Albumin fusion renders thioredoxin an effective anti-oxidative and anti-inflammatory agent for preventing cisplatin-induced nephrotoxicity.

BACKGROUND: A strategy for preventing cisplatin nephrotoxicity due to enhanced oxidative stress and inflammatory response is highly desirable. Thioredoxin-1 (Trx), an endogenous redox-active protein, has a short retention time in the blood. A long acting form of Trx, human serum albumin-Trx (HSA-Trx), was produced by recombinant HSA fusion and its effectiveness in preventing cisplatin nephrotoxicity was examined. METHODS: HSA-Trx was prepared in Pichia expression system. Cisplatin-induced nephropathy mouse model was established by a single administration of cisplatin. RESULTS: Compared to saline, Trx or N-acetylcysteine, an intravenous administration of HSA-Trx attenuated the cisplatin-induced elevation in serum creatinine, blood urea nitrogen and urinary N-acetyl-ß-d-glucosaminidase along with the decrease in creatinine clearance. HSA-Trx caused a substantial reduction in the histological features of renal tubular injuries and the apoptosis-positive tubular cells. Changes in superoxide, 8-OHdG, glutathione and nitrotyrosine levels indicated that HSA-Trx significantly suppressed renal oxidative stress. HSA-Trx also suppressed the elevation of TNF-α, IL-1ß and IL-6. Administered fluorescein isothiocyanate-labeled HSA-Trx was found partially localized in the proximal tubular cells whereas majority remained in the blood circulation. Specific cellular uptake and the scavenging of intracellular reactive oxygen species by HSA-Trx were observed in HK-2 cells. CONCLUSION: HSA-Trx could be a novel and effective approach for preventing cisplatin nephrotoxicity due to its prolonged anti-oxidative and anti-inflammatory action not only in extracellular compartment but also inside the proximal tubular cell. GENERAL SIGNIFICANCE: We report the renoprotective effect of HSA-Trx against cisplatin nephrotoxicity. This work would enhance developing therapeutics against acute kidney injuries including cisplatin nephrotoxicity.

Ulam type stability for von Bertalanffy growth model with Allee effect.

In many studies dealing with mathematical models, the subject is examining the fitting between actual data and the solution of the mathematical model by applying statistical processing. However, if there is a solution that fluctuates greatly due to a small perturbation, it is expected that there will be a large difference between the actual phenomenon and the solution of the mathematical model, even in a short time span. In this study, we address this concern by considering Ulam stability, which is a concept that guarantees that a solution to an unperturbed equation exists near the solution to an equation with bounded perturbations. Although it is known that Ulam stability is guaranteed for the standard von Bertalanffy growth model, it remains unsolved for a model containing the Allee effect. This paper investigates the Ulam stability of a von Bertalanffy growth model with the Allee effect. In a sense, we obtain results that correspond to conditions of the Allee effect being very small or very large. In particular, a more preferable Ulam constant than the existing result for the standard von Bertalanffy growth model, is obtained as the Allee effect approaches zero. In other words, this paper even improves the proof of the result in the absence of the Allee effect. By guaranteeing the Ulam stability of the von Bertalanffy growth model with Allee effect, the stability of the model itself is guaranteed, and, even if a small perturbation is added, it becomes clear that even a small perturbation does not have a large effect on the solutions. Several examples and numerical simulations are presented to illustrate the obtained results.

Regulation of Renin Expression by Β1-Integrin in As4.1 Juxtaglomerular Line Cells.

(1) Background: Renal dysfunction and hypertension are mutually aggravating factors; however, the details of their interaction remain unclear. In a study using renal tissue from diabetic rats, we found that ß1-integrin, a cell-substrate adhesion molecule, is specifically phosphorylated in juxtaglomerular cells that secrete renin, a blood pressure regulator. (2) Methods: A mouse juxtaglomerular cell line (As4.1 cells) was used for the following experiments: drug-induced promotion of ß1-integrin phosphorylation/dephosphorylation; knockdown of ß1-integrin and the cell adhesion molecule connexin-40 (a candidate for the main body of baroreceptor); and pressurization to atmospheric pressure + 100 mmHg. culture in hypotonic liquid medium. The expression of renin under these conditions was measured by qRT-PCR. (3) Results: Phosphorylation of ß1-integrin suppressed the expression of renin, while dephosphorylation conversely promoted it. ß1-integrin and connexin-40 knockdown both promoted the expression of renin. Pneumatic pressurization and hypotonic medium culture both decreased the expression of renin, which was restored by the knockdown of ß1-integrin. (4) Conclusions: ß1-integrin plays an inhibitory role in the regulation of the expression of renin, which may be controlled by phosphorylation and dephosphorylation. It is hypothesized that ß1-integrin and other adhesion factors regulate the expression of renin by altering the sensitivity of baroreceptors on the plasma membrane.

Regulation of Blood Pressure and Phosphorylation of ß1-integrin in Renal Tissue in a Rat Model of Diabetic Nephropathy.

