Role of dietary amino acid balance in diet restriction-mediated lifespan extension, renoprotection, and muscle weakness in aged mice.

Extending healthy lifespan is an emerging issue in an aging society. This study was designed to identify a dietary method of extending lifespan, promoting renoprotection, and preventing muscle weakness in aged mice, with a focus on the importance of the balance between dietary essential (EAAs) and nonessential amino acids (NEAAs) on the dietary restriction (DR)-induced antiaging effect. Groups of aged mice were fed ad libitum, a simple DR, or a DR with recovering NEAAs or EAAs. Simple DR significantly extended lifespan and ameliorated age-related kidney injury; however, the beneficial effects of DR were canceled by recovering dietary EAA but not NEAA. Simple DR prevented the age-dependent decrease in slow-twitch muscle fiber function but reduced absolute fast-twitch muscle fiber function. DR-induced fast-twitch muscle fiber dysfunction was improved by recovering either dietary NEAAs or EAAs. In the ad libitum-fed and the DR plus EAA groups, the renal content of methionine, an EAA, was significantly higher, accompanied by lower renal production of hydrogen sulfide (H2 S), an endogenous antioxidant. Finally, removal of methionine from the dietary EAA supplement diminished the adverse effects of dietary EAA on lifespan and kidney injury in the diet-restricted aged mice, which were accompanied by a recovery in H2 S production capacity and lower oxidative stress. These data imply that a dietary approach could combat kidney aging and prolong lifespan, while preventing muscle weakness, and suggest that renal methionine metabolism and the trans-sulfuration pathway could be therapeutic targets for preventing kidney aging and subsequently promoting healthy aging

Protective role of podocyte autophagy against glomerular endothelial dysfunction in diabetes.

To examine the cell-protective role of podocyte autophagy against glomerular endothelial dysfunction in diabetes, we analyzed the renal phenotype of tamoxifen (TM)-inducible podocyte-specific Atg5-deficient (iPodo-Atg5-/-) mice with experimental endothelial dysfunction. In both control and iPodo-Atg5-/- mice, high fat diet (HFD) feeding induced glomerular endothelial damage characterized by decreased urinary nitric oxide (NO) excretion, collapsed endothelial fenestrae, and reduced endothelial glycocalyx. HFD-fed control mice showed slight albuminuria and nearly normal podocyte morphology. In contrast, HFD-fed iPodo-Atg5-/- mice developed massive albuminuria accompanied by severe podocyte injury that was observed predominantly in podocytes adjacent to damaged endothelial cells by scanning electron microscopy. Although podocyte-specific autophagy deficiency did not affect endothelial NO synthase deficiency-associated albuminuria, it markedly exacerbated albuminuria and severe podocyte morphological damage when the damage was induced by intravenous neuraminidase injection to remove glycocalyx from the endothelial surface. Furthermore, endoplasmic reticulum stress was accelerated in podocytes of iPodo-Atg5-/- mice stimulated with neuraminidase, and treatment with molecular chaperone tauroursodeoxycholic acid improved neuraminidase-induced severe albuminuria and podocyte injury. In conclusion, podocyte autophagy plays a renoprotective role against diabetes-related structural endothelial damage, providing an additional insight into the pathogenesis of massive proteinuria in diabetic nephropathy

Contrast medium-induced severe thrombocytopenia in patient on maintenance hemodialysis : a case report and literature review.

A 43-year-old male patient on maintenance hemodialysis had an enhanced computed tomography scan examination with iohexol for the first time 10 min before regular hemodialysis therapy. At the start of hemodialysis, no symptoms were observed, and the platelet count was 148,000/μl. Approximately 1 h after starting hemodialysis, dyspnea and chest discomfort appeared. Since oxygen saturation of the peripheral artery decreased to 87%, oxygen administration was immediately started while continuing hemodialysis therapy. Furthermore, gingival hemorrhage was observed, and the platelet count decreased to 5000/μl. We were carefully monitoring his conditions while continuing hemodialysis and oxygen administration, but no further deterioration was observed. Thereafter, these symptoms and severe thrombocytopenia gradually improved without additional treatment. At the end of hemodialysis, these symptoms completely disappeared. As well, the platelet count recovered to 35,000/μl at the end of hemodialysis and increased to 92,000/μl the next morning. From the clinical course, we diagnosed with contrast medium-induced thrombocytopenia. Acute thrombocytopenia is a rare complication induced by the contrast medium. Until now, 16 cases on contrast medium-induced thrombocytopenia have been reported. Our case spontaneously recovered from severe thrombocytopenia relatively earlier than previous reports. Our patient started hemodialysis therapy 10 min after an enhanced computed tomography examination. Early removal of contrast medium by hemodialysis might be associated with early improvement. We should acknowledge that contrast media have potential to induce severe thrombocytopenia, even in patients on maintenance hemodialysi