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Low Activity (low + activity)
Selected AbstractsHistone H1 and MAP Kinase Activities in Bovine Oocytes following Protein Synthesis InhibitionREPRODUCTION IN DOMESTIC ANIMALS, Issue 3-4 2001B Meinecke In vitro nuclear maturation is associated with known activity profiles of the M-phase promoting factor (MPF) and the mitogen-activated protein (MAP) kinases, which are two key regulators of mitotic and meiotic cell cycles. Initiation of meiotic resumption in vitro can be prevented by cycloheximide treatment and after removal of the inhibitor germinal vesicle breakdown takes place nearly twice as fast as in untreated controls. In this study experiments were conducted in order to examine the chromosome condensation status and the dynamics of MPF and MAP kinase activities after cycloheximide treatment (10 ,g/ml) of cumulus-enclosed oocytes for 17 and 24 h, respectively, and subsequent culture in inhibitor-free medium for various times. Bovine oocytes displayed variations in the degree of chromosome condensation at the end of the inhibitor treatment phase. Following removal of the inhibitor germinal vesicle breakdown occurred after 4,5 h of subsequent culture in inhibitor-free medium. MPF and MAP kinase exhibited low activities during the first 1,3 h following cycloheximide treatment. Increasing levels of enzyme activities were detected 4,7 h following cycloheximide treatment for 17 and 24 h, respectively, and subsequent culture in inhibitor-free medium. The patterns of enzyme activities corresponded with the accelerated nuclear maturation process. It can be concluded that cycloheximide treatment does not lead to a more synchronous course of nuclear maturation and that the activities of both, MPF and MAP kinase are initiated at least 2,5 h earlier in comparison with untreated oocytes. [source] Changes in the plasma activities of protein C and protein S during pregnancyAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 4 2000Semra Oruç Summary: The objective of the study was to determine the changes in the plasma activities of protein C and protein S that occur during normal pregnancy. In this prospective cross-sectional study, plasma activities of protein C and protein S were measured in 32 normal pregnant women in the first, second and third trimester and 6 weeks after delivery. There was a significant fall in protein C and protein S activities during normal pregnancy compared with the post-puerperal period. The activities of protein C and protein S also gradually decreased through-out pregnancy (p < 0.01). Increasing plasma volume during normal pregnancy and its dilutional effect might play some role in the low activities of protein S observed. The normal falls in protein S and protein C activities make it difficult to diagnose protein S and C deficiency during pregnancy. Based on our findings, if a woman has a thromboembolic event during pregnancy, testing for a definitive diagnosis of protein C or protein S deficiency or functional failure should be delayed until at least 6 weeks postpartum. [source] Diabetic embryopathy: Studies using a rat embryo culture system and an animal modelCONGENITAL ANOMALIES, Issue 3 2005Shoichi Akazawa ABSTRACT The mechanism of diabetic embryopathy was investigated using in vitro experiments in a rat embryo culture system and in streptozotocin-induced diabetic pregnant rats. The energy metabolism in embryos during early organogenesis was characterized by a high rate of glucose utilization and lactic acid production (anaerobic glycolysis). Embryos uninterruptedly underwent glycolysis. When embryos were cultured with hypoglycemic serum, such embryos showed malformations in association with a significant reduction in glycolysis. In a diabetic environment, hyperglycemia caused an increased glucose flux into embryonic cells without a down-regulation of GLUT1 and an increased metabolic overload on mitochondria, leading to an increased formation of reactive oxygen species (ROS). Activation of the hexamine pathway, subsequently occurring with increased protein carbonylation and increased lipid peroxidation, also contributed to the increased generation of ROS. Hyperglycemia also caused a myo-inositol deficiency with a competitive inhibition of ambient glucose, which might have been associated with a diminished phosphoinositide signal transduction. In the presence of low activity of the mitochondrial oxidative glucose metabolism, the ROS scavenging system in the embryo was not sufficiently developed. Diabetes further weakened the antioxidant system, especially, the enzyme for GSH synthesis, ,-GCS, thereby reducing the GSH concentration. GSH depletion also disturbed prostaglandin biosynthesis. An increased formation of ROS in a diminished GSH-dependent antioxidant system may, therefore, play an important role in the development of embryonic malformations in diabetes. [source] Salient virulence factors in anaerobic bacteria, with emphasis on their importance in endodontic infectionsENDODONTIC TOPICS, Issue 1 2004Ingar Olsen Endodontic infections by microbial invasion of the necrotic pulp lead to apical periodontitis of both acute and chronic forms. Acute lesions often develop from multiplication of bacteria in primary infections. Such lesions may also occur as exacerbations of chronic forms provoked for example in conjunction with endodontic treatment measures. The clinical course appears related to the character of the microflora. While primary infections are predominated by a mixed flora of anaerobic bacteria and resembles that of aggressive marginal periodontitis, chronic forms of apical periodontitis emerge following regression of the acute infection, whereupon prevailing bacteria have assumed low activity. The significance of virulence factors is easy to understand as far as acute inflammatory conditions are concerned. The role of virulence factors for sustaining chronic inflammation is more unclear and complex. This review is about salient virulence factors in some selected bacterial genera such as Peptostreptococcus, Porphyromonas, Prevotella and Fusobacterium, which often predominate the root canal microbiota in the acute phase of endodontic