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Metabolic Studies (metabolic + studies)
Selected AbstractsReproduction and metabolism at , 10°C of bacteria isolated from Siberian permafrostENVIRONMENTAL MICROBIOLOGY, Issue 4 2003Corien Bakermans Summary We report the isolation and properties of several species of bacteria from Siberian permafrost. Half of the isolates were spore-forming bacteria unable to grow or metabolize at subzero temperatures. Other Gram-positive isolates metabolized, but never exhibited any growth at , 10°C. One Gram-negative isolate metabolized and grew at , 10°C, with a measured doubling time of 39 days. Metabolic studies of several isolates suggested that as temperature decreased below + 4°C, the partitioning of energy changes with much more energy being used for cell maintenance as the temperature decreases. In addition, cells grown at , 10°C exhibited major morphological changes at the ultrastructural level. [source] In vitro inhibition of CYP3A4 by herbal remedies frequently used by cancer patientsPHYTOTHERAPY RESEARCH, Issue 7 2009Silje Engdal Abstract The herbal remedies Natto K2, Agaricus, mistletoe, noni juice, green tea and garlic, frequently used by cancer patients, were investigated for their in vitro inhibition potential of cytochrome P-450 3A4 (CYP3A4) metabolism. To our knowledge, only garlic and green tea had available data on the possible inhibition of CYP3A4 metabolism. Metabolic studies were performed with human c-DNA baculovirus expressed CYP3A4. Testosterone was used as a substrate and ketoconazole as a positive quantitative inhibition control. The formation of 6- , -OH-testosterone was quantified by a validated HPLC methodology. Green tea was the most potent inhibitor of CYP3A4 metabolism (IC50: 73 µg/mL), followed by Agaricus, mistletoe and noni juice (1324, 3594, >10 000 µg/mL, respectively). All IC50 values were high compared with those determined for crude extracts of other herbal remedies. The IC50/IC25 ratios for the inhibiting herbal remedies ranged from 2.15 to 2.67, indicating similar inhibition profiles of the herbal inhibitors of CYP3A4. Garlic and Natto K2 were classified as non-inhibitors. Although Agaricus, noni juice, mistletoe and green tea inhibited CYP3A4 metabolism in vitro, clinically relevant systemic or intestinal interactions with CYP3A4 were considered unlikely, except for a probable inhibition of intestinal CYP3A4 by the green tea product. Copyright © 2009 John Wiley & Sons, Ltd. [source] Carbon metabolism of intracellular bacteriaCELLULAR MICROBIOLOGY, Issue 1 2006Ernesto J. Muñoz-Elías Summary Bacterial metabolism has been studied intensively since the first observations of these ,animalcules' by Leeuwenhoek and their isolation in pure cultures by Pasteur. Metabolic studies have traditionally focused on a small number of model organisms, primarily the Gram negative bacillus Escherichia coli, adapted to artificial culture conditions in the laboratory. Comparatively little is known about the physiology and metabolism of wild microorganisms living in their natural habitats. For ,500,1000 species of commensals and symbionts, and a smaller number of pathogenic bacteria, that habitat is the human body. Emerging evidence suggests that the metabolism of bacteria grown in vivo differs profoundly from their metabolism in axenic cultures. [source] Evidence against a sexual dimorphism in glucose and fatty acid metabolism in skeletal muscle cultures from age-matched men and post-menopausal womenACTA PHYSIOLOGICA, Issue 3 2009A. Rune Abstract Aim:,In vivo whole body differences in glucose/lipid metabolism exist between men and women. Thus, we tested the hypothesis that intrinsic sex differences exist in skeletal muscle gene expression and glucose/lipid metabolism using cultured myotubes. Methods:, Myotube cultures were prepared for gene expression and metabolic studies from vastus lateralis skeletal muscle biopsies obtained from age-matched men (n = 11; 59 ± 2 years) and post-menopausal women (n = 10; 60 ± 1 years). Results:, mRNA expression of several genes involved in glucose and lipid metabolism was higher in skeletal muscle biopsies from female vs. male donors, but unaltered between the sexes in cultured myotubes. Basal and insulin-stimulated glucose uptake, as well as glucose incorporation into glycogen, was similar in myotube cultures derived from male vs. female donors. In males vs. females, insulin increased glucose uptake (1.3 ± 0.1 vs. 1.5 ± 0.1-fold respectively) and incorporation into glycogen (2.3 ± 0.3 vs. 2.0 ± 0.3-fold respectively) to the same extent. Basal fatty acid oxidation and rate of uptake/accumulation was similar between sexes. In response to the 5,AMP-activated protein kinase activator AICAR, lipid oxidation was increased to the same extent in myotubes established from male vs. female donors (1.6 ± 0.6 vs. 2.0 ± 0.3-fold respectively). Moreover, the AICAR-induced rate of uptake/accumulation was similar between sexes. Conclusion:, Differences in metabolic parameters and gene expression profiles between age-matched men and