Home About us Contact
|
Home About us Contact | ||
|
|
||
Metabolic Capacity (metabolic + capacity)
Selected AbstractsThe roots of microbiology and the influence of Ferdinand Cohn on microbiology of the 19th centuryFEMS MICROBIOLOGY REVIEWS, Issue 3 2000Gerhart Drews Abstract The beginning of modern microbiology can be traced back to the 1870s, and it was based on the development of new concepts that originated during the two preceding centuries on the role of microorganisms, new experimental methods, and discoveries in chemistry, physics, and evolutionary cell biology. The crucial progress was the isolation and growth on solid media of clone cultures arising from single cells and the demonstration that these pure cultures have specific, inheritable characteristics and metabolic capacities. The doctrine of the spontaneous generation of microorganisms, which stimulated research for a century, lost its role as an important concept. Microorganisms were discovered to be causative agents of infectious diseases and of specific metabolic processes. Microscopy techniques advanced studies on microorganisms. The discovery of sexuality and development in microorganisms and Darwin's theory of evolution contributed to the founding of microbiology as a science. Ferdinand Cohn (1828,1898), a pioneer in the developmental biology of lower plants, considerably promoted the taxonomy and physiology of bacteria, discovered the heat-resistant endospores of bacilli, and was active in applied microbiology. [source] Structure, function and evolution of the gas exchangers: comparative perspectivesJOURNAL OF ANATOMY, Issue 4 2002J. N. Maina Abstract Over the evolutionary continuum, animals have faced similar fundamental challenges of acquiring molecular oxygen for aerobic metabolism. Under limitations and constraints imposed by factors such as phylogeny, behaviour, body size and environment, they have responded differently in founding optimal respiratory structures. A quintessence of the aphorism that ,necessity is the mother of invention', gas exchangers have been inaugurated through stiff cost,benefit analyses that have evoked transaction of trade-offs and compromises. Cogent structural,functional correlations occur in constructions of gas exchangers: within and between taxa, morphological complexity and respiratory efficiency increase with metabolic capacities and oxygen needs. Highly active, small endotherms have relatively better-refined gas exchangers compared with large, inactive ectotherms. Respiratory structures have developed from the plain cell membrane of the primeval prokaryotic unicells to complex multifunctional ones of the modern Metazoa. Regarding the respiratory medium used to extract oxygen from, animal life has had only two choices , water or air , within the biological range of temperature and pressure the only naturally occurring respirable fluids. In rarer cases, certain animals have adapted to using both media. Gills (evaginated gas exchangers) are the primordial respiratory organs: they are the archetypal water breathing organs. Lungs (invaginated gas exchangers) are the model air breathing organs. Bimodal (transitional) breathers occupy the water,air interface. Presentation and exposure of external (water/air) and internal (haemolymph/blood) respiratory media, features determined by geometric arrangement of the conduits, are important features for gas exchange efficiency: counter-current, cross-current, uniform pool and infinite pool designs have variably developed. [source] Increased fat oxidation and regulation of metabolic genes with ultraendurance exerciseACTA PHYSIOLOGICA, Issue 1 2007J. W. Helge Abstract Aim:, Regular endurance exercise stimulates muscle metabolic capacity, but effects of very prolonged endurance exercise are largely unknown. This study examined muscle substrate availability and utilization during prolonged endurance exercise, and associated metabolic genes. Methods:, Data were obtained from 11 competitors of a 4- to 5-day, almost continuous ultraendurance race (seven males, four females; age: 36 ± 11 years; cycling o2peak: males 57.4 ± 5.9, females 48.1 ± 4.0 mL kg,1 min,1). Before and after the race muscle biopsies were obtained from vastus lateralis, respiratory gases were sampled during cycling at 25 and 50% peak aerobic power output, venous samples were obtained, and fat mass was estimated by bioimpedance under standardized conditions. Results:, After the race fat mass was decreased by 1.6 ± 0.4 kg (11%; P < 