Temos aktualumas: Sportinėje praktikoje taikomi įvairaus intensyvumo statiniai ir dinaminiai fiziniai pratimai. Statinė ir dinaminė ištvermė yra kaip darbingumo rodiklis, priklausantis nuo maksimalių tiriamojo pastangų. Statinė ir dinaminė raumenų ištvermė fiziniuose krūviuose 50 proc. arba 75 proc. MVJ yra savarankiški fiziologiniai funkciniai mėginiai, rodantys judėjimo aparato funkcines galimybes. Svarbu žinoti skirtingo intensyvumo 50 proc. MVJ ir 75 proc. MVJ, ir rėžimo fizinių krūvių poveikį funkcinei raumenų būsenai, širdies ir kraujagyslių sistemos veiklai. Tikslas: Įvertinti ištvermės sporto šakų sportininkų, kai kurių ŠKS parametrų ir arterinės kraujotakos kaitą blauzdos raumenyse atliekant 50 proc. ir 75 proc. MVJ statinius ir dinaminius fizinius krūvius. Uždaviniai: 1. Nustatyti statinių ir dinaminių fizinių krūvių 50 proc. ir 75 proc. MVJ poveikį pėdos lenkiamųjų raumenų darbingumui. 2. Nustatyti statinių ir dinaminių fizinių krūvių 50 proc. ir 75 proc. MVJ iki visiško nuovargio poveikį arterinės kraujotakos kaitai blauzdos raumenyse. 3. Nustatyti statinių ir dinaminių fizinių krūvių 50 proc. ir 75 proc. MVJ iki visiško nuovargio poveikį AKS ir ŠSD kaitai. Hipotezė: Ištvermės sporto šakų sportininkams daugiau priimtinas funkcinis mėginys 75 proc. MVJ tiek statiniam, tiek dinaminiam fiziniam darbingumui įvertinti negu 50 proc. MVJ. Tyrimo metodai: Dinamometrija, ergometrija, veninė okliuzinė pletizmografija, arterinio kraujo spaudimo matavimas, pulsometrija... [toliau žr. visą tekstą] / Research background and hypothesis. In sport activity different intensity static and dynamic exercises are used. Static and dynamic endurance is an activity rate dependent on maximum voluntary contraction. Static and dynamic muscles endurance in sport activity 50 per cent or 75 per cent MVC are a physiological functional test, which shows locomotor functional abilities. It is important to know different intensity 50 per cent and 75 per cent MVC physical activities influence functional muscular and cardiovascular systems. Hypothesis: endurance sports athletes accept more functional test of 75 perc ent MVC both static and dynamic physical activity nor 50 per cent. Research aim. Analyze endurance athletes some of the heart vascular systems parameters and arterial blood flow changes of the intensity in the calf muscle in different intensities 50 per cent and 75 per cent MVC static and dynamic exercises. Objectives of the study. 1. Identifying static and dynamic physical loads 50 and 75 per cent. MVC influence of foot flexion muscles working capacity. 2. Identifying static and dynamic physical loads 50 and 75 per cent. MVC until exhaustion, arterial blood flow changes of the calf muscles. 3. Identifying static and dynamic physical loads 50 and 75 per cent MVC until exhaustion blood preassure and heart rate changes. Research methods. Dynamometry, ergometry, venous occlusive plethysmography, arterial blood preassure measurement, pulsometry, statistical analysis. Research... [to full text]

Tikslas: Išanalizuoti griaučių raumenų arterinės kraujotakos ir fizinio darbingumo kaita atliekant 120 mm Hg slėgio okliuzines treniruotes Uždaviniai: 1. Nustatyti arterinio kraujo spaudimo ir blauzdos raumenų arterinės kraujotakos intensyvumą ramybės būsenoje be okliuzijos ir su 120 mm Hg okliuzija. 2. Nustatyti arterinio kraujo spaudimo ir blauzdos raumenų darbingumo kaitą be okliuzijos ir su 120 mm Hg slėgio okliuzija. 