Carbohydrate response element (ChRE)-binding protein (ChREBP) is a recently discovered transcription factor that is activated in response to high glucose concentrations in liver independently of insulin. ChREBP was first identified by its ability to bind the ChRE of the liver pyruvate kinase (LPK) gene. We recently reported that the increase in expression of multiple liver lipogenic enzyme mRNAs elicited by feeding a high-carbohydrate diet as well as that of LPK mRNA is markedly reduced in mice lacking ChREBP gene expression (ChREBP ؊/؊ ) in comparison to WT mice. The present study provides evidence for a direct and dominant role of ChREBP in the glucose regulation of two key liver lipogenic enzymes, acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS). ACC, FAS, and LPK mRNA levels were higher in WT hepatocytes cultured with high (25 mM) rather than low (5.5 mM) glucose medium, but there was no effect of glucose concentration on these mRNA levels in ChREBP ؊/؊ hepatocytes. Similarly, reporter constructs containing ACC, FAS, or LPK gene ChREs were responsive to glucose when transfected into WT but not ChREBP ؊/؊ hepatocytes, and glucose transactivation of the constructs in ChREBP ؊/؊ hepatocytes was restored by cotransfection with a ChREBP expression plasmid. ChREBP binding to ACC, FAS, and LPK ChRE sequences in vitro was demonstrated by electrophoretic mobility super shift assays. In vivo binding of ChREBP to ACC, FAS, and LPK gene promoters in intact liver nuclei from rats fed a high-carbohydrate diet was demonstrated by using a formaldehyde crosslinking and chromatin immunoprecipitation procedure.

Factors that elevate amyloid-␤ (A␤) peptide levels are associated with an increased risk for Alzheimer's disease. Insulysin has been identified as one of several proteases potentially involved in A␤ degradation based on its hydrolysis of A␤ peptides in vitro. In this study, in vivo levels of brain A␤40 and A␤42 peptides were found to be increased significantly (1.6-and 1.4-fold, respectively) in an insulysin-deficient gene-trap mouse model. A 6-fold increase in the level of the ␥-secretase-generated C-terminal fragment of the A␤ precursor protein in the insulysin-deficient mouse also was found. In mice heterozygous for the insulysin gene trap, in which insulysin activity levels were decreased Ϸ50%, brain A␤ peptides were increased to levels intermediate between those in wild-type mice and homozygous insulysin gene-trap mice that had no detectable insulysin activity. These findings indicate that there is an inverse correlation between in vivo insulysin activity levels and brain A␤ peptide levels and suggest that modulation of insulysin activity may alter the risk for Alzheimer's disease.A myloid-␤ (A␤) peptide-containing senile plaques are a prominent feature of the pathology of Alzheimer's disease (AD) and occur consistently in AD of all etiology, from earlyonset, familial-linked AD to late-onset AD of indeterminate origin (1). A␤ is formed from the amyloid precursor protein (APP) by sequential enzymatic processing. A ␤-secretase cleavage first yields the 99-aa C-terminal fragment (CTF) of APP, CTF␤, which then is cleaved by ␥-secretase to release A␤ peptides, predominately A␤40 and A␤42, and the CTF␥ peptides of 49-51 residues (2).The proteolysis of APP to yield A␤ peptides is a normal physiologic process observed in multiple cell types, although the endogenous function of APP processing and its products is still not well defined (3). To date, all of the genetic mutations linked to AD result in increased A␤ accumulation, albeit by distinct mechanisms.Although considerable effort has been directed toward generating specific inhibitors of the ␤-and ␥-secretases as a means of preventing A␤ formation (4), the mechanism of A␤ clearance also is of considerable interest because the steady-state concentrations of A␤ peptides are dependent on both their rates of synthesis and their rates of clearance. Recent studies suggest that an important route of A␤ clearance is through hydrolytic cleavage by proteases and peptidases (recently reviewed in refs. 36-38). The peptidase insulysin (EC 3.4.24.56) is one of the enzymes that has been suggested as a candidate A␤-degrading enzyme primarily based on its ability to degrade A␤ peptides in vitro (5-7).Insulysin is a zinc metalloprotease, originally identified as an insulin-degrading enzyme (8), that migrates with reported molecular masses of 110-115 kDa on SDS͞polyacrylamide gels and has no demonstrated posttranslational modifications. The observed molecular mass of insulysin is consistent with the use of the second of its two potential translation initiation sites, although N-te...

The B point on the impedance cardiograph waveform corresponds to the opening of the aortic valve and is an important parameter for calculating systolic time intervals, stroke volume, and cardiac output. Identifying the location of the B point is sometimes problematic because the characteristic upstroke that serves as a marker of this point is not always apparent. Here is presented a reliable method for B point identification, based on the consistent relationship between the R to B interval (RB) and the interval between the R-wave and the peak of the dZ/dt function (RZ). The polynomial function relating RB to RZ (RB = 1.233RZ - 0.0032RZ(2) - 31.59) accounts for 90%-95% of the variance in the B point location across ages and gender and across baseline and stress conditions. This relation affords a rapid approximation to B point measurement that, in noisy or degraded signals, is superior to visual B point identification and to a derivative-based estimate.