Local and global interpretations of a disease-causing mutation near the ligand entry path in hyperpolarization-activated cAMP-gated channel.

Hyperpolarization-activated, cAMP-gated (HCN) channels sense membrane potential and intracellular cAMP levels. A mutation identified in the cAMP binding domain (CNBD) of the human HCN4 channel, S672R, severely reduces the heart rate, but the molecular mechanism has been unclear. Our biochemical binding assays on isolated CNBD and patch-clamp recordings on the functional channel show that S672R reduces cAMP binding.

Normal-mode-analysis-guided investigation of crucial intersubunit contacts in the cAMP-dependent gating in HCN channels.

Protein structures define a complex network of atomic interactions in three dimensions. Direct visualization of the structure and analysis of the interaction potential energy are not straightforward approaches to pinpoint the atomic contacts that are crucial for protein function. We used the tetrameric hyperpolarization-activated cAMP-regulated (HCN) channel as a model system to study the intersubunit contacts in cAMP-dependent gating.

Inner activation gate in S6 contributes to the state-dependent binding of cAMP in full-length HCN2 channel.

Recently, applications of the patch-clamp fluorometry (PCF) technique in studies of cyclic nucleotide-gated (CNG) and hyperpolarization-activated, cyclic nucleotide-regulated (HCN) channels have provided direct evidence for the long-held notion that ligands preferably bind to and stabilize these channels in an open state. This state-dependent ligand-channel interaction involves contributions from not only the ligand-binding domain but also other discrete structural elements within the channel protein. This insight led us to investigate whether the pore of the HCN channel plays a role in the ligand-whole channel interaction.

Intracellular Ca(2+)- and PKC-dependent upregulation of T-type Ca(2+) channels in LPC-stimulated cardiomyocytes.

Lysophosphatidylcholine (LPC) accumulation in intracellular and/or interstitial space in cardiomyocytes may underlie as a mechanism for tachycardia and various arrhythmias during cardiac ischemia, which is usually accompanied by elevation of intracellular Ca(2+) concentration ([Ca(2+)](i)). The present study was therefore designed to investigate possible mechanisms responsible for [Ca(2+)](i) elevation by LPC focusing on T-type Ca(2+) channel current (I(Ca.T)).

Green banana reduces clinical severity of childhood shigellosis: a double-blind, randomized, controlled clinical trial.

Background And Aims: Mature green banana (GB) fruit is rich in amylase-resistant starch that stimulates colonic production of short-chain fatty acids (referred to as fatty acid) and is useful in treating diarrheal diseases. We studied therapeutic effects of GB in childhood shigellosis by determining colonic fatty acid production in a double-blind, randomized, controlled, clinical trial.

Methods: Seventy-three children aged 6 to 60 months with severe bloody dysentery caused by Shigella infection were either given a rice-based diet (54 kcal/dL), with cooked GB (250 g/L) (n = 34) or without GB (n = 39) for 5 days; all given ciprofloxacin (15 mg/kg, q12 hours).

17 beta-estradiol modulates expression of low-voltage-activated Ca(V)3.2 T-type calcium channel via extracellularly regulated kinase pathway in cardiomyocytes.

T-type Ca(2+) channel current (I(Ca,T)) plays an important role for spontaneous pacemaker activity and is involved in the progression of structural heart diseases. Estrogens are of importance for the regulation of growth and differentiation and function in a wide array of target tissues, including those in the cardiovascular system. The aim of this study was to elucidate the short-term and long-term effects of 17beta-estradiol (E(2)) on I(Ca,T) in cardiomyocytes.

Antidiarrheal effects of L-histidine-supplemented rice-based oral rehydration solution in the treatment of male adults with severe cholera in Bangladesh: a double-blind, randomized trial.

Background: Because of the antisecretory potential of L-histidine in the intestinal tract, its antidiarrheal effects were determined in cholera.

Methods: In a double-blind trial of 126 adult male patients with cholera, L-histidine (2.5 g/L) was mixed with a rice-based oral rehydration solution (ORS) and administered to 62 patients; 64 patients received the same ORS without L-histidine.

Antioxidants in detoxification of arsenic-induced oxidative injury in rabbits: preliminary results.

To assess the oxidative injuries caused by arsenic toxicity in rabbits and evaluate the detoxifying effects of exogenous antioxidants, we administered arsenic trioxide (3-5 mg/kg/day) in rabbits through a feeding tube for seven days. These rabbits were then treated with a recipe of vitamins, zinc, selenium (VZS) or a plant polyphenol or a placebo for the next seven days. Blood samples were collected from ear vein for spectrophotometric assay of reduced glutathione (GSH), thiobarbituric acid reactive substances (TBARS), and nitrite/nitrate (NOx; index of nitric oxide formation) before arsenic administration, seven days after arsenic administration, and seven days after antioxidant treatment.