infections. [source] Hypothalamic,pituitary,adrenal axis activity and early onset of cannabis useADDICTION, Issue 11 2006Anja C. Huizink ABSTRACT Aims To identify early onset cannabis users by measuring basal hypothalamic,pituitary,adrenal (HPA) axis activity, which may be a risk factor for early onset substance use when showing low activity. Design In a prospective cohort study, adolescents who initiated cannabis use at an early age (9,12 years), those who initiated at a later age (13,14 years) and those who did not use cannabis by the age of 14 were compared with respect to HPA axis activity. Setting and participants Data were used from the first and second assessment wave of the TRacking Adolescents' Individual Lives Survey (TRAILS), that included 1768 Dutch young adolescents aged 10,12 years who were followed-up across a period of 2 years. Measurements Cortisol was measured in saliva samples at awakening, 30 minutes later and at 8 p.m. at age 10,12. Self-reported age at first cannabis use was used. Findings The early onset group had lower cortisol levels 30 minutes after awakening than the late onset group (OR = 0.93, 95% CI: 0.86,0.99). Furthermore, compared to non-users, the early and late onset cannabis users had higher levels of cortisol at 8 p.m. (OR = 1.25, 95% CI: 1.03,1.53 and OR = 1.21, 95% CI: 1.01,1.45, respectively). Conclusions Some evidence was found for HPA axis hypo-activity at awakening in adolescents with early onset of cannabis use compared to late onset users, which might indicate an increased risk for early onset users of seeking stimulation to restore arousal levels by using substances. [source] Ethene Polymerization Behavior of MAO-Activated Dichloridotitanium Complexes Bearing Bi- and Tetradentate Salicylaldimine DerivativesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2010Antti Pärssinen Abstract New chiral bridged tetradentate (N2O2)TiIVCl2 -type complexes bearing dimethylbiphenyl (1-Ti,3-Ti) and previously published binaphthyl-bridged (4-Ti) complex were synthesized with high yields. This was achieved by treating the corresponding Schiff-base ligand (H2L) precursors with Ti(NMe2)4, followed by conversion of these diamido complexes to LTiCl2 derivatives by the addition of excess of Me3SiCl. A series of unbridged titanium complexes 5-Ti,8-Ti with similar substituents at the phenoxy group were studied and their polymerization properties, after methylaluminoxane (MAO) activation, compared with the above bridged complexes. It was found that the catalysts bearing chiral tetradentate biaryl-bridged salicylaldimine ligands produce multimodal polyethylene (PE) with low activity [below 10 kgPE/(molTi,h,bar)] while their unbridged analogues provide activities that are 10,1000 times greater under similar reaction conditions. The reasons for this dramatic difference in polymerization activities are discussed based on the stabilities of the different cationic species configurations. [source] Studies of the Nature of the Catalytic Species in the ,-Olefin Polymerisation Processes Generated by the Reaction of Diamido(cyclopentadienyl)titanium Complexes with Aluminium Reagents as CocatalystsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2005Vanessa Tabernero Abstract The reaction of the diamido(chloro)cyclopentadienyltitanium compounds TiCpRx[1,2-C6H4(NR,)2]Cl [CpRx = ,5 -C5H5, ,5 -C5(CH3)5, ,5 -C5H4(SiMe3); R, = CH2tBu, Pr] with the Grignard reagent MgClR (R = Me, CH2Ph) affords the monomethyl and monobenzyl derivatives TiCpRx[1,2-C6H4(NR,)2]R. Upon addition of methylaluminoxane (MAO), the chloro- and alkyltitanium complexes show low activity towards the polymerisation of ethylene and styrene. However, no methylation was observed during the treatment of trimethylaluminium with the chloro compounds TiCpRx[1,2-C6H4(NR,)2]Cl. Instead, these reactions give the dinuclear aluminium complexes Al2[1,2-C6H4(NR,)2]Me4 (R, = CH2tBu, Pr) through transmetallation of the diamido ligand, suggesting a deactivation process of the catalysts in the olefin polymerisation reactions. In an additional effort to model the catalytic species, stoichiometric reactions between the methyl derivatives TiCpRx[1,2-C6H4(NR,)2]Me and solid methylaluminoxane (MAO) were studied by NMR spectroscopy. Monitoring of these reactions revealed the formation of zwitterionic species depending on the nature of the solvent. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Characterization and mode of action of an exopolygalacturonase from the hyperthermophilic bacterium Thermotoga maritimaFEBS JOURNAL, Issue 21 2005Leon D. Kluskens An intracellular pectinolytic enzyme, PelB (TM0437), from the hyperthermophilic bacterium Thermotoga maritima was functionally produced in Escherichia coli and purified to homogeneity. PelB belongs to family 28 of the glycoside hydrolases, consisting of pectin-hydrolysing enzymes. As one of the few bacterial exopolygalacturonases, it is able to remove monogalacturonate units from the nonreducing end of polygalacturonate. Detailed characterization of the enzyme showed that PelB is highly thermo-active and thermostable, with a melting temperature of 105 °C and a temperature optimum of 80 °C, the highest described to date for hydrolytic pectinases. PelB showed increasing activity on oligosaccharides with an increasing degree of polymerization. The highest activity was found on the pentamer (1000 U·mg,1). In addition, the affinity increased in conjunction with the length of the oligoGalpA chain. PelB displayed specificity for saturated oligoGalpA and was unable to degrade unsaturated or methyl-esterified oligoGalpA. Analogous to the exopolygalacturonase from Aspergillus tubingensis, it showed low activity with xylogalacturonan. Calculations on the subsite affinity revealed the presence of four subsites and a high affinity for GalpA at subsite +1, which is typical of exo-active enzymes. The physiological role of PelB and the previously characterized exopectate lyase PelA is discussed. [source] Protein engineering of Bacillus megaterium CYP102FEBS JOURNAL, Issue 10 2001The oxidation of polycyclic aromatic hydrocarbons Cytochrome P450 (CYP) enzymes are involved in activating the carcinogenicity of polycyclic