Science.gov

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.

  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. 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

  6. 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.

  7. 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

  8. Intensification of insulin therapy with basal-bolus or premixed insulin regimens in type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials.

    PubMed

    Giugliano, Dario; Chiodini, Paolo; Maiorino, Maria Ida; Bellastella, Giuseppe; Esposito, Katherine

    2016-03-01

    The purpose of this study was to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing the effect of intensified insulin regimens (basal-bolus versus premixed) on glycemic control in patients with type 2 diabetes. We conducted an electronic search until March 2015 on many electronic databases including online registries of ongoing trials. All RCTs comparing basal-bolus with premixed insulin regimens, with a duration of >12 weeks and with >30 patients per arm, were included. Investigators extracted data on study characteristics, outcome measures, and methodological quality. We found thirteen RCTs lasting 16-60 weeks and involving 5255 patients assessed for the primary endpoint (reduction of HbA1c from baseline). Meta-analysis of change in HbA1c level between basal-bolus and premixed insulin regimens resulted in a small and non-significant difference of 0.09% (95% CI -0.03 to 0.21), with substantial heterogeneity between studies (I(2) = 74.4%). There was no statistically significant difference in the event rate for overall hypoglycemia (0.16 episode/patient/year, 95%CI -2.07 to 2.3), weight change (-0.21 kg, -0.164 to 0.185), and daily insulin dose (-0.54 U/day, -2.7 to 1.6). The likelihood for reaching the HbA1c <7% was 8% higher (3-13%, I(2) = 68.8%) with the basal-bolus as compared with the premixed regimen. There is no clinically relevant difference in the efficacy of basal-bolus versus premixed insulin regimens for HbA1c decrease in type 2 diabetic patients. These findings may be helpful to adapt treatment to individual patient needs.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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)

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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)

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  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. 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.

  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. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Insulin

    MedlinePlus

    ... container that can be closed like a laundry detergent bottle. Check the expiration date on the insulin ... in a hard container like an empty laundry detergent bottle or a metal coffee can. Make sure ...

  4. 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

  5. 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

  6. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. [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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  4. 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.

  5. 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.

  6. 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)

  7. Human islet preparations distributed for research exhibit a variety of insulin-secretory profiles.

    PubMed

    Kayton, Nora S; Poffenberger, Gregory; Henske, Joseph; Dai, Chunhua; Thompson, Courtney; Aramandla, Radhika; Shostak, Alena; Nicholson, Wendell; Brissova, Marcela; Bush, William S; Powers, Alvin C

    2015-04-01

    Human islet research is providing new insights into human islet biology and diabetes, using islets isolated at multiple US centers from donors with varying characteristics. This creates challenges for understanding, interpreting, and integrating research findings from the many laboratories that use these islets. In what is, to our knowledge, the first standardized assessment of human islet preparations from multiple isolation centers, we measured insulin secretion from 202 preparations isolated at 15 centers over 11 years and noted five distinct patterns of insulin secretion. Approximately three quarters were appropriately responsive to stimuli, but one quarter were dysfunctional, with unstable basal insulin secretion and/or an impairment in stimulated insulin secretion. Importantly, the patterns of insulin secretion by responsive human islet preparations (stable Baseline and Fold stimulation of insulin secretion) isolated at different centers were similar and improved slightly over the years studied. When all preparations studied were considered, basal and stimulated insulin secretion did not correlate with isolation center, biological differences of the islet donor, or differences in isolation, such as Cold Ischemia Time. Dysfunctional islet preparations could not be predicted from the information provided by the isolation center and had altered expression of genes encoding components of the glucose-sensing pathway, but not of insulin production or cell death. These results indicate that insulin secretion by most preparations from multiple centers is similar but that in vitro responsiveness of human islets cannot be predicted, necessitating preexperimental human islet assessment. These results should be considered when one is designing, interpreting, and integrating experiments using human islets.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

  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. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. [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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  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. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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)

  8. 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.

  9. 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

  10. 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.

  11. 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

  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. 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

  15. 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.

  16. 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.

  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. 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.

  19. 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

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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).

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  5. 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

  6. Personalized intensification of insulin therapy in type 2 diabetes - does a basal-bolus regimen suit all patients?

    PubMed

    Giugliano, D; Sieradzki, J; Stefanski, A; Gentilella, R

    2016-08-01

    Many patients with type 2 diabetes mellitus (T2DM) require insulin therapy. If basal insulin fails to achieve glycemic control, insulin intensification is one possible treatment intensification strategy. We summarized clinical data from randomized clinical trials designed to compare the efficacy and safety of basal-bolus and premixed insulin intensification regimens. We defined a between-group difference of ≥0.3% in end-of-study glycated hemoglobin (HbA1c) as clinically meaningful. A PubMed database search supplemented by author-identified papers yielded 15 trials which met selection criteria: randomized design, patients with T2DM receiving basal-bolus (bolus injection ≤3 times/day) vs. premixed (≤3 injections/day) insulin regimens, primary/major endpoint(s) HbA1c- and/or hypoglycemia-related, and trial duration ≥12 weeks. Glycemic control improved with both basal-bolus and premixed insulin regimens with - in most cases - acceptable levels of weight gain and hypoglycemia. A clinically meaningful difference between regimens in glycemic control was recorded in only four comparisons, all of which favored basal-bolus therapy. The incidence of hypoglycemia was significantly different between regimens in only three comparisons, one of which favored premixed insulin and two basal-bolus therapy. Of the four trials that reported a significant difference between regimens in bodyweight change, two favored basal-bolus therapy and two favored premixed insulin. Thus, on a population level, neither basal-bolus therapy nor premixed insulin showed a consistent advantage in terms of glycemic control, hypoglycemic risk, or bodyweight gain. It is therefore recommended that clinicians should adopt an individualized approach to insulin intensification - taking into account the benefits and risks of each treatment approach and the attitude and preferences of each patient - in the knowledge that both basal-bolus and premixed regimens may be successful.

  7. 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

  8. 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.

  9. Looking at the carcinogenicity of human insulin analogues via the intrinsic disorder prism.

    PubMed

    Redwan, Elrashdy M; Linjawi, Moustafa H; Uversky, Vladimir N

    2016-03-17

    Therapeutic insulin, in its native and biosynthetic forms as well as several currently available insulin analogues, continues to be the protein of most interest to researchers. From the time of its discovery to the development of modern insulin analogues, this important therapeutic protein has passed through several stages and product generations. Beside the well-known link between diabetes and cancer risk, the currently used therapeutic insulin analogues raised serious concerns due to their potential roles in cancer initiation and/or progression. It is possible that structural variations in some of the insulin analogues are responsible for the appearance of new oncogenic species with high binding affinity to the insulin-like growth factor 1 (IGF1) receptor. The question we are trying to answer in this work is: are there any specific features of the distribution of intrinsic disorder propensity within the amino acid sequences of insulin analogues that may provide an explanation for the carcinogenicity of the altered insulin protein?

  10. Reevaluation of Fatty Acid Receptor 1 as a Drug Target for the Stimulation of Insulin Secretion in Humans

    PubMed Central

    Wagner, Robert; Kaiser, Gabriele; Gerst, Felicia; Christiansen, Elisabeth; Due-Hansen, Maria E.; Grundmann, Manuel; Machicao, Fausto; Peter, Andreas; Kostenis, Evi; Ulven, Trond; Fritsche, Andreas; Häring, Hans-Ulrich; Ullrich, Susanne

    2013-01-01

    The role of free fatty acid receptor 1 (FFAR1/GPR40) in glucose homeostasis is still incompletely understood. Small receptor agonists stimulating insulin secretion are undergoing investigation for the treatment of type 2 diabetes. Surprisingly, genome-wide association studies did not discover diabetes risk variants in FFAR1. We reevaluated the role of FFAR1 in insulin secretion using a specific agonist, FFAR1-knockout mice and human islets. Nondiabetic individuals were metabolically phenotyped and genotyped. In vitro experiments indicated that palmitate and a specific FFAR1 agonist, TUG-469, stimulate glucose-induced insulin secretion through FFAR1. The proapoptotic effect of chronic exposure of β-cells to palmitate was independent of FFAR1. TUG-469 was protective, whereas inhibition of FFAR1 promoted apoptosis. In accordance with the proapoptotic effect of palmitate, in vivo cross-sectional observations demonstrated a negative association between fasting free fatty acids (NEFAs) and insulin secretion. Because NEFAs stimulate secretion through FFAR1, we examined the interaction of genetic variation in FFAR1 with NEFA and insulin secretion. The inverse association of NEFA and secretion was modulated by rs1573611 and became steeper for carriers of the minor allele. In conclusion, FFAR1 agonists support β-cell function, but variation in FFAR1 influences NEFA effects on insulin secretion and therefore could affect therapeutic efficacy of FFAR1 agonists. PMID:23378609

  11. Topographic abnormalities of proinsulin to insulin conversion in functioning human insulinomas. Comparison of immunoelectron microscopic and clinical data.

    PubMed Central

    Roth, J.; Komminoth, P.; Heitz, P. U.

    1995-01-01

    It has been proposed that the major defect in human insulinomas is a decreased hormone storage capacity resulting in uncontrolled release of proinsulin and insulin. By immunoelectron microscopy with monoclonal antibodies we studied the subcellular distribution of proinsulin and insulin in benign and malignant functioning insulinomas of different histology and compared the findings with various clinical and pathohistological parameters. We found that, in contrast to normal B cells, the proinsulin to insulin conversion in insulinomas occurs already in the trans Golgi apparatus but remains incomplete, resulting in the formation of secretory granules containing both proinsulin and insulin. Thus, in functioning insulinomas, sorting into secretory granules is not a prerequisite for hormone conversion. Furthermore, proinsulin and insulin storage and most probably subsequent secretion occurs through the secretory granules via the regulated pathway. A substantial variability for both proinsulin and insulin immunolabeling in secretory granules was found not only in individual tumor cells but also among the insulinomas studied. This observed variability may account for the lack of correlation between pathohistological, immunohistochemical, and clinical parameters in functioning insulinomas. Images Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:7639339

  12. 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.

  13. Clinical utility of insulin and insulin analogs

    PubMed Central

    Sanlioglu, Ahter D.; Altunbas, Hasan Ali; Balci, Mustafa Kemal; Griffith, Thomas S.; Sanlioglu, Salih

    2013-01-01

    Diabetes is a pandemic disease characterized by autoimmune, genetic and metabolic abnormalities. While insulin deficiency manifested as hyperglycemia is a common sequel of both Type-1 and Type-2 diabetes (T1DM and T2DM), it does not result from a single genetic defect—rather insulin deficiency results from the functional loss of pancreatic β cells due to multifactorial mechanisms. Since pancreatic β cells of patients with T1DM are destroyed by autoimmune reaction, these patients require daily insulin injections. Insulin resistance followed by β cell dysfunction and β cell loss is the characteristics of T2DM. Therefore, most patients with T2DM will require insulin treatment due to eventual loss of insulin secretion. Despite the evidence of early insulin treatment lowering macrovascular (coronary artery disease, peripheral arterial disease and stroke) and microvascular (diabetic nephropathy, neuropathy and retinopathy) complications of T2DM, controversy exists among physicians on how to initiate and intensify insulin therapy. The slow acting nature of regular human insulin makes its use ineffective in counteracting postprandial hyperglycemia. Instead, recombinant insulin analogs have been generated with a variable degree of specificity and action. Due to the metabolic variability among individuals, optimum blood glucose management is a formidable task to accomplish despite the presence of novel insulin analogs. In this article, we present a recent update on insulin analog structure and function with an overview of the evidence on the various insulin regimens clinically used to treat diabetes. PMID:23584214

  14. Application of simple fed-batch technique to high-level secretory production of insulin precursor using Pichia pastoris with subsequent purification and conversion to human insulin

    PubMed Central

    2010-01-01

    Background The prevalence of diabetes is predicted to rise significantly in the coming decades. A recent analysis projects that by the year 2030 there will be ~366 million diabetics around the world, leading to an increased demand for inexpensive insulin to make this life-saving drug also affordable for resource poor countries. Results A synthetic insulin precursor (IP)-encoding gene, codon-optimized for expression in P. pastoris, was cloned in frame with the Saccharomyces cerevisiae α-factor secretory signal and integrated into the genome of P. pastoris strain X-33. The strain was grown to high-cell density in a batch procedure using a defined medium with low salt and high glycerol concentrations. Following batch growth, production of IP was carried out at methanol concentrations of 2 g L-1, which were kept constant throughout the remaining production phase. This robust feeding strategy led to the secretion of ~3 gram IP per liter of culture broth (corresponding to almost 4 gram IP per liter of cell-free culture supernatant). Using immobilized metal ion affinity chromatography (IMAC) as a novel approach for IP purification, 95% of the secreted product was recovered with a purity of 96% from the clarified culture supernatant. Finally, the purified IP was trypsin digested, transpeptidated, deprotected and further purified leading to ~1.5 g of 99% pure recombinant human insulin per liter of culture broth. Conclusions A simple two-phase cultivation process composed of a glycerol batch and a constant methanol fed-batch phase recently developed for the intracellular production of the Hepatitis B surface antigen was adapted to secretory IP production. Compared to the highest previously reported value, this approach resulted in an ~2 fold enhancement of IP production using Pichia based expression systems, thus significantly increasing the efficiency of insulin manufacture. PMID:20462406

  15. Expression of metalloprotease insulin-degrading enzyme (insulysin) in normal and malignant human tissues

    PubMed Central

    Yfanti, Christina; Mengele, Karin; Gkazepis, Apostolos; Weirich, Gregor; Giersig, Cecylia; Kuo, Wen-Liang; Tang, Wei-Jen; Rosner, Marsha; Schmitt, Manfred

    2013-01-01

    Background Insulin-degrading enzyme (IDE, insulysin, insulinase; EC 3.4.22.11), a thiol metalloendopeptidase, is involved in intracellular degradation of insulin, thereby inhibiting its translocation and accumulation to the nucleus. Recently, protein expression of IDE has been demonstrated in the epithelial ducts of normal breast and in breast cancer tissue (Radulescu et al., Int J Oncol 30:73; 2007). Materials and Methods Utilizing four different antibodies generated against different epitopes of the IDE molecule, we performed western blot analysis and immunohistochemical staining on several normal human tissues, on a plethora of tumor cell lines of different tissue origin, and on malignant breast and ovarian tissue. Results Applying the four IDE-directed antibodies, we demonstrate IDE expression at the protein level, both by means of immunoblotting and immunocytochemistry, in all of the tumor cell lines analyzed. Besides, IDE protein expression was found in normal tissues of the kidney, liver, lung, brain, breast and skeletal muscle, as well as in breast and ovarian cancer tissues. Immunohistochemical visualization of IDE indicated cytoplasmic localization of IDE in all of the cell lines and tissues assessed. Conclusions We performed for the first time a wide-ranging survey on IDE protein expression in normal and malignant tissues and cells and thus extend knowledge about cellular and tissue distribution of IDE, an enzyme which so far has mainly been studied in connection with Alzheimer’s disease and diabetes but not in cancer. PMID:18813847

  16. The location and characterisation of the O-linked glycans of the human insulin receptor.

    PubMed

    Sparrow, Lindsay G; Gorman, Jeffrey J; Strike, Phillip M; Robinson, Christine P; McKern, Neil M; Epa, V Chandana; Ward, Colin W

    2007-02-01

    O-linked glycosylation is a post-translational and post-folding event involving exposed S/T residues at beta-turns or in regions with extended conformation. O-linked sites are difficult to predict from sequence analyses compared to N-linked sites. Here we compare the results of chemical analyses of isolated glycopeptides with the prediction using the neural network prediction method NetOGlyc3.1, a procedure that has been reported to correctly predict 76% of O-glycosylated residues in proteins. Using the heavily glycosylated human insulin receptor as the test protein six sites of mucin-type O-glycosylation were found at residues T744, T749, S757, S758, T759, and T763 compared to the three sites (T759 and T763- correctly, T756- incorrectly) predicted by the neural network method. These six sites occur in a 20 residue segment that begins nine residues downstream from the start of the insulin receptor beta-chain. This region which also includes N-linked glycosylation sites at N742 and N755, is predicted to lack secondary structure and is followed by residues 765-770, the known linear epitope for the monoclonal antibody 18-44.

  17. Sex-linked behavioural differences in mice expressing a human insulin transgene in the medial habenula.

    PubMed

    Douhet, P; Bertaina, V; Durkin, T; Calas, A; Destrade, C

    1997-12-01

    We previously reported that a human insulin transgene was specifically expressed in the medial habenula of the adult mouse brain, and that this expression was ascribed to the delta-168 transgene. The present study analyses the possible behavioural consequences of this insulin transgene expression using measures of food intake, spontaneous activity, emotional reactivity, learning and extinction performance of an operant task. The delta-168 transgenic mice did not differ from the C57BL/6 control mice as concerns food intake, behaviour in the open field, or emotional response in an elevated plus maze. On the other hand, measures of locomotor activity in a circular corridor revealed a significantly faster decline of spontaneous locomotor activity in male as compared to female delta-168 transgenic mice. Moreover, as compared to female transgenic mice, male transgenic mice exhibited a deficit in the rate of acquisition and an acceleration of the rate of extinction of a bar press response in a Skinner box. In contrast, the behaviour of female transgenic mice did not differ from either male or female C57BL/6 control mice. The results of the present study demonstrate that the behavioural modifications observed in delta-168 transgenic mice are sex-linked and suggest that these behavioural differences result from changes in the interaction (interface) between motivational and motor mechanisms mediated via the striato-habenulo-mesencephalic system.

  18. 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.

  19. A transgene coding for a human insulin analog has a mitogenic effect on murine embryonic beta cells.

    PubMed Central

    Vincent, M T; Carroll, R J; Hammer, R E; Chan, S J; Guz, Y; Steiner, D F; Teitelman, G

    1995-01-01

    We have investigated the mitogenic effect of three mutant forms of human insulin on insulin-producing beta cells of the developing pancreas. We examined transgenic embryonic and adult mice expressing (i) human [AspB10]-proinsulin/insulin ([AspB10]ProIN/IN), produced by replacement of histidine by aspartic acid at position 10 of the B chain and characterized by an increased affinity for the insulin receptor; (ii) human [LeuA3]insulin, produced by the substitution of leucine for valine in position 3 of the A chain, which exhibits decreased receptor binding affinity; and (iii) human [LeuA3, AspB10]insulin "double" mutation. During development, beta cells of AspB10 embryos were twice as abundant and had a 3 times higher rate of proliferation compared with beta cells of littermate controls. The mitogenic effect of [AspB10]ProIN/IN was specific for embryonic beta cells because the rate of proliferation of beta cells of adults and of glucagon (alpha) cells and adrenal chromaffin cells of embryos was similar in AspB10 mice and controls. In contrast to AspB10 embryos, the number of beta cells in the LeuA3 and "double" mutant lines was similar to the number in controls. These findings indicate that the [AspB10]ProIN/IN analog increased the rate of fetal beta-cell proliferation. The mechanism or mechanisms that mediate this mitogenic effect remain to be determined. Images Fig. 1 Fig. 4 PMID:7603977

  20. Effects of Inhibition of Interleukin-6 Signalling on Insulin Sensitivity and Lipoprotein (A) Levels in Human Subjects with Rheumatoid Diseases

    PubMed Central

    Schultz, Olaf; Oberhauser, Frank; Saech, Jasemine; Rubbert-Roth, Andrea; Hahn, Moritz; Krone, Wilhelm; Laudes, Matthias

    2010-01-01

    Background Interleukin-6 (IL-6) is a pro-inflammatory cytokine that has been found to be increased in type 2 diabetic subjects. However, it still remains unclear if these elevated IL-6 levels are co-incidental or if this cytokine is causally related to the development of insulin resistance and type 2 diabetes in humans. Therefore, in the present study we examined insulin sensitivity, serum adipokine levels and lipid parameters in human subjects before and after treatment with the IL-6 receptor antibody Tocilizumab. Methodology/Principal Findings 11 non-diabetic patients with rheumatoid disease were included in the study. HOMA-IR was calculated and serum levels for leptin, adiponectin, triglycerides, LDL-cholesterol, HDL-cholesterol and lipoprotein (a) (Lp (a)) were measured before as well as one and three months after Tocilizumab treatment. The HOMA index for insulin resistance decreased significantly. While leptin concentrations were not altered by inhibition of IL-6 signalling, adiponectin concentrations significantly increased. Thus the leptin to adiponectin ratio, a novel marker for insulin resistance, exhibited a significant decrease. Serum triglycerides, LDL-cholesterol and HDL-cholesterol tended to be increased whereas Lp (a) levels significantly decreased. Conclusions/Significance Inhibition of IL-6 signalling improves insulin sensitivity in humans with immunological disease suggesting that elevated IL-6 levels in type 2 diabetic subjects might be causally involved in the pathogenesis of insulin resistance. Furthermore, our data indicate that inhibition of IL-6 signalling decreases Lp (a) serum levels, which might reduce the cardiovascular risk of human subjects. PMID:21179199

  1. Characterization and regulation of the gene coding for human glutathione-insulin transhydrogenase (protein-disulfide interchange enzyme)

    SciTech Connect

    Morris, J.I.; Varandani, P.T.

    1987-05-01

    Glutathione-insulin transhydrogenase (GIT) is an ubiquitious enzyme whose action is to catalyze the rearrangement of disulfide bonds in proteins, resulting in either the activation or inactivation of protein molecules. The interaction of GIT with insulin results in the cleavage of the hormone into its constituent subunits, the A and B chains. GIT levels found in several tissue types have been shown to be modulated by circulating levels of insulin. An increased level of blood insulin is associated with increased levels of GIT and decreased levels of insulin are associated with decreased levels of GIT, indicating that insulin regulates its own degradation. A cDNA probe coding for the GIT gene was isolated from a human liver cDNA expression library constructed in lambda gt11. Sequencing of this clone indicates that it codes for the 3' half of the gene through the poly-A tail region. There is high homology between this cDNA to human GIT and a published sequence for rat liver cDNA. The clone was used as a probe for quantitation and characterization of GIT mRNA in rat tissues by use of RNA Dot blots and Northern blots. Only one species of mRNA having 2300 bases was found in tissues screened thus far (liver, spleen, kidney, and testis). This mRNA is sufficiently large to code for a protein the size of GIT (58,000 d). Work is in progress to compare mRNA levels as influenced by insulin levels.

  2. 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

  3. Crystal structure of human insulin-regulated aminopeptidase with specificity for cyclic peptides

    PubMed Central

    Hermans, Stefan J; Ascher, David B; Hancock, Nancy C; Holien, Jessica K; Michell, Belinda J; Yeen Chai, Siew; Morton, Craig J; Parker, Michael W

    2015-01-01

    Insulin-regulated aminopeptidase (IRAP or oxytocinase) is a membrane-bound zinc-metallopeptidase that cleaves neuroactive peptides in the brain and produces memory enhancing effects when inhibited. We have determined the crystal structure of human IRAP revealing a closed, four domain arrangement with a large, mostly buried cavity abutting the active site. The structure reveals that the GAMEN exopeptidase loop adopts a very different conformation from other aminopeptidases, thus explaining IRAP's unique specificity for cyclic peptides such as oxytocin and vasopressin. Computational docking of a series of IRAP-specific cognitive enhancers into the crystal structure provides a molecular basis for their structure–activity relationships and demonstrates that the structure will be a powerful tool in the development of new classes of cognitive enhancers for treating a variety of memory disorders such as Alzheimer's disease. PMID:25408552

  4. High-affinity insulin binding to an atypical insulin-like growth factor-I receptor in human breast cancer cells.

    PubMed Central

    Milazzo, G; Yip, C C; Maddux, B A; Vigneri, R; Goldfine, I D

    1992-01-01

    We studied the nature of insulin receptor binding in MCF-7 breast cancer cells. In both intact cells and solubilized receptor preparations, high-affinity insulin binding was seen. However, unlabeled insulin-like growth factor-I (IGF-I) was five-fold more potent in inhibiting 125I-insulin binding than insulin itself. With monoclonal antibodies to the insulin receptor, 30% of 125I-insulin binding was inhibited. In contrast when alpha-IR3, a monoclonal antibody that recognizes typical IGF-I receptor, was employed over 60% of 125I-insulin binding was inhibited. The B29-MAB-125I-insulin photoprobe was then cross-linked to MCF-7 membranes. Cross-linking was inhibited by both unlabeled insulin and IGF-I. Further, the B29-MAB-125I-insulin photoprobe cross-linked to MCF-7 membranes was strongly immunoprecipitated by alpha-IR3. Employing sequential affinity chromatography with insulin-Affi-gel followed by insulin receptor monoclonal antibody agarose, atypical insulin binding activity was separated from insulin receptor binding activity. This atypical receptor had intrinsic tyrosine kinase activity. Both insulin and IGF-I stimulated the phosphorylation of the receptor's beta subunit. In MCF-7 cells both IGF-I and insulin stimulated [3H]thymidine incorporation; alpha-IR3 blocked all of the IGF-I effect but only 50-60% of the insulin effect. This study demonstrates in MCF-7 cells that, in addition to typical insulin and IGF-I receptors, there is another receptor that binds both insulin and IGF-I with high affinity. Images PMID:1311720

  5. Insulin reverses D-glucose-increased nitric oxide and reactive oxygen species generation in human umbilical vein endothelial cells.

    PubMed

    González, Marcelo; Rojas, Susana; Avila, Pía; Cabrera, Lissette; Villalobos, Roberto; Palma, Carlos; Aguayo, Claudio; Peña, Eduardo; Gallardo, Victoria; Guzmán-Gutiérrez, Enrique; Sáez, Tamara; Salsoso, Rocío; Sanhueza, Carlos; Pardo, Fabián; Leiva, Andrea; Sobrevia, Luis

    2015-01-01

    Vascular tone is controlled by the L-arginine/nitric oxide (NO) pathway, and NO bioavailability is strongly affected by hyperglycaemia-induced oxidative stress. Insulin leads to high expression and activity of human cationic amino acid transporter 1 (hCAT-1), NO synthesis and vasodilation; thus, a protective role of insulin on high D-glucose-alterations in endothelial function is likely. Vascular reactivity to U46619 (thromboxane A2 mimetic) and calcitonin gene related peptide (CGRP) was measured in KCl preconstricted human umbilical vein rings (wire myography) incubated in normal (5 mmol/L) or high (25 mmol/L) D-glucose. hCAT-1, endothelial NO synthase (eNOS), 42 and 44 kDa mitogen-activated protein kinases (p42/44mapk), protein kinase B/Akt (Akt) expression and activity were determined by western blotting and qRT-PCR, tetrahydrobiopterin (BH4) level was determined by HPLC, and L-arginine transport (0-1000 μmol/L) was measured in response to 5-25 mmol/L D-glucose (0-36 hours) in passage 2 human umbilical vein endothelial cells (HUVECs). Assays were in the absence or presence of insulin and/or apocynin (nicotinamide adenine dinucleotide phosphate-oxidase [NADPH oxidase] inhibitor), tempol or Mn(III)TMPyP (SOD mimetics). High D-glucose increased hCAT-1 expression and activity, which was biphasic (peaks: 6 and 24 hours of incubation). High D-glucose-increased maximal transport velocity was blocked by insulin and correlated with lower hCAT-1 expression and SLC7A1 gene promoter activity. High D-glucose-increased transport parallels higher reactive oxygen species (ROS) and superoxide anion (O2•-) generation, and increased U46619-contraction and reduced CGRP-dilation of vein rings. Insulin and apocynin attenuate ROS and O2•- generation, and restored vascular reactivity to U46619 and CGRP. Insulin, but not apocynin or tempol reversed high D-glucose-increased NO synthesis; however, tempol and Mn(III)TMPyP reversed the high D-glucose-reduced BH4 level. Insulin and

  6. Human placental insulin binding in normal and well-controlled diabetic patients.

    PubMed

    Nelson, D M; Ortman-Nabi, J; Curran, E M

    1990-01-01

    Previous studies of insulin binding to placentas of both insulin-dependent and untreated gestational diabetic patients have described placentas from diabetics to contain fewer insulin receptors than placentas from nondiabetic gravidas. However, these studies were done using membrane fractions prepared from the placentas and at a time when adequacy of antepartum glycemic control in the diabetic patients was not routinely evaluated by self blood sugar measurement or hemoglobin A1 assay. The current study compares specific 125I-insulin binding in vitro to intact placental villi from 15 normal patients with insulin binding to intact villi obtained from 15 insulin-dependent diabetic mothers whose fasting and postprandial blood sugars and hemoglobin A1 levels were maintained in a range normal for term pregnancy. We demonstrate that insulin binding to intact placental villi is the same in this group of diabetic patients as in the nondiabetic patients.

  7. Increased bioactive lipids content in human subcutaneous and epicardial fat tissue correlates with insulin resistance.

    PubMed

    Błachnio-Zabielska, Agnieszka U; Baranowski, Marcin; Hirnle, Tomasz; Zabielski, Piotr; Lewczuk, Anna; Dmitruk, Iwona; Górski, Jan

    2012-12-01

    Obesity is a risk factor for metabolic diseases. Intramuscular lipid accumulation of ceramides, diacylglycerols, and long chain acyl-CoA is responsible for the induction of insulin resistance. These lipids are probably implicated in obesity-associated insulin resistance not only in skeletal muscle but also in fat tissue. Only few data are available about ceramide content in human subcutaneous adipose tissue. However, there are no data on DAG and LCACoA content in adipose tissue. The aim of our study was to measure the lipids content in human SAT and epicardial adipose tissue we sought to determine the bioactive lipids content by LC/MS/MS in fat tissue from lean non-diabetic, obese non-diabetic, and obese diabetic subjects and test whether the lipids correlate with HOMA-IR. We found, that total content of measured lipids was markedly higher in OND and OD subjects in both types of fat tissue (for all p < 0.001) as compared to LND group. In SAT we found positive correlation between HOMA-IR and C16:0-Cer (r = 0.79, p < 0.001) and between HOMA-IR and C16:0/18:2 DAG (r = 0.56, p < 0.001). In EAT we found a strong correlation between C16:0-CoA content and HOMA-IR (r = 0.73, p < 0.001). The study showed that in obese and obese diabetic patients, bioactive lipids content is greater in subcutaneous and epicardial fat tissue and the particular lipids content positively correlates with HOMA-IR.

  8. 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.

  9. Human Skeletal Muscle Disuse Atrophy: Effects on Muscle Protein Synthesis, Breakdown, and Insulin Resistance—A Qualitative Review

    PubMed Central

    Rudrappa, Supreeth S.; Wilkinson, Daniel J.; Greenhaff, Paul L.; Smith, Kenneth; Idris, Iskandar; Atherton, Philip J.

    2016-01-01

    The ever increasing burden of an aging population and pandemic of metabolic syndrome worldwide demands further understanding of the modifiable risk factors in reducing disability and morbidity associated with these conditions. Disuse skeletal muscle atrophy (sometimes referred to as “simple” atrophy) and insulin resistance are “non-pathological” events resulting from sedentary behavior and periods of enforced immobilization e.g., due to fractures or elective orthopedic surgery. Yet, the processes and drivers regulating disuse atrophy and insulin resistance and the associated molecular events remain unclear—especially in humans. The aim of this review is to present current knowledge of relationships between muscle protein turnover, insulin resistance and muscle atrophy during disuse, principally in humans. Immobilization lowers fasted state muscle protein synthesis (MPS) and induces fed-state “anabolic resistance.” While a lack of dynamic measurements of muscle protein breakdown (MPB) precludes defining a definitive role for MPB in disuse atrophy, some proteolytic “marker” studies (e.g., MPB genes) suggest a potential early elevation. Immobilization also induces muscle insulin resistance (IR). Moreover, the trajectory of muscle atrophy appears to be accelerated in persistent IR states (e.g., Type II diabetes), suggesting IR may contribute to muscle disuse atrophy under these conditions. Nonetheless, the role of differences in insulin sensitivity across distinct muscle groups and its effects on rates of atrophy remains unclear. Multifaceted time-course studies into the collective role of insulin resistance and muscle protein turnover in the setting of disuse muscle atrophy, in humans, are needed to facilitate the development of appropriate countermeasures and efficacious rehabilitation protocols. PMID:27610086

  10. Systems-wide Experimental and Modeling Analysis of Insulin Signaling through Forkhead Box Protein O1 (FOXO1) in Human Adipocytes, Normally and in Type 2 Diabetes.

    PubMed

    Rajan, Meenu Rohini; Nyman, Elin; Kjølhede, Preben; Cedersund, Gunnar; Strålfors, Peter

    2016-07-22

    Insulin resistance is a major aspect of type 2 diabetes (T2D), which results from impaired insulin signaling in target cells. Signaling to regulate forkhead box protein O1 (FOXO1) may be the most important mechanism for insulin to control transcription. Despite this, little is known about how insulin regulates FOXO1 and how FOXO1 may contribute to insulin resistance in adipocytes, which are the most critical cell type in the development of insulin resistance. We report a detailed mechanistic analysis of insulin control of FOXO1 in human adipocytes obtained from non-diabetic subjects and from patients with T2D. We show that FOXO1 is mainly phosphorylated through mTORC2-mediated phosphorylation of protein kinase B at Ser(473) and that this mechanism is unperturbed in T2D. We also demonstrate a cross-talk from the MAPK branch of insulin signaling to stimulate phosphorylation of FOXO1. The cellular abundance and consequently activity of FOXO1 are halved in T2D. Interestingly, inhibition of mTORC1 with rapamycin reduces the abundance of FOXO1 to the levels in T2D. This suggests that the reduction of the concentration of FOXO1 is a consequence of attenuation of mTORC1, which defines much of the diabetic state in human adipocytes. We integrate insulin control of FOXO1 in a network-wide mathematical model of insulin signaling dynamics based on compatible data from human adipocytes. The diabetic state is network-wide explained by attenuation of an mTORC1-to-insulin receptor substrate-1 (IRS1) feedback and reduced abundances of insulin receptor, GLUT4, AS160, ribosomal protein S6, and FOXO1. The model demonstrates that attenuation of the mTORC1-to-IRS1 feedback is a major mechanism of insulin resistance in the diabetic state.

  11. 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.

  12. 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.

  13. Expression of recombinant human bifunctional peptidylglycine α-amidating monooxygenase in CHO cells and its use for insulin analogue modification.

    PubMed

    Zieliński, Marcin; Wójtowicz-Krawiec, Anna; Mikiewicz, Diana; Kęsik-Brodacka, Małgorzata; Cecuda-Adamczewska, Violetta; Marciniak-Rusek, Alina; Sokołowska, Iwona; Łukasiewicz, Natalia; Gurba, Lidia; Odrowąż-Sypniewski, Michał; Baran, Piotr; Płucienniczak, Grażyna; Płucienniczak, Andrzej; Borowicz, Piotr; Szewczyk, Bogusław

    2016-03-01

    The availability of catalytically active peptidylglycine α-amidating monooxygenase (PAM) should provide the means to examine its potential use for the chemienzymatic synthesis of bioactive peptides for the purpose of pharmacological studies. Hypoglycemic activity is one of the most important features of insulin derivatives. Insulin glargine amide was found to show a time/effect profile which is distinctly more flat and thus more advantageous than insulin glargine itself. The aim of the study was to obtain recombinant PAM and use it for insulin analogue amidation. We stably expressed a recombinant PAM in CHO dhfr-cells in culture. Recombinant PAM was partially purified by fractional ammonium sulphate precipitation and ion-exchange chromatography. The enzyme was used to modify glycine-extended A22(G)-B31(K)-B32(R) human insulin analogue (GKR). Alpha-amidated insulin was analyzed by HPLC and mass spectrometry. Hypoglycemic activity of amidated and non-amidated insulin was compared. The pharmacodynamic effect was based on glucose concentration measurement in Wistar rats with hyperglycemia induced by streptozotocin. The overall glycemic profile up to 36 h was evaluated after subcutaneous single dosing at a range of 2.5-7.5 U/kg b.w. The experiment on rats confirmed with a statistical significance (P < 0.05) hypoglycemic activity of GKR-NH2 in comparison to a control group receiving 0.9% NaCl. Characteristics for GKR-NH2 profile was a rather fast beginning of action (0.5-2.0 h) and quite prolonged return to initial values. GKR-NH2 is a candidate for a hypoglycemic drug product in diabetes care. In addition, this work also provides a valuable alternative method for preparing any other recombinant bioactive peptides with C-terminal amidation.

  14. Curcumin Improves Palmitate-Induced Insulin Resistance in Human Umbilical Vein Endothelial Cells by Maintaining Proteostasis in Endoplasmic Reticulum

    PubMed Central

    Ye, Mao; Qiu, Hong; Cao, Yingkang; Zhang, Min; Mi, Yan; Yu, Jing; Wang, Changhua

    2017-01-01

    Dysfunction of proteasome and autophagy will result in disturbance of endoplasmic reticulum (ER) proteostasis, and thus lead to long-term and chronic ER stress and subsequent unfolded protein response (UPR), which is implicated in the occurrence and development of insulin resistance. Curcumin exerts beneficial metabolic effects in in vitro cells and in vivo animal models of diabetes and diabetic complications including cardiovascular diseases, due to its powerful anti-oxidative and anti-inflammatory properties. However, its impacts on insulin resistance of endothelial cells and its underlying mechanism(s) remain ill-defined. Herein, we tested the hypothesis that curcumin action in ER protein quality control was related to improvement of insulin resistance in human umbilical vein endothelial cells (HUVECs) cultured with saturated fatty acid palmitate. We found that palmitate treatment induced insulin resistance of HUVECs and activated both the ubiquitin-proteasome system (UPS) and autophagy. Palmitate-stimulated activation of the UPS and autophagy was attenuated by pharmacological inhibition of ER stress. In addition, curcumin supplementation mitigated palmitate-induced insulin resistance, inhibited the UPS, and activated autophagy. Furthermore, curcumin administration suppressed palmitate-induced protein aggregation and ER stress. Genetic inhibition of autophagy by silencing autophagy protein 5 (Atg5) completely restored total protein ubiquitination and protein aggregation in HUVECs treated with combined curcumin and palmitate. Atg5-knockdown also abolished the beneficial effects of curcumin on palmitate-induced ER stress, JNK/IRS-1 pathway as well as insulin signaling. Our results reveal that curcumin-activated autophagy could maintain proteostasis in ER leading to attenuation of ER stress and subsequent inhibition of JNK/IRS-1 pathway and improvement of insulin resistance. PMID:28377722

  15. Palmitate-induced inflammatory pathways in human adipose microvascular endothelial cells promote monocyte adhesion and impair insulin transcytosis.

    PubMed

    Pillon, Nicolas J; Azizi, Paymon M; Li, Yujin E; Liu, Jun; Wang, Changsen; Chan, Kenny L; Hopperton, Kathryn E; Bazinet, Richard P; Heit, Bryan; Bilan, Philip J; Lee, Warren L; Klip, Amira

    2015-07-01

    Obesity is associated with inflammation and immune cell recruitment to adipose tissue, muscle and intima of atherosclerotic blood vessels. Obesity and hyperlipidemia are also associated with tissue insulin resistance and can compromise insulin delivery to muscle. The muscle/fat microvascular endothelium mediates insulin delivery and facilitates monocyte transmigration, yet its contribution to the consequences of hyperlipidemia is poorly understood. Using primary endothelial cells from human adipose tissue microvasculature (HAMEC), we investigated the effects of physiological levels of fatty acids on endothelial inflammation and function. Expression of cytokines and adhesion molecules was measured by RT-qPCR. Signaling pathways were evaluated by pharmacological manipulation and immunoblotting. Surface expression of adhesion molecules was determined by immunohistochemistry. THP1 monocyte interaction with HAMEC was measured by cell adhesion and migration across transwells. Insulin transcytosis was measured by total internal reflection fluorescence microscopy. Palmitate, but not palmitoleate, elevated the expression of IL-6, IL-8, TLR2 (Toll-like receptor 2), and intercellular adhesion molecule 1 (ICAM-1). HAMEC had markedly low fatty acid uptake and oxidation, and CD36 inhibition did not reverse the palmitate-induced expression of adhesion molecules, suggesting that inflammation did not arise from palmitate uptake/metabolism. Instead, inhibition of TLR4 to NF-κB signaling blunted palmitate-induced ICAM-1 expression. Importantly, palmitate-induced surface expression of ICAM-1 promoted monocyte binding and transmigration. Conversely, palmitate reduced insulin transcytosis, an effect reversed by TLR4 inhibition. In summary, palmitate activates inflammatory pathways in primary microvascular endothelial cells, impairing insulin transport and increasing monocyte transmigration. This behavior may contribute in vivo to reduced tissue insulin action and enhanced tissue

  16. Nelfinavir Suppresses Insulin Signaling and Nitric Oxide Production by Human Aortic Endothelial Cells: Protective Effects of Thiazolidinediones

    PubMed Central

    Mondal, Debasis; Liu, Kai; Hamblin, Milton; Lasky, Joseph A.; Agrawal, Krishna C.

    2013-01-01

    ABSTRACT Background In human immunodeficiency virus 1 (HIV-1)–infected individuals, exposure to a protease inhibitor (PI)-based highly active antiretroviral therapy (HAART) regimen increases cardiovascular disease and endothelial dysfunction. However, the mechanisms of PI-induced effects on endothelial cells (ECs) are not known. Furthermore, strategies to suppress these deleterious outcomes of PIs need to be developed. Insulin-induced PI3K/Akt signaling and endothelial nitric oxide (NO)-synthase (eNOS) phosphorylation regulates NO production by ECs that maintain vascular homeostasis. We evaluated whether nelfinavir (NEL), a potent HIV-1 PI that suppresses Akt phosphorylation, can alter insulin-induced NO production in human aortic endothelial cells (HAECs) and whether insulin sensitization of HAECs via the peroxisome proliferator-activated receptor-gamma agonists, thiazolidinediones, can ameliorate these side effects. Methods Real-time NO production in HAECs was monitored by fluorimetric dyes DAF-FM DA and DAF-2 DA. Immunodetection studies were used to determine the phosphorylation of Akt, eNOS, insulin receptor-β (IR-β), insulin receptor substrate-1 (IRS-1), and PI3K/p85α. Expression of eNOS messenger RNA was measured by reverse transcription polymerase chain reaction. Results In vitro exposure (72 hours) of HAECs to NEL (0.25-2 μg/mL) decreased both basal (2.5-fold) and insulin-induced NO production (4- to 5-fold). NEL suppressed insulin-induced phosphorylation of both Akt and eNOS at serine residues 473 and 1177, respectively. NEL decreased tyrosine phosphorylation of IR-β, IRS-1, and PI3K. Coexposure to troglitazone (TRO; 250 nM) ameliorated the suppressive effects of NEL on insulin signaling and NO production. Coexposure to TRO also increased eNOS expression in NEL-treated HAECs. Conclusion Our findings indicate that treatment with potent insulin sensitizers may protect against PI-mediated endothelial dysfunction during long-term HAART. PMID:23533049

  17. 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.

  18. Peroxisome proliferator-activated receptor gamma (PPARG) modulates free fatty acid receptor 1 (FFAR1) dependent insulin secretion in humans

    PubMed Central

    Wagner, Robert; Hieronimus, Anja; Lamprinou, Apostolia; Heni, Martin; Hatziagelaki, Erifili; Ullrich, Susanne; Stefan, Norbert; Staiger, Harald; Häring, Hans-Ulrich; Fritsche, Andreas

    2014-01-01

    Genetic variation in FFAR1 modulates insulin secretion dependent on non-esterified fatty acid (NEFA) concentrations. We previously demonstrated lower insulin secretion in minor allele carriers of PPARG Pro12Ala in high-NEFA environment, but the mode of action could not been revealed. We tested if this effect is mediated by FFAR1 in humans. Subjects with increased risk of diabetes who underwent oral glucose tolerance tests were genotyped for 7 tagging SNPs in FFAR1 and PPARG Pro12Ala. The FFAR1 SNPs rs12462800 and rs10422744 demonstrated interactions with PPARG on insulin secretion. FFAR1 rs12462800 (p = 0.0006) and rs10422744 (p = 0.001) were associated with reduced insulin secretion in participants concomitantly carrying the PPARG minor allele and having high fasting FFA. These results suggest that the minor allele of the PPARG SNP exposes its carriers to modulatory effects of FFAR1 on insulin secretion. This subphenotype may define altered responsiveness to FFAR1-agonists, and should be investigated in further studies. PMID:25161890

  19. Differentiation of Human Mesenchymal Stem Cells into Insulin Producing Cells by Using A Lentiviral Vector Carrying PDX1

    PubMed Central

    Allahverdi, Amir; Abroun, Saied; Jafarian, Arefeh; Soleimani, Masoud; Taghikhani, Mohammad; Eskandari, Fatemeh

    2015-01-01

    Objective Type I diabetes is an immunologically-mediated devastation of insulin producing cells (IPCs) in the pancreatic islet. Stem cells that produce β-cells are a new promising tool. Adult stem cells such as mesenchymal stem cells (MSCs) are self renewing multi potent cells showing capabilities to differentiate into ectodermal, mesodermal and endodermal tissues. Pancreatic and duodenal homeobox factor 1 (PDX1) is a master regulator gene required for embryonic development of the pancreas and is crucial for normal pancreatic islets activities in adults. Materials and Methods We induced the over-expression of the PDX1 gene in human bone marrow MSCs (BM-MSCs) by Lenti-PDX1 in order to generate IPCs. Next, we examine the ability of the cells by measuring insulin/c-peptide production and INSULIN and PDX1 gene expressions. Results After transduction, MSCs changed their morphology at day 5 and gradually differentiated into IPCs. INSULIN and PDX1 expressions were confirmed by real time polymerase chain reaction (RT-PCR) and immunostaining. IPC secreted insulin and C-peptide in the media that contained different glucose concentrations. Conclusion MSCs differentiated into IPCs by genetic manipulation. Our result showed that lentiviral vectors could deliver PDX1 gene to MSCs and induce pancreatic differentiation. PMID:26199902

  20. Assessment of implantable infusion pumps for continuous infusion of human insulin in rats: potential for group housing.

