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Biomedical subjects

E Vazquez

Publications and source records attributed to E Vazquez.

At least 19 recordsLinked to original sources
PubMed2002

Interaction of cimetidine with P450 in a mouse model of hepatocarcinogenesis initiation.

Many drugs and xenobiotics are lipophilic and they should be transformed into more polar water soluble compounds to be excreted. Cimetidine inhibits cytochrome P450. The aim of this study was to investigate the preventive and/or reversal action of cimetidine on cytochrome P450 induction and other metabolic alterations provoked by the carcinogen p-dimethylaminoazobenzene. A group of male CF1 mice received a standard laboratory diet and another group was placed on dietary p-dimethylaminoazobenzene (0.5% w w(-1). After 40 days of treatment, animals of both groups received p-dimethylaminoazobenzene and two weekly doses of cimetidine (120 mg kg(-1), i.p.) during a following period of 35 days. Cimetidine prevented and reversed delta-aminolevulinate synthetase induction and cytochrome P450 enhancement provoked by p-dimethylaminoazobenzene. However, cimetidine did not restore haem oxygenase activity decreased by p-dimethylaminoazobenzene. Enhancement in glutathione S-transferase activity provoked by p-dimethylaminoazobenzene, persisted in those animals then treated with cimetidine. This drug did not modify either increased lipid peroxidation or diminution of the natural antioxidant defence system (inferred by catalase activity) induced by p-dimethylaminoazobenzene. In conclusion, although cimetidine treatment partially prevented and reversed cytochrome P450 induction, and alteration on haem metabolism provoked by p-dimethylaminoazobenzene AB, it did not reverse liver damage or lipid peroxidation. These results further support our hypothesis on the necessary existence of a multiple biochemical pathway disturbance for the onset of hepatocarcinogenesis initiation.

5-Aminolevulinate Synthetase↗
PubMed2001

Painful ophthalmoplegia with reversible carotid stenosis in a child.

Painful ophthalmoplegia in childhood has different causes. One is Tolosa-Hunt syndrome, in which a first episode may be difficult to diagnose because of its clinical similarity to ophthalmoplegic migraine. A 10-year-old male with painful ophthalmoplegia and a cavernous sinus inflammation associated with an intracavernous carotid stenosis demonstrated by magnetic resonance imaging and angiography is reported. These findings resolved in follow-up imaging. This report suggests that in the presence of painful ophthalmoplegia, magnetic resonance imaging detection of cavernous sinus inflammation can facilitate the diagnosis of Tolosa-Hunt syndrome when other causes are excluded.

Blepharoptosis↗
PubMed2001

On the promoting action of tamoxifen in a model of hepatocarcinogenesis induced by p-dimethylaminoazobenzene in CF1 mice.

BACKGROUND AND AIMS: Tamoxifen (TMX) has proven to be an effective palliative treatment for advanced breast cancer with low reported incidence of side effects. TMX has been demonstrated to be an initiator and/or a promoter in the rat model of hepatocarcinogenesis. To document the long-term effect of TMX in mice treated with p-dimethylaminoazobenzene (DAB), we have investigated the time response action of these drugs on different biochemical parameters. METHODS: A group of animals was placed on dietary DAB (0.5%, w/w) during a period of 28 weeks. Control animals received a standard laboratory diet. Two other groups of non-treated and DAB-treated animals received TMX citrate (0.025%, w/w) in the diet since day 20. RESULTS: The activities of the enzymes involved in heme synthesis and degradation as evaluated in the DAB group was not further affected by TMX. DAB and/or TMX treatment significantly increased the content of total cytochrome P450 and also the activity of glutathione S-transferase indicating liver damage. In all treated groups oxidative stress and an adaptive response of the natural defense system (catalase and superoxide dismutase) were demonstrated. Histological and morphological studies revealed liver cell hyperplasia in DAB treated group; however, only in the DAB+TMX group solid, trabecular and acinar hepatocellular carcinoma was confirmed at the end of the experimental trial. CONCLUSION: We have demonstrated that TMX produced changes in hepatic enzyme activities which may be relevant for the metabolism and disposition of this and/or other drugs. Because liver tumors could be initiated and promoted by several agents which need to be activated, the possible hazard of TMX should be considered. This study reports that long-term treatment with TMX enhances hepatocarcinogenesis induced by DAB. The widespread use of TMX as an anticancer agent adds to the significance of this study.

5-Aminolevulinate Synthetase↗
PubMed2000

Preventive aspirin treatment of streptozotocin induced diabetes: blockage of oxidative status and revertion of heme enzymes inhibition.