aromatic hydrocarbons (PAHs) in mammals, but they are also utilized by microorganisms for the degradation of these hazardous environmental contaminants. Wild-type CYP102 (P450BM-3) from Bacillus megaterium has low activity for the oxidation of the PAHs phenanthrene, fluoranthene and pyrene. The double hydrophobic substitution R47L/Y51F at the entrance of the substrate access channel increased the PAH oxidation activity by up to 40-fold. Combining these mutations with the active site mutations F87A and A264G lead to order of magnitude increases in activity. Both these mutations increased the NADPH turnover rate, but the A264G mutation increased the coupling efficiency while the F87A mutation had dominant effects in product selectivity. Fast NADPH oxidation rates were observed (2250 min,1 for the R47L/Y51F/F87A mutant with phenanthrene) but the coupling efficiencies were relatively low (< 13%), resulting in a highest substrate oxidation rate of 110 min,1 for fluoranthene oxidation by the R47L/Y51F/A264G mutant. Mutation of M354 and L437 inside the substrate access channel reduced PAH oxidation activity. The PAHs were oxidized to a mixture of phenols and quinones. Notably mutants containing the A264G mutation showed some similarity to mammalian CYP enzymes in that some 9,10-phenanthrenequinone, the K -region oxidation product from phenanthrene, was formed. The results suggest that CYP102 mutants could be useful models for PAH oxidation by mammalian CYP enzymes, and also potentially for the preparation of novel PAH bioremediation systems. [source] Oxidation of polychlorinated benzenes by genetically engineered CYP101 (cytochrome P450cam)FEBS JOURNAL, Issue 5 2001Jonathan P. Jones Polychlorinated benzenes are recalcitrant environmental pollutants primarily because they are resistant to attack by dioxygenases commonly used by micro-organisms for the biodegradation of aromatic compounds. We have investigated the oxidation of polychlorinated benzenes by mutants of the haem mono-oxygenase CYP101 (cytochrome P450cam) from Pseudomonas putida with the aim of generating novel systems for their biodegradation. Wild-type CYP101 had low activity for the oxidation of dichlorobenzenes and trichlorobenzenes to the chlorophenols, but no products were detected for the heavily chlorinated benzenes. Increasing the active-site hydrophobicity with the Y96F mutation increased the activity up to 100-fold, and both pentachlorobenzene and hexachlorobenzene were oxidized slowly to pentachlorophenol. Decreasing the space available at the top of the active site with the F87W mutation to force the substrate to be bound closer to the haem resulted in a further 10-fold increase in activity with most substrates. Introducing the F98W mutation, also at the top of the active site, decreased the NADH-turnover rates but increased the coupling efficiencies, and >,90% coupling was observed for 1,3-dichlorobenzene and 1,3,5-trichlorobenzene with the F87W,Y96F,F98W mutant. The V247L mutation generally increased the NADH-turnover rates, and the F87W,Y96F,V247L mutant showed reasonably fast NADH turnover (229 min,1) with the highly insoluble pentachlorobenzene without the need for surfactants or organic cosolvents. As all chlorophenols are degraded by micro-organisms, novel biodegradation systems could be constructed in which CYP101 mutants convert the inert polychlorinated benzenes to the phenols, which are then readily degraded by natural pathways. [source] Cloning, expression and characterization of the pig liver GDP-mannose pyrophosphorylaseFEBS JOURNAL, Issue 23 2000Evidence that GDP-mannose, GDP-Glc pyrophosphorylases are different proteins GDP-Man, the mannosyl donor for most Man-containing polymers is formed by the transfer of Man-1- P to GTP to form GDP-Man and PPi. This reaction is catalyzed by the widespread and essential enzyme, GDP-Man pyrophosphorylase (GMPP). The pig liver GMPP consists of an , subunit (43 kDa) and a , subunit (37 kDa). Purified pig GMPP catalyzes the synthesis of GDP-Glc (from Glc-1- P and GTP) and GDP-Man (from Man-1- P and GTP), but has higher activity for the formation of GDP-Glc than for synthesis of GDP-Man. In the present study, we report the cloning of the cDNA for the , subunit of GMPP, and its expression in a bacterial system resulting in the formation of active enzyme. The full length cDNA encoding the , subunit was isolated from a porcine cDNA library, and its predicted gene product showed high amino-acid sequence homology to GMPPs from other species. The gene was expressed in Escherichia coli cells, and a 37-kDa protein was over-produced in these cells. This gene product reacted strongly with antibody reactive to the native , subunit of pig GMPP. Most interestingly, this recombinant protein had high activity for synthesizing GDP-Man (from Man-1- P and GTP), but very low activity for the formation of GDP-Glc (from Glc-1- P and GTP). Other properties of the recombinant protein were also analyzed. This study suggests that the , subunit is the GMPP, whereas the , subunit, or a combination of both subunits, may have the GDP-Glc pyrophosphorylase activity. [source] Antifungal activity of the essential oil of Thymus capitellatus against Candida, Aspergillus and dermatophyte strainsFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2006Lígia Ribeiro Salgueiro Abstract The antifungal activity of Thymus capitellatus oils on Candida, Aspergillus and dermatophyte strains were studied. The essential oils were obtained from the aerial parts of the plants by water distillation and analysed by GC and GC,MS. Three chemotypes were characterized: 1,8-cineole (47.5%), 1,8-cineole/borneol (28.8% and 19.5%, respectively) and 1,8-cineole/linalyl acetate/linalool (27.5%, 20.0% and 17.0%, respectively). The minimal inhibitory concentration (MIC) determined according to the NCCLS protocols (M27-A and M38-P) and the minimal lethal concentration (MLC) were used to evaluate the antifungal activity of the oils against Candida (seven clinical isolates and three ATCC type strains), Aspergillus (five clinical isolates, two CECT and two ATCC type strains) and five dermatophyte clinical fungi strains. The oils exhibited antifungal activity for the