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Sample records for premixed human insulin

  1. Interactions of short-acting, intermediate-acting and pre-mixed human insulins with free radicals--Comparative EPR examination.

    PubMed

    Olczyk, Paweł; Komosinska-Vassev, Katarzyna; Ramos, Paweł; Mencner, Łukasz; Olczyk, Krystyna; Pilawa, Barbara

    2015-07-25

    Electron paramagnetic resonance (EPR) spectroscopy was used to examine insulins interactions with free radicals. Human recombinant DNA insulins of three groups were studied: short-acting insulin (Insuman Rapid); intermediate-acting insulins (Humulin N, Insuman Basal), and pre-mixed insulins (Humulin M3, Gensulin M50, Gensulin M40, Gensulin M30). The aim of an X-band (9.3GHz) study was comparative analysis of antioxidative properties of the three groups of human insulins. DPPH was used as a stable free radical model. Amplitudes of EPR lines of DPPH as the paramagnetic free radical reference, and DPPH interacting with the individual tested insulins were compared. For all the examined insulins kinetics of their interactions with free radicals up to 60 min were obtained. The strongest interactions with free radicals were observed for the short-acting insulin - Insuman Rapid. The lowest interactions with free radicals were characteristic for intermediate-acting insulin - Insuman Basal. The pre-mixed insulins i.e. Humulin M3 and Gensulin M50 revealed the fastest interactions with free radicals. The short acting, intermediate acting and premixed insulins have been found to be effective agents in reducing free radical formation in vitro and should be further considered as potential useful tools in attenuation of oxidative stress in diabetic patients. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. PROGENS-HbA1c study: safety and effectiveness of premixed recombinant human insulin (Gensulin M30)

    PubMed Central

    Walicka, Magdalena; Jóźwiak, Jacek; Rzeszotarski, Jacek; Zarzycka-Lindner, Grażyna; Zonenberg, Anna; Bijoś, Paweł; Masierek, Małgorzata

    2016-01-01

    Introduction Insulin analogues have gained widespread popularity. However, in many countries the use of these drugs is limited by their relatively high cost, so there is still a need for more cost-effective human insulin therapies. The aim of the study was to assess the effectiveness and safety of the premixed recombinant human insulin (rhuI) Gensulin M30 in a real-life setting. Material and methods The study group consisted of 4257 patients (2196 female, 2061 male) with type 2 diabetes, aged 63.7 ±9.4, with body mass index (BMI) 30.3 ±4.5 kg/m2 and diabetes duration 9 ±5.5 years. All patients were treated with premixed rhuI Gensulin M30. In 91.7% of patients, insulin was used in combination with metformin. In 3.7% of patients, it was used with sulphonylureas. The patients were observed for a period of 6 months. Results The total insulin dose on visit 1 was 36.1 ±18.7 U (0.42 ±0.22 U/kg), and by the end of the study it reached 40.3 ±18.9 U (0.48 ±0.22 U/kg). A significant, continuous decrease of the levels of glycated hemoglobin (HbA1c), along with fasting and postprandial plasma glucose, was observed during the study period. The frequency of hypoglycemia increased slightly during the study, although these figures remained low, especially with regard to severe hypoglycemic episodes (0.02 episodes/patient/year). The lowest number of hypoglycemic episodes occurred in patients treated with insulin and metformin, while the highest number of episodes was observed in patients treated with insulin alone. No weight changes were noted in the patients during the study. Conclusions This study shows rhuI Gensulin M30 to be effective and safe in a real-life setting. PMID:27695488

  3. Comparison of Basal-Bolus and Premixed Insulin Regimens in Hospitalized Patients With Type 2 Diabetes

    PubMed Central

    Suarez, Lorena; Rodriguez, Maria Galiana; Sanchez, Cecilia; Dieguez, Marta; Riestra, Maria; Casal, Florentino; Delgado, Elias; Menendez, Edelmiro; Umpierrez, Guillermo E.

    2015-01-01

    OBJECTIVE Premixed insulin is a commonly prescribed formulation for the outpatient management of patients with type 2 diabetes. The safety and efficacy of premixed insulin formulations in the hospital setting is not known. RESEARCH DESIGN AND METHODS In a prospective, open-label trial, we randomized general medicine and surgery patients to receive a basal-bolus regimen with glargine once daily and glulisine before meals (n = 33) or premixed human insulin (30% regular insulin and 70% NPH insulin) twice daily (n = 39). Major outcomes included differences in daily blood glucose (BG) levels and frequency of hypoglycemic events (<70 mg/dL) between treatment groups. RESULTS At the first prespecified interim analysis, the study was stopped early because of an increased frequency of hypoglycemia >50% in patients treated with premixed human insulin. A total of 64% of patients treated with premixed insulin experienced one or more episodes of hypoglycemia compared with 24% in the basal-bolus group (P < 0.001). There were no differences in mean daily BG level after the first day of insulin treatment (175 ± 32 vs. 179 ± 43 mg/dL, P = 0.64) between groups. A BG target between 80 and 180 mg/dL before meals was achieved in 55.9% of BG readings in the basal-bolus group and 54.3% of BG readings in the premixed insulin group (P = 0.23). There was no difference in the length of hospital stay or mortality between treatment groups. CONCLUSIONS Inpatient treatment with premixed human insulin resulted in similar glycemic control but in significantly higher frequency of hypoglycemia compared with treatment with basal-bolus insulin regimen in hospitalized patients with diabetes. PMID:26459273

  4. Insulin Analogs or Premixed Insulin Analogs in Combination With Oral Agents for Treatment of Type 2 Diabetes

    PubMed Central

    Levy, Philip

    2007-01-01

    Context Type 2 diabetes is a progressive disease that is reaching epidemic proportions. Whereas most patients are initially managed with oral antidiabetic agents (OADs), the majority eventually require insulin to maintain glycemic control. The availability of insulin analogs (rapid-acting, long-acting, and premixed), with more predictable time-action profiles than human insulin preparations and simple-to-use insulin delivery devices, can help ease the transition to insulin therapy, which is often delayed until glycemic control has been inadequate for several years. >Objective To review the rationale for and strategies to initiate therapy with insulin analogs earlier in the course of type 2 diabetes. Practical barriers that must be overcome to successfully initiate insulin therapy in patients with type 2 diabetes are also briefly described. Design Narrative review of clinical evidence and current diabetes treatment guidelines. Setting and Patients Outpatients with type 2 diabetes inadequately managed with OADs alone. Interventions Three of the most common approaches to initiating insulin therapy with analogs are considered, with clinical evidence and detailed dosing algorithms provided. These approaches include: (1) addition of a basal insulin analog to oral therapy to reduce and stabilize fasting plasma glucose, (2) supplementation of oral therapy with a rapid-acting mealtime insulin analog to control postprandial glucose excursions, and (3) addition of or switching to a premixed insulin analog, which can be used to control both fasting and postprandial glucose in 1 injection. Conclusions Selection of appropriate insulin analog regimens and individualization of therapy can help patients achieve recommended glycemic goals while minimizing hypoglycemia. Education about the eventual need for insulin and improvements in insulin preparations and delivery systems at the time of diagnosis can also help overcome patient barriers. PMID:17955068

  5. Insulin aspart in a 30/70 premixed formulation. Pharmacodynamic properties of a rapid-acting insulin analog in stable mixture.

    PubMed

    Weyer, C; Heise, T; Heinemann, L

    1997-10-01

    To study the pharmacodynamic properties of a 30/70 premixed formulation of the rapid-acting insulin analog insulin aspart (B28Asp) and its protamine-retarded preparation (30/70 IA) in comparison with a respective mixture of soluble human insulin and NPH insulin (30/70 HI). In this single-center double-blind euglycemic glucose-clamp study, 24 healthy male volunteers (age, 26 +/- 2 years; BMI, 23.7 +/- 1.7 kg/m2) received single subcutaneous injections of 0.3 U/kg body wt of either 30/70 IA or 30/70 HI on 2 study days in randomized order. Glucose infusion rates (GIRs) were determined over a 24-h period after administration. The injection of 30/70 IA resulted in an earlier onset and more pronounced peak of action (tmax, 127 +/- 24 min; GIRmax 9.7 +/- 2.3 mg.kg-1.min-1) than 30/70 HI (tmax, 185 +/- 52 min; GIRmax, 7.4 +/- 1.7 mg.kg-1.min-1_ (P < 0.001). The metabolic activity of 30/70 IA (measured as the sum of the glucose infused) within the first 4 h after injection was 37% greater than that of 30/70 HI (P < 0.0001), while the total metabolic potencies over 24 h of both preparations were comparable. The 30/70 premixed formulation of insulin aspart shows a significantly greater metabolic effect in the first 4 h after subcutaneous injection than the 30/70 mixture of human insulin. Insulin aspart retains its pharmacodynamic properties in a premixed 30/70 formulation.

  6. Management of Type 2 diabetes in Ramadan: Low-ratio premix insulin working group practical advice

    PubMed Central

    Hassanein, Mohamed; Belhadj, Mohamed; Abdallah, Khalifa; Bhattacharya, Arpan D.; Singh, Awadhesh K.; Tayeb, Khaled; Al-Arouj, Monira; Elghweiry, Awad; Iraqi, Hinde; Nazeer, Mohamed; Jamoussi, Henda; Mnif, Mouna; Al-Madani, Abdulrazzaq; Al-Ali, Hossam; Ligthelm, Robert

    2014-01-01

    The challenge of insulin use during Ramadan could be minimized, if people with diabetes are metabolically stable and are provided with structured education for at least 2–3 months pre-Ramadan. Although, American diabetes association (ADA) recommendations 2010 and South Asian Consensus Guideline 2012 deal with management of diabetes in Ramadan and changes in insulin dosage, no specific guidance on widely prescribed low-ratio premix insulin is currently available. Hence, the working group for insulin therapy in Ramadan, after collective analysis, evaluation, and opinion from clinical practice, have formulated a practical advice to empower physicians with pre-Ramadan preparation, dose adjustment, and treatment algorithm for self-titration of low-ratio premix insulin. PMID:25364673

  7. Glycaemic control with modified intensive insulin injections (MII) using insulin pens and premixed insulin in children with type-1 diabetes: a randomized controlled trial.

    PubMed

    Soliman, Ashraf T; Omar, Magdi; Rizk, Mostafa M; El Awwa, Ahmad; AlGhobashy, Fatma M

    2006-08-01

    The objective of this study was to compare glycemic control and insulin dosage in children with type 1 diabetes treated by a modified intensified insulin therapy MII using insulin pens (and premixed and regular insulin) with those on conventional insulin therapy. This was a longitudinal, randomized controlled trial for 6 months or more. From a cohort of 125 children with previously diagnosed type-1 diabetes (more than a year after diagnosis) two groups were randomly selected Group AI (n=20) and Group B (n=20). Group AI children and 10 children with recently diagnosed type 1 diabetes (Group AII) were allocated to MII using regular insulin and premixed insulin (30/70 and 40/60 and 50/50). Group B patients continued their conventional insulin therapy for the whole period of the trial. The main outcome measures were glycemic control measured by mean blood glucose concentration and percentage of glycated haemoglobin and total daily insulin dose. Mean blood glucose concentrations before the three main meals, and at midnight, (148, 147, 179 and 127 mg/dl, respectively) were lower in children receiving intensified MII compared with those receiving conventional insulin therapy (192, 174, 194 and 179 mg/dl, respectively) (standardized mean difference 34+/-15 mg/dl), equivalent to a difference of 1.9+/-0.8 mmol/l. This improved control during MII was achieved with no change in the average daily insulin dose in group-AI. In group-AII insulin dose decreased significantly during their first 6 moths of treatment (honeymooning). Glycemic control is better during MII using insulin pens and premixed and regular insulin compared with conventional insulin therapy, without any significant change in insulin dose needed to achieve this level of control. The difference in glycemic control between the two methods is significant and could reduce the risk of micro-vascular complications.

  8. Glycemic control with insulin glargine plus insulin glulisine versus premixed insulin analogues in real-world practices: a cost-effectiveness study with a randomized pragmatic trial design.

    PubMed

    Levin, Philip A; Zhang, Quanwu; Mersey, James H; Lee, Francis Y; Bromberger, Lee A; Bhushan, Madhu; Bhushan, Rajat

    2011-07-01

    Cost can be an important consideration, along with safety and efficacy, in deciding the most appropriate treatment for patients with type 2 diabetes. Both basal-bolus and premixed insulin analogue regimens are widely used in clinical practice; however, limited information is available regarding cost-effectiveness. The goal of this study was to compare glycemic control, cost-effectiveness, and quality of life effects of insulin glargine plus insulin glulisine (glargine/glulisine) versus premixed insulin analogues in real-world clinical practice. Adults with type 2 diabetes (glycosylated hemoglobin [HbA(1c)] ≥7.0%) at 3 US endocrinology centers were randomly assigned to receive either glargine/glulisine or premixed insulin analogues and continued treatment following the centers' usual practice. HbA(1c), weight, insulin dose, concomitant oral antidiabetic drug (OAD) usage, and hypoglycemia were evaluated at baseline and 3, 6, and 9 months. Medication costs, including costs for all insulin or OAD regimens, were estimated using published wholesale acquisition costs. A total of 197 patients were randomized to receive glargine/glulisine therapy (n = 106) or premixed analogue therapy (n = 91). Overall, the mean age was 56 years, the mean duration of diabetes was 13 years, with a mean HbA(1c) of 9.25% and mean BMI of 35.8 kg/m(2) at baseline. Patients randomized to receive glargine/glulisine had a greater mean HbA(1c) reduction from baseline (-2.3%) than patients receiving a premixed analogue regimen (-1.7%). Adjusted mean follow-up HbA(1c) was 6.9% versus 7.5%, respectively (difference, -0.59%; P < 0.01). The glargine/glulisine group also used a lower mean number of OADs (0.86 vs 1.14; difference, -0.28; P = 0.04) but had a higher weight (240 vs 235 lb; difference, 4.55 lb; P = 0.03) than the premixed analogue group at follow-up. There were no significant differences in daily insulin dose and rates of hypoglycemia. Overall medication costs per 1.0% reduction in HbA(1c

  9. Subject-driven titration of biphasic insulin aspart 30 twice daily is non-inferior to investigator-driven titration in Chinese patients with type 2 diabetes inadequately controlled with premixed human insulin: A randomized, open-label, parallel-group, multicenter trial.

    PubMed

    Yang, Wenying; Zhu, Lvyun; Meng, Bangzhu; Liu, Yu; Wang, Wenhui; Ye, Shandong; Sun, Li; Miao, Heng; Guo, Lian; Wang, Zhanjian; Lv, Xiaofeng; Li, Quanmin; Ji, Qiuhe; Zhao, Weigang; Yang, Gangyi

    2016-01-01

    The present study was to compare the efficacy and safety of subject-driven and investigator-driven titration of biphasic insulin aspart 30 (BIAsp 30) twice daily (BID). In this 20-week, randomized, open-label, two-group parallel, multicenter trial, Chinese patients with type 2 diabetes inadequately controlled by premixed/self-mixed human insulin were randomized 1:1 to subject-driven or investigator-driven titration of BIAsp 30 BID, in combination with metformin and/or α-glucosidase inhibitors. Dose adjustment was decided by patients in the subject-driven group after training, and by investigators in the investigator-driven group. Eligible adults (n = 344) were randomized in the study. The estimated glycated hemoglobin (HbA1c) reduction was 14.5 mmol/mol (1.33%) in the subject-driven group and 14.3 mmol/mol (1.31%) in the investigator-driven group. Non-inferiority of subject-titration vs investigator-titration in reducing HbA1c was confirmed, with estimated treatment difference -0.26 mmol/mol (95% confidence interval -2.05, 1.53) (-0.02%, 95% confidence interval -0.19, 0.14). Fasting plasma glucose, postprandial glucose increment and self-measured plasma glucose were improved in both groups without statistically significant differences. One severe hypoglycemic event was experienced by one subject in each group. A similar rate of nocturnal hypoglycemia (events/patient-year) was reported in the subject-driven (1.10) and investigator-driven (1.32) groups. There were 64.5 and 58.1% patients achieving HbA1c <53.0 mmol/mol (7.0%), and 51.2 and 45.9% patients achieving the HbA1c target without confirmed hypoglycemia throughout the trial in the subject-driven and investigator-driven groups, respectively. Subject-titration of BIAsp 30 BID was as efficacious and well-tolerated as investigator-titration. The present study supported patients to self-titrate BIAsp 30 BID under physicians' supervision.

  10. Inhaled human insulin.

    PubMed

    Strack, Thomas R

    2006-04-01

    The benefit of subcutaneous insulin therapy in patients with diabetes is frequently limited due to difficulty in convincing patients of the importance of multiple daily insulin injections to cope effectively with meal-associated glycemic changes. Thus, the aim of achieving tight glycemic control, which is critical for reducing the risk of long-term diabetes-related complications, frequently remains elusive. The successful development of an inhalable insulin as a noninvasive alternative promises to change the management of diabetes. The first product to become available to patients is inhaled human insulin, a dry-powder formulation packaged into discrete blisters containing 1 or 3 mg of dry-powder human insulin and administered via a unique pulmonary inhaler device. It has recently been approved in both the United States and the European Union for the control of hyperglycemia in adult patients with type 1 or type 2 diabetes. The pharmacokinetic profile of inhaled human insulin closely mimics the natural pattern of insulin secretion, and resembles that of rapid-acting subcutaneous analogs. Similarly to rapid-acting subcutaneous analogs, inhaled human insulin has a more rapid onset of glucose-lowering activity compared to subcutaneous regular insulin, allowing it to be administered shortly before meals. It has a duration of glucose-lowering activity comparable to subcutaneous regular insulin and longer than rapid-acting insulin analogs. Inhaled human insulin effectively controls postprandial glucose concentrations in patients with type 1 or type 2 diabetes without increasing the risk of hypoglycemia, and even improves fasting glucose levels compared to subcutaneous insulin. Inhaled human insulin has an overall favorable safety profile. There are small reductions in lung function (1-1.5% of total lung forced expiratory volume in the first second [FEV1] capacity) after onset of treatment that are reversible in most patients if treatment is discontinued. Inhaled human

  11. Glycemic control and safety in Chinese patients with type 2 diabetes mellitus who switched from premixed insulin to insulin glargine plus oral antidiabetics: a large, prospective, observational study.

    PubMed

    Zhang, Bo; Zhao, Jing; Yang, Wenying

    2017-03-01

    In some circumstances, the premixed insulin should be switched to alternative therapy. The effectiveness and the safety of switching from premixed insulin to insulin glargine plus oral antidiabetic drugs (OADs) in Chinese patients with type 2 diabetes mellitus (T2DM) have not been clarified and, hence, will be assessed in this study. Chinese patients with T2DM (2013 men and women aged 18-75 years) who had received premixed insulin ± OADs for ≥3 months with glycated hemoglobin (HbA1c) ≤ 10% were enrolled in a prospective, observational study conducted at 53 hospitals across China. At baseline and at the discretion of the physician, patients switched from premixed insulin to insulin glargine plus OADs. Changes in HbA1c, fasting plasma glucose (FPG), 2-hour postprandial glucose (PPG), treatment satisfaction, and the incidence of hypoglycemia were assessed for 16 weeks. In total, 1850 patients completed the study. Mean HbA1c level for the group decreased significantly (from 7.8% ± 1.2% at week 1 to 7.0% ± 1.0% at week 16; P < .0001), and 55.2% of patients achieved HbA1c < 7% at week 16. Mean FPG and 2-hour PPG decreased significantly (-1.4 ± 2.2 and -2.1 ± 3.9 mmol/L, respectively; both P < .0001), whereas patient satisfaction improved significantly. Adverse events were reported in 18.7% of patients. Chinese patients with T2DM who switched from premixed insulin to insulin glargine plus OADs achieved significantly improved glycemic control and treatment satisfaction with a low incidence of hypoglycemia. Patients who are most likely to achieve the HbA1c target less than 7% are younger, have shorter disease duration, and have lower baseline HbA1c and FPG levels.

  12. Cost effectiveness of insulin glargine plus oral antidiabetes drugs compared with premixed insulin alone in patients with type 2 diabetes mellitus in Canada.

    PubMed

    Tunis, Sandra L; Sauriol, Luc; Minshall, Michael E

    2010-01-01

    Several treatment options are available for patients with type 2 diabetes mellitus who are making the transition from oral antidiabetes drugs (OADs) to insulin. Two options currently recommended by the Canadian Diabetes Association for initiating insulin therapy in patients with type 2 diabetes who are no longer responsive to OADs alone are insulin glargine plus OADs, and premixed insulin therapy only. Because of differences in efficacy, adverse events (such as hypoglycaemia) and acquisition costs, these two treatment options may lead to different long-term clinical and economic outcomes. To determine the cost effectiveness of insulin glargine plus OADs compared with premixed insulin without OADs in insulin-naive patients with type 2 diabetes in Canada. Using treatment effects taken from a published clinical trial, the validated IMS-CORE Diabetes Model was used to simulate the long-term cost effectiveness of insulin glargine with OADs, versus premixed insulin. Input treatment effects for the two therapeutic approaches were based on changes in glycosylated haemoglobin A(1c) (HbA(1c)) at clinical trial endpoint, and hypoglycaemia rates. The analysis was conducted from the perspective of the Canadian Provincial payer. Direct treatment and complication costs were obtained from published sources (primarily from Ontario) and reported in $Can, year 2008 values. All base-case costs and outcomes were discounted at 5% per year. Sensitivity analyses were conducted around key parameters and assumptions used in the study. Outcomes included direct medical costs associated with both treatment and diabetes-related complications. Cost-effectiveness outcomes included total average lifetime (35 years) costs, life expectancy (LE), QALYs and incremental cost-effectiveness ratios (ICERs). Base-case analyses showed that, compared with premixed insulin only, insulin glargine in combination with OADs was associated with a 0.051-year increase in LE and a 0.043 increase in QALYs. Insulin

  13. Premixed vs basal-bolus insulin regimen in Type 2 diabetes: comparison of clinical outcomes from randomized controlled trials and real-world data.

    PubMed

    Anyanwagu, U; Mamza, J; Gordon, J; Donnelly, R; Idris, I

    2017-09-25

    To evaluate the concordance between data derived from randomized controlled trial (RCT) and real-world estimates of HbA1c and weight change after 24 weeks of initiation of a basal-bolus compared with a premixed insulin regimen in people with Type 2 diabetes. Data eight RCTs were pooled after a systematic review of studies examining basal-bolus (n = 1893) or premixed (n = 1517) regimens. Real-world data were extracted from the UK primary care dataset for people on basal-bolus (n = 7483) or premixed insulin regimens (n=10 744). The mean differences between HbA1c and weight from baseline were calculated using t-tests, while analysis of variance was used to compare the two populations. Linear regression analyses were used to determine the predictors of this change. Both insulin regimens were associated with HbA1c reductions (real-world data -0.28%; RCT data, -1.4%) and weight gain (real-world data, +0.27 kg; RCT data, +2.96 kg) but there were no significant differences between basal-bolus and premixed insulin. Discordances in the pattern of treatment response were observed, however, between real-world and RCT data for both insulin regimens. For any given baseline HbA1c concentration, the change in HbA1c in the RCTs was greater than in real-world conditions and for those with baseline weight above ~60 kg, RCT data showed overall weight gain in contrast to slight weight loss in the real-world population. Lastly, for both randomized controlled trial and real-world populations, while greater baseline weight was associated with reduced response to treatment, the association was much steeper in the RCT than in the real-world population. In addition, greater baseline weight was associated with greater weight reductions after both premixed insulin and basal-bolus insulin regimens, although to a lesser extent with the latter. These results highlight discrepancies between real-world outcomes and RCT results with respect to starting basal-bolus insulin therapy (which is lower in

  14. Insulin Human Inhalation

    MedlinePlus

    Insulin inhalation is used in combination with a long-acting insulin to treat type 1 diabetes (condition in which the body does not produce insulin and therefore cannot control the amount of sugar ...

  15. Human insulin genome sequence map, biochemical structure of insulin for recombinant DNA insulin.

    PubMed

    Chakraborty, Chiranjib; Mungantiwar, Ashish A

    2003-08-01

    Insulin is a essential molecule for type I diabetes that is marketed by very few companies. It is the first molecule, which was made by recombinant technology; but the commercialization process is very difficult. Knowledge about biochemical structure of insulin and human insulin genome sequence map is pivotal to large scale manufacturing of recombinant DNA Insulin. This paper reviews human insulin genome sequence map, the amino acid sequence of porcine insulin, crystal structure of porcine insulin, insulin monomer, aggregation surfaces of insulin, conformational variation in the insulin monomer, insulin X-ray structures for recombinant DNA technology in the synthesis of human insulin in Escherichia coli.

  16. Adherence to premixed insulin in a prefilled pen compared with a vial/syringe in people with diabetes in Singapore.

    PubMed

    Cheen, Hua Heng McVin; Lim, Seng Han; Huang, Ming Chien; Bee, Yong Mong; Wee, Hwee Lin

    2014-07-01

    The real-world clinical effectiveness of exogenous insulin is limited by nonadherence. Various insulin delivery systems have been developed to help improve adherence, with prefilled pens gaining popularity among adult Singaporeans with diabetes. However, adherence to insulin in people with diabetes in Singapore and most of Asia has not been studied. This study aimed to compare adherence to premixed insulin formulated in a prefilled pen versus a vial/syringe and to identify predictors of adherence in 955 patients managed at the outpatient clinics of the largest acute care hospital in Singapore. In this retrospective longitudinal study, electronic medical and pharmacy refill records were used to determine adherence to insulin over 24 months, measured in terms of compliance and persistence. Compliance is expressed as the medication possession ratio (used as continuous and categorical variables), and persistence is reported as a dichotomous variable with a permissible refill gap of 30 days before discontinuation of therapy is considered. Multivariate linear or logistic regression analysis was used to identify predictors of adherence. Compared with prefilled pen users, vial/syringe users were older (mean [SD] age, 64.1 [10.6] vs 62.4 [11.9] years; P = 0.032), and more were undergoing polypharmacy (69.6% vs 54.1%; P < 0.001). The mean (SD) medication possession ratio was comparable in vial/syringe versus prefilled pen users (83.8% [26.9%] vs 86.0% [23.2%]; P = 0.266). Prefilled pen users were more persistent with therapy compared with vial/syringe users (odds ratio = 1.36; 95% CI, 1.01-1.86) after adjusting for sociodemographic and clinical covariates. Median time to discontinuation of therapy was comparable (vial/syringe vs prefilled pen: 409 vs 532 days; P = 0.076). Being managed by an endocrinologist and not receiving government subsidies were significant predictors of persistence. Compared with other studies that found strong associations between adherence and

  17. Protein Crystal Recombinant Human Insulin

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The comparison of protein crystal, Recombiant Human Insulin; space-grown (left) and earth-grown (right). On STS-60, Spacehab II indicated that space-grown crystals are larger and of greater optical clarity than their earth-grown counterparts. Recombiant Human Insulin facilitates the incorporation of glucose into cells. In diabetics, there is either a decrease in or complete lack of insulin, thereby leading to several harmful complications. Principal Investigator is Larry DeLucas.

  18. Protein Crystal Recombinant Human Insulin

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The comparison of protein crystal, Recombiant Human Insulin; space-grown (left) and earth-grown (right). On STS-60, Spacehab II indicated that space-grown crystals are larger and of greater optical clarity than their earth-grown counterparts. Recombiant Human Insulin facilitates the incorporation of glucose into cells. In diabetics, there is either a decrease in or complete lack of insulin, thereby leading to several harmful complications. Principal Investigator is Larry DeLucas.

  19. Switching from premixed insulin to glargine-based insulin regimen improves glycaemic control in patients with type 1 or type 2 diabetes: a retrospective primary care-based analysis

    PubMed Central

    Sharplin, Peter; Gordon, Jason; Peters, John R; Tetlow, Anthony P; Longman, Andrea J; McEwan, Philip

    2009-01-01

    Background Insulin glargine (glargine) and premixed insulins (premix) are alternative insulin treatments. This analysis evaluated glycaemic control in 528 patients with type 1 (n = 183) or type 2 (n = 345) diabetes, after switching from premix to a glargine-based regimen, using unselected general practice (GP) data. Methods Data for this retrospective observational analysis were extracted from a UK GP database (The Health Improvement Network). Patients were required to have at least 12 months of available data, before and after, switching from premix to a glargine-based regimen. The principal analysis was the change in HbA1c after 12 months of treatment with glargine; secondary analyses included change in weight, bolus usage and total daily insulin dose. Inconsistent reporting of hypoglycemic episodes precludes reliable assessment of this outcome. Multivariate analyses were used to adjust for baseline characteristics and confounding variables. Results Both cohorts showed significant reduction in mean HbA1c 12 months after the switch: by -0.67% (p < 0.001) in the type 1 cohort and by -0.53% (p < 0.001) in the type 2 cohort (adjusted data). The size of HbA1c improvement was positively correlated with baseline HbA1c; patients with a baseline HbA1c ≥ 10% had the greatest mean reduction in HbA1c, by -1.7% (p < 0.001) and -1.2% (p < 0.001), respectively. The proportion of patients receiving co-bolus prescriptions increased in the type 1 (mean 24.6% to 95.1%, p < 0.001) and type 2 (mean 16.2% to 73.9%, p < 0.001) cohorts. There was no significant change in weight in either cohort. Total mean insulin use increased in type 2 diabetes patients (from 0.67 ± 1.35 U/Kg to 0.88 ± 1.33 U/Kg, p < 0.001) with a slight decrease in type 1 diabetes patients (from 1.04 ± 2.51 U/Kg to 0.98 ± 2.58 U/Kg, p < 0.001). Conclusion In everyday practice, patients with type 1 or type 2 diabetes inadequately controlled by premix insulins experienced significant improvement in glycaemic

  20. Factors associated with reaching or not reaching target HbA1c after initiation of basal or premixed insulin in patients with type 2 diabetes.

    PubMed

    Scheen, A J; Schmitt, H; Jiang, H H; Ivanyi, T

    2017-02-01

    To evaluate factors associated with reaching or not reaching target glycated haemoglobin (HbA1c) levels by analysing the respective contributions of fasting hyperglycaemia (FHG), also referred to as basal hyperglycaemia, vs postprandial hyperglycaemia (PHG) before and after initiation of a basal or premixed insulin regimen in patients with type 2 diabetes. This post-hoc analysis of insulin-naïve patients in the DURABLE study randomised to receive either insulin glargine or insulin lispro mix 25 evaluated the percentages of patients achieving a target HbA1c of <7.0% (<53mmol/mol) per baseline HbA1c quartiles, and the effect of each insulin regimen on the relative contributions of PHG and FHG to overall hyperglycaemia. Patients had comparable demographic characteristics and similar HbA1c and FHG values at baseline in each HbA1c quartile regardless of whether they reached the target HbA1c. The higher the HbA1c quartile, the greater was the decrease in HbA1c, but also the smaller the percentage of patients achieving the target HbA1c. HbA1c and FHG decreased more in patients reaching the target, resulting in significantly lower values at endpoint in all baseline HbA1c quartiles with either insulin treatment. Patients not achieving the target HbA1c had slightly higher insulin doses, but lower total hypoglycaemia rates. Smaller decreases in FHG were associated with not reaching the target HbA1c, suggesting a need to increase basal or premixed insulin doses to achieve targeted fasting plasma glucose and improve patient response before introducing more intensive prandial insulin regimens. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  1. Improved sensitivity for insulin in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry by premixing alpha-cyano-4-hydroxycinnamic acid matrix with transferrin.

    PubMed

    Kobayashi, Tetsu; Kawai, Hiroshi; Suzuki, Takuo; Kawanishi, Toru; Hayakawa, Takao

    2004-01-01

    This report describes an enhancement of the signal intensities of proteins and peptides in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). When alpha-cyano-4-hydroxycinnamic acid (CHCA) premixed with human transferrin (Tf) was used as a matrix, the signal intensity of insulin was amplified to more than ten times that of the respective control in CHCA without Tf. The detection limit of insulin was 0.39 fmol on-probe in the presence of Tf, while it was 6.3 fmol in the absence of Tf. The signal intensity of insulin was also enhanced when the CHCA matrix was premixed with proteins other than Tf (80 kDa), such as horse ferritin (20 kDa), bovine serum albumin (BSA, 66 kDa), or human immunoglobulin G (150 kDa). The optimum spectrum of insulin was obtained when the added amount of protein was in the range 0.26-0.62 pmol, regardless of the molecular weight of the added protein. Tf and BSA outperformed the other tested proteins, as determined by improvements in the resulting spectra. When the mass spectra of several peptides and proteins were recorded in the presence of Tf or BSA, the signal intensities of large peptides such as glucagon were enhanced, though those of smaller peptides were not enhanced. In addition, the signal enhancement achieved with Tf and BSA was more pronounced for the proteins, including cytochrome C, than for the large peptides. This enhancement effect could be applied to improve the sensitivity of MALDI-TOFMS to large peptides and proteins. Copyright 2004 John Wiley & Sons, Ltd.

  2. Human insulin prepared by recombinant DNA techniques and native human insulin interact identically with insulin receptors.

    PubMed Central

    Keefer, L M; Piron, M A; De Meyts, P

    1981-01-01

    Human insulin synthesized from A and B chains separately produced in Escherichia coli from cloned synthetic genes (prepared by the Eli Lilly Research Laboratories, Indianapolis, IN) was characterized by examining its interaction with human cultured lymphocytes, human circulating erythrocytes in vitro, and isolated rat fat cells. The binding behavior of the biosynthetic insulin with human cells was indistinguishable from that of native human or porcine insulins, with respect to affinity, association and dissociation kinetics, negative cooperativity, and the down-regulation of lymphocyte receptors. Similarly, the biosynthetic insulin was as potent as the native insulins in stimulating lipogenesis in isolated rat fat cells. We also examined the receptor binding characteristics of 125I-labeled human and porcine insulins monoiodinated solely at Tyr-A14, which were obtained by means of high-performance liquid chromatography of the iodination reaction mixture (this material was prepared by B. Frank, Eli Lilly Research Laboratories). In all aspects studied, the pure [TyrA14-125I]iodoinsulins were superior as tracers to the monoiodoinsulin purified by the more conventional method of gel filtration. PMID:7015337

  3. Efficacy and safety of a premixed versus a basal-plus insulin regimen as intensification for type 2 diabetes by timing of the main meal.

    PubMed

    Gross, Jorge L; Rojas, Arturo; Shah, Sanjiv; Tinahones, Francisco J; Cleall, Simon; Rodríguez, Angel

    2016-06-01

    To describe the efficacy and safety of premixed insulin lispro protamine suspension 75%/insulin lispro solution 25% (LM25) twice daily (bid) versus basal insulin glargine plus prandial insulin lispro (IGL), both once daily, according to main meal timing. Data were obtained post hoc from a 24 week, randomized, open-label study comparing LM25 and IGL as insulin intensification in patients with type 2 diabetes inadequately controlled with once daily basal insulin glargine plus metformin and/or pioglitazone (ClinicalTrials.gov identifier: NCT01175824). Patients administered LM25 bid before breakfast and the evening meal, insulin glargine at bedtime and insulin lispro before the day's main meal (meal with the highest 2 hour postprandial glucose level during screening). Patients were grouped by main meal. Changes in glycosylated hemoglobin (HbA1c) and bodyweight were summarized using likelihood-based mixed models; hypoglycemia incidence was compared between treatments using Fisher's exact test. Overall, 476 patients (LM25, n = 236; IGL, n = 240) were randomized. In all main meal groups, with both insulin regimens, mean HbA1c significantly decreased from baseline to 24 weeks (p < 0.0001). Patients whose main meal was in the evening had a greater bodyweight increase with LM25 than with IGL (p = 0.015), and a smaller proportion of these patients experienced total (p = 0.027) and nocturnal (p = 0.006) hypoglycemia with LM25 compared with IGL. Patients whose main meal was lunch experienced more nocturnal hypoglycemia with LM25 than with IGL (p = 0.030). Study limitations include that this was a post hoc analysis and no assessments ensured that: SMBG results determined timing of the main meal, each patient's main meal remained unchanged throughout the study, or patients administered insulin lispro with that meal. Glycemic control improved in patients receiving either LM25 or IGL, irrespective of main meal timing. Both regimens can be used in

  4. Comparative assessment of the efficacy and safety of acarbose and metformin combined with premixed insulin in patients with type 2 diabetes mellitus.

    PubMed

    Wu, Honghua; Liu, Jie; Lou, Qingqing; Liu, Jing; Shen, Li; Zhang, Mingxia; Lv, Xiaofeng; Gu, Mingjun; Guo, Xiaohui

    2017-09-01

    This study, a subgroup analysis of the data from the Organization Program of DiabEtes INsulIN ManaGement study, aimed to compare the efficacy and safety profiles of acarbose and metformin used in combination with premixed insulin.This analysis included 80 and 192 patients taking only 1 oral antidiabetic drug, classified into acarbose (treated with acarbose + insulin) and metformin groups (treated with metformin + insulin), respectively. The efficacy and safety data were analyzed for within- and between-group differences. The clinical trial registry number was NCT01338376.The percentage of patients who achieved target hemoglobin A1c (HbA1c) <7% in the acarbose and metformin groups were 38.75% and 30.73%, respectively, after a 16-week treatment. The average HbA1c levels in the acarbose and metformin groups were comparable at baseline and decreased significantly in both groups at the end of the study. All 7 blood glucose decreased significantly in both groups at endpoint compared with that at baseline. Insulin consumption was higher in the metformin group in terms of total daily amount and units/kg body weight. Incidences of hypoglycemia were similar in both groups. Body weight changed significantly in both groups from baseline to endpoint, but with no significant difference between the groups. Mean scores of Morisky Medication Adherence Scale improved in both groups at endpoint.Combination of insulin with acarbose or metformin could improve glycemic control in patients with type 2 diabetes mellitus. Acarbose and metformin were found to be comparable in terms of efficacy, weight gain, and incidence of hypoglycemia.

  5. Effects of switching from prandial premixed insulin therapy to basal plus two times bolus insulin therapy on glycemic control and quality of life in patients with type 2 diabetes mellitus.

    PubMed

    Ito, Hiroyuki; Abe, Mariko; Antoku, Shinichi; Omoto, Takashi; Shinozaki, Masahiro; Nishio, Shinya; Mifune, Mizuo; Togane, Michiko

    2014-01-01

    The effects of switching from prandial premixed insulin therapy (PPT) injected three times a day to basal plus two times bolus insulin therapy (B2B) on glycemic control and quality of life were investigated in patients with type 2 diabetes mellitus. The clinical course was prospectively observed during the first 16 weeks after switching to B2B (insulin glargine plus insulin glulisine before breakfast and dinner) in 27 subjects previously treated with PPT using 50/50 premixed insulin. The Diabetes Treatment Satisfaction Questionnaire (DTSQ) was administered at the start and end of the study. The glycated hemoglobin (HbA1c) level (8.3% ± 1.8% to 8.2% ± 1.1%) and the DTSQ score did not change between the start and end of the study. An improvement in HbA1c level was found in nine (33%) subjects. The change in HbA1c showed a significant negative correlation with baseline HbA1c, and was significantly better in patients with a baseline HbA1c >8.0% than in those with an HbA1c ≤ 8.0% (-0.9 ± 2.0 versus 0.3 ± 0.6, respectively, P = 0.02). The change in DTSQ score representing treatment satisfaction was significantly greater in patients whose HbA1c level was improved than in those in whom it was not (2.7 ± 3.6 versus -0.8 ± 3.5, P = 0.04). B2B was noninferior to PPT with regard to HbA1c levels in patients with type 2 diabetes mellitus. B2B should be considered particularly for subjects whose glycemic control is poor despite PPT.

  6. Effects of switching from prandial premixed insulin therapy to basal plus two times bolus insulin therapy on glycemic control and quality of life in patients with type 2 diabetes mellitus

    PubMed Central

    Ito, Hiroyuki; Abe, Mariko; Antoku, Shinichi; Omoto, Takashi; Shinozaki, Masahiro; Nishio, Shinya; Mifune, Mizuo; Togane, Michiko

    2014-01-01

    Background The effects of switching from prandial premixed insulin therapy (PPT) injected three times a day to basal plus two times bolus insulin therapy (B2B) on glycemic control and quality of life were investigated in patients with type 2 diabetes mellitus. Methods The clinical course was prospectively observed during the first 16 weeks after switching to B2B (insulin glargine plus insulin glulisine before breakfast and dinner) in 27 subjects previously treated with PPT using 50/50 premixed insulin. The Diabetes Treatment Satisfaction Questionnaire (DTSQ) was administered at the start and end of the study. Results The glycated hemoglobin (HbA1c) level (8.3%±1.8% to 8.2%±1.1%) and the DTSQ score did not change between the start and end of the study. An improvement in HbA1c level was found in nine (33%) subjects. The change in HbA1c showed a significant negative correlation with baseline HbA1c, and was significantly better in patients with a baseline HbA1c >8.0% than in those with an HbA1c ≤8.0% (−0.9±2.0 versus 0.3±0.6, respectively, P=0.02). The change in DTSQ score representing treatment satisfaction was significantly greater in patients whose HbA1c level was improved than in those in whom it was not (2.7±3.6 versus −0.8±3.5, P=0.04). Conclusion B2B was noninferior to PPT with regard to HbA1c levels in patients with type 2 diabetes mellitus. B2B should be considered particularly for subjects whose glycemic control is poor despite PPT. PMID:24790413

  7. Insulin treatment of type 2 diabetes: considerations when converting from human insulin to insulin analogs.

    PubMed

    Griffin, Stacy

    2013-03-01

    Type 2 diabetes mellitus is a highly prevalent disease characterized by insulin resistance, hyperglycemia, and diminished pancreatic β-cell function. Conventional insulin products used to manage this disease include regular human insulin and intermediate-acting human insulin. However, due to several limitations imposed by human insulins, such as onset and duration of action that do not coincide with physiologic needs and increased risk of hypoglycemia, insulin analogs were developed. Because they more closely mimic the physiologic action of endogenous insulin, insulin analogs are associated with more effective glucose control, a lower risk of hypoglycemia, greater convenience, and, in some instances, less weight gain. Switching from human insulin to insulin analogs is easily accomplished. Several studies have demonstrated a high rate of success with patient-initiated, self-adjusted dosing algorithms compared to investigator/clinician-initiated dose adjustments. These studies and several other published guidelines on insulin analogs provide patients and clinicians with information pertaining to better treatment options and can help increase overall patient satisfaction.

  8. A Randomized Trial of Step-up Treatment with Premixed Insulin Lispro-50/50 vs. Aspart-70/30 in Patients with Type 2 Diabetes Mellitus.

    PubMed

    Domeki, Nozomi; Matsumura, Mihoko; Monden, Tsuyoshi; Nakatani, Yuki; Aso, Yoshimasa

    2014-12-01

    When insulin treatment is started in patients with type 2 diabetes mellitus (T2DM), there are many regimens that control serum glucose levels to a normal range. Basal-bolus insulin therapy is one of the most effective treatments for improving glycemic control to prevent the progression of diabetic microvascular complications. This study was conducted to determine whether step-up insulin treatment with premixed insulin aspart-30/70 (BIAsp 30) or lispro-50/50 (Mix50) in Japanese patients with type 2 diabetes mellitus could achieve better glycemic control. In this open label study, 72 insulin-naïve patients with poorly controlled T2DM (HbA1c ≥8.4%), who had been taking oral antidiabetic drugs for at least 12 months, were randomized to receive BIAsp 30 or Mix50 therapy. Patients started treatment of a pre-dinner injection of each type of insulin (Step 1). At 16 ± 2 weeks, a pre-breakfast injection of each type of insulin was added if HbA1c exceeded 7.4% (step 2). If patients had still not achieved HbA1c <7.4% after an additional 16 ± 2 weeks, a pre-lunch insulin injection was added (step 3). Hypoglycemic episodes were also recorded. The cumulative percentages of subjects who achieved HbA1c <7.4% were 36.1% (13/36) for both Mix50 and BIAsp 30 in step 1, 62.9% (23/36) for BIAsp 30 and 52.8% (19/36) for Mix50 in step 2, and 66.7% (24/36) in BIAsp 30 and 72.2% (26/36) in Mix50 in step 3. The achievement rates of HbA1c <7.4% were not statistically different between the two groups. A total of ten hypoglycemic episodes occurred in this study. However, there were no severe hypoglycemic episodes. All cases recovered by taking glucose and drinking juice. Mix50 step-up treatment has a clinical effect in achieving good glycemic control equal to that of BIAsp 30 treatment.

  9. Human blood-brain barrier insulin receptor.

    PubMed

    Pardridge, W M; Eisenberg, J; Yang, J

    1985-06-01

    A new model system for characterizing the human brain capillary, which makes up the blood-brain barrier (BBB) in vivo, is described in these studies and is applied initially to the investigation of the human BBB insulin receptor. Autopsy brains were obtained from the pathologist between 22-36 h postmortem and were used to isolate human brain microvessels which appeared intact on both light and phase microscopy. The microvessels were positive for human factor 8 and for a BBB-specific enzyme marker, gamma-glutamyl transpeptidase. The microvessels avidly bound insulin with a high-affinity dissociation constant, KD = 1.2 +/- 0.5 nM. The human brain microvessels internalized insulin based on acid-wash assay, and 75% of insulin was internalized at 37 degrees C. The microvessels transported insulin to the medium at 37 degrees C with a t1/2 = approximately 70 min. Little of the 125I-insulin was metabolized by the microvessels under these conditions based on the elution profile of the medium extract over a Sephadex G-50 column. Plasma membranes were obtained from the human brain microvessels and these membranes were enriched in membrane markers such as gamma-glutamyl transpeptidase or alkaline phosphatase. The plasma membranes bound 125I-insulin with and ED50 = 10 ng/ml, which was identical to the 50% binding point in intact microvessels. The human BBB plasma membranes were solubilized in Triton X-100 and were adsorbed to a wheat germ agglutinin Sepharose affinity column, indicating the BBB insulin receptor is a glycoprotein. Affinity cross-linking of insulin to the plasma membranes revealed a 127K protein that specifically binds insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. [Current concept of insulin therapy intensification, and the role of human regular insulin and rapid-acting insulin analogs in insulin treatment].

    PubMed

    Hamaguchi, Tomoya; Sadahiro, Katsuhiko; Satoh, Tomomi

    2015-03-01

    The evolution of insulin therapy from animal insulin to recombinant human regular insulin has improved diabetes treatment. Generating of rapid-acting insulin analogs, mimicking physiologic insulin action enables us to provide better control of post-prandial glucose level and lower incidence of hypoglycemia compared with human regular insulin. These rapid-acting insulin analogs show lower susceptibility of insulin precipitation and catheter occlusions, and are suitable for insulin pump therapy of continuous subcutaneous insulin infusion. Insulin lispro and insulin aspart are also applicable for diabetic patients with pregnancy, requiring excellent glycemic control. In some studies, stepwise addition of prandial insulin, as well as full basal-bolus regimen can improve glycemic control with less hypoglycemia. Treatment intensification with rapid-acting insulin analogs may offer a proper method to reach glycemic goals.

  11. Caffeine can decrease insulin sensitivity in humans.

    PubMed

    Keijzers, Gerben B; De Galan, Bastiaan E; Tack, Cees J; Smits, Paul

    2002-02-01

    Caffeine is a central stimulant that increases the release of catecholamines. As a component of popular beverages, caffeine is widely used around the world. Its pharmacological effects are predominantly due to adenosine receptor antagonism and include release of catecholamines. We hypothesized that caffeine reduces insulin sensitivity, either due to catecholamines and/or as a result of blocking adenosine-mediated stimulation of peripheral glucose uptake. Hyperinsulinemic-euglycemic glucose clamps were used to assess insulin sensitivity. Caffeine or placebo was administered intravenously to 12 healthy volunteers in a randomized, double-blind, crossover design. Measurements included plasma levels of insulin, catecholamines, free fatty acids (FFAs), and hemodynamic parameters. Insulin sensitivity was calculated as whole-body glucose uptake corrected for the insulin concentration. In a second study, the adenosine reuptake inhibitor dipyridamole was tested using an identical protocol in 10 healthy subjects. Caffeine decreased insulin sensitivity by 15% (P < 0.05 vs. placebo). After caffeine administration, plasma FFAs increased (P < 0.05) and remained higher than during placebo. Plasma epinephrine increased fivefold (P < 0.0005), and smaller increases were recorded in plasma norepinephrine (P < 0.02) and blood pressure (P < 0.001). Dipyridamole did not alter insulin sensitivity and only increased plasma norepinephrine (P < 0.01). Caffeine can decrease insulin sensitivity in healthy humans, possibly as a result of elevated plasma epinephrine levels. Because dipyridamole did not affect glucose uptake, peripheral adenosine receptor antagonism does not appear to contribute to this effect.

  12. A(1c) control in a primary care setting: self-titrating an insulin analog pre-mix (INITIATEplus trial).

    PubMed

    Oyer, David S; Shepherd, Mark D; Coulter, Franklin C; Bhargava, Anuj; Brett, Jason; Chu, Pei-Ling; Trippe, Bruce S

    2009-11-01

    To study glycemic control and hypoglycemia development upon initiation of insulin through a self-titration schedule in a 24-week trial, conducted with 4875 insulin-naïve patients with poorly controlled type 2 diabetes, predominantly in a primary care setting. Subjects initiated twice-daily biphasic insulin aspart 70/30 with 6 units prebreakfast and 6 units presupper, self-titrating according to self-measured blood glucose values. Subjects were randomized (1:1:1) to telephone counseling provided by a registered dietician: no counseling (NC), 1 counseling session (1C), or 3 sessions (3C). Mean baseline HbA(1c) (9.9% across groups) decreased approximately 2.5% to 7.49% + or - 1.48, 7.48% + or - 1.50, and 7.44% + or - 1.46 in the NC, 1C, and 3C groups, respectively. Within these groups, a hemoglobin A(1c) (HbA(1c)) value <7% was achieved by 40.2%, 41.6%, and 41.8% of subjects, respectively. Eight-point blood glucose profiles were substantially improved from baseline for all groups. Hypoglycemia was experienced by 10.2%-11.4% of the subjects in each group. Rates of minor and major hypoglycemia were low but decreased as dietary counseling increased (minor hypoglycemia: 56 vs 50 vs 45 episodes per 100 patient-years; major hypoglycemia, 9 vs 6 vs 4 episodes per 100 patient-years, for the NC vs 1C vs 3C groups, respectively; P <.001, 3C vs NC). Weight increased by 3.13, 3.40, and 2.88 kg for the NC, 1C, and 3C groups, respectively. In the primary care setting, self-titration of biphasic insulin aspart 70/30 was effective in achieving recommended HbA(1c) goals even with minimal dietary counseling.

  13. Insulin reciprocally regulates glucagon secretion in humans.

    PubMed

    Cooperberg, Benjamin A; Cryer, Philip E

    2010-11-01

    We tested the hypothesis that an increase in insulin per se, i.e., in the absence of zinc, suppresses glucagon secretion during euglycemia and that a decrease in insulin per se stimulates glucagon secretion during hypoglycemia in humans. We measured plasma glucagon concentrations in patients with type 1 diabetes infused with the zinc-free insulin glulisine on three occasions. Glulisine was infused with clamped euglycemia (∼95 mg/dl [5.3 mmol/l]) from 0 to 60 min on all three occasions. Then, glulisine was discontinued with clamped euglycemia or with clamped hypoglycemia (∼55 mg/dl [3.0 mmol/l]) or continued with clamped hypoglycemia from 60 to 180 min. Plasma glucagon concentrations were suppressed by -13 ± 3, -9 ± 3, and -12 ± 2 pg/ml (-3.7 ± 0.9, -2.6 ± 0.9, and -3.4 ± 0.6 pmol/l), respectively, (all P < 0.01) during zinc-free hyperinsulinemic euglycemia over the first 60 min. Glucagon levels remained suppressed following a decrease in zinc-free insulin with euglycemia (-14 ± 3 pg/ml [-4.0 ± 0.9 pmol/l]) and during sustained hyperinsulinemia with hypoglycemia (-14 ± 2 pg/ml [-4.0 ± 0.6 pmol/l]) but increased to -3 ± 3 pg/ml (-0.9 ± 0.9 pmol/l) (P < 0.01) following a decrease in zinc-free insulin with hypoglycemia over the next 120 min. These data indicate that an increase in insulin per se suppresses glucagon secretion and a decrease in insulin per se, in concert with a low glucose concentration, stimulates glucagon secretion. Thus, they document that insulin is a β-cell secretory product that, in concert with glucose and among other signals, reciprocally regulates α-cell glucagon secretion in humans.

  14. Structural and functional changes in human insulin induced by methylglyoxal.

    PubMed

    Jia, Xuming; Olson, Douglas J H; Ross, Andrew R S; Wu, Lingyun

    2006-07-01

    Elevated methylglyoxal (MG) levels have been reported in insulin-resistance syndrome. The present study investigated whether MG, a highly reactive metabolite of glucose, induced structural and functional changes of insulin. Incubation of human insulin with MG in vitro yielded MG-insulin adducts, as evidenced by additional peaks observed on mass spectrometric (MS) analysis of the incubates. Tandem MS analysis of insulin B-chain adducts confirmed attachment of MG at an arginine residue. [3H]-2-deoxyglucose uptake by 3T3-L1 adipocytes was significantly and concentration-dependently decreased after the treatment with MG-insulin adducts, in comparison with the effect of native insulin at the same concentrations. A significant decrease of glucose uptake induced by MG-insulin adducts was also observed in L8 skeletal muscle cells. MG alone had no effect on glucose uptake or the transcriptional expression of insulin receptor. Unlike native insulin, MG-insulin adducts did not inhibit insulin release from pancreatic beta-cells. The degradation of MG-insulin through liver cells was also decreased. In conclusion, MG modifies insulin by attaching to internal arginine residue in beta-chain of insulin. The formation of this MG-insulin adduct decreases insulin-mediated glucose uptake, impairs autocrine control of insulin secretion, and decreases insulin clearance. These structural and functional abnormalities of insulin molecule may contribute to the pathogenesis of insulin resistance.

  15. [Studies on genetic engineering of human insulin-purification and characterization of human proinsulin and insulin].

    PubMed

    Guo, L H; Zhou, M Y; Shen, M H; Wang, E B; Liu, J F; Yu, Y J

    1992-06-01

    E. coli DH 5 alpha cells harboring a plasmid pWR 590-BCA 4 for fused human proinsulin production were cultured. The fused human proinsulin was isolated from the fermented cells and then subjected it to cleavage with BrCN. The cleaved product was then converted to crude proinsulin-S-sulfonate using oxidative sulfitolysis. The isolation of human proinsulin-S-sulfonate was accomplished by ion exchange chromatography on QAE-sephadex A-25, followed by gel filtration on sephadex G-50. The purified human proinsulin-S-sulfonate was folded using a disulfide interchange method. The folding mixture was then chromatographed on sephadex G-50 and purified proinsulin was obtained. The proinsulin was then converted to human insulin and C-peptide by a combination cleavage with trypsin and carboxypeptidase B. The total yield of human insulin was about 5 mg/L The Zinc insulin crystals were obtained with amorphous human insulin using citrate method. The amino acid composition N-terminal sequences as well as C-terminal amino acid residues are in agreement with expected results. The hypoglycemic activity of purified human insulin is 26-27 U/mg, as judged by mouse convulsion assay, and the RIA activity is about 99% of that of porcine insulin.

  16. Multiple tube premixing device

    DOEpatents

    Uhm, Jong Ho; Naidu, Balachandar; Ziminksy, Willy Steve; Kraemer, Gilbert Otto; Yilmaz, Ertan; Lacy, Benjamin; Stevenson, Christian; Felling, David

    2013-08-13

    The present application provides a premixer for a combustor. The premixer may include a fuel plenum with a number of fuel tubes and a burner tube with a number of air tubes. The fuel tubes extend about the air tubes.

  17. Multiple tube premixing device

    DOEpatents

    Uhm, Jong Ho; Varatharajan, Balachandar; Ziminsky, Willy Steve; Kraemer, Gilbert Otto; Yilmaz, Ertan; Lacy, Benjamin; Stevenson, Christian; Felling, David

    2012-12-11

    The present application provides a premixer for a combustor. The premixer may include a fuel plenum with a number of fuel tubes and a burner tube with a number of air tubes. The fuel tubes extend about the air tubes.

  18. Studies in premixed combustion

    SciTech Connect

    Sivashinsky, G.I.

    1992-01-01

    This report discusses the following topics on premixed combustion: theory of turbulent flame propagation; pattern formation in premixed flames and related problems; and pattern formation in extended systems. (LSP)

  19. Human insulin versus porcine insulin in rhesus monkeys with diabetes mellitus.

    PubMed

    Jin, Xi; Zeng, Li; Zhang, Shuang; He, Sirong; Ren, Yan; Chen, Younan; Wei, Lingling; Wang, Li; Li, Hongxia; Cheng, Jingqiu; Lu, Yanrong

    2013-02-01

    Monkeys with insulin-dependent diabetes are important preclinical animal models for islet transplantation. Exogenous insulin should be administered to achieve good glycemic control and minimize the long-term vascular complications associated with diabetes until the graft function recovered completely. However, the effect of multiple daily injections of porcine or human insulin and the long-term effects of porcine insulin have not been studied in diabetic rhesus monkeys. Diabetic rhesus monkeys, using a 6-month self-control insulin comparison experiment, were used to detect the incidence of adverse events and long-term diabetes complication events after long-term administration of porcine insulin. In this study, we found that a 20% higher dose of porcine insulin results in similar glycemic control as the human insulin regimen, and adverse events were seldom reported when porcine insulin was administered. Moreover, long-term injection with porcine insulin could delay the rate and severity of diabetes-related complications. Porcine insulin as a competent candidate for regular insulin therapy to maintain blood glucose levels in insulin-dependent diabetic monkeys during preclinical studies of islet transplantation. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  20. Transgenic silkworms expressing human insulin receptors for evaluation of therapeutically active insulin receptor agonists.

    PubMed

    Matsumoto, Yasuhiko; Ishii, Masaki; Ishii, Kenichi; Miyaguchi, Wataru; Horie, Ryo; Inagaki, Yoshinori; Hamamoto, Hiroshi; Tatematsu, Ken-ichiro; Uchino, Keiro; Tamura, Toshiki; Sezutsu, Hideki; Sekimizu, Kazuhisa

    2014-12-12

    We established a transgenic silkworm strain expressing the human insulin receptor (hIR) using the GAL4/UAS system. Administration of human insulin to transgenic silkworms expressing hIR decreased hemolymph sugar levels and facilitated Akt phosphorylation in the fat body. The decrease in hemolymph sugar levels induced by injection of human insulin in the transgenic silkworms expressing hIR was blocked by co-injection of wortmannin, a phosphoinositide 3-kinase inhibitor. Administration of bovine insulin, an hIR ligand, also effectively decreased sugar levels in the transgenic silkworms. These findings indicate that functional hIRs that respond to human insulin were successfully induced in the transgenic silkworms. We propose that the humanized silkworm expressing hIR is useful for in vivo evaluation of the therapeutic activities of insulin receptor agonists.

  1. Metabolism of human insulin after subcutaneous administration: A possible means to uncover insulin misuse.

    PubMed

    Thomas, Andreas; Brinkkötter, Paul; Schänzer, Wilhelm; Thevis, Mario

    2015-10-15

    The misuse of insulin for performance enhancement in sport or as toxic agent has frequently been reported in the past. In contrast to synthetic insulin analogues, the administration of recombinant human insulin is hardly recognized by mass spectrometry. The present study was designed to uncover the misuse of recombinant human insulin for doping control purposes as well as for forensic applications. It is hypothesized that an altered metabolite profile of circulating insulin prevails after subcutaneous administration due to exposure of insulin to epidermal proteases. In vitro experiments with skin tissue lysates (S9 fraction and microsomes), different biological fluids (urine, serum, plasma) and recombinant human insulin were performed and the deriving metabolites were characterized by liquid chromatography coupled to high resolution mass spectrometry (HRMS). Afterwards, authentic blood samples of patients suffering from diabetes mellitus and a control group of healthy humans were analysed. Therefore, a method using protein precipitation, ultrafiltration and antibody-coated magnetic beads for purification with subsequent separation by nano-scale liquid chromatography coupled a Q Exactive mass spectrometer was applied. Several metabolites of insulin with C-terminally truncated sequences of the B-chain (and A-chain in minor extent) were identified within this study. Here, the DesB30 human insulin represents the major metabolite in all experiments. This metabolite is frequently found in urine samples due to degradation processes and, thus, disqualifies this matrix for the intended purposes. In contrast, blood samples do commonly not contain DesB30 insulin, which was corroborated by data obtained from the control group. In post-administration blood samples, minute but distinct amounts (approx. 50 pg mL(-1)) of DesB30 insulin were found and suggest the use of this analyte as potential marker for subcutaneous human insulin administration, supporting the attempts to

  2. A minimized human insulin-receptor-binding motif revealed in a Conus geographus venom insulin.

    PubMed

    Menting, John G; Gajewiak, Joanna; MacRaild, Christopher A; Chou, Danny Hung-Chieh; Disotuar, Maria M; Smith, Nicholas A; Miller, Charleen; Erchegyi, Judit; Rivier, Jean E; Olivera, Baldomero M; Forbes, Briony E; Smith, Brian J; Norton, Raymond S; Safavi-Hemami, Helena; Lawrence, Michael C

    2016-10-01

    Insulins in the venom of certain fish-hunting cone snails facilitate prey capture by rapidly inducing hypoglycemic shock. One such insulin, Conus geographus G1 (Con-Ins G1), is the smallest known insulin found in nature and lacks the C-terminal segment of the B chain that, in human insulin, mediates engagement of the insulin receptor and assembly of the hormone's hexameric storage form. Removal of this segment (residues B23-B30) in human insulin results in substantial loss of receptor affinity. Here, we found that Con-Ins G1 is monomeric, strongly binds the human insulin receptor and activates receptor signaling. Con-Ins G1 thus is a naturally occurring B-chain-minimized mimetic of human insulin. Our crystal structure of Con-Ins G1 reveals a tertiary structure highly similar to that of human insulin and indicates how Con-Ins G1's lack of an equivalent to the key receptor-engaging residue Phe(B24) is mitigated. These findings may facilitate efforts to design ultrarapid-acting therapeutic insulins.

  3. [Preparation of recombinant human insulin--study of downstream process].

    PubMed

    Yu, Rong; Li, Xiaohong; Yang, Jiyu; Wu, Wutong

    2004-10-01

    This study was intended to establish a method of preparation of recombinant human insulin, with (His)6-Arg-Arg-human proinsulin (RRhPI) expressed by Escherichia coli. After DEAE-Sepharose Fast Flow ion-exchange chromatography, Sephadex G-25 chromatography and refolding, enzyme cleavage and Superdex 75 size exclusion chromatography,the RRhPI expressed by Escherichia coli in inclusion body form was converted to human insulin. The obtained recombinant human insulin was analyzed by SDS-PAGE, HPLC, amino acid composition analysis and bioidentity test (mouse convulsion test). The results indicate that our obtained preparation is highly purified, active recombinant human insulin.

  4. [Intensive insulin therapy in type 2 diabetes mellitus].

    PubMed

    Jermendy, György

    2012-09-23

    In the last couple of years, the intensive conservative insulin treatment (basal-bolus regime) became more and more popular even in patients with type 2 diabetes. Using this insulin treatment, continuous patient education, co-operation between the medical team (diabetologist, dietician and diabetes-nurses) and the patient as well as the availability of modern insulins, pens and glucometers are of great importance. Clearly, the basal-bolus treatment with human insulin has advantages over the conservative (conventional) treatment with twice daily premix insulins. Moreover, the basal-bolus treatment with insulin-analogues proved to be superior in some aspects as compared to human insulins. The intensive insulin treatment (basal-bolus regime with insulin-analogues) approaches the optimal insulin substitution and, with its use the adequate correction of each element of the glucose triad (fasting blood glucose, postprandial blood glucose, HbA1c) should be considered feasible even in patients with type 2 diabetes.

  5. Human Insulin from Recombinant DNA Technology

    NASA Astrophysics Data System (ADS)

    Johnson, Irving S.

    1983-02-01

    Human insulin produced by recombinant DNA technology is the first commercial health care product derived from this technology. Work on this product was initiated before there were federal guidelines for large-scale recombinant DNA work or commercial development of recombinant DNA products. The steps taken to facilitate acceptance of large-scale work and proof of the identity and safety of such a product are described. While basic studies in recombinant DNA technology will continue to have a profound impact on research in the life sciences, commercial applications may well be controlled by economic conditions and the availability of investment capital.

  6. Recombinant DNA derived monomeric insulin analogue: comparison with soluble human insulin in normal subjects.

    PubMed Central

    Vora, J. P.; Owens, D. R.; Dolben, J.; Atiea, J. A.; Dean, J. D.; Kang, S.; Burch, A.; Brange, J.

    1988-01-01

    OBJECTIVE--To compare the rate of absorption from subcutaneous tissue and the resulting hypoglycaemic effect of iodine-125 labelled soluble human insulin and a monomeric insulin analogue derived by recombinant DNA technology. DESIGN--Single blind randomised comparison of equimolar doses of 125I labelled soluble human insulin and insulin analogue. SETTING--Study in normal people at a diabetes research unit and a university department of medical physics. SUBJECTS--Seven healthy male volunteers aged 20-39 not receiving any other drugs. INTERVENTIONS--After an overnight fast and a basal period of one hour two doses (0.05 and 0.1 U/kg) of 125I labelled soluble human insulin and insulin analogue were injected subcutaneously into the anterior abdominal wall on four separate days. END POINT--To find a fast acting insulin for meal related requirements in insulin dependent diabetics. MEASUREMENTS and main results--Residual radioactivity at the injection site was measured continuously for the first two hours after injection of the 125I labelled preparations and thereafter for five minutes simultaneously with blood sampling. Frequent venous blood samples were obtained over six hours for determination of plasma immunoreactive insulin, insulin analogue, glucose, and glucagon values. Time to 50% of initial radioactivity at the injection site for the insulin analogue compared with soluble insulin was 61 v 135 minutes (p less than 0.05) with 0.05 U/kg and 67 v 145 minutes (p less than 0.001) with 0.1 U/kg. Concentrations in plasma increased faster after the insulin analogue compared with soluble insulin, resulting in higher plasma concentrations between 10 and 150 minutes (0.001 less than p less than 0.05) after 0.05 U/kg and between 40 and 360 minutes (0.001 less than p less than 0.05) after 0.1 U/kg. The hypoglycaemic response to insulin analogue was a plasma glucose nadir at 60 minutes with both doses compared with 90 and 120 minutes with soluble insulin at 0.5 and 0.1 U

  7. Improvement in morning hyperglycaemia with basal human ultratard and prandial human actrapid insulin--a comparison of multiple injection regimens.

    PubMed

    Davies, R R; McEwen, J; Moreland, T A; Durnin, C; Newton, R W

    1988-10-01

    Three 'pen'-administered multiple injection regimens have been compared with twice daily insulin injection regimens by means of 24-h profiles of plasma glucose and free insulin concentrations. Ten Type 1 diabetic patients received their usual twice daily insulin regimen and were then randomized to receive the same total daily insulin dose in four divided doses using (1) 50:50 premixed soluble and isophane, (2) 30:70 premixed soluble and isophane, and (3) preprandial soluble and evening crystalline-zinc insulins. Profiles were performed after 1 week on each regimen. Plasma glucose concentrations were similar during the twice daily regimen and the two premixed regimens, rising during the early hours of the morning to a peak between 0900 and 0930 h of 13.8 +/- 2.8 (+/- SD) mmol l-1 on the twice daily regimen, 13.6 +/- 5.3 mmol l-1 on the premixed 50:50 regimen, and 13.5 +/- 4.2 mmol-1 on the premixed 30:70 regimen. With the basal and prandial regimen, overnight plasma glucose concentrations were higher than with the other regimens between 2400 and 0300 h (p less than 0.05). Concentrations then fell until breakfast, and rose after this meal to a peak of 9.5 +/- 4.3 mmol l-1 (p less than 0.01). Mean plasma glucose concentrations were significantly lower than on the other three regimens between 0830 and 1100 h (p less than 0.05). Less variability was observed in 24-h mean plasma glucose concentrations during the basal and prandial regimen than during the other three regimens.

  8. Monoclonal Antibodies to the Human Insulin Receptor that Activate Glucose Transport but not Insulin Receptor Kinase Activity

    NASA Astrophysics Data System (ADS)

    Forsayeth, John R.; Caro, Jose F.; Sinha, Madhur K.; Maddux, Betty A.; Goldfine, Ira D.

    1987-05-01

    Three mouse monoclonal antibodies were produced that reacted with the α subunit of the human insulin receptor. All three both immunoprecipitated 125I-labeled insulin receptors from IM-9 lymphocytes and competitively inhibited 125I-labeled insulin binding to its receptor. Unlike insulin, the antibodies failed to stimulate receptor autophosphorylation in both intact IM-9 lymphocytes and purified human placental insulin receptors. Moreover, unlike insulin, the antibodies failed to stimulate receptor-mediated phosphorylation of exogenous substrates. However, like insulin, two of the three antibodies stimulated glucose transport in isolated human adipocytes. One antibody, on a molar basis, was as potent as insulin. These studies indicate, therefore, that monoclonal antibodies to the insulin receptor can mimic a major function of insulin without activating receptor kinase activity. They also raise the possibility that certain actions of insulin such as stimulation of glucose transport may not require the activation of receptor kinase activity.

  9. Interacting Effects of TSH and Insulin on Human Differentiated Adipocytes.

    PubMed

    Felske, D; Gagnon, A; Sorisky, A

    2015-08-01

    Subclinical hypothyroidism, characterized by an isolated rise in TSH serum levels with normal thyroid function, is a pro-inflammatory state associated with insulin resistance. Adipocytes express TSH receptors, but it is not known if TSH can directly inhibit insulin signaling. Using primary human differentiated adipocytes, we examined the effects of TSH on insulin-stimulated Akt phosphorylation, and whether conventional PKC (cPKC) were involved. The effect of insulin on TSH-stimulated lipolysis was also investigated. TSH inhibited insulin-stimulated Akt phosphorylation in adipocytes by 54%. TSH activated cPKC, and Gö6976, a PKCα and -β1 inhibitor, prevented the inhibitory effect of TSH on the insulin response. Insulin reduced the ability of TSH to activate cPKC and to stimulate lipolysis.Our data reveal novel interactions between TSH and insulin. TSH inhibits insulin-stimulated Akt signaling in a cPKC-dependent fashion, whereas insulin blocks TSH-stimulated cPKC activity and lipolysis. TSH and insulin act on differentiated human adipocytes to modulate their respective intracellular signals. © Georg Thieme Verlag KG Stuttgart · New York.

  10. Intracellular insulin-receptor dissociation and segregation in a rat fibroblast cell line transfected with a human insulin receptor gene

    SciTech Connect

    Levy, J.R.; Olefsky, J.M.

    1988-05-05

    The cellular processing of insulin and insulin receptors was studied using a rat fibroblast cell line that had been transfected with a normal human insulin receptor gene, expressing approximately 500 times the normal number of native fibroblasts insulin receptors. These cells bind and internalize insulin normally. Biochemically assays based on the selective precipitation by polyethylene glycol of intact insulin-receptor complexes but not of free intracellular insulin were developed to study the time course of intracellular insulin-receptor dissociation. Fibroblasts were incubated with radiolabeled insulin at 4/sup 0/C, and internalization of insulin-receptor complexes was initiated by warming the cells to 37/sup 0/C. Within 2 min, 90% of the internalized radioactivity was composed of intact insulin-receptor complexes. The dissociation of insulin from internalized insulin-receptor complexes was markedly inhibited by monensin and chloroquine. Furthermore, chloroquine markedly increased the number of cross-linkable intracellular insulin-receptor complexes, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis autoradiography. These findings suggest that acidification of intracellular vesicles is responsible for insulin-receptor dissociation. Physical segregation of dissociated intracellular insulin from its receptor was monitored. The results are consistent with the view that segregation of insulin and receptor occurs 5-10 min after initiation of dissociation. These studies demonstrate the intracellular itinerary of insulin-receptor complexes, including internalization, dissociation of insulin from the internalized receptor within an acidified compartment, segregation of insulin from the receptor, and subsequent ligand degradation.

  11. Insulin antibodies in patients with type 2 diabetic receiving recombinant human insulin injection: A report of 12 cases.

    PubMed

    Hu, Xiaolei; Ma, Xiaowen; Wang, Xin; Zhao, Xiuli; Xu, Xuling; Gong, Hui; Chen, Fengling; Sun, Junjie

    2015-12-01

    We report 12 cases of patients with type 2 diabetic receiving recombinant human insulin injection, who had uncontrolled hyperglycemia or frequent episodes of hypoglycemia, high levels of serum insulin and positive insulin antibodies. The clinical characteristics and insulin antibodies pharmacokinetics parameters were analyzed. After administration of glucocorticoids, changing insulin formulations or discontinuing the insulin and switching to oral antidiabetic agents, the level of insulin antibodies decreased and the plasma glucose restored. Thus, we recommend to identify the presence of high insulin antibodies in patients with type 2 diabetes who experience unexplained high plasma glucose or frequent reoccurrence of hypoglycemia.

  12. Bioavailability of insulin detemir and human insulin at the level of peripheral interstitial fluid in humans, assessed by open-flow microperfusion.

    PubMed

    Bodenlenz, M; Ellmerer, M; Schaupp, L; Jacobsen, L V; Plank, J; Brunner, G A; Wutte, A; Aigner, B; Mautner, S I; Pieber, T R

    2015-12-01

    To find an explanation for the lower potency of insulin detemir observed in humans compared with unmodified human insulin by investigating insulin detemir and human insulin concentrations directly at the level of peripheral insulin-sensitive tissues in humans in vivo. Euglycaemic-hyperinsulinaemic clamp experiments were performed in healthy volunteers. Human insulin was administered i.v. at 6 pmol/kg/min and insulin detemir at 60 pmol/kg/min, achieving a comparable steady-state pharmacodynamic action. In addition, insulin detemir was doubled to 120 pmol/kg/min. Minimally invasive open-flow microperfusion (OFM) sampling methodology was combined with inulin calibration to quantify human insulin and insulin detemir in the interstitial fluid (ISF) of subcutaneous adipose and skeletal muscle tissue. The human insulin concentration in the ISF was ∼115 pmol/l or ∼30% of the serum concentration, whereas the insulin detemir concentration in the ISF was ∼680 pmol/l or ∼2% of the serum concentration. The molar insulin detemir interstitial concentration was five to six times higher than the human insulin interstitial concentration and metabolic clearance of insulin detemir from serum was substantially reduced compared with human insulin. OFM proved useful for target tissue measurements of human insulin and the analogue insulin detemir. Our tissue data confirm a highly effective retention of insulin detemir in the vascular compartment. The higher insulin detemir relative to human insulin tissue concentrations at comparable pharmacodynamics, however, indicate that the lower potency of insulin detemir in humans is attributable to a reduced effect in peripheral insulin-sensitive tissues and is consistent with the reduced in vitro receptor affinity. © 2015 John Wiley & Sons Ltd.

  13. Insulin stimulation of glycogen synthase in cultured human diploid fibroblasts.

    PubMed

    Hidaka, H; Howard, B V; Kosmakos, F C; Fields, R M; Craig, J W; Bennett, P H; Larner, J

    1980-10-01

    The effect of insulin on glycogen synthase activity in human diploid fibroblasts has been studied. As little as 2 X 10(-10) M insulin increased the glycogen synthase / activity without changing the total activity. Stimulation occurred within 5 min and became maximal in 30 min. A half-maximal increase of / activity was achieved at 3 X 10(-9) M insulin. Glucose starvation increased the magnitude of response of glycogen synthase to insulin but did not change the insulin concentration necessary to give a half-maximal stimulation. Glucose increased the basal level of / activity in human diploid fibroblasts; the effect of insulin was additive. During in vitro senescence the total glycogen synthase activity declined, but the concentration of insulin that produced a half-maximal stimulation remained unchanged. These data indicate that regulation of glycogen synthase activity in human diploid fibroblasts is responsive to physiologic insulin levels and that the system provides a useful model for the in vitro study of insulin sensitivity.

  14. Postreceptor insulin resistance contributes to human dyslipidemia and hepatic steatosis

    PubMed Central

    Semple, Robert K.; Sleigh, Alison; Murgatroyd, Peter R.; Adams, Claire A.; Bluck, Les; Jackson, Sarah; Vottero, Alessandra; Kanabar, Dipak; Charlton-Menys, Valentine; Durrington, Paul; Soos, Maria A.; Carpenter, T. Adrian; Lomas, David J.; Cochran, Elaine K.; Gorden, Phillip; O’Rahilly, Stephen; Savage, David B.

