Megalin-related mechanism of hemolysis-induced acute kidney injury and the therapeutic strategy.

Hemolysis-induced acute kidney injury (AKI) is attributed to heme-mediated proximal tubule epithelial cell (PTEC) injury and tubular cast formation due to intratubular protein condensation. Megalin is a multiligand endocytic receptor for proteins, peptides, and drugs in PTECs and mediates the uptake of free hemoglobin and the heme-scavenging protein α1-microglobulin. However, understanding of how megalin is involved in the development of hemolysis-induced AKI remains elusive. Here, we investigated the megalin-related pathogenesis of hemolysis-induced AKI and a therapeutic strategy using cilastatin, a megalin blocker. A phenylhydrazine-induced hemolysis model developed in kidney-specific mosaic megalin knockout (MegKO) mice confirmed megalin-dependent PTEC injury revealed by the co-expression of kidney injury molecule-1 (KIM-1). In the hemolysis model in kidney-specific conditional MegKO mice, the uptake of hemoglobin and α1-microglobulin as well as KIM-1 expression in PTECs was suppressed, but tubular cast formation was augmented, likely due to the nonselective inhibition of protein reabsorption in PTECs. Quartz crystal microbalance analysis revealed that cilastatin suppressed the binding of megalin with hemoglobin and α1-microglobulin. Cilastatin also inhibited the specific uptake of fluorescent hemoglobin by megalin-expressing rat yolk sac tumor-derived L2 cells. In a mouse model of hemolysis-induced AKI, repeated cilastatin administration suppressed PTEC injury by inhibiting the uptake of hemoglobin and α1-microglobulin and also prevented cast formation. Hemopexin, another heme-scavenging protein, was also found to be a novel ligand of megalin, and its binding to megalin and uptake by PTECs in the hemolysis model were suppressed by cilastatin. Mass spectrometry-based semiquantitative analysis of urinary proteins in cilastatin-treated C57BL/6J mice indicated that cilastatin suppressed the reabsorption of a limited number of megalin ligands in PTECs, including α1-microglobulin and hemopexin. Collectively, cilastatin-mediated selective megalin blockade is an effective therapeutic strategy to prevent both heme-mediated PTEC injury and cast formation in hemolysis-induced AKI. © 2024 The Pathological Society of Great Britain and Ireland.

Cryo-EM structures elucidate the multiligand receptor nature of megalin.

Megalin (low-density lipoprotein receptor-related protein 2) is a giant glycoprotein of about 600 kDa, mediating the endocytosis of more than 60 ligands, including those of proteins, peptides, and drug compounds [S. Goto, M. Hosojima, H. Kabasawa, A. Saito, Int. J. Biochem. Cell Biol. 157, 106393 (2023)]. It is expressed predominantly in renal proximal tubule epithelial cells, as well as in the brain, lungs, eyes, inner ear, thyroid gland, and placenta. Megalin is also known to mediate the endocytosis of toxic compounds, particularly those that cause renal and hearing disorders [Y. Hori et al., J. Am. Soc. Nephrol. 28, 1783-1791 (2017)]. Genetic megalin deficiency causes Donnai-Barrow syndrome/facio-oculo-acoustico-renal syndrome in humans. However, it is not known how megalin interacts with such a wide variety of ligands and plays pathological roles in various organs. In this study, we elucidated the dimeric architecture of megalin, purified from rat kidneys, using cryoelectron microscopy. The maps revealed the densities of endogenous ligands bound to various regions throughout the dimer, elucidating the multiligand receptor nature of megalin. We also determined the structure of megalin in complex with receptor-associated protein, a molecular chaperone for megalin. The results will facilitate further studies on the pathophysiology of megalin-dependent multiligand endocytic pathways in multiple organs and will also be useful for the development of megalin-targeted drugs for renal and hearing disorders, Alzheimer's disease [B. V. Zlokovic et al., Proc. Natl. Acad. Sci. U.S.A. 93, 4229-4234 (1996)], and other illnesses.

The structure of the rat vitamin B12 transporter TC and its complex with glutathionylcobalamin.

