Dapagliflozin induced hypernatremia via osmotic diuresis: a case report.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been widely used. They inhibit proximal tubular glucose reabsorption, resulting in glycosuria. Herein, we report the case of a 65-year-old woman who presented with hypernatremia during the perioperative period of a subarachnoid hemorrhage. The patient continued to take dapagliflozin postoperatively and subsequently developed severe hypernatremia. Based on the urinalysis findings, we diagnosed osmotic diuresis due to glycosuria as contributing to hypernatremia. Hypernatremia improved with the discontinuation of dapagliflozin and the administration of a hypotonic infusion. In the perioperative period, physicians should discontinue SGLT2 inhibitors owing to concerns about the development of hypernatremia.

Hypernatremic chloride-depletion metabolic alkalosis successfully treated with high cation-gap amino acids: a case report.

Normal saline (NS) is recommended for the treatment of chloride-depletion alkalosis (CDA). However, its use in patients with drinking water restrictions or fluid volume deficiencies may lead to hypernatremia. We report the case of a 42-year-old Japanese man with ileus due to sigmoidal volvulus, who presented with CDA. After endoscopic decompression, NS was administered to treat the CDA. Despite the administration of NS, CDA persisted and hypernatremia developed. The infusion was then changed to high cation-gap amino acids (HCG-AA), which improved both metabolic alkalosis and hypernatremia. Thus, HCG-AA may be useful for the treatment of hypernatremia in patients with CDA.

Basigin is released in extracellular vesicles derived from the renal tubular epithelium in response to albuminuria.

AIM: Irrespective of the cause, albumin/proteinuria induces tubulointerstitial damage and accelerates the progression of kidney diseases. Our series of studies demonstrated that proteinuria, an independent prognostic factor for chronic kidney disease (CKD), is correlated with urinary basigin/CD147 (Bsg) levels. We examined the morphology and origin of Bsg in the tubular lumen through the effects of filtered glucose and protein solutes on the tubules. METHODS: Diabetic kidney disease (DKD) patients (N = 50) were treated with spironolactone 25 mg for 4 weeks or by conservative treatment. The associations between urinary Bsg values and clinical indicators were examined. Primary-cultured proximal tubular epithelial cells (PTECs) from human adult kidneys were exposed to high glucose or bovine serum albumin (BSA). RESULTS: In patients with early phase DKD, urinary Bsg levels were closely correlated with proteinuria but not HbA1c. Full-length Bsg on extracellular vesicles (EVs) was investigated primarily in urine collected from DKD patients. EVs obtained from the urine of DKD patients included Bsg and SGLT2 proteins. Notably, spironolactone treatment concomitantly suppressed the release of Bsg-bearing EVs in correlation with decreased albuminuria. Exposure of PTECs to BSA (but not high glucose) enhanced the storage of supernatant Bsg in EVs despite the absence of exposure-specific changes in Bsg transcription. CONCLUSION: Proteinuria induces the release of Bsg-bearing EVs derived from PTECs into the tubular lumen.

Basigin deficiency prevents anaplerosis and ameliorates insulin resistance and hepatosteatosis.

Monocarboxylates, such as lactate and pyruvate, are precursors for biosynthetic pathways, including those for glucose, lipids, and amino acids via the tricarboxylic acid (TCA) cycle and adjacent metabolic networks. The transportation of monocarboxylates across the cellular membrane is performed primarily by monocarboxylate transporters (MCTs), the membrane localization and stabilization of which are facilitated by the transmembrane protein basigin (BSG). Here, we demonstrate that the MCT/BSG axis sits at a crucial intersection of cellular metabolism. Abolishment of MCT1 in the plasma membrane was achieved by Bsg depletion, which led to gluconeogenesis impairment via preventing the influx of lactate and pyruvate into the cell, consequently suppressing the TCA cycle. This net anaplerosis suppression was compensated in part by the increased utilization of glycogenic amino acids (e.g., alanine and glutamine) into the TCA cycle and by activated ketogenesis through fatty acid ß-oxidation. Complementary to these observations, hyperglycemia and hepatic steatosis induced by a high-fat diet were ameliorated in Bsg-deficient mice. Furthermore, Bsg deficiency significantly improved insulin resistance induced by a high-fat diet. Taken together, the plasma membrane-selective modulation of lactate and pyruvate transport through BSG inhibition could potentiate metabolic flexibility to treat metabolic diseases.