0.01). Respiratory exchange ratio at the 25 and 50% workloads decreased (P < 0.01) from 0.83 ± 0.06 and 0.93 ± 0.03 before, to 0.71 ± 0.01 and 0.85 ± 0.02, respectively, after the race. Plasma fatty acids were 3.5 times higher (from 298 ± 74 to 1407 ± 118 ,mol L,1; P < 0.01). Muscle glycogen content fell 50% (from 554 ± 28 to 270 ± 25 nmol kg,1 d.w.; n = 7, P < 0.01), whereas the decline in muscle triacylglycerol (from 32 ± 5 to 22 ± 3 mmol kg,1 d.w.; P = 0.14) was not statistically significant. After the race, muscle mRNA content of lipoprotein lipase and glycogen synthase increased (P < 0.05) 3.9- and 1.7-fold, respectively, while forkhead homolog in rhabdomyosarcoma, pyruvate dehydrogenase kinase 4 and vascular endothelial growth factor mRNA tended (P < 0.10) to be higher, whereas muscle peroxisome proliferator-activated receptor , co-activator-1, mRNA tended to be lower (P = 0.06). Conclusion:, Very prolonged exercise markedly increases plasma fatty acid availability and fat utilization during exercise. Exercise-induced regulation of genes encoding proteins involved in fatty acid recruitment and oxidation may contribute to these changes. [source] Reprogramming of genetic networks during initiation of the Fetal Alcohol Syndrome,DEVELOPMENTAL DYNAMICS, Issue 2 2007Maia L. Green Abstract Fetal Alcohol Spectrum Disorders (FASD) are birth defects that result from maternal alcohol use. We used a non a priori approach to prioritize candidate pathways during alcohol-induced teratogenicity in early mouse embryos. Two C57BL/6 substrains (B6J, B6N) served as the basis for study. Dosing pregnant dams with alcohol (2× 2.9 g/kg ethanol spaced 4 hr on day 8) induced FASD in B6J at a higher incidence than B6N embryos. Counter-exposure to PK11195 (4 mg/kg) significantly protected B6J embryos but slightly promoted FASD in B6N embryos. Microarray transcript profiling was performed on the embryonic headfold 3 hr after the first maternal alcohol injection (GEO data series accession GSE1074). This analysis revealed metabolic and cellular reprogramming that was substrain-specific and/or PK11195-dependent. Mapping ethanol-responsive KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways revealed down-regulation of ribosomal proteins and proteasome, and up-regulation of glycolysis and pentose phosphate pathway in B6N embryos; and significant up-regulation of tight junction, focal adhesion, adherens junction, and regulation of the actin cytoskeleton (and near-significant up-regulation of Wnt signaling and apoptosis) pathways in both substrains. Expression networks constructed computationally from these altered genes identified entry points for EtOH at several hubs (MAPK1, ALDH3A2, CD14, PFKM, TNFRSF1A, RPS6, IGF1, EGFR, PTEN) and for PK11195 at AKT1. Our findings are consistent with the growing view that developmental exposure to alcohol alters common signaling pathways linking receptor activation to cytoskeletal reorganization. The programmatic shift in cell motility and metabolic capacity further implies cell signals and responses that are integrated by the mitochondrial recognition site for PK11195. Developmental Dynamics 236:613,631, 2007. © 2007 Wiley-Liss, Inc. [source] Persistent organochlorine residues and their bioaccumulation profiles in resident and migratory birds from North VietnamENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2002Tu Binh Minh Abstract Concentrations of persistent organochlorines (OCs), such as polychlorinated biphenyls (PCBs), 1 1,1-trichloro-2,2-bis(p -chlorophenyl)ethane (DDT) and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), and chlordane compounds (CHLs), were determined in whole-body homogenates of resident and migratory birds collected from the Red River estuary, North Vietnam, during March and October 1997. Contamination pattern was in the order of DDTs > PCBs > HCHs > CHLs > HCB in both resident and migratory birds. Residue concentrations, according to the feeding habit, showed little variability, which may reflect relatively similar trophic levels of the bird species analyzed. Resident birds accumulated greater concentrations of DDTs as compared to migrants. In contrast, HCH residues were greater in migratory species. Higher proportions of p,p,-DDT to total DDT concentrations were found in many species of residents and migrants, indicating recent exposure to technical DDT in northern Vietnam. Congener-specific PCB analysis showed the predominance of penta- and hexachlorobiphenyls in all the species