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Biomedical subjects

C Villaverde

Publications and source records attributed to C Villaverde.

At least 19 recordsLinked to original sources
PubMed2006

Effects of dietary concentration and degree of polyunsaturation of dietary fat on endogenous synthesis and deposition of fatty acids in chickens.

Two experiments were performed to assess the effect of different amounts of dietary polyunsaturated fatty acids (PUFA) on fatty acid composition of chickens. The contribution of de novo fatty acid synthesis to fatty acid profile was also estimated. In trial 1, different fat sources were blended in different ratios allowing a gradient of dietary PUFA (from 15 to 61 g/kg), keeping added fat constant (9%). In trial 2, PUFA-rich oil was added at increasing inclusion rates (2, 4, 6 and 8%), achieving a dietary PUFA content ranging between 27 and 59 g/kg. Increasing dietary PUFA inclusion resulted in an increase in PUFA deposition, with higher efficiency when dietary fat also provided saturated (SFA) and monounsaturated (MUFA) fatty acids (trial 1). Increasing dietary PUFA in both trials resulted in a decrease in SFA and MUFA concentration in the whole body. The estimated deposition of fatty acids from de novo synthesis was reduced when dietary fat content increased from 0 to 10%, varying between 35.34 and 17.66% for SFA and between 52.70 and 7.01% for MUFA in the whole body. The greater variation range for the MUFA supports the existence of a mechanism maintaining the SFA: (MUFA + PUFA) ratio within a specific range in biological membranes.

Adipose Tissue↗
PubMed2005

Influence of the dietary polyunsaturation level on chicken meat quality: lipid oxidation.

The present study was carried out to evaluate the influence of increasing amounts of dietary polyunsaturated fatty acids (PUFA) and alpha-tocopheryl acetate (alpha-TA) supplementation on lipid oxidation of raw and cooked thigh meat stored under refrigeration. One hundred ninety-two female, 1-d-old, broiler chickens were randomly distributed into 16 experimental treatments resuIting from the combination of 4 levels of dietary PUFA (15, 34, 45, and 61 g/kg) and 4 levels of supplementation with alpha-TA (0, 100, 200, and 400 mg/kg). Thiobarbituric acid reactive substance (TBARS) values in cooked meat and cooked refrigerated meat were 12- and 24-fold higher, respectively, than in raw meat. Dietary polyunsaturation and alpha-TA supplementation affected lipid oxidation more markedly in cooked meat and cooked refrigerated meat than in raw meat and raw refrigerated meat. Lipid oxidation in cooked meat showed a significant linear increase as the concentration of PUFA in raw meat increased. The oxidative stability of meat was not affected by an increase in the dietary alpha-TA level from 200 to 400 mg/kg. Nonlinear relationship between TBARS values in cooked meat and alpha-tocopherol content of raw meat showed saturation in the antioxidant effect of alpha-Toc. The equation y = x (11.88 + 63.38e(-0.007z) was calculated to predict the minimum inclusion of alpha-tocopherol to diets (z) of chickens with certain dietary PUFA content (x) to assure a certain TBARS value (y).

Animals↗
PubMed2004

Fatty acid content in chicken thigh and breast as affected by dietary polyunsaturation level.

