Isolated vacuoles from the yeast Saccharomyces cerevisiae were examined in the whole-vacuole mode of patch recording, to get a detailed functional description of the vacuolar proton pump, the V-ATPase. Functioning of the V-ATPase was characterized by its current-voltage (I-V) relationship, obtained for various levels of vacuolar and cytosolic pH. I-V curves for the V-ATPase were computed as the difference between I-V curves obtained with the pump switched on (ATP, ADP, and Pi present) or off (no ATP). These difference current-voltage relationships usually crossed the voltage axis within the experimental range (from -80 to +80 mV), thus measuring the reversal voltage (ER) for the V-ATPase, which could be compared with the standing ion gradients and free energy of ATP hydrolysis, to calculate the apparent pump stoichiometry or coupling ratio: the number of protons transported for each ATP molecule hydrolyzed. This ratio was found to depend strongly upon the pH difference (DeltapH) across the vacuolar membrane, being approximately 2H+/ATP at high DeltapH (4 pH units) and increasing to >4H+/ATP for small or zero DeltapH. That result is in quantitative agreement with previous determinations on plant vacuoles. Considerations of purely electrical behavior, together with the physical properties of a recent detailed structural model for V-ATPases, led to a linear equivalent circuit--which quantitatively accounts for all observations of variable coupling ratios in fungal and plant V-ATPases by variations of the conductance for bona fide proton pumping (GP) through the ATPase relative to independent proton shunting (GS) through the same protein.
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http://dx.doi.org/10.1016/S0006-3495(03)74789-4 | DOI Listing |
Plant Cell Rep
December 2024
Institute of Nanfan & Seed Industry, Guangdong Academy of Sciences, Guangzhou, 510000, Guangdong, China.
A total of 24 genes of vacuolar H-translocating pyrophosphatases H-PPases (VPP) genes were identified in Saccharum spontaneum AP85-441 and the ScVPP1-overexpressed Arabidopsis plants conferred salt tolerance. The vital role of vacuolar H-translocating pyrophosphatases H-PPases (VPP) genes involved in plants in response to abiotic stresses. However, the understanding of VPP functions in sugarcane remained unclear.
View Article and Find Full Text PDFPatient Prefer Adherence
December 2024
CIBER of Epidemiology and Public Health, CIBERESP, Madrid, Spain.
Purpose: Proton-pump inhibitor (PPI) therapy stands as the primary treatment for upper gastrointestinal symptoms, yet poor adherence often results in treatment failure. Given that patients experiencing these symptoms frequently seek assistance at community pharmacies, the development of collaborative tools with primary care is becoming imperative. The objective was to assess the effectiveness of a pharmaceutical intervention, as demonstrated by a collaborative model between primary care and community pharmacies, in enhancing adherence to PPI among patients experiencing upper gastrointestinal symptoms.
View Article and Find Full Text PDFJGH Open
December 2024
Division of Gastroenterology and Hepatology, Rajavithi Hospital, College of Medicine Rangsit University Bangkok Thailand.
Background: A proportion of patients with functional dyspepsia (FD) have inadequate symptom control with proton pump inhibitors (PPIs) treatment. Vonoprazan demonstrates higher efficacy in acid reduction than PPI; however, the existing efficacy data for vonoprazan in treating PPI-refractory FD is limited.
Methods: This double-blinded, randomized controlled trial study was conducted at Rajavithi Hospital, Bangkok between December 2022 and 2023.
Vonoprazan is a novel acid blocker with greater potency than proton pump inhibitors. A Japanese study reported no significant safety concerns over 5 years of Vonoprazan use; however, elevated serum gastrin and increased parietal cell and foveolar hyperplasia were observed, and long-term safety data beyond 5 years are limited. We report a case that used Vonoprazan for 6 years, complicated by significant gastric epithelial changes during treatment and acute duodenal mucosal lesions following its discontinuation.
View Article and Find Full Text PDFProc (Bayl Univ Med Cent)
November 2024
Division of Gastroenterology and Hepatology, Case Western Reserve University, Cleveland, Ohio, USA.
Introduction: There is a paucity of information regarding providers' attitudes toward gastric-protective strategies with concurrent use of nonsteroidal anti-inflammatory drugs (NSAIDs). We aimed to assess gastric-protective strategies used upon prescribing NSAIDs and providers' awareness of societal guidelines for preventing NSAID-induced gastric complications.
Methods: A standardized 10-item questionnaire was sent to all orthopedic providers in North Carolina and South Carolina.
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