Vitamin B12 (cobalamin or Cbl) functions as a cofactor in two important enzymatic processes in human cells, and life is not sustainable without it. B12 is obtained from food and travels from the stomach, through the intestine, and into the bloodstream by three B12-transporting proteins: salivary haptocorrin (HC), gastric intrinsic factor, and transcobalamin (TC), which all bind B12 with high affinity and require proteolytic degradation to liberate Cbl. After intracellular delivery of dietary B12, Cbl in the aquo/hydroxocobalamin form can coordinate various nucleophiles, for example, GSH, giving rise to glutathionylcobalamin (GSCbl), a naturally occurring form of vitamin B12. Currently, there is no data showing whether GSCbl is recognized and transported in the human body. Our crystallographic data shows for the first time the complex between a vitamin B12 transporter and GSCbl, which compared to aquo/hydroxocobalamin, binds TC equally well. Furthermore, sequence analysis and structural comparisons show that TC recognizes and transports GSCbl and that the residues involved are conserved among TCs from different organisms. Interestingly, haptocorrin and intrinsic factor are not structurally tailored to bind GSCbl. This study provides new insights into the interactions between TC and Cbl.

Megalin is involved in angiotensinogen-induced, angiotensin II-mediated ERK1/2 signaling to activate Na + -H + exchanger 3 in proximal tubules.

BACKGROUND: Kidney angiotensin (Ang) II is produced mainly from liver-derived, glomerular-filtered angiotensinogen (AGT). Podocyte injury has been reported to increase the kidney Ang II content and induce Na + retention depending on the function of megalin, a proximal tubular endocytosis receptor. However, how megalin regulates the renal content and action of Ang II remains elusive. METHODS: We used a mass spectrometry-based, parallel reaction-monitoring assay to quantitate Ang II in plasma, urine, and kidney homogenate of kidney-specific conditional megalin knockout (MegKO) and control (Ctl) mice. We also evaluated the pathophysiological changes in both mouse genotypes under the basal condition and under the condition of increased glomerular filtration of AGT induced by administration of recombinant mouse AGT (rec-mAGT). RESULTS: Under the basal condition, plasma and kidney Ang II levels were comparable in the two mouse groups. Ang II was detected abundantly in fresh spot urine in conditional MegKO mice. Megalin was also found to mediate the uptake of intravenously administered fluorescent Ang II by PTECs. Administration of rec-mAGT increased kidney Ang II, exerted renal extracellular signal-regulated kinase 1/2 (ERK1/2) signaling, activated proximal tubular Na + -H + exchanger 3 (NHE3), and decreased urinary Na + excretion in Ctl mice, whereas these changes were suppressed but urinary Ang II was increased in conditional MegKO mice. CONCLUSION: Increased glomerular filtration of AGT is likely to augment Ang II production in the proximal tubular lumen. Thus, megalin-dependent Ang II uptake should be involved in the ERK1/2 signaling that activates proximal tubular NHE3 in vivo , thereby causing Na + retention.

The endocytosis receptor megalin: From bench to bedside.

The large (∼600 kDa) endocytosis receptor megalin/low-density lipoprotein receptor-related protein 2 is highly expressed at the apical membrane of proximal tubular epithelial cells (PTECs). Megalin plays an important role in the endocytosis of various ligands via interactions with intracellular adaptor proteins, which mediate the trafficking of megalin in PTECs. Megalin mediates the retrieval of essential substances, including carrier-bound vitamins and elements, and impairment of the endocytic process may result in the loss of those substances. In addition, megalin reabsorbs nephrotoxic substances such as antimicrobial (colistin, vancomycin, and gentamicin) or anticancer (cisplatin) drugs and advanced glycation end product-modified or fatty acid-containing albumin. The megalin-mediated uptake of these nephrotoxic ligands causes metabolic overload in PTECs and leads to kidney injury. Blockade or suppression of the megalin-mediated endocytosis of nephrotoxic substances may represent a novel therapeutic strategy for drug-induced nephrotoxicity or metabolic kidney disease. Megalin reabsorbs urinary biomarker proteins such as albumin, α1-microglobulin, ß2-microglobulin, and liver-type fatty acid-binding protein; thus, the above-mentioned megalin-targeted therapy may have an effect on the urinary excretion of these biomarkers. We have previously established a sandwich enzyme-linked immunosorbent assay to measure the ectodomain (A-megalin) and full-length (C-megalin) forms of urinary megalin using monoclonal antibodies against the amino- and carboxyl-terminals of megalin, respectively, and reported their clinical usefulness. In addition, there have been reports of patients with novel pathological anti-brush border autoantibodies targeting megalin in the kidney. Even with these breakthroughs in the characterization of megalin, a large number of issues remain to be addressed in future research.