analyzed. Estimation of hepatic microsomal enzyme activities suggested higher metabolic capacity for PCB congeners in shore birds from Vietnam as compared to higher-trophic predator birds and marine mammals. Comparison of OC residues in avian species in Asia-Pacific revealed that DDT residues in resident birds in North Vietnam are among the highest values reported for the countries surveyed, suggesting recent usage of DDT in Vietnam. Available data for birds, fish, and bivalves from the recent Asia-Pacific Mussel Watch Program suggested that Vietnam might be a potential source of DDT contamination in Asian developing countries. To our knowledge, this is the first study of the OC accumulation in avian species from Vietnam. [source] Prediction of human pharmacokinetics , renal metabolic and excretion clearanceJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 11 2007Urban Fagerholm The kidneys have the capability to both excrete and metabolise drugs. An understanding of mechanisms that determine these processes is required for the prediction of pharmacokinetics, exposures, doses and interactions of candidate drugs. This is particularly important for compounds predicted to have low or negligible non-renal clearance (CL). Clinically significant interactions in drug transport occur mostly in the kidneys. The main objective was to evaluate methods for prediction of excretion and metabolic renal CL (CLR) in humans. CLR is difficult to predict because of the involvement of bi-directional passive and active tubular transport, differences in uptake capacity, pH and residence time on luminal and blood sides of tubular cells, and limited knowledge about regional tubular residence time, permeability (Pe) and metabolic capacity. Allometry provides poor predictions of excretion CLR because of species differences in unbound fraction, urine pH and active transport. The correlation between fraction excreted unchanged in urine (fe) in humans and animals is also poor, except for compounds with high passive Pe (extensive/complete tubular reabsorption; zero/negligible fe) and/or high non-renal CL. Physiologically based in-vitro/in-vivo methods could potentially be useful for predicting CLR. Filtration could easily be predicted. Prediction of tubular secretion CL requires an in-vitro transport model and establishment of an in-vitro/in-vivo relationship, and does not appear to have been attempted. The relationship between passive Pe and tubular fraction reabsorbed (freabs) for compounds with and without apparent secretion has recently been established and useful equations and limits for prediction were developed. The suggestion that reabsorption has a lipophilicity cut-off does not seem to hold. Instead, compounds with passive Pe that is less than or equal to that of atenolol are expected to have negligible passive freabs. Compounds with passive Pe that is equal to or higher than that of carbamazepine are expected to have complete freabs. For compounds with intermediate Pe the relationship is irregular and freabs is difficult to predict. Tubular cells are comparably impermeable (for passive diffusion), and show regional differences in enzymatic and transporter activities. This limits the usefulness of microsome data and makes microsome-based predictions of metabolic CLR questionable. Renal concentrations and activities of CYP450s are comparably low, suggesting that CYP450 substrates have negligible metabolic CLR. The metabolic CLR of high-Pe UDP-glucuronyltransferase substrates could contribute to the total CL. [source] Maternal capital and the metabolic ghetto: An evolutionary perspective on the transgenerational basis of health inequalitiesAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2010Jonathan C.K. Wells There is particular interest in understanding socioeconomic and ethnic variability in health status. The developmental origins of disease hypothesis emphasize the importance of growth patterns across the life-course in relation to noncommunicable disease risk. The physiological components of cardiovascular risk, collectively termed the metabolic syndrome, derive in part from a disparity between the homeostatic "metabolic capacity" of vital organs and the "metabolic load" induced by large tissue masses, a rich diet and sedentary behavior. From an evolutionary perspective, the risk of such disparity is decreased by maternal physiology regulating offspring growth trajectory during gestation and lactation. Maternal capital, defined as phenotypic resources