Systematic, computer-assisted optimisation of the isolation of Thermus thermophilus 50S ribosomal proteins by reversed-phase high-performance liquid chromatography

Isolation of the 50S ribosomal proteins from Thermus thermophilus has been achieved for the first time using reversed-phase high-performance liquid chromatography based on the use of the non-end-capped LiChrospher RP-18 sorbent and computer-assisted method development for optimisation of the resolution. The separation approach for these basic ribosomal proteins utilised mobile phases of high ionic strength, to suppress silanophilic interactions with this type of reversed-phase sorbent. These conditions were found to be a key requirement for achieving good resolution with minimal peak-tailing. The retention times of the 50S ribosomal proteins of Thermus thermophilus were observed to be in very close agreement with the values predicted by computer simulation procedures based on linear solvent strength concepts, with an average error of only 0.5%, whilst base-line resolution was achieved for most of the adjacent peak zones. Following N-terminal sequencing, the proteins TthL5, TthL9, TthL18, TthL24, TthL29, TthL32, TthL34, TthL35 and TthL36 of Thermus thermophilus were readily identified. This approach thus provided a readily optimised strategy for the isolation of the 50S ribosomal proteins from Thermus thermophilus and should be generally applicable to the corresponding ribosomal proteins from various other species, as well as other classes of basic proteins present in crude extracts derived from other biological sources.     

Effects of curvature and stenosis-like narrowing on wall shear stress in a coronary artery model with phasic flow

To gain insight into the details of intracoronary flow we have used computational fluid dynamic techniques to determine the velocity and wall shear stress distributions in both steady- and phasic-flow models of a curved coronary artery with several degrees of stenosis. The steady-flow Reynolds number was 500 and the peak phasic flow Reynolds number was 700. Without stenosis and at 25% (area) stenosis wall shear stress and velocities are higher at the outer wall than the inner wall but retain the same direction as the superimposed flow. At higher stenoses laminar flow separation occurs and the inner wall is exposed to shear stresses that vary widely, both temporally and spatially.     

Differential diagnosis of posterior cranial fossa: potentialities and unsolved problems

This study describes nurse practitioners' (NPs) practice and employment trends, primary care/direct patient care involvement, scope of practice issues, productivity, and demographic characteristics. Data were collected by mailed survey from 2,499 NPs in New York State. NPs were predominantly certified as Adult, Pediatric or Family NPs. The vast majority of NPs were working (64.1% full-time; 22.7% part-time). Fifty percent said they spend over 80% of their time providing primary care. Over 50% of the NPs employed in non-hospital settings said that their organizations had contracts with four or more managed care organizations.     

Obliteration of gallbladder lumen in patients with high operation risk

The paper presents pilot results of clinical application of developed experimintally method of treatment for acute cholecystitis based on demucosation of the gall-bladder followed by obliteration of its lumen. Two modifications of the method-treatment of mucous membrane of the gall-bladder by phenol emulsion (16 patients) and electrocoagulation of the mucosa (49 patients)--were used with good clinical results in patients with high operation risk. Follow-up results are available for up to 3.5 years.     

Genotoxicity and cytotoxicity in male B6C3F1 mice following exposure to mixtures of 1,3-butadiene and styrene