dermatophyte strains, with MIC values of 0.32,1.25 µl/ml; the chemotype 1,8-cineole/linalyl acetate/linalool proved to be more active. The highest antifungal activity of this oil can be associated with the contribution of the linalyl acetate. In the other hand, all samples showed low activity against Candida and Aspergillus strains. Copyright © 2006 John Wiley & Sons, Ltd. [source] Caspase activation correlates with the degree of inflammatory liver injury in chronic hepatitis C virus infectionHEPATOLOGY, Issue 4 2001Heike Bantel Hepatitis C virus (HCV) infection is a major cause of liver disease characterized by inflammation, cell damage, and fibrotic reactions of hepatocytes. Apoptosis has been implicated in the pathogenesis, although it is unclear whether proteases of the caspase family as the central executioners of apoptosis are involved and how caspase activation contributes to liver injury. In the present study, we measured the activation of effector caspases in liver biopsy specimens of patients with chronic HCV infection. The activation of caspase-3, caspase-7, and cleavage of poly(ADP-ribose)polymerase (PARP), a specific caspase substrate, were measured by immunohistochemistry and Western blot analysis by using antibodies that selectively detect the active truncated, but not the inactive precursor forms of the caspases and PARP. We found that caspase activation was considerably elevated in liver lobules of HCV patients in comparison to normal controls. Interestingly, the immunoreactive cells did yet not reveal an overt apoptotic morphology. The extent of caspase activation correlated significantly with the disease grade, i.e., necroinflammatory activity. In contrast, no correlation was observed with other surrogate markers such as serum transaminases and viral load. In biopsy specimens with low activity (grade 0) 7.7% of the hepatocytes revealed caspase-3 activation, whereas 20.9% of the cells stained positively in grade 3. Thus, our results suggest that caspase activation is involved in HCV-associated liver injury. Moreover, measurement of caspase activity may represent a reliable marker for the early detection of liver damage, which may open up new diagnostic and therapeutic strategies in HCV infection. [source] Glutathione-S-transferase genotypes and the adverse effects of azathioprine in young patients with inflammatory bowel diseaseINFLAMMATORY BOWEL DISEASES, Issue 1 2007Gabriele Stocco PhD Abstract Background: Adverse drug reactions to azathioprine, the prodrug of 6-mercaptopurine, occur in 15%,38% of patients and the majority are not explained by thiopurine-S-methyltransferase (TPMT) deficiency. Azathioprine is known to induce glutathione depletion and consumption of glutathione is greater in cells with high glutathione-S-transferase (GST) activity compared with those with low activity; moreover, some reports indicate that GST might play a direct role in the reaction of glutathione with azathioprine. The association between polymorphisms of GST-M1, GST-P1, GST-T1, and TPMT genes and the adverse effects of azathioprine was therefore investigated. Methods: Seventy patients with inflammatory bowel disease (IBD), treated with azathioprine, were enrolled and clinical data were retrospectively determined. TPMT and GST genotyping were performed by polymerase chain reaction (PCR) assays on DNA extracted from blood samples. Results: Fifteen patients developed adverse effects (21.4%); there was a significant underrepresentation of the GST-M1 null genotype among patients developing adverse drug reactions to azathioprine (odds ratio [OR] = 0.18, 95% confidence interval [CI] = 0.037,0.72, P = 0.0072) compared with patients who did not develop adverse effects. Patients heterozygous for TPMT mutations presented a marginally significant increased probability of developing adverse effects (OR = 6.38, 95% CI = 0.66,84.1, P = 0.062). Moreover, among the 55 patients who did not develop adverse effects, there was a significant underrepresentation of the GST-M1 null genotype among patients who displayed lymphopenia as compared with those that did not display this effect of azathioprine (OR = 0.15, 95% CI = 0.013,1.08, P = 0.032). Conclusion: Patients with IBD with a wildtype GST-M1 genotype present increased probability of developing adverse effects and increased incidence of lymphopenia during azathioprine treatment. (Inflamm Bowel Dis 2007;13:57,64) [source] The Association Between Obesity and the Frailty Syndrome in Older Women: The Women's Health and Aging StudiesJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 6 2005Caroline S. Blaum MD Objectives: To determine whether obesity is associated with the frailty phenotype and, if so, whether comorbid conditions or inflammatory markers explain this association. Design: Cross-sectional analysis of baseline data from the Women's Health and Aging Studies I (1992) and II (1994), complementary population-based studies. Setting: Twelve contiguous ZIP code areas in Baltimore, Maryland. Participants: Five hundred ninety-nine community-dwelling women aged 70 to 79 with a body mass index (BMI) greater than 18.5 kg/m2. Measurements: The dependent variables were the frailty syndrome, including prefrailty, defined as presence of one or two of five frailty indicators (weakness, slowness, weight loss, low physical activity, exhaustion), and frailty, defined as three or more indicators. Independent variables included BMI, categorized using World Health Organization criteria as normal (18.5 to <25 kg/m2), overweight (25 to <30 kg/m2), and obese (,30 kg/m2); chronic diseases; C-reactive protein; and serum carotenoids. Results: Being overweight was significantly associated with prefrailty, and obesity was associated with prefrailty and frailty. In all frail women, regardless of BMI group, a similar pattern of three defining frailty indicators was found: slowness, weakness, and low activity (with the addition of weight loss in the normal weight group.) In multinomial regression models, obesity was significantly associated with prefrailty (odds ratio (OR)=2.23, 95% confidence interval (CI)=1.29,3.84) and frailty (OR=3.52, 95% CI=1.34,9.13), even when controlling for covariates. Conclusion: