Koichiro Atsuda

Telmisartan but not candesartan affects adiponectin expression in vivo and in vitro.

To examine the effects of telmisartan on peroxisome proliferator–activated receptor γ activation, we compared the effects of telmisartan with those of candesartan on adipocytokines and glucose and lipid metabolism in vivo and in vitro. In vivo, 56 patients with both type 2 diabetes and hypertension were enrolled and randomized to receive either telmisartan (40 mg) or candesartan (8 mg) for 3 months. Serum adiponectin, HbA1c levels, lipid profiles and blood pressure were recorded at the beginning and 3 months later. In vitro, differentiated 3T3-L1 adipocytes were treated with telmisartan, candesartan, pioglitazone or vehicle for 24 h, and then adiponectin mRNA and protein levels were measured. The results showed that most of the metabolic parameters, including the lipid profiles, did not change significantly during the study in either group. However, the changes in serum adiponectin and plasma glucose over 3 months were significantly greater in the telmisartan group than in the candesartan group. In vitro, although the protein level of adiponectin was not significantly elevated, the mRNA expression of adiponectin was elevated 1.5-fold by telmisartan in 3T3-L1 adipocytes. Our findings suggest that telmisartan may have beneficial effects in type 2 diabetes beyond its antihypertensive effect.

Comparison of twice-daily injections of biphasic insulin lispro and basal-bolus therapy: glycaemic control and quality-of-life of insulin-naïve type 2 diabetic patients

Objective:  The aim of this study was to evaluate twice‐daily injections of biphasic insulin lispro vs. basal–bolus (BB) therapy with regard to quality‐of‐life (QOL) and glycaemic control in insulin‐naïve type 2 diabetic patients.

Dipeptidyl Peptidase-4 Greatly Contributes to the Hydrolysis of Vildagliptin in Human Liver

The major metabolic pathway of vildagliptin in mice, rats, dogs, and humans is hydrolysis at the cyano group to produce a carboxylic acid metabolite M20.7 (LAY151), whereas the major metabolic enzyme of vildagliptin has not been identified. In the present study, we determined the contribution rate of dipeptidyl peptidase-4 (DPP-4) to the hydrolysis of vildagliptin in the liver. We performed hydrolysis assay of the cyano group of vildagliptin using mouse, rat, and human liver samples. Additionally, DPP-4 activities in each liver sample were assessed by DPP-4 activity assay using the synthetic substrate H-glycyl-prolyl-7-amino-4-methylcoumarin (Gly-Pro-AMC). M20.7 formation rates in liver microsomes were higher than those in liver cytosol. M20.7 formation rate was significantly positively correlated with the DPP-4 activity using Gly-Pro-AMC in liver samples (r = 0.917, P < 0.01). The formation of M20.7 in mouse, rat, and human liver S9 fraction was inhibited by sitagliptin, a selective DPP-4 inhibitor. These findings indicate that DPP-4 is greatly involved in vildagliptin hydrolysis in the liver. Additionally, we established stable single expression systems of human DPP-4 and its R623Q mutant, which is the nonsynonymous single-nucleotide polymorphism of human DPP-4, in human embryonic kidney 293 (HEK293) cells to investigate the effect of R623Q mutant on vildagliptin-hydrolyzing activity. M20.7 formation rate in HEK293 cells expressing human DPP-4 was significantly higher than that in control HEK293 cells. Interestingly, R623Q mutation resulted in a decrease of the vildagliptin-hydrolyzing activity. Our findings might be useful for the prediction of interindividual variability in vildagliptin pharmacokinetics.

Insulin Degludec Requires Lower Bolus Insulin Doses Than Does Insulin Glargine in Japanese Diabetic Patients With Insulin-Dependent State:

