Hyperglycemia Activates Caspase-1 and TXNIP-Mediated IL-1β Transcription in Human Adipose Tissue

Contains fulltext : 96993.pdf (publisher's version ) (Closed access)OBJECTIVE: Obesity is characterized by elevated levels of proinflammatory cytokines, including interleukin (IL)-1beta, that contribute to the development of insulin resistance. In this study, we set out to investigate whether hyperglycemia drives IL-1beta production and caspase-1 activation in murine and human adipose tissue, thus inducing insulin resistance. RESEARCH DESIGN AND METHODS: ob/ob animals were used as a model to study obesity and hyperglycemia. Human adipose tissue fragments or adipocytes were cultured in medium containing normal or high glucose levels. Additionally, the role of thioredoxin interacting protein (TXNIP) in glucose-induced IL-1beta production was assessed. RESULTS: TXNIP and caspase-1 protein levels were more abundantly expressed in adipose tissue of hyperglycemic ob/ob animals as compared with wild-type mice. In human adipose tissue, high glucose resulted in a 10-fold upregulation of TXNIP gene expression levels (P < 0.01) and a 10% elevation of caspase-1 activity (P < 0.05), together with induction of IL-1beta transcription (twofold, P < 0.01) and a significant increase in IL-1beta secretion. TXNIP suppression in human adipocytes, either by a small interfering RNA approach or a peroxisome proliferator-activated receptor-gamma agonist, counteracted the effects of high glucose on bioactive IL-1 production (P < 0.01) mainly through a decrease in transcription levels paralleled by reduced intracellular pro-IL-1beta levels. CONCLUSIONS: High glucose activates caspase-1 in human and murine adipose tissue. Glucose-induced activation of TXNIP mediates IL-1beta mRNA expression levels and intracellular pro-IL-1beta accumulation in adipose tissue. The concerted actions lead to enhanced secretion of IL-1beta in adipose tissue that may contribute to the development of insulin resistance

Expression QTL Modules as Functional Components Underlying Higher-Order Phenotypes

Systems genetics studies often involve the mapping of numerous regulatory relations between genetic loci and expression traits. These regulatory relations form a bipartite network consisting of genetic loci and expression phenotypes. Modular network organizations may arise from the pleiotropic and polygenic regulation of gene expression. Here we analyzed the expression QTL (eQTL) networks derived from expression genetic data of yeast and mouse liver and found 65 and 98 modules respectively. Computer simulation result showed that such modules rarely occurred in randomized networks with the same number of nodes and edges and same degree distribution. We also found significant within-module functional coherence. The analysis of genetic overlaps and the evidences from biomedical literature have linked some eQTL modules to physiological phenotypes. Functional coherence within the eQTL modules and genetic overlaps between the modules and physiological phenotypes suggests that eQTL modules may act as functional units underlying the higher-order phenotypes

Hearing shapes of drums - mathematical and physical aspects of isospectrality

In a celebrated paper '"Can one hear the shape of a drum?"' M. Kac [Amer. Math. Monthly 73, 1 (1966)] asked his famous question about the existence of nonisometric billiards having the same spectrum of the Laplacian. This question was eventually answered positively in 1992 by the construction of noncongruent planar isospectral pairs. This review highlights mathematical and physical aspects of isospectrality.Comment: 42 pages, 60 figure

Formation of stable uranium(VI) colloidal nanoparticles in conditions relevant to radioactive waste disposal

The favored pathway for disposal of higher activity radioactive wastes is via deep geological disposal. Many geological disposal facility designs include cement in their engineering design. Over the long term, interaction of groundwater with the cement and waste will form a plume of a hyperalkaline leachate (pH 10-13), and the behavior of radionuclides needs to be constrained under these extreme conditions to minimize the environmental hazard from the wastes. For uranium, a key component of many radioactive wastes, thermodynamic modeling predicts that, at high pH, U(VI) solubility will be very low (nM or lower) and controlled by equilibrium with solid phase alkali and alkaline-earth uranates. However, the formation of U(VI) colloids could potentially enhance the mobility of U(VI) under these conditions, and characterizing the potential for formation and medium-term stability of U(VI) colloids is important in underpinning our understanding of U behavior in waste disposal. Reflecting this, we applied conventional geochemical and microscopy techniques combined with synchrotron based in situ and ex situ X-ray techniques (small-angle X-ray scattering and X-ray adsorption spectroscopy (XAS)) to characterize colloidal U(VI) nanoparticles in a synthetic cement leachate (pH > 13) containing 4.2-252 μM U(VI). The results show that in cement leachates with 42 μM U(VI), colloids formed within hours and remained stable for several years. The colloids consisted of 1.5-1.8 nm nanoparticles with a proportion forming 20-60 nm aggregates. Using XAS and electron microscopy, we were able to determine that the colloidal nanoparticles had a clarkeite (sodium-uranate)-type crystallographic structure. The presented results have clear and hitherto unrecognized implications for the mobility of U(VI) in cementitious environments, in particular those associated with the geological disposal of nuclear waste