Obesity is associated with the frailty syndrome in older women in cross-sectional data. This association remains significant even when multiple conditions associated with frailty are considered. Prospective studies are needed to confirm this finding. [source] Understanding Predictors of Low Physical Activity in Adults with Intellectual DisabilitiesJOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES, Issue 3 2009Janet Finlayson Background, Lack of regular physical activity is globally one of the most significant risks to health. The main aims of this study were to describe the types and levels of regular physical activity undertaken by adults with intellectual disabilities, and to investigate the factors predicting low activity. Materials and Methods, Interviews were conducted with a community-based sample of adults with intellectual disabilities (n = 433) at two time points. Data hypothesized to be predictive of low levels of activity were collected at time 1. Descriptive data were collected on the frequency and intensity, and actual level of participation in activities at time 2. Results, Only 150 (34.6%) adults with intellectual disabilities undertook any regular activity of at least moderate intensity. This was of shorter duration, compared with the general population. Older age, having immobility, epilepsy, no daytime opportunities, living in congregate care and faecal incontinence were independently predictive of low levels of activity. Conclusions, These results are a step towards informing the development of interventions to promote the health of adults with intellectual disabilities through increased physical activity. [source] The COMT val158met Polymorphism Is Associated With Peak BMD in Men,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2004Mattias Lorentzon Abstract The associations between the functional val158met polymorphism of the estrogen-degrading COMT enzyme and skeletal properties in young men were investigated. BMD was associated with COMT genotype. Introduction: Peak BMD is an important predictor of future risk of osteoporosis, and it is to a large extent determined by genetic factors. Estrogens are involved in the accretion of bone mass during puberty. Catechol- O -methyltransferase (COMT) is involved in the degradation of estrogens. There is a functional polymorphism in the COMT gene (val158met), resulting in a 60,75% difference in enzyme activity between the val (high activity [H]) and met (low activity [L]) variants. The aim of this cross-sectional study was to investigate the associations between this polymorphism and peak BMD in young men. Materials and Methods: A total of 458 healthy men (mean age, 19 ± 0.6 years) were genotyped and classified as COMTLL, COMTHL, or COMTHH. Areal BMD (aBMD) was measured by DXA. Cortical and trabecular volumetric BMD (vBMD) were measured by pQCT. The associations between COMT genotype and skeletal phenotypes were determined. Results and Conclusions: Regression models using physical activity, height, weight, age, and COMT genotype as covariates showed that COMT genotype was an independent predictor of aBMD in the total body and in all femur locations investigated, but not in the spine. The values for COMTHL and COMTHH were very similar, and therefore, they were pooled into one group. aBMD at Ward's triangle, trochanter, and total femur were 4.9%, 4.5%, and 3.7% lower, respectively, in the COMTLL than in the COMTHL/HH group (p < 0.01). pQCT analyses showed that COMT genotype was an independent predictor of trabecular vBMD of the tibia, radius, and fibula. Trabecular vBMD of the radius and fibula in COMTLL was 5.3% and 7.4% lower, respectively, than that of the combined COMTHL/HH group. COMT genotype was associated with cortical vBMD but not with cortical cross-sectional area in the tibia. These findings show that the COMT polymorphism is associated with BMD in young adult men. [source] The Metabolic Syndrome: A Brain Disease?JOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2006Ruud M Buijs Summary The incidence of obesity with, as consequence, a rise in associated diseases such as diabetes, hypertension and dyslipidemia , the metabolic syndrome , is reaching epidemic proportions in industrialized countries. Here, we provide a hypothesis that the biological clock which normally prepares us each morning for the coming activity period is altered due to a modern life style of low activity during the day and late-night food intake. Furthermore, we review the anatomical evidence supporting the proposal that an unbalanced autonomic nervous system output may lead to the simultaneous occurrence of diabetes type 2, dyslipidemia, hypertension and visceral obesity. [source] Allosteric kinetics of human carboxylesterase 1: Species differences and interindividual variability,JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2008Shiori Takahashi Abstract Esterified drugs such as imidapril, derapril, and oxybutynin hydrolyzed by carboxylesterase 1 (CES1) are extensively used in clinical practice. The kinetics using the CES1 substrates have not fully clarified, especially concerning species and tissue differences. In the present study, we performed the kinetic analyses in humans and rats in order to clarify these differences. The imidaprilat formation from imidapril exhibited sigmoidal kinetics in human liver microsomes (HLM) and cytosol (HLC) but Michaelis-Menten kinetics in rat liver microsomes and cytosol. The 2-cyclohexyl-2-phenylglycolic acid (CPGA) formation from oxybutynin were not detected in enzyme sources from rats, although HLM showed high activity. The kinetics were clarified to be different among species, tissues, and preparations. In individual HLM and HLC, there was large interindividual variability in imidaprilat (31- and 24-fold) and CPGA formations (15- and 9-fold). Imidaprilat formations exhibited Michaelis-Menten kinetics in HLM and HLC with high activity but sigmoidal kinetics in those with low activity. CPGA formations showed sigmoidal kinetics in high activity HLM but Michaelis-Menten kinetics in HLM with low activity. We revealed that the kinetics were different between individuals. These results could be useful for understanding interindividual variability and for the development of oral prodrugs. