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Biomedical subjects

A I Alvarez

Publications and source records attributed to A I Alvarez.

At least 19 recordsLinked to original sources
PubMed2005

Protection of Panax ginseng in injured muscles after eccentric exercise.

Panax ginseng C.A. Meyer, the root of an Araliaceae plant has been shown to possess various biological effects. Ginseng treatment (100 mg kg(-1)) protected muscles from eccentric exercise injuries. It was effective in preserving mitochondrial membrane integrity and reduced nitrate concentration in vastus and rectus (46% and 26%, respectively). It also reduced carbonyl contents by approximately 27% in all the muscles studied.

Animals↗
PubMed2005

Comparative study of hyaluronic derivatives: rheological behaviour, mechanical and chemical degradation.

Depolymerisation by oxytetracycline (OTC) as well as the progressive cleavage of hyaluronic acid induced by ultrasound was investigated in nine commercially available hyaluronic polymers. Sample solutions differed in molecular weight, from 500 to 7000 kDa, and in their source. The hyaluronic acid concentration in each sample was analysed by HPLC. The concentration range was over 8.39-10.18 mg ml(-1) in samples with a nominal concentration of 1%, and 14.05 mg ml(-1) in one sample with a nominal concentration of 1.5%. It was found that stability was dependent on both molecular weight and the concentration of the samples. The rheological parameters n (power law index) and K (consistency coefficient) were good predictors regarding the degradation behaviour. Although many factors are involved in obtaining a therapeutic response, the results obtained in this work support the notion that both mechanical and chemical degradation are reduced in hyaluronate solutions with low molecular weight, the final concentration of the product being a critical factor.

Biocompatible Materials↗
PubMed2004

Ginseng administration protects skeletal muscle from oxidative stress induced by acute exercise in rats.

Enzymatic activity was analyzed in the soleus, gastrocnemius (red and white) and plantaris muscles of acutely exercised rats after long-term administration of Panax ginseng extract in order to evaluate the protective role of ginseng against skeletal muscle oxidation. Ginseng extract (3, 10, 100, or 500 mg/kg) was administered orally for three months to male Wistar rats weighing 200 +/- 50 g before exercise and to non-exercised rats (N = 8/group). The results showed a membrane stabilizing capacity of the extract since mitochondrial function measured on the basis of citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities was reduced, on average, by 20% (P < 0.05) after exercise but the activities remained unchanged in animals treated with a ginseng dose of 100 mg/kg. Glutathione status did not show significant changes after exercise or treatment. Lipid peroxidation, measured on the basis of malondialdehyde levels, was significantly higher in all muscles after exercise, and again was reduced by about 74% (P < 0.05) by the use of ginseng extract. The administration of ginseng extract was able to protect muscle from exercise-induced oxidative stress irrespective of fiber type.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed2003

Improved LC method to determine ivermectin in plasma.

A simple, rapid and sensitive high-performance liquid chromatographic (HPLC) method has been developed to quantify Ivermectin (IVM) in plasma using an isocratic system with fluorescence detection. The method included a fast liquid phase extraction using cold methanol. HPLC separation was carried out by reversed phase chromatography with a mobile phase composed of methanol:acetonitrile:water with 0.2% acetic acid (45:50:5 v/v/v), pumped at flow rate of 2 ml min(-1). Fluorescence detection was performed at 365 nm (excitation) and 475 nm (emission). The calibration curve for IVM was linear from 0.25 to 100 ng ml(-1). The validation method yielded good results regarding linearity, precision, accuracy, specificity and recoveries. The values of the limit of detection (LOD) and limit of quantification (LOQ) were 0.032 and 0.167 ng ml(-1), respectively.

Chromatography, High Pressure Liquid↗
PubMed2003

Effect of clotrimazole on microsomal metabolism and pharmacokinetics of albendazole.

