O-band DFB laser heterogeneously integrated on a bulk-silicon platform.

An O-band DFB laser heterogeneously integrated on bulk-silicon platform is presented. A high wall plug efficiency of over 8% up to 70°C is achieved due to efficient heat dissipation from III/V active region to silicon platform. The single-mode operation is maintained in a wide current range with side-mode suppression ratio over 45dB. This result completes the optical device library suite for the bulk-silicon platform used in most semiconductor products.

The aqueous fraction of Castanea crenata inner shell extract reduces obesity and intramuscular lipid accumulation via induction of mitochondrial respiration and fatty acid oxidation in muscle.

BACKGROUND: Skeletal muscle is responsible for free fatty acid (FFA) disposal via mitochondrial respiration and fatty acid oxidation (FAO). Obesity triggers high levels of circulating FFAs, which can cause intramuscular lipid (IMCL) deposition. Diverse phytochemicals, including crude Castanea crenata inner shell extract (CCE), have been shown to possess an anti-obesity effect. PURPOSE: We aimed to demonstrate whether the aqueous fraction of CCE (ACCE) provides an anti-obesity effect with a decrease in plasma FFAs and reduces IMCL. METHODS: High-fat-fed C57BL/6 mice received ACCE via water intake. A204 cells incubated with fatty acids were treated with ACCE. Lipid accumulation and mitochondrial metabolism were assessed using histological and molecular techniques. RESULTS: ACCE possessed a notably higher gallic acid content than CCE among the constituents. ACCE-administered mice exhibited reduced plasma FFA levels, adiposity, and IMCL. Muscle lipotoxicity was suppressed, including apoptosis, ER stress, and inflammation. The anti-lipid effect of ACCE was observed with the induction of mitochondrial respiration and fatty acid oxidation in muscle. CONCLUSIONS: ACCE increases mitochondrial respiration and FAO in skeletal muscle and protects muscle from IMCL and lipotoxicity, reducing plasma FFA and adiposity.

Progesterone receptor membrane component 1 reduces cardiac steatosis and lipotoxicity via activation of fatty acid oxidation and mitochondrial respiration.

Obesity is implicated in cardiovascular disease and heart failure. When fatty acids are transported to and not adequately oxidized in cardiac cells, they accumulate, causing lipotoxicity in the heart. Since hepatic progesterone receptor membrane component 1 (Pgrmc1) suppressed de novo lipogenesis in a previous study, it was questioned whether cardiac Pgrmc1 protects against lipotoxicity. Hence, we focused on the role of cardiac Pgrmc1 in basal (Resting), glucose-dominant (Refed) and lipid-dominant high-fat diet (HFD) conditions. Pgrmc1 KO mice showed high FFA levels and low glucose levels compared to wild-type (WT) mice. Pgrmc1 KO mice presented low number of mitochondrial DNA copies in heart, and it was concomitantly observed with low expression of TCA cycle genes and oxidative phosphorylation genes. Pgrmc1 absence in heart presented low fatty acid oxidation activity in all conditions, but the production of acetyl-CoA and ATP was in pronounced suppression only in HFD condition. Furthermore, HFD Pgrmc1 KO mice resulted in high cardiac fatty acyl-CoA levels and TG level. Accordingly, HFD Pgrmc1 KO mice were prone to cardiac lipotoxicity, featuring high levels in markers of inflammation, endoplasmic reticulum stress, oxidative stress, fibrosis, and heart failure. In vitro study, it was also confirmed that Pgrmc1 enhances rates of mitochondrial respiration and fatty acid oxidation. This study is clinically important because mitochondrial defects in Pgrmc1 KO mice hearts represent the late phase of cardiac failure.

Parathyroid hormone activates TRPV5 via PKA-dependent phosphorylation.

