Glycemic Outcomes of Use of CLC Versus PLGS in Type 1 Diabetes: A Randomized Controlled Trial

OBJECTIVE

Limited information is available about glycemic outcomes with a closed-loop control (CLC) system compared with a predictive low-glucose suspend (PLGS) system.

RESEARCH DESIGN AND METHODS

After 6 months of use of a CLC system in a randomized trial, 109 participants with type 1 diabetes (age range, 14-72 years; mean HbA_1c, 7.1% [54 mmol/mol]) were randomly assigned to CLC (N = 54, Control-IQ) or PLGS (N = 55, Basal-IQ) groups for 3 months. The primary outcome was continuous glucose monitor (CGM)-measured time in range (TIR) for 70-180 mg/dL. Baseline CGM metrics were computed from the last 3 months of the preceding study.

RESULTS

All 109 participants completed the study. Mean ± SD TIR was 71.1 ± 11.2% at baseline and 67.6 ± 12.6% using intention-to-treat analysis (69.1 ± 12.2% using per-protocol analysis excluding periods of study-wide suspension of device use) over 13 weeks on CLC vs. 70.0 ± 13.6% and 60.4 ± 17.1% on PLGS (difference = 5.9%; 95% CI 3.6%, 8.3%; P < 0.001). Time >180 mg/dL was lower in the CLC group than PLGS group (difference = -6.0%; 95% CI -8.4%, -3.7%; P < 0.001) while time <54 mg/dL was similar (0.04%; 95% CI -0.05%, 0.13%; P = 0.41). HbA_1c after 13 weeks was lower on CLC than PLGS (7.2% [55 mmol/mol] vs. 7.5% [56 mmol/mol], difference -0.34% [-3.7 mmol/mol]; 95% CI -0.57% [-6.2 mmol/mol], -0.11% [1.2 mmol/mol]; P = 0.0035).

CONCLUSIONS

Following 6 months of CLC, switching to PLGS reduced TIR and increased HbA_1c toward their pre-CLC values, while hypoglycemia remained similarly reduced with both CLC and PLGS.

Safety and Efficacy of Initializing the Control-IQ Artificial Pancreas System Based on Total Daily Insulin in Adolescents with Type 1 Diabetes

Objective: To assess the safety and efficacy of a simplified initialization for the Tandem t:slim X2 Control-IQ hybrid closed-loop system, using parameters based on total daily insulin ("MyTDI") in adolescents with type 1 diabetes under usual activity and during periods of increased exercise. Research Design and Methods: Adolescents with type 1 diabetes 12-18 years of age used Control-IQ for 5 days at home using their usual parameters. Upon arrival at a 60-h ski camp, participants were randomized to either continue Control-IQ using their home settings or to reinitialize Control-IQ with MyTDI parameters. Control-IQ use continued for 5 days following camp. The effect of MyTDI on continuous glucose monitoring outcomes were analyzed using repeated measures analysis of variance (ANOVA): baseline, camp, and at home. Results: Twenty participants were enrolled and completed the study; two participants were excluded from the analysis due to absence from ski camp (1) and illness (1). Time in range was similar between both groups at home and camp. A tendency to higher time <70 mg/dL in the MyTDI group was present but only during camp (median 3.8% vs. 1.4%, P = 0.057). MyTDI users with bolus/TDI ratios >40% tended to show greater time in the euglycemic range improvements between baseline and home than users with ratios <40% (+16.3% vs. -9.0%, P = 0.012). All participants maintained an average of 95% time in closed loop (84.1%-100%). Conclusions: MyTDI is a safe, effective, and easy way to determine insulin parameters for use in the Control-IQ artificial pancreas. Future modifications to account for the influence of carbohydrate intake on MyTDI calculations might further improve time in range.

The Use of a Smart Bolus Calculator Informed by Real-time Insulin Sensitivity Assessments Reduces Postprandial Hypoglycemia Following an Aerobic Exercise Session in Individuals With Type 1 Diabetes

OBJECTIVE

Insulin dosing in type 1 diabetes (T1D) is oftentimes complicated by fluctuating insulin requirements driven by metabolic and psychobehavioral factors impacting individuals' insulin sensitivity (IS). In this context, smart bolus calculators that automatically tailor prandial insulin dosing to the metabolic state of a person can improve glucose management in T1D.

RESEARCH DESIGN AND METHODS

Fifteen adults with T1D using continuous glucose monitors (CGMs) and insulin pumps completed two 24-h admissions in a hotel setting. During the admissions, participants engaged in an early afternoon 45-min aerobic exercise session, after which they received a standardized dinner meal. The dinner bolus was computed using a standard bolus calculator or smart bolus calculator informed by real-time IS estimates. Glucose control was assessed in the 4 h following dinner using CGMs and was compared between the two admissions.

RESULTS

The IS-informed bolus calculator allowed for a reduction in postprandial hypoglycemia as quantified by the low blood glucose index (2.02 vs. 3.31, P = 0.006) and percent time <70 mg/dL (8.48% vs. 15.18%, P = 0.049), without increasing hyperglycemia (high blood glucose index: 3.13 vs. 2.09, P = 0.075; percent time >180 mg/dL: 13.24% vs. 10.42%, P = 0.5; percent time >250 mg/dL: 2.08% vs. 1.19%, P = 0.317). In addition, the number of hypoglycemia rescue treatments was reduced from 12 to 7 with the use of the system.

CONCLUSIONS

The study shows that the proposed IS-informed bolus calculator is safe and feasible in adults with T1D, appropriately reducing postprandial hypoglycemia following an exercise-induced IS increase.

Randomized Controlled Trial of Mobile Closed-Loop Control

OBJECTIVE

Assess the efficacy of inControl AP, a mobile closed-loop control (CLC) system.

RESEARCH DESIGN AND METHODS

This protocol, NCT02985866, is a 3-month parallel-group, multicenter, randomized unblinded trial designed to compare mobile CLC with sensor-augmented pump (SAP) therapy. Eligibility criteria were type 1 diabetes for at least 1 year, use of insulin pumps for at least 6 months, age ≥14 years, and baseline HbA1c <10.5% (91 mmol/mol). The study was designed to assess two coprimary outcomes: superiority of CLC over SAP in continuous glucose monitor (CGM)-measured time below 3.9 mmol/L and noninferiority in CGM-measured time above 10 mmol/L.

RESULTS

Between November 2017 and May 2018, 127 participants were randomly assigned 1:1 to CLC (n = 65) versus SAP (n = 62); 125 participants completed the study. CGM time below 3.9 mmol/L was 5.0% at baseline and 2.4% during follow-up in the CLC group vs. 4.7% and 4.0%, respectively, in the SAP group (mean difference -1.7% [95% CI -2.4, -1.0]; P < 0.0001 for superiority). CGM time above 10 mmol/L was 40% at baseline and 34% during follow-up in the CLC group vs. 43% and 39%, respectively, in the SAP group (mean difference -3.0% [95% CI -6.1, 0.1]; P < 0.0001 for noninferiority). One severe hypoglycemic event occurred in the CLC group, which was unrelated to the study device.

CONCLUSIONS

In meeting its coprimary end points, superiority of CLC over SAP in CGM-measured time below 3.9 mmol/L and noninferiority in CGM-measured time above 10 mmol/L, the study has demonstrated that mobile CLC is feasible and could offer certain usability advantages over embedded systems, provided the connectivity between system components is stable.

Evening and overnight closed-loop control versus 24/7 continuous closed-loop control for type 1 diabetes: a randomised crossover trial

Background

Automated closed-loop control (CLC), known as the "artificial pancreas" is emerging as a treatment option for Type 1 Diabetes (T1D), generally superior to sensor-augmented insulin pump (SAP) treatment. It is postulated that evening-night (E-N) CLC may account for most of the benefits of 24-7 CLC; however, a direct comparison has not been done.

Methods

In this trial (NCT02679287), adults with T1D were randomised 1:1 to two groups, which followed different sequences of four 8-week sessions, resulting in two crossover designs comparing SAP vs E-N CLC and E-N CLC vs 24-7 CLC, respectively. Eligibility: T1D for at least 1 year, using an insulin pump for at least six months, ages 18 years or older. Primary hypothesis: E-N CLC compared to SAP will decrease percent time <70mg/dL (3.9mmol/L) measured by continuous glucose monitoring (CGM) without deterioration in HbA1c. Secondary Hypotheses: 24-7 CLC compared to SAP will increase CGM-measured time in target range (TIR, 70-180mg/dL; 3.9-10mmol/L) and will reduce glucose variability during the day.

Findings

Ninety-three participants were randomised and 80 were included in the analysis, ages 18-69 years; HbA1c levels 5.4-10.6%; 66% female. Compared to SAP, E-N CLC reduced overall time <70mg/dL from 4.0% to 2.2% () resulting in an absolute difference of 1.8% (95%CI: 1.2-2.4%), p<0.0001. This was accompanied by overall reduction in HbA1c from 7.4% at baseline to 7.1% at the end of study, resulting in an absolute difference of 0.3% (95% CI: 0.1-0.4%), p<0.0001. There were 5 severe hypoglycaemia adverse events attributed to user-directed boluses without malfunction of the investigational device, and no diabetic ketoacidosis events.

Interpretation

In type 1 diabetes, evening-night closed-loop control was superior to sensor-augmented pump therapy, achieving most of the glycaemic benefits of 24-7 closed-loop.

Six-Month Randomized, Multicenter Trial of Closed-Loop Control in Type 1 Diabetes

BACKGROUND

Closed-loop systems that automate insulin delivery may improve glycemic outcomes in patients with type 1 diabetes.

METHODS

In this 6-month randomized, multicenter trial, patients with type 1 diabetes were assigned in a 2:1 ratio to receive treatment with a closed-loop system (closed-loop group) or a sensor-augmented pump (control group). The primary outcome was the percentage of time that the blood glucose level was within the target range of 70 to 180 mg per deciliter (3.9 to 10.0 mmol per liter), as measured by continuous glucose monitoring.

