SEARCH · PubMed Health

Results for “NASH”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources

PubMed2006

Molecular interaction studies of acrylic esters with 1-alcohols.

Hydrogen bonding between 1-alcohols and acrylic esters in n-heptane has been studied by FTIR spectroscopic method. The formation constant of the 1:1 complexes has been calculated using Nash method. The values of formation constant and free energy change vary with alcohol and ester chain length, which suggests that the strengths of the intermolecular O-H...O=C bonds are shown to be dependent on the alkyl group of acrylic esters and the 1-alcohols and the results shows that the proton donating ability of 1-alcohols is in the order: 1-propanol<1-butanol<1-pentanol and the accepting ability of acrylic esters is in the order: methyl methacrylate<ethyl methacrylate<butyl methacrylate.

1-Butanol↗

PubMed2006

Hydrogen bonding interaction between acrylic esters and monohydric alcohols in non-polar solvents: An FTIR study.

The association between acrylic esters (methyl methacrylate, ethyl methacrylate and butyl methacrylate) and some monohydric (primary, secondary and tertiary) alcohols in non-polar solvents, viz. n-heptane, CCl4 and benzene has been investigated by means of FTIR spectroscopy. The most likely association complex between alcohol and acrylic ester is 1:1 stoichiometric complex through the hydroxyl group of alcohol and the carbonyl group of acrylic ester. The formation constant of the 1:1 complexes has been calculated using Nash method. It appears that the primary alcohols have larger formation constant than the secondary and tertiary alcohols. The results show that the proton donating power of the alcohols decreases in the order primary>secondary>tertiary and the association constant increases with the increase in carbon chain of the alkyl group of acrylic esters and alcohols. Also the results show a significant dependence of the association constant upon the solvents used. The solvent effect on the formation of hydrogen bond equilibria is discussed in terms of specific interaction between the solute and solvent.

Acrylates↗

PubMed2005

Analysis of the QUESTOR water quality model using a Fourier amplitude sensitivity test (FAST) for two UK rivers.

This paper presents the sensitivity analysis of a well-known in-stream water quality model, QUESTOR (QUality Evaluation and Simulation TOol for River systems) as applied to two rivers of contrasting land-use in the northeast of England: the 'rural' Ouse and the 'urban' Aire. The analysis employed a version of the Fourier Amplitude Sensitivity Test (FAST) that quantifies the contribution of changes in individual parameters and combination of parameters to the variance of the model output (here the Nash-Sutcliffe) in an efficient way. The quantification of the sensitivity of the model output to the parameters led to the identification of the most influential parameters. Differences between the Aire and the Ouse were found, reflecting their different water quality regime. Results highlighted the importance of interactions between two, or more, parameters on the model output. It led to question the one-at-a-time calibration method currently applied with QUESTOR and underlined the importance of including interactions between parameters in sensitivity analyses. Comparison of the relative influence of parameters versus input data showed contrasting results. In the urban system, the inputs from discharges (sewage treatment works and industrial effluents) were highly influential on model outputs and generally more important than the model parameters. For the rural river, the tributary discharges were most influential, but only at a similar or a lower level than the model parameters.

Chlorides↗

PubMed2003

Statistical decision theory and evolution.

Two recent articles by Geisler and Diehl use Bayesian statistical decision theory to model the co-evolution of predator and prey in a simple, game-like environment. The prey is characterized by its coloration. The predator is characterized by the chromatic sensitivity of its visual system and its willingness to attack. The authors demonstrate how the coloration of prey and the perceptual system of the predator co-evolve, converging to a Nash equilibrium for both species.

Journal Article↗

PubMed2006

Evolutionary game dynamics with non-uniform interaction rates.

The classical setting of evolutionary game theory, the replicator equation, assumes uniform interaction rates. The rate at which individuals meet and interact is independent of their strategies. Here we extend this framework by allowing the interaction rates to depend on the strategies. This extension leads to non-linear fitness functions. We show that a strict Nash equilibrium remains uninvadable for non-uniform interaction rates, but the conditions for evolutionary stability need to be modified. We analyze all games between two strategies. If the two strategies coexist or exclude each other, then the evolutionary dynamics do not change qualitatively, only the location of the equilibrium point changes. If, however, one strategy dominates the other in the classical setting, then the introduction of non-uniform interaction rates can lead to a pair of interior equilibria. For the Prisoner's Dilemma, non-uniform interaction rates allow the coexistence between cooperators and defectors. For the snowdrift game, non-uniform interaction rates change the equilibrium frequency of cooperators.

