Tyrosine kinase, phosphatidylinositol 3-kinase, and protein kinase C regulate insulin-stimulated NaCl absorption in the thick ascending limb

Tyrosine kinase, phosphatidylinositol 3-kinase, and protein kinase C regulate insulin-stimulated NaCl absorption in the thick ascending limb. We have previously shown a direct stimulatory effect of insulin on NaCl absorption in the medullary thick ascending limb of Henle's loop (mTAL). To further investigate the signal transduction involved, we determined whether tyrosine kinase, phosphatidylinositol 3-kinase (PI3-kinase), and/or protein kinase C (PKC) regulate insulin-stimulated NaCl absorption in the mTAL by in vitro microperfusion methods. In control experiments, insulin increased transepithelial voltage (Vte) and net lumen-to-bath Cl− flux (JCl). Genistein and methyl 2,5-dihydroxycinnamate, two specific tyrosine kinase inhibitors, abolished the effects of insulin. Wort-mannin, a specific PI3-kinase inhibitor, inhibited the action of insulin. The effects of insulin also were inhibited by staurosporin and calphostin C, which are dissimilar inhibitors of PKC. These results indicate that insulin stimulates NaCl absorption in the mTAL through tyrosine kinase, PI3-kinase, and PKC-mediated mechanisms. Moreover, because we have reported previously that insulin causes no detectable change in cytosolic free Ca2+ in the mTAL cells, the present results also suggest that insulin-induced PKC activation is not related to inositol 1,4,5-triphosphate (IP3) production

Dynamics of Hepatitis B Virus Quasispecies in Association with Nucleos(t)ide Analogue Treatment Determined by Ultra-Deep Sequencing

[Background and Aims]: Although the advent of ultra-deep sequencing technology allows for the analysis of heretofore-undetectable minor viral mutants, a limited amount of information is currently available regarding the clinical implications of hepatitis B virus (HBV) genomic heterogeneity. [Methods]: To characterize the HBV genetic heterogeneity in association with anti-viral therapy, we performed ultra-deep sequencing of full-genome HBV in the liver and serum of 19 patients with chronic viral infection, including 14 therapy-naïve and 5 nucleos(t)ide analogue(NA)-treated cases. [Results]: Most genomic changes observed in viral variants were single base substitutions and were widely distributed throughout the HBV genome. Four of eight (50%) chronic therapy-naïve HBeAg-negative patients showed a relatively low prevalence of the G1896A pre-core (pre-C) mutant in the liver tissues, suggesting that other mutations were involved in their HBeAg seroconversion. Interestingly, liver tissues in 4 of 5 (80%) of the chronic NA-treated anti-HBe-positive cases had extremely low levels of the G1896A pre-C mutant (0.0%, 0.0%, 0.1%, and 1.1%), suggesting the high sensitivity of the G1896A pre-C mutant to NA. Moreover, various abundances of clones resistant to NA were common in both the liver and serum of treatment-naïve patients, and the proportion of M204VI mutants resistant to lamivudine and entecavir expanded in response to entecavir treatment in the serum of 35.7% (5/14) of patients, suggesting the putative risk of developing drug resistance to NA. [Conclusion]: Our findings illustrate the strong advantage of deep sequencing on viral genome as a tool for dissecting the pathophysiology of HBV infection

Mathematical model for self-propelled droplets driven by interfacial tension

We propose a model for the spontaneous motion of a droplet induced by inhomogeneity in interfacial tension. The model is derived from a variation of the Lagrangian of the system and we use a time-discretized Morse flow scheme to perform its numerical simulations. Our model can naturally simulate the dynamics of a single droplet, as well as that of multiple droplets, where the volume of each droplet is conserved. We reproduced the ballistic motion and fission of a droplet, and the collision of two droplets was also examined numerically

Urinary neutrophil gelatinase-associated lipocalin levels reflect damage to glomeruli, proximal tubules, and distal nephrons.

Published online 1 October 2008Urinary neutrophil gelatinase-associated lipocalin (Ngal or lipocalin 2) is a very early and sensitive biomarker of kidney injury. Here we determined the origin and time course of Ngal appearance in several experimental and clinically relevant renal diseases. Urinary Ngal levels were found to be markedly increased in lipoatrophic- and streptozotocin-induced mouse models of diabetic nephropathy. In the latter mice, the angiotensin receptor blocker candesartan dramatically decreased urinary Ngal excretion. The reabsorption of Ngal by the proximal tubule was severely reduced in streptozotocin-induced diabetic mice, but upregulation of its mRNA and protein in the kidney was negligible, compared to those of control mice, suggesting that increased urinary Ngal was mainly due to impaired renal reabsorption. In the mouse model of unilateral ureteral obstruction, Ngal protein synthesis was dramatically increased in the dilated thick ascending limb of Henle and N was found in the urine present in the swollen pelvis of the ligated kidney. Five patients with nephrotic syndrome or interstitial nephritis had markedly elevated urinary Ngal levels at presentation, but these decreased in response to treatment. Our study shows that the urinary Ngal level may be useful for monitoring the status and treatment of diverse renal diseases reflecting defects in glomerular filtration barrier, proximal tubule reabsorption, and distal nephrons