Effects of thromboxane analog U46619 on endothelial damaged canine coronary arteries in vivo

We studied the effects of the thromboxane analog, U46619, infused into the left anterior descending (LAD) artery of intact dogs before and after producing endothelial denudation of the mid portion of the LAD. Proximal artery cross-sectional area (CSA) decreased by 47% with 0.1 microgram/min infusion of U46619 with intact and denuded endothelium, while resting CSA reduced spontaneously following denudation. Coronary resistance vessels demonstrated a marked constrictor response to U46619 with a rise in resistance and a fall in flow and myocardial O2 consumption. U46619 produces significant narrowing of proximal epicardial coronary arteries as well as resistance coronary vessels. This effect could cause ischemia in patients with moderate coronary atherosclerosis.     

Phylogenetic analysis using insertion sequence fingerprinting in Escherichia coli

Chromosomal DNA from 23 closely related, pathogenic strains of Escherichia coli was digested and probed for the insertion sequences IS1, IS2, IS4, IS5, and IS30. Under the assumption that elements residing in DNA restriction fragments of the same apparent length are identical by descent, parsimony analysis of these characters yielded a unique phylogenetic tree. This analysis not only distinguished among bacterial strains that were otherwise identical in their biochemical characteristics and enzyme electrophoretic mobilities, but certain aspects of the topology of the tree were consistent across several unrelated insertion elements. The distribution of IS elements was then reexamined in light of the inferred phylogenetic relationships to investigate the biological properties of the elements, such as rates of insertion and deletion, and to discover apparent recombinational events. The analysis shows that the pattern of distribution of insertion elements in the bacterial genome is sufficiently stable for epidemiological studies. Although the rate of recombination by conjugation has been postulated to be low, at least two such events appear to have taken place.      

The adaptation of enzymes to temperature: catalytic characterization of glucosephosphate isomerase homologues isolated from Mytilus edulis and Isognomon alatus, bivalve molluscs inhabiting different thermal environments

Homologues of glucosephosphate isomerase (GPI, EC 5.3.1.9) were purified to homogeneity and kinetically characterized from Mytilus edulis and Isognomon alatus, two bivalve molluscs experiencing contrasting thermal environments. The enzyme isolated from I. alatus functions at warmer temperatures (25-35 C) than GPI from M. edulis, a species that inhabits colder marine littoral habitats (5-20 C). The former exhibits apparent first-order (with respect to substrate) catalytic rate constants (Vmax/KM) in vitro that become progressively greater than the mussel enzyme as the assay temperature is raised. Apparent zero-order catalytic rate constants (Vmax) are relatively less differentiated. Catalytic efficiency, defined as the rate at which a catalytic event occurs in either reaction direction for reference standard states (substrate concentrations), is greater for the enzyme from the tropical species (I. alatus) at all realistic combinations of temperature and substrate concentration except for the lowest temperatures and highest substrate concentrations, where the GPI from the boreal/temperate M. edulis is more efficient. This pattern of catalytic divergence appears to be due primarily to differentiation in Vmax/KM. These results and other published data are reviewed and shown to be inconsistent with claims that adaptation of enzymes to higher cell temperatures requires a loss in catalytic efficiency.      

Modeling environment for numerical simulation of applied electric fields on biological cells

The application of electric pulses in cells increases membrane permeability. This phenomenon is called electroporation. Current electroporation models do not explain all experimental findings: part of this problem is due to the limitations of numerical methods. The Equivalent Circuit Method (ECM) was developed in an attempt to solve electromagnetic problems in inhomogeneous and anisotropic media. ECM is based on modeling of the electrical transport properties of the medium by lumped circuit elements as capacitance, conductance, and current sources, representing the displacement, drift, and diffusion current, respectively. The purpose of the present study was to implement a 2-D cell Model Development Environment (MDE) of ionic transport process, local anisotropy around cell membranes, biological interfaces, and the dispersive behaviour of tissues. We present simulations of a single cell, skeletal muscle, and polygonal cell arrangement. Simulation of polygonal form indicates that the potential distribution depends on the geometrical form of cell. The results demonstrate the importance of the potential distributions in biological cells to provide strong evidences for the understanding of electroporation.     

The role of FASL,BCL-2 and BAX polymorphisms in brazilian patients with prostate cancer and benign prostatic hyperplasia

Molecular Biology Reports - Prostate cancer (PCA) is one of the leading causes of death among men, being related to several factors, including the aging male population, like benign prostatic...     

An Inexpensive,Accurate, and Precise Wet-Mount Method for Enumerating Aquatic Viruses

Viruses affect biogeochemical cycling, microbial mortality, gene flow, and metabolic functions in diverse environments through infection and lysis of microorganisms. Fundamental to quantitatively investigating these roles is the determination of viral abundance in both field and laboratory samples. One current, widely used method to accomplish this with aquatic samples is the “filter mount” method, in which samples are filtered onto costly 0.02-μm-pore-size ceramic filters for enumeration of viruses by epifluorescence microscopy. Here we describe a cost-effective (ca. 500-fold-lower materials cost) alternative virus enumeration method in which fluorescently stained samples are wet mounted directly onto slides, after optional chemical flocculation of viruses in samples with viral concentrations of <5 × 10⁷ viruses ml⁻¹. The concentration of viruses in the sample is then determined from the ratio of viruses to a known concentration of added microsphere beads via epifluorescence microscopy. Virus concentrations obtained by using this wet-mount method, with and without chemical flocculation, were significantly correlated with, and had precision equivalent to, those obtained by the filter mount method across concentrations ranging from 2.17 × 10⁶ to 1.37 × 10⁸ viruses ml⁻¹ when tested by using cultivated viral isolates and natural samples from marine and freshwater environments. In summary, the wet-mount method is significantly less expensive than the filter mount method and is appropriate for rapid, precise, and accurate enumeration of aquatic viruses over a wide range of viral concentrations (≥1 × 10⁶ viruses ml⁻¹) encountered in field and laboratory samples.     

Comparative cytotoxicity of fumonisin B1 in two cell lines derived from normal human bronchial epithelial cells using four distinct bioassay techniques

This study focuses on the cytotoxic effects of fumonisin B₁ (FB₁) on both immortalised and immortalised and subsequently transfected normal human bronchial epithelial (NHBE) cells of human origin using four bioassays. While the MTT, Neutral Red and hexosaminidase colorimetric assays showed little difference between the toxic effects on the two related cell lines, the clonogenic assay, measuring cell survival and proliferation, indicated that FB₁ had a more toxic effect on the nontransfected cells. This kind ofin vitro approach using cells which retain many characteristics of normal cell growth and differentiation can go some way to developing evaluation models for food safety in the case of mycotoxin contamination without resorting totally to whole animal testing. Nevertheless, one or two cytotoxicity tests may be inadequate for a complete appraisal of toxic potential: rather, as wide a range of methodologies as feasible should be employed initially before meaningful conclusions may be drawn.