Refractory Hypotension Caused by Selenium Deficiency in a Patient on Peritoneal Dialysis.

Selenium is essential for human health; its deficiency leads to cardiac dysfunction. We herein report a 79-year-old man on peritoneal dialysis who presented with refractory hypotension caused by selenium deficiency. He was admitted to our hospital with bacterial pneumonia and hypotension and abnormal electrocardiogram (ECG) findings. Despite improvement of pneumonia, his hypotension continued, and intravenous noradrenalin could not be discontinued. His serum selenium level was extremely low, and he was started on intravenous selenium. His hypotension and ECG findings gradually improved, and noradrenalin was discontinued. Physicians should consider selenium deficiency when patients on peritoneal dialysis show refractory hypotension.

CD147 Is Essential for the Development of Psoriasis via the Induction of Th17 Cell Differentiation.

Th17 cells play an important role in psoriasis. The differentiation of naïve CD4+ T cells into Th17 cells depends on glycolysis as the energy source. CD147/basigin, an integral transmembrane protein belonging to the immunoglobulin superfamily, regulates glycolysis in association with monocarboxylate transporters (MCTs)-1 and -4 in cancer cells and T cells. We examined whether CD147/basigin is involved in the pathogenesis of psoriasis in humans and psoriasis-model mice. The serum level of CD147 was increased in patients with psoriasis, and the expression of CD147 and MCT-1 was elevated in their dermal CD4+ RORγt+ T cells. In vitro, the potential of naïve CD4+ T cells to differentiate into Th17 cells was abrogated in CD147-/- T cells. Imiquimod (IMQ)-induced psoriatic dermatitis was significantly milder in CD147-/- mice and bone marrow chimeric mice lacking CD147 in the hematopoietic cells of myeloid lineage. These findings demonstrate that CD147 is essential for the development of psoriasis via the induction of Th17 cell differentiation.

Acquired Fanconi Syndrome in a Patient with Nontyphoidal Salmonella Bacteremia.

Nontyphoidal Salmonella is a common cause of bacterial gastroenteritis, occasionally causing bacteremia. We herein report the case of an 80-year-old man who presented with bacteremia and pre-renal acute kidney injury (AKI) secondary to diarrhea caused by nontyphoidal Salmonella. Despite AKI improvement on fluid administration, some serological abnormalities, such as hypokalemia, hypophosphatemia, and hypouricemia, and abnormal urinary findings emerged, including renal glycosuria and aminoaciduria. Fractional excretion of phosphate and uric acid was increased, suggesting that the serological and urinary abnormalities may have arisen from Fanconi syndrome. Physicians should consider acquired Fanconi syndrome when patients with nontyphoidal Salmonella bacteremia present with electrolyte disorders.

CD147/Basigin Deficiency Prevents the Development of Podocyte Injury through FAK Signaling.

Podocytes, which are susceptible to injury by various stimuli and stress, are critical regulators of proteinuric kidney diseases, regardless of the primary disease and pathogenesis. We further confirmed a significant correlation between urinary CD147/basigin (Bsg) levels and proteinuria in patients with focal segmental glomerulosclerosis. However, the molecular mechanism of podocyte injury involving Bsg is not fully understood. Here, the involvement of Bsg in the pathogenesis of podocyte injury was elucidated. Healthy podocytes rarely express Bsg protein. In two independent mouse models, including adriamycin-induced nephropathy and Nω-nitro-l-arginine methyl ester (l-name)-induced endothelial dysfunction, Bsg induction in injured podocytes caused podocyte effacement, which led to development of proteinuria. Bsg silencing in cultured podocytes exposed to transforming growth factor-ß suppressed focal adhesion rearrangement and cellular motility via the activation of ß1 integrin-focal adhesion kinase-matrix metallopeptidase signaling. In addition, induction of vascular endothelial growth factor and endothelin-1, which are implicated in podocyte-to-endothelial cross-communication, was lower in the supernatants of cultured Bsg-silenced podocytes stimulated with transforming growth factor-ß. In this setting, Bsg may be involved in a physiological positive feedback loop that accelerates podocyte cell motility and depolarization. The current study thus suggests that Bsg silencing via suppression of ß1 integrin-focal adhesion kinase-matrix metallopeptidase signaling may be an attractive therapeutic strategy for the maintenance of podocytes in patients with proteinuric kidney diseases.