3. Nustatyti arterinio kraujo spaudimo ir blauzdos raumenų arterinės kraujotakos ir darbingumo kaitą atliekant treniruotes, be okliuzijos ir su 120 mm Hg okliuzija. Tyrimo metodai: Dinamometrija, ergometrija, veninė okliuzinė pletizmografija, pulsometrija, arterinio kraujo spaudimo (AKS) matavimai. Tyrimų organizavimas: Pirmo etapo tyrimo, kontrolinėje grupėje – registruojama kraujotaka ir AKS ramybėje ir 15 min be okliuzijos, o eksperimentinėje – su 15 min okliuzija. Antro etapo tyrimo kontrolinėje grupėje registruojama arterinė kraujotaka ir AKS ramybėje ir po 75 % MVJ fizinio darbo kilnojant svarmenį iki visiško nuovargio. Eksperimentinėje grupėje tarp dviejų fizinių krūvių atliekama 15 min okliuzija. Trečio etapo tyrimo kontrolinėje grupėje registruojama arterinė kraujotaka, AKS, ŠSD, bei atliko vienos savaitės treniruočių ciklą. Analogiškai tyrimas buvo atliktas ir eksperimentinėje grupėje, tik buvo atliekama okliuzija. Rezultatai. Pirmo etapo tyrimo eksperimentinės grupės okliuzja 120 mm Hg mažina arterinę kraujotaką. Antro etapo kontrolinėje grupėje... [toliau žr. visą tekstą] / Objective: To analyze the skeletal muscle of arterial blood flow and changes in physical working capacity 120 mm Hg pressure occlusive workouts Goals: 1. Set of arterial blood pressure and arterial calf muscle blood flow at rest without occlusion and 120 mm Hg occlusion. Second Set of arterial blood pressure and calf muscle work change without occlusion and 120 mm Hg pressure occlusion. 3rd Set of arterial blood pressure and calf muscle blood flow and arterial capacity change during workouts without occlusion and 120 mm Hg occlusion. The research methods: Dynamometry, ergometry, venous occlusive plesthysmography, heart rate, arterial blood pressure (BP) measurements. Research Organization: The first phase of the study, the control group - keeping the blood flow and blood pressure at rest and 15 min without occlusion, and experimental - to 15-minute occlusion. The second phase of the study in the control group recorded arterial blood flow and blood pressure at rest and 75% MVC physical work lifting a weight up to full weariness. In the experimental group between two physical workloads performed 15 min occlusion. The third phase of the study in the control group recorded arterial blood flow, blood pressure, heart rate, and performed a one-week training cycle. Similarly, the study was conducted, and the experimental group, but occlusion was performed. Results. The first phase of the study the experimental group okliuzja 120 mm Hg reduces arterial blood flow. The second phase of... [to full text]

This study combines noninvasive hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] with occlusive calibration for continuous measurement of absolute blood flow (BF), tissue blood oxygenation (StO2), and oxygen consumption rate (VO2) in exercising skeletal muscle. Subjects performed rhythmic dynamic handgrip exercise, while an optical probe connected to a hybrid NIRS/DCS flow-oximeter directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and [tHb]), StO2, relative BF (rBF), and relative VO2 (rVO2) in the forearm flexor muscles. Absolute baseline BF and VO2 were obtained through venous and arterial occlusions, respectively, and used to calibrate continuous relative parameters. Previously known problems with muscle fiber motion artifact in optical measurements were mitigated with a novel dynamometer-based gating algorithm. Nine healthy young subjects were measured and results validated against previous literature findings. Ten older subjects with fibromyalgia and thirteen age-matched healthy controls were then successfully measured to observe differences in hemodynamic and metabolic response to exercise. This study demonstrates a novel application of NIRS/DCS technology to simultaneously evaluate quantitative hemodynamic and metabolic parameters in exercising skeletal muscle. This method has broad application to research and clinical assessment of disease (e.g. peripheral vascular disease, fibromyalgia), treatment evaluation, and sports medicine.

