Virstatin-Conjugated Gold Nanoparticle with Enhanced Antimicrobial Activity against the El Tor Biotype.

Because of the emergence of multidrug-resistant pathogenic bacteria, there is a growing interest for the development of an efficient alternative to antibiotics. Gold nanoparticles (AuNPs) are promising candidates due to their inherent non-toxicity and can be used as effective carriers of drugs. Cholera caused by Gram-negative is still a potential threat in many developing countries.

extract elicits chloride secretion by stimulation of the intestinal TMEM16A ion channel.

Context: Cucumber ( Linn. [Cucurbitaceae]) is widely known for its purgative, antidiabetic, antioxidant, and anticancer therapeutic potential. However, its effect on gastrointestinal (GI) disease is unrecognised.

The gold nanoparticle reduces Vibrio cholerae pathogenesis by inhibition of biofilm formation and disruption of the production and structure of cholera toxin.

Formation of biofilm by Vibrio cholerae plays a crucial role in pathogenesis and transmission of cholera. Lower infective dose of the biofilm form of V. cholerae compared to the planktonic counterpart, and its antibiotic resistance, make it challenging to combat cholera.

Intestinal TMEM16A control luminal chloride secretion in a NHERF1 dependent manner.

TMEM16A (Transmembrane protein 16A or Anoctamin1) is a calcium-activated chloride channel. (CaCC),that exerts critical roles in epithelial secretion. However, its localization, function, and regulation in intestinal chloride (Cl) secretion remain obscure.

Parallel intermediate conductance K and Cl channel activity mediates electroneutral K exit across basolateral membranes in rat distal colon.

Transepithelial K absorption requires apical K uptake and basolateral K exit. In the colon, apical H-K-ATPase mediates cellular K uptake, and it has been suggested that electroneutral basolateral K exit reflects K-Cl cotransporter-1 (KCC1) operating in parallel with K and Cl channels. The present study was designed to identify basolateral transporter(s) responsible for K exit in rat distal colon.

The ABCG2 Q141K hyperuricemia and gout associated variant illuminates the physiology of human urate excretion.

The pathophysiological nature of the common ABCG2 gout and hyperuricemia associated variant Q141K (rs2231142) remains undefined. Here, we use a human interventional cohort study (ACTRN12615001302549) to understand the physiological role of ABCG2 and find that participants with the Q141K ABCG2 variant display elevated serum urate, unaltered FEUA, and significant evidence of reduced extra-renal urate excretion. We explore mechanisms by generating a mouse model of the orthologous Q140K Abcg2 variant and find male mice have significant hyperuricemia and metabolic alterations, but only subtle alterations of renal urate excretion and ABCG2 abundance.

Control of Ion Transport by Tmem16a Expressed in Murine Intestine.

Cl secretion by the human and murine intestinal epithelium occurs through the cystic fibrosis transmembrane conductance regulator (cftr). However, the Ca activated Cl channel Tmem16a was shown to contribute to Cl secretion, mainly, but not exclusively, as a basolaterally located Cl channel that controls basolateral Ca signaling, and thus activation of basolateral Ca dependent Sk4 K channels. In intestinal goblet cells, Tmem16a was shown to regulated Ca signals required for exocytosis of mucus.

Structure and function of Vibrio cholerae accessory cholera enterotoxin in presence of gold nanoparticles: Dependence on morphology.

Background: Accessory cholera enterotoxin (Ace) is a classical enterotoxin produced by Vibrio cholerae, the causative agent for cholera. Considering the crucial role of Ace in pathogenesis of cholera, we explored the modulation of structure/function of Ace using gold nanoparticles (AuNPs) of different size and shape - spherical (AuNS10 and AuNS100, the number indicating the diameter in nm) and rod (AuNR10).

Methods: Biophysical techniques have been used to find out structural modulation of Ace by AuNPs.

Anoctamin 6 Contributes to Cl- Secretion in Accessory Cholera Enterotoxin (Ace)-stimulated Diarrhea: AN ESSENTIAL ROLE FOR PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE (PIP2) SIGNALING IN CHOLERA.

Accessory cholera enterotoxin (Ace) of Vibrio cholerae has been shown to contribute to diarrhea. However, the signaling mechanism and specific type of Cl channel activated by Ace are still unknown. We have shown here that the recombinant Ace protein induced I of apical plasma membrane, which was inhibited by classical CaCC blockers.

The antimicrobial activity of ZnO nanoparticles against Vibrio cholerae: Variation in response depends on biotype.

