-
1.
Insulin resistance and coronary flow velocity reserve in patients with autosomal dominant polycystic kidney disease.
Turkmen, K, Tufan, F, Alpay, N, Kasıkcioglu, E, Oflaz, H, Ecder, SA, Ecder, T
Internal medicine journal. 2012;(2):146-53
Abstract
BACKGROUND Cardiovascular problems are a major cause of morbidity and mortality in patients with autosomal dominant polycystic kidney disease (ADPKD). AIM: The aim of this study was to investigate coronary flow velocity reserve (CFVR) as a marker of endothelial dysfunction, carotid intima media thickness (CIMT) as a marker of subclinical organ damage and insulin resistance (IR) as a cardiovascular risk factor in patients with ADPKD. METHODS Twenty-two normotensive ADPKD patients with well-preserved renal function and 19 healthy subjects were included in the study. Creatinine clearances were calculated by the Cockcroft-Gault formula. The homeostasis model of IR (HOMA-IR) was used to measure IR. CIMT was measured by high-resolution vascular ultrasound. CFVR was calculated as the ratio of hyperaemic to baseline diastolic peak velocities by echocardiography. RESULTS There was no significant difference between the two groups regarding age, gender, body mass index, systolic and diastolic blood pressures, cholesterol and triglyceride levels. However, CIMT and HOMA-IR were significantly increased and CFVR was significantly decreased in patients with ADPKD compared with healthy subjects. CONCLUSIONS The findings of decreased CFVR, increased CIMT and increased IR suggest that cardiovascular risk is elevated even in the early stages of ADPKD.
-
2.
Lifetime fruit and vegetable consumption and arterial pulse wave velocity in adulthood: the Cardiovascular Risk in Young Finns Study.
Aatola, H, Koivistoinen, T, Hutri-Kähönen, N, Juonala, M, Mikkilä, V, Lehtimäki, T, Viikari, JS, Raitakari, OT, Kähönen, M
Circulation. 2010;(24):2521-8
Abstract
BACKGROUND The relationships between childhood lifestyle risk factors and adulthood pulse wave velocity (PWV) have not been reported. We studied whether childhood and adulthood lifestyle risk factors are associated with PWV assessed in adulthood. METHODS AND RESULTS The study cohort comprised 1622 subjects of the Cardiovascular Risk in Young Finns Study followed up for 27 years since baseline (1980; aged 3 to 18 years) with lifestyle risk factor data available since childhood. Arterial PWV was measured in 2007 by whole-body impedance cardiography device. Vegetable consumption in childhood was inversely associated with adulthood PWV (β=-0.06, P=0.02), and this association remained significant (β=-0.07, P=0.004) when adjusted for traditional risk factors (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, systolic blood pressure, body mass index, and smoking). Vegetable consumption was also an independent predictor of PWV in adulthood when adjusted for lifestyle or traditional risk factors (β=-0.08, P=0.002 and β=-0.07, P=0.0007, respectively). Persistently high consumption of both fruits and vegetables from childhood to adulthood was associated with lower PWV compared with persistently low consumption (P=0.03 for both). The number of lifestyle risk factors (the lowest quintile for vegetable consumption, fruit consumption, physical activity, and smoking) in childhood was directly associated with PWV in adulthood (P=0.001). This association remained significant when adjusted for the number of lifestyle risk factors in adulthood (P=0.003). CONCLUSIONS These findings suggest that lifetime lifestyle risk factors, with low consumption of fruits and vegetables in particular, are related to arterial stiffness in young adulthood.
-
3.
The comparative effects of sevoflurane versus isoflurane on cerebrovascular carbon dioxide reactivity in patients with diabetes mellitus.