Novel findings on the anatomy of medial canthus in dogs.

PURPOSE: Severe entropion of the medial canthus results in ocular surface diseases and tear staining syndrome. However, detailed anatomical structures of the medial canthus and lacrimal ducts in dogs are poorly understood. We aimed to understand the anatomical structures of the medial canthus by analyzing the distances from the medial palpebral commissure to the superior lacrimal punctum (DSP) and to the inferior lacrimal punctum (DIP) and by histological examinations of the medial canthal anatomy. METHODS: Dogs that underwent modified medial canthoplasty (MMC) between April 2017 and March 2021 were studied. As a reference, non-brachycephalic dogs that underwent other surgeries were also examined. DSP and DIP were measured preoperatively in all dogs in both the non-everted and everted positions. Histological examinations of the medial canthal anatomy were performed in four eyes isolated from beagles. RESULTS: The ratios of DIP to DSP (mean ± SD) at the non-everted and everted positions in 242 MMC eyes of 126 dogs were 2.05 ± 0.46 and 1.05 ± 0.13, respectively (p < .01). The ratios of everted to non-everted positions for DIP and DSP were 0.98 ± 0.21 and 1.93 ± 0.49, respectively (p < .01). Histological findings indicated that the orbicularis oculi muscle (OOM) circumjacent lacrimal canaliculus transformed into collagen fibers and were attached to the lacrimal bone. CONCLUSIONS: Histological studies revealed that the OOM circumjacent lacrimal canaliculus transformed into collagen fibers and these collagen fibers may be related to the difference between DSP and DIP.

A case of idiopathic nodular glomerulosclerosis successfully treated by intensive blockade of the renin-angiotensin-aldosterone system.

Idiopathic nodular glomerulosclerosis has a poor renal prognosis and is characterized by diffuse nodular glomerulosclerotic lesions in the absence of diabetic mellitus. Here, we report the case of a 69-year-old woman with no smoking history who developed renal dysfunction and proteinuria in the absence of overt diabetes or obesity. A biopsy specimen showed nodular mesangial sclerosis with arteriolar hyalinosis and severe large-vessel arteriosclerosis, leading to a diagnosis of idiopathic nodular glomerulosclerosis. Addition of esaxerenone to her existing renin-angiotensin-aldosterone inhibitor therapy led to a rapid decrease in the proteinuria levels and the maintenance of renal function without any complications for more than a year. The results suggest that intensive renin-angiotensin-aldosterone blockade might be an effective treatment for idiopathic nodular glomerulosclerosis.

A review of diagnostic tests for qualitative and quantitative tear film deficiency in dogs.

Dry eye disease (DED) is a complex multifactorial condition caused by loss of ocular surface homeostasis from quantitative and/or qualitative tear film deficiency. Schirmer tear test (STT) is often the only diagnostic test used to assess for DED in veterinary practice. STT is invaluable in the diagnosis and monitoring of quantitative tear film deficiency (i.e., keratoconjunctivitis sicca); however, it is not sufficient to optimize therapy and fully recognize other contributing factors for the disturbance in ocular surface homeostasis. The present work reviews diagnostic tests for assessing aqueous tear production in veterinary medicine, as well as the quality of tears, corneal epithelial barrier integrity, and the lacrimal functional unit.

Efficacy of Low-Protein Rice for Dietary Protein Restriction in CKD Patients: A Multicenter, Randomized, Controlled Study.