The potency of zinc oxide nanoparticles (NPs), with a core size of ~7-10nm, to inhibit cholera disease was investigated by demonstrating the effect on two biotypes (classical and El Tor) of O1 serogroup of Vibrio cholerae-El Tor was more susceptible both in planktonic and in biofilm forms. Interaction with ZnO NP results in deformed cellular architecture. Increased fluidity and depolarization of membrane, and protein leakage further confirmed the damages inflicted on Vibrio by NP.

Effects of Small Molecule Calcium-Activated Chloride Channel Inhibitors on Structure and Function of Accessory Cholera Enterotoxin (Ace) of Vibrio cholerae.

Cholera pathogenesis occurs due to synergistic pro-secretory effects of several toxins, such as cholera toxin (CTX) and Accessory cholera enterotoxin (Ace) secreted by Vibrio cholerae strains. Ace activates chloride channels stimulating chloride/bicarbonate transport that augments fluid secretion resulting in diarrhea. These channels have been targeted for drug development.

New advances in the pathophysiology of intestinal ion transport and barrier function in diarrhea and the impact on therapy.

Diarrhea remains a continuous threat to human health worldwide. Scaling up the best practices for diarrhea prevention requires improved therapies. Diarrhea results from dysregulation of normal intestinal ion transport functions.

Accessory cholera enterotoxin, Ace, from Vibrio cholerae: structure, unfolding, and virstatin binding.

Vibrio cholerae accessory cholera enterotoxin (Ace) is the third toxin, along with cholera toxin (CT) and zonula occludens toxin (Zot), that causes the endemic disease cholera. Structural characterization of Ace has been restricted because of the limited production of this toxic protein by V. cholerae.

Epac1 mediates protein kinase A-independent mechanism of forskolin-activated intestinal chloride secretion.

Intestinal Cl- secretion is stimulated by cyclic AMP (cAMP) and intracellular calcium ([Ca2+]i). Recent studies show that protein kinase A (PKA) and the exchange protein directly activated by cAMP (Epac) are downstream targets of cAMP. Therefore, we tested whether both PKA and Epac are involved in forskolin (FSK)/cAMP-stimulated Cl- secretion.

A new insight into pathophysiological mechanisms of zinc in diarrhea.

An increasing amount of data showing the beneficial use of zinc (Zn) in treating diarrhea continues to emerge from epidemiological and clinical trials. However, without a thorough understanding of physiological mechanisms of Zn, it does not support policy recommendation to advocate the therapeutic use of Zn. Our data demonstrate that Zn is a potential antidiarrheal agent that provides substantial benefit by stimulating sodium absorption and inhibiting chloride secretion in intestinal epithelial cells.

A purine-selective nucleobase/nucleoside transporter in PK15NTD cells.

Nucleoside and nucleobase transporters are important for salvage of purines and pyrimidines and for transport of their analog drugs into cells. However, the pathways for nucleobase translocation in mammalian cells are not well characterized. We identified an Na-independent purine-selective nucleobase/nucleoside transport system in the nucleoside transporter-deficient PK15NTD cells.

Zinc in the treatment of acute diarrhea: current status and assessment.

The improved treatment of acute diarrhea in children during the past 35 years has reduced its morbidity and mortality substantially. However, better therapy still is required. This article reviews the role of oral rehydration solution in the treatment of acute diarrhea with particular attention to recent efforts to develop improved oral rehydration solution formulations.

Zinc inhibits cAMP-stimulated Cl secretion via basolateral K-channel blockade in rat ileum.

Zn, an essential micronutrient and second most abundant trace element in cell and tissues, reduces stool output when administered to children with acute diarrhea. The mechanism by which Zn improves diarrhea is not known but could result from stimulating Na absorption and/or inhibiting anion secretion. The aim of this study was to investigate the direct effect of Zn on intestinal epithelial ion absorption and secretion.

Translocation of protein kinase-C with IP3-induced calcium mobilization by heat-stable enterotoxin of Vibrio cholerae non-O1 in isolated rat enterocytes.

The activity of the calcium- and phospholipid-dependent enzyme protein kinase C (PKC) in response to heat-stable enterotoxin (NAG-ST) of Vibrio cholerae non-O1 was examined in isolated rat enterocytes. Optimal stimulation of the membrane-bound PKC activity (about 4.3-fold) was observed after 1 min of incubation of cells with 10 ng/ml toxin; and the effects were dose dependent.