Some late complications of diabetes are associated with alterations in the structure and function of proteins due to glycation and free radicals generation. Aspirin inhibits protein glycation by acetylation of free amino groups. In the diabetic status, it was demonstrated that several enzymes of heme pathway were diminished. The aim of this work has been to investigate the in vivo effect of short and long term treatment with acetylsalicylic acid in streptozotocin induced diabetic mice. In both treatments, the acetylsalicylic acid prevented delta-aminolevulinic dehydratase and porphobilinogen deaminase inactivation in diabetic mice and blocked the accumulation of lipoperoxidative aldehydes. Catalase activity was significantly augmented in diabetic mice and the long term treatment with aspirin partially reverted it. We propose that oxidative stress might play an important role in streptozotocin induced diabetes. Our results suggest that aspirin can prevent some of the late complications of diabetes, lowering glucose concentration and probably inhibiting glycation by acetylation of protein amino groups.

Animals↗
PubMed1999

Combined Assessment of Genetic Variability in Populations of Brown Trout (Salmo trutta L.) Based on Allozymes, Microsatellites, and RAPD Markers.

: Genetic variability within and among four Spanish natural populations of Salmo trutta L. was evaluated on the basis of 25 enzyme loci, 3 microsatellite loci, and 9 randomly amplified polymorphic DNAs (RAPDs). A total of 21 allelic markers were found, 12 of which were reported by microsatellites, whereas enzyme and RAPD accounted only for 6 and 3, respectively. Genetic variation within samples was significantly higher for microsatellites and RAPD than for enzyme loci. Although all methods reported a high degree of allelic heterogeneity among samples, also revealing a high degree of gene diversity, genetic relationships depicted by UPGMA dendrograms closely agreed for all kinds of data. Microsatellite loci appeared to be the most feasible technique when searching for specific alleles for a population or an area, owing to the higher number of allelic variants found.

Journal Article↗
PubMed1999

A prospective randomized trial comparing the efficacy of tacrolimus versus cyclosporine in black recipients of primary cadaveric renal transplants.

BACKGROUND: We performed a prospective randomized trial to compare the efficacy and safety of tacrolimus (FK506) versus cyclosporine (CSA) in black primary cadaveric renal transplant (CRT) recipients. METHODS: Between December 1994 and February 1997, 35 black primary CRT recipients were enrolled in this trial. All patients received 7 days of induction therapy with OKT3. Fourteen patients received FK506 and prednisone only. Twenty-one patients received CSA, azathioprine, and prednisone. The two groups were comparable in terms of age, gender, plasma renin activity, human leukocyte antigen mismatches, and cause of renal failure. RESULTS: Patient and graft survival were 12 of 14 (86%) for the FK506 group and 20 of 21 (95%) for the CSA group (P = 0.71). Three patients died owing to cardiac events with functioning grafts. Acute rejection was 2 of 14 (14%) for the FK506 and 8 of 21 (38%) for the CSA group (P = 0.25). Two other patients on CSA were converted to FK506 as rescue for OKT3-resistant rejection. Mean serum cholesterol at 1 year was 198 +/- 45 mg/dL for the FK506 group and 244 +/- 49 mg/dL for the CSA group (P = 0.03). Mean serum creatinine at 1 year was 1.39 +/- 0.38 mg/dL for the FK506 group and 1.94 +/- 0.64 mg/dL for the CSA group (P = 0.02). CONCLUSION: Patient and graft survival were similar in both groups at 1 year posttransplant. Although statistically not significant, the incidence of acute rejection was lower in the FK506 group. Furthermore, FK506-treated patients had significantly lower serum creatinine and cholesterol levels at 1 year posttransplant.

Adult↗
PubMed1999

Drug metabolizing enzyme system and heme pathway in hepatocarcinogenesis.

Chemically induced and spontaneous liver tumors share some metabolic alterations. The decline in hemoprotein levels during hepatocarcinogenesis may result from a diminution of the intracellular heme pool. To elucidate if the onset of the pre-initiation stage alters the natural regulation mechanism of heme pathway, animals were fed with p-dimethylaminoazobenzene (DAB) and treated or not with 2-allylisopropylacetamide (AIA). The induction of 6-Aminolevulinic acid synthase (ALA-S) activity and the diminution in microsomal heme oxygenase (MHO) did not change when DAB fed animals were treated with AIA. Cytochrome P-450 (P-450) levels and glutathione S-transferase activity were increased in all the groups tested. Tryptophan pyrrolase, sulphatase and beta-glucuronidase activities were altered in DAB fed animals but AIA treatment did not produce any effect. Changes in drug metabolizing enzymes in livers of DAB fed animals could be the result of a primary deregulation of heme metabolism. These results give additional support to our hypothesis about a mechanism for the onset of hepatocarcinogenesis.