post-menopausal women noted in vivo are not observed in cultured human skeletal muscle cells. Thus, the sexual dimorphism in glucose and lipid metabolism is likely a consequence of systemic whole body factors, rather than intrinsic differences in the skeletal muscle proper. [source] Evidence for genetic heterogeneity in D -2-hydroxyglutaric aciduria,HUMAN MUTATION, Issue 3 2010Martijn Kranendijk Abstract We performed molecular, enzyme, and metabolic studies in 50 patients with D -2-hydroxyglutaric aciduria (D -2-HGA) who accumulated D -2-hydroxyglutarate (D -2-HG) in physiological fluids. Presumed pathogenic mutations were detected in 24 of 50 patients in the D -2-hydroxyglutarate dehydrogenase (D2HGDH) gene, which encodes D -2-hydroxyglutarate dehydrogenase (D -2-HGDH). Enzyme assay of D -2-HGDH confirmed that all patients with mutations had impaired enzyme activity, whereas patients with D -2-HGA whose enzyme activity was normal did not have mutations. Significantly lower D -2-HG concentrations in body fluids were observed in mutation-positive D -2-HGA patients than in mutation-negative patients. These results imply that multiple genetic loci may be associated with hyperexcretion of D -2-HG. Accordingly, we suggest a new classification: D -2-HGA Type I associates with D -2-HGDH deficiency, whereas idiopathic D -2-HGA manifests with normal D -2-HGDH activity and higher D -2-HG levels in body fluids compared with Type I patients. It remains possible that several classifications for idiopathic D -2-HGA patients with diverse genetic loci will be revealed in future studies. Hum Mutat 31:1,5, 2010. © 2009 Wiley-Liss, Inc. [source] Synthesis of 14C-labelled EM-800 (SCH 57050) and EM-652·HCl (SCH 57068·HCl, acolbifene), pure selective estrogen receptor modulatorsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 11 2004Jean-Yves Sancéau Abstract EM-800 (SCH 57050) and EM-652·HCl (SCH 57068·HCl, acolbifene) are orally active pure selective estrogen receptor modulators. The corresponding 14C2 -radiolabelled compounds 1 and 2 were synthesized for metabolic studies with uniform labelling of two carbons within the benzene ring of the 2H-1-benzopyran moiety by optical resolution of racemic (±)-[14C2]EM-343 4. This pivotal intermediate amine was prepared in 6 steps with 38% yield from commercially available [U- 14C2]resorcinol (3). Resolution by selective crystallization of the diastereomeric mixture of (S)-(+)-camphorsulfonates salts gave the desired (+)-[14C2]EM-652·(+)-CSA 13. Moreover, the racemic amine 4 was recovered from mother liquors by basic treatment, and resolved again. We obtained salt 13, at a 52% yield with 97% diastereomeric excess by repeating the resolution,racemization process. Finally, the corresponding dipivaloate (+)-[14C2]EM-800 1 and hydrochloride salt (+)-[14C2]EM-652·HCl 2 were prepared at respective specific activities of 19.7 and 24.5 µCi/mg with 96.3% radiochemical purity. Copyright © 2004 John Wiley & Sons, Ltd. [source] Synthesis of [3,- 14C] coenzyme Q10JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 10 2002Kimio Hamamura Abstract Radio-labelled coenzyme Q10, labelled at the 3,-position with 14C, was synthesized starting from natural solanesol and ethyl [3- 14C] acetoacetate. The radiochemical yield was 8.0% from ethyl [3- 14C] acetoacetate. The specific radioactivity of the product was 44.8 ,Ci, 1.66 MBq/mg. The specific radioactivity and radiochemical purity are sufficiently high to enable us to use this labelled form of coenzyme Q10 in metabolic studies. Copyright © 2002 John Wiley & Sons, Ltd. [source] Characteristics of murine histidinaemia and its potential for genetic manipulationLIVER INTERNATIONAL, Issue 4 2004N. Mellor Abstract: Background: Histidinaemia is an autosomal recessive disorder affecting the hepatic enzyme histidine ammonia lyase (histidase) resulting in elevated plasma and urinary histidine and is prototypic of a series of hepatic cytosolic enzyme defects. Aims: To characterise the physiology of murine histidinaemia with respect to histidine excretion and catabolism, and explore the potential for manipulating cellular and whole body histidase metabolism by gene transfer. Materials and Methods: We studied his/his mice which have a G to A substitution in the gene encoding histidase, using both in vitro transduction of isolated hepatocytes by lipofection with wild-type histidase cDNA, and in vivo transduction of whole liver using a retroviral construct. Results and Conclusion: Histidase cDNA expression restored histidase activity in vivo and in vitro towards normal levels, demonstrated both at the cellular level and by whole body metabolic studies, establishing the potential of this model for the development of new gene therapeutic approaches. [source] High-performance liquid chromatography/tandem mass spectrometry for the quantitative analysis of a novel taxane derivative (BAY59-8862) in biological samples and characterisation of its metabolic profile in rat bile samplesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2001Cristina Sottani A sensitive, specific, accurate