    2009-01-01

    Metabolic dyslipidemia is characterized by high circulating triglyceride (TG) and low HDL cholesterol levels and is frequently accompanied by hepatic steatosis. Increased hepatic lipogenesis contributes to both of these problems. Because insulin fails to suppress gluconeogenesis but continues to stimulate lipogenesis in both obese and lipodystrophic insulin-resistant mice, it has been proposed that a selective postreceptor defect in hepatic insulin action is central to the pathogenesis of fatty liver and hypertriglyceridemia in these mice. Here we show that humans with generalized insulin resistance caused by either mutations in the insulin receptor gene or inhibitory antibodies specific for the insulin receptor uniformly exhibited low serum TG and normal HDL cholesterol levels. This was due at least in part to surprisingly low rates of de novo lipogenesis and was associated with low liver fat content and the production of TG-depleted VLDL cholesterol particles. In contrast, humans with a selective postreceptor defect in AKT2 manifest increased lipogenesis, elevated liver fat content, TG-enriched VLDL, hypertriglyceridemia, and low HDL cholesterol levels. People with lipodystrophy, a disorder characterized by particularly severe insulin resistance and dyslipidemia, demonstrated similar abnormalities. Collectively these data from humans with molecularly characterized forms of insulin resistance suggest that partial postreceptor hepatic insulin resistance is a key element in the development of metabolic dyslipidemia and hepatic steatosis. PMID:19164855

  15. Human gut microbes impact host serum metabolome and insulin sensitivity.

    PubMed

    Pedersen, Helle Krogh; Gudmundsdottir, Valborg; Nielsen, Henrik Bjørn; Hyotylainen, Tuulia; Nielsen, Trine; Jensen, Benjamin A H; Forslund, Kristoffer; Hildebrand, Falk; Prifti, Edi; Falony, Gwen; Le Chatelier, Emmanuelle; Levenez, Florence; Doré, Joel; Mattila, Ismo; Plichta, Damian R; Pöhö, Päivi; Hellgren, Lars I; Arumugam, Manimozhiyan; Sunagawa, Shinichi; Vieira-Silva, Sara; Jørgensen, Torben; Holm, Jacob Bak; Trošt, Kajetan; Kristiansen, Karsten; Brix, Susanne; Raes, Jeroen; Wang, Jun; Hansen, Torben; Bork, Peer; Brunak, Søren; Oresic, Matej; Ehrlich, S Dusko; Pedersen, Oluf

    2016-07-21

    Insulin resistance is a forerunner state of ischaemic cardiovascular disease and type 2 diabetes. Here we show how the human gut microbiome impacts the serum metabolome and associates with insulin resistance in 277 non-diabetic Danish individuals. The serum metabolome of insulin-resistant individuals is characterized by increased levels of branched-chain amino acids (BCAAs), which correlate with a gut microbiome that has an enriched biosynthetic potential for BCAAs and is deprived of genes encoding bacterial inward transporters for these amino acids. Prevotella copri and Bacteroides vulgatus are identified as the main species driving the association between biosynthesis of BCAAs and insulin resistance, and in mice we demonstrate that P. copri can induce insulin resistance, aggravate glucose intolerance and augment circulating levels of BCAAs. Our findings suggest that microbial targets may have the potential to diminish insulin resistance and reduce the incidence of common metabolic and cardiovascular disorders.

  16. Human insulin microcrystals with lactose carriers for pulmonary delivery.

    PubMed

    Lim, Se-Hwan; Park, Hye Won; Shin, Chang-Hoon; Kwon, Jai-Hyun; Kim, Chan-Wha

    2009-12-01

    Dry powder formulations for pulmonary delivery are attractive because many issues of solubility and stability can be minimized. Human insulin microcrystals with lactose carriers were produced for pulmonary delivery. The average particle diameter was 2.3 microm, with a narrow, monodispersed size distribution. The percentages of high molecular weight proteins (%HMWPs), other insulin-related compounds (%OIRCs), and A-21 desamido insulin (%D(es)) were very low throughout the microcrystal preparation process. Administration of the microcrystal powder by intratracheal insufflation significantly reduced the blood glucose levels of Sprague-Dawley rats. The percent minimum reductions of the blood glucose concentration (%MRBG) produced by the insulin microcrystal powder and by an insulin solution reached 40.4% and 33.4% of the initial glucose levels respectively, and their bioavailability relative to subcutaneous injection (F) was 15% and 10% respectively. These results confirm that the insulin microcrystal powder prepared is suitable for pulmonary delivery in an effective dosage form.

  17. Premixed conical flame stabilization

    NASA Astrophysics Data System (ADS)

    Krikunova, A. I.; Son, E. E.; Saveliev, A. S.

    2016-11-01

    In the current work, stabilization of premixed laminar and lean turbulent flames for wide range of flow rates and equivalence ratios was performed. Methane-air mixture was ignited after passing through premixed chamber with beads and grids, and conical nozzle (Bunsen-type burner). On the edge of the nozzle a stabilized body-ring was mounted. Ring geometry was varied to get the widest stable flame parameters. This work was performed as part of the project on experimental investigation of premixed flames under microgravity conditions.

  18. [Efficacy and safety of insulin aspart versus regular human insulin for women with gestational diabetes mellitus].

    PubMed

    Zhou, Li; Fan, Ling

    2012-05-22

    To explore the efficacy and safety of human aspart versus regular human insulin in women with gestational diabetes mellitus (GDM). A total of 80 women with GDM during pregnancy delivered at our hospital divided into 2 groups: Group 1 with human aspart and regular human insulin N while Group 2 with regular human insulin R and N. The levels of glucose were compared before and after 2 h at breakfast, lunch and supper at Day 1, 3 and 5. And the outcomes of women and their babies were evaluated. No significant difference in general characteristics existed between two groups. Except for breakfast of Day 3, no significant difference was found in terms of the amount of insulin, the time of satisfactory glucose level and delivery time point, etc. There was no significant inter-group difference in the outcomes of pregnant women and their babies. The efficacy and safety of human aspart or regular human insulin are comparable for the women with gestational diabetes mellitus.

  19. Human adipose tissue expresses intrinsic circadian rhythm in insulin sensitivity.

    PubMed

    Carrasco-Benso, Maria P; Rivero-Gutierrez, Belen; Lopez-Minguez, Jesus; Anzola, Andrea; Diez-Noguera, Antoni; Madrid, Juan A; Lujan, Juan A; Martínez-Augustin, Olga; Scheer, Frank A J L; Garaulet, Marta

    2016-09-01

    In humans, insulin sensitivity varies according to time of day, with decreased values in the evening and at night. Mechanisms responsible for the diurnal variation in insulin sensitivity are unclear. We investigated whether human adipose tissue (AT) expresses intrinsic circadian rhythms in insulin sensitivity that could contribute to this phenomenon. Subcutaneous and visceral AT biopsies were obtained from extremely obese participants (body mass index, 41.8 ± 6.3 kg/m(2); 46 ± 11 y) during gastric-bypass surgery. To assess the rhythm in insulin signaling, AKT phosphorylation was determined every 4 h over 24 h in vitro in response to different insulin concentrations (0, 1, 10, and 100 nM). Data revealed that subcutaneous AT exhibited robust circadian rhythms in insulin signaling (P < 0.00001). Insulin sensitivity reached its maximum (acrophase) around noon, being 54% higher than during midnight (P = 0.009). The amplitude of the rhythm was positively correlated with in vivo sleep duration (r = 0.53; P = 0.023) and negatively correlated with in vivo bedtime (r = -0.54; P = 0.020). No circadian rhythms were detected in visceral AT (P = 0.643). Here, we demonstrate the relevance of the time of the day for how sensitive AT is to the effects of insulin. Subcutaneous AT shows an endogenous circadian rhythm in insulin sensitivity that could provide an underlying mechanism for the daily rhythm in systemic insulin sensitivity.-Carrasco-Benso, M. P., Rivero-Gutierrez, B., Lopez-Minguez, J., Anzola, A., Diez-Noguera, A., Madrid, J. A., Lujan, J. A., Martínez-Augustin, O., Scheer, F. A. J. L., Garaulet, M. Human adipose tissue expresses intrinsic circadian rhythm in insulin sensitivity.

  20. Human Recombinant Insulin 1g - ug

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Proteins are the building blocks of our bodies and the living world around us. Within our bodies proteins make it possible for red blood cells to carry oxygen throughout the body. Others help transmit nerve impulses so we can hear, smell and feel the world around us. While others play a crucial role in preventing or causing disease. If the structure of a protein is known, then companies can develop new or improved drugs to fight the disease of which the protein is a part. To determine protein structure, researchers must grow near-perfect crystals of the protein. On Earth convection currents, sedimentation and other gravity-induced phenomena hamper crystal growth efforts. In microgravity researchers can grow near-perfect crystals in an environment free of these effects. Because of the enormous potential for new pharmaceutical products the Center for Macromolecular Crystallography--the NASA Commercial Space Center responsible for commercial protein crystal growth efforts has more than fifty major industry and academic partners. Research on crystals of human insulin could lead to improved treatments for diabetes.

  1. Human Recombinant Insulin 1g - ug

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Proteins are the building blocks of our bodies and the living world around us. Within our bodies proteins make it possible for red blood cells to carry oxygen throughout the body. Others help transmit nerve impulses so we can hear, smell and feel the world around us. While others play a crucial role in preventing or causing disease. If the structure of a protein is known, then companies can develop new or improved drugs to fight the disease of which the protein is a part. To determine protein structure, researchers must grow near-perfect crystals of the protein. On Earth convection currents, sedimentation and other gravity-induced phenomena hamper crystal growth efforts. In microgravity researchers can grow near-perfect crystals in an environment free of these effects. Because of the enormous potential for new pharmaceutical products the Center for Macromolecular Crystallography--the NASA Commercial Space Center responsible for commercial protein crystal growth efforts has more than fifty major industry and academic partners. Research on crystals of human insulin could lead to improved treatments for diabetes.

  2. Gas turbine premixing systems

    SciTech Connect

    Kraemer, Gilbert Otto; Varatharajan, Balachandar; Evulet, Andrei Tristan; Yilmaz, Ertan; Lacy, Benjamin Paul

    2013-12-31

    Methods and systems are provided for premixing combustion fuel and air within gas turbines. In one embodiment, a combustor includes an upstream mixing panel configured to direct compressed air and combustion fuel through premixing zone to form a fuel-air mixture. The combustor includes a downstream mixing panel configured to mix additional combustion fuel with the fule-air mixture to form a combustion mixture.

  3. Effects of glucosamine infusion on insulin secretion and insulin action in humans.

    PubMed

    Monauni, T; Zenti, M G; Cretti, A; Daniels, M C; Targher, G; Caruso, B; Caputo, M; McClain, D; Del Prato, S; Giaccari, A; Muggeo, M; Bonora, E; Bonadonna, R C

    2000-06-01

    Glucose toxicity (i.e., glucose-induced reduction in insulin secretion and action) may be mediated by an increased flux through the hexosamine-phosphate pathway. Glucosamine (GlcN) is widely used to accelerate the hexosamine pathway flux, independently of glucose. We tested the hypothesis that GlcN can affect insulin secretion and/or action in humans. In 10 healthy subjects, we sequentially performed an intravenous glucose (plus [2-3H]glucose) tolerance test (IVGTT) and a euglycemic insulin clamp during either a saline infusion or a low (1.6 micromol x min(-1) x kg(-1)) or high (5 micromol x min(-1) x kg(-1) [n = 5]) GlcN infusion. Beta-cell secretion, insulin (SI*-IVGTT), and glucose (SG*) action on glucose utilization during the IVGTT were measured according to minimal models of insulin secretion and action. Infusion of GlcN did not affect readily releasable insulin levels, glucose-stimulated insulin secretion (GSIS), or the time constant of secretion, but it increased both the glucose threshold of GSIS (delta approximately 0.5-0.8 mmol/l, P < 0.03-0.01) and plasma fasting glucose levels (delta approximately 0.3-0.5 mmol/l, P < 0.05-0.02). GlcN did not change glucose utilization or intracellular metabolism (glucose oxidation and glucose storage were measured by indirect calorimetry) during the clamp. However, high levels of GlcN caused a decrease in SI*-IVGTT (delta approximately 30%, P < 0.02) and in SG* (delta approximately 40%, P < 0.05). Thus, in humans, acute GlcN infusion recapitulates some metabolic features of human diabetes. It remains to be determined whether acceleration of the hexosamine pathway can cause insulin resistance at euglycemia in humans.

  4. Circulating Palmitoleate Strongly and Independently Predicts Insulin Sensitivity in Humans

    PubMed Central

    Stefan, Norbert; Kantartzis, Konstantinos; Celebi, Nora; Staiger, Harald; Machann, Jürgen; Schick, Fritz; Cegan, Alexander; Elcnerova, Michaela; Schleicher, Erwin; Fritsche, Andreas; Häring, Hans-Ulrich

    2010-01-01

    OBJECTIVE We investigated whether palmitoleate, which prevents insulin resistance in mice, predicts insulin sensitivity in humans. RESEARCH DESIGN AND METHODS The fasting fatty acid pattern in the plasma free fatty acid (FFA) fraction was determined in 100 subjects at increased risk for type 2 diabetes. Insulin sensitivity was estimated during an oral glucose tolerance test (OGTT) at baseline and after 9 months of lifestyle intervention and measured during the euglycemic-hyperinsulinemic clamp (n = 79). RESULTS Circulating palmitoleate (OGTT:F ratio = 8.2, P = 0.005; clamp:F ratio = 7.8, P = 0.007) but not total FFAs (OGTT:F ratio = 0.6, P = 0.42; clamp:F ratio = 0.7, P = 0.40) correlated positively with insulin sensitivity, independently of age, sex, and adiposity. High baseline palmitoleate predicted a larger increase in insulin sensitivity. For 1-SD increase in palmitoleate, the odds ratio for being in the highest versus the lowest tertile of adjusted change in insulin sensitivity was 2.35 (95% CI 1.16–5.35). CONCLUSIONS Circulating palmitoleate strongly and independently predicts insulin sensitivity, suggesting that it plays an important role in the pathophysiology of insulin resistance in humans. PMID:19889804

  5. Continuous subcutaneous insulin infusion with short-acting insulin analogues or human regular insulin: efficacy, safety, quality of life, and cost-effectiveness.

    PubMed

    Radermecker, Régis Pierre; Scheen, André Jacques

    2004-01-01

    Portable insulin infusion devices are effective and safe insulin delivery systems for managing diabetes mellitus, especially type 1 diabetes. Rapidly absorbed insulin analogues, such as insulin lispro or insulin aspart, may offer an advantage over regular human insulin for insulin pumps. Several open-label randomised crossover trials demonstrated that continuous subcutaneous insulin infusion (CSII) with insulin lispro provided a better control of postprandial hyperglycaemia and a slightly but significantly lower glycated haemoglobin level, with lower daily insulin requirement and similar or even less hypoglycaemic episodes. A CSII study comparing insulin lispro and insulin aspart demonstrated similar results with the two analogues, and better results than those with regular insulin. Because these analogues have a quicker onset and a shorter duration of action than regular insulin, one might expect an earlier and greater metabolic deterioration in case of CSII interruption, but a more rapid correction of metabolic abnormalities after insulin boluses when reactivating the pump. These expectations were confirmed in randomised protocols comparing the metabolic changes occurring during and after CSII interruption of various durations when the pump infused either insulin lispro or regular insulin. The extra cost resulting from the use of CSII and insulin analogues in diabetes management should be compensated for by better metabolic control and quality of life. In conclusion, CSII delivering fast-acting insulin analogues may be considered as one of the best methods to replace insulin in a physiological manner by mimicking meal and basal insulin requirements, without higher risk of hypoglycaemia or ketoacidosis in well-educated diabetic patients.

  6. Demonstrating strategies for initiation of insulin therapy: matching the right insulin to the right patient.

    PubMed

    Meneghini, L

    2008-08-01

    To increase awareness regarding the different types of insulin available and provide discussion regarding how each type of insulin can address the needs of diverse patients in terms of their unique requirements, preferences, medical history and lifestyle concerns. New classes of antidiabetes medications, the development of insulin analogues and novel insulin delivery systems, provide more options for the management of type 2 diabetes. Given the inevitable progression of beta-cell dysfunction, along with the relatively limited glucose-lowering capacity of other agents, many patients will eventually require insulin for optimal glycaemic management. However, patients and physicians often fail to initiate insulin early enough during the progression of disease to maintain the recommended levels of glycaemic control. The inherent properties of the new insulin analogues, more physiological and user-friendly time-action profiles compared with older human insulin formulations, may partly address the barriers to insulin use. Insulin analogues include rapid acting (for prandial glycaemic control), long acting (for basal insulin coverage) and premixed insulin analogues, which combine both a rapid acting and an extended duration component in a single insulin formulation. Various case-based scenarios on initiating and intensifying therapy with insulin analogues will be presented. Development of an individualised treatment plan for initiation of insulin is a critical step in achieving target glycaemic levels in patients with type 2 diabetes.

  7. Effects of exercise on insulin binding to human muscle

    SciTech Connect

    Bonen, A.; Tan, M.H.; Clune, P.; Kirby, R.L.

    1985-04-01

    A procedure was developed to measure insulin binding to human skeletal muscle obtained via the percutaneous muscle biopsy technique. With this method the effects of exercise on insulin binding were investigated. Subjects (n = 9) exercised for 60 min on a bicycle ergometer at intensities ranging from 20-86% maximum O/sub 2/ consumption (VO/sub 2/max). Blood samples were obtained before, during, and after exercise and analyzed for glucose and insulin. Muscle samples (250 mg) for the vastus lateralis were obtained 30 min before exercise, at the end of exercise, and 60 min after exercise. Two subjects rested during the experimental period. There was no linear relationship between exercise intensities and the changes in insulin binding to human muscle. At rest (n = 2) and at exercise intensities below 60% VO/sub 2/max (n = 5) no change in insulin binding occurred (P greater than 0.05). However, when exercise occurred at greater than or equal to 69% VO/sub 2/max (n = 4), a pronounced decrement in insulin binding (30-50%) was observed (P less than 0.05). This persisted for 60 min after exercise. These results indicate that insulin binding in human muscle is not altered by 60 min of exercise at less than or equal to 60% VO/sub 2/max but that a marked decrement occurs when exercise is greater than or equal to 69% VO/sub 2/max.

  8. Dietary Sodium Restriction Decreases Insulin Secretion Without Affecting Insulin Sensitivity in Humans

    PubMed Central

    Byrne, Loretta M.; Yu, Chang; Wang, Thomas J.; Brown, Nancy J.

    2014-01-01

    Context: Interruption of the renin-angiotensin-aldosterone system prevents incident diabetes in high-risk individuals, although the mechanism remains unclear. Objective: To test the hypothesis that activation of the endogenous renin-angiotensin-aldosterone system or exogenous aldosterone impairs insulin secretion in humans. Design: We conducted a randomized, blinded crossover study of aldosterone vs vehicle and compared the effects of a low-sodium versus a high-sodium diet. Setting: Academic clinical research center. Participants: Healthy, nondiabetic, normotensive volunteers. Interventions: Infusion of exogenous aldosterone (0.7 μg/kg/h for 12.5 h) or vehicle during low or high sodium intake. Low sodium (20 mmol/d; n = 12) vs high sodium (160 mmol/d; n = 17) intake for 5–7 days. Main Outcome Measures: Change in acute insulin secretory response assessed during hyperglycemic clamps while in sodium balance during a low-sodium vs high-sodium diet during aldosterone vs vehicle. Results: A low-sodium diet increased endogenous aldosterone and plasma renin activity, and acute glucose-stimulated insulin (−16.0 ± 5.6%; P = .007) and C-peptide responses (−21.8 ± 8.4%; P = .014) were decreased, whereas the insulin sensitivity index was unchanged (−1.0 ± 10.7%; P = .98). Aldosterone infusion did not affect the acute insulin response (+1.8 ± 4.8%; P = .72) or insulin sensitivity index (+2.0 ± 8.8%; P = .78). Systolic blood pressure and serum potassium were similar during low and high sodium intake and during aldosterone infusion. Conclusions: Low dietary sodium intake reduces insulin secretion in humans, independent of insulin sensitivity. PMID:25029426

  9. Bovine and human insulin adsorption at lipid monolayers: a comparison

    NASA Astrophysics Data System (ADS)

    Mauri, Sergio; Pandey, Ravindra; Rzeznicka, Izabela; Lu, Hao; Bonn, Mischa; Weidner, Tobias

    2015-07-01

    Insulin is a widely used peptide in protein research and it is utilised as a model peptide to understand the mechanics of fibril formation, which is believed to be the cause of diseases such as Alzheimer and Creutzfeld-Jakob syndrome. Insulin has been used as a model system due to its biomedical relevance, small size and relatively simple tertiary structure. The adsorption of insu lin on a variety of surfaces has become the focus of numerous studies lately. These works have helped in elucidating the consequence of surface/protein hydrophilic/hydrophobic interaction in terms of protein refolding and aggregation. Unfortunately, such model surfaces differ significantly from physiological surfaces. Here we spectroscopically investigate the adsorption of insulin at lipid monolayers, to further our understanding of the interaction of insulin with biological surfaces. In particular we study the effect of minor mutations of insulin’s primary amino acid sequence on its interaction with 1,2-Dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) model lipid layers. We probe the structure of bovine and human insulin at the lipid/water interface using sum frequency generation spectroscopy (SFG). The SFG experiments are complemented with XPS analysis of Langmuir-Schaefer deposited lipid/insulin films. We find that bovine and human insulin, even though very similar in sequence, show a substantially different behavior when interacting with lipid films.

  10. Insulin

    MedlinePlus

    ... Information by Audience For Women Women's Health Topics Insulin Share Tweet Linkedin Pin it More sharing options ... medicines. You can do it. Back to Top Insulin Safety Tips Never drink insulin. Do not share ...

  11. Identification of insulin in the human pancreatic juice.

    PubMed

    Ishii, H; Sato, K; Murozono, S

    1986-12-01

    In this study, we purified insulin-like substance (ILS) in the human pancreatic juice by the combined use of affinity chromatography and radioimmunoassay (RIA). The amino acid sequence of ILS in the N-terminal region is the same as that of human insulin. The influence of the enzymes present in the pancreatic juice on the RIA procedure, was examined. Trypsin, chymotrypsin and amylase showed steep influences on radioactivity. The addition of enzyme inhibitors could not reduce pseudo-activity, but the elimination of enzymes in the pancreatic juice by ultrafiltration with the Mole-Cut (Millipore, Japan) resulted in a lowering of the pseudo-insulin activity. Affinity chromatography on Sepharose 4B coupled with anti-porcine insulin was used to capture ILS. ILS was eluted by 1 M acetic acid from the affinity column monitoring pH and the insulin activity by RIA. The amino acid sequences of two components of ILS in amino terminal region were Phe-Val and Gly-Ile-Val. This indicates that ILS obtained from human pancreatic juice was the insulin derived from endocrine secretion of pancreas.

  12. Characterization of proinsulin-insulin intermediates in human plasma.

    PubMed Central

    de Haën, C; Little, S A; May, J M; Williams, R H

    1978-01-01

    This work addressed the problem of heterogeneity of immunoreactive insulin (IRI) in human plasma. Subjects with normal glucose tolerance were given 75g of an oral glucose solution, followed in 30 min by an intravenous infusion of 30g of arginine over 30 min. At the end of the infusion blood was withdrawn for analysis. IRI was extracted from plasma of individual subject by immunosorbent columns and was fractionated by gel filtration, disc gel electrophoresis and isoelectric focusing. Human IRI components were identified by molecular size, immunoreactivity with a human proinsulin antibody, sensitivity to trypsin, and by comparison of electrophoretic mobility and isoelectric point with porcine pancreatic products, after suitable correction for electric charge and molecular weight differences. The pattern of IRI heterogeneity was the same among six healthy subjects. Heterogeneity of proinsulin-size IRI in circulation was more marked than that of insulin-size material. Proinsulin and desdipeptide proinsulin were present in approximately equal amounts accompanied by minor amounts of split proinsulin and monodesamido-desdipeptide proinsulin. Insulin-size IRI contained over 80% insulin. Minor amounts of monodesamidoinsulin and diarginylinsulin were observed in some cases. The types of IRI components observed in plasma are evidence in support of a physiologic role of trypsin-and carboxypeptidase B-like enzymes in the conversion of proinsulin to insulin. Moreover, this study provides a base line for investigation of abnormalities in proinsulin-to-insulin conversion that may be associated with certain pathologic states. PMID:359597

  13. Plasma obestatin is lower at fasting and not suppressed by insulin in insulin-resistant humans.

    PubMed

    Anderwald-Stadler, Marietta; Krebs, Michael; Promintzer, Miriam; Mandl, Martina; Bischof, Martin G; Nowotny, Peter; Kästenbauer, Thomas; Luger, Anton; Prager, Rudolf; Anderwald, Christian

    2007-11-01

    Obestatin, a recently discovered 23-amino acid peptide, is involved in the regulation of appetite and body weight in antagonistic fashion to ghrelin, both deriving from a common precursor peptide. Ghrelin was shown to be associated with insulin resistance, which may also affect obestatin. We investigated the association between insulin resistance and plasma concentrations of obestatin and ghrelin in nondiabetic individuals with high (IS; n = 18, 13 females and 5 males, age 47 +/- 2 yr, BMI = 25.5 +/- 0.9 kg/m(2)) and low (IR; n = 18, 12 females and 6 males, age 45 +/- 2 yr, P = 0.49, BMI = 27.5 +/- 1.1 kg/m(2), P = 0.17) insulin-stimulated glucose disposal (M), measured by 2-h hyperinsulinemic (40 mU.min(-1).m(-2)) isoglycemic clamp tests. M(100-120 min) was higher in IS (10.7 +/- 0.7) than in IR (4.4 +/- 0.2 mg.min(-1).kg(-1), P < 10(-9)), whereas insulin-dependent suppression of free fatty acids (FFA) in plasma was reduced in IR (71 +/- 6% vs. IS: 82 +/- 5%, P < 0.02). In both groups, plasma ghrelin concentrations were comparable at fasting and similarly reduced by 24-28% during insulin infusion. IR had lower fasting plasma obestatin levels (383 +/- 26 pg/ml vs. IS: 469 +/- 23 pg/ml, P < 0.02). Clamp insulin infusion reduced plasma obestatin to approximately 81% of basal values in IS (P < 0.00002), but not in IR. Fasting plasma obestatin was correlated positively with M (r = 0.34, P = 0.04), HDL cholesterol (r = 0.45, P = 0.01), and plasma ghrelin concentrations (r = 0.80, P < 0.000001) and negatively with measures of adiposity, plasma FFA during clamp (r = -0.42, P < 0.01), and systolic blood pressure (r = -0.33, P < 0.05). In conclusion, fasting plasma concentrations of obestatin, but not of ghrelin, are reduced in insulin resistance and are positively associated with whole body insulin sensitivity in nondiabetic humans. Furthermore, plasma obestatin is reduced by insulin in insulin-sensitive but not in insulin-resistant persons.

  14. (A-C-B) human proinsulin, a novel insulin agonist and intermediate in the synthesis of biosynthetic human insulin.

    PubMed

    Heath, W F; Belagaje, R M; Brooke, G S; Chance, R E; Hoffmann, J A; Long, H B; Reams, S G; Roundtree, C; Shaw, W N; Slieker, L J

    1992-01-05

    The hormone insulin is synthesized in the beta cell of the pancreas as the precursor, proinsulin, where the carboxyl terminus of the B-chain is connected to the amino terminus of the A-chain by a connecting or C-peptide. Proinsulin is a weak insulin agonist that possesses a longer in vivo half-life than does insulin. A form of proinsulin clipped at the Arg65-Gly66 bond has been shown to be more potent than the parent molecule with protracted in vivo activity, presumably as a result of freeing the amino terminal residue of the A-chain. To generate a more active proinsulin-like molecule, we have constructed an "inverted" proinsulin molecule where the carboxyl terminus of the A-chain is connected to the amino terminus of the B-chain by the C-peptide, leaving the critical Gly1 residue free. Transformation of Escherichia coli with a plasmid coding for A-C-B human proinsulin led to the stable production of the protein. By a process of cell disruption, sulfitolysis, anion-exchange chromatography, refolding, and reversed-phase high-performance liquid chromatography, two forms of the inverted proinsulin differing at their amino termini as Gly1 and Met0-Gly1 were identified and purified to homogeneity. Both proteins were shown by a number of analytical techniques to be of the inverted sequence, with insulin-like disulfide bonding. Biological analyses by in vitro techniques revealed A-C-B human proinsulin to be intermediate in potency when compared to human insulin and proinsulin. The time to maximal lowering of blood glucose in the fasted normal rat appeared comparable to that of proinsulin. Additionally, we were able to generate fully active, native insulin from A-C-B human proinsulin by proteolytic transformation. The results of this study lend themselves to the generation of novel insulin-like peptides while providing a simplified route to the biosynthetic production of insulin.

  15. Influence of PAMAM dendrimers on the human insulin

    NASA Astrophysics Data System (ADS)

    Nowacka, Olga; Miłowska, Katarzyna; Ionov, Maksim; Bryszewska, Maria

    2015-12-01

    Dendrimers are specific class of polymeric macromolecules with wide spectrum of properties. One of the promising activities of dendrimers involves inhibition of protein fibril formation. Aggregation and fibrillation of insulin occurs in insulin-dependent diabetic patients after repeated administration, due to these processes being very easily triggered by the conditions of drug administration. The aim of this work was to study the influence of various generations PAMAM dendrimers on human insulin zeta potential, secondary structure and dithiotreitol (DTT)-induced aggregation. We observed the dependence between the number of positive charges on the surface of the PAMAM dendrimer and the values of zeta potential. Addition of dendrimers to insulin caused insignificant changes in the secondary structure. There was a small decrease in ellipticity, but it did not result in alterations in the circular dichroism (CD) spectrum shape. Dendrimers neither induced protein aggregation nor inhibited the aggregation process induced by DTT, except for 0.01 µmol/l concentration.

  16. Oral Insulin: A Comparison With Subcutaneous Regular Human Insulin in Patients With Type 2 Diabetes

    PubMed Central

    Kapitza, Christoph; Zijlstra, Eric; Heinemann, Lutz; Castelli, M. Cristina; Riley, Gary; Heise, Tim

    2010-01-01

    OBJECTIVE To determine the pharmacokinetic and pharmacodynamic properties of an oral insulin (OI) formulation compared with subcutaneously injected regular human insulin (RHI). RESEARCH DESIGN AND METHODS Ten male patients with type 2 diabetes (means ± SD; A1C 7.0 ± 1.1%; BMI 28.3 ± 2.7 kg/m2) received either 300 units of insulin combined with 400 mg of delivery agent orally or 15 units RHI subcutaneously under isoglycemic clamp conditions. RESULTS Maximum insulin concentration was greater and onset of action was faster with OI (Cmax 93 ± 71 vs. 33 ± 11 μU/ml; AUCGIR(0−1h) 173 ± 86 vs. 27 ± 32 mg/kg; P < 0.05). Mean insulin concentration and glucose infusion rate returned to baseline within 3 h after OI administration. Relative bioavailability of OI was 7 ± 4% (1st 2 h). CONCLUSIONS This proof-of-concept study demonstrated that absorption of OI is feasible under fasting conditions. OI has a fast onset and a short duration of action but also shows a rather high between-subject variability in absorption. PMID:20185734

  17. Comparative double-blind trial of the effectiveness and antigenicity of semisynthetic human insulin and purified porcine insulin in newly treated diabetic subjects.

    PubMed

    Larkins, R G; Zajac, J; Saunders, R; Read, A; Hopper, J L

    1986-04-01

    A double-blind comparative trial of the effectiveness and antigenicity of semisynthetic human insulin (Novo) and highly purified (Monocomponent) porcine insulin was performed over a 12 month period in 20 diabetic subjects newly treated with insulin. Human insulin was shown to be indistinguishable from porcine insulin of comparable purity with respect to plasma glucose and glycosylated hemoglobin levels and insulin dose requirements. Human insulin was no less antigenic than porcine insulin; significant IgG-associated insulin binding activity was detected in six of the ten patients in the human insulin treated group and four of the ten patients in the porcine insulin treated group. In all patients, the binding activity was of low capacity. No adverse reactions to human insulin were noted. It is concluded that semisynthetic human insulin, like purified porcine insulin, is safe and effective. Although there may be advantages for human insulin in the setting of insulin allergy, this study does not indicate that human insulin has advantages over purified porcine insulin with respect to elicitation of antibodies of the IgG class.

  18. Premixed turbulent flame calculation

    NASA Technical Reports Server (NTRS)

    El-Tahry, S.; Rutland, C. J.; Ferziger, J. H.; Rogers, M. M.

    1987-01-01

    The importance of turbulent premixed flames in a variety of applications has led to a substantial amount of effort towards improving the understanding of these flames. Although these efforts have increased the understanding, many questions still remain. The use of direct numerical simulation (DNS) in solving these questions is examined.

  19. The effect of insulin dose on the measurement of insulin sensitivity by the minimal model technique. Evidence for saturable insulin transport in humans.

    PubMed Central

    Prigeon, R L; Røder, M E; Porte, D; Kahn, S E

    1996-01-01

    Administration of exogenous insulin during an intravenous glucose tolerance test allows the use of the minimal model technique to determine the insulin sensitivity index in subjects with reduced endogenous insulin responses. To study the effect of different insulin administration protocols, we performed three intravenous glucose tolerance tests in each of seven obese subjects (age, 20-41 yr; body mass index, 30-43 kg/m2). Three different insulin administration protocols were used: a low-dose (0.025 U/kg) infusion given over 10 min, a low-dose (0.025 U/kg) bolus injection, and a high-dose (0.050 U/kg) bolus injection, resulting in peak insulin concentrations of 1,167 +/- 156, 3,014 +/- 483, and 6,596 +/- 547 pM, respectively. The mean insulin sensitivity index was 4.80 +/- 0.95 x 10(-5), 3.56 +/- 0.53 x 10(-5), and 2.42 +/- 0.40 x 10(-5) min-1/pM respectively (chi +/- SEM; P = 0.01). The association of higher peak insulin concentrations with lower measured insulin sensitivity values suggested the presence of a saturable process. Because results were not consistent with the known saturation characteristics of insulin action on tissue, a second saturable site involving the transport of insulin from plasma to interstitium was introduced, leading to a calculated Km of 807 +/- 165 pM for this site, a value near the 1/Kd of the insulin receptor. Thus, the kinetics of insulin action in humans in these studies is consistent with two saturable sites, and supports the hypothesis for transport of insulin to the interstitial space. Saturation may have an impact on minimal model results when high doses of exogenous insulin are given as a bolus, but can be minimized by infusing insulin at a low dose. PMID:8567973

  20. Interleukin-1β inhibits insulin signaling and prevents insulin-stimulated system A amino acid transport in primary human trophoblasts.

    PubMed

    Aye, Irving L M H; Jansson, Thomas; Powell, Theresa L

    2013-12-05

    Interleukin-1β (IL-1β) promotes insulin resistance in tissues such as liver and skeletal muscle; however the influence of IL-1β on placental insulin signaling is unknown. We recently reported increased IL-1β protein expression in placentas of obese mothers, which could contribute to insulin resistance. In this study, we tested the hypothesis that IL-1β inhibits insulin signaling and prevents insulin-stimulated amino acid transport in cultured primary human trophoblast (PHT) cells. Cultured trophoblasts isolated from term placentas were treated with physiological concentrations of IL-1β (10pg/ml) for 24h. IL-1β increased the phosphorylation of insulin receptor substrate-1 (IRS-1) at Ser307 (inhibitory) and decreased total IRS-1 protein abundance but did not affect insulin receptor β expression. Furthermore, IL-1β inhibited insulin-stimulated phosphorylation of IRS-1 (Tyr612, activation site) and Akt (Thr308) and prevented insulin-stimulated increase in PI3K/p85 and Grb2 protein expression. IL-1β alone stimulated cRaf (Ser338), MEK (Ser221) and Erk1/2 (Thr202/Tyr204) phosphorylation. The inflammatory pathways nuclear factor kappa B and c-Jun N-terminal kinase, which are involved in insulin resistance, were also activated by IL-1β treatment. Moreover, IL-1β inhibited insulin-stimulated System A, but not System L amino acid uptake, indicating functional impairment of insulin signaling. In conclusion, IL-1β inhibited the insulin signaling pathway by inhibiting IRS-1 signaling and prevented insulin-stimulated System A transport, thereby promoting insulin resistance in cultured PHT cells. These findings indicate that conditions which lead to increased systemic maternal or placental IL-1β levels may attenuate the effects of maternal insulin on placental function and consequently fetal growth.

  1. Effects of Dietary n-3 Fatty Acids on Hepatic and Peripheral Insulin Sensitivity in Insulin-Resistant Humans

    PubMed Central

    Lalia, Antigoni Z.; Johnson, Matthew L.; Jensen, Michael D.; Hames, Kazanna C.; Port, John D.

    2015-01-01

    OBJECTIVE Dietary n-3 polyunsaturated fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), prevent insulin resistance and stimulate mitochondrial biogenesis in rodents, but the findings of translational studies in humans are thus far ambiguous. The aim of this study was to evaluate the influence of EPA and DHA on insulin sensitivity, insulin secretion, and muscle mitochondrial function in insulin-resistant, nondiabetic humans using a robust study design and gold-standard measurements. RESEARCH DESIGN AND METHODS Thirty-one insulin-resistant adults received 3.9 g/day EPA+DHA or placebo for 6 months in a randomized double-blind study. Hyperinsulinemic-euglycemic clamp with somatostatin was used to assess hepatic and peripheral insulin sensitivity. Postprandial glucose disposal and insulin secretion were measured after a meal. Measurements were performed at baseline and after 6 months of treatment. Abdominal fat distribution was evaluated by MRI. Muscle oxidative capacity was measured in isolated mitochondria using high-resolution respirometry and noninvasively by magnetic resonance spectroscopy. RESULTS Compared with placebo, EPA+DHA did not alter peripheral insulin sensitivity, postprandial glucose disposal, or insulin secretion. Hepatic insulin sensitivity, determined from the suppression of endogenous glucose production by insulin, exhibited a small but significant improvement with EPA+DHA compared with placebo. Muscle mitochondrial function was unchanged by EPA+DHA or placebo. CONCLUSIONS This study demonstrates that dietary EPA+DHA does not improve peripheral glucose disposal, insulin secretion, or skeletal muscle mitochondrial function in insulin-resistant nondiabetic humans. There was a modest improvement in hepatic insulin sensitivity with EPA+DHA, but this was not associated with any improvements in clinically meaningful outcomes. PMID:25852206

  2. Cellular reprogramming of human amniotic fluid cells to express insulin.

    PubMed

    Gage, Blair K; Riedel, Michael J; Karanu, Francis; Rezania, Alireza; Fujita, Yukihiro; Webber, Travis D; Baker, Robert K; Wideman, Rhonda D; Kieffer, Timothy J

    2010-01-01

    Islet transplantation represents a potential cure for type 1 diabetes; however, a lack of sufficient donor material limits its clinical use. To address the shortfall of islet availability, surrogate insulin-producing cells are sought. Studies suggest that human amniotic fluid (hAF) contains multipotent progenitor cells capable of differentiating to all three germ layers. Here, we used high-content, live-cell imaging to assess the ability to reprogram hAF cells towards a beta cell phenotype. A fluorescent reporter system was developed where DsRed express (DSRE) expression is driven by the human insulin promoter. Using integrative lentiviral technology, we created stable reporter hAF cells that could be routinely monitored for insulin promoter activation. These cells were subjected to combinatorial high-content screening using adenoviral-mediated expression of up to six transcription factors important for beta cell development. Cells were monitored for DSRE expression which revealed an optimal combination of the transcription factors required to induce insulin gene expression in hAF cells. These optimally induced cells were examined for expression of additional beta cell transcription factors and proteins involved in glucose sensing and insulin processing. RT-qPCR revealed very low level expression of insulin that was ultimately insufficient to reverse streptozotocin-induced diabetes following sub-capsular kidney transplantation. High-content, live-cell imaging using fluorescent reporter cells provides a convenient method for repeated assessment of cellular reprogramming. hAF cells could be reprogrammed to express key beta cell proteins, however insulin gene expression was insufficient to reverse hyperglycemia in diabetic animals. Copyright © 2010 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.

  3. Premixed Turbulent Flame Propagation in Microgravity

    NASA Technical Reports Server (NTRS)

    Menon, S.; Disseau, M.; Chakravarthy, V. K.; Jagoda, J.

    1997-01-01

    Papers included address the following topics: (1) Turbulent premixed flame propagation in microgravity; (2) The effect of gravity on turbulent premixed flame propagation - a preliminary cold flow study; and (3) Characteristics of a subgrid model for turbulent premixed combustion.

  4. A new C-Peptide correction model used to assess bioavailability of regular human insulin.

    PubMed

    Marino, M T; Cassidy, J P; Baughman, R A; Boss, A H; Richardson, P C

    2010-10-01

    The clinical assessment of new formulations of human insulin is problematic due to the inability to distinguish between endogenous insulin and exogenously administered insulin. The usual methods to surmount the problem of distinguishing between endogenous and exogenous human insulin include evaluation in subjects with no or little endogenous insulin, hyper-insulinemic clamp studies or the administration of somatostatin to suppress endogenous insulin secretion. All of these methods have significant drawbacks. This paper describes a method for C-Peptide correction based upon a mixed effects linear regression of multiple time point sampling of C-Peptide and insulin. This model was able to describe each individual's insulin to C-Peptide relationship using the data from four different phase I clinical trials involving both subjects with and without type 2 diabetes in which insulin and C-Peptide were measured. These studies used hyper-insulinemic euglycemic clamps or meal challenges and subjects received insulin or Glucagon-like peptide 1 (GLP-1). It was possible to determine the exogenously administered insulin concentration from the measured total insulin concentration. A simple statistical technique can be used to determine each individual's insulin to C-Peptide relationship to estimate exogenous and endogenous insulin following the administration of regular human insulin. This technique will simplify the assessment of new formulations of human insulin.

  5. Premixed direct injection nozzle

    DOEpatents

    Zuo, Baifang [Simpsonville, SC; Johnson, Thomas Edward [Greer, SC; Lacy, Benjamin Paul [Greer, SC; Ziminsky, Willy Steve [Simpsonville, SC

    2011-02-15

    An injection nozzle having a main body portion with an outer peripheral wall is disclosed. The nozzle includes a plurality of fuel/air mixing tubes disposed within the main body portion and a fuel flow passage fluidly connected to the plurality of fuel/air mixing tubes. Fuel and air are partially premixed inside the plurality of the tubes. A second body portion, having an outer peripheral wall extending between a first end and an opposite second end, is connected to the main body portion. The partially premixed fuel and air mixture from the first body portion gets further mixed inside the second body portion. The second body portion converges from the first end toward said second end. The second body portion also includes cooling passages that extend along all the walls around the second body to provide thermal damage resistance for occasional flame flash back into the second body.

  6. Postprandial blood glucose response to a standard test meal in insulin-requiring patients with diabetes treated with insulin lispro mix 50 or human insulin mix 50.

    PubMed

    Gao, Y; Li, G; Li, Y; Guo, X; Yuan, G; Gong, Q; Yan, L; Zheng, Y; Zhang, J

    2008-09-01

    To compare the 2-h postprandial blood glucose (PPBG) excursion following a standard test meal in insulin-requiring patients with diabetes treated twice daily with human insulin mix 50 vs. insulin lispro mix 50 (LM50). This was a multicentre, randomised, open-label, crossover comparison of two insulin treatments for two 12-week treatment periods in 120 Chinese patients. One- and 2-h PPBG and excursion values were obtained following a standardised test meal. Fasting blood glucose (FBG), haemoglobin A1c (HbA1c), insulin dose, rate of hypoglycaemia and safety data were obtained. A crossover analysis using SAS Proc MIXED was employed. Mean 2-h PPBG excursion decreased from 6.32 +/- 3.07 mmol/l at baseline to 3.47 +/- 2.97 mmol/l at end-point in the LM50 group, and from 6.31 +/- 2.88 at baseline to 5.02 +/- 3.32 mmol/l at end-point in the human insulin mix 50 group (p < 0.001). Two-hour PPBG (p = 0.004) and 1-h PPBG excursion (p < 0.001) were significantly lower with LM50 as compared with human insulin mix 50. Both treatment groups were equivalent for HbA1c control, 1-h PPBG and insulin dose requirements. Mean FBG was higher with LM50 than with human insulin mix 50 (p = 0.023). The overall incidence of treatment-emergent adverse events and hypoglycaemia rate per 30 days were similar between treatment groups. Insulin lispro mix 50 provided better postprandial glycaemic control compared with human insulin mix 50 while providing the convenience of injecting immediately before meals. Both treatments were generally well tolerated by all randomly assigned patients.

  7. Comparison of Human and Bovine Insulin Amyloidogenesis under Uniform Shear.

    PubMed

    McBride, Samantha A; Tilger, Christopher F; Sanford, Sean P; Tessier, Peter M; Hirsa, Amir H

    2015-08-20

    A diverse range of proteins can assemble into amyloid fibrils, a process that generally results in a loss of function and an increase in toxicity. The occurrence and rate of conversion is strongly dependent on several factors including molecular structure and exposure to hydrodynamic forces. To investigate the origins of shear-induced enhancement in the rate of fibrillization, a stable rotating Couette flow was used to evaluate the kinetics of amyloid formation under uniform shear for two similar insulin species (human and bovine) that demonstrate unique fibrillization kinetics. The presence of shear-induced nuclei predicted by previous studies is supported by observations of a lag between the consumption of soluble insulin and the precipitation of amyloid aggregates. The apparent fibrillization rate generally increases with shear. However, a two-parameter kinetic model revealed that the nucleation rate has a maximum value at intermediate shear rates. The fibril elongation rate increases monotonically with shear and is similar for both insulin variants, suggesting that increased elongation rates are related to mixing. Differences between human and bovine insulin kinetics under shear are attributable to the nucleation step.

  8. Free insulin-like growth factors in human obesity.

    PubMed

    Frystyk, J; Vestbo, E; Skjaerbaek, C; Mogensen, C E; Orskov, H

    1995-10-01

    It is well established that spontaneous and stimulated growth hormone (GH) secretion is diminished in human obesity. In contrast to classic GH deficiency, obesity is not associated with hypopituitary levels of circulating total (extractable) insulin-like growth factor-I (IGF-I) and reduced somatic growth. Thus, the riddle of "normal growth without GH" in obese children and the mechanisms behind the GH suppression have remained unsolved. Insulin reduces hepatic production of IGF-binding protein-1 (IGFBP-1), an in vitro inhibitor of IGF bioactivity, and it has been suggested that the obesity-related hyperinsulinemia may increase free (bioactive) IGF in vivo by reducing the concentration of IGFBP-1. We have recently developed a method that during near in vivo conditions isolates the free, unbound fractions of IGF-I and IGF-II in human serum. Using this method, we have determined overnight fasting serum levels of free IGFs in obese subjects and compared the results with levels of total (extractable) IGFs, IGFBPs, GH, and insulin. The study included 92 healthy subjects (56 males and 36 females) allocated to three age-matched groups depending on body mass index (BMI): 31 controls (BMI < or = 25), 33 subjects with moderate obesity (25 < BMI < 30), and 28 subjects with severe obesity (BMI > or = 30). Fasting serum insulin correlated positively (r = .61, P < .0001) with BMI and was significantly elevated in moderate and severe obesity (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Characterization of the growth of murine fibroblasts that express human insulin receptors. II. Interaction of insulin with other growth factors

    SciTech Connect

    Randazzo, P.A.; Jarett, L. )

    1990-09-01

    The effects of insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and insulin on DNA synthesis were studied in murine fibroblasts transfected with an expression vector containing human insulin receptor cDNA (NIH 3T3/HIR) and the parental NIH 3T3 cells. In NIH 3T3/HIR cells, individual growth factors in serum-free medium stimulated DNA synthesis with the following relative efficacies: insulin greater than or equal to 10% fetal calf serum greater than PDGF greater than IGF-1 much greater than EGF. In comparison, the relative efficacies of these factors in stimulating DNA synthesis by NIH 3T3 cells were 10% fetal calf serum greater than PDGF greater than EGF much greater than IGF-1 = insulin. In NIH 3T3/HIR cells, EGF was synergistic with 1-10 ng/ml insulin but not with 100 ng/ml insulin or more. Synergy of PDGF or IGF-1 with insulin was not detected. In the parental NIH 3T3 cells, insulin and IGF-1 were found to be synergistic with EGF (1 ng/ml), PDGF (100 ng/ml), and PDGF plus EGF. In NIH 3T3/HIR cells, the lack of interaction of insulin with other growth factors was also observed when the percentage of cells synthesizing DNA was examined. Despite insulin's inducing only 60% of NIH 3T3/HIR cells to incorporate thymidine, addition of PDGF, EGF, or PDGF plus EGF had no further effect. In contrast, combinations of growth factors resulted in 95% of the parental NIH 3T3 cells synthesizing DNA. The independence of insulin-stimulated DNA synthesis from other mitogens in the NIH 3T3/HIR cells is atypical for progression factor-stimulated DNA synthesis and is thought to be partly the result of insulin receptor expression in an inappropriate context or quantity.

  10. Insulin signaling in type 2 diabetes: experimental and modeling analyses reveal mechanisms of insulin resistance in human adipocytes.

    PubMed

    Brännmark, Cecilia; Nyman, Elin; Fagerholm, Siri; Bergenholm, Linnéa; Ekstrand, Eva-Maria; Cedersund, Gunnar; Strålfors, Peter

    2013-04-05

    Type 2 diabetes originates in an expanding adipose tissue that for unknown reasons becomes insulin resistant. Insulin resistance reflects impairments in insulin signaling, but mechanisms involved are unclear because current research is fragmented. We report a systems level mechanistic understanding of insulin resistance, using systems wide and internally consistent data from human adipocytes. Based on quantitative steady-state and dynamic time course data on signaling intermediaries, normally and in diabetes, we developed a dynamic mathematical model of insulin signaling. The model structure and parameters are identical in the normal and diabetic states of the model, except for three parameters that change in diabetes: (i) reduced concentration of insulin receptor, (ii) reduced concentration of insulin-regulated glucose transporter GLUT4, and (iii) changed feedback from mammalian target of rapamycin in complex with raptor (mTORC1). Modeling reveals that at the core of insulin resistance in human adipocytes is attenuation of a positive feedback from mTORC1 to the insulin receptor substrate-1, which explains reduced sensitivity and signal strength throughout the signaling network. Model simulations with inhibition of mTORC1 are comparable with experimental data on inhibition of mTORC1 using rapamycin in human adipocytes. We demonstrate the potential of the model for identification of drug targets, e.g. increasing the feedback restores insulin signaling, both at the cellular level and, using a multilevel model, at the whole body level. Our findings suggest that insulin resistance in an expanded adipose tissue results from cell growth restriction to prevent cell necrosis.

  11. Analysis of alternatives for insulinizing patients to achieve glycemic control and avoid accompanying risks of hypoglycemia.

    PubMed

    Gao, Jialin; Xiong, Qianyin; Miao, Jun; Zhang, Yao; Xia, Libing; Lu, Meiqin; Zhang, Binhua; Chen, Yueping; Zhang, Ansu; Yu, Cui; Wang, Li-Zhuo

    2015-05-01

    The aims of the present study were to explore the efficacy of glycemic control and the risks of hypoglycemia with different methods of insulin therapy, and to provide reference data for the clinical treatment of diabetes. In this retrospective study, hospitalized patients diagnosed with type 2 diabetes between March and December 2014, in the Department of Endocrinology in the First Affiliated Hospital of Wannan Medical College, were divided into three groups, including an intensive insulin analogue therapy group, a premixed insulin analogue treatment group and a premixed human insulin therapy group. The efficacy of glycemic control and the incidence of hypoglycemia were determined in each of the insulin treatment groups. Compared with the other treatment groups, the intensive insulin analogue therapy group was associated with superior blood glucose control, shorter time to reach standard insulin regimen, shorter hospitalization time, fewer fluctuations in blood glucose levels and lower insulin dosage on discharge from hospital. However, this treatment was also associated with a high risk of hypoglycemia. In conclusion, when combined with the effective prevention of hypoglycemia and appropriate nursing care (especially in hospital care), intensive insulin analogue therapy may provide the greatest benefit to patients.

  12. Human insulin B24 (Phe----Ser). Secretion and metabolic clearance of the abnormal insulin in man and in a dog model.

    PubMed Central

    Shoelson, S E; Polonsky, K S; Zeidler, A; Rubenstein, A H; Tager, H S

    1984-01-01

    We have already demonstrated that a hyperinsulinemic, diabetic subject secreted an abnormal insulin in which serine replaced phenylalanine B24 (Shoelson S., M. Fickova, M. Haneda, A. Nahum, G. Musso, E. T. Kaiser, A. H. Rubenstein, and H. Tager. 1983. Proc. Natl. Acad. Sci. USA. 80:7390-7394). High performance liquid chromatography analysis now shows that the circulating insulin in several other family members also consists of a mixture of the abnormal human insulin B24 (Phe----Ser) and normal human insulin in a ratio of approximately 9.5:1 during fasting. Although all affected subjects show fasting hyperinsulinemia, only the propositus and her father are overtly diabetic. Analysis of the serum insulin from two nondiabetic siblings revealed that normal insulin increased from approximately 2 to 15% of total serum insulin after the ingestion of glucose and that the proportion of the normal hormone plateaued or fell while the level of total insulin continued to rise. Animal studies involving the graded intraportal infusion of equimolar amounts of semisynthetic human [SerB24]-insulin and normal human insulin in pancreatectomized dogs (to simulate the secretion of insulin due to oral glucose in man) also showed both a rise in the fraction of normal insulin that reached the periphery and the attainment of a brief steady state in this fraction while total insulin levels continued to rise. Separate experiments documented a decreased hepatic extraction, a decreased metabolic clearance rate, and an increased plasma half-life of human [SerB24]-insulin within the same parameters as those determined for normal human insulin. These results form a basis for considering (a) the differential clearance of low activity abnormal insulins and normal insulin from the circulation in vivo, and (b) the causes of hyperinsulinemia in both diabetic and nondiabetic individuals who secrete abnormal human insulins. PMID:6371057

  13. Molecular Basis of Catalytic Chamber-assisted Unfolding and Cleavage of Human Insulin by Human Insulin-degrading Enzyme*S⃞

    PubMed Central

    Manolopoulou, Marika; Guo, Qing; Malito, Enrico; Schilling, Alexander B.; Tang, Wei-Jen

    2009-01-01

    Insulin is a hormone vital for glucose homeostasis, and insulin-degrading enzyme (IDE) plays a key role in its clearance. IDE exhibits a remarkable specificity to degrade insulin without breaking the disulfide bonds that hold the insulin A and B chains together. Using Fourier transform ion cyclotron resonance (FTICR) mass spectrometry to obtain high mass accuracy, and electron capture dissociation (ECD) to selectively break the disulfide bonds in gas phase fragmentation, we determined the cleavage sites and composition of human insulin fragments generated by human IDE. Our time-dependent analysis of IDE-digested insulin fragments reveals that IDE is highly processive in its initial cleavage at the middle of both the insulin A and B chains. This ensures that IDE effectively splits insulin into inactive N- and C-terminal halves without breaking the disulfide bonds. To understand the molecular basis of the recognition and unfolding of insulin by IDE, we determined a 2.6-Å resolution insulin-bound IDE structure. Our structure reveals that IDE forms an enclosed catalytic chamber that completely engulfs and intimately interacts with a partially unfolded insulin molecule. This structure also highlights how the unique size, shape, charge distribution, and exosite of the IDE catalytic chamber contribute to its high affinity (∼100 nm) for insulin. In addition, this structure shows how IDE utilizes the interaction of its exosite with the N terminus of the insulin A chain as well as other properties of the catalytic chamber to guide the unfolding of insulin and allowing for the processive cleavages. PMID:19321446

  14. Changes in insulin therapy regimens over 10 yr in children and adolescents with type 1 diabetes attending diabetes camps.

    PubMed

    Redon, Isabelle; Beltrand, Jacques; Martin, Delphine; Taupin, Pierre; Choleau, Carine; Morandini, Mélina; Cahané, Michel; Robert, Jean-Jacques

    2014-08-01

    To describe the changes in insulin therapy regimens of children and adolescents with type 1 diabetes over 10 yr and their correlation with hemoglobin A1c (HbA1c). The study included 7206 children and adolescents (age 12.8 ± 2.7 yr, more than 1 yr of diabetes duration) admitted in summer camps between 1998 and 2007 (707-896/yr). Based on injection times (breakfast, lunch, afternoon, dinner, bedtime) and insulin types (short, long and premixed; human or analog), 786 different therapeutic combinations were classified in six main types of regimens. The distribution of the different regimens and their correlation with HbA1c were evaluated as a function of year and age. Over 10 yr, basal bolus increased from 13 to 52% and the pump from <1 to 13%, regimens with two to three injections per day decreased from 50 to 25%, those with only premixed insulins from 33 to 7%, and diverse regimens from 9 to 1%. HbA1c was significantly higher with premixed insulin only, but there were no differences between the other regimens throughout the follow-up. Mean yearly HbA1c (8.21-8.45%) did not show any significant decrease, but the percentage of patients with HbA1c > 9 and 10% decreased significantly, in those treated with two to three injections and the pump, not with basal bolus or premixed only regimens. A major trend in intensifying insulin treatment in children and adolescents with type 1 diabetes was accompanied by modest improvements in HbA1c. No insulin regimen has shown any better results, except over premixed insulins. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Insulin-like growth factor I stimulates lipid oxidation, reduces protein oxidation, and enhances insulin sensitivity in humans.

    PubMed Central

    Hussain, M A; Schmitz, O; Mengel, A; Keller, A; Christiansen, J S; Zapf, J; Froesch, E R

    1993-01-01

    To elucidate the effects of insulin-like growth factor I (IGF-I) on fuel oxidation and insulin sensitivity, eight healthy subjects were treated with saline and recombinant human (IGF-I (10 micrograms/kg.h) during 5 d in a crossover, randomized fashion, while receiving an isocaloric diet (30 kcal/kg.d) throughout the study period. On the third and fourth treatment days, respectively, an L-arginine stimulation test and an intravenous glucose tolerance test were performed. A euglycemic, hyperinsulinemic clamp combined with indirect calorimetry and a glucose tracer infusion were performed on the fifth treatment day. IGF-I treatment led to reduced fasting and stimulated (glucose and/or L-arginine) insulin and growth hormone secretion. Basal and stimulated glucagon secretion remained unchanged. Intravenous glucose tolerance was unaltered despite reduced insulin secretion. Resting energy expenditure and lipid oxidation were both elevated, while protein oxidation was reduced, and glucose turnover rates were unaltered on the fifth treatment day with IGF-I as compared to the control period. Enhanced lipolysis was reflected by elevated circulating free fatty acids. Moreover, insulin-stimulated oxidative and nonoxidative glucose disposal (i.e., insulin sensitivity) were enhanced during IGF-I treatment. Thus, IGF-I treatment leads to marked changes in lipid and protein oxidation, whereas, at the dose used, carbohydrate metabolism remains unaltered in the face of reduced insulin levels and enhanced insulin sensitivity. Images PMID:8227340

  16. [Reflections of a clinician on the switch from human to analogue insulin treatment].

    PubMed

    Deák, László

    2012-10-07

    The development of insulin therapy has not been stopped since the manufacturing of human insulin, because better mimic of physiological insulin response made it necessary to modify the human insulin molecule in order to create rapidly absorbing insulin analogues and 24-hour acting basal insulin analogues. Clinical observations indicate that the complete switch from human basal-bolus therapy to insulin analogues means not only "unit-for-unit" switch but it represents a transfer to an insulin therapy with different basal/bolus ratio as a result of different pharmacokinetic and pharmacodynamic properties of insulin and the level of insulin resistance of the patient. With reference to a case-history, the author presents his experience on a switch from human insulin to insulin analogue. Furthermore, the author summarizes data obtained from a few cases reported in international literature which draw the attention to the fact that the basal/bolus ratio should be adjusted individually, which may be the key for the success in the therapy in these cases.

  17. Ingested human insulin inhibits the mosquito NF-¿B-dependent immune response to Plasmodium falciparum

    USDA-ARS?s Scientific Manuscript database

    We showed previously that ingested human insulin activates the insulin/IGF-1 signaling pathway in Anopheles stephensi and increases the susceptibility of these mosquitoes to Plasmodium falciparum. In other organisms insulin can alter immune responsiveness through regulation of NF-kB transcription fa...

  18. Insulin adherence and persistence among Chinese patients with type 2 diabetes: a retrospective database analysis

    PubMed Central

    He, Xiaoning; Chen, Liming; Wang, Ke; Wu, Haiya; Wu, Jing

    2017-01-01

    Objective To assess adherence and persistence to insulin therapy and identify its associated factors among Chinese insulin-naïve patients with type 2 diabetes (T2D). Methods Tianjin Urban Employee Basic Medical Insurance claims database was used (2008–2011). Adult patients with T2D who initiated insulin therapy during January 2009 through December 2010 and were continuously enrolled for 12 months pre-(baseline) and 12 months post-initiation (follow-up) were included. Patients who had a ≥80% medication possession ratio were deemed adherent, while patients who had no gaps of ≥90 days in insulin therapy were deemed persistent. Associated factors of insulin adherence and persistence were detected by univariate and multivariate analyses. Results A total of 24,192 patients were included; the patients had a mean age of 58.9 years, with 49.5% being female. About 51.9% of the patients had human insulin as initiation therapy, while 39.1% were initiated with insulin analog and 9.0% with animal-derived insulin. Premixed insulin (77.3%) was prescribed most often in comparison with basal (11.8%) and prandial (10.9%) insulin. Only 30.9% of patients were adherent, and the mean (standard deviation) medication possession ratio was 0.499 (0.361). About 53.0% of patients persisted insulin therapy during follow-up, and the mean time to nonpersistence was 230.3 (145.5) days. Patients initiated with analog were more likely to be adherent (adjusted odds ratio: 1.07, P=0.036) and persistent (adjusted hazard ratio: 0.88, P<0.001) compared with those initiated with human insulin. Patients initiation with basal insulin had lower adherence relative to premixed (adjusted odds ratio: 0.79, P<0.001). Patients comorbid with hypertension or dyslipidemia, initiated with prandial insulin, and with baseline severe hypoglycemic events were more likely to be nonadherent/nonpersistent. Conclusion The insulin adherence and persistence among Chinese patients with T2D are generally poor. Initiation

  19. Insulin

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The manipulation of organic materials--cells, tissues, and even living organisms--offers many exciting possibilities for the future from organic computers to improved aquaculture. Commercial researchers are using the microgravity environment to produce large near perfect protein crystals Research on insulin has yielded crystals that far surpass the quality of insulin crystals grown on the ground. Using these crystals industry partners are working to develop new and improved treatments for diabetes. Other researchers are exploring the possibility of producing antibiotics using plant cell cultures which could lead to both orbital production and the improvement of ground-based antibiotic production.

  20. Premixed direct injection disk

    SciTech Connect

    York, William David; Ziminsky, Willy Steve; Johnson, Thomas Edward; Lacy, Benjamin; Zuo, Baifang; Uhm, Jong Ho

    2013-04-23

    A fuel/air mixing disk for use in a fuel/air mixing combustor assembly is provided. The disk includes a first face, a second face, and at least one fuel plenum disposed therebetween. A plurality of fuel/air mixing tubes extend through the pre-mixing disk, each mixing tube including an outer tube wall extending axially along a tube axis and in fluid communication with the at least one fuel plenum. At least a portion of the plurality of fuel/air mixing tubes further includes at least one fuel injection hole have a fuel injection hole diameter extending through said outer tube wall, the fuel injection hole having an injection angle relative to the tube axis. The invention provides good fuel air mixing with low combustion generated NOx and low flow pressure loss translating to a high gas turbine efficiency, that is durable, and resistant to flame holding and flash back.

  1. Lean premixed/prevaporized combustion

    NASA Technical Reports Server (NTRS)

    Lefebvre, A. H. (Editor)

    1977-01-01

    Recommendations were formulated on the status and application of lean premixed/prevaporized combustion to the aircraft gas turbine for the reduction of pollutant emissions. The approach taken by the NASA Stratospheric Cruise Emission Reduction Program (SCERP) in pursuing the lean premixed/prevaporized combustion technique was also discussed. The proceedings contains an overview of the SCERP program, the discussions and recommendations of the participants, and an overall summary.

  2. Mechanisms of insulin resistance in human obesity: evidence for receptor and postreceptor defects.

    PubMed Central

    Kolterman, O G; Insel, J; Saekow, M; Olefsky, J M

    1980-01-01

    To assess the mechanisms of the insulin resistance in human obesity, we have determined, using a modification of the euglycemic glucose clamp technique, the shape of the in vivo insulin-glucose disposal dose-response curves in 7 control and 13 obese human subjects. Each subject had at least three euglycemic studies performed at insulin infusion rates of 15, 40, 120, 240, or 1,200 mU/M2/min. The glucose disposal rate was decreased in all obese subjects compared with controls (101 +/- 16 vs. 186 +/- 16 mg/M2/min) during the 40 mU/M2/min insulin infusion. The mean dose-response curve for the obese subjects was displaced to the right, i.e., the half-maximally effective insulin concentration was 270 +/- 27 microU/ml for the obese compared with 130 +/- 10 microU/ml for controls. In nine of the obese subjects, the dose-response curves were shifted to the right, and maximal glucose disposal rates (at a maximally effective insulin concentration) were markedly decreased, indicating both a receptor and a postreceptor defect. On the other hand, four obese patients had right-shifted dose-response curves but reached normal maximal glucose disposal rates, consistent with decreased insulin receptors as the only abnormality. When the individual data were analyzed, it was found that the lease hyperinsulinemic, least insulin-resistant patients displayed only the receptor defect, whereas those with the greatest hyperinsulinemia exhibited the largest post-receptor defect, suggesting a continuous spectrum of defects as one advances from mild to severe insulin resistance. When insulin's ability to suppress hepatic glucose output was assessed, hyperinsulinemia produced total suppresssion in all subjects. The dose-response curve for the obese subjects was shifted to the right, indicating a defect in insulin receptors. Insulin binding to isolated adipocytes obtained from the obese subjects was decreased, and a highly significant inverse linear relationship was demonstrated between insulin

  3. Stress-impaired transcription factor expression and insulin secretion in transplanted human islets

    PubMed Central

    Dai, Chunhua; Kayton, Nora S.; Shostak, Alena; Poffenberger, Greg; Cyphert, Holly A.; Aramandla, Radhika; Thompson, Courtney; Papagiannis, Ioannis G.; Shiota, Masakazu; Stafford, John M.; Greiner, Dale L.; Herrera, Pedro L.; Shultz, Leonard D.; Stein, Roland; Powers, Alvin C.

    2016-01-01

    Type 2 diabetes is characterized by insulin resistance, hyperglycemia, and progressive β cell dysfunction. Excess glucose and lipid impair β cell function in islet cell lines, cultured rodent and human islets, and in vivo rodent models. Here, we examined the mechanistic consequences of glucotoxic and lipotoxic conditions on human islets in vivo and developed and/or used 3 complementary models that allowed comparison of the effects of hyperglycemic and/or insulin-resistant metabolic stress conditions on human and mouse islets, which responded quite differently to these challenges. Hyperglycemia and/or insulin resistance impaired insulin secretion only from human islets in vivo. In human grafts, chronic insulin resistance decreased antioxidant enzyme expression and increased superoxide and amyloid formation. In human islet grafts, expression of transcription factors NKX6.1 and MAFB was decreased by chronic insulin resistance, but only MAFB decreased under chronic hyperglycemia. Knockdown of NKX6.1 or MAFB expression in a human β cell line recapitulated the insulin secretion defect seen in vivo. Contrary to rodent islet studies, neither insulin resistance nor hyperglycemia led to human β cell proliferation or apoptosis. These results demonstrate profound differences in how excess glucose or lipid influence mouse and human insulin secretion and β cell activity and show that reduced expression of key islet-enriched transcription factors is an important mediator of glucotoxicity and lipotoxicity. PMID:27064285

  4. Insulin stimulates the biosynthesis of chiro-inositol-containing phospholipids in a rat fibroblast line expressing the human insulin receptor.

    PubMed Central

    Pak, Y; Paule, C R; Bao, Y D; Huang, L C; Larner, J

    1993-01-01

    HIRc-B cells (rat fibroblasts expressing the human insulin receptor) were incubated with myo-[3H]inositol for 48 hr, and the biosynthesis of chiro-[3H]inositol was investigated in the absence and presence of insulin following a time course up to 60 min. After phase separation, treatment with insulin for 15 min caused a 2.2-fold increase in the specific radioactivity of chiro-[3H]inositol-containing phospholipids in contrast to a 1.2-fold increase in the specific radioactivity of myo-[3H]inositol-containing phospholipids. No insulin-mediated change in the specific radioactivity was observed in the inositol phosphates or free inositols. Further detailed analysis of individual [3H]inositol-containing phospholipids demonstrated marked increases in specific activity of the chiro-[3H]inositol phospholipids after 15 min of incubation with insulin: phosphatidylinositol 4-phosphate and 4,5-bisphosphate, 4.2-fold; lysophosphatidylinositol, 1.5-fold; phosphatidylinositol, 3.2-fold. In contrast, myo-[3H]inositol-containing phospholipids demonstrated relatively small increases (1.1- to 1.4-fold) after 5 min of incubation with insulin. These findings indicate that insulin stimulates de novo synthesis of chiro-inositol-containing phospholipids at the inositol phospholipid level. Images Fig. 2 Fig. 3 PMID:8356081

  5. Effects of Insulin Detemir and NPH Insulin on Body Weight and Appetite-Regulating Brain Regions in Human Type 1 Diabetes: A Randomized Controlled Trial

    PubMed Central

    van Golen, Larissa W.; Veltman, Dick J.; IJzerman, Richard G.; Deijen, Jan Berend; Heijboer, Annemieke C.; Barkhof, Frederik; Drent, Madeleine L.; Diamant, Michaela

    2014-01-01

    Studies in rodents have demonstrated that insulin in the central nervous system induces satiety. In humans, these effects are less well established. Insulin detemir is a basal insulin analog that causes less weight gain than other basal insulin formulations, including the current standard intermediate-long acting Neutral Protamine Hagedorn (NPH) insulin. Due to its structural modifications, which render the molecule more lipophilic, it was proposed that insulin detemir enters the brain more readily than other insulins. The aim of this study was to investigate whether insulin detemir treatment differentially modifies brain activation in response to food stimuli as compared to NPH insulin. In addition, cerebral spinal fluid (CSF) insulin levels were measured after both treatments. Brain responses to viewing food and non-food pictures were measured using functional Magnetic Resonance Imaging in 32 type 1 diabetic patients, after each of two 12-week treatment periods with insulin detemir and NPH insulin, respectively, both combined with prandial insulin aspart. CSF insulin levels were determined in a subgroup. Insulin detemir decreased body weight by 0.8 kg and NPH insulin increased weight by 0.5 kg (p = 0.02 for difference), while both treatments resulted in similar glycemic control. After treatment with insulin detemir, as compared to NPH insulin, brain activation was significantly lower in bilateral insula in response to visual food stimuli, compared to NPH (p = 0.02 for right and p = 0.05 for left insula). Also, CSF insulin levels were higher compared to those with NPH insulin treatment (p = 0.003). Our findings support the hypothesis that in type 1 diabetic patients, the weight sparing effect of insulin detemir may be mediated by its enhanced action on the central nervous system, resulting in blunted activation in bilateral insula, an appetite-regulating brain region, in response to food stimuli. Trial Registration ClinicalTrials.gov NCT00626080

  6. [Insulin resistance as a mechanism of adaptation during human evolution].

    PubMed

    Ricart, W; Fernández-Real, J M

    2010-10-01

    The recent application of concepts of evolution to human disease is proving useful to understand certain pathophysiological mechanisms of different entities that span genomic alterations of immunity, respiratory and hormone function, and the circulatory and neural systems. However, effort has concentrated on explaining the keys to adaptation that define human metabolism and, since the early 1960s, several theories have been developed. This article reviews some of the hypotheses postulated in recent years on the potential benefit of insulin resistance and discusses the most recent knowledge. The concept of the thrifty gene seems to have been definitively refuted by current knowledge. The current paradigm describes an interaction between the metabolic and the immune systems resulting from their coevolution, promoted by evolutionary pressures triggered by fasting, infection and intake of different foods. The activation and regulation of these ancient mechanisms in integrated and interdependent areas defines insulin resistance as a survival strategy that is critical during fasting and in the fight against infection. The relationship with some components of the diet and, particularly, with the symbiotic intestinal microflora points to new paradigms in understanding the pathophysiology of obesity, metabolic syndrome and type 2 diabetes mellitus.

  7. Intranasal insulin suppresses endogenous glucose production in humans compared with placebo in the presence of similar venous insulin concentrations.

    PubMed

    Dash, Satya; Xiao, Changting; Morgantini, Cecilia; Koulajian, Khajag; Lewis, Gary F

    2015-03-01

    Intranasal insulin (INI) has been shown to modulate food intake and food-related activity in the central nervous system in humans. Because INI increases insulin concentration in the cerebrospinal fluid, these effects have been postulated to be mediated via insulin action in the brain, although peripheral effects of insulin cannot be excluded. INI has been shown to lower plasma glucose in some studies, but whether it regulates endogenous glucose production (EGP) is not known. To assess the role of INI in the regulation of EGP, eight healthy men were studied in a single-blind, crossover study with two randomized visits (one with 40 IU INI and the other with intranasal placebo [INP] administration) 4 weeks apart. EGP was assessed under conditions of an arterial pancreatic clamp, with a primed, constant infusion of deuterated glucose and infusion of 20% dextrose as required to maintain euglycemia. Between 180 and 360 min after administration, INI significantly suppressed EGP by 35.6% compared with INP, despite similar venous insulin concentrations. In conclusion, INI lowers EGP in humans compared with INP, despite similar venous insulin concentrations. INI may therefore be of value in treating excess liver glucose production in diabetes.

  8. Palmitate induces insulin resistance in human HepG2 hepatocytes by enhancing ubiquitination and proteasomal degradation of key insulin signaling molecules.

    PubMed

    Ishii, Megumi; Maeda, Ayumi; Tani, Shuji; Akagawa, Mitsugu

    2015-01-15

    Obesity-associated insulin resistance is a major pathogenesis of type 2 diabetes mellitus and is characterized by defects in insulin signaling. High concentrations of plasma free fatty acids (FFAs) are involved in the etiology of obesity-associated insulin resistance. However, the detailed mechanism by which FFAs contribute to the development of insulin resistance is not yet fully understood. We investigated the molecular basis of insulin resistance elicited by FFAs using the human hepatocyte cell line HepG2. Among major human FFAs, palmitate markedly inhibited insulin-stimulated phosphorylation of key insulin signaling molecules such as insulin receptor, insulin receptor substrate-1, and Akt, indicating that palmitate is the principal inducer of insulin resistance. We revealed that palmitate facilitates ubiquitination of the key insulin signaling molecules, and subsequently elicits their proteasomal degradation. Furthermore, we demonstrated that inhibition of ubiquitination by the ubiquitin-activating enzyme E1 inhibitor PYR41 significantly prevents palmitate-inducible insulin resistance but not by the proteasome inhibitor MG132, implying that ubiquitinated signaling molecules may be dysfunctional. In conclusion, inhibition of ubiquitination of the key insulin signaling molecules may be a potential strategy for preventing and treating obesity-associated insulin resistance.

  9. Insulin concentration is critical in culturing human neural stem cells and neurons

    PubMed Central

    Rhee, Y-H; Choi, M; Lee, H-S; Park, C-H; Kim, S-M; Yi, S-H; Oh, S-M; Cha, H-J; Chang, M-Y; Lee, S-H

    2013-01-01

    Cell culture of human-derived neural stem cells (NSCs) is a useful tool that contributes to our understanding of human brain development and allows for the development of therapies for intractable human brain disorders. Human NSC (hNSC) cultures, however, are not commonly used, mainly because of difficulty with consistently maintaining the cells in a healthy state. In this study, we show that hNSC cultures, unlike NSCs of rodent origins, are extremely sensitive to insulin, an indispensable culture supplement, and that the previously reported difficulty in culturing hNSCs is likely because of a lack of understanding of this relationship. Like other neural cell cultures, insulin is required for hNSC growth, as withdrawal of insulin supplementation results in massive cell death and delayed cell growth. However, severe apoptotic cell death was also detected in insulin concentrations optimized to rodent NSC cultures. Thus, healthy hNSC cultures were only produced in a narrow range of relatively low insulin concentrations. Insulin-mediated cell death manifested not only in all human NSCs tested, regardless of origin, but also in differentiated human neurons. The underlying cell death mechanism at high insulin concentrations was similar to insulin resistance, where cells became less responsive to insulin, resulting in a reduction in the activation of the PI3K/Akt pathway critical to cell survival signaling. PMID:23928705

  10. Insulin as an Autoantigen in NOD/Human Diabetes

    PubMed Central

    Zhang, Li; Nakayama, Maki; Eisenbarth, George S.

    2008-01-01

    Though multiple islet autoantigens are recognized by T lymphocytes and autoantibodies prior to the development of type 1A (immune mediated diabetes) there is increasing evidence that autoimmunity to insulin may be central to disease pathogenesis. Evidence is strongest for the NOD mouse model where blocking immune responses to insulin prevents diabetes and insulin peptides can be utilized to induce diabetes. In man insulin gene polymorphisms are associated with disease risk, and autoantibodies and T cells reacting with multiple insulin/proinsulin epitopes are present. It is not currently clear why insulin autoimmunity is so prominent and frequent and though insulin can be used to immunologically prevent diabetes of NOD mice, insulin based preventive immunoregulation of diabetes in man is not yet possible. PMID:18178393

  11. Specificity of insulin signalling in human skeletal muscle as revealed by small interfering RNA.

    PubMed

    Krook, A; Zierath, J R

    2009-07-01

    Insulin action on metabolically active tissues is a complex process involving positive and negative feedback regulation to control whole body glucose homeostasis. At the cellular level, glucose and lipid metabolism, as well as protein synthesis, are controlled through canonical insulin signalling cascades. The discovery of small interfering RNA (siRNA) allows for the molecular dissection of critical components of the regulation of metabolic and gene regulatory events in insulin-sensitive tissues. The application of siRNA to tissues of human origin allows for the molecular dissection of the mechanism(s) regulating glucose and lipid metabolism. Penetration of the pathways controlling insulin action in human tissue may aid in discovery efforts to develop diabetes prevention and treatment strategies. This review will focus on the use of siRNA to validate critical regulators controlling insulin action in human skeletal muscle, a key organ important for the control of whole body insulin-mediated glucose uptake and metabolism.