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:5434,5445, 2008 [source] Glycoengineering: The effect of glycosylation on the properties of therapeutic proteinsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2005Angus M. Sinclair Abstract Therapeutic proteins have revolutionized the treatment of many diseases but low activity or rapid clearance limits their utility. New approaches have been taken to design drugs with enhanced in vivo activity and half-life to reduce injection frequency, increase convenience, and improve patient compliance. One recently used approach is glycoengineering, changing protein-associated carbohydrate to alter pharmacokinetic properties of proteins. This technology has been applied to erythropoietin and resulted in the discovery of darbepoetin alfa (DA), a hyperglycosylated analogue of erythropoietin that contains two additional N-linked carbohydrates, a threefold increase in serum half-life and increased in vivo activity compared to recombinant human erythropoietin (rHuEPO). The increased serum half-life allows for less frequent dosing to maintain target hemoglobin levels in anemic patients. Carbohydrates on DA and other molecules can also increase molecular stability, solubility, increase in vivo biological activity, and reduce immunogenicity. These properties are discussed. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1626,1635, 2005 [source] Fundamentals and development of high-efficiency supported catalyst systems for atom transfer radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2007Santiago Faucher Abstract Atom transfer radical polymerization (ATRP) is a controlled/living radical polymerization process developed a decade ago that allows the synthesis of tailored macromolecules. It has been widely used in the laboratory for polymer synthesis since but little use has been made of it at the industrial scale for polymer production. This is due to the low activity of the ATRP catalyst that is central to the process. Much work has been done over the years to overcome this challenge, and the greatest successes have been achieved through catalyst supporting and recycling. We present here a historical account of the development of supported ATRP catalysts while shedding light on their present and future challenges. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 553,565, 2007 [source] Copolymerization of vinylcyclohexane with ethene and propene using zirconocene catalystsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2006Erkki Aitola Abstract Vinylcyclohexane (VCH) was copolymerized with ethene and propene using methylaluminoxane-activated metallocene catalysts. The catalyst precursor for the ethene copolymerization was rac -ethylenebis(indenyl)ZrCl2 (1). Propene copolymerizations were further studied with Cs -symmetric isopropylidene(cyclopentadienyl)(fluorenyl)ZrCl2 (2), C1 -symmetric ethylene(1-indenyl-2-phenyl-2-fluorenyl)ZrCl2 (3), and "meso"-dimethylsilyl[3-benzylindenyl)(2-methylbenz[e]indenyl)]ZrCl2 (4). Catalyst 1 produced a random ethene,VCH copolymer with very high activity and moderate VCH incorporation. The highest comonomer content in the copolymer was 3.5 mol %. Catalysts 1 and 4 produced poly(propene- co -vinylcyclohexane) with moderate to good activities [up to 4900 and 15,400 kg of polymer/(mol of catalyst × h) for 1 and 4, respectively] under similar reaction conditions but with fairly low comonomer contents (up to 1.0 and 2.0% for 1 and 4, respectively). Catalysts 2 and 3, both bearing a fluorenyl moiety, gave propene,VCH copolymers with only negligible amounts of the comonomer. The homopolymerization of VCH was performed with 1 as a reference, and low-molar-mass isotactic polyvinylcyclohexane with a low activity was obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6569,6574, 2006 [source] Zolpidem Generalization and Antagonism in Male and Female Cynomolgus Monkeys Trained to Discriminate 1.0 or 2.0 g,/,kg EthanolALCOHOLISM, Issue 7 2008Christa M. Helms Background:, The subtypes of , -aminobutyric acid (GABA)A receptors mediating the discriminative stimulus effects of ethanol in nonhuman primates are not completely identified. The GABAA receptor positive modulator zolpidem has high, intermediate, and low activity at receptors containing ,1, ,2/3, and ,5 subunits, respectively, and partially generalizes from ethanol in several species. The partial inverse agonist Ro15-4513 has the greatest affinity for ,4/6 -containing receptors, higher affinity for ,5 - and lower, but equal, affinity for ,1 - and ,2/3 -, containing GABAA receptors, and antagonizes the discriminative stimulus effects of ethanol. Methods:, This study assessed Ro15-4513 antagonism of the generalization of zolpidem from ethanol in male (n = 9) and female (n = 8) cynomolgus monkeys (Macaca fascicularis) trained to discriminate 1.0 g/kg (n = 10) or 2.0 g/kg (n = 7) ethanol (i.g.) from water with a 30-minute pretreatment interval. Results:, Zolpidem (0.017 to 5.6 mg/kg, i.m.) completely generalized from ethanol (,80% of total session responses on the ethanol-appropriate lever) for 6/7 monkeys trained to discriminate 2.0 g/kg and 4/10 monkeys trained to discriminate 1.0 g/kg ethanol. Zolpidem partially generalized from 1.0 or 2.0 g/kg ethanol in 6/7 remaining monkeys. Ro15-4513 (0.003 to 0.30 mg/kg, i.m., 5-minute pretreatment) shifted the zolpidem dose,response curve to the right in all monkeys showing generalization. Analysis of apparent pKB from antagonism tests suggested that the discriminative stimulus effects of ethanol common with zolpidem are mediated by low-affinity Ro15-4513 binding sites. Main effects of sex and training dose indicated greater potency of Ro15-4513 in males and in monkeys trained to discriminate 1.0 g/kg ethanol. Conclusions:, Ethanol and zolpidem share similar discriminative stimulus effects most likely through GABAA receptors that contain ,1 subunits, however, antagonism by Ro15-4513 of zolpidem generalization from the lower training dose of ethanol (1.0 g/kg) may involve additional zolpidem-sensitive GABAA receptor subtypes (e.g., ,2/3 and ,5). [source] In vitro and