Biological Evolution↗

PubMed2006

Game theory and human evolution: a critique of some recent interpretations of experimental games.

Economists and psychologists have been testing Nash equilibrium predictions of game theory models of human behavior. In many instances, humans do not conform to the predictions. These results are of great interest to biologists because they also raise questions about well-known ESS models of cooperation. Cooperation in certain one-shot, anonymous interactions, and a willingness to punish others at a net cost to oneself are some of the most intriguing deviations from standard theory. One proposed explanation for these results that is receiving increasing attention invokes the cultural group selection of 'other regarding' social norms. We critically review this explanation. We conclude that experimental results reveal limits in two implicit models of cognitive structure commonly employed by economists and evolutionary biologists.

Altruism↗

PubMed1998

Concordance between enzyme activity and genotype of glutathione S-transferase theta (GSTT1).

Blood samples from 140 healthy German volunteers were used to further characterize the genetic polymorphism of the human theta class glutathione S-transferase 1 (GSTT1). For measurements of GSTT1 activity, hemolysates were incubated in vitro with different concentrations of dichloromethane. The resulting enzymatically mediated production of formaldehyde was determined colorimetrically by the Nash reaction. GSTT1 genotyping was performed by polymerase chain reaction (PCR) methods using genomic DNA from total white blood cells. The prevalence of homozygous deletion of the GSTT1 gene was 19.3% (95% confidence limits: 12.2-27.7%). There was a high agreement between genotyping and phenotyping data. The individuals with the null genotype had a rate of formaldehyde production below the limit of quantification. In addition, in the group of GSTT1-positive individuals, we could differentiate highly active people (35.7%) from individuals with an intermediate enzyme activity (45.0%). It can be concluded that the PCR method is suitable to quickly genotype large populations, whereas the phenotyping assay at present offers the advantage of differentiating heterozygously from homozygously active subjects. Our results confirm the ethnic differences in the prevalence of the homozygous deleted genotype which were previously observed and seem to exist even between closely related ethnic groups such as German and Swedish populations.

Female↗

PubMed2000

Lipoxygenase-mediated hydrogen peroxide-dependent N-demethylation of N,N-dimethylaniline and related compounds.

To date, studies of xenobiotic N-demethylation have focused on heme-proteins such as P450 and peroxidases. In this study we investigated the ability of non-heme iron proteins, namely soybean lipoxygenase (SLO) and human term placental lipoxygenase (HTPLO) to mediate N-demethylation of N,N-dimethylaniline (DMA) and related compounds in the presence of hydrogen peroxide. In addition to being hydrogen peroxide dependent, the reaction was also dependent on incubation time, concentration of enzyme and DMA and the pH of the medium. Using Nash reagent to estimate formaldehyde production, we determined the specific activity for SLO mediated N-demethylation of DMA to be 200 + 18 nmol HCHO/min per mg protein or 23 +/- 2 nmol/min per nmol of enzyme, while that of HTPLO was 33 +/- 4 nmol HCHO/min per mg protein. Nordihydroguaiaretic acid (NDGA), a classical inhibitor of lipoxygenase (LO), as well as antioxidants and free radical reducing agents, caused a marked reduction in the rate of production of formaldehyde from DMA by SLO. Besides N,N-dimethylaniline, N-methylaniline, N,N,N',N'-tetramethylbenzidine, N,N-dimethyl-p-phenylenediamine, N,N-dimethyl-3-nitroaniline and N,N-dimethyl-p-toluidine were also demethylated by SLO. The formation of a DMA N-oxide was not detected. Preliminary experiments suggested SLO-mediated hydrogen peroxide-dependent S-dealkylation of methiocarb or O-dealkylation of 4-nitroanisole does not occur.

Aniline Compounds↗

PubMed2001

Gln27Glu beta2-adrenergic receptor variant is associated with hypertriglyceridemia and the development of fatty liver.