enabling investment in the offspring, allows effective buffering of the offspring from nutritional perturbations and represents the environmental niche initially occupied by the offspring. Offspring growth patterns are sensitive to the magnitude of maternal capital during early windows of plasticity. Offspring life-history strategy can then respond adaptively to further factors across the life-course, but only within the context of this initial maternal influence on growth. Maternal somatic capital is primarily gained or lost across generations, through variable rates of fetal and infant growth. I argue that the poor nutritional experience of populations subjected to colonialism resulted in a systematic loss of maternal capital, reflected in downward secular trends in stature. Accelerating the recovery of somatic capital within generations overloads metabolic capacity and exacerbates cardiovascular risk, reflected in increased disease rates in urbanizing and emigrant populations. Public health policies need to benefit metabolic capacity without exacerbating metabolic load. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source] Lung Development of Monotremes: Evidence for the Mammalian MorphotypeTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2009Kirsten Ferner Abstract The reproductive strategies and the extent of development of neonates differ markedly between the three extant mammalian groups: the Monotremata, Marsupialia, and Eutheria. Monotremes and marsupials produce highly altricial offspring whereas the neonates of eutherian mammals range from altricial to precocial. The ability of the newborn mammal to leave the environment in which it developed depends highly on the degree of maturation of the cardio-respiratory system at the time of birth. The lung structure is thus a reflection of the metabolic capacity of neonates. The lung development in monotremes (Ornithorhynchus anatinus, Tachyglossus aculeatus), in one marsupial (Monodelphis domestica), and one altricial eutherian (Suncus murinus) species was examined. The results and additional data from the literature were integrated into a morphotype reconstruction of the lung structure of the mammalian neonate. The lung parenchyma of monotremes and marsupials was at the early terminal air sac stage at birth, with large terminal air sacs. The lung developed slowly. In contrast, altricial eutherian neonates had more advanced lungs at the late terminal air sac stage and postnatally, lung maturation proceeded rapidly. The mammalian lung is highly conserved in many respects between monotreme, marsupial, and eutherian species and the structural differences in the neonatal lungs can be explained mainly by different developmental rates. The lung structure of newborn marsupials and monotremes thus resembles the ancestral condition of the mammalian lung at birth, whereas the eutherian newborns have a more mature lung structure. Anat Rec, 2009. © 2008 Wiley-Liss, Inc. [source] Petroleum hydrocarbon contamination in boreal forest soils: a mycorrhizal ecosystems perspectiveBIOLOGICAL REVIEWS, Issue 2 2007Susan J. Robertson Abstract The importance of developing multi-disciplinary approaches to solving problems relating to anthropogenic pollution is now clearly appreciated by the scientific community, and this is especially evident in boreal ecosystems exposed to escalating threats of petroleum hydrocarbon (PHC) contamination through expanded natural resource extraction activities. This review aims to synthesize information regarding the fate and behaviour of PHCs in boreal forest soils in both ecological and sustainable management contexts. From this, we hope to evaluate potential management strategies, identify gaps in knowledge and guide future research. Our central premise is that mycorrhizal systems, the ubiquitous root symbiotic fungi and associated food-web communities, occupy the structural and functional interface between decomposition and primary production in northern forest ecosystems (i.e. underpin survival and productivity of the ecosystem as a whole), and, as such, are an appropriate focal point for such a synthesis. We provide pertinent basic information about mycorrhizas, followed by insights into the ecology of ecto- and ericoid mycorrhizal systems. Next, we review the fate and behaviour of PHCs in forest soils, with an emphasis on interactions with mycorrhizal fungi and associated bacteria. Finally, we summarize implications for ecosystem management. Although we have