Influence of glycoprotein MUC1 on trafficking of the Ca2+-selective ion channels, TRPV5 and TRPV6, and on in vivo calcium homeostasis.

Polymorphism of the gene encoding mucin 1 (MUC1) is associated with skeletal and dental phenotypes in human genomic studies. Animals lacking MUC1 exhibit mild reduction in bone density. These phenotypes could be a consequence of modulation of bodily Ca homeostasis by MUC1, as suggested by the previous observation that MUC1 enhances cell surface expression of the Ca2+-selective channel, TRPV5, in cultured unpolarized cells. Using biotinylation of cell surface proteins, we asked whether MUC1 influences endocytosis of TRPV5 and another Ca2+-selective TRP channel, TRPV6, in cultured polarized epithelial cells. Our results indicate that MUC1 reduces endocytosis of both channels, enhancing cell surface expression. Further, we found that mice lacking MUC1 lose apical localization of TRPV5 and TRPV6 in the renal tubular and duodenal epithelium. Females, but not males, lacking MUC1 exhibit reduced blood Ca2+. However, mice lacking MUC1 exhibited no differences in basal urinary Ca excretion or Ca retention in response to PTH receptor signaling, suggesting compensation by transport mechanisms independent of TRPV5 and TRPV6. Finally, humans with autosomal dominant tubulointerstitial kidney disease due to frame-shift mutation of MUC1 (ADTKD-MUC1) exhibit reduced plasma Ca concentrations compared to control individuals with mutations in the gene encoding uromodulin (ADTKD-UMOD), consistent with MUC1 haploinsufficiency causing reduced bodily Ca2+. In summary, our results provide further insight into the role of MUC1 in Ca2+-selective TRP channel endocytosis and the overall effects on Ca concentrations.

Managing Energy Consumption of Devices with Multiconnectivity by Deep Learning and Software-Defined Networking.

Multiconnectivity allows user equipment/devices to connect to multiple radio access technologies simultaneously, including 5G, 4G (LTE), and WiFi. It is a necessity in meeting the increasing demand for mobile network services for the 5G and beyond wireless networks, while ensuring that mobile operators can still reap the benefits of their present investments. Multipath TCP (MPTCP) has been introduced to allow uninterrupted reliable data transmission over multiconnectivity links. However, energy consumption is a significant issue for multihomed wireless devices since most of them are battery-powered. This paper employs software-defined networking (SDN) and deep neural networks (DNNs) to manage the energy consumption of devices with multiconnectivity running MPTCP. The proposed method involves two lightweight algorithms implemented on an SDN controller, using a real hardware testbed of dual-homed wireless nodes connected to WiFi and cellular networks. The first algorithm determines whether a node should connect to a specific network or both networks. The second algorithm improves the selection made by the first by using a DNN trained on different scenarios, such as various network sizes and MPTCP congestion control algorithms. The results of our extensive experimentation show that this approach effectively reduces energy consumption while providing better network throughput performance compared to using single-path TCP or MPTCP Cubic or BALIA for all nodes.

KIM-1-mediated anti-inflammatory activity is preserved by MUC1 induction in the proximal tubule during ischemia-reperfusion injury.

