Malonyl-CoA Accumulation as a Compensatory Cytoprotective Mechanism in Cardiac Cells in Response to 7-Ketocholesterol-Induced Growth Retardation.

The major oxidized product of cholesterol, 7-Ketocholesterol (7KCh), causes cellular oxidative damage. In the present study, we investigated the physiological responses of cardiomyocytes to 7KCh. A 7KCh treatment inhibited the growth of cardiac cells and their mitochondrial oxygen consumption. It was accompanied by a compensatory increase in mitochondrial mass and adaptive metabolic remodeling. The application of [U-13C] glucose labeling revealed an increased production of malonyl-CoA but a decreased formation of hydroxymethylglutaryl-coenzyme A (HMG-CoA) in the 7KCh-treated cells. The flux of the tricarboxylic acid (TCA) cycle decreased, while that of anaplerotic reaction increased, suggesting a net conversion of pyruvate to malonyl-CoA. The accumulation of malonyl-CoA inhibited the carnitine palmitoyltransferase-1 (CPT-1) activity, probably accounting for the 7-KCh-induced suppression of ß-oxidation. We further examined the physiological roles of malonyl-CoA accumulation. Treatment with the inhibitor of malonyl-CoA decarboxylase, which increased the intracellular malonyl-CoA level, mitigated the growth inhibitory effect of 7KCh, whereas the treatment with the inhibitor of acetyl-CoA carboxylase, which reduced malonyl-CoA content, aggravated such a growth inhibitory effect. Knockout of malonyl-CoA decarboxylase gene (Mlycd-/-) alleviated the growth inhibitory effect of 7KCh. It was accompanied by improvement of the mitochondrial functions. These findings suggest that the formation of malonyl-CoA may represent a compensatory cytoprotective mechanism to sustain the growth of 7KCh-treated cells.

Effects of plant density on the aboveground dry matter and radiation-use efficiency of field corn.

The amount of solar radiation intercepted by the plant canopy drives crop plant photosynthesis and the formation and development of plant organs. Radiation-use efficiency (RUE) is an index used to quantify the relationship between solar radiation and biomass, and crop yield can be increased by increasing RUE. The main goals of this study were to initially investigate the effects of plant densities on the aboveground dry matter of corn, and subsequently examine the effects of plant densities on RUE and leaf area index (LAI), and the effects of LAI on RUE. Finally, we provide a comparative assessment of the approaches used to determine RUE. Analyses were conducted using growth and meteorological data obtained for two field corn varieties (TNG1 and TNG7) grown under four different plant density conditions in central Taiwan in 2017. The RUE values obtained in this study were primarily estimated from the slope of the linear relationship between aboveground dry matter measured at periodic harvests and the corresponding cumulative intercepted photosynthetically active radiation up to the time of harvest. TNG1 and TNG7 with a row spacing of 37.5 cm × 20 cm had the largest amounts of aboveground dry matter and highest RUE values of 4.41 and 4.55 g MJ-1, respectively. We established that the higher the plant density, the higher were the values obtained for RUE and LAI. We also compared the different methods of estimating RUE and make recommendations in this regard. Our findings in this study will enable farmers to gain information on the dynamics of crop yield variation at an early stage of growth, and also provide reference values that can be incorporated in future crop yield models.

W-band circular TM11 mode converter for gyrotrons.

This work proposes a methodology to convert a rectangular TE10 mode to a circular TM11 mode using an H-plane power divider at W-band. The divider evenly splits the input signal into two parts with the same amplitude and phase. One of the waves then goes through a wider rectangular waveguide with a lower cutoff frequency. After propagating through a specific length, the two waves differ by 180°. The two out-of-phase waves can jointly synthesize the circular TM11 mode with high mode purity. This power divider is structurally simple and capable of high-power operation. The full-wave simulation shows that the metal's conductivity affects the transmission of two-mode converters joined back-to-back. The measured back-to-back transmission agrees with the simulation result except for minor quantitative differences. The measured 3-dB bandwidth is 2.8 GHz with a center frequency of 93.6 GHz, which warrants the success of the TM11 mode gyrotrons.

Erythropoietin produced by genetic-modified NIH/3T3 fibroblasts enhances the survival of degenerating neurons.

BACKGROUND: Erythropoietin (EPO) has potent neuroprotective effects. The short-term delivery of high-dose EPO seemed to improve patients' neuromuscular functions; however, excessive EPO resulted in systematically high hematocrit and thrombotic risk. In our study, we established a cellular material for future in vivo studies of neurodegenerative diseases based on EPO provided regionally at a nontoxic level. METHODS: A mouse EPO cDNA was subcloned into the pCMS-EGFP vector and transfected into NIH/3T3 fibroblasts to design a biological provider that can regionally release EPO for the treatment of neurological diseases. After G418 selection, a stable EPO-overexpressing cell line, EPO-3T3-EGFP, was established. To further confirm the neuroprotective abilities of secreted EPO from EPO-3T3-EGFP cells, a cell model of neurodegeneration, PC12-INT-EGFP, was applied. RESULTS: The expression level of EPO was highly elevated in EPO-3T3-EGFP cells, and an abundant amount of EPO secreted from EPO-3T3-EGFP cells was detected in the extracellular milieu. After supplementation with conditioned medium prepared from EPO-3T3-EGFP cells, the survival rate of PC12-INT-EGFP cells was significantly enhanced. Surprisingly, a fraction of aggregated cytoskeletal EGFP-tagged α-internexin in PC12-INT-EGFP cells was disaggregated and transported into neurites dynamically. The immunocytochemical distribution of IF proteins, including NF-M, phosphorylated-NF-M, and the α-INT-EGFP fusion protein, were less aggregated in the perikaryal region and transported into neurites after the EPO treatment. CONCLUSION: The established EPO-overexpressing NIH/3T3 cell line, EPO-3T3-EGFP, may provide a material for future studies of cell-based therapies for neurodegenerative diseases via the secretion of EPO on a short-term, high-dose, regional basis.

Association between abnormal liver function and risk factors for metabolic syndrome among freshmen.

PURPOSE: The aim of this study was to investigate the prevalence of obesity and metabolic syndrome among freshmen and to find the association between abnormal liver function and risk factors for metabolic syndrome in Taiwan. METHODS: A total of 515 freshmen who were less than 22 years of age and negative for hepatitis B surface antigen marker from one general university in North Taiwan participated in this study during their school entry health examination in September 2004. Demographic characteristics, body height, body weight, biochemistry values such as alanine aminotransferase, and risk factors for metabolic syndrome such as blood pressure, fasting blood sugar, high-density lipoprotein cholesterol, triglycerides, and waist circumference were recorded for statistical analysis. Subjects with elevated serum alanine aminotransferase levels were considered to have abnormal liver function. RESULTS: The prevalence of overweight, obesity, and metabolic syndrome among freshmen in Taiwan was 18.5%, 6.0% and 1.4%, respectively. The prevalence of abnormal liver function test was 6.2%. In multivariate logistic regression analyses, patients of metabolic syndrome were 94.5 times more likely (95% confidence interval [CI] = 10.5-852.5) to be associated with abnormal liver function after adjusting for gender and age. Among the risk factors for metabolic syndrome, enlarged waist circumference (adjusted odds ratio [OR] = 10.1, 95% CI = 4.3-23.8), and elevated triglyceride (adjusted OR = 6.1, 95% CI = 1.6-23.5) were found to be statistically significantly associated with abnormal liver function. CONCLUSIONS: Central obesity and elevated triglyceride level were the two risk factors for metabolic syndrome associated with abnormal liver function among freshmen in Taiwan.