RESULTS

A total of 168 patients underwent randomization; 112 were assigned to the closed-loop group, and 56 were assigned to the control group. The age range of the patients was 14 to 71 years, and the glycated hemoglobin level ranged from 5.4 to 10.6%. All 168 patients completed the trial. The mean (±SD) percentage of time that the glucose level was within the target range increased in the closed-loop group from 61±17% at baseline to 71±12% during the 6 months and remained unchanged at 59±14% in the control group (mean adjusted difference, 11 percentage points; 95% confidence interval [CI], 9 to 14; P<0.001). The results with regard to the main secondary outcomes (percentage of time that the glucose level was >180 mg per deciliter, mean glucose level, glycated hemoglobin level, and percentage of time that the glucose level was <70 mg per deciliter or <54 mg per deciliter [3.0 mmol per liter]) all met the prespecified hierarchical criterion for significance, favoring the closed-loop system. The mean difference (closed loop minus control) in the percentage of time that the blood glucose level was lower than 70 mg per deciliter was -0.88 percentage points (95% CI, -1.19 to -0.57; P<0.001). The mean adjusted difference in glycated hemoglobin level after 6 months was -0.33 percentage points (95% CI, -0.53 to -0.13; P = 0.001). In the closed-loop group, the median percentage of time that the system was in closed-loop mode was 90% over 6 months. No serious hypoglycemic events occurred in either group; one episode of diabetic ketoacidosis occurred in the closed-loop group.

CONCLUSIONS

In this 6-month trial involving patients with type 1 diabetes, the use of a closed-loop system was associated with a greater percentage of time spent in a target glycemic range than the use of a sensor-augmented insulin pump. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases; iDCL ClinicalTrials.gov number, NCT03563313.).

Hybrid Closed-Loop Control Is Safe and Effective for People with Type 1 Diabetes Who Are at Moderate to High Risk for Hypoglycemia

Background: Typically, closed-loop control (CLC) studies excluded patients with significant hypoglycemia. We evaluated the effectiveness of hybrid CLC (HCLC) versus sensor-augmented pump (SAP) in reducing hypoglycemia in this high-risk population. Methods: Forty-four subjects with type 1 diabetes, 25 women, 37 ± 2 years old, HbA1c 7.4% ± 0.2% (57 ± 1.5 mmol/mol), diabetes duration 19 ± 2 years, on insulin pump, were enrolled at the University of Virginia (N = 33) and Stanford University (N = 11). Eligibility: increased risk of hypoglycemia confirmed by 1 week of blinded continuous glucose monitor (CGM); randomized to 4 weeks of home use of either HCLC or SAP. Primary/secondary outcomes: risk for hypoglycemia measured by the low blood glucose index (LBGI)/CGM-based time in ranges. Results: Values reported: mean ± standard deviation. From baseline to the final week of study: LBGI decreased more on HCLC (2.51 ± 1.17 to 1.28 ± 0.5) than on SAP (2.1 ± 1.05 to 1.79 ± 0.98), P < 0.001; percent time below 70 mg/dL (3.9 mmol/L) decreased on HCLC (7.2% ± 5.3% to 2.0% ± 1.4%) but not on SAP (5.8% ± 4.7% to 4.8% ± 4.5%), P = 0.001; percent time within the target range 70-180 mg/dL (3.9-10 mmol/L) increased on HCLC (67.8% ± 13.5% to 78.2% ± 10%) but decreased on SAP (65.6% ± 12.9% to 59.6% ± 16.5%), P < 0.001; percent time above 180 mg/dL (10 mmol/L) decreased on HCLC (25.1% ± 15.3% to 19.8% ± 10.1%) but increased on SAP (28.6% ± 14.6% to 35.6% ± 17.6%), P = 0.009. Mean glucose did not change significantly on HCLC (144.9 ± 27.9 to 143.8 ± 14.4 mg/dL [8.1 ± 1.6 to 8.0 ± 0.8 mmol/L]) or SAP (152.5 ± 24.3 to 162.4 ± 28.2 [8.5 ± 1.4 to 9.0 ± 1.6]), P = ns. Conclusions: Compared with SAP therapy, HCLC reduced the risk and frequency of hypoglycemia, while improving time in target range and reducing hyperglycemia in people at moderate to high risk of hypoglycemia.

The International Diabetes Closed-Loop Study: Testing Artificial Pancreas Component Interoperability

BACKGROUND

Use of artificial pancreas (AP) requires seamless interaction of device components, such as continuous glucose monitor (CGM), insulin pump, and control algorithm. Mobile AP configurations also include a smartphone as computational hub and gateway to cloud applications (e.g., remote monitoring and data review and analysis). This International Diabetes Closed-Loop study was designed to demonstrate and evaluate the operation of the inControl AP using different CGMs and pump modalities without changes to the user interface, user experience, and underlying controller.

METHODS

Forty-three patients with type 1 diabetes (T1D) were enrolled at 10 clinical centers (7 United States, 3 Europe) and 41 were included in the analyses (39% female, >95% non-Hispanic white, median T1D duration 16 years, median HbA1c 7.4%). Two CGMs and two insulin pumps were tested by different study participants/sites using the same system hub (a smartphone) during 2 weeks of in-home use.

RESULTS

The major difference between the system components was the stability of their wireless connections with the smartphone. The two sensors achieved similar rates of connectivity as measured by percentage time in closed loop (75% and 75%); however, the two pumps had markedly different closed-loop adherence (66% vs. 87%). When connected, all system configurations achieved similar glycemic outcomes on AP control (73% [mean] time in range: 70-180 mg/dL, and 1.7% [median] time <70 mg/dL).

CONCLUSIONS

CGMs and insulin pumps can be interchangeable in the same Mobile AP system, as long as these devices achieve certain levels of reliability and wireless connection stability.

Continuous Glucose Monitoring and Insulin Informed Advisory System with Automated Titration and Dosing of Insulin Reduces Glucose Variability in Type 1 Diabetes Mellitus

BACKGROUND

Glucose variability (GV) remains a key limiting factor in the success of diabetes management. While new technologies, for example, accurate continuous glucose monitoring (CGM) and connected insulin delivery devices, are now available, current treatment standards fail to leverage the wealth of information generated. Expert systems, from automated insulin delivery to advisory systems, are a key missing element to richer, more personalized, glucose management in diabetes.

METHODS

Twenty four subjects with type 1 diabetes mellitus (T1DM), 15 women, 37 ± 11 years of age, hemoglobin A1c 7.2% ± 1%, total daily insulin (TDI) 46.7 ± 22.3 U, using either an insulin pump or multiple daily injections with carbohydrate counting, completed two randomized crossover 48-h visits at the University of Virginia, wearing Dexcom G4 CGM, and using either usual care or the UVA decision support system (DSS). DSS consisted of a combination of automated insulin titration, bolus calculation, and CHO treatment advice. During each admission, participants were exposed to a variety of meal sizes and contents and two 45-min bouts of exercise. GV and glucose control were assessed using CGM.

RESULTS

The use of DSS significantly reduced GV (coefficient of variation: 0.36 ± 08. vs. 0.33 ± 0.06, P = 0.045) while maintaining glycemic control (average CGM: 155.2 ± 27.1 mg/dL vs. 155.2 ± 23.2 mg/dL), by reducing hypoglycemia exposure (%<70 mg/dL: 3.8% ± 4.6% vs. 1.8% ± 2%, P = 0.018), with nonsignificant trends toward reduction of significant hyperglycemia overnight (%>250 mg/dL: 5.3% ± 9.5% vs. 1.9% ± 4.6%) and at mealtime (11.3% ± 14.8% vs. 5.8% ± 9.1%).

CONCLUSIONS

A CGM/insulin informed advisory system proved to be safe and feasible in a cohort of 24 T1DM subjects. Use of the system may result in reduced GV and improved protection against hypoglycemia.

Recent Exposure to Hypoglycemia Increases Glucose Variability Following a Hyper/Hypoglycemic Metabolic Challenge in T1D

AIMS

In type 1 diabetes (T1D), repeated hypoglycemic episodes may reduce hormonal defenses and increase the risk for severe hypoglycemia. In this work, we investigate the effect of a structured hyper/hypoglycemic metabolic challenge on the postintervention glucose variability in T1D subjects studied at home.

METHODS

Thirty T1D subjects using insulin pump were monitored with blood glucose meters (SMBG) during a 1-month observation period. After 2 weeks of monitoring, participants were admitted at the University of Virginia Clinical Research Unit to undergo an 8-hour metabolic challenge. The intervention was designed to create hyperglycemia shortly followed by hypoglycemia, mimicking a real-life scenario of underbolused meal followed by overcorrection. After the intervention, subjects were monitored for 2 more weeks. Glycemic variability was assessed before and after the challenge using the low blood glucose index (LBGI). Glucagon counterregulation (GCR) response to induced hypoglycemia was also measured. LBGI variation and GCR were linked to prior exposure to hypoglycemia.

RESULTS

Subjects significantly exposed to hypoglycemia in the 2 weeks before the intervention had a significant increase of postchallenge LBGI ( P < .001) and lower GCR response ( P < .05). Recent occurrence of hypoglycemia and number of years not using an insulin pump were identified as significant predictors of postchallenge LBGI ( P < .001).

CONCLUSION

Glycemic swings, a common result of suboptimal insulin treatment, have a significant impact on future (days) glycemic control in T1D subjects with a recent history of hypoglycemia, as measured in the field. Choice of past insulin therapy may also mediate this effect.

Abstract P5-05-03: Obesity drives breast cancer progression through estrogen dependent and independent mechanisms

Background: More than 200,000 women are diagnosed with breast cancer each year and 75% develop estrogen receptor positive (ER+) tumors. Obesity is an independent risk factor for the development of ER+ breast cancer, particularly after menopause, and affects 40% of US women. Obese women are more likely to be diagnosed with advanced tumors, lymph node involvement, and less likely to respond to endocrine therapy versus lean women. Mechanisms underlying the increased risk and worse prognosis of obese women are poorly understood. The dogma in the field states that estrogen production is the main contributor to obesity-associated ER+ breast cancer. We show that this is not always the case. Given the epidemic proportions of obesity in the US, we need better pre-clinical models that will inform focused clinical trials and interventions for patients. In this study, we describe a novel mouse model of obesity and ER+ breast cancer patient-derived xenografts (PDX). Our studies highlight the heterogeneity of responses within the ER+ breast cancer subtype to the obese environment and implicate both estrogen-dependent and independent mechanisms of obesity-associated tumor progression.