Cell-associated kidney injury molecule-1 (KIM-1) exerts an anti-inflammatory role following kidney injury by mediating efferocytosis and downregulating the NF-κB pathway. KIM-1 cleavage blunts its anti-inflammatory activities. We reported that mucin 1 (MUC1) is protective in a mouse model of ischemia-reperfusion injury (IRI). As both KIM-1 and MUC1 are induced in the proximal tubule (PT) during IRI and are a disintegrin and metalloprotease 17 (ADAM17) substrates, we tested the hypothesis that MUC1 protects KIM-1 activity. Muc1 knockout (KO) mice and wild-type (WT) littermates were subjected to IRI. KIM-1, MUC1, and ADAM17 levels (and signaling pathways) were assessed by immunoblot analysis. PT localization was assessed by confocal microscopy and an in situ proximity ligation assay. Findings were extended using human kidneys and urine as well as KIM-1-mediated efferocytosis assays in mouse PT cultures. In response to tubular injury in mouse and human kidneys, we observed induction and coexpression of KIM-1 and MUC1 in the PT. Compared with WT mice, Muc1 KO mice had higher urinary KIM-1 and lower kidney KIM-1. KIM-1 was apical in the PT of WT kidneys but predominately with luminal debris in Muc1 KO mice. Efferocytosis was reduced in Muc1 KO PT cultures compared with WT cultures, whereas inflammation was increased in Muc1 KO kidneys compared with WT kidneys. MUC1 was cleaved by ADAM17 in PT cultures and blocked KIM-1 shedding in Madin-Darby canine kidney cells. We conclude that KIM-1-mediated efferocytosis and thus anti-inflammatory activity during IRI is preserved in the injured kidney by MUC1 inhibition of KIM-1 shedding.NEW & NOTEWORTHY KIM-1 plays a key role in the recovery of the tubule epithelium during renal IRI by mediating efferocytosis and associated signaling that suppresses inflammation. Excessive cleavage of KIM-1 by ADAM17 provides a decoy receptor that aggravates efferocytosis and subsequent signaling. Our data from experiments in mice, patients, and cultured cells show that MUC1 is also induced during IRI and competes with KIM-1 for cleavage by ADAM17. Consequently, MUC1 protects KIM-1 anti-inflammatory activity in the damaged kidney.

L-WNK1 is required for BK channel activation in intercalated cells.

Large-conductance K+ (BK) channels expressed in intercalated cells (ICs) in the aldosterone-sensitive distal nephron (ASDN) mediate flow-induced K+ secretion. In the ASDN of mice and rabbits, IC BK channel expression and activity increase with a high-K+ diet. In cell culture, the long isoform of with-no-lysine kinase 1 (L-WNK1) increases BK channel expression and activity. Apical L-WNK1 expression is selectively enhanced in ICs in the ASDN of rabbits on a high-K+ diet, suggesting that L-WNK1 contributes to BK channel regulation by dietary K+. We examined the role of IC L-WNK1 expression in enhancing BK channel activity in response to a high-K+ diet. Mice with IC-selective deletion of L-WNK1 (IC-L-WNK1-KO) and littermate control mice were placed on a high-K+ (5% K+, as KCl) diet for 10 or more days. IC-L-WNK1-KO mice exhibited reduced IC apical + subapical α-subunit expression and BK channel-dependent whole cell currents compared with controls. Six-hour urinary K+ excretion in response a saline load was similar in IC-L-WNK1-KO mice and controls. The observations that IC-L-WNK1-KO mice on a high-K+ diet have higher blood K+ concentration and reduced IC BK channel activity are consistent with impaired urinary K+ secretion, demonstrating that IC L-WNK1 has a role in the renal adaptation to a high-K+ diet.NEW & NOTEWORTHY When mice are placed on a high-K+ diet, genetic disruption of the long form of with no lysine kinase 1 (L-WNK1) in intercalated cells reduced relative apical + subapical localization of the large-conductance K+ channel, blunted large-conductance K+ channel currents in intercalated cells, and increased blood K+ concentration. These data confirm an in vivo role of L-WNK1 in intercalated cells in adaptation to a high-K+ diet.

Revealing oral microbiota composition and functionality associated with heavy cigarette smoking.