and reproducible high-performance liquid chromatography (HPLC) analytical method was developed and validated for the quantification of the novel oral taxane analogue BAY59-8862 in mouse plasma and tissue samples. A fully automated solid-phase extraction procedure was applied to the plasma after internal standard (IS) addition, with only 0.2,mL volume of the sample loaded on a CN-Sep-pak cartridge. In the case of the tissues a very simple acetonitrile extraction was used to recover BAY59-8862 and its internal standard from liver. The procedure for the quantification of BAY59-8862 and its IS (IDN5127) is based on high-performance liquid chromatography/ion spray-tandem mass spectrometry, operating in selected ion monitoring mode. The retention times of BAY and IS were 7.21 and 10.36,min, respectively. In both plasma and tissue specimens the assay was linear in the range 50,5000,ng/mL (ng/g). The overall precision and accuracy were assessed on three different days. The results for plasma were within 6.1% (precision) and between 99 and 112% (accuracy), and for the liver samples within 7.3% and between 104 and 118%, respectively. The LOD was 5,ng/mL and 20,ng/g in the plasma and liver, respectively. In addition, the biliary excretion of the compound in rats was studied. The study showed that an oxidative chemical reaction was the preferred metabolic pathway for biliary excretion, and two sets of mono- and dihydroxylated metabolites were detected by LC/ISP-MS/MS experiments. With this method, BAY59-8862 pharmacokinetic was determined in mice. The combined results demonstrate that the methodology can be considered a valid approach to conduct pharmacokinetic and metabolic studies during preclinical and clinical investigations. Copyright © 2001 John7 Wiley & Sons, Ltd. [source] Labeled brassinosteroids for biochemical studiesTHE CHEMICAL RECORD, Issue 5 2007Vladimir Khripach Abstract The present paper describes the results of our studies on the synthesis of brassinolide biosynthetic precursors as tools for investigations of new biosynthetic routes leading to brassinosteroids. The corresponding labeled compounds containing three or six deuterium atoms at terminal methyl group(s) of the side chain (in a position ensuring lack of isotopic exchange) were prepared starting from stigmasterol or bisnorcholenic acid. Two strategies for the construction of the carbon skeleton of the side chain were applied in this study: Claisen rearrangement of allylic alcohols and convergent synthesis based on the coupling of 22-aldehydes with appropriate chiral sulfone. More than 20 brassinolide precursors (actual or suspected) have been prepared for metabolic studies that enabled identification of new brassinosteroids and biosynthetic subpathways to brassinolide in Secale cereale and Arabidopsis thaliana. © 2007 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 7: 265,274; 2007: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20123 [source] Resting energy metabolism of Goeldi's monkey (Callimico goeldii) is similar to that of Other callitrichidsAMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2003Michael L. Power Abstract The resting metabolic rates (RMRs) of six adult Goeldi's monkeys (Callimico goeldii) were measured using standard methods of open circuit respirometry during both the active (daytime) and inactive (nighttime) circadian phases for this species. One subject was measured both while she was pregnant and after she delivered a full-term, stillborn infant. Inactive-phase RMR within thermal neutrality (above 27.5°C) averaged 288.5±30.8 ml O2/hr; active-phase RMR within thermal neutrality averaged 416.3±60.9 ml O2/hr. These values are 74.6% and 107.6%, respectively, of the mammalian expected for animals of this body mass. During the inactive phase, metabolic rate increased an estimated 4.3% for every degree decline in temperature below 27.5°C. The RMR in Goeldi's monkey is similar quantitatively and qualitatively to those of other captive callitrichids that have been studied, with active-phase RMR being at or slightly above the mammalian expected, and inactive-phase RMR being significantly reduced. We propose that this circadian pattern of RMR is a consequence of small body size, and is not a specific metabolic adaptation within the Callitrichidae. Thus we predict that metabolic studies measuring both circadian phases in other small primates will also find this pattern of reduced RMR during the inactive phase. The inactive-phase RMR within thermal neutrality of the pregnant female was not different from that measured after the stillbirth, despite an almost 15% difference in body mass. During pregnancy, however, the female was more metabolically responsive to temperature below thermal neutrality, and had a lower upper critical temperature (i.e., was less tolerant of heat). Am. J. Primatol. 