Methods: ER+, FGFR1-amplified or non-amplified human tumors were established in ovariectomized lean and obese mice in the presence of high or low estradiol (E2). To simulate the hormonal environment of women on aromatase inhibitors, E2 was removed from half of the mice in each adiposity group and the study was terminated 3 weeks later. Weight gain, body fat percentage, and adipose tissue as well as tumor characteristics were analyzed.

Results: Prior to EWD, obese mice were heavier and had higher body fat percentage than lean mice and also displayed a phenotype of metabolic dysfunction. This trend was accelerated after EWD, with obese mice gaining more weight due to body fat accumulation. Tumors responded in one of two ways: Regardless of FGFR1 amplification, obesity promoted ER+ tumor growth in the presence of low (postmenopausal), but not high (premenopausal) E2. In the presence of low E2, tumor PR levels were higher in obese compared to lean mice, suggesting hyperactive ER signaling. In FGFR1-amplified tumors, obesity promoted tumor growth after EWD. In addition, EWD induced excess fat deposition in visceral depots in both lean and obese mice; however, obese mice also gained fat in mammary adipose depots. Mammary fat pad mass and rate of post-EWD weight gain directly correlated with adipose FGF1 levels. Tumors from obese mice had higher levels of phosphorylated FGFR1, without changes in total FGFR1, compared to lean mice.

Conclusions: Utilizing a unique PDX model system, we show that obesity promotes tumor progression in the presence of low E2, and also after EWD, and identify growth factor receptor signaling as a mediator of these phenotypes. The activation of FGFR1 may underlie increased breast cancer risk and recurrence observed in obese, postmenopausal women.

Citation Format: Wellberg EA, Johnson SJ, Jacobsen BM, Anderson SM, Sartorius CA, MacLean PS, Kabos P. Obesity drives breast cancer progression through estrogen dependent and independent mechanisms [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-05-03.

Overnight Closed-Loop Control Improves Glycemic Control in a Multicenter Study of Adults With Type 1 Diabetes

CONTEXT

Closed-loop control (CLC) for the management of type 1 diabetes (T1D) is a novel method for optimizing glucose control, and strategies for individualized implementation are being developed.

OBJECTIVE

To analyze glycemic control in an overnight CLC system designed to "reset" the patient to near-normal glycemic targets every morning.

DESIGN

Randomized, crossover, multicenter clinical trial.

PARTICIPANTS

Forty-four subjects with T1D requiring insulin pump therapy.

INTERVENTION

Sensor-augmented pump therapy (SAP) at home vs 5 nights of CLC (active from 23:00 to 07:00) in a supervised outpatient setting (research house or hotel), with a substudy of 5 nights of CLC subsequently at home.

MAIN OUTCOME MEASURE

The percentage of time spent in the target range (70 to 180 mg/dL measured using a continuous glucose monitor).

RESULTS

Forty subjects (age, 45.5 ± 9.5 years; hemoglobin A1c, 7.4% ± 0.8%) completed the study. The time in the target range (70 to 180 mg/dL) significantly improved in CLC vs SAP over 24 hours (78.3% vs 71.4%; P = 0.003) and overnight (85.7% vs 67.6%; P < 0.001). The time spent in a hypoglycemic range (<70 mg/dL) decreased significantly in the CLC vs SAP group over 24 hours (2.5% vs 4.3%; P = 0.002) and overnight (0.9% vs 3.2%; P < 0.001). The mean glucose level at 07:00 was lower with CLC than with SAP (123.7 vs 145.3 mg/dL; P < 0.001). The substudy at home, involving 10 T1D subjects, showed similar trends with an increased time in target (70 to 180 mg/dL) overnight (75.2% vs 62.2%; P = 0.07) and decreased time spent in the hypoglycemic range (<70 mg/dL) overnight in CLC vs SAP (0.6% vs 3.7%; P = 0.03).

CONCLUSION

Overnight-only CLC increased the time in the target range over 24 hours and decreased the time in hypoglycemic range over 24 hours in a supervised outpatient setting. A pilot extension study at home showed a similar nonsignificant trend.

Evaluation of a Predictive Low-Glucose Management System In-Clinic

BACKGROUND

Predictions based on continuous glucose monitoring (CGM) data are the basis for automatic suspension and resumption of insulin delivery by a predictive low-glucose management feature termed "suspend before low," which is part of the Medtronic MiniMed^® 640G combined insulin pump and CGM system. This study assessed the safety and performance characteristics of the system in an in-clinic setting at eight sites.

MATERIALS AND METHODS

In-clinic standardized increases in basal insulin delivery rates were used to induce nocturnal hypoglycemia in subjects (14-75 years) with type 1 diabetes wearing the MiniMed 640G system. The "suspend before low" feature was set at 65 mg/dL, and as a result, the predictive algorithm suspended insulin delivery when the forecasted glucose was predicted to be ≤85 mg/dL in 30 min (a 20 mg/dL safety buffer). Reference plasma glucose values (Yellow Springs Instruments [YSI], Yellow Springs, OH) were used to establish hypoglycemia and were defined as ≥2 consecutive values ≤65 mg/dL.

RESULTS

Eighty subjects were screened. Among the 69 successful completers, 27 experienced a hypoglycemic event and 42 did not, a prevention rate of 60%. The mean (±standard deviation) YSI value at the time of pump suspension was 101 ± 18.5 mg/dL, and the mean duration of the 68 "suspend before low" events was 105 ± 27 min. At 120 min after the start of the pump suspension events, the mean YSI value was 102 ± 34.6 mg/dL.

CONCLUSION

The MiniMed 640G "suspend before low" feature prevented 60% of induced predicted hypoglycemic events without significant rebound hyperglycemia.

Experiences of adolescent lung transplant recipients: A qualitative study

Many young transplant recipients experience psychological distress and adjustment difficulties, yet there is little research investigating lung transplantation from the recipients' perspective. This qualitative study aimed to explore experiences of young people who underwent lung transplantation. Semi-structured interviews were conducted with six lung transplant recipients (aged 15-18). Interviews were analysed using IPA, a qualitative research approach examining how people make sense of their major life experiences. The analysis revealed three master themes: "Living with Dodgy Lungs" outlined how participants dealt with their experiences, managing through accepting or discussing their feelings with others, although talking was often difficult. "The Big Deal" reflected participants' experiences of the process, their expectations, and the contrast of their lives pre- and post-transplant. Inherent in their accounts was the profound meaning ascribed to transplantation, the emotional turmoil, and impact on their lives. "A Sense of Self" illustrated participants' developing identities within their social contexts and at times isolating experiences. The results highlight key areas where adolescent lung transplant recipients could be supported by clinicians, enabling the promotion of psychological well-being. Examples include supporting identity integration post-transplant, facilitating social inclusion, considering alternative means of support, and involving adolescents in healthcare decisions.

Glucose Outcomes with the In-Home Use of a Hybrid Closed-Loop Insulin Delivery System in Adolescents and Adults with Type 1 Diabetes

BACKGROUND

The safety and effectiveness of the in-home use of a hybrid closed-loop (HCL) system that automatically increases, decreases, and suspends insulin delivery in response to continuous glucose monitoring were investigated.

METHODS

Adolescents (n = 30, ages 14-21 years) and adults (n = 94, ages 22-75 years) with type 1 diabetes participated in a multicenter (nine sites in the United States, one site in Israel) pivotal trial. The Medtronic MiniMed^® 670G system was used during a 2-week run-in phase without HCL control, or Auto Mode, enabled (Manual Mode) and, thereafter, with Auto Mode enabled during a 3-month study phase. A supervised hotel stay (6 days/5 nights) that included a 24-h frequent blood sample testing with a reference measurement (i-STAT) occurred during the study phase.

RESULTS

Adolescents (mean ± standard deviation [SD] 16.5 ± 2.29 years of age and 7.7 ± 4.15 years of diabetes) used the system for a median 75.8% (interquartile range [IQR] 68.0%-88.4%) of the time (2977 patient-days). Adults (mean ± SD 44.6 ± 12.79 years of age and 26.4 ± 12.43 years of diabetes) used the system for a median 88.0% (IQR 77.6%-92.7%) of the time (9412 patient-days). From baseline run-in to the end of study phase, adolescent and adult HbA_1c levels decreased from 7.7% ± 0.8% to 7.1% ± 0.6% (P < 0.001) and from 7.3% ± 0.9% to 6.8% ± 0.6% (P < 0.001, Wilcoxon signed-rank test), respectively. The proportion of overall in-target (71-180 mg/dL) sensor glucose (SG) values increased from 60.4% ± 10.9% to 67.2% ± 8.2% (P < 0.001) in adolescents and from 68.8% ± 11.9% to 73.8% ± 8.4% (P < 0.001) in adults. During the hotel stay, the proportion of in-target i-STAT^® blood glucose values was 67.4% ± 27.7% compared to SG values of 72.0% ± 11.6% for adolescents and 74.2% ± 17.5% compared to 76.9% ± 8.3% for adults. There were no severe hypoglycemic or diabetic ketoacidosis events in either cohort.

CONCLUSIONS

HCL therapy was safe during in-home use by adolescents and adults and the study phase demonstrated increased time in target, and reductions in HbA_1c, hyperglycemia and hypoglycemia, compared to baseline.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02463097.

Abstract P4-06-07: Fibroblast growth factor receptor activation and breast tumor progression in a mouse xenograft model of obesity

This abstract was withdrawn by the authors.

Feasibility of Long-Term Closed-Loop Control: A Multicenter 6-Month Trial of 24/7 Automated Insulin Delivery

BACKGROUND

In the past few years, the artificial pancreas-the commonly accepted term for closed-loop control (CLC) of blood glucose in diabetes-has become a hot topic in research and technology development. In the summer of 2014, we initiated a 6-month trial evaluating the safety of 24/7 CLC during free-living conditions.