BACKGROUND: Heavy tobacco smoking, a hallmark feature of lung cancer, is drastically predominant in Middle Eastern populations. The precise links between nicotine dependence and the functional contribution of the oral microbiota remain unknown in these populations. METHODS: We evaluated the composition and functional capabilities of oral microbiota with relation to cigarette smoking in 105 adults through shotgun metagenomics using buccal swabs. RESULTS: The oral microbiota composition in our study subjects was dominated by the phyla Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes, in addition to the genera Prevotella and Veillonella, similar to previously described westernized cohorts. Furthermore, the smoker's oral microbiota represented a significant abundance of Veillonella dispar, Leptotrichia spp. and Prevotella pleuritidis when compared to non-smokers. Within the smoking groups, differential relative abundance testing unveiled relative abundance of Streptobacillus hongkongensis, Fusobacterium massiliense, Prevotella bivia in high nicotine dependent compared to low nicotine dependent profiles based on Fagerström Test for Nicotine Dependence. Functional profiling showed marked differences between smokers and non-smokers. Smokers exhibited an enrichment of Tricarballylate utilization and Lactate racemization when compared to the non-smokers. According to their nicotine dependence, enrichment of Xanthosine utilization, p-Aminobenzoyl-Glutamate utilization, and multidrug efflux pump in Campylobacter jejuni biosynthesis modules were detected in the high nicotine dependent group. CONCLUSIONS: These compositional and functional differences may provide critical insight on how variations in the oral microbiota could predispose to respiratory illnesses and smoke cessation relapse in cigarette smokers. In particular, the observed enrichment of Fusobacterium and Prevotella in the oral microbiota possibly suggests an intriguing linkage to gut and lung cancers.

Altered respiratory microbiota composition and functionality associated with asthma early in life.

BACKGROUND: The microbiota of the respiratory tract has an important role in maintaining respiratory health. However, little is known on the respiratory microbiota in asthmatic patients among Middle Eastern populations. This study investigated the respiratory microbiota composition and functionality associated with asthma in Emirati subjects. METHODS: We performed 16S rRNA and ITS2-gene based microbial profiling of 40 expectorated sputum samples from adult and pediatric Emirati individuals averaging 52 and 7 years of age, respectively with or without asthma. RESULTS: We report bacterial difference belonging to Bacteroidetes, Firmicutes, Fusobacteria and Proteobacteria phyla between asthmatic and non-asthmatic controls. Similarly, fungal difference belonging to Ascomycota, Basidiomycota phyla and other unclassified fungi. Differential abundance testing among asthmatic individuals with relation to Asthma Control Test show a significant depletion of Penicillium aethiopicum and Alternaria spp., among poorly controlled asthmatics. Moreover, data suggest a significant expansion of Malassezia spp. and other unclassified fungi in the airways of those receiving steroids and leukotriene receptor antagonists' combination therapy, in contrast to those receiving steroids alone. Functional profiling from 16S data showed marked differences between pediatric asthmatic and non-asthmatic controls, with pediatric asthmatic patients showing an increase in amino acid (p-value < 5.03 × 10- 7), carbohydrate (p-value < 4.76 × 10- 7), and fatty acid degradation (p-value < 6.65 × 10- 7) pathways, whereas non-asthmatic controls are associated with increase in amino acid (p-value < 8.34 × 10- 7), carbohydrate (p-value < 3.65 × 10- 7), and fatty acid (p-value < 2.18 × 10- 6) biosynthesis pathways in concordance with enterotype composition. CONCLUSIONS: These differences provide an insight into respiratory microbiota composition in Emirati population and its possible role in the development of asthma early in life. This study provides important information that may eventually lead to the development of screening biomarkers to predict early asthma development and novel therapeutic approaches.

Preferred teaching styles of medical faculty: an international multi-center study.

BACKGROUND: In the current wave of educational reforms, understanding teaching styles of medical faculty can help modify instructional strategies for effective teaching. Few studies have probed distinctive teaching styles of medical faculty. We compared preferred teaching styles of faculty from seven medical schools in United Arab Emirates, the Netherlands, Saudi Arabia, Malaysia, Pakistan, and Sudan. METHODS: The validated Grasha-Riechmann teaching style inventory was administered online for data collection and used SPSS version 20.0 for statistical analysis. RESULTS: Of the 460 invitees, 248 responded (response rate; 54%). Delegator teaching style was most common with a highest median and mean of 2.38 and 2.45, respectively. There was a significant correlation between expert and authority teaching styles, correlation coefficient 0.62. Similarly, we found a significant correlation between authority teaching style and nature of curriculum, correlation coefficient 0.30. Multiple regression analysis showed that only authority teaching style and male gender had significant correlation. Interestingly, 117 (47%) teachers disagreed with the teaching philosophy of delivering course contents by strictly following learning outcomes. Female teachers (114/248) were more willing to negotiate with their students regarding how and what to teach in their course, while male teachers tended to allow more autonomy by allowing students to set their learning agenda. CONCLUSIONS: This study showed that the medical teachers preferred delegator teacher style that promotes students' collaboration and peer-to-peer learning. Most teachers are conscious of their teaching styles to motivate students for scientific curiosity. These findings can help medical educators to modify their teaching styles for effective learning.