    PubMed

    Jensen, Vivi Flou Hjorth; Mølck, Anne-Marie; Mårtensson, Martin; Strid, Mette Aagaard; Chapman, Melissa; Lykkesfeldt, Jens; Bøgh, Ingrid Brück

    2016-07-27

    Group housing is considered to be important for rats, which are highly sociable animals. Single housing may impact behaviour and levels of circulating stress hormones. Rats are typically used in the toxicological evaluation of insulin analogues. Human insulin (HI) is frequently used as a reference compound in these studies, and a comparator model of persistent exposure by HI infusion from external pumps has recently been developed to support toxicological evaluation of long-acting insulin analogues. However, this model requires single housing of the animals. Developing an insulin-infusion model which allows group housing would therefore greatly improve animal welfare. The aim of the present study was to investigate the suitability of implantable infusion pumps for HI infusion in group-housed rats. Group housing of rats implanted with a battery-driven pump proved to be possible. Intravenous infusion of HI lowered blood glucose levels persistently for two weeks, providing a comparator model for use in two-week repeated-dose toxicity studies with new long-acting insulin analogues, which allows group housing, and thereby increasing animal welfare compared with an external infusion model.

  1. Insulin and Insulin Resistance

    PubMed Central

    2005-01-01

    As obesity and diabetes reach epidemic proportions in the developed world, the role of insulin resistance and its consequences are gaining prominence. Understanding the role of insulin in wide-ranging physiological processes and the influences on its synthesis and secretion, alongside its actions from the molecular to the whole body level, has significant implications for much chronic disease seen in Westernised populations today. This review provides an overview of insulin, its history, structure, synthesis, secretion, actions and interactions followed by a discussion of insulin resistance and its associated clinical manifestations. Specific areas of focus include the actions of insulin and manifestations of insulin resistance in specific organs and tissues, physiological, environmental and pharmacological influences on insulin action and insulin resistance as well as clinical syndromes associated with insulin resistance. Clinical and functional measures of insulin resistance are also covered. Despite our incomplete understanding of the complex biological mechanisms of insulin action and insulin resistance, we need to consider the dramatic social changes of the past century with respect to physical activity, diet, work, socialisation and sleep patterns. Rapid globalisation, urbanisation and industrialisation have spawned epidemics of obesity, diabetes and their attendant co-morbidities, as physical inactivity and dietary imbalance unmask latent predisposing genetic traits. PMID:16278749

  2. Differential roles of MAPK-Erk1/2 and MAPK-p38 in insulin or insulin-like growth factor-I (IGF-I) signaling pathways for progesterone production in human ovarian cells.

    PubMed

    Seto-Young, D; Avtanski, D; Varadinova, M; Park, A; Suwandhi, P; Leiser, A; Parikh, G; Poretsky, L

    2011-06-01

    Insulin and insulin like-growth factor-I (IGF-I) participate in the regulation of ovarian steroidogenesis. In insulin resistant states ovaries remain sensitive to insulin because insulin can activate alternative signaling pathways, such as phosphatidylinositol-3-kinase (PI-3 kinase) and mitogen-activated protein-kinase (MAPK) pathways, as well as insulin receptors and type 1 IGF receptors. We investigated the roles of MAPK-Erk1/2 and MAPK-p38 in insulin and IGF-I signaling pathways for progesterone production in human ovarian cells. Human ovarian cells were cultured in tissue culture medium in the presence of varying concentrations of insulin or IGF-I, with or without PD98059, a specific MAPK-Erk1/2 inhibitor, with or without SB203580, a specific MAPK-p38 inhibitor or with or without a specific PI-3-kinase inhibitor LY294002. Progesterone concentrations were measured using radioimmunoassay. PD98059 alone stimulated progesterone production in a dose-dependent manner by up to 65% (p<0.001). Similarly, LY294002 alone stimulated progesterone production by 13-18% (p<0.005). However, when used together, PD98059 and LY294002 inhibited progesterone production by 17-20% (p<0.001). SB203580 alone inhibited progesterone production by 20-30% (p<0.001). Insulin or IGF-I alone stimulated progesterone production by 40-60% (p<0.001). In insulin studies, PD98059 had no significant effect on progesterone synthesis while SB203580 abolished insulin-induced progesterone production. Either PD98059 or SB203580 abolished IGF-I-induced progesterone production. Both MAPK-Erk1/2 and MAPK-p38 participate in IGF-I-induced signaling pathways for progesterone production, while insulin-induced progesterone production requires MAPK-p38, but not MAPK-Erk1/2. These studies provide further evidence for divergence of insulin and IGF-I signaling pathways for human ovarian cell steroidogenesis.

  3. Activation of IGF-1 and insulin signaling pathways ameliorate mitochondrial function and energy metabolism in Huntington's Disease human lymphoblasts.

    PubMed

    Naia, Luana; Ferreira, I Luísa; Cunha-Oliveira, Teresa; Duarte, Ana I; Ribeiro, Márcio; Rosenstock, Tatiana R; Laço, Mário N; Ribeiro, Maria J; Oliveira, Catarina R; Saudou, Frédéric; Humbert, Sandrine; Rego, A Cristina

    2015-02-01

    Huntington's disease (HD) is an inherited neurodegenerative disease caused by a polyglutamine repeat expansion in the huntingtin protein. Mitochondrial dysfunction associated with energy failure plays an important role in this untreated pathology. In the present work, we used lymphoblasts obtained from HD patients or unaffected parentally related individuals to study the protective role of insulin-like growth factor 1 (IGF-1) versus insulin (at low nM) on signaling and metabolic and mitochondrial functions. Deregulation of intracellular signaling pathways linked to activation of insulin and IGF-1 receptors (IR,IGF-1R), Akt, and ERK was largely restored by IGF-1 and, at a less extent, by insulin in HD human lymphoblasts. Importantly, both neurotrophic factors stimulated huntingtin phosphorylation at Ser421 in HD cells. IGF-1 and insulin also rescued energy levels in HD peripheral cells, as evaluated by increased ATP and phosphocreatine, and decreased lactate levels. Moreover, IGF-1 effectively ameliorated O2 consumption and mitochondrial membrane potential (Δψm) in HD lymphoblasts, which occurred concomitantly with increased levels of cytochrome c. Indeed, constitutive phosphorylation of huntingtin was able to restore the Δψm in lymphoblasts expressing an abnormal expansion of polyglutamines. HD lymphoblasts further exhibited increased intracellular Ca(2+) levels before and after exposure to hydrogen peroxide (H2O2), and decreased mitochondrial Ca(2+) accumulation, being the later recovered by IGF-1 and insulin in HD lymphoblasts pre-exposed to H2O2. In summary, the data support an important role for IR/IGF-1R mediated activation of signaling pathways and improved mitochondrial and metabolic function in HD human lymphoblasts.

  4. Insulin secretion and interleukin-1β dependent mechanisms in human diabetes remission after metabolic surgery.

    PubMed

    Chen, Chih-Yen; Lee, Wei-Jei; Asakawa, A; Fujitsuka, N; Chong, Keong; Chen, Shu-Chun; Lee, Shou-Dong; Inui, A

    2013-01-01

    To compare endocrine, metabolic, and inflammatory changes induced by gastric bypass (GB) and sleeve gastrectomy (SG) in patients with type 2 diabetes mellitus (T2DM), and to investigate the mechanisms of success after metabolic surgery. Sixteen GB and 16 SG patients were followed up before and at 1 year after surgery. The 75-g oral glucose tolerance test (OGTT) was performed before and after surgery. Glucose homeostasis, serum interleukin-1β, plasma gut hormones and adipokines, and the United Kingdom Prospective Diabetes Study (UKPDS) ten-year cardiovascular risks were evaluated. The diabetes remission rate was significantly higher in GB than SG. Changes in the area under the curve (AUC) for glucose were greater in those with complete and partial remission after GB and remitters after SG than non-remitters after SG, whereas changes in AUC for C-peptide were higher in complete and partial remitters after GB than non-remitters after SG. Insulinogenic index was enhanced and serum interleukin-1β was reduced in complete remitters after GB and remitters after SG. Logistic regression analysis confirmed that insulinogenic index and interleukin-1β, not insulin resistance, were the factors determining the success of diabetes remission after metabolic surgeries. GB and SG significantly reduced the ten-year risk of coronary heart disease and fatal coronary heart disease in T2DM patients after surgery, while GB had the additional benefit of reduced stroke risk. Human diabetes remission after metabolic surgery is through insulin secretion and interleukin-1β dependent mechanisms. GB is superior to SG in cardiocerebral risk reduction in Asian non-morbidly obese, not well-controlled T2DM patients.

  5. Integrative mRNA-microRNA analyses reveal novel interactions related to insulin sensitivity in human adipose tissue.

    PubMed

    Kirby, Tyler J; Walton, R Grace; Finlin, Brian; Zhu, Beibei; Unal, Resat; Rasouli, Neda; Peterson, Charlotte A; Kern, Philip A

    2016-02-01

    Adipose tissue has profound effects on whole-body insulin sensitivity. However, the underlying biological processes are quite complex and likely multifactorial. For instance, the adipose transcriptome is posttranscriptionally modulated by microRNAs, but the relationship between microRNAs and insulin sensitivity in humans remains to be determined. To this end, we utilized an integrative mRNA-microRNA microarray approach to identify putative molecular interactions that regulate the transcriptome in subcutaneous adipose tissue of insulin-sensitive (IS) and insulin-resistant (IR) individuals. Using the NanoString nCounter Human v1 microRNA Expression Assay, we show that 17 microRNAs are differentially expressed in IR vs. IS. Of these, 16 microRNAs (94%) are downregulated in IR vs. IS, including miR-26b, miR-30b, and miR-145. Using Agilent Human Whole Genome arrays, we identified genes that were predicted targets of miR-26b, miR-30b, and miR-145 and were upregulated in IR subjects. This analysis produced ADAM22, MYO5A, LOX, and GM2A as predicted gene targets of these microRNAs. We then validated that miR-145 and miR-30b regulate these mRNAs in differentiated human adipose stem cells. We suggest that use of bioinformatic integration of mRNA and microRNA arrays yields verifiable mRNA-microRNA pairs that are associated with insulin resistance and can be validated in vitro.

  6. 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

  7. Immobilization of primary cultures of insulin-releasing human pancreatic cells.

    PubMed

    Mantovani, Marluce da Cunha; da Conceição, Mateus Meneghesso; Ferreira, Ari José Scattone; Labriola, Letícia; dos Santos, Patrícia Barros; Tonso, Aldo; Pereira, Carlos Augusto; El-Dorry, Hamza; Sogayar, Mari Cleide

    2009-01-01

    Transplantation of pancreatic islets isolated from organ donors constitutes a promising alternative treatment for type1 Diabetes, however, it is severely limited by the shortage of organ donors. Ex-vivo islet cell cultures appear as an attractive but still elusive approach for curing type 1 Diabetes. It has recently been shown that, even in the absence of fibrotic overgrowth, several factors, such as insufficient nutrition of the islet core, represent a major barrier for long-term survival of islets grafts. The use of immobilized dispersed cells may contribute to solve this problem due to conceivably easier nutritional and oxygen support to the cells.  Therefore, we set out to establish an immobilization method for primary cultures of human pancreatic cells by adsorption onto microcarriers (MCs). Dispersed human islets cells were seeded onto Cytodex1 microcarriers and cultured in bioreactors for up to eight days. The cell number increased and islet cells maintained their insulin secretion levels throughout the time period studied. Moreover, the cells also presented a tendency to cluster upon five days culturing.  Therefore, this procedure represents a useful tool for controlled studies on islet cells physiology and, also, for biotechnological applications.

  8. Regeneration of insulin-producing pancreatic cells using a volatile bioactive compound and human teeth.

    PubMed

    Okada, Mio; Imai, Toshio; Yaegaki, Ken; Ishkitiev, Nikolay; Tanaka, Tomoko

    2014-10-30

    Transplantation of insulin (INS)-secreting cells differentiated in vitro from stem cells promises a safer and easier treatment of severe diabetes mellitus. A volatile bioactive compound, hydrogen sulfide (H2S), promotes cell differentiation; human tooth-pulp stem cells undergo hepatic differentiation. The aim of this study is to develop a novel protocol using H2S to enhance pancreatic differentiation from the CD117(+) cell fraction of human tooth pulp. During the differentiation, the cells were exposed to 0.1 ng ml(-1) H2S. Immunocytochemistry, RT-PCR, determination of INS c-peptide content and flow cytometry of pancreatically related markers were carried out. Expression of WNT and the PI3K/AKT signaling pathway were also determined by PCR array. After differentiation, INS, glucagon (GCG), somatostatin (SST) and pancreatic polypeptide (PPY) were positive when examined by immunofluorescence. INS and GCG were also determined flow-cytometrically. Only the cells expressing INS increased after H2S exposure. The number of cells expressing GCG was significantly decreased. Genes involved in canonical WNT and the WNT/calcium pathways were highly expressed after H2S exposure. H2S accelerated INS synthesis and secretion by regenerated INS-producing cells from human teeth. All signaling pathway functions of the PI3K-AKT pathway were extremely activated by H2S exposure. The matured INS-producing cells originating in human teeth were increased by H2S in order to control blood-glucose level.

  9. In vivo imaging of insulin receptors by PET: preclinical evaluation of iodine-125 and iodine-124 labelled human insulin.

    PubMed

    Iozzo, P; Osman, S; Glaser, M; Knickmeier, M; Ferrannini, E; Pike, V W; Camici, P G; Law, M P

    2002-01-01

    [A(14)-*I]iodoinsulin was prepared for studies to assess the suitability of labeled iodoinsulin for positron emission tomography (PET). Iodine-125 was used to establish the methods and for preliminary studies in rats. Further studies and PET scanning in rats were carried out using iodine-124. Tissue and plasma radioactivity was measured as the uptake index (UI = [cpm x (g tissue)(-1)]/[cpm injected x (g body weight)(-1)]) at 1 to 40 min after intravenous injection of either [A(14)-(125)I]iodoinsulin or [A(14)-(124)I]iodoinsulin. For both radiotracers, initial clearance of radioactivity from plasma was rapid (T(1/2) approximately 1 min), reaching a plateau (UI = 2.8) at approximately 5 min which was maintained for 35 min. Tissue biodistributions of the two radiotracers were comparable; at 10 min after injection, UI for myocardium was 2.4, liver, 4.0, pancreas, 5.4, brain, 0.17, kidney, 22, lung, 2.3, muscle, 0.54 and fat, 0.28. Predosing rats with unlabelled insulin reduced the UI for myocardium (0.95), liver (1.8), pancreas (1.2) and brain (0.08), increased that for kidney (61) but had no effect on that for lung (2.5), muscle (0.50) or fat (0.34). Analysis of radioactivity in plasma demonstrated a decrease of [(125)I]iodoinsulin associated with the appearance of labeled metabolites; the percentage of plasma radioactivity due to [(125)I]iodoinsulin was 40% at 5 min and 10% at 10 min. The heart, liver and kidneys were visualized using [(124)I]iodoinsulin with PET.

  10. 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

  11. Computer-aided process analysis and economic evaluation for biosynthetic human insulin production-A case study.

    PubMed

    Petrides, D; Sapidou, E; Calandranis, J

    1995-12-05

    Human insulin was the first mammalian protein produced in bacteria using recombinant DNA technology. Two technologies were developed; the first based on the separate expression of precursors of chains A and B of insulin, and the second based on the expression of a precursor of proinsulin as a Trp-E fusion protein. Both technologies utilized Escherichia coli as an expression system. Later, a third technology was developed based on a strain of yeast that can secrete a precursor of insulin. The second E. coli process, a variation of which has been commercialized by Eli Lilly and Co., is analyzed in this article from a process design and economic evaluation viewpoint. The objective of this work is to elucidate the technical complexity and high cost associated with the manufacturing of biopharmaceuticals. Human insulin is a good example of a protein-based biopharmaceutical produced in large quantities (a fex tons per year) that requires large scale equipment and presents a multitude of scale-up challenges. Based onthe analysis, a number of conclusions are drawn regarding the cost breakdown and cost dependency on process parameters. Recommendations are made for cost reduction and environmental impact minimization. This analysis was performed using a software tool for computer-aided bioprocess design. (c) 1995 John Wiley & Sons, Inc.

  12. Pragmatic use of insulin degludec/insulin aspart co-formulation: A multinational consensus statement

    PubMed Central

    Kalra, Sanjay; Latif, Zafar A.; Comlekci, Abdurrahman; Galvez, Guillermo Gonzalez; Malik, Rached; Pathan, Md Faruque; Kumar, Ajay

    2016-01-01

    Insulin degludec/insulin aspart (IDegAsp) is a modern coformulation of ultra-long-acting basal insulin degludec, with rapid-acting insulin aspart. IDegAsp provides effective, safe, well-tolerated glycemic control, with a low risk of hypoglycemia while allowing flexibility in meal patterns and timing of administration. This consensus statement describes a pragmatic framework to identify patients who may benefit from IDegAsp therapy. It highlights the utility of IDegAsp in type 2 diabetic patients who are insulin-naive, suboptimally controlled on basal or premixed insulin, or dissatisfied with basal–bolus regimens. It also describes potential IDegAsp usage in type 1 diabetic patients. PMID:27366723

  13. Insulin differentially modulates the peripheral endocannabinoid system in human subcutaneous abdominal adipose tissue from lean and obese individuals.

    PubMed

    Murdolo, G; Kempf, K; Hammarstedt, A; Herder, C; Smith, U; Jansson, P-A

    2007-09-01

    Human obesity has been associated with a dysregulation of the peripheral and adipose tissue (AT) endocannabinoid system (ES). The aim of this study was to elucidate the acute in vivo effects of insulin on gene expression of the cannabinoid type 1 (CB-1) and type 2 (CB-2) receptors, as well as of the fatty acid amide hydrolase (FAAH) in the sc abdominal adipose tissue (SCAAT). Nine lean (L) and 9 obese (OB), but otherwise healthy males were studied in the fasting state and during a euglycemic hyperinsulinemic clamp (40 mU/m2 * min(-1)). SCAAT biopsies were obtained at baseline and after 270 min of i.v. maintained hyperinsulinemia. The basal SCAAT gene expression pattern revealed an upregulation of the FAAH in the OB (p=0.03 vs L), whereas similar CB-1 and CB-2 mRNA levels were seen. Following hyperinsulinemia, the FAAH mRNA levels significantly increased approximately 2-fold in the L (p=0.01 vs baseline) but not in the OB. In contrast, insulin failed to significantly change both the adipose CB-1 and CB-2 gene expression. Finally, the FAAH gene expression positively correlated with the fasting serum insulin concentration (r 0.66; p=0.01), whereas an inverse association with the whole-body glucose disposal (r -0.58; p<0.05) was seen. Taken together, these first time observations demonstrate that the ES-related genes in the SCAAT differentially respond to hyperinsulinemia in lean/insulin-sensitive and in obese/insulin-resistant individuals. We suggest that insulin may play a key role in the obesity-linked dysregulation of the adipose ES at the gene level.

  14. Lipodystrophy in human immunodeficiency virus patients impairs insulin action and induces defects in beta-cell function.

    PubMed

    Andersen, Ove; Haugaard, Steen B; Andersen, Ulrik B; Friis-Møller, Nina; Storgaard, Heidi; Vølund, Aage; Nielsen, Jens Ole; Iversen, Johan; Madsbad, Sten

    2003-10-01

    The pathophysiology of insulin resistance in human immunodeficiency virus (HIV)-associated lipodystrophy syndrome (HALS) is not fully clarified. We investigated 18 men with HALS and 18 HIV-positive males without lipodystrophy (control subjects). Duration and modality of antiretroviral therapy were similar between study groups. A hyperinsulinemic euglycemic clamp showed an impaired glucose disposal rate (GDR) in HALS patients (5.6 v 8.3 mg glucose/min. kg(FFM), P =.0006). As demonstrated by indirect calorimetry, HALS patients showed an impaired nonoxidative glucose metabolism (NOGM, 2.2 v 4.2, P =.006), whereas levels of basal and insulin-stimulated oxidative glucose metabolism (OGM) (2.4 v 2.3, P =.55, and 3.3 v 4.0, P =.064, respectively) were not significantly different between groups. Despite comparable total fat masses, dual energy x-ray absorptiometry (DEXA) scans showed that the percentage of limb fat (ie, peripheral-fat-mass/[peripheral-fat-mass + trunk-fat-mass]. 100%) was reduced in HALS patients (36% v 46%, P =.0002). Multiple linear regression analysis indicated that percentage of limb fat explained 53% of the variability of GDR and 45% of the variability of NOGM in HALS patients. In HALS patients, leg fat mass correlated positively with NOGM (r =.51, P <.05), whereas abdominal fat mass and NOGM did not correlate (P =.91). Analyzing the relationship between first phase insulin secretion and insulin sensitivity, 6 HALS patients compared with none of the control subjects exhibited impaired insulin secretion (P <.05). Our data suggest that fat redistribution independently of antiretroviral therapy is highly related to insulin resistance in HALS patients. Furthermore, in HALS patients, impaired glucose metabolism most likely relates to decreased NOGM and to defects in beta-cell function.

  15. Looking at the carcinogenicity of human insulin analogues via the intrinsic disorder prism

    PubMed Central

    Redwan, Elrashdy M.; Linjawi, Moustafa H.; Uversky, Vladimir N.

    2016-01-01

    Therapeutic insulin, in its native and biosynthetic forms as well as several currently available insulin analogues, continues to be the protein of most interest to researchers. From the time of its discovery to the development of modern insulin analogues, this important therapeutic protein has passed through several stages and product generations. Beside the well-known link between diabetes and cancer risk, the currently used therapeutic insulin analogues raised serious concerns due to their potential roles in cancer initiation and/or progression. It is possible that structural variations in some of the insulin analogues are responsible for the appearance of new oncogenic species with high binding affinity to the insulin-like growth factor 1 (IGF1) receptor. The question we are trying to answer in this work is: are there any specific features of the distribution of intrinsic disorder propensity within the amino acid sequences of insulin analogues that may provide an explanation for the carcinogenicity of the altered insulin protein? PMID:26983499

  16. Protamine coated proliposomes of recombinant human insulin encased in Eudragit S100 coated capsule offered improved peptide delivery and permeation across Caco-2 cells.

    PubMed

    Sharma, Shiva; Jyoti, Kiran; Sinha, Richa; Katyal, Anju; Jain, Upendra Kumar; Madan, Jitender

    2016-10-01

    In present investigation, recombinant human insulin loaded proliposomes and protamine sulphate coated proliposomes (rh insulin-proliposomes and Pt-rh insulin proliposomes) were encased in Eudragit S100 coated capsule to offer peptide release in simulated intestinal conditions. The particle size and zeta potential of Pt-rh insulin proliposomes were measured to be 583.2±10.2nm/+28.3±3.7mV significantly (P<0.05) higher than 569.7±14.9nm/-37.9±4.3mV and 534.6±24.6nm/-42.7±2.8mV of rh insulin proliposomes and proliposomes, respectively. Next, shape and surface morphology analysis pointed out the successful transformation of proliposomes in to spherical shaped liposomes. Furthermore, in vitro release study specified that free rh insulin solution encapsulated in uncoated gelatine capsule released 97.8% of peptide within 1h in SGF (pH~1.2). On other hand, rh insulin-proliposomes and Pt-rh insulin proliposomes encased in Eudragit S100 coated capsule released 93.2% and 81.6% of peptide, up to 24 h in SIF (pH~7.2). SDS-PAGE and circular dichroism (CD) ascertained the stability and intactness of isolated rh insulin from tailored dosage forms. In last, cellular uptake in Caco-2 cells indicating the superiority of Pt-rh insulin proliposomes in comparison to rh-insulin proliposomes and free rh insulin solution, respectively. In conclusion, Pt-rh insulin proliposomes displayed promising results and may be considered for further investigations.

  17. Insulin Therapy

    MedlinePlus

    ... 3 hours and lasts 12 to 16 hours.Long-acting insulin (such as insulin glargine and insulin detemir) ... hard to time their meals around regular insulin injections. Sometimes they end up eating too soon or ...

  18. 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

  19. Defective regulation of insulin release and transmembrane Ca2+ fluxes by human islet cell tumours.

    PubMed Central

    Flatt, P. R.; Swanston-Flatt, S. K.; Powell, C. J.; Marks, V.

    1987-01-01

    Regulation of insulin release and transmembrane Ca2+ fluxes was examined using pieces of 3 benign medullary-type insulinomas removed from the pancreas of female patients at surgery. Immunocytochemical staining confirmed the presence of insulin-containing cells with no demonstrable glucagon, somatostatin or pancreatic polypeptide. After 3 days of culture in RPMI-1640, tumour pieces released 11-158 mg insulin kg-1 dry wt during acute 60 min incubations with the concomitant uptake of 2-47 mmol 45Ca kg-1 into the intracellular lanthanum-nondisplaceable pool. At 2.56 mM Ca2+, glucose alone or in combination with glyceraldehyde, mannoheptulose or diazoxide did not modify insulin release or 45Ca uptake. Theophylline significantly increased insulin release from 2 tumours with a small stimulatory effect on the third. A depolarising concentration of K+ enhanced insulin release from one tumour but this was not associated with an increase of 45Ca uptake. Calcium antagonists, (verapamil, D-600 and trifluoroperazine) and calcium ionophores (A23187 and Br-X537A) failed to modify insulin release or 45Ca uptake by each of the two tumours tested. Evaluation of 45Ca efflux from one tumour confirmed the unresponsiveness to glucose, K+, verapamil and A23187. Prolonged culture of 2 tumours for up to 16 days was associated with the gradual decline of insulin release to a steady output of 2-15 ng 24 h-1. Addition of verapamil to the cultures inhibited insulin output from one tumour, but mannoheptulose or diazoxide were without effect. The results indicate that inappropriate insulin release from these 3 benign medullary-type insulinomas is associated with disturbances in the regulation of transmembrane Ca2+ fluxes. Images Figure 1 PMID:2825749

  20. Modeling the effect of insulin-like growth factor-1 on human cell growth.

    PubMed

    Phillips, Gemma M A; Shorten, Paul R; Wake, Graeme C; Guan, Jian

    2015-01-01

    Insulin-like growth factor-1 (IGF-1) plays a key role in human growth and development. The interactions of IGF-1 with IGF-1 receptors and IGF-1 binding proteins (IGFBPs) regulate IGF-1 function. Recent research suggests that a metabolite of IGF-1, cyclo-glycyl-proline (cGP), has a role in regulating IGF-1 homeostasis. A component of this interaction is believed to be the competitive binding of IGF-1 and cGP to IGFBPs. In this paper we describe a mathematical model of the interaction between IGF-1 and cGP on human cell growth. The model can be used to understand the interaction between IGF-1, IGFBPs, cGP and IGF-1 receptors along with the kinetics of cell growth. An explicit model of the known interactions between IGF-1, cGP, IGFBPs, IGF-1 receptors explained a large portion of the variance in cell growth (R(2) = 0.83). An implicit model of the interactions between IGF-1, cGP, IGFBPs, IGF-1 receptors that included a hypothesized feedback of cGP on IGF-1 receptors explained nonlinear features of interaction between IGF-1 and cGP not described by the explicit model (R(2) = 0.84). The model also explained the effect of IGFBP antibody on the interaction between cGP and IGF-1 (R(2) = 0.78). This demonstrates that the competitive binding of IGF-1 and cGP to IGFBPs plays a large role in the interaction between IGF-1 and cGP, but that other factors potentially play a role in the interaction between cGP and IGF-1. These models can be used to predict the complex interaction between IGF-1 and cGP on human cell growth and form a basis for further research in this field.

  1. Effects of low-dose recombinant human insulin-like growth factor-I on insulin sensitivity, growth hormone and glucagon levels in young adults with insulin-dependent diabetes mellitus.

    PubMed

    Acerini, C L; Harris, D A; Matyka, K A; Watts, A P; Umpleby, A M; Russell-Jones, D L; Dunger, D B

    1998-12-01

    Despite recent interest in the therapeutic potential of recombinant human insulin-like growth factor-I (rhIGF-I) in the treatment of diabetes mellitus, its mechanism of action is still not defined. We have studied the effects of low-dose bolus subcutaneous rhIGF-I (40 microg/kg and 20 microg/kg) on insulin sensitivity, growth hormone (GH) and glucagon levels in seven young adults with insulin-dependent diabetes mellitus (IDDM) using a randomized double-blind placebo-controlled crossover study design. Each was subjected to a euglycemic clamp (5 mmol/L) protocol consisting of a variable-rate insulin infusion clamp (6:00 PM to 8:00 AM) followed by a two-dose hyperinsulinemic clamp (insulin infusion of 0.75 mU x kg(-1) x min(-1) from 8 to 10 AM and 1.5 mU x kg(-1) x min(-1) from 10 AM to 12 noon) incorporating [6,6 2H2]glucose tracer for determination of glucose production/utilization rates. Following rhIGF-I administration, the serum IGF-I level (mean +/- SEM) increased (40 microg/kg, 655 +/- 90 ng/mL, P < .001; 20 microg/kg, 472 +/- 67 ng/mL, P < .001; placebo, 258 +/- 51 ng/mL). Dose-related reductions in insulin were observed during the period of steady-state euglycemia (1 AM to 8 AM) (40 microg/kg, 48 +/- 5 pmol/L, P = .01; 20 microg/kg, 58 +/- 8 pmol/L, P = .03; placebo, 72 +/- 8 pmol/L). The mean overnight GH level (40 microg/kg, 9.1 +/- 1.4 mU/L, P = .04; 20 microg/kg, 9.6 +/- 2.0 mU/L, P = .12; placebo, 11.3 +/- 1.7 mU/L) and GH pulse amplitude (40 microg/kg, 18.8 +/- 2.9 mU/L, P = .04; 20 microg/kg, 17.0 +/- 3.4 mU/L, P > .05; placebo, 23.0 +/- 3.7 mU/L) were also reduced. No differences in glucagon, IGF binding protein-1 (IGFBP-1), acetoacetate, or beta-hydroxybutyrate levels were found. During the hyperinsulinemic clamp conditions, no differences in glucose utilization were noted, whereas hepatic glucose production was reduced by rhIGF-I 40 microg/kg (P = .05). Our data demonstrate that in subjects with IDDM, low-dose subcutaneous rhIGF-I leads to a dose

  2. 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.

  3. 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.

  4. In vitro differentiation of human umbilical cord Wharton’s jelly mesenchymal stromal cells to insulin producing clusters

    PubMed Central

    Nekoei, Seideh Masoomeh; Azarpira, Negar; Sadeghi, Ladan; Kamalifar, Sulmaz

    2015-01-01

    AIM: To investigate the differentiation of human Wharton’s jelly derived mesenchymal stromal cells (WJ-MSCs) to insulin producing clusters (IPC) this study was conducted. METHODS: The umbilical cords samples were collected from full term caesarian section mothers and the WJ-MSCS were cultured from tissue explants in High glucose-Dulbecco’s Modified Eagle Medium (H-DMEM); H-DMEM supplemented with 10% fetal bovine serum (FBS) and antibiotics. The expression of CD90, CD44, CD105, CD34 and CD133 as well as osteogenic and adipogenic differentiation of cells in appropriate medium were also evaluated. The cells were differentiated toward IPC with changing the culture medium and adding the small molecules such as nicotinic acid, epidermal growth factor, and exendin-4 during 3 wk period. The gene expression of PDX1, NGN3, Glut2, insulin was monitored by reveres transcription polymerase chain reaction method. The differentiated clusters were stained with Dithizone (DTZ) which confirms the presence of insulin granules. The insulin challenge test (low and high glucose concentration in Krebs-Ringer HEPES buffer) was also used to evaluate the functional properties of differentiated clusters. RESULTS: WJ-MSCS were positive for mesenchymal surface markers (CD90, CD44, CD105), and negative for CD34 and CD133. The accumulation of lipid vacuoles and deposition of calcium mineral in cells were considered as adipogenic and osteogenic potential of WJ-MSCS. The cells also expressed the transcriptional factors such as Nanog and OCT4. During this three step differentiation, the WJ-MSCS morphology was gradually changed from spindle shaped cells in to epithelioid cells and eventually to three dimensional clusters. The clusters expressed PDX1, NGN3, Glut2, and insulin. The cells became bright red color when stained with DTZ and the insulin secretion was also confirmed. In glucose challenge test a significant increase in insulin secretion from 0.91 ± 0.04 μIu/mL (2.8 mmol/L glucose) to

  5. Interaction between free fatty acids and insulin in the acute control of very low density lipoprotein production in humans.

    PubMed

    Lewis, G F; Uffelman, K D; Szeto, L W; Weller, B; Steiner, G

    1995-01-01

    Changes in VLDL triglyceride and VLDL apo B production were determined semiquantitatively in healthy young men by examining the effect of altering plasma insulin and/or FFA levels on the change in the slopes of the specific activity of VLDL [3H]triglyceride glycerol or the 131I-VLDL apo B versus time curves. In one study (n = 8) insulin was infused for 5 h using the euglycemic hyperinsulinemic clamp technique. Plasma FFA levels declined by approximately 80% (0.52 +/- 0.01 to 0.11 +/- 0.02 mmol/liter), VLDL triglyceride production decreased by 66.7 +/- 4.2% (P = 0.0001) and VLDL apo B production decreased by 51.7 +/- 10.6% (P = 0.003). In a second study (n = 8) heparin and Intralipid (Baxter Corp., Toronto, Canada) were infused with insulin to prevent the insulin-mediated fall in plasma FFA levels. Plasma FFA increased approximately twofold (0.43 +/- 0.05 to 0.82 + 0.13 mmol/liter), VLDL triglyceride production decreased to a lesser extent than with insulin alone (P = 0.006) (-31.8 +/- 9.5%, decrease from baseline P = 0.03) and VLDL apo B production did not decrease significantly (-6.3 +/- 13.6%, P = NS). In a third study (n = 8) when heparin and Intralipid were infused without insulin, FFA levels rose approximately twofold (0.53 +/- 0.04 to 0.85 +/- 0.1 mmol/liter), VLDL triglyceride production increased by 180.1 +/- 45.7% (P = 0.008) and VLDL apo B production increased by 94.2 +/- 28.7% (P = 0.05). We confirm our previous observation that acute hyperinsulinemia suppresses VLDL triglyceride and VLDL apo B production in healthy humans. In addition, we have demonstrated that elevation of plasma FFA levels acutely stimulates VLDL production in vivo in healthy young males. Elevating plasma FFA during hyperinsulinemia attenuates but does not completely abolish the suppressive effect of insulin on VLDL production, at least with respect to VLDL triglycerides. Therefore, in normal individuals the acute inhibition of VLDL production by insulin in vivo is only partly due to

  6. Novel Small Molecule Glucagon-Like Peptide-1 Receptor Agonist Stimulates Insulin Secretion in Rodents and From Human Islets

    PubMed Central

    Sloop, Kyle W.; Willard, Francis S.; Brenner, Martin B.; Ficorilli, James; Valasek, Kathleen; Showalter, Aaron D.; Farb, Thomas B.; Cao, Julia X.C.; Cox, Amy L.; Michael, M. Dodson; Gutierrez Sanfeliciano, Sonia Maria; Tebbe, Mark J.; Coghlan, Michael J.

    2010-01-01

    OBJECTIVE The clinical effectiveness of parenterally-administered glucagon-like peptide-1 (GLP-1) mimetics to improve glucose control in patients suffering from type 2 diabetes strongly supports discovery pursuits aimed at identifying and developing orally active, small molecule GLP-1 receptor agonists. The purpose of these studies was to identify and characterize novel nonpeptide agonists of the GLP-1 receptor. RESEARCH DESIGN AND METHODS Screening using cells expressing the GLP-1 receptor and insulin secretion assays with rodent and human islets were used to identify novel molecules. The intravenous glucose tolerance test (IVGTT) and hyperglycemic clamp characterized the insulinotropic effects of compounds in vivo. RESULTS Novel low molecular weight pyrimidine-based compounds that activate the GLP-1 receptor and stimulate glucose-dependent insulin secretion are described. These molecules induce GLP-1 receptor-mediated cAMP signaling in HEK293 cells expressing the GLP-1 receptor and increase insulin secretion from rodent islets in a dose-dependent manner. The compounds activate GLP-1 receptor signaling, both alone or in an additive fashion when combined with the endogenous GLP-1 peptide; however, these agonists do not compete with radiolabeled GLP-1 in receptor-binding assays. In vivo studies using the IVGTT and the hyperglycemic clamp in Sprague Dawley rats demonstrate increased insulin secretion in compound-treated animals. Further, perifusion assays with human islets isolated from a donor with type 2 diabetes show near-normalization of insulin secretion upon compound treatment. CONCLUSIONS These studies characterize the insulinotropic effects of an early-stage, small molecule GLP-1 receptor agonist and provide compelling evidence to support pharmaceutical optimization. PMID:20823098

  7. 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.

  8. 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.

  9. 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.

  10. Molecular Simulation-Based Structural Prediction of Protein Complexes in Mass Spectrometry: The Human Insulin Dimer

    PubMed Central

    Li, Jinyu; Rossetti, Giulia; Dreyer, Jens; Raugei, Simone; Ippoliti, Emiliano; Lüscher, Bernhard; Carloni, Paolo

    2014-01-01

    Protein electrospray ionization (ESI) mass spectrometry (MS)-based techniques are widely used to provide insight into structural proteomics under the assumption that non-covalent protein complexes being transferred into the gas phase preserve basically the same intermolecular interactions as in solution. Here we investigate the applicability of this assumption by extending our previous structural prediction protocol for single proteins in ESI-MS to protein complexes. We apply our protocol to the human insulin dimer (hIns2) as a test case. Our calculations reproduce the main charge and the collision cross section (CCS) measured in ESI-MS experiments. Molecular dynamics simulations for 0.075 ms show that the complex maximizes intermolecular non-bonded interactions relative to the structure in water, without affecting the cross section. The overall gas-phase structure of hIns2 does exhibit differences with the one in aqueous solution, not inferable from a comparison with calculated CCS. Hence, care should be exerted when interpreting ESI-MS proteomics data based solely on NMR and/or X-ray structural information. PMID:25210764

  11. Mechanisms underlying the onset of oral lipid-induced skeletal muscle insulin resistance in humans.

    PubMed

    Nowotny, Bettina; Zahiragic, Lejla; Krog, Dorothea; Nowotny, Peter J; Herder, Christian; Carstensen, Maren; Yoshimura, Toru; Szendroedi, Julia; Phielix, Esther; Schadewaldt, Peter; Schloot, Nanette C; Shulman, Gerald I; Roden, Michael

    2013-07-01

    Several mechanisms, such as innate immune responses via Toll-like receptor-4, accumulation of diacylglycerols (DAG)/ceramides, and activation of protein kinase C (PKC), are considered to underlie skeletal muscle insulin resistance. In this study, we examined initial events occurring during the onset of insulin resistance upon oral high-fat loading compared with lipid and low-dose endotoxin infusion. Sixteen lean insulin-sensitive volunteers received intravenous fat (iv fat), oral fat (po fat), intravenous endotoxin (lipopolysaccharide [LPS]), and intravenous glycerol as control. After 6 h, whole-body insulin sensitivity was reduced by iv fat, po fat, and LPS to 60, 67, and 48%, respectively (all P < 0.01), which was due to decreased nonoxidative glucose utilization, while hepatic insulin sensitivity was unaffected. Muscle PKCθ activation increased by 50% after iv and po fat, membrane Di-C18:2 DAG species doubled after iv fat and correlated with PKCθ activation after po fat, whereas ceramides were unchanged. Only after LPS, circulating inflammatory markers (tumor necrosis factor-α, interleukin-6, and interleukin-1 receptor antagonist), their mRNA expression in subcutaneous adipose tissue, and circulating cortisol were elevated. Po fat ingestion rapidly induces insulin resistance by reducing nonoxidative glucose disposal, which associates with PKCθ activation and a rise in distinct myocellular membrane DAG, while endotoxin-induced insulin resistance is exclusively associated with stimulation of inflammatory pathways.

  12. Ghrelin, a natural GH secretagogue produced by the stomach, induces hyperglycemia and reduces insulin secretion in humans.

    PubMed

    Broglio, F; Arvat, E; Benso, A; Gottero, C; Muccioli, G; Papotti, M; van der Lely, A J; Deghenghi, R; Ghigo, E

    2001-10-01

    Ghrelin, a 28 amino acid gastric hormone is a natural ligand of the GH Secretagogue (GHS) receptor (GHS-R) and strongly stimulates GH secretion though, like synthetic GHS, it shows other endocrine and non-endocrine activities. Aim of the present study was to clarify whether ghrelin administration influences insulin and glucose levels in humans. To this goal, we compared the effects of ghrelin, hexarelin, a synthetic GHS, or placebo on insulin and glucose as well as on GH levels in 11 normal young volunteers (age [mean +/- SEM]: 28.5 +/- 3.1 yr; BMI: 22.2 +/- 0.9 Kg/m(2)). Ghrelin induced very marked increase in GH secretion (DeltaAUC(0-180): 5777.1 +/- 812.6 microg/l/h; p < 0.01) which was not modified by placebo. Placebo administration did not modify insulin and glucose levels. On the other hand, ghrelin administration induced a prompt increase in glucose levels (DeltaAUC(0-180): 1343.1 +/- 443.5 mg/dl/h; p < 0.01 vs. saline). Absolute glucose levels at +15' were already higher than those at baseline (93.9 +/- 7.1 mg/dl; p < 0.01) and persisted elevated up to 165' (90.3 +/- 5.8 mg/dl; p < 0.01 vs. 0'). Ghrelin administration was also followed by a decrease in serum insulin levels (DeltaAUC(0-180): -207.1 +/- 70.5 mU/l/h; p < 0.05 vs. saline). Absolute insulin levels were significantly reduced from 30' (11.4 +/- 0.9 mU/l, p < 0.1 vs. 0'), showed the nadir at +45' (10.0 +/- 0.6 mU/l, p < 0.01 vs. 0') and then persisted lower (p < 0.01) than baseline up to +105'. Hexarelin administration did not modify glucose and insulin levels despite its marked GH-releasing effect (DeltaAUC(0-180): 4156.8 +/- 1180.3 microg/l/h; p < 0.01 vs. saline) that was slightly lower (p < 0.05) than that of ghrelin. In conclusion, these findings show that, besides stimulating GH secretion, ghrelin is a gastric hormone possessing metabolic actions such as hyperglycemic effect and lowering effect on insulin secretion in humans, at least after acute administration.

  13. Long-term exposure to abnormal glucose levels alters drug metabolism pathways and insulin sensitivity in primary human hepatocytes

    PubMed Central

    Davidson, Matthew D.; Ballinger, Kimberly R.; Khetani, Salman R.

    2016-01-01

    Hyperglycemia in type 2 diabetes mellitus has been linked to non-alcoholic fatty liver disease, which can progress to inflammation, fibrosis/cirrhosis, and hepatocellular carcinoma. Understanding how chronic hyperglycemia affects primary human hepatocytes (PHHs) can facilitate the development of therapeutics for these diseases. Conversely, elucidating the effects of hypoglycemia on PHHs may provide insights into how the liver adapts to fasting, adverse diabetes drug reactions, and cancer. In contrast to declining PHH monocultures, micropatterned co-cultures (MPCCs) of PHHs and 3T3-J2 murine embryonic fibroblasts maintain insulin-sensitive glucose metabolism for several weeks. Here, we exposed MPCCs to hypo-, normo- and hyperglycemic culture media for ~3 weeks. While albumin and urea secretion were not affected by glucose level, hypoglycemic MPCCs upregulated CYP3A4 enzyme activity as compared to other glycemic states. In contrast, hyperglycemic MPCCs displayed significant hepatic lipid accumulation in the presence of insulin, while also showing decreased sensitivity to insulin-mediated inhibition of glucose output relative to a normoglycemic control. In conclusion, we show for the first time that PHHs exposed to hypo- and hyperglycemia can remain highly functional, but display increased CYP3A4 activity and selective insulin resistance, respectively. In the future, MPCCs under glycemic states can aid in novel drug discovery and mechanistic investigations. PMID:27312339

  14. Long-term exposure to abnormal glucose levels alters drug metabolism pathways and insulin sensitivity in primary human hepatocytes

    NASA Astrophysics Data System (ADS)

    Davidson, Matthew D.; Ballinger, Kimberly R.; Khetani, Salman R.

    2016-06-01

    Hyperglycemia in type 2 diabetes mellitus has been linked to non-alcoholic fatty liver disease, which can progress to inflammation, fibrosis/cirrhosis, and hepatocellular carcinoma. Understanding how chronic hyperglycemia affects primary human hepatocytes (PHHs) can facilitate the development of therapeutics for these diseases. Conversely, elucidating the effects of hypoglycemia on PHHs may provide insights into how the liver adapts to fasting, adverse diabetes drug reactions, and cancer. In contrast to declining PHH monocultures, micropatterned co-cultures (MPCCs) of PHHs and 3T3-J2 murine embryonic fibroblasts maintain insulin-sensitive glucose metabolism for several weeks. Here, we exposed MPCCs to hypo-, normo- and hyperglycemic culture media for ~3 weeks. While albumin and urea secretion were not affected by glucose level, hypoglycemic MPCCs upregulated CYP3A4 enzyme activity as compared to other glycemic states. In contrast, hyperglycemic MPCCs displayed significant hepatic lipid accumulation in the presence of insulin, while also showing decreased sensitivity to insulin-mediated inhibition of glucose output relative to a normoglycemic control. In conclusion, we show for the first time that PHHs exposed to hypo- and hyperglycemia can remain highly functional, but display increased CYP3A4 activity and selective insulin resistance, respectively. In the future, MPCCs under glycemic states can aid in novel drug discovery and mechanistic investigations.

  15. Blood-based biomarkers of age-associated epigenetic changes in human islets associate with insulin secretion and diabetes

    PubMed Central

    Bacos, Karl; Gillberg, Linn; Volkov, Petr; Olsson, Anders H; Hansen, Torben; Pedersen, Oluf; Gjesing, Anette Prior; Eiberg, Hans; Tuomi, Tiinamaija; Almgren, Peter; Groop, Leif; Eliasson, Lena; Vaag, Allan; Dayeh, Tasnim; Ling, Charlotte

    2016-01-01

    Aging associates with impaired pancreatic islet function and increased type 2 diabetes (T2D) risk. Here we examine whether age-related epigenetic changes affect human islet function and if blood-based epigenetic biomarkers reflect these changes and associate with future T2D. We analyse DNA methylation genome-wide in islets from 87 non-diabetic donors, aged 26–74 years. Aging associates with increased DNA methylation of 241 sites. These sites cover loci previously associated with T2D, for example, KLF14. Blood-based epigenetic biomarkers reflect age-related methylation changes in 83 genes identified in human islets (for example, KLF14, FHL2, ZNF518B and FAM123C) and some associate with insulin secretion and T2D. DNA methylation correlates with islet expression of multiple genes, including FHL2, ZNF518B, GNPNAT1 and HLTF. Silencing these genes in β-cells alter insulin secretion. Together, we demonstrate that blood-based epigenetic biomarkers reflect age-related DNA methylation changes in human islets, and associate with insulin secretion in vivo and T2D. PMID:27029739

  16. Blood-based biomarkers of age-associated epigenetic changes in human islets associate with insulin secretion and diabetes.