RESEARCH DESIGN AND METHODS

Following an initial 1-month Phase 1, 14 individuals (10 males/4 females) with type 1 diabetes at three clinical centers in the United States and one in Italy continued with a 5-month Phase 2, which included 24/7 CLC using the wireless portable Diabetes Assistant (DiAs) developed at the University of Virginia Center for Diabetes Technology. Median subject characteristics were age 45 years, duration of diabetes 27 years, total daily insulin 0.53 U/kg/day, and baseline HbA1c 7.2% (55 mmol/mol).

RESULTS

Compared with the baseline observation period, the frequency of hypoglycemia below 3.9 mmol/L during the last 3 months of CLC was lower: 4.1% versus 1.3%, P < 0.001. This was accompanied by a downward trend in HbA1c from 7.2% (55 mmol/mol) to 7.0% (53 mmol/mol) at 6 months. HbA1c improvement was correlated with system use (Spearman r = 0.55). The user experience was favorable with identified benefit particularly at night and overall trust in the system. There were no serious adverse events, severe hypoglycemia, or diabetic ketoacidosis.

CONCLUSION

We conclude that CLC technology has matured and is safe for prolonged use in patients' natural environment. Based on these promising results, a large randomized trial is warranted to assess long-term CLC efficacy and safety.

A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase

BACKGROUND

Equine type 1 polysaccharide storage myopathy (PSSM1) is associated with a missense mutation (R309H) in the glycogen synthase (GYS1) gene, enhanced glycogen synthase (GS) activity and excessive glycogen and amylopectate inclusions in muscle.

METHODS

Equine muscle biochemical and recombinant enzyme kinetic assays in vitro and homology modelling in silico, were used to investigate the hypothesis that higher GS activity in affected horse muscle is caused by higher GS expression, dysregulation, or constitutive activation via a conformational change.

RESULTS

PSSM1-affected horse muscle had significantly higher glycogen content than control horse muscle despite no difference in GS expression. GS activity was significantly higher in muscle from homozygous mutants than from heterozygote and control horses, in the absence and presence of the allosteric regulator, glucose 6 phosphate (G6P). Muscle from homozygous mutant horses also had significantly increased GS phosphorylation at sites 2+2a and significantly higher AMPKα1 (an upstream kinase) expression than controls, likely reflecting a physiological attempt to reduce GS enzyme activity. Recombinant mutant GS was highly active with a considerably lower K_m for UDP-glucose, in the presence and absence of G6P, when compared to wild type GS, and despite its phosphorylation.

CONCLUSIONS

Elevated activity of the mutant enzyme is associated with ineffective regulation via phosphorylation rendering it constitutively active. Modelling suggested that the mutation disrupts a salt bridge that normally stabilises the basal state, shifting the equilibrium to the enzyme's active state.

GENERAL SIGNIFICANCE

This study explains the gain of function pathogenesis in this highly prevalent polyglucosan myopathy.

Multinational Home Use of Closed-Loop Control Is Safe and Effective

OBJECTIVE

To evaluate the efficacy of a portable, wearable, wireless artificial pancreas system (the Diabetes Assistant [DiAs] running the Unified Safety System) on glucose control at home in overnight-only and 24/7 closed-loop control (CLC) modes in patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

At six clinical centers in four countries, 30 participants 18-66 years old with type 1 diabetes (43% female, 96% non-Hispanic white, median type 1 diabetes duration 19 years, median A1C 7.3%) completed the study. The protocol included a 2-week baseline sensor-augmented pump (SAP) period followed by 2 weeks of overnight-only CLC and 2 weeks of 24/7 CLC at home. Glucose control during CLC was compared with the baseline SAP.

RESULTS

Glycemic control parameters for overnight-only CLC were improved during the nighttime period compared with baseline for hypoglycemia (time <70 mg/dL, primary end point median 1.1% vs. 3.0%; P < 0.001), time in target (70-180 mg/dL: 75% vs. 61%; P < 0.001), and glucose variability (coefficient of variation: 30% vs. 36%; P < 0.001). Similar improvements for day/night combined were observed with 24/7 CLC compared with baseline: 1.7% vs. 4.1%, P < 0.001; 73% vs. 65%, P < 0.001; and 34% vs. 38%, P < 0.001, respectively.

CONCLUSIONS

CLC running on a smartphone (DiAs) in the home environment was safe and effective. Overnight-only CLC reduced hypoglycemia and increased time in range overnight and increased time in range during the day; 24/7 CLC reduced hypoglycemia and increased time in range both overnight and during the day. Compared with overnight-only CLC, 24/7 CLC provided additional hypoglycemia protection during the day.

Anxiolytic-like and anxiogenic-like effects of nicotine are regulated via diverse action at β2*nicotinic acetylcholine receptors

BACKGROUND AND PURPOSE

Nicotine dose-dependently activates or preferentially desensitizes β2 subunit containing nicotinic ACh receptors (β2*nAChRs). Genetic and pharmacological manipulations assessed effects of stimulation versus inhibition of β2*nAChRs on nicotine-associated anxiety-like phenotype.

EXPERIMENTAL APPROACH

Using a range of doses of nicotine in β2*nAChR subunit null mutant mice (β2KO; backcrossed to C57BL/6J) and their wild-type (WT) littermates, administration of the selective β2*nAChR agonist, 5I-A85380, and the selective β2*nAChR antagonist dihydro-β-erythroidine (DHβE), we determined the behavioural effects of stimulation and inhibition of β2*nAChRs in the light-dark and elevated plus maze (EPM) assays.

KEY RESULTS

Low-dose i.p. nicotine (0.05 mg·kg(-) 1) supported anxiolysis-like behaviour independent of genotype whereas the highest dose (0.5 mg·kg(-1) ) promoted anxiogenic-like phenotype in WT mice, but was blunted in β2KO mice for the measure of latency. Administration of 5I-A85380 had similar dose-dependent effects in C57BL/6J WT mice; 0.001 mg·kg(-1) 5I-A85380 reduced anxiety on an EPM, whereas 0.032 mg·kg(-1) 5I-A85380 promoted anxiogenic-like behaviour in both the light-dark and EPM assays. DHβE pretreatment blocked anxiogenic-like effects of 0.5 mg·kg(-1) nicotine. Similarly to DHβE, pretreatment with low-dose 0.05 mg·kg(-1) nicotine did not accumulate with 0.5 mg·kg(-1) nicotine, but rather blocked anxiogenic-like effects of high-dose nicotine in the light-dark and EPM assays.

CONCLUSIONS AND IMPLICATIONS

These studies provide direct evidence that low-dose nicotine inhibits nAChRs and demonstrate that inhibition or stimulation of β2*nAChRs supports the corresponding anxiolytic-like or anxiogenic-like effects of nicotine. Inhibition of β2*nAChRs may relieve anxiety in smokers and non-smokers alike.

Multinight "bedside" closed-loop control for patients with type 1 diabetes

BACKGROUND

Studies of closed-loop control (CLC) systems have improved glucose levels in patients with type 1 diabetes. In this study we test a new CLC concept aiming to "reset" the patient overnight to near-normoglycemia each morning, for several consecutive nights.

SUBJECTS AND METHODS

Ten insulin pump users with type 1 diabetes (mean age, 46.4±8.5 years) were enrolled in a two-center (in the United States and Italy) randomized crossover trial comparing 5 consecutive nights of CLC (23:00-07:00 h) in an outpatient setting versus sensor-augmented insulin pump therapy of the same duration at home. Primary end points included time spent in 80-140 mg/dL as measured by continuous glucose monitoring overnight and fasting blood glucose distribution at 7:00 h.

RESULTS

Compared with sensor-augmented pump therapy, CLC improved significantly time spent between 80 and 140 mg/dL (54.5% vs. 32.2%; P<0.001) and between 70 and 180 mg/dL (85.4% vs. 59.1%; P<0.001); CLC reduced the mean glucose level at 07:00 h (119.3 vs. 152.9 mg/dL; P<0.001) and overnight mean glucose level (139.0 vs. 170.3 mg/dL; P<0.001) using a marginally lower amount of insulin (6.1 vs. 6.8 units; P=0.1). Tighter overnight control led to improved daytime control on the next day: the overnight/next-day control correlation was r=0.52, P<0.01.

CONCLUSIONS

Multinight CLC of insulin delivery (artificial pancreas) results in significant improvement in morning and overnight glucose levels and time in target range, with the potential to improve daytime control when glucose levels were "reset" to near-normoglycemia each morning.

Multicenter closed-loop insulin delivery study points to challenges for keeping blood glucose in a safe range by a control algorithm in adults and adolescents with type 1 diabetes from various sites

BACKGROUND

The Control to Range Study was a multinational artificial pancreas study designed to assess the time spent in the hypo- and hyperglycemic ranges in adults and adolescents with type 1 diabetes while under closed-loop control. The controller attempted to keep the glucose ranges between 70 and 180 mg/dL. A set of prespecified metrics was used to measure safety.

RESEARCH DESIGN AND METHODS

We studied 53 individuals for approximately 22 h each during clinical research center admissions. Plasma glucose level was measured every 15-30 min (YSI clinical laboratory analyzer instrument [YSI, Inc., Yellow Springs, OH]). During the admission, subjects received three mixed meals (1 g of carbohydrate/kg of body weight; 100 g maximum) with meal announcement and automated insulin dosing by the controller.

RESULTS

For adults, the mean of subjects' mean glucose levels was 159 mg/dL, and mean percentage of values 71-180 mg/dL was 66% overall (59% daytime and 82% overnight). For adolescents, the mean of subjects' mean glucose levels was 166 mg/dL, and mean percentage of values in range was 62% overall (53% daytime and 82% overnight). Whereas prespecified criteria for safety were satisfied by both groups, they were met at the individual level in adults only for combined daytime/nighttime and for isolated nighttime. Two adults and six adolescents failed to meet the daytime criterion, largely because of postmeal hyperglycemia, and another adolescent failed to meet the nighttime criterion.

CONCLUSIONS

The control-to-range system performed as expected: faring better overnight than during the day and performing with variability between patients even after individualization based on patients' prior settings. The system had difficulty preventing postmeal excursions above target range.