Expression and distribution of PIEZO1 in the mouse urinary tract.

The proper function of the organs that make up the urinary tract (kidneys, ureters, bladder, and urethra) depends on their ability to sense and respond to mechanical forces, including shear stress and wall tension. However, we have limited understanding of the mechanosensors that function in these organs and the tissue sites in which these molecules are expressed. Possible candidates include stretch-activated PIEZO channels (PIEZO1 and PIEZO2), which have been implicated in mechanically regulated body functions including touch sensation, proprioception, lung inflation, and blood pressure regulation. Using reporter mice expressing a COOH-terminal fusion of Piezo1 with the sequence for the tandem-dimer Tomato gene, we found that PIEZO1 is expressed in the kidneys, ureters, bladder, and urethra as well as organs in close proximity, including the prostate, seminal vesicles and ducts, ejaculatory ducts, and the vagina. We further found that PIEZO1 expression is not limited to one cell type; it is observed in the endothelial and parietal cells of the renal corpuscle, the basolateral surfaces of many of the epithelial cells that line the urinary tract, the interstitial cells of the bladder and ureters, and populations of smooth and striated muscle cells. We propose that in the urinary tract, PIEZO1 likely functions as a mechanosensor that triggers responses to wall tension.

Novel roles for mucin 1 in the kidney.

PURPOSE OF REVIEW: Recent studies in the kidney have revealed that the well characterized tumor antigen mucin 1 (MUC1/Muc1) also has numerous functions in the normal and injured kidney. RECENT FINDINGS: Mucin 1 is a transmembrane mucin with a robust glycan-dependent apical targeting signal and efficient recycling from endosomes. It was recently reported that the TRPV5 calcium channel is stabilized on the cell surface by galectin-dependent cross-linking to mucin 1, providing a novel mechanism for regulation of ion channels and normal electrolyte balance.Our recent studies in mice show that Muc 1 is induced after ischemia, stabilizing hypoxia-inducible factor 1 (HIF-1)α and ß-catenin levels, and transactivating the HIF-1 and ß-catenin protective pathways. However, prolonged induction of either pathway in the injured kidney can proceed from apparent full recovery to chronic kidney disease. A very recent report indicates that aberrant activation of mucin 1 signaling after ischemic injury in mice and humans is associated with development of chronic kidney disease and fibrosis. A frameshift mutation in MUC1 was recently identified as the genetic lesion causing medullary cystic kidney disease type 1, now appropriately renamed MUC1 Kidney Disease. SUMMARY: Studies of mucin 1 in the kidney now reveal significant functions for the extracellular mucin-like domain and signaling through the cytoplasmic tail.

Aurora kinase A activates the vacuolar H+-ATPase (V-ATPase) in kidney carcinoma cells.