Low extracellular calcium (Ca(2+)) promotes release of parathyroid hormone (PTH), which acts on multiple organs to maintain overall Ca(2+) balance. In the distal part of the nephron, PTH stimulates active Ca(2+) reabsorption via the adenylyl cyclase-cAMP-protein kinase A (PKA) pathway, but the molecular target of this pathway is unknown. The transient receptor potential vanilloid 5 (TRPV5) channel constitutes the luminal gate for Ca(2+) entry in the distal convoluted tubule and has several putative PKA phosphorylation sites. Here, we investigated the effect of PTH-induced cAMP signaling on TRPV5 activity. Using fluorescence resonance energy transfer, we studied cAMP and Ca(2+) dynamics during PTH stimulation of HEK293 cells that coexpressed the PTH receptor and TRPV5. PTH increased cAMP levels, followed by a rise in TRPV5-mediated Ca(2+) influx. PTH (1 to 31) and forskolin, which activate the cAMP pathway, mimicked the stimulation of TRPV5 activity. Remarkably, TRPV5 activation was limited to conditions of strong intracellular Ca(2+) buffering. Cell surface biotinylation studies demonstrated that forskolin did not affect TRPV5 expression on the cell surface, suggesting that it alters the single-channel activity of a fixed number of TRPV5 channels. Application of the PKA catalytic subunit, which phosphorylated TRPV5, directly increased TRPV5 channel open probability. Alanine substitution of threonine-709 abolished both in vitro phosphorylation and PTH-mediated stimulation of TRPV5. In summary, PTH activates the cAMP-PKA signaling cascade, which rapidly phosphorylates threonine-709 of TRPV5, increasing the channel's open probability and promoting Ca(2+) reabsorption in the distal nephron.

Progesterone increases blood glucose via hepatic progesterone receptor membrane component 1 under limited or impaired action of insulin.

Hepatic gluconeogenesis is the main pathway for blood glucose maintenance activated during fasting. Retardation of insulin action, such as in diabetes mellitus, activates gluconeogenesis during the fed state. While the role of progesterone (P4) in diabetes is controversial, the P4 receptor, progesterone receptor membrane component 1 (PGRMC1), is known to stimulate pancreatic insulin secretion. We investigated the role of P4, via hepatic PGRMC1, during gluconeogenesis. The PGRMC1 binding chemical, AG-205, induced PGRMC1 monomer (25 kDa) abundance, and increased PEPCK expression and glucose production in parallel with cyclic AMP (cAMP) induction in Hep3B cells. PGRMC1-mediated cyclic AMP was inhibited by an adenylate cyclase inhibitor (MDL-12,330A). PEPCK suppression in Pgrmc1 KO hepatocyte was not observed after treatment of MDL-12,330A. PGRMC1 knockdown or overexpression systems in Hep3B cells confirmed that PGRMC1 mediates PEPCK expression via phosphorylation of cAMP-response element binding protein (CREB). CREB phosphorylation and PEPCK expression in primary hepatocytes were greater than that in PGRMC1 knock-out hepatocytes. Progesterone increased PGRMC1 expression, which induced cAMP and PEPCK induction and glucose production. In vivo, P4 suppressed gluconeogenesis following plasma insulin induction under normal conditions in a mouse model. However, P4 increased blood glucose via gluconeogenesis in parallel with increases in PGRMC1 and PEPCK expression in mice in both insulin-deficient and insulin-resistant conditions. We conclude that P4 increases hepatic glucose production via PGRMC1, which may exacerbate hyperglycaemia in diabetes where insulin action is limited.

TRPV5 gene polymorphisms in renal hypercalciuria.

BACKGROUND: Kidney stone formation is a major socioeconomic problem in humans, involving pain, recurrent treatment and renal insufficiency. As most renal precipitates contain calcium as a major component, hypercalciuria is the main risk factor for renal stone formation. Different forms of hypercalciuria can be classified, which primarily arise from defects in the main organs involved in calcium homeostasis. A distinction can be made between renal, absorptive and resorptive hypercalciuria, originating from disturbed calcium handling in kidney, intestine and bone, respectively. A positive family history predisposes individuals to an increased risk of stone formation, which strongly indicates the involvement of genetic susceptibility factors. TRPV5 is the renal epithelial calcium channel that is the gatekeeper protein in active calcium reabsorption in the kidney. TRPV5 gene ablation in mice leads to severe hypercalciuria, implying that TRPV5 is an interesting candidate gene for renal hypercalciuria in humans. This study aims to identify and functionally characterize TRPV5 gene aberrations in patients with renal hypercalciuria. METHODS: The TRPV5 coding region and intron-exon boundaries were screened for gene mutations in 20 subjects displaying renal hypercalciuria after which identified non-synonymous polymorphisms were functionally characterized by patch-clamp analysis. Wild-type and TRPV5 channels including polymorphisms were transiently expressed in human embryonic kidney (HEK) 293 cells and functionally characterized by path-clamp analysis. RESULTS: Genotyping TRPV5 in renal hypercalciuria patients revealed three non-synonymous and five synonymous polymorphisms. Electrophysiological characterization of the TRPV5 mutants did not reveal significant functional changes compared to wild-type TRPV5 channel recordings. CONCLUSIONS: In this specific patient cohort, our data do not support a primary role for TRPV5 in the pathogenesis of renal hypercalciuria. However, TRPV5 cannot be excluded as a candidate gene in hypercalciuria.