  12. Glucocorticoids fail to cause insulin resistance in human subcutaneous adipose tissue in vivo.

    PubMed

    Hazlehurst, Jonathan M; Gathercole, Laura L; Nasiri, Maryam; Armstrong, Matthew J; Borrows, Sarah; Yu, Jinglei; Wagenmakers, Anton J M; Stewart, Paul M; Tomlinson, Jeremy W

    2013-04-01

    It is widely believed that glucocorticoids cause insulin resistance in all tissues. We have previously demonstrated that glucocorticoids cause insulin sensitization in human adipose tissue in vitro and induce insulin resistance in skeletal muscle. Our aim was to determine whether glucocorticoids have tissue-specific effects on insulin sensitivity in vivo. Fifteen healthy volunteers were recruited into a double-blind, randomized, placebo-controlled, crossover study, receiving both an overnight hydrocortisone and saline infusion. The tissue-specific actions of insulin were determined using paired 2-step hyperinsulinemic euglycemic clamps incorporating stable isotopes with concomitant adipose tissue microdialysis. The study was performed in the Wellcome Trust Clinical Research Facility, Queen Elizabeth Hospital, Birmingham, United Kingdom. The sensitivity of sc adipose tissue to insulin action was measured. Hydrocortisone induced systemic insulin resistance but failed to cause sc adipose tissue insulin resistance as measured by suppression of adipose tissue lipolysis and enhanced insulin-stimulated pyruvate generation. In primary cultures of human hepatocytes, glucocorticoids increased insulin-stimulated p-ser473akt/protein kinase B. Similarly, glucocorticoids enhanced insulin-stimulated p-ser473akt/protein kinase B and increased Insulin receptor substrate 2 mRNA expression in sc, but not omental, intact human adipocytes, suggesting a depot-specificity of action. This study represents the first description of sc adipose insulin sensitization by glucocorticoids in vivo and demonstrates tissue-specific actions of glucocorticoids to modify insulin action. It defines an important advance in our understanding of the actions of both endogenous and exogenous glucocorticoids and may have implications for the development and targeting of future glucocorticoid therapies.

  13. Myotubes derived from human-induced pluripotent stem cells mirror in vivo insulin resistance.

    PubMed

    Iovino, Salvatore; Burkart, Alison M; Warren, Laura; Patti, Mary Elizabeth; Kahn, C Ronald

    2016-02-16

    Induced pluripotent stem cells (iPS cells) represent a unique tool for the study of the pathophysiology of human disease, because these cells can be differentiated into multiple cell types in vitro and used to generate patient- and tissue-specific disease models. Given the critical role for skeletal muscle insulin resistance in whole-body glucose metabolism and type 2 diabetes, we have created a novel cellular model of human muscle insulin resistance by differentiating iPS cells from individuals with mutations in the insulin receptor (IR-Mut) into functional myotubes and characterizing their response to insulin in comparison with controls. Morphologically, IR-Mut cells differentiated normally, but had delayed expression of some muscle differentiation-related genes. Most importantly, whereas control iPS-derived myotubes exhibited in vitro responses similar to primary differentiated human myoblasts, IR-Mut myotubes demonstrated severe impairment in insulin signaling and insulin-stimulated 2-deoxyglucose uptake and glycogen synthesis. Transcriptional regulation was also perturbed in IR-Mut myotubes with reduced insulin-stimulated expression of metabolic and early growth response genes. Thus, iPS-derived myotubes from individuals with genetically determined insulin resistance demonstrate many of the defects observed in vivo in insulin-resistant skeletal muscle and provide a new model to analyze the molecular impact of muscle insulin resistance.

  14. Pharmacokinetics of intravenous insulin delivery in humans with type 1 diabetes.

    PubMed

    Hipszer, Brian; Joseph, Jeffrey; Kam, Moshe

    2005-02-01

    Insulin pharmacokinetics models describe the distribution and elimination of insulin in the body. These models can be useful in designing infusion schemes to produce a desired plasma insulin profile. We evaluated the pharmacokinetics of intravenous insulin delivery in five human subjects with type 1 diabetes; one subject was studied on three separate occasions for a total of seven experiments. Each subject consumed an identical 829 Kcal meal of solid food for breakfast and lunch, followed by exercise on a stationary bicycle. Regular human insulin was infused into a peripheral vein at a basal rate (0.5 U/h) for the entire study. Coinciding with the consumption of each meal, insulin was infused at a higher rate for 120 min (average dose 8.5 +/- 2.1 U). The bolus dose was based upon preprandial and 60-min postprandial blood glucose measurements and a sliding scale regimen. Blood glucose levels were allowed to fluctuate throughout the protocol (mean 174 mg/dL, range 55-340 mg/dL). Human insulin levels were measured from plasma samples obtained every 10 min throughout the 8.5-h protocol. A total of 346 plasma samples were assayed to measure the concentration of human insulin. Data were used to compare (previously developed) insulin kinetics models consisting of one, two, and three first-order linear differential equations. The ability of each model to simulate the input/output data (intravenous insulin infusion rate/plasma insulin concentration) was assessed. Our main finding is that the first-order linear insulin kinetics model was sufficient to describe the clinical data. The model had a fractional insulin loss rate of 0.112 +/- 0.063 min(1) and a distribution volume of 15.6 +/- 4.0 L.

  15. Determination of insulin in humans with insulin-dependent diabetes mellitus patients by HPLC with diode array detection.

    PubMed

    Yilmaz, Bilal; Kadioglu, Yucel; Capoglu, Ilyas

    2012-08-01

    A simple and reliable high-performance liquid chromatographic method with diode array detection has been developed and validated for the determination of insulin in human plasma. A good chromatographic separation was achieved on a C18 column with a mobile phase consisting of acetonitrile and 0.2M sodium sulfate (pH 2.4), 25:75 (v/v). Its flow rate was 1.2 mL/min. Calibration curve was linear within the concentration range of 0.15-25 µg/mL. Intra-day and inter-day relative standard deviations for insulin in human plasma were less than 6.3 and 8.5%, respectively. The limits of detection and quantification of insulin were 0.10 and 0.15 µg/mL, respectively. Also, this assay was applied to determine the pharmacokinetic parameters of insulin in eight insulin-dependent diabetes mellitus patients after subcutaneous injection of 25 IU of Actrapid HM.

  16. [Immunoenzyme method of determining trace amounts of proinsulin in recombinant human insulin].

    PubMed

    Britsyna, N S; Prokop'ev, A A; Kulikov, S V; Samartsev, M A

    1994-01-01

    An enzyme immunoassay (ELISA) for the detection of human proinsulin has been developed based on the interaction of the absorbed proinsulin with the antiserum against the synthetic proinsulin C-peptide. In the presence of high concentrations of insulin, the sensitivity of the assay slightly decreases due to the competitive adsorption of insulin onto the polystyrene carrier with the binding constant 800-1000 times less than that of proinsulin. A method is proposed for the interpretation of ELISA data based on analysis of a weighed dry insulin sample, which enables the detection of a 0.02-0.1% admixture of proinsulin in the chromatographically purified recombinant human insulin.

  17. Protein crystal growth in microgravity review of large scale temperature induction method: bovine insulin, human insulin and human alpha interferon

    NASA Astrophysics Data System (ADS)

    Long, Marianna M.; Bishop, John Bradford; Nagabhushan, Tattanahalli L.; Reichert, Paul; Smith, G. David; DeLucas, Lawrence J.

    1996-10-01

    The protein crystal growth facility (PCF) is space-flight hardware that accommodates large scale protein crystal growth experiments using temperature change as the inductive step. Recent modifications include specialized instrumentation for monitoring crystal nucleation with laser light scattering. This paper reviews results from the PCF's first seven flights on the Space Shuttle, the last with laser light scattering instrumentation. The PCF's objective is twofold: (1) production of high quality protein crystals for X-ray analysis and subsequent structure based drug design and (2) preparation of a large quantity of relatively contaminant free crystals for use as time-release protein pharmaceuticals. The first three Shuttle flights with bovine insulin constituted the PCF's proof of concept, demonstrating that the space-grown crystals were larger and diffracted to higher resolution than their earth-grown counterparts. The later four PCF missions were used to grow recombinant human insulin crystals for X-ray analysis and to continue productions trials aimed at the development of a processing facility for crystalline recombinant alpha interferon.

  18. Effects of physiological variations in circulating insulin levels on bone turnover in humans.

    PubMed

    Basu, Rita; Peterson, James; Rizza, Robert; Khosla, Sundeep

    2011-05-01

    Recent studies in mice have demonstrated that insulin signaling in osteoblasts stimulates bone formation and reduces osteoprotegerin production; the latter results in an increase in bone resorption, which then leads to the release of undercarboxylated osteocalcin from bone. Undercarboxylated osteocalcin, in turn, enhances insulin sensitivity. The objective of the study was to test whether physiological changes in insulin levels regulate bone metabolism in humans. This investigation was an analysis of samples from a prospective study. The study was conducted at a clinical research unit. Fourteen subjects underwent a 7-h stepped insulin infusion accompanied by a glucose clamp and somatostatin infusion along with replacement infusions of GH and glucagon, thus isolating possible effects of insulin on bone. Insulin was infused at rates achieving low (∼150 pmol/liter), intermediate (∼350 pmol/liter), or high (∼700 pmol/liter) plasma insulin levels. Bone turnover markers, undercarboxylated osteocalcin, and osteoprotegerin levels at the end of the low, intermediate, and high dose insulin infusions were measured. Values for the outcome measures at the end of the intermediate- and high-dose insulin infusions were no different from values at the end of the low-dose insulin infusion. However, measures of insulin sensitivity (glucose infusion and disappearance rates) correlated positively with C-terminal telopeptide of type I collagen levels. Acute changes in insulin levels, as occur during meals, do not regulate bone turnover, undercarboxylated osteocalcin, or osteoprotegerin levels. However, the correlation of measures of insulin sensitivity with bone resorption suggests the need for further studies in humans on the possible regulation of bone metabolism by insulin.

  19. A functional circadian clock is required for proper insulin secretion by human pancreatic islet cells.

    PubMed

    Saini, C; Petrenko, V; Pulimeno, P; Giovannoni, L; Berney, T; Hebrok, M; Howald, C; Dermitzakis, E T; Dibner, C

    2016-04-01

    To determine the impact of a functional human islet clock on insulin secretion and gene transcription. Efficient circadian clock disruption was achieved in human pancreatic islet cells by small interfering RNA-mediated knockdown of CLOCK. Human islet secretory function was assessed in the presence or absence of a functional circadian clock by stimulated insulin secretion assays, and by continuous around-the-clock monitoring of basal insulin secretion. Large-scale transcription analysis was accomplished by RNA sequencing, followed by quantitative RT-PCR analysis of selected targets. Circadian clock disruption resulted in a significant decrease in both acute and chronic glucose-stimulated insulin secretion. Moreover, basal insulin secretion by human islet cells synchronized in vitro exhibited a circadian pattern, which was perturbed upon clock disruption. RNA sequencing analysis suggested alterations in 352 transcript levels upon circadian clock disruption. Among them, key regulators of the insulin secretion pathway (GNAQ, ATP1A1, ATP5G2, KCNJ11) and transcripts required for granule maturation and release (VAMP3, STX6, SLC30A8) were affected. Using our newly developed experimental approach for efficient clock disruption in human pancreatic islet cells, we show for the first time that a functional β-cell clock is required for proper basal and stimulated insulin secretion. Moreover, clock disruption has a profound impact on the human islet transcriptome, in particular, on the genes involved in insulin secretion. © 2015 John Wiley & Sons Ltd.

  20. Insulin binding properties of normal and transformed human epidermal cultured keratinocytes

    SciTech Connect

    Verrando, P.; Ortonne, J.P.

    1985-10-01

    Insulin binding to its receptors was studied in cultured normal and transformed (A431 line) human epidermal keratinocytes. The specific binding was a temperature-dependent, saturable process. Normal keratinocytes possess a mean value of about 80,000 receptors per cell. Fifteen hours exposure of the cells to insulin lowered their receptor number (about 65% loss in available sites); these reappeared when the hormone was removed from the culture medium. In the A431 epidermoid carcinoma cell line, there is a net decrease in insulin binding (84% of the initial bound/free hormone ratio in comparison with normal cells) essentially related to a loss in receptor affinity for insulin. Thus, cultured human keratinocytes which express insulin receptors may be a useful tool in understanding skin pathology related to insulin disorders.

  1. Insulin in human milk and the prevention of type 1 diabetes.

    PubMed

    Shehadeh, N; Shamir, R; Berant, M; Etzioni, A

    2001-12-01

    Although controversial, exclusive breast milk feeding was shown to exert a protective effect in preventing type 1 diabetes. In contrast, an early introduction of cow's milk-based formula in young infants may enhance the risk of disease, especially in genetically susceptible children, presumably by an increase of intestinal permeability to macromolecules such as bovine serum albumin and beta-casein, which may arouse autoimmunity. We have shown that human milk contains insulin in substantial concentrations, while insulin is barely detectable (if at all) in infant formulas. Orally administered insulin was demonstrated to promote gut maturation and to reduce intestinal permeability to macromolecules. Furthermore, oral insulin may induce tolerance to insulin and protect against the development of type 1 diabetes. We herewith raise a hypothesis that human milk is protective against the development of type 1 diabetes by virtue of the effects of its substantial content of insulin.

  2. Comparison of the effects of recombinant human insulin-like growth factor-I and insulin on glucose and leucine kinetics in humans.

    PubMed Central

    Laager, R; Ninnis, R; Keller, U

    1993-01-01

    To compare the metabolic effects of elevated plasma concentrations of IGF-I and insulin, overnight-fasted normal subjects were studied twice, once receiving IGF-I and once insulin at doses that resulted in identical increases in glucose uptake during 8-h euglycemic clamping. Recombinant human IGF-I or insulin were infused in one group at high doses (30 micrograms/kg per h IGF-I or 0.23 nmol/kg per h insulin) and in another group at low doses (5 micrograms/kg per h IGF-I or 0.04 nmol/kg per h insulin). Glucose rate of disappearance (measured by [6,6-D2]-glucose infusions) increased from baseline by 239 +/- 16% during high dose IGF-I vs 197 +/- 18% during insulin (P = 0.021 vs IGF-I). Hepatic glucose production decreased by 37 +/- 6% during high dose IGF-I vs 89 +/- 13% during insulin (P = 0.0028 vs IGF-I). IGF-I suppressed whole body leucine flux ([1-13C]-leucine infusion technique) more than insulin (42 +/- 4 vs 32 +/- 3% during high doses, P = 0.0082). Leucine oxidation rate decreased during high dose IGF-I more than during insulin (55 +/- 4 vs 32 +/- 6%, P = 0.0001). The decreases of plasma concentrations of free fatty acids, acetoacetate, and beta-hydroxybutyrate after 8 h of IGF-I and insulin administration were similar. Plasma C-peptide levels decreased by 57 +/- 4% during high doses of IGF-I vs 36 +/- 6% during insulin (P = 0.005 vs IGF-I). The present data demonstrate that, compared to insulin, an acute increase in plasma IGF-I levels results in preferential enhancement of peripheral glucose utilization, diminished suppression of hepatic glucose production, augmented decrease of whole body protein breakdown (leucine flux), and of irreversible leucine catabolism but in similar antilipolytic effects. The data suggest that insulin-like effects of IGF-I in humans are mediated in part via IGF-I receptors and in part via insulin receptors. PMID:8408642

  3. On the suppression of plasma nonesterified fatty acids by insulin during enhanced intravascular lipolysis in humans.

    PubMed

    Carpentier, André C; Frisch, Frédérique; Cyr, Denis; Généreux, Philippe; Patterson, Bruce W; Giguère, Robert; Baillargeon, Jean-Patrice

    2005-11-01

    During the fasting state, insulin reduces nonesterified fatty acid (NEFA) appearance in the systemic circulation mostly by suppressing intracellular lipolysis in the adipose tissue. In the postprandial state, insulin may also control NEFA appearance through enhanced trapping into the adipose tissue of NEFA derived from intravascular triglyceride lipolysis. To determine the contribution of suppression of intracellular lipolysis in the modulation of plasma NEFA metabolism by insulin during enhanced intravascular triglyceride lipolysis, 10 healthy nonobese subjects underwent pancreatic clamps at fasting vs. high physiological insulin level with intravenous infusion of heparin plus Intralipid. Nicotinic acid was administered orally during the last 2 h of each 4-h clamp to inhibit intracellular lipolysis and assess insulin's effect on plasma NEFA metabolism independently of its effect on intracellular lipolysis. Stable isotope tracers of palmitate, acetate, and glycerol were used to assess plasma NEFA metabolism and total triglyceride lipolysis in each participant. The glycerol appearance rate was similar during fasting vs. high insulin level, but plasma NEFA levels were significantly lowered by insulin. Nicotinic acid significantly blunted the insulin-mediated suppression of plasma palmitate appearance and oxidation rates by approximately 60 and approximately 70%, respectively. In contrast, nicotinic acid did not affect the marked stimulation of palmitate clearance by insulin. Thus most of the insulin-mediated reduction of plasma NEFA appearance and oxidation can be explained by suppression of intracellular lipolysis during enhanced intravascular triglyceride lipolysis in healthy humans. Our results also suggest that insulin may affect plasma NEFA clearance independently of the suppression of intracellular lipolysis.

  4. Forkhead box O-1 modulation improves endothelial insulin resistance in human obesity.

    PubMed

    Karki, Shakun; Farb, Melissa G; Ngo, Doan T M; Myers, Samantha; Puri, Vishwajeet; Hamburg, Naomi M; Carmine, Brian; Hess, Donald T; Gokce, Noyan

    2015-06-01

    Increased visceral adiposity has been closely linked to insulin resistance, endothelial dysfunction, and cardiometabolic disease in obesity, but pathophysiological mechanisms are poorly understood. We sought to investigate mechanisms of vascular insulin resistance by characterizing depot-specific insulin responses and gain evidence that altered functionality of transcription factor forkhead box O-1 (FOXO-1) may play an important role in obesity-related endothelial dysfunction. We intraoperatively collected paired subcutaneous and visceral adipose tissue samples from 56 severely obese (body mass index, 43 ± 7 kg/m(2)) and 14 nonobese subjects during planned surgical operations, and characterized depot-specific insulin-mediated responses using Western blot and quantitative immunofluorescence techniques. Insulin signaling via phosphorylation of FOXO-1 and consequent endothelial nitric oxide synthase stimulation was selectively impaired in the visceral compared with subcutaneous adipose tissue and endothelial cells of obese subjects. In contrast, tissue actions of insulin were preserved in nonobese individuals. Pharmacological antagonism with AS1842856 and biological silencing using small interfering RNA-mediated FOXO-1 knockdown reversed insulin resistance and restored endothelial nitric oxide synthase activation in the obese. We observed profound endothelial insulin resistance in the visceral adipose tissue of obese humans which improved with FOXO-1 inhibition. FOXO-1 modulation may represent a novel therapeutic target to diminish vascular insulin resistance. In addition, characterization of endothelial insulin resistance in the adipose microenvironment may provide clues to mechanisms of systemic disease in human obesity. © 2015 American Heart Association, Inc.

  5. Insulin Acutely Inhibits Intestinal Lipoprotein Secretion in Humans in Part by Suppressing Plasma Free Fatty Acids

    PubMed Central

    Pavlic, Mirjana; Xiao, Changting; Szeto, Linda; Patterson, Bruce W.; Lewis, Gary F.

    2010-01-01

    OBJECTIVE Intestinal lipoprotein production has recently been shown to be increased in insulin resistance, but it is not known whether it is regulated by insulin in humans. Here, we investigated the effect of acute hyperinsulinemia on intestinal (and hepatic) lipoprotein production in six healthy men in the presence and absence of concomitant suppression of plasma free fatty acids (FFAs). RESEARCH DESIGN AND METHODS Each subject underwent the following three lipoprotein turnover studies, in random order, 4–6 weeks apart: 1) insulin and glucose infusion (euglycemic-hyperinsulinemic clamp) to induce hyperinsulinemia, 2) insulin and glucose infusion plus Intralipid and heparin infusion to prevent the insulin-induced suppression of plasma FFAs, and 3) saline control. RESULTS VLDL1 and VLDL2-apoB48 and -apoB100 production rates were suppressed by 47–62% by insulin, with no change in clearance. When the decline in FFAs was prevented by concomitant infusion of Intralipid and heparin, the production rates of VLDL1 and VLDL2-apoB48 and -apoB100 were intermediate between insulin and glucose infusion and saline control. CONCLUSIONS This is the first demonstration in humans that intestinal apoB48-containing lipoprotein production is acutely suppressed by insulin, which may involve insulin's direct effects and insulin-mediated suppression of circulating FFAs. PMID:20028946

  6. High-mix insulins

    PubMed Central

    Kalra, Sanjay; Farooqi, Mohammad Hamed; El-Houni, Ali E.

    2015-01-01

    Premix insulins are commonly used insulin preparations, which are available in varying ratios of different molecules. These drugs contain one short- or rapid-acting, and one intermediate- or long-acting insulin. High-mix insulins are mixtures of insulins that contain 50% or more than 50% of short-acting insulin. This review describes the clinical pharmacology of high-mix insulins, including data from randomized controlled trials. It suggests various ways, in which high-mix insulin can be used, including once daily, twice daily, thrice daily, hetero-mix, and reverse regimes. The authors provide a rational framework to help diabetes care professionals, identify indications for pragmatic high-mix use. PMID:26425485

  7. Structure, Aggregation, and Activity of a Covalent Insulin Dimer Formed During Storage of Neutral Formulation of Human Insulin.

    PubMed

    Hjorth, Christian Fogt; Norrman, Mathias; Wahlund, Per-Olof; Benie, Andrew J; Petersen, Bent O; Jessen, Christian M; Pedersen, Thomas Å; Vestergaard, Kirsten; Steensgaard, Dorte B; Pedersen, Jan Skov; Naver, Helle; Hubálek, František; Poulsen, Christian; Otzen, Daniel

    2016-04-01

    A specific covalently linked dimeric species of insulin high molecular weight products (HMWPs), formed during prolonged incubation of a neutral pharmaceutical formulation of human insulin, were characterized in terms of tertiary structure, self-association, biological activity, and fibrillation properties. The dimer was formed by a covalent link between A21Asn and B29Lys. It was analyzed using static and dynamic light scattering and small-angle X-ray scattering to evaluate its self-association behavior. The tertiary structure was obtained using nuclear magnetic resonance and X-ray crystallography. The biological activity of HMWP was determined using 2 in vitro assays, and its influence on fibrillation was investigated using Thioflavin T assays. The dimer's tertiary structure was nearly identical to that of the noncovalent insulin dimer, and it was able to form hexamers in the presence of zinc. The dimer exhibited reduced propensity for self-association in the absence of zinc but significantly postponed the onset of fibrillation in insulin formulations. Consistent with its dimeric state, the tested species of HMWP showed little to no biological activity in the used assays. This study is the first detailed characterization of a specific type of human insulin HMWP formed during storage of a marketed pharmaceutical formulation. These results indicate that this specific type of HMWP is unlikely to antagonize the physical stability of the formulation, as HMWP retained a tertiary structure similar to the noncovalent dimer and participated in hexamer assembly in the presence of zinc. In addition, increasing amounts of HMWP reduce the rate of insulin fibrillation.

  8. Bariatric Surgery in Morbidly Obese Insulin Resistant Humans Normalises Insulin Signalling but Not Insulin-Stimulated Glucose Disposal

    PubMed Central

    de Berker, David A. R.; May, Margaret T.; Hers, Ingeborg; Dayan, Colin M.; Andrews, Robert C.; Tavaré, Jeremy M.

    2015-01-01

    Aims Weight-loss after bariatric surgery improves insulin sensitivity, but the underlying molecular mechanism is not clear. To ascertain the effect of bariatric surgery on insulin signalling, we examined glucose disposal and Akt activation in morbidly obese volunteers before and after Roux-en-Y gastric bypass surgery (RYGB), and compared this to lean volunteers. Materials and Methods The hyperinsulinaemic euglycaemic clamp, at five infusion rates, was used to determine glucose disposal rates (GDR) in eight morbidly obese (body mass index, BMI=47.3±2.2 kg/m2) patients, before and after RYGB, and in eight lean volunteers (BMI=20.7±0.7 kg/m2). Biopsies of brachioradialis muscle, taken at fasting and insulin concentrations that induced half-maximal (GDR50) and maximal (GDR100) GDR in each subject, were used to examine the phosphorylation of Akt-Thr308, Akt-473, and pras40, in vivo biomarkers for Akt activity. Results Pre-operatively, insulin-stimulated GDR was lower in the obese compared to the lean individuals (P<0.001). Weight-loss of 29.9±4 kg after surgery significantly improved GDR50 (P=0.004) but not GDR100 (P=0.3). These subjects still remained significantly more insulin resistant than the lean individuals (p<0.001). Weight loss increased insulin-stimulated skeletal muscle Akt-Thr308 and Akt-Ser473 phosphorylation, P=0.02 and P=0.03 respectively (MANCOVA), and Akt activity towards the substrate PRAS40 (P=0.003, MANCOVA), and in contrast to GDR, were fully normalised after the surgery (obese vs lean, P=0.6, P=0.35, P=0.46, respectively). Conclusions Our data show that although Akt activity substantially improved after surgery, it did not lead to a full restoration of insulin-stimulated glucose disposal. This suggests that a major defect downstream of, or parallel to, Akt signalling remains after significant weight-loss. PMID:25876175

  9. Human milk insulin is related to maternal plasma insulin and BMI: but other components of human milk do not differ by BMI.

    PubMed

    Young, B E; Patinkin, Z; Palmer, C; de la Houssaye, B; Barbour, L A; Hernandez, T; Friedman, J E; Krebs, N F

    2017-09-01

    The impact of maternal BMI and insulin sensitivity on bioactive components of human milk (HM) is not well understood. As the prevalence of obesity and diabetes rises, it is increasingly critical that we understand how maternal BMI and hormones associated with metabolic disease relate to concentrations of bioactive components in HM. This longitudinal cohort design followed 48 breastfeeding mothers through the first four months of lactation, collecting fasting morning HM samples at 2-weeks and 1, 2, 3 and 4-months, and fasting maternal blood at 2-weeks and 4-months. Insulin, glucose, adipokines leptin and adiponectin, appetite regulating hormone ghrelin, marker of oxidative stress 8OHdG and inflammatory cytokines (IL-6, IL-8, and TNF-a) were measured in HM and maternal plasma. A total of 26 normal weight (NW) (BMI=21.4±2.0 kg/m(2)) and 22 overweight/obese (OW/Ob) (BMI=30.4±4.2 kg/m(2)) were followed. Of all HM analytes measured, only insulin and leptin were different between groups - consistently higher in the OW/Ob group (leptin: P<0.001; insulin: P<0.03). HM insulin was 98% higher than maternal plasma insulin at 2-weeks and 32% higher at 4-months (P<0.001). Maternal fasting plasma insulin and HOMA-IR were positively related to HM insulin at 2-weeks (P<0.001, R(2)⩾0.38, n=31), and 4-months (P⩽0.005, R(2)⩾0.20, n=38). The concentrations of insulin in HM are higher than in maternal plasma and are related to maternal BMI and insulin sensitivity. With the exception of leptin, there were minimal other differences observed in HM composition across a wide range in maternal BMI.

  10. Vitamin E induces regular structure and stability of human insulin, more intense than vitamin D3.

    PubMed

    Soleymani, Hossein; Saboury, Ali A; Moosavi-Movahedi, Ali A; Rahmani, Fatemeh; Maleki, Javad; Yousefinejad, Saeid; Maghami, Parvaneh

    2016-12-01

    Changes in human environment and lifestyle over the last century have caused a dramatic increase in the occurrence of diabetes. Research of past decades illustrated that vitamin D and E have a key role in the improvement of diabetes by reducing oxidative stress, protein glycosylation, insulin resistance and also improving beta cell function. Binding properties and conformational changes of human insulin upon interaction with vitamins D3 and E (α-tocopherol) were investigated by spectroscopy, differential scanning calorimetry (DSC) and molecular dynamic simulation. Tyrosine fluorescence quenching studies indicates changes in the human insulin conformation in the presence of vitamins. Binding constants of vitamins D3 and E for human insulin were determined to be 2.7 and 1.5 (×10(-5)M(-1)) and the corresponding average numbers of binding sites were determined to be 1.3 and 1.2, respectively. Far- and near-UV circular dichroism studies showed that vitamin E can significantly change the secondary and tertiary structures of human insulin via an increase in the content of α-helix structure. Results of DSC showed that both vitamins D3 and E stabilize the structure of human insulin. Molecular dynamic simulation results indicated that vitamin D3 decreases the helical and strand structural contents of human insulin, but vitamin E stabilizes more regular secondary structures such as helical and strand structural contents as shown by experimental results.

  11. ADCY5 Couples Glucose to Insulin Secretion in Human Islets

    PubMed Central

    Mitchell, Ryan K.; Marselli, Lorella; Pullen, Timothy J.; Gimeno Brias, Silvia; Semplici, Francesca; Everett, Katy L.; Cooper, Dermot M.F.; Bugliani, Marco; Marchetti, Piero; Lavallard, Vanessa; Bosco, Domenico; Piemonti, Lorenzo; Johnson, Paul R.; Hughes, Stephen J.; Li, Daliang; Li, Wen-Hong; Shapiro, A.M. James

    2014-01-01

    Single nucleotide polymorphisms (SNPs) within the ADCY5 gene, encoding adenylate cyclase 5, are associated with elevated fasting glucose and increased type 2 diabetes (T2D) risk. Despite this, the mechanisms underlying the effects of these polymorphic variants at the level of pancreatic β-cells remain unclear. Here, we show firstly that ADCY5 mRNA expression in islets is lowered by the possession of risk alleles at rs11708067. Next, we demonstrate that ADCY5 is indispensable for coupling glucose, but not GLP-1, to insulin secretion in human islets. Assessed by in situ imaging of recombinant probes, ADCY5 silencing impaired glucose-induced cAMP increases and blocked glucose metabolism toward ATP at concentrations of the sugar >8 mmol/L. However, calcium transient generation and functional connectivity between individual human β-cells were sharply inhibited at all glucose concentrations tested, implying additional, metabolism-independent roles for ADCY5. In contrast, calcium rises were unaffected in ADCY5-depleted islets exposed to GLP-1. Alterations in β-cell ADCY5 expression and impaired glucose signaling thus provide a likely route through which ADCY5 gene polymorphisms influence fasting glucose levels and T2D risk, while exerting more minor effects on incretin action. PMID:24740569

  12. Premixed Prevaporized Combustor Technology Forum

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The Forum was held to present the results of recent and current work intended to provide basic information required for demonstration of lean, premixed prevaporized combustors for aircraft gas turbine engine application. Papers are presented which deal with the following major topics: (1) engine interfaces; (2) fuel-air preparation; (3) autoignition; (4) lean combustion; and (5) concept design studies.

  13. Statistics of premixed flame cells

    SciTech Connect

    Noever, D.A. )

    1991-07-15

    The statistics of random cellular patterns in premixed flames are analyzed. Agreement is found with a variety of topological relations previously found for other networks, namely, Lewis's law and Aboav's law. Despite the diverse underlying physics, flame cells are shown to share a broad class of geometric properties with other random networks---metal grains, soap foams, bioconvection, and Langmuir monolayers.

  14. Statistics of premixed flame cells

    NASA Technical Reports Server (NTRS)

    Noever, David A.

    1991-01-01

    The statistics of random cellular patterns in premixed flames are analyzed. Agreement is found with a variety of topological relations previously found for other networks, namely, Lewis's law and Aboav's law. Despite the diverse underlying physics, flame cells are shown to share a broad class of geometric properties with other random networks-metal grains, soap foams, bioconvection, and Langmuir monolayers.

  15. Statistics of premixed flame cells

    NASA Technical Reports Server (NTRS)

    Noever, David A.

    1991-01-01

    The statistics of random cellular patterns in premixed flames are analyzed. Agreement is found with a variety of topological relations previously found for other networks, namely, Lewis's law and Aboav's law. Despite the diverse underlying physics, flame cells are shown to share a broad class of geometric properties with other random networks-metal grains, soap foams, bioconvection, and Langmuir monolayers.

  16. Key Role for Ceramides in Mediating Insulin Resistance in Human Muscle Cells

    USDA-ARS?s Scientific Manuscript database

    Elevated non-esterified fatty acids, triglyceride, diacylglycerol and ceramide have all been associated with insulin resistance in muscle. We set out to investigate the role of intramyocellular lipid metabolites in the induction of insulin resistance in human primary myoblast cultures. Muscle cell...

  17. Preparative isolation by high performance liquid chromatography of human insulin B chain produced in escherichia coli

    SciTech Connect

    Cruz, N.; Antonio, S.; De Anda, R.; Gosset, G.; Bolivar, F. )

    1990-01-01

    This paper reports on a simple method developed for the analytical and preparative purification of human insulin B chain from recombinant origin. Three solvent systems: acetonitrile, isopropanol and methanol, were studied to determine their capacity to resolve the insulin B chain from a mixture of cyanogen bromide generated bacterial peptides. Using a {mu}Bondapak C18 column, it was possible to resolve the insulin B chain in all three systems. On a preparative scale, using a PrePak 500 C18 column with the isopropanol system, it was possible to purify insulin B chain and to obtain a 95% protein recovery.

  18. Pid1 induces insulin resistance in both human and mouse skeletal muscle during obesity.

    PubMed

    Bonala, Sabeera; McFarlane, Craig; Ang, Jackie; Lim, Radiance; Lee, Marcus; Chua, Hillary; Lokireddy, Sudarsanareddy; Sreekanth, Patnam; Leow, Melvin Khee Shing; Meng, Khoo Chin; Shyong, Tai E; Lee, Yung Seng; Gluckman, Peter D; Sharma, Mridula; Kambadur, Ravi

    2013-09-01

    Obesity is associated with insulin resistance and abnormal peripheral tissue glucose uptake. However, the mechanisms that interfere with insulin signaling and glucose uptake in human skeletal muscle during obesity are not fully characterized. Using microarray, we have identified that the expression of Pid1 gene, which encodes for a protein that contains a phosphotyrosine-interacting domain, is increased in myoblasts established from overweight insulin-resistant individuals. Molecular analysis further validated that both Pid1 mRNA and protein levels are increased in cell culture models of insulin resistance. Consistent with these results, overexpression of phosphotyrosine interaction domain-containing protein 1 (PID1) in human myoblasts resulted in reduced insulin signaling and glucose uptake, whereas knockdown of PID1 enhanced glucose uptake and insulin signaling in human myoblasts and improved the insulin sensitivity following palmitate-, TNF-α-, or myostatin-induced insulin resistance in human myoblasts. Furthermore, the number of mitochondria in myoblasts that ectopically express PID1 was significantly reduced. In addition to overweight humans, we find that Pid1 levels are also increased in all 3 peripheral tissues (liver, skeletal muscle, and adipose tissue) in mouse models of diet-induced obesity and insulin resistance. An in silico search for regulators of Pid1 expression revealed the presence of nuclear factor-κB (NF-κB) binding sites in the Pid1 promoter. Luciferase reporter assays and chromatin immunoprecipitation studies confirmed that NF-κB is sufficient to transcriptionally up-regulate the Pid1 promoter. Furthermore, we find that myostatin up-regulates Pid1 expression via an NF-κB signaling mechanism. Collectively these results indicate that Pid1 is a potent intracellular inhibitor of insulin signaling pathway during obesity in humans and mice.

  19. Retraction: Pid1 Induces Insulin Resistance in Both Human and Mouse Skeletal Muscle during Obesity

    PubMed Central

    Bonala, Sabeera; McFarlane, Craig; Ang, Jackie; Lim, Radiance; Lee, Marcus; Chua, Hillary; Lokireddy, Sudarsanareddy; Sreekanth, Patnam; Shing Leow, Melvin Khee; Meng, Khoo Chin; Shyong, TAI E; Lee, Yung Seng; Gluckman, Peter D.; Sharma, Mridula

    2013-01-01

    Obesity is associated with insulin resistance and abnormal peripheral tissue glucose uptake. However, the mechanisms that interfere with insulin signaling and glucose uptake in human skeletal muscle during obesity are not fully characterized. Using microarray, we have identified that the expression of Pid1 gene, which encodes for a protein that contains a phosphotyrosine-interacting domain, is increased in myoblasts established from overweight insulin-resistant individuals. Molecular analysis further validated that both Pid1 mRNA and protein levels are increased in cell culture models of insulin resistance. Consistent with these results, overexpression of phosphotyrosine interaction domain-containing protein 1 (PID1) in human myoblasts resulted in reduced insulin signaling and glucose uptake, whereas knockdown of PID1 enhanced glucose uptake and insulin signaling in human myoblasts and improved the insulin sensitivity following palmitate-, TNF-α-, or myostatin-induced insulin resistance in human myoblasts. Furthermore, the number of mitochondria in myoblasts that ectopically express PID1 was significantly reduced. In addition to overweight humans, we find that Pid1 levels are also increased in all 3 peripheral tissues (liver, skeletal muscle, and adipose tissue) in mouse models of diet-induced obesity and insulin resistance. An in silico search for regulators of Pid1 expression revealed the presence of nuclear factor-κB (NF-κB) binding sites in the Pid1 promoter. Luciferase reporter assays and chromatin immunoprecipitation studies confirmed that NF-κB is sufficient to transcriptionally up-regulate the Pid1 promoter. Furthermore, we find that myostatin up-regulates Pid1 expression via an NF-κB signaling mechanism. Collectively these results indicate that Pid1 is a potent intracellular inhibitor of insulin signaling pathway during obesity in humans and mice. PMID:23927930

  20. Cloning of a new member of the insulin gene superfamily (INSL4) expressed in human placenta

    SciTech Connect

    Chassin, D.; Laurent, A.; Janneau, J.L.

    1995-09-20

    A new member of the insulin gene superfamily was identified by screening a subtracted cDNA library of first-trimester human placenta and, hence, was tentatively named early placenta insulin-like peptide (EPIL). In this paper, we report the cloning and sequencing of the EPIL cDNA and the EPIL gene (INSL4). Comparison of the deduced amino acid sequence of the early placenta insulin-like peptide revealed significant overall and structural homologies with members of the insulin-like hormone superfamily. Moreover, the organization of the early placenta insulin-like gene, which is composed of two exons and one intron, is similiar to that of insulin and relaxin. By in situ hybridization, the INSL4 gene was assigned to band p24 of the short arm of chromosome 9. RT-PCR analysis of EPIL tissue distribution revealed that its transcripts are expressed in the placenta and uterus. 22 refs., 3 figs.

  1. The importance of the time interval between insulin injection and breakfast in determining postprandial glycaemic control--a comparison between human and porcine insulin.

    PubMed

    Patrick, A W; Collier, A; Matthews, D M; Macintyre, C C; Clarke, B F

    1988-01-01

    This study assessed the effect of the time interval between insulin injection and breakfast in determining subsequent postprandial glycaemic control and also whether this differed between highly purified porcine insulin and human insulin (crb) in six diabetic patients (age range 24-36 years, duration of diabetes greater than 10 years) usually treated with twice daily Actrapid MC and Monotard MC and with stable insulin requirements and diabetic control. On separate mornings each patient was given, after an overnight fast, their usual dose of either Actrapid MC and Monotard MC or Humulin S and Humulin Zn injected 5, 20, or 40 min before a standard breakfast. The postprandial glycaemic profile was not significantly different at any of the three time intervals with Actrapid MC and Monotard MC. However, with the human insulin the profile was significantly better at the 40 min interval than at the 5 min interval (p less than 0.05) and this was also better than any of the profiles with the porcine insulin, there being a significant difference between the two types of insulin (p less than 0.05). These findings suggest that the time interval between insulin injection and breakfast may be more important with human insulin than with porcine insulin.

  2. Symptoms of hypoglycemia--a comparison between porcine and human insulin.

    PubMed

    Jakober, B; Lingenfelser, T; Glück, H; Maassen, T; Overkamp, D; Renn, W; Eggstein, M

    1990-05-04

    For more than 2 years now it has been controversially debated whether awareness of hypoglycemia is reduced when type I diabetic patients are switched from porcine to human insulin. In order to address this question, we studied nine C-peptide negative diabetics (age 27.6 years, Broca index 106%, duration of diabetes 5.7 years, HbA1, 8.8%) in comparison with eight healthy volunteers (age 22.4 years, Broca index 104%). Following euglycemic monitoring overnight, a controlled hypoglycemia was induced by altering the algorithms of the Biostator. This was done in a double-blind, cross-over fashion using porcine or human insulin on 2 nonconsecutive days. There were no differences between the results obtained with respect to the time course of the study, blood glucose, amount of insulin infused, and concentration of venous free insulin achieved. Of the nine diabetics, eight were aware of hypoglycemia at a higher blood glucose level under porcine insulin. The first symptom of hypoglycemia was perceived at a mean blood glucose level of 61.1 +/- 5.4 mg/dl under porcine insulin and of 44.4 +/- 5.3 mg/dl under human insulin (P less than or equal to 0.05). Thirty symptoms were noted under porcine insulin exclusively or preferentially as opposed to only eight which were observed exclusively or preferentially under human insulin. The healthy volunteers evidenced fewer symptoms at lower blood glucose concentrations than the diabetics. The clear difference between human and porcine insulin could not unequivocally be reproduced in this group.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Large-Scale Refolding and Enzyme Reaction of Human Preproinsulin for Production of Human Insulin.

    PubMed

    Kim, Chang-Kyu; Lee, Seung-Bae; Son, Young-Jin

    2015-10-01

    Human insulin is composed of 21 amino acids of an A-chain and 30 amino acids of a B-chain. This is the protein hormone that has the role of blood sugar control. When the recombinant human proinsulin is expressed in Escherichia coli, a serious problem is the formation of an inclusion body. Therefore, the inclusion body must be denatured and refolded under chaotropic agents and suitable reductants. In this study, H27R-proinsulin was refolded from the denatured form with β-mercaptoethanol and urea. The refolding reaction was completed after 15 h at 15°C, whereas the reaction at 25°C was faster than that at 15°C. The refolding yield at 15°C was 17% higher than that at 25°C. The refolding reaction could be carried out at a high protein concentration (2 g/l) using direct refolding without sulfonation. The most economical and optimal refolding condition for human preproinsulin was 1.5 g/l protein, 10 mM glycine buffer containing 0.6 M urea, pH 10.6, and 0.3 mM β-mercaptoethanol at 15°C for 16 h. The maximum refolding yield was 74.8% at 15°C with 1.5 g/l protein. Moreover, the refolded preproinsulin could be converted into normal mature insulin with two enzymes. The average amount of human insulin was 138.2 g from 200 L of fermentation broth after enzyme reaction with H27R-proinsulin. The direct refolding process for H27R-proinsulin was successfully set up without sulfonation. The step yields for refolding and enzyme reaction were comparatively high. Therefore, our refolding process for production of recombinant insulin may be beneficial to the large-scale production of other biologically active proteins.

  4. A single-islet microplate assay to measure mouse and human islet insulin secretion.

    PubMed

    Truchan, Nathan A; Brar, Harpreet K; Gallagher, Shannon J; Neuman, Joshua C; Kimple, Michelle E

    2015-01-01

    One complication to comparing β-cell function among islet preparations, whether from genetically identical or diverse animals or human organ donors, is the number of islets required per assay. Islet numbers can be limiting, meaning that fewer conditions can be tested; other islet measurements must be excluded; or islets must be pooled from multiple animals/donors for each experiment. Furthermore, pooling islets negates the possibility of performing single-islet comparisons. Our aim was to validate a 96-well plate-based single islet insulin secretion assay that would be as robust as previously published methods to quantify glucose-stimulated insulin secretion from mouse and human islets. First, we tested our new assay using mouse islets, showing robust stimulation of insulin secretion 24 or 48 h after islet isolation. Next, we utilized the assay to quantify mouse islet function on an individual islet basis, measurements that would not be possible with the standard pooled islet assay methods. Next, we validated our new assay using human islets obtained from the Integrated Islet Distribution Program (IIDP). Human islets are known to have widely varying insulin secretion capacity, and using our new assay we reveal biologically relevant factors that are significantly correlated with human islet function, whether displayed as maximal insulin secretion response or fold-stimulation of insulin secretion. Overall, our results suggest this new microplate assay will be a useful tool for many laboratories, expert or not in islet techniques, to be able to precisely quantify islet insulin secretion from their models of interest.

  5. Dopamine-Mediated Autocrine Inhibitory Circuit Regulating Human Insulin Secretion in Vitro

    PubMed Central

    Simpson, Norman; Maffei, Antonella; Freeby, Matthew; Burroughs, Steven; Freyberg, Zachary; Javitch, Jonathan; Leibel, Rudolph L.

    2012-01-01

    We describe a negative feedback autocrine regulatory circuit for glucose-stimulated insulin secretion in purified human islets in vitro. Using chronoamperometry and in vitro glucose-stimulated insulin secretion measurements, evidence is provided that dopamine (DA), which is loaded into insulin-containing secretory granules by vesicular monoamine transporter type 2 in human β-cells, is released in response to glucose stimulation. DA then acts as a negative regulator of insulin secretion via its action on D2R, which are also expressed on β-cells. We found that antagonism of receptors participating in islet DA signaling generally drive increased glucose-stimulated insulin secretion. These in vitro observations may represent correlates of the in vivo metabolic changes associated with the use of atypical antipsychotics, such as increased adiposity. PMID:22915827

  6. [Measurement of proinsulin, insulin and C-peptide in human blood by high performance liquid chromatography].

    PubMed

    Povazhenko, A A; Ryzhova, T I; Kozyreva, E V

    1997-09-01

    The technique of measuring insulin, proinsulin, and C-peptide in human blood by high-pressure liquid chromatography is described. Donors, subjects with abnormal glucose tolerance, and patients with type I diabetes were examined. The main advantage of the method over radioimmunoassay and enzyme immunoassay is the possibility of simultaneous differentiated measurement of human insulin and animal hormone administered parenterally, and separation of insulin and its precursor on the basis of difference in molecular weight and charge of molecules. The results indicate that patients with type I diabetes retain the secretion of endogenous insulin, although its level is appreciably lower than in healthy donors, and the structure of its molecules is heterogeneous, which is proven by a biphasic chromatographic peak. Inhibition of proinsulin transformation into insulin is one probable mechanism of impairment of glucose tolerance. High-pressure liquid chromatography can be used at clinical laboratories for examinations of diabetics.

  7. Activation of transforming potential of the human insulin receptor gene

    SciTech Connect

    Wang, L.H.; Lin, B.; Jong, S.M.J.; Dixon, D.; Ellis, L.; Roth, R.A.; Rutter, W.J.

    1987-08-01

    A retrovirus containing part of the human insulin receptor (hIR) gene was constructed by replacing ros sequences in the avian sarcoma virus UR2 with hIR cDNA sequences coding for 46 amino acids of the extracellular domain and the entire transmembrane and cytoplasmic domains of the ..beta.. subunit of hIR. The resulting virus, named UIR, contains the hIR sequence fused to the 5' portion of the UR2 gag gene coding for p19. UIR is capable of transforming chicken embryo fibroblasts and promoting formation of colonies in soft agar; however, it does not form tumors in vivo. A variant that arose from the parental UIR is capable of efficiently inducing sarcomas in vivo. UIR-transformed cells exhibit higher rates of glucose uptake and growth than normal cells. The 4-kilobase UIR genome codes for a membrane-associated, glycosylated gag-hIR fusion protein of 75 kDa designated P75/sup gag-hir/. P75/sup gag-hir/ contains a protein tyrosine kinase activity that is capable of undergoing autophosphorylation and of phosphorylating foreign substrates in vitro; it is phosphorylated at both serine and tyrosine residues in vivo

  8. Pharmacokinetics and Pharmacodynamics of High-Dose Human Regular U-500 Insulin Versus Human Regular U-100 Insulin in Healthy Obese Subjects

    PubMed Central

    de la Peña, Amparo; Riddle, Matthew; Morrow, Linda A.; Jiang, Honghua H.; Linnebjerg, Helle; Scott, Adam; Win, Khin M.; Hompesch, Marcus; Mace, Kenneth F.; Jacobson, Jennie G.; Jackson, Jeffrey A.

    2011-01-01

    OBJECTIVE Human regular U-500 (U-500R) insulin (500 units/mL) is increasingly being used clinically, yet its pharmacokinetics (PK) and pharmacodynamics (PD) have not been well studied. Therefore, we compared PK and PD of clinically relevant doses of U-500R with the same doses of human regular U-100 (U-100R) insulin (100 units/mL). RESEARCH DESIGN AND METHODS This was a single-site, randomized, double-blind, crossover euglycemic clamp study. Single subcutaneous injections of 50- and 100-unit doses of U-500R and U-100R were administered to 24 healthy obese subjects. RESULTS Both overall insulin exposure (area under the serum insulin concentration versus time curve from zero to return to baseline [AUC0-t’]) and overall effect (total glucose infused during a clamp) were similar between formulations at both 50- and 100-unit doses (90% [CI] of ratios contained within [0.80, 1.25]). However, peak concentration and effect were significantly lower for U-500R at both doses (P < 0.05). Both formulations produced relatively long durations of action (18.3 to 21.5 h). Time-to-peak concentration and time to maximum effect were significantly longer for U-500R than U-100R at the 100-unit dose (P < 0.05). Time variables reflective of duration of action (late tRmax50, tRlast) were prolonged for U-500R versus U-100R at both doses (P < 0.05). CONCLUSIONS Overall exposure to and action of U-500R insulin after subcutaneous injection were no different from those of U-100R insulin. For U-500R, peaks of concentration and action profiles were blunted and the effect after the peak was prolonged. These findings may help guide therapy with U-500R insulin for highly insulin-resistant patients with diabetes. PMID:21994429

  9. Clinical use of the co-formulation of insulin degludec and insulin aspart.

    PubMed

    Kumar, A; Awata, T; Bain, S C; Ceriello, A; Fulcher, G R; Unnikrishnan, A G; Arechavaleta, R; Gonzalez-Gálvez, G; Hirose, T; Home, P D; Kaku, K; Litwak, L; Madsbad, S; Pinget, M; Mehta, R; Mithal, A; Tambascia, M; Tibaldi, J; Christiansen, J S

    2016-08-01

    To provide a review of the available data and practical use of insulin degludec with insulin aspart (IDegAsp). Premixed insulins provide basal and prandial glucose control; however, they have an intermediate-acting prandial insulin component and do not provide as effective basal coverage as true long-acting insulins, owing to the physicochemical incompatibility of their individual components, coupled with the inflexibility of adjustment. The molecular structure of the co-formulation of IDegAsp, a novel insulin preparation, allows these two molecules to coexist without affecting their individual pharmacodynamic profiles. Clinical evidence in phase 2/3 trials of IDegAsp efficacy and safety in type 1 and type 2 diabetes mellitus (T1DM and T2DM) have been assessed and summarised. In people with T2DM, once- and twice-daily dosing provides similar overall glycaemic control (HbA1c ) to current modern insulins, but with lower risk of nocturnal hypoglycaemia. In prior insulin users, glycaemic control was achieved with lower or equal insulin doses vs. other basal+meal-time or premix insulin regimens. In insulin-naïve patients with T2DM, IDegAsp can be started once or twice-daily, based on individual need. People switching from more than once-daily basal or premix insulin therapy can be converted unit-to-unit to once-daily IDegAsp, although this strategy should be assessed by the physician on an individual basis. IDegAsp offers physicians and people with T2DM a simpler insulin regimen than other available basal-bolus or premix-based insulin regimens, with stable daytime basal coverage, a lower rate of hypoglycaemia and some flexibility in injection timing compared with premix insulins. © 2016 John Wiley & Sons Ltd.

  10. Characterization of the growth of murine fibroblasts that express human insulin receptors. I. The effect of insulin in the absence of other growth factors

    SciTech Connect

    Randazzo, P.A.; Morey, V.A.; Polishook, A.K.; Jarett, L. )

    1990-09-01

    The effect of insulin on the growth of murine fibroblasts transfected with an expression vector containing human insulin receptor cDNA (NIH 3T3/HIR) and the parental cells (NIH/3T3) was characterized. Insulin in the absence of other mitogens increased the rate of incorporation of thymidine into NIH 3T3/HIR cells with a half-maximal response occurring at an insulin concentration of 35 ng/ml and a maximal response that was equivalent to that elicited by 10% fetal calf serum. The thymidine incorporation rate was increased by 12 h, was maximal at approximately 16 h, and returned to basal rates at 24 h after the addition of insulin. Insulin induced a maximum of 65% of cells to incorporate thymidine. The increased DNA synthesis was accompanied by net growth. Addition of insulin to the NIH 3T3/HIR cells resulted in increased DNA content with a half-maximal response occurring at approximately 30 ng/ml insulin and a maximal response equivalent to that elicited by serum. An increase in cell number detected after the addition of insulin to the NIH 3T3/HIR suggests that the cells had progressed through mitosis. Insulin did not increase the rate of thymidine incorporation, DNA content, or number of the parental NIH 3T3 cells. These data show that insulin, in the absence of a second mitogen, is able to induce NIH 3T3/HIR fibroblasts to traverse the cell cycle.

  11. Effect of Human Myotubes-Derived Media on Glucose-Stimulated Insulin Secretion

    PubMed Central

    Cataldo, Luis R.; Gutierrez, Juan; Santos, José L.; Casas, Mariana; Contreras-Ferrat, Ariel E.; Moro, Cedric; Bouzakri, Karim

    2017-01-01

    Fasting to postprandial transition requires a tight adjustment of insulin secretion to its demand, so tissue (e.g., skeletal muscle) glucose supply is assured while hypo-/hyperglycemia are prevented. High muscle glucose disposal after meals is pivotal for adapting to increased glycemia and might drive insulin secretion through muscle-released factors (e.g., myokines). We hypothesized that insulin influences myokine secretion and then increases glucose-stimulated insulin secretion (GSIS). In conditioned media from human myotubes incubated with/without insulin (100 nmol/L) for 24 h, myokines were qualitatively and quantitatively characterized using an antibody-based array and ELISA-based technology, respectively. C57BL6/J mice islets and Wistar rat beta cells were incubated for 24 h with control and conditioned media from noninsulin- and insulin-treated myotubes prior to GSIS determination. Conditioned media from insulin-treated versus nontreated myotubes had higher RANTES but lower IL6, IL8, and MCP1 concentration. Qualitative analyses revealed that conditioned media from noninsulin- and insulin-treated myotubes expressed 32 and 23 out of 80 myokines, respectively. Islets incubated with conditioned media from noninsulin-treated myotubes had higher GSIS versus control islets (p < 0.05). Meanwhile, conditioned media from insulin-treated myotubes did not influence GSIS. In beta cells, GSIS was similar across conditions. In conclusion, factors being present in noninsulin-stimulated muscle cell-derived media appear to influence GSIS in mice islets. PMID:28286777

  12. Sustained prolonged topical delivery of bioactive human insulin for potential treatment of cutaneous wounds.

    PubMed

    Hrynyk, Michael; Martins-Green, Manuela; Barron, Annelise E; Neufeld, Ronald J

    2010-10-15

    Skin damaged by heat, radiation, or chemical exposure is difficult to treat and slow to heal. Indeed full restoration of the tissue is difficult to obtain. Sub-dermal insulin injection was recently shown to stimulate wound healing of the skin by accelerating wound closure, stimulating angiogenesis and inducing a regenerative process of healing. We have developed a topical delivery vehicle that is capable of releasing therapeutic levels of bioactive insulin for several weeks with the potential to stimulate and sustain healing. By encapsulating the crystalline form of insulin within poly(d,l-lactide-co-glycolide) microspheres, we succeeded in stabilizing and then releasing bioactive insulin for up to 25 days. To measure bioactivity we used Rat L6 myofibroblasts, stimulated them with this slow release insulin and determined activation of the receptors on the cell surface by quantifying AKT phosphorylation. There was only a minor and gradual decrease in AKT phosphorylation over time. To determine whether the slow release insulin could stimulate keratinocyte migration, wounding was simulated by scratching confluent cultures of human keratinocytes (HaCaT). Coverage of the scratch "wounds" was significantly faster in the presence of insulin released from microspheres than in the insulin-free control. Extended and sustained topical delivery of active insulin from a stable protein crystal-based reservoir shows promise in promoting tissue healing. Copyright 2010 Elsevier B.V. All rights reserved.

  13. Effect of Human Myotubes-Derived Media on Glucose-Stimulated Insulin Secretion.

    PubMed

    Mizgier, Maria L; Cataldo, Luis R; Gutierrez, Juan; Santos, José L; Casas, Mariana; Llanos, Paola; Contreras-Ferrat, Ariel E; Moro, Cedric; Bouzakri, Karim; Galgani, Jose E

    2017-01-01

    Fasting to postprandial transition requires a tight adjustment of insulin secretion to its demand, so tissue (e.g., skeletal muscle) glucose supply is assured while hypo-/hyperglycemia are prevented. High muscle glucose disposal after meals is pivotal for adapting to increased glycemia and might drive insulin secretion through muscle-released factors (e.g., myokines). We hypothesized that insulin influences myokine secretion and then increases glucose-stimulated insulin secretion (GSIS). In conditioned media from human myotubes incubated with/without insulin (100 nmol/L) for 24 h, myokines were qualitatively and quantitatively characterized using an antibody-based array and ELISA-based technology, respectively. C57BL6/J mice islets and Wistar rat beta cells were incubated for 24 h with control and conditioned media from noninsulin- and insulin-treated myotubes prior to GSIS determination. Conditioned media from insulin-treated versus nontreated myotubes had higher RANTES but lower IL6, IL8, and MCP1 concentration. Qualitative analyses revealed that conditioned media from noninsulin- and insulin-treated myotubes expressed 32 and 23 out of 80 myokines, respectively. Islets incubated with conditioned media from noninsulin-treated myotubes had higher GSIS versus control islets (p < 0.05). Meanwhile, conditioned media from insulin-treated myotubes did not influence GSIS. In beta cells, GSIS was similar across conditions. In conclusion, factors being present in noninsulin-stimulated muscle cell-derived media appear to influence GSIS in mice islets.

  14. Differential effects of insulin deficiency on albumin and fibrinogen synthesis in humans.

    PubMed Central

    De Feo, P; Gaisano, M G; Haymond, M W

    1991-01-01

    Insulin deficiency decreases tissue protein synthesis, albumin mRNA concentration, and albumin synthesis in rats. In contrast, insulin deficiency does not change, or, paradoxically, increases estimates of whole body protein synthesis in humans. To determine if such estimates of whole body protein synthesis could obscure potential differential effects of insulin on the synthetic rates of individual proteins, we determined whole body protein synthesis and albumin and fibrinogen fractional synthetic rates using 5-h simultaneous infusions of [14C]leucine and [13C]bicarbonate, in six type 1 diabetics during a continuous i.v. insulin infusion (to maintain euglycemia) and after short-term insulin withdrawal (12 +/- 2 h). Insulin withdrawal increased (P less than 0.03) whole body proteolysis by approximately 35% and leucine oxidation by approximately 100%, but did not change 13CO2 recovery from NaH13CO3 or estimates of whole body protein synthesis (P = 0.21). Insulin deficiency was associated with a 29% decrease (P less than 0.03) in the albumin fractional synthetic rate but a 50% increase (P less than 0.03) in that of fibrinogen. These data provide strong evidence that albumin synthesis in humans is an insulin-sensitive process, a conclusion consistent with observations in rats. The increase in fibrinogen synthesis during insulin deficiency most likely reflects an acute phase protein response due to metabolic stress. These data suggest that the absence of changes in whole body protein synthesis after insulin withdrawal is the result of the summation of differential effects of insulin deficiency on the synthesis of specific body proteins. PMID:1909352

  15. Treatment of insulin resistance by acupuncture: a review of human and animal studies.

    PubMed

    Martinez, Bridget; Peplow, Philip V

    2016-08-01

    Numerous experimental studies have demonstrated that acupuncture can correct various metabolic disorders such as hyperglycaemia, overweight, hyperphagia, hyperlipidaemia, inflammation, altered activity of the sympathetic nervous system, and insulin signalling defects, all of which contribute to the development of insulin resistance. To review human and animal studies investigating acupuncture as a treatment for insulin resistance, and to evaluate its potential to increase insulin sensitivity. PubMed was searched for relevant articles published between January 2008 and October 2015. Search terms used were 'acupuncture', 'insulin resistance', 'insulin sensitivity', and 'blood glucose'. Additional secondary sources of information included reference lists from retrieved papers and pertinent papers identified by hand searches of relevant journals not found in the database. In total, 31 articles were included in this review and comprised studies of the following insulin resistant conditions: obesity (n=9); diabetes mellitus (n=12); polycystic ovarian syndrome (n=7); skeletal muscle atrophy (n=1); ischaemic heart disease (n=1); and fatty liver disease (n=1). Of these articles, seven were human trials and 24 animal experiments. Collectively, the studies suggest that electroacupuncture (EA) at low intensity and low frequency can reduce insulin resistance and increase insulin sensitivity in a range of different insulin-resistant conditions. EA, used alone or in combination with other therapies, such as Chinese herbs or diet-exercise interventions, has the potential to be an effective treatment for insulin resistance. Additional controlled clinical studies of acupuncture are needed in subjects with diabetes mellitus, ischaemic heart disease, muscle atrophy, and fatty liver disease. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  16. Destabilization of Human Insulin Fibrils by Peptides of Fruit Bromelain Derived From Ananas comosus (Pineapple).

    PubMed

    Das, Sromona; Bhattacharyya, Debasish

    2017-05-26

    Deposition of insulin aggregates in human body leads to dysfunctioning of several organs. Effectiveness of fruit bromelain from pineapple in prevention of insulin aggregate was investigated. Proteolyses of bromelain was done as par human digestive system and the pool of small peptides was separated from larger peptides and proteins. Under conditions of growth of insulin aggregates from its monomers, this pool of peptides restricted the reaction upto formation of oligomers of limited size. These peptides also destabilized preformed insulin aggregates to oligomers. These processes were followed fluorimetrically using Thioflavin T and 1-ANS, size-exclusion HPLC, dynamic light scattering, atomic force microscopy, and transmission electron microscopy. Sequences of insulin (A and B chains) and bromelain were aligned using Clustal W software to predict most probable sites of interactions. Synthetic tripeptides corresponding to the hydrophobic interactive sites of bromelain showed disaggregation of insulin suggesting specificity of interactions. The peptides GG and AAA serving as negative controls showed no potency in destabilization of aggregates. Disaggregation potency of the peptides was also observed when insulin was deposited on HepG2 liver cells where no formation of toxic oligomers occurred. Amyloidogenic des-octapeptide (B23-B30 of insulin) incapable of cell signaling showed cytotoxicity similar to insulin. This toxicity could be neutralized by bromelain derived peptides. FT-IR and far-UV circular dichroism analysis indicated that disaggregated insulin had structure distinctly different from that of its hexameric (native) or monomeric states. Based on the stoichiometry of interaction and irreversibility of disaggregation, the mechanism/s of the peptides and insulin interactions has been proposed. J. Cell. Biochem. 9999: 1-16, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  17. The human insulin gene is part of a large open chromatin domain specific for human islets.

    PubMed

    Mutskov, Vesco; Felsenfeld, Gary

    2009-10-13

    Knowledge of how insulin (INS) gene expression is regulated will lead to better understanding of normal and abnormal pancreatic beta cell function. We have mapped histone modifications over the INS region, coupled with an expression profile, in freshly isolated islets from multiple human donors. Unlike many other human genes, in which active modifications tend to be concentrated within 1 kb around the transcription start site, these marks are distributed over the entire coding region of INS as well. Moreover, a region of approximately 80 kb around the INS gene, which contains the {tyrosine hydroxylase (TH)-(INS)-insulin-like growth factor 2 antisense (IGF2AS)-insulin-like growth factor 2 (IGF2)} gene cluster, unusually is marked by almost uniformly elevated levels of histone acetylation and H3K4 dimethylation, extending both downstream into IGF2 and upstream beyond the TH gene. This is accompanied by islet specific coordinate expression with INS of the neighboring TH and IGF2 genes. The presence of islet specific intergenic transcripts suggests their possible function in the maintenance of this unusual large open chromatin domain.

  18. Effects of pasteurization on adiponectin and insulin concentrations in donor human milk.

    PubMed

    Ley, Sylvia H; Hanley, Anthony J; Stone, Debbie; O'Connor, Deborah L

    2011-09-01

    Although pasteurization is recommended before distributing donor human milk in North America, limited data are available on its impact on metabolic hormones in milk. We aimed to investigate the effects of pasteurization on adiponectin and insulin concentrations in donor human milk. The study investigates concentrations of components in donor human milk before and after Holder pasteurization. After the guidelines of the Human Milk Bank Association of North America, human milk samples were pooled to produce 17 distinct batches (4 individuals per batch) and pasteurized at 62.5°C for 30 min. Adiponectin, insulin, energy, fat, total protein, and glucose concentrations were measured pre- and postpasteurization. Pasteurization reduced milk adiponectin and insulin by 32.8 and 46.1%, respectively (both p < 0.0001). Adiponectin and insulin were significantly correlated with energy and fat milk composition (r = 0.36-0.47; all p < 0.05). Pasteurization effects on milk hormone concentrations remained significant after adjusting for fat and energy (beta ± SEE: -4.11 ± 1.27, p = 0.003 for adiponectin; -70.0 ± 15.0, p < 0.0001 for insulin). Holder pasteurization reduced adiponectin and insulin concentrations in donor human milk. In view of emerging knowledge on the importance of milk components, continued work to find the optimal pasteurization process that mitigates risks but promotes retention of bioactive components is needed.

  19. Human Y-79 Retinoblastoma Cells Exhibit Specific Insulin Receptors.

    DTIC Science & Technology

    1985-01-01

    receptor. The Scatchard plot of, inulin competition data was curvilinear and was resolved in a high affinity Kd M) - low capacity ( ~ 3,000 sites/cell...containing insulin receptor antibodies (Flier et al 1977) was a gift of Dr. Philip Gorden, Diabetes Branch, NIADDK, NIH. Eagle’s minimum essential medium...Houten, M., Posner, B.I., White, R.J., Ohgaku, S., Horvat, A., and Hemmelgarn, E. (1983) Binding of insulin by monkey and pig hypothalamus. Diabetes 32

  20. Turbulent transport in premixed flames

    NASA Technical Reports Server (NTRS)

    Rutland, C. J.; Cant, R. S.

    1994-01-01

    Simulations of planar, premixed turbulent flames with heat release were used to study turbulent transport. Reynolds stress and Reynolds flux budgets were obtained and used to guide the investigation of important physical effects. Essentially all pressure terms in the transport equations were found to be significant. In the Reynolds flux equations, these terms are the major source of counter-gradient transport. Viscous and molecular terms were also found to be significant, with both dilatational and solenoidal terms contributing to the Reynolds stress dissipation. The BML theory of premixed turbulent combustion was critically examined in detail. The BML bimodal pdf was found to agree well with the DNS data. All BML decompositions, through the third moments, show very good agreement with the DNS results. Several BML models for conditional terms were checked using the DNS data and were found to require more extensive development.

  1. Inflammatory Induction of Human Resistin Causes Insulin Resistance in Endotoxemic Mice

    PubMed Central

    Park, Hyeong-Kyu; Qatanani, Mohammed; Briggs, Erika R.; Ahima, Rexford S.; Lazar, Mitchell A.

    2011-01-01

    OBJECTIVE Although adipocyte-derived murine resistin links insulin resistance to obesity, the role of human resistin, predominantly expressed in mononuclear cells and induced by inflammatory signals, remains unclear. Given the mounting evidence that obesity and type 2 diabetes are inflammatory diseases, we sought to determine the relationship between inflammatory increases in human resistin and insulin resistance. RESEARCH DESIGN AND METHODS To investigate the role of human resistin on glucose homeostasis in inflammatory states, we generated mice lacking murine resistin but transgenic for a bacterial artificial chromosome containing human resistin (BAC-Retn), whose expression was similar to that in humans. The metabolic and molecular phenotypes of BAC-Retn mice were assessed after acute and chronic endotoxemia (i.e., exposure to inflammatory lipopolysaccharide). RESULTS We found that BAC-Retn mice have circulating resistin levels within the normal human range, and similar to humans, lipopolysaccharide markedly increased serum resistin levels. Acute endotoxemia caused hypoglycemia in mice lacking murine resistin, and this was attenuated in BAC-Retn mice. In addition, BAC-Retn mice developed severe hepatic insulin resistance under chronic endotoxemia, accompanied by increased inflammatory responses in liver and skeletal muscle. CONCLUSIONS These results strongly support the role of human resistin in the development of insulin resistance in inflammation. Thus, human resistin may link insulin resistance to inflammatory diseases such as obesity, type 2 diabetes, and atherosclerosis. PMID:21282361

  2. Assessment of intracellular insulin content during all steps of human islet isolation procedure.

    PubMed

    Brandhorst, H; Brandhorst, D; Brendel, M D; Hering, B J; Bretzel, R G

    1998-01-01

    This study investigated the recovery of pancreatic insulin content during human islet isolation prior to and after digestion-filtration, continuous Hanks-Ficoll gradient purification (n = 20), and 3-4 day culture at 22 degrees C (n = 6). The native insulin content varied in a wide range from 28.4 U to 360.8 U/pancreas. After digestion the initially measured average insulin content of 115.8 +/- 20.8 U/pancreas (mean +/- SEM) increased to 264.6 +/- 22.8% (p < 0.001). This increase of insulin during pancreas digestion was attributed to the asymetrical distribution of insulin within the pancreas. Sampling of insulin within the pancreatic caput seemed not to be representative for the insulin content of the complete native organ, because the ratio of insulin per gram tissue within the pancreatic cauda compared to the caput (n = 5) was 2.4 +/- 0.4 (p < 0.05). After purification total insulin recovery was 55.3 +/- 4.8% (p < 0.001). Because recovery of islet equivalent number (IEQ) (83.7 +/- 4.4%) exceeded insulin recovery, insulin/IEQ ratio decreased from 656.8 +/- 70.6 microU/IEQ before purification to 436.4 +/- 58.1 microU/IEQ (p < 0.001) after purification. After 22 degrees C culture (n = 6) recovery of insulin and IEQ was 80.1 +/- 8.1% (p < 0.05) and 92.8 +/- 3.5% (p = NS), respectively. Insulin content per IEQ decreased to 85.8 +/- 6.5% (p < 0.05). This study clearly shows that most of islet insulin is lost during purification. This seems to be caused rather by an amplified insulin release than by the loss of islets itself. This release may facilitate the separation of endocrine and exocrine tissue by gradient centrifugation, but may also accelerate islet exhaustion detrimental for long-term insulin independence.

  3. Insulin sensitization of human preadipocytes through glucocorticoid hormone induction of forkhead transcription factors.

    PubMed

    Tomlinson, Julianna J; Boudreau, Adèle; Wu, Dongmei; Abdou Salem, Houssein; Carrigan, Amanda; Gagnon, AnneMarie; Mears, Alan J; Sorisky, Alexander; Atlas, Ella; Haché, Robert J G

    2010-01-01

    Glucocorticoids are synthesized locally in adipose tissue and contribute to metabolic disease through the facilitation of adipose tissue expansion. Here we report that exposure of human primary preadipocytes to glucocorticoids increases their sensitivity to insulin and enhances their subsequent response to stimuli that promote differentiation. This effect was observed in primary human preadipocytes but not in immortalized 3T3-L1 murine preadipocytes or in fully differentiated primary human adipocytes. Stimulation of insulin signaling was mediated through induction of insulin receptor (IR), IR substrate protein 1 (IRS1), IRS2, and the p85 regulatory subunit of phosphoinositide-3-3-kinase, which led to enhanced insulin-mediated activation of Akt. Although induction of IRS2 was direct, induction of IR and IRS1 by glucocorticoids occurred subsequent to primary induction of the forkhead family transcription factors FoxO1A and FoxO3A. These results reveal a new role for glucocorticoids in preparing preadipocytes for differentiation.

  4. Lewis Number Effects on Partially Premixed Flames

    NASA Technical Reports Server (NTRS)

    Ruetsch, G. R.; Ferziger, J.

    1996-01-01

    Combustion is generally categorized as either premixed, where flames propagate into homogeneous mixtures of reactants, or as nonpremixed, where initially separated reactants diffuse into the reaction zones. Although these approaches are applicable to many combustion devices, there are cases not in either of these two limiting regimes. Under such circumstances, one must consider partially premixed combustion. In partially premixed combustion, mechanisms from both premixed and nonpremixed regimes coexist and, as a result, some interesting phenomena arise. One such phenomenon is flame stabilization in laminar mixing layers by triple flames.

  5. Alternative signaling network activation through different insulin receptor family members caused by pro-mitogenic antidiabetic insulin analogues in human mammary epithelial cells.

    PubMed

    ter Braak, Bas; Wink, Steven; Koedoot, Esmee; Pont, Chantal; Siezen, Christine; van der Laan, Jan Willem; van de Water, Bob

    2015-07-19

    Insulin analogues are designed to have improved pharmacokinetic parameters compared to regular human insulin. This provides a sustained control of blood glucose levels in diabetic patients. All novel insulin analogues are tested for their mitogenic side effects, however these assays do not take into account the molecular mode of action of different insulin analogues. Insulin analogues can bind the insulin receptor and the insulin-like growth factor 1 receptor with different affinities and consequently will activate different downstream signaling pathways. Here we used a panel of MCF7 human breast cancer cell lines that selectively express either one of the isoforms of the INSR or the IGF1R. We applied a transcriptomics approach to assess the differential transcriptional programs activated in these cells by either insulin, IGF1 or X10 treatment. Based on the differentially expressed genes between insulin versus IGF1 and X10 treatment, we retrieved a mitogenic classifier gene set. Validation by RT-qPCR confirmed the robustness of this gene set. The translational potential of these mitogenic classifier genes was examined in primary human mammary cells and in mammary gland tissue of mice in an in vivo model. The predictive power of the classifier genes was evaluated by testing all commercial insulin analogues in the in vitro model and defined X10 and glargine as the most potent mitogenic insulin analogues. We propose that these mitogenic classifier genes can be used to test the mitogenic potential of novel insulin analogues as well as other alternative molecules with an anticipated affinity for the IGF1R.

  6. Insulin stimulates synthesis and release of human chorionic gonadotropin by choriocarcinoma cell lines

    SciTech Connect

    Ren, S.G.; Braunstein, G.D. )

    1991-03-01

    Recent studies have shown that insulin regulates placental lactogen, progesterone, and estrogen production from human trophoblast cells. This study was performed to examine whether insulin also regulates the production of hCG by this type of cell. After 24-36 h of preincubation, JEG-3 and JAR cells (2-3 x 10(5) cells/ml.well) or human term trophoblast cells (1 x 10(6) cells/ml.well) were exposed to the test hormone in serum-free Dulbecco's Modified Eagle's Medium for 24-96 h. Secretion of hCG from JEG-3 cells was stimulated by human insulin, human proinsulin, or porcine insulin in a dose-dependent manner, with lowest effective doses of 6.7, 96, and 53 mg/L, respectively. Time-course studies showed that hCG secretion peaked at 72-96 h with insulin exposure; in contrast, no decernable peak was seen without insulin in serum-free media. Exposure of JEG-3 cells for 24 h to 209 mg/liter insulin stimulated hCG synthesis, with 40 +/- 3% more immunoreactive intracellular hCG (P less than 0.05). Cells grown in the presence of insulin and (35S)methionine had 47 +/- 21% more labeled intracellular hCG and 56 +/- 13% more immunoprecipitable (35S)methionine-hCG secreted into the medium than the control cultures (P less than 0.05). During this time period, human placental lactogen release and total trichloroacetice acid-precipitable (35S)methionine protein were not increased. The insulin-induced stimulation of hCG synthesis was inhibited by cycloheximide. Additionally, insulin did not significantly affect total intracellular protein during 24-96 h of incubation. Insulin also increased hCG release from JAR cells, but not from human term trophoblast cells. A mouse monoclonal antibody to the IGF-I receptor inhibited the stimulation of insulin in JEG-3 cells.

  7. Interleukin-1β mediates macrophage-induced impairment of insulin signaling in human primary adipocytes.

    PubMed

    Gao, Dan; Madi, Mohamed; Ding, Cherlyn; Fok, Matthew; Steele, Thomas; Ford, Christopher; Hunter, Leif; Bing, Chen

    2014-08-01

    Adipose tissue expansion during obesity is associated with increased macrophage infiltration. Macrophage-derived factors significantly alter adipocyte function, inducing inflammatory responses and decreasing insulin sensitivity. Identification of the major factors that mediate detrimental effects of macrophages on adipocytes may offer potential therapeutic targets. IL-1β, a proinflammatory cytokine, is suggested to be involved in the development of insulin resistance. This study investigated the role of IL-1β in macrophage-adipocyte cross-talk, which affects insulin signaling in human adipocytes. Using macrophage-conditioned (MC) medium and human primary adipocytes, we examined the effect of IL-1β antagonism on the insulin signaling pathway. Gene expression profile and protein abundance of insulin signaling molecules were determined, as was the production of proinflammatory cytokine/chemokines. We also examined whether IL-1β mediates MC medium-induced alteration in adipocyte lipid storage. MC medium and IL-1β significantly reduced gene expression and protein abundance of insulin signaling molecules, including insulin receptor substrate-1, phosphoinositide 3-kinase p85α, and glucose transporter 4 and phosphorylation of Akt. In contrast, the expression and release of the proinflammatory markers, including IL-6, IL-8, monocyte chemotactic protein-1, and chemokine (C-C motif) ligand 5 by adipocytes were markedly increased. These changes were significantly reduced by blocking IL-1β activity, its receptor binding, or its production by macrophages. MC medium-inhibited expression of the adipogenic factors and -stimulated lipolysis was also blunted with IL-1β neutralization. We conclude that IL-1β mediates, at least in part, the effect of macrophages on insulin signaling and proinflammatory response in human adipocytes. Blocking IL-1β could be beneficial for preventing obesity-associated insulin resistance and inflammation in human adipose tissue. Copyright

  8. Root and shoot parts of strawberry: factories for production of functional human pro-insulin.

    PubMed

    Tavizi, Ashkan; Javaran, Mokhtar Jalali; Moieni, Ahmad; Mohammadi-Dehcheshmeh, Manijeh; Mohebodini, Mehdi; Ebrahimie, Esmaeil

    2015-05-01

    Diabetes, a disease caused by excessive blood sugar, is caused by the lack of insulin. For commercial production, insulin is made in bacteria or yeast by protein recombinant technology. The focus of this research is evaluating another resource and producing of recombinant insulin protein in as strawberry as this plant has high potential in production of pharmaceutical proteins. Strawberry is a suitable bioreactor for production of recombinant proteins especially edible vaccines. In this research, human pro-insulin gene was cloned in pCAMBIA1304 vector under CaMV35S promoter and NOS terminator. Agrobacterium tumefaciens LBA4404, AGL1, EHA105, EHA101, C58, C58 (pGV2260) and C58 (pGV3101) strains were used for transformation of pro-insulin gene into strawberry cv. Camarosa, Selva, Sarian Hybrid, Pajaro, Paros, Gaviota, Alpine. Additionally, Agrobacterium rhizogenes K599, R1000, A4 and MSU440 strains were utilized for gene transformation into hairy roots. PCR analysis indicated the presence of transformed human pro-insulin gene in the strawberry and hairy roots. Also, its transcription was confirmed using RT-PCR. Furthermore, the analysis of plants, fruits and hairy roots at the level of proteins using dot blot, ELISA, SDS-PAGE and ECL tests re-confirmed the expression of this protein in the transgenic plants as well as hairy roots. Protein purification of human pro-insulin from transgenic tissues was performed using affinity chromatography. Finally, the bioassay of recombinant pro-insulin was performed. The analysis of second generations of transgenic plants (T1) at DNA and protein levels was also performed as a complementary experiment. This study opens a new avenue in molecular farming of human pro-insulin through its mass production in roots and shoots of strawberry.

