Near Infrared Spectroscopy is not a Surrogate of Venous Occlusion Plethysmography to Assess Microvascular Resting Blood Flow and Function

International Journal of Exercise Science 15(2): 1616-1626, 2022. Near-infrared spectroscopy (NIRS) is a non-invasive technique that measures tissue perfusion using red blood cells oxygen saturation and venous occlusion plethysmography (VOP) is the gold standard to assess microvascular blood flow and function. The purpose of this study was to determine if NIRS can surrogate the microvascular blood flow assessment after an ischemic challenge obtained via VOP. Twenty apparently healthy subjects (10 males and 10 females), aged 18 to 35 years, were recruited for this single session study. NIRS probes were placed 40mm apart along the epicondylar muscles on the right forearm and on the tibialis anterior on the right lower leg, while VOP strain gauges were placed on the largest circumference on both right forearm and calf. Blood flow via VOP and NIRS variables (hemoglobin saturation (SO2), oxygenated hemoglobin (HbO2), and deoxyhemoglobin (HHb) slopes) were assessed before and after 5-min ischemic challenge. Person’s correlations and intra-class correlations (ICC2k) were conducted for each of the NIRS variables vs VOP. There were moderate associations between of SO2 and HbO2 slopes and VOP (r = 0.59, p \u3c 0.01 and r = 0.53, p \u3c 0.05, respectively) at the lower body during resting conditions. There was a poor agreement between NIRS SO2 and VOP at the resting condition in the lower body (ICC2k = 0.45). There were no other associations between any of the other NIRS variables and VOP of the lower and upper body at resting or post-ischemic conditions. In conclusion, NIRS cannot surrogate VOP for measurements of microvascular blood flow at resting or post-ischemic conditions

Quantum Evolution of the Bianchi Type I Model

The behaviour of the flat anisotropic model of the Universe with a scalar field is explored within the framework of quantum cosmology. The principal moment of the account of an anisotropy is the presence either negative potential barrier or positive repelling wall. In the first case occur the above barrier reflection of the wave function of the Universe, in the second one there is bounce off a potential wall. The further evolution of the Universe represents an exponential inflating with fast losses of an anisotropy and approach to the standard cosmological scenario.Comment: Latex, 18 pages, 5 figure

Effects of Pulsatile Exercise-Induced Shear Stress on eNOS, SOD, VCAM-1, and ICAM-1 mRNA Expression of Human Carotid Artery Endothelial Cells

Exercise-induced endothelial shear stress (ESS) has been proposed as a molecular mechanism that regulates the expression of genes involved in the protection against atherosclerosis. However, research on this topic has not considered the pulsatile nature of blood flow for in vivo ESS estimations. PURPOSE: to analyze the effect of pulsatile exercise-induced ESS on endothelial nitric oxide synthase (eNOS), superoxide dismutase (SOD), vascular cell adhesion molecule 1 (VCAM-1), and intercellular adhesion molecule 1 (ICAM-1) mRNA expression of human carotid artery endothelial cells. METHODS: A reverse translational approach was employed for this study. First, an in vivo assessment, a total of 24 apparently healthy young subjects (14 females and 10 males) were recruited to perform two exercise tests on a cycle ergometer. The first test was a maximal incremental test which established the workloads for the next session, according to lactate levels. The second one, performed at least 48 hours after the first exercise test, was a steady-state test at lactate levels of \u3c2 mmol/L for 5 minutes. Left common carotid artery diameters and velocities were recorded through Doppler ultrasound. Microhematocrit measurement was used to determine blood density (ρ) and viscosity (μ). ESS was calculated by Womersley’s approximation, ESS = μ * 2K * Velocity/Diameter, where K is a function of Womersley’s parameter (α). Thereafter, in an in vitro experiment, commercially available human carotid artery endothelial cells were cultured on 6 slides until 95-100% confluence and were randomly assigned to no ESS exposure or were exposed to anterograde pulsatile flow (OsciFlow®) in a flow chamber (Streamer®) for 35 minutes, simulating exercise-induced ESS from the previous assessments. Finally, eNOS, SOD, VCAM-1, and ICAM-1 mRNA expression were compared between both groups, using GAPDH as the housekeeping gene. RESULTS: Exercise-induced ESS for lactate \u3c2 mmol was on average 56.32 (14.82) dynes/cm2. A significant increment on eNOS mRNA expression (P\u3c0.05) and a significant reduction on SOD mRNA expression (P\u3c0.05) were observed on those cells exposed to exercise-induced ESS compared to the group without ESS exposure. No significant differences were detected on mRNA expression of VCAM-1 and ICAM-1 between both groups. CONCLUSION: Pulsatile ESS generated during 35 minutes of low-intensity cycling might favor the upregulation of eNOS and the downregulation of SOD which in turn could provide a molecular explanation of the beneficial effects of exercise on atherosclerosis