5-Aminolevulinate Synthetase↗
PubMed1998

Brainstem involvement in a child with ophthalmoplegia, ataxia, areflexia syndrome.

The anatomic location and pathogenesis of the ophthalmoplegia, ataxia, areflexia syndrome, which includes both the Miller-Fisher syndrome and Bickerstaff's brainstem encephalitis, continues to be a matter for debate. A patient with this syndrome is reported, and the brainstem location of the lesion and elevated titers of anti-GM1 antibodies in serum are demonstrated.

Autoantibodies↗
PubMed1998

beta-Carotene partially prevents the damage induced by 1,4-dimethylaminoazobenzene in mice.

Hepatocarcinogenesis (HC) induced by various carcinogens such as 1,4-dimethylaminoazobenzene (DAB) is a multistep and complex process. The anticancer efficacy of beta-carotene (beta C) was evaluated by estimating some biochemical parameters during the initiation stage of HC. beta C dietary supplementation partially prevented the rise in delta-aminolevulinate synthetase activity. P 450 levels were dramatically enhanced in all groups studied. beta C administration did not overcome catalase inactivation due to DAB treatment; however, superoxide dismutase activity levels showed to be less decreased in the DAB + beta C animals in comparison to the DAB group. The great enhancement provoked by DAB of glutathione S-transferase, a proposed marker of HC, was partially reversed by beta C. In conclusion, heme pathway regulation, drug metabolism, and natural oxidative defence systems, strikingly modified in DAB fed animals, were partially controlled by provitamin A. The potential use of beta C in preventing carcinogenesis is suggested.

Animals↗
PubMed1998

MRI evidence that docosahexaenoic acid ethyl ester improves myelination in generalized peroxisomal disorders.

OBJECTIVE: We have found that docosahexaenoic acid (DHA; 22:6n-3), an important constituent of the CNS and retina, is dramatically decreased in patients with generalized peroxisomal disorders. Such a DHA deficiency could be pathogenic. Our aim was to test the possible beneficial effects of normalizing the DHA levels in these patients. The current report focuses on MRI changes during the treatment and reports follow-up evidence of myelin improvement in five peroxisomal disorder patients treated with DHA. METHODS: DHA ethyl ester (DHA-EE), about 90% pure, was used at daily oral doses of 100 to 600 mg. The treatment was monitored both clinically and biochemically, with periodic neurophysiologic and MRI examinations and repeated controls of liver tests and blood fatty acids by capillary column gas chromatography. RESULTS: DHA-EE normalized the blood levels of DHA in a few weeks. The levels of very-long-chain fatty acids decreased in plasma and those of plasmalogens increased in erythrocytes. Visual and liver function improved. On MRI, a virtual normalization of the brain myelin images was found in the three youngest patients. A clear improvement was noticed in the other two. CONCLUSIONS: The beneficial effects obtained indicate that DHA deficiency plays an important role in the pathogenesis of peroxisomal disease, probably in relation to myelinogenesis. Early initiation of DHA therapy is thus strongly recommended in patients with generalized peroxisomal disorders.

Brain Diseases↗
PubMed1998

Hepatic enzymatic metabolism alterations and oxidative stress during the onset of carcinogenesis: protective role of alpha-tocopherol.

Oxidants play a role in several stages of carcinogenesis. A high antioxidant capacity is expected to protect 'initiated' cells from excessive oxidant toxicity. The aim of this study was to determine the chemopreventive effect of a-tocopherol (alpha-T) on the hepatocarcinogenesis induced with p-dimethylaminoazobenzene (DAB) in mice. The dietary administration of alpha-T completely reversed the induction of delta-aminolevulinate synthetase and glutathione-S-transferase (the tumoral marker enzyme). alpha-T greatly enhanced P 450 levels, which were even higher in animals exposed to DAB. Indirect evidence for the involvement of oxygen radicals in the DAB model of hepatocarcinogenesis was provided by increased levels of thiobarbituric acid reactive species, which were detected in animals with severe liver damage and were assessed by histological analysis. alpha-T reduced the degree of hepatic injury, although this vitamin produced only slight changes in the oxidative parameters evaluated. The use of alpha-T as a potential chemopreventive agent, particularly during the initiation stage of carcinogenesis provoked by DAB, is worthy of further study.

5-Aminolevulinate Synthetase↗
PubMed1997

Altered heme pathway regulation and drug metabolizing enzyme system in a mouse model of hepatocarcinogenesis: effect of veronal.