in vivo pharmacodynamic properties of the fluoroquinolone ibafloxacinJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2002M. Coulet The pharmacodynamic properties of a new veterinary fluoroquinolone antimicrobial agent, ibafloxacin, were evaluated. Minimal inhibitory concentrations (MIC), time-kill kinetics, postantibiotic effect (PAE) and postantibiotic subminimal inhibitory concentration effects (PA-SME) were determined against pathogenic canine Gram-negative and Gram-positive bacterial isolates from dermal, respiratory and urinary tract infections. The synergistic interactions between ibafloxacin and its main metabolite, 8-hydroxy-ibafloxacin were investigated. Finally, the efficacy of ibafloxacin was tested in in vivo canine infection models. Ibafloxacin had good activity against Pasteurella spp., Escherichia coli, Klebsiella spp., Proteus spp. and Staphylococcus spp. (MIC90=0.5 µg/mL), moderate activity against Bordetella bronchiseptica, Enterobacter spp. and Enterococcus spp. (MIC50=4 µg/mL) and low activity against Pseudomonas spp. and Streptococcus spp. The time-killing analysis confirmed that ibafloxacin was bactericidal with a broad spectrum of activity. The PAE and PA-SME were between 0.7,2.13 and 1,11.5 h, respectively. Finally, studies in dog models of wound infection and cystitis confirmed the efficacy of once daily oral ibafloxacin at a dosage of 15 mg/kg. Additional studies are needed to better define the importance of AUC/MIC (AUIC) and Cmax/MIC ratios on the outcome of fluoroquinolone therapy in dogs. [source] Acetaminophen UDP-glucuronosyltransferase in ferrets: species and gender differences, and sequence analysis of ferret UGT1A6JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2001M. H. Court The principal objective of this study was to determine whether ferrets glucuronidate acetaminophen more slowly compared with other species, and if so investigate the molecular basis for the difference. Acetaminophen-UDP-glucuronosyltransferase (UGT) activities were measured using hepatic microsomes from eight ferrets, four humans, four cats, four dogs, rat, mouse, cow, horse, monkey, pig and rabbit. Gender differences between male and female ferret livers were explored using enzyme kinetic analysis. Immunoblotting of microsomal proteins was also performed using UGT-specific antibodies. Finally, the exon 1 region of UGT1A6, a major acetaminophen-UGT, was sequenced. Glucuronidation of acetaminophen was relatively slow in ferret livers compared with livers from all other species except cat. Gender differences were also apparent, with intrinsic clearance (Vmax/Km) values significantly higher in male compared with female ferret livers. Furthermore, Vmax values correlated with densitometric measurements of two protein bands identified with a UGT1A subfamily-specific antibody. No deleterious mutations were identified in the exon 1 or flanking regions of the ferret UGT1A6 gene. In conclusion, like cats, ferret livers glucuronidate acetaminophen relatively slowly. However, unlike cats, in which UGT1A6 is encoded by a pseudogene and dysfunctional, there are no defects in the ferret UGT1A6 gene which could account for the low activity. [source] Effects of MgCl2 Crystallographic Structure on Active Centre Formation in Immobilized Single-Centre and Ziegler,Natta Catalysts for Ethylene PolymerizationMACROMOLECULAR RAPID COMMUNICATIONS, Issue 21 2008Rubin Huang Abstract The ability of a MgCl2 support to activate a transition metal catalyst has been found to depend both on the crystallographic structure of the support and on the nature of the catalyst. A high degree of crystallographic disorder can be very effective for the immobilization and activation of titanium and vanadium complexes, but is not necessarily effective for zirconocene activation. A highly disordered support prepared by the reaction of MgBu2 with HCl gave high activity with TiCl4 but low activity with (n -PrCp)2ZrCl2. High polymerization activities with the zirconocene were only obtained with supports of type MgCl2/AlRn(OEt)3,n prepared from the reaction of AlR3 with MgCl2,·,1.1EtOH. These supports are characterized by additional peaks in the X-ray diffraction pattern, indicating the presence of a crystalline structure which is absent in the other supports and contains highly Lewis acidic sites able to generate the active metallocenium species. [source] Compounds from Ageratum conyzoides: isolation, structural elucidation and insecticidal activityPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2007Márcio D Moreira Abstract This work aimed at identifying plant compounds with insecticidal activity against Diaphania hyalinata (L.) (Lepidoptera: Pyralidae), Musca domestica (L.) (Diptera: Muscidae), Periplaneta americana (L.) (Blattodea: Blattidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). The plant species used were: basil (Ocimum selloi Benth.), rue (Ruta graveolens L.), lion's ear (Leonotis nepetaefolia L.), Jimson weed (Datura stramonium L.), ,baleeira' herb (Cordia verbenaceae L.), mint (Mentha piperita L.), wild balsam apple (Mormodica charantia L.) and billy goat weed (Ageratum conyzoides L.). Firstly, the insecticidal activities of hexane and ethanol plant extracts were evaluated against adults of R. dominica. Among them, only the hexane extract of A. conyzoides showed insecticidal activity. The hexane extract of this plant species was therefore fractionated by silica gel column chromatography to isolate and purify its bioactive chemical constituents. Three compounds were identified using IR spectra, 1H NMR, 13C NMR, HMBC and NOE after gel chromatography: 5,6,7,8,3,, 4,, 5,-heptamethoxyflavone, 5,6,7,8,3,-pentamethoxy-4,, 5,-methylenedioxyflavone and coumarin. The complete assignment of 13C NMR to 5,6,7,8,3,-pentamethoxy-4,, 5,-methylenedioxyflavone was successfully made for the first time. 5,6,7,8,3,-Pentamethoxy-4,, 5,-methylenedioxyflavone did not show any insecticidal activity against the four insect species tested. 