  9. Interleukin-1β mediates macrophage-induced impairment of insulin signaling in human primary adipocytes

    PubMed Central

    Gao, Dan; Madi, Mohamed; Ding, Cherlyn; Fok, Matthew; Steele, Thomas; Ford, Christopher; Hunter, Leif

    2014-01-01

    Adipose tissue expansion during obesity is associated with increased macrophage infiltration. Macrophage-derived factors significantly alter adipocyte function, inducing inflammatory responses and decreasing insulin sensitivity. Identification of the major factors that mediate detrimental effects of macrophages on adipocytes may offer potential therapeutic targets. IL-1β, a proinflammatory cytokine, is suggested to be involved in the development of insulin resistance. This study investigated the role of IL-1β in macrophage-adipocyte cross-talk, which affects insulin signaling in human adipocytes. Using macrophage-conditioned (MC) medium and human primary adipocytes, we examined the effect of IL-1β antagonism on the insulin signaling pathway. Gene expression profile and protein abundance of insulin signaling molecules were determined, as was the production of proinflammatory cytokine/chemokines. We also examined whether IL-1β mediates MC medium-induced alteration in adipocyte lipid storage. MC medium and IL-1β significantly reduced gene expression and protein abundance of insulin signaling molecules, including insulin receptor substrate-1, phosphoinositide 3-kinase p85α, and glucose transporter 4 and phosphorylation of Akt. In contrast, the expression and release of the proinflammatory markers, including IL-6, IL-8, monocyte chemotactic protein-1, and chemokine (C-C motif) ligand 5 by adipocytes were markedly increased. These changes were significantly reduced by blocking IL-1β activity, its receptor binding, or its production by macrophages. MC medium-inhibited expression of the adipogenic factors and -stimulated lipolysis was also blunted with IL-1β neutralization. We conclude that IL-1β mediates, at least in part, the effect of macrophages on insulin signaling and proinflammatory response in human adipocytes. Blocking IL-1β could be beneficial for preventing obesity-associated insulin resistance and inflammation in human adipose tissue. PMID:24918199

  10. Glucose responsive insulin production from human embryonic germ (EG) cell derivatives

    SciTech Connect

    Clark, Gregory O.; Yochem, Robert L.; Axelman, Joyce; Sheets, Timothy P.; Kaczorowski, David J.; Shamblott, Michael J. . E-mail: mshambl1@jhmi.edu

    2007-05-11

    Type 1 diabetes mellitus subjects millions to a daily burden of disease management, life threatening hypoglycemia and long-term complications such as retinopathy, nephropathy, heart disease, and stroke. Cell transplantation therapies providing a glucose-regulated supply of insulin have been implemented clinically, but are limited by safety, efficacy and supply considerations. Stem cells promise a plentiful and flexible source of cells for transplantation therapies. Here, we show that cells derived from human embryonic germ (EG) cells express markers of definitive endoderm, pancreatic and {beta}-cell development, glucose sensing, and production of mature insulin. These cells integrate functions necessary for glucose responsive regulation of preproinsulin mRNA and expression of insulin C-peptide in vitro. Following transplantation into mice, cells become insulin and C-peptide immunoreactive and produce plasma C-peptide in response to glucose. These findings suggest that EG cell derivatives may eventually serve as a source of insulin producing cells for the treatment of diabetes.

  11. GPR54 peptide agonists stimulate insulin secretion from murine, porcine and human islets.

    PubMed

    Bowe, James E; Foot, Victoria L; Amiel, Stephanie A; Huang, Gao Cai; Lamb, Morgan W; Lakey, Jonathan; Jones, Peter M; Persaud, Shanta J

    2012-01-01

    This study was designed to determine the effects of 10 and 13 amino acid forms of kisspeptin on dynamic insulin secretion from mammalian islets since it is not clear from published data whether the shorter peptide is stimulatory while the longer peptide inhibits insulin release. Insulin secretion was measured by radioimmunoassay following perifusion of human, pig, rat and mouse isolated islets with kisspeptin-10 or kisspeptin-13 in the presence of 20 mM glucose. Both peptides stimulated rapid, reversible potentiation of glucose-stimulated insulin secretion from islets of all species tested. These data indicate that both kisspeptin-10 and kisspeptin-13, which is an extension of kisspeptin-10 by three amino acids, act directly at islet β-cells of various species to potentiate insulin secretion, and suggest that inhibitory effects reported in earlier studies may reflect differences in experimental protocols.

  12. Expression of a mutant IRS inhibits metabolic and mitogenic signalling of insulin in human adipocytes.

    PubMed

    Stenkula, Karin G; Said, Lilian; Karlsson, Margareta; Thorn, Hans; Kjølhede, Preben; Gustavsson, Johanna; Söderström, Mats; Strålfors, Peter; Nystrom, Fredrik H

    2004-06-30

    Adipose tissue is a primary target of insulin, but knowledge about insulin signalling in human adipocytes is limited. We developed an electroporation technique for transfection of primary human adipocytes with a transfection efficiency of 15% +/- 5 (mean +/- S.D.). Human adipocytes were co-transfected with a mutant of IRS-3 (all four potential PI3-kinase binding motifs mutated: IRS-3F4) and HA-tagged protein kinase B (HA-PKB/Akt). HA-PKB/Akt was immunoprecipitated from cell lysates with anti-HA antibodies, resolved with SDS-PAGE, and immunoblotted with phospho-specific antibodies. We found that IRS-3F4 blocked insulin stimulation of HA-PKB/Akt phosphorylation and in further analyses also translocation of recombinant HA-tagged glucose transporter to the plasma membrane. IRS-3F4 also blocked insulin-induced activation of the transcription factor Elk-1. Our results demonstrate the critical importance of IRS for metabolic as well as mitogenic signalling by insulin. This method for transfection of primary human adipocytes will be useful for studying insulin signalling in human adipocytes with molecular biological techniques.

  13. Salsalate Attenuates Free Fatty Acid–Induced Microvascular and Metabolic Insulin Resistance in Humans

    PubMed Central

    Chai, Weidong; Liu, Jia; Jahn, Linda A.; Fowler, Dale E.; Barrett, Eugene J.; Liu, Zhenqi

    2011-01-01

    OBJECTIVE Insulin recruits muscle microvasculature, thereby increasing endothelial exchange surface area. Free fatty acids (FFAs) cause insulin resistance by activating inhibitor of κB kinase β. Elevating plasma FFAs impairs insulin’s microvascular and metabolic actions in vivo. Whether salsalate, an anti-inflammatory agent, prevents FFA-induced microvascular and/or metabolic insulin resistance in humans is unknown. RESEARCH DESIGN AND METHODS Eleven healthy, young adults were studied three times in random order. After an overnight fast, on two occasions each subject received a 5-h systemic infusion of Intralipid ± salsalate pretreatment (50 mg/kg/day for 4 days). On the third occasion, saline replaced Intralipid. A 1 mU/kg/min euglycemic insulin clamp was superimposed over the last 2-h of each study. Skeletal and cardiac muscle microvascular blood volume (MBV), microvascular flow velocity (MFV), and microvascular blood flow (MBF) were determined before and after insulin infusion. Whole body glucose disposal rates were calculated from glucose infusion rates. RESULTS Insulin significantly increased skeletal and cardiac muscle MBV and MBF without affecting MFV. Lipid infusion abolished insulin-mediated microvascular recruitment in both skeletal and cardiac muscle and lowered insulin-stimulated whole body glucose disposal (P < 0.001). Salsalate treatment rescued insulin’s actions to recruit muscle microvasculature and improved insulin-stimulated whole body glucose disposal in the presence of high plasma FFAs. CONCLUSIONS High plasma concentrations of FFAs cause both microvascular and metabolic insulin resistance, which can be prevented or attenuated by salsalate treatment. Our data suggest that treatments aimed at inhibition of inflammatory response might help alleviate vascular insulin resistance and improve metabolic control in patients with diabetes. PMID:21617098

  14. Predictors of Whole-Body Insulin Sensitivity Across Ages and Adiposity in Adult Humans

    PubMed Central

    Lalia, Antigoni Z.; Dasari, Surendra; Johnson, Matthew L.; Robinson, Matthew M.; Konopka, Adam R.; Distelmaier, Klaus; Port, John D.; Glavin, Maria T.; Esponda, Raul Ruiz; Nair, K. Sreekumaran

    2016-01-01

    Context: Numerous factors are purported to influence insulin sensitivity including age, adiposity, mitochondrial function, and physical fitness. Univariate associations cannot address the complexity of insulin resistance or the interrelationship among potential determinants. Objective: The objective of the study was to identify significant independent predictors of insulin sensitivity across a range of age and adiposity in humans. Design, Setting, and Participants: Peripheral and hepatic insulin sensitivity were measured by two stage hyperinsulinemic-euglycemic clamps in 116 men and women (aged 19–78 y). Insulin-stimulated glucose disposal, the suppression of endogenous glucose production during hyperinsulinemia, and homeostatic model assessment of insulin resistance were tested for associations with 11 potential predictors. Abdominal subcutaneous fat, visceral fat (AFVISC), intrahepatic lipid, and intramyocellular lipid (IMCL) were quantified by magnetic resonance imaging and spectroscopy. Skeletal muscle mitochondrial respiratory capacity (state 3), coupling efficiency, and reactive oxygen species production were evaluated from muscle biopsies. Aerobic fitness was measured from whole-body maximum oxygen uptake (VO2 peak), and metabolic flexibility was determined using indirect calorimetry. Results: Multiple regression analysis revealed that AFVISC (P < .0001) and intrahepatic lipid (P = .002) were independent negative predictors of peripheral insulin sensitivity, whereas VO2 peak (P = .0007) and IMCL (P = .023) were positive predictors. Mitochondrial capacity and efficiency were not independent determinants of peripheral insulin sensitivity. The suppression of endogenous glucose production during hyperinsulinemia model of hepatic insulin sensitivity revealed percentage fat (P < .0001) and AFVISC (P = .001) as significant negative predictors. Modeling homeostatic model assessment of insulin resistance identified AFVISC (P < .0001), VO2 peak (P = .001), and IMCL

  15. An update on the treatment of type 1 and type 2 diabetes mellitus: focus on insulin detemir, a long-acting human insulin analog.

    PubMed

    Raslova, Katarina

    2010-06-01

    Basal insulin analogs are used to minimize unpredictable processes of NPH insulin. Modification of the human insulin molecule results in a slower distribution to peripheral target tissues, a longer duration of action with stable concentrations and thus a lower rate of hypoglycemia. Insulin detemir is a basal insulin analog that provides effective therapeutic options for patients with type 1 and type 2 diabetes. For glycemic control, no significant differences were found in HbA1c levels compared with NPH and insulin glargine. It is comparable with insulin glargine in significantly reducing rates of all types of hypoglycemia. Clinical studies have demonstrated that detemir is responsible for significantly lower within-subject variability and no or less weight gain than NPH insulin and glargine. Recent pharmacodynamic studies have shown that detemir can be used once daily in many patients with diabetes. Together with patient-friendly injection devices and dose adjustments, it provides a treatment option with the potential to lower the key barriers of adherence to insulin therapy in type 2 diabetes. Recent guidelines for treatment of type 2 diabetes suggest starting intensive therapy of hyperglycemia at an early stage of diabetes and recommend therapeutic options that provide the possibility of reaching HbA1c goals individually, with a low risk of hypoglycemia or other adverse effects of treatment. The properties of insulin detemir match these requirements.

  16. Glucose-Stimulated Insulin Release: Parallel Perifusion Studies of Free and Hydrogel Encapsulated Human Pancreatic Islets.

    PubMed

    Buchwald, Peter; Tamayo-Garcia, Alejandro; Manzoli, Vita; Tomei, Alice A; Stabler, Cherie L

    2017-09-02

    To explore the effects immune-isolating encapsulation has on the insulin secretion of pancreatic islets and to improve our ability to quantitatively describe the glucose-stimulated insulin release (GSIR) of pancreatic islets, we conducted dynamic perifusion experiments with isolated human islets. Free (unencapsulated) and hydrogel encapsulated islets were perifused, in parallel, using an automated multi-channel system that allows sample collection with high temporal resolution. Results indicated that free human islets secrete less insulin per unit mass or islet equivalent (IEQ) than murine islets and with a less pronounced first-phase peak. While small microcapsules (d ≈ 700 µm) caused only a slightly delayed and blunted first-phase insulin response compared to unencapsulated islets, larger capsules (d ≈ 1800 µm) completely blunted the first-phase peak and decreased the total amount of insulin released. Experimentally obtained insulin time-profiles were fitted with our complex insulin secretion computational model. This allowed further fine-tuning of the hormone-release parameters of this model, which was implemented in COMSOL Multiphysics to couple hormone secretion and nutrient consumption kinetics with diffusive and convective transport. The results of these GSIR experiments, which were also supported by computational modeling, indicate that larger capsules unavoidably lead to dampening of the first-phase insulin response and to a sustained-release type insulin secretion that can only slowly respond to changes in glucose concentration. Bioartificial pancreas type devices can provide long-term and physiologically desirable solutions only if immunoisolation and biocompatibility considerations are integrated with optimized nutrient diffusion and insulin release characteristics by design. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  17. The Biosulin equivalence in standard therapy (BEST) study - a multicentre, open-label, non-randomised, interventional, observational study in subjects using Biosulin 30/70 for the treatment of insulin-dependent type 1 and type 2 diabetes mellitus.

    PubMed

    Segal, D; Tupy, D; Distiller, L

    2013-04-02

    The need for more cost-effective insulin therapy is critical in reducing the burden on patients and health systems. Biosimilar insulins have the potential to dramatically lower healthcare costs by delivering insulin with a similar anti-glycaemic effect and adverse reaction profile. The purpose of this study was to confirm equivalence in glycaemic outcomes and side-effect profiles between Biosulin 30/70 and other human premixed insulin preparations on the South African market in a clinical practice setting. Subjects in this interventional, observational, multicentre, open-label, prospective study were switched from their existing human premix insulin (Actraphane, Humulin 30/70 or Insuman) to the study insulin Biosulin 30/70. The primary endpoint was the change in HbA1c from baseline to 6 months. Seventy-seven adult patients with type 1(n=18) or type 2 (n=59) diabetes were enrolled. The baseline HbA1c in the overall cohort was 7.9%, 8.0% at 3 months (p=0.50) and 7.6% at 6 months (p=0.14).There was a small increase in the total daily dose of insulin used in both the type 1 and type 2 cohort, from 0.62 to 0.65 units/kg/day (p=0.0004). There was no significant difference in weight in the study subjects during the 6-month period on Biosulin 30/70 (p=0.67). Biosulin 30/70 achieved at least equivalent glycaemic control to existing human premix insulins, with no reported new or severe adverse events. Increased use of biosimilar insulins has the potential for significant cost savings.

  18. Hypoglycemic activity and stability enhancement of human insulin-tat mixture loaded in elastic anionic niosomes.

    PubMed

    Manosroi, Aranya; Tangjai, Theeraphong; Sutthiwanjampa, Chanutchamon; Manosroi, Worapaka; Werner, Rolf G; Götz, Friedrich; Sainakham, Mathukorn; Manosroi, Jiradej

    2016-10-01

    This study aimed to investigate the synergistic effect of trans-activator of transcription (Tat) and niosomes for the improvement of hypoglycemic activity of orally delivered human insulin. The elastic anionic niosomes composing of Tween 61/cholesterol/dicetyl phosphate/sodium cholate at 1:1:0.05:0.02 molar ratio loaded with insulin-Tat mixture (1:3 molar ratio) was prepared. Deformability of the elastic anionic niosomes decreased after loaded with the mixture of 1.35 times. For the in vitro release, the insulin (T10 = 4 h) loaded in the elastic anionic niosomes indicated the slower release rate than insulin in the mixture (T10 = 3 h) loaded in niosomes. At room temperature (30 ± 2 °C), the mixture loaded in elastic anionic niosomes was more chemical stable than the free mixture of 1.3, 1.4 and 1.7 times after stored for 4, 8 and 12 weeks, respectively. Oral administration in the alloxan-induced diabetic mice of the mixture loaded in elastic anionic niosomes with the insulin doses at 25, 50 and 100 IU/kg body weight indicated significant hypoglycemic activity with the percentage fasting blood glucose reduction of 1.95, 2.10 and 2.10 folds of the subcutaneous insulin injection at 12 h, respectively. This study has demonstrated the synergistic benefits of Tat and elastic anionic niosomes for improving the hypoglycemic activity of the orally delivered human insulin as well as the stability enhancement of human insulin when stored at high temperature. The results from this study can be further developed as an effective oral insulin delivery.

  19. Genetic Defects in Human Pericentrin Are Associated With Severe Insulin Resistance and Diabetes

    PubMed Central

    Huang-Doran, Isabel; Bicknell, Louise S.; Finucane, Francis M.; Rocha, Nuno; Porter, Keith M.; Tung, Y.C. Loraine; Szekeres, Ferenc; Krook, Anna; Nolan, John J.; O’Driscoll, Mark; Bober, Michael; O’Rahilly, Stephen; Jackson, Andrew P.; Semple, Robert K.

    2011-01-01

    OBJECTIVE Genetic defects in human pericentrin (PCNT), encoding the centrosomal protein pericentrin, cause a form of osteodysplastic primordial dwarfism that is sometimes reported to be associated with diabetes. We thus set out to determine the prevalence of diabetes and insulin resistance among patients with PCNT defects and examined the effects of pericentrin depletion on insulin action using 3T3-L1 adipocytes as a model system. RESEARCH DESIGN AND METHODS A cross-sectional metabolic assessment of 21 patients with PCNT mutations was undertaken. Pericentrin expression in human tissues was profiled using quantitative real-time PCR. The effect of pericentrin knockdown on insulin action and adipogenesis in 3T3-L1 adipocytes was determined using Oil red O staining, gene-expression analysis, immunoblotting, and glucose uptake assays. Pericentrin expression and localization also was determined in skeletal muscle. RESULTS Of 21 patients with genetic defects in PCNT, 18 had insulin resistance, which was severe in the majority of subjects. Ten subjects had confirmed diabetes (mean age of onset 15 years [range 5–28]), and 13 had metabolic dyslipidemia. All patients without insulin resistance were younger than 4 years old. Knockdown of pericentrin in adipocytes had no effect on proximal insulin signaling but produced a twofold impairment in insulin-stimulated glucose uptake, approximately commensurate with an associated defect in cell proliferation and adipogenesis. Pericentrin was highly expressed in human skeletal muscle, where it showed a perinuclear distribution. CONCLUSIONS Severe insulin resistance and premature diabetes are common features of PCNT deficiency but are not congenital. Partial failure of adipocyte differentiation may contribute to this, but pericentrin deficiency does not impair proximal insulin action in adipocytes. PMID:21270239

  20. ATF-2 stimulates the human insulin promoter through the conserved CRE2 sequence.

    PubMed

    Hay, Colin W; Ferguson, Laura A; Docherty, Kevin

    2007-02-01

    The insulin promoter contains a number of dissimilar cis-acting regulatory elements that bind a range of tissue specific and ubiquitous transcription factors. Of the regulatory elements within the insulin promoter, the cyclic AMP responsive element (CRE) binds by far the most diverse array of transcription factors. Rodent insulin promoters have a single CRE site, whereas there are four CREs within the human insulin gene, of which CRE2 is the only one conserved between species. The aim of this study was to characterise the human CRE2 site and to investigate the effects of the two principal CRE-associated transcription factors; CREB-1 and ATF-2. Co-transfection of INS-1 pancreatic beta-cells with promoter constructs containing the human insulin gene promoter placed upstream of the firefly luciferase reporter gene and expression plasmids for ATF-2 or CREB-1 showed that ATF-2 stimulated transcriptional activity while CREB-1 elicited an inhibitory effect. Mutagenesis of CRE2 diminished the effect of ATF-2 but not that of CREB-1. ATF-2 was shown to bind to the CRE2 site by electrophoretic mobility shift assay and by chromatin immunoprecipitation, while siRNA mediated knockdown of ATF-2 diminished the stimulatory effects of cAMP related signalling on promoter activity. These results suggest that ATF-2 may be a key regulator of the human insulin promoter possibly stimulating activity in response to extracellular signals.

  1. Comparison of medication adherence in diabetes mellitus patients on human versus analogue insulins.

    PubMed

    Machado-Alba, Jorge Enrique; Medina-Morales, Diego Alejandro; Echeverri-Cataño, Luis Felipe

    2017-02-01

    Objetive: This study evaluated the results of treatment adherence scales in two cohorts of patients with diabetes mellitus treated either with human or analogue insulins. A cohort study was conducted in diabetes mellitus patients older than 18 that were being treated with human or analogue insulins. Two instruments were applied to each patient [medication possession ratio, Morisky-Green test] to evaluate treatment adherence. A total of 238 patients, were included. The majority (69.4%) of the subjects had human insulin and 30.6% had insulin analogue prescriptions. Out of the total, 163 (68.5%) cases were classified as adherent to therapy, according to the type of insulin, as follows: 69.9% for conventional and 65.3% for analogues; without differences between the groups (CI95%:0.450-1.458). The adherence to treatment was more probable in patients with elementary-secondary education (OR:2.341; CI95%:1.199-4.568) and less probable for those in the age range of 31-45 years (OR:0.427; CI95%:0.187-0.971). The results of this study show that there are no significant statistical differences in adherence when comparing human with analogue insulin therapy. Strategies to improve treatment adherence are particularly important since they improve the clinical results.

  2. Premixed Parenteral Nutrition Solution Use in Children

    PubMed Central

    Crill, Catherine M.

    2015-01-01

    OBJECTIVES: In response to national drug shortages, our institution established criteria for the use of commercial premixed parenteral nutrition (PN) solutions in select pediatric patients. Although these solutions have been marketed for use in children, there are no data in this patient population. The objective of this study was to review our use of commercial premixed PN solutions in children. METHODS: This was a retrospective review of patients ≤18 years of age who received a premixed PN solution from October 2010 to April 2012. All premixed PN courses were assessed for incidence of premixed PN discontinuation due to laboratory abnormalities. Estimated goal and actual protein and total caloric intake were evaluated for premixed PN courses that were continued for >48 hours. RESULTS: Sixty-nine patients received 74 courses of premixed PN solutions for a mean duration of 5.6 ± 6.2 (range, 1–31) days. Fifteen courses (20%) required discontinuation of premixed PN as a result of mild laboratory abnormalities. No changes in clinical status were observed in patients and all abnormalities were corrected after switching to individualized PN. In patients receiving PN for >48 hours, premixed PN solutions provided goal protein in 48/49 (98%) courses and goal calories in 33/49 (67%) courses. CONCLUSIONS: Premixed PN solutions were used in a wide range of pediatric patients and provide a potential option for PN support in pediatric patients when drug shortages limit PN product supply. Close monitoring for electrolyte abnormalities and protein and caloric intake is recommended when using premixed PN solutions in children. PMID:26472952

  3. Insulin Resistance, Ceramide Accumulation, and Endoplasmic Reticulum Stress in Human Chronic Alcohol-Related Liver Disease

    PubMed Central

    Longato, Lisa; Ripp, Kelsey; Setshedi, Mashiko; Dostalek, Miroslav; Akhlaghi, Fatemeh; Branda, Mark; Wands, Jack R.; de la Monte, Suzanne M.

    2012-01-01

    Background. Chronic alcohol-related liver disease (ALD) is mediated by insulin resistance, mitochondrial dysfunction, inflammation, oxidative stress, and DNA damage. Recent studies suggest that dysregulated lipid metabolism with accumulation of ceramides, together with ER stress potentiate hepatic insulin resistance and may cause steatohepatitis to progress. Objective. We examined the degree to which hepatic insulin resistance in advanced human ALD is correlated with ER stress, dysregulated lipid metabolism, and ceramide accumulation. Methods. We assessed the integrity of insulin signaling through the Akt pathway and measured proceramide and ER stress gene expression, ER stress signaling proteins, and ceramide profiles in liver tissue. Results. Chronic ALD was associated with increased expression of insulin, IGF-1, and IGF-2 receptors, impaired signaling through IGF-1R and IRS1, increased expression of multiple proceramide and ER stress genes and proteins, and higher levels of the C14, C16, C18, and C20 ceramide species relative to control. Conclusions. In human chronic ALD, persistent hepatic insulin resistance is associated with dysregulated lipid metabolism, ceramide accumulation, and striking upregulation of multiple ER stress signaling molecules. Given the role of ceramides as mediators of ER stress and insulin resistance, treatment with ceramide enzyme inhibitors may help reverse or halt progression of chronic ALD. PMID:22577490

  4. Integrating insulin into single-step culture medium regulates human embryo development in vitro.

    PubMed

    Fawzy, Mohamed; Sabry, Mohamed; Nour, Mohamed; Abdelrahman, Mohamed Y; Roshdy, Eman; Magdi, Yasmin; Abdelghafar, Hazem

    2017-02-01

    To evaluate the effect of supplementing single-step embryo culture medium with insulin on human embryo development. Comparative study. Two private centers. The study involved a sibling oocyte split of 5,142 retrieved oocytes from 360 patients. Sibling oocytes split after intracytoplasmic sperm injection for culture from day 0 through day 5 or 6 in insulin-supplemented or control medium. Women were split to receive their embryos from insulin-supplemented or control medium. Clinical pregnancy rate. There were significantly higher rates of clinical, ongoing, and twin pregnancies in the insulin-supplemented arm than in the control arm. On day 3, embryo quality and compaction were higher in insulin-supplemented medium. On day 5, insulin supplementation showed higher rates of blastocyst formation, quality, and cryopreservation. Insulin supplementation of single-step embryo culture medium from day 0 through day 5 or 6 improved clinical pregnancy rate and human embryo development. However, these findings need further confirmation through a multicenter randomized controlled trial that may include other patient populations and different culture media. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  5. Impaired tethering and fusion of GLUT4 vesicles in insulin-resistant human adipose cells.

    PubMed

    Lizunov, Vladimir A; Lee, Jo-Ping; Skarulis, Monica C; Zimmerberg, Joshua; Cushman, Samuel W; Stenkula, Karin G

    2013-09-01

    Systemic glucose homeostasis is profoundly influenced by adipose cell function. Here we investigated GLUT4 dynamics in living adipose cells from human subjects with varying BMI and insulin sensitivity index (Si) values. Cells were transfected with hemagglutinin (HA)-GLUT4-green fluorescent protein (GFP)/mCherry (red fluorescence), and were imaged live using total internal reflection fluorescence and confocal microscopy. HA-GLUT4-GFP redistribution to the plasma membrane (PM) was quantified by surface-exposed HA epitope. In the basal state, GLUT4 storage vesicle (GSV) trafficking to and fusion with the PM were invariant with donor subject Si, as was total cell-surface GLUT4. In cells from insulin-sensitive subjects, insulin augmented GSV tethering and fusion approximately threefold, resulting in a corresponding increase in total PM GLUT4. However, with decreasing Si, these effects diminished progressively. All insulin-induced effects on GLUT4 redistribution and trafficking correlated strongly with Si and only weakly with BMI. Thus, while basal GLUT4 dynamics and total cell-surface GLUT4 are intact in human adipose cells, independent of donor Si, cells from insulin-resistant donors show markedly impaired GSV tethering and fusion responses to insulin, even after overnight culture. This altered insulin responsiveness is consistent with the hypothesis that adipose cellular dysfunction is a primary contributor to systemic metabolic dysfunction.

  6. Fibroblast Growth Factor 21 Improves Insulin Sensitivity and Synergizes with Insulin in Human Adipose Stem Cell-Derived (hASC) Adipocytes

    PubMed Central

    Lee, Darwin V.; Li, Dongmei; Yan, Qingyun; Zhu, Yimin; Goodwin, Bryan; Calle, Roberto; Brenner, Martin B.; Talukdar, Saswata

    2014-01-01

    Fibroblast growth factor 21 (FGF21) has evolved as a major metabolic regulator, the pharmacological administration of which causes weight loss, insulin sensitivity and glucose control in rodents and humans. To understand the molecular mechanisms by which FGF21 exerts its metabolic effects, we developed a human in vitro model of adipocytes to examine crosstalk between FGF21 and insulin signaling. Human adipose stem cell-derived (hASC) adipocytes were acutely treated with FGF21 alone, insulin alone, or in combination. Insulin signaling under these conditions was assessed by measuring tyrosine phosphorylation of insulin receptor (InsR), insulin receptor substrate-1 (IRS-1), and serine 473 phosphorylation of Akt, followed by a functional assay using 14C-2-deoxyglucose [14C]-2DG to measure glucose uptake in these cells. FGF21 alone caused a modest increase of glucose uptake, but treatment with FGF21 in combination with insulin had a synergistic effect on glucose uptake in these cells. The presence of FGF21 also effectively lowered the insulin concentration required to achieve the same level of glucose uptake compared to the absence of FGF21 by 10-fold. This acute effect of FGF21 on insulin signaling was not due to IR, IGF-1R, or IRS-1 activation. Moreover, we observed a substantial increase in basal S473-Akt phosphorylation by FGF21 alone, in contrast to the minimal shift in basal glucose uptake. Taken together, our data demonstrate that acute co-treatment of hASC-adipocytes with FGF21 and insulin can result in a synergistic improvement in glucose uptake. These effects were shown to occur at or downstream of Akt, or separate from the canonical insulin signaling pathway. PMID:25365322

  7. The Novel Endocrine Disruptor Tolylfluanid Impairs Insulin Signaling in Primary Rodent and Human Adipocytes through a Reduction in Insulin Receptor Substrate-1 Levels

    PubMed Central

    Sargis, Robert M.; Neel, Brian A.; Brock, Clifton O.; Lin, Yuxi; Hickey, Allison T.; Carlton, Daniel A.; Brady, Matthew J.

    2012-01-01

    Emerging data suggest that environmental endocrine disrupting chemicals (EDCs) may contribute to the pathophysiology of obesity and diabetes. In prior work, the phenylsulfamide fungicide tolylfluanid (TF) was shown to augment adipocyte differentiation, yet its effects on mature adipocyte metabolism remain unknown. Because of the central role of adipose tissue in global energy regulation, the present study tested the hypothesis that TF modulates insulin action in primary rodent and human adipocytes. Alterations in insulin signaling in primary mammalian adipocytes were determined by the phosphorylation of Akt, a critical insulin signaling intermediate. Treatment of primary murine adipose tissue in vitro with 100 nM TF for 48 h markedly attenuated acute insulin-stimulated Akt phosphorylation in a strain- and species-independent fashion. Perigonadal, perirenal, and mesenteric fat were all sensitive to TF-induced insulin resistance. A similar TF-induced reduction in insulin-stimulated Akt phosphorylation was observed in primary human subcutaneous adipose tissue. TF-treatment led to a potent and specific reduction in insulin receptor substrate-1 (IRS-1) mRNA and protein levels, a key upstream mediator of insulin’s diverse metabolic effects. In contrast, insulin receptor-β, phosphatidylinositol 3-kinase, and Akt expression were unchanged, indicating a specific abrogation of insulin signaling. Additionally, TF-treated adipocytes exhibited altered endocrine function with a reduction in both basal and insulin-stimulated leptin secretion. These studies demonstrate that TF induces cellular insulin resistance in primary murine and human adipocytes through a reduction of IRS-1 expression and protein stability, raising concern about the potential for this fungicide to disrupt metabolism and thereby contribute to the pathogenesis of diabetes. PMID:22387882

  8. Separation of human, bovine, and porcine insulins, three very closely related proteins, by micellar electrokinetic chromatography.

    PubMed

    Lamalle, Caroline; Roland, Diane; Crommen, Jacques; Servais, Anne-Catherine; Fillet, Marianne

    2015-10-01

    Human, bovine, and porcine insulins are small proteins with very closely related amino acid sequences, which makes their separation challenging. In this study, we took advantage of the high-resolution power of CE, and more particularly of micellar electrokinetic chromatography, to separate those biomolecules. Among several surfactants, perfluorooctanoic acid ammonium salt was selected. Then, using a design of experiments approach, the optimal BGE composition was found to consist of 50 mM ammonium acetate pH 9.0, 65 mM perfluorooctanoic acid ammonium salt, and 4% MeOH. The three insulins could be separated within 12 min with a satisfactory resolution. This method could be useful to detect possible counterfeit pharmaceutical formulations. Indeed, it would be easy to determine if human insulin was replaced by bovine or porcine insulin.

  9. Mechanisms of insulin resistance after insulin-induced hypoglycemia in humans: the role of lipolysis.

    PubMed

    Lucidi, Paola; Rossetti, Paolo; Porcellati, Francesca; Pampanelli, Simone; Candeloro, Paola; Andreoli, Anna Marinelli; Perriello, Gabriele; Bolli, Geremia B; Fanelli, Carmine G

    2010-06-01

    Changes in glucose metabolism occurring during counterregulation are, in part, mediated by increased plasma free fatty acids (FFAs), as a result of hypoglycemia-activated lipolysis. However, it is not known whether FFA plays a role in the development of posthypoglycemic insulin resistance as well. We conducted a series of studies in eight healthy volunteers using acipimox, an inhibitor of lipolysis. Insulin action was measured during a 2-h hyperinsulinemic-euglycemic clamp (plasma glucose [PG] 5.1 mmo/l) from 5:00 p.m. to 7:00 p.m. or after a 3-h morning hyperinsulinemic-glucose clamp (from 10 a.m. to 1:00 p.m.), either euglycemic (study 1) or hypoglycemic (PG 3.2 mmol/l, studies 2-4), during which FFA levels were allowed to increase (study 2), were suppressed by acipimox (study 3), or were replaced by infusing lipids (study 4). [6,6-(2)H(2)]-Glucose was infused to measure glucose fluxes. Plasma adrenaline, norepinephrine, growth hormone, and cortisol levels were unchanged (P > 0.2). Glucose infusion rates (GIRs) during the euglycemic clamp were reduced by morning hypoglycemia in study 2 versus study 1 (16.8 +/- 2.3 vs. 34.1 +/- 2.2 micromol/kg/min, respectively, P < 0.001). The effect was largely removed by blockade of lipolysis during hypoglycemia in study 3 (28.9 +/- 2.6 micromol/kg/min, P > 0.2 vs. study 1) and largely reproduced by replacement of FFA in study 4 (22.3 +/- 2.8 micromol/kg/min, P < 0.03 vs. study 1). Compared with study 2, blockade of lipolysis in study 3 decreased endogenous glucose production (2 +/- 0.3 vs. 0.85 +/- 0.1 micromol/kg/min, P < 0.05) and increased glucose utilization (16.9 +/- 1.85 vs. 28.5 +/- 2.7 micromol/kg/min, P < 0.05). In study 4, GIR fell by approximately 23% (22.3 +/- 2.8 micromol/kg/min, vs. study 3, P = 0.058), indicating a role of acipimox per se on insulin action. Lipolysis induced by hypoglycemia counterregulation largely mediates posthypoglycemic insulin resistance in healthy subjects, with an estimated overall

  10. Mechanisms of Insulin Resistance After Insulin-Induced Hypoglycemia in Humans: The Role of Lipolysis

    PubMed Central

    Lucidi, Paola; Rossetti, Paolo; Porcellati, Francesca; Pampanelli, Simone; Candeloro, Paola; Andreoli, Anna Marinelli; Perriello, Gabriele; Bolli, Geremia B.; Fanelli, Carmine G.

    2010-01-01

    OBJECTIVE Changes in glucose metabolism occurring during counterregulation are, in part, mediated by increased plasma free fatty acids (FFAs), as a result of hypoglycemia-activated lipolysis. However, it is not known whether FFA plays a role in the development of posthypoglycemic insulin resistance as well. RESEARCH DESIGN AND METHODS We conducted a series of studies in eight healthy volunteers using acipimox, an inhibitor of lipolysis. Insulin action was measured during a 2-h hyperinsulinemic-euglycemic clamp (plasma glucose [PG] 5.1 mmo/l) from 5:00 p.m. to 7:00 p.m. or after a 3-h morning hyperinsulinemic-glucose clamp (from 10 a.m. to 1:00 p.m.), either euglycemic (study 1) or hypoglycemic (PG 3.2 mmol/l, studies 2–4), during which FFA levels were allowed to increase (study 2), were suppressed by acipimox (study 3), or were replaced by infusing lipids (study 4). [6,6-2H2]-Glucose was infused to measure glucose fluxes. RESULTS Plasma adrenaline, norepinephrine, growth hormone, and cortisol levels were unchanged (P > 0.2). Glucose infusion rates (GIRs) during the euglycemic clamp were reduced by morning hypoglycemia in study 2 versus study 1 (16.8 ± 2.3 vs. 34.1 ± 2.2 μmol/kg/min, respectively, P < 0.001). The effect was largely removed by blockade of lipolysis during hypoglycemia in study 3 (28.9 ± 2.6 μmol/kg/min, P > 0.2 vs. study 1) and largely reproduced by replacement of FFA in study 4 (22.3 ± 2.8 μmol/kg/min, P < 0.03 vs. study 1). Compared with study 2, blockade of lipolysis in study 3 decreased endogenous glucose production (2 ± 0.3 vs. 0.85 ± 0.1 μmol/kg/min, P < 0.05) and increased glucose utilization (16.9 ± 1.85 vs. 28.5 ± 2.7 μmol/kg/min, P < 0.05). In study 4, GIR fell by ∼23% (22.3 ± 2.8 μmol/kg/min, vs. study 3, P = 0.058), indicating a role of acipimox per se on insulin action. CONCLUSION Lipolysis induced by hypoglycemia counterregulation largely mediates posthypoglycemic insulin resistance in healthy subjects, with an

  11. Prolonged fasting identifies skeletal muscle mitochondrial dysfunction as consequence rather than cause of human insulin resistance.

    PubMed

    Hoeks, Joris; van Herpen, Noud A; Mensink, Marco; Moonen-Kornips, Esther; van Beurden, Denis; Hesselink, Matthijs K C; Schrauwen, Patrick

    2010-09-01

    Type 2 diabetes and insulin resistance have been associated with mitochondrial dysfunction, but it is debated whether this is a primary factor in the pathogenesis of the disease. To test the concept that mitochondrial dysfunction is secondary to the development of insulin resistance, we employed the unique model of prolonged fasting in humans. Prolonged fasting is a physiologic condition in which muscular insulin resistance develops in the presence of increased free fatty acid (FFA) levels, increased fat oxidation and low glucose and insulin levels. It is therefore anticipated that skeletal muscle mitochondrial function is maintained to accommodate increased fat oxidation unless factors secondary to insulin resistance exert negative effects on mitochondrial function. While in a respiration chamber, twelve healthy males were subjected to a 60 h fast and a 60 h normal fed condition in a randomized crossover design. Afterward, insulin sensitivity was assessed using a hyperinsulinemic-euglycemic clamp, and mitochondrial function was quantified ex vivo in permeabilized muscle fibers using high-resolution respirometry. Indeed, FFA levels were increased approximately ninefold after 60 h of fasting in healthy male subjects, leading to elevated intramuscular lipid levels and decreased muscular insulin sensitivity. Despite an increase in whole-body fat oxidation, we observed an overall reduction in both coupled state 3 respiration and maximally uncoupled respiration in permeabilized skeletal muscle fibers, which could not be explained by changes in mitochondrial density. These findings confirm that the insulin-resistant state has secondary negative effects on mitochondrial function. Given the low insulin and glucose levels after prolonged fasting, hyperglycemia and insulin action per se can be excluded as underlying mechanisms, pointing toward elevated plasma FFA and/or intramuscular fat accumulation as possible causes for the observed reduction in mitochondrial capacity.

  12. Prolonged Fasting Identifies Skeletal Muscle Mitochondrial Dysfunction as Consequence Rather Than Cause of Human Insulin Resistance

    PubMed Central

    Hoeks, Joris; van Herpen, Noud A.; Mensink, Marco; Moonen-Kornips, Esther; van Beurden, Denis; Hesselink, Matthijs K.C.; Schrauwen, Patrick

    2010-01-01

    OBJECTIVE Type 2 diabetes and insulin resistance have been associated with mitochondrial dysfunction, but it is debated whether this is a primary factor in the pathogenesis of the disease. To test the concept that mitochondrial dysfunction is secondary to the development of insulin resistance, we employed the unique model of prolonged fasting in humans. Prolonged fasting is a physiologic condition in which muscular insulin resistance develops in the presence of increased free fatty acid (FFA) levels, increased fat oxidation and low glucose and insulin levels. It is therefore anticipated that skeletal muscle mitochondrial function is maintained to accommodate increased fat oxidation unless factors secondary to insulin resistance exert negative effects on mitochondrial function. RESEARCH DESIGN AND METHODS While in a respiration chamber, twelve healthy males were subjected to a 60 h fast and a 60 h normal fed condition in a randomized crossover design. Afterward, insulin sensitivity was assessed using a hyperinsulinemic-euglycemic clamp, and mitochondrial function was quantified ex vivo in permeabilized muscle fibers using high-resolution respirometry. RESULTS Indeed, FFA levels were increased approximately ninefold after 60 h of fasting in healthy male subjects, leading to elevated intramuscular lipid levels and decreased muscular insulin sensitivity. Despite an increase in whole-body fat oxidation, we observed an overall reduction in both coupled state 3 respiration and maximally uncoupled respiration in permeabilized skeletal muscle fibers, which could not be explained by changes in mitochondrial density. CONCLUSIONS These findings confirm that the insulin-resistant state has secondary negative effects on mitochondrial function. Given the low insulin and glucose levels after prolonged fasting, hyperglycemia and insulin action per se can be excluded as underlying mechanisms, pointing toward elevated plasma FFA and/or intramuscular fat accumulation as possible

  13. Gas turbine premixer with internal cooling

    DOEpatents

    York, William David; Johnson, Thomas Edward; Lacy, Benjamin Paul; Stevenson, Christian Xavier

    2012-12-18

    A system that includes a turbine fuel nozzle comprising an air-fuel premixer. The air-fuel premixed includes a swirl vane configured to swirl fuel and air in a downstream direction, wherein the swirl vane comprises an internal coolant path from a downstream end portion in an upstream direction through a substantial length of the swirl vane.

  14. Flashback resistant pre-mixer assembly

    DOEpatents

    Laster, Walter R [Oviedo, FL; Gambacorta, Domenico [Oviedo, FL

    2012-02-14

    A pre-mixer assembly associated with a fuel supply system for mixing of air and fuel upstream from a main combustion zone in a gas turbine engine. The pre-mixer assembly includes a swirler assembly disposed about a fuel injector of the fuel supply system and a pre-mixer transition member. The swirler assembly includes a forward end defining an air inlet and an opposed aft end. The pre-mixer transition member has a forward end affixed to the aft end of the swirler assembly and an opposed aft end defining an outlet of the pre-mixer assembly. The aft end of the pre-mixer transition member is spaced from a base plate such that a gap is formed between the aft end of the pre-mixer transition member and the base plate for permitting a flow of purge air therethrough to increase a velocity of the air/fuel mixture exiting the pre-mixer assembly.

  15. Plasma adiponectin concentration is associated with skeletal muscle insulin receptor tyrosine phosphorylation, and low plasma concentration precedes a decrease in whole-body insulin sensitivity in humans.

    PubMed

    Stefan, Norbert; Vozarova, Barbora; Funahashi, Tohru; Matsuzawa, Yuji; Weyer, Christian; Lindsay, Robert S; Youngren, Jack F; Havel, Peter J; Pratley, Richard E; Bogardus, Clifton; Tataranni, P Antonio

    2002-06-01

    Adiponectin, the most abundant adipose-specific protein, has been found to be negatively associated with degree of adiposity and positively associated with insulin sensitivity in Pima Indians and other populations. Moreover, adiponectin administration to rodents has been shown to increase insulin-induced tyrosine phosphorylation of the insulin receptor (IR) and also increase whole-body insulin sensitivity. To further characterize the relationship between plasma adiponectin concentration and insulin sensitivity in humans, we examined 1) the cross-sectional association between plasma adiponectin concentration and skeletal muscle IR tyrosine phosphorylation and 2) the prospective effect of plasma adiponectin concentration at baseline on change in insulin sensitivity. Fasting plasma adiponectin concentration, body composition (hydrodensitometry or dual energy X-ray absorptiometry), insulin sensitivity (insulin-stimulated glucose disposal, hyperinsulinemic clamp), and glucose tolerance (75-g oral glucose tolerance test) were measured in 55 Pima Indians (47 men and 8 women, aged 31 +/- 8 years, body fat 29 +/- 8% [mean +/- SD]; 50 with normal glucose tolerance, 3 with impaired glucose tolerance, and 2 with diabetes). Group 1 (19 subjects) underwent skeletal muscle biopsies for the measurement of basal and insulin-stimulated tyrosine phosphorylation of the IR (stimulated by 100 nmol/l insulin). The fold increase after insulin stimulation was calculated as the ratio between maximal and basal phosphorylation. Group 2 (38 subjects) had follow-up measurements of insulin-stimulated glucose disposal. Cross-sectionally, plasma adiponectin concentration was positively associated with insulin-stimulated glucose disposal (r = 0.58, P < 0.0001) and negatively associated with percent body fat (r = -0.62, P < 0.0001) in the whole group. In group 1 plasma adiponectin was negatively associated with the basal (r = -0.65, P = 0.003) and positively associated with the fold increase in IR

  16. Insulin Exhibits an Antiproliferative and Hypertrophic Effect in First Trimester Human Extravillous Trophoblasts.

    PubMed

    Silva, Cláudia; Nunes, Catarina; Correia-Branco, Ana; Araújo, João R; Martel, Fátima

    2017-04-01

    Our aim was to investigate the effect of high levels of glucose, insulin, leptin, and tumor necrosis factor alpha, biomarkers of diabetes in pregnancy, in the process of placentation, using as a cell model a first trimester extravillous human trophoblast cell line (HTR8/SVneo cells). Exposure of HTR8/SVneo cells for 24 hours to either glucose (20 mmol/L) or leptin (25-100 ng/mL) did not cause significant changes in cell proliferation and viability. Tumor necrosis factor alpha (24 hours; 10-100 ng/L) caused a small decrease (10%) in cell proliferation and an increase (9%) in cell viability; however, both effects disappeared when exposure time was increased. Insulin (24 hours; 1-10 nmol/L) caused a concentration- and time-dependent decrease (10%-20%) in cell proliferation; the effect of insulin (10 nmol/L) was more pronounced after a 48 hours exposure (35%). In contrast, exposure to insulin (10 nmol/L; 48 hours) showed no significant effect on cell viability, apoptosis, and migration capacity. Insulin appears to cause hypertrophy of HTR8/SVneo cells as it reduces the cell mitotic index while increasing the culture protein content. The antiproliferative effect of insulin seems to involve activation of mammalian target of rapamycin, phosphoinositide 3-kinase, and p38 mitogen-activated protein kinase. Finally, simvastatin and the polyphenol quercetin potentiated the antiproliferative effect of insulin; on the contrary, the polyphenol resveratrol, the polyunsaturated fatty acids eicosapentaenoic and docosahexaenoic acids, and folic acid were not able to change it. In conclusion, we show that insulin has an antiproliferative and hypertrophic effect on a first trimester extravillous human trophoblast cell line. So insulin might affect the process of placentation.

  17. Impairment of glucose-induced insulin secretion in human pancreatic islets transplanted to diabetic nude mice.

    PubMed

    Jansson, L; Eizirik, D L; Pipeleers, D G; Borg, L A; Hellerström, C; Andersson, A

    1995-08-01

    Hyperglycemia-induced beta-cell dysfunction may be an important component in the pathogenesis of non-insulin-dependent diabetes mellitus. However, most available data in this field were obtained from rodent islets. To investigate the relevance of this hypothesis for human beta-cells in vivo, human pancreatic islets were transplanted under the renal capsule of nude mice. Experimental groups were chosen so that grafted islets were exposed to either hyper- or normoglycemia or combinations of these for 4 or 6 wk. Grafts of normoglycemic recipients responded with an increased insulin release to a glucose stimulus during perfusion, whereas grafts of hyperglycemic recipients failed to respond to glucose. The insulin content of the grafts in the latter groups was only 10% of those observed in controls. Recipients initially hyperglycemic (4 wk), followed by 2 wk of normoglycemia regained a normal graft insulin content, but a decreased insulin response to glucose remained. No ultrastructural signs of beta-cell damage were observed, with the exception of increased glycogen deposits in animals hyperglycemic at the time of killing. It is concluded that prolonged exposure to a diabetic environment induces a long-term secretory defect in human beta-cells, which is not dependent on the size of the islet insulin stores.

  18. Impairment of glucose-induced insulin secretion in human pancreatic islets transplanted to diabetic nude mice.

    PubMed Central

    Jansson, L; Eizirik, D L; Pipeleers, D G; Borg, L A; Hellerström, C; Andersson, A

    1995-01-01

    Hyperglycemia-induced beta-cell dysfunction may be an important component in the pathogenesis of non-insulin-dependent diabetes mellitus. However, most available data in this field were obtained from rodent islets. To investigate the relevance of this hypothesis for human beta-cells in vivo, human pancreatic islets were transplanted under the renal capsule of nude mice. Experimental groups were chosen so that grafted islets were exposed to either hyper- or normoglycemia or combinations of these for 4 or 6 wk. Grafts of normoglycemic recipients responded with an increased insulin release to a glucose stimulus during perfusion, whereas grafts of hyperglycemic recipients failed to respond to glucose. The insulin content of the grafts in the latter groups was only 10% of those observed in controls. Recipients initially hyperglycemic (4 wk), followed by 2 wk of normoglycemia regained a normal graft insulin content, but a decreased insulin response to glucose remained. No ultrastructural signs of beta-cell damage were observed, with the exception of increased glycogen deposits in animals hyperglycemic at the time of killing. It is concluded that prolonged exposure to a diabetic environment induces a long-term secretory defect in human beta-cells, which is not dependent on the size of the islet insulin stores. Images PMID:7635965

  19. Brown Adipose Tissue Improves Whole-Body Glucose Homeostasis and Insulin Sensitivity in Humans

    PubMed Central

    Chondronikola, Maria; Volpi, Elena; Børsheim, Elisabet; Porter, Craig; Annamalai, Palam; Enerbäck, Sven; Lidell, Martin E.; Saraf, Manish K.; Labbe, Sebastien M.; Hurren, Nicholas M.; Yfanti, Christina; Chao, Tony; Andersen, Clark R.; Cesani, Fernando; Hawkins, Hal

    2014-01-01

    Brown adipose tissue (BAT) has attracted scientific interest as an antidiabetic tissue owing to its ability to dissipate energy as heat. Despite a plethora of data concerning the role of BAT in glucose metabolism in rodents, the role of BAT (if any) in glucose metabolism in humans remains unclear. To investigate whether BAT activation alters whole-body glucose homeostasis and insulin sensitivity in humans, we studied seven BAT-positive (BAT+) men and five BAT-negative (BAT−) men under thermoneutral conditions and after prolonged (5–8 h) cold exposure (CE). The two groups were similar in age, BMI, and adiposity. CE significantly increased resting energy expenditure, whole-body glucose disposal, plasma glucose oxidation, and insulin sensitivity in the BAT+ group only. These results demonstrate a physiologically significant role of BAT in whole-body energy expenditure, glucose homeostasis, and insulin sensitivity in humans, and support the notion that BAT may function as an antidiabetic tissue in humans. PMID:25056438

  20. Diabetes mellitus caused by mutations in human insulin: analysis of impaired receptor binding of insulins Wakayama, Los Angeles and Chicago using pharmacoinformatics.

    PubMed

    Islam, Md Ataul; Bhayye, Sagar; Adeniyi, Adebayo A; Soliman, Mahmoud E S; Pillay, Tahir S

    2017-03-01

    Several naturally occuring mutations in the human insulin gene are associated with diabetes mellitus. The three known mutant molecules, Wakayama, Los Angeles and Chicago were evaluated using molecular docking and molecular dynamics (MD) to analyse mechanisms of deprived binding affinity for insulin receptor (IR). Insulin Wakayama, is a variant in which valine at position A3 is substituted by leucine, while in insulin Los Angeles and Chicago, phenylalanine at positions B24 and B25 is replaced by serine and leucine, respectively. These mutations show radical changes in binding affinity for IR. The ZDOCK server was used for molecular docking, while AMBER 14 was used for the MD study. The published crystal structure of IR bound to natural insulin was also used for MD. The binding interactions and MD trajectories clearly explained the critical factors for deprived binding to the IR. The surface area around position A3 was increased when valine was substituted by leucine, while at positions B24 and B25 aromatic amino acid phenylalanine replaced by non-aromatic serine and leucine might be responsible for fewer binding interactions at the binding site of IR that leads to instability of the complex. In the MD simulation, the normal mode analysis, rmsd trajectories and prediction of fluctuation indicated instability of complexes with mutant insulin in order of insulin native insulin < insulin Chicago < insulin Los Angeles < insulin Wakayama molecules which corresponds to the biological evidence of the differing affinities of the mutant insulins for the IR.

  1. Ion channels and regulation of insulin secretion in human β-cells

    PubMed Central

    Fridlyand, Leonid E.; Jacobson, David A.; Philipson, L.H.

    2013-01-01

    In mammals an increase in glucose leads to block of ATP dependent potassium channels in pancreatic β cells leading to membrane depolarization. This leads to the repetitive firing of action potentials that increases calcium influx and triggers insulin granule exocytosis. Several important differences between species in this process suggest that a dedicated human-oriented approach is advantageous as extrapolating from rodent data may be misleading in several respects. We examined depolarization-induced spike activity in pancreatic human islet-attached β-cells employing whole-cell patch-clamp methods. We also reviewed the literature concerning regulation of insulin secretion by channel activity and constructed a data-based computer model of human β cell function. The model couples the Hodgkin-Huxley-type ionic equations to the equations describing intracellular Ca2+ homeostasis and insulin release. On the basis of this model we employed computational simulations to better understand the behavior of action potentials, calcium handling and insulin secretion in human β cells under a wide range of experimental conditions. This computational system approach provides a framework to analyze the mechanisms of human β cell insulin secretion. PMID:23624892

  2. Artemisia dracunculus L. extract ameliorates insulin sensitivity by attenuating inflammatory signalling in human skeletal muscle culture

    PubMed Central

    Vandanmagsar, Bolormaa; Haynie, Kimberly R.; Wicks, Shawna E.; Bermudez, Estrellita M.; Mendoza, Tamra M.; Ribnicky, David; Cefalu, William T.; Mynatt, Randall L.

    2014-01-01

    Aims Bioactives of Artemisia dracunculus L. (termed PMI 5011) have been shown to improve insulin action by increasing insulin signalling in skeletal muscle. However, it has not known if PMI 5011’s effects are retained during an inflammatory condition. We examined the attenuation of insulin action and whether PMI 5011 enhances insulin signalling in the inflammatory environment with elevated cytokines. Methods Muscle cell cultures derived from lean, overweight and diabetic obese subjects were used. Expression of pro-inflammatory genes and inflammatory response of human myotubes were evaluated by RT-PCR. Insulin signalling and activation of inflammatory pathways in human myotubes were evaluated by Multiplex protein assays. Results We found increased gene expression of MCP1 and TNFα, and basal activity of the NFkB pathway in myotubes derived from diabetic-obese subjects as compared to myotubes derived from normal-lean subjects. In line with this, basal Akt phosphorylation (Ser473) was significantly higher, while insulin-stimulated phosphorylation of Akt (Ser473) was lower in myotubes from normal-overweight and diabetic-obese subjects compared to normal-lean subjects. PMI 5011 treatment reduced basal phosphorylation of Akt and enhanced insulin-stimulated phosphorylation of Akt in the presence of cytokines in human myotubes. PMI 5011 treatment led to an inhibition of cytokine-induced activation of inflammatory signalling pathways such as Erk1/2 and IkBα-NFkB and moreover, NFkB target gene expression, possibly by preventing further propagation of the inflammatory response within muscle tissue. Conclusions PMI 5011 improved insulin sensitivity in diabetic-obese myotubes to the level of normal-lean myotubes despite the presence of pro-inflammatory cytokines. PMID:24521217

  3. Effects of insulin on human pancreatic cancer progression modeled in vitro.

    PubMed

    Chan, Michelle T; Lim, Gareth E; Skovsø, Søs; Yang, Yu Hsuan Carol; Albrecht, Tobias; Alejandro, Emilyn U; Hoesli, Corinne A; Piret, James M; Warnock, Garth L; Johnson, James D

    2014-11-06

    Pancreatic adenocarcinoma is one of the most lethal cancers, yet it remains understudied and poorly understood. Hyperinsulinemia has been reported to be a risk factor of pancreatic cancer, and the rapid rise of hyperinsulinemia associated with obesity and type 2 diabetes foreshadows a rise in cancer incidence. However, the actions of insulin at the various stages of pancreatic cancer progression remain poorly defined. Here, we examined the effects of a range of insulin doses on signalling, proliferation and survival in three human cell models meant to represent three stages in pancreatic cancer progression: primary pancreatic duct cells, the HPDE immortalized pancreatic ductal cell line, and the PANC1 metastatic pancreatic cancer cell line. Cells were treated with a range of insulin doses, and their proliferation/viability were tracked via live cell imaging and XTT assays. Signal transduction was assessed through the AKT and ERK signalling pathways via immunoblotting. Inhibitors of AKT and ERK signalling were used to determine the relative contribution of these pathways to the survival of each cell model. While all three cell types responded to insulin, as indicated by phosphorylation of AKT and ERK, we found that there were stark differences in insulin-dependent proliferation, cell viability and cell survival among the cell types. High concentrations of insulin increased PANC1 and HPDE cell number, but did not alter primary duct cell proliferation in vitro. Cell survival was enhanced by insulin in both primary duct cells and HPDE cells. Moreover, we found that primary cells were more dependent on AKT signalling, while HPDE cells and PANC1 cells were more dependent on RAF/ERK signalling. Our data suggest that excessive insulin signalling may contribute to proliferation and survival in human immortalized pancreatic ductal cells and metastatic pancreatic cancer cells, but not in normal adult human pancreatic ductal cells. These data suggest that signalling pathways

  4. St. John's Wort inhibits insulin signaling in murine and human adipocytes.

    PubMed

    Richard, Allison J; Amini, Zhaleh J; Ribnicky, David M; Stephens, Jacqueline M

    2012-04-01

    Adipocytes are insulin-sensitive cells that play a major role in energy homeostasis. Obesity is the primary disease of fat cells and a major risk factor for the development of Type 2 diabetes, cardiovascular disease, and metabolic syndrome. The use of botanicals in the treatment of metabolic diseases is an emerging area of research. In previous studies, we screened over 425 botanical extracts for their ability to modulate adipogenesis and insulin sensitivity. We identified St. John's Wort (SJW) extracts as inhibitors of adipogenesis of 3T3-L1 cells and demonstrated that these extracts also inhibited insulin-sensitive glucose uptake in mature fat cells. In these follow-up studies we have further characterized the effects of SJW on insulin action in both murine and human fat cells. We have shown that SJW also attenuates insulin-sensitive glucose uptake in human adipocytes. Moreover, SJW inhibits IRS-1 tyrosine phosphorylation in both murine and human fat cells. Botanical extracts are complex mixtures. Many bioactive compounds have been identified in SJW, including hypericin (HI) and hyperforin (HF). We have examined the ability of HI and HF, purified from SJW, to modulate adipocyte development and insulin action in mature adipocytes. Our novel studies indicate that the profound effects of SJW on adipogenesis, IRS-1 activation, and insulin-stimulated glucose uptake are not mediated by HI and/or HF. Nonetheless, we propose that extracts of SJW may contribute to adipocyte related diseases by limiting differentiation of preadipocytes and significantly inducing insulin resistance in mature fat cells.

  5. Resistin's, obesity and insulin resistance: the continuing disconnect between rodents and humans.

    PubMed

    Huang, X; Yang, Z

    2016-06-01

    This review aimed to discuss the conflicting findings from resistin research in rodents and humans as well as recent advances in our understanding of resistin's role in obesity and insulin resistance. A comprehensive review and synthesis of resistin's role in obesity and insulin resistance as well as conflicting findings from resistin research in rodents and humans. In rodents, resistin is increased in high-fat/high-carbohydrate-fed, obese states characterized by impaired glucose uptake and insulin sensitivity. Resistin plays a causative role in the development of insulin resistance in rodents via 5' AMP-activated protein kinase (AMPK)-dependent and AMPK-independent suppressor of cytokine signaling-3 (SOCS-3) signaling. In contrast to rodents, human resistin is primarily secreted by peripheral-blood mononuclear cells (PBMCs) as opposed to white adipocytes. Circulating resistin levels have been positively associated with central/visceral obesity (but not BMI) as well as insulin resistance, while other studies show no such association. Human resistin has a role in pro-inflammatory processes that have been conclusively associated with obesity and insulin resistance. PBMCs, as well as vascular cells, have been identified as the primary targets of resistin's pro-inflammatory activity via nuclear factor-κB (NF-κB, p50/p65) and other signaling pathways. Mounting evidence reveals a continuing disconnect between resistin's role in rodents and humans due to significant differences between these two species with respect to resistin's gene and protein structure, differential gene regulation, tissue-specific distribution, and insulin resistance induction as well as a paucity of evidence regarding the resistin receptor and downstream signaling mechanisms of action.

  6. Intranasal insulin suppresses food intake via enhancement of brain energy levels in humans.

    PubMed

    Jauch-Chara, Kamila; Friedrich, Alexia; Rezmer, Magdalena; Melchert, Uwe H; G Scholand-Engler, Harald; Hallschmid, Manfred; Oltmanns, Kerstin M

    2012-09-01

    Cerebral insulin exerts anorexic effects in humans and animals. The underlying mechanisms, however, are not clear. Because insulin physiologically facilitates glucose uptake by most tissues of the body and thereby fosters intracellular energy supply, we hypothesized that intranasal insulin reduces food consumption via enhancement of the neuroenergetic level. In a double-blind, placebo-controlled, within-subject comparison, 15 healthy men (BMI 22.2 ± 0.37 kg/m(2)) aged 22-28 years were intranasally administered insulin (40 IU) or placebo after an overnight fast. Cerebral energy metabolism was assessed by (31)P magnetic resonance spectroscopy. At 100 min after spray administration, participants consumed ad libitum from a test buffet. Our data show that intranasal insulin increases brain energy (i.e., adenosine triphosphate and phosphocreatine levels). Cerebral energy content correlates inversely with subsequent calorie intake in the control condition. Moreover, the neuroenergetic rise upon insulin administration correlates with the consecutive reduction in free-choice calorie consumption. Brain energy levels may therefore constitute a predictive value for food intake. Given that the brain synchronizes food intake behavior in dependence of its current energetic status, a future challenge in obesity treatment may be to therapeutically influence cerebral energy homeostasis. Intranasal insulin, after optimizing its application schema, seems a promising option in this regard.

  7. Effects of glucose and insulin on secretion of amyloid-β by human adipose tissue cells.

    PubMed

    Tharp, William G; Gupta, Dhananjay; Smith, Joshua; Jones, Karen P; Jones, Amanda M; Pratley, Richard E

    2016-07-01

    Obesity and type 2 diabetes mellitus are risk factors for developing Alzheimer disease. Overlapping patterns of metabolic dysfunction may be common molecular links between these complex diseases. Amyloid-β (Aβ) precursor protein and associated β- and γ-secretases are expressed in adipose tissue. Aβ precursor protein is up-regulated with obesity and correlated to insulin resistance. Aβ may be secreted by adipose tissue, its production may be regulated through metabolic pathways, and Aβ may exert effects on adipose tissue insulin receptor signaling. Human stromal-vascular cells and differentiated adipocytes were cultured with different combinations of glucose and insulin and then assayed for Aβ in conditioned media. Aβ was measured in vivo using adipose tissue microdialysis. Aβ secretion was increased by glucose and insulin in vitro. Adipose tissue microdialysates contained Aβ. Adipocytes treated with Aβ had decreased expression of insulin receptor substrate-2 and reduced Akt-1 phosphorylation. Aβ was made by adipose tissue cells in vitro at concentrations similar to in vivo measurements. Regulation of Aβ production by glucose and insulin and effects of Aβ on the insulin receptor pathway suggest similar cellular mechanisms may exist between neuronal dysfunction in Alzheimer disease and adipose dysfunction in type 2 diabetes. © 2016 The Authors Obesity published by Wiley Periodicals, Inc. on behalf of The Obesity Society (TOS).

  8. Human muscle fiber type-specific insulin signaling: impact of obesity and type 2 diabetes.

    PubMed

    Albers, Peter H; Pedersen, Andreas J T; Birk, Jesper B; Kristensen, Dorte E; Vind, Birgitte F; Baba, Otto; Nøhr, Jane; Højlund, Kurt; Wojtaszewski, Jørgen F P

    2015-02-01

    Skeletal muscle is a heterogeneous tissue composed of different fiber types. Studies suggest that insulin-mediated glucose metabolism is different between muscle fiber types. We hypothesized that differences are due to fiber type-specific expression/regulation of insulin signaling elements and/or metabolic enzymes. Pools of type I and II fibers were prepared from biopsies of the vastus lateralis muscles from lean, obese, and type 2 diabetic subjects before and after a hyperinsulinemic-euglycemic clamp. Type I fibers compared with type II fibers have higher protein levels of the insulin receptor, GLUT4, hexokinase II, glycogen synthase (GS), and pyruvate dehydrogenase-E1α (PDH-E1α) and a lower protein content of Akt2, TBC1 domain family member 4 (TBC1D4), and TBC1D1. In type I fibers compared with type II fibers, the phosphorylation response to insulin was similar (TBC1D4, TBC1D1, and GS) or decreased (Akt and PDH-E1α). Phosphorylation responses to insulin adjusted for protein level were not different between fiber types. Independently of fiber type, insulin signaling was similar (TBC1D1, GS, and PDH-E1α) or decreased (Akt and TBC1D4) in muscle from patients with type 2 diabetes compared with lean and obese subjects. We conclude that human type I muscle fibers compared with type II fibers have a higher glucose-handling capacity but a similar sensitivity for phosphoregulation by insulin.

  9. Influence of glucocorticoids and growth hormone on insulin sensitivity in humans.

    PubMed

    Yuen, K C J; Chong, L E; Riddle, M C

    2013-06-01

    The seminal concept proposed by Sir Harold Himsworth more than 75 years ago that a large number of patients with diabetes were 'insulin insensitive', now termed insulin resistance, has now expanded to include several endocrine syndromes, namely those of glucocorticoid excess, and growth hormone excess and deficiency. Synthetic glucocorticoids are increasingly used to treat a wide variety of chronic diseases, whereas the beneficial effects of recombinant growth hormone replacement therapy in children and adults with growth hormone deficiency have now been well-recognized for over 25 years. However, clinical and experimental studies have established that increased circulating levels of glucocorticoids and growth hormone can also lead to worsening of insulin resistance, glucose intolerance, overt diabetes mellitus and cardiovascular disease. Improved understanding of the physiological 24-h rhythmicity of glucocorticoid and growth hormone secretion and its influence on the dawn phenomenon and the Staub-Trauggot effect has therefore led to renewed interest in studies on the mechanisms of insulin resistance induced by exogenous administration of glucocorticoids and growth hormone in humans. In this review, we describe the physiological events that result from the presence of resistance to insulin action at the level of skeletal muscle, adipose tissue, and liver, describe the known mechanisms of glucocorticoid- and growth hormone-mediated insulin resistance, and provide an update of the contributions of glucocorticoids and growth hormone to understanding the pathophysiology of insulin resistance and its effects on several endocrine syndromes. © 2013 The Authors. Diabetic Medicine © 2013 Diabetes UK.

  10. Long-acting insulin analog detemir displays reduced effects on adipocyte differentiation of human subcutaneous and visceral adipose stem cells.

    PubMed

    Cignarelli, A; Perrini, S; Nigro, P; Ficarella, R; Barbaro, M; Peschechera, A; Porro, S; Natalicchio, A; Laviola, L; Puglisi, F; Giorgino, F

    2016-04-01

    Since treatment with insulin detemir results in a lower weight gain compared to human insulin, we investigated whether detemir is associated with lower ability to promote adipogenesis and/or lipogenesis in human adipose stem cells (ASC). Human ASC isolated from both the subcutaneous and visceral adipose tissues were differentiated for 30 days in the presence of human insulin or insulin detemir. Nile Red and Oil-Red-O staining were used to quantify the rate of ASC conversion to adipocytes and lipid accumulation, respectively. mRNA expression levels of early genes, including Fos and Cebpb, as well as of lipogenic and adipogenic genes, were measured at various phases of differentiation by qRT-PCR. Activation of insulin signaling was assessed by immunoblotting. ASC isolated from subcutaneous and visceral adipose tissue were less differentiated when exposed to insulin detemir compared to human insulin, showing lower rates of adipocyte conversion, reduced triglyceride accumulation, and impaired expression of late-phase adipocyte marker genes, such as Pparg2, Slc2a4, Adipoq, and Cidec. However, no differences in activation of insulin receptor, Akt and Erk and induction of the early genes Fos and Cebpb were observed between insulin detemir and human insulin. Insulin detemir displays reduced induction of the Pparg2 adipocyte master gene and diminished effects on adipocyte differentiation and lipogenesis in human subcutaneous and visceral ASC, in spite of normal activation of proximal insulin signaling reactions. These characteristics of insulin detemir may be of potential relevance to its weight-sparing effects observed in the clinical setting. Copyright © 2015 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.

  11. Regulation of recombinant human insulin-induced maturational events in Clarias batrachus (L.) oocytes in vitro.

    PubMed

    Hajra, Sudip; Das, Debabrata; Ghosh, Pritha; Pal, Soumojit; Nath, Poulomi; Maitra, Sudipta

    2016-04-01

    Regulation of insulin-mediated resumption of meiotic maturation in catfish oocytes was investigated. Insulin stimulation of post-vitellogenic oocytes promotes the synthesis of cyclin B, histone H1 kinase activation and a germinal vesicle breakdown (GVBD) response in a dose-dependent and duration-dependent manner. The PI3K inhibitor wortmannin abrogates recombinant human (rh)-insulin action on histone H1 kinase activation and meiotic G2-M1 transition in denuded and follicle-enclosed oocytes in vitro. While the translational inhibitor cycloheximide attenuates rh-insulin action, priming with transcriptional blocker actinomycin D prevents insulin-stimulated maturational response appreciably, albeit in low amounts. Compared with rh-insulin, human chorionic gonadotrophin (hCG) stimulation of follicle-enclosed oocytes in vitro triggers a sharp increase in 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DHP) secreted in the incubation medium at 12 h. Interestingly, the insulin, but not the hCG-induced, maturational response shows less susceptibility to steroidogenesis inhibitors, trilostane or dl-aminoglutethimide. In addition, priming with phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX) or cell-permeable dbcAMP or adenylyl cyclase activator forskolin reverses the action of insulin on meiotic G2-M1 transition. Conversely, the adenylyl cyclase inhibitor, SQ 22536, or PKA inhibitor H89 promotes the resumption of meiosis alone and further potentiates the GVBD response in the presence of rh-insulin. Furthermore, insulin-mediated meiotic maturation involves the down-regulation of endogenous protein kinase A (PKA) activity in a manner sensitive to PI3K activation, suggesting potential involvement of a cross-talk between cAMP/PKA and insulin-mediated signalling cascade in catfish oocytes in vitro. Taken together, these results suggest that rh-insulin regulation of the maturational response in C. batrachus oocytes involves down-regulation of PKA, synthesis of cyclin

  12. The Expanding Pathogenic Role of Insulin Resistance in Human Disease.

    PubMed

    2014-01-07

    The December 2011 issue of Diabetic Medicine celebrated the outstanding personal contributions of the renowned clinical scientist Prof. Sir Harold Himsworth in characterizing impaired insulin action in relation to phenotypes of diabetes. The commissioned articles in the special issue of the journal were assembled in recognition of the publication in 1936 of a landmark paper in which Himsworth summarized his innovative research, to which much of our current understanding of insulin resistance can be readily traced. The collection of invited articles that marked the 75th anniversary of the Lancet publication provided a state-of-the-art summary from internationally renowned investigators of what has become an increasingly diverse field reaching into myriad aspects of clinical medicine. This article is protected by copyright. All rights reserved.

  13. Structural meta-analysis of regular human insulin in pharmaceutical formulations.

    PubMed

    Fávero-Retto, Maely P; Palmieri, Leonardo C; Souza, Tatiana A C B; Almeida, Fábio C L; Lima, Luís Mauricio T R

    2013-11-01

    We have studied regular acting, wild-type human insulin at potency of 100 U/mL from four different pharmaceutical products directly from their final finished formulation by the combined use of mass spectrometry (MS), dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR), and single-crystal protein crystallography (PX). All products showed similar oligomeric assembly in solution as judged by DLS and SAXS measurements. The NMR spectra were compatible with well folded proteins, showing close conformational identity for the human insulin in the four products. Crystallographic assays conducted with the final formulated products resulted in all insulin crystals belonging to the R3 space group with two a dimer in the asymmetric unit, both with the B-chain in the T configuration. Meta-analysis of the 24 crystal structures solved from the four distinct insulin products revealed close similarity between them regardless of variables such as biological origin, product batch, country origin of the product, and analytical approach, revealing a low conformational variability for the converging insulin structural ensemble. We propose the use of MS, SAXS, NMR fingerprint, and PX as a precise chemical and structural proof of folding identity of regular insulin in the final, formulated product.

  14. PKCδ regulates hepatic insulin sensitivity and hepatosteatosis in mice and humans

    PubMed Central

    Bezy, Olivier; Tran, Thien T.; Pihlajamäki, Jussi; Suzuki, Ryo; Emanuelli, Brice; Winnay, Jonathan; Mori, Marcelo A.; Haas, Joel; Biddinger, Sudha B.; Leitges, Michael; Goldfine, Allison B.; Patti, Mary Elizabeth; King, George L.; Kahn, C. Ronald

    2011-01-01

    C57BL/6J and 129S6/Sv (B6 and 129) mice differ dramatically in their susceptibility to developing diabetes in response to diet- or genetically induced insulin resistance. A major locus contributing to this difference has been mapped to a region on mouse chromosome 14 that contains the gene encoding PKCδ. Here, we found that PKCδ expression in liver was 2-fold higher in B6 versus 129 mice from birth and was further increased in B6 but not 129 mice in response to a high-fat diet. PRKCD gene expression was also elevated in obese humans and was positively correlated with fasting glucose and circulating triglycerides. Mice with global or liver-specific inactivation of the Prkcd gene displayed increased hepatic insulin signaling and reduced expression of gluconeogenic and lipogenic enzymes. This resulted in increased insulin-induced suppression of hepatic gluconeogenesis, improved glucose tolerance, and reduced hepatosteatosis with aging. Conversely, mice with liver-specific overexpression of PKCδ developed hepatic insulin resistance characterized by decreased insulin signaling, enhanced lipogenic gene expression, and hepatosteatosis. Therefore, changes in the expression and regulation of PKCδ between strains of mice and in obese humans play an important role in the genetic risk of hepatic insulin resistance, glucose intolerance, and hepatosteatosis; and thus PKCδ may be a potential target in the treatment of metabolic syndrome. PMID:21576825

  15. Gestational Diabetes Reduces Adenosine Transport in Human Placental Microvascular Endothelium, an Effect Reversed by Insulin

    PubMed Central

    Salomón, Carlos; Westermeier, Francisco; Puebla, Carlos; Arroyo, Pablo; Guzmán-Gutiérrez, Enrique; Pardo, Fabián; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis

    2012-01-01

    Gestational diabetes mellitus (GDM) courses with increased fetal plasma adenosine concentration and reduced adenosine transport in placental macrovascular endothelium. Since insulin modulates human equilibrative nucleoside transporters (hENTs) expression/activity, we hypothesize that GDM will alter hENT2-mediated transport in human placental microvascular endothelium (hPMEC), and that insulin will restore GDM to a normal phenotype involving insulin receptors A (IR-A) and B (IR-B). GDM effect on hENTs expression and transport activity, and IR-A/IR-B expression and associated cell signalling cascades (p42/44 mitogen-activated protein kinases (p42/44mapk) and Akt) role in hPMEC primary cultures was assayed. GDM associates with elevated umbilical whole and vein, but not arteries blood adenosine, and reduced hENTs adenosine transport and expression. IR-A/IR-B mRNA expression and p42/44mapk/Akt ratios (‘metabolic phenotype’) were lower in GDM. Insulin reversed GDM-reduced hENT2 expression/activity, IR-A/IR-B mRNA expression and p42/44mapk/Akt ratios to normal pregnancies (‘mitogenic phenotype’). It is suggested that insulin effects required IR-A and IR-B expression leading to differential modulation of signalling pathways restoring GDM-metabolic to a normal-mitogenic like phenotype. Insulin could be acting as protecting factor for placental microvascular endothelial dysfunction in GDM. PMID:22808198

  16. Human umbilical cord-derived mesenchymal stem cells can secrete insulin in vitro and in vivo.

    PubMed

    Boroujeni, Zahra Niki; Aleyasin, Ahmad

    2014-01-01

    Diabetes mellitus is characterized by autoimmune destruction of pancreatic beta cells, leading to decreased insulin production. Differentiation of mesenchymal stem cells (MSCs) into insulin-producing cells offers novel ways of diabetes treatment. MSCs can be isolated from the human umbilical cord tissue and differentiate into insulin-secreting cells. Human umbilical cord-derived stem cells (hUDSCs) were obtained after birth, selected by plastic adhesion, and characterized by flow cytometric analysis. hUDSCs were transduced with nonintegrated lentivirus harboring PDX1 (nonintegrated LV-PDX1) and was cultured in differentiation medium in 21 days. Pancreatic duodenum homeobox protein-1 (PDX1) is a transcription factor in pancreatic development. Significant expressions of PDX1, neurogenin3 (Ngn3), glucagon, glucose transporter2 (Glut2), and somatostatin were detected by quantitative RT-PCR (P < 0.05). PDX1 and insulin proteins were shown by immunocytochemistry analysis. Insulin secretion of hUDSCs(PDX1+) in the high-glucose medium was 1.8 μU/mL. They were used for treatment of diabetic rats and could decrease the blood glucose level from 400 mg/dL to a normal level in 4 days. In conclusion, our results demonstrated that hUDSCs are able to differentiate into insulin-producing cells by transduction with nonintegrated LV-PDX1. These hUDSCs(PDX1+) have the potential to be used as a viable resource in cell-based gene therapy of type 1 diabetes.