Extracellular proton-secreting transport systems that contribute to extracellular pH include the vacuolar H(+)-ATPase (V-ATPase). This pump, which mediates ATP-driven transport of H(+) across membranes, is involved in metastasis. We previously showed (Alzamora R, Thali RF, Gong F, Smolak C, Li H, Baty CJ, Bertrand CA, Auchli Y, Brunisholz RA, Neumann D, Hallows KR, Pastor-Soler NM. J Biol Chem 285: 24676-24685, 2010) that V-ATPase A subunit phosphorylation at Ser-175 is important for PKA-induced V-ATPase activity at the membrane of kidney intercalated cells. However, Ser-175 is also located within a larger phosphorylation consensus sequence for Aurora kinases, which are known to phosphorylate proteins that contribute to the pathogenesis of metastatic carcinomas. We thus hypothesized that Aurora kinase A (AURKA), overexpressed in aggressive carcinomas, regulates the V-ATPase in human kidney carcinoma cells (Caki-2) via Ser-175 phosphorylation. We found that AURKA is abnormally expressed in Caki-2 cells, where it binds the V-ATPase A subunit in an AURKA phosphorylation-dependent manner. Treatment with the AURKA activator anacardic acid increased V-ATPase expression and activity at the plasma membrane of Caki-2 cells. In addition, AURKA phosphorylates the V-ATPase A subunit at Ser-175 in vitro and in Caki-2 cells. Immunolabeling revealed that anacardic acid induced marked membrane accumulation of the V-ATPase A subunit in transfected Caki-2 cells. However, anacardic acid failed to induce membrane accumulation of a phosphorylation-deficient Ser-175-to-Ala (S175A) A subunit mutant. Finally, S175A-expressing cells had decreased migration in a wound-healing assay compared with cells expressing wild-type or a phospho-mimetic Ser-175-to-Asp (S175D) mutant A subunit. We conclude that AURKA activates the V-ATPase in kidney carcinoma cells via phosphorylation of Ser-175 in the V-ATPase A subunit. This regulation contributes to kidney carcinoma V-ATPase-mediated extracellular acidification and cell migration.

Muc1 enhances the ß-catenin protective pathway during ischemia-reperfusion injury.

The hypoxia-inducible factor (HIF)-1 and ß-catenin protective pathways represent the two most significant cellular responses that are activated in response to acute kidney injury. We previously reported that murine mucin (Muc)1 protects kidney function and morphology in a mouse model of ischemia-reperfusion injury (IRI) by stabilizing HIF-1α, enhancing HIF-1 downstream signaling, and thereby preventing metabolic stress (Pastor-Soler et al. Muc1 is protective during kidney ischemia-reperfusion injury. Am J Physiol Renal Physiol 308: F1452-F1462, 2015). We asked if Muc1 regulates the ß-catenin protective pathway during IRI as 1) ß-catenin nuclear targeting is MUC1 dependent in cultured human cells, 2) ß-catenin is found in coimmunoprecipitates with human MUC1 in extracts of both cultured cells and tissues, and 3) MUC1 prevents ß-catenin phosphorylation by glycogen synthase kinase (GSK)3ß and thereby ß-catenin degradation. Using the same mouse model of IRI, we found that levels of active GSK3ß were significantly lower in kidneys of control mice compared with Muc1 knockout (KO) mice. Consequently, ß-catenin was significantly upregulated at 24 and 72 h of recovery and appeared in the nuclear fraction at 72 h in control mouse kidneys. Both ß-catenin induction and nuclear targeting were absent in Muc1 KO mice. We also found downstream induction of ß-catenin prosurvival factors (activated Akt, survivin, transcription factor T cell factor 4 (TCF4), and its downstream target cyclin D1) and repression of proapoptotic factors (p53, active Bax, and cleaved caspase-3) in control mouse kidneys that were absent or aberrant in kidneys of Muc1 KO mice. Altogether, the data clearly indicate that Muc1 protection during acute kidney injury proceeds by enhancing both the HIF-1 and ß-catenin protective pathways.

Activation of the metabolic sensor AMP-activated protein kinase inhibits aquaporin-2 function in kidney principal cells.