This research investigates various applications of diffuse correlation spectroscopy (DCS) on in-vivo human muscle tissue, both at rest and during dynamic exercise. Previously suspected muscle tissue relative blood flow (rBF) baseline shift during extended measurement with DCS and DCS-Near infrared spectroscopy (NIRS) hybrid optical systems are verified, quantified, and resolved by redesign of optical probe and alteration in optical probe attachment methodology during 40 minute supine bed rest baseline measurements. We then translate previously developed occlusion techniques, whereby rBF and relative oxygen consumption rV̇O2 are calibrated to initial resting absolute values by use of a venous occlusion (VO) and arterial occlusion (AO) protocol, respectively, to the lower leg (gastrocnemius) and these blood flows are cross validated at rest by strain gauge venous plethysmography (SGVP). Methods used to continuously observe 0.5Hz, 30% maximum voluntary isometric contraction (MVIC) plantar flexion exercise via dynamometer are adapted for our hybrid DCS-Imagent diffuse optical flow-oximeter in the medial gastrocnemius. We obtain healthy control muscle tissue hemodynamic profiles for key parameters BF, V̇O2, oxygen saturation (StO2), deoxyhemoglobin, oxyhemoglobin, and total hemoglobin concentrations ([Hb], [HbO2], and THC respectively), as well as systemic mean arterial pressure (MAP) and pulse rate (PR), at rest, during VO/AO, during dynamic exercise and during 15 minute recovery periods. Next, we began investigation of muscle tissue hemodynamic disease states by performing a feasibility pilot study using limited numbers of controls and peripheral arterial disease (PAD) patients using the translated methods/techniques to determine the ability of our technology to assess differences in these populations.

The overall aim of this thesis was to combine optical methods into a system with the ability to simultaneously measure blood flow changes at different tissue depths. The goal of such a system was to reveal vascular mechanisms relevant to pressure ulcer etiology under clinically relevant conditions and in relation to the evaluation of pressure-redistribution support surfaces. This thesis consists of four quantitative, cross-sectional studies measuring blood flow responses before, during, and after pressure exposure of the sacral tissue. Two optical methods – photoplethysmography and laser Doppler flowmetry – were combined in a newly developed system that has the ability to discriminate blood flows at different tissue depths. Studies I and II explored blood flow responses at different depths in 17 individuals. In Study I the blood flow was related to tissue thickness and tissue compression during pressure exposure of ≥ 220 mmHg. In Study II, the sacral tissue was loaded with 37.5 mmHg and 50.0 mmHg, and the variation in blood flow was measured. Studies III and IV included 42 healthy individuals < 65 years, 38 healthy individuals ≥ 65 years, and 35 patients ≥ 65 years. Study III included between-subject comparisons of blood flow and pressure between individuals in the three study groups lying in supine positions on a standard hospital mattress. Study IV added within-subject comparisons while the individual was lying on four different types of mattress. The studies explored the vascular phenomena pressure-induced vasodilation (PIV) and reactive hyperemia (RH). The most common blood flow response to tissue exposure in this thesis was PIV, although a decrease in blood flow (a lack of PIV) was observed in some individuals. The patients tended to have higher interface pressure during pressure exposure than the healthy groups but no differences in blood flow responses were seen. Our results showed that pressure levels that are normally considered to be harmless could have a significant effect on the microcirculation in different tissue structures. Differences in individual blood flow responses in terms of PIV and RH were seen, and a larger proportion of individuals lacked these responses in the deeper tissue structures compared to more superficial tissue structures. This thesis identified PIV and RH that are important vascular mechanisms for pressure ulcer development and revealed for the first time that PIV and RH are present at different depths under clinically relevant conditions. The thesis also identified a population of individuals not previously identified who lack both PIV and RH and seem to be particularly vulnerable to pressure exposure. Further, this thesis has added a new perspective to the microcirculation in pressure ulcer etiology in terms of blood flow regulation and endothelial function that are anchored in clinically relevant studies. Finally, the evaluation of pressureredistribution support surfaces in terms of mean blood flow during and after tissue exposure was shown to be unfeasible, but the assessment of PIV and RH could provide a new possibility for measuring individual physiological responses that are known to be related to pressure ulcer development.