Adding heart rate signal to a control-to-range artificial pancreas system improves the protection against hypoglycemia during exercise in type 1 diabetes

BACKGROUND

We present a clinical trial establishing the feasibility of a control-to-range (CTR) closed-loop system informed by heart rate (HR) and assess the effect of HR information added to CTR on the risk for hypoglycemia during and after exercise.

SUBJECTS AND METHODS

Twelve subjects with type 1 diabetes (five men, seven women; weight, 68.9 ± 3.1 kg; age, 38 ± 3.3 years; glycated hemoglobin, 6.9 ± 0.2%) participated in a randomized crossover clinical trial comparing CTR versus CTR+HR in two 26-h admissions, each including 30 min of mild exercise. The CTR algorithm was implemented in the DiAs portable artificial pancreas platform based on an Android(®) (Google, Mountainview, CA) smartphone. We assessed blood glucose (BG) decline during exercise, the Low BG Index (LBGI) (a measure of hypoglycemic risk), number of hypoglycemic episodes (BG <70 mg/dL) and overall glucose control (percentage time within the target range 70 mg/dL ≤ BG ≤ 180 mg/dL).

RESULTS

Using HR to inform the CTR algorithm reduced significantly the BG decline during exercise (P=0.022), indicated marginally lower LBGI (P=0.3) and fewer hypoglycemic events during exercise (none vs. two events; P=0.16), and resulted in overall higher percentage time within the target range (81% vs. 75%; P=0.2). LBGI and average BG remained unchanged overall, during recovery, and overnight.

CONCLUSIONS

HR-informed closed-loop control can be implemented in a portable artificial pancreas. Although closed loop has been shown to reduce hypoglycemia, adding HR signal may further limit the risk for hypoglycemia during and immediately after exercise. The most prominent effect of adding HR information is reduced BG decline during exercise, without deterioration of overall glycemic control.

Effect of algorithm aggressiveness on the performance of the Hypoglycemia-Hyperglycemia Minimizer (HHM) System

The Hypoglycemia-Hyperglycemia Minimizer (HHM) System aims to mitigate glucose excursions by preemptively modulating insulin delivery based on continuous glucose monitor (CGM) measurements. The "aggressiveness factor" is a key parameter in the HHM System algorithm, affecting how readily the system adjusts insulin infusion in response to changing CGM levels. Twenty adults with type 1 diabetes were studied in closed-loop in a clinical research center for approximately 26 hours. This analysis focused on the effect of the aggressiveness factor on the insulin dosing characteristics of the algorithm and, to a lesser extent, on the glucose control results observed. As the aggressiveness factor increased from conservative to medium to aggressive: the maximum observed insulin dose delivered by the algorithm—which is designed to give doses that are corrective in nature every 5 minutes—increased (1.00 vs 1.15 vs 2.20 U, respectively); tendency to adhere to the subject's nominal basal dose decreased (61.9% vs 56.6% vs 53.4%); and readiness to decrease insulin below basal also increased (18.4% vs 19.4% vs 25.2%). Glucose analyses by both CGM and Yellow Springs Instruments (YSI) indicated that the aggressive setting of the algorithm resulted in the least time spent at levels >180 mg/dL, and the most time spent between 70-180 mg/dL. There was no severe hyperglycemia, diabetic ketoacidosis, or severe hypoglycemia for any of the aggressiveness values investigated. These analyses underscore the importance of investigating the sensitivity of the HHM System to its key parameters, such as the aggressiveness factor, to guide future development decisions.

Safety of outpatient closed-loop control: first randomized crossover trials of a wearable artificial pancreas

OBJECTIVE

We estimate the effect size of hypoglycemia risk reduction on closed-loop control (CLC) versus open-loop (OL) sensor-augmented insulin pump therapy in supervised outpatient setting.

RESEARCH DESIGN AND METHODS

Twenty patients with type 1 diabetes initiated the study at the Universities of Virginia, Padova, and Montpellier and Sansum Diabetes Research Institute; 18 completed the entire protocol. Each patient participated in two 40-h outpatient sessions, CLC versus OL, in randomized order. Sensor (Dexcom G4) and insulin pump (Tandem t:slim) were connected to Diabetes Assistant (DiAs)-a smartphone artificial pancreas platform. The patient operated the system through the DiAs user interface during both CLC and OL; study personnel supervised on site and monitored DiAs remotely. There were no dietary restrictions; 45-min walks in town and restaurant dinners were included in both CLC and OL; alcohol was permitted.

RESULTS

The primary outcome-reduction in risk for hypoglycemia as measured by the low blood glucose (BG) index (LGBI)-resulted in an effect size of 0.64, P = 0.003, with a twofold reduction of hypoglycemia requiring carbohydrate treatment: 1.2 vs. 2.4 episodes/session on CLC versus OL (P = 0.02). This was accompanied by a slight decrease in percentage of time in the target range of 3.9-10 mmol/L (66.1 vs. 70.7%) and increase in mean BG (8.9 vs. 8.4 mmol/L; P = 0.04) on CLC versus OL.

CONCLUSIONS

CLC running on a smartphone (DiAs) in outpatient conditions reduced hypoglycemia and hypoglycemia treatments when compared with sensor-augmented pump therapy. This was accompanied by marginal increase in average glycemia resulting from a possible overemphasis on hypoglycemia safety.

Coat color genotypes and risk and severity of melanoma in gray quarter horses

BACKGROUND

Both graying and melanoma formation in horses have recently been linked to a duplication in the STX17 gene. This duplication, as well as a mutation in the ASIP gene that increases MC1R pathway signaling, affects melanoma risk and severity in gray horses.

OBJECTIVE

To determine if melanoma susceptibility in gray Quarter Horses (QH) is lower than gray horses from other breeds because of decreased MC1R signaling resulting from a high incidence of the MC1R chestnut coat color allele in the QH population.

ANIMALS

A total of 335 gray QH with and without dermal melanomas.

METHODS

Blood or hair root samples were collected from all horses for DNA extraction and genotyping for STX17, ASIP, and MC1R genotypes. Age, sex, and external melanoma presence and grade were recorded. The effect of age and genotype on melanoma presence and severity was evaluated by candidate gene association.

RESULTS

Melanoma prevalence (16%) and grade (0.35) in this QH cohort was lower than that reported in other breeds. Age was significantly associated with melanoma prevalence (P = 5.28 × 10(-11)) and severity (P = 2.2 × 10(-13)). No significant effect of MC1R genotype on melanoma prevalence or severity was identified. An effect of ASIP genotype on melanoma risk was not detected. Low STX17 homozygosity precluded evaluation of the gray allele effect.

CONCLUSION AND CLINICAL IMPORTANCE

Melanoma prevalence and severity is lower in this population of gray QH than what is reported in other breeds. This could be because of the infrequent STX17 homozygosity, a mitigating effect of the MC1R mutation on ASIP potentiation of melanoma, other genes in the MC1R signaling pathway, or differences in breed genetic background.

Feasibility of outpatient fully integrated closed-loop control: first studies of wearable artificial pancreas

OBJECTIVE

To evaluate the feasibility of a wearable artificial pancreas system, the Diabetes Assistant (DiAs), which uses a smart phone as a closed-loop control platform.

RESEARCH DESIGN AND METHODS

Twenty patients with type 1 diabetes were enrolled at the Universities of Padova, Montpellier, and Virginia and at Sansum Diabetes Research Institute. Each trial continued for 42 h. The United States studies were conducted entirely in outpatient setting (e.g., hotel or guest house); studies in Italy and France were hybrid hospital-hotel admissions. A continuous glucose monitoring/pump system (Dexcom Seven Plus/Omnipod) was placed on the subject and was connected to DiAs. The patient operated the system via the DiAs user interface in open-loop mode (first 14 h of study), switching to closed-loop for the remaining 28 h. Study personnel monitored remotely via 3G or WiFi connection to DiAs and were available on site for assistance.

RESULTS

The total duration of proper system communication functioning was 807.5 h (274 h in open-loop and 533.5 h in closed-loop), which represented 97.7% of the total possible time from admission to discharge. This exceeded the predetermined primary end point of 80% system functionality.

CONCLUSIONS

This study demonstrated that a contemporary smart phone is capable of running outpatient closed-loop control and introduced a prototype system (DiAs) for further investigation. Following this proof of concept, future steps should include equipping insulin pumps and sensors with wireless capabilities, as well as studies focusing on control efficacy and patient-oriented clinical outcomes.

Abstract P5-10-04: Metformin mediated upregulation of microRNA-193 triggers apoptosis by decreasing fatty acid synthase

Background: We have previously shown that the anti-diabetic drug metformin kills triple negative (TN) breast cancer cells lines via apoptosis, at lower IC50 than luminal and HER2 subtypes (presented at ENDO, manuscript in preparation). Metformin reportedly shows greater efficacy against stem cells than differentiated cells, reducing mammosphere formation in in non-adherent culture. Fatty acid synthase (FASN) is an enzyme critical for de novo fatty acid synthesis that is overexpressed in breast cancer.

Hypothesis: We hypothesized that miRNAs might be involved in the ability of metformin to preferentially kill TN cell lines at a lower IC50 than luminal A lines.

Methods: TN and luminal A (LA) breast cancer cell lines (MDA-468, HCC70 and MCF7, T47D, respectively) were used to study the effects of 10mM metformin action in vitro, at physiological and hyperglycemic culture conditions. Affymetrix chips Human Gene 1.1 and the miRNA 2.0 were utilized to profile gene and miRNA expression at 6 and 24 hrs. Mimics and lentiviral expression vectors were utilized to manipulate miRNA expression and a luciferase reporter was used to confirm miR-193 direct targeting of the FASN 3′ UTR.

Results: miR-193 is significantly higher in untreated LA as compared to TN cells. MiR-193 increases 2–4 fold within 6 hrs of metformin treatment in both TN, but not LA cell lines. A predicted target of miR-193, fatty acid synthase (FASN), is decreased by 8 fold following 24 hrs 10mM metformin treatment of the TN breast cancer cells. miR-193 directly targets FASN via a binding site in the 3′ UTR, downregulating gene expression. Restoration of miR-193 to TN lines, causes a dramatic decrease in FASN protein in a dose dependent fashion.