BACKGROUND: Nonalcoholic steatohepatitis (NASH) is associated with the metabolism of lipid, glucose and energy. Beta-adrenergic receptors play an important role in the regulation of energy expenditure, in part, by stimulating lipid mobilization through lipolysis. METHODS: To assess whether it is common for the beta2-adrenergic receptor (B2AR) gene polymorphisms in codons 16 and 27 to play a role in the development of fatty liver, we investigated 251 unrelated healthy Japanese males who were drug-free and showed no signs of heavy drinking. RESULTS: The allelic frequency of B2AR gene mutation in codons 16 and 27 did not differ between obese subjects (BMI>25.0 kg/m(2), n=151) and non-obese subjects (BMI</=25.0 kg/m(2), n=100). The Gly16 homozygotes had a lower high-density lipoprotein cholesterol (HDL-C) level than the Arg16 homozygotes (1.50+/-0.4 vs. 1.32+/-0.3 mmol/l, p=0.014). However, no significant association with fatty liver was observed in the Gly16 allele frequency. The Gln27Glu27 heterozygotes showed higher concentrations of serum triglycerides (TG) than the Gln27Gln27 homozygotes (1.62+/-0.93 vs. 2.21+/-1.67 mmol/l, p=0.013). This correlation was also observed in all subjects regardless of weight classification. Univariate analysis indicated that subjects with the heterozygous Gln27Glu mutant alleles had a significantly higher prevalence of fatty liver vs. those without the mutation (Glu27 allele frequency, 0.07 vs. 0.12, p=0.047; odds ratio, 1.92; 95% confidence interval, 1.01-3.68). However, multivariate logistic regression models showed the prevalence of fatty liver to be significantly related to the homeostasis model assessment (HOMA) index, BMI, triglyceride and HDL-cholesterol. CONCLUSIONS: These results suggest that the amino-terminal polymorphisms of the beta2-adrenergic receptor gene in codon 27 were associated with hypertryglyceridemia and independent of obesity, and thereby could be involved in the molecular pathogenesis of fatty liver.

Adult↗

PubMed1998

Molecular comparison of Giardia lamblia isolates.

Giardia lamblia (also Giardia duodenalis, Giardia intestinalis) isolates have been variably divided into two or three genotypes by different investigators. We have compared the triose phosphate isomerase sequences of the three genotypes (Groups 1, 2, and 3) described by Nash and shown that Groups 1 and 2 are similar, while Group 3 is markedly different from Groups 1 and 2, indicating that Group 1/2 and Group 3 correspond to the two major genotypes identified by other investigators. We have also analysed three Chinese isolates and showed that two fit into Group 3, while the third contained a mixture of Groups 1 and 3 isolates. These results confirm the relatedness of G. lamblia isolates from throughout the world, and established the feasibility of using DNA amplification and sequence analysis for detecting mixed isolates.

Amino Acid Sequence↗

PubMed1990

Evolutionarily stable stalk to spore ratio in cellular slime molds and the law of equalization in net incomes.

The evolutionarily stable stalk ratio (ESSR) in the cellular slime molds is studied when the fruiting body is formed by multiple clones of various size. The survival probability of a spore cell is assumed to depend on the stalk ratio and the fruiting body size. ESSR is obtained as the non-co-operative equilibrium (Nash solution) that maximizes the fitness of each clone. The following two predictions are obtained: (1) the number of spore cells produced by each clone forming a fruiting body tends to be equalized, even if a variation in clone size exists. As a result, the larger clones do not necessarily enjoy higher fitness than the smaller ones. (2) The stalk ratio and the overall fitness of the fruiting body decrease as the genetic diversity in the fruiting body increases. A condition for the stalk to spore ratio to be invariant of overall fruiting body size is also investigated. Finally, "the law of equalization in net incomes" is proposed, extending result (1) into the broader range of resource allocation problems.

Adaptation, Physiological↗

PubMed1984

Construction and use of models designed to demonstrate some topological properties of multistranded nucleic acid structure and its possible bearing on recombination.

A description is given of the construction and use of a simple model designed to show the consequences of association between duplexes to form some kind of four strand structure in recombination. The model was first devised to help in consideration of the work of Nash et al. (1980). Conclusions drawn from it may however be of wider interest. The model was designed with a detailed molecular model in mind (McGavin, 1971a, 1979). It could however apply to any close juxtaposition of duplexes. A close juxtaposition of duplexes is a feature of several models for recombination, although this is not often referred to explicitly as four strand structure.

DNA↗

PubMed2001

A comment on Neudeck and Podczeck's "adverse selection and regulation in health insurance markets".

