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Background/Aims: Trafficking, brush border membrane (BBM) retention, and signal-specific regulation of the Na+/H+ exchanger NHE3 is regulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adaptor proteins, which enable the formation of multiprotein complexes. It is unclear, however, what determines signal specificity of these NHERFs. Thus, we studied the association of NHE3, NHERF1 (EBP50), NHERF2 (E3KARP), and NHERF3 (PDZK1) with lipid rafts in murine small intestinal BBM. Methods: Detergent resistant membranes ('lipid rafts') were isolated by floatation of Triton X-incubated small intestinal BBM from a variety of knockout mouse strains in an Optiprep step gradient. Acid-activated NHE3 activity was measured fluorometrically in BCECF-loaded microdissected villi, or by assessment of CO2/HCO3- mediated increase in fluid absorption in perfused jejunal loops of anethetized mice. Results: NHE3 was found to partially associate with lipid rafts in the native BBM, and NHE3 raft association had an impact on NHE3 transport activity and regulation in vivo. NHERF1, 2 and 3 were differentially distributed to rafts and non-rafts, with NHERF2 being most raft-associated and NHERF3 entirely non-raft associated. NHERF2 expression enhanced the localization of NHE3 to membrane rafts. The use of acid sphingomyelinase-deficient mice, which have altered membrane lipid as well as lipid raft composition, allowed us to test the validity of the lipid raft concept in vivo. Conclusions: The differential association of the NHERFs with the raft-associated and the non-raft fraction of NHE3 in the brush border membrane is one component of the differential and signal-specific NHE3 regulation by the different NHERFs. © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Key points Cystic fibrosis (CF) is a lethal disease characterized by low rates of epithelial Cl− and HCO3− secretion and obstruction of the airways and gastrointestinal and reproductive organs by sticky mucus. HCO3− secretion has recently been demonstrated to be necessary for mucus hydration., The most frequent CF mutation is F508del. This mutant protein is usually degraded in the proteasome. New therapeutic strategies have been developed which deliver F508del to the plasma membrane., Utilizing transgenic F508del mutant and cystic fibrosis transmembrane conductance regulator (CFTR) knockout mice, apical membrane expression of F508del protein was found to be associated with enhanced stimulation of intestinal HCO3− secretion., The predominant molecular mechanism for enhanced F508del HCO3− stimulation appeared to be the activation of a Cl− recycling pathway, with Cl− exit via membrane-resident F508del protein and Cl− entry in exchange for HCO3− by apical Cl−/HCO3− exchange. In contrast, the predominant molecular mechanism for cAMP-activated HCO3− secretion in WT intestine appears to be HCO3− exit via CFTR itself., Abstract This study investigated whether expression of the common cystic fibrosis transmembrane conductance regulator (CFTR) mutant F508del in the apical membrane of enterocytes confers increased bicarbonate secretory capacity on the intestinal epithelium of F508del mutant mice compared to that of CFTR knockout (KO) mice. CFTR KO mice, F508del mutant mice (F508del) and wild-type (WT) littermates were bred on the FVB/N background. F508del isolated brush border membrane (BBM) contained approximately 5-10% fully glycosylated band C protein compared to WT BBM. Similarly, the forskolin (FSK)-induced, CFTR-dependent short-circuit current (Δ Isc) of F508del mucosa was approximately 5-10% of WT, whereas the HCO3− secretory response () was almost half that of WT in both duodenum and mid-colon studied in vitro and in vivo. While WT intestine retained full FSK-induced in the absence of luminal Cl−, the markedly higher than Δ Isc in F508del intestine was dependent on the presence of luminal Cl−, and was blocked by CFTR inhibitors. The Ste20-related proline-alanine-rich kinases (SPAK/OSR1), which are downstream of the with-no-lysine (K) protein kinases (WNK), were rapidly phosphorylated by FSK in WT and F508del, but significantly more slowly in CFTR KO intestine. In conclusion, the data demonstrate that low levels of F508del membrane expression in the intestine of F508del mice significantly increased FSK-induced HCO3− secretion mediated by Cl−/HCO3− exchange. However, in WT mucosa FSK elicited strong SPAK/OSR1 phosphorylation and Cl−-independent HCO3− efflux. This suggests that therapeutic strategies which deliver F508del to the apical membrane have the potential to significantly enhance epithelial HCO3− secretion. [ABSTRACT FROM AUTHOR]

An abstract of the article "cGMP-dependent kinase 2, Na+/H+ regulatory factor 2, and Na+/H+ exchanger isoform 3 assemble within lipid rafts in murine small intestinal brush border membrane," by Min Luo and colleagues is presented.