    PubMed

    Bacos, Karl; Gillberg, Linn; Volkov, Petr; Olsson, Anders H; Hansen, Torben; Pedersen, Oluf; Gjesing, Anette Prior; Eiberg, Hans; Tuomi, Tiinamaija; Almgren, Peter; Groop, Leif; Eliasson, Lena; Vaag, Allan; Dayeh, Tasnim; Ling, Charlotte

    2016-03-31

    Aging associates with impaired pancreatic islet function and increased type 2 diabetes (T2D) risk. Here we examine whether age-related epigenetic changes affect human islet function and if blood-based epigenetic biomarkers reflect these changes and associate with future T2D. We analyse DNA methylation genome-wide in islets from 87 non-diabetic donors, aged 26-74 years. Aging associates with increased DNA methylation of 241 sites. These sites cover loci previously associated with T2D, for example, KLF14. Blood-based epigenetic biomarkers reflect age-related methylation changes in 83 genes identified in human islets (for example, KLF14, FHL2, ZNF518B and FAM123C) and some associate with insulin secretion and T2D. DNA methylation correlates with islet expression of multiple genes, including FHL2, ZNF518B, GNPNAT1 and HLTF. Silencing these genes in β-cells alter insulin secretion. Together, we demonstrate that blood-based epigenetic biomarkers reflect age-related DNA methylation changes in human islets, and associate with insulin secretion in vivo and T2D.

  17. Estrogens and Insulin-Like Growth Factor 1 Modulate Neoplastic Cell Growth in Human Cholangiocarcinoma

    PubMed Central

    Alvaro, Domenico; Barbaro, Barbara; Franchitto, Antonio; Onori, Paolo; Glaser, Shannon S.; Alpini, Gianfranco; Francis, Heather; Marucci, Luca; Sterpetti, Paola; Ginanni-Corradini, Stefano; Onetti Muda, Andrea; Dostal, David E.; De Santis, Adriano; Attili, Adolfo F.; Benedetti, Antonio; Gaudio, Eugenio

    2006-01-01

    We investigated the expression of estrogen receptors (ERs), insulin-like growth factor 1 (IGF-1), and IGF-1R (receptor) in human cholangiocarcinoma and cholangiocarcinoma cell lines (HuH-28, TFK-1, Mz-ChA-1), evaluating the role of estrogens and IGF-1 in the modulation of neoplastic cell growth. ER-α, ER-β, IGF-1, and IGF-1R were expressed (immunohistochemistry) in all biopsies (18 of 18) of intrahepatic cholangiocarcinoma. ER-α was expressed (Western blot) only by the HuH-28 cell line (intrahepatic cholangiocarcinoma), whereas ER-β, IGF-1, and IGF-1R were expressed in the three cell lines examined. In serum-deprived HuH-28 cells, serum readmission induced stimulation of cell proliferation that was inhibited by ER and IGF-1R antagonists. 17β-Estradiol and IGF-1 stimulated proliferation of HuH-28 cells to a similar extent to that of MCF7 (breast cancer) but greater than that of TFK-1 and Mz-ChA-1, inhibiting apoptosis and exerting additive effects. These effects of 17β-estradiol and IGF-1 were associated with enhanced protein expression of ER-α, phosphorylated (p)-ERK1/2 and pAKT but with decreased expression of ER-β. Finally, transfection of IGF-1R anti-sense oligonucleotides in HuH-28 cells markedly decreased cell proliferation. In conclusion, human intrahepatic cholangiocarcinomas express receptors for estrogens and IGF-1, which cooperate in the modulation of cell growth and apoptosis. Modulation of ER and IGF-1R could represent a strategy for the management of cholangiocarcinoma. PMID:16936263

  18. Insulin increases sodium reabsorption in diluting segment in humans: evidence for indirect mediation through hypokalemia.

    PubMed

    Friedberg, C E; van Buren, M; Bijlsma, J A; Koomans, H A

    1991-08-01

    To examine the mechanism of renal sodium (Na) and potassium (K) retention during insulin infusion, seven healthy volunteers underwent clearance studies without (time control) and with insulin infusion (40 mU bolus, followed by 1 mU/kg/min for 150 min). Maximal free water clearance and fractional lithium clearance (FELi) were used to analyze renal sodium handling. Insulin decreased Na excretion (from 189 +/- 25 to 121 +/- 19 mumol/min, P less than 0.01) and K excretion (from 64 +/- 8 to 19 +/- 1 mumol/min, P less than 0.01), but did not change in glomerular filtration rate. FELi increased from 29.8 +/- 1.9 to 32.3 +/- 1.9% (P less than 0.05), minimal urine osmolality decreased from 59 +/- 3 to 46 +/- 3 mOsm/kg (P less than 0.01), and the diluting segment reabsorption index increased from 88.0 +/- 0.9 to 93.7 +/- 0.9%, P less than 0.01). Insulin also decreased plasma K, from 3.91 +/- 0.08 to 3.28 +/- 0.08 mmol/liter, P less than 0.01. In a third clearance study KCl was infused simultaneously (3.75 mumol/kg/min) to prevent this fall in plasma K. In this study insulin had no effect on Na and K excretion and diluting segment reabsorption, but the rise in FELi remained. In a fourth clearance study NaCl (3.75 mumol/kg/min) instead of KCl was infused together with insulin. This maneuver did not prevent the Na and K retaining effect of insulin, nor any of its effects on renal sodium handling parameters. These data suggest that Na and K retention during insulin infusion are largely secondary to hypokalemia, which causes increased reabsorption in the diluting segment.

  19. Integrative genomic analysis implicates limited peripheral adipose storage capacity in the pathogenesis of human insulin resistance.

    PubMed

    Lotta, Luca A; Gulati, Pawan; Day, Felix R; Payne, Felicity; Ongen, Halit; van de Bunt, Martijn; Gaulton, Kyle J; Eicher, John D; Sharp, Stephen J; Luan, Jian'an; De Lucia Rolfe, Emanuella; Stewart, Isobel D; Wheeler, Eleanor; Willems, Sara M; Adams, Claire; Yaghootkar, Hanieh; Forouhi, Nita G; Khaw, Kay-Tee; Johnson, Andrew D; Semple, Robert K; Frayling, Timothy; Perry, John R B; Dermitzakis, Emmanouil; McCarthy, Mark I; Barroso, Inês; Wareham, Nicholas J; Savage, David B; Langenberg, Claudia; O'Rahilly, Stephen; Scott, Robert A

    2017-01-01

    Insulin resistance is a key mediator of obesity-related cardiometabolic disease, yet the mechanisms underlying this link remain obscure. Using an integrative genomic approach, we identify 53 genomic regions associated with insulin resistance phenotypes (higher fasting insulin levels adjusted for BMI, lower HDL cholesterol levels and higher triglyceride levels) and provide evidence that their link with higher cardiometabolic risk is underpinned by an association with lower adipose mass in peripheral compartments. Using these 53 loci, we show a polygenic contribution to familial partial lipodystrophy type 1, a severe form of insulin resistance, and highlight shared molecular mechanisms in common/mild and rare/severe insulin resistance. Population-level genetic analyses combined with experiments in cellular models implicate CCDC92, DNAH10 and L3MBTL3 as previously unrecognized molecules influencing adipocyte differentiation. Our findings support the notion that limited storage capacity of peripheral adipose tissue is an important etiological component in insulin-resistant cardiometabolic disease and highlight genes and mechanisms underpinning this link.

  20. Insulin-Producing Endocrine Cells Differentiated In Vitro From Human Embryonic Stem Cells Function in Macroencapsulation Devices In Vivo

    PubMed Central

    Ambruzs, Dana M.; Moorman, Mark A.; Bhoumik, Anindita; Cesario, Rosemary M.; Payne, Janice K.; Kelly, Jonathan R.; Haakmeester, Carl; Srijemac, Robert; Wilson, Alistair Z.; Kerr, Justin; Frazier, Mauro A.; Kroon, Evert J.; D’Amour, Kevin A.

    2015-01-01

    The PEC-01 cell population, differentiated from human embryonic stem cells (hESCs), contains pancreatic progenitors (PPs) that, when loaded into macroencapsulation devices (to produce the VC-01 candidate product) and transplanted into mice, can mature into glucose-responsive insulin-secreting cells and other pancreatic endocrine cells involved in glucose metabolism. We modified the protocol for making PEC-01 cells such that 73%–80% of the cell population consisted of PDX1-positive (PDX1+) and NKX6.1+ PPs. The PPs were further differentiated to islet-like cells (ICs) that reproducibly contained 73%–89% endocrine cells, of which approximately 40%–50% expressed insulin. A large fraction of these insulin-positive cells were single hormone-positive and expressed the transcription factors PDX1 and NKX6.1. To preclude a significant contribution of progenitors to the in vivo function of ICs, we used a simple enrichment process to remove remaining PPs, yielding aggregates that contained 93%–98% endocrine cells and 1%–3% progenitors. Enriched ICs, when encapsulated and implanted into mice, functioned similarly to the VC-01 candidate product, demonstrating conclusively that in vitro-produced hESC-derived insulin-producing cells can mature and function in vivo in devices. A scaled version of our suspension culture was used, and the endocrine aggregates could be cryopreserved and retain functionality. Although ICs expressed multiple important β cell genes, the cells contained relatively low levels of several maturity-associated markers. Correlating with this, the time to function of ICs was similar to PEC-01 cells, indicating that ICs required cell-autonomous maturation after delivery in vivo, which would occur concurrently with graft integration into the host. Significance Type 1 diabetes (T1D) affects approximately 1.25 million people in the U.S. alone and is deadly if not managed with insulin injections. This paper describes the production of insulin

  1. Production of functional human insulin-like growth factor binding proteins (IGFBPs) using recombinant expression in HEK293 cells.

    PubMed

    Wanscher, Anne Sofie Molsted; Williamson, Michael; Ebersole, Tasja Wainani; Streicher, Werner; Wikström, Mats; Cazzamali, Giuseppe

    2015-04-01

    Insulin-like growth factor binding proteins (IGFBPs) display many functions in humans including regulation of the insulin-like growth factor (IGF) signaling pathway. The various roles of human IGFBPs make them attractive protein candidates in drug discovery. Structural and functional knowledge on human proteins with therapeutic relevance is needed to design and process the next generation of protein therapeutics. In order to conduct structural and functional investigations large quantities of recombinant proteins are needed. However, finding a suitable recombinant production system for proteins such as full-length human IGFBPs, still remains a challenge. Here we present a mammalian HEK293 expression method suitable for over-expression of secretory full-length human IGFBP-1 to -7. Protein purification of full-length human IGFBP-1, -2, -3 and -5 was conducted using a two-step chromatography procedure and the final protein yields were between 1 and 12mg protein per liter culture media. The recombinant IGFBPs contained PTMs and exhibited high-affinity interactions with their natural ligands IGF-1 and IGF-2.

  2. Effect of sevoflurane on human hepatocellular carcinoma HepG2 cells under conditions of high glucose and insulin.

    PubMed

    Nishiwada, Tadashi; Kawaraguchi, Yoshitaka; Uemura, Keiko; Sugimoto, Hiroshi; Kawaguchi, Masahiko

    2015-10-01

    Diabetes mellitus is associated with morbidity and progression of some cancers, such as hepatocellular carcinoma. It has been reported that sevoflurane, a volatile anesthetic agent commonly used in cancer surgery, can lead to lower overall survival rates than those observed when propofol is used to treat cancer patients, and sevoflurane increases cancer cell proliferation in in vitro studies. It has been also reported that glucose levels in rats anesthetized with sevoflurane were higher than those in rats anesthetized with propofol. We investigated the effect of sevoflurane, under conditions of high glucose and insulin, on cell proliferation in the human hepatocellular carcinoma cell line, HepG2. First, we exposed HepG2 cells to sevoflurane at 1 or 2 % concentration for 6 h in various glucose concentrations and then evaluated cell proliferation using the MTT assay. Subsequently, to mimic diabetic conditions observed during surgery, HepG2 cells were exposed to sevoflurane at 1 or 2 % concentration in high glucose concentrations at various concentrations of insulin for 6 h. One-percent sevoflurane exposure enhanced cell proliferation under conditions of high glucose, treated with 0.05 mg/l insulin. Our study implies that sevoflurane may affect cell proliferation in human hepatocellular carcinoma cells in a physiological situation mimicking that of diabetes.

  3. Human circulating monocytes internalize 125I-insulin in a similar fashion to rat hepatocytes: relevance to receptor regulation in target and nontarget tissues.

    PubMed

    Grunberger, G; Robert, A; Carpentier, J L; Dayer, J M; Roth, A; Stevenson, H C; Orci, L; Gorden, P

    1985-08-01

    Circulating monocytes bind 125I-insulin in a specific fashion and have been used to analyze the ambient receptor status in humans. When freshly isolated circulating monocytes are incubated with 125I-insulin and examined by electron microscopic autoradiography, approximately 18% of the labeled material is internalized after 15 minutes at 37 degrees C. By 2 hours at 37 degrees C, approximately one half of the 125I-insulin is internalized. Internalization occurs also at 15 degrees C but at a slower rate. Furthermore, the monocytes bind and internalize 125I-insulin in a manner that mirrors that of major target tissues, such as rat hepatocytes. These data suggest that the insulin receptor of the circulating monocyte might be regulated by adsorptive endocytosis in a manner analogous to that of target tissue, such as the liver.

  4. N-linked glycans of the human insulin receptor and their distribution over the crystal structure.

    PubMed

    Sparrow, Lindsay G; Lawrence, Michael C; Gorman, Jeffrey J; Strike, Phillip M; Robinson, Christine P; McKern, Neil M; Ward, Colin W

    2008-04-01

    The human insulin receptor (IR) homodimer is heavily glycosylated and contains a total of 19 predicted N-linked glycosylation sites in each monomer. The recent crystal structure of the IR ectodomain shows electron density consistent with N-linked glycosylation at the majority of sites present in the construct. Here, we describe a refined structure of the IR ectodomain that incorporates all of the N-linked glycans and reveals the extent to which the attached glycans mask the surface of the IR dimer from interaction with antibodies or other potential therapeutic binding proteins. The usefulness of Fab complexation in the crystallization of heavily glycosylated proteins is also discussed. The compositions of the glycans on IR expressed in CHO-K1 cells and the glycosylation deficient Lec8 cell line were determined by protease digestion, glycopeptide purification, amino acid sequence analysis, and mass spectrometry. Collectively the data reveal: multiple species of complex glycan at residues 25, 255, 295, 418, 606, 624, 742, 755, and 893 (IR-B numbering); multiple species of high-mannose glycan at residues 111 and 514; a single species of complex glycan at residue 671; and a single species of high-mannose glycan at residue 215. Residue 16 exhibited a mixture of complex, hybrid, and high-mannose glycan species. Of the remaining five predicted N-linked sites, those at residues 397 and 906 were confirmed by amino acid sequencing to be glycosylated, while that at residue 78 and the atypical (NKC) site at residue 282 were not glycosylated. The peptide containing the final site at residue 337 was not recovered but is seen to be glycosylated in the electron density maps of the IR ectodomain. The model of the fully glycosylated IR reveals that the sites carrying high-mannose glycans lie at positions of relatively low steric accessibility.

  5. Human testicular insulin-like factor 3: in relation to development, reproductive hormones and andrological disorders.

    PubMed

    Bay, K; Andersson, A-M

    2011-04-01

    Knockout of the gene encoding insulin-like factor 3 (INSL3) results in cryptorchidism in mice due to disruption of the transabdominal phase of testicular descent. This finding was essential for understanding the complete course of testis descensus, and wound up years of speculations regarding the endocrine regulation of this process. INSL3 is, along with testosterone, a major secretory product of testicular Leydig cells. In addition to its crucial function in testicular descent, INSL3 is suggested to play a paracrine role in germ cell survival and an endocrine role in bone metabolism. INSL3 is produced in human prenatal and neonatal, and in adult Leydig cells to various extents, and is in a developmental context regulated like testosterone, with production during second trimester, an early postnatal peak and increasing secretion during puberty, resulting in high adult serum levels. INSL3 production is entirely dependent on the state of Leydig cell differentiation, and is stimulated by the long-term trophic effects mediated by luteinizing hormone (LH). Once differentiated, Leydig cells apparently express INSL3 in a constitutive manner, and the hormone is thereby insensitive to the acute, steroidogenic effects of LH, which for example is an important factor in the regulation of testosterone. Clinically, serum INSL3 levels can turn out to be a usable tool to monitor basal Leydig cell function in patients with various disorders affecting Leydig cell function. According to animal studies, foetal INSL3 production is, directly or indirectly, sensitive to oestrogenic or anti-androgenic compounds. This provides important insight into the mechanism by which maternal exposure to endocrine disrupters can result in cryptorchidism in the next generation. Conclusively, INSL3 is an interesting testicular hormone with potential clinical value as a marker for Leydig cell function. It should be considered on a par with testosterone in the evaluation of testicular function and the

  6. The Ups and Downs of Insulin Resistance and Type 2 Diabetes: Lessons from Genomic Analyses in Humans

    PubMed Central

    Sales, Vicencia; Patti, Mary-Elizabeth

    2012-01-01

    We are in the midst of a worldwide epidemic of type 2 diabetes (T2D) and obesity. Understanding the mechanisms underlying these diseases is critical if we are to halt their progression and ultimately prevent their development. The advent and widespread implementation of microarray technology has allowed analysis of small samples of human skeletal muscle, adipose, liver, pancreas and blood. While patterns differ in each tissue, several dominant themes have emerged from these studies, including altered expression of genes indicating increased inflammation and altered lipid and mitochondrial oxidative metabolism and insulin signaling in patients with T2D, and in some cases, in those at risk for disease. Unraveling which changes in gene expression are primary, and which are secondary to an insulin resistant or diabetes metabolic milieu remains a scientific challenge but we are one step closer. PMID:23459395

  7. Enterovirus infection of human islets of Langerhans affects β-cell function resulting in disintegrated islets, decreased glucose stimulated insulin secretion and loss of Golgi structure

    PubMed Central

    Hodik, M; Skog, O; Lukinius, A; Isaza-Correa, J M; Kuipers, J; Giepmans, B N G; Frisk, G

    2016-01-01

    Aims/hypothesis In type 1 diabetes (T1D), most insulin-producing β cells are destroyed, but the trigger is unknown. One of the possible triggers is a virus infection and the aim of this study was to test if enterovirus infection affects glucose stimulated insulin secretion and the effect of virus replication on cellular macromolecules and organelles involved in insulin secretion. Methods Isolated human islets were infected with different strains of coxsackievirus B (CVB) virus and the glucose-stimulated insulin release (GSIS) was measured in a dynamic perifusion system. Classical morphological electron microscopy, large-scale electron microscopy, so-called nanotomy, and immunohistochemistry were used to study to what extent virus-infected β cells contained insulin, and real-time PCR was used to analyze virus induced changes of islet specific genes. Results In islets infected with CVB, GSIS was reduced in correlation with the degree of virus-induced islet disintegration. The expression of the gene encoding insulin was decreased in infected islets, whereas the expression of glucagon was not affected. Also, in islets that were somewhat disintegrated, there were uninfected β cells. Ultrastructural analysis revealed that virus particles and virus replication complexes were only present in β cells. There was a significant number of insulin granules remaining in the virus-infected β cells, despite decreased expression of insulin mRNA. In addition, no typical Golgi apparatus was detected in these cells. Exposure of islets to synthetic dsRNA potentiated glucose-stimulated insulin secretion. Conclusions/interpretation Glucose-stimulated insulin secretion; organelles involved in insulin secretion and gene expression were all affected by CVB replication in β cells. PMID:27547409

  8. Insulin fails to enhance mTOR phosphorylation, mitochondrial protein synthesis, and ATP production in human skeletal muscle without amino acid replacement.

    PubMed

    Barazzoni, Rocco; Short, Kevin R; Asmann, Yan; Coenen-Schimke, Jill M; Robinson, Matthew M; Nair, K Sreekumaran

    2012-11-01

    Systemic insulin administration causes hypoaminoacidemia by inhibiting protein degradation, which may in turn inhibit muscle protein synthesis (PS). Insulin enhances muscle mitochondrial PS and ATP production when hypoaminoacidemia is prevented by exogenous amino acid (AA) replacement. We determined whether insulin would stimulate mitochondrial PS and ATP production in the absence of AA replacement. Using l-[1,2-¹³C]leucine as a tracer, we measured the fractional synthetic rate of mitochondrial as well as sarcoplasmic and mixed muscle proteins in 18 participants during sustained (7-h) insulin or saline infusion (n = 9 each). We also measured muscle ATP production, mitochondrial enzyme activities, mRNA levels of mitochondrial genes, and phosphorylation of signaling proteins regulating protein synthesis. The concentration of circulating essential AA decreased during insulin infusion. Mitochondrial, sarcoplasmic, and mixed muscle PS rates were also lower during insulin (2-7 h) than during saline infusions despite increased mRNA levels of selected mitochondrial genes. Under these conditions, insulin did not alter mitochondrial enzyme activities and ATP production. These effects were associated with enhanced phosphorylation of Akt but not of protein synthesis activators mTOR, p70(S6K), and 4EBP1. In conclusion, sustained physiological hyperinsulinemia without AA replacement did not stimulate PS of mixed muscle or protein subfractions and did not alter muscle mitochondrial ATP production in healthy humans. These results support that insulin and AA act in conjunction to stimulate muscle mitochondrial function and mitochondrial protein synthesis.

  9. PDF Modeling of Turbulent Lean Premixed Combustion

    SciTech Connect

    Yilmaz, S.L.; •Givi, P.; Strakey, P.A.

    2007-10-01

    The joint velocity-scalar-frequency probability density function (PDF) methodology is employed for prediction of a bluff-body stabilized lean premixed methane-air flame. A reduced mechanism with CO and NO chemistry is used to describe fuel oxidation. The predicted mean and rms values of the velocity, temperature and concentrations of major and minor species are compared with laboratory measurements. This technical effort was performed in support of the National Energy Technology Laboratory’s on-going research in “Assessment of Turbo-Chemistry Models for Gas Turbine Combustion Emissions” under the RDS contract DE-AC26-04NT41817.

  10. Albert Renold Memorial Lecture: Molecular Background of Nutritionally Induced Insulin Resistance Leading to Type 2 Diabetes – From Animal Models to Humans

    PubMed Central

    Shafrir, Eleazar

    2001-01-01

    Albert Renold strived to gain insight into the abnormalities of human diabetes by defining the pathophysiology of the disease peculiar to a given animal. He investigated the Israeli desert-derived spiny mice (Acomys cahirinus), which became obese on fat-rich seed diet. After a few months hyperplasia and hypertrophy of β-cells occurred leading to a sudden rupture, insulin loss and ketosis. Spiny mice were low insulin responders, which is probably a characteristic of certain desert animals, protecting against insulin oversecretion when placed on an abundant diet. We have compared the response to overstimulation of several mutant diabetic species and nutritionally induced nonmutant animals when placed on affluent diet. Some endowed with resilient β-cells sustain long-lasting oversecretion, compensating for the insulin resistance, without lapsing into overt diabetes. Some with labile beta cells exhibit apoptosis and lose their capacity of coping with insulin resistance after a relatively short period. The wide spectrum of response to insulin resistance among different diabetes prone species seems to represent the varying response of human beta cells among the populations. In search for the molecular background of insulin resistance resulting from overnutrition we have studied the Israeli desert gerbil Psammomys obesus (sand rat), which progresses through hyperinsulinemia, followed by hyperglycemia and irreversible beta cell loss. Insulin resistance was found to be the outcome of reduced activation of muscle insulin receptor tyrosine kinase by insulin, in association with diminished GLUT4 protein and DNA content and overexpression of PKC isoenzymes, notably of PKCε. This overexpression and translocation to the membrane was discernible even prior to hyperinsulinemia and may reflect the propensity to diabetes in nondiabetic species and represent a marker for preventive action. By promoting the phosphorylation of serine/threonine residues on certain proteins of the

  11. Pancreas transplantation for treatment of generalized allergy to human insulin in type 1 diabetes.

    PubMed

    Malaise, J; Leonet, J; Goffin, E; Lefebvre, C; Tennstedt, D; Vandeleene, B; Buysschaert, M; Squifflet, J P

    2005-01-01

    We report the case of a 29-year-old man with a 14-year history of type 1 diabetes, normal renal function, and mild diabetic retinopathy. The patient progressively developed a generalized allergic reaction to two insulin excipients--protamine and metacresol--with systemic manifestations of tremor, tachycardia, vertigo, shortness of breath, and short episodes of unconsciousness causing him to be out of work. In June 2003, he received a vascularized cadaveric pancreas transplant using induction with polyclonal antibodies along with tacrolimus and sirolimus but without steroids. A hyperglycemic episode following corticosteroid therapy for rejection treatment required reintroduction of insulin therapy with prompt reappearance of allergic manifestations. Now, the patient is euglycemic without insulin or allergic manifestations and a glycated hemoglobin of 6.4%.

  12. Liposomal insulin promoter-thymidine kinase gene therapy followed by ganciclovir effectively ablates human pancreatic cancer in mice.

    PubMed

    Wu, James X; Liu, Shi-He; Nemunaitis, John J; Brunicardi, F Charles

    2015-04-10

    PDX1 is overexpressed in pancreatic cancer, and activates the insulin promoter (IP). Adenoviral IP-thymidine kinase and ganciclovir (TK/GCV) suppresses human pancreatic ductal carcinoma (PDAC) in mice, but repeated doses carry significant toxicity. We hypothesized that multiple cycles of liposomal IP-TK/GCV ablate human PDAC in SCID mice with minimal toxicity compared to adenoviral IP-TK/GCV. SCID mice with intraperitoneal human pancreatic cancer PANC-1 tumor implants were given a single cycle of 35 µg iv L-IP-TK, or four cycles of 1, 10, 20, 30, or 35 µg iv L-IP-TK (n = 20 per group), followed by intraperitoneal GCV. Insulin and glucose levels were monitored in mice treated with four cycles of 35 µg iv L-IP-TK. We found that four cycles of 10-35 µg L-IP-TK/GCV ablated more PANC-1 tumor volume compared to a single cycle with 35 µg. Mice that received four cycles of 10 µg L-IP-TK demonstrated the longest survival (P < 0.05), with a median survival of 126 days. In comparison, mice that received a single cycle of 35 µg L-IP-TK/GCV or GCV alone survived a median of 92 days and 68.7 days, respectively. There were no significant changes in glucose or insulin levels following treatment. In conclusion, multiple cycles of liposomal IP-TK/GCV ablate human PDAC in SCID mice with minimal toxicity, suggesting non-viral vectors are superior to adenoviral vectors for IP-gene therapy.

  13. Vasodilator effects of L-arginine are stereospecific and augmented by insulin in humans.

    PubMed

    Dallinger, Susanne; Sieder, Anna; Strametz, Jeanette; Bayerle-Eder, Michaela; Wolzt, Michael; Schmetterer, Leopold

    2003-06-01

    The amino acid l-arginine, the precursor of nitric oxide (NO) synthesis, induces vasodilation in vivo, but the mechanism behind this effect is unclear. There is, however, some evidence to assume that the l-arginine membrane transport capacity is dependent on insulin plasma levels. We hypothesized that vasodilator effects of l-arginine may be dependent on insulin plasma levels. Accordingly, we performed two randomized, double-blind crossover studies in healthy male subjects. In protocol 1 (n = 15), subjects received an infusion of insulin (6 mU x kg(-1) x min(-1) for 120 min) or placebo and, during the last 30 min, l-arginine or d-arginine (1 g/min for 30 min) x In protocol 2 (n = 8), subjects received l-arginine in stepwise increasing doses in the presence (1.5 mU x kg(-1) x min(-1)) or absence of insulin. Renal plasma flow and glomerular filtration rate were assessed by the para-aminohippurate and inulin plasma clearance methods, respectively. Pulsatile choroidal blood flow was assessed with laser interferometric measurement of fundus pulsation, and mean flow velocity in the ophthalmic artery was measured with Doppler sonography. l-arginine, but not d-arginine, significantly increased renal and ocular hemodynamic parameters. Coinfusion of l-arginine with insulin caused a dose-dependent leftward shift of the vasodilator effect of l-arginine. This stereospecific renal and ocular vasodilator potency of l-arginine is enhanced by insulin, which may result from facilitated l-arginine membrane transport, enhanced intracellular NO formation, or increased NO bioavailability.

  14. Insulin Basics

    MedlinePlus

    ... long insulin continues to lower blood glucose. Insulin Strength All insulins come dissolved or suspended in liquids. The standard and most commonly used strength in the United States today is U-100, ...

  15. Cell motility in models of wounded human skin is improved by Gap27 despite raised glucose, insulin and IGFBP-5.

    PubMed

    Wright, Catherine S; Berends, Rebecca F; Flint, David J; Martin, Patricia E M

    2013-02-15

    Reducing Cx43 expression stimulates skin wound healing. This is mimicked in models when Cx43 function is blocked by the connexin mimetic peptide Gap27. IGF-I also stimulates wound healing with IGFBP-5 attenuating its actions. Further, the IGF-I to IGFBP-5 ratio is altered in diabetic skin, where wound closure is impaired. We investigated whether Gap27 remains effective in augmenting scrape-wound closure in human skin wound models simulating diabetes-induced changes, using culture conditions with raised glucose, insulin and IGFBP-5. Gap27 increased scrape-wound closure in normal glucose and insulin (NGI) and to a lesser extent in high glucose and insulin (HGI). IGF-I enhanced scrape-wound closure in keratinocytes whereas IGFBP-5 inhibited this response. Gap27 overcame the inhibitory effects of IGFBP-5 on IGF-I activity. Connexin-mediated communication (CMC) was reduced in HGI, despite raised Cx43, and Gap27 significantly decreased CMC in NGI and HGI. IGF-I and IGFBP-5 did not affect CMC. IGF-I increased keratinocyte proliferation in NGI, and Gap27 increased proliferation in NGI to a greater extent than in HGI. We conclude that IGF-I and Gap27 stimulate scrape-wound closure by independent mechanisms with Gap27 inhibiting Cx43 function. Gap27 can enhance wound closure in diabetic conditions, irrespective of the IGF-I:IGFBP-5 balance.

  16. Human Monoclonal Antibody Fragments Binding to Insulin-like Growth Factors 1 and 2 with Picomolar Affinity

    PubMed Central

    Zhao, Qi; Feng, Yang; Zhu, Zhongyu; Dimitrov, Dimiter S.

    2011-01-01

    The type 1 insulin-like growth factor receptor (IGF1R) and its ligands (IGF1 and IGF2) have been implicated in a variety of physiological processes and in diseases such as cancer. In addition to IGF1R, IGF2 also activates the insulin receptor (IR) isoform A and therefore antibodies against IGF2 can inhibit cell proliferation mediated by the signaling through both IGF1R and IR triggered by IGF2. We identified a new human monoclonal antibody (mAb), m708.2, which bound to IGF1 and IGF2 but not to insulin. m708.2 potently inhibited signal transduction mediated by the interaction of IGF1 or IGF2 with the IGF1R and IGF2 with the IR. It also inhibited the growth of the breast cancer cell line MCF-7. An affinity-matured derivative of m708.2, m708.5, bound to IGF1 with equilibrium dissociation constant, KD = 200 pM and to IGF2 with KD = 60 pM. m708.5 inhibited signal transduction mediated by IGF1 and IGF2 and cancer cell growth more potently than m708.2. These results suggest that m708.5 could have potential as a candidate therapeutic for cancers driven by the IGF1,2 interactions with IGF1R and IR. PMID:21750218

  17. Expression of human uncoupling protein-3 in Drosophila insulin-producing cells increases insulin-like peptide (DILP) levels and shortens lifespan.

    PubMed

    Humphrey, Dickon M; Toivonen, Janne M; Giannakou, Maria; Partridge, Linda; Brand, Martin D

    2009-05-01

    Uncoupling proteins (UCPs) can dissipate mitochondrial protonmotive force by increasing the proton conductance of the inner membrane and through this effect could decrease ROS production, ameliorate oxidative stress and extend lifespan. We investigated whether ubiquitous, pan-neuronal or neurosecretory cell-specific expression of human UCP3 (hUCP3) in adult Drosophila melanogaster affected lifespan. Low, ubiquitous expression of hUCP3 at levels found in rodent skeletal muscle mitochondria did not affect proton conductance in mitochondria isolated from whole flies, but high pan-neuronal expression of hUCP3 increased the proton conductance of mitochondria isolated from fly heads. Expression of hUCP3 at moderate levels in adult neurons led to a marginal lifespan-extension in males. However, high expression of hUCP3 in neuronal tissue shortened lifespan. The life-shortening effect was replicated when hUCP3 was expressed specifically in median neurosecretory cells (mNSC), which express three of the Drosophila insulin-like peptides (DILPs). Expression of hUCP3 in the mNSC did not alter expression of dilp2, dilp3 or dilp5 mRNA, but led to increased amounts of DILP2 in fly heads. These data suggest that lowering mitochondrial coupling by high expression of hUCP3 alters mNSC function in a way that appears to increase DILP-levels in fly heads and lead to a concomitant decrease in lifespan.

  18. African plant foods rich in non-starch polysaccharides reduce postprandial blood glucose and insulin concentrations in healthy human subjects.

    PubMed

    Onyechi, U A; Judd, P A; Ellis, P R

    1998-11-01

    The effects of two vegetable flours, prepared from the African plants Detarium senegalense Gmelin, a legume, and Cissus rotundifolia, a shrub, on postprandial blood glucose and insulin concentrations in human subjects, were investigated. Chemical analysis indicated that these flours contained significant amounts of NSP. The detarium in particular was found to be a rich source of water-soluble NSP (SNSP). The flours were incorporated into two types of breakfast meal, a stew meal and a wheat bread meal, containing 50 g and 70 g available carbohydrate respectively. Both meals also contained 10-12 g NSP, the major fraction of which was SNSP. Control and fibre-rich meals were consumed on separate days in randomized order by two different groups of subjects (n 5, stew meals; n 10, bread meals). Venous blood samples were taken at fasting (0 min) and postprandially at 30 min intervals for 2.5 h and the plasma analysed for glucose and insulin. Compared with the controls, detarium and cissus meals elicited significant reductions (P < 0.006) in plasma glucose levels at most postprandial time points and for area-under-the-curve (AUC) values (AUC reductions 38-62%). Significant reductions (P < 0.002) in plasma insulin levels at various postprandial time points and for AUC values were also seen after detarium and cissus breads (AUC reductions 43 and 36% respectively), but not after the fibre-rich stew meals. SNSP and starch are possibly the main, but not the only, components responsible for the glucose- and insulin-lowering effects of cissus flour. The main SNSP fraction of detarium, identified as a high-molecular-weight xyloglucan, is likely to be a primary factor in determining the physiological activity of detarium flour.

  19. Human glycated albumin affects glucose metabolism in L6 skeletal muscle cells by impairing insulin-induced insulin receptor substrate (IRS) signaling through a protein kinase C alpha-mediated mechanism.

    PubMed

    Miele, Claudia; Riboulet, Audrey; Maitan, Maria Alessandra; Oriente, Francesco; Romano, Chiara; Formisano, Pietro; Giudicelli, Jean; Beguinot, Francesco; Van Obberghen, Emmanuel

    2003-11-28

    Nonenzymatic glycation is increased in diabetes and leads to increased levels of glycated proteins. Most studies have focused on the role of glycation products in vascular complications. Here, we have investigated the action of human glycated albumin (HGA) on insulin signaling in L6 skeletal muscle cells. Exposure of these cells to HGA inhibited insulin-stimulated glucose uptake and glycogen synthase activity by 95 and 80%, respectively. These effects were time- and dose-dependent, reaching a maximum after 12 h incubation with 0.1 mg/ml HGA. In contrast, exposure of the cells to HGA had no effect on thymidine incorporation. Further, HGA reduced insulin-stimulated serine phosphorylation of PKB and GSK3, but did not alter ERK1/2 activation. HGA did not affect either insulin receptor kinase activity or insulin-induced Shc phosphorylation on tyrosine. In contrast, insulin-dependent IRS-1 and IRS-2 tyrosine phosphorylation was severely reduced in cells preincubated with HGA for 24 h. Insulin-stimulated association of PI3K with IRS-1 and IRS-2, and PI3K activity were reduced by HGA in parallel with the changes in IRS tyrosine phosphorylation, while Grb2-IRS association was unchanged. In L6 myotubes, exposure to HGA increased PKC activity by 2-fold resulting in a similar increase in Ser/Thr phosphorylation of IRS-1 and IRS-2. These phosphorylations were blocked by the PKC inhibitor bisindolylmaleimide (BDM). BDM also blocked the action of HGA on insulin-stimulated PKB and GSK3 alpha. Simultaneously, BDM rescued insulin-stimulation of glucose uptake and glycogen synthase activity in cells exposed to HGA. The use of antibodies specific to PKC isoforms shows that this effect appears to be mediated by activated PKC alpha, independent of reactive oxygen species production. In summary, in L6 skeletal muscle cells, exposure to HGA leads to insulin resistance selectively in glucose metabolism with no effect on growth-related pathways regulated by the hormone.

  20. Preparation of feed premix for veterinary purposes.

    PubMed

    Franc, Aleš; Lehocký, Róbert; Muselík, Jan; Vetchý, David; Dobšíková, Radka; Modrá, Helena

    2014-10-01

    This experimental study describes the preparation of a veterinary medicated premix containing tetracycline hydrochloride for oral administration to aquatic animals. For the manufacture of the premix, commercially produced animal feed is used, which is intended for consumption in the form of pellets that were coated with a mixture of chlortetracycline hydrochloride and other excipients. Feed pellets were combined with a mixture of an active substance and excipients with a large specific surface (colloidal silica - Aerosil® 200) allowing an easy adhesion to the surface of the pellets, and a solid polymer with a low glass transition point (Eudragit® E) which ensures the formation of a hard coat. A mixture of these substances has been applied to the surface of the pellets either A) in the solid state simply by dry adhesion; B) by coating the pellets with the mixture and additional impregnation with ethanol; or C) the polymer was subsequently applied in solution. In the final stage, the pellets were heated in order to achieve the glass transition point of the polymer to create a solid and mechanically resistant coating. Coated pellets prepared by three methods described above are almost identical in their physical properties. With this technology it is possible to produce a feed mixture with a very low content of the active substance in situ without the need for a complex technological equipment.

  1. Multiscale Interactions and Backscatter in Premixed Combustion

    NASA Astrophysics Data System (ADS)

    Hamlington, Peter; Towery, Colin; O'Brien, Jeffrey; Poludnenko, Alexei; Urzay, Javier; Ihme, Matthias

    2015-11-01

    Multiscale interactions and energy transfer between turbulence and flames are fundamental to understanding and modeling premixed turbulent reacting flows. To investigate such flows, direct numerical simulations of statistically planar turbulent premixed flames have been performed, and the dynamics of kinetic energy transfer are examined in both spectral and physical spaces. In the spectral analysis, two-dimensional kinetic energy spectra and triadic interactions are computed through the flame brush. It is found that there is suppression of turbulent small-scale motions in the combustion products, along with backscatter of energy for a range of scales near the thermal laminar flame width. In the physical-space analysis, a differential filter is applied to examine the transfer of kinetic energy between subgrid and resolved scales in the context of large eddy simulations. Subgrid-scale backscatter of kinetic energy driven by combustion is found to prevail over forward scatter throughout the flame brush. The spectral- and physical-space analyses thus both suggest an enhancement of reverse-cascade phenomena in the flame brush, which is possibly driven by accumulation of kinetic energy in the scales where combustion-induced heat release is preferentially deployed.

  2. A model for premixed combustion oscillations

    SciTech Connect

    Janus, M.C.; Richards, G.A.

    1996-03-01

    Combustion oscillations are receiving renewed research interest due to increasing application of lean premix (LPM) combustion to gas turbines. A simple, nonlinear model for premixed combustion is described; it was developed to explain experimental results and to provide guidance for developing active control schemes based on nonlinear concepts. The model can be used to quickly examine instability trends associated with changes in equivalence ratio, mass flow rate, geometry, ambient conditions, etc. The model represents the relevant processes occurring in a fuel nozzle and combustor analogous to current LPM turbine combustors. Conservation equations for the nozzle and combustor are developed from simple control volume analysis, providing ordinary differential equations that can be solved on a PC. Combustion is modeled as a stirred reactor, with bimolecular reaction between fuel and air. Although focus is on the model, it and experimental results are compared to understand effects of inlet air temperature and open loop control schemes. The model shows that both are related to changes in transport time.

  3. Internal structure of a premixed turbulent flame

    SciTech Connect

    Rajan, S.; Smith, J.R.; Rambach, G.D.

    1982-10-01

    A pulsed laser and a multielement detector have been used to make instantaneous Rayleigh profiles along a line through a turbulent flame front thus eliminating the effects of flame front motion. The flame front in a premixed turbulent flame moves randomly about a mean position, giving rise to the visually observed flame brush or time-averaged flame thickness which is larger than the instantaneous thickness of the reaction zone. The physical characteristics and statistical properties of such turbulent flames reported previously were deduced from the time histories of Rayleigh scattered laser light at one or two points within the reaction zone. The study was conducted on a premixed propane-air flame stabilized on a rod at the exit plane of a square burner. Turbulence-producing screens below the burner exit controlled turbulent length scales while intensity was controlled with inlet mixture velocity. Turbulence properties of the cold reactants were determined by hot-wire anemometry. Mean and fluctuating velocity in the unburnt and burnt gases were measured using laser Doppler velocimetry. At the low level of turbulence studied, the instantaneous flame front thickness was found to be only slightly greater than the laminar flame thickness, and the magnitude of the density fluctuations only slightly greater than the cold flow turbulence intensity. Mean and rms values of density and velocity; density and velocity probability density functions; spatial density correlations; and comparison of data with the Bray-Moss-Libby model are presented.

  4. Insulin therapy in the elderly with type 2 diabetes.

    PubMed

    Eriksson, J G; Laine, M K

    2015-12-01

    Type 2 diabetes (T2D) is a progressive disorder and therefore many elderly people with T2D will require insulin therapy in order to reach treatment targets and to optimize quality of life. It is commonly assumed that insulin is underutilized in elderly T2 diabetics because of fear that it is too complicated to use. With the use of long-acting insulin analogues it has become much easier to use insulin in elderly patients as once daily pen injections. When basal insulin treatment is initiated in T2D it is often added to the oral medication. The use of basal insulin analogues (e.g. detemir and glargine) with relatively little peaking effects has made insulin therapy in elderly subjects a relatively straightforward process. Newer insulin analogues are also discussed. The use of prandial insulin in addition to basal insulin and use of premixed insulin analogues is also discussed and illustrated with patient cases. Avoidance of hypoglycemia is an important factor to consider when choosing therapeutic agents for elderly T2D diabetics. This is certainly also true when establishing glycemic goals. Therefore insulin must be used with caution and wisely and the motto "start low and go slow" is a good principle. Basal insulin therapy in combination with oral drugs, most often metformin ‑ is the most convenient initial regimen. However, all next steps, from one to two or even more daily injections in elderly T2D subjects should be considered carefully.

  5. Insulin, catecholamines, glucose and antioxidant enzymes in oxidative damage during different loads in healthy humans.

    PubMed

    Koska, J; Blazícek, P; Marko, M; Grna, J D; Kvetnanský, R; Vigas, M

    2000-01-01

    Exercise, insulin-induced hypoglycemia and oral glucose loads (50 g and 100 g) were used to compare the production of malondialdehyde and the activity of antioxidant enzymes in healthy subjects. Twenty male volunteers participated in the study. Exercise consisted of three consecutive work loads on a bicycle ergometer of graded intensity (1.5, 2.0, and 2.5 W/kg, 6 min each). Hypoglycemia was induced by insulin (Actrapid MC Novo, 0.1 IU/kg, i.v.). Oral administration of 50 g and 100 g of glucose was given to elevate plasma glucose. The activity of superoxide dismutase (SOD) was determined in red blood cells, whereas glutathione peroxidase (GSH-Px) activity was measured in whole blood. The concentration of malondialdehyde (MDA) was determined by HPLC, catecholamines were assessed radioenzymatically and glucose was measured by the glucose-oxidase method. Exercise increased MDA concentrations, GSH-Px and SOD activities as well as plasma noradrenaline and adrenaline levels. Insulin hypoglycemia increased plasma adrenaline levels, but the concentrations of MDA and the activities of GSH-Px and SOD were decreased. Hyperglycemia increased plasma MDA concentrations, but the activities of GSH-Px and SOD were significantly higher after a larger dose of glucose only. Plasma catecholamines were unchanged. These results indicate that the transient increase of plasma catecholamine and insulin concentrations did not induce oxidative damage, while glucose already in the low dose was an important triggering factor for oxidative stress.