  17. Fuel premixing module for gas turbine engine combustor

    NASA Technical Reports Server (NTRS)

    Chin, Jushan (Inventor); Rizk, Nader K. (Inventor); Razdan, Mohan K. (Inventor); Marshall, Andre W. (Inventor)

    2005-01-01

    A fuel-air premixing module is designed to reduce emissions from a gas turbine engine. In one form, the premixing module includes a central pilot premixer module with a main premixer module positioned thereround. Each of the portions of the fuel-air premixing module include an axial inflow swirler with a plurality of fixed swirler vanes. Fuel is injected into the main premixer module between the swirler vanes of the axial inflow swirler and at an acute angle relative to the centerline of the premixing module.

  18. Glucose-dependent insulinotropic polypeptide induces cytokine expression, lipolysis, and insulin resistance in human adipocytes.

    PubMed

    Timper, Katharina; Grisouard, Jean; Sauter, Nadine S; Herzog-Radimerski, Tanja; Dembinski, Kaethi; Peterli, Ralph; Frey, Daniel M; Zulewski, Henryk; Keller, Ulrich; Müller, Beat; Christ-Crain, Mirjam

    2013-01-01

    Obesity-related insulin resistance is linked to a chronic state of systemic and adipose tissue-derived inflammation. Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone also acting on adipocytes. We investigated whether GIP affects inflammation, lipolysis, and insulin resistance in human adipocytes. Human subcutaneous preadipocyte-derived adipocytes, differentiated in vitro, were treated with human GIP to analyze mRNA expression and protein secretion of cytokines, glycerol, and free fatty acid release and insulin-induced glucose uptake. GIP induced mRNA expression of IL-6, IL-1β, and the IL-1 receptor antagonist IL-1Ra, whereas TNFα, IL-8, and monocyte chemotactic protein (MCP)-1 remained unchanged. Cytokine induction involved PKA and the NF-κB pathway as well as an autocrine IL-1 effect. Furthermore, GIP potentiated IL-6 and IL-1Ra secretion in the presence of LPS, IL-1β, and TNFα. GIP induced lipolysis via activation of hormone-sensitive lipase and was linked to NF-κB activation. Finally, chronic GIP treatment impaired insulin-induced glucose uptake possibly due to the observed impaired translocation of glucose transporter GLUT4. In conclusion, GIP induces an inflammatory and prolipolytic response via the PKA -NF-κB-IL-1 pathway and impairs insulin sensitivity of glucose uptake in human adipocytes.

  19. Population pharmacokinetic model of human insulin following different routes of administration.

    PubMed

    Potocka, Elizabeth; Baughman, Robert A; Derendorf, Hartmut

    2011-07-01

    Multiple-compartment disposition of insulin has been demonstrated following intravenous administration; however, because of slow absorption and flip-flop kinetics, meal-time insulin pharmacokinetics have been described by a 1-compartment model. Technosphere insulin (TI) is an inhaled human insulin with rapid absorption and a distinct second compartment in its pharmacokinetics. The aim of this analysis was to develop a pharmacokinetic model for insulin administered via the intravenous, subcutaneous, and inhalation routes. A 2-compartment pharmacokinetic model with 1 (inhaled) or 2 sequential (subcutaneous) first-order absorption processes and first-order elimination was developed using data from 2 studies with a total of 651 concentrations from 16 healthy volunteers. Insulin was administered intravenously (5 U), subcutaneously (10 U), and via inhalation (25, 50, and 100 U). The data were modeled simultaneously with NONMEM VI, using ADVAN6 subroutine with FO. Typical values were clearance, 43.4 L/h; volume of distribution in the central compartment, 5.0 L; intercompartmental clearance, 23.9 L/h; volume of distribution in the peripheral compartment 30.7 L; TI first-order absorption rate constant, 2.35 h⁻¹; and first-order absorption rate constants associated with subcutaneously administered insulin, 0.63 and 1.04 h⁻¹, respectively. Absorption rate after subcutaneous dosing was found to decrease with increasing body mass index. Insulin pharmacokinetics were found to be consistent with 2-compartment disposition, regardless of route of administration, with insulin curve differences attributable to absorption differences.

  20. Effects of insulin on pharmacodynamics of immunosuppressive drugs against mitogen-activated human peripheral blood mononuclear cells.

    PubMed

    Chen, Shuiling; Sugiyama, Kentaro; Inamura, Mariko; Tanaka, Sachiko; Onda, Kenji; Yin, Huijun; Hirano, Toshihiko

    2016-10-01

    Diabetes mellitus is one of the most common causes of chronic renal failure. Immunosuppressive efficacies of glucocorticoids, calcineurin inhibitors, and mycophenolic acid are possibly affected by insulin after renal transplantation in these patients. We investigated the effects of insulin on responses of mitogen-activated human peripheral blood mononuclear cells (PBMCs) to several immunosuppressive drugs. Antiproliferative efficacies of prednisolone, hydrocortisone, cyclosporine, tacrolimus, and mycophenolic acid against concanavalin A-stimulated PBMCs were evaluated in the presence of physiological (5 μunits/mL) and super physiological (50 μunits/mL) concentrations of insulin. Insulin-receptor expressions on PBMCs were evaluated by flow cytometry. Insulin itself had no effects on the mitogen-induced proliferation of PBMCs. The IC50 values of cyclosporine against the mitogen-activated PBMCs in the presence of 5 or 50 μunits/mL insulin were significantly higher than those of cyclosporine without insulin (p < 0.05). The IC50 values of mycophenolic acid significantly increased by 50 μunits/mL insulin (p < 0.01). Insulin receptors were detected on the mitogen-activated CD4(+)/CD14(+ )cells in PBMCs. These results indicate that insulin at even physiological concentration attenuates suppressive efficacies of several immunosuppressive drugs against mitogen-activated proliferation of human PBMCs, possibly via insulin receptors. Insulin used in dialysis patients accompanying diabetes mellitus is suggested to attenuate efficacies of immunosuppressive drugs after renal transplantation.

  1. Effect of extracellular vesicles of human adipose tissue on insulin signaling in liver and muscle cells.

    PubMed

    Kranendonk, Mariëtte E G; Visseren, Frank L J; van Herwaarden, Joost A; Nolte-'t Hoen, Esther N M; de Jager, Wilco; Wauben, Marca H M; Kalkhoven, Eric

    2014-10-01

    Insulin resistance (IR) is a key mechanism in obesity-induced cardiovascular disease. To unravel mechanisms whereby human adipose tissue (AT) contributes to systemic IR, the effect of human AT-extracellular vesicles (EVs) on insulin signaling in liver and muscle cells was determined. EVs released from human subcutaneous (SAT) and omental AT (OAT)-explants ex vivo were used for stimulation of hepatocytes and myotubes in vitro. Subsequently, insulin-induced Akt phosphorylation and expression of gluconeogenic genes (G6P, PEPCK) was determined. AT-EV adipokine levels were measured by multiplex immunoassay, and AT-EVs were quantified by high-resolution flow cytometry. In hepatocytes, AT-EVs from the majority of patients inhibited insulin-induced Akt phosphorylation, while EVs from some patients stimulated insulin-induced Akt phosphorylation. In myotubes AT-EVs exerted an ambiguous effect on insulin signaling. Hepatic Akt phosphorylation related negatively to G6P-expression by both SAT-EVs (r = -0.60, P = 0.01) and OAT-EVs (r = -0.74, P = 0.001). MCP-1, IL-6, and MIF concentrations were higher in OAT-EVs compared to SAT-EVs and differently related to lower Akt phosphorylation in hepatocytes. Finally, the number of OAT-EVs correlated positively with liver enzymes indicative for liver dysfunction. Human AT-EVs can stimulate or inhibit insulin signaling in hepatocytes- possibly depending on their adipokine content- and may thereby contribute to systemic IR. Copyright © 2014 The Obesity Society.

  2. Insulin management of type 2 diabetes mellitus.

    PubMed

    Petznick, Allison

    2011-07-15

    Insulin therapy is recommended for patients with type 2 diabetes mellitus and an initial A1C level greater than 9 percent, or if diabetes is uncontrolled despite optimal oral glycemic therapy. Insulin therapy may be initiated as augmentation, starting at 0.3 unit per kg, or as replacement, starting at 0.6 to 1.0 unit per kg. When using replacement therapy, 50 percent of the total daily insulin dose is given as basal, and 50 percent as bolus, divided up before breakfast, lunch, and dinner. Augmentation therapy can include basal or bolus insulin. Replacement therapy includes basal-bolus insulin and correction or premixed insulin. Glucose control, adverse effects, cost, adherence, and quality of life need to be considered when choosing therapy. Metformin should be continued if possible because it is proven to reduce all-cause mortality and cardiovascular events in overweight patients with diabetes. In a study comparing premixed, bolus, and basal insulin, hypoglycemia was more common with premixed and bolus insulin, and weight gain was more common with bolus insulin. Titration of insulin over time is critical to improving glycemic control and preventing diabetes-related complications.

  3. Mechanisms of defective glucose-induced insulin release in human pancreatic islets transplanted to diabetic nude mice.

    PubMed

    Eizirik, D L; Jansson, L; Flodström, M; Hellerström, C; Andersson, A

    1997-08-01

    We have previously observed that human islets, transplanted under the kidney capsule of hyperglycemic nude mice, show a longlasting impairment in glucose-induced insulin release. To investigate the cause(s) of this phenomenon, we transplanted human islets into normoglycemic or alloxan-diabetic nude mice for a 4- to 6-week period. In a third experimental group, aimed at evaluating reversibility of hyperglycemia effects, diabetic nude mice bearing a human islet graft were cured by a second intrasplenic transplant of mouse islets, and the human islets were exposed to a further 2 weeks of normoglycemia. Four to 6 weeks of hyperglycemia induced a severe impairment of glucose- and arginine-induced insulin release, as demonstrated by perfusion of the graft-bearing kidney. This defective release was not restored by a subsequent 2-week period of normoglycemia, and it was accompanied by normal (pro)insulin biosynthesis, glucose oxidation, and expression of insulin messenger RNA. Taken together with our previous study, these observations indicate that impaired glucose metabolism, depletion of insulin messenger RNA, decreased (pro)insulin biosynthesis, increased glycogen accumulation, and depletion of insulin reserves cannot explain the deleterious effects of the diabetic state on human islet insulin release. This, and the similar inhibition of glucose- and arginine-induced insulin release, suggest that prolonged hyperglycemia may exert its deleterious effect on insulin release at a step distal to closure of ATP-sensitive K-channels.

  4. [Anaphylactic shock due to recombinant human insulin: follow-up of a desensitization protocol by basophil activation test].

    PubMed

    Luyasu, S; Hougardy, N; Hasdenteufel, F; Jacquenet, S; Weber, E; Moneret-Vautrin, A; Kanny, G

    2011-01-01

    Despite the occurrence of a severe allergic reaction including an anaphylactic shock, a drug may remain essential and impossible to replace. This may be the case of insulin in a diabetic patient. We describe the case of an anaphylactic shock to human insulin in whom a desensitization protocol was successfully achieved. A 50-year-old type 2 diabetic man presented one year after initiation of the insulin therapy an anaphylactic shock following the subcutaneous administration of a human insulin containing protamine (Insulatard®). A desensitization protocol to human insulin was performed and allowed to use two human insulin analogues containing no protamine (asparte and glargine), with a two-year event-free follow-up. Positive skin tests with insulin and protamine, and the presence of insulin specific IgE were evidenced of an IgE-mediated mechanism. Desensitization was monitored by skin tests, Maunsell's test, measurement of specific IgE and IgG4, and the basophil activation test. The decrease of basophil sensitivity to insulin is an early marker for tolerance induction. The effectiveness of the desensitization to human insulin underlines the importance to define the modalities of such desensitization protocol and of the monitoring of the tolerance induction. Copyright © 2010 Société nationale française de médecine interne (SNFMI). Published by Elsevier SAS. All rights reserved.

  5. SUMOylation Regulates Insulin Exocytosis Downstream of Secretory Granule Docking in Rodents and Humans

    PubMed Central

    Dai, Xiao-Qing; Plummer, Greg; Casimir, Marina; Kang, Youhou; Hajmrle, Catherine; Gaisano, Herbert Y.; Manning Fox, Jocelyn E.; MacDonald, Patrick E.

    2011-01-01

    OBJECTIVE The reversible attachment of small ubiquitin-like modifier (SUMO) proteins controls target localization and function. We examined an acute role for the SUMOylation pathway in downstream events mediating insulin secretion. RESEARCH DESIGN AND METHODS We studied islets and β-cells from mice and human donors, as well as INS-1 832/13 cells. Insulin secretion, intracellular Ca2+, and β-cell exocytosis were monitored after manipulation of the SUMOylation machinery. Granule localization was imaged by total internal reflection fluorescence and electron microscopy; immunoprecipitation and Western blotting were used to examine the soluble NSF attachment receptor (SNARE) complex formation and SUMO1 interaction with synaptotagmin VII. RESULTS SUMO1 impairs glucose-stimulated insulin secretion by blunting the β-cell exocytotic response to Ca2+. The effect of SUMO1 to impair insulin secretion and β-cell exocytosis is rapid and does not require altered gene expression or insulin content, is downstream of granule docking at the plasma membrane, and is dependent on SUMO-conjugation because the deSUMOylating enzyme, sentrin/SUMO-specific protease (SENP)-1, rescues exocytosis. SUMO1 coimmunoprecipitates with the Ca2+ sensor synaptotagmin VII, and this is transiently lost upon glucose stimulation. SENP1 overexpression also disrupts the association of SUMO1 with synaptotagmin VII and mimics the effect of glucose to enhance exocytosis. Conversely, SENP1 knockdown impairs exocytosis at stimulatory glucose levels and blunts glucose-dependent insulin secretion from mouse and human islets. CONCLUSIONS SUMOylation acutely regulates insulin secretion by the direct and reversible inhibition of β-cell exocytosis in response to intracellular Ca2+ elevation. The SUMO protease, SENP1, is required for glucose-dependent insulin secretion. PMID:21266332

  6. Adipose Cell Size and Regional Fat Deposition as Predictors of Metabolic Response to Overfeeding in Insulin-Resistant and Insulin-Sensitive Humans.

    PubMed

    McLaughlin, Tracey; Craig, Colleen; Liu, Li-Fen; Perelman, Dalia; Allister, Candice; Spielman, Daniel; Cushman, Samuel W

    2016-05-01

    Obesity is associated with insulin resistance, but significant variability exists between similarly obese individuals, pointing to qualitative characteristics of body fat as potential mediators. To test the hypothesis that obese, insulin-sensitive (IS) individuals possess adaptive adipose cell/tissue responses, we measured subcutaneous adipose cell size, insulin suppression of lipolysis, and regional fat responses to short-term overfeeding in BMI-matched overweight/obese individuals classified as IS or insulin resistant (IR). At baseline, IR subjects exhibited significantly greater visceral adipose tissue (VAT), intrahepatic lipid (IHL), plasma free fatty acids, adipose cell diameter, and percentage of small adipose cells. With weight gain (3.1 ± 1.4 kg), IR subjects demonstrated no significant change in adipose cell size, VAT, or insulin suppression of lipolysis and only 8% worsening of insulin-mediated glucose uptake (IMGU). Alternatively, IS subjects demonstrated significant adipose cell enlargement; decrease in the percentage of small adipose cells; increase in VAT, IHL, and lipolysis; 45% worsening of IMGU; and decreased expression of lipid metabolism genes. Smaller baseline adipose cell size and greater enlargement with weight gain predicted decline in IMGU, as did increase in IHL and VAT and decrease in insulin suppression of lipolysis. Weight gain in IS humans causes maladaptive changes in adipose cells, regional fat distribution, and insulin resistance. The correlation between development of insulin resistance and changes in adipose cell size, VAT, IHL, and insulin suppression of lipolysis highlight these factors as potential mediators between obesity and insulin resistance. © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  7. Simultaneous determination and validated quantification of human insulin and its synthetic analogues in human blood serum by immunoaffinity purification and liquid chromatography-mass spectrometry.

    PubMed

    Hess, Cornelius; Thomas, Andreas; Thevis, Mario; Stratmann, Bernd; Quester, Wulf; Tschoepe, Diethelm; Madea, Burkhard; Musshoff, Frank

    2012-10-01

    Possible fatal complications of human insulin and its synthetic analogues like hypoglycemia require precise classification and quantitative determination of these drugs both for clinical purposes as well as for forensic toxicologists. A procedure was developed for the identification and quantification of human insulin and different long-acting as well as short-acting synthetic insulins in human blood serum specimens. After an immunoaffinity purification step and separation by liquid chromatography, the insulins were characterized by their five- or sixfold protonated molecule ions and diagnostic product ions. Clinical samples of 207 diabetic and 50 non-diabetic patients after the administration of human insulin or oral antidiabetics and forensic samples were analyzed for human/synthetic insulin concentrations. The method was validated according to international guidelines. Limits of detection of the insulins ranged between 1.3 and 2.8 μU/ml. Recoveries ranged between 33.2 % and 51.7 %. Precision data was in accordance with international guidelines. Clinical samples showed concentrations of human insulin lower than 301 μU/ml. Our liquid chromatography tandem mass spectrometry procedure allows unambiguous identification and quantification of the intact human insulin and its intact synthetic analogues Humalog®, Novolog®, Apidra®, Lantus®, and Levemir® in human blood serum in clinical and overdose cases. The assay could be successfully tested in patients with diabetes mellitus on therapy with insulins or oral antidiabetics.

  8. Caenorhabditis elegans DAF-2 as a Model for Human Insulin Receptoropathies

    PubMed Central

    Bulger, David A.; Fukushige, Tetsunari; Yun, Sijung; Semple, Robert K.; Hanover, John A.; Krause, Michael W.

    2016-01-01

    Human exome sequencing has dramatically increased the rate of identification of disease-associated polymorphisms. However, examining the functional consequences of those variants has created an analytic bottleneck. Insulin-like signaling in Caenorhabditis elegans has long provided a model to assess consequences of human insulin signaling mutations, but this has not been evaluated in the context of current genetic tools. We have exploited strains derived from the Million Mutation Project (MMP) and gene editing to explore further the evolutionary relationships and conservation between the human and C. elegans insulin receptors. Of 40 MMP alleles analyzed in the C. elegans insulin-like receptor gene DAF-2, 35 exhibited insulin-like signaling indistinguishable from wild-type animals, indicating tolerated mutations. Five MMP alleles proved to be novel dauer-enhancing mutations, including one new allele in the previously uncharacterized C-terminus of DAF-2. CRISPR-Cas9 genome editing was used to confirm the phenotypic consequence of six of these DAF-2 mutations and to replicate an allelic series of known human disease mutations in a highly conserved tyrosine kinase active site residue, demonstrating the utility of C. elegans for directly modeling human disease. Our results illustrate the challenges associated with prediction of the phenotypic consequences of amino acid substitutions, the value of assaying mutant isoform function in vivo, and how recently developed tools and resources afford the opportunity to expand our understanding even of highly conserved regulatory modules such as insulin signaling. This approach may prove generally useful for modeling phenotypic consequences of candidate human pathogenic mutations in conserved signaling and developmental pathways. PMID:27856697

  9. Insulin Restores Gestational Diabetes Mellitus–Reduced Adenosine Transport Involving Differential Expression of Insulin Receptor Isoforms in Human Umbilical Vein Endothelium

    PubMed Central

    Westermeier, Francisco; Salomón, Carlos; González, Marcelo; Puebla, Carlos; Guzmán-Gutiérrez, Enrique; Cifuentes, Fredi; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis

    2011-01-01

    OBJECTIVE To determine whether insulin reverses gestational diabetes mellitus (GDM)–reduced expression and activity of human equilibrative nucleoside transporters 1 (hENT1) in human umbilical vein endothelium cells (HUVECs). RESEARCH DESIGN AND METHODS Primary cultured HUVECs from full-term normal (n = 44) and diet-treated GDM (n = 44) pregnancies were used. Insulin effect was assayed on hENT1 expression (protein, mRNA, SLC29A1 promoter activity) and activity (initial rates of adenosine transport) as well as endothelial nitric oxide (NO) synthase activity (serine1177 phosphorylation, l-citrulline formation). Adenosine concentration in culture medium and umbilical vein blood (high-performance liquid chromatography) as well as insulin receptor A and B expression (quantitative PCR) were determined. Reactivity of umbilical vein rings to adenosine and insulin was assayed by wire myography. Experiments were in the absence or presence of l-NG-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor) or ZM-241385 (an A2A-adenosine receptor antagonist). RESULTS Umbilical vein blood adenosine concentration was higher, and the adenosine- and insulin-induced NO/endothelium-dependent umbilical vein relaxation was lower in GDM. Cells from GDM exhibited increased insulin receptor A isoform expression in addition to the reported NO–dependent inhibition of hENT1-adenosine transport and SLC29A1 reporter repression, and increased extracellular concentration of adenosine and NO synthase activity. Insulin reversed all these parameters to values in normal pregnancies, an effect blocked by ZM-241385 and l-NAME. CONCLUSIONS GDM and normal pregnancy HUVEC phenotypes are differentially responsive to insulin, a phenomenon where insulin acts as protecting factor for endothelial dysfunction characteristic of this syndrome. Abnormal adenosine plasma levels, and potentially A2A-adenosine receptors and insulin receptor A, will play crucial roles in this phenomenon in GDM. PMID:21515851

  10. Leucine modulates dynamic phosphorylation events in insulin signaling pathway and enhances insulin-dependent glycogen synthesis in human skeletal muscle cells

    PubMed Central

    2014-01-01

    Background Branched-chain amino acids, especially leucine, are known to interact with insulin signaling pathway and glucose metabolism. However, the mechanism by which this is exerted, remain to be clearly defined. In order to examine the effect of leucine on muscle insulin signaling, a set of experiments was carried out to quantitate phosphorylation events along the insulin signaling pathway in human skeletal muscle cell cultures. Cells were exposed to insulin, leucine or both, and phosphorylation events of key insulin signaling molecules were tracked over time so as to monitor time-related responses that characterize the signaling events and could be missed by a single sampling strategy limited to pre/post stimulus events. Results Leucine is shown to increase the magnitude of insulin-dependent phosphorylation of protein kinase B (AKT) at Ser473 and glycogen synthase kinase (GSK3β) at Ser21-9. Glycogen synthesis follows the same pattern of GSK3β, with a significant increase at 100 μM leucine plus insulin stimulus. Moreover, data do not show any statistically significant increase of pGSK3β and glycogen synthesis at higher leucine concentrations. Leucine is also shown to increase the magnitude of insulin-mediated extracellularly regulated kinase (ERK) phosphorylation; however, differently from AKT and GSK3β, ERK shows a transient behavior, with an early peak response, followed by a return to the baseline condition. Conclusions These experiments demonstrate a complementary effect of leucine on insulin signaling in a human skeletal muscle cell culture, promoting insulin-activated GSK3β phosphorylation and glycogen synthesis. PMID:24646332

  11. Insulin restores gestational diabetes mellitus-reduced adenosine transport involving differential expression of insulin receptor isoforms in human umbilical vein endothelium.

    PubMed

    Westermeier, Francisco; Salomón, Carlos; González, Marcelo; Puebla, Carlos; Guzmán-Gutiérrez, Enrique; Cifuentes, Fredi; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis

    2011-06-01

    To determine whether insulin reverses gestational diabetes mellitus (GDM)-reduced expression and activity of human equilibrative nucleoside transporters 1 (hENT1) in human umbilical vein endothelium cells (HUVECs). Primary cultured HUVECs from full-term normal (n = 44) and diet-treated GDM (n = 44) pregnancies were used. Insulin effect was assayed on hENT1 expression (protein, mRNA, SLC29A1 promoter activity) and activity (initial rates of adenosine transport) as well as endothelial nitric oxide (NO) synthase activity (serine(1177) phosphorylation, l-citrulline formation). Adenosine concentration in culture medium and umbilical vein blood (high-performance liquid chromatography) as well as insulin receptor A and B expression (quantitative PCR) were determined. Reactivity of umbilical vein rings to adenosine and insulin was assayed by wire myography. Experiments were in the absence or presence of l-N(G)-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor) or ZM-241385 (an A(2A)-adenosine receptor antagonist). Umbilical vein blood adenosine concentration was higher, and the adenosine- and insulin-induced NO/endothelium-dependent umbilical vein relaxation was lower in GDM. Cells from GDM exhibited increased insulin receptor A isoform expression in addition to the reported NO-dependent inhibition of hENT1-adenosine transport and SLC29A1 reporter repression, and increased extracellular concentration of adenosine and NO synthase activity. Insulin reversed all these parameters to values in normal pregnancies, an effect blocked by ZM-241385 and l-NAME. GDM and normal pregnancy HUVEC phenotypes are differentially responsive to insulin, a phenomenon where insulin acts as protecting factor for endothelial dysfunction characteristic of this syndrome. Abnormal adenosine plasma levels, and potentially A(2A)-adenosine receptors and insulin receptor A, will play crucial roles in this phenomenon in GDM.

  12. Endocytotic uptake, processing, and retroendocytosis of human biosynthetic proinsulin by rat fibroblasts transfected with the human insulin receptor gene.

    PubMed Central

    Levy, J R; Ullrich, A; Olefsky, J M

    1988-01-01

    The cellular itinerary and processing of insulin and proinsulin were studied to elucidate possible mechanisms for the observed in vivo differences in the biologic half-lives of these two hormones. A rat fibroblast cell line transfected with a normal human insulin receptor gene was used. Due to gene amplification, the cells express large numbers of receptors and are ideal for studying a ligand, such as proinsulin, that has a low affinity for the insulin receptor. Competitive binding at 4 degrees C showed that the concentration of unlabeled insulin and proinsulin that is needed to displace 50% of tracer insulin or proinsulin was 0.85-0.95 nM and 140-150 nM, respectively. Binding to surface receptors and internalization occur at rates that are four to five times faster in cells incubated with insulin compared with proinsulin. Chloroquine led to an increase in cell-associated radioactivity of approximately 1.4-fold in cells incubated with insulin or proinsulin, but inhibited the appearance of degraded insulin by 54% and degraded proinsulin by only 10%. To study the fate of internalized ligand, cells were incubated with insulin and proinsulin until steady state binding occurred. Surface bound ligand was removed by an acid wash and the remaining cell-associated radioactivity represented internalized ligand. Cells were then reincubated in 37 degrees C buffer and the cell-associated radioactivity and radioactivity released into the medium were analyzed by TCA precipitation, Sephadex G-50, and HPLC. The results demonstrated that proinsulin more readily bypasses the intracellular degradative machinery and is therefore released intact from the cell via the retroendocytotic pathway. These results may help to explain the prolonged metabolic clearance rate and biologic responsiveness of proinsulin in vivo. PMID:3284910

  13. Reversal of diabetes with insulin-producing cells derived in vitro from human pluripotent stem cells.

    PubMed

    Rezania, Alireza; Bruin, Jennifer E; Arora, Payal; Rubin, Allison; Batushansky, Irina; Asadi, Ali; O'Dwyer, Shannon; Quiskamp, Nina; Mojibian, Majid; Albrecht, Tobias; Yang, Yu Hsuan Carol; Johnson, James D; Kieffer, Timothy J

    2014-11-01

    Transplantation of pancreatic progenitors or insulin-secreting cells derived from human embryonic stem cells (hESCs) has been proposed as a therapy for diabetes. We describe a seven-stage protocol that efficiently converts hESCs into insulin-producing cells. Stage (S) 7 cells expressed key markers of mature pancreatic beta cells, including MAFA, and displayed glucose-stimulated insulin secretion similar to that of human islets during static incubations in vitro. Additional characterization using single-cell imaging and dynamic glucose stimulation assays revealed similarities but also notable differences between S7 insulin-secreting cells and primary human beta cells. Nevertheless, S7 cells rapidly reversed diabetes in mice within 40 days, roughly four times faster than pancreatic progenitors. Therefore, although S7 cells are not fully equivalent to mature beta cells, their capacity for glucose-responsive insulin secretion and rapid reversal of diabetes in vivo makes them a promising alternative to pancreatic progenitor cells or cadaveric islets for the treatment of diabetes.

  14. Evidence-based clinical use of insulin premixtures

    PubMed Central

    2013-01-01

    Brazil is expected to have 19.6 million patients with diabetes by the year 2030. A key concept in the treatment of type 2 diabetes mellitus (T2DM) is establishing individualized glycemic goals based on each patient’s clinical characteristics, which impact the choice of antihyperglycemic therapy. Targets for glycemic control, including fasting blood glucose, postprandial blood glucose, and glycated hemoglobin (A1C), are often not reached solely with antihyperglycemic therapy, and insulin therapy is often required. Basal insulin is considered an initial strategy; however, premixed insulins are convenient and are equally or more effective, especially for patients who require both basal and prandial control but desire a more simplified strategy involving fewer daily injections than a basal-bolus regimen. Most physicians are reluctant to transition patients to insulin treatment due to inappropriate assumptions and insufficient information. We conducted a nonsystematic review in PubMed and identified the most relevant and recently published articles that compared the use of premixed insulin versus basal insulin analogues used alone or in combination with rapid-acting insulin analogues before meals in patients with T2DM. These studies suggest that premixed insulin analogues are equally or more effective in reducing A1C compared to basal insulin analogues alone in spite of the small increase in the risk of nonsevere hypoglycemic events and nonclinically significant weight gain. Premixed insulin analogues can be used in insulin-naïve patients, in patients already on basal insulin therapy, and those using basal-bolus therapy who are noncompliant with blood glucose self-monitoring and titration of multiple insulin doses. We additionally provide practical aspects related to titration for the specific premixed insulin analogue formulations commercially available in Brazil. PMID:24011173

  15. A premixed hydrogen/oxygen catalytic igniter

    NASA Technical Reports Server (NTRS)

    Green, James M.

    1989-01-01

    The catalytic ignition of hydrogen and oxygen propellants was studied using a premixing hydrogen/oxygen injector. The premixed injector was designed to eliminate problems associated with catalytic ignition caused by poor propellant mixing in the catalyst bed. Mixture ratio, mass flow rate, and propellant inlet temperature were varied parametrically in testing, and a pulse mode life test of the igniter was conducted. The results of the tests showed that the premixed injector eliminated flame flashback in the reactor and increased the life of the igniter significantly. The results of the experimental program and a comparison with data collected in a previous program are given.

  16. Mitochondrial respiratory capacity and content are normal in young insulin-resistant obese humans.

    PubMed

    Fisher-Wellman, Kelsey H; Weber, Todd M; Cathey, Brook L; Brophy, Patricia M; Gilliam, Laura A A; Kane, Constance L; Maples, Jill M; Gavin, Timothy P; Houmard, Joseph A; Neufer, P Darrell

    2014-01-01

    Considerable debate exists about whether alterations in mitochondrial respiratory capacity and/or content play a causal role in the development of insulin resistance during obesity. The current study was undertaken to determine whether such alterations are present during the initial stages of insulin resistance in humans. Young (∼23 years) insulin-sensitive lean and insulin-resistant obese men and women were studied. Insulin resistance was confirmed through an intravenous glucose tolerance test. Measures of mitochondrial respiratory capacity and content as well as H(2)O(2) emitting potential and the cellular redox environment were performed in permeabilized myofibers and primary myotubes prepared from vastus lateralis muscle biopsy specimens. No differences in mitochondrial respiratory function or content were observed between lean and obese subjects, despite elevations in H(2)O(2) emission rates and reductions in cellular glutathione. These findings were apparent in permeabilized myofibers as well as in primary myotubes. The results suggest that reductions in mitochondrial respiratory capacity and content are not required for the initial manifestation of peripheral insulin resistance.

  17. Mitochondrial Respiratory Capacity and Content Are Normal in Young Insulin-Resistant Obese Humans

    PubMed Central

    Fisher-Wellman, Kelsey H.; Weber, Todd M.; Cathey, Brook L.; Brophy, Patricia M.; Gilliam, Laura A.A.; Kane, Constance L.; Maples, Jill M.; Gavin, Timothy P.; Houmard, Joseph A.; Neufer, P. Darrell

    2014-01-01

    Considerable debate exists about whether alterations in mitochondrial respiratory capacity and/or content play a causal role in the development of insulin resistance during obesity. The current study was undertaken to determine whether such alterations are present during the initial stages of insulin resistance in humans. Young (∼23 years) insulin-sensitive lean and insulin-resistant obese men and women were studied. Insulin resistance was confirmed through an intravenous glucose tolerance test. Measures of mitochondrial respiratory capacity and content as well as H2O2 emitting potential and the cellular redox environment were performed in permeabilized myofibers and primary myotubes prepared from vastus lateralis muscle biopsy specimens. No differences in mitochondrial respiratory function or content were observed between lean and obese subjects, despite elevations in H2O2 emission rates and reductions in cellular glutathione. These findings were apparent in permeabilized myofibers as well as in primary myotubes. The results suggest that reductions in mitochondrial respiratory capacity and content are not required for the initial manifestation of peripheral insulin resistance. PMID:23974920

  18. Cadherin engagement improves insulin secretion of single human β-cells.

    PubMed

    Parnaud, Geraldine; Lavallard, Vanessa; Bedat, Benoît; Matthey-Doret, David; Morel, Philippe; Berney, Thierry; Bosco, Domenico

    2015-03-01

    The aim of this study was to assess whether cadherin-mediated adhesion of human islet cells was affected by insulin secretagogues and explore the role of cadherins in the secretory activity of β-cells. Experiments were carried out with single islet cells adherent to chimeric proteins made of functional E-, N-, or P-cadherin ectodomains fused to the Fc fragment of immunoglobulin (E-cad/Fc, N-cad/Fc, and P-cad/Fc) and immobilized on an inert substrate. We observed that cadherin expression in islet cells was not affected by insulin secretagogues. Adhesion tests showed that islet cells attached to N-cad/Fc and E-cad/Fc acquired, in a time- and secretagogue-dependent manner, a spreading form that was inhibited by blocking cadherin antibodies. By reverse hemolytic plaque assay, we showed that glucose-stimulated insulin secretion of single β-cells was increased by N-cad/Fc and E-cad/Fc adhesion compared with control. In the presence of E-cad/Fc and after glucose stimulation, we showed that total insulin secretion was six times higher in spreading β-cells compared with round β-cells. Furthermore, cadherin-mediated adhesion induced an asymmetric distribution of cortical actin in β-cells. Our results demonstrate that adhesion of β-cells to E- and N-cadherins is regulated by insulin secretagogues and that E- and N-cadherin engagement promotes stimulated insulin secretion.

  19. The human insulin receptor substrate-1 gene (IRS1) is localized on 2q36

    SciTech Connect

    Nishiyama, Masaki; Matsufuji, Senya; Hayashi, Shin-ichi; Furusaka, Akihiro; Tanaka, Teruji ); Inazawa, J.; Nakamura, Yusuke ); Ariyama, Takeshi ); Wands, J.R. )

    1994-03-01

    The chromosomal localization of some of the genes participating in the insulin signaling pathway is known. The insulin and insulin receptor genes have been mapped to chromosomes 11 and 19, respectively. To identify the chromosomal localization of the human IRS1 gene, the fluorescence in situ hybridization technique was employed with Genomic Clone B-10. A total of 50 metaphase cells exhibiting either single or double spots of hybridization signals were examined. Among them, 32 showed the specific signals on 2q36. Therefore, the authors assigned the human IRS1 gene to 2q36. The genes for homeobox sequence (HOX4), fibronectin 1, alkaline phosphatase (intestinal), transition protein 1, villin 1, collagen (type IV), Waardenburg syndrome (type 1), alanine-glyoxylate aminotransferase, and glucagon have been localized in the vicinity of the IRS1 gene.

  20. WNT5A-JNK regulation of vascular insulin resistance in human obesity.

    PubMed

    Farb, Melissa G; Karki, Shakun; Park, Song-Young; Saggese, Samantha M; Carmine, Brian; Hess, Donald T; Apovian, Caroline; Fetterman, Jessica L; Bretón-Romero, Rosa; Hamburg, Naomi M; Fuster, José J; Zuriaga, María A; Walsh, Kenneth; Gokce, Noyan

    2016-12-01

    Obesity is associated with the development of vascular insulin resistance; however, pathophysiological mechanisms are poorly understood. We sought to investigate the role of WNT5A-JNK in the regulation of insulin-mediated vasodilator responses in human adipose tissue arterioles prone to endothelial dysfunction. In 43 severely obese (BMI 44±11 kg/m(2)) and five metabolically normal non-obese (BMI 26±2 kg/m(2)) subjects, we isolated arterioles from subcutaneous and visceral fat during planned surgeries. Using videomicroscopy, we examined insulin-mediated, endothelium-dependent vasodilator responses and characterized adipose tissue gene and protein expression using real-time polymerase chain reaction and Western blot analyses. Immunofluorescence was used to quantify endothelial nitric oxide synthase (eNOS) phosphorylation. Insulin-mediated vasodilation was markedly impaired in visceral compared to subcutaneous vessels from obese subjects (p<0.001), but preserved in non-obese individuals. Visceral adiposity was associated with increased JNK activation and elevated expression of WNT5A and its non-canonical receptors, which correlated negatively with insulin signaling. Pharmacological JNK antagonism with SP600125 markedly improved insulin-mediated vasodilation by sixfold (p<0.001), while endothelial cells exposed to recombinant WNT5A developed insulin resistance and impaired eNOS phosphorylation (p<0.05). We observed profound vascular insulin resistance in the visceral adipose tissue arterioles of obese subjects that was associated with up-regulated WNT5A-JNK signaling and impaired endothelial eNOS activation. Pharmacological JNK antagonism markedly improved vascular endothelial function, and may represent a potential therapeutic target in obesity-related vascular disease. © The Author(s) 2016.

  1. Cavitation-enhanced delivery of insulin in agar and porcine models of human skin

    NASA Astrophysics Data System (ADS)

    Feiszthuber, Helga; Bhatnagar, Sunali; Gyöngy, Miklós; Coussios, Constantin-C.

    2015-03-01

    Ultrasound-assisted transdermal insulin delivery offers a less painful and less invasive alternative to subcutaneous insulin injections. However, ultrasound-based drug delivery, otherwise known as sonophoresis, is a highly variable phenomenon, in part dependent on cavitation. The aim of the current work is to investigate the role of cavitation in transdermal insulin delivery. Fluorescently stained, soluble Actrapid insulin was placed on the surface of human skin-mimicking materials subjected to 265 kHz, 10% duty cycle focused ultrasound. A confocally and coaxially aligned 5 MHz broadband ultrasound transducer was used to detect cavitation. Two different skin models were used. The first model, 3% agar hydrogel, was insonated with a range of pressures (0.25-1.40 MPa peak rarefactional focal pressure—PRFP), with and without cavitation nuclei embedded within the agar at a concentration of 0.05% w/v. The second, porcine skin was insonated at 1.00 and 1.40 MPa PRFP. In both models, fluorescence measurements were used to determine penetration depth and concentration of delivered insulin. Results show that in agar gel, both insulin penetration depth and concentration only increased significantly in the presence of inertial cavitation, with up to a 40% enhancement. In porcine skin the amount of fluorescent insulin was higher in the epidermis of those samples that were exposed to ultrasound compared to the control samples, but there was no significant increase in penetration distance. The results underline the importance of instigating and monitoring inertial cavitation during transdermal insulin delivery.

  2. Computational model of cellular metabolic dynamics: effect of insulin on glucose disposal in human skeletal muscle

    PubMed Central

    Li, Yanjun; Solomon, Thomas P. J.; Haus, Jacob M.; Saidel, Gerald M.; Cabrera, Marco E.

    2010-01-01

    Identifying the mechanisms by which insulin regulates glucose metabolism in skeletal muscle is critical to understanding the etiology of insulin resistance and type 2 diabetes. Our knowledge of these mechanisms is limited by the difficulty of obtaining in vivo intracellular data. To quantitatively distinguish significant transport and metabolic mechanisms from limited experimental data, we developed a physiologically based, multiscale mathematical model of cellular metabolic dynamics in skeletal muscle. The model describes mass transport and metabolic processes including distinctive processes of the cytosol and mitochondria. The model simulated skeletal muscle metabolic responses to insulin corresponding to human hyperinsulinemic-euglycemic clamp studies. Insulin-mediated rate of glucose disposal was the primary model input. For model validation, simulations were compared with experimental data: intracellular metabolite concentrations and patterns of glucose disposal. Model variations were simulated to investigate three alternative mechanisms to explain insulin enhancements: Model 1 (M.1), simple mass action; M.2, insulin-mediated activation of key metabolic enzymes (i.e., hexokinase, glycogen synthase, pyruvate dehydrogenase); or M.3, parallel activation by a phenomenological insulin-mediated intracellular signal that modifies reaction rate coefficients. These simulations indicated that models M.1 and M.2 were not sufficient to explain the experimentally measured metabolic responses. However, by application of mechanism M.3, the model predicts metabolite concentration changes and glucose partitioning patterns consistent with experimental data. The reaction rate fluxes quantified by this detailed model of insulin/glucose metabolism provide information that can be used to evaluate the development of type 2 diabetes. PMID:20332360

  3. [Solid state isotope hydrogen exchange for deuterium and tritium in human gene-engineered insulin].

    PubMed

    Zolotarev, Yu A; Dadayan, A K; Kozik, V S; Gasanov, E V; Nazimov, I V; Ziganshin, R Kh; Vaskovsky, B V; Murashov, A N; Ksenofontov, A L; Haribin, O N; Nikolaev, E N; Myasoedov, N F

    2014-01-01

    The reaction of high temperature solid state catalytic isotope exchange in peptides and proteins under the action of catalyst-activated spillover hydrogen was studied. The reaction of human gene-engineered insulin with deuterium and tritium was conducted at 120-140° C to produce insulin samples containing 2-6 hydrogen isotope atoms. To determine the distribution of the isotope label over tritium-labeled insulin's amino acid residues, oxidation of the S-S bonds of insulin by performic acid was performed and polypeptide chains isolated; then their acid hydrolysis, amino acid analysis and liquid scintillation counts of tritium in the amino acids were conducted. The isotope label was shown to be incorporated in all amino acids of the protein, with the peptide fragment FVNQHLCGSHLVE of the insulin β-chain showing the largest incorporation. About 45% of the total protein isotope label was incorporated in His5 and His10 of this fragment. For the analysis of isotope label distribution in labeled insulin's peptide fragments, the recovery of the S-S bonds by mercaptoethanol, the enzymatic hydrolysis by glutamyl endopeptidase from Bacillus intermedius and HPLC division of the resulting peptides were carried out. Attribution of the peptide fragments formed due to hydrolysis at the Glu-X bond in the β-chain was accomplished by mass spectrometry. Mass spectrometry analysis data of the deuterium-labeled insulin samples' isotopomeric composition showed that the studied solid state isotope exchange reaction equally involved all the protein molecules. Biological studying of tritium-labeled insulin showed its physiological activity to be completely retained.

  4. The Investigation of ADAMTS16 in Insulin-Induced Human Chondrosarcoma Cells

    PubMed Central

    Comertoglu, Ismail; Firat, Ridvan; Erdemli, Haci Kemal; Kursunlu, S. Fatih; Akyol, Sumeyya; Ugurcu, Veli; Altuntas, Aynur; Adam, Bahattin; Demircan, Kadir

    2015-01-01

    Abstract Objectives: A disintegrin-like metalloproteinase with thrombospondin motifs (ADAMTS) is a group of proteins that have enzymatic activity secreted by cells to the outside extracellular matrix. Insulin induces proteoglycan biosynthesis in chondrosarcoma chondrocytes. The purpose of the present in vitro study is to assess the time course effects of insulin on ADAMTS16 expression in OUMS-27 (human chondrosarcoma) cell line to examine whether insulin regulates ADAMTS16 expression as well as proteoglycan biosynthesis with multifaceted properties or not. Methods: Chondrosarcoma cells were cultured in Dulbecco's modified Eagle's medium having either 10 μg/mL insulin or not. While the experiment was going on, the medium containing insulin had been changed every other day. Cells were harvested at 1st, 3rd, 7th, and 11th days; subsequently, RNA and proteins were isolated in every experimental group according to their time interval. RNA expression of ADAMTS was estimated by quantitative real-time polymerase chain reaction (qRT-PCR) by using primers. Immunoreactive protein levels were encountered by the western blot protein detection technique by using proper anti-ADAMTS16 antibodies. Results: ADAMTS16 mRNA expression level of chondrosarcoma cells was found to be insignificantly decreased in chondrosarcoma cells induced by insulin detected by the qRT-PCR instrument. On the other hand, there was a gradual decrease in immune-reactant ADAMTS16 protein amount by the time course in insulin-treated cell groups when compared with control cells. Conclusion: It has been suggested that insulin might possibly regulate ADAMTS16 levels/activities in OUMS-27 chondrosarcoma cells taking a role in extracellular matrix turnover. PMID:26181853

  5. Cavitation-enhanced delivery of insulin in agar and porcine models of human skin.

    PubMed

    Feiszthuber, Helga; Bhatnagar, Sunali; Gyöngy, Miklós; Coussios, Constantin-C

    2015-03-21

    Ultrasound-assisted transdermal insulin delivery offers a less painful and less invasive alternative to subcutaneous insulin injections. However, ultrasound-based drug delivery, otherwise known as sonophoresis, is a highly variable phenomenon, in part dependent on cavitation. The aim of the current work is to investigate the role of cavitation in transdermal insulin delivery. Fluorescently stained, soluble Actrapid insulin was placed on the surface of human skin-mimicking materials subjected to 265 kHz, 10% duty cycle focused ultrasound. A confocally and coaxially aligned 5 MHz broadband ultrasound transducer was used to detect cavitation. Two different skin models were used. The first model, 3% agar hydrogel, was insonated with a range of pressures (0.25-1.40 MPa peak rarefactional focal pressure-PRFP), with and without cavitation nuclei embedded within the agar at a concentration of 0.05% w/v. The second, porcine skin was insonated at 1.00 and 1.40 MPa PRFP. In both models, fluorescence measurements were used to determine penetration depth and concentration of delivered insulin. Results show that in agar gel, both insulin penetration depth and concentration only increased significantly in the presence of inertial cavitation, with up to a 40% enhancement. In porcine skin the amount of fluorescent insulin was higher in the epidermis of those samples that were exposed to ultrasound compared to the control samples, but there was no significant increase in penetration distance. The results underline the importance of instigating and monitoring inertial cavitation during transdermal insulin delivery.

  6. Short-Term Aerobic Exercise Training in Obese Humans with Type 2 Diabetes Mellitus Improves Whole-Body Insulin Sensitivity through Gains in Peripheral, not Hepatic Insulin Sensitivity

    PubMed Central

    Winnick, Jason J.; Sherman, W. Michael; Habash, Diane L.; Stout, Michael B.; Failla, Mark L.; Belury, Martha A.; Schuster, Dara P.

    2008-01-01

    Context: Short-term aerobic exercise training can improve whole-body insulin sensitivity in humans with type 2 diabetes mellitus; however, the contributions of peripheral and hepatic tissues to these improvements are not known. Objective: Our objective was to determine the effect of 7-d aerobic exercise training on peripheral and hepatic insulin sensitivity during isoglycemic/hyperinsulinemic clamp conditions. Design: Subjects were randomly assigned to one of two groups. The energy balance group consumed an isocaloric diet consisting of 50% carbohydrate, 30% fat, and 20% protein for 15 d. The energy balance plus exercise group consumed a similar diet over the 15 d and performed 50-min of treadmill walking at 70% of maximum oxygen consumption maximum during the second 7 d of the 15-d study period. Each subject underwent an initial isoglycemic/hyperinsulinemic clamp after 1-wk dietary control and a second clamp after completing the study. Setting: The study was performed at Ohio State University’s General Clinical Research Center. Participants: There were 18 obese, mildly diabetic humans included in the study. Intervention: Aerobic exercise training was performed for 7 d. Main Outcome Measures: Whole-body, peripheral, and hepatic insulin sensitivity were measured. Results: Exercise training did not have an impact on peripheral glucose uptake or endogenous glucose production during the basal state or low-dose insulin. Likewise, it did not alter endogenous glucose production during high-dose insulin. However, 1-wk of exercise training increased both whole-body (P < 0.05) and peripheral insulin sensitivity (P < 0.0001) during high-dose insulin. Conclusion: Improvements to whole body insulin sensitivity after short-term aerobic exercise training are due to gains in peripheral, not heptic insulin sensitivity. PMID:18073312

  7. Differentiation of human-induced pluripotent stem cells into insulin-producing clusters.

    PubMed

    Shaer, Anahita; Azarpira, Negar; Vahdati, Akbar; Karimi, Mohammad Hosein; Shariati, Mehrdad

    2015-02-01

    In diabetes mellitus type 1, beta cells are mostly destroyed; while in diabetes mellitus type 2, beta cells are reduced by 40% to 60%. We hope that soon, stem cells can be used in diabetes therapy via pancreatic beta cell replacement. Induced pluripotent stem cells are a kind of stem cell taken from an adult somatic cell by "stimulating" certain genes. These induced pluripotent stem cells may be a promising source of cell therapy. This study sought to produce isletlike clusters of insulin-producing cells taken from induced pluripotent stem cells. A human-induced pluripotent stem cell line was induced into isletlike clusters via a 4-step protocol, by adding insulin, transferrin, and selenium (ITS), N2, B27, fibroblast growth factor, and nicotinamide. During differentiation, expression of pancreatic β-cell genes was evaluated by reverse transcriptase-polymerase chain reaction; the morphologic changes of induced pluripotent stem cells toward isletlike clusters were observed by a light microscope. Dithizone staining was used to stain these isletlike clusters. Insulin produced by these clusters was evaluated by radio immunosorbent assay, and the secretion capacity was analyzed with a glucose challenge test. Differentiation was evaluated by analyzing the morphology, dithizone staining, real-time quantitative polymerase chain reaction, and immunocytochemistry. Gene expression of insulin, glucagon, PDX1, NGN3, PAX4, PAX6, NKX6.1, KIR6.2, and GLUT2 were documented by analyzing real-time quantitative polymerase chain reaction. Dithizone-stained cellular clusters were observed after 23 days. The isletlike clusters significantly produced insulin. The isletlike clusters could increase insulin secretion after a glucose challenge test. This work provides a model for studying the differentiation of human-induced pluripotent stem cells to insulin-producing cells.

  8. Tyrosine-specific phosphorylation of calmodulin by the insulin receptor kinase purified from human placenta.

    PubMed Central

    Sacks, D B; Fujita-Yamaguchi, Y; Gale, R D; McDonald, J M

    1989-01-01

    It has previously been demonstrated that calmodulin can be phosphorylated in vitro and in vivo by both tyrosine-specific and serine/threonine protein kinase. We demonstrate here that the insulin receptor tyrosine kinase purified from human placenta phosphorylates calmodulin. The highly purified receptors (prepared by insulin-Sepharose chromatography) were 5-10 times more effective in catalysing the phosphorylation of calmodulin than an equal number of partially purified receptors (prepared by wheat-germ agglutinin-Sepharose chromatography). Phosphorylation occurred exclusively on tyrosine residues, up to a maximum of 1 mol [0.90 +/- 0.14 (n = 5)] of phosphate incorporated/mol of calmodulin. Phosphorylation of calmodulin was dependent on the presence of certain basic proteins and divalent cations. Some of these basic proteins, i.e. polylysine, polyarginine, polyornithine, protamine sulphate and histones H1 and H2B, were also able to stimulate the phosphorylation of calmodulin via an insulin-independent activation of the receptor tyrosine kinase. Addition of insulin further increased incorporation of 32P into calmodulin. The magnitude of the effect of insulin was dependent on the concentration and type of basic protein used, ranging from 0.5- to 9.0-fold stimulation. Maximal phosphorylation of calmodulin was obtained at an insulin concentration of 10(-10) M, with half-maximal effect at 10(-11) M. Either Mg2+ or Mn2+ was necessary to obtain phosphorylation, but Mg2+ was far more effective than Mn2+. In contrast, maximal phosphorylation of calmodulin was observed in the absence of Ca2+. Inhibition of phosphorylation was observed as free Ca2+ concentration exceeded 0.1 microM, with almost complete inhibition at 30 microM free Ca2+. The Km for calmodulin was approx. 0.1 microM. To gain further insight into the effects of basic proteins in this system, we examined the binding of calmodulin to the insulin receptor and the polylysine. Calmodulin binds to the insulin

  9. Human pituitary and placental hormones control human insulin-like growth factor II secretion in human granulosa cells

    SciTech Connect

    Ramasharma, K.; Li, C.H.

    1987-05-01

    Human granulosa cells cultured with calf serum actively proliferated for 18-20 generations and secreted progesterone into the medium; progesterone levels appeared to decline with increase in generation number. Cells cultured under serum-free conditions secreted significant amounts of progesterone and insulin-like growth factor II (IGF-II). The progesterone secretion was enhanced by the addition of human follitropin, lutropin, and chorionic gonadotropin but not by growth hormone. These cells, when challenged to varying concentrations of human growth hormone, human chorionic somatomammotropin, human prolactin, chorionic gonadotropin, follitropin, and lutropin, secreted IGF-II into the medium as measured by specific IGF-II RIA. Among these human hormones, chorionic gonadotropin, follitropin, and lutropin were most effective in inducing IGF-II secretion from these cells. When synthetic lutropin-releasing hormone and ..cap alpha..-inhibin-92 were tested, only lutropin-releasing hormone was effective in releasing IGF-II. The results described suggest that cultured human granulosa cells can proliferate and actively secrete progesterone and IGF-II into the medium. IGF-II production in human granulosa cells was influenced by a multi-hormonal complex including human growth hormone, human chorionic somatomammotropin, and prolactin.

  10. Different metabolic responses of human brown adipose tissue to activation by cold and insulin.

    PubMed

    Orava, Janne; Nuutila, Pirjo; Lidell, Martin E; Oikonen, Vesa; Noponen, Tommi; Viljanen, Tapio; Scheinin, Mika; Taittonen, Markku; Niemi, Tarja; Enerbäck, Sven; Virtanen, Kirsi A

    2011-08-03

    We investigated the metabolism of human brown adipose tissue (BAT) in healthy subjects by determining its cold-induced and insulin-stimulated glucose uptake and blood flow (perfusion) using positron emission tomography (PET) combined with computed tomography (CT). Second, we assessed gene expression in human BAT and white adipose tissue (WAT). Glucose uptake was induced 12-fold in BAT by cold, accompanied by doubling of perfusion. We found a positive association between whole-body energy expenditure and BAT perfusion. Insulin enhanced glucose uptake 5-fold in BAT independently of its perfusion, while the effect on WAT was weaker. The gene expression level of insulin-sensitive glucose transporter GLUT4 was also higher in BAT as compared to WAT. In conclusion, BAT appears to be differently activated by insulin and cold; in response to insulin, BAT displays high glucose uptake without increased perfusion, but when activated by cold, it dissipates energy in a perfusion-dependent manner. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Premixed autoignition in compressible turbulence

    NASA Astrophysics Data System (ADS)

    Konduri, Aditya; Kolla, Hemanth; Krisman, Alexander; Chen, Jacqueline

    2016-11-01

    Prediction of chemical ignition delay in an autoignition process is critical in combustion systems like compression ignition engines and gas turbines. Often, ignition delay times measured in simple homogeneous experiments or homogeneous calculations are not representative of actual autoignition processes in complex turbulent flows. This is due the presence of turbulent mixing which results in fluctuations in thermodynamic properties as well as chemical composition. In the present study the effect of fluctuations of thermodynamic variables on the ignition delay is quantified with direct numerical simulations of compressible isotropic turbulence. A premixed syngas-air mixture is used to remove the effects of inhomogeneity in the chemical composition. Preliminary results show a significant spatial variation in the ignition delay time. We analyze the topology of autoignition kernels and identify the influence of extreme events resulting from compressibility and intermittency. The dependence of ignition delay time on Reynolds and turbulent Mach numbers is also quantified. Supported by Basic Energy Sciences, Dept of Energy, United States.

  12. Production of transgenic tilapia with Brockmann bodies secreting [desThrB30] human insulin.

    PubMed

    Pohajdak, Bill; Mansour, Marc; Hrytsenko, Olga; Conlon, J Michael; Dymond, L Clayton; Wright, James R

    2004-08-01

    Tilapia are commercially important tropical fish which, like many teleosts, have anatomically discrete islet organs called Brockmann bodies. When transplanted into diabetic nude mice, tilapia islets provide long-term normoglycemia and mammalian-like glucose tolerance profiles. Using site-directed mutagenesis and linker ligation we have "humanized" the tilapia insulin gene so that it codes for [desThrB30] human insulin while maintaining the tilapia regulatory sequences. Following microinjection into fertilized eggs, we screened DNA isolated from whole fry shortly after hatching by PCR. Positive fish were grown to sexual maturity and mated to wild-types and positive Fl's were further characterized. Human insulin was detected in both serum and in the clusters of beta cells scattered throughout the Brockmann bodies. Surrounding non-beta cells as well as other tissues were negative indicating beta cell specific expression. Purification and sequencing of both A-and B-chains verified that the insulin was properly processed and humanized. After extensive characterization, transgenic tilapia could become a suitable, inexpensive source of islet tissue that can be easily mass-produced for clinical islet xenotransplantation. Because tilapia islets are exceedingly resistant to hypoxia by mammalian standards, transgenic tilapia islets should be ideal for xenotransplantation using immunoisolation techniques.

  13. Dose-dependent insulin regulation of insulin-like growth factor binding protein-1 in human endometrial stromal cells is mediated by distinct signaling pathways.

    PubMed

    Lathi, R B; Hess, A P; Tulac, S; Nayak, N R; Conti, M; Giudice, L C

    2005-03-01

    IGF binding protein-1 (IGFBP-1) is a major product of decidualized human endometrial stromal cells and decidua, and as a modulator of IGF action and/or by independent mechanisms, it regulates cell growth and differentiation and embryonic implantation in these tissues. IGFBP-1 secretion is primarily stimulated by progesterone and cAMP and is inhibited by insulin and IGFs. The signaling pathways mediating the latter are not well defined, and the current study was conducted to determine which pathways mediate the effects of insulin on IGFBP-1 mRNA and protein expression by human endometrial stromal cells decidualized in vitro by progesterone. Cells were cultured and treated with different combinations of insulin; wortmannin, an inhibitor of the phosphatidylinositide-3-kinase (PI3-kinase) pathway; and PD98059, an inhibitor of the MAPK pathway. IGFBP-1 mRNA was determined by real-time PCR, and protein secretion in the conditioned medium was measured by ELISA. Activation of the PI3-kinase and the MAPK pathways was assessed by the detection of phosphorylated AKT and ERK in Western blots, respectively. Insulin inhibited IGFBP-1 mRNA and protein secretion in a dose-dependent fashion, with an ED(50) for the latter 0.127 ng/ml (21.6 pm). Inhibitor studies revealed that at low doses, insulin acts through the PI3-kinase pathway, whereas at higher levels it also activates the MAPK pathway in the inhibition of IGFBP-1. The data demonstrate that human endometrium is a target for insulin action in the regulation of IGFBP-1. At physiological levels insulin likely plays a homeostatic role for energy metabolism in the endometrium, and in hyperinsulinemic states, insulin action on the endometrium may activate cellular mitosis via the MAPK pathway and perhaps predispose this tissue to hyperplasia and/or cancer.

  14. LEM-CF Premixed Tool Kit

    SciTech Connect

    2015-01-19

    The purpose of LEM-CF Premixed Tool Kit is to process premixed flame simulation data from the LEM-CF solver (https://fileshare.craft-tech.com/clusters/view/lem-cf) into a large-eddy simulation (LES) subgrid model database. These databases may be used with a user-defined-function (UDF) that is included in the Tool Kit. The subgrid model UDF may be used with the ANSYS FLUENT flow solver or other commercial flow solvers.

  15. Insulin regulates GLUT1-mediated glucose transport in MG-63 human osteosarcoma cells.

    PubMed

    Cifuentes, Manuel; García, Maria A; Arrabal, Pilar M; Martínez, Fernando; Yañez, María J; Jara, Nery; Weil, Bernardo; Domínguez, Dolores; Medina, Rodolfo A; Nualart, Francisco

    2011-06-01

    Osteosarcoma is the most common type of malignant bone cancer, accounting for 35% of primary bone malignancies. Because cancer cells utilize glucose as their primary energy substrate, the expression and regulation of glucose transporters (GLUT) may be important in tumor development and progression. GLUT expression has not been studied previously in human osteosarcoma cell lines. Furthermore, although insulin and insulin-like growth factor (IGF-I) play an important role in cell proliferation and tumor progression, the role of these hormones on GLUT expression and glucose uptake, and their possible relation to osteosarcoma, have also not been studied. We determined the effect of insulin and IGF-I on GLUT expression and glucose transport in three well-characterized human osteosarcoma cell lines (MG-63, SaOs-2, and U2-Os) using immunocytochemical, RT-PCR and functional kinetic analyses. Furthermore we also studied GLUT isoform expression in osteosarcoma primary tumors and metastases by in situ hybridization and immunohistochemical analyses. RT-PCR and immunostaining show that GLUT1 is the main isoform expressed in the cell lines and tissues studied, respectively. Immunocytochemical analysis shows that although insulin does not affect levels of GLUT1 expression it does induce a translocation of the transporter to the plasma membrane. This translocation is associated with increased transport of glucose into the cell. GLUT1 is the main glucose transporter expressed in osteosarcoma, furthermore, this transporter is regulated by insulin in human MG-63 cells. One possible mechanism through which insulin is involved in cancer progression is by increasing the amount of glucose available to the cancer cell.

  16. Differentiation of human adipose stromal cells in vitro into insulin-sensitive adipocytes.

    PubMed

    Huttala, Outi; Mysore, R; Sarkanen, J R; Heinonen, T; Olkkonen, V M; Ylikomi, T

    2016-10-01

    Adipose tissue-related diseases such as obesity and type 2 diabetes are worldwide epidemics. In order to develop adipose tissue cultures in vitro that mimic more faithfully the in vivo physiology, new well-characterized and publicly accepted differentiation methods of human adipose stem cells are needed. The aims of this study are (1) to improve the existing natural adipose tissue extract (ATE)-based induction method and (2) to study the effects of a differentiation method on insulin responsiveness of the resulting adipocytes. Different induction media were applied on human adipose stromal cell (hASC) monocultures to study the differentiation capacity of the induction media and the functionality of the differentiated adipocytes. Cells were differentiated for 14 days to assess triglyceride accumulation per cell and adipocyte-specific gene expression (PPARγ, adiponectin, AP2, leptin, Glut4, Prdm16, CIDEA, PGC1-α, RIP140, UCP and ADCY5). Insulin response was studied by measuring glucose uptake and inhibition of lipolysis after incubation with 100 or 500 nM insulin. The selected differentiation method included a 3-day induction with ATE, 6 days in serum-free medium supplemented with 1.15 μM insulin and 9.06 μM Troglitazone, followed by 4 days in a defined serum- and insulin-free stimulation medium. This protocol induced prominent general adipocyte gene expression, including markers for both brown and white adipocytes and triglyceride accumulation. Moreover, the cells were sensitive to insulin as observed from increased glucose uptake and inhibition of lipolysis. This differentiation protocol provides a promising approach for the induction of hASC adipogenesis to obtain functional and mature human adipocytes.

  17. Premixed turbulent flame propagation in microgravity

    NASA Technical Reports Server (NTRS)

    Menon, S.; Jagoda, J.; Sujith, R.

    1995-01-01

    To reduce pollutant formation there is, at present, an increased interest in employing premixed fuel/air mixture in combustion devices. It is well known that greater control over local temperature can be achieved with premixed flames and with lean premixed mixtures, significant reduction of pollutants such as NO(x) can be achieved. However, an issue that is still unresolved is the predictability of the flame propagation speed in turbulent premixed mixtures, especially in lean mixtures. Although substantial progress has been made in recent years, there is still no direct verification that flame speeds in turbulent premixed flows are highly predictable in complex flow fields found in realistic combustors. One of the problems associated with experimental verification is the difficulty in obtaining access to all scales of motion in typical high Reynolds number flows, since, such flows contain scales of motion that range from the size of the device to the smallest Kolmogorov scale. The overall objective of this study is to characterize the behavior of turbulent premixed flames at reasonable high Reynolds number, Re(sub L). Of particular interest here is the thin flame limit where the laminar flame thickness is much smaller than the Kolmogorov scale. Thin flames occur in many practical combustion devices and will be numerically studied using a recently developed new formulation that is briefly described.

  18. Interferon alpha impairs insulin production in human beta cells via endoplasmic reticulum stress.

    PubMed

    Lombardi, Angela; Tomer, Yaron

    2017-02-23

    Despite substantial advances in the research exploring the pathogenesis of Type 1 Diabetes (T1D), the pathophysiological mechanisms involved remain unknown. We hypothesized in this study that interferon alpha (IFNα) participates in the early stages of T1D development by triggering endoplasmic reticulum (ER) stress. To verify our hypothesis, human islets and human EndoC-βH1 cells were exposed to IFNα and tested for ER stress markers, glucose stimulated insulin secretion (GSIS) and insulin content. IFNα treatment induced upregulation of ER stress markers including Binding immunoglobulin Protein, phospho-eukaryotic translation initiation factor 2α, spliced- X-box binding protein-1, C/EBP homologous protein and activating transcription factor 4. Intriguingly, IFNα treatment did not impair GSIS but significantly decreased insulin production in both human islets and EndoC-βH1 cells. Furthermore, IFNα decreased the expression of both proinsulin convertase 1 and proinsulin convertase 2, suggesting an altered functional state of the beta cells characterized by a slower proinsulin-insulin conversion. Pretreatment of both human islets and EndoC-βH1 cells with chemical chaperones 4-phenylbutyric acid and tauroursodeoxycholic acid completely prevented IFNα effects, indicating an ER stress-mediated impairment of insulin production. We demonstrated for the first time that IFNα elicits ER stress in human beta cells providing a novel mechanistic role for this virus-induced cytokine in the development of T1D. Compounds targeting molecular processes altered in ER-stressed beta cells could represent a potential therapeutic strategy to prevent IFNα-induced beta cell dysfunction in the early onset of T1D.

  19. Epigallocatechin gallate (EGCG) attenuates high glucose-induced insulin signaling blockade in human hepG2 hepatoma cells.

    PubMed

    Lin, Chih-Li; Lin, Jen-Kun

    2008-08-01

    Insulin resistance is the primary characteristic of type 2 diabetes which as a result of insulin signaling defects. It has been suggested that the tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) displays some antidiabetic effects, but the mechanism for EGCG insulin-enhancing effects is incompletely understood. In the present study, the investigations of EGCG on insulin signaling are performed in insulin-responsive human HepG2 cells cotreated with high glucose. We found that the high glucose condition causes significant increasing Ser307 phosphorylation of insulin receptor substrate-1 (IRS-1), leading to reduce insulin-stimulated phosphorylation of Akt. As the results, the insulin metabolic effects of glycogen synthesis and glucose uptake are inhibited by high glucose. However, the treatment of EGCG improves insulin-stimulated downsignaling by reducing IRS-1 Ser307 phosphorylation. Furthermore, we also demonstrated these EGCG effects are essential depends on the 5'-AMP-activated protein kinase (AMPK) activation. Together, our data suggest a putative link between high glucose and insulin resistance in HepG2 cells, and the EGCG treatment attenuates insulin signaling blockade by reducing IRS-1 Ser307 phosphorylation through the AMPK activation pathway.

  20. Solution structure of human insulin-like growth factor II; recognition sites for receptors and binding proteins.

    PubMed Central

    Terasawa, H; Kohda, D; Hatanaka, H; Nagata, K; Higashihashi, N; Fujiwara, H; Sakano, K; Inagaki, F

    1994-01-01

    The three-dimensional structure of human insulin-like growth factor II was determined at high resolution in aqueous solution by NMR and simulated annealing based calculations. The structure is quite similar to those of insulin and insulin-like growth factor I, which consists of an alpha-helix followed by a turn and a strand in the B-region and two antiparallel alpha-helices in the A-region. However, the regions of Ala1-Glu6, Pro31-Arg40 and Thr62-Glu67 are not well-defined for lack of distance constraints, possibly due to motional flexibility. Based on the resultant structure and the results of structure-activity relationships, we propose the interaction sites of insulin-like growth factor II with the type 2 insulin-like growth factor receptor and the insulin-like growth factor binding proteins. These sites partially overlap with each other at the opposite side of the putative binding surface to the insulin receptor and the type 1 insulin-like growth factor receptor. We also discuss the interaction modes of insulin-like growth factor II with the insulin receptor and the type 1 insulin-like growth factor receptor. Images PMID:7527339

  1. A human model of dietary saturated fatty acid induced insulin resistance.

    PubMed

    Koska, Juraj; Ozias, Marlies K; Deer, James; Kurtz, Julie; Salbe, Arline D; Harman, S Mitchell; Reaven, Peter D

    2016-11-01

    Increased consumption of high-fat diets is associated with the development of insulin resistance and type 2 diabetes. Current models to study the mechanisms of high-fat diet-induced IR in humans are limited by their long duration or low efficacy. In the present study we developed and characterized an acute dietary model of saturated fatty acid-enriched diet induced insulin resistance. High caloric diets enriched with saturated fatty acids (SFA) or carbohydrates (CARB) were evaluated in subjects with normal and impaired glucose tolerance (NGT or IGT). Both diets were compared to a standard eucaloric American Heart Association (AHA) control diet in a series of crossover studies. Whole body insulin resistance was estimated as steady state plasma glucose (SSPG) concentrations during the last 30min of a 3-h insulin suppression test. SSPG was increased after a 24-h SFA diet (by 83±74% vs. control, n=38) in the entire cohort, which was comprised of participants with NGT (92±82%, n=22) or IGT (65±55%, n=16) (all p<0.001). SSPG was also increased after a single SFA breakfast (55±32%, p=0.008, n=7). The increase in SSPG was less pronounced after an overnight fast following a daylong SFA diet (24±31%, p=0.04, n=10), and further attenuated 24h after returning to the control diet (19±35%, p=0.09, n=11). SSPG was not increased after a 24-h CARB diet (26±50%, p=0.11, n=12). A short-term SFA-enriched diet induced whole body insulin resistance in both NGT and IGT subjects. Insulin resistance persisted overnight after the last SFA meal and was attenuated by one day of a healthy diet. This model offers opportunities for identifying early mechanisms and potential treatments of dietary saturated fat induced insulin resistance. Published by Elsevier Inc.

  2. Effect of insulin on D-glucose transport by human placental brush border membranes.

    PubMed

    Brunette, M G; Lajeunesse, D; Leclerc, M; Lafond, J

    1990-02-12

    We studied the effect of insulin on the uptake of D-glucose by human placental brush border membranes (BBM) in vitro. D-glucose transport through placental BBM is a Na(+)-independent transport, inhibited by 0.5 mM phloretin. Increasing the substrate concentration from 1 to 50 mM resulted in an increase in glucose uptake according to an S-shaped relationship. Hill plot analysis suggests that at least two molecules of D-glucose are transported at the same time by the carrier. Preincubation of the placental tissue with insulin for 45 min at 22 degrees C significantly enhanced the D-glucose influx into the membrane vesicles, without influencing the slope of the Hill plot. A dose-response curve of the effect of insulin revealed that although the effect was already significant at 10(-9) M, the maximal activity was reached at 10(-8) M. The influence of insulin on D-glucose uptake was present only when preincubation of the placental tissue with the hormone was performed in the presence of Mn2+. Incubation of placental tissue with 10(-8) M insulin did not influence D-glucose efflux from the BBM vesicles. Finally, direct incubation of the membranes with insulin had no effect on the glucose influx into these membrane vesicles. We conclude that insulin, at physiological concentrations, enhances glucose uptake by the BBM, and that such a regulation might contribute to the glucose homeostasis in the fetal circulation, independent of the maternal variations in glycemia.

  3. Regular exercise enhances insulin activation of IRS-1-associated PI3-kinase in human skeletal muscle.

    PubMed

    Kirwan, J P; del Aguila, L F; Hernandez, J M; Williamson, D L; O'Gorman, D J; Lewis, R; Krishnan, R K

    2000-02-01

    Insulin action in skeletal muscle is enhanced by regular exercise. Whether insulin signaling in human skeletal muscle is affected by habitual exercise is not well understood. Phosphatidylinositol 3-kinase (PI3-kinase) activation is an important step in the insulin-signaling pathway and appears to regulate glucose metabolism via GLUT-4 translocation in skeletal muscle. To examine the effects of regular exercise on PI3-kinase activation, 2-h hyperinsulinemic (40 mU. m(-2). min(-1))-euglycemic (5.0 mM) clamps were performed on eight healthy exercise-trained [24 +/- 1 yr, 71.8 +/- 2.0 kg, maximal O(2) uptake (VO(2 max)) of 56.1 +/- 2.5 ml. kg(-1). min(-1)] and eight healthy sedentary men and women (24 +/- 1 yr, 64.7 +/- 4.4 kg, VO(2 max) of 44.4 +/- 2.7 ml. kg(-1). min(-1)). A [6, 6-(2)H]glucose tracer was used to measure hepatic glucose output. A muscle biopsy was obtained from the vastus lateralis muscle at basal and at 2 h of hyperinsulinemia to measure insulin receptor substrate-1(IRS-1)-associated PI3-kinase activation. Insulin concentrations during hyperinsulinemia were similar for both groups (293 +/- 22 and 311 +/- 22 pM for trained and sedentary, respectively). Insulin-mediated glucose disposal rates (GDR) were greater (P < 0.05) in the exercise-trained compared with the sedentary control group (9.22 +/- 0.95 vs. 6.36 +/- 0.57 mg. kg fat-free mass(-1). min(-1)). Insulin-stimulated PI3-kinase activation was also greater (P < 0.004) in the trained compared with the sedentary group (3.8 +/- 0.5- vs. 1.8 +/- 0.2-fold increase from basal). Endurance capacity (VO(2 max)) was positively correlated with PI3-kinase activation (r = 0.53, P < 0.04). There was no correlation between PI3-kinase and muscle morphology. However, increases in GDR were positively related to PI3-kinase activation (r = 0.60, P < 0.02). We conclude that regular exercise leads to greater insulin-stimulated IRS-1-associated PI3-kinase activation in human skeletal muscle, thus facilitating enhanced

  4. The human insulin gene linked polymorphic region exhibits an altered DNA structure.

    PubMed Central

    Hammond-Kosack, M C; Dobrinski, B; Lurz, R; Docherty, K; Kilpatrick, M W

    1992-01-01

    Regulation of transcription of the human insulin gene appears to involve a series of DNA sequences in the 5' region. Hypersensitivity to DNA structural probes has previously been demonstrated in regulatory regions of cloned genomic DNA fragments, and been correlated with gene activity. To investigate the structure of the DNA in the human insulin gene, bromoacetaldehyde and S1 nuclease were reacted with a supercoiled plasmid containing a 5kb genomic insulin fragment. Both probes revealed the human insulin gene linked polymorphic region (ILPR), a region (-363) upstream of the transcriptional start site which contains multiple repeats of a 14-15mer oligonucleotide with the consensus sequence ACAGGGGT(G/C)(T/C)GGGG, as the major hypersensitive site. Fine mapping and electron microscopic analysis both show a very different behaviour of the two DNA strands in the region of the ILPR and suggest the G-rich strand may be adopting a highly structured conformation with the complementary strand remaining largely single stranded. Images PMID:1741248

  5. A novel Gymnema sylvestre extract stimulates insulin secretion from human islets in vivo and in vitro.

    PubMed

    Al-Romaiyan, A; Liu, B; Asare-Anane, H; Maity, C R; Chatterjee, S K; Koley, N; Biswas, T; Chatterji, A K; Huang, G-C; Amiel, S A; Persaud, S J; Jones, P M

    2010-09-01

    Many plant-based products have been suggested as potential antidiabetic agents, but few have been shown to be effective in treating the symptoms of Type 2 diabetes mellitus (T2DM) in human studies, and little is known of their mechanisms of action. Extracts of Gymnema sylvestre (GS) have been used for the treatment of T2DM in India for centuries. The effects of a novel high molecular weight GS extract, Om Santal Adivasi, (OSA(R)) on plasma insulin, C-peptide and glucose in a small cohort of patients with T2DM are reported here. Oral administration of OSA(R) (1 g/day, 60 days) induced significant increases in circulating insulin and C-peptide, which were associated with significant reductions in fasting and post-prandial blood glucose. In vitro measurements using isolated human islets of Langerhans demonstrated direct stimulatory effects of OSA(R) on insulin secretion from human ß-cells, consistent with an in vivo mode of action through enhancing insulin secretion. These in vivo and in vitro observations suggest that OSA(R) may provide a potential alternative therapy for the hyperglycemia associated with T2DM.