Background: The benefits of dietary protein restriction in CKD remain unclear, largely due to inadequate adherence in most clinical trials. We examined whether low-protein rice (LPR) previously developed to reduce the protein content of rice, a major staple food, would help improve adherence to dietary protein restriction. Methods: This open-label, multicenter, randomized, controlled trial evaluated the efficacy of LPR use for reducing dietary protein intake (DPI) in patients with CKD stages G3aA2-G4. Participants were randomly assigned in a 1:1 ratio to an LPR or control group and were followed up for 24 weeks. Both groups received regular counseling by dietitians to help achieve a target DPI of 0.7 g/kg ideal body weight (IBW) per day. The amount of protein in LPR is about 4% of that in ordinary rice, and the participants in the LPR group were instructed to consume LPR with at least two meals per day. The primary outcome was estimated dietary protein intake (eDPI) determined using the Maroni formula. The secondary outcomes included creatinine clearance (CCr) and urinary protein on the basis of 24-hour urine collection. Results: In total, 51 patients were randomized to either the LPR group or the control group. At baseline, mean age was 62.5 years, 70% were men, mean CCr was 52.0 ml/min, and mean eDPI was 0.99 g/kg IBW per day. At 24 weeks, mean eDPI decreased to 0.80 g/kg IBW per day in the LPR group and to 0.91 g/kg IBW per day in the control group, giving a between-group difference of 0.11 g/kg IBW per day (95% confidence interval, 0.03 to 0.19 g/kg IBW per day; P=0.006). There was no significant between-group difference in CCr, but urinary protein was lower at 24 weeks in the LPR group than in the control group. Conclusions: LPR is a feasible tool for efficiently reducing DPI in patients with CKD. Clinical Trial registry name and registration number: Randomized, Multicenter, Controlled Study for the Efficacy of Low-Protein Rice Diet in Patients with Chronic Kidney Disease, UMIN000015630.

Urinary A- and C-megalin predict progression of diabetic kidney disease: an exploratory retrospective cohort study.

AIMS: Megalin, a proximal tubular endocytosis receptor, is excreted in urine in two forms: ectodomain (A-megalin) and full-length (C-megalin). We explored whether urinary megalin levels can be used as independent prognostic biomarkers in the progression of diabetic kidney disease (DKD). METHODS: The associations between baseline urinary A-megalin/creatinine (Cr) and/or C-megalin/Cr levels and the subsequent estimated glomerular filtration rate (eGFR) slope were analyzed using a generalized estimating equation. Patients were categorized into higher or lower groups based on the optimal cutoff values, obtained from a receiver operating characteristic curve, of the two forms of urinary megalin. RESULTS: We retrospectively analyzed 188 patients with type 2 diabetes. The eGFR slopes of the higher A-megalin/Cr and higher C-megalin/Cr groups were - 0.904 and -0.749 ml/min/1.73 m2/year steeper than those of the lower groups, respectively. Moreover, the eGFR slope was -1.888 ml/min/1.73 m2/year steeper in the group with both higher A- and higher C-megalin/Cr than in the other group. These results remained significant when adjusted for known urinary biomarkers (albumin, α1-microglobulin, ß2-microglobulin, and N-acetyl-ß-d-glucosaminidase). CONCLUSIONS: Urinary A- and C-megalin/Cr levels are likely to be prognostic biomarkers in the progression of DKD independent of other urinary biomarkers.

Association of metabolic syndrome traits with urinary biomarkers in Japanese adults.

BACKGROUND: Although metabolic syndrome traits are risk factors for chronic kidney disease, few studies have examined their association with urinary biomarkers. METHODS: Urinary biomarkers, including A-megalin, C-megalin, podocalyxin, albumin, α1-microglobulin, ß2-microglobulin, and N-acetyl-ß-D-glucosaminidase, were cross-sectionally assessed in 347 individuals (52.7% men) with a urine albumin-to-creatinine ratio (ACR) < 300 mg/g in a health checkup. Metabolic syndrome traits were adopted from the National Cholesterol Education Program (third revision) of the Adult Treatment Panel criteria modified for Asians. RESULTS: Participants had a mean body mass index, estimated glomerular filtration rate (eGFR), and median ACR of 23.0 kg/m2, 74.8 mL/min/1.73 m2, and 7.5 mg/g, respectively. In age- and sex-adjusted logistic regression analysis, A-megalin and albumin were significantly associated with the clustering number of metabolic syndrome traits (3 or more). After further adjustment with eGFR, higher quartiles of A-megalin and albumin were each independently associated with the clustering number of metabolic syndrome traits (adjusted odds ratio for A-megalin: 1.30 per quartile, 95% CI 1.03-1.64; albumin: 1.42 per quartile, 95% CI 1.12-1.79). CONCLUSIONS: Both urinary A-megalin and albumin are associated with the clustering number of metabolic syndrome traits. Further research on urinary A-megalin is warranted to examine its role as a potential marker of kidney damage from metabolic risk factors.