Background: The study presents a comparison of the glucose-lowering effects, glycemic variability, and insulin doses during treatment with insulin degludec or insulin glargine. Methods: In this open-label, single-center, 2-way crossover study, 13 Japanese diabetic outpatients in the insulin-dependent state on basal-bolus therapy were assigned to receive either insulin glargine followed by insulin degludec, or insulin degludec followed by insulin glargine. Basal insulin doses were fixed in principle, and patients self-adjusted their bolus insulin doses. Seventy-two-hour continuous glucose monitoring was performed 2 weeks after switching the basal insulin. Results: Mean blood glucose (mg/dL) was not significantly different between insulin degludec and insulin glargine over 48 hours (141.8 ± 35.2 vs 151.8 ± 43.3), at nighttime (125.6 ± 40.0 vs 124.7 ± 50.4), or at daytime (149.3 ± 37.1 vs 163.3 ± 44.5). The standard deviation (mg/dL) was also similar (for 48 hours: 48.9 ± 19.4 vs 50.3 ± 17.3; nighttime: 18.7 ± 14.3 vs 13.7 ± 6.7; daytime: 49.3 ± 20.0 vs 44.3 ± 17.7). Other indices of glycemic control, glycemic variability, and hypoglycemia were similar for both insulin analogs. Total daily insulin dose (TDD) and total daily bolus insulin dose (TDBD) were significantly lower with insulin degludec than with insulin glargine (TDD: 0.42 ± 0.20 vs 0.46 ± 0.22 U/kg/day, P = .028; TDBD: 0.27 ± 0.13 vs 0.30 ± 0.14 U/kg/day, P = .036). Conclusions: Insulin degludec and insulin glargine provided effective and stable glycemic control. Insulin degludec required lower TDD and TDBD in this population of patients.

The Synthesis of 7-Substituted-3-dinitrostyryl Cephalosporins and Their Ability for Detecting Extended Spectrum β-Lactamases (ESBLs)

AbstractWe synthesized 7-substituted-3-(2,4-dinitrostyryl)cephalosporin derivatives which were Nitrocefin analogs, for detecting extended spectrum β-lactamase (ESBL) specifically. HMRZ-86 which has carboxypropyloxyimino group on 7-aminothiazolacetamide substituent were not hydrolyzed by class A, C and D β-lactamases, but it was hydrolyzed by ESBL and metallo β-lactamase (class B), then its color changed from yellow to red. The hydrolysis of metallo β-lactamase was inhibited by adding sodium mercapto acetic acid (SMA). Therefore HMRZ-86 is a useful chromogenic agent to detect ESBL specifically.

Vildagliptin and its metabolite M20.7 induce the expression of S100A8 and S100A9 in human hepatoma HepG2 and leukemia HL-60 cells

Vildagliptin is a potent, orally active inhibitor of dipeptidyl peptidase-4 (DPP-4) for the treatment of type 2 diabetes mellitus. It has been reported that vildagliptin can cause hepatic dysfunction in patients. However, the molecular-mechanism of vildagliptin-induced liver dysfunction has not been elucidated. In this study, we employed an expression microarray to determine hepatic genes that were highly regulated by vildagliptin in mice. We found that pro-inflammatory S100 calcium-binding protein (S100) a8 and S100a9 were induced more than 5-fold by vildagliptin in the mouse liver. We further examined the effects of vildagliptin and its major metabolite M20.7 on the mRNA expression levels of S100A8 and S100A9 in human hepatoma HepG2 and leukemia HL-60 cells. In HepG2 cells, vildagliptin, M20.7, and sitagliptin – another DPP-4 inhibitor – induced S100A9 mRNA. In HL-60 cells, in contrast, S100A8 and S100A9 mRNAs were significantly induced by vildagliptin and M20.7, but not by sitagliptin. The release of S100A8/A9 complex in the cell culturing medium was observed in the HL-60 cells treated with vildagliptin and M20.7. Therefore, the parental vildagliptin- and M20.7-induced release of S100A8/A9 complex from immune cells, such as neutrophils, might be a contributing factor of vildagliptin-associated liver dysfunction in humans.

Acquired resistance to gemcitabine and cross-resistance in human pancreatic cancer clones.

The efficacy of gemcitabine (GEM), a standard treatment agent for pancreatic cancer, is insufficient because of primary or acquired resistance to this drug. Patients with tumors intrinsically sensitive to GEM gradually acquire resistance and require a shift to second agents, which are associated with the risk of cross-resistance. However, whether cross-resistance is actually present has long been disputed. Using six GEM-resistant and four highly GEM-resistant clones derived from the pancreatic cancer cell line BxPC-3, we determined the resistance of each clone and parent cell line to GEM and four anticancer agents (5-FU, CDDP, CPT-11, and DTX). The GEM-resistant clones had different resistances to GEM and other agents, and did not develop a specific pattern of cross-resistance. This result shows that tumor cells are heterogeneous. However, all highly GEM-resistant clones presented overexpression of ribonucleotide reductase subunit M1 (RRM1), a target enzyme for metabolized GEM, and showed cross-resistance with 5-FU. The expression level of RRM1 was high; therefore, resistance to GEM was high. We showed that a tumor cell acquired resistance to GEM, and cross-resistance developed in one clone. These results suggest that only cells with certain mechanisms for high-level resistance to GEM survive against selective pressure applied by highly concentrated GEM. RRM1 may be one of the few factors that can induce high resistance to GEM and a suitable therapeutic target for GEM-resistant pancreatic cancer.