Differences between Males and Females in Determining Exercise Intensity

International Journal of Exercise Science 13(4): 1305-1316, 2020. Even though there are physiological differences between males and females, heart rate (HR), ratings of perceived exertion (RPE), power output (PO), oxygen consumption (VO2), and blood lactate (BL) levels have been used as measures of exercise intensity independently of sex. The purpose of this study was to determine differences between sexes in different exercise intensity models. Thirty (15 females) young, healthy individuals were scheduled for two testing visits 48-72 hours apart. During the first testing visit, a graded exercise test (GXT), with BL obtained at the end of each exercise step, was administered on a stationary bicycle to determine peak PO and VO2max. BL during the GXT was used to determine three 5-min steady-state workloads (low: 0-2 mmol/L; moderate: 2-4 mmol/L; and high: \u3e4 mmol/L) for the second test. HR, %HRmax, RPE, PO, %POmax, VO2, %VO2max, and BL were obtained at the end of each steady-state workload. A two-way repeated measures ANOVA was performed to compare all exercise intensity variables obtained during the second test between males and females (α=0.05). Only RPE, %PO, and BL did not differ between sexes on all 3 exercise intensities. HR, %HR, and PO differ between sexes on at least 2 exercise intensities. Females have higher HR and %HR than males for similar %PO. VO2 and %VO2max differ between sexes on at least 1 exercise intensity. Based on the current results, traditional exercise intensity markers are different between males and females. BL and %PO appear to be markers that might be used independently of sex

Biomechanical Characteristics of the Carotid Artery during Aerobic Exercise

Cardiovascular disease is known as the leading cause of death, including coronary artery disease and stroke. Atherosclerosis is responsible for 9 in every 10 cases of stroke. The prevention of stroke and other cardiovascular diseases is possible through aerobic exercise (AE). However, not much is known about the biomechanical characteristics of the carotid artery during AE. PURPOSE: To estimate arterial stiffness in-vivo during submaximal cycling exercise at three different exercise intensities. METHODS: 20 apparently healthy young adults participated in two laboratory visits. First visit, subjects were laid down on a medical bed, in which resting pressure, maximal/minimal artery diameter, and blood flow velocity of the carotid artery were obtained. Three recordings were obtained with a coefficient of variation (CV) of less than 5%. Compliance and stiffness were calculated from the collected data. Thereafter, subjects performed a cardiopulmonary exercise test (CPET) with a graded exercise test protocol. In session two, participants performed for three submaximal intensities stages, three minutes per stage, in which the intensities were determined via lactate levels of initial CPET, low intensity: 4.0 mmol/L. Throughout each stage, the same data as resting conditions were obtained as well as blood flow patterns. RESULTS: There were no differences in any of the biomechanical characteristics between resting and any of the exercise intensities (p\u3e0.05). However, there was a significant interaction by participants (p\u3c0.05). CONCLUSION: Even though the estimation of arterial stiffness per condition was not significantly different, a larger sample size, due to a significant interaction by subject, might show a different result

The Effects of Different Intensities on Eccentric Cycling Blood Flow Patterns at a Concentric Cycling Workload Match

Decrease of blood flow to tissues, due to plaque built by atherosclerosis, increases mortality and morbidity. Homeostatic balance in the vascular system depends directly on endothelial cells, and blood flow, better known as endothelial sheer stress (ESS). Different types of blood flow patterns have been established measured by Reynolds number (Re), and turbulent flow has been associated with the decrease of ESS. Eccentric exercise (ECC) has gained attention as a novel exercise modality that increases muscle performance without increasing metabolic demands; however, little is known about ESS during ECC. PURPOSE: To determine the effects of ECC cycling in blood flow patterns in young, apparently healthy individuals. METHODS: 18 apparently healthy participants, were recruited for two laboratory visits. First visit served to obtain maximum oxygen consumption and peak power (PP), to determine workload intensities, followed by a 5-min familiarization on eccentric ergometer. Second visit on eccentric ergometer assessed blood flow patterns (i.e. ESS and Re measured via imaging ultrasound and Doppler) during a 3-workload steady exercise test at low, moderate, and high intensities. RESULTS: There was an interaction of exercise intensity on antegrade ESS (F(3,53.7)=26.90, p\u3c0.001), but not Sex (p\u3e0.05), and a random effect of participant (p\u3c0.001) and Re anterograde (F(3,53.6)=25.03, p\u3c0.001), but not Sex or random effect of participant (p\u3e0.05). There was an interaction of condition on retrograde ESS (F(3,53.4)=11.21, p\u3c0.001), but not Sex (p\u3e0.05), and a random effect of participant (p\u3c0.001). and Re retrograde (F(3,54.3)=12.34, p\u3c0.001), Sex (F(1,18.5)=4.41, p=0.05), and random effect of participant (p\u3e0.05). CONCLUSION: Eccentric cycling exercise produces exercise-induced blood flow patterns that are intensity-dependent in males and females and these patterns are similar to traditional concentric cycling

Emergent Universe with Exotic Matter

A general framework for an emergent universe scenario has been given which makes use of an equation of state. The general features of the model have also been studied and possible primordial composition of the universe have been suggested.Comment: 11 pages, no fi

Galaxies behind the Galactic plane: First results and perspectives from the VVV Survey

Vista Variables in The Via Lactea (VVV) is an ESO variability survey that is performing observations in near infrared bands (ZYJHKs) towards the Galactic bulge and part of the disk with the completeness limits at least 3 mag deeper than 2MASS. In the present work, we searched in the VVV survey data for background galaxies near the Galactic plane using ZYJHKs photometry that covers 1.636 square degrees. We identified 204 new galaxy candidates by analyzing colors, sizes, and visual inspection of multi-band (ZYJHKs) images. The galaxy candidates colors were also compared with the predicted ones by star counts models considering a more realistic extinction model at the same completeness limits observed by VVV. A comparison of the galaxy candidates with the expected one by Milennium simulations is also presented. Our results increase the number density of known galaxies behind the Milky Way by more than one order of magnitude. A catalog with galaxy properties including ellipticity, Petrosian radii and ZYJHKs magnitudes is provided, as well as comparisons of the results with other surveys of galaxies towards Galactic plane.Comment: 27 pages, 10 figures, 2 tables; in press at The Astronomical Journa