  6. Overexpression of Insulin Receptor Substrate-2 in Human and Murine Hepatocellular Carcinoma

    PubMed Central

    Boissan, Mathieu; Beurel, Eléonore; Wendum, Dominique; Rey, Colette; Lécluse, Yann; Housset, Chantal; Lacombe, Marie-Lise; Desbois-Mouthon, Christèle

    2005-01-01

    Deregulations in insulin and insulin-like growth factor (IGF) pathways may contribute to hepatocellular carcinoma. Although intracellular insulin receptor substrate-2 (IRS-2) is the main effector of insulin signaling in the liver, its role in hepatocarcinogenesis is unknown. Here, we show that IRS-2 was overexpressed in two murine models of hepatocarcinogenesis: administration of diethylnitrosamine and hepatic overexpression of SV40 large T antigen. In both models, IRS-2 overexpression was detected in preneoplastic lesions and at higher levels in tumoral nodules. IRS-2 overexpression associated with IGF-2 and IRS-1 overexpression and with GSK-3β inhibition. Increased expression of IRS-2 was also detected in human hepatocellular carcinoma specimens and hepatoma cell lines. In murine and human hepatoma cells, IRS-2 protein induction associated with increased IRS-2 mRNA levels. The functionality of IRS-2 was demonstrated in Hep3B cells, in which IRS-2 tyrosine phosphorylation and its association with phosphatidylinositol-3 kinase were induced by IGF-2. Moreover, down-regulation of IRS-2 expression increased apoptosis in these cells. In conclusion, we demonstrate that IRS-2 is overexpressed in human and murine hepatocellular carcinoma. The emergence of IRS-2 overexpression at preneoplastic stages during experimental hepatocarcinogenesis and its protective effect against apoptosis suggest that IRS-2 contributes to liver tumor progression. PMID:16127164

  7. Human insulin/IGF-1 and familial longevity at middle age

    PubMed Central

    Rozing, Maarten P.; Westendorp, Rudi G.J.; Frölich, Marijke; de Craen, Anton J.M.; Beekman, Marian; Heijmans, Bastiaan T.; Mooijaart, Simon P.; Blauw, Gerard-Jan; Slagboom, P. Eline; van Heemst, Diana; Group, on behalf of the Leiden Longevity Study (LLS)

    2009-01-01

    Recently, we have shown that compared to controls, long-lived familial nonagenarians (mean age: 93.4 years) from the Leiden Longevity Study displayed a lower mortality rate, and their middle-aged offspring displayed a lower prevalence of cardio-metabolic diseases, including diabetes mellitus. The evolutionarily conserved insulin/IGF-1 signaling (IIS) pathway has been implicated in longevity in model organisms, but its relevance for human longevity has generated much controversy. Here, we show that compared to their partners, the offspring of familial nonagenarians displayed similar non-fasted serum levels of IGF-1, IGFBP3 and insulin but lower non-fasted serum levels of glucose, indicating that familial longevity is associated with differences in insulin sensitivity. PMID:20157552

  8. Insulin Inhibits Low Oxygen-Induced ATP Release from Human Erythrocytes: Implication for Vascular Control

    PubMed Central

    Hanson, Madelyn S.; Ellsworth, Mary L.; Achilleus, David; Stephenson, Alan H.; Bowles, Elizabeth A.; Sridharan, Meera; Adderley, Shaquria; Sprague, Randy S.

    2010-01-01

    Objective ATP released from human erythrocytes in response to reduced oxygen tension (pO2) participates in the matching of oxygen (O2) supply with need in skeletal muscle by stimulating increases in blood flow to areas with increased O2 demand. Here we investigated the hypothesis that hyperinsulinemia inhibits ATP release from erythrocytes and impairs their ability to stimulate dilation of isolated arterioles exposed to decreased extra-luminal pO2. Methods Erythrocyte ATP release was stimulated pharmacologically (mastoparan 7) and physiologically (reduced pO2) in the absence or presence of insulin. We also examined the ability of isolated skeletal muscle arterioles perfused with buffer containing erythrocytes treated with insulin or its vehicle (saline) to dilate in response to decreased extra-luminal pO2. Results Insulin significantly attenuated mastoparan 7– and reduced pO2–induced ATP release. In vessels perfused with untreated erythrocytes, low extra-luminal pO2 resulted in an increase in vessel diameter. In contrast, when erythrocytes were treated with insulin, no vasodilation occurred. Conclusions These studies demonstrate that insulin inhibits ATP release from erythrocytes in response to reduced pO2 and impairs their ability to stimulate dilation of skeletal muscle arterioles. These results suggest that hyperinsulinemia could hinder the matching of O2 supply with need in skeletal muscle. PMID:19412833

  9. Human insulin production from a novel mini-proinsulin which has high receptor-binding activity.

    PubMed

    Chang, S G; Kim, D Y; Choi, K D; Shin, J M; Shin, H C

    1998-02-01

    To increase the folding efficiency of the insulin precursor and the production yield of insulin, we have designed a mini-proinsulin (M2PI) having the central C-peptide region replaced with a sequence forming a reverse turn. The mini-proinsulin was fused at the N-terminus to a 21-residue fusion partner containing a His10 tag for affinity purification. The gene for the fusion protein was inserted downstream of the T7 promoter of the expression plasmid pET-3a, and the fusion proteins were produced as inclusion bodies in the Escherichia coli cytoplasm at levels up to 25% of the total cell protein. The protein was sulphonated, cleaved by CNBr and the M2PI mini-proinsulin was purified using ion-exchange chromatography. The refolding yield of M2PI was 20-40% better than that of proinsulin studied at the same molar concentrations, indicating that the short turn-forming sequence is more effective in the refolding process than the much longer C-peptide. Native human insulin was successfully generated by subsequent enzymic conversion of mini-proinsulin. The mini-proinsulin exhibited high receptor-binding activity, about 50% as potent as insulin, suggesting that this single-chained mini-proinsulin may provide a foundation in understanding the receptor-bound structure of insulin as well as the role of C-peptide in the folding and activity of proinsulin.

  10. Human insulin production from a novel mini-proinsulin which has high receptor-binding activity.

    PubMed Central

    Chang, S G; Kim, D Y; Choi, K D; Shin, J M; Shin, H C

    1998-01-01

    To increase the folding efficiency of the insulin precursor and the production yield of insulin, we have designed a mini-proinsulin (M2PI) having the central C-peptide region replaced with a sequence forming a reverse turn. The mini-proinsulin was fused at the N-terminus to a 21-residue fusion partner containing a His10 tag for affinity purification. The gene for the fusion protein was inserted downstream of the T7 promoter of the expression plasmid pET-3a, and the fusion proteins were produced as inclusion bodies in the Escherichia coli cytoplasm at levels up to 25% of the total cell protein. The protein was sulphonated, cleaved by CNBr and the M2PI mini-proinsulin was purified using ion-exchange chromatography. The refolding yield of M2PI was 20-40% better than that of proinsulin studied at the same molar concentrations, indicating that the short turn-forming sequence is more effective in the refolding process than the much longer C-peptide. Native human insulin was successfully generated by subsequent enzymic conversion of mini-proinsulin. The mini-proinsulin exhibited high receptor-binding activity, about 50% as potent as insulin, suggesting that this single-chained mini-proinsulin may provide a foundation in understanding the receptor-bound structure of insulin as well as the role of C-peptide in the folding and activity of proinsulin. PMID:9445392

  11. Selection of an RNA molecule that mimics a major autoantigenic epitope of human insulin receptor.

    PubMed Central

    Doudna, J A; Cech, T R; Sullenger, B A

    1995-01-01

    Autoimmunity often involves the abnormal targeting of self-antigens by antibodies, leading to tissue destruction and other pathologies. This process could potentially be disrupted by small ligands that bind specifically to autoantibodies and inhibit their interaction with the target antigen. Here we report the identification of an RNA sequence that binds a mouse monoclonal antibody specific for an autoantigenic epitope of human insulin receptor. The RNA ligand binds specifically and with high affinity (apparent Kd congruent to 2 nM) to the anti-insulin receptor antibody and not to other mouse IgGs. The RNA can also act as a decoy, blocking the antibody from binding the insulin receptor. Thus, it probably binds near the combining site on the antibody. Strikingly, the RNA cross-reacts with autoantibodies from patients with extreme insulin resistance. One simple explanation is that the selected RNA may structurally mimic the antigenic epitope on the insulin receptor protein. These results suggest that decoy RNAs may be used in the treatment of autoimmune diseases. Images Fig. 1 Fig. 4 Fig. 5 PMID:7534420

  12. Measurement of hepatic insulin sensitivity early after the bypass of the proximal small bowel in humans

    PubMed Central

    Herring, R.; Vusirikala, A.; Shojaee‐Moradi, F.; Jackson, N. C.; Chandaria, S.; Jackson, S. N.; Goldstone, A. P.; Hakim, N.; Patel, A. G.; Umpleby, A. M.; Le Roux, C. W.

    2016-01-01

    Summary Objective Unlike gastric banding or sleeve gastrectomy procedures, intestinal bypass procedures, Roux‐en‐Y gastric bypass in particular, lead to rapid improvements in glycaemia early after surgery. The bypass of the proximal small bowel may have weight loss and even caloric restriction‐independent glucose‐lowering properties on hepatic insulin sensitivity. In this first human mechanistic study, we examined this hypothesis by investigating the early effects of the duodeno‐jejunal bypass liner (DJBL; GI Dynamics, USA) on the hepatic insulin sensitivity by using the gold standard euglycaemic hyperinsulinaemic clamp methodology. Method Seven patients with obesity underwent measurement of hepatic insulin sensitivity at baseline, 1 week after a low‐calorie liquid diet and after a further 1 week following insertion of the DJBL whilst on the same diet. Results Duodeno‐jejunal bypass liner did not improve the insulin sensitivity of hepatic glucose production beyond the improvements achieved with caloric restriction. Conclusions Caloric restriction may be the predominant driver of early increases in hepatic insulin sensitivity after the endoscopic bypass of the proximal small bowel. The same mechanism may be at play after Roux‐en‐Y gastric bypass and explain, at least in part, the rapid improvements in glycaemia.

  13. A genetically engineered human pancreatic β cell line exhibiting glucose-inducible insulin secretion.

    PubMed

    Ravassard, Philippe; Hazhouz, Yasmine; Pechberty, Séverine; Bricout-Neveu, Emilie; Armanet, Mathieu; Czernichow, Paul; Scharfmann, Raphael

    2011-09-01

    Despite intense efforts over the past 30 years, human pancreatic β cell lines have not been available. Here, we describe a robust technology for producing a functional human β cell line using targeted oncogenesis in human fetal tissue. Human fetal pancreatic buds were transduced with a lentiviral vector that expressed SV40LT under the control of the insulin promoter. The transduced buds were then grafted into SCID mice so that they could develop into mature pancreatic tissue. Upon differentiation, the newly formed SV40LT-expressing β cells proliferated and formed insulinomas. The resulting β cells were then transduced with human telomerase reverse transcriptase (hTERT), grafted into other SCID mice, and finally expanded in vitro to generate cell lines. One of these cell lines, EndoC-βH1, expressed many β cell-specific markers without any substantial expression of markers of other pancreatic cell types. The cells secreted insulin when stimulated by glucose or other insulin secretagogues, and cell transplantation reversed chemically induced diabetes in mice. These cells represent a unique tool for large-scale drug discovery and provide a preclinical model for cell replacement therapy in diabetes. This technology could be generalized to generate other human cell lines when the cell type-specific promoter is available.

  14. Recombinant human insulin IX. Investigation of factors, influencing the folding of fusion protein-S-sulfonates, biotechnological precursors of human insulin.

    PubMed

    Tikhonov, Roman V; Pechenov, Sergey E; Belacheu, Irina A; Yakimov, Sergey A; Klyushnichenko, Vadim E; Tunes, Heloisa; Thiemann, Josef E; Vilela, Luciano; Wulfson, Andrey N

    2002-11-01

    The peculiarities of molecular structures and the influence of reaction conditions on the folding efficiency of fusion proteins-biotechnological precursors of human insulin, expressed in Escherichia coli as inclusion bodies have been investigated. The fusion proteins contained proinsulin sequence with various leader peptides connected by an Arg residue to the insulin B-chain. The kind and the size of leader peptide do not have essential influence on folding efficiency. However, the efficiency of protein folding depends on the location of the (His)6 site, which is used for metal-chelating affinity chromatography. In our study the protein folding depends on the reaction medium composition (including additives), the presence of accompanied cell components, pH, temperature, concentrations of protein, and redox agents. A negative influence of nucleic acid and heavy metal ions on folding has been found. S-sulfonated fusion protein has proinsulin-like secondary structure (by CD-spectroscopy data) that is the key point for 95% efficient folding proceeding. Folded fusion proteins are transformed into insulin by enzymatic cleavage.

  15. The effect of feeding frequency on insulin and ghrelin responses in human subjects.

    PubMed

    Solomon, Thomas P J; Chambers, Edward S; Jeukendrup, Asker E; Toogood, Andrew A; Blannin, Andrew K

    2008-10-01

    Recent work shows that increased meal frequency reduces ghrelin responses in sheep. Human research suggests there is an interaction between insulin and ghrelin. The effect of meal frequency on this interaction is unknown. Therefore, we investigated the effect of feeding frequency on insulin and ghrelin responses in human subjects. Five healthy male volunteers were recruited from the general population: age 24 (SEM 2)years, body mass 75.7 (SEM 3.2) kg and BMI 23.8 (SEM 0.8) kg/m(2). Volunteers underwent three 8-h feeding regimens: fasting (FAST); low-frequency(two) meal ingestion (LOFREQ(MEAL)); high-frequency (twelve) meal ingestion (HIFREQ(MEAL)). Meals were equi-energetic within trials,consisting of 64% carbohydrate, 23% fat and 13% protein. Total energy intake was equal between feeding trials. Total area under the curve for serum insulin and plasma ghrelin responses did not differ between trials (P>0.05), although the hormonal response patterns to the two meal feeding regimens were different. An inverse relationship was found between serum insulin and plasma ghrelin during the FAST andLOFREQ(MEAL) trials (P<0.05); and, in the postprandial period, there was a time delay between insulin responses and successive ghrelin responses.This relationship was not observed during the HIFREQ(MEAL) trial (P>0.05). This study provides further evidence that the postprandial fall in ghrelin might be due, at least partially, to the rise in insulin and that high-frequency feeding may disrupt this relationship.

  16. Biphasic insulin Aspart 30 vs. NPH plus regular human insulin in type 2 diabetes patients; a cost-effectiveness study.

    PubMed

    Farshchi, Amir; Aghili, Rokhsareh; Oskuee, Maryam; Rashed, Marjan; Noshad, Sina; Kebriaeezadeh, Abbas; Kia, Maryam; Esteghamati, Alireza

    2016-06-09

    The aim of this study was to compare the efficacy, safety, costs, and cost-effectiveness of biphasic insulin aspart 30 (BIAsp 30) with NPH plus regular human insulin (NPH/Reg) in patients with type 2 diabetes mellitus (T2DM). It was a Single-center, parallel-group, randomized, clinical trial (Trial Registration: NCT01889095). One hundred and seventy four T2DM patients with poorly controlled diabetes (HbA1c ≥ 8 % (63.9 mmol/mol)) were randomly assigned to trial arms (BIAsp 30 and NPH/Reg) and were followed up for 48 weeks. BIAsp 30 was started at an initial dose of 0.2-0.6 IU/Kg in two divided doses and was titrated according to the glycemic status of the patient. Similarly, NPH/Reg insulin was initiated at a dose of 0.2-0.6 IU/Kg with a 2:1 ratio and was subsequently titrated. Level of glycemic control, hypoglycemic events, direct and indirect costs, quality adjusted life year (QALY) and incremental cost-effectiveness ratio have been assessed. HbA1c, Fasting plasma glucose (FPG), and two-hour post-prandial glucose (PPG) were improved in both groups during the study (P < 0.05 for all analyses). Lower frequencies of minor, major, and nocturnal hypoglycemic episodes were observed with BIAsp 30 (P < 0.05). Additionally, BIAsp 30 was associated with less weight gain and also higher QALYs (P < 0.05). Total medical and non-medical costs were significantly lower with BIAsp 30 as compared with NPH/Reg (930.55 ± 81.43 USD vs. 1101.24 ± 165.49 USD, P = 0.004). Moreover, BIAsp 30 showed lower ICER as a dominant alternative. Despite being more expensive, BIAsp 30 offers the same glycemic control as to NPH/Reg dose-dependently and also appears to cause fewer hypoglycemic events and to be more cost-effective in Iranian patients with type 2 diabetes.

  17. Detailed Physiologic Characterization Reveals Diverse Mechanisms for Novel Genetic Loci Regulating Glucose and Insulin Metabolism in Humans

    PubMed Central

    Ingelsson, Erik; Langenberg, Claudia; Hivert, Marie-France; Prokopenko, Inga; Lyssenko, Valeriya; Dupuis, Josée; Mägi, Reedik; Sharp, Stephen; Jackson, Anne U.; Assimes, Themistocles L.; Shrader, Peter; Knowles, Joshua W.; Zethelius, Björn; Abbasi, Fahim A.; Bergman, Richard N.; Bergmann, Antje; Berne, Christian; Boehnke, Michael; Bonnycastle, Lori L.; Bornstein, Stefan R.; Buchanan, Thomas A.; Bumpstead, Suzannah J.; Böttcher, Yvonne; Chines, Peter; Collins, Francis S.; Cooper, Cyrus C.; Dennison, Elaine M.; Erdos, Michael R.; Ferrannini, Ele; Fox, Caroline S.; Graessler, Jürgen; Hao, Ke; Isomaa, Bo; Jameson, Karen A.; Kovacs, Peter; Kuusisto, Johanna; Laakso, Markku; Ladenvall, Claes; Mohlke, Karen L.; Morken, Mario A.; Narisu, Narisu; Nathan, David M.; Pascoe, Laura; Payne, Felicity; Petrie, John R.; Sayer, Avan A.; Schwarz, Peter E. H.; Scott, Laura J.; Stringham, Heather M.; Stumvoll, Michael; Swift, Amy J.; Syvänen, Ann-Christine; Tuomi, Tiinamaija; Tuomilehto, Jaakko; Tönjes, Anke; Valle, Timo T.; Williams, Gordon H.; Lind, Lars; Barroso, Inês; Quertermous, Thomas; Walker, Mark; Wareham, Nicholas J.; Meigs, James B.; McCarthy, Mark I.; Groop, Leif; Watanabe, Richard M.; Florez, Jose C.

    2010-01-01

    OBJECTIVE Recent genome-wide association studies have revealed loci associated with glucose and insulin-related traits. We aimed to characterize 19 such loci using detailed measures of insulin processing, secretion, and sensitivity to help elucidate their role in regulation of glucose control, insulin secretion and/or action. RESEARCH DESIGN AND METHODS We investigated associations of loci identified by the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) with circulating proinsulin, measures of insulin secretion and sensitivity from oral glucose tolerance tests (OGTTs), euglycemic clamps, insulin suppression tests, or frequently sampled intravenous glucose tolerance tests in nondiabetic humans (n = 29,084). RESULTS The glucose-raising allele in MADD was associated with abnormal insulin processing (a dramatic effect on higher proinsulin levels, but no association with insulinogenic index) at extremely persuasive levels of statistical significance (P = 2.1 × 10−71). Defects in insulin processing and insulin secretion were seen in glucose-raising allele carriers at TCF7L2, SCL30A8, GIPR, and C2CD4B. Abnormalities in early insulin secretion were suggested in glucose-raising allele carriers at MTNR1B, GCK, FADS1, DGKB, and PROX1 (lower insulinogenic index; no association with proinsulin or insulin sensitivity). Two loci previously associated with fasting insulin (GCKR and IGF1) were associated with OGTT-derived insulin sensitivity indices in a consistent direction. CONCLUSIONS Genetic loci identified through their effect on hyperglycemia and/or hyperinsulinemia demonstrate considerable heterogeneity in associations with measures of insulin processing, secretion, and sensitivity. Our findings emphasize the importance of detailed physiological characterization of such loci for improved understanding of pathways associated with alterations in glucose homeostasis and eventually type 2 diabetes. PMID:20185807

  18. The Effects of Insulin Resistance on Individual Tissues: An Application of a Mathematical Model of Metabolism in Humans.

    PubMed

    Pearson, Taliesin; Wattis, Jonathan A D; King, John R; MacDonald, Ian A; Mazzatti, Dawn J

    2016-06-01

    Whilst the human body expends energy constantly, the human diet consists of a mix of carbohydrates and fats delivered in a discontinuous manner. To deal with this sporadic supply of energy, there are transport, storage and utilisation mechanisms, for both carbohydrates and fats, around all tissues of the body. Insulin-resistant states such as type 2 diabetes and obesity are characterised by reduced efficiency of these mechanisms. Exactly how these insulin-resistant states develop, for example whether there is an order in which tissues become insulin resistant, is an active area of research with the hope of gaining a better overall understanding of insulin resistance. In this paper, we use a previously derived system of 12 first-order coupled differential equations that describe the transport between, and storage in, different tissues of the human body. We briefly revisit the derivation of the model before parametrising the model to account for insulin resistance. We then solve the model numerically, separately simulating each individual tissue as insulin resistant, and discuss and compare these results, drawing three main conclusions. The implications of these results are in accordance with biological intuition. First, insulin resistance in a tissue creates a knock-on effect on the other tissues in the body, whereby they attempt to compensate for the reduced efficiency of the insulin-resistant tissue. Second, insulin resistance causes a fatty liver, and the insulin resistance of tissues other than the liver can cause fat to accumulate in the liver. Finally, although insulin resistance in individual tissues can cause slightly reduced skeletal muscle metabolic flexibility, it is when the whole body is insulin resistant that the biggest effect on skeletal muscle flexibility is seen.

  19. Overview of insulin delivery pen devices.

    PubMed

    Kroon, Lisa

    2009-01-01

    To review currently available insulin delivery pen devices for use in diabetes and to describe their primary benefits and drawbacks in comparison with the traditional vial/syringe method of insulin administration. Not applicable. Insulin delivery pen devices are available for most types of insulin, including all insulin analog preparations and insulin premixes with rapid-acting insulin or regular insulin with neutral protamine Hagedorn insulin. Some devices have a replaceable insulin cartridge (categorized as reusable or durable); other devices are prefilled and are disposed of after the insulin reservoir is emptied. Insulin delivery pens offer several advantages over the vial and syringe method of injection, including greater ease and discretion of use and improved portability, adherence, and dosing accuracy. The tactile and auditory feedback provided by the dosing dial on insulin delivery pen devices may be particularly helpful for patients who have impaired manual dexterity or vision. Studies also show a strong preference among patients in favor of insulin delivery pen devices compared with the vial/syringe method. Finally, despite greater per-unit cost, insulin delivery pen devices have also been associated with reductions in health resource use and associated costs compared with vial/syringe therapy. Insulin delivery pen devices offer another option to patients with diabetes for insulin administration. They are associated with not only improved ease of use but also improved dosing accuracy and adherence to therapy. To develop the most suitable insulin regimens for their patients, health providers should be informed about available insulin delivery pen devices.

  20. A Human Anti-Insulin IgG Autoantibody Apparently Arises Through Clonal Selection from an Insulin-Specific “Germ-Line” Natural Antibody Template

    PubMed Central

    Ichiyoshi, Yuji; Zhou, Min; Casali, Paolo

    2015-01-01

    We analyzed the structural correlates underlying the insulin-dependent selection of the specific anti-insulin IgG1 κ mAb13-producing cell clone, derived from a patient with insulin-dependent diabetes mellitus treated with recombinant human insulin. First, we cloned the germ-line genes that putatively gave rise to the expressed VH and Vκ segments and used them to generate the full (unmutated) “germ-line revertant” of the “wild-type” (somatically mutated) mAb13, using recombinant PCR methods and an in vitro human Cγ1 and Cκ expression system. The full “germ-line revertant” bound insulin specifically and in a dose-saturable fashion, but with a relative avidity (Avrel) more than three-fold lower than that of its wild-type counterpart (Avrel, 1.69 × 10−8 vs 4.91 × 10−9 g/μl). Second, we established, by reassorting wild-type and germ-line revertant forms of the mAb13 VH and Vκ segments, that the increased Avrel for insulin of mAb13 when compared with its full “germ-line revertant” counterpart was entirely dependent on the mutations in the VH not those in the Vκ chain. Third, we determined, by site-directed mutagenesis experiments, that of the three mutations in the mAb13 VH segment (Ser→Gly, Ser→Thr, and Ser→Arg at positions 31, 56, and 58, respectively), only Arg58 was crucial in increasing the mAb13 Avrel (from 1.44 × 10−8 to 5.14 × 10−9 g/μl) and affinity (Kd, from 189 to 59 nM) for insulin. The affinity enhancement mediated by the VH segment Arg58 residue reflected about a threefold decrease in dissociation rate constant (Koff, from 4.92 × 10−3 to 1.54 × 10−3 s−1)but not an increase in association rate constant (Kon, from 2.60 × 104 to 2.61 × 104 M−1 s−1), and it contrasted with the complete loss of insulin binding resulting from the substitution of the VH segment Asn52 by Lys. The present findings suggest that human insulin, a self Ag, has the potential to recruit a natural autoantibody-producing cell precursor

  1. Blunted metabolic responses to cold and insulin stimulation in brown adipose tissue of obese humans.

    PubMed

    Orava, Janne; Nuutila, Pirjo; Noponen, Tommi; Parkkola, Riitta; Viljanen, Tapio; Enerbäck, Sven; Rissanen, Aila; Pietiläinen, Kirsi H; Virtanen, Kirsi A

    2013-11-01

    Inactive brown adipose tissue (BAT) may predispose to weight gain. This study was designed to measure metabolism in the BAT of obese humans, and to compare it to that in lean subjects. The impact of weight loss on BAT and the association of detectable BAT with various metabolic characteristics were also assessed. Using positron emission tomography (PET), cold- and insulin-stimulated glucose uptake and blood flow in the BAT of obese and lean humans were quantified. Further, cold-induced glucose uptake was measured in obese subjects before and after a 5-month conventional weight loss. Mean responses in BAT glucose uptake rate to both cold and insulin stimulation were twice as large in lean as in obese subjects. Blood flow in BAT was also lower in obese subjects under cold conditions. The increase in cold-induced BAT glucose uptake rate after weight loss was not statistically significant. Subjects with cold-activated detectable BAT were leaner and had higher whole-body insulin sensitivity than BAT-negative subjects, irrespective of age and gender. The effects of cold and insulin on BAT activity are severely blunted in obesity, and the presence of detectable BAT may contribute to a metabolically healthy status. Copyright © 2013 The Obesity Society.

  2. Analysis of the regions flanking the human insulin gene and sequence of an Alu family member.

    PubMed Central

    Bell, G I; Pictet, R; Rutter, W J

    1980-01-01

    The regions around the human insulin gene have been studied by heteroduplex, hybridization and sequence analysis. These studies indicated that there is a region of heterogeneous length located approximately 700 bp before the 5' end of the gene; and that the 19 kb of cloned DNA which includes the 1430 bp insulin gene as well as 5650 bp before and 11,500 bp after the gene is single copy sequence except for 500 bp located 6000 bp from the 3' end of the gene. This 500 bp segment contains a member of the Alu family of dispersed middle repetitive sequences as well as another less highly repeated homopolymeric segment. The sequence of this region was determined. This Alu repeat is bordered by 19 bp direct repeats and also contains an 83 bp sequence which is present twice. The regions flanking the human and rat I insulin genes were compared by heteroduplex analysis to localize homologous sequences in the flanking regions which could be involved in the regulation of insulin biosynthesis. The homology between the two genes is restricted to the region encoding preproinsulin and a short region of approximately 60 bp flanking the 5' side of the genes. Images PMID:6253909

  3. Distribution of insulin mRNA transcripts within the human body.

    PubMed

    Bell, Glenn D; Reddy, Shiva; Sun, Xueying; Yang, Yi; Krissansen, Geoffrey W

    2014-08-29

    Here we sought evidence for the existence of insulin mRNA-producing cells outside the human pancreas. Commercially available complementary DNA (cDNA) arrays prepared from 72 different types of adult human tissues were screened by PCR for transcripts encoding insulin, and other classic pancreatic hormones. Insulin mRNA transcripts were detected by standard PCR in the pancreas, stomach, pylorus region of the stomach, and the duodenum; and additionally by nested PCR in the jejunum, ileum and cecum, but not in other body tissues including the brain and colon. Most of these tissues also variably expressed mRNA transcripts for amylase α2B, amylin, glucagon, somatostatin, and pancreatic polypeptide. In summary, using sensitive PCR methods we have provided evidence for the presence of rare insulin mRNA-expressing cells within the stomach, small intestine, and cecum. Their role at these sites may be to support classical enteroendocrine cells as sentinels to sense and monitor gastric contents passing into and through the bowel. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Preserved endothelial function in human obesity in the absence of insulin resistance

    PubMed Central

    2013-01-01

    Background Insulin resistance (IR) is frequently associated with endothelial dysfunction and has been proposed to play a major role in cardiovascular disease (CVD). On the other hand, obesity has long been related to IR and increased CVD. However it is not known if IR is a necessary condition for endothelial dysfunction in human obesity, allowing for preserved endothelial function in obese people when absent. Therefore, the purpose of the study was to assess the relationship between IR and endothelial dysfunction in human obesity and the mechanisms involved. Methods Twenty non-insulin resistant morbid obese (NIR-MO), 32 insulin resistant morbid obese (IR-MO), and 12 healthy subjects were included. Serum concentrations of glucose, insulin, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), resistin and adiponectin were determined. IR was evaluated by HOMA-index. Endothelium-dependent relaxation to bradykinin (BK) in mesenteric microvessels was assessed in wire myograph. Results Serum IL-6, and TNF-α levels were elevated only in IR-MO patients while resistin was elevated and adiponectin reduced in all MO individuals. Mesenteric arteries from IR-MO, but not from NIR-MO subjects displayed blunted relaxation to BK. Vasodilatation was improved in IR-MO arteries by the superoxide scavenger, superoxide dismutase (SOD) or the mitochondrial-targeted SOD mimetic, mito-TEMPO. NADPH oxidase inhibitors (apocynin and VAS2870) and the nitric oxide synthase (NOS) cofactor, tetrahydrobiopterin failed to modify BK-induced vasodilatations. Superoxide generation was higher in vessels from IR-MO subjects and reduced by mito-TEMPO. Blockade of TNF-α with infliximab, but not inhibition of inducible NOS or cyclooxygenase, improved endothelial relaxation and decreased superoxide formation. Conclusions Endothelial dysfunction is observed in human morbid obesity only when insulin resistance is present. Mechanisms involved include augmented mitochondrial superoxide generation, and

  5. Claudin-binder C-CPE mutants enhance permeability of insulin across human nasal epithelial cells.

    PubMed

    Kojima, Takashi; Kondoh, Masuo; Keira, Takashi; Takano, Ken-Ichi; Kakuki, Takuya; Kaneko, Yakuto; Miyata, Ryo; Nomura, Kazuaki; Obata, Kazufumi; Kohno, Takayuki; Konno, Takumi; Sawada, Norimasa; Himi, Tetsuo

    2016-10-01

    Intranasal insulin administration has therapeutic potential for Alzheimer's disease and in intranasal administration across the nasal mucosa, the paracellular pathway regulated by tight junctions is important. The C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) binds the tight junction protein claudin and disrupts the tight junctional barrier without a cytotoxic effect. The C-CPE mutant called C-CPE 194 binds only to claudin-4, whereas the C-CPE 194 mutant called C-CPE m19 binds not only to claudin-4 but also to claudin-1. In the present study, to investigate the effects of C-CPE mutants on the tight junctional functions of human nasal epithelial cells (HNECs) and on the permeability of human recombinant insulin across the cells, HNECs were treated with C-CPE 194 and C-CPE m19. C-CPE 194 and C-CPE m19 disrupted the barrier and fence functions without changes in expression of claudin-1, -4, -7, and occludin or cytotoxicity, whereas they transiently increased the activity of ERK1/2 phosphorylation. The disruption of the barrier function caused by C-CPE 194 and C-CPE m19 was prevented by pretreatment with the MAPKK inhibitor U0126. Furthermore, C-CPE 194 and C-CPE m19 significantly enhanced the permeability of human recombinant insulin across HNECs and the permeability was also inhibited by U0126. These findings suggest that C-CPE mutants 194 and m19 can regulate the permeability of insulin across HNECs via the MAPK pathway and may play a crucial role in therapy for the diseases such as Alzheimer's disease via the direct intranasal insulin administration.

  6. Insulin-induced myosin light-chain phosphorylation during receptor capping in IM-9 human B-lymphoblasts.

    PubMed Central

    Majercik, M H; Bourguignon, L Y

    1988-01-01

    We have examined further the interaction between insulin surface receptors and the cytoskeleton of IM-9 human lymphoblasts. Using immunocytochemical techniques, we determined that actin, myosin, calmodulin and myosin light-chain kinase (MLCK) are all accumulated directly underneath insulin-receptor caps. In addition, we have now established that the concentration of intracellular Ca2+ (as measured by fura-2 fluorescence) increases just before insulin-induced receptor capping. Most importantly, we found that the binding of insulin to its receptor induces phosphorylation of myosin light chain in vivo. Furthermore, a number of drugs known to abolish the activation properties of calmodulin, such as trifluoperazine (TFP) or W-7, strongly inhibit insulin-receptor capping and myosin light-chain phosphorylation. These data imply that an actomyosin cytoskeletal contraction, regulated by Ca2+/calmodulin and MLCK, is involved in insulin-receptor capping. Biochemical analysis in vitro has revealed that IM-9 insulin receptors are physically associated with actin and myosin; and most interestingly, the binding of insulin-receptor/cytoskeletal complex significantly enhances the phosphorylation of the 20 kDa myosin light chain. This insulin-induced phosphorylation is inhibited by calmodulin antagonists (e.g. TFP and W-7), suggesting that the phosphorylation is catalysed by MLCK. Together, these results strongly suggest that MLCK-mediated myosin light-chain phosphorylation plays an important role in regulating the membrane-associated actomyosin contraction required for the collection of insulin receptors into caps. Images Fig. 2. Fig. 4. PMID:3048249

  7. Inhaled Technosphere® Insulin in Comparison to Subcutaneous Regular Human Insulin: Time Action Profile and Variability in Subjects with Type 2 Diabetes

    PubMed Central

    Rave, Klaus; Heise, Tim; Heinemann, Lutz; Boss, Anders H.

    2008-01-01

    Background This study assessed time action profile and within- and between-subject variability of inhaled Technosphere® Insulin (TI) compared with subcutaneous regular human insulin (sc RHI). Methods Thirteen subjects with type 2 diabetes (age 56 ± 7 years, body mass index 30.4 ± 3.0 kg·m-2; hemoglobin A1c 6.9 ± 0.9%; mean ± SD) participated in this six-period crossover isoglycemic glucose clamp study. In randomized order, each subject received three single doses of TI and sc RHI on separate study days. Results Inhalation of TI resulted in a higher maximum serum insulin concentration (858 vs 438 pmol·liter-1; p = 0.0001) and shorter intervals to maximum insulin concentration (17 vs 135 minutes; p = 0.0001) than sc RHI. Overall, 48 units of TI and 24 units of sc RHI provided comparable 3-hour insulin exposure (INS area under the curve0–3 h 55.8 vs 60.0 nmol·min·liter-1, respectively). Time to maximum metabolic effect was shorter (79 vs 293 minutes; p < 0.0001), and percentage of glucose disposal during the first 3 hours was higher for TI compared with sc RHI (59 vs 27%). Within-subject variabilities of insulin exposure following inhalation of TI for 2 and 3 hours and end of study period were 19, 18, and 16% as compared with 27, 25, and 15% after sc RHI injection (p = not significant). Conclusion Technosphere Insulin has a more rapid onset of action than sc RHI. About 60% of the glucose-lowering effect of TI occurs during the first 3 hours after application. In contrast, <30% of the glucose-lowering effect of sc RHI occurs in this period. Technosphere Insulin demonstrated a lower intrasubject variability during the 3-hour postprandial period, without reaching statistical significance. PMID:19885344

  8. Detection of the single-chain precursor in the production and purification process of recombinant human insulin.

    PubMed

    Leng, Chunsheng; Li, Qingwei; Wu, Fenfang; Chen, Liyong; Su, Peng

    2013-08-01

    High quality recombinant insulin requires being free of single-chain precursor (proinsulin), a task that depends on the selectivity and sensitivity of the monitoring process for detecting proinsulin. In this study we developed an enzyme-linked immunosorbent assay (ELISA) system that was specifically tailored to detect recombinant proinsulin. The proinsulin consists of six components: an initiating methionine, 48 amino acids from human growth hormones (HGH, used as the protection peptide), first connecting Arg-residue, B-chain of insulin, and second connecting Arg-peptide and A-chain of insulin. This form of proinsulin is more stable and can be efficiently expressed by E. coli than insulin. Herein, we evaluated the specificity, precision, recovery, sensitivity, and detection range of the proinsulin ELISA kit. The results showed that the ELISA kit is a very useful tool for monitoring the proinsulin yield in early stages of insulin production as well as the residual proinsulin in the final product, insulin.

  9. Turbulent Premixed Flames in Microgravity

    NASA Technical Reports Server (NTRS)

    Menon, Suresh

    1996-01-01

    The experimental cold-flow facility is now full operational and is currently being used to obtain baseline turbulence data in a Couette flow. The baseline turbulence data is necessary to confirm the capability of the chosen device to generate and maintain the required turbulence intensity. Subsequent reacting flow studies will assume that a similar turbulent flow field exists ahead of the premixed flame. Some modifications and refinements had to be made to enable accurate measurements. It consists of two rollers, one (driven by a motor) which drives a continuous belt and four smaller rollers used to set the belt spacing and tension to minimize belt flutter. The entire assemble is enclosed in a structure that has the dimensions to enable future drop tower experiments of the hot facility. All critical dimensions are the same as the original plans except for the pulley ratio which has been changed to enable a wider operating regime in terms of the Reynolds number. With the current setup, Reynolds numbers as low as 100 and as high as 14,000 can be achieved. This is because the in-between belt spacing can be varied from 1 cm to 7.6 cm, and the belt speed can be accurately varied from .15 m/sec to 3.1 m/sec.

  10. Stimulation of glycogen synthesis by insulin in human erythroleukemia cells requires the synthesis of glycosyl-phosphatidylinositol.

    PubMed Central

    Lazar, D F; Knez, J J; Medof, M E; Cuatrecasas, P; Saltiel, A R

    1994-01-01

    Although the insulin-dependent hydrolysis of glycosyl-phosphatidylinositol (GPI) may play an important role in insulin action, an absolute requirement for this glycolipid has not been demonstrated. Human K562 cells were mutated to produce a cell line (IA) incapable of the earliest step in PI glycosylation, the formation of PI-GlcNAc. Another cell line (IVD) was deficient in the deacetylation of PI-GlcNAc to form PI-GlcN and subsequent mannosylated species. Each line was transfected with wild-type human insulin receptors. Similar insulin-stimulated receptor autophosphorylation was observed in all three lines, along with a nearly identical increase in the association of phosphorylated insulin receptor substrate 1 with endogenous PI 3-kinase. Both normal and GPI-defective lines also displayed a similar 2- to 3-fold increase in phosphorylation of the Shc protein and its association with growth factor receptor-bound protein 2 in response to insulin. In contrast to these results, striking differences were noted in insulin-stimulated glycogen synthesis. In normal cells, glycogen synthesis was significantly increased by insulin, whereas no insulin stimulation was observed in GPI-deficient IA cells, and only a trace of stimulation was detected in IVD cells. These results indicate that tyrosine phosphorylation produced by insulin is not dependent on GPI synthesis, and this effect is not sufficient to elicit at least some of the metabolic effects of the hormone. In contrast, GPI synthesis is required for the stimulation of glycogen synthesis by insulin in these cells. These findings support the existence of divergent pathways in the action of insulin. Images PMID:7524086

  11. Design factors for stable lean premix combustion

    SciTech Connect

    Richards, G.A.; Yip, M.J.; Gemmen, R.S.

    1995-10-01

    The Advanced Turbine Systems (ATS) program includes the development of low-emission combustors. Low emissions have already been achieved by premixing fuel and air to avoid the hot gas pockets produced by nozzles without premixing. While the advantages of premixed combustion have been widely recognized, turbine developers using premixed nozzles have experienced repeated problems with combustion oscillations. Left uncontrolled, these oscillations can lead to pressure fluctuations capable of damaging engine hardware. Elimination of such oscillations is often difficult and time consuming - particularly when oscillations are discovered in the last stages of engine development. To address this issue, METC is studying oscillating combustion from lean premixing fuel nozzles. These tests are providing generic information on the mechanisms that contribute to oscillating behavior in gas turbines. METC is also investigating the use of so-called {open_quotes}active{close_quotes} control of combustion oscillations. This technique periodically injects fuel pulses into the combustor to disrupt the oscillating behavior. Recent results on active combustion control are presented in Gemmen et al. (1995) and Richards et al. (1995). This paper describes the status of METC efforts to avoid oscillations through simple design changes.

  12. Short-term effects of the long-acting insulin analog detemir and human insulin on plasma levels of insulin-like growth factor-I and its binding proteins in humans.

    PubMed

    Porcellati, Francesca; Rossetti, Paolo; Candeloro, Paola; Lucidi, Paola; Cioli, Patrizia; Andreoli, Anna Marinelli; Ghigo, Ezio; Bolli, Geremia B; Fanelli, Carmine G

    2009-08-01

    The objective of the study was to compare responses of plasma levels of IGF-I and IGF binding proteins (IGFBP-1 and IGFBP-3) induced by human regular insulin (HI) and the long-acting insulin analog detemir (IDet) at doses equivalent with respect to the glucose-lowering effect. Ten nondiabetic subjects (six males, four females; age, 36 +/- 7 yr; body mass index, 22.9 +/- 2.6 kg/m(2)) were studied on four randomized occasions with iv infusion of IDet (2 mU/kg . min for 4 h, followed by 4 mU/kg . min for 1 h) or HI (1 mU/kg . min for 4 h, followed by 2 mU/kg . min for 1 h) in euglycemia [plasma glucose (PG), 90 mg/dl] or during stepped hypoglycemia (PG, 90, 78, 66, 54, and 42 mg/dl). PG was maintained at preselected plateaus, without any significant difference between IDet and HI (P > 0.2). Plasma insulin concentrations were on average approximately nine times greater with IDet than HI (749 +/- 52 vs. 83 +/- 19 muU/ml, respectively). Plasma IGF-I concentrations did not change from baseline during insulin infusion in euglycemia (IDet, 147 +/- 16 ng/ml; HI, 155 +/- 15 ng/ml) and hypoglycemia (IDet, 163 +/- 14 ng/ml; HI, 165 +/- 14 ng/ml) with no differences between the two insulins (P > 0.2). A similar pattern was observed for plasma IGFBP-3 levels. Insulin infusion resulted in a suppression of plasma IGFBP-1 concentrations with no differences between IDet (baseline, 16.6 +/- 3.8 ng/ml; endpoint, 2.0 +/- 0.6 ng/ml) and HI (baseline, 16.6 +/- 4.1 ng/ml; endpoint, 2.6 +/- 1.4 ng/ml) (P > 0.2) and study conditions (P > 0.2). The greater plasma insulin concentrations obtained with IDet exert effects on plasma levels of IGF-I, IGFBP-1, and IGFBP-3 similar to those of HI. Additional studies are needed to confirm these short-term results in patients with diabetes mellitus on long-term treatment with IDet.

  13. Analysis of Insulin in Human Breast Milk in Mothers with Type 1 and Type 2 Diabetes Mellitus

    PubMed Central

    Whitmore, T. J.; Trengove, N. J.; Graham, D. F.; Hartmann, P. E.

    2012-01-01

    Despite the important role that insulin plays in the human body, very little is known about its presence in human milk. Levels rapidly decrease during the first few days of lactation and then, unlike other serum proteins of similar size, achieve comparable levels to those in serum. Despite this, current guides for medical treatment suggest that insulin does not pass into milk, raising the question of where the insulin in milk originates. Five mothers without diabetes, 4 mothers with type 1, and 5 mothers with type 2 diabetes collected milk samples over a 24-hour period. Samples were analysed for total and endogenous insulin content and for c-peptide content. All of the insulin present in the milk of type 1 mothers was artificial, and c-peptide levels were 100x lower than in serum. This demonstrates that insulin is transported into human milk at comparable concentration to serum, suggesting an active transport mechanism. The role of insulin in milk is yet to be determined; however, there are a number of potential implications for the infant of the presence of artificial insulins in milk. PMID:22500167

  14. Structure and pharmaceutical formulation development of a new long-acting recombinant human insulin analog studied by NMR and MS.

    PubMed

    Bednarek, Elżbieta; Sitkowski, Jerzy; Bocian, Wojciech; Borowicz, Piotr; Płucienniczak, Grażyna; Stadnik, Dorota; Surmacz-Chwedoruk, Weronika; Jaworska, Beata; Kozerski, Lech

    2017-02-20

    A monomer structure of a novel human insulin analog A22(S)-B3(K)-B31(R) (SK3R) has been characterized by NMR in water/acetonitrile solution and compared with the structure of human insulin (HIS) established in the same medium. The composition of the oligomer ensemble for neat insulins in water was qualitatively assessed by monitoring, derived from NMR experiment, translational diffusion coefficient Dix10(-10)m(2)s(-1), whose value is a population averaged of individual coefficients for species in oligomeric ensemble. Nanospray ESI/MS experiment was used to establish the masses of oligomers in pharmaceutical formulation of the SK3R insulin. The pharmacodynamic data were established and compared to insulin glargine characterized by the same profile of action in diabetics. The oligomerization process of insulin during development of pharmaceutical formulation with routinely used excipients has been studied using translation diffusion coefficient Dix10(-10)m(2)s(-1) established in water solution. These properties were compared with those of human insulin (HIS) which is a standard reference for novel recombinant insulins. Copyright © 2016. Published by Elsevier B.V.

  15. Disruption of GIP/GIPR axis in human adipose tissue is linked to obesity and insulin resistance.

    PubMed

    Ceperuelo-Mallafré, Victòria; Duran, Xavier; Pachón, Gisela; Roche, Kelly; Garrido-Sánchez, Lourdes; Vilarrasa, Nuria; Tinahones, Francisco J; Vicente, Vicente; Pujol, Jordi; Vendrell, Joan; Fernández-Veledo, Sonia

    2014-05-01

    Glucose-dependent insulinotropic peptide (GIP) has a central role in glucose homeostasis through its amplification of insulin secretion; however, its physiological role in adipose tissue is unclear. Our objective was to define the function of GIP in human adipose tissue in relation to obesity and insulin resistance. GIP receptor (GIPR) expression was analyzed in human sc adipose tissue (SAT) and visceral adipose (VAT) from lean and obese subjects in 3 independent cohorts. GIPR expression was associated with anthropometric and biochemical variables. GIP responsiveness on insulin sensitivity was analyzed in human adipocyte cell lines in normoxic and hypoxic environments as well as in adipose-derived stem cells obtained from lean and obese patients. GIPR expression was downregulated in SAT from obese patients and correlated negatively with body mass index, waist circumference, systolic blood pressure, and glucose and triglyceride levels. Furthermore, homeostasis model assessment of insulin resistance, glucose, and G protein-coupled receptor kinase 2 (GRK2) emerged as variables strongly associated with GIPR expression in SAT. Glucose uptake studies and insulin signaling in human adipocytes revealed GIP as an insulin-sensitizer incretin. Immunoprecipitation experiments suggested that GIP promotes the interaction of GRK2 with GIPR and decreases the association of GRK2 to insulin receptor substrate 1. These effects of GIP observed under normoxia were lost in human fat cells cultured in hypoxia. In support of this, GIP increased insulin sensitivity in human adipose-derived stem cells from lean patients. GIP also induced GIPR expression, which was concomitant with a downregulation of the incretin-degrading enzyme dipeptidyl peptidase 4. None of the physiological effects of GIP were detected in human fat cells obtained from an obese environment with reduced levels of GIPR. GIP/GIPR signaling is disrupted in insulin-resistant states, such as obesity, and normalizing this

  16. Proteasome Dysfunction Associated to Oxidative Stress and Proteotoxicity in Adipocytes Compromises Insulin Sensitivity in Human Obesity

    PubMed Central

    Díaz-Ruiz, Alberto; Guzmán-Ruiz, Rocío; Moreno, Natalia R.; García-Rios, Antonio; Delgado-Casado, Nieves; Membrives, Antonio; Túnez, Isaac; El Bekay, Rajaa; Fernández-Real, José M.; Tovar, Sulay; Diéguez, Carlos; Tinahones, Francisco J.; Vázquez-Martínez, Rafael; López-Miranda, José

    2015-01-01

    Abstract Aims: Obesity is characterized by a low-grade systemic inflammatory state and adipose tissue (AT) dysfunction, which predispose individuals to the development of insulin resistance (IR) and metabolic disease. However, a subset of obese individuals, referred to as metabolically healthy obese (MHO) individuals, are protected from obesity-associated metabolic abnormalities. Here, we aim at identifying molecular factors and pathways in adipocytes that are responsible for the progression from the insulin-sensitive to the insulin-resistant, metabolically unhealthy obese (MUHO) phenotype. Results: Proteomic analysis of paired samples of adipocytes from subcutaneous (SC) and omental (OM) human AT revealed that both types of cells are altered in the MUHO state. Specifically, the glutathione redox cycle and other antioxidant defense systems as well as the protein-folding machinery were dysregulated and endoplasmic reticulum stress was increased in adipocytes from IR subjects. Moreover, proteasome activity was also compromised in adipocytes of MUHO individuals, which was associated with enhanced accumulation of oxidized and ubiquitinated proteins in these cells. Proteasome activity was also impaired in adipocytes of diet-induced obese mice and in 3T3-L1 adipocytes exposed to palmitate. In line with these data, proteasome inhibition significantly impaired insulin signaling in 3T3-L1 adipocytes. Innovation: This study provides the first evidence of the occurrence of protein homeostasis deregulation in adipocytes in human obesity, which, together with oxidative damage, interferes with insulin signaling in these cells. Conclusion: Our results suggest that proteasomal dysfunction and impaired proteostasis in adipocytes, resulting from protein oxidation and/or misfolding, constitute major pathogenic mechanisms in the development of IR in obesity. Antioxid. Redox Signal. 23, 597–612. PMID:25714483

  17. Proteasome Dysfunction Associated to Oxidative Stress and Proteotoxicity in Adipocytes Compromises Insulin Sensitivity in Human Obesity.

    PubMed

    Díaz-Ruiz, Alberto; Guzmán-Ruiz, Rocío; Moreno, Natalia R; García-Rios, Antonio; Delgado-Casado, Nieves; Membrives, Antonio; Túnez, Isaac; El Bekay, Rajaa; Fernández-Real, José M; Tovar, Sulay; Diéguez, Carlos; Tinahones, Francisco J; Vázquez-Martínez, Rafael; López-Miranda, José; Malagón, María M

    2015-09-01

    Obesity is characterized by a low-grade systemic inflammatory state and adipose tissue (AT) dysfunction, which predispose individuals to the development of insulin resistance (IR) and metabolic disease. However, a subset of obese individuals, referred to as metabolically healthy obese (MHO) individuals, are protected from obesity-associated metabolic abnormalities. Here, we aim at identifying molecular factors and pathways in adipocytes that are responsible for the progression from the insulin-sensitive to the insulin-resistant, metabolically unhealthy obese (MUHO) phenotype. Proteomic analysis of paired samples of adipocytes from subcutaneous (SC) and omental (OM) human AT revealed that both types of cells are altered in the MUHO state. Specifically, the glutathione redox cycle and other antioxidant defense systems as well as the protein-folding machinery were dysregulated and endoplasmic reticulum stress was increased in adipocytes from IR subjects. Moreover, proteasome activity was also compromised in adipocytes of MUHO individuals, which was associated with enhanced accumulation of oxidized and ubiquitinated proteins in these cells. Proteasome activity was also impaired in adipocytes of diet-induced obese mice and in 3T3-L1 adipocytes exposed to palmitate. In line with these data, proteasome inhibition significantly impaired insulin signaling in 3T3-L1 adipocytes. This study provides the first evidence of the occurrence of protein homeostasis deregulation in adipocytes in human obesity, which, together with oxidative damage, interferes with insulin signaling in these cells. Our results suggest that proteasomal dysfunction and impaired proteostasis in adipocytes, resulting from protein oxidation and/or misfolding, constitute major pathogenic mechanisms in the development of IR in obesity.

  18. Human adipose tissue-derived mesenchymal stem cells differentiate into insulin, somatostatin, and glucagon expressing cells

    SciTech Connect

    Timper, Katharina; Seboek, Dalma; Eberhardt, Michael; Linscheid, Philippe; Christ-Crain, Mirjam; Keller, Ulrich; Mueller, Beat; Zulewski, Henryk . E-mail: henryk.zulewski@unibas.ch

    2006-03-24

    Mesenchymal stem cells (MSC) from mouse bone marrow were shown to adopt a pancreatic endocrine phenotype in vitro and to reverse diabetes in an animal model. MSC from human bone marrow and adipose tissue represent very similar cell populations with comparable phenotypes. Adipose tissue is abundant and easily accessible and could thus also harbor cells with the potential to differentiate in insulin producing cells. We isolated human adipose tissue-derived MSC from four healthy donors. During the proliferation period, the cells expressed the stem cell markers nestin, ABCG2, SCF, Thy-1 as well as the pancreatic endocrine transcription factor Isl-1. The cells were induced to differentiate into a pancreatic endocrine phenotype by defined culture conditions within 3 days. Using quantitative PCR a down-regulation of ABCG2 and up-regulation of pancreatic developmental transcription factors Isl-1, Ipf-1, and Ngn3 were observed together with induction of the islet hormones insulin, glucagon, and somatostatin.

  19. Variation in the sequence and modification state of the human insulin gene flanking regions.

    PubMed

    Ullrich, A; Dull, T J; Gray, A; Philips, J A; Peter, S

    1982-04-10

    The nucleotide sequence of a highly repetitive sequence region upstream from the human insulin gene is reported. The length of this region varies between alleles in the population, and appears to be stably transmitted to the next generation in a Mendelian fashion. There is no significant correlation between the length of this sequence and two types of diabetes mellitus. We observe variation in the cleavability of a BglI recognition site downstream from the human insulin gene, which is probably due to variable nucleotide modification. This presumed modification state appears not to be inherited, and varies between tissues within an individual and between individuals for a given tissue. Both alleles in a given tissue DNA sample are modified to the same extent.

  20. Regulation of autophagy in human skeletal muscle: effects of exercise, exercise training and insulin stimulation

    PubMed Central

    Fritzen, Andreas M.; Madsen, Agnete B.; Kleinert, Maximilian; Treebak, Jonas T.; Lundsgaard, Anne‐Marie; Jensen, Thomas E.; Richter, Erik A.; Wojtaszewski, Jørgen; Kiens, Bente

    2016-01-01

    Key points Regulation of autophagy in human muscle in many aspects differs from the majority of previous reports based on studies in cell systems and rodent muscle.An acute bout of exercise and insulin stimulation reduce human muscle autophagosome content.An acute bout of exercise regulates autophagy by a local contraction‐induced mechanism.Exercise training increases the capacity for formation of autophagosomes in human muscle.AMPK activation during exercise seems insufficient to regulate autophagosome content in muscle, while mTORC1 signalling via ULK1 probably mediates the autophagy‐inhibiting effect of insulin. Abstract Studies in rodent muscle suggest that autophagy is regulated by acute exercise, exercise training and insulin stimulation. However, little is known about the regulation of autophagy in human skeletal muscle. Here we investigate the autophagic response to acute one‐legged exercise, one‐legged exercise training and subsequent insulin stimulation in exercised and non‐exercised human muscle. Acute one‐legged exercise decreased (P<0.01) lipidation of microtubule‐associated protein 1A/1B‐light chain 3 (LC3) (∼50%) and the LC3‐II/LC3‐I ratio (∼60%) indicating that content of autophagosomes decreases with exercise in human muscle. The decrease in LC3‐II/LC3‐I ratio did not correlate with activation of 5′AMP activated protein kinase (AMPK) trimer complexes in human muscle. Consistently, pharmacological AMPK activation with 5‐aminoimidazole‐4‐carboxamide riboside (AICAR) in mouse muscle did not affect the LC3‐II/LC3‐I ratio. Four hours after exercise, insulin further reduced (P<0.01) the LC3‐II/LC3‐I ratio (∼80%) in muscle of the exercised and non‐exercised leg in humans. This coincided with increased Ser‐757 phosphorylation of Unc51 like kinase 1 (ULK1), which is suggested as a mammalian target of rapamycin complex 1 (mTORC1) target. Accordingly, inhibition of mTOR signalling in mouse muscle prevented the

  1. Postprandial whole-body glycolysis is similar in insulin-resistant and insulin-sensitive non-diabetic humans

    PubMed Central

    Ravussin, E.

    2015-01-01

    Aims/hypothesis Insulin resistance is characterised by impaired glucose utilisation when measured by a euglycaemic–hyperinsulinaemic clamp. We hypothesised that, in response to postprandial conditions, non-diabetic individuals would have similar intracellular glycolytic and oxidative glucose metabolism independent of the degree of insulin resistance. Methods Fourteen (seven male) sedentary, insulin-sensitive participants (mean±SD: BMI 25±4 kg/m2; age 39±10 years; glucose disposal rate 9.4±2.1 mg [kg estimated metabolic body size]−1 min−1) and 14 (six male) sedentary, non-diabetic, insulin-resistant volunteers (29±4 kg/m2; 34±13 years; 5.3±1.2 mg [kg estimated metabolic body size]−1 min−1) received after a 10 h fast 60 g glucose plus 15 g [6,6-2H2]glucose. Serum glucose and insulin concentrations, plasma 2H enrichment and whole-body gas exchange were determined before glucose ingestion and hourly thereafter for 4 h. Plasma 2H2O production is an index of glycolytic disposal. On day 2, participants received a weight-maintenance diet. On day 3, a euglycaemic–hyperinsulinaemic clamp was performed. Results Insulin-resistant individuals had about a twofold higher postprandial insulin response than insulin-sensitive individuals (p=0.003). Resting metabolic rate was similar in the two groups before (p=0.29) and after (p=0.33–0.99 over time) glucose ingestion, whereas a trend for blunted glucose-induced thermogenesis was observed in insulin-resistant vs insulin-sensitive individuals (p=0.06). However, over the 4 h after the 75 g glucose ingestion, glycolytic glucose disposal was the same in insulin-sensitive and insulin-resistant individuals (36.5±3.7 and 36.2±6.4 mmol, respectively; p=0.99). Similarly, whole-body carbohydrate oxidation did not differ between the groups either before or after glucose ingestion (p=0.41). Conclusions/interpretation Postprandial hyperinsulinaemia and modest hyperglycaemia overcome insulin resistance by enhancing tissue

  2. A computational model of the human glucose-insulin regulatory system☆

    PubMed Central

    Shiang, Keh-Dong; Kandeel, Fouad

    2010-01-01

    Objective A computational model of insulin secretion and glucose metabolism for assisting the diagnosis of diabetes mellitus in clinical research is introduced. The proposed method for the estimation of parameters for a system of ordinary differential equations (ODEs) that represent the time course of plasma glucose and insulin concentrations during glucose tolerance test (GTT) in physiological studies is presented. The aim of this study was to explore how to interpret those laboratory glucose and insulin data as well as enhance the Ackerman mathematical model. Methods Parameters estimation for a system of ODEs was performed by minimizing the sum of squared residuals (SSR) function, which quantifies the difference between theoretical model predictions and GTT's experimental observations. Our proposed perturbation search and multiple-shooting methods were applied during the estimating process. Results Based on the Ackerman's published data, we estimated the key parameters by applying R-based iterative computer programs. As a result, the theoretically simulated curves perfectly matched the experimental data points. Our model showed that the estimated parameters, computed frequency and period values, were proven a good indicator of diabetes. Conclusion The present paper introduces a computational algorithm to biomedical problems, particularly to endocrinology and metabolism fields, which involves two coupled differential equations with four parameters describing the glucose-insulin regulatory system that Ackerman proposed earlier. The enhanced approach may provide clinicians in endocrinology and metabolism field insight into the transition nature of human metabolic mechanism from normal to impaired glucose tolerance. PMID:23554650

  3. Linking Functional Domains of the Human Insulin Receptor with the Bacterial Aspartate Receptor

    NASA Astrophysics Data System (ADS)

    Ellis, Leland; Morgan, David O.; Koshland, Daniel E.; Clauser, Eric; Moe, Gregory R.; Bollag, Gideon; Roth, Richard A.; Rutter, William J.

    1986-11-01

    A hybrid receptor has been constructed that is composed of the extracellular domain of the human insulin receptor fused to the transmembrane and cytoplasmic domains of the bacterial aspartate chemoreceptor. This hybrid protein can be expressed in rodent (CHO) cells and displays several functional features comparable to wild-type insulin receptor. It is localized to the cell surface, binds insulin with high affinity, forms oligomers, and is recognized by conformation-specific monoclonal antibodies. Although most of the expressed protein accumulates as a 180-kDa proreceptor, some processed 135-kDa receptor can be detected on the cell surface by covalent cross-linking. Expression of the hybrid receptor inhibits the insulin-activated uptake of 2-deoxyglucose by CHO cells. Thus, this hybrid is partially functional and can be processed; however, it is incapable of native transmembrane signaling. The results indicate that the intact domains of different types of receptors can retain some of the native features in a hybrid molecule but specific requirements will need to be satisfied for transmembrane signaling.

  4. Seven mutations in the human insulin gene linked to permanent neonatal/infancy-onset diabetes mellitus.

    PubMed

    Colombo, Carlo; Porzio, Ottavia; Liu, Ming; Massa, Ornella; Vasta, Mario; Salardi, Silvana; Beccaria, Luciano; Monciotti, Carla; Toni, Sonia; Pedersen, Oluf; Hansen, Torben; Federici, Luca; Pesavento, Roberta; Cadario, Francesco; Federici, Giorgio; Ghirri, Paolo; Arvan, Peter; Iafusco, Dario; Barbetti, Fabrizio

    2008-06-01

    Permanent neonatal diabetes mellitus (PNDM) is a rare disorder usually presenting within 6 months of birth. Although several genes have been linked to this disorder, in almost half the cases documented in Italy, the genetic cause remains unknown. Because the Akita mouse bearing a mutation in the Ins2 gene exhibits PNDM associated with pancreatic beta cell apoptosis, we sequenced the human insulin gene in PNDM subjects with unidentified mutations. We discovered 7 heterozygous mutations in 10 unrelated probands. In 8 of these patients, insulin secretion was detectable at diabetes onset, but rapidly declined over time. When these mutant proinsulins were expressed in HEK293 cells, we observed defects in insulin protein folding and secretion. In these experiments, expression of the mutant proinsulins was also associated with increased Grp78 protein expression and XBP1 mRNA splicing, 2 markers of endoplasmic reticulum stress, and with increased apoptosis. Similarly transfected INS-1E insulinoma cells had diminished viability compared with those expressing WT proinsulin. In conclusion, we find that mutations in the insulin gene that promote proinsulin misfolding may cause PNDM.

  5. A model for the quaternary structure of human placental insulin receptor deduced from electron microscopy.

    PubMed Central

    Christiansen, K; Tranum-Jensen, J; Carlsen, J; Vinten, J

    1991-01-01

    Electrophoretically pure and functionally intact human placental insulin receptor was studied by electron microscopy with negative-staining techniques. The quaternary structure of the detergent-solubilized receptor was determined. The receptor had the shape of a letter T approximately 24 nm in height and 18 nm in width with a thickness of the stem and the crossbar of 3-4 nm. No consistent change in ultrastructure of the receptor could be detected after the addition of insulin alone or insulin and Mn2+/Mg2+/ATP. After partial reduction of the alpha 2 beta 2 heterotetrameric receptor into alpha beta heterodimers, the electron micrographs showed a clear reduction in average size of the molecule with disappearance of the T profiles characteristic of the alpha 2 beta 2 heterotetramers. By incubation of the heterodimers in a phosphorylation medium containing insulin, a reassociation to molecules with molecular weights of the alpha 2 beta 2 heterotetramer took place judged from SDS/PAGE. Electron microscopy showed that the molecule formed larger aggregates, and only a few solitary T-shaped copies were seen. Images PMID:1986371

  6. A novel point mutation in the human insulin gene giving rise to hyperproinsulinemia (proinsulin Kyoto).

    PubMed Central

    Yano, H; Kitano, N; Morimoto, M; Polonsky, K S; Imura, H; Seino, Y

    1992-01-01

    We have identified a 65-yr-old nonobese Japanese man with diabetes mellitus, fasting hyperinsulinemia (150-300 pM), and a reduced fasting C-peptide/insulin molar ratio of 2.5-3.0. Fasting hyperinsulinemia was also found in his son and daughter. Analysis of insulin isolated from the serum of the proband and his son by reverse-phase high performance liquid chromatography revealed a minor peak coeluting with human insulin and a major peak of proinsulin-like materials. The insulin gene of the patient was amplified by the polymerase chain reaction and the products were sequenced. A novel point mutation was identified in which guanine was replaced by thymine. The substitution gives rise to a new HindIII recognition site and results in the amino acid replacement of leucine for arginine at position 65. These results indicate that the amino-acid replacement prevents recognition of the C-peptide-A chain dibasic protease and results in an elevation of proinsulin-like materials in the circulation. Furthermore, in this family the proinsulin-like materials is due to a biosynthetic defect, inherited as an autosomal dominant trait. Rapid detection of this mutation can be accomplished by HindIII restriction enzyme mapping of polymerase chain reaction-generated DNA, which enables us to facilitate the diagnosis and screening. Images PMID:1601997

  7. Role of disulfide bonds in the structure and activity of human insulin.

    PubMed

    Chang, Seung-Gu; Choi, Ki-Doo; Jang, Seung-Hwan; Shin, Hang-Cheol

    2003-12-31

    Insulin contains two inter-chain disulfide bonds between the A and B chains (A7-B7 and A20-B19), and one intra-chain linkage in the A chain (A6-A11). To investigate the role of each disulfide bond in the structure, function and stability of the molecule, three des mutants of human insulin, each lacking one of the three disulfide bonds, were prepared by enzymatic conversion of refolded mini-proinsulins. Structural and biological studies of the three des mutants revealed that all three disulfide bonds are essential for the receptor binding activity of insulin, whereas the different disulfide bonds make different contributions to the overall structure of insulin. Deletion of the A20-B19 disulfide bond had the most substantial influence on the structure as indicated by loss of ordered secondary structure, increased susceptibility to proteolysis, and markedly reduced compactness. Deletion of the A6-A11 disulfide bond caused the least perturbation to the structure. In addition, different refolding efficiencies between the three des mutants suggest that the disulfide bonds are formed sequentially in the order A20-B19, A7-B7 and A6-A11 in the folding pathway of proinsulin.

  8. Ohgata, the Single Drosophila Ortholog of Human Cereblon, Regulates Insulin Signaling-dependent Organismic Growth.

    PubMed

    Wakabayashi, Satoru; Sawamura, Naoya; Voelzmann, André; Broemer, Meike; Asahi, Toru; Hoch, Michael

    2016-11-25

    Cereblon (CRBN) is a substrate receptor of the E3 ubiquitin ligase complex that is highly conserved in animals and plants. CRBN proteins have been implicated in various biological processes such as development, metabolism, learning, and memory formation, and their impairment has been linked to autosomal recessive non-syndromic intellectual disability and cancer. Furthermore, human CRBN was identified as the primary target of thalidomide teratogenicity. Data on functional analysis of CRBN family members in vivo, however, are still scarce. Here we identify Ohgata (OHGT), the Drosophila ortholog of CRBN, as a regulator of insulin signaling-mediated growth. Using ohgt mutants that we generated by targeted mutagenesis, we show that its loss results in increased body weight and organ size without changes of the body proportions. We demonstrate that ohgt knockdown in the fat body, an organ analogous to mammalian liver and adipose tissue, phenocopies the growth phenotypes. We further show that overgrowth is due to an elevation of insulin signaling in ohgt mutants and to the down-regulation of inhibitory cofactors of circulating Drosophila insulin-like peptides (DILPs), named acid-labile subunit and imaginal morphogenesis protein-late 2. The two inhibitory proteins were previously shown to be components of a heterotrimeric complex with growth-promoting DILP2 and DILP5. Our study reveals OHGT as a novel regulator of insulin-dependent organismic growth in Drosophila.

  9. Sulfate Anion Delays the Self-Assembly of Human Insulin by Modifying the Aggregation Pathway

    PubMed Central

    Owczarz, Marta; Arosio, Paolo

    2014-01-01

    The understanding of the molecular mechanisms underlying protein self-assembly and of their dependence on solvent composition has implications in a large number of biological and biotechnological systems. In this work, we characterize the aggregation process of human insulin at acidic pH in the presence of sulfate ions using a combination of Thioflavin T fluorescence, dynamic light scattering, size exclusion chromatography, Fourier transform infrared spectroscopy, and transmission electron microscopy. It is found that the increase of sulfate concentration inhibits the conversion of insulin molecules into aggregates by modifying the aggregation pathway. At low sulfate concentrations (0–5 mM) insulin forms amyloid fibrils following the nucleated polymerization mechanism commonly observed under acidic conditions in the presence of monovalent anions. When the sulfate concentration is increased above 5 mM, the sulfate anion induces the salting-out of ∼18–20% of insulin molecules into reversible amorphous aggregates, which retain a large content of α-helix structures. During time these aggregates undergo structure rearrangements into β-sheet structures, which are able to recruit monomers and bind to the Thioflavin T dye. The alternative aggregation mechanism observed at large sulfate concentrations is characterized by a larger activation energy and leads to more polymorphic structures with respect to the self-assembly in the presence of chloride ions. The system shown in this work represents a case where amorphous aggregates on pathway to the formation of structures with amyloid features could be detected and analyzed. PMID:24988354

  10. Soot Formation in Laminar Premixed Flames

    NASA Technical Reports Server (NTRS)

    Xu, F.; Krishnan, S. S.; Faeth, G. M.

    1999-01-01

    Soot processes within hydrocarbon-fueled flames affect emissions of pollutant soot, thermal loads on combustors, hazards of unwanted fires and capabilities for computational combustion. In view of these observations, the present study is considering processes of soot formation in both burner-stabilized and freely-propagating laminar premixed flames. These flames are being studied in order to simplify the interpretation of measurements and to enhance computational tractability compared to the diffusion flame environments of greatest interest for soot processes. In addition, earlier studies of soot formation in laminar premixed flames used approximations of soot optical and structure properties that have not been effective during recent evaluations, as well as questionable estimates of flow residence times). The objective of present work was to exploit methods of avoiding these difficulties developed for laminar diffusion flames to study soot growth in laminar premixed flames. The following description of these studies is brief.

  11. Deletion analysis of the human insulin receptor ectodomain reveals independently folded soluble subdomains and insulin binding by a monomeric alpha-subunit.

    PubMed

    Schaefer, E M; Siddle, K; Ellis, L

    1990-08-05

    A series of 13 deletions within the extracellular domain of the human insulin receptor delineates the boundaries of subdomains that fold de novo into stable proteins that are efficiently secreted and retain the epitopes required for interaction with two conformation-specific monoclonal antibodies. While most of these proteins fail to bind insulin, a truncation that includes only the alpha-subunit is secreted as a monomer that binds the hormone with an affinity only slightly less than that of the complete heterotetrameric extracellular domain. These results thus demarcate landmarks within the primary sequence which will now guide further analysis of the structure and function of this complex domain of the receptor.

  12. High Insulin Combined With Essential Amino Acids Stimulates Skeletal Muscle Mitochondrial Protein Synthesis While Decreasing Insulin Sensitivity in Healthy Humans

    PubMed Central

    Robinson, Matthew M.; Soop, Mattias; Sohn, Tae Seo; Morse, Dawn M.; Schimke, Jill M.; Klaus, Katherine A.

    2014-01-01

    Context: Insulin and essential amino acids (EAAs) regulate skeletal muscle protein synthesis, yet their independent effects on mitochondrial protein synthesis (MiPS) and oxidative function remain to be clearly defined. Objective: The purpose of this study was to determine the effects of high or low insulin with or without EAAs on MiPS. Design: Thirty participants were randomized to 3 groups of 10 each with each participant studied twice. Study groups comprised (1) low and high insulin, (2) low insulin with and without EAAs, and (3) high insulin with and without EAAs. Setting: The study was conducted in an in-patient clinical research unit. Participants: Eligible participants were 18 to 45 years old, had a body mass index of <25 kg/m2, and were free of diseases and medications that might impair mitochondrial function. Intervention: Low (∼6 μU/mL) and high (∼40 μU/mL) insulin levels were maintained by iv insulin infusion during a somatostatin clamp while maintaining euglycemia (4.7–5.2 mM) and replacing GH and glucagon. The EAA infusion was 5.4% NephrAmine. l-[ring-13C6]Phenylalanine was infused, and muscle needle biopsies were performed. Main Outcomes: Muscle MiPS, oxidative enzymes, and plasma amino acid metabolites were measured. Results: MiPS and oxidative enzyme activities did not differ between low and high insulin (MiPS: 0.07 ± 0.009 vs 0.07 ± 0.006%/h, P = .86) or between EAAs and saline during low insulin (MiPS: 0.05 ± 0.01 vs 0.07 ± 0.01, P = .5). During high insulin, EAAs in comparison with saline increased MiPS (0.1 ± 0.01 vs 0.06 ± 0.01, P < .05) and cytochrome c oxidase activity (P < .05) but not citrate synthase (P = .27). EAA infusion decreased (P < .05) the glucose infusion rates needed to maintain euglycemia during low (∼40%) and high insulin (∼24%). Conclusion: EAAs increased MiPS and oxidative enzyme activity only with high insulin concentrations. PMID:25222757

  13. Insulin allergy.

    PubMed

    Ghazavi, Mohammad K; Johnston, Graham A

    2011-01-01

    Insulin reactions occur rarely but are of tremendous clinical importance. The first was reported in 1922 as a callus reaction at the injection site of insufficiently purified bovine insulin. Porcine insulin was subsequently found to be less allergenic than bovine insulin. Increasingly pure insulins have decreased the risk of adverse reactions, and the production of recombinant insulin with the same amino sequence as human insulin saw a large decrease in adverse reactions. Currently, the prevalence of allergic reactions to insulin products appears to be approximately 2%, and less than one-third of these events have been considered related to the insulin itself. Other reactions occur due to the preservatives added to insulin, including zinc, protamine, and meta-cresol. Allergic reactions can be type I or immunoglobulin E-mediated, type III or Arthus, and type IV or delayed-type hypersensitivity reactions. Type I reactions are the most common and can, rarely, cause anaphylaxis. In contrast, type IV reactions can occur after a delay of several days. Investigations include skin prick testing, patch testing, intradermal testing, and occasionally, skin biopsy.

  14. Effects of treatment with recombinant human growth hormone on insulin sensitivity and glucose metabolism in adults with growth hormone deficiency.

    PubMed

    Fowelin, J; Attvall, S; Lager, I; Bengtsson, B A

    1993-11-01

    In a double-blind, cross-over, placebo-controlled trial, the effect of 26 weeks of replacement therapy with recombinant human growth hormone (rhGH) on insulin sensitivity and glucose metabolism in nine patients with adult-onset growth hormone deficiency was studied with a euglycemic clamp. Glucose production and utilization were studied with D-(3-3H)-glucose infusions. Comparisons were made with placebo treatment for 6 and 26 weeks, respectively. GH therapy for 6 weeks increased fasting plasma concentrations of glucose and insulin. However, after 26 weeks of GH treatment, no significant changes in glucose or insulin concentrations were recorded. GH treatment induced a marked change in insulin action evident after 6 weeks of therapy as shown by lower glucose infusion rates (GIRs) during the clamp compared with placebo treatment (2.6 +/- 0.4 v 4.1 +/- 0.7 mg.kg-1.min-1). This change in insulin action was due to a decreased insulin effect on glucose utilization. After 26 weeks of GH therapy, there was no significant difference in GIRs. During placebo treatment, insulin sensitivity and insulin, glucose, and nonesterified fatty acid (NEFA) concentrations were unchanged compared with concentrations measured before the study. Thus GH replacement therapy induces a change in insulin action in GH-deficient individuals. Whether this change represents a decrease in insulin action (ie, insulin resistance) or a restoration of action to normal is presently unclear, since a healthy control group was not included in the study. During long-term treatment, the present study suggests that the change in insulin action can be reversed, probably secondarily to changes in body composition.

  15. Insulin-secreting cells from human eyelid-derived stem cells alleviate type I diabetes in immunocompetent mice.

    PubMed

    Kang, Hyun Mi; Kim, Jiyoung; Park, Seah; Kim, Jinyoung; Kim, Haekwon; Kim, Kyung Sik; Lee, Eun Jig; Seo, Sung Ig; Kang, Sung Goo; Lee, Jong-Eun; Lim, Hyunjung

    2009-08-01

    Various attempts have been made to develop stem cell-based therapy to alleviate type I diabetes using animal models. However, it has been a question whether human insulin produced from explanted cells is solely responsible for the normoglycemia of diabetic animals. In this study, we isolated neural crest-like stem cells from the human eyelid fat and examined their therapeutic potentials for diabetes. The human eyelid adipose-derived stem cells (HEACs) displayed characteristics of neural crest cells. Using a two-step culture condition combined with nicotinamide, activin, and/or GLP-1, we differentiated HEACs into insulin-secreting cells and examined in vivo effects of differentiated cells by transplantation experiments. Following differentiation in vitro, HEACs released insulin and c-peptide in a glucose-dependent manner. Upon their transplantation under kidney capsules of streptozotocin-treated immunocompetent mice, we observed normalization of hyperglycemia in 10 of 20 recipient mice until sacrifice after 2 months. Only the human, but not the mouse, insulin and c-peptide were detected in the blood of recipient mice. Removal of the kidneys transplanted with HEACs resulted in a sharp increase of blood glucose level. Removed kidney tissues showed distinct expression of various human genes including insulin, and colocalization of the human insulin and the human nuclear protein in many cells. However, they showed diminished or null expression of some immune-related genes. In conclusion, human insulin alone produced from eyelid-derived stem cells following differentiation into insulin-secreting cells and transplantation could normalize type I diabetes in mice.