Long-term vision outcomes and breed differences of Ahmed Glaucoma Valve implantation in 132 eyes of 122 dogs.

OBJECTIVE: To evaluate the long-term vision outcomes of Ahmed glaucoma valve (AGV) implantation in dogs. PROCEDURES: The medical records of dogs that underwent AGV implantation from January 2010 to December 2019 were reviewed to assess the duration of post-surgical vision preservation (PVP). The relationship between PVP and the underlying cause of glaucoma, implant placement, and preoperative intraocular pressure was evaluated. RESULTS: One hundred and thirty-two eyes of 122 dogs (mean age, 8.3 ± 2.6 years) were included. The mean ± standard error of PVP for all eyes was 57.5 ± 3.9 months. PVP in the dogs with primary acute glaucoma and prior history of cataract surgery was 56.4 ± 4.7 and 59.3 ± 5.9 months, respectively (p = .712). The PVP of the Shiba Inu, American Cocker Spaniel, and other breeds was 63.1 ± 5.5, 33.7 ± 5.3, and 59.1 ± 6.3 months, respectively (p < .05). The PVP in dogs with medial implantation was 61.9 ± 4.7 months, and in those with lateral implantation was 45.4 ± 6.4 months (p = .034). Among the 132 eyes investigated, 48 (36.4%) lost vision by the last follow-up, and 18 eyes retained vision for more than 5 years. Two of the total number of eyes retained their vision for more than 8 years. CONCLUSIONS: The vision outcomes regarding the use of AGV for the management of canine glaucoma were favorable in dogs.

Rice Endosperm Protein Improves the Anti-Inflammatory Effects of High-Density Lipoprotein and Produces Lower Atherosclerotic Lesion Accelerated by the Renal Mass Reduction than Casein in a Mouse Model.

Chronic kidney disease (CKD) impairs the anti-inflammatory effects of high-density lipoprotein (HDL) and increases cardiovascular mortality. Though the potential role of dietary interventions to manage HDL is well studied, the clinical trials aimed to increase HDL levels have failed to reduce cardiovascular risk, rendering HDL function to be explored as a more relevant clinical parameter. This study investigates the effects of rice endosperm protein (REP), a plant-based protein, on the anti-inflammatory properties of HDL and renal injury-driven atherosclerosis in comparison with casein, an animal protein.Ten-week-old apolipoprotein E-deficient hyperlipidemic mice underwent uninephrectomy. The mice (n = 6 each) were pair-fed a normal casein-based diet or a REP-based diet (both with 20.0% protein content) for seven weeks. Atherosclerotic lesions were detected by en face Sudan IV staining of the aorta.The number and sizes of the atherosclerotic lesions were significantly lower in the REP-based diet-fed group than the casein-based diet-fed group (p = 0.038). However, the REP-based diet neither elicited an ameliorative effect on kidney function or histology nor impacted the cholesterol profiles. Furthermore, HDL from the REP-based diet-fed mice significantly suppressed the inflammatory cytokine response of human umbilical vein endothelial cells than that from the casein-based diet-fed mice (MCP-1, p = 0.010; IL-6, p = 0.011; IL-1ß, p = 0.028).The REP-based diet has a higher potential to lessen the atherosclerotic lesions accelerated by renal mass reduction than a casein-based diet, which could be associated with the anti-inflammatory effects of HDL.

Measurement of Plasma Glucagon Levels Using Mass Spectrometry in Patients with Type 2 Diabetes on Maintenance Hemodialysis.