Albendazole is a broad spectrum anthelmintic drug widely used in human and veterinary medicine. Intestinal and hepatic albendazole metabolism leads to albendazole sulfoxide (active metabolite) and albendazole sulfone (inactive metabolite) formation. Microsomal sulfonase activity can be abolished by in-vitro interaction with clotrimazole and pharmacokinetic studies confirm this interaction. After albendazole incubation, albendazole sulfone formation was completely inhibited by 50 microM clotrimazole in intestinal incubations and a 50% inhibition was observed in hepatic incubations. The lower inhibition constant (K(i)) value observed in the intestinal incubations (9.4 +/- 1.0 microM) compared with the hepatic counterparts (23.3 +/- 15.8 microM) pointed to a greater affinity of the enzymatic systems in the intestine. Regarding the formation of albendazole sulfoxide, an inhibition close to 50% was observed in liver and intestine at 10 microM clotrimazole. The pharmacokinetic parameters obtained following the oral co-administration of albendazole sulfoxide and clotrimazole corroborated the in-vitro inhibition of albendazole sulfone formation, since the ratio of the area under the plasma concentration-time curves for the sulfoxide/sulfone (AUC(ABZSO)/AUC(ABZSO2)) was significantly higher (38.1%). In addition, the AUC and C(max) for albendazole sulfone were significantly lower. The effect of clotrimazole was also studied after prolonged treatment. Hepatic microsomal metabolism of albendazole was induced after 10 days of clotrimazole administration, with significant increases in formation of albendazole sulfoxide (40%) and sulfone (27%). These results offer further insight into the metabolism of benzimidazole drugs and highlight the difficulty involved in human therapy with these anthelmintics, since after prolonged treatment the drug interactions are affected differentially.

Administration, Oral↗
PubMed2001

Effect of chronic ethanol ingestion and exercise training on skeletal muscle in rat.

The aim of this study was to investigate the interactive effects of exercise training and chronic ethanol consumption on metabolism, capillarity, and myofibrillar composition in rat limb muscles. Male Wistar rats were treated in separate groups as follows: non exercised-control; ethanol (15%) in animals' drinking water for 12 weeks; exercise training in treadmill and ethanol administration plus exercise for 12 weeks. Ethanol administration decreased capillarity and increased piruvate kinase and lactate dehydrogenase activities in white gastrocnemius; in plantaris muscle, ethanol increased citrate synthase activity and decreased cross-sectional area of type I, IIa, and IIb fibres. Exercise increased capillarity in all four limb muscles and decreased type I fibre area in plantaris. The decreased capillarity effect induced by ethanol in some muscles, was ameliorated when alcohol was combined with exercise. While alcoholic myopathy affects predominantly type IIb fibres, ethanol administration and aerobic exercise in some cases can affect type I and type IIa fibre areas. The exercise can decrease some harmful effects produced by ethanol in the muscle, including the decrease in the fibre area and capillary density.

Analysis of Variance↗
PubMed2001

Protective effects of Panax ginseng on muscle injury and inflammation after eccentric exercise.

Eccentric muscle contraction causes fibre injury associated with disruption of the myofibrillar cytoskeleton. The medicinal plant Panax ginseng C.A. Meyer, known for its therapeutic properties, was studied to explore its protective effects after eccentric contraction. A crude extract and a standardised extract (G115) of different saponin compositions were tested as to their efficacy in reducing lipid peroxidation, inflammation and release of myocellular proteins after the realisation of an eccentric contraction protocol on a rat treadmill. Plasma creatine kinase (CK) levels were significantly reduced by approximately 25% after ingestion of both extracts of ginseng. Both extracts reduced lipid peroxidation by approximately 15% as measured by malondialdehyde levels. beta-Glucuronidase concentrations and glucose-6-phosphate dehydrogenase (G6PDH) levels, which can be considered markers of inflammation, were also significantly reduced. The values of beta-glucuronidase were increased from 35.9+/-1.5 to 128.4+/-8.1 in vastus and to 131.1+/-12.1 U x g(-1) in rectus, the protection due to ginseng administration being approximately 40% in both muscles. Both extracts appeared to be equally effective in reducing injuries and inflammation caused by eccentric muscle contractions.

Animals↗
PubMed1999

Effects of administration of the standardized Panax ginseng extract G115 on hepatic antioxidant function after exhaustive exercise.

The effect of prolonged treatment with the standardized Panax ginseng extract G115 on the antioxidant capacity of the liver was investigated. For this purpose, rats that had received G115 orally at different doses for 3 months and untreated control rats were subjected to exhaustive exercise on a treadmill. A bell-shaped dose response on running time was obtained. The results showed that the administration of G115 significantly increases the hepatic glutathione peroxidase activity (GPX) and the reduced glutathione (GSH) levels in the liver, with a dose-dependent reduction of the thiobarbituric acid reactant substances (TBARS). After the exercise, there is reduced hepatic lipid peroxidation, as evidenced by the TBARS levels in both the controls and the treated animals. The GPX (glutathione peroxidase) and SOD (superoxide dismutase) activity are also significantly increased in the groups receiving G115, compared with the controls. The hepatic transaminase levels, ALT (Alanine-amino-transferase) and AST (Aspartate-amino-transferase), in the recuperation phase 48 h after the exercise, indicate a clear hepatoprotective effect related to the administration of the standardized Panax ginseng extract G115. At hepatic level, G115 increases the antioxidant capacity, with a marked reduction of the effects of the oxidative stress induced by the exhaustive exercise.

