Chiral HPLC analysis of venlafaxine metabolites in rat liver microsomal preparations after LPME extraction and application to an in vitro biotransformation study

A three-phase LPME (liquid-phase microextraction) method for the enantioselective analysis of venlafaxine (VF) metabolites (O-desmethylvenlafaxine (ODV) and N-desmethylvenlafaxine (NDV) in microsomal preparations is described for the first time. The assay involves the chiral HPLC separation of drug and metabolites using a Chiralpak AD column under normal-phase mode of elution and detection at 230 nm. The LPME procedure was optimized using multifactorial experiments and the following optimal condition was established: sample agitation at 1,750 rpm, 20 min of extraction, acetic acid 0.1 mol/L as acceptor phase, 1-octanol as organic phase and donor phase pH adjustment to 10.0. Under these conditions, the mean recoveries were 41% and 42% for (-)-(R)-ODV and (+)-(S)-ODV, respectively, and 47% and 48% for (-)-( R)-NDV and (+)-( S)-NDV, respectively. The method presented quantification limits of 200 ng/mL and it was linear over the concentration range of 200-5,000 ng/mL for all analytes. The validated method was employed to study the in vitro biotransformation of VF using rat liver microsomal fraction. The results demonstrated the enantioselective biotransformation of VF.

Uncoupling and oxidative stress in liver mitochondria isolated from rats with acute iron overload

One hypothesis for the etiology of cell damage arising from iron overload is that its excess selectively affects mitochondria. Here we tested the effects of acute iron overload on liver mitochondria isolated from rats subjected to a single dose of i.p. 500 mg/kg iron-dextran. The treatment increased the levels of iron in mitochondria (from 21 +/- A 4 to 130 +/- A 7 nmol/mg protein) and caused both lipid peroxidation and glutathione oxidation. The mitochondria of iron-treated rats showed lower respiratory control ratio in association with higher resting respiration. The mitochondrial uncoupling elicited by iron-treatment did not affect the phosphorylation efficiency or the ATP levels, suggesting that uncoupling is a mitochondrial protective mechanism against acute iron overload. Therefore, the reactive oxygen species (ROS)/H(+) leak couple, functioning as a mitochondrial redox homeostatic mechanism could play a protective role in the acutely iron-loaded mitochondria.

Rheological behavior, zeta potential, and accelerated stability tests of Buriti oil (Mauritia flexuosa) emulsions containing lyotropic liquid crystals

Background: It is well known that the Amazon region presents a huge biodiversity; therefore, countless natural resources are being employed in the production of phytocosmetics and phytomedicines. Objective: The purpose of this work was to obtain emulsions produced with Buriti oil and nonionic surfactants. Methods: Two surfactant systems were employed (Steareth-2 associated to Ceteareth-5 and to Ceteareth-20) to produce the emulsions using phase diagram method. Emulsions were obtained by echo-planar imaging method at 75 degrees C. Rheological behavior and zeta potential were evaluated, and accelerated stability tests were performed. Results: All emulsions analyzed presented pseudoplastic behavior. Zeta potential values were obtained between -14.2 and -53.3 mV. The formulations did not show changes in either physical stability, pH, or rheological behavior after accelerated stability tests. Significant differences were observed only after temperature cycling test. Conclusion: Based on these results, the emulsions obtained could be considered as promising delivery systems.

Effect of zinc supplementation in pregnant mice during experimental Trypanosoma cruzi infection

Zinc is an essential micronutrient and has significant effects on human growth, development, and immune function. Zinc supplementation or deficiency may affect the course of infection. Zinc enhances immune response against a wide range of viral, bacterial, and parasitic pathogens. In the present study, we investigated the effects of zinc sulphate (ZnSO(4)) supplementation (20 mg/kg/day) during pregnancy in mice, Swiss Webster strain infected by the Y strain of Trypanosoma cruzi. Oral supplementation of zinc sulphate in pregnant and non-pregnant infected animals did not affect the count of blood parasites as well as tissue parasitism in the heart, liver, and spleen. Zinc supplementation did not alter female body weight, the length of fetuses and neonates, placental size/weight and mortality rate. Among zinc supplied animals, no significant plasmatic zinc concentrations were observed. Concerning to tissue zinc concentrations, only the liver displayed enhanced values as compared to other organs. For placental parasitism, zinc supplied group displayed a significant decrease in amastigote burdens (P < 0.05). However due to the reduced number of parasite burdens in placenta of animals supplied with zinc, these data suggest that zinc was partially effective in up-regulating the host`s immune response against parasite, probably attenuating the infection in fetuses. (C) 2010 Elsevier Ltd. All rights reserved.