Hemorrhagic shock due to bleeding from an arteriovenous fistula after allograft biopsy in a kidney transplant recipient: a case report.

Arteriovenous fistula (AVF) after allograft biopsy occurs in 1.6-8.3% of kidney transplant patients and most cases remain asymptomatic. Here, we report a case of hemorrhagic shock in a kidney transplant recipient following bleeding from an AVF after graft biopsy. Immediate intensive care including angiographic embolization saved the patient and the allograft. A 62-year-old woman with end-stage renal disease caused by diabetic nephropathy underwent ABO-incompatible kidney transplantation. No complications occurred in the early postoperative period. However, serum creatinine levels did not decrease sufficiently and decreased graft diastolic blood flow was noted on ultrasound. Therefore, at 14 days after kidney transplantation, allograft biopsy was performed to elucidate the cause of allograft dysfunction. At 5 days after allograft biopsy, the patient developed hemorrhagic shock caused by bleeding from an AVF in the allograft. We immediately performed angiographic embolization, and her vital signs improved without deterioration in renal function. AVF can cause hemorrhagic shock, and angiographic embolization is effective for treating it.

Fanconi Syndrome Associated with Hyponatremia in Two Patients with Legionella Pneumonia.

Legionella pneumophila is a cause of community-acquired pneumonia that is reported to induce electrolyte disorders, including hyponatremia, hypokalemia, and hypophosphatemia. We herein report two Japanese men with Legionella pneumonia and hyponatremia and hypophosphatemia. These findings were associated with an elevation of urinary low-molecular-weight tubular protein, including urinary ß2-microglobulin, N-acetyl-ß-D-glucosaminidase, the fractional excretion of phosphate and uric acid, and the presence of glycosuria and panaminoaciduria, suggesting that their electrolyte disorders had been caused by Fanconi syndrome. In these two cases, hyponatremia was probably due to salt wasting. Electrolyte disorders caused by Legionella pneumonia are corrected by treatment of the primary disease and fluid administration.

Hyponatremic Chloride-depletion Metabolic Alkalosis Successfully Treated with High Cation-gap Amino Acid.

Chloride (Cl)-depletion alkalosis (CDA) develops due to the loss of Cl-rich body fluid, i.e., vomiting or diuretics use, and is typically treated with a chloride-rich solution such as normal saline (NS). Although NS is one of the most utilized Cl-rich solutions, high cation-gap amino acid (HCG-AA) predominantly comprises Cl and less sodium, making HCG-AA more efficient in correcting CDA. We herein report a case of CDA with chronic hyponatremia after frequent vomiting, which was successfully treated with HCG-AA without overcorrecting hyponatremia or causing hypervolemia. HCG-AA may be more beneficial than NS for treating hyponatremic or hypervolemic metabolic alkalosis.

Ischemic Acute Tubular Necrosis due to Diltiazem Overdose.

Diltiazem overdose has a high mortality rate due to cardiotoxicity associated with bradycardia and hypotension. A previous article reported that this type of overdose can cause acute tubular necrosis, which was not pathologically, but rather clinically, diagnosed. We herein report the case of a 55-year-old man who sustained nonoliguric acute kidney injury after taking 60 diltiazem tablets. A kidney biopsy performed six days after admission showed ischemic, not toxic, acute tubular necrosis. The patient's kidney function improved spontaneously. In this case report, we clarify the cause of renal impairment caused by diltiazem overdose pathologically. Physicians should therefore consider ischemic acute tubular necrosis as a cause of kidney injury in patients with diltiazem overdose.

A Fatal Case of Metformin-associated Lactic Acidosis.

A 72-year-old woman with a history of type 2 diabetes mellitus was brought to the ER with metformin-associated lactic acidosis. She received continuous hemofiltration and hemodialysis, but the laboratory analyses showed no improvement. She died 11 hours after admission. Metformin is minimally bound to proteins and is readily dialyzable, but a prolonged period of dialysis is required, because metformin has a very large distribution volume and is distributed to multiple compartments. The peak blood metformin level was 432 mg/L in this case, which is one of the highest metformin concentrations ever reported, and eight hours of hemodialysis were not sufficient to reduce the serum level.