5,6,7,8,3,, 4,, 5,-Heptamethoxyflavone showed low activity against D. hyalinata and R. dominica and was not toxic to M. domestica or P. americana. In contrast, coumarin showed insecticidal activity against all four insect pest species tested, with the following order of susceptibility: R. dominica < P. americana < D. hyalinata < M. domestica after 24 h exposure. Copyright © 2007 Society of Chemical Industry [source] Regulation of glucagon release in mouse ,-cells by KATP channels and inactivation of TTX-sensitive Na+ channelsTHE JOURNAL OF PHYSIOLOGY, Issue 3 2000S. O. Göpel 1The perforated patch whole-cell configuration of the patch-clamp technique was applied to superficial glucagon-secreting ,-cells in intact mouse pancreatic islets. 2,-cells were distinguished from the ,- and ,-cells by the presence of a large TTX-blockable Na+ current, a TEA-resistant transient K+ current sensitive to 4-AP (A-current) and the presence of two kinetically separable Ca2+ current components corresponding to low- (T-type) and high-threshold (L-type) Ca2+ channels. 3The T-type Ca2+, Na+ and A-currents were subject to steady-state voltage-dependent inactivation, which was half-maximal at ,45, ,47 and ,68 mV, respectively. 4Pancreatic ,-cells were equipped with tolbutamide-sensitive, ATP-regulated K+ (KATP) channels. Addition of tolbutamide (0·1 mm) evoked a brief period of electrical activity followed by a depolarisation to a plateau of ,30 mV with no regenerative electrical activity. 5Glucagon secretion in the absence of glucose was strongly inhibited by TTX, nifedipine and tolbutamide. When diazoxide was added in the presence of 10 mm glucose, concentrations up to 2 ,m stimulated glucagon secretion to the same extent as removal of glucose. 6We conclude that electrical activity and secretion in the ,-cells is dependent on the generation of Na+ -dependent action potentials. Glucagon secretion depends on low activity of KATP channels to keep the membrane potential sufficiently negative to prevent voltage-dependent inactivation of voltage-gated membrane currents. Glucose may inhibit glucagon release by depolarising the ,-cell with resultant inactivation of the ion channels participating in action potential generation. [source] Enantioselective Synthesis of l -Homophenylalanine by Whole Cells of Recombinant Escherichia coli Expressing l -Aminoacylase and N -Acylamino Acid Racemase Genes from Deinococcus radiodurans BCRC12827BIOTECHNOLOGY PROGRESS, Issue 6 2006Shih-Kuang Hsu l -Homophenylalanine (l -HPA) is a chiral unnatural amino acid used in the synthesis of angiotensin converting enzyme inhibitors and many pharmaceuticals. To develop a bioconversion process with dynamic resolution of N -acylamino acids for the l -HPA production, N -acylamino acid racemase (NAAAR) and l -aminoacylase (LAA) genes were cloned from Deinococcus radiodurans BCRC12827 and expressed in Escherichia coli XLIBlue. The recombinant enzymes were purified by nickel-chelate chromatography, and their biochemical properties were determined. The NAAAR had high racemization activity toward chiral N -acetyl-homophenylalanine (NAc-HPA). The LAA exhibited strict l -enantioselection to hydrolyze the NAc- l -HPA. A stirred glass vessel containing transformed E. coli cells expressing D. radiodurans NAAAR and LAA was used for the conversion of NAc- d -HPA to l -HPA. Unbalance activities of LAA and NAAAR were found in E. coli cell coexpressing laa and naaar genes, which resulted in the accumulation of an intermediate, NAc- l -HPA, in the early stage of conversion and a low productivity of 0.83 mmol l -HPA/L h. The results indicated that low activity of LAA present in the biomass is the rate-limiting factor in l -HPA production. In the case of two whole cells with separately expressed enzyme, the enzymatic activities of LAA and NAAAR could be balanced by changing the loading of individual cells. When the activities of two enzymes were fixed at 3600 U/L, 99.9% yield of l -HPA could be reached in 1 h, with a productivity of 10 mmol l -HPA/L h. The cells can be reused at least six cycles at a conversion yield of more than 96%. This is the first NAAAR/LAA process using NAc-HPA as substrate and recombinant whole cells containing Deinococcus enzymes as catalysts for the production of l -HPA to be reported. [source] Improving 1,3-Propanediol Production from Glycerol in a Metabolically Engineered Escherichia coliby Reducing Accumulation of sn -Glycerol-3-phosphateBIOTECHNOLOGY PROGRESS, Issue 4 2002Marie M. Zhu High levels of glycerol significantly inhibit cell growth and 1,3-propanediol (1,3-PD) production in anaerobic glycerol fermentation by genetically engineered Escherichia coli( E. coli) strains expressing genes from the Klebsiella pneumoniae dha( K.pneumoniae) regulon. We have previously demonstrated that 1,3-PD production by the engineered E. colican be improved by reducing the accumulation of methylglyoxal. This study focuses on investigation of another lesser-known metabolite in the pathways related to 1,3-PD production-glycerol-3-phosphate (G3P). When grown anaerobically on glycerol in the absence of an exogenous acceptor, the engineered E.colistrains have intracellular G3P levels that are significantly higher than those in K. pneumoniae, a natural 1,3-PD producer. Furthermore, in the engineered E. colistrains, the G3P levels increase with increasing glycerol concentrations, whereas, in K. pneumoniae, the concentrations of G3P remain relatively constant. Addition of fumarate, which can stimulate activity of anaerobic G3P dehydrogenase, into the fermentation medium led to a greater than 30-fold increase in the specific activity of anaerobic G3P dehydrogenase and a significant decrease in concentrations of intracellular G3P and resulted in better cell growth and an improved production of 1,3-PD. This indicates that the low activity of G3P dehydrogenase in the absence of an exogenous electron acceptor is one of the reasons for G3P accumulation. In addition, spent media from E. coliLin61, a glycerol kinase (responsible for conversion of glycerol to G3P) mutant, contains greatly decreased concentrations of G3P and shows improved production of 1,3-PD (by 2.5-fold), when compared to media from its parent strain E. coliK10. This further suggests that G3P accumulation is one of the reasons for the inhibition of 1,3-PD production during anaerobic fermentation. [source] | |||||||||||||||||||