Aquaporin-2 (AQP2) is essential to maintain body water homeostasis. AQP2 traffics from intracellular vesicles to the apical membrane of kidney collecting duct principal cells in response to vasopressin [arginine vasopressin (AVP)], a hormone released with low intravascular volume, which causes decreased kidney perfusion. Decreased kidney perfusion activates AMP-activated kinase (AMPK), a metabolic sensor that inhibits the activity of several transport proteins. We hypothesized that AMPK activation also inhibits AQP2 function. These putative AMPK effects could protect interstitial ionic gradients required for urinary concentration during metabolic stress when low intravascular volume induces AVP release. Here we found that short-term AMPK activation by treatment with 5-aminoimidazole-4-carboxamide-1-ß-d-ribofuranoside (AICAR; 75 min) in kidney tissue prevented baseline AQP2 apical accumulation in principal cells, but did not prevent AQP2 apical accumulation in response to the AVP analog desmopressin (dDAVP). Prolonged AMPK activation prevented AQP2 cell membrane accumulation in response to forskolin in mouse collecting duct mpkCCDc14 cells. Moreover, AMPK inhibition accelerated hypotonic lysis of Xenopus oocytes expressing AQP2. We performed phosphorylation assays to elucidate the mechanism by which AMPK regulates AQP2. Although AMPK weakly phosphorylated immunoprecipitated AQP2 in vitro, no direct AMPK phosphorylation of the AQP2 COOH-terminus was detected by mass spectrometry. AMPK promoted Ser-261 phosphorylation and antagonized dDAVP-dependent phosphorylation of other AQP2 COOH-terminal sites in cells. Our findings suggest an increasing, time-dependent antagonism of AMPK on AQP2 regulation with AICAR-dependent inhibition of cAMP-dependent apical accumulation and AVP-dependent phosphorylation of AQP2. This inhibition likely occurs via a mechanism that does not involve direct AQP2 phosphorylation by AMPK.

Endosomal GPCR signaling turned off by negative feedback actions of PKA and v-ATPase.

The PTH receptor is to our knowledge one of the first G protein-coupled receptor (GPCR) found to sustain cAMP signaling after internalization of the ligand-receptor complex in endosomes. This unexpected model is adding a new dimension on how we think about GPCR signaling, but its mechanism is incompletely understood. We report here that endosomal acidification mediated by the PKA action on the v-ATPase provides a negative feedback mechanism by which endosomal receptor signaling is turned off.

Muc1 is protective during kidney ischemia-reperfusion injury.

Ischemia-reperfusion injury (IRI) due to hypotension is a common cause of human acute kidney injury (AKI). Hypoxia-inducible transcription factors (HIFs) orchestrate a protective response in renal endothelial and epithelial cells in AKI models. As human mucin 1 (MUC1) is induced by hypoxia and enhances HIF-1 activity in cultured epithelial cells, we asked whether mouse mucin 1 (Muc1) regulates HIF-1 activity in kidney tissue during IRI. Whereas Muc1 was localized on the apical surface of the thick ascending limb, distal convoluted tubule, and collecting duct in the kidneys of sham-treated mice, Muc1 appeared in the cytoplasm and nucleus of all tubular epithelia during IRI. Muc1 was induced during IRI, and Muc1 transcripts and protein were also present in recovering proximal tubule cells. Kidney damage was worse and recovery was blocked during IRI in Muc1 knockout mice compared with congenic control mice. Muc1 knockout mice had reduced levels of HIF-1α, reduced or aberrant induction of HIF-1 target genes involved in the shift of glucose metabolism to glycolysis, and prolonged activation of AMP-activated protein kinase, indicating metabolic stress. Muc1 clearly plays a significant role in enhancing the HIF protective pathway during ischemic insult and recovery in kidney epithelia, providing a new target for developing therapies to treat AKI. Moreover, our data support a role specifically for HIF-1 in epithelial protection of the kidney during IRI as Muc1 is present only in tubule epithelial cells.

Regulation of proximal tubule vacuolar H(+)-ATPase by PKA and AMP-activated protein kinase.

The vacuolar H(+)-ATPase (V-ATPase) mediates ATP-driven H(+) transport across membranes. This pump is present at the apical membrane of kidney proximal tubule cells and intercalated cells. Defects in the V-ATPase and in proximal tubule function can cause renal tubular acidosis. We examined the role of protein kinase A (PKA) and AMP-activated protein kinase (AMPK) in the regulation of the V-ATPase in the proximal tubule as these two kinases coregulate the V-ATPase in the collecting duct. As the proximal tubule V-ATPases have different subunit compositions from other nephron segments, we postulated that V-ATPase regulation in the proximal tubule could differ from other kidney tubule segments. Immunofluorescence labeling of rat ex vivo kidney slices revealed that the V-ATPase was present in the proximal tubule both at the apical pole, colocalizing with the brush-border marker wheat germ agglutinin, and in the cytosol when slices were incubated in buffer alone. When slices were incubated with a cAMP analog and a phosphodiesterase inhibitor, the V-ATPase accumulated at the apical pole of S3 segment cells. These PKA activators also increased V-ATPase apical membrane expression as well as the rate of V-ATPase-dependent extracellular acidification in S3 cell monolayers relative to untreated cells. However, the AMPK activator AICAR decreased PKA-induced V-ATPase apical accumulation in proximal tubules of kidney slices and decreased V-ATPase activity in S3 cell monolayers. Our results suggest that in proximal tubule the V-ATPase subcellular localization and activity are acutely coregulated via PKA downstream of hormonal signals and via AMPK downstream of metabolic stress.