gained tremendous insights into understanding linkages between ecosystem functions and the various aspects of mycorrhizal diversity, very little is known regarding rhizosphere communities in PHC-contaminated soils. This makes it difficult to translate ecological knowledge into environmental management strategies. Further research is required to determine which fungal symbionts are likely to survive and compete in various ecosystems, whether certain fungal - plant associations gain in ecological importance following contamination events, and how PHC contamination may interfere with processes of nutrient acquisition and exchange and metabolic processes. Research is also needed to assess whether the metabolic capacity for intrinsic decomposition exists in these ecosystems, taking into account ecological variables such as presence of other organisms (and their involvement in syntrophic biodegradation), bioavailability and toxicity of mixtures of PHCs, and physical changes to the soil environment. [source] In vitro biotransformation of imatinib by the tumor expressed CYP1A1 and CYP1B1BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 2 2008Bertrand Rochat Abstract The main objective of the study was to examine the biotransformation of the anticancer drug imatinib in target cells by incubating it with oxidoreductases expressed in tumor cells. The second objective was to obtain an in silico prediction of the potential activity of imatinib metabolites. An in vitro enzyme kinetic study was performed with cDNA expressed human oxidoreductases and LC-MS/MS analysis. The kinetic parameters (Km and Vmax) were determined for six metabolites. A molecular modeling approach was used to dock these metabolites to the target Abl or Bcr-Abl kinases. CYP3A4 isozyme showed the broadest metabolic capacity, whereas CYP1A1, CYP1B1 and FMO3 isozymes biotransformed imatinib with a high intrinsic clearance. The predicted binding modes for the metabolites to Abl were comparable to that of the parent drug, suggesting potential activity. These findings indicate that CYP1A1 and CYP1B1, which are known to be overexpressed in a wide range of tumors, are involved in the biotransformation of imatinib. They could play a role in imatinib disposition in the targeted stem, progenitor and differentiated cancer cells, with a possible contribution of the metabolites toward the activity of the drug. Copyright © 2008 John Wiley & Sons, Ltd. [source] GENOTYPE AND ALLELE FREQUENCIES OF N -ACETYLTRANSFERASE 2 AND GLUTATHIONE S -TRANSFERASE IN THE IRANIAN POPULATIONCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2007Anahita Torkaman-Boutorabi SUMMARY 1.,Xenobiotic-metabolizing enzymes constitute an important line of defence against a variety of carcinogens. Many are polymorphic, constituting the basis for the wide interindividual variation in metabolic capacity and possibly a source of variation in the susceptibility to chemical-induced carcinogenesis. The aim of the present study was to determine the frequencies of important allelic variants in the N- acetyltransferase 2 (NAT2) and glutathione S- transferase (GST) genes in the Iranian population and compare them with frequencies in other ethnic populations. 2Genotyping was performed in a total of 229 unrelated healthy subjects (119 men, 110 women) for NAT2 and 170 unrelated healthy subjects (89 men, 81 women) for GST from the general Tehran population. A combination of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) was applied for typing of NAT2 polymorphisms. Detection of GSTM1 and GSTT1 null alleles was performed simultaneously using a multiplex PCR assay. 3The frequencies of specific NAT2 alleles were 0.299, 0.314, 0.380, 0.007 and 0.000 for *4 (wild-type), *5 (C481T, M1), *6 (G590A, M2), *7 (G857A, M3) and *14 (G191A, M4), respectively. The most prevalent genotypes were NAT2 *5/*6 (29.70%) and *4/*6 (21.40%). The GSTM1 - and GSTT1 -null alleles were detected in 44.7 and 21.2% of subjects, respectively. 4We found that Iranians resemble Indians with regard to allelic frequencies of the tested variants of NAT2. The predominance of slow (49.36%) and intermediate (41.47%) acetylation status compared with wild-type rapid acetylation status (9.17%) in the study group suggests the significant prevalence of the slow acetylator (SA) phenotypes in the Iranian population. Our data confirmed that Iranians are similar to other Caucasian populations in the frequency of both GSTM1 - and GSTT1 -null alleles. [source] | |||||||||||||