Conclusions and future directions: Metformin stimulates an increase in mature miR-193, which mediates the dramatic downregulation of FASN. This occurs coincident with apoptotic cell death. It remains to be determined if FASN is the only relevant direct target of miR-193 in TN cell lines. The addition of exogenous non-targetable FASN, lacking its 3′ UTR, will demonstrate whether this pathway is a primary mechanism of metformin action in TN cells. Future studies will investigate the ability of metformin to inhibit FASN in non-adherent mammosphere (stem cell-like) subpopulations, the role of fatty acid metabolism in mammosphere maintenance and anoikis resistance.

Supported by Komen Breast Cancer Foundation Grants KG100575 (ADT, JKR, SME, NSS) and KG090415 (JKR, DRC)

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-10-04.

Muscle microvascular recruitment predicts insulin sensitivity in middle-aged patients with type 1 diabetes mellitus

AIMS/HYPOTHESIS

Insulin delivery to muscle is rate-limiting for insulin's metabolic action and is regulated by insulin's own action to increase skeletal muscle blood flow and to recruit microvasculature. Microvascular dysfunction has been observed in insulin resistant states. We investigated the relation between insulin's action to recruit microvasculature and its metabolic action in type 1 diabetes.

METHODS

Near euglycaemia was obtained by an overnight insulin infusion during 17 inpatient admissions of participants with type 1 diabetes. This was followed by a 2 h 1 mU kg⁻¹ min⁻¹ euglycaemic-hyperinsulinaemic clamp. Microvascular blood volume (MBV) was assessed using contrast-enhanced ultrasound 10 min before and 30 min after starting the clamp.

RESULTS

We observed that, after overnight modest hyperinsulinaemia (average ≈ 286 pmol/l), MBV was positively related to the steady-state insulin sensitivity measured during the subsequent clamp (r = 0.62, p = 0.008). The more marked hyperinsulinaemia during the clamp (average steady-state insulin ≈ 900 pmol/l) increased MBV in the more insulin resistant participants within 30 min but not in the insulin sensitive participants. The change in MBV during the clamp was negatively correlated to the insulin sensitivity (r = -0.55, p = 0.022). As a result, MBV after 30 min of marked hyperinsulinaemia was comparable between the insulin sensitive and resistant participants.

CONCLUSIONS/INTERPRETATION

We conclude that moderate overnight hyperinsulinaemia recruited microvasculature in the more sensitive participants, while higher levels of plasma insulin were needed for more insulin resistant participants. This suggests that microvascular responsiveness to insulin is one determinant of metabolic insulin sensitivity in type 1 diabetes.

Association of Basal hyperglucagonemia with impaired glucagon counterregulation in type 1 diabetes

Glucagon counterregulation (GCR) protects against hypoglycemia, but is impaired in type 1 diabetes (T1DM). A model-based analysis of in vivo animal data predicts that the GCR defects are linked to basal hyperglucagonemia. To test this hypothesis we studied the relationship between basal glucagon (BasG) and the GCR response to hypoglycemia in 29 hyperinsulinemic clamps in T1DM patients. Glucose levels were stabilized in euglycemia and then steadily lowered to 50 mg/dL. Glucagon was measured before induction of hypoglycemia and at 10 min intervals after glucose reached levels below 70 mg/dL. GCR was assessed by CumG, the cumulative glucagon levels above basal; MaxG, the maximum glucagon response; and RIG, the relative increase in glucagon over basal. Analysis of the results was performed with our mathematical model of GCR. The model describes interactions between islet peptides and glucose, reproduces the normal GCR axis and its impairment in diabetes. It was used to identify a control mechanism consistent with the observed link between BasG and GCR. Analysis of the clinical data showed that higher BasG was associated with lower GCR response. In particular, CumG and RIG correlated negatively with BasG (r = −0.46, p = 0.012 and r = −0.74, p < 0.0001 respectively) and MaxG increased linearly with BasG at a rate less than unity (p < 0.001). Consistent with these results was a model of GCR in which the secretion of glucagon has two components. The first is under (auto) feedback control and drives a pulsatile GCR and the second is feedback independent (basal secretion) and its increase suppresses the GCR. Our simulations showed that this model explains the observed relationships between BasG and GCR during a three-fold simulated increase in BasG. Our findings support the hypothesis that basal hyperglucagonemia contributes to the GCR impairment in T1DM and show that the predictive power of our GCR animal model applies to human pathophysiology in T1DM.

Loss of PKCδ results in characteristics of Sjögren's syndrome including salivary gland dysfunction

OBJECTIVES

Chronic infiltration of lymphocytes into the salivary and lacrimal glands of patients with Sjögren's syndrome (SS) leads to destruction of acinar cells and loss of exocrine function. Protein kinase C-delta (PKCδ) is known to play a critical role in B-cell maintenance. Mice in which the PKCδ gene has been disrupted have a loss of B-cell tolerance, multiple organ lymphocytic infiltration, and altered apoptosis. To determine whether PKCδ contributes to the pathogenesis of SS, we quantified changes in indicators of SS in PKCδ-/- mice as a function of age. Salivary gland histology, function, the presence of autoantibodies, and cytokine expression were examined.

MATERIALS AND METHODS

Submandibular glands were examined for the presence of lymphocytic infiltrates, and the type of infiltrating lymphocyte and cytokine deposition was evaluated by immunohistochemistry. Serum samples were tested by autoantibody screening, which was graded by its staining pattern and intensity. Salivary gland function was determined by saliva collection at various ages.

RESULTS

PKCδ-/- mice have reduced salivary gland function, B220+ B-cell infiltration, anti-nuclear antibody production, and elevated IFN-γ in the salivary glands as compared to PKCδ+/+ littermates.

CONCLUSIONS

PKCδ-/- mice have exocrine gland tissue damage indicative of a SS-like phenotype.

Loss of protein kinase C delta alters mammary gland development and apoptosis

As apoptotic pathways are commonly deregulated in breast cancer, exploring how mammary gland cell death is regulated is critical for understanding human disease. We show that primary mammary epithelial cells from protein kinase C delta (PKCδ) −/− mice have a suppressed response to apoptotic agents in vitro. In the mammary gland in vivo, apoptosis is critical for ductal morphogenesis during puberty and involution following lactation. We have explored mammary gland development in the PKCδ −/− mouse during these two critical windows. Branching morphogenesis was altered in 4- to 6-week-old PKCδ −/− mice as indicated by reduced ductal branching; however, apoptosis and proliferation in the terminal end buds was unaltered. Conversely, activation of caspase-3 during involution was delayed in PKCδ −/− mice, but involution proceeded normally. The thymus also undergoes apoptosis in response to physiological signals. A dramatic suppression of caspase-3 activation was observed in the thymus of PKCδ −/− mice treated with irradiation, but not mice treated with dexamethasone, suggesting that there are both target- and tissue-dependent differences in the execution of apoptotic pathways in vivo. These findings highlight a role for PKCδ in both apoptotic and nonapoptotic processes in the mammary gland and underscore the redundancy of apoptotic pathways in vivo.

Systematic method to assess microvascular recruitment using contrast-enhanced ultrasound. Application to insulin-induced capillary recruitment in subjects with T1DM

Contrast-enhanced ultrasound (CEU) is an ultrasound imaging technique used to assess tissue perfusion. Analysis of microvascular recruitment necessitates the definition of a region of interest (ROI) containing exclusively the tissues to be studied. Conventional ROI selection requires examining the images and drawing the ROI by hand, making the analysis of CEU images non-reproducible and analyst-dependent. We have designed a systematic ROI selection method that is both reproducible and analyst-independent. Microvascular blood volume (MBV) assessed in 21 sequences of images was used to correlate the systematic ROI selection method with the conventional method performed by two independent analysts (correlation of 0.88 and 0.87 respectively) and the MBV sample distribution from the systematic method was not significantly different from those obtained from the conventional one. Using the systematic method, we found no significant insulin-induced capillary recruitment in subjects with type 1 diabetes mellitus, which might be related to the observed low glucose uptake during the hyperinsulinemic euglycemic clamp compared to healthy patients.

Hypoglycemia risk and glucose variability indices derived from routine self-monitoring of blood glucose are related to laboratory measures of insulin sensitivity and epinephrine counterregulation

BACKGROUND

the widely held assumptions that in type 1 diabetes glucose variability may correlate with insulin sensitivity and impaired epinephrine counterregulation have not been studied directly. Here we investigate possible relationships between outpatient measures of glucose variability and risk for hypoglycemia with physiological characteristics: insulin sensitivity and hypoglycemia counterregulation.

METHODS

thirty-four subjects with type 1 diabetes (14 women, 20 men; 37 ± 2.1 years old; glycosylated hemoglobin [HbA1c], 7.6  ±  0.21%) performed self-monitoring of blood glucose (SMBG) for a month, followed by an inpatient hyperinsulinemic euglycemic and hypoglycemic clamp. SMBG field data were used to calculate measures of glucose variability and risk of hypoglycemia, while the clamp procedure was used to evaluate insulin sensitivity and epinephrine response during induced hypoglycemia. Spearman partial correlations adjusted for age, duration of diabetes, body mass index, gender, and HbA1c were used to assess the relationship between the field indices of glucose variability and the physiological characteristics of diabetes.

RESULTS

two glucose variability measures correlated positively (P < 0.01) with insulin sensitivity: the Average Daily Risk Range (ADRR) (ρ = 0.5) and the Glycemic Lability Index (ρ = 0.48). The Low Blood Glucose Index, a measure of the risk for hypoglycemia, and the ADRR correlated negatively with maximum epinephrine response during hypoglycemia: ρ = -0.46, P < 0.01 and ρ = -0.4, P = 0.03, respectively.

CONCLUSIONS

higher insulin sensitivity and lower epinephrine response during hypoglycemia are related to increased glucose variability (as quantified by the ADRR), irrespective of HbA1c and other patient characteristics. Lower epinephrine relates to risk for hypoglycemia as well.

