunosuppressor drug widely used in the treatment of autoimmune diseases. Adverse effects during treatment are related to the activity of thiopurine methyltransferase (TPMT), an enzyme which plays a role in azathioprine metabolism. The presence of the allelic variants of the TPMT gene allows us to classify patients into three different groups: high, moderate and low risk of myelosuppression after receiving standard doses of azathioprine. PATIENTS AND METHODS: Study of the allelic variants of the TPMT gene in the positions 460 and 719 with PCR methods in a patient with Crohn's disease, who developed aplasia after receiving azathioprine. The study was extended to his relatives. RESULTS: The patient under study carried the most frequent variant allele of the TPMT gene associated with low enzymatic activity. The mother and one sister of the patient were also carriers of this allelic variant. CONCLUSIONS: Genotyping the allelic variants of the TPMT gene is a useful method to identify patients at moderate or high risk of myelosuppression after administration of azathioprine.

Adult↗
PubMed2000

Infection caused by Nocardia farcinica: case report and review.

Nocardia farcinica is a rare Nocardia species causing localised and disseminated infections. A case of Nocardia farcinica infection is presented, and 52 cases previously reported in the literature are reviewed. The hosts usually had predisposing conditions (85%), and acquired the infection through the respiratory tract or skin; the infection then often spread to the brain, kidney, joints, bones and eyes. Pulmonary or pleural infections (43%), brain abscesses (30%) and wound infections (15%) which failed to respond to conventional antimicrobial therapy were the more frequent forms of infection. Nocardia farcinica was frequently isolated from pus (100% of samples), bronchial secretions (41%) and biopsy specimens (63%), but isolation from blood and urine, as in the case presented here, is rare. Antibiotic therapy was adequate in 61% of the patients in whom it was specified, the agents most frequently given being trimethoprim-sulfamethoxazole (54%), amikacin combined with imipenem (7%) and amoxicillin-clavulanate (7%). The high mortality (31%) can be attributed to the severe underlying diseases present, difficulties encountered in identifying the pathogen, inappropriate therapy and late initiation of therapy. Although an infrequent pathogen, Nocardia farcinica should be kept in mind as a cause of infection especially in immunosuppressed patients with indolent infections not responding to third-generation cephalosporins.

Aged↗
PubMed2000

Simultaneous presence of C-ANCA and P-ANCA in a patient with concurrent Churg-Strauss syndrome and giant cell temporal arteritis.

We herein describe the case of a 77-year-old woman, who presented clinical and histopathological evidence of giant cell arteritis (GCA) involving the temporal artery, together with a Churg-Strauss syndrome (CSS). Our patient presented positive anti-neutrophil cytoplasmic antibodies (ANCA), with cytoplasmic staining pattern (C-ANCA) that was specific against proteinase 3 (PR3), and also a perinuclear pattern (P-ANCA) with specificity against myeloperoxidase (MPO). To our knowledge, the simultaneous presence in the same patient of both types of antibodies has not been previously reported.

Aged↗
PubMed1999

Subcutaneous adipocyte apoptosis in HIV-1 protease inhibitor-associated lipodystrophy.

BACKGROUND: Inhibitors of HIV-1 protease produce a rapid decrease in plasma HIV-1 RNA, with concomitant immune reconstitution. However, severe metabolic side effects together with a previously unseen form of lipodystrophy have been associated with long-term use of protease-inhibitor therapy. The pathogenic mechanisms underlying HIV-1 protease inhibitor-associated lipodystrophy are still largely unknown. METHODS: Fourteen HIV-infected patients with HIV-1 protease inhibitor-associated lipodystrophy had a biopsy of subcutaneous fat performed in the antero-lateral aspect of the right leg. The samples were submitted for standard pathologic study together with a careful search for adipocyte apoptosis. Apoptosis was assessed by the terminal deoxynucleotidyl transferase dUTP-digoxigenin nick end labelling (TUNEL) method, using the ApopTag kit (Oncor, Gaithersburg, Maryland, USA). The procedure was performed between three and five times for each sample. Appropriate positive and negative controls were used. Controls which were subcutaneous fat biopsies from patients with untreated melanoma were also examined for the presence of apoptosis. RESULTS: Fourteen HIV-infected patients with a mean exposure to HIV-1 protease inhibitors of 12.6 +/- 3.7 months (range: 6-21 months), developed the characteristic features of HIV-1 protease inhibitor-associated lipodystrophy. All but one patient had an abnormal waist:hip ratio, and they all exhibited an abnormal serum lipid profile. Pathologically, subcutaneous fat atrophy was a constant feature, along with focal lipogranuloma formation and vascular proliferation. One of the eleven assessable biopsy samples was negative for the presence of apoptosis, six showed focally positive apoptotic cells, and the remaining four biopsies demonstrated moderate positivity. Apoptotic changes were also detected in endothelial cells. Apoptotic changes were more pronounced in patients with higher increases in CD4 and CD8 counts, and in those with a greater decay in plasma viral load. CONCLUSIONS: Subcutaneous adipocyte apoptosis occurs in lipoatrophic areas of patients with HIV-1 protease inhibitor-associated lipodystrophy.

Adipocytes↗
PubMed1999

Pelvic insufficiency fractures in patients with pelvic irradiation.

BACKGROUND: Insufficiency fractures (IF) occur as a result of normal physiological stress on bones with deficient elastic resistance. Pelvic insufficiency fractures are a complication of osteoporosis due to postmenopausal status, high dose of corticosteroids, or local irradiation. They are important because differential diagnosis includes pelvic bone metastases. Diagnosis is based on both clinical manifestations and radiographic and scintigraphic findings. METHODS AND MATERIALS: We examined eight patients with pelvic cancer who had previously undergone external beam radiation therapy as part of their treatment. In the follow-up, they developed insufficiency fractures, and no factor other than pelvic irradiation was present. Diagnosis was confirmed by radionuclide bone scan followed by conventional radiography and computed tomography (CT) scan. RESULTS: The average onset of symptoms was 13.7 months after radiation therapy was completed. The initial symptom in all cases was pain. In all of the patients, the bone scan showed abnormalities. One to four increased uptake foci were observed, in the sacroiliac joint in all cases, and in the pubis in three cases. The initial diagnosis was bone metastases in five patients. CT scan showed fractures in all of the patients, in sacrum and pubis, both endostic and cortical. Treatment, consisting of nonsteroidal anti-inflammatory drugs and rest, led to symptomatic relief in all cases. CONCLUSION: Knowledge of pelvic insufficiency fractures is essential in order to rule out metastasic disease, and thus avoid inaccurate treatment. Although radionuclide bone scan is useful in early detection of pelvic IF, definitive diagnosis is provided by CT scan.

Adenocarcinoma↗
PubMed1999

Immunohistochemical evidence of the presence of aromatase P450 in the rat hypophysis.

In order to analyze whether aromatase is present in the hypophysis of adult rats, we have performed an immunohistochemical study in young adult male and female rats. Our study has revealed that the hypophysis of adult rats contains aromatase, although marked differences are found between the sexes. The hypophyses of male rats have cells immunoreactive for the enzyme, 34.40% of these hypophyseal cells showing reaction. By contrast, cells from female rats show very little reaction, only 0.84% of them being reactive. No significant differences in the percentage of immunoreactive cells between one phase and another are observed during the estrous cycle. Our results point to the immunohistochemical expression of aromatase in the hypophysis of adult rats and at the same time suggest that its expression is sex-dependent. The enzyme may therefore be involved in the regulation of adenohypophyseal cytology by androgens.

Amino Acid Sequence↗