60:57,67, 2003. © 2003 Wiley-Liss, Inc. [source] In Vitro/in Vivo scaling of alprazolam metabolism by CYP3A4 and CYP3A5 in humansBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 2 2001Noriko Hirota Abstract We attempted to predict the in vivo metabolic clearance of alprazolam from in vitro metabolic studies using human liver microsomes and human CYP recombinants. Good correlations were observed between the intrinsic clearance (CLint) for 4-hydroxylation and CYP3A4 content and between the CLint for ,-hydroxylation and CYP3A5 content in ten human liver microsomal samples. Using the recombinant CYP isoforms expressed in insect cells, the CLint for CYP3A4 was about 2-fold higher than the CLint for CYP3A5 in the case of 4-hydroxylation. However, the CLint for CYP3A5 was about 3-fold higher than the CLint for CYP3A4 in the case of ,-hydroxylation. The metabolic rates for 4- and ,-hydroxylation increased as the added amount of cytochrome b5 increased, and their maximum values were 3- to 4-fold higher than those without cytochrome b5. The values of CLint, in vivo predicted from in vitro studies using human liver microsomes and CYP3A4 and CYP3A5 recombinants were within 2.5 times of the observed value calculated from literature data. The average CLint value (sum of 4- and ,-hydroxylation) obtained using three human liver microsomal samples was 4-fold higher than that obtained using three small intestinal microsomal samples from the same donors, indicating the minor contribution of intestinal metabolism to alprazolam disposition. The area under the plasma concentration-time curve (AUC) of alprazolam is reported to increase following co-administration of ketoconazole and the magnitude of the increase predicted from the in vitroKi values and reported pharmacokinetic parameters of ketoconazole was 2.30,2.45, which is close to the value observed in vivo (3.19). A quantitative prediction of the AUC increase by cimetidine was also successful (1.73,1.79 vs 1.58,1.64), considering the active transport of cimetidine into the liver. In conclusion, we have succeeded in carrying out an in vitro/in vivo scaling of alprazolam metabolism using human liver microsomes and human CYP3A4 and CYP3A5 recombinants. Copyright © 2001 John Wiley & Sons, Ltd. [source] Impact of skin tone on the performance of a transcutaneous jaundice meterACTA PAEDIATRICA, Issue 12 2009Stephen Wainer Abstract Aim:, To evaluate the performance of the Konica Minolta/Air-Shields® JM-103 jaundice meter on the basis of infant skin tone during the early neonatal period. Methods:, Infants were prospectively categorized into light, medium and dark skin tone groups relative to two reference colours. Transcutaneous bilirubin readings were taken at predetermined intervals through the early neonatal period on a convenience sample of 938 healthy infants ,37 weeks gestation. Serum bilirubin measurements were drawn routinely with metabolic studies and repeated in the presence of an elevated transcutaneous reading or clinically significant jaundice. Results:, Multivariate linear regression analysis showed a significant impact on serum and transcutaneous bilirubin agreement by skin tone. Highest precision and lowest bias were observed for medium skin toned infants. Greater disagreement between serum and transcutaneous measurements was noted at serum bilirubin concentrations >200 ,mol/L. Insufficient numbers of dark skin toned infants were enroled to evaluate fully the performance of the jaundice meter for this group. Conclusion:, The JM-103 jaundice meter displayed good correlation with serum bilirubin concentrations in light and medium skin tone infants, although it showed a tendency to under-read in the lighter skin tone group and to over-read in the darker skin tone group. The device shows excellent performance characteristics for use as a screening device. [source] 2-Acylaminopyridin-4-ylimidazoles as p38 MAP Kinase Inhibitors: Design, Synthesis, and Biological and Metabolic EvaluationsCHEMMEDCHEM, Issue 11 2009Katharina Ziegler Dr. Abstract Targeting cytokines has become an important focus in the treatment of many inflammatory disorders. p38 MAP kinase (MAPK) is the key enzyme in regulating the biosynthesis and release of pro-inflammatory cytokines such as IL-1, and TNF,. Inhibition of p38 MAPK results in decreased expression of these cytokines. Tri- and tetrasubstituted pyridinylimidazoles are potent inhibitors of p38 MAPK. Substitution on the pyridinyl moiety allows the design of inhibitors that show increased selectivity and activity by targeting the enzyme's hydrophobic region,II. The objective of this study was to synthesize novel 1,2,4,5-tetrasubstituted imidazole derivates and to characterize them not only for their ability to inhibit p38 MAPK and modulate cytokine release in human whole blood, but also to evaluate their metabolic stability. Biological data and metabolic studies demonstrate that the introduction of a 2-acylamino function at C2 of the pyridine results in highly efficient and metabolically stable inhibitors relative to C2-alkylamino derivatives. A series of novel candidates was investigated for metabolic stability in human liver microsomes and in human whole blood. Additionally, metabolic S-oxidation was investigated, and possible metabolites were synthesized. [source] | ||||||||||||||||