BACKGROUND: Recently, attention has been focused on the effect of glucagon on blood glucose variability. The dynamics of glucagon have attracted attention as a new target in the treatment of diabetes patients. However, the dynamics of glucagon in hemodialysis (HD) patients with type 2 diabetes mellitus (T2DM) remain unclear. OBJECTIVES: The aim of this study was to assess the dynamics of glucagon in HD patients with T2DM. MATERIALS AND METHODS: We measured plasma glucagon in HD patients with T2DM by liquid chromatography-high-resolution mass spectrometry (LC-HRMS), sandwich enzyme-linked immunosorbent assay (ELISA), and radioimmunoassay (RIA). The glucagon levels measured by each method were compared. We used the glucagon levels determined by our developed LC-HRMS method as the standard in this study. RESULTS: Plasma glucagon levels measured by LC-HRMS before HD were significantly higher than those measured after HD. Plasma glucagon levels measured using sandwich ELISA had a significantly higher correlation with those measured using LC-HRMS compared with RIA. CONCLUSIONS: This was the first study to assess glucagon levels in HD patients with T2DM using LC-HRMS, which is considered a highly accurate method. Sandwich ELISA was shown to measure glucagon levels accurately as well.

Urinary FABP1 is a biomarker for impaired proximal tubular protein reabsorption and is synergistically enhanced by concurrent liver injury.

Urinary fatty acid binding protein 1 (FABP1, also known as liver-type FABP) has been implicated as a biomarker of acute kidney injury (AKI) in humans. However, the precise biological mechanisms underlying its elevation remain elusive. Here, we show that urinary FABP1 primarily reflects impaired protein reabsorption in proximal tubule epithelial cells (PTECs). Bilateral nephrectomy resulted in a marked increase in serum FABP1 levels, suggesting that the kidney is an essential organ for removing serum FABP1. Injected recombinant FABP1 was filtered through the glomeruli and robustly reabsorbed via the apical membrane of PTECs. Urinary FABP1 was significantly elevated in mice devoid of megalin, a giant endocytic receptor for protein reabsorption. Elevation of urinary FABP1 was also observed in patients with Dent disease, a rare genetic disease characterized by defective megalin function in PTECs. Urinary FABP1 levels were exponentially increased following acetaminophen overdose, with both nephrotoxicity and hepatotoxicity observed. FABP1-deficient mice with liver-specific overexpression of FABP1 showed a massive increase in urinary FABP1 levels upon acetaminophen injection, indicating that urinary FABP1 is liver-derived. Lastly, we employed transgenic mice expressing diphtheria toxin receptor (DT-R) either in a hepatocyte- or in a PTEC-specific manner, or both. Upon administration of diphtheria toxin (DT), massive excretion of urinary FABP1 was induced in mice with both kidney and liver injury, while mice with either injury type showed marginal excretion. Collectively, our data demonstrated that intact PTECs have a considerable capacity to reabsorb liver-derived FABP1 through a megalin-mediated mechanism. Thus, urinary FABP1, which is synergistically enhanced by concurrent liver injury, is a biomarker for impaired protein reabsorption in AKI. These findings address the use of urinary FABP1 as a biomarker of histologically injured PTECs that secrete FABP1 into primary urine, and suggest the use of this biomarker to simultaneously monitor impaired tubular reabsorption and liver function. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Combination therapy of cisplatin with cilastatin enables an increased dose of cisplatin, enhancing its antitumor effect by suppression of nephrotoxicity.

Cisplatin, one of the most active anticancer agents, is widely used in standard chemotherapy for various cancers. Cisplatin is more poorly tolerated than other chemotherapeutic drugs, and the main dose-limiting toxicity of cisplatin is its nephrotoxicity, which is dose-dependent. Although less toxic methods of cisplatin administration have been established, cisplatin-induced nephrotoxicity remains an unsolved problem. Megalin is an endocytic receptor expressed at the apical membrane of proximal tubules. We previously demonstrated that nephrotoxic drugs, including cisplatin, are reabsorbed through megalin and cause proximal tubular cell injury. We further found that cilastatin blocked the binding of cisplatin to megalin in vitro. In this study, we investigated whether cilastatin could reduce cisplatin-induced nephrotoxicity without influencing the antitumor effects of cisplatin. Nephrotoxicity was decreased or absent in mice treated with cisplatin and cilastatin, as determined by kidney injury molecule-1 staining and the blood urea nitrogen content. Combined with cilastatin, a twofold dose of cisplatin was used to successfully treat the mice, which enhanced the antitumor effects of cisplatin but reduced its nephrotoxicity. These findings suggest that we can increase the dose of cisplatin when combined with cilastatin and improve the outcome of cancer patients.