Two-way crossover comparison of insulin glargine and insulin detemir in basal-bolus therapy using continuous glucose monitoring

Objective: This study aimed to compare the glucose-lowering effect and glycemic variability of insulin glargine with those of insulin detemir. Material and methods: This was an open-label, single-center, randomized, two-way crossover study in patients with diabetes on basal-bolus insulin therapy, with neutral protamine Hagedorn (NPH) insulin as basal insulin. Patients switched from NPH insulin to a course either of insulin glargine followed by insulin detemir, or insulin detemir followed by insulin glargine, continuing the same dose of the prior bolus of insulin. To evaluate the glucose-lowering effect, daily glycemic profiles were recorded for 72 hours by continuous glucose monitoring (CGM) in an outpatient setting. The mean amplitude of glycemic excursions, standard deviation (SD), and the mean of daily difference (MODD) were used to assess intraday and day-to-day glycemic variability. Results: Eleven patients were enrolled and nine completed the study. Mean blood glucose calculated from CGM values was significantly lower with insulin glargine compared with insulin detemir (9.6 ± 2.4 mmol/L versus 10.4 ± 2.8 mmol/L, P = 0.038). The SD was significantly lower with insulin glargine versus insulin detemir (2.5 ± 0.9 mmol/L vs 3.5 ± 1.6 mmol/L, P = 0.011). The MODD value was significantly lower with insulin glargine than with insulin detemir (2.2 ± 1.1 mmol/L vs 3.6 ± 1.7 mmol/L, P = 0.011). There was no significant difference between the two insulin analogs in terms of hypoglycemia. Conclusion: This study suggests that insulin glargine leads to more effective and more stable glycemic control than the same dose of insulin detemir.

Lansoprazole binding to the neutrophils in dextran sulfate sodium-induced rat colitis.

To clarify the effector sites of lansoprazole in the colonic mucosa during the formation of colitis, dextran sulfate sodium-induced colitis was induced by the oral administration of 3% aqueous solution for 3 and 7 days. The effector sites of [3H]lansoprazole were examined by the intra-aortic infusion of the radiolabelled compound and the autoradiographic tracing of water-soluble compounds. As a result, the [3H]lansoprazole binding in the control rat colon was negligible, while in dextran sulfate sodium-treated rats specific binding sites of [3H]lansoprazole were recognized in the cytoplasm of the mesenchymal cells, and most of them coincided with polymorphonuclear leucocytes and macrophages.

Human Nitrilase-like Protein Does Not Catalyze the Hydrolysis of Vildagliptin

Nitrilase, which is found in plants and many types of bacteria, is known as the enzyme that catalyzes hydrolysis of a wide variety of nitrile compounds. While human nitrilase-like protein (NIT), which is a member of the nitrilase superfamily, has two distinct isozymes, NIT1 and NIT2, their function has not been well understood. In this study, we investigated whether human NIT1 and NIT2 are involved in the hydrolysis of drugs using vildagliptin as a substrate. We performed Western blot analysis using human liver samples to examine protein expression of human NIT in the liver, finding that human NIT1 and NIT2 were highly expressed in the liver cytosol. We established stable single expression systems of human NIT1 and NIT2 in HEK293 cells to clarify the contribution of human NIT to hydrolysis of vildagliptin. Although the formation of a carboxylic acid metabolite of vildagliptin (M20.7) was observed in human liver samples, M20.7 was not formed by incubating vildagliptin with HEK293 cells expressing human NIT1 or NIT2. This suggests that human NIT1 or NIT2 is not involved in the metabolism of vildagliptin. Further investigation using other drugs is needed to clarify the contribution of human NIT to drug metabolism.