OBJECTIVE: Induction of hypertension by diabetic nephropathy (DN) may be dependent on increased renin secretion from juxtaglomerular cells (JGC). To reveal that the mechanisms of cell adhesion and cell motility associated with ß1-integrin phosphorylation contribute to pressure sensing in JGC, we tested the ß1-integrin phosphorylation levels in renal tissue and the relationship between ß1-integrin phosphorylation and the expression of renin. METHODS: The DN rat model was generated by intravenous injection of streptozotocin (STZ, 60 mg/kg body weight). Immunohistochemistry and an imaging analysis were performed to detect and evaluate the ß1-integrin phosphorylation levels in renal tissue. Quantitative real-time polymerase chain reaction was also performed to evaluate renin mRNA levels. RESULTS: We found that the serine-785 and threonine-788/789 sites of ß1-integrin are specifically phosphorylated in macula densa and JGC, respectively, and that changes in their expression during the progression of DN are associated with the production of renin. Phosphorylation of these ß1-integrins increased or decreased with changes of the renin expression during the progression of DN. In particular, phosphorylation of threonine-788/789 was negatively correlated with the expression of renin. CONCLUSION: These findings suggest that the phosphorylation of ß1-integrin may contribute to the regulatory mechanism of renin production in JGC.

Favorable Effect on Blood Volume Control in Hemodialysis Patients with Type 2 Diabetes after Switching from Insulin Therapy to Liraglutide, a Human Glucagon-like Peptide-1 Analog--Results from a Pilot Study in Japan-.

OBJECTIVE: Hemodialysis patients are advised to limit the intake of foods in order to control volume status and body weight (BW). We report the clinical course of five Japanese hemodialysis patients with type 2 diabetes mellitus (T2DM) who were switched from insulin to liraglutide, and the efficacy of the treatment, especially in terms of changes in interdialysis weight gain (IDWG). METHODS: This retrospective pilot study included 5 Japanese hemodialysis patients with T2DM. Insulin and other oral hypoglycemic agents, if any, were discontinued before switching to liraglutide. The initial dose of liraglutide was set at 0.3 mg/day for more than 1 week, increased to 0.6 mg/day for more than 1 week and then, to 0.9 mg/day if needed. RESULTS: At baseline, the mean body mass index (BMI) was 23.2 ± 1.2 kg/m2 and mean IDWG was 2.0 ± 0.4 kg. The required dose of liraglutide ranged from 0.3 to 0.9 mg/day. At the end of 3-month treatment, liraglutide reduced HbA1c level, BMI, and IDWG. A significant decrease in cardiothoracic ratio was confirmed on chest radiography. CONCLUSION: Switching from insulin to liraglutide seems effective in hemodialysis patients with T2DM, especially in those with difficult blood fluid volume control associated with failure of dietary restriction.

The Prevalence of 25-hydroxyvitamin D Deficiency in Japanese Patients with Diabetic Nephropathy.

Objective The purpose of this study was to measure serum 25-hydroxyvitamin D [25(OH)D] levels in Japanese patients with diabetic nephropathy and determine the relationship between 25(OH)D concentrations and various factors. Methods The study subjects included 442 patients with type 2 diabetes. Their serum levels of creatinine, HbA1c, intact-parathyroid hormone, urinary albumin, 25(OH)D, and 1,25-dihydroxyvitamin D [1,25(OH)2D] were measured and their estimated glomerular filtration rate (eGFR) was determined. The patients were divided into four groups based on the risk for progression to chronic kidney disease (CKD): low, moderate, high, very high, based on their eGFR and their level of albuminuria. Results The median 25(OH)D level was 14.6 ng/mL; 11% of the patients had 25(OH)D deficiency (<10 ng/mL), and 2% of patients had active vitamin D deficiency, as defined by a 1,25(OH)2D level of <22 pg/mL. The serum 25(OH)D level was correlated with the serum 1,25(OH)2D level in patients with a very high risk for CKD, but not in those with a moderate or high risk for CKD. Conclusion Although the vitamin D levels of the Japanese patients with diabetic nephropathy and CKD were low, the prevalence of vitamin D deficiency, as defined by the 1,25(OH)2D level, was low. Albuminuria, younger age, and female gender were associated with a low 25(OH)D level. The serum level of 25(OH)D should be monitored to assess the vitamin D status of patients with nephropathy and CKD.

Association between insulin resistance and plasma amino acid profile in non-diabetic Japanese subjects.