1. Male CF 1 mice were fed p-dimethylaminoazobenzene (DAB) for 35 days and received 5,5-diethylbarbituric acid, before or after DAB treatment, with the purpose of investigating whether the onset of the preinitiation stage of carcinogenesis alters the natural regulatory mechanism of the heme pathway. 2. Changes detected in drug metabolizing enzymes are likely to be the consequence of a primary deregulation mechanism of heme metabolism, shown by an increase in delta-aminolevulinic acid synthetase activity and a decrease in microsomal heme oxygenase, which would finally lead to a great enhancement of cytochrome P450 levels. 3. The alterations found here would give rise to a pattern distinctive to that usually observed in the so-called resistant hepatocyte.

5-Aminolevulinate Synthetase↗
PubMed1997

Survival of inner ear sensory neurons in trk mutant mice.

Analysis of trkB-/-; trkC-/- double mutant mice revealed that peripheral and central inner ear sensory neurons are affected in these mice. However, a substantial amount of cochlear and vestibular neurons survive, possibly due to maintenance or upregulation of TrkA expression. To clarify the function of the TrkA receptor during development of the cochlear and vestibular ganglion we analysed trkA-/- mice and the expression of this receptor in inner ear sensory neurons of trkB-/-; trkC-/- animals. TrkA homozygous mutant mice showed normal numbers of neurons and no TrkA expression was detected in neurons of trkB-/-; trkC-/- double mutant mice. We conclude that TrkA is not essential for inner ear development and that in the absence of any of the known catalytic Trk receptors peripheral inner ear sensory neurons are prone to undergo cell death or must use a different signaling mechanism to survive.

Animals↗
PubMed1997

Neutrophil phagocytosis in AIDS patients with azole resistant candidiasis.

OBJECTIVE AND SUBJECTS: This study aimed to evaluate phagocytosis of C. albicans by neutrophils in 10 AIDS patients and 50 control subjects. Five of the AIDS patients were colonised with azole-resistant C. albicans isolates and five with azole-sensitive isolates. RESULTS AND CONCLUSIONS: Percentage phagocytosis was within normal limits for seven of the 10 AIDS patients and was reduced in the remaining three patients. Phagocytosis was unaffected by the carriage of azole resistant C. albicans, and the patients' own strains were phagocytosed as readily as a standard strain of C. albicans. This study suggests that azole resistance is not related to impaired phagocytosis in AIDS patients.

AIDS-Related Opportunistic Infections↗
PubMed1997

Mitochondrial and cytosolic rhodanese from liver of DAB-treated mice. III. Inhibition kinetic studies.

Rhodanese (thiosulphate:cyanide sulphurtransferase) shows distinctive mitochondrial and cytoplasmic activities in several models of tumorigenesis. To investigate the basis for these differences, the enzyme was purified from mitochondrial and cytosolic liver fractions of mice treated with the carcinogen p-dimethyl-aminoazobenzene (DAB) and some inhibition kinetic studies were carried out. When both substrates were assayed at inhibitory levels, non-competitive inhibition was observed for the second substrate at variable concentrations, the reversible connection between both substrates was attained by the instability of the second enzyme form. It is suggested that the enzyme might be changing from an unstable ES form to a more stable sulphur substituted intermediate as a consequence of DAB treatment. Sulphite was a competitive inhibitor vs thiosulphate for rhodanese isolated from normal liver and a hyperbolic activator for the enzyme isolated from liver of DAB-treated animals.

Animals↗
PubMed1996

Distribution of p75 and trk-neurotrophin receptor proteins in adult human sympathetic ganglia.

We investigated the expression of immunoreactivity (IR) for low- (p75) and high-affinity (trk proteins) neurotrophin-receptor proteins in adult human paravertebral-sympathetic ganglion neurons. Mouse monoclonal antibodies against the pan-neurotrophin-receptor p75, and rabbit polyclonal antibodies against specific epitopes of the intracytoplasmic domain on trk neurotrophin-receptor proteins were used in fresh unfixed and formaldehyde-fixed paraffin-embedded sympathetic ganglia. All adult human paravertebral-sympathetic neurons displayed trkA neurotrophin-receptor-like protein IR, 10% express trkC neurotrophin-receptor-like protein IR, 37-44% show p75 IR, and no IR was obtained for trkB neurotrophin-receptor-like protein. The intensity of immunostaining was independent of the neuron size. Labelling of non-neuronal tissues, especially blood-vessel walls, was observed for p75, trkA and trkC neurotrophin-receptor proteins. These results indicate that overlapping exists in the expression of p75 and trk neurotrophin-receptor proteins in adult human paravertebral-sympathetic neurons, and suggest that neurotrophins might act on these neurons.

Adult↗