  6. Serum sphingolipids: relationships to insulin sensitivity and changes with exercise in humans.

    PubMed

    Bergman, Bryan C; Brozinick, Joseph T; Strauss, Allison; Bacon, Samantha; Kerege, Anna; Bui, Hai Hoang; Sanders, Phil; Siddall, Parker; Kuo, Ming Shang; Perreault, Leigh

    2015-08-15

    Ceramides and sphingolipids are a family of lipid molecules that circulate in serum and accumulate in skeletal muscle, promoting insulin resistance. Plasma ceramide and dihydroceramide are related to insulin resistance, yet less is known regarding other ceramide and sphingolipid species. Despite its association with insulin sensitivity, chronic endurance exercise training does not change plasma ceramide and sphingolipid content, with little known regarding a single bout of exercise. We measured basal relationships and the effect of acute exercise (1.5 h at 50% V̇o2 max) and recovery on serum ceramide and sphingolipid content in sedentary obese individuals, endurance-trained athletes, and individuals with type 2 diabetes (T2D). Basal serum C18:0, C20:0, and C24:1 ceramide and C18:0 and total dihydroceramide were significantly higher in T2D and, along with C16:0 ceramide and C18:0 sphingomyelin, correlated positively with insulin resistance. Acute exercise significantly increased serum ceramide, glucosylceramide, and GM3 gangliosides, which largely decreased to basal values in recovery. Sphingosine 1-phosphate and sphingomyelin did not change during exercise but decreased below basal values in recovery. Serum C16:0 and C18:0 ceramide and C18:0 sphingomyelin, but not the total concentrations of either of them, were positively correlated with markers of muscle NF-κB activation, suggesting that specific species activate intracellular inflammation. Interestingly, a subset of sphingomyelin species, notably C14:0, C22:3, and C24:4 species, was positively associated with insulin secretion and glucose tolerance. Together, these data show that unique ceramide and sphingolipid species associate with either protective or deleterious features for diabetes and could provide novel therapeutic targets for the future.

  7. Sensorineural hearing loss in insulin-like growth factor I-null mice: a new model of human deafness.

    PubMed

    Cediel, R; Riquelme, R; Contreras, J; Díaz, A; Varela-Nieto, I

    2006-01-01

    It has been reported that mutations in the gene encoding human insulin-like growth factor-I (IGF-I) cause syndromic hearing loss. To study the precise role of IGF-I in auditory function and to hypothesize the possible morphological and electrophysiological changes that may occur in the human inner ear, we have analysed the auditory brainstem response in a mouse model of IGF-I deficiency. We show here that homozygous Igf-1(-/-) mice present an all-frequency involved bilateral sensorineural hearing loss. Igf-1(-/-) mice also present a delayed response to acoustic stimuli; this increases along the auditory pathway, indicating a contribution of the central nervous system to the hearing loss in Igf-1(-/-) mice. These results support the use of the Igf-1(-/-) mouse as a new model for the study of human syndromic deafness.

  8. Granulocyte colony-stimulating factor (G-CSF): A saturated fatty acid-induced myokine with insulin-desensitizing properties in humans

    PubMed Central

    Ordelheide, Anna-Maria; Gommer, Nadja; Böhm, Anja; Hermann, Carina; Thielker, Inga; Machicao, Fausto; Fritsche, Andreas; Stefan, Norbert; Häring, Hans-Ulrich; Staiger, Harald

    2016-01-01

    Objective Circulating long-chain free fatty acids (FFAs) are important metabolic signals that acutely enhance fatty acid oxidation, thermogenesis, energy expenditure, and insulin secretion. However, if chronically elevated, they provoke inflammation, insulin resistance, and β-cell failure. Moreover, FFAs act via multiple signaling pathways as very potent regulators of gene expression. In human skeletal muscle cells differentiated in vitro (myotubes), we have shown in previous studies that the expression of CSF3, the gene encoding granulocyte colony-stimulating factor (G-CSF), is markedly induced upon FFA treatment and exercise. Methods and results We now report that CSF3 is induced in human myotubes by saturated, but not unsaturated, FFAs via Toll-like receptor 4-dependent and -independent pathways including activation of Rel-A, AP-1, C/EBPα, Src, and stress kinases. Furthermore, we show that human adipocytes and myotubes treated with G-CSF become insulin-resistant. In line with this, a functional polymorphism in the CSF3 gene affects adipose tissue- and whole-body insulin sensitivity and glucose tolerance in human subjects with elevated plasma FFA concentrations. Conclusion G-CSF emerges as a new player in FFA-induced insulin resistance and thus may be of interest as a target for prevention and treatment of type 2 diabetes. PMID:27069870

  9. Premixed flames in closed cylindrical tubes

    NASA Astrophysics Data System (ADS)

    Metzener, Philippe; Matalon, Moshe

    2001-09-01

    We consider the propagation of a premixed flame, as a two-dimensional sheet separating unburned gas from burned products, in a closed cylindrical tube. A nonlinear evolution equation, that describes the motion of the flame front as a function of its mean position, is derived. The equation contains a destabilizing term that results from the gas motion induced by thermal expansion and has a memory term associated with vorticity generation. Numerical solutions of this equation indicate that, when diffusion is stabilizing, the flame evolves into a non-planar form whose shape, and its associated symmetry properties, are determined by the Markstein parameter, and by the initial data. In particular, we observe the development of convex axisymmetric or non-axisymmetric flames, tulip flames and cellular flames.

  10. Nongradient diffusion in premixed turbulent flames

    NASA Technical Reports Server (NTRS)

    Libby, Paul A.

    1988-01-01

    Recent theoretical and experimental results demonstrating the interaction between force fields and density inhomogeneities as they arise in premixed turbulent flames are discussed. In such flames, the density fluctuates between two levels, the high density in reactants rho sub r and the low density in products rho sub p, with the ratio rho sub r/rho sub p on the order of five to ten in flows of applied interest. The force fields in such flames arise from the mean pressure drop across the flame or from the Reynolds shear stresses in tangential flames with constrained streamlines. The consequence of the interaction is nongradient turbulent transport, countergradient in the direction normal to the flame and nongradient in the tangential direction. The theoretical basis for these results, the presently available experimental support therefore and the implications for other variable density turbulent flows are discussed.

  11. The structure of particle cloud premixed flames

    NASA Technical Reports Server (NTRS)

    Seshadri, K.

    1993-01-01

    The aim of this study is to provide a numerical and asymptotic description of the structure of planar laminar flames, propagating in a medium containing a uniform cloud of fuel-particles premixed with air. Attention is restricted here to systems where the fuel-particles first vaporize to form a known gaseous fuel, which is then oxidized in the gas-phase. This program is supported for the period September 14, 1991 to September 13, 1992. Some results of the study is shown in Ref. 1. The work summarized in Ref. 1 was initiated prior to September 14, 1991 and was completed on February 1992. Research performed in addition to that described in Ref. 1 in collaboration with Professor A. Linan, is summarized here.

  12. The premixed flame in uniform straining flow

    NASA Technical Reports Server (NTRS)

    Durbin, P. A.

    1982-01-01

    Characteristics of the premixed flame in uniform straining flow are investigated by the technique of activation-energy asymptotics. An inverse method is used, which avoids some of the restrictions of previous analyses. It is shown that this method recovers known results for adiabatic flames. New results for flames with heat loss are obtained, and it is shown that, in the presence of finite heat loss, straining can extinguish flames. A stability analysis shows that straining can suppress the cellular instability of flames with Lewis number less than unity. Strain can produce instability of flames with Lewis number greater than unity. A comparison shows quite good agreement between theoretical deductions and experimental observations of Ishizuka, Miyasaka & Law (1981).

  13. Microencapsulation of human insulin DEAE-dextran complex and the complex in liposomes by the emulsion non-solvent addition method.

    PubMed

    Manosroi, A; Manosroi, J

    1997-01-01

    Human insulin-DEAE (diethyl amino ethyl) dextran complex and human insulin DEAE-dextran complex in liposomes were encapsulated in cellulose acetate butyrate (CAB) microcapsules by the emulsion non-solvent addition method. The ratio of core-to-coat used was 1:1. The average diameters of the complex microcapsules and the complex liposome microcapsules were 239.5 +/- 77.5 and 182.9 +/- 52.2 microns respectively. In vitro dissolution studies of both types of microcapsules in simulated intestinal fluid at pH 7.2 showed a sustained release of the complex and the complex liposome microcapsules with t50 = 1.5 h and 4 h respectively. This study can be applied to the further development of oral formulations of human insulin liposomes for diabetic treatment.

  14. Human umbilical cord-derived mesenchymal stem cells elicit macrophages into an anti-inflammatory phenotype to alleviate insulin resistance in type 2 diabetic rats.

    PubMed

    Xie, Zongyan; Hao, Haojie; Tong, Chuan; Cheng, Yu; Liu, Jiejie; Pang, Yaping; Si, Yiling; Guo, Yulin; Zang, Li; Mu, Yiming; Han, Weidong

    2016-03-01

    Insulin resistance, a major characteristic of type 2 diabetes (T2D), is closely associated with adipose tissue macrophages (ATMs) that induce chronic low-grade inflammation. Recently, mesenchymal stem cells (MSCs) have been identified in alleviation of insulin resistance. However, the underlying mechanism still remains elusive. Thus, we aimed to investigate whether the effect of MSCs on insulin resistance was related to macrophages phenotypes in adipose tissues of T2D rats. In this study, human umbilical cord-derived MSCs (UC-MSCs) infusion produced significantly anti-diabetic effects and promoted insulin sensitivity in T2D rats that were induced by a high-fat diet combined with streptozotocin and directed ATMs into an alternatively activated phenotype (M2, anti-inflammatory). In vitro, MSC-induced M2 macrophages alleviated insulin resistance caused by classically activated macrophages (M1, pro-inflammatory). Further analysis showed that M1 stimulated UC-MSCs to increase expression of interleukin (IL)-6, a molecule which upregulated IL4R expression, promoted phosphorylation of STAT6 in macrophages, and eventually polarized macrophages into M2 phenotype. Moreover, the UC-MSCs effect on macrophages was largely abrogated by small interfering RNA (siRNA) knockdown of IL-6. Together, our results indicate that UC-MSCs can alleviate insulin resistance in part via production of IL-6 that elicits M2 polarization. Additionally, human obesity and insulin resistance were associated with increased pro-inflammatory ATMs infiltration. Thus, MSCs may be a new treatment for obesity-related insulin resistance and T2D concerning macrophage polarized effects.

  15. Studies of premixed laminar and turbulent flames at microgravity

    NASA Technical Reports Server (NTRS)

    Ronney, Paul D.

    1993-01-01

    A two and one-half year experimental and theoretical research program on the properties of laminar and turbulent premixed gas flames at microgravity was conducted. Progress during this program is identified and avenues for future studies are discussed.

  16. Implementation of Premixed Equilibrium Chemistry Capability in OVERFLOW

    NASA Technical Reports Server (NTRS)

    Olsen, Mike E.; Liu, Yen; Vinokur, M.; Olsen, Tom

    2004-01-01

    An implementation of premixed equilibrium chemistry has been completed for the OVERFLOW code, a chimera capable, complex geometry flow code widely used to predict transonic flowfields. The implementation builds on the computational efficiency and geometric generality of the solver.

  17. Implementation of Premixed Equilibrium Chemistry Capability in OVERFLOW

    NASA Technical Reports Server (NTRS)

    Olsen, M. E.; Liu, Y.; Vinokur, M.; Olsen, T.

    2003-01-01

    An implementation of premixed equilibrium chemistry has been completed for the OVERFLOW code, a chimera capable, complex geometry flow code widely used to predict transonic flowfields. The implementation builds on the computational efficiency and geometric generality of the solver.

  18. Mechanisms of combustion limits in premixed gas flames at microgravity

    NASA Technical Reports Server (NTRS)

    Ronney, Paul D.

    1991-01-01

    A three-year experimental and theoretical research program on the mechanisms of combustion limits of premixed gasflames at microgravity was conducted. Progress during this program is identified and avenues for future studies are discussed.

  19. Ignition transition in turbulent premixed combustion

    SciTech Connect

    Shy, S.S.; Liu, C.C.; Shih, W.T.

    2010-02-15

    Recently, Shy and his co-workers reported a turbulent ignition transition based on measurements of minimum ignition energies (MIE) of lean premixed turbulent methane combustion in a centrally-ignited, fan-stirred cruciform burner capable of generating intense isotropic turbulence. Using the same methodology, this paper presents new complete MIE data sets for stoichiometric and rich cases at three different equivalence ratios {phi} = 1.0, 1.2 and 1.3, each covering a wide range of a turbulent Karlovitz number (Ka) indicating a time ratio between chemical reaction and turbulence. Thus, ignition transition in premixed turbulent combustion depending on both Ka and {phi} can be identified for the first time. It is found that there are two distinct modes on ignition in randomly stirred methane-air mixtures (ignition transition) separated by a critical Ka where values of Ka{sub c} {approx} 8-26 depending on {phi} with the minimum Ka{sub c} occurring near {phi} = 1. For Ka < Ka{sub c}, MIE increases gradually with Ka, flame kernel formation is similar to laminar ignition remaining a torus, and 2D laser tomography images of subsequent outwardly-propagating turbulent flames show sharp fronts. For Ka > Ka{sub c}, MIE increases abruptly with Ka, flame kernel is disrupted, and subsequent randomly-propagating turbulent flames reveal distributed-like fronts. Moreover, we introduce a reaction zone Peclet number (P{sub RZ}) indicating the diffusivity ratio between turbulence and chemical reaction, such that the aforementioned very scattering MIE data depending on Ka and {phi} can be collapsed into a single curve having two drastically different increasing slopes with P{sub RZ} which are separated by a critical P{sub RZ} {approx} 4.5 showing ignition transition. Finally, a physical model is proposed to explain these results. (author)

  20. Transient response of premixed methane flames

    SciTech Connect

    Vagelopoulos, Christina M.; Frank, Jonathan H.

    2006-08-15

    The response of premixed methane-air flames to transient strain and local variations in equivalence ratio is studied during isolated interactions between a line-vortex pair and a V-flame. The temporal evolution of OH and CH is measured with planar laser-induced fluorescence for N{sub 2}-diluted flames with equivalence ratios ranging from 0.8 to 1.2. One-dimensional laminar flame calculations are used to simulate the flame response to unsteady strain and variations in reactant composition. When the reactant composition of the vortex pair and the V-flame are identical, the measurements and predictions show that the peak mole fractions of OH and CH decay monotonically in lean, stoichiometric, and rich flames. We also investigate the effects of a vortex pair with a leaner composition than the V-flame. In a stoichiometric flame, the leaner vortex enhances the decay of both OH and CH. In a rich flame, we observe an abrupt increase in OH-LIF signal and a disappearance of CH-LIF signal that are consistent with a previous experimental investigation. Our results indicate that the previously observed OH burst and CH breakage were caused by a difference in the equivalence ratios of the vortex pair and the main reactant flow. A numerical study shows that N{sub 2} dilution enhances the response of premixed flames to unsteady strain and variations in stoichiometry. Reaction-path and sensitivity analyses indicate that the peak OH and CH mole fractions exhibit significant sensitivity to the main branching reaction, H+O{sub 2} {r_reversible}OH+O. The sensitivity of OH and CH to this and other reactions is enhanced by N{sub 2} dilution. As a result, N{sub 2}-diluted flames provide a good test case for studying the reliability of chemical kinetic and transport models. (author)

  1. Cell motility in models of wounded human skin is improved by Gap27 despite raised glucose, insulin and IGFBP-5

    SciTech Connect

    Wright, Catherine S.; Berends, Rebecca F.; Flint, David J.; Martin, Patricia E.M.

    2013-02-15

    Reducing Cx43 expression stimulates skin wound healing. This is mimicked in models when Cx43 function is blocked by the connexin mimetic peptide Gap27. IGF-I also stimulates wound healing with IGFBP-5 attenuating its actions. Further, the IGF-I to IGFBP-5 ratio is altered in diabetic skin, where wound closure is impaired. We investigated whether Gap27 remains effective in augmenting scrape-wound closure in human skin wound models simulating diabetes-induced changes, using culture conditions with raised glucose, insulin and IGFBP-5. Gap27 increased scrape-wound closure in normal glucose and insulin (NGI) and to a lesser extent in high glucose and insulin (HGI). IGF-I enhanced scrape-wound closure in keratinocytes whereas IGFBP-5 inhibited this response. Gap27 overcame the inhibitory effects of IGFBP-5 on IGF-I activity. Connexin-mediated communication (CMC) was reduced in HGI, despite raised Cx43, and Gap27 significantly decreased CMC in NGI and HGI. IGF-I and IGFBP-5 did not affect CMC. IGF-I increased keratinocyte proliferation in NGI, and Gap27 increased proliferation in NGI to a greater extent than in HGI. We conclude that IGF-I and Gap27 stimulate scrape-wound closure by independent mechanisms with Gap27 inhibiting Cx43 function. Gap27 can enhance wound closure in diabetic conditions, irrespective of the IGF-I:IGFBP-5 balance. - Highlights: ► Human organotypic and keratinocyte ‘diabetic’ skin models were used to demonstrate the ability of Gap27 to improve scrape-wound closure. ► Gap27 enhanced scrape-wound closure by reducing Cx43-mediated communication, whereas IGFBP-5 retarded cell migration. ► IGF-I and IGFBP-5 did not affect connexin-mediated pathways. ► Gap27 can override altered glucose, insulin, IGF-I, and IGFBP-5 in ‘diabetic’ skin models and thus has therapeutic potential.

  2. Activation of peripheral blood neutrophils and lymphocytes by human procathepsin D and insulin-like growth factor II.

    PubMed

    Vĕtvicka, V; Fusek, M

    1994-07-01

    Cathepsin D, a lysosomal aspartic proteinase, is well known to be overexpressed and secreted in the form of its zymogen by many types of human breast cancer tissues. In the cell lines derived from these tissues, cathepsin D functions as an autocrine mitogen, and it was suggested that its secretion might pose some physiological functions. Recently we have identified the presence of procathepsin D in human breast milk and similar findings were reported for bovine milk which imply also some physiological function. Thus, we have tested the influence of procathepsin D and insulin-like growth factor II on the expression of CD11a, CD11b, FcRI, CD62L, and HLA-DR surface determinants on neutrophils and lymphocytes. We have used procathepsin D purified from the secretions of breast cancer cell line ZR-75-1 and commercially available IGF II. Our results showed that both studied factors significantly influence the expression of tested surface molecules.

  3. Studies of Premixed Laminar and Turbulent Flames at Microgravity

    NASA Technical Reports Server (NTRS)

    Ronney, Paul D.

    1993-01-01

    The work of the Principal Investigator (PI) has encompassed four topics related to the experimental and theoretical study of combustion limits in premixed flames at microgravity, as discussed in the following sections. These topics include: (1) radiation effects on premixed gas flames; (2) flame structure and stability at low Lewis number; (3) flame propagation and extinction is cylindrical tubes; and (4) experimental simulation of combustion processes using autocatalytic chemical reactions.

  4. Antagonistic Effects of Insulin and TGF-β3 during Chondrogenic Differentiation of Human BMSCs under a Minimal Amount of Factors.

    PubMed

    Hara, Emilio Satoshi; Ono, Mitsuaki; Yoshioka, Yuya; Ueda, Junji; Hazehara, Yuri; Pham, Hai Thanh; Matsumoto, Takuya; Kuboki, Takuo

    2016-01-01

    Growth factors are crucial regulators of cell differentiation towards tissue and organ development. Insulin and transforming growth factor-β (TGF-β) have been used as the major factors for chondrogenesis in vitro, by activating the AKT and Smad signaling pathways. Previous reports demonstrated that AKT and Smad3 have a direct interaction that results in the inhibition of TGF-β-mediated cellular responses. However, the result of this interaction between AKT and Smad3 during the chondrogenesis of human bone marrow-derived stem/progenitor cells (hBMSCs) is unknown. In this study, we performed functional analyses by inducing hBMSCs into chondrogenesis with insulin, TGF-β3 or in combination, and found that TGF-β3, when applied concomitantly with insulin, significantly decreases an insulin-induced increase in mRNA levels of the master regulator of chondrogenesis, SOX9, as well as the regulators of the 2 major chondrocyte markers, ACAN and COL2A1. Similarly, the insulin/TGF-β3-treated group presented a significant decrease in the deposition of cartilage matrix as detected by safranin O staining of histological sections of hBMSC micromass cultures when compared to the group stimulated with insulin alone. Intracellular analysis revealed that insulin-induced activation of AKT suppressed Smad3 activation in a dose-dependent manner. Accordingly, insulin/TGF-β3 significantly decreased the TGF-β3-induced increase in mRNA levels of the direct downstream factor of TGF-β/Smad3, CCN2/CGTF, compared to the group stimulated with TGF-β3 alone. On the other hand, insulin/TGF-β3 stimulation did not suppress insulin-induced expression of the downstream targets TSC2 and DDIT4/REDD1. In summary, insulin and TGF-β3 have antagonistic effects when applied concomitantly, with a minimal number of factors. The application of an insulin/TGF-β3 combination without further supplementation should be used with caution in the chondrogenic differentiation of hBMSCs.

  5. Premixes production for synthesis of wear-resistant composite materials

    NASA Astrophysics Data System (ADS)

    Kontsevoi, Yu V.; Meilakh, A. G.; Shubin, A. B.; Pastukhov, E. A.; Dolmatov, A. V.; Sipatov, I. S.

    2017-01-01

    State of the art line of powder metallurgy is application of initial powders as micro-composites with additional components - premixes. Usage of premixes inhibits segregation of added components and implies the homogeneity of powder charge composition, and finally it has a significant impact on structure formation and properties of end products. The aim of the present work was to design the new production technology of premixes based on iron powder which is layer-by-layer plated by aluminium and copper. We propose to carry out production of Cu-Al-Fe premixes in two stages: cladding of iron powder by aluminium and coating of the obtained composite by copper. The self-developed technique of vibration treatment of iron and aluminium powder mixture was chosen for this purpose. The uniform in thickness and unbroken copper-plating of Fe-Al powders were carried out by chemical technique. Physico-chemical properties and production conditions of premixes-powders were studied, besides optimal parameters of production and further heat-treatment were selected. In the result of the present study the Fe-Al-Cu premixes with laminated structure comprising of iron core, Fe-Al and Cu-Al intermetallide shells were synthesised.

  6. Fully Premixed Low Emission, High Pressure Multi-Fuel Burner

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet (Inventor)

    2012-01-01

    A low-emissions high-pressure multi-fuel burner includes a fuel inlet, for receiving a fuel, an oxidizer inlet, for receiving an oxidizer gas, an injector plate, having a plurality of nozzles that are aligned with premix face of the injector plate, the plurality of nozzles in communication with the fuel and oxidizer inlets and each nozzle providing flow for one of the fuel and the oxidizer gas and an impingement-cooled face, parallel to the premix face of the injector plate and forming a micro-premix chamber between the impingement-cooled face and the in injector face. The fuel and the oxidizer gas are mixed in the micro-premix chamber through impingement-enhanced mixing of flows of the fuel and the oxidizer gas. The burner can be used for low-emissions fuel-lean fully-premixed, or fuel-rich fully-premixed hydrogen-air combustion, or for combustion with other gases such as methane or other hydrocarbons, or even liquid fuels.

  7. Insulin degludec and insulin degludec/insulin aspart in Ramadan: A single center experience

    PubMed Central

    Kalra, Sanjay

    2016-01-01

    This study aimed to document the utility and safety of insulin degludec (IDeg) and insulin degludec aspart (IDegAsp) in persons with type 2 diabetes, observing the Ramadan fast. An observational study was conducted at a single center, in the real world setting, on six persons who either switched to IDeg or IDegAsp a month before Ramadan or changed time of administration of IDegAsp at the onset of Ramadan, to keep the fast in a safe manner. Subjects were kept under regular monitoring and surveillance before, during, and after Ramadan, and counseled in an opposite manner. Four persons, who shifted from premixed insulin to IDegAsp, experienced a 12–18% dose reduction after 14 days. At the onset of Ramadan, the Suhur dose was reduced by 30%, and this remained unchanged during the fasting month. The Iftar dose had to be increased by 4 units. One person who shifted from neutral protamine hagedorn to IDeg demonstrated a 25% dose reduction at 20 days, without any further change in insulin requirement during Ramadan. One person who changed time of injection of IDegAsp from morning to night reported no change in dosage. No episode of major hypoglycemia was reported. IDeg and IDegAsp are effective, safe, and well-tolerated means of achieving glycemic control in persons with type 2 diabetes who wish to fast. PMID:27366727

  8. Insulin signaling and insulin resistance.

    PubMed

    Beale, Elmus G

    2013-01-01

    Insulin resistance or its sequelae may be the common etiology of maladies associated with metabolic syndrome (eg, hypertension, type 2 diabetes, atherosclerosis, heart attack, stroke, and kidney failure). It is thus important to understand those factors that affect insulin sensitivity. This review stems from the surprising discovery that interference with angiotensin signaling improves insulin sensitivity, and it provides a general overview of insulin action and factors that control insulin sensitivity.

  9. Potential Epigenetic Biomarkers of Obesity Related Insulin Resistance in Human Whole-blood.

    PubMed

    Day, Samantha E; Coletta, Richard L; Kim, Joon Young; Garcia, Luis A; Campbell, Latoya E; Benjamin, Tonya R; Roust, Lori R; De Filippis, Elena A; Mandarino, Lawrence J; Coletta, Dawn K

    2017-01-20

    Obesity can increase the risk of complex metabolic diseases, including insulin resistance. Moreover, obesity can be caused by environmental and genetic factors. However, the epigenetic mechanisms of obesity are not well defined. Therefore, the identification of novel epigenetic biomarkers of obesity allows for a more complete understanding of the disease and its underlying insulin resistance. The aim of our study was to identify DNA methylation changes in whole-blood that were strongly associated with obesity and insulin resistance. Whole-blood was obtained from lean (n = 10; BMI = 23.6 ± 0.7 kg/m(2)) and obese (n = 10; BMI = 34.4 ± 1.3 kg/m(2)) participants in combination with euglycemic hyperinsulinemic clamps to assess insulin sensitivity. We performed reduced representation bisulfite sequencing on genomic DNA isolated from the blood. We identified 49 differentially methylated cytosines (DMCs; q<0.05) that were altered in obese compared to lean participants. We identified two sites (Chr.21:46,957,981 and Chr.21:46,957,915) in the 5' untranslated region of solute carrier family 19 member 1 (SLC19A1) with decreased in methylation in obese participants (lean 0.73 ± 0.11 vs. obese 0.09 ± 0.05; lean 0.68 ± 0.10 vs. obese 0.09 ± 0.05, respectively). These two DMCs identified by obesity were also significantly predicted by insulin sensitivity (r = 0.68, P = 0.003; r = 0.66; P = 0.004). In addition, we performed a differentially methylated region (DMR) analysis and demonstrated a decrease in methylation of Chr.21:46,957,915-46,958,001 in SLC19A1 of -34.9% (70.4% lean vs. 35.5% obese). The decrease in whole-blood SLC19A1 methylation in our obese participants was similar to the change observed in skeletal muscle (Chr.21:46,957,981, lean 0.70 ± 0.09 vs. obese 0.31 ± 0.11 and Chr.21:46,957,915, lean 0.72 ± 0.11 vs. obese 0.31 ± 0.13). Pyrosequencing analysis further demonstrated a decrease in methylation at Chr.21:46,957,915 in both whole-blood (lean 0.71 ± 0

  10. Basal and insulin-regulated free fatty acid and glucose metabolism in humans.

    PubMed

    Shadid, Samyah; Kanaley, Jill A; Sheehan, Michael T; Jensen, Michael D

    2007-06-01

    These studies were done to examine the effects of body composition, resting energy expenditure (REE), sex, and fitness on basal and insulin-regulated FFA and glucose metabolism. We performed 137 experiments in 101 nondiabetic, premenopausal women and men, ranging from low normal weight to class III obese (BMI 18.0-40.5 kg/m2). Glucose flux was measured using [6-(2)H2]glucose and FFA kinetics with [9,10-(3)H]oleate under either basal (74 experiments) or euglycemic hyperinsulinemic (1.0 mU.kg FFM(-1).min(-1)) clamp conditions (63 experiments). Consistent with our previous findings, REE and sex independently predicted basal FFA flux, whereas fat-free mass was the best predictor of basal glucose flux; in addition, percent body fat was independently and positively associated with basal glucose flux (total r2 = 0.52, P < 0.0001). Insulin-suppressed lipolysis remained significantly associated with REE (r = 0.25, P < 0.05), but percent body fat also contributed (total adjusted r2 = 0.36, P < 0.0001), whereas sex was not significantly related to insulin-suppressed FFA flux. Glucose disposal during hyperinsulinemia was independently associated with peak VO2, percent body fat, and FFA concentrations (total r2 = 0.63, P < 0.0001) but not with sex. We conclude that basal glucose production is independently related to both FFM and body fatness. In addition, hyperinsulinemia obscures the sex differences in FFA release relative to REE, but brings out the effects of fatness on lipolysis.

  11. Chromium and insulin resistance.

    PubMed

    Anderson, Richard A

    2003-12-01

    Insulin resistance leads to the inability of insulin to control the utilization and storage of glucose. It is associated initially with elevated levels of circulating insulin followed by glucose intolerance which may progress to type 2 diabetes, hyperlipidaemia, hypertension, obesity and cardiovascular diseases. While the causes of these diseases are multifactorial, one nutrient that is associated with all of these abnormalities is Cr. In the presence of Cr, in a biologically active form, much lower levels of insulin are required. Modern diets, which are often high in refined carbohydrates, are not only low in Cr, but lead to enhanced Cr losses. In response to the consumption of refined carbohydrates, there is a rapid rise in blood sugar leading to elevations in insulin that cause a mobilization of Cr. Once mobilized, Cr is not reabsorbed but lost via the urine leading to decreased Cr stores. Several studies involving both human subjects and experimental animals have reported improvements in insulin sensitivity, blood glucose, insulin, lipids, haemoglobin A1c, lean body mass and related variables in response to improved Cr nutrition. However, not all studies have reported beneficial effects associated with improved Cr nutrition. Well-controlled human studies are needed to document an unequivocal effect of Cr on insulin sensitivity in human subjects. Studies need to involve a significant number of subjects with insulin resistance, glucose intolerance or early stages of diabetes, who have not been taking supplements containing Cr for at least 4 months, and involve at least 400 to 600 microg supplemental Cr daily or more. Studies should be at least 4 months to document sustained effects of supplemental Cr on insulin resistance and related variables. Cr is a nutrient and not a therapeutic agent and therefore will only be of benefit to those whose problems are due to suboptimal intake of Cr.

  12. Naturally occurring amino acid substitutions at Arg1174 in the human insulin receptor result in differential effects on receptor biosynthesis and hybrid formation, leading to discordant clinical phenotypes.

    PubMed

    Rau, H; Kocova, M; O'Rahilly, S; Whitehead, J P

    2000-07-01

    Missense mutations in the tyrosine kinase domain of the human insulin receptor frequently result in a dominantly inherited form of insulin resistance. We noted a marked disparity in the clinical phenotypes of our study subjects with different missense mutations at the same residue (Arg1174) of the insulin receptor. Subjects with a tryptophan substitution (W) were only moderately hyperinsulinemic, whereas those with a glutamine substitution (Q) had severe clinical and biochemical insulin resistance. Studies were undertaken to explore the molecular mechanisms underlying these differences. Both W and Q mutant receptors bound insulin normally but were kinase inactive. The W mutation resulted in more rapid degradation of newly synthesized mutant receptor, which contrasted with the near-normal biosynthesis of the Q receptor. The propensity of the W receptor to form hybrids with the cotransfected wild-type (WT) receptor was also markedly impaired compared with the Q receptor, to an extent greater than could be explained by lower steady-state expression. Thus, the more clinically benign consequences of the heterozygous W mutant receptor are likely to relate to its impaired biosynthesis and/or reduced capacity to form hybrids with WT receptors. In addition to providing an explanation for the milder phenotype of 1174W versus 1174Q carriers, these studies provide further support for the notion that the dominant-negative effect of insulin receptor tyrosine kinase mutations involves the competition between inactive mutant homodimers and WT/mutant hybrids with active WT homodimers for both ligands and intracellular substrates.

  13. Zinc Up-Regulates Insulin Secretion from β Cell-Like Cells Derived from Stem Cells from Human Exfoliated Deciduous Tooth (SHED)

    PubMed Central

    Kim, Gyuyoup; Shin, Ki-Hyuk; Pae, Eung-Kwon

    2016-01-01

    Stem cells from human exfoliated deciduous tooth (SHED) offer several advantages over other stem cell sources. Using SHED, we examined the roles of zinc and the zinc uptake transporter ZIP8 (Zrt- and irt-like protein 8) while inducing SHED into insulin secreting β cell-like stem cells (i.e., SHED-β cells). We observed that ZIP8 expression increased as SHED differentiated into SHED-β cells, and that zinc supplementation at day 10 increased the levels of most pancreatic β cell markers—particularly Insulin and glucose transporter 2 (GLUT2). We confirmed that SHED-β cells produce insulin successfully. In addition, we note that zinc supplementation significantly increases insulin secretion with a significant elevation of ZIP8 transporters in SHED-β cells. We conclude that SHED can be converted into insulin-secreting β cell-like cells as zinc concentration in the cytosol is elevated. Insulin production by SHED-β cells can be regulated via modulation of zinc concentration in the media as ZIP8 expression in the SHED-β cells increases. PMID:27983594

  14. Cocoa flavonoids attenuate high glucose-induced insulin signalling blockade and modulate glucose uptake and production in human HepG2 cells.

    PubMed

    Cordero-Herrera, Isabel; Martín, María Ángeles; Goya, Luis; Ramos, Sonia

    2014-02-01

    Insulin resistance is the primary characteristic of type 2 diabetes. Cocoa and its main flavanol, (-)-epicatechin (EC), display some antidiabetic effects, but the mechanisms for their preventive activities related to glucose metabolism and insulin signalling in the liver remain largely unknown. In the present work, the preventive effect of EC and a cocoa polyphenolic extract (CPE) on insulin signalling and on both glucose production and uptake are studied in insulin-responsive human HepG2 cells treated with high glucose. Pre-treatment of cells with EC or CPE reverted decreased tyrosine-phosphorylated and total levels of IR, IRS-1 and -2 triggered by high glucose. EC and CPE pre-treatment also prevented the inactivation of the PI3K/AKT pathway and AMPK, as well as the diminution of GLUT-2 levels induced by high glucose. Furthermore, pre-treatment of cells with EC and CPE avoided the increase in PEPCK levels and the diminished glucose uptake provoked by high glucose, returning enhanced levels of glucose production and decreased glycogen content to control values. These findings suggest that EC and CPE improved insulin sensitivity of HepG2 treated with high glucose, preventing or delaying a potential hepatic dysfunction through the attenuation of the insulin signalling blockade and the modulation of glucose uptake and production.

  15. Immunologic insulin resistance.

    PubMed

    Davidson, J K; DeBra, D W

    1978-03-01

    The efficacy of sulfated beef insulin for plasma glucose control in 35 patients with immunologic insulin resistance was studied. Patients were on a mean dose of 550 U./day (range 200--2,000) of U-500 regular beef insulin. Mean maximum 125I-insulin-binding capacity was 191 mU./ml. serum (range 13--1,080). Mean in vivo half-life (T 1/2) of 125I-regular beef insulin was 614 minutes (range 114--1,300), as against a mean T 1/2 of 13.9 minutes (range 11.8--16.5) in normal controls. Treatment was successful in 34 patients and unsuccessful in one with lipoatrophic diabetes. The mean initial dose of sulfated insulin was 89 U./day (range 15--400) and at three months was 66 U./day (range 20--400). Twenty-eight patients who responded and survived have been on sulfated insulin for a mean of 39 months (range 2-66) and are on a mean dose of 25 U./day (range 0--100). The mean maximum binding capacity fell to 9 mU./ml. (range 0--34) during therapy (p less than 0.01). Mean 125I-insulin T 1/2 fell from 614 to 249 minutes after sulfated insulin therapy (p less than 0.001). A comparative study of 15 patients on consecutive days showed a 35 sulfated insulin T 1/2 of 60 minutes (range 15--94) and a mean 125I-regular insulin T 1/2 of 246 minutes (range 62--560, p less than 0.001). These results indicate that sulfated insulin is less antigenic than regular beef insulin and combines less avidly with human antibodies to regular beef insulin. The response to sulfated insulin therapy was significantly better than the response reported by other investigators to pork insulin or to steroid therapy in similar patients.

  16. Apoptosis induced by an anti-epidermal growth factor receptor monoclonal antibody in a human colorectal carcinoma cell line and its delay by insulin.

    PubMed Central

    Wu, X; Fan, Z; Masui, H; Rosen, N; Mendelsohn, J

    1995-01-01

    Both EGF and insulin, or IGF, stimulate the growth of many cell types by activating receptors that contain tyrosine kinase activities. A monoclonal antibody (mAb 225) against the EGF receptor produced in this laboratory has been shown to competitively inhibit EGF binding and block activation of receptor tyrosine kinase. Here we report that a human colorectal carcinoma cell line, DiFi, which expresses high levels of EGF receptors on plasma membranes, can be induced to undergo G1 cell cycle arrest and programmed cell death (apoptosis) when cultured with mAb 225 at concentrations that saturate EGF receptors. Addition of IGF-1 or high concentrations of insulin can delay apoptosis induced by mAb 225, while the G1 arrest cannot be reversed by either IGF-1 or insulin. Insulin/IGF-1 cannot activate EGF receptor tyrosine kinase that has been inhibited by mAb 225. Moreover, an mAb against the IGF-1 receptor, which has little direct effect on DiFi cell growth, can block the capacity of insulin/IGF-1 to delay apoptosis induced by mAb 225, suggesting that the insulin/IGF-1-mediated delay of apoptosis is acting through the IGF-1 receptor. In contrast, insulin/IGF-1 cannot delay the apoptosis caused by the DNA damaging agent, cisplatin. The results indicate that EGF receptor activation is required both for cell cycle progression and for prevention of apoptosis in DiFi cells, and that a signal transduction pathway shared by receptors for insulin/IGF-1 and EGF may be involved in regulating apoptosis triggered by blockade of the EGF receptor. Images PMID:7706497

  17. In-vitro evaluation of the effect of polymer structure on uptake of novel polymer-insulin polyelectrolyte complexes by human epithelial cells.

    PubMed

    Ibie, C; Knott, R; Thompson, C J

    2015-02-01

    The biocompatibility and cellular uptake of polymer, insulin polyelectrolyte complexes (PECs) prepared using polyallylamine-based polymers was evaluated in-vitro using Caco-2 cell monolayers as a predictive model for human small intestinal epithelial cells. Poly(allyl amine) (PAA) and Quaternised PAA (QPAA) were thiolated using either carbodiimide mediated conjugation to N-acetylcysteine (NAC) or reaction with 2-iminothiolane hydrochloride yielding their NAC and 4-thiobutylamidine (TBA) conjugates, respectively. The effect of polymer quaternisation and/or thiolation on the IC50 of PAA was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay carried out on Caco-2 cells (with and without a 24 h recovery period after samples were removed). Uptake of PECs by Caco-2 cells was monitored by microscopy using fluorescein isothiocyanate (FITC) labelled insulin and rhodamine-labelled polymers at polymer:insulin ratios (4:5) after 0.5, 1, 2 and 4 h incubation in growth media (±calcium) and following pre-incubation with insulin. MTT results indicated that quaternisation of PAA was associated with an improvement in IC50 values; cells treated with QPAA (0.001-4 mg mL(-1)) showed no signs of toxicity following a 24 h cell recovery period, while thiolation of QPAA resulted in a decrease in the IC50. Cellular uptake studies showed that within 2-4 h, QPAA and QPAA-TBA insulin PECs were taken up intracellularly, with PECs being localised within the perinuclear area of cells. Further investigation showed that uptake of PECs was unaffected when calcium-free media was used, while presaturating insulin receptors affected the uptake of QPAA, insulin PECs, but not QPAA-TBA PECs. The biocompatibility of PAA and uptake of insulin was improved by both thiol and quaternary substitution.

  18. Insulin does not stimulate muscle protein synthesis during increased plasma branched-chain amino acids alone but still decreases whole body proteolysis in humans.

    PubMed

    Everman, Sarah; Meyer, Christian; Tran, Lee; Hoffman, Nyssa; Carroll, Chad C; Dedmon, William L; Katsanos, Christos S

    2016-10-01

    Insulin stimulates muscle protein synthesis when the levels of total amino acids, or at least the essential amino acids, are at or above their postabsorptive concentrations. Among the essential amino acids, branched-chain amino acids (BCAA) have the primary role in stimulating muscle protein synthesis and are commonly sought alone to stimulate muscle protein synthesis in humans. Fourteen healthy young subjects were studied before and after insulin infusion to examine whether insulin stimulates muscle protein synthesis in relation to the availability of BCAA alone. One half of the subjects were studied in the presence of postabsorptive BCAA concentrations (control) and the other half in the presence of increased plasma BCAA (BCAA). Compared with that prior to the initiation of the insulin infusion, fractional synthesis rate of muscle protein (%/h) did not change (P > 0.05) during insulin in either the control (0.04 ± 0.01 vs 0.05 ± 0.01) or the BCAA (0.05 ± 0.02 vs. 0.05 ± 0.01) experiments. Insulin decreased (P < 0.01) whole body phenylalanine rate of appearance (μmol·kg(-1)·min(-1)), indicating suppression of muscle proteolysis, in both the control (1.02 ± 0.04 vs 0.76 ± 0.04) and the BCAA (0.89 ± 0.07 vs 0.61 ± 0.03) experiments, but the change was not different between the two experiments (P > 0.05). In conclusion, insulin does not stimulate muscle protein synthesis in the presence of increased circulating levels of plasma BCAA alone. Insulin's suppressive effect on proteolysis is observed independently of the levels of circulating plasma BCAA.

  19. Premixer Design for High Hydrogen Fuels

    SciTech Connect

    Benjamin P. Lacy; Keith R. McManus; Balachandar Varatharajan; Biswadip Shome

    2005-12-16

    This 21-month project translated DLN technology to the unique properties of high hydrogen content IGCC fuels, and yielded designs in preparation for a future testing and validation phase. Fundamental flame characterization, mixing, and flame property measurement experiments were conducted to tailor computational design tools and criteria to create a framework for predicting nozzle operability (e.g., flame stabilization, emissions, resistance to flashback/flame-holding and auto-ignition). This framework was then used to establish, rank, and evaluate potential solutions to the operability challenges of IGCC combustion. The leading contenders were studied and developed with the most promising concepts evaluated via computational fluid dynamics (CFD) modeling and using the design rules generated by the fundamental experiments, as well as using GE's combustion design tools and practices. Finally, the project scoped the necessary steps required to carry the design through mechanical and durability review, testing, and validation, towards full demonstration of this revolutionary technology. This project was carried out in three linked tasks with the following results. (1) Develop conceptual designs of premixer and down-select the promising options. This task defined the ''gap'' between existing design capabilities and the targeted range of IGCC fuel compositions and evaluated the current capability of DLN pre-mixer designs when operated at similar conditions. Two concepts (1) swirl based and (2) multiple point lean direct injection based premixers were selected via a QFD from 13 potential design concepts. (2) Carry out CFD on chosen options (1 or 2) to evaluate operability risks. This task developed the leading options down-selected in Task 1. Both a GE15 swozzle based premixer and a lean direct injection concept were examined by performing a detailed CFD study wherein the aerodynamics of the design, together with the chemical kinetics of the combustion process, were

  20. Large eddy simulation of bluff body stabilized premixed and partially premixed combustion

    NASA Astrophysics Data System (ADS)

    Porumbel, Ionut

    Large Eddy Simulation (LES) of bluff body stabilized premixed and partially premixed combustion close to the flammability limit is carried out in this thesis. The main goal of the thesis is the study of the equivalence ratio effect on flame stability and dynamics in premixed and partially premixed flames. An LES numerical algorithm able to handle the entire range of combustion regimes and equivalence ratios is developed for this purpose. The algorithm has no ad-hoc adjustable model parameters and is able to respond automatically to variations in the inflow conditions, without user intervention. Algorithm validation is achieved by conducting LES of reactive and non-reactive flow. Comparison with experimental data shows good agreement for both mean and unsteady flow properties. In the reactive flow, two scalar closure models, Eddy Break-Up (EBULES) and Linear Eddy Mixing (LEMLES), are used and compared. Over important regions, the flame lies in the Broken Reaction Zone regime. Here, the EBU model assumptions fail. In LEMLES, the reaction-diffusion equation is not filtered, but resolved on a linear domain and the model maintains validity. The flame thickness predicted by LEMLES is smaller and the flame is faster to respond to turbulent fluctuations, resulting in a more significant wrinkling of the flame surface when compared to EBULES. As a result, LEMLES captures better the subtle effects of the flame-turbulence interaction, the flame structure shows higher complexity, and the far field spreading of the wake is closer to the experimental observations. Three premixed (φ = 0.6, 0.65, and 0.75) cases are simulated. As expected, for the leaner case (φ = 0.6) the flame temperature is lower, the heat release is reduced and vorticity is stronger. As a result, the flame in this case is found to be unstable. In the rich case (φ = 0.75), the flame temperature is higher, and the spreading rate of the wake is increased due to the higher amount of heat release. The ignition

  1. Application of PK/PD modeling and simulation to dosing regimen optimization of high-dose human regular U-500 insulin.

    PubMed

    de la Peña, Amparo; Ma, Xiaosu; Reddy, Shobha; Ovalle, Fernando; Bergenstal, Richard M; Jackson, Jeffrey A

    2014-07-01

    Pharmacokinetic/pharmacodynamic (PK/PD) studies of human regular U-500 insulin (U-500R) at high doses commonly used in clinical practice (>100 units) have not been performed. The current analysis applied PK/PD modeling/simulation to fit the data and simulate single-dose and steady-state PK/PD of U-500R high-dose regimens. Data from 3 single-dose euglycemic clamp studies in healthy obese and normal-weight patients, and normal-weight patients with type 1 diabetes were used to build the model. The model was sequential (PK inputs fed into PD component). PK was described using a 1-compartment model with first-order absorption and elimination. The model estimated separate absorption rate constants for U-500R and human regular U-100 insulin. The PD component used an effect compartment model, parameterized in terms of maximum pharmacologic effect (E(max)) and concentration to achieve 50% of E(max). The model described the data well. Steady-state PK for once-daily (QD), twice-daily (BID), or thrice-daily (TID) administration appeared to be reached 24 hours after the first dose. At steady-state, QD dosing showed the greatest fluctuations in PK/PD. BID dosing showed a gradual increase in insulin action with each dose and a fairly stable basal insulin effect. For TID dosing, activity was maintained throughout the dosing interval. PK/PD modeling/simulation of high U-500R doses supports BID or TID administration with an extended duration of activity relative to QD. TID dosing may provide slightly better full-day insulin effect. Additional PK/PD studies and randomized controlled trials of U-500R are needed to validate model predictions in patients with insulin-resistant diabetes requiring high-dose insulin.