One hundred ninety-two female broiler chickens were randomly distributed into 16 experimental treatments as a result of the combination of 4 levels of dietary polyunsaturated fatty acids (PUFA) (15, 34, 45, and 61 g/kg) and 4 levels of supplementation with alphatocopheryl acetate (alpha-TA) (0, 100, 200, and 400 mg/kg), to determine the modification of the amount and type of fatty acids (FA) deposited in raw and cooked chicken tissues. At 44 d, quantified FA of thighs and breasts were not affected by dietary supplementation with alpha-TA. Total FA content of breast was less than 15% of the total FA content of thigh. However, increasing the PUFA content of the diet by 46 g, from 15 to 61 g/kg, decreased total FA of thigh 17%, but did not affect FA content in breast meat. Monounsaturated fatty acid (MUFA) and saturated fatty acid (SFA) content of thigh (y) decreased linearly as the inclusion of dietary PUFA (x) increased (MUFA: y = 89.34 - 0.92x, R2 = 0.70; SFA: y = 53.81 - 0.43x, R2 = 0.57), whereas the relationship between PUFA content of feed (x) and thighs (y) was exponential (y = 92.03 92.03e(-00155x), R2 = 0.75). A similar response was observed in breast, with less variation and more incorporation of PUFA than thigh. Cooking of thigh meat led to a reduction in total FA content that affected SFA, MUFA, and PUFA in a similar proportion.

Animals↗
PubMed2004

Relationship between dietary unsaturation and vitamin E in poultry.

Vitamin E requirements are linked to dietary polyunsaturated fatty acids (PUFA) content as a result of the protective effect of vitamin E from lipid peroxidation. On the other hand, it has been suggested that dietary PUFA interfere with vitamin E absorption. A 4 x 4 factorial study was planned to assess the effect of dietary vitamin E inclusion level (0, 100, 200 and 400 mg/kg) and degree of unsaturation (15, 34, 45 and 61 g PUFA/kg) on vitamin E apparent absorption and tissue deposition in poultry. A total of 192 female broiler chickens were used. A digestibility balance was carried out between 19 and 23 days of age to calculate apparent absorption of fat and vitamin E. The livers of 96 animals were obtained at 44 days of age for vitamin E determination. Increasing dietary levels of vitamin E reduced its apparent absorption. The more saturated diet reduced fat and vitamin E apparent absorption while PUFA levels from 34 to 61 g/kg did not modify this parameter but reduced the hepatic vitamin E concentration, suggesting a greater systemic use of this vitamin. These results suggest that PUFA do not limit vitamin E absorption, although they may increase its degradation in the gastrointestinal tract.

Animal Feed↗
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

Fibrinogen and fibrinolysis in blood and in the arterial wall: its role in advanced atherosclerotic disease.

High plasma fibrinogen appears to be an important risk factor for the development of atherosclerosis. The aim of our study was to measure fibrinogen and fibrin degradation products (D-dimer), interleukin-6 tissue plasminogen activator, plasminogen activator inhibitor-1 and urokinase-type plasminogen activator in the plasma and arterial walls of 45 patients who had arterial surgery between April 1993 and November 1995. The arterial specimens were also examined by immunohistochemists for these same factors. The serum fibrinogen and fibrin degradation products were high in all patients, and fibrinolysis was depressed. Few leukocytes were seen in the arterial walls, which had poor fibrinolytic activity. Plasminogen-activator inhibitor activity in the wall was also reduced in the affected arterial walls. The abdominal aorta appeared to have the highest levels of fibrinogen and this may be related to its ability to form aneurysms. Fibrinogen may play an important role in the progression of atherosclerotic disease.

Aorta, Abdominal↗
PubMed1997

Plasma concentrations of beta-endorphin and adrenocorticotropic hormone in women with and without childbirth preparation.

We studied plasma concentrations of beta-endorphin (beta-EP) and adrenocorticotropic hormone (ACTH) during dilation, expulsion and immediate puerperium in 47 primiparous women with an uneventful pregnancy and spontaneous vaginal delivery. Twenty-five women had received childbirth preparation with the Lamaze method, and 22 had received no preparation. Mean concentrations of beta-EP from the beginning of labor until puerperium were higher in women who had received preparation, but there was no significant difference between the two groups. When behavior during labor was evaluated regardless of which group the patient was assigned to, women whose behavior was unsatisfactory has significantly higher concentrations of ACTH at all times during childbirth. We discuss the role of childbirth preparation as a way to enhance beta-EP secretion. Levels of ACTH, on the other hand, appear to be more closely related with behavior during labor, regardless of whether the mother received preparation.