Animals↗
PubMed1999

Bioavailability of albendazole sulphoxide after netobimin administration in sheep: effects of fenbendazole coadministration.

After oral co-administration of two dosages of netobimin (7.5 and 20 mg kg-1 with fenbendazole (1.1 mg kg-1) to Merino sheep, the AUC0-infinity of albendazole sulphoxide at the lower dosage of netobimin, was significantly increased (75.5 per cent) from control value (34.43 +/- 7.91 versus 60.33 +/- 11.93 microg h ml-1). The pharmacokinetic parameters MRT and T1/2 were also increased: 18.96 +/- 2.54 vs 26.44 +/- 4.69 h and 10.31 +/- 1.72 vs 22.28 +/- 6.75 h respectively. No data corresponding to the higher dosage of netobimin (20 mg kg-1) were statistically different from control values. It is concluded that fenbendazole increases the bioavailability of albendazole sulphoxide in sheep at the 7.5 mg kg-1 dosage, and this may produce a potentiated anthelmintic action.

Administration, Oral↗
PubMed1999

Effects of a standardized Panax ginseng extract on the skeletal muscle of the rat: a comparative study in animals at rest and under exercise.

The effect of standardized Panax ginseng extract G115 on enzymatic activities, myotypological composition, capillaries and mitochondrial content was studied in the skeletal muscle of male rats Wistar. Simultaneously to the G115 administration the rats performed exercise. The animals were divided into 4 groups. The dose of the ginseng extract G115 was 50 mg/kg. The length of the experimental period was 12 weeks. After 24 hours of inactivity the muscles of the hindlimb were extracted. With regard to the enzymatic activities of the citrate synthase (CS) and lactate dehydrogenase (LDH), CS increases with exercise, while the LDH undergoes no major variations, either due to the exercise or the treatment. Treatment with G115 increases the capillary density and the mitochondrial content of the red gastrocnemius muscle. The results suggest that prolonged treatment with G115 increases the capillary density and the oxidative capacity of the muscles with greater aerobic potential in a manner similar to the performance of physical exercise. When exercise and treatment are combined, the effects that are obtained separately are not potentiated.

Animals↗
PubMed1999

Effects of ginseng extract on various haematological parameters during aerobic exercise in the rat.

The effects of the Ginseng extract on various biochemical and haematological parameters in male Wistar rats subjected to a treadmill exercise protocol were studied for 12 weeks. The results showed increases in the haematological parameters, these increases being greatest for the animals treated with the extract during the third month of the study. The exercise also led to increases in these parameters, while the combination of both exercise and extract produced smaller increases. This study shows a clear physiological response due to the ginseng extract administration that reproduces many of the effects obtained after long-term exercise. The combination of exercise and treatments seems to support the theory that there is no clear synergic effect when the advantages associated with the ingestion of ginseng are compared with the performance of exercise.

Animals↗
PubMed1999

Presystemic metabolism of albendazole: experimental evidence of an efflux process of albendazole sulfoxide to intestinal lumen.

Albendazole (ABZ) presystemic clearance was studied in rat by perfusion of a 25 microM ABZ solution in isolated intestinal loops. Significant secretion of the active metabolite, ABZSO, into the lumen was observed. The metabolite was also present in mesenteric blood. After 30 min of intestinal perfusion, 64% of the ABZ dose had disappeared from lumen. The total amount of ABZSO measured was 0.341 +/- 0.04 nmol/cm with 0.176 +/- 0.03 nmol/cm in mesenteric blood. The metabolite secretion to intestinal lumen was 0.165 +/- 0.05 nmol/cm. Intestinal sulfoxidation was induced by repeated administration of ABZ and ABZ coadministered with surfactants, especially polysorbate 80. The enantioselectivity of the in vitro intestinal sulfoxidation of ABZ showed that the relative contribution of P-450 and flavin-containing monooxygenase was quite similar, but after the induction by ABZ coadministered with polysorbate 80, the cytochrome P-450 system contribution was significantly increased. The appearance of ABZSO in mesenteric blood clearance was also increased under these conditions.

Albendazole↗
PubMed1998

Influence of surfactants on oral bioavailability of albendazole based on the formation of the sulphoxide metabolites in rats.