Rechargeable wireless EMG sensor for prosthetic control

Surface electrodes in modern myoelectric prosthetics are often embedded in the prosthesis socket and make contact with the skin. These electrodes detect and amplify muscle action potentials from voluntary contractions of the muscle in the residual limb and are used to control the prosthetic's movement and function. There are a number of performance-related deficiencies associated with external electrodes including the maintenance of sufficient electromyogram (EMG) signal amplitude, extraneous noise acquisition, and proper electrode interface maintenance that are expected to be improved or eliminated using the proposed implanted sensors. This research seeks to investigate the design components for replacing external electrodes with fully-implantable myoelectric sensors that include a wireless interface to the prosthetic limbs. This implanted technology will allow prosthetic limb manufacturers to provide products with increased performance, capability, and patient-comfort. The EMG signals from the intramuscular recording electrode are amplified and wirelessly transmitted to a receiver in the prosthetic limb. Power to the implant is maintained using a rechargeable battery and an inductive energy transfer link from the prosthetic. A full experimental system was developed to demonstrate that a wireless biopotential sensor can be designed that meets the requirements of size, power, and performance for implantation.

Type 1 diabetic drivers with and without a history of recurrent hypoglycemia-related driving mishaps: physiological and performance differences during euglycemia and the induction of hypoglycemia

OBJECTIVE

Collisions are more common among drivers with type 1 diabetes than among their nondiabetic spouses. This increased risk appears to be attributable to a subgroup of drivers with type 1 diabetes. The hypothesis tested is that this vulnerable subgroup is more at risk for hypoglycemia and its disruptive effects on driving.

RESEARCH DESIGN AND METHODS

Thirty-eight drivers with type 1 diabetes, 16 with (+history) and 22 without (-history) a recent history of recurrent hypoglycemia-related driving mishaps, drove a virtual reality driving simulator and watched a videotape of someone driving a simulator for 30-min periods. Driving and video testing occurred in a double-blind, randomized, crossover manner during euglycemia (5.5 mmol/l) and progressive hypoglycemia (3.9-2.5 mmol/l). Examiners were blind to which subjects were +/-history, whereas subjects were blind to their blood glucose levels and targets.

RESULTS

During euglycemia, +history participants reported more autonomic and neuroglycopenic symptoms (P≤0.01) and tended to require more dextrose infusion to maintain euglycemia with the same insulin infusion (P<0.09). During progressive hypoglycemia, these subjects demonstrated less epinephrine release (P=0.02) and greater driving impairments (P=0.03).

CONCLUSIONS

Findings support the speculation that there is a subgroup of type 1 diabetic drivers more vulnerable to experiencing hypoglycemia-related driving mishaps. This increased vulnerability may be due to more symptom "noise" (more symptoms during euglycemia), making it harder to detect hypoglycemia while driving; possibly greater carbohydrate utilization, rendering them more vulnerable to experiencing hypoglycemia; less hormonal counterregulation, leading to more profound hypoglycemia; and more neuroglycopenia, rendering them more vulnerable to impaired driving.

Nonlinear metabolic effect of insulin across the blood glucose range in patients with type 1 diabetes mellitus

BACKGROUND

For insulin therapy to successfully maintain blood glucose (BG) levels of patients with type 1 diabetes mellitus (T1DM) in normoglycemia, it is necessary to understand if the metabolic effect of insulin across the BG range is linear or not.

METHODS

We assess the ability of insulin to lower BG in patients with T1DM in hypoglycemia and hyperglycemia. The net metabolic effect of insulin, defined as the total effect resulting from both reduced endogenous glucose production and increased glucose uptake, was used to define the insulin effectiveness (IE), a measure that indicates the amplitude of glucose lowering that a unit of active insulin can achieve at a given BG level. The IE was assessed in hypoglycemia and hyperglycemia through two separate studies. In the first study, patients were subjected to a hyperinsulinemic euglycemic and hypoglycemic glucose clamp. In the second study, another group of patients were clamped at a hyperglycemic level.

RESULTS

The IE increased by 75% when BG dropped from 90 to 50 mg/dl at a steady rate of 1 mg/dl/min and decreased by 10% when BG was increased from 100 to 200 mg/dl.

CONCLUSIONS

The net metabolic effect of insulin is nonlinear across the BG range and is amplified in hypoglycemia and dampened in hyperglycemia. Most importantly, the BG lowering per unit of insulin is accelerated when falling into hypoglycemia. The understanding of the accelerated risk for hypoglycemia with falling glucose levels will help the design of more robust hypoglycemia prevention and detection systems.

Metabolic Demand of Driving Among Adults with Type 1 Diabetes Mellitus (T1DM)

Recent research suggests that the frequency of driving mishaps is increased in people with Type 1 diabetes (T1DM) as compared to those with Type 2 diabetes or their non-diabetic spouses. This study involved a sample of T1DM drivers and was designed to investigate the metabolic and physiologic demands of driving compared to sitting passively. Participants (N=38) were divided into two groups: the -History group included those reporting no driving mishaps in the past two years, and the +History group included participants reporting at least two such mishaps in the past two years. Glucose utilization rates were determined in participants while: (a) they were driving a virtual reality driving simulator for 30 minutes, and (b) watching a 30-minute video. Blood glucose (BG) levels were maintained at similar levels during both procedures. Other biological variables including heart rate (HR) were monitored. Participants rated their hypoglycemia (low BG) symptoms before and after each of the two procedures. . Participants could self-treat if they perceived they were experiencing hypoglycemia. There were no differences between the two groups. However, glucose utilization rates were significantly higher during the driving scenario (3.83mg/kg/min + 1.7 vs. 3.37 mg/kg/min + 1.6, p=0.047). HR was significantly higher during the driving scenario. Drivers reported more autonomic symptoms during driving and 32% treated perceived hypoglycemia during driving. Driving a virtual reality simulator is associated with increased glucose utilization rates suggesting that driving per se has a metabolic cost and that BG should be measured prior to driving and periodically during long drives.

System to improve AED resuscitation using interactive CPR coaching

A positive impact on cardiac arrest survival has been demonstrated with the substantial reduction in time to defibrillation provided by the widespread deployment of automated external defibrillators (AEDs). However, recent studies have identified the importance of performing chest compressions before defibrillation in facilitating effective recovery from long duration ventricular fibrillation (VF). Despite the importance of cardiopulmonary resuscitation (CPR), effective performance of it in the field is hampered by many problems including the dependence on rescuer technique, which is known to be variable even with trained professionals. This research seeks to enhance survival outcomes following resuscitation. A full experimental system was developed that used an instrumented CPR manikin to provide interactive CPR coaching while collecting performance data. This system was utilized in a controlled human CPR performance study comparing the differences in chest compression performance with and without visual coaching and with and without interactive performance feedback coaching. Results from the human study support a number of conclusions and recommendations. In general using any type of coaching provided improvements in all of the CPR performance measures excluding chest recoil where there was a slight decrease in performance. The statistical results also indicated that the audio/visual coaching conditions provided a more effective coaching condition with respect to chest compression rate. Most notably, the feedback conditions both provided a statistically significant or trends toward improving chest compression effectiveness and produced superior performance as a whole.

Modeling of Calibration Effectiveness and Blood-to-Interstitial Glucose Dynamics as Potential Confounders of the Accuracy of Continuous Glucose Sensors during Hyperinsulinemic Clamp

BACKGROUND

Models of the dynamics of interstitial fluid-based continuous glucose sensors imply a variable sensor deviation from reference blood glucose (BG), depending on both sensor calibration procedure and BG dynamics. These effects could have a significant effect on the cross-interpretation of nonidentical accuracy studies.

METHODS

Hyperinsulinemic euglycemic and hypoglycemic clamps were performed on 39 subjects with type 1 diabetes wearing the Medtronic Continuous Glucose Monitoring System®. Sensor calibration and interstitial glucose (IG) dynamics were modeled and analyzed as potential confounders of sensor deviation from reference BG.

RESULTS

The mean absolute deviation (MAD) of sensor data was 20.9 mg/dl during euglycemia and 24.5 mg/dl during descent into and recovery from hypoglycemia. Computer-generated recalibration reduced MAD to 10.6 and 14.6 mg/dl, respectively. Modeling of IG dynamics reduced the MAD further to 10.0 and 10.4 mg/dl (using idiosyncratic parameters) or to 10.6 and 11.5 mg/dl (using model parameters common for all subjects), respectively.

CONCLUSIONS

The sensor MAD from reference is strongly influenced by the choice of calibration points. Thus, cross-experiment comparisons of sensor accuracy are likely to be heavily dependent on the employed calibration procedures. Demanding calibration points substantially differing in value was found to improve calibration effectiveness. Simulation using existing IG models and population parameters reduced the bias resulting from BG-IG dynamics.

Cocaine-induced alterations in dopamine receptor signaling: Implications for reinforcement and reinstatement

The transition from casual drug use to addiction, and the intense drug craving that accompanies it, has been postulated to result from neuroadaptations within the limbic system caused by repeated drug exposure. This review will examine the implications of cocaine-induced alterations in mesolimbic dopamine receptor signaling within the context of several widely used animal models of addiction. Extensive evidence indicates that dopaminergic mechanisms critically mediate behavioral sensitization to cocaine, cocaine-induced conditioned place preference, cocaine self-administration, and the drug prime-induced reinstatement of cocaine-seeking behavior. The propagation of the long-term neuronal changes associated with recurring cocaine use appears to occur at the level of postreceptor signal transduction. Repeated cocaine treatment causes an up-regulation of the 3',5'-cyclic adenosine monophosphate (cAMP)-signaling pathway within the nucleus accumbens, resulting in a dys-regulation of balanced D1/D2 dopamine-like receptor signaling. The intracellular events arising from enhanced D1-like postsynaptic signaling mediate both facilitatory and compensatory responses to the further reinforcing effects of cocaine.