Since the analysis of dynamics of intervals of short cardiovascular signals reflects important vital processes, involving complex interactions of the regulatory processes (Batzel, Bachar, 2010), mathematical formalism is one of the ways to research the complexity of biological systems (Davis et al., 2010). Concerning the interaction of various physiological systems / parameters that point out the causes of fatigue, the theory of non-linear dynamical systems enables to reveal this phenomenon as a part of dynamic system’s processes. Cardiovascular functional values are integral indicators, i.e. the values of the recorded parameters are affected by numerous factors or at least some of them. The question to which we tried to find the answer performing the following analysis of the data could be worded as follows. Apparently, the evaluation of the dynamic concatenation among these cardiovascular parameters, when the functional state of the subject changes, can reveal an increase or decrease in the significance of the selected structural component during the developing and incremental fatigue. The aim of the study was to find out the peculiarities in concatenation between central and peripheral cardiovascular indices under the conditions of increasing fatigue. Objectives: 1. To compare the peculiarities of dynamics in cardiovascular functional and functional state indices while performing increamental exercise up to inability by applying the provocative or increasing workload... [to full text] / Nauji tyrimų rezultatų analizės metodai, nauja tyrimų metodologija išplečia fiziologų galimybes pažinti naujas, ligi šiol neatskleistas organizmo funkcijų ypatybes, panaudoti jas funkcinei būklei vertinti, valdant fizinio ir kitokio poveikio trukmę, stiprumą, ieškant optimalaus poveikio ir adaptacijos efekto. Kompleksiškumo ypatybėms vertinti Lietuvos mokslininkai pasiūlė dinaminių sąsajų vertinimo metodiką, taikant algebrinį duomenų kointegracijos metodą (Navickas ir kt., 2005; Navickas, Bikulčienė, 2008; Vainoras et al., 2008; Bikulčienė et al., 2009; Poderys et al., 2010). Darbo tikslas – nustatyti aktyvių raumenų kraujotakos ir kitų ŠKS funkcinių rodiklių dinaminių sąsajų ypatybes atliekant didėjantį fizinį krūvį iki negalėjimo. Uždaviniai: 1. Palyginti ŠKS funkcinių ir funkcinės būklės rodiklių kaitos ypatybes atliekant pakopomis didėjantį fizinį krūvį iki negalėjimo, taikant provokacinio ir darbinio fizinio krūvio didinimo protokolus. 2. Nustatyti reikšmingų širdies ir kraujagyslių sistemos funkcinių rodiklių dinaminių sąsajų ypatybes veloergometru atliekant pakopomis didėjantį fizinį krūvį iki negalėjimo. 3. Nustatyti adaptacijos greitumo, arba ištvermės fiziniams krūviams, įtaką širdies ir kraujagyslių sistemos funkcinių rodiklių dinaminių sąsajų kaitai atliekant pakopomis didėjantį fizinį krūvį iki negalėjimo. 4. Nustatyti, ar galima algebriniu duomenų kointegracijos metodu gauti fiziologijai reikšmingą informaciją, vertinant dinamines sąsajas tarp rodiklių, kai... [toliau žr. visą tekstą]

Microvascular lesions of the brain are observed in numerous pathological conditions including Alzheimer's disease (AD). Regional patterns of microvascular abnormality can be characterized using current neuroimaging technologies. When applied to mouse models of human disease, these technologies reveal cerebral vascular patterns and help uncover genotype-to-phenotype relationships. This thesis focuses on the development and testing of techniques for measuring two perfusion-related metrics in mouse brain regions, namely, cerebral blood volume (CBV) and cerebral blood flow (CBF) using micro-computed tomography (micro-CT) and arterial spin labeling (ASL), respectively. The main developments for measurement of CBV have included: refinements to micro-CT specimen preparation; registration of micro-CT images to an MRI anatomical brain atlas; and masking of major vessels to calculate small-vessel CBV (sv-CBV). The development of this micro-CT technique provided reference values of CBV over neuroanatomical brain regions in wildtype mice. A separate study was conducted to assess regional sv-CBV in a mouse model of AD; this study was motivated by the prevalence of microvascular lesions in patients who suffer from AD. Significant regional differences in sv-CBV were found between AD-afflicted mice and controls. The main developments for measurement of CBF have included: design and implementation of accurate ASL slice positioning and optimization of inversion efficiency parameters. The development of this ASL technique provided reference values of CBF over neuroanatomical brain regions in wildtype mice. These techniques for measuring CBV and CBF over mouse brain regions could lead to improved characterization of vascularity in models of neurological diseases.