1,3-Butadiene and styrene are oxidized, in part, by cytochrome P450 2E1 and have been shown to metabolically interact in rodents exposed by inhalation to mixtures of both compounds. Because the reactive metabolites of butadiene and styrene are thought to be responsible for the toxicity of each compound, metabolic interactions may alter the response in animals exposed to mixtures of butadiene and styrene compared with the response in animals exposed to butadiene alone or styrene alone. The purpose of this study was to quantitate alterations in genotoxicity and cytotoxicity in male B6C3F1 mice exposed to mixtures of butadiene and styrene. Male B6C3F1 mice were exposed to 6.25, 62.5, 200, or 625 ppm butadiene alone, 50 ppm styrene alone, or mixtures of 6.25, 62.5, 200, or 625 ppm butadiene and 50 ppm styrene. Genotoxicity was assessed by quantitating the frequency of micronucleated polychromatic erythrocytes in bone marrow. Cytotoxicity was assessed by counting total spleen and thymus cells and by quantitating the frequency of polychromatic erythrocytes in the peripheral blood. Butadiene and mixtures of butadiene and styrene were genotoxic in mice, as shown by a significant increase in the frequency of micronucleated polychromatic erythrocytes. The increased frequency following exposure to mixtures of butadiene and styrene was not significantly different compared with the frequency following exposure to butadiene alone. Styrene and mixtures of butadiene and styrene were cytotoxic in mice, as shown by significantly decreased number of spleen cells. Exposure to mixtures of butadiene and styrene with butadiene concentrations of 62.5 or 625 ppm significantly reduced the number of thymus cells. Exposure to 200 ppm or 625 ppm butadiene alone, or to mixtures of 200 ppm or 625 ppm butadiene and 50 ppm styrene, significantly reduced the frequency of polychromatic erythrocytes in the peripheral blood. The results of the study demonstrate that exposure to mixture of butadiene and styrene does not reduce the respective genotoxicity of butadiene or cytotoxicity of styrene.     

Beta-2 adrenergic activation of L-type Ca++ current in cardiac myocytes

The whole-cell patch-clamp and intracellular perfusion techniques were used for studying the effects of a beta-2 adrenergic receptor activation on the L-type Ca current (ICa) in frog ventricular myocytes. The beta-2 adrenergic agonist zinterol increased ICa in a concentration-dependent manner with an EC50 (i.e., the concentration of zinterol at which the response was 50% of the maximum) of 2.2 nM. The effect of zinterol was essentially independent of the membrane potential. The stimulatory effect of zinterol was competitively antagonized by ICI 118,551, a beta-2 adrenergic antagonist. The maximal stimulatory effect of zinterol was comparable in amplitude to the effect of a saturating concentration (1 or 10 microM) of isoprenaline, a nonselective beta adrenergic agonist. Moreover, 3-isobutyl-1-methylxanthine (100 microM), a nonselective phosphodiesterase inhibitor, or forskolin (10 microM), a direct activator of adenylyl cyclase, had no additive effects in the presence of 0.1 microM zinterol. Zinterol had a long lasting action on frog ICa because after washout of the drug, ICa returned to basal level with a time constant of 17 min. An application of acetylcholine (1 microM) during this recovery phase promptly reduced ICa back to its basal level suggesting a persistent activation of adenylyl cyclase due to a slow dissociation rate constant of zinterol from its receptor. Zinterol also increased ICa in rat ventricular and human atrial myocytes, and the maximal effect was obtained at 10 and 1 microM, respectively. In all three preparations, intracellular perfusion with 20 microM PKI(15-22), a highly selective peptide inhibitor of cAMP-dependent protein kinase, completely antagonized the stimulatory effect of zinterol on ICa. We conclude that beta-2 adrenergic receptor activation produces a strong increase in ICa in frog, rat and human cardiac myocytes which is due to stimulation of adenylyl cyclase and activation of cAMP-dependent phosphorylation.     

In vitro and in vivo digestibility of the albumin and globulin fractions of eight Brazilian cowpea [Vigna unguiculata (L) Walp] cultivars

Cowpea (Vigna unguiculata) is a very important crop for people living in the north‐east of Brazil where it constitutes the principal source of protein and carbohydrate. In this study, it was observed that the in vitro digestibility of the seed albumin and globulin fractions extracted from eight Brazilian cowpea cultivars was high when treated with pepsin but resistant to degradation by trypsin or chymotrypsin even after 3 h of treatment. When the albumin and globulin fractions were given to rats by intragastric intubation it was observed that intact proteins or their fragments were immunodetected in the faeces. Immunohistochemical analyses of the gut sections of these rats showed that a proportion of the albumin fraction (or its fragments), but not the globulin one, was bound to the brush border enterocytes in the duodenum. Thus the incomplete enzymatic degradation of both globulin and albumin fractions as well as the albumin binding to the gut may have a bearing upon the growth depression, malabsorption and diarrhoea observed on rats fed on cowpea seeds. Copyright © 2004 Society of Chemical Industry