  2. The effect of the putative endogenous imidazoline receptor ligand, clonidine-displacing substance, on insulin secretion from rat and human islets of Langerhans

    PubMed Central

    Chan, Susan L F; Atlas, Daphne; James, Roger F L; Morgan, Noel G

    1997-01-01

    The effects of a rat brain extract containing clonidine-displacing substance (CDS), a putative endogenous imidazoline receptor ligand, on insulin release from rat and human isolated islets of Langerhans were investigated.CDS was able to potentiate the insulin secretory response of rat islets incubated at 6 mM glucose, in a dose-dependent manner. The magnitude of this effect was similar to that in response to the well-characterized imidazoline secretagogue, efaroxan.CDS, like other imidazoline secretagogues, was also able to reverse the inhibitory action of diazoxide on glucose-induced insulin release, in both rat and human islets.These effects of CDS on secretion were reversed by the imidazoline secretagogue antagonists, RX801080 and the newly defined KU14R, providing the first evidence that imidazoline-mediated actions of CDS can be blocked by specific imidazoline antagonists.The effects of CDS on insulin secretion were unaffected when the method of preparation involved centri-filtration through a 3,000 Da cut-off membrane or when the extract was treated with protease. These results confirm that the active principle is of low molecular weight and is not a peptide.Overall, the data suggest that CDS behaves as a potent endogenous insulin secretagogue acting at the islet imidazoline receptor. PMID:9138700

  3. Insulin Test

    MedlinePlus

    ... ovarian syndrome (PCOS) , prediabetes or heart disease , or metabolic syndrome . A health practitioner also may order insulin and ... such as appears in type 2 diabetes and metabolic syndrome Decreased insulin levels are seen with: Diabetes Hypopituitarism ...

  4. Human insulin analogues modified at the B26 site reveal a hormone conformation that is undetected in the receptor complex

    SciTech Connect

    Žáková, Lenka; Kletvíková, Emília; Lepšík, Martin; Collinsová, Michaela; Watson, Christopher J.; Turkenburg, Johan P.; Jiráček, Jiří; Brzozowski, Andrzej M.

    2014-10-01

    [AsnB26]- and [GlyB26]-insulin mutants attain a B26-turn like fold without assistance of chemical modifications. Their structures match the insulin receptor interface and expand the spectrum of insulin conformations. The structural characterization of the insulin–insulin receptor (IR) interaction still lacks the conformation of the crucial B21–B30 insulin region, which must be different from that in its storage forms to ensure effective receptor binding. Here, it is shown that insulin analogues modified by natural amino acids at the TyrB26 site can represent an active form of this hormone. In particular, [AsnB26]-insulin and [GlyB26]-insulin attain a B26-turn-like conformation that differs from that in all known structures of the native hormone. It also matches the receptor interface, avoiding substantial steric clashes. This indicates that insulin may attain a B26-turn-like conformation upon IR binding. Moreover, there is an unexpected, but significant, binding specificity of the AsnB26 mutant for predominantly the metabolic B isoform of the receptor. As it is correlated with the B26 bend of the B-chain of the hormone, the structures of AsnB26 analogues may provide the first structural insight into the structural origins of differential insulin signalling through insulin receptor A and B isoforms.

  5. Functional properties of an isolated. cap alpha beta. heterodimeric human placenta insulin-like growth factor 1 receptor complex

    SciTech Connect

    Feltz, S.M.; Swanson, M.L.; Wemmie, J.A.; Pessin, J.E.

    1988-05-03

    Treatment of human placenta membranes at pH 8.5 in the presence of 2.0 mM dithiothreitol (DTT) for 5 min, followed by the simultaneous removal of the DTT and pH adjustment of pH 7.6, resulted in the formation of a functional ..cap alpha beta.. heterodimeric insulin-like growth factor 1 (IGF-1) receptor complex from the native ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric disulfide-linked state. The membrane-bound ..cap alpha beta.. heterodimeric complex displayed similar curvilinear /sup 125/I-IGF-1 equilibrium binding compared to the ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric complex. /sup 125/I-IGF-1 binding to both the isolated ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric and ..cap alpha beta.. heterodimeric complexes demonstrated a marked straightening of the Scatchard plots, compared to the placenta membrane-bound IGF-1 receptors, with a 2-fold increase in the high-affinity binding component. IGF-1 stimulation of IGF-1 receptor autophosphorylation indicated that the ligand-dependent activation of ..cap alpha beta.. heterodimeric protein kinase activity occurred concomitant with the reassociation into a covalent ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric state. These data demonstrate that (i) a combination of alkaline pH and DTT treatment of human placenta membranes results in the formation of an ..cap alpha beta.. heterodimeric IGF-1 receptor complex, (ii) unlike the insulin receptor, high-affinity homogeneous IGF-1 binding occurs in both the ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric and ..cap alpha beta.. heterodimeric complexes, and (iii) IGF-1-dependent autophosphorylation of the ..cap alpha beta.. heterodimeric IGF-1 receptor complex correlates wit an IGF-1 dependent covalent reassociation into an ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric disulfide-linked state.

  6. The Role of Growth Hormone and Insulin-Like Growth Factor 1 in Human Breast Cancer Growth in a Mouse Xenograft Model

    DTIC Science & Technology

    1998-10-01

    The purpose of this research is to determine the role of human growth hormone (hGH) and insulin-like growth factor 1(IGF-1) in the development of an...progression of tumor growth in the animal model. In addition, growth hormone may be semi-inhibitory to growth for tumors dependent upon estrogen

  7. The Role of Growth Hormone and Insulin-Like Growth Factor-1 in Human Breast Cancer Growth in a Mouse Xenograft Model

    DTIC Science & Technology

    1999-10-01

    The purpose of this research is to determine the role of human growth hormone (hGH) and insulin-like growth factor 1 (IGF- 1) in the development of...the progression of tumor growth in the animal model. In addition growth hormone may be semi-inhibitory to growth for tumors dependent upon estrogen

  8. Dehydroepiandrosterone (DHEA) replacement decreases insulin resistance and lowers inflammatory cytokines in aging humans.

    PubMed

    Weiss, Edward P; Villareal, Dennis T; Fontana, Luigi; Han, Dong-Ho; Holloszy, John O

    2011-05-01

    Plasma dehydroepiandrosterone (DHEA) decreases ~80% between ages 25 and 75 yr. In a preliminary study, we found that 6 mo of DHEA replacement improved insulin action in elderly individuals. The purpose of the present larger, randomized double-blind study was to determine whether a longer period of DHEA replacement improves glucose tolerance. Fifty-seven men and 68 women aged 65 to 75 yr were randomly assigned to 50 mg DHEA or placebo once daily. Year one was a randomized, double blind trial. Year 2 was an open label continuation. DHEA replacement improved glucose tolerance in participants who had abnormal GT initially, reduced plasma triglycerides, and the inflammatory cytokines IL6 and TNFα.

  9. Studies in premixed combustion. Progress report, November 1, 1990--October 31, 1992

    SciTech Connect

    Sivashinsky, G.I.

    1992-08-01

    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)

  10. Flame front geometry in premixed turbulent flames

    SciTech Connect

    Shepherd, I.G.; Ashurst, W.T.

    1991-12-01

    Experimental and numerical determinations of flame front curvature and orientation in premixed turbulent flames are presented. The experimental data is obtained from planar, cross sectional images of stagnation point flames at high Damkoehler number. A direct numerical simulation of a constant energy flow is combined with a zero-thickness, constant density flame model to provide the numerical results. The computational domain is a 32{sup 3} cube with periodic boundary conditions. The two-dimensional curvature distributions of the experiments and numerical simulations compare well at similar q{prime}/S{sub L} values with means close to zero and marked negative skewness. At higher turbulence levels the simulations show that the distributions become symmetric about zero. These features are also found in the three dimensional distributions of curvature. The simulations support assumptions which make it possible to determine the mean direction cosines from the experimental data. This leads to a reduction of 12% in the estimated flame surface area density in the middle of the flame brush. 18 refs.

  11. Flame structure and chemiluminescence in premixed flames

    NASA Astrophysics Data System (ADS)

    Grana-Otero, Jose; Mahmoudi, Siamak

    2016-11-01

    The quantitative use of chemiluminescence requires the knowledge of the relationship between the concentration of excited species with flame properties such as the equivalency ratio, the burning rate or the heat release rate. With the aim of rigorously finding from first principles these relations we have analyzed, numerically and analytically, the distribution of the excited species OH* and CH* in steady hydrogen and methane planar premixed flames. Their mass fractions turn out to be extremely small; thus, a kinetic mechanism describing their dynamics in the flame can be obtained by simply adding the kinetic mechanism describing the excitation and de-excitation to the mechanism of the base flame. Due also to their small concentrations, the excited species are in steady state, facilitating a simple analytical description. The analyses show that OH*, both in hydrogen and methane flames, can be found broadly distributed downstream the preheat region, in a three-layer structure that is analytically described. The distribution of CH* is much simpler, being always in equilibrium with CH, whose concentration is in turn proportional to that of CH4. As a result, CH* is confined to the methane consumption layer in lean flames, but broadly distributed in rich flames.

  12. Premixed flame propagation in vertical tubes

    NASA Astrophysics Data System (ADS)

    Kazakov, Kirill A.

    2016-04-01

    Analytical treatment of the premixed flame propagation in vertical tubes with smooth walls is given. Using the on-shell flame description, equations for a quasi-steady flame with a small but finite front thickness are obtained and solved numerically. It is found that near the limits of inflammability, solutions describing upward flame propagation come in pairs having close propagation speeds and that the effect of gravity is to reverse the burnt gas velocity profile generated by the flame. On the basis of these results, a theory of partial flame propagation driven by a strong gravitational field is developed. A complete explanation is given of the intricate observed behavior of limit flames, including dependence of the inflammability range on the size of the combustion domain, the large distances of partial flame propagation, and the progression of flame extinction. The role of the finite front-thickness effects is discussed in detail. Also, various mechanisms governing flame acceleration in smooth tubes are identified. Acceleration of methane-air flames in open tubes is shown to be a combined effect of the hydrostatic pressure difference produced by the ambient cold air and the difference of dynamic gas pressure at the tube ends. On the other hand, a strong spontaneous acceleration of the fast methane-oxygen flames at the initial stage of their evolution in open-closed tubes is conditioned by metastability of the quasi-steady propagation regimes. An extensive comparison of the obtained results with the experimental data is made.

  13. Numerical simulation of premixed turbulent methane combustion

    SciTech Connect

    Bell, John B.; Day, Marcus S.; Grcar, Joseph F.

    2001-12-14

    In this paper we study the behavior of a premixed turbulent methane flame in three dimensions using numerical simulation. The simulations are performed using an adaptive time-dependent low Mach number combustion algorithm based on a second-order projection formulation that conserves both species mass and total enthalpy. The species and enthalpy equations are treated using an operator-split approach that incorporates stiff integration techniques for modeling detailed chemical kinetics. The methodology also incorporates a mixture model for differential diffusion. For the simulations presented here, methane chemistry and transport are modeled using the DRM-19 (19-species, 84-reaction) mechanism derived from the GRIMech-1.2 mechanism along with its associated thermodynamics and transport databases. We consider a lean flame with equivalence ratio 0.8 for two different levels of turbulent intensity. For each case we examine the basic structure of the flame including turbulent flame speed and flame surface area. The results indicate that flame wrinkling is the dominant factor leading to the increased turbulent flame speed. Joint probability distributions are computed to establish a correlation between heat release and curvature. We also investigate the effect of turbulent flame interaction on the flame chemistry. We identify specific flame intermediates that are sensitive to turbulence and explore various correlations between these species and local flame curvature. We identify different mechanisms by which turbulence modulates the chemistry of the flame.

  14. The structure of particle cloud premixed flames

    NASA Technical Reports Server (NTRS)

    Seshadri, K.; Berlad, A. L.

    1992-01-01

    The structure of premixed flames propagating in combustible systems containing uniformly distributed volatile fuel particles in an oxidizing gas mixture is analyzed. This analysis is motivated by experiments conducted at NASA Lewis Research Center on the structure of flames propagating in combustible mixtures of lycopodium particles and air. Several interesting modes of flame propagation were observed in these experiments depending on the number density and the initial size of the fuel particle. The experimental results show that steady flame propagation occurs even if the initial equivalence ratio of the combustible mixture based on the gaseous fuel available in the particles, phi sub u, is substantially larger than unity. A model is developed to explain these experimental observations. In the model, it is presumed that the fuel particles vaporize first to yield a gaseous fuel of known chemical composition which then reacts with oxygen in a one-step overall process. The activation energy of the chemical reaction is presumed to be large. The activation energy characterizing the kinetics of vaporization is also presumed to be large. The equations governing the structure of the flame were integrated numerically. It is shown that the interplay of vaporization kinetics and oxidation process can result in steady flame propagation in combustible mixtures where the value of phi sub u is substantially larger than unity. This prediction is in agreement with experimental observations.

  15. Insulin Resistance in Alzheimer's Disease

    PubMed Central

    Dineley, Kelly T; Jahrling, Jordan B; Denner, Larry

    2014-01-01

    Insulin is a key hormone regulating metabolism. Insulin binding to cell surface insulin receptors engages many signaling intermediates operating in parallel and in series to control glucose, energy, and lipids while also regulating mitogenesis and development. Perturbations in the function of any of these intermediates, which occur in a variety of diseases, cause reduced sensitivity to insulin and insulin resistance with consequent metabolic dysfunction. Chronic inflammation ensues which exacerbates compromised metabolic homeostasis. Since insulin has a key role in learning and memory as well as directly regulating ERK, a kinase required for the type of learning and memory compromised in early Alzheimer's disease (AD), insulin resistance has been identified as a major risk factor for the onset of AD. Animal models of AD or insulin resistance or both demonstrate that AD pathology and impaired insulin signaling form a reciprocal relationship. Of note are human and animal model studies geared toward improving insulin resistance that have led to the identification of the nuclear receptor and transcription factor, peroxisome proliferator-activated receptor gamma (PPARγ) as an intervention tool for early AD. Strategic targeting of alternate nodes within the insulin signaling network has revealed disease-stage therapeutic windows in animal models that coalesce with previous and ongoing clinical trial approaches. Thus, exploiting the connection between insulin resistance and AD provides powerful opportunities to delineate therapeutic interventions that slow or block the pathogenesis of AD. PMID:25237037

  16. Insulin resistance and hypertension: new insights.

    PubMed

    Soleimani, Manoocher

    2015-03-01

    Insulin resistance is associated with hypertension. Nakamura et al. demonstrate in rodents and humans with insulin resistance that while the stimulatory effect of insulin on glucose uptake in adipocytes, mediated via insulin receptor substrate 1 (IRS1), was severely diminished, its effect on salt reabsorption in the kidney proximal tubule, mediated via IRS2, was preserved. Compensatory hyperinsulinemia in individuals with insulin resistance may enhance salt absorption in the proximal tubule, resulting in a state of salt overload and hypertension.

  17. Orthologs of Human Disease Associated Genes and RNAi Analysis of Silencing Insulin Receptor Gene in Bombyx mori

    PubMed Central

    Zhang, Zan; Teng, Xiaolu; Chen, Maohua; Li, Fei

    2014-01-01

    The silkworm, Bombyx mori L., is an important economic insect that has been domesticated for thousands of years to produce silk. It is our great interest to investigate the possibility of developing the B. mori as human disease model. We searched the orthologs of human disease associated genes in the B. mori by bi-directional best hits of BLAST and confirmed by searching the OrthoDB. In total, 5006 genes corresponding to 1612 kinds of human diseases had orthologs in the B. mori, among which, there are 25 genes associated with diabetes mellitus. Of these, we selected the insulin receptor gene of the B. mori (Bm-INSR) to study its expression in different tissues and at different developmental stages and tissues. Quantitative PCR showed that Bm-INSR was highly expressed in the Malpighian tubules but expressed at low levels in the testis. It was highly expressed in the 3rd and 4th instar larvae, and adult. We knocked down Bm-INSR expression using RNA interference. The abundance of Bm-INSR transcripts were dramatically reduced to ~4% of the control level at 6 days after dsRNA injection and the RNAi-treated B. mori individuals showed apparent growth inhibition and malformation such as abnormal body color in black, which is the typical symptom of diabetic patients. Our results demonstrate that B. mori has potential use as an animal model for diabetic mellitus research. PMID:25302617

  18. A low dose euglycemic infusion of recombinant human insulin-like growth factor I rapidly suppresses fasting-enhanced pulsatile growth hormone secretion in humans.

    PubMed Central

    Hartman, M L; Clayton, P E; Johnson, M L; Celniker, A; Perlman, A J; Alberti, K G; Thorner, M O

    1993-01-01

    To determine if insulin-like growth factor I (IGF-I) inhibits pulsatile growth hormone (GH) secretion in man, recombinant human IGF-I (rhIGF-I) was infused for 6 h at 10 micrograms.kg-1.h-1 during a euglycemic clamp in 10 normal men who were fasted for 32 h to enhance GH secretion. Saline alone was infused during an otherwise identical second admission as a control. As a result of rhIGF-I infusion, total and free IGF-I concentrations increased three- and fourfold, respectively. Mean GH concentrations fell from 6.3 +/- 1.6 to 0.59 +/- 0.07 micrograms/liter after 120 min. GH secretion rates, calculated by a deconvolution algorithm, decreased with a t 1/2 of 16.6 min and remained suppressed thereafter. Suppression of GH secretion rates occurred within 60 min when total and free IGF-I concentrations were 1.6-fold and 2-fold above baseline levels, respectively, and while glucose infusion rates were < 1 mumol.kg-1.min-1. During saline infusion, GH secretion rates remained elevated. Infusion of rhIGF-I decreased the mass of GH secreted per pulse by 84% (P < 0.01) and the number of detectable GH secretory pulses by 32% (P < 0.05). Plasma insulin and glucagon decreased to nearly undetectable levels after 60 min of rhIGF-I. Serum free fatty acids, beta-hydroxybutyrate, and acetoacetate were unaffected during the first 3 h of rhIGF-I but decreased thereafter to 52, 32, and 50% of levels observed during saline. We conclude that fasting-enhanced GH secretion is rapidly suppressed by a low-dose euglycemic infusion of rhIGF-I. This effect of rhIGF-I is likely mediated through IGF-I receptors independently of its insulin-like metabolic actions. PMID:8514857

  19. 21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Nitrites and/or nitrates in curing premixes. 170... nitrates in curing premixes. (a) Nitrites and/or nitrates are food additives when combined in curing... nitrates, when packaged separately from flavoring and seasoning in curing premixes, may continue to be...

  20. Pdx1 and controlled culture conditions induced differentiation of human amniotic fluid-derived stem cells to insulin-producing clusters.

    PubMed

    Chun, So Young; Mack, David L; Moorefield, Emily; Oh, Se Heang; Kwon, Tae Gyun; Pettenati, Mark J; Yoo, James J; Coppi, Paolo De; Atala, Anthony; Soker, Shay

    2015-05-01

    This study investigated the differentiation of human amniotic fluid-derived stem cells (hAFSCs) into insulin-producing clusters in vitro. Adenovirally-delivered mouse Pdx1 (Ad-Pdx1) induced human Pdx1 expression in hAFSCs and enhanced the coordinated expression of downstream β-cell markers. When Ad-Pdx1-transduced hAFSCs were sequentially treated with activin A, bFGF and nicotinamide and the culture plate surface coated with poly-l-ornithine, the expression of islet-associated human mRNAs for Pdx1, Pax6, Ngn3 and insulin was increased. C-peptide ELISA confirmed that Ad-Pdx1-transduced hAFSCs processed and secreted insulin in a manner consistent with that pathway in pancreatic β-cells. To sustain the β-cell-like phenotype and investigate the effect of three-dimensional (3D) conformation on the differentiation of hAFSCs, Pdx1-transduced cells were encapsulated in alginate and cultured long-term under serum-free conditions. Over 2 weeks, partially differentiated hAFSC clusters increased in size and increased insulin secretion. Taken together, these data demonstrate that ectopic Pdx1 expression initiates pancreatic differentiation in hAFSCs and that a β-cell-like phenotype can be augmented by culture conditions that mimic the stromal components and 3D geometry associated with pancreatic islets.

  1. Molecularly imprinted polymer cartridges coupled on-line with high performance liquid chromatography for simple and rapid analysis of human insulin in plasma and pharmaceutical formulations.

    PubMed

    Moein, Mohammad Mahdi; Javanbakht, Mehran; Akbari-adergani, Behrouz

    2014-04-01

    In this paper, a novel method is described for automated determination of human insulin in biological fluids using principle of sequential injection on a molecularly imprinted solid-phase extraction (MISPE) cartridge as a sample clean-up technique combined with high performance liquid chromatography (HPLC). The water-compatible molecularly imprinted polymers (MIPs) were prepared using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, chloroform as a porogen and insulin as a template molecule. The imprinted polymers were then employed as the solid-phase extraction sorbent for on-line extraction of insulin from human plasma samples. To achieve the best condition, influential parameters on the extraction efficiency were thoroughly investigated. Rapid and simple analysis of the hormone was successfully accomplished through the good selectivity of the prepared sorbent coupled with HPLC. Limits of detection (LOD) and quantification (LOQ) of 0.2 ng mL(-1), 0.7 ng mL(-1), and 0.03 ng mL(-1), 0.1 ng mL(-1) were obtained in plasma and urine respectively. The obtained data exhibited the great recoveries for extraction of insulin from human plasma and pharmaceutical samples, higher than 87%.

  2. Bisphenol-A impairs insulin action and up-regulates inflammatory pathways in human subcutaneous adipocytes and 3T3-L1 cells.

    PubMed

    Valentino, Rossella; D'Esposito, Vittoria; Passaretti, Federica; Liotti, Antonietta; Cabaro, Serena; Longo, Michele; Perruolo, Giuseppe; Oriente, Francesco; Beguinot, Francesco; Formisano, Pietro

    2013-01-01

    Current evidence indicates that chemical pollutants may interfere with the homeostatic control of nutrient metabolism, thereby contributing to the increased prevalence of metabolic disorders. Bisphenol-A (BPA) is a lipophilic compound contained in plastic which is considered a candidate for impairing energy and glucose metabolism. We have investigated the impact of low doses of BPA on adipocyte metabolic functions. Human adipocytes derived from subcutaneous adipose tissue and differentiated 3T3-L1 cells were incubated with BPA, in order to evaluate the effect on glucose utilization, insulin sensitivity and cytokine secretion. Treatment with 1 nM BPA significantly inhibited insulin-stimulated glucose utilization, without grossly interfering with adipocyte differentiation. Accordingly, mRNA levels of the adipogenic markers PPARγ and GLUT4 were unchanged upon BPA exposure. BPA treatment also impaired insulin-activated receptor phosphorylation and signaling. Moreover, adipocyte incubation with BPA was accompanied by increased release of IL-6 and IFN-γ, as assessed by multiplex ELISA assays, and by activation of JNK, STAT3 and NFkB pathways. Treatment of the cells with the JNK inhibitor SP600125 almost fully reverted BPA effect on insulin signaling and glucose utilization. In conclusion, low doses of BPA interfere with inflammatory/insulin signaling pathways, leading to impairment of adipose cell function.

  3. Relationship of Postprandial Nonesterified Fatty Acids, Adipokines, and Insulin Across Gender in Human Immunodeficiency Virus–Positive Patients Undergoing Highly Active Antiretroviral Therapy

    PubMed Central

    Lu, Guijing; Thomas-Geevarghese, Asha; Anuurad, Erdembileg; Raghavan, Subhashree; Minolfo, Robert; Ormsby, Bernard; Karmally, Wahida; El-Sadr, Wafaa M.; Albu, Jeanine

    2009-01-01

    Abstract Background Metabolic derangements are common in human immunodeficiency virus (HIV)-positive subjects undergoing antiretroviral therapy, but little is known about postprandial conditions. Methods We investigated the relationship between leptin, adiponectin, nonesterified fatty acids (NEFA), and insulin in response to a day-long meal pattern and evaluated gender differences in HIV-positive men (n = 12) and women (n = 13) undergoing highly active antiretroviral therapy (HAART). Results For both men and women, a significant decrease in postprandial NEFA levels was observed following breakfast (0.53 vs. 0.22 mmol/L, P < 0.001, baseline and at 3 hours, respectively), whereas day-long postprandial leptin and adiponectin levels showed small nonsignificant oscillations. In contrast to NEFA and adiponectin, postprandial leptin levels were significantly higher among women compared to men (P < 0.05). Postprandial NEFA levels correlated positively with fasting insulin levels (r2 = 0.25, P = 0.016), and the postbreakfast decrease in NEFA levels correlated significantly with the postbreakfast increase in insulin levels (r2 = 0.17, P = 0.038). No significant association between postprandial adipokines and insulin was observed. Conclusions In HAART-treated, HIV-infected men and women, levels of NEFA, but not adipokines, showed significant postprandial variation. Furthermore, food intake resulted in significant NEFA suppression in proportion to the food-stimulated insulin increase. PMID:19320559

  4. Increased insulin translation from an insulin splice-variant overexpressed in diabetes, obesity, and insulin resistance.

    PubMed

    Minn, Alexandra H; Lan, Hong; Rabaglia, Mary E; Harlan, David M; Peculis, Brenda A; Attie, Alan D; Shalev, Anath

    2005-03-01

    Type 2 diabetes occurs when pancreatic beta-cells become unable to compensate for the underlying insulin resistance. Insulin secretion requires beta-cell insulin stores to be replenished by insulin biosynthesis, which is mainly regulated at the translational level. Such translational regulation often involves the 5'-untranslated region. Recently, we identified a human insulin splice-variant (SPV) altering only the 5'-untranslated region and conferring increased translation efficiency. We now describe a mouse SPV (mSPV) that is found in the cytoplasm and exhibits increased translation efficiency resulting in more normal (prepro)insulin protein per RNA. The RNA stability of mSPV is not increased, but the predicted secondary RNA structure is altered, which may facilitate translation. To determine the role of mSPV in insulin resistance and diabetes, mSPV expression was measured by quantitative real-time RT-PCR in islets from three diabetic and/or insulin-resistant, obese and nonobese, mouse models (BTBRob/ob, C57BL/6ob/ob, and C57BL/6azip). Interestingly, mSPV expression was significantly higher in all diabetic/insulin-resistant mice compared with wild-type littermates and was dramatically induced in primary mouse islets incubated at high glucose. This raises the possibility that the mSPV may represent a compensatory beta-cell mechanism to enhance insulin biosynthesis when insulin requirements are elevated by hyperglycemia/insulin resistance.

  5. Human biliverdin reductase-based peptides activate and inhibit glucose uptake through direct interaction with the kinase domain of insulin receptor

    PubMed Central

    Gibbs, Peter E. M.; Lerner-Marmarosh, Nicole; Poulin, Amelia; Farah, Elie; Maines, Mahin D.

    2014-01-01

    Insulin binding changes conformation of the insulin receptor kinase (IRK) domain and initiates glucose uptake through the insulin, IGF-1, phosphatidyl inositol 3-kinase (PI3K), and MAPK pathways; human biliverdin reductase (hBVR) is an IRK substrate and pathway effector. This is the first report on hBVR peptide-mediated IRK activation and conformational change. 290KYCCSRK, which increased IRK Vmax without changing Km, stimulated glucose uptake and potentiated insulin and IGF-1 stimulation in 4 cell lines. KYCCSRK in native hBVR was necessary for the hBVR and IRK cross-activation. Peptide treatment also activated PI3K downstream effectors, Akt and ERK, phosphorylation, and Elk transcriptional activity. In cells transfected with CMV-regulated EGFP-VP-peptide plasmid, C292→A mutant did not stimulate glucose uptake; K296→A decreased uptake and kinase activity. KEDQYMKMTV, corresponding to hBVR's SH2-binding domain, was a potent inhibitor of glucose uptake and IRK. The mechanism of action of peptides was examined using cells expressing IRK (aa 988–1263) activated by coexpressed KYCCSRK. Three active cys-mutants of IRK, with fluorophore coupled to cysteines, C1056, C1138, or C1234, were examined for changes in fluorescence emission spectra in the presence of peptides. KYCCSRK and KEDQYMKMTV bound to different sites in IRK. The findings identify novel agents for activating or inhibiting insulin signaling and offer a new approach for treatment of type 2 diabetes and hypoglycemia.—Gibbs, P. E. M., Lerner-Marmarosh, N., Poulin, A., Farah, E., Maines, M. D. Human biliverdin reductase-based peptides activate and inhibit glucose uptake through direct interaction with the kinase domain of insulin receptor. PMID:24568842

  6. Human Monoclonal Islet Cell Antibodies From a Patient with Insulin- Dependent Diabetes Mellitus Reveal Glutamate Decarboxylase as the Target Antigen

    NASA Astrophysics Data System (ADS)

    Richter, Wiltrud; Endl, Josef; Eiermann, Thomas H.; Brandt, Michael; Kientsch-Engel, Rosemarie; Thivolet, Charles; Jungfer, Herbert; Scherbaum, Werner A.

    1992-09-01

    The autoimmune phenomena associated with destruction of the β cell in pancreatic islets and development of type 1 (insulin-dependent) diabetes mellitus (IDDM) include circulating islet cell antibodies. We have immortalized peripheral blood lymphocytes from prediabetic individuals and patients with newly diagnosed IDDM by Epstein-Barr virus transformation. IgG-positive cells were selected by anti-human IgG-coupled magnetic beads and expanded in cell culture. Supernatants were screened for cytoplasmic islet cell antibodies using the conventional indirect immunofluorescence test on cryostat sections of human pancreas. Six islet cell-specific B-cell lines, originating from a patient with newly diagnosed IDDM, could be stabilized on a monoclonal level. All six monoclonal islet cell antibodies (MICA 1-6) were of the IgG class. None of the MICA reacted with human thyroid, adrenal gland, anterior pituitary, liver, lung, stomach, and intestine tissues but all six reacted with pancreatic islets of different mammalian species and, in addition, with neurons of rat cerebellar cortex. MICA 1-6 were shown to recognize four distinct antigenic epitopes in islets. Islet cell antibody-positive diabetic sera but not normal human sera blocked the binding of the monoclonal antibodies to their target epitopes. Immunoprecipitation of 35S-labeled human islet cell extracts revealed that a protein of identical size to the enzyme glutamate decarboxylase (EC 4.1.1.15) was a target of all MICA. Furthermore, antigen immunotrapped by the MICA from brain homogenates showed glutamate decarboxylase enzyme activity. MICA 1-6 therefore reveal glutamate decarboxylase as the predominant target antigen of cytoplasmic islet cell autoantibodies in a patient with newly diagnosed IDDM.

  7. Annular fuel and air co-flow premixer

    DOEpatents

    Stevenson, Christian Xavier; Melton, Patrick Benedict; York, William David

    2013-10-15

    Disclosed is a premixer for a combustor including an annular outer shell and an annular inner shell. The inner shell defines an inner flow channel inside of the inner shell and is located to define an outer flow channel between the outer shell and the inner shell. A fuel discharge annulus is located between the outer flow channel and the inner flow channel and is configured to inject a fuel flow into a mixing area in a direction substantially parallel to an outer airflow through the outer flow channel and an inner flow through the inner flow channel. Further disclosed are a combustor including a plurality of premixers and a method of premixing air and fuel in a combustor.

  8. Hypomorphism in human NSMCE2 linked to primordial dwarfism and insulin resistance.

    PubMed

    Payne, Felicity; Colnaghi, Rita; Rocha, Nuno; Seth, Asha; Harris, Julie; Carpenter, Gillian; Bottomley, William E; Wheeler, Eleanor; Wong, Stephen; Saudek, Vladimir; Savage, David; O'Rahilly, Stephen; Carel, Jean-Claude; Barroso, Inês; O'Driscoll, Mark; Semple, Robert

    2014-09-01

    Structural maintenance of chromosomes (SMC) complexes are essential for maintaining chromatin structure and regulating gene expression. Two the three known SMC complexes, cohesin and condensin, are important for sister chromatid cohesion and condensation, respectively; however, the function of the third complex, SMC5-6, which includes the E3 SUMO-ligase NSMCE2 (also widely known as MMS21) is less clear. Here, we characterized 2 patients with primordial dwarfism, extreme insulin resistance, and gonadal failure and identified compound heterozygous frameshift mutations in NSMCE2. Both mutations reduced NSMCE2 expression in patient cells. Primary cells from one patient showed increased micronucleus and nucleoplasmic bridge formation, delayed recovery of DNA synthesis, and reduced formation of foci containing Bloom syndrome helicase (BLM) after hydroxyurea-induced replication fork stalling. These nuclear abnormalities in patient dermal fibroblast were restored by expression of WT NSMCE2, but not a mutant form lacking SUMO-ligase activity. Furthermore, in zebrafish, knockdown of the NSMCE2 ortholog produced dwarfism, which was ameliorated by reexpression of WT, but not SUMO-ligase-deficient NSMCE. Collectively, these findings support a role for NSMCE2 in recovery from DNA damage and raise the possibility that loss of its function produces dwarfism through reduced tolerance of replicative stress.

  9. Human conditions of insulin-like growth factor-I (IGF-I) deficiency

    PubMed Central

    2012-01-01

    Insulin-like growth factor I (IGF-I) is a polypeptide hormone produced mainly by the liver in response to the endocrine GH stimulus, but it is also secreted by multiple tissues for autocrine/paracrine purposes. IGF-I is partly responsible for systemic GH activities although it possesses a wide number of own properties (anabolic, antioxidant, anti-inflammatory and cytoprotective actions). IGF-I is a closely regulated hormone. Consequently, its logical therapeutical applications seems to be limited to restore physiological circulating levels in order to recover the clinical consequences of IGF-I deficiency, conditions where, despite continuous discrepancies, IGF-I treatment has never been related to oncogenesis. Currently the best characterized conditions of IGF-I deficiency are Laron Syndrome, in children; liver cirrhosis, in adults; aging including age-related-cardiovascular and neurological diseases; and more recently, intrauterine growth restriction. The aim of this review is to summarize the increasing list of roles of IGF-I, both in physiological and pathological conditions, underlying that its potential therapeutical options seem to be limited to those proven states of local or systemic IGF-I deficiency as a replacement treatment, rather than increasing its level upper the normal range. PMID:23148873

  10. Insulin-like growth factor I induces migration and invasion of human multiple myeloma cells.

    PubMed

    Qiang, Ya-Wei; Yao, Lei; Tosato, Giovanna; Rudikoff, Stuart

    2004-01-01

    Multiple myeloma (MM) is an incurable form of cancer characterized by accumulation of malignant plasma cells in the bone marrow. During the course of this disease, tumor cells cross endothelial barriers and home to the bone marrow. In latter stages, myeloma cells extravasate through blood vessels and may seed a variety of organs. Insulin-like growth factor I (IGF-I) is one of several growth factors shown to promote the growth of MM cells. In the current study, we have assessed the ability of IGF-I to serve additionally as a chemotactic factor affecting the mobility and invasive properties of these cells. Results indicate that IGF-I promotes transmigration through vascular endothelial cells and bone marrow stromal cell lines. Analysis of endogenous signaling pathways revealed that protein kinase D/protein kinase Cmicro (PKD/PKCmicro) and RhoA were both activated in a phosphatidylinositol 3-kinase (PI-3K)-dependent manner. Inhibition of PI-3K, PKCs, or Rho-associated kinase by pharmacologic inhibitors abrogated migration, whereas mitogen-activated protein kinase (MAPK), Akt, and p70S6 kinase inhibitors had no effect. These results suggest that IGF-I promotes myeloma cell migration by activation of PI-3K/PKCmicro and PI-3K/RhoA pathways independent of Akt. The identification of IGF-I as both a proliferative and migratory factor provides a rational basis for the development of targeted therapeutic strategies directed at IGF-I in the treatment of MM.

  11. Site-specific covalent modifications of human insulin by catechol estrogens: Reactivity and induced structural and functional changes.

    PubMed

    Ku, Ming-Chun; Fang, Chieh-Ming; Cheng, Juei-Tang; Liang, Huei-Chen; Wang, Tzu-Fan; Wu, Chih-Hsing; Chen, Chiao-Chen; Tai, Jung-Hsiang; Chen, Shu-Hui

    2016-06-29

    Proteins, covalently modified by catechol estrogens (CEs), were identified recently from the blood serum of diabetic patients and referred to as estrogenized proteins. Estrogenization of circulating insulin may occur and affect its molecular functioning. Here, the chemical reactivity of CEs towards specific amino acid residues of proteins and the structural and functional changes induced by the estrogenization of insulin were studied using cyclic voltammetry, liquid chromatography-mass spectrometry, circular dichroism spectroscopy, molecular modeling, and bioassays. Our results indicate that CEs, namely, 2- and 4-hydroxyl estrogens, were thermodynamically and kinetically more reactive than the catechol moiety. Upon co-incubation, intact insulin formed a substantial number of adducts with one or multiple CEs via covalent conjugation at its Cys 7 in the A or B chain, as well as at His10 or Lys29 in the B chain. Such conjugation was coupled with the cleavage of inter-chain disulfide linkages. Estrogenization on these sites may block the receptor-binding pockets of insulin. Insulin signaling and glucose uptake levels were lower in MCF-7 cells treated with modified insulin than in cells treated with native insulin. Taken together, our findings demonstrate that insulin molecules are susceptible to active estrogenization, and that such modification may alter the action of insulin.

  12. Site-specific covalent modifications of human insulin by catechol estrogens: Reactivity and induced structural and functional changes

    PubMed Central

    Ku, Ming-Chun; Fang, Chieh-Ming; Cheng, Juei-Tang; Liang, Huei-Chen; Wang, Tzu-Fan; Wu, Chih-Hsing; Chen, Chiao-Chen; Tai, Jung-Hsiang; Chen, Shu-Hui

    2016-01-01

    Proteins, covalently modified by catechol estrogens (CEs), were identified recently from the blood serum of diabetic patients and referred to as estrogenized proteins. Estrogenization of circulating insulin may occur and affect its molecular functioning. Here, the chemical reactivity of CEs towards specific amino acid residues of proteins and the structural and functional changes induced by the estrogenization of insulin were studied using cyclic voltammetry, liquid chromatography-mass spectrometry, circular dichroism spectroscopy, molecular modeling, and bioassays. Our results indicate that CEs, namely, 2- and 4-hydroxyl estrogens, were thermodynamically and kinetically more reactive than the catechol moiety. Upon co-incubation, intact insulin formed a substantial number of adducts with one or multiple CEs via covalent conjugation at its Cys 7 in the A or B chain, as well as at His10 or Lys29 in the B chain. Such conjugation was coupled with the cleavage of inter-chain disulfide linkages. Estrogenization on these sites may block the receptor-binding pockets of insulin. Insulin signaling and glucose uptake levels were lower in MCF-7 cells treated with modified insulin than in cells treated with native insulin. Taken together, our findings demonstrate that insulin molecules are susceptible to active estrogenization, and that such modification may alter the action of insulin. PMID:27353345

  13. Site-specific covalent modifications of human insulin by catechol estrogens: Reactivity and induced structural and functional changes

    NASA Astrophysics Data System (ADS)

    Ku, Ming-Chun; Fang, Chieh-Ming; Cheng, Juei-Tang; Liang, Huei-Chen; Wang, Tzu-Fan; Wu, Chih-Hsing; Chen, Chiao-Chen; Tai, Jung-Hsiang; Chen, Shu-Hui

    2016-06-01

    Proteins, covalently modified by catechol estrogens (CEs), were identified recently from the blood serum of diabetic patients and referred to as estrogenized proteins. Estrogenization of circulating insulin may occur and affect its molecular functioning. Here, the chemical reactivity of CEs towards specific amino acid residues of proteins and the structural and functional changes induced by the estrogenization of insulin were studied using cyclic voltammetry, liquid chromatography-mass spectrometry, circular dichroism spectroscopy, molecular modeling, and bioassays. Our results indicate that CEs, namely, 2- and 4-hydroxyl estrogens, were thermodynamically and kinetically more reactive than the catechol moiety. Upon co-incubation, intact insulin formed a substantial number of adducts with one or multiple CEs via covalent conjugation at its Cys 7 in the A or B chain, as well as at His10 or Lys29 in the B chain. Such conjugation was coupled with the cleavage of inter-chain disulfide linkages. Estrogenization on these sites may block the receptor-binding pockets of insulin. Insulin signaling and glucose uptake levels were lower in MCF-7 cells treated with modified insulin than in cells treated with native insulin. Taken together, our findings demonstrate that insulin molecules are susceptible to active estrogenization, and that such modification may alter the action of insulin.

  14. Interaction between Fibrinogen and Insulin-Like Growth Factor-Binding Protein-1 in Human Plasma under Physiological Conditions.

    PubMed

    Gligorijević, N; Nedić, O

    2016-02-01

    Fibrinogen is a plasma glycoprotein and one of the principle participants in blood coagulation. It interacts with many proteins during formation of a blood clot, including insulin-like growth factors (IGFs) and their binding proteins (IGFBP). Fibrinogen complexes were found as minor fractions in fibrinogen preparations independently of the coagulation process, and their presence influences the kinetics of polymerization. The idea of this work was to investigate whether fibrinogen in human plasma interacts with IGFBPs independently of the tissue injury or coagulation process. The results have shown that fibrinogen forms complexes with IGFBP-1 under physiological conditions. Several experimental approaches have confirmed that complexes are co-isolated with fibrinogen from plasma, they are relatively stable, and they appear as a general feature of human plasma. Several other experiments excluded the possibility that alpha-2 macroglobulin/IGFBP-1 complexes or IGFBP-1 oligomers contributed to IGFBP-1 immunoreactivity. The role of fibrinogen/IGFBP-1 complexes is still unknown. Further investigation in individuals expressing both impaired glucose control and coagulopathy could contribute to identification and understanding of their possible physiological role.

  15. ATP-gated P2X3 receptors constitute a positive autocrine signal for insulin release in the human pancreatic β cell

    PubMed Central

    Jacques-Silva, M. Caroline; Correa-Medina, Mayrin; Cabrera, Over; Rodriguez-Diaz, Rayner; Makeeva, Natalia; Fachado, Alberto; Diez, Juan; Berman, Dora M.; Kenyon, Norma S.; Ricordi, Camillo; Pileggi, Antonello; Molano, R. Damaris; Berggren, Per-Olof; Caicedo, Alejandro

    2010-01-01

    Extracellular ATP has been proposed as a paracrine signal in rodent islets, but it is unclear what role ATP plays in human islets. We now show the presence of an ATP signaling pathway that enhances the human β cell's sensitivity and responsiveness to glucose fluctuations. By using in situ hybridization, RT-PCR, immunohistochemistry, and Western blotting as well as recordings of cytoplasmic-free Ca2+ concentration, [Ca2+]i, and hormone release in vitro, we show that human β cells express ionotropic ATP receptors of the P2X3 type and that activation of these receptors by ATP coreleased with insulin amplifies glucose-induced insulin secretion. Released ATP activates P2X3 receptors in the β-cell plasma membrane, resulting in increased [Ca2+]i and enhanced insulin secretion. Therefore, in human islets, released ATP forms a positive autocrine feedback loop that sensitizes the β cell's secretory machinery. This may explain how the human pancreatic β cell can respond so effectively to relatively modest changes in glucose concentration under physiological conditions in vivo. PMID:20308565

  16. Caffeine's impairment of insulin-mediated glucose disposal cannot be solely attributed to adrenaline in humans

    PubMed Central

    Battram, D S; Graham, T E; Dela, F

    2007-01-01

    Caffeine (CAF) impedes insulin-mediated glucose disposal (IMGD) and increases plasma adrenaline concentrations ([ADR]; 0.6 nm). While the antagonism of ADR abolishes the CAF effect, infusion of ADR (0.75 nm) has no effect on IMGD. We have now examined CAF and ADR in concert to determine whether or not they elicit an additive response on IMGD. We hypothesized that CAF + ADR would elicit a greater effect than either CAF or ADR alone (i.e. that CAF effects would not be solely attributed to ADR). Subjects (n = 8) completed four trials in a randomized manner. An isoglycaemic–hyperinsulinaemic clamp was performed 30 min after the following treatments were administered: (1) placebo capsules and saline infusion ([ADR]= 0.29 nm) (PL trial), (2) CAF capsules (dose = 5 mg kg−1) and saline infusion ([ADR]= 0.62 nm) (CAF trial), (3) PL capsules and ADR infusion ([ADR]= 1.19 nm) (ADR trial), and (4) CAF capsules (dose = 5 mg kg−1) and ADR infusion ([ADR]= 0.93 nm) (CAF + ADR trial). As expected, CAF, ADR and CAF + ADR decreased (P ≤ 0.05) IMGD compared to PL. CAF + ADR resulted in a more pronounced decrease in IMGD versus PL (42%) compared to CAF (26%) or ADR (24%) alone; however, the effect was not fully additive (P = 0.08). Furthermore, CAF decreased IMGD to a similar magnitude as ADR despite a 50% lower [ADR]. In summary, while ADR contributes to the CAF-induced impairment in IMGD, it is not solely responsible for caffeine's effects. PMID:17656440

  17. Differential half-maximal effects of human insulin and its analogs for in situ glucose transport and protein synthesis in rat soleus muscle

    NASA Technical Reports Server (NTRS)

    Weinstein, Randi B.; Eleid, Noura; LeCesne, Catherine; Durando, Bianca; Crawford, Julie T.; Heffner, Michelle; Layton, Christle; O'Keefe, Matthew; Robinson, Jennifer; Rudinsky, Suzy; Henriksen, Erik J.; Tischler, Marc E.