Microvascular lesions of the brain are observed in numerous pathological conditions including Alzheimer's disease (AD). Regional patterns of microvascular abnormality can be characterized using current neuroimaging technologies. When applied to mouse models of human disease, these technologies reveal cerebral vascular patterns and help uncover genotype-to-phenotype relationships. This thesis focuses on the development and testing of techniques for measuring two perfusion-related metrics in mouse brain regions, namely, cerebral blood volume (CBV) and cerebral blood flow (CBF) using micro-computed tomography (micro-CT) and arterial spin labeling (ASL), respectively. The main developments for measurement of CBV have included: refinements to micro-CT specimen preparation; registration of micro-CT images to an MRI anatomical brain atlas; and masking of major vessels to calculate small-vessel CBV (sv-CBV). The development of this micro-CT technique provided reference values of CBV over neuroanatomical brain regions in wildtype mice. A separate study was conducted to assess regional sv-CBV in a mouse model of AD; this study was motivated by the prevalence of microvascular lesions in patients who suffer from AD. Significant regional differences in sv-CBV were found between AD-afflicted mice and controls. The main developments for measurement of CBF have included: design and implementation of accurate ASL slice positioning and optimization of inversion efficiency parameters. The development of this ASL technique provided reference values of CBF over neuroanatomical brain regions in wildtype mice. These techniques for measuring CBV and CBF over mouse brain regions could lead to improved characterization of vascularity in models of neurological diseases.

En simulant l’écoulement du sang dans un réseau de capillaires (en l’absence de contrôle biologique), il est possible d’observer la présence d’oscillations de certains paramètres comme le débit volumique, la pression et l’hématocrite (volume des globules rouges par rapport au volume du sang total). Ce comportement semble être en concordance avec certaines expériences in vivo. Malgré cet accord, il faut se demander si les fluctuations observées lors des simulations de l’écoulement sont physiques, numériques ou un artefact de modèles irréalistes puisqu’il existe toujours des différences entre des modélisations et des expériences in vivo. Pour répondre à cette question de façon satisfaisante, nous étudierons et analyserons l’écoulement du sang ainsi que la nature des oscillations observées dans quelques réseaux de capillaires utilisant un modèle convectif et un modèle moyenné pour décrire les équations de conservation de masse des globules rouges. Ces modèles tiennent compte de deux effets rhéologiques importants : l’effet Fåhraeus-Lindqvist décrivant la viscosité apparente dans un vaisseau et l’effet de séparation de phase schématisant la distribution des globules rouges aux points de bifurcation. Pour décrire ce dernier effet, deux lois de séparation de phase (les lois de Pries et al. et de Fenton et al.) seront étudiées et comparées. Dans ce mémoire, nous présenterons une description du problème physiologique (rhéologie du sang). Nous montrerons les modèles mathématiques employés (moyenné et convectif) ainsi que les lois de séparation de phase (Pries et al. et Fenton et al.) accompagnés d’une analyse des schémas numériques implémentés. Pour le modèle moyenné, nous employons le schéma numérique explicite traditionnel d’Euler ainsi qu’un nouveau schéma implicite qui permet de résoudre ce problème d’une manière efficace. Ceci est fait en utilisant une méthode de Newton- Krylov avec gradient conjugué préconditionné et la méthode de GMRES pour les itérations intérieures ainsi qu’une méthode quasi-Newton (la méthode de Broyden). Cette méthode inclura le schéma implicite d’Euler et la méthode des trapèzes. Pour le schéma convectif, la méthode explicite de Kiani et al. sera implémentée ainsi qu’une nouvelle approche implicite. La stabilité des deux modèles sera également explorée. À l’aide de trois différentes