Effects of the Once-Weekly DPP4 Inhibitor Omarigliptin on Glycemic Control in Patients with Type 2 Diabetes Mellitus on Maintenance Hemodialysis: A 24-Week Open-Label, Multicenter Randomized Controlled Study.

INTRODUCTION: Dipeptidyl peptidase 4 (DPP4) inhibitors are widely used in patients with type 2 diabetes mellitus (T2DM) on maintenance hemodialysis (HD), but the efficacy of the once-weekly DPP4 inhibitor omarigliptin is not known. METHODS: This prospective, randomized, open-label, parallel-group, non-inferiority/superiority, once-daily DPP4 inhibitor linagliptin-controlled, multicenter study examined glycemic control and safety of omarigliptin (UMIN000024284). Sample size was calculated to confirm non-inferiority in terms of changes in glycated hemoglobin (HbA1c). We enrolled 33 patients with T2DM on maintenance HD who had been treated with linagliptin for at least 3 months. The patients were randomized to receive omarigliptin (12.5 mg/week; n = 16) or linagliptin (5 mg/day; n = 17). Primary endpoints were changes in HbA1c and glycoalbumin (GA) over 24 weeks. RESULTS: Differences in the mean change in primary endpoint values between the omarigliptin and linagliptin groups were - 0.61% [- 1.14, - 0.09] for HbA1c, with a two-tailed upper 95% limit (i.e., one-tailed 97.5% upper limit) of 0.25%, below the non-inferiority limit, and - 1.67% [- 4.23, + 0.88] for GA, with a two-tailed upper 95% limit of 0.75%, above the non-inferiority limit. At 24 weeks, the omarigliptin group showed significantly greater reduction in HbA1c than the linagliptin group (- 0.2% ± 0.6% vs. 0.4% ± 0.8%, two-tailed p = 0.024) and significantly greater reduction in blood glucose after a single HD session (- 18.4 ± 31.4 mg/dL vs. 25.2 ± 59.5 mg/dL, respectively, two-tailed p = 0.019). No subjects in the omarigliptin group developed hypoglycemia. CONCLUSIONS: Our data showed that omarigliptin was non-inferior to linagliptin in glycemic control. Omarigliptin is feasible for glycemic control in patients with T2DM on maintenance HD. CLINICAL TRIALS REGISTRATION: UMIN000024284.

Acute neurological deterioration after surgical interruption of spinal dural arteriovenous fistulas: clinical characteristics, possible predictors, and treatment. Patient series.

BACKGROUND: Acute neurological deterioration develops paradoxically in some patients after obliteration of a spinal dural arteriovenous fistula (SDAVF), with thrombosis of the spinal cord veins as its primary cause. The authors aimed to clarify the clinical and radiological characteristics of acute deterioration to identify high-risk patients. They also discussed the optimal treatment for this complication. OBSERVATIONS: Ten patients with SDAVF presenting with congestive myelopathy who received microsurgical interruption were retrospectively reviewed. Severe myelopathy developed in three patients on postoperative days 1 to 3. Anticoagulation therapy was effective; however, discontinuing anticoagulants under residual spinal cord congestion caused redeterioration. These patients were characterized by significantly extended transit time on angiography and significant prolongation of spinal cord congestion. Acute deterioration exhibited a strong correlation with transit time (coefficient, 0.825; p = 0.006) and a strong correlation with spinal cord edema before surgery (coefficient, 0.656; p = 0.040). LESSONS: Acute deterioration after SDAVF treatment is likely to develop in patients with severe venous outflow impairment. Its pathology is prolonged spinal cord congestion caused by postoperative venous thrombosis and preexistent severe venous outflow impairment. Anticoagulation treatment should be continued for patients with acute deterioration until the resolution of spinal cord congestion is confirmed with magnetic resonance imaging.