Kadoi, Y, Takahashi, K, Saito, S, Goto, F
Anesthesia and analgesia. 2006;(1):168-72, table of contents
Abstract
The use of volatile anesthetics has been reported to alter cerebrovascular carbon dioxide (CO2) reactivity. We examined the comparative effects of sevoflurane versus isoflurane on cerebrovascular CO2 reactivity in 40 patients with diabetes mellitus. Anesthesia was maintained with either 1.0 minimum alveolar anesthetic concentration of sevoflurane or 1.0 minimum alveolar anesthetic concentration of isoflurane in 33% oxygen and 67% nitrous oxide. A 2.5-MHz pulsed transcranial Doppler probe was attached to the patient's head at the right temporal window for continuous measurement of mean blood flow velocity in the middle cerebral artery. After establishing baseline middle cerebral artery velocity values and cardiovascular hemodynamics, we increased end-tidal CO2 by decreasing ventilatory frequency by 2-5 breaths/min and repeated the measurements. These were then used to calculate absolute and relative CO2 reactivity. Absolute CO2 reactivity was less in insulin-treated patients with either sevoflurane or isoflurane compared with those patients on oral antidiabetic drugs or dietary therapy (sevoflurane group: diet = 2.6 +/- 0.6; oral antidiabetic drug = 2.5 +/- 0.8; insulin = 1.6 +/- 0.8*; isoflurane group: diet = 3.3 +/- i0.7; oral antidiabetic drug = 3.4 +/- 0.7; insulin = 1.9 +/- 0.7* cm.s(-1).mm Hg(-1); *P < 0.05, respectively). Relative CO2 reactivity showed a similar pattern in the diet-controlled and oral antidiabetic groups, absolute and relative CO2 reactivities were lower with sevoflurane versus isoflurane. Hence, we conclude that cerebrovascular CO2 reactivity in insulin-dependent patients is impaired under both sevoflurane and isoflurane anesthesia.
-
4.
Age and regional specificity of peak limb vascular conductance in women.
Ridout, SJ, Parker, BA, Proctor, DN
Journal of applied physiology (Bethesda, Md. : 1985). 2005;(6):2067-74
Abstract
The influence of age on limb vasodilator capacity in women is unclear. The objectives of this study were to characterize and compare age-associated changes in forearm and calf peak vascular conductance (VC(peak); a functional index of arterial structure) in women and to identify physiological characteristics predictive of variation in limb-specific VC(peak). Peak conductance (plethysmographic flow/mean arterial pressure), VC(peak) of the forearm (forearm VC(peak)), and calf (calf VC(peak)) after 10 min of arterial occlusion were measured in 58 healthy, normally active women aged 21-79 yr. Aerobic capacity (cycle peak oxygen uptake), arterial health (pulse-wave velocity, ankle-brachial index), total cholesterol, limb-specific tissue composition (dual-energy X-ray absorptiometry), and isometric strength (handgrip, plantar flexion) were also assessed. The relative decline in calf VC(peak) with age (-6.8% per decade, P < 0.001) was greater than the forearm (-4.4% per decade, P = 0.004), in contrast to results previously reported for men (forearm decline > calf decline). Limb VC(peak) per kilogram muscle declined with age in the calf (-6.0% per decade; P = 0.002), but not the forearm (P = 0.12). Age, cholesterol, and regional tissue composition were significant predictors of peak conductance in both limbs; however, age was a stronger predictor of peak conductance in the calf. These results suggest that healthy aging is associated with a linear decline in limb vasodilator capacity in women, but the magnitude of this effect is region specific. Further research will be required to determine whether the decline in lower extremity vasodilator capacity with age explains diminished exercising leg vasodilation in older women.
-
5.
Clinical microneedle injection of methyl nicotinate: stratum corneum penetration.
Sivamani, RK, Stoeber, B, Wu, GC, Zhai, H, Liepmann, D, Maibach, H
Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI). 2005;(2):152-6
Abstract
BACKGROUND/PURPOSE In recent years, microneedles were proposed as a method to painlessly deliver drugs past the stratum corneum. Microneedles have been fabricated in several designs, but limited studies have tested microneedle injections in humans. In this work, we compare microneedle injections with topical application (TA) to investigate if microneedles enhance in vivo drug delivery past the stratum corneum. METHOD In vitro tests were used to measure microneedle pressures and injection volumes. In vivo microneedle injections were performed on the volar forearm of 11 healthy volunteers. Two sets of microneedles, pointed and symmetric, were used to develop microneedle/syringe apparatuses that were used to inject approximately 1 microL of 0.1 M methyl nicotinate, and were compared against TA. A Laser Doppler Perfusion Monitor was used to record maximum blood flow and the time to maximum blood flow at the treatment sites. RESULTS Pointed and symmetric microneedle-injected sites showed a significantly faster time to maximum blood flow than TA. The pointed microneedle injections also resulted in a higher maximum blood flux. Volunteers reported feeling pressure but no pain from the microneedles during the injections. CONCLUSION The microneedles aid in bypassing the stratum corneum and enhance drug delivery through it. The design of the microneedle influences its delivery capabilities, because the pointed microneedles seem to be less susceptible to clogging during the injection.