Testosterone blunts feedback inhibition of growth hormone secretion by experimentally elevated insulin-like growth factor-I concentrations

The present study tests the hypothesis that a high dose of testosterone (Te) drives GH and IGF-I production, in part, by blunting autonegative feedback by the end-product peptide. To this end, we infused saline or recombinant human IGF-I (10 microg/kg.h iv for 6 h) in seven healthy men ages 51-72 yr after administration of placebo (Pl) and Te in randomized order. GH release was quantitated fasting before and after injection of GHRH (1 microg/kg). Statistical analyses disclosed that Te vs. Pl: 1) increased the mean concentration of GH from 0.15 +/- 0.045 to 0.48 +/- 0.11 microg/liter (P = 0.007) and IGF-I from 108 +/- 5.0 to 124 +/- 4.1 (P = 0.047) without altering GHRH-induced GH release; 2) elevated the GH nadir from 0.13 +/- 0.03 to 0.23 +/- 0.06 microg/liter (P < 0.05) in the control session and from 0.06 +/- 0.02 to 0.14 +/- 0.04 microg/liter (P = 0.038) during IGF-I infusion; 3) augmented GHRH-stimulated GH release from 3.0 +/- 0.56 (Pl) to 3.7 +/- 0.52 microg/liter (Te) (P < 0.05) during IGF-I infusion; and 4) did not influence estimated IGF-I kinetics. In summary, supplementation of a high dose of Te in middle-aged and older men attenuates IGF-I feedback-dependent inhibition of nadir and peak GH secretion. Both effects of Te differ from those reported recently for estradiol in postmenopausal women. Accordingly, we postulate that Te and estrogen modulate IGF-I negative feedback differentially.

The effects of time following acute growth hormone administration on metabolic and power output measures during acute exercise

We examined the effects of GH infusion on metabolism and performance measures during acute exercise. Nine males [(X+/-SEM): age 23.7+/-1.9 yr, height 182.6+/-1.6 cm, weight 77.3+/- 2.6 kg, percent fat 17.7+/-1.9%, peak oxygen consumption 37.9 +/- 2.9 ml/kg.min] completed six 30-min randomly assigned bicycle ergometer exercise trials at a power output midway between the lactate threshold and peak oxygen consumption. In five of the six trials, the subjects received a recombinant humanGHinfusion (10 microg/kg, 6-min square wave pulse) at 0800 h, followed by a 30-min exercise trial initiated at one of the following times: 0845, 0930, 1015, 1100, or 1145 h. During one of the six trials, the subject received a saline infusion followed by a 30-min exercise trial initiated at 0845 h. Mixed-effect, repeated-measures ANOVA analyses corrected for multiple comparisons revealed that there were no significant condition effects for total work, caloric expenditure, heart rate response, the blood lactate response, or ratings of perceived exertion response. However, acute GH administration resulted in a lower exercise oxygen consumption without a drop-off in power output. We conclude that the time of exercise initiation after GH infusion does not affect total work, caloric expenditure, heart rate response, blood lactate response, or ratings of perceived exertion but reduces oxygen consumption in response to 30 min of constant load exercise at an intensity above the lactate threshold. The last outcome may suggest that GH administration can improve exercise economy.

Estradiol supplementation modulates growth hormone (GH) secretory-burst waveform and recombinant human insulin-like growth factor-I-enforced suppression of endogenously driven GH release in postmenopausal women

The present study tests the mechanistic postulate that estrogen confers resistance to negative feedback by systemic IGF-I. To this end, eight postmenopausal women received a constant iv infusion of recombinant human (rh)IGF-I (10 micro g/kg.h x 6 h) and saline in randomized order on the 10th day of supplementation with oral estradiol (E(2)) and placebo (Pl). GH secretion was quantitated by 10-min blood sampling, immunochemiluminometry assay, and deconvolution analysis. Administration of E(2) compared with Pl followed by saline infusion: 1) stimulated pulsatile GH secretion ( micro g/liter.6 h), viz., 12 +/- 3.3 (Pl) and 18 +/- 4.6 (E(2)) (mean +/- SEM, paired comparison, P < 0.05); 2) halved the time latency (min) to achieve peak GH secretion after GHRH injection, 24 +/- 2.2 (Pl) and 12 +/- 2.1 (E(2)) (P < 0.01); and 3) did not alter the mass of GH secreted ( micro g/liter) in response to a maximally effective dose of GHRH, 30 +/- 7.2 (Pl) and 37 +/- 11 (E(2)). Exposure to E(2) compared with Pl followed by rhIGF-I infusion: 1) accelerated the rate of decline of GH concentrations by 3.3-fold, viz., absolute slope ( micro g/liter.1000 min), 3.8 (range, 2.5-5.0) (Pl) and 12 (range, 10-14) (E(2)) (P < 0.001); 2) augmented the algebraic decrement in GH concentrations ( micro g/liter) enforced by rhIGF-I infusion, 0.73 +/- 0.21 (Pl) and 1.6 +/- 0.25 (E(2)) (P < 0.01); 3) halved the time delay (min) to peak GHRH-induced GH secretion, 20 +/- 1.2 (Pl) vs. 10 +/- 1.3 (E(2)) min (P < 0.01). In contradistinction, E(2) did not alter: 1) the capability of rhIGF-I to suppress GHRH-stimulated GH secretory burst mass significantly, viz., by 50 +/- 8% (Pl) and 52 +/- 14% (E(2)) (P < 0.05 each vs. saline); 2) the hourly rate of rise of infused (total) IGF-I concentrations; and 3) total and ultrafiltratably free IGF-I concentrations ( micro g/liter) attained at the end of the two rhIGF-I infusions. In summary, compared with Pl, E(2) supplementation in postmenopausal women: 1) amplifies endogenously driven GH secretory-burst mass; 2) initiates rapid onset of GHRH-stimulated GH release; and 3) potentiates IGF-I-dependent suppression of unstimulated GH concentrations. Based upon companion modeling data, we postulate that E(2) facilitates the upstroke and IGF-I enforces the downstroke of high-amplitude GH secretory bursts in estrogen-replete individuals.

CT colonography: determination of optimal CT technique using a novel colon phantom

The aim of this study was to determine the thickest slice at the lowest radiation dose for detection of colon polyps larger than 5mm in diameter at computed tomographic (CT) colonography. A colon phantom containing haustral folds, flexures, and straight segments was constructed of borosilicate. One hundred forty simulated polyps (5, 7, 10, and 12 mm) of various shapes (sessile, flat, and pedunculated) were attached at different colon locations (wall, base of fold, on the fold and fold tip). Polyps were positioned parallel, perpendicular, and oblique to the CT gantry. The air-filled phantom was scanned at different slice thicknesses (1.25-5 mm) and x-ray tube currents (5-308 mA). All polyps were identified in all data sets except one (1.25 mm slice thickness, 5 mA). In this acquisition, image noise reduced polyp visibility, and five of 140 (3%) polyps could not be identified. Unidentified polyps were 5 mm, flat or sessile in shape, located on the colon wall or base of the fold, and oblique or parallel to CT gantry. All tested CT techniques provided optimal polyp detection except settings at 1.25 mm and 5 mAs. Thin collimation (<5 mm) scans may not be necessary to detect clinically significant polyps.

Estradiol supplementation in postmenopausal women doubles rebound-like release of growth hormone (GH) triggered by sequential infusion and withdrawal of somatostatin: evidence that estrogen facilitates endogenous GH-releasing hormone drive

We postulated that short-term estradiol replacement in postmenopausal women may act, in part, by facilitating endogenous GHRH release or action. A prediction of this hypothesis is that estradiol repletion should enhance postsomatostatin rebound GH secretion, which appears to be driven by hypothalamic outflow of GHRH. To this end, we administered placebo and estradiol to eight healthy estrogen-withdrawn postmenopausal volunteers in a prospectively randomized, patient-blinded, within-subject crossover design for a total of 36 d. Rebound release of GH was assessed between d 7 and 36 of intervention on separate randomly ordered mornings after continuous iv infusion of saline or somatostatin (9 micro g/kg.h for 3 h). Secretion was quantitated by frequent (10-min) blood sampling for 7 h, GH chemiluminescence assay, and deconvolution analysis. Compared with placebo, estradiol replacement: 1) stimulated spontaneous pulsatile GH secretion by 3.5-fold (95% confidence interval, 2.1- to 5.6-fold) (P < 0.001); and 2) amplified the mass of GH secreted in response to abrupt somatostatin withdrawal by 2.1-fold (95% confidence interval, 1.3- to 3.4-fold) (P = 0.003). Estrogenic augmentation of rebound-like GH secretion was specific, because the pharmacological effects of exogenous GHRH (1 micro g/kg) and GH-releasing peptide-2 (1 micro g/kg, a synthetic ghrelin analog) were not affected. In summary, short-term supplementation with estradiol in postmenopausal individuals doubles the mass of rebound-like GH secretion induced by abrupt somatostatin withdrawal without modifying stimulation by a pharmacological dose of GHRH or GH-releasing peptide-2. Accordingly, we hypothesize that estradiol stimulates pulsatile GH secretion, at least in part, by enhancing the release and/or action of hypothalamic GHRH.

N-ViroTech--a novel process for the treatment of nutrient limited wastewaters

As pulp and paper wastewaters are mostly deficient in nitrogen and phosphorus, historical practice has dictated that they cannot be effectively treated using microbiological processes without the addition of supplementary nutrients, such as urea and phosphoric acid. Supplementation is a difficult step to manage efficiently, requiring extensive post-treatment monitoring and some degree of overdosing to ensure sufficient nutrient availability under all conditions. As a result, treated wastewaters usually contain excess amounts of both nutrients, leading to potential impacts on the receiving waters such as eutrophication. N-ViroTech is a highly effective alternative treatment technology which overcomes this nutrient deficiency/excess paradox. The process relies on communities of nitrogen-fixing bacteria, which are able to directly fix nitrogen from the atmosphere, thus satisfying their cellular nitrogen requirements. The process relies on manipulation of growth conditions within the biological system to maintain a nitrogen-fixing population whilst achieving target wastewater treatment performance. The technology has significant advantages over conventional activated sludge operation, including: Improved environmental performance. Nutrient loadings in the final treated effluent for selected nitrogen and phosphorus species (particularly ammonium and orthophosphate) may be reduced by over 90% compared to conventional systems; Elimination of nitrogen supplementation, and minimisation of phosphorus supplementation, thus achieving significant chemical savings and resulting in between 25% and 35% savings in operational costs for a typical system; Self-regulation of nutrient requirements, as the bacteria only use as much nitrogen as they require, allowing for substantially less operator intervention and monitoring. This paper will summarise critical performance outcomes of the N-ViroTech process utilising results from laboratory-, pilot-scale and recent alpha-adopter, full-scale trials.