Evaluation of nafamostat mesilate as an alternative anticoagulant during intermittent hemodialysis in healthy Beagle dogs.

OBJECTIVE: To evaluate nafamostat mesilate (NM) as an alternative anticoagulant agent for intermittent hemodialysis (IHD). DESIGN: Prospective randomized study. SETTING: University teaching hospital. ANIMALS: Eighteen healthy Beagle dogs. INTERVENTIONS: In group 1 (n = 6), NM was administered at a dose of 0.5 mg/kg/h during IHD for 5 hours. In group 2 (n = 6), NM was administered at a low dose of 0.25 mg/kg/h during IHD. In group 3 (n = 6), which was the control group, unfractionated heparin (UFH) was administered during IHD. The evaluated parameters included: the amount of residual blood clots in the blood chamber and arterial side of the dialyzer; the levels of hemoglobin, hematocrit, and platelets; and the prothrombin time (PT), activated partial thromboplastin time (aPTT), and activated clotting time (ACT). MEASUREMENTS AND MAIN RESULTS: Groups 1 and 2 successfully completed IHD without serious coagulation in the extracorporeal circulation. The residual blood clotting in the blood chamber and arterial side of the dialyzer did not significantly differ in groups 1 and 2 compared to group 3 (group 1 vs group 3, P = 1.000; and group 2 vs group 3, P = 1.000). No significant differences were observed between pre- and posttreatment PTs in groups 1 (P = 0.476) and 2 (P = 0.597), between pre- and posttreatment aPTTs in groups 1 (P = 0.983) and 2 (P = 0.977), and between pre- and posttreatment ACT in groups 1 (P = 0.282) and 2 (P = 0.401). In group 3, a significant elevation of ACT was observed at the posttest (P < 0.001). CONCLUSIONS: The results of this study in healthy Beagle dogs suggest that NM at 0.25 mg/kg/h may be a valid alternative to UFH for IHD. Further studies are needed in patients at high risk of bleeding.

Activation of TRPC4ß by Gαi subunit increases Ca2+ selectivity and controls neurite morphogenesis in cultured hippocampal neuron.

The ubiquitous transient receptor potential canonical (TRPC) channels function as non-selective, Ca(2+)-permeable channels. TRPC channels are activated by stimulation of Gαq-PLC-coupled receptors. Here, we report that TRPC4/TRPC5 can be activated by Gαi. We studied the essential role of Gαi subunits in TRPC4 activation and investigated changes in ion selectivity and pore dilation of the TRPC4 channel elicited by the Gαi2 subunit. Activation of TRPC4 by Gαi2 increased Ca2+ permeability and Ca2+ influx through TRPC4 channels. Co-expression of the muscarinic receptor (M2) and TRPC4 in HEK293 cells induced TRPC4-mediated Ca2+ influx. Moreover, both TRPC4ß and the TRPC4ß-Gαi2 signaling complex induced inhibition of neurite growth and arborization in cultured hippocampal neurons. Cells treated with KN-93, a CaMKII inhibitor, prevented TRPC4- and TRPC4-Gαi2(Q205L)-mediated inhibition of neurite branching and growth. These findings indicate an essential role of Gαi proteins in TRPC4 activation and extend our knowledge of the functional role of TRPC4 in hippocampal neurons.