0000000000113925
AUTHOR
Juris Imants Aivars
showing 10 related works from this author
Assessment of conduit artery vasomotion using photoplethysmography
2013
Vasomotion is a spontaneous oscillation of vascular tone. The phenomenon has been observed in small arterioles and capillaries as well as in the large conduit arteries. The layer of smooth muscle cells that surrounds a blood vessel can spontaneously and periodically change its tension and thereby the arterial wall stiffness also changes. As the understanding of the phenomenon is still rather obscure, researchers would benefit from a low-cost and reliable investigation technique such as photoplethysmography (PPG). PPG is an optical blood pulsation measurement technique that can offer substantial information about the arterial stiffness. The aims of this pilot study were to evaluate the usefu…
Two-stage multi-Gaussian fitting of conduit artery photoplethysmography waveform during induced unilateral hemodynamic events.
2014
Photoplethysmography (PPG) is an optical technique with high diagnostic potential, yet clinical applications remain underdeveloped. Standardization of signal recording and quantification of waveform are essential prerequisites for broader clinical use. The aim of this study was to utilize a two-stage multi-Gaussian fitting technique in order to examine the parameters of conduit artery PPG waveform recorded during increasing the unilateral regional vascular resistance (RVR). This study was conducted on 14 young and healthy volunteers; various external compressions (ECs) were performed by inflating a tight cuff at 0, 40, 80, and 200 mmHg, while registering femoral PPG (wavelength 880 nm), dia…
Effect of acute systemic hypoxia on human cutaneous microcirculation and endothelial, sympathetic and myogenic activity
2015
The regulation of cutaneous vascular tone impacts vascular vasomotion and blood volume distribution as a challenge to hypoxia, but the regulatory mechanisms yet remain poorly understood. A skin has a very compliant circulation, an increase in skin blood flow results in large peripheral displacement of blood volume, which could be controlled by local and systemic regulatory factors. The aim of this study was to determine the acute systemic hypoxia influence on blood flow in skin, local regulatory mechanism fluctuations and changes of systemic hemodynamic parameters. Healthy subjects (n=11; 24.9±3.7years old) participated in this study and procedures were performed in siting position. After 2…
Static magnetic field influence on rat brain function detected by heart rate monitoring.
2004
The aim of the present study was to identify the effects of a static magnetic field (SMF) on rat brain structures that control autonomic functions, specifically heart rate and heart rhythmicity. The experiments were carried out on 44 male Wistar rats under ketamine-xylazine anesthesia. SMF was induced using samarium-cobalt fused magnets (20 x 20 x 10 mm in size) placed bitemporally. Magnetic induction intensity was 100 mT on the surface of the head. Duration of magnetic field application was 15 min. An electrocardiogram was recorded from limb lead II, and both heart rate (average duration of cardiac cycles) and heart rhythmicity were analyzed before and after SMF application. SMF evoked cha…
Interleukin-6 gene promoter –174G/C polymorphism and insulin resistance: a pilot study
2007
Background: The aim of this pilot study was to evaluate the relationship between interleukin-6 promoter -174G/C (IL-6 -174G/C) polymorphism and insulin resistance (IR) in obese patients with coronary heart disease (CHD). Methods: Twenty obese male patients with CHD were selected from a larger database of patients (n=606). IL-6 -174G/C genotype was previously analysed and only homozygotes with the CC genotype (n=10) or GG genotype (n=10) were selected. IR was measured using the homeostasis model assessment for IR (HOMA-IR) method. Results: Differences in age, body mass index, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), triglyceride (T…
Usability of photoplethysmography method in estimation of conduit artery stiffness
2011
Three channel photoplethysmography (PPG) signal waveform studies of leg conduit arteries during a provocative occlusion test were performed. PPG waveform second derivative amplitude ratio and arterial pulse wave velocity values showed significant correlations with ultrasound (US) reference method of local and regional arterial stiffness (AS), showing the ability to use PPG for AS change quantitative assessment.
Relation of inflammatory chemokines to insulin resistance and hypoadiponectinemia in coronary artery disease patients
2009
Although many studies have shown that the metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM) both are associated with chronic inflammatory state and are risk factors for coronary artery disease (CAD), it is still unclear which condition is a more important contributor to the increased production of inflammatory chemokines. The purpose of this study was to assess monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8) levels and their association with insulin resistance and adiponectin concentrations in CAD patients, who were categorized as having T2DM, MS, or neither.CAD male patients were categorized into three groups: 24 non-obese patients with T2DM (D), 24 obese pati…
Nail fold capillary diameter changes in acute systemic hypoxia.
2013
The present study was undertaken to determine the effect of arterial blood hypoxemia induced by acute systemic hypoxia (pO2=12%) on capillary recruitment and diameter, and red blood cell (RBC) velocity in human nail fold capillaries during rest, arterial post-occlusive reactive hyperemia (PRH), and venous occlusion (VO) using intravital video-capillaroscopy. Capillary recruitment was unchanged in acute systemic hypoxia (H) versus normoxia (N). There was no difference in RBC velocity measurements between normoxia and hypoxia (P<0.63). However, a statistically significant increase in nail fold capillary total width (N, 39.9±9.1 vs. H, 42.7±10.3 μm; P<0.05), apical diameter (N, 15.5±4.3 vs. H,…
Relation of Endothelial Dysfunction and Adipokines Levels to Insulin Resistance in Metabolic Syndrome Patients
2009
Relation of Endothelial Dysfunction and Adipokines Levels to Insulin Resistance in Metabolic Syndrome Patients Obese metabolic syndrome (MS) patients were categorised into three groups: 44 with type 2 diabetes mellitus (T2DM)(D); 20 with T2DM and coronary artery disease (CAD) (DC), and 26 with MS alone (M). Eighteen healthy subjects were selected as controls (C). Insulin resistance (IR) was assessed by HOMA-IR. Adiponectin, tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and interleukin-8 (IL-8) concentrations were measured by xMAP technology. Endothelin-1 (ET-1) was determined by ELISA. We used laser Doppler imaging for evaluating cut…