Effects of ketotifen on human lymphocytes in vitro and in vivo

The effects of the antiasthmatic drug ketotifen (CAS 34580-13-7) on human mononuclear leukocytes were studied in vitro and in vivo. In vitro ketotifen concentration-dependently inhibited mitogen-stimulated lymphocyte proliferation. High ketotifen concentrations also inhibited T-lymphocyte mitogen- and adenosine triphosphate stimulated increases in intracellular Ca2+ in lymphocytes and the U937 human monocyte precursor cell line, respectively; this involved inhibition of both Ca2+ influx and intracellular mobilization. In in vivo experiments, treatment of healthy volunteers with 1 mg ketotifen b.i.d. for 7 d did not alter the number or subset composition of circulating lymphocytes. Moreover, the mitogen-stimulated in vitro proliferation of lymphocytes obtained before and after ketotifen treatment in vivo was similar. It is concluded that high ketotifen concentrations can inhibit the activation of resting lymphocytes in vitro but standard ketotifen treatment does not notably affect the number of function of circulating lymphocytes in viv

N-Acetylcysteine improves the disturbed thiol redox balance after methionine loading

Item does not contain fulltextMethionine loading seems to be accompanied by increased oxidative stress and damage. However, it is not known how this oxidative stress is generated. We performed the present crossover study to further elucidate the effects of methionine loading on oxidative stress in the blood of healthy volunteers, and to examine possible preventative effects of N -acetylcysteine (NAC) administration. A total of 18 healthy subjects were given two oral methionine loads of 100 mg/kg body weight, 4 weeks apart, one without NAC (Met group), and one in combination with supplementation with 2x900 mg doses of NAC (Met+NAC group). Blood samples were collected before and 2, 4, 8 and 24 h after methionine loading for measurements of thiol levels, protein carbonyls, lipid peroxidation, cellular fibronectin and ferric reducing ability of plasma (FRAP; i.e. antioxidant capacity). After methionine loading, whole-blood levels of free and oxidized cysteine and homocysteine were increased in both groups. Furthermore, the total plasma levels of homocysteine were higher, whereas those of cysteine were lower, after methionine loading in both groups. Lower levels of oxidized homocysteine and a higher free/oxidized ratio were found in the Met+NAC group compared with the Met group. Although the antioxidant capacity decreased after methionine loading, no major changes over time were found for protein carbonyls or cellular fibronectin in either group. Our results suggest that methionine loading may initiate the generation of reactive oxygen species by the (auto)-oxidation of homocysteine. In addition, supplementation with NAC seems to be able to partially prevent excessive increases in the levels of homocysteine in plasma and of oxidized homocysteine in whole blood, and might thereby contribute to the prevention of oxidative stress

Effects of insulin-induced hypoglycemia on beta 2-adrenoceptor density and proliferative responses of human lymphocytes

We studied the effects of insulin (0.1 IU/kg BW, iv)-induced hypoglycemia on lymphocyte beta 2-adrenoceptor function, lymphocyte subset distribution, and proliferative response to mitogen stimulation in 10 healthy volunteers. Thirty minutes after insulin injection plasma glucose levels were markedly decreased; concomitantly, plasma epinephrine levels had increased about 10-fold; plasma norepinephrine levels, however, increased only moderately. Lymphocyte beta 2-adrenoceptor density and the cAMP response to 10 mumol/L isoproterenol stimulation were elevated; lymphocyte Ts/c-cells had increased, whereas Th-cells had decreased, resulting in a decrease in the Th-/Ts/c-cell ratio from 1.7 to 1.0. These changes were accompanied by a significantly reduced lymphocyte proliferative response (measured as [3H]thymidine uptake) to mitogen stimulation. Two hours after insulin injection plasma catecholamines, lymphocyte beta 2-adrenoceptor function, lymphocyte subset distribution, and proliferative responses had returned to nearly preinsulin levels. We conclude that acute vigorous increases in endogenous epinephrine evoked by insulin-induced hypoglycemia are associated with increases in lymphocyte beta 2-adrenoceptor function, redistribution of lymphocyte subsets, and an (at least transiently) attenuated in vitro immune responsivenes