Differential expression of immunomodulatory galectin-1 in peripheral leukocytes and adult tissues and its cytosolic organization in striated muscle

Galectin-1 (Gal-1) is important in immune function and muscle regeneration, but its expression and localization in adult tissues and primary leukocytes remain unclear. To address this, we generated a specific monoclonal antibody against Gal-1, termed alpha hGal-1, and defined a sequential peptide epitope that it recognizes, which is preserved in human and porcine Gal-1, but not in murine Gal-1. Using alpha hGal-1, we found that Gal-1 is expressed in a wide range of porcine tissues, including striated muscle, liver, lung, brain, kidney, spleen, and intestine. In most types of cells, Gal-1 exhibits diffuse cytosolic expression, but in cells within the splenic red pulp, Gal-1 showed both cytosolic and nuclear localization. Gal-1 was also expressed in arterial walls and exhibited prominent cytosolic and nuclear staining in cultured human endothelial cells. However, human peripheral leukocytes and promyelocytic HL60 cells lack detectable Gal-1 and also showed very low levels of Gal-1 mRNA. In striking contrast, Gal-1 exhibited an organized cytosolic staining pattern within striated muscle tissue of cardiac and skeletal muscle and colocalized with sarcomeric actin on I bands. These results provide insights into previously defined roles for Gal-1 in inflammation, immune regulation and muscle biology.

Central Cardiovascular Anatomy and Function in Crocodilia

Abstract: Among the vertebrates, crocodilians have the most complex anatomy of the heart and outflow channels. Their cardiovascular anatomy may also be the most func­tionally sophisticated, combining as it does the best features of both reptilian and mammalian (and avian) systems. The puzzlingly complex "plumbing" of crocodilians has fascinated ana­tomists and physiologists for a very long time, the first paper being that by Panizza (1833). Gradually, with the application of successive techniques of investigation as they became available, its functional significance has become reasonably clear, and the complexity is now revealed as a cardiovascular system of considerable elegance. In this paper I will review the main anatomical features of the heart and outflow channels, discuss what is known about the way they work, and speculate about the probable functional significance.

Measurement Function Design for Visual Tracking Applications

Extracting human postural information from video sequences has proved a difficult research question. The most successful approaches to date have been based on particle filtering, whereby the underlying probability distribution is approximated by a set of particles. The shape of the underlying observational probability distribution plays a significant role in determining the success, both accuracy and efficiency, of any visual tracker. In this paper we compare approaches used by other authors and present a cost path approach which is commonly used in image segmentation problems, however is currently not widely used in tracking applications.

Metabolite mean transit times in the liver as predicted by various models of hepatic elimination

Predicted area under curve (AUC), mean transit time (MTT) and normalized variance (CV2) data have been compared for parent compound and generated metabolite following an impulse input into the liver, Models studied were the well-stirred (tank) model, tube model, a distributed tube model, dispersion model (Danckwerts and mixed boundary conditions) and tanks-in-series model. It is well known that discrimination between models for a parent solute is greatest when the parent solute is highly extracted by the liver. With the metabolite, greatest model differences for MTT and CV2 occur when parent solute is poorly extracted. In all cases the predictions of the distributed tube, dispersion, and tasks-in-series models are between the predictions of the rank and tube models. The dispersion model with mixed boundary conditions yields identical predictions to those for the distributed tube model (assuming an inverse gaussian distribution of tube transit times). The dispersion model with Danckwerts boundary conditions and the tanks-in series models give similar predictions to the dispersion (mixed boundary conditions) and the distributed tube. The normalized variance for parent compound is dependent upon hepatocyte permeability only within a distinct range of permeability values. This range is similar for each model but the order of magnitude predicted for normalized variance is model dependent. Only for a one-compartment system is the MIT for generated metabolite equal to the sum of MTTs for the parent compound and preformed metabolite administered as parent.