    2002-01-01

    Analogs of human insulin have been used to discriminate between responses of metabolic and mitogenic (growth-related) pathways. This study compared the stimulatory effects of human insulin (HI) and 2 analogs (X2, B-Asp(9), B-Glu(27) and H2, A-His(8),B-His(4),B-Glu(10), B-His(27)) on glucose uptake and protein synthesis in rat soleus muscle in situ. Glucose uptake, estimated by intramuscular (IM) injection of 2-deoxy[1,2-3H]glucose with or without insulin, was maximally increased at 10(-6) mol/L for HI and X2 and 10(-7) mol/L for H2. HI had a larger effect (318%) than either X2 (156%) or H2 (124%). The half-maximal effect (ED(50)) values for HI, X2, and H2 were 3.3 x10(-8) mol/L, 1.7 x 10(-7) mol/L, and 1.6 x 10(-9) mol/L, respectively. Protein synthesis, estimated by protein incorporation of [(3)H]phenylalanine injected into muscles with or without insulin, was maximally increased at 10(-5) mol/L for HI and 10(-6) for X2 and H2. HI had a larger effect in stimulating protein synthesis (34%) than either X2 (25%) or H2 (19.8%). The ED(50) values for HI, X2, and H2 were 3.0 x 10(-7) mol/L, 3.2 x 10(-7) mol/L, and 1.0 x 10(-9) mol/L, respectively. The biological potency of each analog (ED(50)insulin/ED(50)analog) showed X2 to be less potent than HI for both glucose uptake (0.2) and protein synthesis (0.9), whereas H2 is more potent than HI with ratios of 20 and 300, respectively. These data suggest that this approach for studying insulin responsiveness in a single muscle in situ may be a useful tool for investigating insulin signaling in muscle in vivo. Copyright 2002, Elsevier Science (USA). All rights reserved.

  18. Leptin replacement improves postprandial glycemia and insulin sensitivity in human immunodeficiency virus-infected lipoatrophic men treated with pioglitazone: a pilot study.

    PubMed

    Magkos, Faidon; Brennan, Aoife; Sweeney, Laura; Kang, Eun Seok; Doweiko, John; Karchmer, Adolf W; Mantzoros, Christos S

    2011-07-01

    Highly active antiretroviral therapy (HAART)-induced lipoatrophy is characterized by hypoleptinemia and insulin resistance. Evidence suggests that pioglitazone and recombinant methionyl human leptin (metreleptin) administration has beneficial effects in human immunodeficiency virus (HIV)-infected lipoatrophic patients. This proof-of-concept study aimed at evaluating whether the combination of metreleptin and pioglitazone has favorable effects, above and beyond pioglitazone alone, on both metabolic outcomes and peripheral lipoatrophy in HIV-infected patients on HAART. Nine HIV-positive men with at least 6 months of HAART exposure, clinical evidence of lipoatrophy, and low leptin concentrations (≤4 ng/mL) were placed on pioglitazone treatment (30 mg/d per os) and were randomized to receive either metreleptin (0.04 mg/kg subcutaneously once daily; n = 5) or placebo (n = 4) for 3 months in a double-blinded fashion. Compared with placebo, metreleptin reduced fasting serum insulin concentration, increased adiponectin concentration, reduced the homeostasis model assessment index of insulin resistance, and attenuated postprandial glycemia in response to a mixed meal (all P ≤ .02), but did not affect trunk and peripheral fat mass. HIV control was not affected, and no major adverse effects were observed. Metreleptin administration in HIV-positive, leptin-deficient patients with lipoatrophy treated with pioglitazone improves postprandial glycemia and insulin sensitivity. Results from this pilot study should be confirmed in larger clinical trials.

  19. Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells into Insulin-Producing Cells: Evidence for Further Maturation In Vivo.

    PubMed

    Gabr, Mahmoud M; Zakaria, Mahmoud M; Refaie, Ayman F; Khater, Sherry M; Ashamallah, Sylvia A; Ismail, Amani M; El-Halawani, Sawsan M; Ghoneim, Mohamed A

    2015-01-01

    The aim of this study was to provide evidence for further in vivo maturation of insulin-producing cells (IPCs) derived from human bone marrow-derived mesenchymal stem cells (HBM-MSCs). HBM-MSCs were obtained from three insulin-dependent type 2 diabetic volunteers. Following expansion, cells were differentiated according to a trichostatin-A/GLP protocol. One million cells were transplanted under the renal capsule of 29 diabetic nude mice. Blood glucose, serum human insulin and c-peptide levels, and glucose tolerance curves were determined. Mice were euthanized 1, 2, 4, or 12 weeks after transplantation. IPC-bearing kidneys were immunolabeled, number of IPCs was counted, and expression of relevant genes was determined. At the end of in vitro differentiation, all pancreatic endocrine genes were expressed, albeit at very low values. The percentage of IPCs among transplanted cells was small (≤3%). Diabetic animals became euglycemic 8 ± 3 days after transplantation. Thereafter, the percentage of IPCs reached a mean of ~18% at 4 weeks. Relative gene expression of insulin, glucagon, and somatostatin showed a parallel increase. The ability of the transplanted cells to induce euglycemia was due to their further maturation in the favorable in vivo microenvironment. Elucidation of the exact mechanism(s) involved requires further investigation.

  20. Fatty acid binding protein expression in different human adipose tissue depots in relation to rates of lipolysis and insulin concentration in obese individuals.

    PubMed

    Fisher, R M; Thörne, A; Hamsten, A; Arner, P

    2002-10-01

    Two fatty acid binding proteins (FABPs) are expressed in adipose tissue, adipocyte lipid binding protein (ALBP) and keratinocyte lipid binding protein (KLBP). This study investigated FABP expression in visceral and subcutaneous human adipose tissue depots and associations with lipolytic differences between the depots and circulating insulin concentrations. ALBP and KLBP (protein and RNA) were quantified in subcutaneous and omental adipose tissue from obese individuals and expressed relative to actin. ALBP RNA and protein expression was significantly higher in subcutaneous compared to omental adipose tissue (both p < 0.05), whereas KLBP RNA and protein expression was no different between the two sites. There were significant inverse correlations between serum insulin concentrations and the ALBP/KLBP RNA ratio in both subcutaneous and omental adipose tissue (both p < 0.02). Basal rates of glycerol and fatty acid release measured in adipocytes isolated from subcutaneous and omental adipose tissue were significantly higher in the former (p < or = 0.02). Therefore the relative ALBP/KLBP content of human adipose tissue is different in different adipose tissue depots and at the RNA level is related to the circulating insulin concentration, at least in obese subjects. The higher rates of basal lipolysis in adipocytes isolated from subcutaneous compared to omental adipose tissue might be related to the increased ALBP content of the former. Therefore adipose tissue FABPs are interesting candidates for investigation to further our understanding of the insulin resistance syndrome and regulation of lipolysis.

  1. Adipocyte lipolysis and insulin resistance.

    PubMed

    Morigny, Pauline; Houssier, Marianne; Mouisel, Etienne; Langin, Dominique

    2016-06-01

    Obesity-induced insulin resistance is a major risk factor for the development of type 2 diabetes. Basal fat cell lipolysis (i.e., fat cell triacylglycerol breakdown into fatty acids and glycerol in the absence of stimulatory factors) is elevated during obesity and is closely associated with insulin resistance. Inhibition of adipocyte lipolysis may therefore be a promising therapeutic strategy for treating insulin resistance and preventing obesity-associated type 2 diabetes. In this review, we explore the relationship between adipose lipolysis and insulin sensitivity. After providing an overview of the components of fat cell lipolytic machinery, we describe the hypotheses that may support the causality between lipolysis and insulin resistance. Excessive circulating fatty acids may ectopically accumulate in insulin-sensitive tissues and impair insulin action. Increased basal lipolysis may also modify the secretory profile of adipose tissue, influencing whole body insulin sensitivity. Finally, excessive fatty acid release may also worsen adipose tissue inflammation, a well-known parameter contributing to insulin resistance. Partial genetic or pharmacologic inhibition of fat cell lipases in mice as well as short term clinical trials using antilipolytic drugs in humans support the benefit of fat cell lipolysis inhibition on systemic insulin sensitivity and glucose metabolism, which occurs without an increase of fat mass. Modulation of fatty acid fluxes and, putatively, of fat cell secretory pattern may explain the amelioration of insulin sensitivity whereas changes in adipose tissue immune response do not seem involved.

  2. The corticotropin-releasing hormone test in normal short children: comparison of plasma adrenocorticotropin and cortisol responses to human corticotropin-releasing hormone and insulin-induced hypoglycemia.

    PubMed

    Goji, K

    1989-03-01

    The human corticotropin-releasing hormone (hCRH) tests were performed in twelve normal short children, and the responses of plasma ACTH and cortisol to iv administration of 1 micrograms/kg hCRH were compared with those to insulin-induced hypoglycemia. After administration of hCRH, the mean plasma ACTH level rose from a basal value of 3.3 +/- 0.4 pmol/l (mean +/- SEM) to a peak value of 9.2 +/- 0.8 pmol/l at 30 min, and the mean plasma cortisol level rose from a basal value of 231 +/- 25 nmol/l to a peak value of 546 +/- 30 nmol/l at 30 min. The ACTH response after insulin-induced hypoglycemia was greater than that after hCRH administration; the mean peak level (P less than 0.01), the percent maximum increment (P less than 0.01), and the area under the ACTH response curve (P less than 0.01) were all significantly greater after insulin-induced hypoglycemia than those after hCRH administration. Although the mean peak cortisol level after insulin-induced hypoglycemia was about 1.3-fold higher than that after hCRH administration (P less than 0.01), neither the percent maximum increment in plasma cortisol nor the area under the cortisol response curve after insulin-induced hypoglycemia was significantly different from that after hCRH administration. Consequently, the acute increases in plasma ACTH after the administration of 1 microgram/kg hCRH stimulated the adrenal gland to almost the same cortisol response as that obtained with a much greater increase in plasma ACTH after insulin-induced hypoglycemia. These results suggest that a plasma ACTH peak of 9-11 pmol/l produces near maximum acute stimulation of adrenal steroidogenesis.

  3. Expression of Recombinant Human Insulin-like Growth Factor Type 1 (rhIGF-1) in Escherichia coli

    PubMed Central

    Iranpoor, Hamidreza; Omidinia, Eskandar; Vatankhah, Venus; Gharanjik, Vahid; Shahbazi, Majid

    2015-01-01

    Background: Human insulin-like growth factor type 1 (hIGF-1) is a protein consisting of 70 amino acids (MW=7.6 kDa) and mainly synthesized by liver. Mecasermin (Trade name INCRELEX) is the synthetic form of the protein which is used as an effective treatment for particular disorders such as short stature, type 1 and 2 diabetes, and wound healing. Current study was aimed to investigate the expression of human insulin-like growth factor type1 in Escherichia coli (E. coli) BL21 (DE3) expression system in order to produce an active recombinant form of the protein. Methods: For the purpose of the study, firstly codon optimization was done for hIGF-1 gene, using bioinformatics databases. Then, the gene was synthesized and inserted in pET-24a vector by a cutting strategy included NdeI and BamHI-HF enzymes. In the next step, gene was run in agarose gel and purified. The constructed expression cassette was transformed into E. coli BL21 (DE3) cells through CaCl 2 heat shock method. Identification and confirmation of the transformed colonies were performed using screening PCR method. Synthesis of hIGF-1 was induced by IPTG. The expression in induced strains was analyzed by SDS-PAGE and western blotting techniques. Confirmation of cloning and IGF-1 expression cassette was carried out through genetic engineering procedures. Results: Analysis of transformed E. coli strain with SDS-PAGE and western blotting techniques confirmed that gene was expressed in host cells. Molecular weight of the expressed protein was estimated to be 7.6 kDa. Conclusion: hIGF-1 expression cassette for cloning and expression in E. coli was designed and the protein of interest was successfully induced and identified. In addition, E. coli BL21 (DE3) can be used as a suitable host for production of recombinant hIGF-1 and this technology has a potential to be localized. PMID:26306149

  4. Insulin Delivery System

    NASA Technical Reports Server (NTRS)

    1988-01-01

    When Programmable Implantable Medication System (PIMS) is implanted in human body, it delivers precise programmed amounts of insulin over long periods of time. Mini-Med Technologies has been refining the Technologies since initial development at APL. The size of a hockey puck, and encased in titanium shell, PIMS holds about 2 1/2 teaspoons of insulin at a programmed basal rate. If a change in measured blood sugar level dictates a different dose, the patient can vary the amount of insulin delivered by holding a small radio transceiver over the implanted system and dialing in a specific program held in the PIMS computer memory. Insulin refills are accomplished approximately 4 times a year by hypodermic needle.

  5. Human insulin analogues modified at the B26 site reveal a hormone conformation that is undetected in the receptor complex

    PubMed Central

    Žáková, Lenka; Kletvíková, Emília; Lepšík, Martin; Collinsová, Michaela; Watson, Christopher J.; Turkenburg, Johan P.; Jiráček, Jiří; Brzozowski, Andrzej M.

    2014-01-01

    The structural characterization of the insulin–insulin receptor (IR) interaction still lacks the conformation of the crucial B21–B30 insulin region, which must be different from that in its storage forms to ensure effective receptor binding. Here, it is shown that insulin analogues modified by natural amino acids at the TyrB26 site can represent an active form of this hormone. In particular, [AsnB26]-insulin and [GlyB26]-insulin attain a B26-turn-like conformation that differs from that in all known structures of the native hormone. It also matches the receptor interface, avoiding substantial steric clashes. This indicates that insulin may attain a B26-turn-like conformation upon IR binding. Moreover, there is an unexpected, but significant, binding specificity of the AsnB26 mutant for predominantly the metabolic B isoform of the receptor. As it is correlated with the B26 bend of the B-chain of the hormone, the structures of AsnB26 analogues may provide the first structural insight into the structural origins of differential insulin signalling through insulin receptor A and B isoforms. PMID:25286859

  6. Inconsistent formation and nonfunction of insulin-positive cells from pancreatic endoderm derived from human embryonic stem cells in athymic nude rats.

    PubMed

    Matveyenko, Aleksey V; Georgia, Senta; Bhushan, Anil; Butler, Peter C

    2010-11-01

    Embryonic stem cell therapy has been proposed as a therapeutic strategy to restore β-cell mass and function in T1DM. Recently, a group from Novocell (now ViaCyte) reported successful development of glucose-responsive islet-like structures after implantation of pancreatic endoderm (PE) derived from human embryonic stem cells (hESC) into immune-deficient mice. Our objective was to determine whether implantation of hESC-derived pancreatic endoderm from Novocell into athymic nude rats results in development of viable glucose-responsive pancreatic endocrine tissue. Athymic nude rats were implanted with PE derived from hESC either via implantation into the epididymal fat pads or by subcutaneous implantation into TheraCyte encapsulation devices for 20 wk. Blood glucose, weight, and human insulin/C-peptide secretion were monitored by weekly blood draws. Graft β-cell function was assessed by a glucose tolerance test, and graft morphology was assessed by immunohistochemistry and immunofluorescence. At 20 wk postimplantation, epididymal fat-implanted PE progressed to develop islet-like structures in 50% of implants, with a mean β-cell fractional area of 0.8 ± 0.3%. Human C-peptide and insulin were detectable, but at very low levels (C-peptide = 50 ± 26 pmol/l and insulin = 15 ± 7 pmol/l); however, there was no increase in human C-peptide/insulin levels after glucose challenge. There was no development of viable pancreatic tissue or meaningful secretory function when human PE was implanted in the TheraCyte encapsulation devices. These data confirm that islet-like structures develop from hESC differentiated to PE by the protocol developed by NovoCell. However, the extent of endocrine cell formation and secretory function is not yet sufficient to be clinically relevant.

  7. Disruption of glucose homeostasis and induction of insulin resistance by elevated free fatty acids in human L02 hepatocytes.

    PubMed

    Wan, X-D; Yang, W-B; Xia, Y-Z; Wang, J-F; Lu, T; Wang, X-M

    2009-05-01

    Free fatty acids (FFA) have been implicated as an important causative link between obesity, insulin resistance, and Type 2 diabetes. However, the underlying mechanisms especially for FFA-mediated hepatic insulin resistance are not fully elucidated. Here, we investigated the impaired sites in insulin signaling pathways and mechanisms of insulin resistance induced by elevated FFA in L02 hepatocytes. L02 cells were cultured in Dulbecco's modified eagle medium containing various concentrations of palmitic acid (PA) for 24 h followed by 10(-7) mol/l insulin stimulation. In some experiments, cells were pre-treated with enzymatic inhibitor Wortmannin (10(-6) mol/l). Glucose levels in medium, cytosolic glycogen contents, and phosphoenolpyruvate carboxykinase (PEPCK) activity were measured. Protein level of insulin receptor substrate (IRS)-2 and phosphorylated Akt were detected by Western blot analysis. L02 cells treated with high levels of PA exhibited increased glucose levels, whereas hepatic glycogen contents were decreased in a dose-dependent manner as compared to the control cells. There was a significant attenuation of IRS- 2 protein expression in the cells cultured with PA, and Wortmannin intervention exhibited different IRS-2 protein level with or without PA treatment. In accordance with the reduced IRS-2 level, the insulin-stimulated phosphorylation of Akt was diminished in the PA-treated cells. Basal PEPCK activity and insulin- regulated PEPCK activity were overstimulated in the cells incubated with PA. These data indicate high levels of FFA can disrupt glucose homeostasis, inflict some defects in insulin signaling, and induce insulin resistance in L02 cells.

  8. Insulin Resistance and Body Weight: Recent Human Studies Documenting the Benefits of Supplemental Chromium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The essentiality of chromium for humans was confirmed more than three decades ago with the studies showing that patients on total parenteral nutritrion (TPN) developed severe diabetic-like symptoms that could be reversed by the addition of chromium to their parenteral nutrition solutions. Since the...

  9. Premixing and flash vaporization in a two-stage combustor

    SciTech Connect

    Sjoblom, B.G.A.

    1982-01-01

    A double recirculation zone two-stage combustor fitted with airblast atomizers has been investigated in a previous work. This paper describes further tests with premixing tubes in the secondary combustion zone. Flash vaporization was employed to ensure complete vaporization of the secondary fuel, which was heated to 600K by the combustor inlet air. 9 refs.

  10. The human glucokinase gene beta-cell-type promoter: an essential role of insulin promoter factor 1/PDX-1 in its activation in HIT-T15 cells.

    PubMed

    Watada, H; Kajimoto, Y; Umayahara, Y; Matsuoka, T; Kaneto, H; Fujitani, Y; Kamada, T; Kawamori, R; Yamasaki, Y

    1996-11-01

    The glycolytic enzyme glucokinase plays a primary role in the glucose-responsive secretion of insulin, and defects of this enzyme can cause NIDDM. As a step toward understanding the molecular basis of glucokinase (GK) gene regulation, we assessed the structure and regulation of the human GK gene beta-cell-type promoter. The results of reporter gene analyses using HIT-T15 cells revealed that the gene promoter was comprised of multiple cis-acting elements, including two primarily important cis-motifs: a palindrome structure, hPal-1, and the insulin gene cis-motif A element-like hUPE3. While both elements were bound specifically by nuclear proteins, it was the homeodomain-containing transcription factor insulin promoter factor 1 (IPF1)/STF-1/PDX-1 that bound to the hUPE3 site: IPF1, when expressed in CHO-K1 cells, became bound to the hUPE3 site and activated transcription. An anti-IPF1 antiserum used in gel-mobility shift analysis supershifted the DNA protein complex formed with the hUPE3 probe and nuclear extracts from HIT-T15 cells, thus supporting the involvement of IPF1 in GK gene activation in HIT-T15 cells. In contrast to the insulin gene, however, neither the synergistic effect of the Pan1 expression on the IPF1-induced promoter activation nor the glucose responsiveness of the activity was observed for the GK gene promoter. These results revealed some conservative but unique features for the transcriptional regulation of the beta-cell-specific genes in humans. Being implicated in insulin and GK gene regulations as a common transcription factor, IPF1/STF-1/PDX-1 is likely to play an essential role in maintaining normal beta-cell functions.

  11. Characterization of P4 ATPase Phospholipid Translocases (Flippases) in Human and Rat Pancreatic Beta Cells: THEIR GENE SILENCING INHIBITS INSULIN SECRETION.

    PubMed

    Ansari, Israr-ul H; Longacre, Melissa J; Paulusma, Coen C; Stoker, Scott W; Kendrick, Mindy A; MacDonald, Michael J

    2015-09-18

    The negative charge of phosphatidylserine in lipid bilayers of secretory vesicles and plasma membranes couples the domains of positively charged amino acids of secretory vesicle SNARE proteins with similar domains of plasma membrane SNARE proteins enhancing fusion of the two membranes to promote exocytosis of the vesicle contents of secretory cells. Our recent study of insulin secretory granules (ISG) (MacDonald, M. J., Ade, L., Ntambi, J. M., Ansari, I. H., and Stoker, S. W. (2015) Characterization of phospholipids in insulin secretory granules in pancreatic beta cells and their changes with glucose stimulation. J. Biol. Chem. 290, 11075-11092) suggested that phosphatidylserine and other phospholipids, such as phosphatidylethanolamine, in ISG could play important roles in docking and fusion of ISG to the plasma membrane in the pancreatic beta cell during insulin exocytosis. P4 ATPase flippases translocate primarily phosphatidylserine and, to a lesser extent, phosphatidylethanolamine across the lipid bilayers of intracellular vesicles and plasma membranes to the cytosolic leaflets of these membranes. CDC50A is a protein that forms a heterodimer with P4 ATPases to enhance their translocase catalytic activity. We found that the predominant P4 ATPases in pure pancreatic beta cells and human and rat pancreatic islets were ATP8B1, ATP8B2, and ATP9A. ATP8B1 and CDC50A were highly concentrated in ISG. ATP9A was concentrated in plasma membrane. Gene silencing of individual P4 ATPases and CDC50A inhibited glucose-stimulated insulin release in pure beta cells and in human pancreatic islets. This is the first characterization of P4 ATPases in beta cells. The results support roles for P4 ATPases in translocating phosphatidylserine to the cytosolic leaflets of ISG and the plasma membrane to facilitate the docking and fusion of ISG to the plasma membrane during insulin exocytosis.

  12. HNF4α antagonists discovered by a high-throughput screen for modulators of the human insulin promoter.

    PubMed

    Kiselyuk, Alice; Lee, Seung-Hee; Farber-Katz, Suzette; Zhang, Mingjun; Athavankar, Sonalee; Cohen, Tom; Pinkerton, Anthony B; Ye, Mao; Bushway, Paul; Richardson, Adam D; Hostetler, Heather A; Rodriguez-Lee, Mariam; Huang, Li; Spangler, Benjamin; Smith, Layton; Higginbotham, Jennifer; Cashman, John; Freeze, Hudson; Itkin-Ansari, Pamela; Dawson, Marcia I; Schroeder, Friedhelm; Cang, Yong; Mercola, Mark; Levine, Fred

    2012-07-27

    Hepatocyte nuclear factor (HNF)4α is a central regulator of gene expression in cell types that play a critical role in metabolic homeostasis, including hepatocytes, enterocytes, and pancreatic β cells. Although fatty acids were found to occupy the HNF4α ligand-binding pocket and were proposed to act as ligands, there is controversy about both the nature of HNF4α ligands as well as the physiological role of the binding. Here, we report the discovery of potent synthetic HNF4α antagonists through a high-throughput screen for effectors of the human insulin promoter. These molecules bound to HNF4α with high affinity and modulated the expression of known HNF4α target genes. Notably, they were found to be selectively cytotoxic to cancer cell lines in vitro and in vivo, although in vivo potency was limited by suboptimal pharmacokinetic properties. The discovery of bioactive modulators for HNF4α raises the possibility that diseases involving HNF4α, such as diabetes and cancer, might be amenable to pharmacologic intervention by modulation of HNF4α activity.

  13. BMI, RQ, Diabetes, and Sex Affect the Relationships Between Amino Acids and Clamp Measures of Insulin Action in Humans

    PubMed Central

    Thalacker-Mercer, Anna E.; Ingram, Katherine H.; Guo, Fangjian; Ilkayeva, Olga; Newgard, Christopher B.; Garvey, W. Timothy

    2014-01-01

    Previous studies have used indirect measures of insulin sensitivity to link circulating amino acids with insulin resistance and identify potential biomarkers of diabetes risk. Using direct measures (i.e., hyperinsulinemic-euglycemic clamps), we examined the relationships between the metabolomic amino acid profile and insulin action (i.e., glucose disposal rate [GDR]). Relationships between GDR and serum amino acids were determined among insulin-sensitive, insulin-resistant, and type 2 diabetic (T2DM) individuals. In all subjects, glycine (Gly) had the strongest correlation with GDR (positive association), followed by leucine/isoleucine (Leu/Ile) (negative association). These relationships were dramatically influenced by BMI, the resting respiratory quotient (RQ), T2DM, and sex. Gly had a strong positive correlation with GDR regardless of BMI, RQ, or sex but became nonsignificant in T2DM. In contrast, Leu/Ile was negatively associated with GDR in nonobese and T2DM subjects. Increased resting fat metabolism (i.e., low RQ) and obesity were observed to independently promote and negate the association between Leu/Ile and insulin resistance, respectively. Additionally, the relationship between Leu/Ile and GDR was magnified in T2DM males. Future studies are needed to determine whether Gly has a mechanistic role in glucose homeostasis and whether dietary Gly enrichment may be an effective intervention in diseases characterized by insulin resistance. PMID:24130332

  14. Obesity-insulin targeted genes in the 3p26-25 region in human studies and LG/J and SM/J mice.

    PubMed

    Kraja, Aldi T; Lawson, Heather A; Arnett, Donna K; Borecki, Ingrid B; Broeckel, Ulrich; de las Fuentes, Lisa; Hunt, Steven C; Province, Michael A; Cheverud, James; Rao, D C

    2012-08-01

    Identifying metabolic syndrome (MetS) genes is important for novel drug development and health care. This study extends the findings on human chromosome 3p26-25 for an identified obesity-insulin factor QTL, with an LOD score above 3. A focused association analysis comprising up to 9578 African American and Caucasian subjects from the HyperGEN Network (908 African Americans and 1025 whites), the Family Heart Study (3035 whites in time 1 and 1943 in time 2), and the Framingham Heart Study (1317 in Offspring and 1320 in Generation 3) was performed. The homologous mouse region was explored in an F(16) generation of an advanced intercross between the LG/J and SM/J inbred strains, in an experiment where 1002 animals were fed low-fat (247 males; 254 females) or high-fat (253 males; 248 females) diets. Association results in humans indicate pleiotropic effects for SNPs within or surrounding CNTN4 on obesity, lipids and blood pressure traits and for SNPs near IL5RA, TRNT1, CRBN, and LRRN1 on central obesity and blood pressure. Linkage analyses of this region in LG/J×SM/J mice identify a highly significant pleiotropic QTL peak for insulin and glucose levels, as well as response to glucose challenge. The mouse results show that insulin and glucose levels interact with high and low fat diets and differential gene expression was identified for Crbn and Arl8b. In humans, ARL8B resides ~137kbps away from BHLHE40, expression of which shows up-regulation in response to insulin treatment. This focused human genetic analysis, incorporating mouse research evidenced that 3p26-25 has important genetic contributions to MetS components. Several of the candidate genes have functions in the brain. Their interaction with MetS and the brain warrants further investigation.

  15. Generation of insulin-producing β-like cells from human iPS cells in a defined and completely xeno-free culture system.

    PubMed

    Shahjalal, Hussain Md; Shiraki, Nobuaki; Sakano, Daisuke; Kikawa, Kazuhide; Ogaki, Soichiro; Baba, Hideo; Kume, Kazuhiko; Kume, Shoen

    2014-10-01

    Human induced pluripotent stem (hiPS) cells are considered a potential source for the generation of insulin-producing pancreatic β-cells because of their differentiation capacity. In this study, we have developed a five-step xeno-free culture system to efficiently differentiate hiPS cells into insulin-producing cells in vitro. We found that a high NOGGIN concentration is crucial for specifically inducing the differentiation first into pancreatic and duodenal homeobox-1 (PDX1)-positive pancreatic progenitors and then into neurogenin 3 (NGN3)-expressing pancreatic endocrine progenitors, while suppressing the differentiation into hepatic or intestinal cells. We also found that a combination of 3-isobutyl-1-methylxanthine (IBMX), exendin-4, and nicotinamide was important for the differentiation into insulin single-positive cells that expressed various pancreatic β-cell markers. Most notably, the differentiated cells contained endogenous C-peptide pools that were released in response to various insulin secretagogues and high levels of glucose. Therefore, our results demonstrate the feasibility of generating hiPS-derived pancreatic β-cells under xeno-free conditions and highlight their potential to treat patients with type 1 diabetes.

  16. Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans

    PubMed Central

    Stanhope, Kimber L.; Schwarz, Jean Marc; Keim, Nancy L.; Griffen, Steven C.; Bremer, Andrew A.; Graham, James L.; Hatcher, Bonnie; Cox, Chad L.; Dyachenko, Artem; Zhang, Wei; McGahan, John P.; Seibert, Anthony; Krauss, Ronald M.; Chiu, Sally; Schaefer, Ernst J.; Ai, Masumi; Otokozawa, Seiko; Nakajima, Katsuyuki; Nakano, Takamitsu; Beysen, Carine; Hellerstein, Marc K.; Berglund, Lars; Havel, Peter J.

    2009-01-01

    Studies in animals have documented that, compared with glucose, dietary fructose induces dyslipidemia and insulin resistance. To assess the relative effects of these dietary sugars during sustained consumption in humans, overweight and obese subjects consumed glucose- or fructose-sweetened beverages providing 25% of energy requirements for 10 weeks. Although both groups exhibited similar weight gain during the intervention, visceral adipose volume was significantly increased only in subjects consuming fructose. Fasting plasma triglyceride concentrations increased by approximately 10% during 10 weeks of glucose consumption but not after fructose consumption. In contrast, hepatic de novo lipogenesis (DNL) and the 23-hour postprandial triglyceride AUC were increased specifically during fructose consumption. Similarly, markers of altered lipid metabolism and lipoprotein remodeling, including fasting apoB, LDL, small dense LDL, oxidized LDL, and postprandial concentrations of remnant-like particle–triglyceride and –cholesterol significantly increased during fructose but not glucose consumption. In addition, fasting plasma glucose and insulin levels increased and insulin sensitivity decreased in subjects consuming fructose but not in those consuming glucose. These data suggest that dietary fructose specifically increases DNL, promotes dyslipidemia, decreases insulin sensitivity, and increases visceral adiposity in overweight/obese adults. PMID:19381015

  17. A review of piscine islet xenotransplantation using wild-type tilapia donors and the production of transgenic tilapia expressing a "humanized" tilapia insulin.

    PubMed

    Wright, James R; Yang, Hua; Hyrtsenko, Olga; Xu, Bao-You; Yu, Weiming; Pohajdak, Bill

    2014-01-01

    Most islet xenotransplantation laboratories have focused on porcine islets, which are both costly and difficult to isolate. Teleost (bony) fish, such as tilapia, possess macroscopically visible distinct islet organs called Brockmann bodies which can be inexpensively harvested. When transplanted into diabetic nude mice, tilapia islets maintain long-term normoglycemia and provide human-like glucose tolerance profiles. Like porcine islets, when transplanted into euthymic mice, they are rejected in a CD4 T-cell-dependent manner. However, unlike pigs, tilapia are so phylogenetically primitive that their cells do not express α(1,3)Gal and, because tilapia are highly evolved to live in warm stagnant waters nearly devoid of dissolved oxygen, their islet cells are exceedingly resistant to hypoxia, making them ideal for transplantation within encapsulation devices. Encapsulation, especially when combined with co-stimulatory blockade, markedly prolongs tilapia islet xenograft survival in small animal recipients, and a collaborator has shown function in diabetic cynomolgus monkeys. In anticipation of preclinical xenotransplantation studies, we have extensively characterized tilapia islets (morphology, embryologic development, cell biology, peptides, etc.) and their regulation of glucose homeostasis. Because tilapia insulin differs structurally from human insulin by 17 amino acids, we have produced transgenic tilapia whose islets stably express physiological levels of humanized insulin and have now bred these to homozygosity. These transgenic fish can serve as a platform for further development into a cell therapy product for diabetes.

  18. Transplacental passage of insulin complexed to antibody.

    PubMed Central

    Bauman, W A; Yalow, R S

    1981-01-01

    The passage of plasma proteins across the placental barrier in humans is known to be highly selective. Thus, free maternal insulin has been reported not to cross the normal maternofetal barrier, although insulin-binding antibodies have been detected in newborn infants whose diabetic mothers received insulin therapy. In this report we demonstrate, with the use of a human antiserum that permits distinction between human and animal insulins, that insulin in the cord blood of each of two neonates of insulin-treated diabetic mothers was, in part, animal insulin. The higher the antibody titer of the mother the greater was the total insulin in the cord plasma and the greater was the fraction that was animal insulin. In case 1 cord plasma insulin was 0.7 unit/liter, of which 10% was animal insulin; in case 2 cord plasma insulin was 3.5 units/liter, of which 25% was animal insulin. The demonstration that antigen restricted from transplacental passage can be transferred while complexed to antibody raises the question whether such fetal exposure would induce partial or total immunologic unresponsiveness subsequently if the fetus were rechallenged with the same antigen. PMID:7027265

  19. Neurotransmitters act as paracrine signals to regulate insulin secretion from the human pancreatic islet.

    PubMed

    Rodriguez-Diaz, Rayner; Menegaz, Danusa; Caicedo, Alejandro

    2014-08-15

    In this symposium review we discuss the role of neurotransmitters as paracrine signals that regulate pancreatic islet function. A large number of neurotransmitters and their receptors has been identified in the islet, but relatively little is known about their involvement in islet biology. Interestingly, neurotransmitters initially thought to be present in autonomic axons innervating the islet are also present in endocrine cells of the human islet. These neurotransmitters can thus be released as paracrine signals to help control hormone release. Here we propose that the role of neurotransmitters may extend beyond controlling endocrine cell function to work as signals modulating vascular flow and immune responses within the islet.

  20. The role of human factors in the design and development of an insulin pump.

    PubMed

    Schaeffer, Noel E

    2012-03-01

    This article discusses human factors (HF) processes and how they are applied during the development of a medical device to minimize the risk that the user interface design could lead to patient errors, adverse events, and product recalls. This process is best defined as "prevention through design." The HF design process is exemplified by three distinct phases: (1) preliminary analysis, (2) formative design evaluation and modification, and (3) design validation. Additional benefits of employing HF principles during medical device development are briefly reviewed, including reduced patient risk by eliminating design flaws, increased patient adherence through the reduction in the complexity of therapeutic regimes, and reduced likelihood for product recalls.

  1. Insulin therapy in children and adolescents.

    PubMed

    Tamborlane, William V; Sikes, Kristin A

    2012-03-01

    Insulin therapy is the mainstay of treatment in children and adolescents with type 1 diabetes (T1D) and is a key component in the treatment of type 2 diabetes (T2D) in this population as well. A major aim of current insulin replacement therapy is to simulate the normal pattern of insulin secretion as closely as possible. This aim can best be achieved with basal-bolus therapy using multiple daily injections (MDI) or continuous insulin infusion (CSII) pump therapy. Only a few years ago, options for insulin formulations were limited. There are now more than 10 varieties of biosynthetic human and analogue insulin.

  2. Intermittent Compressive Stress Enhanced Insulin-Like Growth Factor-1 Expression in Human Periodontal Ligament Cells

    PubMed Central

    Pumklin, Jittima; Manokawinchoke, Jeeranan; Bhalang, Kanokporn; Pavasant, Prasit

    2015-01-01

    Mechanical force was shown to promote IGF-1 expression in periodontal ligament both in vitro and in vivo. Though the mechanism of this effect has not yet been proved, here we investigated the molecular mechanism of intermittent mechanical stress on IGF-1 expression. In addition, the role of hypoxia on the intermittent compressive stress on IGF-1 expression was also examined. In this study, human periodontal ligament cells (HPDLs) were stimulated with intermittent mechanical stress for 24 hours. IGF-1 expression was examined by real-time polymerase chain reaction. Chemical inhibitors were used to determine molecular mechanisms of these effects. For hypoxic mimic condition, the CoCl2 supplementation was employed. The results showed that intermittent mechanical stress dramatically increased IGF-1 expression at 24 h. The pretreatment with TGF-β receptor I or TGF-β1 antibody could inhibit the intermittent mechanical stress-induced IGF-1 expression. Moreover, the upregulation of TGF-β1 proteins was detected in intermittent mechanical stress treated group. Correspondingly, the IGF-1 expression was upregulated upon being treated with recombinant human TGF-β1. Further, the hypoxic mimic condition attenuated the intermittent mechanical stress and rhTGF-β1-induced IGF-1 expression. In summary, this study suggests intermittent mechanical stress-induced IGF-1 expression in HPDLs through TGF-β1 and this phenomenon could be inhibited in hypoxic mimic condition. PMID:26106417

  3. Carob pulp preparation rich in insoluble dietary fibre and polyphenols increases plasma glucose and serum insulin responses in combination with a glucose load in humans.

    PubMed

    Gruendel, Sindy; Otto, Baerbel; Garcia, Ada L; Wagner, Karen; Mueller, Corinna; Weickert, Martin O; Heldwein, Walter; Koebnick, Corinna

    2007-07-01

    Dietary fibre consumption is associated with improved glucose homeostasis. In contrast, dietary polyphenols have been suggested to exert both beneficial and detrimental effects on glucose and insulin metabolism. Recently, we reported that a polyphenol-rich insoluble dietary fibre preparation from carob pulp (carob fibre) resulted in lower postprandial acylated ghrelin levels after a liquid meal challenge test compared with a control meal without supplementation. The effects may, however, differ when a different food matrix is used. Thus, we investigated the effects of carob fibre on glucose, insulin and ghrelin responses in healthy humans in combination with a glucose load. In a randomized single-blind cross-over study involving twenty healthy subjects (aged 22-62 years), plasma glucose, total and acylated ghrelin, and serum insulin were repeatedly assessed before and after the ingestion of 200 ml water with 50 g glucose and 0, 5, 10 or 20 g carob fibre over a period of 180 min. The intake of 5 and 10 g carob fibre increased the plasma glucose by 47 % and 64 % (P < 0.001), and serum insulin by 19.9 and 24.8 % (P < 0.001), compared with the control. Plasma acylated ghrelin concentrations did not change significantly after the consumption of carob-enriched glucose solution. Total ghrelin decreased only after 10 g carob fibre (P < 0.001) compared with control. In conclusion, we showed that polyphenol-rich carob fibre, administered within a water-glucose solution, increases postprandial glucose and insulin responses, suggesting a deterioration in glycaemic control.

  4. Insulin Induces Relaxation and Decreases Hydrogen Peroxide-Induced Vasoconstriction in Human Placental Vascular Bed in a Mechanism Mediated by Calcium-Activated Potassium Channels and L-Arginine/Nitric Oxide Pathways

    PubMed Central

    Cabrera, Lissette; Saavedra, Andrea; Rojas, Susana; Cid, Marcela; Valenzuela, Cristina; Gallegos, David; Careaga, Pamela; Basualto, Emerita; Haensgen, Astrid; Peña, Eduardo; Rivas, Coralia; Vera, Juan Carlos; Gallardo, Victoria; Zúñiga, Leandro; Escudero, Carlos; Sobrevia, Luis; Wareing, Mark; González, Marcelo

    2016-01-01

    HIGHLIGHTS Short-term incubation with insulin increases the L-arginine transport in HUVECs.Short-term incubation with insulin increases the NO synthesis in HUVECs.Insulin induces relaxation in human placental vascular bed.Insulin attenuates the constriction induced by hydrogen peroxide in human placenta.The relaxation induced by insulin is dependent on BKCa channels activity in human placenta. Insulin induces relaxation in umbilical veins, increasing the expression of human amino acid transporter 1 (hCAT-1) and nitric oxide synthesis (NO) in human umbilical vein endothelial cells (HUVECs). Short-term effects of insulin on vasculature have been reported in healthy subjects and cell cultures; however, its mechanisms remain unknown. The aim of this study was to characterize the effect of acute incubation with insulin on the regulation of vascular tone of placental vasculature. HUVECs and chorionic vein rings were isolated from normal pregnancies. The effect of insulin on NO synthesis, L-arginine transport, and hCAT-1 abundance was measured in HUVECs. Isometric tension induced by U46619 (thromboxane A2 analog) or hydrogen peroxide (H2O2) were measured in vessels previously incubated 30 min with insulin and/or the following pharmacological inhibitors: tetraethylammonium (KCa channels), iberiotoxin (BKCa channels), genistein (tyrosine kinases), and wortmannin (phosphatidylinositol 3-kinase). Insulin increases L-arginine transport and NO synthesis in HUVECs. In the placenta, this hormone caused relaxation of the chorionic vein, and reduced perfusion pressure in placental cotyledons. In vessels pre-incubated with insulin, the constriction evoked by H2O2 and U46619 was attenuated and the effect on H2O2-induced constriction was blocked with tetraethylammonium and iberiotoxin, but not with genistein, or wortmannin. Insulin rapidly dilates the placental vasculature through a mechanism involving activity of BKCa channels and L-arginine/NO pathway in endothelial cells. This

  5. Silencing of ANGPTL 3 (angiopoietin-like protein 3) in human hepatocytes results in decreased expression of gluconeogenic genes and reduced triacylglycerol-rich VLDL secretion upon insulin stimulation

    PubMed Central

    Tikka, Anna; Soronen, Jarkko; Laurila, Pirkka-Pekka; Metso, Jari; Ehnholm, Christian; Jauhiainen, Matti

    2014-01-01

    Homozygosity of loss-of-function mutations in ANGPTL3 (angiopoietin-like protein 3)-gene results in FHBL2 (familial combined hypolipidaemia, OMIM #605019) characterized by the reduction of all major plasma lipoprotein classes, which includes VLDL (very-low-density lipoprotein), LDL (low-density lipoprotein), HDL (high-density lipoprotein) and low circulating NEFAs (non-esterified fatty acids), glucose and insulin levels. Thus complete lack of ANGPTL3 in humans not only affects lipid metabolism, but also affects whole-body insulin and glucose balance. We used wild-type and ANGPTL3-silenced IHHs (human immortalized hepatocytes) to investigate the effect of ANGPTL3 silencing on hepatocyte-specific VLDL secretion and glucose uptake. We demonstrate that both insulin and PPARγ (peroxisome-proliferator-activated receptor γ) agonist rosiglitazone down-regulate the secretion of ANGPTL3 and TAG (triacylglycerol)-enriched VLDL1-type particles in a dose-dependent manner. Silencing of ANGPTL3 improved glucose uptake in hepatocytes by 20–50% and influenced down-regulation of gluconeogenic genes, suggesting that silencing of ANGPTL3 improves insulin sensitivity. We further show that ANGPTL3-silenced cells display a more pronounced shift from the secretion of TAG-enriched VLDL1-type particles to secretion of lipid poor VLDL2-type particles during insulin stimulation. These data suggest liver-specific mechanisms involved in the reported insulin-sensitive phenotype of ANGPTL3-deficient humans, featuring lower plasma insulin and glucose levels. PMID:25495645

  6. Quantitative Phosphoproteomics Analysis Reveals a Key Role of Insulin Growth Factor 1 Receptor (IGF1R) Tyrosine Kinase in Human Sperm Capacitation*

    PubMed Central

    Wang, Jing; Qi, Lin; Huang, Shaoping; Zhou, Tao; Guo, Yueshuai; Wang, Gaigai; Guo, Xuejiang; Zhou, Zuomin; Sha, Jiahao

    2015-01-01

    One of the most important changes during sperm capacitation is the enhancement of tyrosine phosphorylation. However, the mechanisms of protein tyrosine phosphorylation during sperm capacitation are not well studied. We used label-free quantitative phosphoproteomics to investigate the overall phosphorylation events during sperm capacitation in humans and identified 231 sites with increased phosphorylation levels. Motif analysis using the NetworKIN algorithm revealed that the activity of tyrosine phosphorylation kinases insulin growth factor 1 receptor (IGF1R)/insulin receptor is significantly enriched among the up-regulated phosphorylation substrates during capacitation. Western blotting further confirmed inhibition of IGF1R with inhibitors GSK1904529A and NVP-AEW541, which inhibited the increase in tyrosine phosphorylation levels during sperm capacitation. Additionally, sperm hyperactivated motility was also inhibited by GSK1904529A and NVP-AEW541 but could be up-regulated by insulin growth factor 1, the ligand of IGF1R. Thus, the IGF1R-mediated tyrosine phosphorylation pathway may play important roles in the regulation of sperm capacitation in humans and could be a target for improvement in sperm functions in infertile men. PMID:25693802

  7. Human Cortical Neural Stem Cells Expressing Insulin-Like Growth Factor-I: A Novel Cellular Therapy for Alzheimer's Disease.

    PubMed

    McGinley, Lisa M; Sims, Erika; Lunn, J Simon; Kashlan, Osama N; Chen, Kevin S; Bruno, Elizabeth S; Pacut, Crystal M; Hazel, Tom; Johe, Karl; Sakowski, Stacey A; Feldman, Eva L

    2016-03-01

    Alzheimer's disease (AD) is the most prevalent age-related neurodegenerative disorder and a leading cause of dementia. Current treatment fails to modify underlying disease pathologies and very little progress has been made to develop effective drug treatments. Cellular therapies impact disease by multiple mechanisms, providing increased efficacy compared with traditional single-target approaches. In amyotrophic lateral sclerosis, we have shown that transplanted spinal neural stem cells (NSCs) integrate into the spinal cord, form synapses with the host, improve inflammation, and reduce disease-associated pathologies. Our current goal is to develop a similar "best in class" cellular therapy for AD. Here, we characterize a novel human cortex-derived NSC line modified to express insulin-like growth factor-I (IGF-I), HK532-IGF-I. Because IGF-I promotes neurogenesis and synaptogenesis in vivo, this enhanced NSC line offers additional environmental enrichment, enhanced neuroprotection, and a multifaceted approach to treating complex AD pathologies. We show that autocrine IGF-I production does not impact the cell secretome or normal cellular functions, including proliferation, migration, or maintenance of progenitor status. However, HK532-IGF-I cells preferentially differentiate into gamma-aminobutyric acid-ergic neurons, a subtype dysregulated in AD; produce increased vascular endothelial growth factor levels; and display an increased neuroprotective capacity in vitro. We also demonstrate that HK532-IGF-I cells survive peri-hippocampal transplantation in a murine AD model and exhibit long-term persistence in targeted brain areas. In conclusion, we believe that harnessing the benefits of cellular and IGF-I therapies together will provide the optimal therapeutic benefit to patients, and our findings support further preclinical development of HK532-IGF-I cells into a disease-modifying intervention for AD.