Purpose: Benzalkonium chloride (BAK) is a commonly used preservative to maintain sterility for multiuse eye drops such as latanoprost. One option to minimize the deleterious effects of BAK in eye drops may be to reduce the volume administered. The aim of this study was to assess the response of cells from the ocular surface to latanoprost+BAK administered by the Optejet technology, which dispenses a microdose (∼8 µL) ophthalmical spray. Methods: Cultured human conjunctival epithelial cells were exposed to the following treatments: (1) no treatment, (2) drop form of latanoprost without BAK (∼35 µL), (3) drop form of latanoprost with 0.01% BAK (∼35 µL), (4) ophthalmical spray form of latanoprost with 0.01% BAK delivered by the Optejet technology (∼8 µL). After 5 h, cells were assessed for changes in cytotoxicity, morphology, and inflammatory marker expression. Results: Latanoprost+BAK delivered by a drop induced cytotoxicity, cytoplasmic shrinkage, and loss of cell-cell contact, and expression of chemokine (C-C motif) ligand 2 and interleukin-6. In contrast, latanoprost+BAK delivered by the Optejet technology was both well tolerated and similar to no treatment controls and BAK-free latanoprost treatment. Conclusions: A microdose of latanoprost+BAK ophthalmical spray administered with the Optejet technology prevented the cytotoxicity associated with larger volumes found in eye drops. Precision dosing by the Optejet technology has the potential to decrease ocular surface disorder typically associated with eye drops containing preservatives.

In the context of active, advanced malignancies, the recommendation for invasive cardiac interventions is grounded primarily in evidence from trials focused on specific cardiovascular conditions. However, the inclusion of individuals with advanced malignancies in these trials has historically been limited, and the intricate interplay between cancer and cardiovascular disease poses unique challenges for treatment decisions. In this comprehensive review, we delve into the complex landscape of invasive cardiac interventions and their applicability in patients with active, advanced cancer. Our analysis encompasses a range of cardiovascular scenarios, including ST-segment elevation myocardial infarction, non-ST-segment elevation acute coronary syndromes, multivessel coronary disease, severe symptomatic aortic stenosis, and cardiomyopathy. We critically examine the available data and evidence, shedding light on the benefits and potential risks associated with invasive cardiac procedures in the presence of advanced malignancies. Acknowledging the competing risk of mortality posed by advanced cancers, we delve into the contemporary survival expectations for patients across various types of active, advanced malignancies. By synthesizing current literature and exploring cardiovascular interventions within these populations, we aim to establish a well-informed framework. Our ultimate goal is to provide clinicians with a rational guide for making nuanced clinical recommendations regarding the utilization of invasive cardiac interventions in the challenging context of active, advanced cancer., Competing Interests: Conflict of interest: The authors declare no conflict of interest., (© 2024 Greater Baltimore Medical Center.)

Background/aims: Trafficking, brush border membrane (BBM) retention, and signal-specific regulation of the Na+/H+ exchanger NHE3 is regulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adaptor proteins, which enable the formation of multiprotein complexes. It is unclear, however, what determines signal specificity of these NHERFs. Thus, we studied the association of NHE3, NHERF1 (EBP50), NHERF2 (E3KARP), and NHERF3 (PDZK1) with lipid rafts in murine small intestinal BBM., Methods: Detergent resistant membranes ("lipid rafts") were isolated by floatation of Triton X-incubated small intestinal BBM from a variety of knockout mouse strains in an Optiprep step gradient. Acid-activated NHE3 activity was measured fluorometrically in BCECF-loaded microdissected villi, or by assessment of CO2/HCO3(-) mediated increase in fluid absorption in perfused jejunal loops of anethetized mice., Results: NHE3 was found to partially associate with lipid rafts in the native BBM, and NHE3 raft association had an impact on NHE3 transport activity and regulation in vivo. NHERF1, 2 and 3 were differentially distributed to rafts and non-rafts, with NHERF2 being most raft-associated and NHERF3 entirely non-raft associated. NHERF2 expression enhanced the localization of NHE3 to membrane rafts. The use of acid sphingomyelinase-deficient mice, which have altered membrane lipid as well as lipid raft composition, allowed us to test the validity of the lipid raft concept in vivo., Conclusions: The differential association of the NHERFs with the raft-associated and the non-raft fraction of NHE3 in the brush border membrane is one component of the differential and signal-specific NHE3 regulation by the different NHERFs., (© 2013 S. Karger AG, Basel.)

In the title compound, C(10)H(9)IO, the asymmetric unit contains two mol-ecules, in which the iodo-bearing six-membered rings adopt envelope conformations [displacements of the flap atoms = 0.419 (3) and 0.431 (3) Å]. In both mol-ecules, the I atoms are disordered over two set of sites in 0.54 (4):0.46 (4) and 0.71 (3):0.29 (3) ratios. In the crystal, the packing features a weak C-H⋯π inter-action.