The IGF-1 receptor has become a therapeutic target for the treatment of cancer. The efficacy of OSI-906 (linstinib), a dual inhibitor of IGF-1 receptor and insulin receptor, for solid cancers has been examined in clinical trials. The effects of OSI-906, however, on the blood glucose levels and pancreatic β-cell functions have not yet been reported. We investigated the impact of OSI-906 on glycemic control, insulin secretion, β-cell mass, and β-cell proliferation in male mice. Oral administration of OSI-906 worsened glucose tolerance in a dose-dependent manner in the wild-type mice. OSI-906 at a dose equivalent to the clinical daily dose (7.5 mg/kg) transiently evoked glucose intolerance and hyperinsulinemia. Insulin receptor substrate (IRS)-2-deficient mice and mice with diet-induced obesity, both models of peripheral insulin resistance, exhibited more severe glucose intolerance after OSI-906 administration than glucokinase-haploinsufficient mice, a model of impaired insulin secretion. Phloridzin improved the hyperglycemia induced by OSI-906 in mice. In vitro, OSI-906 showed no effect on insulin secretion from isolated islets. After daily administration of OSI-906 for a week to mice, the β-cell mass and β-cell proliferation rate were significantly increased. The insulin signals in the β-cells were apparently unaffected in those mice. Taken together, the results suggest that OSI-906 could exacerbate diabetes, especially in patients with insulin resistance. On the other hand, the results suggest that the β-cell mass may expand in response to chemotherapy with this drug.
Type 2 diabetes mellitus (DM) animal models have provided ample opportunity for investigating pathogenesis, as well as to evaluate novel treatment and prevention options for the disease. Because the domestic cat shares a similar environment with humans, it is also confronted with many similar risk factors for diabetes, such as physical inactivity and obesity. Obesity is a significant risk factor for diabetes in cats, and as such, the domestic cat may serve as an ideal model for investigating obesity induced insulin resistance. This study determined changes in insulin signaling genes within insulin sensitive tissues of obese felines. Quantitative RT-PCR was performed to determine mRNA levels of three important insulin signaling genes which have been implicated with insulin resistance: insulin receptor substrate (IRS)-1, IRS-2, and phosphatidylinositol 3'-kinase (PI3-K) p85alpha. Obese cats had significantly lower IRS-2 and PI3-K p85alpha mRNA levels in liver and skeletal muscle as compared to control cats. This down regulation of insulin signaling genes in obese cats mirrors that of obese humans and rodents suffering from insulin resistance. Interestingly, preprandial blood tests indicated that our obese cats were no different from control cats with regards to glucose tolerance and insulin resistance, thus indicating that the obese cats used in our study had a moderate level of obesity. Therefore, insulin signaling gene alterations were occurring in insulin sensitive tissues of moderately obese felines before glucose intolerance was clinically evident. As such, the monitoring of key insulin signaling genes may have some important diagnostic value to determine the risk level and degree of obesity induced insulin resistance.
It is well known the primary aldosteronism (PA) is most common endocrinological hypertension and accounted for 10% among all hypertension population, and it develops cardiovascular disease more frequently than blood pressure matched essential hypertension. Those patients with bilateral hyperaldosteronism, called idiopathic hyperaldosteronism (IHA), or unwilling for surgical treatment are treated by mineralcorticoid receptor antagonists (MRAs). Although it had been unclear how titrate MRAs to prevent atherosclerotic cardiovascular events, a managemental target for those patients was recently reported as plasma renin activity (PRA) ≥ 1.0 ng/ml/hr to prevent cardiovascular events (Hundemer GL, et. al. Lancet Diabetes Endocrinol. 2018 Jan;6(1):51-59). Thus, we investigated 77 cases of adrenal venous sampling performed patients with PA and followed up for 3 years in our hospital since 2007, including 24 males and 53 females, and their mean age was 56.3 ± 12.5 years old. All patients underwent AVS and showed bilateral hyperaldosteronism and treated with MRAs and followed up more than 3 years. We collected blood pressure, serum sodium and potassium concentration, estimated glomerular filtration ratio (eGFR), PRA, plasma aldosterone concentration (PAC), atherosclerotic parameter, such as mean intima media thickness (IMT), brachial-ankle pulse wave velocity (baPWV) and ankle-brachial index (ABI). We evaluated the relationship of those patients’ PRA and aldosterone to renin ratio (ARR) with eGFR, IMT, baPWV, and ABI. The change of mean IMT after 3 year-follow up were 0.03 ± 0.11 mm vs. 0.06 ± 0.09 mm for well controlled (PRA ≥ 1.0 ng/ml/hr) and poorly controlled (PRA < 1.0 ng/ml/hr), respectively, and no significant difference between them. In the other hand, the change of mean IMT after 3 year-follow up showed 0.03 ± 0.10 mm vs. 0.08 ± 0.10 mm for well controlled (PRA ≥ 1.0 ng/ml/hr and ARR <20) and poorly controlled (PRA < 1.0 ng/ml/hr or ARR ≥ 20), respectively, and the mean IMT increase was significantly lower in this group. The mean IMT increase showed significantly lower only with PRA ≥ 1.0 ng/ml/hr and ARR <20 rather than PRA ≥ 1.0 ng/ml/hr alone. In our results, both PRA ≥ 1.0 ng/ml/hr and ARR<20 are important to prevent or improve atherosclerosis, rather than only PRA ≥ 1.0 ng/ml/hr and should be titrated MRAs to achieve this target. In conclusion, our result revealed the titration of MRAs is important to prevent atherosclerotic cardiovascular event and not only PRA ≥ 1.0 ng/ml/hr, but both PRA and ARR <20 should be achieved.
Increasing evidence supports a more prominent role for postprandial glucose (PPG) regulation in the management of type 2 diabetes. Viscous dietary fibers including oat and barley β-glucan are one of the most effective classes of functional food ingredients for reducing PPG. We investigated the effect of high β-glucan barley on postprandial plasma glucose and C-peptide levels using a meal tolerance test and continuous glucose monitoring (CGM) in 15 subjects with normal glucose tolerance (NGT) and 29 type 2 diabetic patients. A 500-kcal meal tolerance test, using white rice alone (white rice) or white rice mixed with 50% of barley (Kirari-mochi®) containing 1.5-times β-glucan higher than usual barley (barley), was performed, and plasma glucose and C-peptide levels were measured every 30 minutes for 180 minutes. Daily glucose variability was measured using CGM over two days, while subjects consumed 1600-kcal or 1800-kcal test meals consisting of white rice or barley. Subsequently, a meal tolerance test with identical carbohydrate quantity (52g carbohydrate) with or without 1.8g of β-glucan, was performed in 7 diabetic patients. In NGT subjects and diabetic patients, the incremental area under the curve (AUC) of plasma glucose and C-peptide levels for 180 minutes after the meal tolerance test were significantly decreased following the consumption of barley compared to the consumption of white rice alone. The studies using CGM have demonstrated that the consumption of barley lead to a significant decrease in the 24-h standard deviation of blood glucose (24-h SDBG) and mean amplitude of glycemic excursion (MAGE) in diabetic patients. Similar results were obtained in subsequent tests with identical carbohydrate quantity but with β-glucan. In conclusion, these results suggest that high-β-glucan barley may contribute to decreased PPG levels and endogenous insulin secretion in both patients with type 2 diabetes and the subjects with NGT. Disclosure M. Higa: None. A. Hashimoto: None. M. Hayasaka: None. M. Hijikata: None. A. Ueda: None. K. Oda: None. D. Kato: None. K. Yamashita: None. T. Ichijo: None.
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