Euglycemic Diabetic Ketoacidosis Induced by Sodium-Glucose Cotransporter-2 Inhibitor Use and Coronary Angiography: A Case Report.

Euglycemic diabetic ketoacidosis (EDKA) is an uncommon subtype of diabetic ketoacidosis (DKA) which presents with similar laboratory findings to classic DKA with the exception of blood glucose levels being under 250 mg/dl. EDKA has several etiologies including pregnancy, starvation and the use of sodium-glucose cotransporter-2 inhibitors (SGLT-2). SGLT-2 inhibitors such as empagliflozin and dapagliflozin are increasing in popularity due to their positive benefits for patients with diabetes mellitus and cardiac disease. EDKA is underdiagnosed as it presents with blood sugar levels lower than expected in classic DKA. This case report describes a well-controlled type 2 diabetic patient prescribed an SGLT-2 inhibitor who developed EDKA after undergoing coronary angiography for acute heart failure.

AMP-activated protein kinase regulates the vacuolar H+-ATPase via direct phosphorylation of the A subunit (ATP6V1A) in the kidney.

The vacuolar H(+)-ATPase (V-ATPase) in intercalated cells contributes to luminal acidification in the kidney collecting duct and nonvolatile acid excretion. We previously showed that the A subunit in the cytoplasmic V1 sector of the V-ATPase (ATP6V1A) is phosphorylated by the metabolic sensor AMP-activated protein kinase (AMPK) in vitro and in kidney cells. Here, we demonstrate that treatment of rabbit isolated, perfused collecting ducts with the AMPK activator 5-aminoimidazole-4-carboxamide-1-ß-D-ribofuranoside (AICAR) inhibited V-ATPase-dependent H(+) secretion from intercalated cells after an acid load. We have identified by mass spectrometry that Ser-384 is a major AMPK phosphorylation site in the V-ATPase A subunit, a result confirmed by comparing AMPK-dependent phosphate labeling of wild-type A-subunit (WT-A) with that of a Ser-384-to-Ala A subunit mutant (S384A-A) in vitro and in intact HEK-293 cells. Compared with WT-A-expressing HEK-293 cells, S384A-A-expressing cells exhibited greater steady-state acidification of HCO3(-)-containing media. Moreover, AICAR treatment of clone C rabbit intercalated cells expressing the WT-A subunit reduced V-ATPase-dependent extracellular acidification, an effect that was blocked in cells expressing the phosphorylation-deficient S384A-A mutant. Finally, expression of the S384A-A mutant prevented cytoplasmic redistribution of the V-ATPase by AICAR in clone C cells. In summary, direct phosphorylation of the A subunit at Ser-384 by AMPK represents a novel regulatory mechanism of the V-ATPase in kidney intercalated cells. Regulation of the V-ATPase by AMPK may couple V-ATPase activity to cellular metabolic status with potential relevance to ischemic injury in the kidney and other tissues.

Percutaneous extraction of ePTFE-coated ICD leads: a single center comparative experience.