  8. Bacterial Endotoxin Activity in Human Serum Is Associated With Dyslipidemia, Insulin Resistance, Obesity, and Chronic Inflammation

    PubMed Central

    Lassenius, Mariann I.; Pietiläinen, Kirsi H.; Kaartinen, Kati; Pussinen, Pirkko J.; Syrjänen, Jaana; Forsblom, Carol; Pörsti, Ilkka; Rissanen, Aila; Kaprio, Jaakko; Mustonen, Jukka; Groop, Per-Henrik; Lehto, Markku

    2011-01-01

    OBJECTIVE To investigate whether bacterial lipopolysaccharide (LPS) activity in human serum is associated with the components of the metabolic syndrome (MetS) in type 1 diabetic patients with various degrees of kidney disease and patients with IgA glomerulonephritis (IgAGN). RESEARCH DESIGN AND METHODS Serum LPS activity was determined with the Limulus Amoebocyte Lysate chromogenic end point assay in type 1 diabetic patients with a normal albumin excretion rate (n = 587), microalbuminuria (n = 144), macroalbuminuria (n = 173); patients with IgAGN (n = 98); and in nondiabetic control subjects (n = 345). The relationships of the LPS/HDL ratio and MetS-associated variables were evaluated with Pearson correlation. RESULTS The MetS was more prevalent in type 1 diabetic patients (48%) than in patients with IgAGN (15%). Diabetic patients with macroalbuminuria had a significantly higher serum LPS/HDL ratio than patients with IgAGN. In the normoalbuminuric type 1 diabetic group, patients in the highest LPS/HDL quartile were diagnosed as having the MetS three times more frequently than patients in the lowest quartile (69 vs. 22%; P < 0.001). High LPS activity was associated with higher serum triglyceride concentration, earlier onset of diabetes, increased diastolic blood pressure, and elevated urinary excretion of monocyte chemoattractant protein-1. CONCLUSIONS High serum LPS activity is strongly associated with the components of the MetS. Diabetic patients with kidney disease seem to be more susceptible to metabolic endotoxemia than patients with IgAGN. Bacterial endotoxins may thus play an important role in the development of the metabolic and vascular abnormalities commonly seen in obesity and diabetes-related diseases. PMID:21636801

  9. The lipogenic transcription factor ChREBP dissociates hepatic steatosis from insulin resistance in mice and humans

    PubMed Central

    Benhamed, Fadila; Denechaud, Pierre-Damien; Lemoine, Maud; Robichon, Céline; Moldes, Marthe; Bertrand-Michel, Justine; Ratziu, Vlad; Serfaty, Lawrence; Housset, Chantal; Capeau, Jacqueline; Girard, Jean; Guillou, Hervé; Postic, Catherine

    2012-01-01

    Nonalcoholic fatty liver disease (NAFLD) is associated with all features of the metabolic syndrome. Although deposition of excess triglycerides within liver cells, a hallmark of NAFLD, is associated with a loss of insulin sensitivity, it is not clear which cellular abnormality arises first. We have explored this in mice overexpressing carbohydrate responsive element–binding protein (ChREBP). On a standard diet, mice overexpressing ChREBP remained insulin sensitive, despite increased expression of genes involved in lipogenesis/fatty acid esterification and resultant hepatic steatosis (simple fatty liver). Lipidomic analysis revealed that the steatosis was associated with increased accumulation of monounsaturated fatty acids (MUFAs). In primary cultures of mouse hepatocytes, ChREBP overexpression induced expression of stearoyl-CoA desaturase 1 (Scd1), the enzyme responsible for the conversion of saturated fatty acids (SFAs) into MUFAs. SFA impairment of insulin-responsive Akt phosphorylation was therefore rescued by the elevation of Scd1 levels upon ChREBP overexpression, whereas pharmacological or shRNA-mediated reduction of Scd1 activity decreased the beneficial effect of ChREBP on Akt phosphorylation. Importantly, ChREBP-overexpressing mice fed a high-fat diet showed normal insulin levels and improved insulin signaling and glucose tolerance compared with controls, despite having greater hepatic steatosis. Finally, ChREBP expression in liver biopsies from patients with nonalcoholic steatohepatitis was increased when steatosis was greater than 50% and decreased in the presence of severe insulin resistance. Together, these results demonstrate that increased ChREBP can dissociate hepatic steatosis from insulin resistance, with beneficial effects on both glucose and lipid metabolism. PMID:22546860

  10. The Placental Variant of Human Growth Hormone Reduces Maternal Insulin Sensitivity in a Dose-Dependent Manner in C57BL/6J Mice.

    PubMed

    Liao, Shutan; Vickers, Mark H; Stanley, Joanna L; Ponnampalam, Anna P; Baker, Philip N; Perry, Jo K

    2016-03-01

    The human placental GH variant (GH-V) is secreted continuously from the syncytiotrophoblast layer of the placenta during pregnancy and is thought to play a key role in the maternal adaptation to pregnancy. Maternal GH-V concentrations are closely related to fetal growth in humans. GH-V has also been proposed as a potential candidate to mediate insulin resistance observed later in pregnancy. To determine the effect of maternal GH-V administration on maternal and fetal growth and metabolic outcomes during pregnancy, we examined the dose-response relationship for GH-V administration in a mouse model of normal pregnancy. Pregnant C57BL/6J mice were randomized to receive vehicle or GH-V (0.25, 1, 2, or 5 mg/kg · d) by osmotic pump from gestational days 12.5 to 18.5. Fetal linear growth was slightly reduced in the 5 mg/kg dose compared with vehicle and the 0.25 mg/kg groups, respectively, whereas placental weight was not affected. GH-V treatment did not affect maternal body weights or food intake. However, treatment with 5 mg/kg · d significantly increased maternal fasting plasma insulin concentrations with impaired insulin sensitivity observed at day 18.5 as assessed by homeostasis model assessment. At 5 mg/kg · d, there was also an increase in maternal hepatic GH receptor/binding protein (Ghr/Ghbp) and IGF binding protein 3 (Igfbp3) mRNA levels, but GH-V did not alter maternal plasma IGF-1 concentrations or hepatic Igf-1 mRNA expression. Our findings suggest that at higher doses, GH-V treatment can cause hyperinsulinemia and is a likely mediator of the insulin resistance associated with late pregnancy.

  11. The effect of dietary fish oil on weight gain and insulin sensitivity is dependent on APOE genotype in humanized targeted replacement mice

    PubMed Central

    Slim, Kenna E.; Vauzour, David; Tejera, Noemi; Voshol, Peter J.; Cassidy, Aedin; Minihane, Anne Marie

    2017-01-01

    We investigated the independent and interactive impact of the common APOE genotype and marine n-3 polyunsaturated fatty acids (PUFAs) on the development of obesity and associated cardiometabolic dysfunction in a murine model. Human APOE3 and APOE4 targeted replacement mice were fed either a control high-fat diet (HFD) or an HFD supplemented with 3% n-3 PUFAs from fish oil (HFD + FO) for 8 wk. We established the impact of intervention on food intake, body weight, and visceral adipose tissue (VAT) mass; plasma, lipids (cholesterol and triglycerides), liver enzymes, and adipokines; glucose and insulin during an intraperitoneal glucose tolerance test; and Glut4 and ApoE expression in VAT. HFD feeding induced more weight gain and higher plasma lipids in APOE3 compared to APOE4 mice (P < 0.05), along with a 2-fold higher insulin and impaired glucose tolerance. Supplementing APOE3, but not APOE4, animals with dietary n-3 PUFAs decreased body-weight gain, plasma lipids, and insulin (P < 0.05) and improved glucose tolerance, which was associated with increased VAT Glut4 mRNA levels (P < 0.05). Our findings demonstrate that an APOE3 genotype predisposes mice to develop obesity and its metabolic complications, which was attenuated by n-3 PUFA supplementation.—Slim, K. E., Vauzour, D., Tejera, N., Voshol, P. J., Cassidy, A., Minihane, A. M. The effect of dietary fish oil on weight gain and insulin sensitivity is dependent on APOE genotype in humanized targeted replacement mice. PMID:27895108

  12. Commercial premixed parenteral nutrition: Is it right for your institution?

    PubMed

    Miller, Sarah J

    2009-01-01

    Two-compartment premixed parenteral nutrition (PN) products are heavily promoted in the United States. These products may present safety advantages over PN solutions mixed by a local pharmacy, although clinical data to support this assertion are scarce. Multicompartment products can be labor-saving for pharmacy and therefore may be cost-effective for some institutions. Before adopting such products for use, an institution must determine that standardized PN solutions are acceptable for many or most of their patients compared with customized PN compounded specifically for individual patients. A larger selection of premixed products is available in Europe and some other parts of the world compared with the United States. Availability of a broader selection of products in the United States, including 3-compartment bags and a wider range of macronutrient concentrations and volumes, may make the use of such products more desirable in the future.

  13. Premixing quality and flame stability: A theoretical and experimental study

    NASA Technical Reports Server (NTRS)

    Radhakrishnan, K.; Heywood, J. B.; Tabaczynski, R. J.

    1979-01-01

    Models for predicting flame ignition and blowout in a combustor primary zone are presented. A correlation for the blowoff velocity of premixed turbulent flames is developed using the basic quantities of turbulent flow, and the laminar flame speed. A statistical model employing a Monte Carlo calculation procedure is developed to account for nonuniformities in a combustor primary zone. An overall kinetic rate equation is used to describe the fuel oxidation process. The model is used to predict the lean ignition and blow out limits of premixed turbulent flames; the effects of mixture nonuniformity on the lean ignition limit are explored using an assumed distribution of fuel-air ratios. Data on the effects of variations in inlet temperature, reference velocity and mixture uniformity on the lean ignition and blowout limits of gaseous propane-air flames are presented.

  14. Partially Premixed Flame (PPF) Research for Fire Safety

    NASA Technical Reports Server (NTRS)

    Puri, Ishwar K.; Aggarwal, Suresh K.; Lock, Andrew J.; Hegde, Uday

    2004-01-01

    Incipient fires typically occur after the partial premixing of fuel and oxidizer. The mixing of product species into the fuel/oxidizer mixture influences flame stabilization and fire spread. Therefore, it is important to characterize the impact of different levels of fuel/oxidizer/product mixing on flame stabilization, liftoff and extinguishment under different gravity conditions. With regard to fire protection, the agent concentration required to achieve flame suppression is an important consideration. The initial stage of an unwanted fire in a microgravity environment will depend on the level of partial premixing and the local conditions such as air currents generated by the fire itself and any forced ventilation (that influence agent and product mixing into the fire). The motivation of our investigation is to characterize these impacts in a systematic and fundamental manner.

  15. Insulin-like growth factors and their binding proteins in human colonocytes: preferential degradation of insulin-like growth factor binding protein 2 in colonic cancers.

    PubMed Central

    Michell, N. P.; Langman, M. J.; Eggo, M. C.

    1997-01-01

    We have compared the expression of insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) in ten paired samples of normal and tumour colonic tissue with regard to both mRNA and protein. We have compared sensitivity of these tissues to IGF-I using primary cultures of epithelial cells of colonic mucosa, and we have examined the production of IGFs and IGFBPs by these cells. In the tissues, IGFBP-2 mRNA was expressed in all normal and cancer samples but other IGFBPs showed variable expression. mRNAs for IGF-I were expressed in all normal and cancer tissues but IGF-II mRNA was only detected in cancer tissue (3 out of 10). Immunostaining of sections of normal and cancer tissue was negative for IGF-I and IGF-II; IGFBP-2 was positive in 2 out of 10 cancer tissues and 7 out of 10 normal tissues; IGFBP-3 was positive in 7 out of 10 cancer tissues and 7 out of 10 normal tissues; and IGFBP-4 was positive in 5 out of 10 cancer tissues and 6 out of 10 normal tissues. In the cells in culture, cancer cells showed increased incorporation of [35S]methionine into protein and [3H]thymidine into DNA (P < 0.02) when treated with IGF-I. Western blotting of serum-free conditioned media from cells in culture showed that 8 out of 10 normal and 3 out of 10 cancer cultures produced a 32-kDa immunoreactive IGFBP-2. No IGFBP-3 was secreted by any culture but 24-kDa IGFBP-4 was found in 3 out of 10 normal and 5 out of 10 cancer tissues. Because of the discrepancy between mRNA and protein expression for IGFBP-2, degradation of native IGFBPs was assessed using tissue extracts. Colon cancer extracts were able to degrade exogenous IGFBP-2, IGFBP-3 and IGFBP-4, whereas normal tissue extracts were without effect on IGFBP-2. We conclude that IGFBPs are synthesized and secreted by cells of the colonic mucosa but that proteolysis of secreted IGFBP-2 occurs in colon cancer tissue. This selective degradation may confer a growth advantage. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

  16. Cloning of the functional promoter for human insulin-like growth factor binding protein-4 gene: endogenous regulation.

    PubMed

    Dai, B; Widen, S G; Mifflin, R; Singh, P

    1997-01-01

    The majority of the colon cancers analyzed to-date express insulin-like growth factor binding protein (IGFBP)-4, and antisense inhibition of IGFBP-4 messenger RNA (mRNA) confers a growth advantage to the cells in response to endogenous and exogenous IGFs. We recently reported a significant up-regulation of IGFBP-4 expression in a human colon cancer cell line (CaCo2) on spontaneous differentiation of the cells in culture. This suggests that the expression of IGFBP-4 may be related to growth and differentiation of colon cancer cells. To study the endogenous factors involved in the transcriptional regulation of IGFBP-4, we have isolated and sequenced the human (h) IGFBP-4 promoter. The approximately 1.3 kilobase pair (kb) 5' flanking region of the IGFBP-4 gene is GC rich and possesses several potential regulatory elements. These elements include a typical TATA box with sequence TATAA, located -299 nt from the initiation ATG codon. The cap site is located 14 nt downstream of the TATA box as determined by primer extension analysis. A 1.4-kb DNA fragment including the 1.254 kb 5' flanking region of the hIGFBP-4 gene was subcloned into a luciferase reporter vector (pGL-2 basic) either in the sense (BP-4-S-pGL) (S) or antisense (BP-4-AS-pGL) (AS) (negative control) orientation, relative to the luciferase coding sequence in the vector. CaCo2 cells were transfected with either the S or the AS vectors on days 2-10 of culture; cotransfection with the SV40-beta-Galactidose (Gal) vector was used to correct for transfection efficiency. The ratio of luciferase/beta-Gal expression by CaCo2 cells transfected with the S vectors increased significantly from days 3 and 4 to days 5 and 6 of culture, followed by a sharp decline on days 7-9, resembling the pattern of endogenous expression of IGFBP-4 by the cells; the expression of luciferase by the AS vectors remained low and insignificant. These results thus suggest that the approximately 1.4 kb 5' flanking region of the IGFBP-4 gene

  17. Premixed burner experiments: Geometry, mixing, and flame structure issues

    SciTech Connect

    Gupta, A.K.; Lewis, M.J.; Gupta, M.

    1995-10-01

    This research program is exploring techniques for improved fuel-air mixing, with the aim of achieving combustor operations up to stoichiometric conditions with minimal NO x and maximum efficiency. The experimental studies involve the use of a double-concentric natural gas burner that is operable in either premixed or non-premixed modes, and the system allows systematic variation of equivalence ratio, swirl strength shear length region and flow momentum in each annulus. Flame structures formed with various combinations of swirl strengths, flow throughput and equivalence ratios in premixed mode show the significant impact of swirl flow distribution on flame structure emanating from the mixedness. This impact on flame structure is expected to have a pronounced effect on the heat release rate and the emission of NO{sub x}. Thus, swirler design and configuration remains a key factor in the quest for completely optimized combustion. Parallel numerical studies of the flow and combustion phenomena were carried out, using the RSM and thek-{epsilon} turbulence models. These results have not only indicated the strengths and limitations of CFD in performance and pollutants emission predictions, but have provided guidelines on the size and strength of the recirculation produced and the spatio-temporal structure of the combustion flowfield. The first stage of parametric studies on geometry and operational parameters at Morgan State University have culminated in the completion of a one-dimensional flow code that is integrated with a solid, virtual model of the existing premixed burner. This coupling will provide the unique opportunity to study the impact of geometry on the flowfield and vice-versa, with particular emphasis on concurrent design optimization.

  18. Lean, Premixed-Prevaporized (LPP) combustor conceptual design study

    NASA Technical Reports Server (NTRS)

    Dickman, R. A.; Dodds, W. J.; Ekstedt, E. E.

    1979-01-01

    Four combustion systems were designed and sized for the energy efficient engine. A fifth combustor was designed for the cycle and envelope of the twin-spool, high bypass ratio, high pressure ratio turbofan engine. Emission levels, combustion performance, life, and reliability assessments were made for these five combustion systems. Results of these design studies indicate that cruise NOx emission can be reduced by the use of lean, premixed-prevaporaized combustion and airflow modulation.

  19. Pulsed jet combustion generator for non-premixed charge engines

    DOEpatents

    Oppenheim, A. K.; Stewart, H. E.

    1990-01-01

    A device for introducing fuel into the head space of cylinder of non-premixed charge (diesel) engines is disclosed, which distributes fuel in atomized form in a plume, whose fluid dynamic properties are such that the compression heated air in the cylinder head space is entrained into the interior of the plume where it is mixed with and ignites the fuel in the plume interior, to thereby control combustion, particularly by use of a multiplicity of individually controllable devices per cylinder.

  20. Active Control for Statistically Stationary Turbulent PremixedFlame Simulations

    SciTech Connect

    Bell, J.B.; Day, M.S.; Grcar, J.F.; Lijewski, M.J.

    2005-08-30

    The speed of propagation of a premixed turbulent flame correlates with the intensity of the turbulence encountered by the flame. One consequence of this property is that premixed flames in both laboratory experiments and practical combustors require some type of stabilization mechanism to prevent blow-off and flashback. The stabilization devices often introduce a level of geometric complexity that is prohibitive for detailed computational studies of turbulent flame dynamics. Furthermore, the stabilization introduces additional fluid mechanical complexity into the overall combustion process that can complicate the analysis of fundamental flame properties. To circumvent these difficulties we introduce a feedback control algorithm that allows us to computationally stabilize a turbulent premixed flame in a simple geometric configuration. For the simulations, we specify turbulent inflow conditions and dynamically adjust the integrated fueling rate to control the mean location of the flame in the domain. We outline the numerical procedure, and illustrate the behavior of the control algorithm on methane flames at various equivalence ratios in two dimensions. The simulation data are used to study the local variation in the speed of propagation due to flame surface curvature.

  1. Premixed intravenous admixtures: a positive development for hospital pharmacy.

    PubMed

    Lee, H E

    1983-06-01

    The development of premixed intravenous admixtures is reviewed in a historical context, and its effects on hospital pharmacy practice are discussed. As pharmaceutical manufacturers introduce more i.v. medications in ready-to-use containers, the same complaints that were voiced by pharmacists about unit dose packaging and ready-to-dispense tablets and capsules are being aired. But premixed i.v. admixtures are a logical extension of the basic unit dose principle of providing a readily identifiable and ready-to-administer dose. The time and cost savings these products offer are needed in hospital pharmacies. Some of the disadvantages of these products--including storage and freezer space and multiplicity of administration systems--are overcome by proper planning and education of personnel. If fewer personnel are now needed to prepare i.v. admixtures, then those personnel should be used to improve patient care in other ways. The use of premixed i.v. admixtures is a positive technological advance in drug packaging. Its advantages outweight its disadvantages, and it will soon be become the universally accepted form of i.v. drug packaging.

  2. Spectral kinetic energy transfer in turbulent premixed reacting flows.

    PubMed

    Towery, C A Z; Poludnenko, A Y; Urzay, J; O'Brien, J; Ihme, M; Hamlington, P E

    2016-05-01

    Spectral kinetic energy transfer by advective processes in turbulent premixed reacting flows is examined using data from a direct numerical simulation of a statistically planar turbulent premixed flame. Two-dimensional turbulence kinetic-energy spectra conditioned on the planar-averaged reactant mass fraction are computed through the flame brush and variations in the spectra are connected to terms in the spectral kinetic energy transport equation. Conditional kinetic energy spectra show that turbulent small-scale motions are suppressed in the burnt combustion products, while the energy content of the mean flow increases. An analysis of spectral kinetic energy transfer further indicates that, contrary to the net down-scale transfer of energy found in the unburnt reactants, advective processes transfer energy from small to large scales in the flame brush close to the products. Triadic interactions calculated through the flame brush show that this net up-scale transfer of energy occurs primarily at spatial scales near the laminar flame thermal width. The present results thus indicate that advective processes in premixed reacting flows contribute to energy backscatter near the scale of the flame.

  3. Spectral Kinetic Energy Transfer Through a Premixed Flame Brush

    NASA Astrophysics Data System (ADS)

    Towery, Colin A. Z.; Poludnenko, Alexei Y.; Hamlington, Peter E.

    2014-11-01

    Turbulence-flame interactions are of fundamental importance for understanding and modeling premixed turbulent reacting flows. These interactions can result in nonlinear feedback leading to large changes in both the turbulence and flame. Recent computational studies have indicated, however, that not all scales of turbulent motion are affected equally. Small-scale motions appear to be suppressed while larger-scale motions are unaffected or even enhanced. In order to determine the scale-dependence of turbulence-flame interactions, direct numerical simulations of statistically planar, premixed flames have been performed and analyzed. Two-dimensional kinetic energy spectra, conditioned on the planar-averaged fuel mass-fraction, are measured through the flame brush and compared to both compressible and incompressible non-reacting flow spectra. Changes in the spectra with respect to fuel mass-fraction are then connected to the dynamics of the kinetic energy spectrum transport equation. Particular focus is placed on understanding triadic velocity, pressure, and dilatation interactions, including the characterization of backscatter due to heat release and compressibility. Finally, the implications of these results for modeling practical premixed combustion problems are outlined.

  4. Computations of turbulent lean premixed combustion using conditional moment closure

    NASA Astrophysics Data System (ADS)

    Amzin, Shokri; Swaminathan, Nedunchezhian

    2013-12-01

    Conditional Moment Closure (CMC) is a suitable method for predicting scalars such as carbon monoxide with slow chemical time scales in turbulent combustion. Although this method has been successfully applied to non-premixed combustion, its application to lean premixed combustion is rare. In this study the CMC method is used to compute piloted lean premixed combustion in a distributed combustion regime. The conditional scalar dissipation rate of the conditioning scalar, the progress variable, is closed using an algebraic model and turbulence is modelled using the standard k-ɛ model. The conditional mean reaction rate is closed using a first order CMC closure with the GRI-3.0 chemical mechanism to represent the chemical kinetics of methane oxidation. The PDF of the progress variable is obtained using a presumed shape with the Beta function. The computed results are compared with the experimental measurements and earlier computations using the transported PDF approach. The results show reasonable agreement with the experimental measurements and are consistent with the transported PDF computations. When the compounded effects of shear-turbulence and flame are strong, second order closures may be required for the CMC.

  5. Dissociation Between Fatty Liver and Insulin Resistance in Humans Carrying a Variant of the Patatin-Like Phospholipase 3 Gene

    PubMed Central

    Kantartzis, Konstantinos; Peter, Andreas; Machicao, Fausto; Machann, Jürgen; Wagner, Silvia; Königsrainer, Ingmar; Königsrainer, Alfred; Schick, Fritz; Fritsche, Andreas; Häring, Hans-Ulrich; Stefan, Norbert

    2009-01-01

    OBJECTIVE In a genome-wide association scan, the rs738409 C>G single nucleotide polymorphism (SNP) in the patatin-like phospholipase 3 gene (PNPLA3) was strongly associated with increased liver fat but not with insulin resistance estimated from fasting values. We investigated whether the SNP determines liver fat independently of visceral adiposity and whether it may even play a role in protecting from insulin resistance. RESEARCH DESIGN AND METHODS Liver fat was measured by 1H magnetic resonance spectroscopy and total and visceral fat by magnetic resonance tomography in 330 subjects. Insulin sensitivity was estimated during an oral glucose tolerance test and the euglycemic-hyperinsulinemic clamp (n = 222). PNPLA3 and tumor necrosis factor-α mRNA and triglyceride content were measured in liver biopsies from 16 subjects. RESULTS Liver fat correlated strongly with insulin sensitivity (P < 0.0001) independently of age, sex, total fat, and visceral fat. G allele carriers of the SNP rs738409 had higher liver fat (P < 0.0001) and an odds ratio of 2.38 (95% CI 1.37–4.20) for having fatty liver compared to C allele homozygotes. Interestingly, insulin sensitivity (oral glucose tolerance test: P = 0.99; clamp: P = 0.32), serum C-reactive protein levels, lipids, or liver enzymes (all P > 0.14) were not different among the genotypes. Additional adjustment for liver fat actually revealed increased insulin sensitivity in more obese carriers of the G allele (P = 0.01). In liver biopsies triglyceride content correlated positively with expression of the proinflammatory gene tumor necrosis factor-α in C allele homozygotes (n = 6, P = 0.027) but not in G allele carriers (n = 10, P = 0.149). CONCLUSIONS PNPLA3 may be an important key to understand the mechanisms discriminating fatty liver with and without metabolic consequences. PMID:19651814

  6. Randomized trial on the effects of a 7-d low-glycemic diet and exercise intervention on insulin resistance in older obese humans123

    PubMed Central

    Solomon, Thomas PJ; Haus, Jacob M; Kelly, Karen R; Cook, Marc D; Riccardi, Michelle; Rocco, Michael; Kashyap, Sangeeta R; Barkoukis, Hope

    2009-01-01

    Background: The optimal combination of diet and exercise that produces the greatest reversal of obesity-related insulin resistance is unknown. Objectives: We examined the effects of a combined 7-d low–glycemic index (low-GI) diet and exercise training intervention on insulin sensitivity in older obese humans. Design: Participants [n = 32; mean (±SEM) age: 66 ± 1 y; body mass index (in kg/m2): 33.8 ± 0.7] were randomly assigned to a parallel, double-blind, controlled-feeding trial and underwent supervised aerobic exercise (EX; 60 min/d at 80–85% maximum heart rate) in combination with either a low-GI (LoGI + EX: 41.1 ± 0.4) or a high-GI (HiGI + EX: 80.9 ± 0.6) diet. All meals were provided and were isocaloric to individual energy requirements. Insulin sensitivity and hepatic glucose production were assessed with a 40–mU ⋅ m−2 · min−1 hyperinsulinemic euglycemic clamp combined with a [6,6-2H2]-glucose infusion. Results: After the intervention, small decreases were observed in body weight (−1.6 ± 0.2 kg; P < 0.0001) and fat mass (−1.7 ± 0.9%; P = 0.004) in both groups. Maximal aerobic capacity (V̇O2max) also improved slightly (0.06 ± 0.02 L/min; P = 0.004). Resting systolic blood pressure, fasting glucose, insulin, triglycerides, and cholesterol all decreased after the study (all P < 0.05). Larger changes in systolic blood pressure and V̇O2max were seen in the LoGI + EX group. Insulin-stimulated glucose disposal (P < 0.001), insulin suppression of hepatic glucose production (P = 0.004), and postabsorptive fat oxidation (P = 0.03) improved equally in both groups after the intervention. Conclusions: These findings suggest that the metabolic improvements after short-term exercise training in older obese individuals are dependent on increased physical activity and are not influenced by a low-GI diet. However, a low-GI diet has added benefit in alleviating hypertension, thus reducing the risk of diabetic and vascular complications. PMID:19793849

  7. Apigenin modulates the expression levels of pro-inflammatory mediators to reduce the human insulin amyloid-induced oxidant damages in SK-N-MC cells.

    PubMed

    Amini, R; Yazdanparast, R; Ghaffari, S H

    2015-06-01

    Amyloid depositions of proteins play crucial roles in a wide variety of degenerative disorders called amyloidosis. Although the exact mechanisms involved in amyloid-mediated cytotoxicity remain unknown, increased formation of reactive oxygen species (ROS) and nitrogen species and overproduction of pro-inflammatory cytokines are believed to play key roles in the process. In that regard, we investigated the effect of apigenin, a common dietary flavonoid with high antioxidant and anti-inflammatory properties on potential factors involved in cytotoxicity of human insulin amyloids. Pretreatment of SK-N-MC neuroblastoma cells with apigenin increased cell viability and reduced the apoptosis induced by insulin fibrils. In addition, apigenin attenuated insulin fibril-induced ROS production and lipid peroxidation. Our result also demonstrated that pretreatment of the fibril-affected cells with apigenin caused an increase in catalase activity and the intracellular glutathione content along with reduction in nitric oxide production and nuclear factor κB, tumor necrosis factor α, and interleukin 6 gene expression based on real-time polymerase chain reaction evaluation. In accordance with these results, apigenin could be a promising candidate in the design of natural-based drugs for treatment or prevention of amyloid-related disorders.

  8. Effects of Probiotics and Synbiotics on Obesity, Insulin Resistance Syndrome, Type 2 Diabetes and Non-Alcoholic Fatty Liver Disease: A Review of Human Clinical Trials

    PubMed Central

    Sáez-Lara, Maria Jose; Robles-Sanchez, Candido; Ruiz-Ojeda, Francisco Javier; Plaza-Diaz, Julio; Gil, Angel

    2016-01-01

    The use of probiotics and synbiotics in the prevention and treatment of different disorders has dramatically increased over the last decade. Both probiotics and synbiotics are well known ingredients of functional foods and nutraceuticals and may provide beneficial health effects because they can influence the intestinal microbial ecology and immunity. The present study reviews the effects of probiotics and synbiotics on obesity, insulin resistance syndrome (IRS), type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD) in human randomized clinical trials. Select probiotics and synbiotics provided beneficial effects in patients with obesity, mainly affecting the body mass index and fat mass. Some probiotics had beneficial effects on IRS, decreasing the cell adhesion molecule-1 levels, and the synbiotics decreased the insulin resistance and plasma lipid levels. Moreover, select probiotics improved the carbohydrate metabolism, fasting blood glucose, insulin sensitivity and antioxidant status and also reduced metabolic stress in subjects with T2D. Some probiotics and synbiotics improved the liver and metabolic parameters in patients with NAFLD. The oral intake of probiotics and synbiotics as co-adjuvants for the prevention and treatment of obesity, IRS, T2D and NAFLD is partially supported by the data shown in the present review. However, further studies are required to understand the precise mechanism of how probiotics and synbiotics affect these metabolic disorders. PMID:27304953

  9. Effects of Probiotics and Synbiotics on Obesity, Insulin Resistance Syndrome, Type 2 Diabetes and Non-Alcoholic Fatty Liver Disease: A Review of Human Clinical Trials.

    PubMed

    Sáez-Lara, Maria Jose; Robles-Sanchez, Candido; Ruiz-Ojeda, Francisco Javier; Plaza-Diaz, Julio; Gil, Angel

    2016-06-13

    The use of probiotics and synbiotics in the prevention and treatment of different disorders has dramatically increased over the last decade. Both probiotics and synbiotics are well known ingredients of functional foods and nutraceuticals and may provide beneficial health effects because they can influence the intestinal microbial ecology and immunity. The present study reviews the effects of probiotics and synbiotics on obesity, insulin resistance syndrome (IRS), type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD) in human randomized clinical trials. Select probiotics and synbiotics provided beneficial effects in patients with obesity, mainly affecting the body mass index and fat mass. Some probiotics had beneficial effects on IRS, decreasing the cell adhesion molecule-1 levels, and the synbiotics decreased the insulin resistance and plasma lipid levels. Moreover, select probiotics improved the carbohydrate metabolism, fasting blood glucose, insulin sensitivity and antioxidant status and also reduced metabolic stress in subjects with T2D. Some probiotics and synbiotics improved the liver and metabolic parameters in patients with NAFLD. The oral intake of probiotics and synbiotics as co-adjuvants for the prevention and treatment of obesity, IRS, T2D and NAFLD is partially supported by the data shown in the present review. However, further studies are required to understand the precise mechanism of how probiotics and synbiotics affect these metabolic disorders.

  10. Premixed calcium phosphate cements: Synthesis, physical properties, and cell cytotoxicity

    PubMed Central

    Xu, Hockin H.K.; Carey, Lisa E.; Simon, Carl G.; Takagi, Shozo; Chow, Laurence C.

    2009-01-01

    Objectives Calcium phosphate cement (CPC) is a promising material for dental, periodontal, and craniofacial repairs. However, its use requires on-site powder–liquid mixing that increases the surgical placement time and raises concerns of insufficient and inhomogeneous mixing. The objective of this study was to determine a formulation of premixed CPC (PCPC) with rapid setting, high strength, and good in vitro cell viability. Methods PCPCs were formulated from CPC powder + non-aqueous liquid + gelling agent + hardening accelerator. Five PCPCs were thus developed: PCPC-Tartaric, PCPC-Malonic, PCPC-Citric, PCPC-Glycolic, and PCPC-Malic. Formulations and controls were compared for setting time, diametral tensile strength, and osteoblast cell compatibility. Results Setting time (mean ± S.D.; n = 4) for PCPC-Tartaric was 8.2 ± 0.8 min, significantly less than the 61.7 ± 1.5 min for the Premixed Control developed previously (p < 0.001). On 7th day immersion, the diametral tensile strength of PCPC-Tartaric reached 6.5 ± 0.8 MPa, higher than 4.5 ± 0.8 MPa of Premixed Control (p = 0.036). Osteoblast cells displayed a polygonal morphology and attached to the nano-hydroxyapatite crystals in the PCPCs. All cements had similar live cell density values (p = 0.126), indicating that the new PCPCs were as cell compatible as a non-premixed CPC control known to be biocompatible. Each of the new PCPCs had a cell viability that was not significantly different (p > 0.1) from that of the non-premixed CPC control. Significance PCPCs will eliminate the powder–liquid mixing during surgery and may also improve the cement performance. The new PCPCs supported cell attachment and yielded a high cell density and viability. Their mechanical strengths approached the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. These nano-crystalline hydroxyapatite cements may be useful in dental, periodontal, and craniofacial repairs. PMID:16678895

  11. Insulin Human Inhalation

    MedlinePlus

    ... such as aspirin; somatropin (Genotropin, Humatrope, Nutropin, others); sulfa antibiotics; terbutaline; and thyroid medications. Your doctor may ... may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( ...

  12. Cell factories for insulin production.

    PubMed

    Baeshen, Nabih A; Baeshen, Mohammed N; Sheikh, Abdullah; Bora, Roop S; Ahmed, Mohamed Morsi M; Ramadan, Hassan A I; Saini, Kulvinder Singh; Redwan, Elrashdy M

    2014-10-02

    The rapid increase in the number of diabetic patients globally and exploration of alternate insulin delivery methods such as inhalation or oral route that rely on higher doses, is bound to escalate the demand for recombinant insulin in near future. Current manufacturing technologies would be unable to meet the growing demand of affordable insulin due to limitation in production capacity and high production cost. Manufacturing of therapeutic recombinant proteins require an appropriate host organism with efficient machinery for posttranslational modifications and protein refolding. Recombinant human insulin has been produced predominantly using E. coli and Saccharomyces cerevisiae for therapeutic use in human. We would focus in this review, on various approaches that can be exploited to increase the production of a biologically active insulin and its analogues in E. coli and yeast. Transgenic plants are also very attractive expression system, which can be exploited to produce insulin in large quantities for therapeutic use in human. Plant-based expression system hold tremendous potential for high-capacity production of insulin in very cost-effective manner. Very high level of expression of biologically active proinsulin in seeds or leaves with long-term stability, offers a low-cost technology for both injectable as well as oral delivery of proinsulin.

  13. Structural organization of the porcine and human genes coding for a leydig cell-specific insulin-like peptide (LEY I-L) and chromosomal localization of the human gene (INSL3)

    SciTech Connect

    Burkhardt E.; Adham, I.M.; Brosig, B.; Gastmann, A.; Engel, W. ); Mattei, M.G. )

    1994-03-01

    Leydig insulin-like protein (LEY I-L) is a member of the insulin-like hormone superfamily. The LEY I-L gene (designated INSL3) is expressed exclusively in prenatal and postnatal Leydig cells. The authors report here the cloning and nucleotide sequence of porcine and human LEY I-L genes including the 5[prime] regions. Both genes consist of two exons and one intron. The organization of the LEY I-L gene is similar to that of insulin and relaxin. The transcription start site in the porcine and human LEY I-L gene is localized 13 and 14 bp upstream of the translation start site, respectively. Alignment of the 5[prime] flanking regions of both genes reveals that the first 107 nucleotides upstream of the transcription start site exhibit an overall sequence similarity of 80%. This conserved region contains a consensus TATAA box, a CAAT-like element (GAAT), and a consensus SP1 sequence (GGGCGG) at equivalent positions in both genes and therefore may play a role in regulation of expression of the LEY I-L gene. The porcine and human genome contains a single copy of the LEY I-L gene. By in situ hybridization, the human gene was assigned to bands p13.2-p12 of the short arm of chromosome 19. 25 refs., 6 figs.

  14. Molecular Basis for the Recognition and Cleavages of IGF-II, TGF-[alpha], and Amylin by Human Insulin-Degrading Enzyme

    SciTech Connect

    Guo, Qing; Manolopoulou, Marika; Bian, Yao; Schilling, Alexander B.; Tang, Wei-Jen

    2010-02-11

    Insulin-degrading enzyme (IDE) is involved in the clearance of many bioactive peptide substrates, including insulin and amyloid-{beta}, peptides vital to the development of diabetes and Alzheimer's disease, respectively. IDE can also rapidly degrade hormones that are held together by intramolecular disulfide bond(s) without their reduction. Furthermore, IDE exhibits a remarkable ability to preferentially degrade structurally similar peptides such as the selective degradation of insulin-like growth factor (IGF)-II and transforming growth factor-{alpha} (TGF-{alpha}) over IGF-I and epidermal growth factor, respectively. Here, we used high-accuracy mass spectrometry to identify the cleavage sites of human IGF-II, TGF-{alpha}, amylin, reduced amylin, and amyloid-{beta} by human IDE. We also determined the structures of human IDE-IGF-II and IDE-TGF-{alpha} at 2.3 {angstrom} and IDE-amylin at 2.9 {angstrom}. We found that IDE cleaves its substrates at multiple sites in a biased stochastic manner. Furthermore, the presence of a disulfide bond in amylin allows IDE to cut at an additional site in the middle of the peptide (amino acids 18-19). Our amylin-bound IDE structure offers insight into how the structural constraint from a disulfide bond in amylin can alter IDE cleavage sites. Together with NMR structures of amylin and the IGF and epidermal growth factor families, our work also reveals the structural basis of how the high dipole moment of substrates complements the charge distribution of the IDE catalytic chamber for the substrate selectivity. In addition, we show how the ability of substrates to properly anchor their N-terminus to the exosite of IDE and undergo a conformational switch upon binding to the catalytic chamber of IDE can also contribute to the selective degradation of structurally related growth factors.

  15. Vinegar Consumption Increases Insulin-Stimulated Glucose Uptake by the Forearm Muscle in Humans with Type 2 Diabetes

    PubMed Central

    Mitrou, Panayota; Maratou, Eirini; Lambadiari, Vaia; Dimitriadis, Panayiotis; Spanoudi, Filio; Raptis, Sotirios A.; Dimitriadis, George

    2015-01-01

    Background and Aims. Vinegar has been shown to have a glucose-lowering effect in patients with glucose abnormalities. However, the mechanisms of this effect are still obscure. The aim of this randomised, crossover study was to investigate the effect of vinegar on glucose metabolism in muscle which is the most important tissue for insulin-stimulated glucose disposal. Materials and Methods. Eleven subjects with DM2 consumed vinegar or placebo (at random order on two separate days, a week apart), before a mixed meal. Plasma glucose, insulin, triglycerides, nonesterified fatty acids (NEFA), and glycerol were measured preprandially and at 30–60 min for 300 min postprandially from the radial artery and from a forearm vein. Muscle blood flow was measured with strain-gauge plethysmography. Glucose uptake was calculated as the arteriovenous difference of glucose multiplied by blood flow. Results. Vinegar compared to placebo (1) increased forearm glucose uptake (p = 0.0357), (2) decreased plasma glucose (p = 0.0279), insulin (p = 0.0457), and triglycerides (p = 0.0439), and (3) did not change NEFA and glycerol. Conclusions. In DM2 vinegar reduces postprandial hyperglycaemia, hyperinsulinaemia, and hypertriglyceridaemia without affecting lipolysis. Vinegar's effect on carbohydrate metabolism may be partly accounted for by an increase in glucose uptake, demonstrating an improvement in insulin action in skeletal muscle. This trial is registered with Clinicaltrials.gov NCT02309424. PMID:26064976

  16. A Comparison of the Anorexic Effects of Chicken, Porcine, Human and Bovine Insulin on the Central Nervous System of Chicks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of the present study was to determine if some naturally-occurring substitutions of amino acid residues of insulin could act differentially within the central nervous system (CNS) of neonatal chicks to control ingestive behavior. Intracerebroventricular (ICV) administration of chicken insuli...

  17. Insulin Lispro Injection

    MedlinePlus

    ... unless it is used in an external insulin pump. In patients with type 2 diabetes, insulin lispro ... also can be used with an external insulin pump. Before using insulin lispro in a pump system, ...

  18. Immunohistochemical evidence for ubiquitous distribution of metalloendoprotease insulin-degrading enzyme (IDE; insulysin) in human non-malignant tissues and tumor cell lines

    PubMed Central

    Weirich, Gregor; Mengele, Karin; Yfanti, Christina; Gkazepis, Apostolos; Hellmann, Daniela; Welk, Anita; Giersig, Cecylia; Kuo, Wen-Liang; Rosner, Marsha Rich; Tang, Wei-Jen; Schmitt, Manfred

    2013-01-01

    Immunohistochemical evidence for ubiquitous distribution of metalloprotease insulin-degrading enzyme (IDE; insulysin) in human non-malignant tissues and tumor cells is presented. Immunohistochemical staining was performed on a multi-organ tissue microarray (pancreas, lung, kidney, central/peripheral nervous system, liver, breast, placenta, myocardium, striated muscle, bone marrow, thymus, spleen) and on a cell microarray encompassing 31 tumor cell lines of different origin plus trophoblast cells, and normal blood lymphocytes and granulocytes. IDE protein is expressed by all of the tissues assessed and in all of the tumor cell lines except Raji and HL-60; trophoblast cells and granulocytes but not normal lymphocytes are also IDE-positive. PMID:18783335

  19. Correction of Murine Diabetic Hyperglycaemia With A Single Systemic Administration of An AAV2/8 Vector Containing A Novel Codon Optimized Human Insulin Gene.

    PubMed

    Gan, Shu Uin; Notaridou, Maria; Fu, Zhen Ying; Lee, Kok Onn; Sia, Kian Chuan; Nathwani, Amit Chunilal; Della Peruta, Marco; Calne, Roy Yorke

    2016-01-01

    We report the correction of hyperglycemia of STZ induced diabetic mice using one intravenous systemic administration of a single stranded serotype 8 pseudotyped adeno-associated virus (ssAAV2/8) vector encoding the human proinsulin gene under a constitutive liver specific promoter. In vivo dose titration experiments were carried out and we identified an optimal range that achieved maintenance of euglycaemia or a mild diabetic condition for at least 9 months and ongoing to beyond 1 year for some animals, accompanied by human C-peptide secretion and weight gain. Further DNA codon optimization of the insulin gene construct resulted in approximately 3-10 times more human C-peptide secreted in the blood of codon optimized treated animals thereby reducing the number of vector particles required to achieve the same extent of reduction in blood glucose levels as the non-codon optimized vector. The constitutive secretion of insulin achieved with a single administration of the vector could be of therapeutic value for some diabetic patients.

  20. Differential responsiveness of luteinized human granulosa cells to gonadotropins and insulin-like growth factor I for induction of aromatase activity

    SciTech Connect

    Christman, G.M.; Randolph, J.F. Jr.; Peegel, H.; Menon, K.M. )

    1991-06-01

    The objective of this study was to examine the in vitro responsiveness of cultured luteinized human granulosa cells over time to insulin-like growth factor 1 (IGF-1), human follicle-stimulating hormone (FSH), and human chorionic gonadotropin (hCG) for the induction of aromatase activity. Granulosa cells were retrieved from preovulatory follicles in patients undergoing in vitro fertilization. Cells were cultured for a period of 72 hours or 10 days. The ability of hCG, human FSH, and/or IGF-I to induce aromatase activity was assayed by the stereospecific release of tritium from (1B-3H)androstenedione. Short-term cultures (72 hours) demonstrated a marked rise in aromatase activity in response to human FSH and IGF-I, whereas a smaller response to hCG was observed. In contrast, 10-day cultures demonstrated responsiveness predominantly to hCG rather than human FSH for the induction of aromatase activity with no remarkable effect of IGF-I. Luteinized human granulosa cells undergo a transformation from an initial human FSH and IGF-I responsive state to an hCG responsive state in long-term cultures.

  1. New forms of insulin and insulin therapies for the treatment of type 2 diabetes.

    PubMed

    Cahn, Avivit; Miccoli, Roberto; Dardano, Angela; Del Prato, Stefano

    2015-08-01

    Insulin is a common treatment option for many patients with type 2 diabetes, and is generally used late in the natural history of the disease. Its injectable delivery mode, propensity for weight gain and hypoglycaemia, and the paucity of trials assessing the risk-to-safety ratio of early insulin use are major shortcomings associated with its use in patients with type 2 diabetes. Development of new insulins-such as insulin analogues, including long-acting and short-acting insulins-now provide alternative treatment options to human insulin. These novel insulin formulations and innovative insulin delivery methods, such as oral or inhaled insulin, have been developed with the aim to reduce insulin-associated hypoglycaemia, lower intraindividual pharmacokinetic and pharmacodynamic variability, and improve imitation of physiological insulin release. Availability of newer glucose-lowering drugs (such as glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, and sodium-glucose co-transporter-2 inhibitors) also offers the opportunity for combination treatment; the results of the first trials in this area of research suggest that such treatment might lead to use of reduced insulin doses, less weight gain, and fewer hypoglycaemic episodes than insulin treatment alone. These and future developments will hopefully offer better opportunities for individualisation of insulin treatment for patients with type 2 diabetes.

  2. Dry low NOx combustion system with pre-mixed direct-injection secondary fuel nozzle

    SciTech Connect

    Zuo, Baifang; Johnson, Thomas; Ziminsky, Willy; Khan, Abdul

    2013-12-17

    A combustion system includes a first combustion chamber and a second combustion chamber. The second combustion chamber is positioned downstream of the first combustion chamber. The combustion system also includes a pre-mixed, direct-injection secondary fuel nozzle. The pre-mixed, direct-injection secondary fuel nozzle extends through the first combustion chamber into the second combustion chamber.