The influence of two surfactants, sodium taurocholate (STC) and polysorbate 80 (P80), on the bioavailability of albendazole (ABZ), orally administered to rats, has been studied. To assess the effect of the surfactants, they were administered at critical micellar and supramicellar concentrations, 5 and 10 mM for STC and 0.0022 and 0.22% for P80, along with a subclinical dose of 5 mg kg-1 of ABZ. Doses of 5 and 10.6 mg kg-1 ABZ were also administered as controls. The results show an increase in the sulphoxide AUC values: 55% in the STC 5 mM and 88% in the STC 10 mM and P80 0.0022% treatments when compared to the control ABZ 5 mg kg-1 dose. MRT values also show longer-lasting plasma albendazole sulphoxide concentration following these three treatments, particularly for the P80 0.0022% treatment. While there was no change in the apparent rate of formation of ABZSO, the amount of ABZSO formed was increased significantly by the addition of surfactants (STC 10 mM and P80 0.0022%).

Albendazole↗
PubMed1998

Molecular study of the rhodopsin gene in retinitis pigmentosa patients in the Basque Country.

Retinitis pigmentosa (RP) is a degenerative disorder affecting the outer segment of the retina and leading to night blindness and progressive visual field loss. The rhodopsin gene encodes a photolabile pigment located in the rod outer segments constituting around 80-90% of its protein content and is the initiation point for the visual cascade upon absorption of a single photon. Seventy-five unrelated, isolated RP families in the Basque Country, with at least one affected member, were diagnosed at our hospital after ophthalmic examination and electroretinogram analysis. The patients received genetic counselling according to their individual case based on their clinical diagnosis. The modes of inheritance found from pedigree studies were the following: 20% (15/75) were classified as autosomal dominant retinitis pigmentosa (ADRP), 17.33% (13/75) were autosomal recessive (ARRP), 2.66% (2/75) were unclassified (NC), and 60% (45/75) were sporadic cases (SCRP). From these families, 75 unrelated and affected index cases together with 22 affected relatives and 42 unaffected relatives were screened for mutations in the rhodopsin gene by GC clamped denaturing gradient gel electrophoresis. Our results showed that five ADRP, three ARRP, 15 SCRP, and one NC families had alterations in this gene. Only three of these alterations, that is 4% (3/75) (95% CL 0-8), appeared to be responsible for the disease. This represents a lower percentage than the 10% previously reported.

Electrophoresis, Polyacrylamide Gel↗
PubMed1995

Small intestinal sulphoxidation of albendazole.

1. The in vitro sulphoxidation of Albendazole (ABZ) by rat intestinal microsomes has been examined. The results revealed intestinal sulphoxidation of ABZ by intestinal microsomes in a NADPH-dependent enzymatic system. The kinetic constants for sulphoxidase activity were Vmax = 46 pmol/min/mg protein and Michaelis constant Km = 6.8 microM. 2. The possible effect of inducers (Arochlor 1254 and ABZ pretreatment) and inhibitors (erythromycin, methimazole, carbon monoxide and fenbendazole), was also studied. In rat pretreated with Arochlor 1254, Vmax was 52 pmol/min/mg protein, whereas oral administration of ABZ increased the intestinal sulphoxidation of the drug, Vmax being 103 pmol/min/mg protein. 3. Erythromycin did not change the enzymatic bioconversion of ABZ, but methimazole and carbon monoxide inhibited the enzyme activity by approximately 60 and 30% respectively. Fenbendazole (a structural analogue of ABZ) was a competitive inhibitor of the sulphoxidation process, characterized by a Ki or 69 microM. 4. These data demonstrate that the intestinal enzymes contributing to the initial sulphoxidation of ABZ may be similar to the hepatic enzymes involved in the biotransformation process by the P450 and FMO systems, a conclusion that needs to be further established.

Albendazole↗
PubMed1995

Physiological response to experimentally induced anemia in rats: a comparative study.

To induce anemia experimentally in rats to provide a hematocrit of 30 to 35% and provide data about the physiologic response to anemia during induction and after it is established, two methods were selected: the application of repetitive doses of phenylhydrazine and bleeding. Blood sample collection was carried out at various times, and hematologic profiles and osmotic resistance were evaluated. The morphologic features of cells and distinct organs also were examined. Results indicated similar decrease of hematocrit and hemoglobin concentration for the two experimental groups, although the reticulocyte response was higher in rats treated with phenylhydrazine, where the presence of young erythrocyte populations was linked to increases in osmotic resistance and glucose utilization. 2,3-Diphosphoglycerate was induced only during the recovery phase of the study and corresponded to a gradual response to hypoxia. Histologically, marked erythroid hyperplasia was found in the bone marrow, and extramedullary hematopoiesis was seen in the spleen and liver.

2,3-Diphosphoglycerate↗