AIMS/INTRODUCTION: Elevation of the branched-chain amino acids (BCAAs), valine, leucine and isoleucine; and the aromatic amino acids, tyrosine and phenylalanine, has been observed in obesity-related insulin resistance. However, there have been few studies on Asians, who are generally less obese and less insulin-resistant than Caucasian or African-Americans. In the present study, we investigated the relationship between homeostasis model assessment of insulin resistance (HOMA-IR) and plasma amino acid concentration in non-diabetic Japanese participants. MATERIALS AND METHODS: A total of 94 healthy men and women were enrolled, and plasma amino acid concentration was measured by liquid chromatography/mass spectrometry after overnight fasting. The associations between HOMA-IR and 20 amino acid concentrations, and anthropometric and clinical parameters of lifestyle-related diseases were evaluated. RESULTS: The mean age and body mass index were 40.1 ± 9.6 years and 22.7 ± 3.9, respectively. Significantly positive correlations were observed between HOMA-IR and valine, isoleucine, leucine, tyrosine, phenylalanine and total BCAA concentration. Compared with the HOMA-IR ≤ 1.6 group, the HOMA-IR > 1.6 group showed significantly exacerbated anthropometric and clinical parameters, and significantly elevated levels of valine, isoleucine, leucine, tyrosine, phenylalanine and BCAA. CONCLUSIONS: The present study shows that the insulin resistance-related change in amino acid profile is also observed in non-diabetic Japanese subjects. These amino acids include BCAAs (valine, isoleucine and leucine) and aromatic amino acids (tyrosine and phenylalanine), in agreement with previous studies carried out using different ethnic groups with different degrees of obesity and insulin resistance.

Long-term glycemic control in Japanese type 2 diabetes patients after switching treatment from twice-daily premixed insulin to once daily insulin glargine.

OBJECTIVE: To examine the clinical utility of once-daily insulin glargine, we studied the clinical course of patients who were switched to from twice-daily premixed insulin to once daily insulin glargine. METHODS: The study was conducted at Tokai University hospital in 20 patients with type 2 diabetes, whose treatment regimens were switched from twice-a-day premixed insulin formulation to once-a-day insulin glargine. Changes in various clinical indexes were studied during a 3-year period after the switch. We also compared the well-controlled group (hemoglobin A1c, HbA1c, levels maintained at less than 6.9%) and poorly-controlled group (HbA1c levels at 7.4% or higher). RESULTS: During the 3-year period, all patients showed significant decrease in HbA1c levels and tendency for reduced daily dose of insulin. Although both BMI and insulin dose tended to decrease in the well-controlled group, they increased in the poorly controlled group. CONCLUSION: The findings suggest that in type 2 diabetes, once-a-day insulin glargine could be more useful than twice-a-day premixed insulin formulation. Poor adherence was observed in the poorly-controlled group, namely lack of thoroughness in self-monitoring of blood glucose and adherence to diet and exercise therapy, thus emphasizing the importance of diabetes education.

Efficacy of long-acting insulin analog insulin glargine at high dosage for basal-bolus insulin therapy in patients with type 2 diabetes.

OBJECTIVE: Attempts to achieve strict glycemic control with basal-bolus insulin therapy required increased dosages of neutral protamine Hagedorn (NPH) insulin. However, high dosage of NPH insulin often occurs nocturnal hypoglycemia. Insulin glargine can simulate normal basal insulin secretion with its flat time-action profiles. To confirm the efficacy of insulin glargine we investigated the type 2 diabetic patients on basal-bolus insulin therapy whose basal insulin was switched from NPH insulin to insulin glargine. METHODS: The Japanese 400 patients with type 2 diabetes on basal-bolus insulin therapy whose basal insulin was switched from NPH insulin to insulin glargine were followed-up. After the switching, the basal insulin was increased with reference to the self-monitoring of blood glucose results, with the aim of maintaining fasting blood sugar (FBS) level at 110 mg/dL, and simultaneously reducing the bolus insulin dosage to maintain the total daily insulin dosage. RESULTS: We were able to lower FBS significantly with almost no serious hypoglycemia. HbA1c also improved significantly. The improvements in FBS and HbA1c levels did not require a significant increase in the total insulin dosage. CONCLUSION: Our results suggest that basal insulin supplementation using insulin glargine is a useful method to control not only FBS but also HbA1c.

Effectiveness of basal-supported oral therapy (BOT) using insulin glargine in patients with poorly controlled type 2 diabetes.

OBJECTIVE: To determine the clinical usefulness of basal-supported oral therapy (BOT) using insulin glargine in Japanese patients with type 2 diabetes. METHODS: We compared HbA1c levels, body weight, and insulin doses before the introduction of BOT and in the final month of the observation period in 122 patients with type 2 diabetes who received BOT with insulin glargine between October 2007 and July 2009. To exclude the possible effects of seasonal changes in glycemic control, 57 of the 122 patients were followed-up for one year and examined for changes in HbA1c levels, body weight, and insulin dose. RESULTS: Examination of all cases (n=122) showed a significant decrease in HbA1c (before BOT: 8.7±1.8, after: 7.1±1.1%), but no significant change in body weight (before: 63.1±16.1, after: 63.8±17.0 kg). The mean observation period was 10.5±6.4 months. Insulin doses were significantly increased during the study. HbA1c levels improved significantly in patients on non-insulin-secreting drugs (biguanide, α-glucosidase inhibitor and thiazolidine derivatives) than those on insulin-secreting drugs (SU agents and glinides). CONCLUSION: BOT with insulin glargine is a useful strategy that can achieve good glycemic control in clinical practice without causing serious hypoglycemia. The introduction of BOT before exhaustion of pancreatic ß cells may increase its effectiveness.