Phys Chem Chem Phys
October 2020
In this work, we report the theoretical maximum bending angle of MoS2 devices using the creative non-collinear electrodes method based on the first principles theory. The results show that the device with 1T-phase MoS2 electrodes sandwiching N-type MoS2 in a zigzag direction has a better conducting behavior as compared with P-type in an armchair direction. The conductance decreases less than 15% when the angle between the two electrodes is less than 45° in both the equilibrium state and non-equilibrium state because of the continuous resonant response between the two electrodes and the little deformed band structure.
View Article and Find Full Text PDFBiochim Biophys Acta
July 2014
Background: Choline kinase has three isoforms encoded by the genes Chka and Chkb. Inactivation of Chka in mice results in embryonic lethality, whereas Chkb(-/-) mice display neonatal forelimb bone deformations.
Methods: To understand the mechanisms underlying the bone deformations, we compared the biology and biochemistry of bone formation from embryonic to young adult wild-type (WT) and Chkb(-/-) mice.
Biochim Biophys Acta
June 2014
There is a paucity of information about phosphatidylcholine (PC) biosynthesis in bone formation. Thus, we characterized PC metabolism in both primary human osteoblasts (HOB) and human osteosarcoma MG-63 cells. Our results show that the CDP-choline pathway is the only de novo route for PC biosynthesis in both HOB and MG-63 cells.
View Article and Find Full Text PDFPrion diseases are infectious neurodegenerative diseases associated with the accumulation of protease-resistant prion protein, neuronal loss, spongiform change and astrogliosis. In the mouse model, the loss of dendritic spines is one of the earliest pathological changes observed in vivo, occurring 4-5 weeks after the first detection of protease-resistant prion protein in the brain. While there are cell culture models of prion infection, most do not recapitulate the neuropathology seen in vivo.
View Article and Find Full Text PDFBiosynthesis of hepatic choline via phosphatidylethanolamine N-methyltransferase (PEMT) plays an important role in the development of type 2 diabetes and obesity. We investigated the mechanism(s) by which choline modulates insulin sensitivity. PEMT wild-type (Pemt(+/+)) and knock-out (Pemt(-/-)) mice received either a high fat diet (HF; 60% kcal of fat) or a high fat, high choline diet (HFHC; 4 g of choline/kg of HF diet) for 1 week.
View Article and Find Full Text PDFPrevious studies demonstrated that choline supply is directly linked to high-fat-diet-induced obesity and insulin resistance in mice. The aim of this study was to evaluate if choline supply could also modulate obesity and insulin resistance caused by a genetic defect. Eight-week-old male ob/ob mice were fed for two months with either choline-deficient or choline-supplemented diet.
View Article and Find Full Text PDFCholine kinase (CK) was discovered in 1953. Progress in understanding the function of CK was slow until its purification in 1984. The subsequent cloning and expression of the cDNA led to the description of the gene structures.
View Article and Find Full Text PDFCholine kinase in mammals is encoded by two genes, Chka and Chkb. Disruption of murine Chka leads to embryonic lethality, whereas a spontaneous genomic deletion in murine Chkb results in neonatal forelimb bone deformity and hindlimb muscular dystrophy. Surprisingly, muscular dystrophy isn't significantly developed in the forelimb.
View Article and Find Full Text PDFCholine kinase in mice is encoded by two genes, Chka and Chkb. Disruption of murine Chka leads to embryonic lethality, whereas a spontaneously occurring genomic deletion in murine Chkb results in neonatal bone deformity and hindlimb muscular dystrophy. We have investigated the mechanism by which a lack of choline kinase beta, encoded by Chkb, causes hindlimb muscular dystrophy.
View Article and Find Full Text PDFCholine kinase alpha (CK-alpha) is one of two mammalian enzymes that catalyze the phosphorylation of choline to phosphocholine in the biosynthesis of the major membrane phospholipid, phosphatidylcholine. We created mice lacking CK-alpha with an embryonic stem cell line containing an insertional mutation in the gene for CK-alpha (Chka). Embryos homozygous for the mutant Chka allele were recovered at the blastocyst stage, but not at embryonic day 7.
View Article and Find Full Text PDFThe enzyme lipoprotein lipase (LPL) releases fatty acids from lipoprotein triglycerides for use in cell metabolism. LPL activity is rapidly modulated in a tissue-specific manner. Recent studies have shown that in rat adipose tissue this occurs by a shift of extracellular LPL toward an inactive form catalyzed by an LPL-controlling protein whose expression changes in response to the nutritional state.
View Article and Find Full Text PDFThe active form of lipoprotein lipase (LPL) is a noncovalent homodimer of 55-kDa subunits. The dimer is unstable and tends to undergo irreversible dissociation into inactive monomers. We noted that a preparation of such monomers slowly regained traces of activity under assay conditions with substrate, heparin, and serum or in cell culture medium containing serum.
View Article and Find Full Text PDFBackground: Recent studies in vivo indicate that short-term regulation of lipoprotein lipase (LPL) in rat adipose tissue is post-translational and occurs by a shift of the lipase protein towards an inactive form under the influence of another gene with short-lived message and product. It has not been possible to reproduce this process with isolated adipocytes suggesting that other cells are needed, and perhaps mediate the regulation. The objective of the present study was, therefore, to explore if explants of adipose tissue could be used for studies of the regulatory process.
View Article and Find Full Text PDFAm J Physiol Renal Physiol
December 2004
Much evidence points to a relationship among kidney disease, lipoprotein metabolism, and the enzyme lipoprotein lipase (LPL), but there is little information on LPL in the kidney. The range of LPL activity in the kidney in five species differed by >500-fold. The highest activity was in mink, followed by mice, Chinese hamsters, and rats, whereas the activity was low in guinea pigs.
View Article and Find Full Text PDFWhen food was removed from young rats in the early morning, adipose tissue tumor necrosis factor (TNF)-alpha activity increased 50% and lipoprotein lipase (LPL) activity decreased 70% in 6 h. There was a strong negative correlation between the TNF-alpha and LPL activities. Exogenous TNF-alpha further decreased LPL activity.
View Article and Find Full Text PDFTissue-specific regulation of lipoprotein lipase (LPL) has been extensively studied in rats. The mouse is now the most used animal in lipoprotein research, and we have therefore explored the regulation of LPL in this species. In C57 black mice, fed ad libitum adipose tissue LPL activity changed about three-fold with the time of day, indicating a circadian rhythm.
View Article and Find Full Text PDFLipoprotein lipase (LPL) is a non-covalent, homodimeric, N-glycosylated enzyme important for metabolism of blood lipids. LPL is regulated by yet unknown post-translational events affecting the levels of active dimers. On co-expression of LPL with human molecular chaperones, we found that calreticulin had the most pronounced effects on LPL activity, but calnexin was also effective.
View Article and Find Full Text PDFLipoprotein lipase (LPL) acts at the vascular endothelium. Earlier studies have shown that down-regulation of adipose tissue LPL during fasting is post-translational and involves a shift from active to inactive forms of the lipase. Studies in cell systems had indicated that during fasting LPL might be retained in the endoplasmic reticulum.
View Article and Find Full Text PDFDuring short term fasting, lipoprotein lipase (LPL) activity in rat adipose tissue is rapidly down-regulated. This down-regulation occurs on a posttranslational level; it is not accompanied by changes in LPL mRNA or protein levels. The LPL activity can be restored within 4 h by refeeding.
View Article and Find Full Text PDF