Adrenocorticotropic Hormone↗
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↗
PubMed1994

Plasma levels of beta-endorphin and ACTH during labor and immediate puerperium.

We measured concentrations of beta-endorphin (beta-EP) and adrenocorticotropic hormone (ACTH) in maternal peripheral plasma during dilation, the expulsive period and immediate puerperium, and in the umbilical vein. Plasma levels of both peptides increased markedly and were directly correlated during labor, and decreased 24 h after birth; they were no longer correlated during immediate puerperium. In the umbilical vein, beta-EP and ACTH were also directly correlated. Moreover, the concentration of each of the two peptides in maternal plasma during the expulsive period was correlated with the corresponding concentration in umbilical vein. We discuss the importance of placental corticotropin-releasing factor in the regulation of maternal and fetal stress.

Adrenocorticotropic Hormone↗
PubMed1994

Influence of ethanol on gastric absorption and metabolism of albendazole and mebendazole.

The effect of ethanol administration on gastric absorption in rats of two benzimidazole derivatives has been studied. The ethanol administration was carried out as both acute (5%, 10% and 15% w/v of ethanol in the perfusion solution), and chronic (15, 30 and 120 days) forms. Two benzimidazole derivatives were used: albendazole (ABZ) and mebendazole (MBZ). The administration of ethanol did not affect the kinetic mechanism of the absorption process (simple diffusion) but the absorption rate decreased in all treatments except in 5% acute ethanol, presumably due to the improved solubility of the drugs. Plasma, bile and liver levels after gastric perfusion suggest a possible interference of ethanol metabolism with drug hepatic metabolism.

Albendazole↗
PubMed1992

Albendazole and mebendazole uptake by isolated enterocytes.

Uptake of albendazole (ABZ) and mebendazole (MBZ) by isolated rat enterocytes was carried out. These drugs, widely used oral anthelmintics, exhibit a scarce water solubility which reduce its absorption by the oral tract. The present study was designed to assess the captation for ABZ and MBZ in different enterocyte populations isolated from upper to crypt villus. The concentration range used for the absorption experiments was within 10-500 microM for both drugs, using DMSO as solvent. The results obtained show the existence of a passive mechanism for the uptake of ABZ and MBZ at concentrations between 10 and 100 microM, with a maximum intake value around 20 microM/mg protein. No differences were found with respect to the cell populations analyzed. The drug uptake levels seem to be higher for MBZ than for ABZ prior to reaching the maximum plateau.

Albendazole↗
PubMed1991

Inhibition of calcium entry induced by cularines and isocrasifoline in uterine smooth muscle.

The effects of nifedipine, papaverine and four benzylisoquinoline alkaloids (cularine, cularidine, celtisine and isocrasifoline) were studied in isolated rat uterus in order to clarify the mechanism of their relaxant action. All the compounds tested completely relaxed KCl-induced contractions and totally or partially inhibited oxytocin-induced rhythmic contractions. Only papaverine acted intracellularly, promoting relaxation of contractile responses induced by oxytocin or vanadate in a Ca(2+)-free medium. In spite of the structural relationship between papaverine and the other alkaloids, the mechanism of their relaxant action is not the same. The activities of cularine derivatives and of isocrasifoline were similar to that of nifedipine.

Alkaloids↗
PubMed1982

Stable biomembrane surfaces formed by phospholipid polymers.

Phospholipids (phosphatidylcholines) with diacetylene in each acyl chain have been deposited in Langmuir-Blodgett multilayers on a variety of substrates. Upon irradiation the diacetylene groups polymerise and link the phospholipid molecules together with a conjugated chain made up of alternating single, double and triple bonds. Advantage has been taken of this polymerisation process to increase the stability of these lipids layers and to produce stable biomembrane hydrophilic surface. These surfaces may be useful for studies of blood coagulation and protein adsorption. In addition they could also have medical application.

Biopolymers↗