  16. Chaos in an imperfectly premixed model combustor

    SciTech Connect

    Kabiraj, Lipika Saurabh, Aditya; Paschereit, Christian O.; Karimi, Nader; Sailor, Anna; Mastorakos, Epaminondas; Dowling, Ann P.

    2015-02-15

    This article reports nonlinear bifurcations observed in a laboratory scale, turbulent combustor operating under imperfectly premixed mode with global equivalence ratio as the control parameter. The results indicate that the dynamics of thermoacoustic instability correspond to quasi-periodic bifurcation to low-dimensional, deterministic chaos, a route that is common to a variety of dissipative nonlinear systems. The results support the recent identification of bifurcation scenarios in a laminar premixed flame combustor (Kabiraj et al., Chaos: Interdiscip. J. Nonlinear Sci. 22, 023129 (2012)) and extend the observation to a practically relevant combustor configuration.

  17. Palmitic acid but not palmitoleic acid induces insulin resistance in a human endothelial cell line by decreasing SERCA pump expression.

    PubMed

    Gustavo Vazquez-Jimenez, J; Chavez-Reyes, Jesus; Romero-Garcia, Tatiana; Zarain-Herzberg, Angel; Valdes-Flores, Jesus; Manuel Galindo-Rosales, J; Rueda, Angelica; Guerrero-Hernandez, Agustin; Olivares-Reyes, J Alberto

    2016-01-01

    Palmitic acid is a negative regulator of insulin activity. At the molecular level, palmitic acid reduces insulin stimulated Akt Ser473 phosphorylation. Interestingly, we have found that incubation with palmitic acid of human umbilical vein endothelial cells induced a biphasic effect, an initial transient elevation followed by a sustained reduction of SERCA pump protein levels. However, palmitic acid produced a sustained inhibition of SERCA pump ATPase activity. Insulin resistance state appeared before there was a significant reduction of SERCA2 expression. The mechanism by which palmitic acid impairs insulin signaling may involve endoplasmic reticulum stress, because this fatty acid induced activation of both PERK, an ER stress marker, and JNK, a kinase associated with insulin resistance. None of these effects were observed by incubating HUVEC-CS cells with palmitoleic acid. Importantly, SERCA2 overexpression decreased the palmitic acid-induced insulin resistance state. All these results suggest that SERCA pump might be the target of palmitic acid to induce the insulin resistance state in a human vascular endothelial cell line. Importantly, these data suggest that HUVEC-CS cells respond to palmitic acid-exposure with a compensatory overexpression of SERCA pump within the first hour, which eventually fades out and insulin resistance prevails.

  18. Human blood-brain barrier insulin-like growth factor receptor

    SciTech Connect

    Duffy, K.R.; Pardridge, W.M.; Rosenfeld, R.G.

    1988-02-01

    Insulin-like growth factor (IGF)-1 and IGF-2, may be important regulatory molecules in the CNS. Possible origins of IGFs in brain include either de novo synthesis or transport of circulating IGFs from blood into brain via receptor mediated transcytosis mechanisms at the brain capillary endothelial wall, ie, the blood-brain barrier (BBB). In the present studies, isolated human brain capillaries are used as an in vitro model system of the human BBB and the characteristics of IGF-1 or IGF-2 binding to this preparation were assessed. The total binding of IGF-2 at 37 degrees C exceeded 130% per mg protein and was threefold greater than the total binding for IGF-1. However, at 37 degrees C nonsaturable binding equaled total binding, suggesting that endocytosis is rate limiting at physiologic temperatures. Binding studies performed at 4 degrees C slowed endocytosis to a greater extent than membrane binding, and specific binding of either IGF-1 or IGF-2 was detectable. Scatchard plots for either peptide were linear and the molar dissociation constant of IGF-1 and IGF-2 binding was 2.1 +/- 0.4 and 1.1 +/- 0.1 nmol/L, respectively. Superphysiologic concentrations of porcine insulin inhibited the binding of both IGF-1 (ED50 = 2 micrograms/mL) and IGF-2 (ED50 = 0.5 microgram/mL). Affinity cross linking of /sup 125/I-IGF-1, /sup 125/I-IGF-2, and /sup 125/I-insulin to isolated human brain capillaries was performed using disuccinimidylsuberate (DSS). These studies revealed a 141 kd binding site for both IGF-1 and IGF-2, and a 133 kd binding site for insulin.

  19. Transplantation of insulin-secreting cells differentiated from human adipose tissue-derived stem cells into type 2 diabetes mice.

    PubMed

    Nam, Ji Sun; Kang, Hyun Mi; Kim, Jiyoung; Park, Seah; Kim, Haekwon; Ahn, Chul Woo; Park, Jin Oh; Kim, Kyung Rae

    2014-01-10

    Currently, there are limited ways to preserve or recover insulin secretory capacity in human pancreas. We evaluated the efficacy of cell therapy using insulin-secreting cells differentiated from human eyelid adipose tissue-derived stem cells (hEAs) into type 2 diabetes mice. After differentiating hEAs into insulin-secreting cells (hEA-ISCs) in vitro, cells were transplanted into a type 2 diabetes mouse model. Serum levels of glucose, insulin and c-peptide were measured, and changes of metabolism and inflammation were assessed in mice that received undifferentiated hEAs (UDC group), differentiated hEA-ISCs (DC group), or sham operation (sham group). Human gene expression and immunohistochemical analysis were done. DC group mice showed improved glucose level, and survival up to 60 days compared to those of UDC and sham group. Significantly increased levels of human insulin and c-peptide were detected in sera of DC mice. RT-PCR and immunohistochemical analysis showed human gene expression and the presence of human cells in kidneys of DC mice. When compared to sham mice, DC mice exhibited lower levels of IL-6, triglyceride and free fatty acids as the control mice. Transplantation of hEA-ISCs lowered blood glucose level in type 2 diabetes mice by increasing circulating insulin level, and ameliorating metabolic parameters including IL-6.

  20. Protein crystal growth in microgravity review of large scale temperature induction method: Bovine insulin, human insulin and human α-interferon

    NASA Astrophysics Data System (ADS)

    Long, Marianna M.; Bishop, John Bradford; Delucas, Lawrence J.; Nagabhushan, Tattanhalli L.; Reichert, Paul; Smith, G. David

    1997-01-01

    The Protein Crystal Growth Facility (PCF) is space-flight hardware that accommodates large scale protein crystal growth experiments using temperature change as the inductive step. Recent modifications include specialized instrumentation for monitoring crystal nucleation with laser light scattering. This paper reviews results from its first seven flights on the Space Shuttle, the last with laser light scattering instrumentation in place. The PCF's objective is twofold: (1) the production of high quality protein crystals for x-ray analysis and subsequent structure-based drug design and (2) preparation of a large quantity of relatively contaminant free crystals for use as time-release protein pharmaceuticals. The first three Shuttle flights with bovine insulin constituted the PCF's proof of concept, demonstrating that the space-grown crystals were larger and diffracted to higher resolution than their earth-grown counterparts. The later four PCF missions were used to grow recombinant human insulin crystals for x-ray analysis and continue productions trials aimed at the development of a processing facility for crystalline recombinant a-interferon.

  1. Label-Free Detection of Insulin and Glucagon within Human Islets of Langerhans Using Raman Spectroscopy

    PubMed Central

    Hilderink, Janneke; Otto, Cees; Slump, Cees; Lenferink, Aufried; Engelse, Marten; van Blitterswijk, Clemens; de Koning, Eelco; Karperien, Marcel; van Apeldoorn, Aart

    2013-01-01

    Intrahepatic transplantation of donor islets of Langerhans is a promising therapy for patients with type 1 diabetes. It is of critical importance to accurately monitor islet quality before transplantation, which is currently done by standard histological methods that are performed off-line and require extensive sample preparation. As an alternative, we propose Raman spectroscopy which is a non-destructive and label-free technique that allows continuous real-time monitoring of the tissue to study biological changes as they occur. By performing Raman spectroscopic measurements on purified insulin and glucagon, we showed that the 520 cm-1 band assigned to disulfide bridges in insulin, and the 1552 cm-1 band assigned to tryptophan in glucagon are mutually exclusive and could therefore be used as indirect markers for the label-free distinction between both hormones. High-resolution hyperspectral Raman imaging for these bands showed the distribution of disulfide bridges and tryptophan at sub-micrometer scale, which correlated with the location of insulin and glucagon as revealed by conventional immunohistochemistry. As a measure for this correlation, quantitative analysis was performed comparing the Raman images with the fluorescence images, resulting in Dice coefficients (ranging between 0 and 1) of 0.36 for insulin and 0.19 for glucagon. Although the use of separate microscope systems with different spatial resolution and the use of indirect Raman markers cause some image mismatch, our findings indicate that Raman bands for disulfide bridges and tryptophan can be used as distinctive markers for the label-free detection of insulin and glucagon in human islets of Langerhans. PMID:24167603

  2. Beta-endorphin-induced inhibition and stimulation of insulin secretion in normal humans is glucose dependent.

    PubMed

    Giugliano, D; Cozzolino, D; Salvatore, T; Torella, R; D'Onofrio, F

    1988-09-01

    This study evaluated the effect of human beta-endorphin on pancreatic hormone levels and their responses to nutrient challenges in normal subjects. Infusion of 0.5 mg/h beta-endorphin caused a significant rise in plasma glucose concentrations preceded by a significant increase in peripheral glucagon levels. No changes occurred in the plasma concentrations of insulin and C-peptide. Acute insulin and C-peptide responses to intravenous pulses of different glucose amounts (0.33 g/kg and 5 g) and arginine (3 g) were significantly reduced by beta-endorphin infusion (P less than .01). This effect was associated with a significant reduction of the glucose disappearance rates, suggesting that the inhibition of insulin was of biological relevance. beta-Endorphin also inhibited glucose suppression of glucagon levels and augmented the glucagon response to arginine. To verify whether the modification of prestimulus glucose level could be important in these hormonal responses to beta-endorphin, basal plasma glucose concentrations were raised by a primed (0.5 g/kg) continuous (20 mg kg-1.min-1) glucose infusion. After stabilization of plasma glucose levels (350 +/- 34 mg/dl, t = 120 min), beta-endorphin infusion caused an immediate and marked increase in plasma insulin level (peak response 61 +/- 9 microU/ml, P less than .01), which remained elevated even after the discontinuation of opioid infusion. Moreover, the acute insulin response to a glucose pulse (0.33 g/kg i.v.) given during beta-endorphin infusion during hyperglycemia was significantly higher than the response obtained during euglycemia (171 +/- 32 vs. 41 +/- 7 microU/ml, P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Metabolism of des(64,65)-human proinsulin in the rat. Evidence for the proteolytic processing to insulin.

    PubMed

    Wroblewski, V J; Masnyk, M; Kaiser, R E

    1993-10-01

    The metabolism of des(64,65)-human proinsulin was examined in rats after subcutaneous administration. Profiles of circulating insulin-like immunoreactivity in rat plasma 25 min after subcutaneous administration were evaluated by anion exchange fast protein liquid chromatography and reversed-phase high-performance liquid chromatography. Both techniques indicated the presence of circulating immunoreactivity having retention characteristics of human insulin. This metabolite peak comprised 5-10% of circulating immunoreactivity; the remainder had retention characteristics of des(64,65)-human proinsulin. The peaks of immunoreactive material were isolated and their structure determined using reversed-phase high-performance liquid chromatography and electrospray ionization mass spectrometry. The major circulating component co-eluted with des(64,65)-human proinsulin and had an identical mass spectrum. Two circulating metabolites were identified. These metabolites co-eluted by reversed-phase high-performance liquid chromatography with human insulin and diarginyl(B31,32)-human insulin and had mass spectra identical to the standard compounds. The data indicate proteolytic processing of des(64,65)-human proinsulin involves an initial tryptic cleavage at the carboxy side of ArgB32, with the formation of human insulin by the subsequent action of a carboxypeptidase to remove the ArgB31-ArgB32 dipeptide from diarginyl(B31,32)-human insulin. The results suggest that some of the pharmacological activity of des(64,65)-human proinsulin may be mediated in part by circulating insulin-like metabolites.

  4. GAIN Premix Facility: an innovative approach for improving access to quality vitamin and mineral premix in fortification initiatives.

    PubMed

    Guinot, Philippe; Jallier, Vincent; Blasi, Alessandro; Guyondet, Christophe; Van Ameringen, Marc

    2012-12-01

    Vitamin and mineral premix is one of the most significant recurring input costs for large-scale food fortification programs. A number of barriers exist to procuring adequate quality premix, including accessing suppliers, volatile prices for premix, lack of quality assurance and monitoring of delivered products, and lack of funds to purchase premix. To develop and test a model to procure premix through a transparent and efficient process in which an adequate level of quality is guaranteed and a financial mechanism is in place to support countries or specific target groups when there are insufficient resources to cover the cost of premix. Efforts focused on premixes used to fortify flour, such as wheat or maize (iron, zinc, B vitamins, and vitamin A), edible oils (vitamins A and D), and other food vehicles, such as fortified complementary foods, complementary food supplements, and condiments. A premix procurement model was set up with three distinct components: a certification process that establishes industry-wide standards and guidelines for premix, a procurement facility that makes premix more accessible to countries and private industry engaged in fortification, and a credit facility mechanism that helps projects finance premix purchases. After three years of operation, 15 premix suppliers and 29 micronutrient manufacturers have been certified, and more than US$23 million worth of premix that met quality standards has been supplied in 34 countries in Africa, Central and Southern Asia, and Eastern Europe, reaching an estimated 242 million consumers. The Premix Facility demonstrated its effectiveness in ensuring access to high-quality premixes, therefore enabling the success of various fortification programs.

  5. Relationship between pancreatic vesicular monoamine transporter 2 (VMAT2) and insulin expression in human pancreas

    PubMed Central

    Saisho, Yoshifumi; Harris, Paul E.; Butler, Alexandra E.; Galasso, Ryan; Gurlo, Tatyana; Rizza, Robert A.

    2008-01-01

    Vesicular monoamine transporter 2 (VMAT2) is expressed in pancreatic beta cells and has recently been proposed as a target for measurement of beta cell mass in vivo. We questioned, (1) What proportion of beta cells express VMAT2? (2) Is VMAT2 expressed by other pancreatic endocrine or non-endocrine cells? (3) Is the relationship between VMAT2 and insulin expression disturbed in type 1 (T1DM) or type 2 diabetes (T2DM)? Human pancreas (7 non-diabetics, 5 T2DM, 10 T1DM) was immunostained for insulin, VMAT2 and other pancreatic hormones. Most beta cells expressed VMAT2. VMAT2 expression was not changed by the presence of diabetes. In tail of pancreas VMAT2 immunostaining closely correlated with insulin staining. However, VMAT2 was also expressed in some pancreatic polypeptide (PP) cells. Although VMAT2 was not excluded as a target for beta cell mass measurement, expression of VMAT2 in PP cells predicts residual VMAT2 expression in human pancreas even in the absence of beta cells. Electronic supplementary material The online version of this article (doi:10.1007/s10735-008-9195-9) contains supplementary material, which is available to authorized users. PMID:18791800

  6. Renaturation of human proinsulin--a study on refolding and conversion to insulin.

    PubMed

    Winter, Jeannette; Lilie, Hauke; Rudolph, Rainer

    2002-11-15

    The production of human proinsulin in Escherichia coli usually leads to the formation of inclusion bodies. As a consequence, the recombinant protein must be isolated, refolded under suitable redox conditions, and enzymatically converted to the biologically active insulin. In this study we describe a detailed in vitro renaturation protocol for human proinsulin that includes native structure formation and the enzymatic conversion to mature insulin. We used a His(8)-Arg-proinsulin that was renatured from the completely reduced and denatured state in the presence of a cysteine/cystine redox couple. The refolding process was completed after 10-30 min and was shown to be strongly dependent on the redox potential and the pH value, but not on the temperature. Refolding yields of 60-70% could be obtained even at high concentrations of denaturant (3M guanidinium-HCl or 4M urea) and protein concentrations of 0.5mg/ml. By stepwise renaturation a concentration of about 6 mg/ml of native proinsulin was achieved. The refolded proinsulin was correctly disulfide-bonded and native and monomeric as shown by RP-HPLC, ELISA, circular dichroism, and analytical gel filtration. Treatment of the renatured proinsulin with trypsin and carboxypeptidase B yielded mature insulin.

  7. Reversal of diabetes following transplantation of an insulin-secreting human liver cell line: Melligen cells

    PubMed Central

    Lawandi, Janet; Tao, Chang; Ren, Binhai; Williams, Paul; Ling, Dora; Swan, M Anne; Nassif, Najah T; Torpy, Fraser R; O’Brien, Bronwyn A; Simpson, Ann M

    2015-01-01

    As an alternative to the transplantation of islets, a human liver cell line has been genetically engineered to reverse type 1 diabetes (TID). The initial liver cell line (Huh7ins) commenced secretion of insulin in response to a glucose concentration of 2.5 mmol/l. After transfection of the Huh7ins cells with human islet glucokinase, the resultant Melligen cells secreted insulin in response to glucose within the physiological range; commencing at 4.25 mmol/l. Melligen cells exhibited increased glucokinase enzymatic activity in response to physiological glucose concentrations, as compared with Huh7ins cells. When transplanted into diabetic immunoincompetent mice, Melligen cells restored normoglycemia. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed that both cell lines expressed a range of β-cell transcription factors and pancreatic hormones. Exposure of Melligen and Huh7ins cells to proinflammatory cytokines (TNF-α, IL-1β, and IFN-γ) affected neither their viability nor their ability to secrete insulin to glucose. Gene expression (microarray and qRT-PCR) analyses indicated the survival of Melligen cells in the presence of known β-cell cytotoxins was associated with the expression of NF-κB and antiapoptotic genes (such as BIRC3). This study describes the successful generation of an artificial β-cell line, which, if encapsulated to avoid allograft rejection, may offer a clinically applicable cure for T1D. PMID:26029722

  8. Processing of mutated human proinsulin to mature insulin in the non-endocrine cell line, CHO.

    PubMed

    Hunt, S M; Tait, A S; Gray, P P; Sleigh, M J

    1996-01-01

    Heterologous genes encoding proproteins, including proinsulin, generally produce mature protein when expressed in endocrine cells while unprocessed or partially processed protein is produced in non-endocrine cells. Proproteins, which are normally processed in the regulated pathway restricted to endocrine cells, do not always contain the recognition sequence for cleavage by furin, the endoprotease specific to the constitutive pathway, the principal protein processing pathway in non-endocrine cells. Human proinsulin consists of B-Chain-C-peptide-A-Chain and cleavage at the B/C and C/A junctions is required for processing. The B/C, but not the C/A junction, is recognised and cleaved in the constitute pathway. We expressed a human proinsulin and a mutated proinsulin gene with an engineered furin recognition sequence at the C/A junction and compared the processing efficiency of the mutant and native proinsulin in Chinese Hamster Ovary cells. The processing efficiency of the mutant proinsulin was 56% relative to 0.7% for native proinsulin. However, despite similar levels of mRNA being expressed in both cell lines, the absolute levels of immunoreactive insulin, normalized against mRNA levels, were 18-fold lower in the mutant proinsulin-expressing cells. As a result, there was only a marginal increase in absolute levels of insulin produced by these cells. This unexpected finding may result from preferential degradation of insulin in non-endocrine cells which lack the protection offered by the secretory granules found in endocrine cells.

  9. High insulin and leptin increase resistin and inflammatory cytokine production from human mononuclear cells.

    PubMed

    Tsiotra, Panayoula C; Boutati, Eleni; Dimitriadis, George; Raptis, Sotirios A

    2013-01-01

    Resistin and the proinflammatory cytokines, such as TNF- α , IL-6, and IL-1 β , produced by adipocytes, and macrophages, are considered to be important modulators of chronic inflammation contributing to the development of obesity and atherosclerosis. Human monocyte-enriched mononuclear cells, from ten healthy individuals, were exposed to high concentrations of insulin, leptin, and glucose (alone or in combination) for 24 hours in vitro. Resistin, TNF- α , IL-6, and IL-1 β production was examined and compared to that in untreated cells. High insulin and leptin concentrations significantly upregulated resistin and the cytokines. The subsequent addition of high glucose significantly upregulated resistin and TNF- α mRNA and protein secretion, while it did not have any effect on IL-6 or IL-1 β production. By comparison, exposure to dexamethasone reduced TNF- α , IL-6, and IL-1 β production, while at this time point it increased resistin protein secretion. These data suggest that the expression of resistin, TNF- α , IL-6, and IL-1 β from human mononuclear cells, might be enhanced by the hyperinsulinemia and hyperleptinemia and possibly by the hyperglycemia in metabolic diseases as obesity, type 2 diabetes, and atherosclerosis. Therefore, the above increased production may contribute to detrimental effects of their increased adipocyte-derived circulating levels on systemic inflammation, insulin sensitivity, and endothelial function of these patients.

  10. The receptor CD44 is associated with systemic insulin resistance and proinflammatory macrophages in human adipose tissue.

    PubMed

    Liu, Li Fen; Kodama, Keiichi; Wei, Ke; Tolentino, Lorna L; Choi, Okmi; Engleman, Edgar G; Butte, Atul J; McLaughlin, Tracey

    2015-07-01

    Proinflammatory immune cell infiltration in human adipose tissue is associated with the development of insulin resistance. We previously identified, via a gene expression-based genome-wide association study, the cell-surface immune cell receptor CD44 as a functionally important gene associated with type 2 diabetes. We then showed that, compared with controls, Cd44 knockout mice were protected from insulin resistance and adipose tissue inflammation during diet-induced obesity. We thus sought to test whether CD44 is associated with adipose tissue inflammation and insulin resistance in humans. Participants included 58 healthy, overweight/moderately obese white adults who met predetermined criteria for insulin resistance or insulin sensitivity based on the modified insulin-suppression test. Serum was collected from 43 participants to measure circulating concentrations of CD44. Subcutaneous adipose tissue was obtained from 17 participants to compare CD44, its ligand osteopontin (OPN, also known as SPP1) and pro-inflammatory gene expression. CD44 expression on adipose tissue macrophage (ATM) surfaces was determined by flow cytometry. Serum CD44 concentrations were significantly increased in insulin-resistant (IR) participants. CD44 gene expression in subcutaneous adipose tissue was threefold higher in the IR subgroup. The expression of OPN, CD68 and IL6 was also significantly elevated in IR individuals. CD44 gene expression correlated significantly with CD68 and IL6 expression. CD44 density on ATMs was associated with proinflammatory M1 polarisation. CD44 and OPN in human adipose tissue are associated with localised inflammation and systemic insulin resistance. This receptor-ligand pair is worthy of further research as a potentially modifiable contributor to human insulin resistance and type 2 diabetes.

  11. Transmembrane signaling by a chimera of the Escherichia coli aspartate receptor and the human insulin receptor.

    PubMed Central

    Moe, G R; Bollag, G E; Koshland, D E

    1989-01-01

    Since many receptors apparently contain only one or two membrane-spanning segments, their transmembrane topology should be similar. This feature suggests that these receptors share common mechanisms of transmembrane signaling. To test the degree of conservation of signaling properties, a chimeric receptor containing the ligand-binding extracellular domain of the Escherichia coli aspartate chemoreceptor and the cytosolic portion of the human insulin receptor was constructed. This chimeric receptor is active as a tyrosine kinase, and aspartate stimulates its activity. Some interesting differences are noted in the target proteins phosphorylated by the chimera compared to the wild-type insulin receptor. These results indicate that features of the signaling mechanisms used by these diverse receptors are conserved, but that interesting changes in the protein properties are caused by differences in the neighboring domains. Images PMID:2548185

  12. X-ray investigation of gene-engineered human insulin crystallized from a solution containing polysialic acid

    PubMed Central

    Timofeev, V. I.; Chuprov-Netochin, R. N.; Samigina, V. R.; Bezuglov, V. V.; Miroshnikov, K. A.; Kuranova, I. P.

    2010-01-01

    Attempts to crystallize the noncovalent complex of recombinant human insulin with polysialic acid were carried out under normal and microgravity conditions. Both crystal types belonged to the same space group, I213, with unit-cell parameters a = b = c = 77.365 Å, α = β = γ = 90.00°. The reported space group and unit-cell parameters are almost identical to those of cubic insulin reported in the PDB. The results of X-ray studies confirmed that the crystals obtained were cubic insulin crystals and that they contained no polysialic acid or its fragments. Electron-density maps were calculated using X-ray diffraction sets from earth-grown and microgravity-grown crystals and the three-dimensional structure of the insulin molecule was determined and refined. The conformation and secondary-structural elements of the insulin molecule in different crystal forms were compared. PMID:20208155

  13. Vitamin D regulates steroidogenesis and insulin-like growth factor binding protein-1 (IGFBP-1) production in human ovarian cells.

    PubMed

    Parikh, G; Varadinova, M; Suwandhi, P; Araki, T; Rosenwaks, Z; Poretsky, L; Seto-Young, D

    2010-09-01

    Vitamin D Receptor (VDR) is expressed in both animal and human ovarian tissue, however, the role of vitamin D in human ovarian steroidogenesis is unknown. Cultured human ovarian cells were incubated in tissue culture medium supplemented with appropriate substrates, with or without 50 pM-150 pM or 50 nM-150 nM of 1,25-(OH)2D3, and in the presence or absence of insulin. Progesterone, testosterone, estrone, estradiol, and IGFBP-1 concentrations in conditioned tissue culture medium were measured. Vitamin D receptor was present in human ovarian cells. 1,25-(OH)2D3 stimulated progesterone production by 13% (p<0.001), estradiol production by 9% (p<0.02), and estrone production by 21% (p<0.002). Insulin and 1,25-(OH)2D3 acted synergistically to increase estradiol production by 60% (p<0.005). 1,25-(OH)2D3 alone stimulated IGFBP-1 production by 24% (p<0.001), however, in the presence of insulin, 1,25-(OH)2D3 enhanced insulin-induced inhibition of IGFBP-1 production by 13% (p<0.009). Vitamin D stimulates ovarian steroidogenesis and IGFBP-1 production in human ovarian cells likely acting via vitamin D receptor. Insulin and vitamin D synergistically stimulate estradiol production. Vitamin D also enhances inhibitory effect of insulin on IGFBP-1 production.

  14. Determination of human insulin and its analogues in human blood using liquid chromatography coupled to ion mobility mass spectrometry (LC-IM-MS).

    PubMed

    Thomas, Andreas; Schänzer, Wilhelm; Thevis, Mario

    2014-01-01

    The qualitative and quantitative determination of insulin from human blood samples is an emerging topic in doping controls as well as in other related disciplines (e.g. forensics). Beside the therapeutic use, insulin represents a prohibited, performance enhancing substance in sports drug testing. In both cases accurate, sensitive, specific, and unambiguous determination of the target peptide is of the utmost importance. The challenges concerning identifying insulins in blood by liquid chromatography coupled to ion mobility mass spectrometry (LC-IM-MS) are detecting the basal concentrations of approximately 0.2 ng/mL and covering the hyperinsulinaemic clamps at > 3 ng/mL simultaneously using up to 200 μL of plasma or serum. This is achieved by immunoaffinity purification of the insulins with magnetic beads and subsequent separation by micro-scale liquid chromatography coupled to ion mobility / high resolution mass spectrometry. The method includes human insulin as well as the synthetic or animal analogues insulin aspart, glulisine, glargine, detemir, lispro, bovine, and porcine insulin. The method validation shows reliable results considering specificity, limit of detection (0.2 ng/mL except for detemir: 0.8 ng/mL), limit of quantification (0.5 ng/mL for human insulin), precision (CV < 20%), linearity (r > 0.99), recovery, accuracy (>90%), robustness (plasma/serum), and ion suppression. For quantification of human insulin a labelled internal standard ([[(2) H10 ]-Leu(B6,B11,B15,B17) ] - human Insulin) is introduced. By means of the additional ion mobility separation of the different analogues, the chromatographic run time is shortened to 8 min without losing specificity. As proof-of-concept, the procedure was successfully applied to different blood specimens from diabetic patients receiving recombinant synthetic analogues. Copyright © 2014 John Wiley & Sons, Ltd.

  15. Large-Eddy Simulation of Premixed and Partially Premixed Turbulent Combustion Using a Level Set Method

    NASA Astrophysics Data System (ADS)

    Duchamp de Lageneste, Laurent; Pitsch, Heinz

    2001-11-01

    Level-set methods (G-equation) have been recently used in the context of RANS to model turbulent premixed (Hermann 2000) or partially premixed (Chen 1999) combustion. By directly taking into account unsteady effects, LES can be expected to improve predictions over RANS. Since the reaction zone thickness of premixed flames in technical devices is usually much smaller than the LES grid spacing, chemical reactions completely occur on the sub-grid scales and hence have to be modeled entirely. In the level-set methodology, the flame front is represented by an arbitrary iso-surface G0 of a scalar field G whose evolution is described by the so-called G-equation. This equation is only valid at G=G_0, and hence decoupled from other G levels. Heat release is then modeled using a flamelet approach in which temperature is determined as a function of G and the mixture-fraction Z. In the present study, the proposed approach has been formulated for LES and validated using data from a turbulent Bunsen burner experiment (Chen, Peters 1996). Simulation of an experimental Lean Premixed Prevapourised (LPP) dump combustor (Besson, Bruel 1999, 2000) under different premixed or partially premixed conditions will also be presented.

  16. Decreased STARD10 Expression Is Associated with Defective Insulin Secretion in Humans and Mice.

    PubMed

    Carrat, Gaelle R; Hu, Ming; Nguyen-Tu, Marie-Sophie; Chabosseau, Pauline; Gaulton, Kyle J; van de Bunt, Martijn; Siddiq, Afshan; Falchi, Mario; Thurner, Matthias; Canouil, Mickaël; Pattou, Francois; Leclerc, Isabelle; Pullen, Timothy J; Cane, Matthew C; Prabhala, Priyanka; Greenwald, William; Schulte, Anke; Marchetti, Piero; Ibberson, Mark; MacDonald, Patrick E; Manning Fox, Jocelyn E; Gloyn, Anna L; Froguel, Philippe; Solimena, Michele; McCarthy, Mark I; Rutter, Guy A

    2017-02-02

    Genetic variants near ARAP1 (CENTD2) and STARD10 influence type 2 diabetes (T2D) risk. The risk alleles impair glucose-induced insulin secretion and, paradoxically but characteristically, are associated with decreased proinsulin:insulin ratios, indicating improved proinsulin conversion. Neither the identity of the causal variants nor the gene(s) through which risk is conferred have been firmly established. Whereas ARAP1 encodes a GTPase activating protein, STARD10 is a member of the steroidogenic acute regulatory protein (StAR)-related lipid transfer protein family. By integrating genetic fine-mapping and epigenomic annotation data and performing promoter-reporter and chromatin conformational capture (3C) studies in β cell lines, we localize the causal variant(s) at this locus to a 5 kb region that overlaps a stretch-enhancer active in islets. This region contains several highly correlated T2D-risk variants, including the rs140130268 indel. Expression QTL analysis of islet transcriptomes from three independent subject groups demonstrated that T2D-risk allele carriers displayed reduced levels of STARD10 mRNA, with no concomitant change in ARAP1 mRNA levels. Correspondingly, β-cell-selective deletion of StarD10 in mice led to impaired glucose-stimulated Ca(2+) dynamics and insulin secretion and recapitulated the pattern of improved proinsulin processing observed at the human GWAS signal. Conversely, overexpression of StarD10 in the adult β cell improved glucose tolerance in high fat-fed animals. In contrast, manipulation of Arap1 in β cells had no impact on insulin secretion or proinsulin conversion in mice. This convergence of human and murine data provides compelling evidence that the T2D risk associated with variation at this locus is mediated through reduction in STARD10 expression in the β cell. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  17. Production of human insulin in an E. coli system with Met-Lys-human proinsulin as the expressed precursor

    SciTech Connect

    Jin-Qiu Chen; Hong-Tao Zhang; Mei-Hao Hu; Jian-Guo Tang

    1995-10-01

    The construction of a gene encoding Lys-human proinsulin, its direct expression in E.coli, and the simple purification procedure are described here. The temperature inducible promotor was employed for induction in a very short time. The expression level could reach 20-30%. After a simple downstream processing and only one step of Sephadex G50 purification, 150 mg recombinant Lys-human proinsulin with a purity of up to 90% could be obtained easily from 1 L of high density fermentation medium. The obtained product is in the form of Met-Lys-human proinsulin because of the failure of the bacterial host to remove the initiator methionine residue. The Lys-human proinsulin could be changed into human insulin by tryspin and carboxypeptidase B treatment in later steps. After separation with DEAE Sephadex A25, human insulin with expected amino acid composition and full native biological activity could be obtained with a yield of 50 mg/L fermentation medium. 20 refs., 5 figs., 4 tabs.

  18. Physiological hyperinsulinemia has no detectable effect on access of macromolecules to insulin-sensitive tissues in healthy humans.

    PubMed

    Weinhandl, Heinz; Pachler, Christoph; Mader, Julia K; Ikeoka, Dimas; Mautner, Agnes; Falk, Andreas; Suppan, Maria; Pieber, Thomas R; Ellmerer, Martin

    2007-09-01

    Physiologically elevated insulin concentrations promote access of macromolecules to skeletal muscle in dogs. We investigated whether insulin has a stimulating effect on the access of macromolecules to insulin-sensitive tissues in humans as well. In a randomized, controlled trial, euglycemic-hyperinsulinemic clamp (1.2 mU x kg(-1) x min(-1) insulin) and saline control experiments were performed in 10 healthy volunteers (aged 27.5 +/- 4 years, BMI 22.6 +/- 1.6 kg/m(2)). Distribution and clearance parameters of inulin were determined in a whole-body approach, combining primed intravenous infusion of inulin with compartment modeling. Inulin kinetics were measured in serum using open-flow microperfusion in interstitial fluid of femoral skeletal muscle and subcutaneous adipose tissue. Inulin kinetics in serum were best described using a three-compartment model incorporating a serum and a fast and a slow equilibrating compartment. Inulin kinetics in interstitial fluid of peripheral insulin-sensitive tissues were best represented by the slow equilibrating compartment. Serum and interstitial fluid inulin kinetics were comparable between the insulin and saline groups. Qualitative analysis of inulin kinetics was confirmed by model-derived distribution and clearance parameters of inulin. Physiological hyperinsulinemia (473 +/- 6 vs. 18 +/- 2 pmol/l for the insulin and saline group, respectively; P < 0.001) indicated no effect on distribution volume (98.2 +/- 6.2 vs. 102.5 +/- 5.7 ml/kg; NS) or exchange parameter (217.6 +/- 34.2 vs. 243.1 +/- 28.6 ml/min; NS) of inulin to peripheral insulin-sensitive tissues. All other parameters identified by the model were also comparable between the groups. Our data suggest that in contrast to studies performed in dogs, insulin at physiological concentrations does not augment recruitment of insulin-sensitive tissues in healthy humans.

  19. Release of skeletal muscle peptide fragments identifies individual proteins degraded during insulin deprivation in type 1 diabetic humans and mice.

    PubMed

    Robinson, Matthew M; Dasari, Surendra; Karakelides, Helen; Bergen, H Robert; Nair, K Sreekumaran

    2016-09-01

    Insulin regulates skeletal muscle protein degradation, but the types of proteins being degraded in vivo remain to be determined due to methodological limitations. We present a method to assess the types of skeletal muscle proteins that are degraded by extracting their degradation products as low-molecular weight (LMW) peptides from muscle samples. High-resolution mass spectrometry was used to identify the original intact proteins that generated the LMW peptides, which we validated in rodents and then applied to humans. We deprived insulin from insulin-treated streptozotocin (STZ) diabetic mice for 6 and 96 h and for 8 h in type 1 diabetic humans (T1D) for comparison with insulin-treated conditions. Protein degradation was measured using activation of autophagy and proteasome pathways, stable isotope tracers, and LMW approaches. In mice, insulin deprivation activated proteasome pathways and autophagy in muscle homogenates and isolated mitochondria. Reproducibility analysis of LMW extracts revealed that ∼80% of proteins were detected consistently. As expected, insulin deprivation increased whole body protein turnover in T1D. Individual protein degradation increased with insulin deprivation, including those involved in mitochondrial function, proteome homeostasis, nDNA support, and contractile/cytoskeleton. Individual mitochondrial proteins that generated more LMW fragment with insulin deprivation included ATP synthase subunit-γ (+0.5-fold, P = 0.007) and cytochrome c oxidase subunit 6 (+0.305-fold, P = 0.03). In conclusion, identifying LMW peptide fragments offers an approach to determine the degradation of individual proteins. Insulin deprivation increases degradation of select proteins and provides insight into the regulatory role of insulin in maintaining proteome homeostasis, especially of mitochondria. Copyright © 2016 the American Physiological Society.

  20. Computational and structural evidence for neurotransmitter-mediated modulation of the oligomeric states of human insulin in storage granules.

    PubMed

    Palivec, Vladimír; Viola, Cristina M; Kozak, Mateusz; Ganderton, Timothy R; Křížková, Květoslava; Turkenburg, Johan P; Halušková, Petra; Žáková, Lenka; Jiráček, Jiří; Jungwirth, Pavel; Brzozowski, Andrzej M

    2017-05-19

    Human insulin is a pivotal protein hormone controlling metabolism, growth, and aging and whose malfunctioning underlies diabetes, some cancers, and neurodegeneration. Despite its central position in human physiology, the in vivo oligomeric state and conformation of insulin in its storage granules in the pancreas are not known. In contrast, many in vitro structures of hexamers of this hormone are available and fall into three conformational states: T6, T3R(f)3, and R6 As there is strong evidence for accumulation of neurotransmitters, such as serotonin and dopamine, in insulin storage granules in pancreatic β-cells, we probed by molecular dynamics (MD) and protein crystallography (PC) if these endogenous ligands affect and stabilize insulin oligomers. Parallel studies independently converged on the observation that serotonin binds well within the insulin hexamer (site I), stabilizing it in the T3R3 conformation. Both methods indicated serotonin binding on the hexamer surface (site III) as well. MD, but not PC, indicated that dopamine was also a good site III ligand. Some of the PC studies also included arginine, which may be abundant in insulin granules upon processing of pro-insulin, and stable T3R3 hexamers loaded with both serotonin and arginine were obtained. The MD and PC results were supported further by in solution spectroscopic studies with R-state-specific chromophore. Our results indicate that the T3R3 oligomer is a plausible insulin pancreatic storage form, resulting from its complex interplay with neurotransmitters, and pro-insulin processing products. These findings may have implications for clinical insulin formulations. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Pancreatic Transdifferentiation and Glucose-Regulated Production of Human Insulin in the H4IIE Rat Liver Cell Line

    PubMed Central

    Ren, Binhai; Tao, Chang; Swan, Margaret Anne; Joachim, Nichole; Martiniello-Wilks, Rosetta; Nassif, Najah T.; O’Brien, Bronwyn A.; Simpson, Ann M.

    2016-01-01

    Due to the limitations of current treatment regimes, gene therapy is a promising strategy being explored to correct blood glucose concentrations in diabetic patients. In the current study, we used a retroviral vector to deliver either the human insulin gene alone, the rat NeuroD1 gene alone, or the human insulin gene and rat NeuroD1 genes together, to the rat liver cell line, H4IIE, to determine if storage of insulin and pancreatic transdifferentiation occurred. Stable clones were selected and expanded into cell lines: H4IIEins (insulin gene alone), H4IIE/ND (NeuroD1 gene alone), and H4IIEins/ND (insulin and NeuroD1 genes). The H4IIEins cells did not store insulin; however, H4IIE/ND and H4IIEins/ND cells stored 65.5 ± 5.6 and 1475.4 ± 171.8 pmol/insulin/5 × 106 cells, respectively. Additionally, several β cell transcription factors and pancreatic hormones were expressed in both H4IIE/ND and H4IIEins/ND cells. Electron microscopy revealed insulin storage vesicles in the H4IIE/ND and H4IIEins/ND cell lines. Regulated secretion of insulin to glucose (0–20 mmol/L) was seen in the H4IIEins/ND cell line. The H4IIEins/ND cells were transplanted into diabetic immunoincompetent mice, resulting in normalization of blood glucose. This data shows that the expression of NeuroD1 and insulin in liver cells may be a useful strategy for inducing islet neogenesis and reversing diabetes. PMID:27070593

  2. Pancreatic Transdifferentiation and Glucose-Regulated Production of Human Insulin in the H4IIE Rat Liver Cell Line.

    PubMed

    Ren, Binhai; Tao, Chang; Swan, Margaret Anne; Joachim, Nichole; Martiniello-Wilks, Rosetta; Nassif, Najah T; O'Brien, Bronwyn A; Simpson, Ann M

    2016-04-08

    Due to the limitations of current treatment regimes, gene therapy is a promising strategy being explored to correct blood glucose concentrations in diabetic patients. In the current study, we used a retroviral vector to deliver either the human insulin gene alone, the rat NeuroD1 gene alone, or the human insulin gene and rat NeuroD1 genes together, to the rat liver cell line, H4IIE, to determine if storage of insulin and pancreatic transdifferentiation occurred. Stable clones were selected and expanded into cell lines: H4IIEins (insulin gene alone), H4IIE/ND (NeuroD1 gene alone), and H4IIEins/ND (insulin and NeuroD1 genes). The H4IIEins cells did not store insulin; however, H4IIE/ND and H4IIEins/ND cells stored 65.5 ± 5.6 and 1475.4 ± 171.8 pmol/insulin/5 × 10⁶ cells, respectively. Additionally, several β cell transcription factors and pancreatic hormones were expressed in both H4IIE/ND and H4IIEins/ND cells. Electron microscopy revealed insulin storage vesicles in the H4IIE/ND and H4IIEins/ND cell lines. Regulated secretion of insulin to glucose (0-20 mmol/L) was seen in the H4IIEins/ND cell line. The H4IIEins/ND cells were transplanted into diabetic immunoincompetent mice, resulting in normalization of blood glucose. This data shows that the expression of NeuroD1 and insulin in liver cells may be a useful strategy for inducing islet neogenesis and reversing diabetes.

  3. Premixed flame stabilization on a bluff body

    SciTech Connect

    Hertzberg, J.R.; Talbot, L.

    1986-01-01

    This paper studies the effects of fluid mechanics on combustion, the density and velocity fields of a turbulent premixed flame stabilized on a bluff-body flameholder observed by using Rayleigh scattering for single point measurements of density and laser Doppler velocimetry for velocity data. The stabilization region near the flameholder is the focus of this work. There are several motivations for a study of this nature. First, this configuration, in which a premixed flame is stabilized in the free shear layer of a separated wake behind a bluff body has implications for both mixing layer and basic flame anchoring questions, making this a fundamental problem. Second, since most premixed flames require some form of stabilization for laboratory study, understanding the interaction of the stabilization region and the propagating premixed flame is essential for the interpretation of any resultant data. Third, flame stabilization is of ongoing concern for ramjets, turbojet afterburners and other practical combustion systems. Finally, global models of flame stabilization are based on assumptions, such as the presence of stable recirculating vortices and high turbulence in the recirculation zone, which require verification.

  4. Simulation of lean premixed turbulent combustion

    NASA Astrophysics Data System (ADS)

    Bell, J.; Day, M.; Almgren, A.; Lijewski, M.; Rendleman, C.; Cheng, R.; Shepherd, I.

    2006-09-01

    There is considerable technological interest in developing new fuel-flexible combustion systems that can burn fuels such as hydrogen or syngas. Lean premixed systems have the potential to burn these types of fuels with high efficiency and low NOx emissions due to reduced burnt gas temperatures. Although traditional Scientific approaches based on theory and laboratory experiment have played essential roles in developing our current understanding of premixed combustion, they are unable to meet the challenges of designing fuel-flexible lean premixed combustion devices. Computation, with its ability to deal with complexity and its unlimited access to data, has the potential for addressing these challenges. Realizing this potential requires the ability to perform high fidelity simulations of turbulent lean premixed flames under realistic conditions. In this paper, we examine the specialized mathematical structure of these combustion problems and discuss simulation approaches that exploit this structure. Using these ideas we can dramatically reduce computational cost, making it possible to perform high-fidelity simulations of realistic flames. We illustrate this methodology by considering ultra-lean hydrogen flames and discuss how this type of simulation is changing the way researchers study combustion.

  5. Understanding the structural differences between spherical and rod-shaped human insulin nanoparticles produced by supercritical fluids precipitation.

    PubMed

    Park, Yeonju; Seo, Yongil; Chae, Boknam; Pyo, Dongjin; Chung, Hoeil; Hwang, Hyonseok; Jung, Young Mee

    2015-02-02

    In this study, the thermal denaturation mechanism and secondary structures of two types of human insulin nanoparticles produced by a process of solution-enhanced dispersion by supercritical fluids using dimethyl sulfoxide (DMSO) and ethanol (EtOH) solutions of insulin are investigated using spectroscopic approaches and molecular dynamics calculations. First, the temperature-dependent IR spectra of spherical and rod-shaped insulin nanoparticles prepared from DMSO and EtOH solution, respectively, are analyzed using principal component analysis (PCA) and 2D correlation spectroscopy to obtain a deeper understanding of the molecular structures and thermal behavior of the two insulin particle shapes. All-atom molecular dynamics (AAMD) calculations are performed to investigate the influence of the solvent molecules on the production of the insulin nanoparticles and to elucidate the geometric differences between the two types of nanoparticles. The results of the PCA, the 2D correlation spectroscopic analysis, and the AAMD calculations clearly reveal that the thermal denaturation mechanisms and the degrees of hydrogen bonding in the spherical and rod-shaped insulin nanoparticles are different. The polarity of the solvent might not alter the structure or function of the insulin produced, but the solvent polarity does influence the synthesis of different shapes of insulin nanoparticles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Protamine-containing insulin but not analog insulin and duration of insulin use are risk factors for the production of insulin autoantibodies in insulin-treated patients with diabetes mellitus.

    PubMed

    Nishimura, Hidenao; Iizuka, Katsumi; Takeda, Jun

    2014-01-01

    Insulin autoantibodies can be produced by insulin injections but rarely cause severe side effects such as glucose instability and insulin allergy. We study the characteristics of insulin autoantibody-positive diabetic patients with a medical history of insulin therapy using single and multiple (adjusted for age, sex, type of diabetes) logistic regression analyses. Associations between insulin autoantibodies and age, sex, type of diabetes, HbA1c, and serum creatinine were not significant, but the association between insulin autoantibodies and duration of insulin use was significant. Unadjusted and adjusted odds ratios were 1.08 (1.02-1.14) and 1.07 (1.01-1.14), respectively. Unadjusted and adjusted odds ratios for protamine-containing insulin were 3.08 (1.49-6.34) and 4.27 (1.90-9.58), respectively. The adjusted odds ratios for premixed biphasic insulin and intermediate-acting insulin were 2.21 (1.03-4.73) and 2.35 (1.01-5.49), respectively. Associations between insulin autoantibodies and any insulin analog were not significant. These results suggest that protamine-containing insulin and duration of insulin use are risk factors for the production of insulin autoantibodies. If patients with poorly controlled diabetes have a history of protamine-containing insulin therapy over a long time, the appearance of insulin autoantibodies should be monitored.

  7. Flame propagation under partially-premixed conditions

    NASA Technical Reports Server (NTRS)

    Ruetsch, Gregory R.

    1994-01-01

    This study concentrates on developing a better understanding of triple flames. We relax the assumption of zero heat release, address the issue of stabilization, and, in order to investigate the role that heat release plays in flame propagation in partially premixed combustion, we return to a simple flow field and investigate the behavior of flames in a laminar environment. We solve the compressible Navier-Stokes equations in a two-dimensional domain. At the boundaries, we use an inflow boundary condition on the left and nearly-perfect reflective boundary conditions, required to avoid pressure drift, at the outflow and sides. After the flow and flame are initialized, the mixture fraction is varied at the inlet from its uniform stoichiometric value to a tanh profile varying from zero to one. As the mixture fraction gradient reaches the flame surface only the centerline is exposed to the stoichionetric mixture fraction and locally maintains the planar flame speed and reaction rate. Above this point the mixture is fuel rich, and below fuel lean. As a result, these regions of non-unity equivalence ratio burn less, the reaction rate drops, and the local flame speed is reduced. The excess fuel and oxidizer then combine behind the premixed flame along the stoichiometric surface and burn in a trailing diffusion flame. Thus the 'triple' flame refers to the fuel-rich premixed flame, the fuel-lean premixed flame, and the trailing diffusion flame. Due to heat release, the normal velocity across the flame is increased, whereas the tangential component remains unchanged. Far-field flame speed, local flame speed, and their differences are shown as a function of the local mixing thickness. It was also determined that the lateral position of the flame affects stabilization, and the distribution of the reaction rate along the premixed wings of triple flames affects flame propagation.

  8. Resveratrol ameliorates the chemical and microbial induction of inflammation and insulin resistance in human placenta, adipose tissue and skeletal muscle.

    PubMed

    Tran, Ha T; Liong, Stella; Lim, Ratana; Barker, Gillian; Lappas, Martha

    2017-01-01

    Gestational diabetes mellitus (GDM), which complicates up to 20% of all pregnancies, is associated with low-grade maternal inflammation and peripheral insulin resistance. Sterile inflammation and infection are key mediators of this inflammation and peripheral insulin resistance. Resveratrol, a stilbene-type phytophenol, has been implicated to exert beneficial properties including potent anti-inflammatory and antidiabetic effects in non-pregnant humans and experimental animal models of GDM. However, studies showing the effects of resveratrol on inflammation and insulin resistance associated with GDM in human tissues have been limited. In this study, human placenta, adipose (omental and subcutaneous) tissue and skeletal muscle were stimulated with pro-inflammatory cytokines TNF-α and IL-1β, the bacterial product lipopolysaccharide (LPS) and the synthetic viral dsRNA analogue polyinosinic:polycytidylic acid (poly(I:C)) to induce a GDM-like model. Treatment with resveratrol significantly reduced the expression and secretion of pro-inflammatory cytokines IL-6, IL-1α, IL-1β and pro-inflammatory chemokines IL-8 and MCP-1 in human placenta and omental and subcutaneous adipose tissue. Resveratrol also significantly restored the defects in the insulin signalling pathway and glucose uptake induced by TNF-α, LPS and poly(I:C). Collectively, these findings suggest that resveratrol reduces inflammation and insulin resistance induced by chemical and microbial products. Resveratrol may be a useful preventative therapeutic for pregnancies complicated by inflammation and insulin resistance, like GDM.

  9. Interferon gamma attenuates insulin signaling, lipid storage, and differentiation in human adipocytes via activation of the JAK/STAT pathway.

    PubMed

    McGillicuddy, Fiona C; Chiquoine, Elise H; Hinkle, Christine C; Kim, Roy J; Shah, Rachana; Roche, Helen M; Smyth, Emer M; Reilly, Muredach P

    2009-11-13

    Recent reports demonstrate T-cell infiltration of adipose tissue in early obesity. We hypothesized that interferon (IFN) gamma, a major T-cell inflammatory cytokine, would attenuate human adipocyte functions and sought to establish signaling mechanisms. Differentiated human adipocytes were treated with IFNgamma +/- pharmacological inhibitors prior to insulin stimulation. [(3)H]Glucose uptake and AKT phosphorylation were assessed as markers of insulin sensitivity. IFNgamma induced sustained loss of insulin-stimulated glucose uptake in human adipocytes, coincident with reduced Akt phosphorylation and down-regulation of the insulin receptor, insulin receptor substrate-1, and GLUT4. Loss of adipocyte triglyceride storage was observed with IFNgamma co-incident with reduced expression of peroxisome proliferator-activated receptor gamma, adiponectin, perilipin, fatty acid synthase, and lipoprotein lipase. Treatment with IFNgamma also blocked differentiation of pre-adipocytes to the mature phenotype. IFNgamma-induced robust STAT1 phosphorylation and SOCS1 mRNA expression, with modest, transient STAT3 phosphorylation and SOCS3 induction. Preincubation with a non-selective JAK inhibitor restored glucose uptake and Akt phosphorylation while completely reversing IFNgamma suppression of adipogenic mRNAs and adipocyte differentiation. Specific inhibition of JAK2 or JAK3 failed to block IFNgamma effects suggesting a predominant role for JAK1-STAT1. We demonstrate that IFNgamma attenuates insulin sensitivity and suppresses differentiation in human adipocytes, an effect most likely mediated via sustained JAK-STAT1 pathway activation.

  10. Interferon γ Attenuates Insulin Signaling, Lipid Storage, and Differentiation in Human Adipocytes via Activation of the JAK/STAT Pathway*

    PubMed Central

    McGillicuddy, Fiona C.; Chiquoine, Elise H.; Hinkle, Christine C.; Kim, Roy J.; Shah, Rachana; Roche, Helen M.; Smyth, Emer M.; Reilly, Muredach P.

    2009-01-01

    Recent reports demonstrate T-cell infiltration of adipose tissue in early obesity. We hypothesized that interferon (IFN) γ, a major T-cell inflammatory cytokine, would attenuate human adipocyte functions and sought to establish signaling mechanisms. Differentiated human adipocytes were treated with IFNγ ± pharmacological inhibitors prior to insulin stimulation. [3H]Glucose uptake and AKT phosphorylation were assessed as markers of insulin sensitivity. IFNγ induced sustained loss of insulin-stimulated glucose uptake in human adipocytes, coincident with reduced Akt phosphorylation and down-regulation of the insulin receptor, insulin receptor substrate-1, and GLUT4. Loss of adipocyte triglyceride storage was observed with IFNγ co-incident with reduced expression of peroxisome proliferator-activated receptor γ, adiponectin, perilipin, fatty acid synthase, and lipoprotein lipase. Treatment with IFNγ also blocked differentiation of pre-adipocytes to the mature phenotype. IFNγ-induced robust STAT1 phosphorylation and SOCS1 mRNA expression, with modest, transient STAT3 phosphorylation and SOCS3 induction. Preincubation with a non-selective JAK inhibitor restored glucose uptake and Akt phosphorylation while completely reversing IFNγ suppression of adipogenic mRNAs and adipocyte differentiation. Specific inhibition of JAK2 or JAK3 failed to block IFNγ effects suggesting a predominant role for JAK1-STAT1. We demonstrate that IFNγ attenuates insulin sensitivity and suppresses differentiation in human adipocytes, an effect most likely mediated via sustained JAK-STAT1 pathway activation. PMID:19776010

  11. Resveratrol ameliorates the chemical and microbial induction of inflammation and insulin resistance in human placenta, adipose tissue and skeletal muscle

    PubMed Central

    Tran, Ha T.; Liong, Stella; Lim, Ratana; Barker, Gillian

    2017-01-01

    Gestational diabetes mellitus (GDM), which complicates up to 20% of all pregnancies, is associated with low-grade maternal inflammation and peripheral insulin resistance. Sterile inflammation and infection are key mediators of this inflammation and peripheral insulin resistance. Resveratrol, a stilbene-type phytophenol, has been implicated to exert beneficial properties including potent anti-inflammatory and antidiabetic effects in non-pregnant humans and experimental animal models of GDM. However, studies showing the effects of resveratrol on inflammation and insulin resistance associated with GDM in human tissues have been limited. In this study, human placenta, adipose (omental and subcutaneous) tissue and skeletal muscle were stimulated with pro-inflammatory cytokines TNF-α and IL-1β, the bacterial product lipopolysaccharide (LPS) and the synthetic viral dsRNA analogue polyinosinic:polycytidylic acid (poly(I:C)) to induce a GDM-like model. Treatment with resveratrol significantly reduced the expression and secretion of pro-inflammatory cytokines IL-6, IL-1α, IL-1β and pro-inflammatory chemokines IL-8 and MCP-1 in human placenta and omental and subcutaneous adipose tissue. Resveratrol also significantly restored the defects in the insulin signalling pathway and glucose uptake induced by TNF-α, LPS and poly(I:C). Collectively, these findings suggest that resveratrol reduces inflammation and insulin resistance induced by chemical and microbial products. Resveratrol may be a useful preventative therapeutic for pregnancies complicated by inflammation and insulin resistance, like GDM. PMID:28278187

  12. SIRT3 Deficiency Induces Endothelial Insulin Resistance and Blunts Endothelial-Dependent Vasorelaxation in Mice and Human with Obesity

    PubMed Central

    Yang, Lu; Zhang, Julei; Xing, Wenjuan; Zhang, Xing; Xu, Jie; Zhang, Haifeng; Chen, Li; Ning, Xiaona; Ji, Gang; Li, Jia; Zhao, Qingchuan; Gao, Feng

    2016-01-01

    Recent evidence implicates the critical role of Sirtuin 3 (SIRT3) in the development of many metabolic diseases, but the contribution of SIRT3 to vascular homeostasis remains largely unknown. The aim of this study was to investigate the role of SIRT3 in endothelial insulin resistance and vascular dysfunction in obesity. We found an impaired insulin-induced mesenteric vasorelaxation and concomitant reduced vascular SIRT3 expression in morbid obese human subjects compared with the non-obese subjects. Downregulation of SIRT3 in cultured human endothelial cells increased mitochondrial reactive oxygen species (mtROS) and impaired insulin signaling as evidenced by decreased phosphorylation of Akt and endothelial nitric oxide synthase and subsequent reduced nitric oxide (NO) release. In addition, obese mice induced by 24-week high-fat diet (HFD) displayed an impaired endothelium-dependent vasorelaxation to both insulin and acetylcholine, which was further exacerbated by the gene deletion of Sirt3. Scavenging of mtROS not only restored insulin-stimulated NO production in SIRT3 knockdown cells, but also improved insulin-induced vasorelaxation in SIRT3 knockout mice fed with HFD. Taken together, our findings suggest that SIRT3 positively regulates endothelial insulin sensitivity and show that SIRT3 deficiency and resultant increased mtROS contribute to vascular dysfunction in obesity. PMID:27000941

  13. SIRT3 Deficiency Induces Endothelial Insulin Resistance and Blunts Endothelial-Dependent Vasorelaxation in Mice and Human with Obesity.

    PubMed

    Yang, Lu; Zhang, Julei; Xing, Wenjuan; Zhang, Xing; Xu, Jie; Zhang, Haifeng; Chen, Li; Ning, Xiaona; Ji, Gang; Li, Jia; Zhao, Qingchuan; Gao, Feng

    2016-03-22

    Recent evidence implicates the critical role of Sirtuin 3 (SIRT3) in the development of many metabolic diseases, but the contribution of SIRT3 to vascular homeostasis remains largely unknown. The aim of this study was to investigate the role of SIRT3 in endothelial insulin resistance and vascular dysfunction in obesity. We found an impaired insulin-induced mesenteric vasorelaxation and concomitant reduced vascular SIRT3 expression in morbid obese human subjects compared with the non-obese subjects. Downregulation of SIRT3 in cultured human endothelial cells increased mitochondrial reactive oxygen species (mtROS) and impaired insulin signaling as evidenced by decreased phosphorylation of Akt and endothelial nitric oxide synthase and subsequent reduced nitric oxide (NO) release. In addition, obese mice induced by 24-week high-fat diet (HFD) displayed an impaired endothelium-dependent vasorelaxation to both insulin and acetylcholine, which was further exacerbated by the gene deletion of Sirt3. Scavenging of mtROS not only restored insulin-stimulated NO production in SIRT3 knockdown cells, but also improved insulin-induced vasorelaxation in SIRT3 knockout mice fed with HFD. Taken together, our findings suggest that SIRT3 positively regulates endothelial insulin sensitivity and show that SIRT3 deficiency and resultant increased mtROS contribute to vascular dysfunction in obesity.

  14. Hepatic Diacylglycerol-Associated Protein Kinase Cε Translocation Links Hepatic Steatosis to Hepatic Insulin Resistance in Humans.

    PubMed

    Ter Horst, Kasper W; Gilijamse, Pim W; Versteeg, Ruth I; Ackermans, Mariette T; Nederveen, Aart J; la Fleur, Susanne E; Romijn, Johannes A; Nieuwdorp, Max; Zhang, Dongyan; Samuel, Varman T; Vatner, Daniel F; Petersen, Kitt F; Shulman, Gerald I; Serlie, Mireille J

    2017-06-06

    Hepatic lipid accumulation has been implicated in the development of insulin resistance, but translational evidence in humans is limited. We investigated the relationship between liver fat and tissue-specific insulin sensitivity in 133 obese subjects. Although the presence of hepatic steatosis in obese subjects was associated with hepatic, adipose tissue, and peripheral insulin resistance, we found that intrahepatic triglycerides were not strictly sufficient or essential for hepatic insulin resistance. Thus, to examine the molecular mechanisms that link hepatic steatosis to hepatic insulin resistance, we comprehensively analyzed liver biopsies from a subset of 29 subjects. Here, hepatic cytosolic diacylglycerol content, but not hepatic ceramide content, was increased in subjects with hepatic insulin resistance. Moreover, cytosolic diacylglycerols were strongly associated with hepatic PKCε activation, as reflected by PKCε translocation to the plasma membrane. These results demonstrate the relevance of hepatic diacylglycerol-induced PKCε activation in the pathogenesis of NAFLD-associated hepatic insulin resistance in humans. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  15. Reactive oxygen species (ROS) induce chemical and structural changes on human insulin in vitro, including alterations in its immunoreactivity.

    PubMed

    Olivares-Corichi, Ivonne M; Ceballos, Guillermo; Ortega-Camarillo, Clara; Guzman-Grenfell, Alberto M; Hicks, Juan J

    2005-01-01

    Oxidative stress occurs when the production of reactive oxygen species (ROS) exceeds the endogenous antioxidant defense. Peroxidations induced by ROS are the key of chemical and structural modifications of biomolecules including circulating proteins. To elucidate the effect of ROS on circulating proteins and considering the presence of oxidative stress in Diabetes Mellitus, the effects of ROS, in vitro, on human insulin were studied. We utilized the Fenton reaction for free hydroxyl radical (HO*) generation in presence of human recombinant insulin measuring chemical changes on its molecular structure. The induced changes in insulin were: a) significant increase on absorbance (280 nm) due to phenylalanine hydroxylation (0.023 +/- 0.007 to 0.13 +/- 0.07). b) Peroxidation products formed on amino acids side branches (peroxyl and alcohoxyl group); measured as increased capacity of reduce nitroblue of tetrazolium (NBT) to formazan (0.007 +/- 0.007 to 0.06 +/- 0.02). c) Increased concentration of free carbonyl groups (8.8 +/- 8.7 to 45.6 +/- 20.2 pmoles dinitrophenylhidrazones/nmol insulin) with lost of secondary structure, and d) Modification of epithopes decreasing the insulin antigen-antibody reactivity measured as a decrease in insulin concentration by RIA. In conclusion, the radical hydroxyl in vitro is able to induce molecular modifications on insulin.

  16. c-Jun represses the human insulin promoter activity that depends on multiple cAMP response elements.

    PubMed Central

    Inagaki, N; Maekawa, T; Sudo, T; Ishii, S; Seino, Y; Imura, H

    1992-01-01

    Glucose is known to increase the cAMP concentration in pancreatic beta cells. To determine the mechanism by which cAMP augments insulin gene expression, we first identified the cAMP response elements (CREs) of the human insulin gene. In DNase I footprint analysis, the bacterially synthesized CRE-binding protein, CRE-BP1, protected four sites: two sites in the region upstream from the insulin core promoter, one site in the first exon, and one site in the first intron. To examine the roles of those four sites, we constructed a series of DNA plasmids in which the wild-type and mutant insulin promoters were linked to the chloramphenicol acetyl-transferase gene. Studies of the transcriptional activity of these plasmids after transfection into hamster insulinoma (HIT) cells showed that these four sites contributed additively to the cAMP inducibility of the insulin promoter. Surprisingly, the c-jun protooncogene product (c-Jun) repressed the cAMP-induced activity of the insulin promoter in a cotransfection assay with the c-Jun expression plasmid. Northern blot analysis demonstrated that the level of c-jun mRNA was dramatically increased by glucose deprivation in HIT cells. These results suggest that glucose may regulate expression of the human insulin gene through multiple CREs and c-Jun. Images PMID:1310538

  17. Yacon syrup: beneficial effects on obesity and insulin resistance in humans.

    PubMed

    Genta, Susana; Cabrera, Wilfredo; Habib, Natalia; Pons, Juan; Carillo, Iván Manrique; Grau, Alfredo; Sánchez, Sara

    2009-04-01

    Syrup obtained from yacon roots could be well positioned as a nutraceutical product due to its high fructooligosaccharides content. We examined the beneficial effects and tolerance of yacon syrup on human health. Obese and slightly dyslipidemic pre-menopausal women were studied over a 120-day period in a double-blind placebo-controlled experiment. We used two doses of yacon syrup, 0.29 g and 0.14 g fructooligosaccharides/kg/day. At the start and end of the study, anthropometric measurements, blood glucose, calcium, lipid and insulin concentrations and Homeostasis Model Assessment index were determined. The recommended daily consumption of yacon syrup with no undesirable gastrointestinal effects is 0.14 g fructooligosaccharides/kg. Daily intake of yacon syrup produced a significant decrease in body weight, waist circumference and body mass index. Additionally, decrease in fasting serum insulin and Homeostasis Model Assessment index was observed. The consumption of yacon syrup increased defecation frequency and satiety sensation. Fasting glucose and serum lipids were not affected by syrup treatment and the only positive effect was found in serum LDL-cholesterol levels. Yacon syrup is a good source of fructooligosaccharides and its long-term consumption produced beneficial health effects on obese pre-menopausal women with insulin resistance.

  18. Evidence for increased recombination near the human insulin gene: implication for disease association studies.

    PubMed Central

    Chakravarti, A; Elbein, S C; Permutt, M A

    1986-01-01

    Haplotypes for four new restriction site polymorphisms (detected by Rsa I, Taq I, HincII, and Sac I) and a previously identified DNA length polymorphism (5' FP), all at the insulin locus, have been studied in U.S. Blacks, African Blacks, Caucasians, and Pima Indians. Black populations are polymorphic for all five markers, whereas the other groups are polymorphic for Rsa I, Taq I, and 5' FP only. The data suggest that approximately equal to 1 in 550 base pairs is variant in this region. The polymorphisms, even though located within 20 kilobases, display low levels of nonrandom association. Population genetic analysis suggests that recombination within this 20-kilobase segment occurs 24 times more frequently than expected if crossing-over occurred uniformly throughout the human genome. These findings suggest that population associations between DNA polymorphisms and disease susceptibility genes near the insulin gene or structural mutations in the insulin gene will be weak. Thus, population studies would probably require large sample sizes to detect associations. However, the low levels of nonrandom association increase the information content of the locus for linkage studies, which is the best alternative for discovering disease susceptibility genes. PMID:3006026

  19. Lipoprotein lipase in human milk: compartmentalization and effect of fasting, insulin, and glucose.

    PubMed

    Neville, M C; Waxman, L J; Jensen, D; Eckel, R H

    1991-02-01

    The object of this study was to investigate the effect of maternal metabolic state on the activity of lipoprotein lipase (LPL) in human milk. Although the total LPL activity in milk was not significantly affected by up to three cycles of freezing and thawing, the amount of LPL associated with the cream fraction of the milk increased from an average of less than 10% to about 70% after this treatment. The enzyme was relatively stable when the milk was stored on ice, losing activity at a rate of about 1% per hour. At 37 degrees C degradation was more rapid, about 7% per hour. When LPL activity was measured in samples taken at hourly intervals by breast pump, using oxytocin to achieve a complete letdown at each pumping, activity was found to double from the first to the third pumping. Thereafter the activity was stable under fasting conditions. Hyperglycemic and euglycemic, hyperinsulinemic glucose clamp protocols were used to evaluate the effects of glucose and insulin. Both high plasma glucose and high plasma insulin in the presence of normal glucose significantly increased LPL activity within 4 hours. We conclude that, like adipose, tissue LPL, mammary LPL is regulated by plasma insulin.

  20. Sulfate anion delays the self-assembly of human insulin by modifying the aggregation pathway.

    PubMed

    Owczarz, Marta; Arosio, Paolo

    2014-07-01

    The understanding of the molecular mechanisms underlying protein self-assembly and of their dependence on solvent composition has implications in a large number of biological and biotechnological systems. In this work, we characterize the aggregation process of human insulin at acidic pH in the presence of sulfate ions using a combination of Thioflavin T fluorescence, dynamic light scattering, size exclusion chromatography, Fourier transform infrared spectroscopy, and transmission electron microscopy. It is found that the increase of sulfate concentration inhibits the conversion of insulin molecules into aggregates by modifying the aggregation pathway. At low sulfate concentrations (0-5 mM) insulin forms amyloid fibrils following the nucleated polymerization mechanism commonly observed under acidic conditions in the presence of monovalent anions. When the sulfate concentration is increased above 5 mM, the sulfate anion induces the salting-out of ∼18-20% of insulin molecules into reversible amorphous aggregates, which retain a large content of α-helix structures. During time these aggregates undergo structure rearrangements into β-sheet structures, which are able to recruit monomers and bind to the Thioflavin T dye. The alternative aggregation mechanism observed at large sulfate concentrations is characterized by a larger activation energy and leads to more polymorphic structures with respect to the self-assembly in the presence of chloride ions. The system shown in this work represents a case where amorphous aggregates on pathway to the formation of structures with amyloid features could be detected and analyzed. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  1. Differential effects of prednisone and growth hormone on fuel metabolism and insulin antagonism in humans

    SciTech Connect

    Horber, F.F.; Marsh, H.M.; Haymond, M.W. )

    1991-01-01

    Human growth hormone (hGH) and prednisone cause insulin resistance and glucose intolerance. However, it is unknown whether hGH and prednisone antagonize insulin action on protein, fat, and carbohydrate metabolism by a common or independent mechanism. Therefore, protein, fat, and carbohydrate metabolism was assessed simultaneously in four groups of eight subjects each after 7 days of placebo, recombinant DNA hGH (rhGH; 0.1 mg.kg-1.day-1), prednisone (0.8 mg.kg-1.day-1), or rhGH and prednisone administration after an 18-h fast and during gut infusion of glucose and amino acids (fed state). Fasting plasma glucose concentrations were similar during placebo and rhGH but elevated (P less than 0.001) during combined treatment, whereas plasma insulin concentrations were higher (237 +/- 57 pmol/ml, P less than 0.001) during combined than during placebo, rhGH, or prednisone treatment (34, 52, and 91 pM, respectively). In the fed state, plasma glucose concentrations were elevated only during combined treatment (11.3 +/- 2.1 mM, P less than 0.001). Plasma insulin concentrations were elevated during therapy with prednisone alone and rhGH alone (667 +/- 72 and 564 +/- 65 pmol/ml, respectively, P less than 0.001) compared with placebo (226 +/- 44 pmol/ml) but lower than with the combined rhGH and prednisone treatment (1249 +/- 54 pmol/ml, P less than 0.01). Protein oxidation {sup 14}C leucine increased (P less than 0.001) with prednisone therapy, decreased (P less than 0.001) with rhGH treatment, and was normal during the combined treatment.

  2. Interferon-gamma released from omental adipose tissue of insulin-resistant humans alters adipocyte phenotype and impairs response to insulin and adiponectin release.

    PubMed

    Wentworth, J M; Zhang, J-G; Bandala-Sanchez, E; Naselli, G; Liu, R; Ritchie, M; Smyth, G K; O'Brien, P E; Harrison, L C

    2017-08-03

    Inflammatory factors derived from adipose tissue have been implicated in mediating insulin resistance in obesity. We sought to identify these using explanted human adipose tissue exposed to innate and adaptive immune stimuli. Subcutaneous and omental adipose tissue from obese, insulin-resistant donors was cultured in the presence of macrophage and T-cell stimuli, and the conditioned medium tested for its ability to inhibit insulin-stimulated glucose uptake into human Simpson-Golabi-Behmel Syndrome (SGBS) adipocytes. The nature of the inhibitory factor in conditioned medium was characterized physicochemically, inferred by gene microarray analysis and confirmed by antibody neutralization. Conditioned medium from omental adipose tissue exposed to a combination of macrophage- and T-cell stimuli inhibited insulin action and adiponectin secretion in SGBS adipocytes. This effect was associated with a pronounced change in adipocyte morphology, characterized by a decreased number of lipid droplets of increased size. The bioactivity of conditioned medium was abolished by trypsin treatment and had a molecular weight of 46 kDa by gel filtration. SGBS adipocytes exposed to a bioactive medium expressed multiple gene transcripts regulated by interferon-gamma (IFN-γ). Recombinant human IFN-γ recapitulated the effects of the bioactive medium and neutralizing antibody against IFN-γ but not other candidate factors abrogated medium bioactivity. IFN-γ released from inflamed omental adipose tissue may contribute to the metabolic abnormalities seen in human obesity.International Journal of Obesity advance online publication, 22 August 2017; doi:10.1038/ijo.2017.180.

  3. Characterization of the Human Insulin-induced Gene 2 (INSIG2) Promoter

    PubMed Central

    Fernández-Alvarez, Ana; Soledad Alvarez, María; Cucarella, Carme; Casado, Marta

    2010-01-01

    Insulin-induced gene 2 (INSIG2) and its homolog INSIG1 encode closely related endoplasmic reticulum proteins that regulate the proteolytic activation of sterol regulatory element-binding proteins, transcription factors that activate the synthesis of cholesterol and fatty acids in animal cells. Several studies have been carried out to identify INSIG2 genetic variants associated with metabolic diseases. However, few data have been published regarding the regulation of INSIG2 gene expression. Two Insig2 transcripts have been described in rodents through the use of different promoters that produce different noncoding first exons that splice into a common second exon. Herein we report the cloning and characterization of the human INSIG2 promoter and the detection of an INSIG2-specific transcript homologous to the Insig2b mouse variant in human liver. Deletion analyses on 3 kb of 5′-flanking DNA of the human INSIG2 gene revealed the functional importance of a 350-bp region upstream of the transcription start site. Mutated analyses, chromatin immunoprecipitation assays, and RNA interference analyses unveiled the significance of an Ets-consensus motif in the proximal region and the interaction of the Ets family member SAP1a (serum response factor (SRF) accessory protein-1a) with this region of the human INSIG2 promoter. Moreover, our findings suggest that insulin activated the human INSIG2 promoter in a process mediated by phosphorylated SAP1a. Overall, these results map the functional elements in the human INSIG2 promoter sequence and suggest an unexpected regulation of INSIG2 gene expression in human liver. PMID:20145255

  4. Insulin and GH signaling in human skeletal muscle in vivo following exogenous GH exposure: impact of an oral glucose load.

    PubMed

    Krusenstjerna-Hafstrøm, Thomas; Madsen, Michael; Vendelbo, Mikkel H; Pedersen, Steen B; Christiansen, Jens S; Møller, Niels; Jessen, Niels; Jørgensen, Jens O L

    2011-05-03

    GH induces acute insulin resistance in skeletal muscle in vivo, which in rodent models has been attributed to crosstalk between GH and insulin signaling pathways. Our objective was to characterize time course changes in signaling pathways for GH and insulin in human skeletal muscle in vivo following GH exposure in the presence and absence of an oral glucose load. Eight young men were studied in a single-blinded randomized crossover design on 3 occasions: 1) after an intravenous GH bolus 2) after an intravenous GH bolus plus an oral glucose load (OGTT), and 3) after intravenous saline plus OGTT. Muscle biopsies were taken at t = 0, 30, 60, and 120. Blood was sampled at frequent intervals for assessment of GH, insulin, glucose, and free fatty acids (FFA). GH increased AUC(glucose) after an OGTT (p<0.05) without significant changes in serum insulin levels. GH induced phosphorylation of STAT5 independently of the OGTT. Conversely, the OGTT induced acute phosphorylation of the insulin signaling proteins Akt (ser(473) and thr(308)), and AS160.The combination of OGTT and GH suppressed Akt activation, whereas the downstream expression of AS160 was amplified by GH. WE CONCLUDED THE FOLLOWING: 1) A physiological GH bolus activates STAT5 signaling pathways in skeletal muscle irrespective of ambient glucose and insulin levels 2) Insulin resistance induced by GH occurs without a distinct suppression of insulin signaling proteins 3) The accentuation of the glucose-stimulated activation of AS 160 by GH does however indicate a potential crosstalk between insulin and GH. ClinicalTrials.gov NCT00477997.

  5. Insulin Stimulates Translocation of Human GLUT4 to the Membrane in Fat Bodies of Transgenic Drosophila melanogaster

    PubMed Central

    Crivat, Georgeta; Lizunov, Vladimir A.; Li, Caroline R.; Stenkula, Karin G.; Zimmerberg, Joshua; Cushman, Samuel W.; Pick, Leslie

    2013-01-01

    The fruit fly Drosophila melanogaster is an excellent model system for studies of genes controlling development and disease. However, its applicability to physiological systems is less clear because of metabolic differences between insects and mammals. Insulin signaling has been studied in mammals because of relevance to diabetes and other diseases but there are many parallels between mammalian and insect pathways. For example, deletion of Drosophila Insulin-Like Peptides resulted in ‘diabetic’ flies with elevated circulating sugar levels. Whether this situation reflects failure of sugar uptake into peripheral tissues as seen in mammals is unclear and depends upon whether flies harbor the machinery to mount mammalian-like insulin-dependent sugar uptake responses. Here we asked whether Drosophila fat cells are competent to respond to insulin with mammalian-like regulated trafficking of sugar transporters. Transgenic Drosophila expressing human glucose transporter-4 (GLUT4), the sugar transporter expressed primarily in insulin-responsive tissues, were generated. After expression in fat bodies, GLUT4 intracellular trafficking and localization were monitored by confocal and total internal reflection fluorescence microscopy (TIRFM). We found that fat body cells responded to insulin with increased GLUT4 trafficking and translocation to the plasma membrane. While the amplitude of these responses was relatively weak in animals reared on a standard diet, it was greatly enhanced in animals reared on sugar-restricted diets, suggesting that flies fed standard diets are insulin resistant. Our findings demonstrate that flies are competent to mobilize translocation of sugar transporters to the cell surface in response to insulin. They suggest that Drosophila fat cells are primed for a response to insulin and that these pathways are down-regulated when animals are exposed to constant, high levels of sugar. Finally, these studies are the first to use TIRFM to monitor insulin

  6. 208 PRODUCTION OF TRANSGENIC CLONED BUFFALO (BUBALUS BUBALIS) EMBRYOS CONTAINING HUMAN INSULIN GENE THROUGH HAND-GUIDED CLONING.