topologies, nous comparerons les résultats de ces deux modèles mathématiques ainsi que les lois de séparation de phase afin de déterminer dans quelle mesure les oscillations observées peuvent être attribuables au choix des modèles mathématiques ou au choix des méthodes numériques. / While simulating blood flow in a microvascular network (in the absence of biological control), it is possible to observe the presence of oscillations in certain parameters such as blood flow, nodal pressure and hematocrit (red blood cell concentration in blood). This behaviour seems consistent with certain in vivo experiments. Despite this agreement, one has to wonder if the fluctuations observed in simulations are physical in nature, numerical or an artefact of unrealistic models since there are always differences between modelling and in vivo experiments. To settle this question satisfactorily, we will study and analyze blood flow and the nature of the fluctuations in different microvascular networks using a convective model and a well-mixed model to depict the governing equations for conservation of red blood cell mass. These models take into account two important rheological effects : the Fåhraeus-Lindqvist effect describing the apparent viscosity of blood flow in a vessel and the plasma skimming effect which describes the separation of red blood cells at diverging nodes. To describe the latter effect, we will implement two plasma skimming models (Pries et al. and Fenton et al.). In this thesis, we will present a description of the physiological problem (blood rheology). We will introduce the mathematical models used (well-mixed and convective) as well as the plasma skimming models (Pries et al. and Fenton et al.) accompanied by a detailed analysis of the numerical methods implemented. For the well-mixed model, we use the traditional explicit Euler method as well as a new implicit scheme that allows us to solve the problem in an efficient manner. This is done using a Newton-Krylov method with a preconditioned conjugate gradient and GMRES method for the inner iterations as well as a quasi- Newton method (Broyden’s method). The implicit method will include the vi backward Euler and trapezoidal methods. For the convective model, the explicit method of Kiani et al. will be implemented as well as a new numerical implicit approach. The stability of these numerical schemes will be explored. Using three different topologies, we will compare the results of the two mathematical models as well as the two plasma skimming models and the various numerical methods in order to ascertain to what extent the oscillations that have been observed using the traditional schemes may be attributable to the choice of the mathematical models or the choice of the numerical methods.

Arteries respond to changes in global mechanical parameters (pressure, flow rate, and longitudinal stretching) by remodeling to restore local parameters (circumferential stress, shear stress, and axial strain) to baseline levels. Because a change in a single global parameter results in changes of multiple local parameters, the effects of individual local parameters on remodeling remain unknown. This study uses a novel approach to study remodeling in organ culture based on independent control of local mechanical parameters. The approach is illustrated by studying the effects of circumferential and shear stress on remodeling-related biological markers. Porcine carotid arteries were cultured for three days at a circumferential stress of 50 kPa or 150 kPa or, in separate experiments, a shear stress of 0.75 Pa or 2.25 Pa. At high circumferential stress, matrix synthesis, smooth muscle cell proliferation, and cell death are significantly greater, but matrix metalloproteinase-2 (MMP-2) and pro-MMP-2 activity are significantly less. In contrast, biological markers measured were unaffected by shear stress. Applications of the proposed approach for improved understanding of remodeling, optimizing mechanical conditioning of tissue engineered arteries, and selection of experimentally motivated growth laws are discussed.