-
6.
Beneficial effects of fenofibrate to improve endothelial dysfunction and raise adiponectin levels in patients with primary hypertriglyceridemia.
Koh, KK, Han, SH, Quon, MJ, Yeal Ahn, J, Shin, EK
Diabetes care. 2005;(6):1419-24
Abstract
OBJECTIVE Improvement in endothelial function is predicted to improve insulin sensitivity, and this may be one mechanism by which fenofibrate decreases the incidence of coronary heart disease. We hypothesize fenofibrate improves endothelial function by enhancing insulin sensitivity. RESEARCH DESIGN AND METHODS We administered placebo or fenofibrate 200 mg daily for 8 weeks to 46 patients with primary hypertriglyceridemia (24 had metabolic syndrome). This study was randomized, double blind, placebo controlled, and crossover in design. RESULTS Compared with placebo, fenofibrate decreased total cholesterol, non-HDL cholesterol, apolipoprotein B, and triglycerides and increased HDL cholesterol and apolipoprotein A-I (all P < 0.001) while tending to decrease LDL cholesterol (P = 0.069). Fenofibrate significantly improved percent flow-mediated dilator response to hyperemia by 48 +/- 5% (P < 0.001) and lowered plasma levels of high-sensitivity C-reactive protein (hsCRP) relative to baseline measurements from 0.80 to 0.70 mg/l (P = 0.001) and fibrinogen levels by 16 +/- 3% (P < 0.001). Compared with placebo, fenofibrate therapy significantly increased plasma levels of adiponectin by 14 +/- 5% (P = 0.008) and increased insulin sensitivity (assessed by quantitative insulin sensitivity check index [QUICKI]) by 6 +/- 2% (P = 0.048). There were significant correlations between percent changes in adiponectin levels and percent changes in flow-mediated dilation (r = 0.401, P = 0.006), hsCRP (r = -0.443, P = 0.002), or QUICKI (r = 0.292, P = 0.049). Multivariate regression analysis showed that only changes in adiponectin levels persisted as an independent predictor of changes in flow-mediated dilation (r = 0.504, P = 0.013). Overall, we observed similar results in 24 patients with metabolic syndrome. CONCLUSIONS Fenofibrate therapy significantly improved percent flow-mediated dilator response to hyperemia, reduced inflammation marker levels, increased adiponectin levels, and improved insulin sensitivity in hypertriglyceridemic or metabolic syndrome patients.
-
7.
On the flow dependency of the electrical conductivity of blood.
Hoetink, AE, Faes, TJ, Visser, KR, Heethaar, RM
IEEE transactions on bio-medical engineering. 2004;(7):1251-61
Abstract
Experiments presented in the literature show that the electrical conductivity of flowing blood depends on flow velocity. The aim of this study is to extend the Maxwell-Fricke theory, developed for a dilute suspension of ellipsoidal particles in an electrolyte, to explain this flow dependency of the conductivity of blood for stationary laminar flow in a rigid cylindrical tube. Furthermore, these theoretical results are compared to earlier published measurement results. To develop the theory, we assumed that blood is a Newtonian fluid and that red blood cells can be represented by oblate ellipsoids. If blood flows through a cylindrical tube, shear stresses will deform and align the red blood cells with one of their long axes aligned parallel to the stream lines. The pathway of a low-frequency (< 1 MHz) alternating electrical current will be altered by this orientation and deformation of the red blood cells. Consequently, the electrical conductivity in the flow direction of blood increases. The theoretically predicted flow dependency of the conductivity of blood corresponds well with experimental results. This theoretical study shows that red blood cell orientation and deformation can explain quantitatively the flow dependency of blood conductivity.
-
8.
The angiographic and clinical benefits of mibefradil in the coronary slow flow phenomenon.