Using the Grossman equilibrium concept, Neudeck and Podczeck [Journal of Health Economics 15 (1996) 387] show that imposing a minimum standard on a perfectly competitive insurance market can result in anti-competitive effects: decreased welfare with some insurers earning positive profits. However, the Grossman concept precludes an insurer from offering two separating, cross-subsidizing health plans. When an insurer can offer multiple plans (as under both the Nash and Miyazaki-Wilson equilibrium concepts), I show that minimum standards result in a doubleton equilibrium, never allow positive total profits, and increase welfare. This is of interest since in 1997 more than half of establishments in the US offering choice of multiple plans did so through a single insurer.

Economic Competition↗

PubMed2001

The welfare impact of HMO mergers.

This paper estimates the welfare consequences of HMO mergers using data from California's small-group market. The analysis estimates the parameters from a differentiated products demand system. The parameters are then used to simulate the effects of several HMO mergers by solving for the Nash equilibrium in prices under different ownership structures. Even small mergers in moderately concentrated markets can result in significant consumer surplus reductions. However, these welfare losses can be offset by large efficiency gains. The welfare consequences of HMO mergers turn less upon demand-side considerations than on the health plan's ability to realize efficiencies.

California↗

PubMed2002

The family as the health producer--when spouses act strategically.

The Grossman model has been extended recently in order to take account of the fact that most people lead their lives in a family--using frameworks in which family members, respectively, (a) have common preferences and (b) are Nash-bargainers. These models, however, do not consider individual incentives for behaving strategically. In the model presented in this paper, spouses interact strategically both in the production of own health and in the production of health of other family members. We analyse, inter alia, the impact on the distribution of health of changes in family policies, such as child allowance and custody rules.

Adult↗

PubMed1998

Creaming, skimping and dumping: provider competition on the intensive and extensive margins.

Reimbursement incentives influence both the intensity of services and who is treated when patients differ in severity of illness. The social optimum is compared to the private Cournot-Nash solution for three provider strategies: creaming--over-provision of services to low severity patients; skimping--under-provision of services to high severity patients; and dumping--the explicit avoidance of high severity patients. Cost-based reimbursement results in overprovision of services (creaming) to all types of patients. Prospectively paid providers cream low severity patients and skimp high severity ones. If there is dumping of high severity patients, then there will also be skimping.

Economic Competition↗

PubMed2001

Ursodeoxycholic acid 'mechanisms of action and clinical use in hepatobiliary disorders'.

UDCA exerts its beneficial effect in liver diseases through a diverse, probably, complementary array of mechanisms. The clinical use and efficacy of UDCA in PBC have been evident. UDCA may also have a place in the management of PSC, ICP, cystic fibrosis, PFIC and GVHD involving the liver, although, more studies are needed to further determine its therapeutic potential in these diseases and in other hepatobiliary disorders such as liver allograft rejection, drug and TPN-induced cholestasis, NASH, and alcoholic liver disease.

Animals↗

PubMed2003

Oxidative stress, KLF6 and transforming growth factor-beta up-regulation differentiate non-alcoholic steatohepatitis progressing to fibrosis from uncomplicated steatosis in rats.

BACKGROUND/AIMS: Pathogenesis of non-alcoholic steatohepatitis (NASH) remains poorly understood. Cytochrome P450 2E1 (CYP 2E1), cytokines, oxidative stress and activation of hepatic stellate cells seem to play a role in this process. The aim was to determine the potential implication of these factors in the progression from uncomplicated steatosis to steatohepatitis with progressive fibrosis. METHODS: Animals were fed a standard diet, a 5% orotic acid-diet (OA) developing hepatic steatosis, or the methionine-choline deficient (MCD) diet inducing steatohepatitis for 2 and 6 weeks. Lipid peroxidation, CYP 2E1 expression and activity, expression of UCP-2, interleukin (IL)-6, transforming growth factor (TGF)beta1, KLF6 mRNAs, and activation of hepatic stellate cells were examined by gas chromatography, high-performance liquid chromatography, Western blotting, quantitative polymerase chain reaction and immunohistochemistry. RESULTS: Lipid peroxidation increased in the MCD model whereas only minor changes occurred in the OA model. KLF6 and TGFbeta1 mRNAs were selectively up-regulated in MCD animals. Stellate cell activation, inflammation and collagen deposition only occurred in the MCD group. CYP 2E1 expression and activity increased in the OA group while both decreased in MCD animals. UCP-2 and IL-6 mRNA increased in both groups. CONCLUSIONS: In the context of steatosis, lipid peroxidation is associated with inflammation and stellate cell activation with concomitant increase in TGFbeta1 production, possibly through up-regulation of KLF6.

Actins↗