  3. 21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Nitrites and/or nitrates in curing premixes. 170... and Decisions § 170.60 Nitrites and/or nitrates in curing premixes. (a) Nitrites and/or nitrates are.... (b) Nitrites and/or nitrates, when packaged separately from flavoring and seasoning in...

  4. 21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Nitrites and/or nitrates in curing premixes. 170... and Decisions § 170.60 Nitrites and/or nitrates in curing premixes. (a) Nitrites and/or nitrates are.... (b) Nitrites and/or nitrates, when packaged separately from flavoring and seasoning in...

  5. 21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Nitrites and/or nitrates in curing premixes. 170... and Decisions § 170.60 Nitrites and/or nitrates in curing premixes. (a) Nitrites and/or nitrates are.... (b) Nitrites and/or nitrates, when packaged separately from flavoring and seasoning in...

  6. 21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Nitrites and/or nitrates in curing premixes. 170.60... Decisions § 170.60 Nitrites and/or nitrates in curing premixes. (a) Nitrites and/or nitrates are food.... (b) Nitrites and/or nitrates, when packaged separately from flavoring and seasoning in...

  7. Construction of engineering adipose-like tissue in vivo utilizing human insulin gene-modified umbilical cord mesenchymal stromal cells with silk fibroin 3D scaffolds.

    PubMed

    Li, Shi-Long; Liu, Yi; Hui, Ling

    2015-12-01

    We evaluated the use of a combination of human insulin gene-modified umbilical cord mesenchymal stromal cells (hUMSCs) with silk fibroin 3D scaffolds for adipose tissue engineering. In this study hUMSCs were isolated and cultured. HUMSCs infected with Ade-insulin-EGFP were seeded in fibroin 3D scaffolds with uniform 50-60 µm pore size. Silk fibroin scaffolds with untransfected hUMSCs were used as control. They were cultured for 4 days in adipogenic medium and transplanted under the dorsal skins of female Wistar rats after the hUMSCs had been labelled with chloromethylbenzamido-1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (CM-Dil). Macroscopical impression, fluorescence observation, histology and SEM were used for assessment after transplantation at 8 and 12 weeks. Macroscopically, newly formed adipose tissue was observed in the experimental group and control group after 8 and 12 weeks. Fluorescence observation supported that the formed adipose tissue originated from seeded hUMSCs rather than from possible infiltrating perivascular tissue. Oil red O staining of newly formed tissue showed that there was substantially more tissue regeneration in the experimental group than in the control group. SEM showed that experimental group cells had more fat-like cells, whose volume was larger than that of the control group, and degradation of the silk fibroin scaffold was greater under SEM observation. This study provides significant evidence that hUMSCs transfected by adenovirus vector have good compatibility with silk fibroin scaffold, and adenoviral transfection of the human insulin gene can be used for the construction of tissue-engineered adipose.

  8. Nitrosative stress and pathogenesis of insulin resistance.

    PubMed

    Kaneki, Masao; Shimizu, Nobuyuki; Yamada, Daisuke; Chang, Kyungho

    2007-03-01

    Insulin resistance is a major causative factor for type 2 diabetes and is associated with increased risk of cardiovascular disease. Despite intense investigation for a number of years, molecular mechanisms underlying insulin resistance remain to be determined. Recently, chronic inflammation has been highlighted as a culprit for obesity-induced insulin resistance. Nonetheless, upstream regulators and downstream effectors of chronic inflammation in insulin resistance remain unclarified. Inducible nitric oxide synthase (iNOS), a mediator of inflammation, has emerged as an important player in insulin resistance. Obesity is associated with increased iNOS expression in insulin-sensitive tissues in rodents and humans. Inhibition of iNOS ameliorates obesity-induced insulin resistance. However, molecular mechanisms by which iNOS mediates insulin resistance remain largely unknown. Protein S-nitrosylation, a covalent attachment of NO moiety to thiol sulfhydryls, has emerged as a major mediator of a broad array of NO actions. S-nitrosylation is elevated in patients with type 2 diabetes, and increased S-nitrosylation of insulin signaling molecules, including insulin receptor, insulin receptor substrate-1, and Akt/PKB, has been shown in skeletal muscle of obese, diabetic mice. Akt/PKB is reversibly inactivated by S-nitrosylation. Based on these findings, S-nitrosylation has recently been proposed to play an important role in the pathogenesis of insulin resistance.

  9. Insulin pump safety meeting: summary report.

    PubMed

    Klonoff, David C; Reyes, Juliet S

    2009-03-01

    Diabetes Technology Society convened a panel of insulin pump experts in Bethesda, Maryland, on November 12, 2008, at the request of the Food and Drug Administration. The group consisted of physicians, nurses, diabetes educators, and engineers from across the United States. The panel members (1) discussed safety features of insulin pump therapy and (2) recommended adjustments to current insulin pump design and use to enhance overall safety. Software and hardware features of insulin pumps were analyzed from engineering, medical, nursing, and pump-user perspectives. The meeting was divided into four sections: (1) Engineering Safety-Designing Software and Hardware for Insulin Pump Therapy; (2) Patient Safety-Selecting Patients and Clinical Settings for Insulin Pump Use; (3) Clinical Safety-Determining and Delivering Insulin Dosages Using Insulin Pump Therapy; and (4) Personal Experiences-A Panel Discussion about Insulin Pump Safety. Six aspects of insulin pump technology were noted to present potential safety problems: (1) software, (2) wireless communication, (3) hardware, (4) alarms, (5) human factors, and (6) bolus-dose calculation. There was consensus among meeting participants that insulin pump therapy is beneficial in patients of all ages and that insulin pump safety must be assured through careful regulation.

  10. TREATMENT OF TYPE 2 DIABETES WITH BIPHASIC INSULIN ANALOGUES

    PubMed Central

    Rizvi, Ali A.

    2016-01-01

    The majority of patients with Type 2 diabetes require insulin therapy for treating hyperglycaemia. There are several regimens available for insulin initiation and maintenance. Insulin analogues have been developed to mimic normal physiology as closely as possible. Biphasic analogues can target both fasting and postprandial hyperglycaemia, with the added advantage of being premixed and thus convenient for the patient. A practical and feasible option is to initiate insulin with one or more biphasic preparations at mealtimes, thus providing both basal and prandial coverage. Individual titration of dose and frequency of daily injections with biphasic insulin preparations has the potential for improving glycaemic control with a high degree of patient acceptance. Drawbacks include a more rigid regimen, a relative lack of flexibility, and a somewhat higher degree of glycaemic variability and hypoglycaemia when compared to multiple daily basal-bolus injections. Awareness of the advantages and limitations of biphasic insulin analogues can assist clinicians in their appropriate use for the treatment of patients with Type 2 diabetes. PMID:27918600

  11. RANS/PDF and LES/FDF for prediction of turbulent premixed flames

    NASA Astrophysics Data System (ADS)

    Yilmaz, Server Levent

    Probability density function (PDF) and filtered density function (FDF) methodologies are developed and implemented, respectively, for Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) of turbulent premixed flames. RANS predictions are made of a lean premixed bluff-body flame via the joint velocity-scalar-frequency PDF model. LES of a premixed Bunsen-burner flame is conducted via the scalar FDF methodology. Both simulations employ finite rate kinetics via a reduced methane chemistry mechanism to account for combustion. Prediction results are compared with experimental data, and are shown to capture some of the intricate physics of turbulent premixed combustion. Keywords. large eddy simulation, filtered density function, Reynolds-averaged Navier-Stokes, probability density function, turbulent reacting flows, lean premixed combustion.

  12. Insulin-Mediated Downregulation of Apolipoprotein A-I Gene in Human Hepatoma Cell Line HepG2: The Role of Interaction Between FOXO1 and LXRβ Transcription Factors.

    PubMed

    Shavva, Vladimir S; Bogomolova, Alexandra M; Nikitin, Artemy A; Dizhe, Ella B; Tanyanskiy, Dmitry A; Efremov, Alexander M; Oleinikova, Galina N; Perevozchikov, Andrej P; Orlov, Sergey V

    2017-02-01

    Apolipoprotein A-I (ApoA-I) is a key component of high density lipoproteins which possess anti-atherosclerotic and anti-inflammatory properties. Insulin is a crucial mediator of the glucose and lipid metabolism that has been implicated in atherosclerotic and inflammatory processes. Important mediators of insulin signaling such as Liver X Receptors (LXRs) and Forkhead Box A2 (FOXA2) are known to regulate apoA-I expression in liver. Forkhead Box O1 (FOXO1) is a well-known target of insulin signaling and a key mediator of oxidative stress response. Low doses of insulin were shown to activate apoA-I expression in human hepatoma HepG2 cells. However, the detailed mechanisms for these processes are still unknown. We studied the possible involvement of FOXO1, FOXA2, LXRα, and LXRβ transcription factors in the insulin-mediated regulation of apoA-I expression. Treatment of HepG2 cells with high doses of insulin (48 h, 100 nM) suppresses apoA-I gene expression. siRNAs against FOXO1, FOXA2, LXRβ, or LXRα abrogated this effect. FOXO1 forms a complex with LXRβ and insulin treatment impairs FOXO1/LXRβ complex binding to hepatic enhancer and triggers its nuclear export. Insulin as well as LXR ligand TO901317 enhance the interaction between FOXA2, LXRα, and hepatic enhancer. These data suggest that high doses of insulin downregulate apoA-I gene expression in HepG2 cells through redistribution of FOXO1/LXRβ complex, FOXA2, and LXRα on hepatic enhancer of apoA-I gene. J. Cell. Biochem. 118: 382-396, 2017. © 2016 Wiley Periodicals, Inc.

  13. A programmable synthetic lineage-control network that differentiates human IPSCs into glucose-sensitive insulin-secreting beta-like cells

    PubMed Central

    Saxena, Pratik; Heng, Boon Chin; Bai, Peng; Folcher, Marc; Zulewski, Henryk; Fussenegger, Martin

    2016-01-01

    Synthetic biology has advanced the design of standardized transcription control devices that programme cellular behaviour. By coupling synthetic signalling cascade- and transcription factor-based gene switches with reverse and differential sensitivity to the licensed food additive vanillic acid, we designed a synthetic lineage-control network combining vanillic acid-triggered mutually exclusive expression switches for the transcription factors Ngn3 (neurogenin 3; OFF-ON-OFF) and Pdx1 (pancreatic and duodenal homeobox 1; ON-OFF-ON) with the concomitant induction of MafA (V-maf musculoaponeurotic fibrosarcoma oncogene homologue A; OFF-ON). This designer network consisting of different network topologies orchestrating the timely control of transgenic and genomic Ngn3, Pdx1 and MafA variants is able to programme human induced pluripotent stem cells (hIPSCs)-derived pancreatic progenitor cells into glucose-sensitive insulin-secreting beta-like cells, whose glucose-stimulated insulin-release dynamics are comparable to human pancreatic islets. Synthetic lineage-control networks may provide the missing link to genetically programme somatic cells into autologous cell phenotypes for regenerative medicine. PMID:27063289

  14. Acute insulin responses to glucose and arginine as predictors of beta-cell secretory capacity in human islet transplantation.

    PubMed

    Rickels, Michael R; Naji, Ali; Teff, Karen L

    2007-11-27

    Islet transplantation for type 1 diabetes can enable the achievement of near-normal glycemic control without severe hypoglycemic episodes. How much an islet (beta-cell) graft may be contributing to glycemic control can be quantified by stimulatory tests of insulin (or C-peptide) secretion. Glucose-potentiation of arginine-induced insulin secretion provides a measure of functional beta-cell mass, the beta-cell secretory capacity, as either AIR(pot) or AIR(max), but requires conduct of a hyperglycemic clamp. We sought to determine whether acute insulin responses to intravenous glucose (AIR(glu)) or arginine (AIR(arg)) could predict beta-cell secretory capacity in islet recipients. AIR(arg) was a better predictor of both AIR(pot) and AIR(max) (n=10, r2=0.98, P<0.0001 and n=7, r2=0.97, P<0.0001) than was AIR(glu) (n=9, r2=0.78, P=0.002 and n=6, r2=0.76, P=0.02). Also, the measures of beta-cell secretory capacity were highly correlated (n=7, r2=0.98, P<0.0001). These results support the use of AIR(arg) as a surrogate indicator of beta-cell secretory capacity in islet transplantation.

  15. Human cytokines interleukin (IL)-3 and IL-6 affect the growth and insulin binding of the unicellular organism Tetrahymena.

    PubMed

    Csaba, G; Kovács, P; Falus, A

    1995-11-01

    Interleukin (IL)-3 and IL-6 significantly increase the growth rate of the unicellular organism, Tetrahymena. The effect elicited by IL-3 is long lasting as it was also detectable after 20 generations. Effect of IL-6 was detectable as long as the substance was present in the cell culture. Pretreatment with IL-3 did not enhance the proliferative response to subsequent IL-3 treatment, but the second exposure to IL-3 considerably depressed the active proliferation of Tetrahymena cells. However, a positive 'priming effect' elicited by IL-6 resulted in an increased growth rate following repeated IL-6 stimulation. Insulin binding to the plasma membrane of Tetrahymena was increased by IL-6 but not by IL-3 after 24 hours, and this enhancement appeared even after one hour incubation. If the cells were pretreated with insulin, IL-6 did not influence insulin binding, while an inhibition by IL-3 was observed. These results direct attention to the similarities of actions induced by IL-3 and IL-6 at different levels of phylogeny probably due to the presence of cytokine receptor-like structures on this unicellular organism.

  16. Effects of cake made from whole soy powder on postprandial blood glucose and insulin levels in human subjects.

    PubMed

    Oku, Tsuneyuki; Nakamura, Mariko; Takasugi, Ayako; Hashiguchi-Ishiguro, Michiru; Tanabe, Kenichi; Nakamura, Sadako

    2009-01-01

    We investigated the glycemic index (GI) and the insulinemic index (II) of cake made from whole soy powder (SBC) and the suppressive effects of SBC on the postprandial blood glucose and insulin by other carbohydrate foods. Furthermore, breath hydrogen excretion was simultaneously investigated. Twenty subjects were given 114 g SBC, 144 g cooked paddy-rice, and 60 g SBC with 144 g cooked paddy-rice in random order using a within-subject, repeated-measures design. Blood and end-expiratory gas were collected at the indicated periods after ingestion. The GI and the II of SBC were 22+/-6 and 48+/-29, respectively. The elevation of blood glucose by cooked paddy-rice was significantly suppressed by the addition of 60 g SBC, although the insulin secretion did not decrease. Breath hydrogen excretion by the addition of SBC to 144 g cooked paddy-rice was not significantly increased in comparison with cooked paddy-rice alone. SBC was of low GI and low II, but the postprandial insulin secretion in response to cooked paddy-rice was not suppressed.

  17. Field Effects of Buoyancy on Lean Premixed Turbulent Flames

    NASA Technical Reports Server (NTRS)

    Cheng, R. K.; Johnson, M. R.; Greenberg, P. S.; Wernet, M. P.

    2003-01-01

    The study of field effects of buoyancy on premixed turbulent flames is directed towards the advancement of turbulent combustion theory and the development of cleaner combustion technologies. Turbulent combustion is considered the most important unsolved problem in combustion science and laboratory studies of turbulence flame processes are vital to theoretical development. Although buoyancy is dominant in laboratory flames, most combustion models are not yet capable to consider buoyancy effects. This inconsistency has impeded the validation of theories and numerical simulations with experiments. Conversely, the understanding of buoyancy effects is far too limited to help develop buoyant flame models. Our research is also relevant to combustion technology because lean premixed combustion is a proven method to reduce the formation of oxides of nitrogen (NOx). In industrial lean premixed combustion systems, their operating conditions make them susceptible to buoyancy thus affecting heat distribution, emissions, stability, flashback and blowoff. But little knowledge is available to guide combustion engineers as to how to avoid or overcome these problems. Our hypothesis is that through its influence on the mean pressure field, buoyancy has direct and indirect effects on local flame/turbulence interactions. Although buoyancy acts on the hot products in the farfield the effect is also felt in the nearfield region upstream of the flame. These changes also influence the generation and dissipation of turbulent kinetic energy inside the flame brush and throughout the flowfield. Moreover, the plume of an open flame is unstable and the periodic fluctuations make additional contributions to flame front dynamics in the farfield. Therefore, processes such as flame wrinkling, flow acceleration due to heat release and flame- generated vorticity are all affected. Other global flame properties (e.g. flame stabilization limits and flame speed) may all be coupled to buoyancy. This

  18. Combustion mechanism of ultralean rotating counterflow twin premixed flame

    NASA Astrophysics Data System (ADS)

    Uemichi, Akane; Nishioka, Makihito

    2015-01-01

    In our previous numerical studies [Nishioka Makihito, Zhenyu Shen, and Akane Uemichi. "Ultra-lean combustion through the backflow of burned gas in rotating counterflow twin premixed flames." Combustion and Flame 158.11 (2011): 2188-2198. Uemichi Akane, and Makihito Nishioka. "Numerical study on ultra-lean rotating counterflow twin premixed flame of hydrogen-air." Proceedings of the Combustion Institute 34.1 (2013): 1135-1142]. we found that methane- and hydrogen-air rotating counterflow twin flames (RCTF) can achieve ultralean combustion when backward flow of burned gas occurs due to the centrifugal force created by rotation. In this study, we investigated the mechanisms of ultralean combustion in these flames by the detailed numerical analyses of the convective and diffusive transport of the main species. We found that, under ultralean conditions, the diffusive transport of fuel exceeds its backward convective transport in the flame zone, which is located on the burned-gas side of the stagnation point. In contrast, the relative magnitudes of diffusive and convective transport for oxygen are reversed compared to those for the fuel. The resulting flows for fuel and oxygen lead to what we call a 'net flux imbalance'. This net flux imbalance increases the flame temperature and concentrations of active radicals. For hydrogen-air RCTF, a very large diffusivity of hydrogen enhances the net flux imbalance, significantly increasing the flame temperature. This behaviour is intrinsic to a very lean premixed flame in which the reaction zone is located in the backflow of its own burned gas.

  19. Anti-insulin antibody test

    MedlinePlus

    Insulin antibodies - serum; Insulin Ab test; Insulin resistance - insulin antibodies; Diabetes - insulin antibodies ... Normally, there are no antibodies against insulin in your blood. ... different laboratories. Some labs use different measurements or ...

  20. Jet flow and premixed jet flame control by plasma swirler

    NASA Astrophysics Data System (ADS)

    Li, Gang; Jiang, Xi; Zhao, Yujun; Liu, Cunxi; Chen, Qi; Xu, Gang; Liu, Fuqiang

    2017-04-01

    A swirler based on dielectric barrier discharge plasma actuators is designed and its effectiveness in both jet flow and premixed jet flame control is demonstrated. In contrast to traditional spanwise-oriented actuators, plasma actuators are placed along the axial direction of the injector to induce a circumferential velocity to the main flow and create a swirl flow without any insertion or moving part. In the DBD plasma swirl injector, the discharge does not ignite the mixture nor does it induce flashback. Flame visualization is obtained by cameras while velocity profiles are obtained by Laser Doppler Anemometry measurements. The results obtained indicate the effectiveness of the new design.

  1. Heat Transfer Effects on a Fully Premixed Methane Impinging Flame

    DTIC Science & Technology

    2014-10-30

    HEAT TRANSFER EFFECTS ON A FULLY PREMIXED METHANE IMPINGING FLAME D. Mira1, M. Zavala1, M. Avila1, H. Owen1, J.C. Cajas1, G. Houzeaux1 and M...to evaluate the numeri- cal algorithms and the effects of the thermal coupling with the flow dynamics is the case of a jet flame im- pinging on a...investigate the heat transfer effects and flow dynamics of an imping- ing flame with low nozzle-to-plate distance when the solid plate is considered non

  2. Response mechanisms of attached premixed flames subjected to harmonic forcing

    NASA Astrophysics Data System (ADS)

    Shreekrishna

    The persistent thrust for a cleaner, greener environment has prompted air pollution regulations to be enforced with increased stringency by environmental protection bodies all over the world. This has prompted gas turbine manufacturers to move from nonpremixed combustion to lean, premixed combustion. These lean premixed combustors operate quite fuel-lean compared to the stochiometric, in order to minimize CO and NOx productions, and are very susceptible to oscillations in any of the upstream flow variables. These oscillations cause the heat release rate of the flame to oscillate, which can engage one or more acoustic modes of the combustor or gas turbine components, and under certain conditions, lead to limit cycle oscillations. This phenomenon, called thermoacoustic instabilities, is characterized by very high pressure oscillations and increased heat fluxes at system walls, and can cause significant problems in the routine operability of these combustors, not to mention the occasional hardware damages that could occur, all of which cumulatively cost several millions of dollars. In a bid towards understanding this flow-flame interaction, this research works studies the heat release response of premixed flames to oscillations in reactant equivalence ratio, reactant velocity and pressure, under conditions where the flame preheat zone is convectively compact to these disturbances, using the G-equation. The heat release response is quantified by means of the flame transfer function and together with combustor acoustics, forms a critical component of the analytical models that can predict combustor dynamics. To this end, low excitation amplitude (linear) and high excitation amplitude (nonlinear) responses of the flame are studied in this work. The linear heat release response of lean, premixed flames are seen to be dominated by responses to velocity and equivalence ratio fluctuations at low frequencies, and to pressure fluctuations at high frequencies which are in the

  3. Premixer assembly for mixing air and fuel for combustion

    SciTech Connect

    York, William David; Johnson, Thomas Edward; Keener, Christopher Paul

    2016-12-13

    A premixer assembly for mixing air and fuel for combustion includes a plurality of tubes disposed at a head end of a combustor assembly. Also included is a tube of the plurality of tubes, the tube including an inlet end and an outlet end. Further included is at least one non-circular portion of the tube extending along a length of the tube, the at least one non-circular portion having a non-circular cross-section, and the tube having a substantially constant cross-sectional area along its length

  4. Structure of the human glucokinase gene and identification of a missense mutation in a Japanese patient with early-onset non-insulin-dependent diabetes mellitus

    SciTech Connect

    Sakura, Hiroshi; Eto, Kazuhiro; Ueno, Hirohisa; Yazaki, Yoshio; Kadowaki, Takashi ); Kadowaki, Hiroko; Simokawa, Kotaro; Akanuma, Yasuo ); Koda, Naoya; Fukushima, Yoshimitsu )

    1992-12-01

    Glucokinase is thought to play a glucose-sensor role in the pancreas, and abnormalities in its structure, function, and regulation can induce diabetes. The authors isolated the human glucokinase gene, and determined its genomic structure including exon-intron boundaries. Structure of the glucokinase gene in human was very similar to that in rat. Then, by screening Japanese diabetic patients using polymerase chain reaction - single strand conformation polymorphism (PCR-SSCP) and direct-sequencing strategies, they identified a missense mutation substituting ariginine (AGG) for glycine (GGG) at position 261 in exon 7 of the glucokinase gene in a patient with early-onset non-insulin-dependent diabetes (NIDDM). 12 refs., 3 figs., 2 tabs.

  5. Autoreactive T cells specific for insulin B:11-23 recognize a low-affinity peptide register in human subjects with autoimmune diabetes.

    PubMed

    Yang, Junbao; Chow, I-Ting; Sosinowski, Tomasz; Torres-Chinn, Nadia; Greenbaum, Carla J; James, Eddie A; Kappler, John W; Davidson, Howard W; Kwok, William W

    2014-10-14

    Previous studies in type 1 diabetes (T1D) in the nonobese diabetic mouse demonstrated that a crucial insulin epitope (B:9-23) is presented to diabetogenic CD4 T cells by IA(g7) in a weakly bound register. The importance of antigenic peptides with low-affinity HLA binding in human autoimmune disease remains less clear. The objective of this study was to investigate T-cell responses to a low-affinity self-epitope in subjects with T1D. HLA-DQ8 tetramers loaded with a modified insulin peptide designed to improve binding the low-affinity register were used to visualize T-cell responses following in vitro stimulation. Positive responses were only detectable in T1D patients. Because the immunogenic register of B:9-23 presented by DQ8 has not been conclusively demonstrated, T-cell assays using substituted peptides and DQ8 constructs engineered to express and present B:9-23 in fixed binding registers were used to determine the immunogenic register of this peptide. Tetramer-positive T-cell clones isolated from T1D subjects that responded to stimulation by B:11-23 peptide and denatured insulin protein were conclusively shown to recognize B:11-23 bound to HLA-DQ8 in the low-affinity register 3. These T cells also responded to homologous peptides derived from microbial antigens, suggesting that their initial priming could occur via molecular mimicry. These results are in accord with prior observations from the nonobese diabetic mouse model, suggesting a mechanism shared by mouse and man through which T cells that recognize a weakly bound peptide can circumvent tolerance mechanisms and play a role in the initiation of autoimmune diseases, such as T1D.

  6. Insulin-like growth factor I activates the invasion suppressor function of E-cadherin in MCF-7 human mammary carcinoma cells in vitro.

    PubMed Central

    Bracke, M. E.; Vyncke, B. M.; Bruyneel, E. A.; Vermeulen, S. J.; De Bruyne, G. K.; Van Larebeke, N. A.; Vleminckx, K.; Van Roy, F. M.; Mareel, M. M.

    1993-01-01

    The calcium-dependent cell-cell adhesion molecule E-cadherin has been shown to counteract invasion of epithelial neoplastic cells. Using three monoclonal antibodies, we have demonstrated the presence of E-cadherin at the surface of human MCF-7/6 mammary carcinoma cells by indirect immunofluorescence coupled to flow cytometry and by immunocytochemistry. Nevertheless, MCF-7/6 cells failed to aggregate in a medium containing 1.25 mM CaCl2, and they were invasive after confrontation with embryonic chick heart fragments in organ culture. Treatment of MCF-7/6 cells with 0.5 microgram ml-1 insulin-like growth factor I (IGF-I) led to homotypic aggregation within 5 to 10 min and inhibited invasion in vitro during at least 8 days. The effect of IGF-I on cellular aggregation was insensitive to cycloheximide. However, monoclonal antibodies that interfered with the function of either the IGF-I receptor (alpha IR3) or E-cadherin (HECD-1, MB2) blocked the effect of IGF-I on aggregation. The effects of IGF-I on aggregation and on invasion could be mimicked by 1 microgram ml-1 insulin, but not by 0.5 microgram ml-1 IGF-II. The insulin effects were presumably not mediated by the IGF-I receptor, since they could not be blocked by an antibody against this receptor (alpha IR3). Our results indicate that IGF-I activates the invasion suppressor role of E-cadherin in MCF-7/6 cells. Images Figure 1 Figure 3 Figure 4 Figure 7 Figure 8 Figure 10 PMID:8347483

  7. Human interleukin-1 beta induced stimulation of insulin release from rat pancreatic islets is accompanied by an increase in mitochondrial oxidative events.

    PubMed

    Eizirik, D L; Sandler, S

    1989-11-01

    Acute exposure of pancreatic islets to interleukin-1 beta results in an increase in insulin release, while an extension of the exposure time induces a functional suppression and eventually, destruction of the B-cells. We have recently suggested that the interleukin-1 beta induced inhibition of islet function is mediated through an impairment in oxidative metabolism. The aim of the current study was to investigate if the acute, stimulatory effects of interleukin-1 beta on islet function could also be related to changes in the substrate metabolism. For this purpose, rat islets were exposed for 90-120 min to 30 pmol/l human recombinant interleukin-1 beta (biological activity of 2.5 U/ml) and their function and metabolism characterized during this period. The cytokine did not increase insulin release in the presence of 1.7 or 5.5 mmol/l glucose but in both the presence of 16.7 mmol/l glucose or 10 mmol/l leucine + 2 mmol/l glutamine there was a 50% increase in insulin release. Interleukin-1 beta exposure increased the oxidation of D-[U-14C]glucose at 5.5 mmol/l glucose by 25% and at 16.7 mmol/l glucose by 60%. Carbohydrate and amino acid metabolism were further examined in the presence of D-[5-3H]glucose, D-[6-14C]glucose, [1-14C]pyruvate, L-[U-14C]glutamine, L-[U-14C]leucine and L-[1-14C]leucine. There was no difference between control islets and interleukin-1 beta exposed islets in terms of D-[5-3H]glucose utilization or [1-14C]pyruvate decarboxylation, but the oxidation of D-[6-14C]glucose was increased by 64% in the interleukin-1 beta exposed islets.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Temperature response of turbulent premixed flames to inlet velocity oscillations

    NASA Astrophysics Data System (ADS)

    Ayoola, B.; Hartung, G.; Armitage, C. A.; Hult, J.; Cant, R. S.; Kaminski, C. F.

    2009-01-01

    Flame-turbulence interactions are at the heart of modern combustion research as they have a major influence on efficiency, stability of operation and pollutant emissions. The problem remains a formidable challenge, and predictive modelling and the implementation of active control measures both rely on further fundamental measurements. Model burners with simple geometry offer an opportunity for the isolation and detailed study of phenomena that take place in real-world combustors, in an environment conducive to the application of advanced laser diagnostic tools. Lean premixed combustion conditions are currently of greatest interest since these are able to provide low NO x and improved increased fuel economy, which in turn leads to lower CO2 emissions. This paper presents an experimental investigation of the response of a bluff-body-stabilised flame to periodic inlet fluctuations under lean premixed turbulent conditions. Inlet velocity fluctuations were imposed acoustically using loudspeakers. Spatially resolved heat release rate imaging measurements, using simultaneous planar laser-induced fluorescence (PLIF) of OH and CH2O, have been performed to explore the periodic heat release rate response to various acoustic forcing amplitudes and frequencies. For the first time we use this method to evaluate flame transfer functions and we compare these results with chemiluminescence measurements. Qualitative thermometry based on two-line OH PLIF was also used to compare the periodic temperature distribution around the flame with the periodic fluctuation of local heat release rate during acoustic forcing cycles.

  9. Establishing bioequivalence of veterinary premixes (Type A medicated articles).

    PubMed

    Hunter, R P; Lees, P; Concordet, D; Toutain, P-L

    2012-04-01

    a) Key issues concerning Premix (Type A medicated articles) Bioequivalence evaluations: 1) This is a complex issue concerning both route of administration and formulation. 2) If the animal is not at the bunk/trough, the animal is not self-administering (eating medicated feed), thus there can be no drug absorption. b) Differing opinions among scientists and regulatory authorities/expert bodies regarding: 1) No harmonization on how to design, conduct, and interpret in vivo studies. 2) Applicability of biowaivers to Type A (premix) products. 3) Why are topdress and complete feed considered differently? Are they different formulations or different routes of administration? 4) Single dose vs. multi-dose studies. 5) What is the final formulation? c) What are the next steps: 1) Harmonize current bioequivalence guidelines through the VICH process. 2) Determine the applicability/non-applicability of the Biopharmaceutical Classification System (BCS). 3) Establish the Total Mixed Ration (i.e. formulation) effects. 4) Define the test subject (individual, pen, etc.).

  10. Vorticity isotropy in high Karlovitz number premixed flames

    NASA Astrophysics Data System (ADS)

    Bobbitt, Brock; Blanquart, Guillaume

    2016-10-01

    The isotropy of the smallest turbulent scales is investigated in premixed turbulent combustion by analyzing the vorticity vector in a series of high Karlovitz number premixed flame direct numerical simulations. It is found that increasing the Karlovitz number and the ratio of the integral length scale to the flame thickness both reduce the level of anisotropy. By analyzing the vorticity transport equation, it is determined that the vortex stretching term is primarily responsible for the development of any anisotropy. The local dynamics of the vortex stretching term and vorticity resemble that of homogeneous isotropic turbulence to a greater extent at higher Karlovitz numbers. This results in small scale isotropy at sufficiently high Karlovitz numbers and supports a fundamental similarity of the behavior of the smallest turbulent scales throughout the flame and in homogeneous isotropic turbulence. At lower Karlovitz numbers, the vortex stretching term and the vorticity alignment in the strain-rate tensor eigenframe are altered by the flame. The integral length scale has minimal impact on these local dynamics but promotes the effects of the flame to be equal in all directions. The resulting isotropy in vorticity does not reflect a fundamental similarity between the smallest turbulent scales in the flame and in homogeneous isotropic turbulence.

  11. Finite amplitude wave interaction with premixed laminar flames

    NASA Astrophysics Data System (ADS)

    Aslani, Mohamad; Regele, Jonathan D.

    2014-11-01

    The physics underlying combustion instability is an active area of research because of its detrimental impact in many combustion devices, such as turbines, jet engines, and liquid rocket engines. Pressure waves, ranging from acoustic waves to strong shocks, are potential sources of these disturbances. Literature on flame-disturbance interactions are primarily focused on either acoustics or strong shock wave interactions, with little information about the wide spectrum of behaviors that may exist between these two extremes. For example, the interaction between a flame and a finite amplitude compression wave is not well characterized. This phenomenon is difficult to study numerically due to the wide range of scales that need to be captured, requiring powerful and efficient numerical techniques. In this work, the interaction of a perturbed laminar premixed flame with a finite amplitude compression wave is investigated using the Parallel Adaptive Wavelet Collocation Method (PAWCM). This method optimally solves the fully compressible Navier-Stokes equations while capturing the essential scales. The results show that depending on the amplitude and duration of a finite amplitude disturbance, the interaction between these waves and premixed flames can produce a broad range of responses.

  12. Experimental study of premixed flames in intense isotropic turbulence

    SciTech Connect

    Bedat, B.; Cheng, R.K.

    1994-04-01

    A methodology for investigating premixed turbulent flames propagating in intense isotropic turbulence has been developed. The burner uses a turbulence generator developed by Videto and Santavicca and the flame is stabilized by weak-swirl generated by air injectors. This set-up produces stable premixed turbulent flames under a wide range of mixture conditions and turbulence intensities. The experiments are designed to investigate systematically the changes in flame structures for conditions which can be classified as wrinkled laminar flames, corrugated flames and flames with distributed reaction zones. Laser Doppler anemometry and Rayleigh scattering techniques are used to determine the turbulence and scalar statistics. In the intense turbulence, the flames are found to produce very little changes in the mean and rams velocities. Their flame speed increase linearly with turbulence intensity as for wrinkled laminar flames. The Rayleigh scattering pdfs for flames within the distributed reaction zone regime are distinctly bimodal. The probabilities of the reacting states (i.e. contributions from within the reaction zone) is not higher than those of wrinkled laminar flame. These results show that there is no drastic changes in flame structures at Karlovitz number close to unity. This suggest that the Klimov-Williams criterion under-predicts the resilience of wrinkled flamelets to intense turbulence.

  13. Mixing Model Performance in Non-Premixed Turbulent Combustion

    NASA Astrophysics Data System (ADS)

    Pope, Stephen B.; Ren, Zhuyin

    2002-11-01

    In order to shed light on their qualitative and quantitative performance, three different turbulent mixing models are studied in application to non-premixed turbulent combustion. In previous works, PDF model calculations with detailed kinetics have been shown to agree well with experimental data for non-premixed piloted jet flames. The calculations from two different groups using different descriptions of the chemistry and turbulent mixing are capable of producing the correct levels of local extinction and reignition. The success of these calculations raises several questions, since it is not clear that the mixing models used contain an adequate description of the processes involved. To address these questions, three mixing models (IEM, modified Curl and EMST) are applied to a partially-stirred reactor burning hydrogen in air. The parameters varied are the residence time and the mixing time scale. For small relative values of the mixing time scale (approaching the perfectly-stirred limit) the models yield the same extinction behavior. But for larger values, the behavior is distictly different, with EMST being must resistant to extinction.

  14. Higher-Resolution Structure of the Human Insulin Receptor Ectodomain: Multi-Modal Inclusion of the Insert Domain.

    PubMed

    Croll, Tristan I; Smith, Brian J; Margetts, Mai B; Whittaker, Jonathan; Weiss, Michael A; Ward, Colin W; Lawrence, Michael C

    2016-03-01

    Insulin receptor (IR) signaling is critical to controlling nutrient uptake and metabolism. However, only a low-resolution (3.8 Å) structure currently exists for the IR ectodomain, with some segments ill-defined or unmodeled due to disorder. Here, we revise this structure using new diffraction data to 3.3 Å resolution that allow improved modeling of the N-linked glycans, the first and third fibronectin type III domains, and the insert domain. A novel haptic interactive molecular dynamics strategy was used to aid fitting to low-resolution electron density maps. The resulting model provides a foundation for investigation of structural transitions in IR upon ligand binding.

  15. Suppressive response of confections containing the extractive from leaves of Morus Alba on postprandial blood glucose and insulin in healthy human subjects

    PubMed Central

    Nakamura, Mariko; Nakamura, Sadako; Oku, Tsuneyuki

    2009-01-01

    Background The first aim of this study was to clarify the effective ratio of extractive from leaves of Morus Alba (ELM) to sucrose so as to apply this knowledge to the preparation of confections that could effectively suppress the elevation of postprandial blood glucose and insulin. The second aim was to identify the efficacy of confections prepared with the optimally effective ratio determined from the first study, using healthy human subjects. Methods Ten healthy females (22.3 years, BMI 21.4 kg/m2) participated in this within-subject, repeated measures study. For the first aim of this study, the test solutions containing 30 g of sucrose and 1.2 or 3.0 g of ELM were repeatedly and randomly given to each subject. To identify the practically suppressive effects on postprandial blood glucose and insulin, some confections with added ELM were prepared as follows: Mizu-yokan, 30 g of sucrose with the addition of 1.5 or 3.0 g ELM; Daifuku-mochi, 9.0 g of starch in addition to 30 g of sucrose and 1.5 or 3.0 g ELM; Chiffon-cake, 24 g of sucrose, starch, and 3.0 or 6.0 g of ELM, and were ingested by each subject. Blood and end-expiration were collected at selected periods after test food ingestion. Results When 30 g of sucrose with 1.2 or 3.0 g of ELM were ingested by subjects, the elevations of postprandial blood glucose and insulin were effectively suppressed (p < 0.01), and the most effective ratio of ELM to sucrose was evaluated to be 1:10. AUC (area under the curve) of breath hydrogen excretion for 6 h after the ingestion of an added 3 g of ELM significantly increased (p < 0.01). When AUCs-3h of incremental blood glucose of confections without ELM was 100, that of Mizu-yokan and Daifuku-mochi with the ratio (1:10) of ELM to sucrose was decreased to 53.4 and 58.2, respectively. Chiffon-cake added one-fourth ELM was 29.0. Conclusion ELM-containing confections for which the ratio of ELM and sucrose is one-tenth effectively suppress the postprandial blood glucose and

  16. Use of biosynthetic human C-peptide in the measurement of insulin secretion rates in normal volunteers and type I diabetic patients.

    PubMed Central

    Polonsky, K S; Licinio-Paixao, J; Given, B D; Pugh, W; Rue, P; Galloway, J; Karrison, T; Frank, B

    1986-01-01

    We undertook this study to examine the accuracy of plasma C-peptide as a marker of insulin secretion. The peripheral kinetics of biosynthetic human C-peptide (BHCP) were studied in 10 normal volunteers and 7 insulin-dependent diabetic patients. Each subject received intravenous bolus injections of BHCP as well as constant and variable rate infusions. After intravenous bolus injections the metabolic clearance rate of BHCP (3.8 +/- 0.1 ml/kg per min, mean +/- SEM) was not significantly different from the value obtained during its constant intravenous infusion (3.9 +/- 0.1 ml/kg per min). The metabolic clearance rate of C-peptide measured during steady state intravenous infusions was constant over a wide concentration range. During experiments in which BHCP was infused at a variable rate, the peripheral concentration of C-peptide did not change in proportion to the infusion rate. Thus, the infusion rate of BHCP could not be calculated accurately as the product of the C-peptide concentration and metabolic clearance rate. However, the non-steady infusion rate of BHCP could be accurately calculated from peripheral C-peptide concentrations using a two-compartment mathematical model when model parameters were derived from the C-peptide decay curve in each subject. Application of this model to predict constant infusions of C-peptide from peripheral C-peptide concentrations resulted in model generated estimates of the C-peptide infusion rate that were 101.5 +/- 3.4% and 100.4 +/- 2.8% of low and high dose rates, respectively. Estimates of the total quantity of C-peptide infused at a variable rate over 240 min based on the two-compartment model represented 104.6 +/- 2.4% of the amount actually infused. Application of this approach to clinical studies will allow the secretion rate of insulin to be estimated with considerable accuracy. The insulin secretion rate in normal subjects after an overnight fast was 89.1 pmol/min, which corresponds with a basal 24-h secretion of 18.6 U

  17. Reduction of hepatic insulin clearance after oral glucose ingestion is not mediated by glucagon-like peptide 1 or gastric inhibitory polypeptide in humans.

    PubMed

    Meier, Juris J; Holst, Jens J; Schmidt, Wolfgang E; Nauck, Michael A

    2007-09-01

    Changes in hepatic insulin clearance can occur after oral glucose or meal ingestion. This has been attributed to the secretion and action of gastric inhibitory polypeptide (GIP) and glucagon-like peptide (GLP)-1. Given the recent availability of drugs based on incretin hormones, such clearance effects may be important for the future treatment of type 2 diabetes. Therefore, we determined insulin clearance in response to endogenously secreted and exogenously administered GIP and GLP-1. Insulin clearance was estimated from the molar C-peptide-to-insulin ratio calculated at basal conditions and from the respective areas under the curve after glucose, GIP, or GLP-1 administration. Oral glucose administration led to an approximately 60% reduction in the C-peptide-to-insulin ratio (P < 0.0001), whereas intravenous glucose administration had no effect (P = 0.09). The endogenous secretion of GIP or GLP-1 was unrelated to the changes in insulin clearance. The C-peptide-to-insulin ratio was unchanged after the intravenous administration of GIP or GLP-1 in the fasting state (P = 0.27 and P = 0.35, respectively). Likewise, infusing GLP-1 during a meal course did not alter insulin clearance (P = 0.87). An inverse nonlinear relationship was found between the C-peptide-to-insulin ratio and the integrated insulin levels after oral and during intravenous glucose administration. Insulin clearance is reduced by oral but not by intravenous glucose administration. Neither GIP nor GLP-1 has significant effects on insulin extraction. An inverse relationship between insulin concentrations and insulin clearance suggests that the secretion of insulin itself determines the rate of hepatic insulin clearance.

  18. Use of a temporary "solubilizing" peptide tag for the Fmoc solid-phase synthesis of human insulin glargine via use of regioselective disulfide bond formation.

    PubMed

    Hossain, Mohammed Akhter; Belgi, Alessia; Lin, Feng; Zhang, Suode; Shabanpoor, Fazel; Chan, Linda; Belyea, Chris; Truong, Hue-Trung; Blair, Amy R; Andrikopoulos, Sof; Tregear, Geoffrey W; Wade, John D

    2009-07-01

    Solid-phase peptide synthesis has been refined to a stage where efficient preparation of long and complex peptides is now achievable. However, the postsynthesis handling of poorly soluble peptides often remains a significant hindrance to their purification and further use. Several synthetic schemes have been developed for the preparation of such peptides containing modifications to aid their solubility. However, these require the use of complex chemistry or yield non-native sequences. We describe a simple approach based on the use of penta-lysine "tags" that are linked to the C-terminus of the peptide of interest via a base-labile linker. After ready purification of the now freely solubilized peptide, the "tag" is removed by simple, brief base treatment giving the native sequence in much higher overall yield. The applicability of the method was demonstrated by the novel preparation of insulin glargine via solid-phase synthesis of each of the two chains--including the notoriously poorly soluble A-chain--followed by their combination in solution via regioselective disulfide bond formation. At the conclusion of the chain combination, the solubilizing peptide tag was removed from the A-chain to provide synthetic human glargine in nearly 10% overall yield. This approach should facilitate the development of new insulin analogues as well as be widely applicable to the improved purification and acquisition of otherwise poorly soluble synthetic peptides.

  19. Protein Internal Dynamics Associated With Pre-System Glass Transition Temperature Endothermic Events: Investigation of Insulin and Human Growth Hormone by Solid State Hydrogen/Deuterium Exchange.

    PubMed

    Fang, Rui; Grobelny, Pawel J; Bogner, Robin H; Pikal, Michael J

    2016-11-01

    Lyophilized proteins are generally stored below their glass transition temperature (Tg) to maintain long-term stability. Some proteins in the (pure) solid state showed a distinct endotherm at a temperature well below the glass transition, designated as a pre-Tg endotherm. The pre-Tg endothermic event has been linked with a transition in protein internal mobility. The aim of this study was to investigate the internal dynamics of 2 proteins, insulin and human growth hormone (hGH), both of which exhibit the pre-Tg endothermic event with onsets at 50°C-60°C. Solid state hydrogen/deuterium (H/D) exchange of both proteins was characterized by Fourier transform infrared spectroscopy over a temperature range from 30°C to 80°C. A distinct sigmoidal transition in the extent of H/D exchange had a midpoint of 56.1 ± 1.2°C for insulin and 61.7 ± 0.9°C for hGH, suggesting a transition to greater mobility in the protein molecules at these temperatures. The data support the hypothesis that the pre-Tg event is related to a transition in internal protein mobility associated with the protein dynamical temperature. Exceeding the protein dynamical temperature is expected to activate protein internal motion and therefore may have stability consequences.

  20. Influence of water content on hardening and handling of a premixed calcium phosphate cement.

    PubMed

    Engstrand, Johanna; Aberg, Jonas; Engqvist, Håkan

    2013-01-01

    Handling of calcium phosphate cements is difficult, where problems often arise during mixing, transferring to syringes, and subsequent injection. Via the use of premixed cements the risk of handling complications is reduced. However, for premixed cements to work in a clinical situation the setting time needs to be improved. The objective of this study is to investigate the influence of the addition of water on the properties of premixed cement. Monetite-forming premixed cements with small amounts of added water (less than 6.8 wt.%) were prepared and the influence on injectability, working time, setting time and mechanical strength was evaluated. The results showed that the addition of small amounts of water had significant influence on the properties of the premixed cement. With the addition of just 1.7 wt.% water, the force needed to extrude the cement from a syringe was reduced from 107 (±15) N to 39 (±9) N, the compression strength was almost doubled, and the setting time decreased from 29 (±4) min to 19 (±2) min, while the working time remained 5 to 6h. This study demonstrates the importance of controlling the water content in premixed cement pastes and how water can be used to improve the properties o