Beltrame, JF, Turner, SP, Leslie, SL, Solomon, P, Freedman, SB, Horowitz, JD
Journal of the American College of Cardiology. 2004;(1):57-62
Abstract
OBJECTIVES The aim of the study was to assess the angiographic and clinical benefits of the calcium T-channel blocker, mibefradil, in the coronary slow flow phenomenon (CSFP). BACKGROUND The CSFP is characterized by delayed vessel opacification on angiography (Thrombolysis In Myocardial Infarction [TIMI]-2 flow) in the absence of obstructive epicardial coronary disease and is often associated with recurrent chest pain. METHODS A total of 10 CSFP patients (46 +/- 9 years) underwent angiography before and 30 min after 50 mg mibefradil; off-line blinded analysis of angiographic data included comparisons of epicardial vessel diameter, TIMI flow grade and TIMI frame count. We also performed a randomized, double-blind, placebo-controlled, cross-over study to examine the long-term efficacy of mibefradil 100 mg/day on the frequency of total angina, prolonged angina (i.e., persisting >20 min) episodes, and sublingual nitrate consumption, during consecutive one-month treatment periods in 20 patients (age 51 +/- 12 years) with the CSFP. RESULTS Without changing epicardial vessel diameter or rate-pressure product, mibefradil reduced the number of vessels exhibiting TIMI-2 flow from 18 to 5; furthermore, mibefradil significantly improved the TIMI frame count only in those vessels exhibiting TIMI-2 flow (28 +/- 18%, p < 0.005). Compared with placebo, mibefradil significantly reduced total angina frequency by 56% (p < 0.001), prolonged episodes of angina by 74% (p < 0.001), and sublingual nitrate consumption by 59% (p < 0.01); furthermore, mibefradil improved physical quality of life as assessed by the Health Outcome Study Short Form-36. CONCLUSIONS These angiographic and clinical improvements produced by mibefradil support a microspastic pathogenesis of the CSFP.
-
9.
Effective flow performances and dialysis doses delivered with permanent catheters: a 24-month comparative study of permanent catheters versus arterio-venous vascular accesses.
Canaud, B, Leray-Moragues, H, Kerkeni, N, Bosc, JY, Martin, K
Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2002;(7):1286-92
Abstract
BACKGROUND Permanent venous catheters have emerged as a long-term vascular access option for renal replacement therapy in end-stage renal disease patients. The design and venous location of catheter devices bear intrinsic flow limitations that may negatively affect the adequacy of dialysis and the patient outcome. There is limited data comparing the long-term dialysis adequacy delivered with permanent catheters vs arterio-venous vascular accesses (AVA). METHODS To explore this problem, we conducted a prospective 24-month trial comparing the flow performances and dialysis dose (Kt/Vdp) deliveries of both access options in a group of 42 haemodialysis patients during two study phases. During the first 12 months the patients completed a treatment period by means of permanent dual silicone catheters (DualKT). Then they were transferred to an AVA (40 native arterio-venous fistulas and two PTFE grafts) and monitored for an additional 12-month period. Assessments of flow adequacy and dialysis quantification were performed monthly. RESULTS Dialysis adequacy was achieved in all cases. No patient had to be transferred prematurely to the AVA because of catheter failure. Three catheters had to be replaced due to bacteraemia in three patients. The mean effective blood flow rates achieved were 316+/-3.5 ml/min and 340+/-3.3 ml/min with DualKT and AVA, respectively, for a pre-set machine blood flow of 348+/-2.2 ml/min. Recirculation rates evaluated with the 'slow blood flow' method were 8.6+/-0.6 and 12.1+/-0.8% for DualKT and AVA using mean values of the solute markers urea and creatinine. Due to the possibility of a comparison veno-venous vs arterio-venous blood circulation, a corrected arterio-venous access recirculation could be derived from the difference between the two, which was around 3%. The blood flow resistance of the DualKT was slightly higher than with AVA as indicated by venous pressure differences. Kt/Vdp delivered was 1.37+/-0.02 and 1.45+/-0.02 with DualKT and AVA access respectively. The loss of dialysis efficacy using catheters was estimated at 6%. However, in all cases Kt/Vdp values remained above the recommended values (Kt/Vdp > or = 1.2). Protein nutritional state, as well as conventional clinical and biochemical markers of dialysis adequacy, remained in the optimal range. CONCLUSION Permanent venous catheters provide adequate haemodialysis on a long-term basis. Flow performances and dialysis doses are slightly reduced (5-6%) when compared with AVA. Regular assessment of dialysis performance is strongly recommended to assure dialysis adequacy. Lengthening dialysis time may represent a simple and efficient tool to compensate for reduced flow performances with catheter use.