BACKGROUND: Percutaneous extraction of standard implantable cardioverter-defibrillator leads is often complicated by ingrowth of fibrotic tissue into the shocking coils. Leads with GORE™ expanded polytetrafluoroethylene (ePTFE) coating (W. L. Gore & Associates, Inc., Newark, DE, USA) designed to inhibit fibrosis are in use, but clinical data regarding their extraction are lacking. The study's purpose was to examine the feasibility, efficacy, and safety of percutaneous extraction involving defibrillator leads coated with ePTFE. METHODS: We analyzed our database to identify all percutaneously extracted leads with ePTFE-coated shocking coils. Lead and procedure characteristics were compared to a cohort of noncoated leads of similar implant duration. RESULTS: One hundred fifty-six leads were extracted from 145 patients; 57 ePTFE-coated leads, with a mean implant duration of 621 days, were extracted and compared to 99 noncoated leads, with a mean implant duration of 763 days (P = 0.0641). Mean extraction time was 5 minutes for coated leads versus 9.75 minutes for noncoated leads (P = 0.0001). Extraction time of less than 1 minute was more frequent with coated leads (61% vs 35%, P = 0.0025). Adjunct extraction tools were required less frequently with coated leads than noncoated leads (39% vs 63%, P = 0.0071). There was no fibrosis where ePTFE covered the shocking coils. Alternatively, 23 of 99 (23%) noncoated leads demonstrated fibrosis adherent to the shock coil. There were no procedure-related complications in either group. CONCLUSIONS: Compared to noncoated leads, ePTFE-coated leads are associated with shorter extraction times and are less likely to require extraction tools for removal. The difference is likely related to the absence of fibrosis over the ePTFE-coated high-energy coils.

Transforming medical device biofilm control with surface treatment using microfabrication techniques.

Biofilm deposition on indwelling medical devices and implanted biomaterials is frequently attributed to the prevalence of resistant infections in humans. Further, the nature of persistent infections is widely believed to have a biofilm etiology. In this study, the wettability of commercially available indwelling medical devices was explored for the first time, and its effect on the formation of biofilm was determined in vitro. Surprisingly, all tested indwelling devices were found to be hydrophilic, with surface water contact angles ranging from 60° to 75°. First, we established a thriving Candida albicans biofilm growth at 24 hours. in YEPD at 30°C and 37°C plus serum in vitro at Cyclic olefin copolymer (COC) modified surface, which was subsequently confirmed via scanning electron microscopy, while their cellular metabolic function was assessed using the XTT cell viability assay. Surfaces with patterned wettability show that a contact angle of 110° (hydrophobic) inhibits C. albicans planktonic and biofilm formation completely compared to robust growth at a contact angle of 40° (hydrophilic). This finding may provide a novel antimicrobial strategy to prevent biofilm growth and antimicrobial resistance on indwelling devices and prosthetic implants. Overall, this study provides valuable insights into the surface characteristics of medical devices and their potential impact on biofilm formation, leading to the development of improved approaches to control and prevent microbial biofilms and re-infections.

Mineralocorticoid receptor-independent activation of ENaC in bile duct ligated mice.

Sodium and fluid retention in liver disease is classically thought to result from reduced effective circulating volume and stimulation of the renin-angiotensin-aldosterone system (RAAS). Aldosterone dives Na+ retention by activating the mineralocorticoid receptor and promoting the maturation and apical surface expression of the epithelial Na+ channel (ENaC), found in the aldosterone-sensitive distal nephron. However, evidence of fluid retention without RAAS activation suggests the involvement of additional mechanisms. Liver disease can greatly increase plasma and urinary bile acid concentrations and have been shown to activate ENaC in vitro. We hypothesize that elevated bile acids in liver disease activate ENaC and drive fluid retention independent of RAAS. We therefore increased circulating bile acids in mice through bile duct ligation (BDL) and measured effects on urine and body composition, while using spironolactone to antagonize the mineralocorticoid receptor. We found BDL lowered blood [K+] and hematocrit, and increased benzamil-sensitive natriuresis compared to sham, consistent with ENaC activation. BDL mice also gained significantly more body water. Blocking ENaC reversed fluid gains in BDL mice but had no effect in shams. In isolated collecting ducts from rabbits, taurocholic acid stimulated net Na+ absorption but had no effect on K+ secretion or flow-dependent ion fluxes. Our results provide experimental evidence for a novel aldosterone-independent mechanism for sodium and fluid retention in liver disease which may provide additional therapeutic options for liver disease patients.