1.
Reduction in peripheral vascular resistance predicts improvement in insulin clearance following weight loss.
Straznicky, NE, Grima, MT, Sari, CI, Lambert, EA, Phillips, SE, Eikelis, N, Kobayashi, D, Hering, D, Mariani, JA, Dixon, JB, et al
Cardiovascular diabetology. 2015;:113
Abstract
BACKGROUND The hyperinsulinemia of obesity is a function of both increased pancreatic insulin secretion and decreased insulin clearance, and contributes to cardiovascular risk. Whilst weight loss is known to enhance insulin clearance, there is a paucity of data concerning the underlying mechanisms. This study was conducted to examine the inter-relationships between changes in sympathetic nervous system (SNS) activity, vascular function and insulin clearance during a weight loss program. METHODS Seventeen non-smoking, un-medicated individuals aged 55 ± 1 years (mean ± SEM), body mass index (BMI) 33.9 ± 1.7 kg/m(2), underwent a 4-month hypocaloric diet (HCD), using a modified Dietary Approaches to Stop Hypertension diet, whilst seventeen age- and BMI-matched subjects acted as controls. Insulin sensitivity and insulin clearance were assessed via euglycemic hyperinsulinemic clamp (exogenous insulin clearance); hepatic insulin extraction was calculated as fasting C-peptide to insulin ratio (endogenous insulin clearance); SNS activity was quantified by microneurographic nerve recordings of muscle sympathetic nerve activity (MSNA) and whole-body norepinephrine kinetics; and vascular function by calf venous occlusion plethysmography and finger arterial tonometry. RESULTS Weight loss averaged -8.3 ± 0.6% of body weight in the HCD group and was accompanied by increased clamp-derived glucose utilization (by 20 ± 9%, P = 0.04) and exogenous insulin clearance (by 12 ± 5%, P = 0.02). Hepatic insulin extraction increased from 6.3 ± 0.8 to 7.1 ± 0.9 (P = 0.09). Arterial norepinephrine concentration decreased by -12 ± 5%, whole-body norepinephrine spillover rate by -14 ± 8%, and MSNA by -9 ± 5 bursts per 100 heartbeats in the HCD group (P all >0.05 versus control group). Step-wise regression analysis revealed a bidirectional relationship between enhanced exogenous insulin clearance post weight loss and reduction in calf vascular resistance (r = -0.63, P = 0.01) which explained 40% of the variance. Increase in hepatic insulin extraction was predicted by enhanced finger reactive hyperaemic response (P = 0.006) and improvement in oral glucose tolerance (P = 0.002) which together explained 64% of the variance. CONCLUSIONS Insulin clearance is independently and reciprocally associated with changes in vascular function during weight loss intervention. Trial registration ClinicalTrials.gov: NCT01771042 and NCT00408850.
2.
Reproducibility of pulse contour analysis in children before and after maximal exercise stress test: the Physical Activity and Nutrition in Children (PANIC) study.
Veijalainen, A, Tompuri, T, Lakka, HM, Laitinen, T, Lakka, TA
Clinical physiology and functional imaging. 2011;(2):132-8
Abstract
OBJECTIVE Arterial stiffness index (SI) and reflection index (RI) from digital pulse contour analysis have been shown to be good measures of arterial stiffness and may be useful in the evaluation of endothelial function. Finger skin temperature (FST) is also considered to reflect peripheral circulatory functions. We evaluated the reproducibility of SI, RI and FST before and after the exercise stress test. METHODS The subjects were 36 children (16 boys, 20 girls) 6-8 years of age. We measured SI, RI and FST at rest both before and after the exercise stress test on a cycle ergometer and repeated these measurements within 5-14 days. The reproducibility of SI, RI and FST was evaluated by calculating intraclass correlation coefficients (ICC), coefficients of variation (CV%) and 95% limits of agreements. RESULTS SI had a greater reproducibility after the exercise stress test than before it (CV% 4·8 versus 6·3%, ICC 0·548 versus 0·438). RI had a better ICC (0·689 versus 0·416) but a higher CV% (28·6 versus 18·7%) after the exercise stress test than before it. Relative change in response to the exercise stress test in SI (-1·5% at first visit and 0·4% at second visit) was not as dramatic as in RI (-49·3% at first visit and -46·5% at second visit). The reproducibility of FST was also better after the exercise test than before it (CV% 5·7 versus 10·0%, ICC 0·509 versus 0·503). CONCLUSION In healthy children, the reproducibility of SI, RI and FST was relatively good, especially after the exercise stress test.
3.
The effect of metoprolol alone and combined metoprolol-felodipin on the digital microcirculation of patients with primary Raynaud's syndrome.
Csiki, Z, Garai, I, Shemirani, AH, Papp, G, Zsori, KS, Andras, C, Zeher, M
Microvascular research. 2011;(1):84-7
Abstract
OBJECTIVES Calcium channel inhibitors have beneficial impact on microcirculation, but beta-blocker effect is controversial. Clinicians still do not agree on beta-blocker combination with other treatments in the management of impaired microcirculation. The aim of the present study was to describe the effects of beta-blocker metoprolol monotherapy and combined with calcium channel inhibitor felodipin on digital microcirculation in primary Raynaud's syndrome. METHODS We enrolled in this study 46 patients suffering from both hypertension and primary Raynaud's syndrome. Fifteen patients were treated with beta-blocker monotherapy (metoprolol), 13 received combined beta-blocker and calcium channel blocker therapy (felodipin and metoprolol), while 18 patients without any medications served as controls. Measurement of digital microcirculation was carried out with laser Doppler scanner. RESULTS AND CONCLUSIONS Our investigation concludes that the concurrent administration of beta-blockers with calcium channel inhibitors positively reduces symptoms in patients suffering from Raynaud's syndrome.
4.
Alternate site glucose testing: a crossover design.
Bennion, N, Christensen, NK, McGarraugh, G
Diabetes technology & therapeutics. 2002;(1):25-33; discussion 45-7
Abstract
A crossover design study was conducted to determine if reducing pain, by using alternative sites off the finger tip, would increase testing frequency and improve clinical outcome as measured by hemoglobin A1c (HbA1c). Subjects with type 1 and type 2 diabetes tested with the FreeStyle meter (group 1) or tested with their original meter (group 2). After three months the subjects used the alternate meter. Testing frequency and blood glucose concentrations were recorded for the month before the study began and monthly thereafter. HbA1c was tested initially, at the crossover point, and at study conclusion. Insulin users increased testing frequency from 2.4 to 3.0 tests/day. Testing frequency for non-insulin users remained the same at 1.5 tests/day. Testing frequency was the same with the FreeStyle and the original meters. The average HbA1c was 7.4% (SD 1.5%) initially, 7.3% (SD 1.5%) at the crossover point, and 6.9% (SD 1.1%) at study conclusion. There was no significant difference in HbA1c measurements between meter types. Preference rankings were 76% for FreeStyle, 20% for their original meter, and 4% preferred both meters equally. This population tended to be in good glycemic control with 70% having HbA1c at < or = 8.0 at study initiation. Subjects preferred testing with the FreeStyle meter (76%), but did not increase testing frequency. Study participants tended to be in good testing compliance and glycemic control with little room for improvement. A population in poor glucose control might show differences in outcome with off site monitoring.