    PubMed

    Mehta, P; Kaushik, R; Chauhan, M S; Palta, P; Singla, S; Singh, M K; Manik, R S

    2016-01-01

    Diabetes is a growing disease worldwide and has emerged as a major healthcare problem in India. Insulin is an essential medicine for the treatment of diabetes. Large dairy animals, such as buffaloes and cows, may be used as bioreactors for cost-effective production of human insulin. The present study was aimed to produce transgenic buffalo embryos containing the human insulin gene through hand-guided cloning for production of transgenic animals. Buffalo female fetal fibroblast cells at passage number 3 were transfected using mammary gland- specific expression vector containing the human insulin gene under buffalo β-lactoglobulin promoter by nucleofection method and cultured with G418 drug for 3 weeks to obtain positive transgenic cell clones. Transgene integration into buffalo female fetal fibroblast genome was confirmed by PCR and Southern blotting. Nontransfected and transgene integrated cells were used as nuclear donors to produce embryos by the hand-guided cloning technique. The developmental competence and quality of embryos as judged by total cell number and TUNEL assay were compared among transgenic and nontransgenic (control) embryos. The blastocyst rate was lower (P<0.05) for transgenic embryos than that of nontransgenic cloned embryos (35.97±2.16v. 45.80±4.11, respectively). The apoptotic index was found to be lower (P<0.05) for control blastocysts than that for transgenic blastocysts. However, the total cell number was similar (P<0.05) among transgenic and control cloned blastocysts. Thus, transgenic cells, and subsequently transgenic embryos containing the human insulin gene, were successfully produced and transferred in recipients. In the future, these may be used for production of transgenic buffalo expressing human insulin in its milk and thus can be further utilised in large-scale production of human insulin.

  7. Dynamics and structure of turbulent premixed flames

    NASA Technical Reports Server (NTRS)

    Bilger, R. W.; Swaminathan, N.; Ruetsch, G. R.; Smith, N. S. A.

    1995-01-01

    In earlier work (Mantel & Bilger, 1994) the structure of the turbulent premixed flame was investigated using statistics based on conditional averaging with the reaction progress variable as the conditioning variable. The DNS data base of Trouve and Poinsot (1994) was used in this investigation. Attention was focused on the conditional dissipation and conditional axial velocity in the flame with a view to modeling these quantities for use in the conditional moment closure (CMC) approach to analysis of kinetics in premixed flames (Bilger, 1993). Two remarkable findings were made: there was almost no acceleration of the axial velocity in the flame front itself; and the conditional scalar dissipation remained as high, or higher, than that found in laminar premixed flames. The first finding was surprising since in laminar flames all the fluid acceleration occurs through the flame front, and this could be expected also for turbulent premixed flames at the flamelet limit. The finding gave hope of inventing a new approach to the dynamics of turbulent premixed flames through use of rapid distortion theory or an unsteady Bernoulli equation. This could lead to a new second order closure for turbulent premixed flames. The second finding was contrary to our measurements with laser diagnostics in lean hydrocarbon flames where it is found that conditional scalar dissipation drops dramatically below that for laminar flamelets when the turbulence intensity becomes high. Such behavior was not explainable with a one-step kinetic model, even at non-unity Lewis number. It could be due to depletion of H2 from the reaction zone by preferential diffusion. The capacity of the flame to generate radicals is critically dependent on the levels of H2 present (Bilger, et al., 1991). It seemed that a DNS computation with a multistep reduced mechanism would be worthwhile if a way could be found to make this feasible. Truly innovative approaches to complex problems often come only when there is the

  8. AMP-activated protein kinase (AMPK) regulates the insulin-induced activation of the nitric oxide synthase in human platelets.

    PubMed

    Fleming, Ingrid; Schulz, Christian; Fichtlscherer, Birgit; Kemp, Bruce E; Fisslthaler, Beate; Busse, Rudi

    2003-11-01

    Little is known about the signaling cascades that eventually regulate the activity of the endothelial nitric oxide synthase (eNOS) in platelets. Here, we investigated the effects of insulin on the phosphorylation and activation of eNOS in washed human platelets and in endothelial cells. Insulin activated the protein kinase Akt in cultured endothelial cells and increased the phosphorylation of eNOS on Ser(1177) but failed to increase endothelial cyclic GMP levels or to elicit the relaxation of endothelium-intact porcine coronary arteries. In platelets, insulin also elicited the activation of Akt as well as the phosphorylation of eNOS and initiated NO production which was associated with increased cyclic GMP levels and the inhibition of thrombin-induced aggregation. The insulin-induced inhibition of aggregation was accompanied by a decreased Ca(2+) response to thrombin and was also prevented by N(omega) nitro-L-arginine. In platelets, but not in endothelial cells, insulin induced the activation of the AMP-activated protein kinase (AMPK), a metabolic stress-sensing kinase which was sensitive to the phosphatidylinositol 3-kinase (PI3-K) inhibitor wortmannin and the AMPK inhibitor iodotubercidin. Moreover, the insulin-mediated inhibition of thrombin-induced aggregation was prevented by iodotubercidin. Insulin-independent activation of the AMPK using 5-aminoimidazole-4-carboxamide ribonucleoside, increased platelet eNOS phosphorylation, increased cyclic GMP levels and attenuated platelet aggregation. These results highlight the differences in the signal transduction cascade activated by insulin in endothelial cells and platelets, and demonstrate that insulin stimulates the formation of NO in human platelets, in the absence of an increase in Ca(2+), by acti-vating PI3-K and AMPK which phosphorylates eNOS on Ser(1177).

  9. The human insulin gene-linked polymorphic region adopts a G-quartet structure in chromatin assembled in vitro.

    PubMed

    Hammond-Kosack, M C; Kilpatrick, M W; Docherty, K

    1993-04-01

    The insulin gene-linked polymorphic region (ILPR), located 363 bp upstream of the human insulin gene, is composed of tandem repeats of the consensus sequence ACAGGGGT(G/C)(T/C)GGGG. It has previously been shown that an insulin gene fragment containing the ILPR adopts an altered DNA structure in vitro. Furthermore, oligonucleotides containing the consensus repeat sequence exhibit multiple quadriplex DNA structures. The present study was undertaken to determine whether such altered DNA structures existed within the ILPR when the insulin gene was assembled into chromatin in vitro. Chromatin assembly was achieved using histones and an extract from unfertilized eggs from Xenopus laevis. The presence of altered DNA conformations within the 5' region of the human insulin gene was investigated using the structural probe nuclease P1. Nuclease P1 recognized multiple distinct sites in the 5' flanking region of the human insulin gene in naked DNA. Most of these sites disappeared when the recombinant plasmid DNA was treated with histones and unfertilized egg extract. In the assembled DNA, the ILPR appeared as the major site of nuclease P1 hypersensitivity. Fine-mapping of the multiple reactive sites within the ILPR showed a pattern characteristic of G-quartet foldback structures similar to those that have been observed for telomeric DNA.

  10. Insulin inhibits human erythrocyte cAMP accumulation and ATP release: role of PDE3 and PI3K

    PubMed Central

    Hanson, Madelyn S.; Stephenson, Alan H.; Bowles, Elizabeth A.; Sprague, Randy S.

    2010-01-01

    In non – erythroid cells, insulin stimulates a signal transduction pathway that results in the activation of phosphoinositide 3 – kinase (PI3K) and phosphorylation of phosphodiesterase 3 (PDE3). Erythrocytes possess insulin receptors, PI3K, and PDE3B. These cells release ATP via a signaling pathway that requires activation of the G protein, Gi, as well as increases in cAMP. Although insulin inhibits ATP release from human erythrocytes in response to Gi activation with mastoparan 7 (Mas 7), no effect on cAMP was described. Here, we investigated the hypothesis that insulin activates PDE3 in human erythrocytes via a PI3K – mediated mechanism resulting in cAMP hydrolysis and inhibition of ATP release. We show that insulin attenuates Mas 7 – induced increases in cAMP and that selective inhibitors of PDE3 (cilostazol) or PI3K (LY294002) rescue this effect of insulin. In addition, we demonstrated that both cilostazol and LY294002 prevent insulin – induced attenuation of Mas 7 – induced ATP release. These results provide support for the hypothesis that insulin activates PDE3 in erythrocytes via a PI3K – dependent mechanism. Once activated, PDE3 limits Mas 7 – induced increases in intracellular cAMP. This effect of insulin leads, ultimately, to decreased ATP release in response to Mas 7. Since the activation of Gi is required for reduced O2 tension – induced ATP release from erythrocytes, and insulin has been shown to inhibit that release, these results suggest a novel mechanism by which supraphysiological levels of plasma insulin, such as those reported in humans with prediabetes, could inhibit ATP release from erythrocytes. Erythrocyte – derived ATP has been shown to participate in the matching of O2 supply with demand in skeletal muscle. Thus, pathological increases in circulating insulin could, via activation of PDE3, inhibit ATP release from erythrocytes depriving the peripheral circulation of a mechanism that regulates delivery of O2 to meet tissue

  11. Dual effect of insulin resistance and cadmium on human granulosa cells - In vitro study.

    PubMed

    Belani, Muskaan; Shah, Preeti; Banker, Manish; Gupta, Sarita

    2016-12-15

    Combined exposure of cadmium (Cd) and insulin resistance (IR) might be responsible for subfertility. In the present study, we investigated the effects of Cd in vitro in IR human granulosa cells. Isolated human granulosa cells from control and polycystic ovary syndrome (PCOS) follicular fluid samples were confirmed for IR by decrease in protein expression of insulin receptor-β. Control and IR human granulosa cells were then incubated with or without 32μM Cd. The combined effect of IR with 32μM Cd in granulosa cells demonstrated significant decrease in expression of StAR, CYP11A1, CYP19A1, 17β-HSD, 3β-HSD, FSH-R and LH-R. Decrease was also observed in progesterone and estradiol concentrations as compared to control. Additionally, increase in protein expression of cleaved PARP-F2, active caspase-3 and a positive staining for Annexin V and PI indicated apoptosis as the mode of increased cell death ultimately leading to decreased steroidogenesis, as observed through the combined exposure. Taken together the results suggest decrease in steroidogenesis ultimately leading to abnormal development of the follicle thus compromising fertility at the level of preconception. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Structural analogs of human insulin-like growth factor I with reduced affinity for serum binding proteins and the type 2 insulin-like growth factor receptor

    SciTech Connect

    Bayne, M.L.; Applebaum, J.; Chicchi, G.G.; Hayes, N.S.; Green, B.G.; Cascieri, M.A.

    1988-05-05

    Four structural analogs of human insulin-like growth factor I (hIGF-I) have been prepared by site-directed mutagenesis of a synthetic IGF-I gene and subsequent expression and purification of the mutant protein from the conditioned media of transformed yeast. (Phe/sup -1/, Val/sup 1/, Asn/sup 2/, Gln/sup 3/, His/sup 4/, Ser/sup 8/, His/sup 9/, Glu/sup 12/, Tyr/sup 15/, Leu/sup 16/)IGF-I (B-chain mutant), in which the first 16 amino acids of hIGF-I were replaced with the first 17 amino acids of the B-chain of insulin, has >1000-, 100-, and 2-fold reduced potency for human serum binding proteins, the rat liver type 2 IGF receptor, and the human placental type 1 IGF receptor, respectively. The B-chain mutant also has 4-fold increased affinity for the human placental insulin receptor. (Gln/sup 3/, Ala/sup 4/) IGF-I has 4-fold reduced affinity for human serum binding proteins, but is equipotent to hIGF-I at the types 1 and 2 IGF and insulin receptors. (Tyr/sup 15/, Leu/sup 16/) IGH-I has 4-fold reduced affinity for human serum binding proteins and 10-fold increased affinity for the insulin receptor. The peptide in which these four-point mutations are combined, (Gln/sup 3/, Ala/sup 4/, Tyr/sup 15/,Leu/sup 16/)IGF-I, has 600-fold reduced affinity for the serum binding proteins. All four of these mutants stimulate DNA synthesis in the rat vascular smooth muscle cell line A10 with potencies reflecting their potency at the type 1 IGF receptor. These studies identify some of the domains of hIGF-I which are responsible for maintaining high affinity binding with the serum binding protein and the type 2 IGF receptor. In addition, These peptides will be useful in defining the role of the type 2 IGF receptor and serum binding proteins in the physiological actions of hIGF-I.

  13. Lipocalin 2 produces insulin resistance and can be upregulated by glucocorticoids in human adipose tissue.

    PubMed

    Kamble, Prasad G; Pereira, Maria J; Sidibeh, Cherno O; Amini, Sam; Sundbom, Magnus; Börjesson, Joey Lau; Eriksson, Jan W

    2016-05-15

    The adipokine lipocalin 2 is linked to obesity and metabolic disorders. However, its role in human adipose tissue glucose and lipid metabolism is not explored. Here we show that the synthetic glucocorticoid dexamethasone dose-dependently increased lipocalin 2 gene expression in subcutaneous and omental adipose tissue from pre-menopausal females, while it had no effect in post-menopausal females or in males. Subcutaneous adipose tissue from both genders treated with recombinant human lipocalin 2 showed a reduction in protein levels of GLUT1 and GLUT4 and in glucose uptake in isolated adipocytes. In subcutaneous adipose tissue, lipocalin 2 increased IL-6 gene expression whereas expression of PPARγ and adiponectin was reduced. Our findings suggest that lipocalin 2 can contribute to insulin resistance in human adipose tissue. In pre-menopausal females, it may partly mediate adverse metabolic effects exerted by glucocorticoid excess. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Effect of Dexamethasone, Insulin and EGF on the Myogenic Potential on Human Endometrial Stem Cell

    PubMed Central

    Jalali Tehrani, Hora; Parivar, Kazem; Ai, Jafar; Kajbafzadeh, Abdolmohammad; Rahbarghazi, Reza; Hashemi, Mehrdad; Sadeghizadeh, Majid

    2014-01-01

    Human endometrium contains mesenchymal stem cells (eMSC) which have the ability to differentiate into three cell lineages and the potential in therapeutic applications. We hypothesize that using environmental induction in culture media such as dexamethasone, human recombinant insulin and human epidermal growth factor (hEGF) can differentiate endometrial stem cells into myoblast. These agents have a broad range of effects in myoblast differentiation in-vitro. We used immunohystochemistry analysis and RT –PCR to evaluate the presence of skeletal muscle - specific proteins some of which are expressed in the early stage of differentiation including myoD and Desmin which expressed at later stages of differentiation. In conclusion eMSC can differentiate in culture media which contains above mentioned factors and use for therapeutic purpose in muscular degenerative disease. PMID:25237362

  15. The behavior of partially premixed flames

    NASA Astrophysics Data System (ADS)

    Choi, Chun Wai

    In this investigation, we have characterized the structure of two-dimensional partially-premixed slot burner flames through the measurement of the heat release topography, and the temperature and velocity distribution. The measurements were used to infer the flame stretch and the response of the local propagation speed of the inner rich premixed reaction zone in these flames to stretch rate variations due to hydrodynamic and curvature effects. The inner premixed reaction zone of the PPFs exhibits a highly curved portion near its tip and planar topography along its lower portion. An "effective flame speed" was characterized for two flames beyond the rich flammability limit that can only burn in a partially-premixed mode due to the synergy between the inner premixed and outer nonpremixed reaction zones. The reaction zone speed in the curved region increases significantly during the transition from a planar to curved topology due to curvature effects. The Markstein relation must be suitably modified to account for the curvature of the reaction zones for flame with negative curvature. Negative curvature increases the local value of the flame speed above the unstretched flame speed Su o while positive curvature decreases it below that value. Although curvature effects are included in the definition of stretch, they are not fully accounted for by the Su(kappa) Markstein linear relation. This implies that the curvature has an influence on Su through kappa and another more explicit effect. The propagation of triple flames in premixed and nonpremixed jet modes was investigated. The response of flame speed at the triple point to stretch has a turning behavior due to the variation of the radius of curvature while the flame is propagating downward. In normal gravity, the buoyant gases accelerate the flow in a direction opposite to the gravity vector, causing air entrainment, which enhances the mixing of the reactants with ambient laboratory air and consequently, influences the

  16. CART is overexpressed in human type 2 diabetic islets and inhibits glucagon secretion and increases insulin secretion.

    PubMed

    Abels, Mia; Riva, Matteo; Bennet, Hedvig; Ahlqvist, Emma; Dyachok, Oleg; Nagaraj, Vini; Shcherbina, Liliya; Fred, Rikard G; Poon, Wenny; Sörhede-Winzell, Maria; Fadista, Joao; Lindqvist, Andreas; Kask, Lena; Sathanoori, Ramasri; Dekker-Nitert, Marloes; Kuhar, Michael J; Ahrén, Bo; Wollheim, Claes B; Hansson, Ola; Tengholm, Anders; Fex, Malin; Renström, Erik; Groop, Leif; Lyssenko, Valeriya; Wierup, Nils

    2016-09-01

    Insufficient insulin release and hyperglucagonaemia are culprits in type 2 diabetes. Cocaine- and amphetamine-regulated transcript (CART, encoded by Cartpt) affects islet hormone secretion and beta cell survival in vitro in rats, and Cart (-/-) mice have diminished insulin secretion. We aimed to test if CART is differentially regulated in human type 2 diabetic islets and if CART affects insulin and glucagon secretion in vitro in humans and in vivo in mice. CART expression was assessed in human type 2 diabetic and non-diabetic control pancreases and rodent models of diabetes. Insulin and glucagon secretion was examined in isolated islets and in vivo in mice. Ca(2+) oscillation patterns and exocytosis were studied in mouse islets. We report an important role of CART in human islet function and glucose homeostasis in mice. CART was found to be expressed in human alpha and beta cells and in a subpopulation of mouse beta cells. Notably, CART expression was several fold higher in islets of type 2 diabetic humans and rodents. CART increased insulin secretion in vivo in mice and in human and mouse islets. Furthermore, CART increased beta cell exocytosis, altered the glucose-induced Ca(2+) signalling pattern in mouse islets from fast to slow oscillations and improved synchronisation of the oscillations between different islet regions. Finally, CART reduced glucagon secretion in human and mouse islets, as well as in vivo in mice via diminished alpha cell exocytosis. We conclude that CART is a regulator of glucose homeostasis and could play an important role in the pathophysiology of type 2 diabetes. Based on the ability of CART to increase insulin secretion and reduce glucagon secretion, CART-based agents could be a therapeutic modality in type 2 diabetes.

  17. Pseudoislet formation enhances gene expression, insulin secretion and cytoprotective mechanisms of clonal human insulin-secreting 1.1B4 cells.

    PubMed

    Green, Alastair D; Vasu, Srividya; McClenaghan, Neville H; Flatt, Peter R

    2015-10-01

    We have studied the effects of cell communication on human beta cell function and resistance to cytotoxicity using the novel human insulin-secreting cell line 1.1B4 configured as monolayers and pseudoislets. Incubation with the incretin gut hormones GLP-1 and GIP caused dose-dependent stimulation of insulin secretion from 1.1B4 cell monolayers and pseudoislets. The secretory responses were 1.5-2.7-fold greater than monolayers. Cell viability (MTT), DNA damage (comet assay) and apoptosis (acridine orange/ethidium bromide staining) were investigated following 2-h exposure of 1.1B4 monolayers and pseudoislets to ninhydrin, H2O2, streptozotocin, glucose, palmitate or cocktails of proinflammatory cytokines. All agents tested decreased viability and increased DNA damage and apoptosis in both 1.1B4 monolayers and pseudoislets. However, pseudoislets exhibited significantly greater resistance to cytotoxicity (1.5-2.7-fold increases in LD50) and lower levels of DNA damage (1.3-3.4-fold differences in percentage tail DNA and olive tail moment) and apoptosis (1.3-1.5-fold difference) compared to monolayers. Measurement of gene expression by reverse-transcription, real-time PCR showed that genes involved with insulin secretion (INS, PDX1, PCSK1, PCSK2, GLP1R and GIPR), cell-cell communication (GJD2, GJA1 and CDH1) and antioxidant defence (SOD1, SOD2, GPX1 and CAT) were significantly upregulated in pseudoislets compared to monolayers, whilst the expression of proapoptotic genes (NOS2, MAPK8, MAPK10 and NFKB1) showed no significant differences. In summary, these data indicate cell-communication associated with three-dimensional islet architecture is important both for effective insulin secretion and for protection of human beta cells against cytotoxicity.

  18. Electric stimulation of human fibroblasts causes an increase in Ca2+ influx and the exposure of additional insulin receptors.

    PubMed

    Bourguignon, G J; Jy, W; Bourguignon, L Y

    1989-08-01

    Previously we reported that treating human fibroblasts in cell culture with high-voltage, pulsed galvanic stimulation (HVPGS) can significantly increase cellular protein and DNA synthesis (Bourguignon and Bourguignon: FASEB J., 1:398-402, 1987). In this study we have identified two of the early cellular events which occur following exposure to HVPGS: 1) an increase in Ca2+ uptake from the external medium and 2) an increase in the number of insulin receptors on the fibroblast cell surface. The increase in Ca2+ uptake begins within the first minute of electric stimulation while increased insulin binding is not detected until the second minute of stimulation. The HVPGS-induced increase in insulin binding can be inhibited by bepridil, a specific Ca2+ channel blocker, suggesting that the Ca2+ influx is required for the exposure of additional insulin receptors on the cell surface. Furthermore, we have determined that the addition of insulin to electrically stimulated cultures results in 1) an immediate, second increase in Ca2+ uptake and 2) significant increases in both protein and DNA synthesis compared to cells which were not stimulated. All three of these insulin-dependent effects are also inhibited by bepridil. Based on these results, we propose that HVPGS initially triggers the opening of voltage-sensitive calcium channels in the fibroblast plasma membrane. The increased level of intracellular Ca2+ then induces the exposure of additional insulin receptors, the fibroblasts will significantly increase both protein and DNA synthesis.

  19. Are insulin analogues an unavoidable necessity for the treatment of type 2 diabetes in developing countries? The case of Jordan.

    PubMed

    Hyassat, D; Al Shekarchi, N; Jaddou, H; Liswi, M; El-Khateeb, M; Ajlouni, K M

    2015-12-13

    Despite their reported benefits in terms of glycaemic control, insulin analogues are expensive for patients in developing countries. This study in Jordan aimed to compare the effectiveness and adverse events of premixed human insulin (BHI30) versus premixed insulin analogue (BIAsp30) in patients with type 2 diabetes. In a retrospective cohort study from October 2012 to March 2013, outcomes (HbA1c, weight, hypoglycaemia and lipohypertrophy) were compared at baseline and 6 months after treatment in 628 patients. BHI30 produced a significantly greater reduction in HbA1c than did BIAsp30. This difference in HbA1c remained significant after controlling for the effects of age, sex, duration of diabetes, body mass index and hypoglycaemia (β-coefficient was -0.18 in favour of BHI30). Weight gain and mild hypoglycaemia was significantly higher with BHI30 than with BIAsp30. BHI30 achieved better reduction in HbA1c compared with BIAsp30, with less cost, slightly more weight gain and greater reported mild hypoglycaemia.

  20. Role of cannabinoid receptor 1 in human adipose tissue for lipolysis regulation and insulin resistance.

    PubMed

    Sidibeh, Cherno O; Pereira, Maria J; Lau Börjesson, Joey; Kamble, Prasad G; Skrtic, Stanko; Katsogiannos, Petros; Sundbom, Magnus; Svensson, Maria K; Eriksson, Jan W

    2017-03-01

    We recently showed that the peripheral cannabinoid receptor type 1 (CNR1) gene is upregulated by the synthetic glucocorticoid dexamethasone. CNR1 is highly expressed in the central nervous system and has been a drug target for the treatment of obesity. Here we explore the role of peripheral CNR1 in states of insulin resistance in human adipose tissue. Subcutaneous adipose tissue was obtained from well-controlled type 2 diabetes subjects and controls. Subcutaneous adipose tissue gene expression levels of CNR1 and endocannabinoid synthesizing and degrading enzymes were assessed. Furthermore, paired human subcutaneous adipose tissue and omental adipose tissue from non-diabetic volunteers undergoing kidney donation or bariatric surgery, was incubated with or without dexamethasone. Subcutaneous adipose tissue obtained from volunteers through needle biopsy was incubated with or without dexamethasone and in the presence or absence of the CNR1-specific antagonist AM281. CNR1 gene and protein expression, lipolysis and glucose uptake were evaluated. Subcutaneous adipose tissue CNR1 gene expression levels were 2-fold elevated in type 2 diabetes subjects compared with control subjects. Additionally, gene expression levels of CNR1 and endocannabinoid-regulating enzymes from both groups correlated with markers of insulin resistance. Dexamethasone increased CNR1 expression dose-dependently in subcutaneous adipose tissue and omental adipose tissue by up to 25-fold. Dexamethasone pre-treatment of subcutaneous adipose tissue increased lipolysis rate and reduced glucose uptake. Co-incubation with the CNR1 antagonist AM281 prevented the stimulatory effect on lipolysis, but had no effect on glucose uptake. CNR1 is upregulated in states of type 2 diabetes and insulin resistance. Furthermore, CNR1 is involved in glucocorticoid-regulated lipolysis. Peripheral CNR1 could be an interesting drug target in type 2 diabetes and dyslipidemia.

  1. Human visfatin expression: relationship to insulin sensitivity, intramyocellular lipids, and inflammation.

    PubMed

    Varma, Vijayalakshmi; Yao-Borengasser, Aiwei; Rasouli, Neda; Bodles, Angela M; Phanavanh, Bounleut; Lee, Mi-Jeong; Starks, Tasha; Kern, Leslie M; Spencer, Horace J; McGehee, Robert E; Fried, Susan K; Kern, Philip A

    2007-02-01

    Visfatin (VF) is a recently described adipokine preferentially secreted by visceral adipose tissue (VAT) with insulin mimetic properties. The aim of this study was to examine the association of VF with insulin sensitivity, intramyocellular lipids (IMCL), and inflammation in humans. VF mRNA was examined in paired samples of VAT and abdominal sc adipose tissue (SAT) obtained from subjects undergoing surgery. Plasma VF and VF mRNA was also examined in SAT and muscle tissue, obtained by biopsy from well-characterized subjects with normal or impaired glucose tolerance, with a wide range in body mass index (BMI) and insulin sensitivity (S(I)). The study was conducted at a University Hospital and General Clinical Research Center. S(I) was measured, and fat and muscle biopsies were performed. In impaired glucose tolerance subjects, these procedures were performed before and after treatment with pioglitazone or metformin. We measured the relationship between VF and obesity, S(I), adipose tissue inflammation, IMCL, and response to insulin sensitizers. No significant difference in VF mRNA was seen between SAT and VAT depots. VAT VF mRNA associated positively with BMI, whereas SAT VF mRNA decreased with BMI. SAT VF correlated positively with S(I), and the association of SAT VF mRNA with S(I) was independent of BMI. IMCL and markers of inflammation (adipose CD68 and plasma TNFalpha) were negatively associated with SAT VF. Impaired glucose tolerance subjects treated with pioglitazone showed no change in SAT VF mRNA despite a significant increase in S(I). Plasma VF and muscle VF mRNA did not correlate with BMI or S(I) or IMCL, and there was no change in muscle VF with either pioglitazone or metformin treatments. SAT VF is highly expressed in lean, more insulin-sensitive subjects and is attenuated in subjects with high IMCL, low S(I), and high levels of inflammatory markers. VAT VF and SAT VF are regulated oppositely with BMI.

  2. β-Cell Sensitivity to GLP-1 in Healthy Humans Is Variable and Proportional to Insulin Sensitivity

    PubMed Central

    Aulinger, Benedikt A.; Vahl, Torsten P.; Wilson-Pérez, Hilary E.; Prigeon, Ron L.

    2015-01-01

    Context: Glucagon-like peptide-1 (GLP-1) is an insulinotropic factor made in the gastrointestinal tract that is essential for normal glucose tolerance. Infusion of GLP-1 increases insulin secretion in both diabetic and nondiabetic humans. However, the degree to which people vary in their β-cell sensitivity to GLP-1 and the factors contributing to this variability have not been reported. Objective: The objective was to measure the sensitivity of insulin secretion to GLP-1 in cohorts of lean and obese subjects across a broad range of insulin sensitivity. Methods: Insulin secretion was measured during clamped hyperglycemia (7.2 mmol/L) and graded GLP-1 infusion in young, healthy subjects, and GLP-1 sensitivity was computed from the insulin secretion rate (ISR) during progressive increases in plasma GLP-1. Results: All subjects had fasting glucose values <5.2 mm. The obese subjects were insulin resistant compared to the lean group (homeostasis model of assessment 2 for insulin resistance: obese, 2.6 ± 0.5; lean, 0.8 ± 0.1; P < .001). ISR increased linearly in both cohorts with escalating doses of GLP-1, but the slope of ISR in response to GLP-1 was greater in the obese than in the lean subjects (obese, 0.17 ± 0.03 nmol/min/pm; lean, 0.05 ± 0.01 nmol/min/pm; P < .001). There was a significant association of β-cell GLP-1 sensitivity and insulin resistance (r = 0.83; P < .001), and after correction for homeostasis model of assessment 2 for insulin resistance, the slopes of ISR vs GLP-1 concentration did not differ in the two cohorts (obese, 0.08 ± 0.01; lean, 0.08 ± 0.01; P = .98). However, within the entire study group, β-cell GLP-1 sensitivity corrected for insulin resistance varied nearly 10-fold. Conclusions: Insulin secretion in response to GLP-1 is proportional to insulin resistance in healthy subjects. However, there is considerable variability in the sensitivity of the β-cell to GLP-1 that is independent of insulin sensitivity. PMID:25825945

  3. Reprogramming human gallbladder cells into insulin-producing β-like cells

    PubMed Central

    Benedetti, Eric; Wang, Yuhan; Pelz, Carl; Schug, Jonathan; Kaestner, Klaus H.; Grompe, Markus

    2017-01-01

    The gallbladder and cystic duct (GBCs) are parts of the extrahepatic biliary tree and share a common developmental origin with the ventral pancreas. Here, we report on the very first genetic reprogramming of patient-derived human GBCs to β-like cells for potential autologous cell replacement therapy for type 1 diabetes. We developed a robust method for large-scale expansion of human GBCs ex vivo. GBCs were reprogrammed into insulin-producing pancreatic β-like cells by a combined adenoviral-mediated expression of hallmark pancreatic endocrine transcription factors PDX1, MAFA, NEUROG3, and PAX6 and differentiation culture in vitro. The reprogrammed GBCs (rGBCs) strongly induced the production of insulin and pancreatic endocrine genes and these responded to glucose stimulation in vitro. rGBCs also expressed an islet-specific surface marker, which was used to enrich for the most highly reprogrammed cells. More importantly, global mRNA and microRNA expression profiles and protein immunostaining indicated that rGBCs adopted an overall β-like state and these rGBCs engrafted in immunodeficient mice. Furthermore, comparative global expression analyses identified putative regulators of human biliary to β cell fate conversion. In summary, we have developed, for the first time, a reliable and robust genetic reprogramming and culture expansion of primary human GBCs—derived from multiple unrelated donors—into pancreatic β-like cells ex vivo, thus showing that human gallbladder is a potentially rich source of reprogrammable cells for autologous cell therapy in diabetes. PMID:28813430

  4. Studies of Premixed Laminar and Turbulent Flames at Microgravity

    NASA Technical Reports Server (NTRS)

    Kwon, O. C.; Abid, M.; Porres, J.; Liu, J. B.; Ronney, P. D.; Struk, P. M.; Weiland, K. J.

    2003-01-01

    Several topics relating to premixed flame behavior at reduced gravity have been studied. These topics include: (1) flame balls; (2) flame structure and stability at low Lewis number; (3) experimental simulation of buoyancy effects in premixed flames using aqueous autocatalytic reactions; and (4) premixed flame propagation in Hele-Shaw cells. Because of space limitations, only topic (1) is discussed here, emphasizing results from experiments on the recent STS-107 Space Shuttle mission, along with numerical modeling efforts.

  5. Effect of insulin on human skeletal muscle mitochondrial ATP production, protein synthesis, and mRNA transcripts

    PubMed Central

    Stump, Craig S.; Short, Kevin R.; Bigelow, Maureen L.; Schimke, Jill M.; Nair, K. Sreekumaran

    2003-01-01

    Mitochondria are the primary site of skeletal muscle fuel metabolism and ATP production. Although insulin is a major regulator of fuel metabolism, its effect on mitochondrial ATP production is not known. Here we report increases in vastus lateralis muscle mitochondrial ATP production capacity (32–42%) in healthy humans (P < 0.01) i.v. infused with insulin (1.5 milliunits/kg of fat-free mass per min) while clamping glucose, amino acids, glucagon, and growth hormone. Increased ATP production occurred in association with increased mRNA levels from both mitochondrial (NADH dehydrogenase subunit IV) and nuclear [cytochrome c oxidase (COX) subunit IV] genes (164–180%) encoding mitochondrial proteins (P < 0.05). In addition, muscle mitochondrial protein synthesis, and COX and citrate synthase enzyme activities were increased by insulin (P < 0.05). Further studies demonstrated no effect of low to high insulin levels on muscle mitochondrial ATP production for people with type 2 diabetes mellitus, whereas matched nondiabetic controls increased 16–26% (P < 0.02) when four different substrate combinations were used. In conclusion, insulin stimulates mitochondrial oxidative phosphorylation in skeletal muscle along with synthesis of gene transcripts and mitochondrial protein in human subjects. Skeletal muscle of type 2 diabetic patients has a reduced capacity to increase ATP production with high insulin levels. PMID:12808136

  6. Effect of insulin on human skeletal muscle mitochondrial ATP production, protein synthesis, and mRNA transcripts

    NASA Astrophysics Data System (ADS)

    Stump, Craig S.; Short, Kevin R.; Bigelow, Maureen L.; Schimke, Jill M.; Sreekumaran Nair, K.

    2003-06-01

    Mitochondria are the primary site of skeletal muscle fuel metabolism and ATP production. Although insulin is a major regulator of fuel metabolism, its effect on mitochondrial ATP production is not known. Here we report increases in vastus lateralis muscle mitochondrial ATP production capacity (32-42%) in healthy humans (P < 0.01) i.v. infused with insulin (1.5 milliunits/kg of fat-free mass per min) while clamping glucose, amino acids, glucagon, and growth hormone. Increased ATP production occurred in association with increased mRNA levels from both mitochondrial (NADH dehydrogenase subunit IV) and nuclear [cytochrome c oxidase (COX) subunit IV] genes (164-180%) encoding mitochondrial proteins (P < 0.05). In addition, muscle mitochondrial protein synthesis, and COX and citrate synthase enzyme activities were increased by insulin (P < 0.05). Further studies demonstrated no effect of low to high insulin levels on muscle mitochondrial ATP production for people with type 2 diabetes mellitus, whereas matched nondiabetic controls increased 16-26% (P < 0.02) when four different substrate combinations were used. In conclusion, insulin stimulates mitochondrial oxidative phosphorylation in skeletal muscle along with synthesis of gene transcripts and mitochondrial protein in human subjects. Skeletal muscle of type 2 diabetic patients has a reduced capacity to increase ATP production with high insulin levels. cytochrome c oxidase | NADH dehydrogenase subunit IV | amino acids | citrate synthase

  7. Characterization of Insulin-Immunoreactive Cells and Endocrine Cells Within the Duct System of the Adult Human Pancreas.

    PubMed

    Li, Rong; Zhang, Xiaoxi; Yu, Lan; Zou, Xia; Zhao, Hailu

    2016-01-01

    The adult pancreatic duct system accommodates endocrine cells that have the potential to produce insulin. Here we report the characterization and distribution of insulin-immunoreactive cells and endocrine cells within the ductal units of adult human pancreas. Sequential pancreas sections from 12 nondiabetic adults were stained with biomarkers of ductal epithelial cells (cytokeratin 19), acinar cells (amylase), endocrine cells (chromogranin A; neuron-specific enolase), islet hormones (insulin, glucagon, somatostatin, pancreatic polypeptide), cell proliferation (Ki-67), and neogenesis (CD29). The number of islet hormone-immunoreactive cells increased from large ducts to the terminal branches. The insulin-producing cells outnumbered endocrine cells reactive for glucagon, somatostatin, or pancreatic polypeptide. The proportions of insulin-immunoreactive count compared with local islets (100% as a baseline) were 1.5% for the main ducts, 7.2% for interlobular ducts, 24.8% for intralobular ducts, 67.9% for intercalated ducts, and 348.9% for centroacinar cells. Both Ki-67- and CD29-labeled cells were predominantly localized in the terminal branches around the islets. The terminal branches also showed cells coexpressing islet hormones and cytokeratin 19. The adult human pancreatic ducts showed islet hormone-producing cells. The insulin-reactive cells predominantly localized in terminal branches where they may retain potential capability for β-cell neogenesis.

  8. Leptin rapidly suppresses insulin release from insulinoma cells, rat and human islets and, in vivo, in mice.

    PubMed Central

    Kulkarni, R N; Wang, Z L; Wang, R M; Hurley, J D; Smith, D M; Ghatei, M A; Withers, D J; Gardiner, J V; Bailey, C J; Bloom, S R

    1997-01-01

    Obesity is associated with diabetes, and leptin is known to be elevated in obesity. To investigate whether leptin has a direct effect on insulin secretion, isolated rat and human islets and cultured insulinoma cells were studied. In all cases, mouse leptin inhibited insulin secretion at concentrations within the plasma range reported in humans. Insulin mRNA expression was also suppressed in the cultured cells and rat islets. The long form of the leptin receptor (OB-Rb) mRNA was present in the islets and insulinoma cell lines. To determine the significance of these findings in vivo, normal fed mice were injected with two doses of leptin. A significant decrease in plasma insulin and associated rise in glucose concentration were observed. Fasted normal and leptin receptor-deficient db/db mice showed no response to leptin. A dose of leptin, which mimicked that found in normal mice, was administered to leptin-deficient, hyperinsulinemic ob/ob mice. This caused a marked lowering of plasma insulin concentration and a doubling of plasma glucose. Thus, leptin has a powerful acute inhibitory effect on insulin secretion. These results suggest that the action of leptin may be one mechanism by which excess adipose tissue could acutely impair carbohydrate metabolism. PMID:9389736

  9. Turbulent flame propagation in partially premixed flames

    NASA Technical Reports Server (NTRS)

    Poinsot, T.; Veynante, D.; Trouve, A.; Ruetsch, G.

    1996-01-01

    Turbulent premixed flame propagation is essential in many practical devices. In the past, fundamental and modeling studies of propagating flames have generally focused on turbulent flame propagation in mixtures of homogeneous composition, i.e. a mixture where the fuel-oxidizer mass ratio, or equivalence ratio, is uniform. This situation corresponds to the ideal case of perfect premixing between fuel and oxidizer. In practical situations, however, deviations from this ideal case occur frequently. In stratified reciprocating engines, fuel injection and large-scale flow motions are fine-tuned to create a mean gradient of equivalence ratio in the combustion chamber which provides additional control on combustion performance. In aircraft engines, combustion occurs with fuel and secondary air injected at various locations resulting in a nonuniform equivalence ratio. In both examples, mean values of the equivalence ratio can exhibit strong spatial and temporal variations. These variations in mixture composition are particularly significant in engines that use direct fuel injection into the combustion chamber. In this case, the liquid fuel does not always completely vaporize and mix before combustion occurs, resulting in persistent rich and lean pockets into which the turbulent flame propagates. From a practical point of view, there are several basic and important issues regarding partially premixed combustion that need to be resolved. Two such issues are how reactant composition inhomogeneities affect the laminar and turbulent flame speeds, and how the burnt gas temperature varies as a function of these inhomogeneities. Knowledge of the flame speed is critical in optimizing combustion performance, and the minimization of pollutant emissions relies heavily on the temperature in the burnt gases. Another application of partially premixed combustion is found in the field of active control of turbulent combustion. One possible technique of active control consists of pulsating

  10. Temperature-Acclimated Brown Adipose Tissue Modulates Insulin Sensitivity in Humans

    PubMed Central

    Lee, Paul; Smith, Sheila; Linderman, Joyce; Courville, Amber B.; Brychta, Robert J.; Dieckmann, William; Werner, Charlotte D.; Chen, Kong Y.

    2014-01-01

    In rodents, brown adipose tissue (BAT) regulates cold- and diet-induced thermogenesis (CIT; DIT). Whether BAT recruitment is reversible and how it impacts on energy metabolism have not been investigated in humans. We examined the effects of temperature acclimation on BAT, energy balance, and substrate metabolism in a prospective crossover study of 4-month duration, consisting of four consecutive blocks of 1-month overnight temperature acclimation (24°C [month 1] → 19°C [month 2] → 24°C [month 3] → 27°C [month 4]) of five healthy men in a temperature-controlled research facility. Sequential monthly acclimation modulated BAT reversibly, boosting and suppressing its abundance and activity in mild cold and warm conditions (P < 0.05), respectively, independent of seasonal fluctuations (P < 0.01). BAT acclimation did not alter CIT but was accompanied by DIT (P < 0.05) and postprandial insulin sensitivity enhancement (P < 0.05), evident only after cold acclimation. Circulating and adipose tissue, but not skeletal muscle, expression levels of leptin and adiponectin displayed reciprocal changes concordant with cold-acclimated insulin sensitization. These results suggest regulatory links between BAT thermal plasticity and glucose metabolism in humans, opening avenues to harnessing BAT for metabolic benefits. PMID:24954193

  11. Human leukocyte antigen class II susceptibility conferring alleles among non-insulin dependent diabetes mellitus patients.

    PubMed

    Tipu, Hamid Nawaz; Ahmed, Tahir Aziz; Bashir, Mohammad Mukarram

    2011-01-01

    To determine the frequency of Human Leukocyte Antigen (HLA) class II susceptibility conferring alleles among type 2 Diabetes mellitus patients, in comparison with healthy controls. Cross-sectional comparative study. Department of Immunology, Armed Forces Institute of Pathology, Rawalpindi, from January 2009 to April 2010. Patients with non-insulin dependent Diabetes mellitus meeting World Health Organization criteria were studied. These were compared with age and gender matched healthy control subjects. For each subject (patients as well as controls), DNA was extracted from ethylene diamine tetra-acetate sample and HLA class II DRB1 typing was carried out at allele group level (DRB1*01-DRB1*16) by sequence specific primers. Human leukocyte antigen DRB1 type was determined by agarose gel electrophoresis and results were recorded. Frequencies were determined as number of an allele divided by total number of alleles per group; p-value was computed using Pearson's chi-square test. Among the 100 patients, there were 63 males and 37 females with 68 controls. A total of 13 different HLA DRB1 alleles were detected, with DRB1*15 being the commonest in both the groups. The allele DRB1*13 had statistically significant higher frequency in patient group as compared to controls (p = 0.005). HLA DRB1*13 was found with a significantly increased frequency in non-insulin dependent Diabetes mellitus.

  12. Differentiation of human labia minora dermis-derived fibroblasts into insulin-producing cells

    PubMed Central

    Kim, Bona; Yoon, Byung Sun; Moon, Jai-Hee; Kim, Jonggun; Jun, Eun Kyoung; Lee, Jung Han; Kim, Jun Sung; Baik, Cheong Soon; Kim, Aeree; Whang, Kwang Youn

    2012-01-01

    Recent evidence has suggested that human skin fibroblasts may represent a novel source of therapeutic stem cells. In this study, we report a 3-stage method to induce the differentiation of skin fibroblasts into insulin-producing cells (IPCs). In stage 1, we establish the isolation, expansion and characterization of mesenchymal stem cells from human labia minora dermis-derived fibroblasts (hLMDFs) (stage 1: MSC expansion). hLMDFs express the typical mesenchymal stem cell marker proteins and can differentiate into adipocytes, osteoblasts, chondrocytes or muscle cells. In stage 2, DMEM/F12 serum-free medium with ITS mix (insulin, transferrin, and selenite) is used to induce differentiation of hLMDFs into endoderm-like cells, as determined by the expression of the endoderm markers Sox17, Foxa2, and PDX1 (stage 2: mesenchymal-endoderm transition). In stage 3, cells in the mesenchymal-endoderm transition stage are treated with nicotinamide in order to further differentiate into self-assembled, 3-dimensional islet cell-like clusters that express multiple genes related to pancreatic β-cell development and function (stage 3: IPC). We also found that the transplantation of IPCs can normalize blood glucose levels and rescue glucose homeostasis in streptozotocin-induced diabetic mice. These results indicate that hLMDFs have the capacity to differentiate into functionally competent IPCs and represent a potential cell-based treatment for diabetes mellitus. PMID:22020533

  13. Characterization of lipid metabolism in insulin-sensitive adipocytes differentiated from immortalized human mesenchymal stem cells

    SciTech Connect

    Prawitt, Janne; Niemeier, Andreas; Kassem, Moustapha; Beisiegel, Ulrike; Heeren, Joerg

    2008-02-15

    There is a great demand for cell models to study human adipocyte function. Here we describe the adipogenic differentiation of a telomerase-immortalized human mesenchymal stem cell line (hMSC-Tert) that maintains numerous features of terminally differentiated adipocytes even after prolonged withdrawal of the peroxisome proliferator activated receptor {gamma} (PPAR{gamma}) agonist rosiglitazone. Differentiated hMSC-Tert developed the characteristic monolocular phenotype of mature adipocytes. The expression of adipocyte specific markers was highly increased during differentiation. Most importantly, the presence of the PPAR{gamma} agonist rosiglitazone was not required for the stable expression of lipoprotein lipase, adipocyte fatty acid binding protein and perilipin on mRNA and protein levels. Adiponectin expression was post-transcriptionally down-regulated in the absence of rosiglitazone. Insulin sensitivity as measured by insulin-induced phosphorylation of Akt and S6 ribosomal protein was also independent of rosiglitazone. In addition to commonly used adipogenic markers, we investigated further PPAR{gamma}-stimulated proteins with a role in lipid metabolism. We observed an increase of lipoprotein receptor (VLDLR, LRP1) and apolipoprotein E expression during differentiation. Despite this increased expression, the receptor-mediated endocytosis of lipoproteins was decreased in differentiated adipocytes, suggesting that these proteins may have an additional function in adipose tissue beyond lipoprotein uptake.

  14. Characterization of lipid metabolism in insulin-sensitive adipocytes differentiated from immortalized human mesenchymal stem cells.

    PubMed

    Prawitt, Janne; Niemeier, Andreas; Kassem, Moustapha; Beisiegel, Ulrike; Heeren, Joerg

    2008-02-15

    There is a great demand for cell models to study human adipocyte function. Here we describe the adipogenic differentiation of a telomerase-immortalized human mesenchymal stem cell line (hMSC-Tert) that maintains numerous features of terminally differentiated adipocytes even after prolonged withdrawal of the peroxisome proliferator activated receptor gamma (PPARgamma) agonist rosiglitazone. Differentiated hMSC-Tert developed the characteristic monolocular phenotype of mature adipocytes. The expression of adipocyte specific markers was highly increased during differentiation. Most importantly, the presence of the PPARgamma agonist rosiglitazone was not required for the stable expression of lipoprotein lipase, adipocyte fatty acid binding protein and perilipin on mRNA and protein levels. Adiponectin expression was post-transcriptionally down-regulated in the absence of rosiglitazone. Insulin sensitivity as measured by insulin-induced phosphorylation of Akt and S6 ribosomal protein was also independent of rosiglitazone. In addition to commonly used adipogenic markers, we investigated further PPARgamma-stimulated proteins with a role in lipid metabolism. We observed an increase of lipoprotein receptor (VLDLR, LRP1) and apolipoprotein E expression during differentiation. Despite this increased expression, the receptor-mediated endocytosis of lipoproteins was decreased in differentiated adipocytes, suggesting that these proteins may have an additional function in adipose tissue beyond lipoprotein uptake.

  15. Differentiation of human labia minora dermis-derived fibroblasts into insulin-producing cells.

    PubMed

    Kim, Bona; Yoon, Byung Sun; Moon, Jai Hee; Kim, Jonggun; Jun, Eun Kyoung; Lee, Jung Han; Kim, Jun Sung; Baik, Cheong Soon; Kim, Aeree; Whang, Kwang Youn; You, Seungkwon

    2012-01-31

    Recent evidence has suggested that human skin fibroblasts may represent a novel source of therapeutic stem cells. In this study, we report a 3-stage method to induce the differentiation of skin fibroblasts into insulin- producing cells (IPCs). In stage 1, we establish the isolation, expansion and characterization of mesenchymal stem cells from human labia minora dermis- derived fibroblasts (hLMDFs) (stage 1: MSC expansion). hLMDFs express the typical mesenchymal stem cell marker proteins and can differentiate into adipocytes, osteoblasts, chondrocytes or muscle cells. In stage 2, DMEM/F12 serum-free medium with ITS mix (insulin, transferrin, and selenite) is used to induce differentiation of hLMDFs into endoderm-like cells, as determined by the expression of the endoderm markers Sox17, Foxa2, and PDX1 (stage 2: mesenchymal-endoderm transition). In stage 3, cells in the mesenchymal- endoderm transition stage are treated with nicotinamide in order to further differentiate into self-assembled, 3-dimensional islet cell-like clusters that express multiple genes related to pancreatic β-cell development and function (stage 3: IPC). We also found that the transplantation of IPCs can normalize blood glucose levels and rescue glucose homeostasis in streptozotocin- induced diabetic mice. These results indicate that hLMDFs have the capacity to differentiate into functionally competent IPCs and represent a potential cell-based treatment for diabetes mellitus.

  16. Practice tips and tools for the successful use of U-500 regular human insulin: the diabetes educator is key.

    PubMed

    Cochran, Elaine K; Valentine, Virginia; Samaan, Karen H; Corey, Ilene B; Jackson, Jeffrey A

    2014-01-01

    This review provides information to equip diabetes educators to instruct and guide patients in using U-500 human regular insulin (U-500R). The article includes an overview of U-500R pharmacology and clinical data, strategies for outpatient and inpatient use, and tools for patient education. U-500R is useful for treating patients with any type of diabetes who require high doses of insulin. U-500R alleviates the volume-related problems associated with high doses of U-100 insulin, making treatment with high doses of insulin more feasible (because of the need for fewer injections for patients) as well as more cost-efficient and potentially more effective. These tools can help diabetes educators feel more comfortable and confident as they advise and educate patients who receive high-dose U-500R as part of their overall diabetes care plan. The diabetes educator plays a vital role in helping patients use U-500R safely and successfully.

  17. Reversal of hyperglycemia in mice by using human expandable insulin-producing cells differentiated from fetal liver progenitor cells

    NASA Astrophysics Data System (ADS)

    Zalzman, Michal; Gupta, Sanjeev; Giri, Ranjit K.; Berkovich, Irina; Sappal, Baljit S.; Karnieli, Ohad; Zern, Mark A.; Fleischer, Norman; Efrat, Shimon

    2003-06-01

    Beta-cell replacement is considered to be the most promising approach for treatment of type 1 diabetes. Its application on a large scale is hindered by a shortage of cells for transplantation. Activation of insulin expression, storage, and regulated secretion in stem/progenitor cells offers novel ways to overcome this shortage. We explored whether fetal human progenitor liver cells (FH) could be induced to differentiate into insulin-producing cells after expression of the pancreatic duodenal homeobox 1 (Pdx1) gene, which is a key regulator of pancreatic development and insulin expression in beta cells. FH cells possess a considerable replication capacity, and this was further extended by introduction of the gene for the catalytic subunit of human telomerase. Immortalized FH cells expressing Pdx1 activated multiple beta-cell genes, produced and stored considerable amounts of insulin, and released insulin in a regulated manner in response to glucose. When transplanted into hyperglycemic immunodeficient mice, the cells restored and maintained euglycemia for prolonged periods. Quantitation of human C-peptide in the mouse serum confirmed that the glycemia was normalized by the transplanted human cells. This approach offers the potential of a novel source of cells for transplantation into patients with type 1 diabetes.

  18. Eptifibatide and abciximab inhibit insulin-induced focal adhesion formation and proliferative responses in human aortic smooth muscle cells

    PubMed Central

    Pathak, Alokkumar; Zhao, Renyi; Huang, Jianhua; Stouffer, George A

    2008-01-01

    Background The use of abciximab (c7E3 Fab) or eptifibatide improves clinical outcomes in diabetics undergoing percutaneous coronary intervention. These β3 integrin inhibitors antagonize fibrinogen binding to αIIbβ3 integrins on platelets and ligand binding to αvβ3 integrins on vascular cells. αvβ3 integrins influence responses to insulin in various cell types but effects in human aortic smooth muscle cells (HASMC) are unknown. Results and discussion Insulin elicited a dose-dependent proliferative response in HASMC. Pretreatment with m7E3 (an anti-β3 integrin monoclonal antibody from which abciximab is derived), c7E3 or LM609 inhibited proliferative responses to insulin by 81%, 59% and 28%, respectively. Eptifibatide or cyclic RGD peptides completely abolished insulin-induced proliferation whereas tirofiban, which binds αIIbβ3 but not αvβ3, had no effect. Insulin-induced increases in c-Jun NH2-terminal kinase-1 (JNK1) activity were partially inhibited by m7E3 and eptifibatide whereas antagonism of αvβ3 integrins had no effect on insulin-induced increases in extracellular signal-regulated kinase (ERK) activity. Insulin stimulated a rapid increase in the number of vinculin-containing focal adhesions per cell and treatment with m7E3, c7E3 or eptifibatide inhibited insulin-induced increases in focal adhesions by 100%, 74% and 73%, respectively. Conclusion These results demonstrate that αvβ3 antagonists inhibit signaling, focal adhesion formation and proliferation of insulin-treated HASMC. PMID:19108709

  19. Preparation of a microcrystalline suspension formulation of Lys(B28)Pro(B29)-human insulin with ultralente properties.

    PubMed

    Richards, J P; Stickelmeyer, M P; Frank, B H; Pye, S; Barbeau, M; Radziuk, J; Smith, G D; DeFelippis, M R

    1999-09-01

    The monomeric analogue, Lys(B28)Pro(B29)-human insulin (LysPro), has been crystallized using similar conditions employed to prepare extended-acting insulin ultralente formulations. In the presence of zinc ions, sodium acetate and sodium chloride, but without phenolic preservative, LysPro surprisingly forms small rhombohedral crystals with similar morphology to human insulin ultralente crystals with a mean particle size of 20 +/- 1 microm. X-ray powder diffraction studies on the LysPro crystals prior to dilution in ultralente vehicle ([NaCl] = 1.2 M) revealed the presence of T(3)R(3)(f) hexamers. Consistent with human insulin ultralente preparations, LysPro crystals formulated as an ultralente suspension ([NaCl] = 0. 12 M) contain T(6) hexamers indicating that a conformational change occurs in the hexamer units of the crystals upon dilution of the salt concentration. The pharmacological properties of subcutaneously administered ultralente LysPro (ULP) were compared to ultralente human insulin (UHI) using a conscious dog model (n = 5) with glucose levels clamped at basal. There were no statistically significant differences between the kinetic and dynamic responses of ULP compared to UHI [C(max) (ng/mL): 3.58 +/- 0.76, ULP and 3.61 +/- 0. 66, UHI; T(max) (min): 226 +/- 30, ULP and 185 +/- 42, UHI; R(max) (mg/kg min): 11.2 +/- 1.9, ULP and 13.3 +/- 2.0, UHI; and T(Rmax) (min): 336 +/- 11, ULP and 285 +/- 57, UHI]. Although the Pro to Lys sequence inversion destabilizes insulin self-assembly and greatly alters the time action of soluble LysPro preparations, this modification has now been found neither to prevent the formation of ultralente crystals in the absence of phenolics nor to compromise the protracted activity of the insulin analogue suspension.

  20. Gravity Effects Observed In Partially Premixed Flames

    NASA Technical Reports Server (NTRS)

    Puri, Ishwar K.; Aggarwal, Suresh K.; Lock, Andrew J.; Gauguly, Ranjan; Hegde, Uday

    2003-01-01

    Partially premixed flames (PPFs) contain a rich premixed fuel air mixture in a pocket or stream, and, for complete combustion to occur, they require the transport of oxidizer from an appropriately oxidizer-rich (or fuel-lean) mixture that is present in another pocket or stream. Partial oxidation reactions occur in fuel-rich portions of the mixture and any remaining unburned fuel and/or intermediate species are consumed in the oxidizer-rich portions. Partial premixing, therefore, represents that condition when the equivalence ratio (phi) in one portion of the flowfield is greater than unity, and in another section its value is less than unity. In general, for combustion to occur efficiently, the global equivalence ratio is in the range fuel-lean to stoichiometric. These flames can be established by design by placing a fuel-rich mixture in contact with a fuel-lean mixture, but they also occur otherwise in many practical systems, which include nonpremixed lifted flames, turbulent nonpremixed combustion, spray flames, and unwanted fires. Other practical applications of PPFs are reported elsewhere. Although extensive experimental studies have been conducted on premixed and nonpremixed flames under microgravity, there is a absence of previous experimental work on burner stabilized PPFs in this regard. Previous numerical studies by our group employing a detailed numerical model showed gravity effects to be significant on the PPF structure. We report on the results of microgravity experiments conducted on two-dimensional (established on a Wolfhard-Parker slot burner) and axisymmetric flames (on a coannular burner) that were investigated in a self-contained multipurpose rig. Thermocouple and radiometer data were also used to characterize the thermal transport in the flame.

  1. Displacement speeds in turbulent premixed flame simulations

    SciTech Connect

    Day, Marcus S.; Shepherd, Ian G.; Bell, J.; Grcar, Joseph F.; Lijewski, Michael J.

    2007-07-01

    The theory of turbulent premixed flames is based on acharacterization of the flame as a discontinuous surface propagatingthrough the fluid. The displacement speed, defined as the local speed ofthe flame front normal to itself, relative to the unburned fluid,provides one characterization of the burning velocity. In this paper, weintroduce a geometric approach to computing displacement speed anddiscuss the efficacy of the displacement speed for characterizing aturbulent flame.

  2. Whole and fractionated yellow pea flours reduce fasting insulin and insulin resistance in hypercholesterolaemic and overweight human subjects.

    PubMed

    Marinangeli, Christopher P F; Jones, Peter J H

    2011-01-01

    The objective of the present study was to compare whole pea flour (WPF) to fractionated pea flour (FPF; hulls only) for their ability to reduce risk factors associated with CVD and diabetes in overweight hypercholesterolaemic individuals. Using a cross-over design, twenty-three hypercholesterolaemic overweight men and women received two-treatment muffins/d containing WPF, FPF or white wheat flour (WF) for 28 d, followed by 28 d washout periods. Daily doses of WPF and FPF complied with the United States Department of Agriculture's recommended level of intake of half a cup of pulses/d (approximately 50 g/d). Dietary energy requirements were calculated for each study subject, and volunteers were only permitted to eat food supplied by the study personnel. Fasting insulin, body composition, urinary enterolactone levels, postprandial glucose response, as well as fasting lipid and glucose concentrations, were assessed at the beginning and at the end of each treatment. Insulin concentrations for WPF (37·8 (SEM 3·4) pmol/ml, P = 0·021) and FPF (40·5 (SEM 3·4) pmol/ml, P = 0·037) were lower compared with WF (50·7 (SEM 3·4) pmol/ml). Insulin homeostasis modelling assessment showed that consumption of WPF and FPF decreased (P < 0·05) estimates of insulin resistance (IR) compared with WF. Android:gynoid fat ratios in women participants were lower (P = 0·027) in the WPF (1·01 (sem 0·01) group compared with the WF group (1·06 (SEM 0·01). Urinary enterolactone levels tended to be higher (P = 0·087) in WPF compared with WF. Neither treatment altered circulating fasting lipids or glucose concentrations. In conclusion, under a controlled diet paradigm, a daily consumption of whole and fractionated yellow pea flours at doses equivalent to half a cup of yellow peas/d reduced IR, while WPF reduced android adiposity in women.

  3. From the Cover: Cell-replacement therapy for diabetes: Generating functional insulin-producing tissue from adult human liver cells

    NASA Astrophysics Data System (ADS)

    Sapir, Tamar; Shternhall, Keren; Meivar-Levy, Irit; Blumenfeld, Tamar; Cohen, Hamutal; Skutelsky, Ehud; Eventov-Friedman, Smadar; Barshack, Iris; Goldberg, Iris; Pri-Chen, Sarah; Ben-Dor, Lya; Polak-Charcon, Sylvie; Karasik, Avraham; Shimon, Ilan; Mor, Eytan; Ferber, Sarah

    2005-05-01

    Shortage in tissue availability from cadaver donors and the need for life-long immunosuppression severely restrict the large-scale application of cell-replacement therapy for diabetic patients. This study suggests the potential use of adult human liver as alternate tissue for autologous beta-cell-replacement therapy. By using pancreatic and duodenal homeobox gene 1 (PDX-1) and soluble factors, we induced a comprehensive developmental shift of adult human liver cells into functional insulin-producing cells. PDX-1-treated human liver cells express insulin, store it in defined granules, and secrete the hormone in a glucose-regulated manner. When transplanted under the renal capsule of diabetic, immunodeficient mice, the cells ameliorated hyperglycemia for prolonged periods of time. Inducing developmental redirection of adult liver offers the potential of a cell-replacement therapy for diabetics by allowing the patient to be the donor of his own insulin-producing tissue. pancreas | transdifferentiation

  4. Insulin/glucose induces natriuretic peptide clearance receptor in human adipocytes: a metabolic link with the cardiac natriuretic pathway.

    PubMed

    Bordicchia, M; Ceresiani, M; Pavani, M; Minardi, D; Polito, M; Wabitsch, M; Cannone, V; Burnett, J C; Dessì-Fulgheri, P; Sarzani, R

    2016-07-01

    Cardiac natriuretic peptides (NP) are involved in cardiorenal regulation and in lipolysis. The NP activity is largely dependent on the ratio between the signaling receptor NPRA and the clearance receptor NPRC. Lipolysis increases when NPRC is reduced by starving or very-low-calorie diet. On the contrary, insulin is an antilipolytic hormone that increases sodium retention, suggesting a possible functional link with NP. We examined the insulin-mediated regulation of NP receptors in differentiated human adipocytes and tested the association of NP receptor expression in visceral adipose tissue (VAT) with metabolic profiles of patients undergoing renal surgery. Differentiated human adipocytes from VAT and Simpson-Golabi-Behmel Syndrome (SGBS) adipocyte cell line were treated with insulin in the presence of high-glucose or low-glucose media to study NP receptors and insulin/glucose-regulated pathways. Fasting blood samples and VAT samples were taken from patients on the day of renal surgery. We observed a potent insulin-mediated and glucose-dependent upregulation of NPRC, through the phosphatidylinositol 3-kinase pathway, associated with lower lipolysis in differentiated adipocytes. No effect was observed on NPRA. Low-glucose medium, used to simulate in vivo starving conditions, hampered the insulin effect on NPRC through modulation of insulin/glucose-regulated pathways, allowing atrial natriuretic peptide to induce lipolysis and thermogenic genes. An expression ratio in favor of NPRC in adipose tissue was associated with higher fasting insulinemia, HOMA-IR, and atherogenic lipid levels. Insulin/glucose-dependent NPRC induction in adipocytes might be a key factor linking hyperinsulinemia, metabolic syndrome, and higher blood pressure by reducing NP effects on adipocytes. Copyright © 2016 the American Physiological Society.

  5. Premixed Turbulent Flame Propagation in Microgravity

    NASA Technical Reports Server (NTRS)

    Menon, Suresh

    1999-01-01

    A combined numerical-experimental study has been carried out to investigate the structure and propagation characteristics of turbulent premixed flames with and without the influence of buoyancy. Experimentally, the premixed flame characteristics are studied in the wrinkled regime using a Couette flow facility and an isotropic flow facility in order to resolve the scale of flame wrinkling. Both facilities were chosen for their ability to achieve sustained turbulence at low Reynolds number. This implies that conventional diagnostics can be employed to resolve the smallest scales of wrinkling. The Couette facility was also built keeping in mind the constraints imposed by the drop tower requirements. Results showed that the flow in this Couette flow facility achieves full-developed turbulence at low Re and all turbulence statistics are in good agreement with past measurements on large-scale facilities. Premixed flame propagation studies were then carried out both using the isotropic box and the Couette facility. Flame imaging showed that fine scales of wrinkling occurs during flame propagation. Both cases in Ig showed significant buoyancy effect. To demonstrate that micro-g can remove this buoyancy effect, a small drop tower was built and drop experiments were conducted using the isotropic box. Results using the Couette facility confirmed the ability to carry out these unique reacting flow experiments at least in 1g. Drop experiments at NASA GRC were planned but were not completed due to termination of this project.

  6. Simulation of lean premixed turbulent combustion

    SciTech Connect

    Bell, John B.; Day, Marcus S.; Almgren, Ann S.; Lijewski, MichaelJ.; Rendleman, Charles A.; Cheng, Robert K.; Shepherd, Ian G.

    2006-06-25

    There is considerable technological interest in developingnew fuel-flexible combustion systems that can burn fuels such ashydrogenor syngas. Lean premixed systems have the potential to burn thesetypes of fuels with high efficiency and low NOx emissions due to reducedburnt gas temperatures. Although traditional scientific approaches basedon theory and laboratory experiment have played essential roles indeveloping our current understanding of premixed combustion, they areunable to meet the challenges of designing fuel-flexible lean premixedcombustion devices. Computation, with itsability to deal with complexityand its unlimited access to data, hasthe potential for addressing thesechallenges. Realizing this potential requires the ability to perform highfidelity simulations of turbulent lean premixed flames under realisticconditions. In this paper, we examine the specialized mathematicalstructure of these combustion problems and discuss simulation approachesthat exploit this structure. Using these ideas we can dramatically reducecomputational cost, making it possible to perform high-fidelitysimulations of realistic flames. We illustrate this methodology byconsidering ultra-lean hydrogen flames and discuss how this type ofsimulation is changing the way researchers study combustion.

  7. Numerical simulation of premixed turbulent methane combustion

    SciTech Connect

    Day, Marc S.; Bell, John B.; Almgren, Ann S.; Beckner, Vincent E.; Lijewski, Michael J.; Cheng, Robert; Shepherd, Ian; Johnson, Matthew

    2003-06-14

    With adaptive-grid computational methodologies and judicious use of compressible and low Mach number combustion models, we are carrying out three-dimensional, time-dependent direct numerical simulations of a laboratory-scale turbulent premixed methane burner. In the laboratory experiment, turbulence is generated by a grid located in the throat of a 50mm diameter circular nozzle; swirl is be introduced by four tangential air jets spaced uniformly around the circumference of the nozzle just above the turbulence grid. A premixed methane flame is stabilized above the nozzle in the central core region where a velocity deficit is induced7the swirling flow. The time-dependent flow field inside the nozzle, from the turbulence grid and the high-speed jets, to the nozzle exit plane is simulated using an adaptive-grid embedded-boundary compressible Navier-Stokes solver. The compressible calculation then provides time-dependent boundary conditions for an adaptive low Mach number model of the swirl-stabilized premixed flame. The low Mach model incorporates detailed chemical kinetics and species transport using 20 species and 84 reactions. Laboratory diagnostics available for comparisons include characterizations of the flow field just down stream of the nozzle exit plane, and flame surface statistics, such as mean location, wrinkling and crossing frequencies.

  8. Premixed calcium silicate cement for endodontic applications

    PubMed Central

    Persson, Cecilia; Engqvist, Håkan

    2011-01-01

    Calcium silicate-based materials (also called MTA) are increasingly being used in endodontic applications. However, the handling properties of MTA are not optimal when it comes to injectability and cohesion. Premixing the cements using glycerol avoids these issues. However, there is a lack of data on the effect of common cement variables on important properties of premixed cements for endodontic applications. In this study, the effects of liquid-to-powder ratio, amount of radiopacifier and amount of calcium sulfate (added to control the setting time) were screened using a statistical model. In the second part of the study, the liquid-to-powder ratio was optimized for cements containing three different amounts of radiopacifier. Finally, the effect of using glycerol rather than water was evaluated in terms of radiopacity. The setting time was found to increase with the amount of radiopacifier when the liquid-to-powder ratio was fixed. This was likely due to the higher density of the radiopacifier in comparison to the calcium silicate, which gave a higher liquid-to-powder ratio in terms of volume. Using glycerol rather than water to mix the cements led to a decrease in radiopacity of the cement. In conclusion, we were able to produce premixed calcium silicate cements with acceptable properties for use in endodontic applications. PMID:23507729

  9. Enhanced glycemic responsiveness to epinephrine in insulin-dependent diabetes mellitus is the result of the inability to secrete insulin. Augmented insulin secretion normally limits the glycemic, but not the lipolytic or ketogenic, response to epinephrine in humans.

    PubMed Central

    Berk, M A; Clutter, W E; Skor, D; Shah, S D; Gingerich, R P; Parvin, C A; Cryer, P E

    1985-01-01

    their increased glucagon secretory response; rather, it is the result of their inability to augment insulin secretion. Augmented insulin secretion, albeit restrained, normally limits the glycemic response, but not the lipolytic or ketogenic responses, to epinephrine in humans. Images PMID:3891786

  10. Enhanced glycemic responsiveness to epinephrine in insulin-dependent diabetes mellitus is the result of the inability to secrete insulin. Augmented insulin secretion normally limits the glycemic, but not the lipolytic or ketogenic, response to epinephrine in humans.

    PubMed

    Berk, M A; Clutter, W E; Skor, D; Shah, S D; Gingerich, R P; Parvin, C A; Cryer, P E

    1985-06-01

    their increased glucagon secretory response; rather, it is the result of their inability to augment insulin secretion. Augmented insulin secretion, albeit restrained, normally limits the glycemic response, but not the lipolytic or ketogenic responses, to epinephrine in humans.

  11. Efficacy and safety of biphasic insulin aspart and biphasic insulin lispro mix in patients with type 2 diabetes: A review of the literature

    PubMed Central

    Kumar, Ajay

    2016-01-01

    Type 2 diabetes (T2D) represents an escalating burden worldwide, particularly in China and India. Compared with Caucasians, Asian people with diabetes have lower body mass index, increased visceral adiposity, and postprandial glucose (PPG)/insulin resistance. Since postprandial hyperglycemia contributes significantly to total glycemic burden and is associated with heightened cardiovascular risk, targeting PPG early in T2D is paramount. Premixed insulin regimens are widely used in Asia due to their convenience and effectiveness. Data from randomized controlled trials and observational studies comparing efficacy and safety of biphasic insulin aspart 30 (BIAsp 30) with biphasic insulin lispro mix (LM 25/50) and versus other insulin therapies or oral antidiabetic drugs (OADs) in T2D demonstrated that BIAsp 30 and LM 25/50 were associated with similar or greater improvements in glycemic control versus comparator regimens, such as basal–bolus insulin, in insulin-naÏve, and prior insulin users. Studies directly comparing BIAsp 30 and LM 25 provided conflicting glycemic control results. Safety data generally showed increased hypoglycemia and weight gain with premixed insulins versus basal–bolus insulin or OADs. However, large observational trials documented improvements in glycated hemoglobin, PPG, and hypoglycemia with BIAsp 30 in multi-ethnic patient populations. In summary, this literature review demonstrates that premixed insulin regimens are an appropriate and effective treatment choice in T2D. PMID:27186543

  12. Evidence for defects in the trafficking and translocation of GLUT4 glucose transporters in skeletal muscle as a cause of human insulin resistance.

    PubMed Central

    Garvey, W T; Maianu, L; Zhu, J H; Brechtel-Hook, G; Wallace, P; Baron, A D

    1998-01-01

    insulin in insulin-resistant subgroups. In conclusion, insulin alters the subcellular localization of GLUT4 vesicles in human muscle, and this effect is impaired equally in insulin-resistant subjects with and without diabetes. This translocation defect is associated with abnormal accumulation of GLUT4 in a dense membrane compartment demonstrable in basal muscle. We have previously observed a similar pattern of defects causing insulin resistance in human adipocytes. Based on these data, we propose that human insulin resistance involves a defect in GLUT4 traffic and targeting leading to accumulation in a dense membrane compartment from which insulin is unable to recruit GLUT4 to the cell surface. PMID:9616209

  13. Activated α2-Macroglobulin Binding to Human Prostate Cancer Cells Triggers Insulin-like Responses

    PubMed Central

    Misra, Uma Kant; Pizzo, Salvatore Vincent

    2015-01-01

    Ligation of cell surface GRP78 by activated α2-macroglobulin (α2M*) promotes cell proliferation and suppresses apoptosis. α2M*-treated human prostate cancer cells exhibit a 2–3-fold increase in glucose uptake and lactate secretion, an effect similar to insulin treatment. In both α2M* and insulin-treated cells, the mRNA levels of SREBP1-c, SREBP2, fatty-acid synthase, acetyl-CoA carboxylase, ATP citrate lyase, and Glut-1 were significantly increased together with their protein levels, except for SREBP2. Pretreatment of cells with α2M* antagonist antibody directed against the carboxyl-terminal domain of GRP78 blocks these α2M*-mediated effects, and silencing GRP78 expression by RNAi inhibits up-regulation of ATP citrate lyase and fatty-acid synthase. α2M* induces a 2–3-fold increase in lipogenesis as determined by 6-[14C]glucose or 1-[14C]acetate incorporation into free cholesterol, cholesterol esters, triglycerides, free fatty acids, and phosphatidylcholine, which is blocked by inhibitors of fatty-acid synthase, PI 3-kinase, mTORC, or an antibody against the carboxyl-terminal domain of GRP78. We also assessed the incorporation of [14CH3]choline into phosphatidylcholine and observed similar effects. Lipogenesis is significantly affected by pretreatment of prostate cancer cells with fatostatin A, which blocks sterol regulatory element-binding protein proteolytic cleavage and activation. This study demonstrates that α2M* functions as a growth factor, leading to proliferation of prostate cancer cells by promoting insulin-like responses. An antibody against the carboxyl-terminal domain of GRP78 may have important applications in prostate cancer therapy. PMID:25720493

  14. Pharmacodynamic Considerations with Recombinant Human Insulin-Like Growth Factor-I in Children

    PubMed Central

    Ferry, Robert J.; Cohen, Pinchas; Levitt Katz, Lorraine E.

    2011-01-01

    Aim To report effects of weight-based recombinant human insulin-like growth factor-I (rhIGF-I) on IGF axis parameters in children with hyperinsulinism. Methods Open label trial with subcutaneous rhIGF-I (40 μg/kg/dose). Patients studied were children (1 month to 11 years) with diffuse hyperinsulinism (n = 7). Serial serum IGF and insulin-like growth factor binding protein (IGFBP) concentrations were measured by RIA and analyzed by linear Pearson regression. Results Following the initial rhIGF-I dose, total insulin-like growth factor-I (IGF-I) rose by 56% at 30 min (p < 0.01) and 85% at 120 min (p < 0.02). Serum IGF-II, IGFBP-2, and IGFBP-3 levels did not change. Peak serum IGF-I levels within 12 h of the initial rhIGF-I dose were 167–700 mg/ml. The variable peak IGF-I response is attributable in part to IGFBP-3 differences across this pediatric age range. Models of rhIGF-I dosing based upon body surface area (BSA) or initial IGFBP-3 resulted in predictable peak serum IGF-I levels (r = 0.78; p < 0.03). Recalculating rhIGF-I dosing based upon the BSA · IGFBP-3 product correlated closely with peak IGF-I level (r = 0.85; p < 0.007). Conclusions Weight-based IGF-I dosing in this cohort resulted in variable IGF-I levels. Considering BSA and serum IGFBP-3 concentration in children is appropriate for subcutaneous IGF-I administration. A combination of these values may yield predictable individualization of rhIGF-I dosing. PMID:15886488

  15. Activated α2-macroglobulin binding to human prostate cancer cells triggers insulin-like responses.

    PubMed

    Misra, Uma Kant; Pizzo, Salvatore Vincent

    2015-04-10

    Ligation of cell surface GRP78 by activated α2-macroglobulin (α2M*) promotes cell proliferation and suppresses apoptosis. α2M*-treated human prostate cancer cells exhibit a 2-3-fold increase in glucose uptake and lactate secretion, an effect similar to insulin treatment. In both α2M* and insulin-treated cells, the mRNA levels of SREBP1-c, SREBP2, fatty-acid synthase, acetyl-CoA carboxylase, ATP citrate lyase, and Glut-1 were significantly increased together with their protein levels, except for SREBP2. Pretreatment of cells with α2M* antagonist antibody directed against the carboxyl-terminal domain of GRP78 blocks these α2M*-mediated effects, and silencing GRP78 expression by RNAi inhibits up-regulation of ATP citrate lyase and fatty-acid synthase. α2M* induces a 2-3-fold increase in lipogenesis as determined by 6-[(14)C]glucose or 1-[(14)C]acetate incorporation into free cholesterol, cholesterol esters, triglycerides, free fatty acids, and phosphatidylcholine, which is blocked by inhibitors of fatty-acid synthase, PI 3-kinase, mTORC, or an antibody against the carboxyl-terminal domain of GRP78. We also assessed the incorporation of [(14)CH3]choline into phosphatidylcholine and observed similar effects. Lipogenesis is significantly affected by pretreatment of prostate cancer cells with fatostatin A, which blocks sterol regulatory element-binding protein proteolytic cleavage and activation. This study demonstrates that α2M* functions as a growth factor, leading to proliferation of prostate cancer cells by promoting insulin-like responses. An antibody