The mean and variance of phylogenetic diversity under rarefaction.

PubMed

Nipperess, David A; Matsen, Frederick A

2013-06-01

Phylogenetic diversity (PD) depends on sampling depth, which complicates the comparison of PD between samples of different depth. One approach to dealing with differing sample depth for a given diversity statistic is to rarefy, which means to take a random subset of a given size of the original sample. Exact analytical formulae for the mean and variance of species richness under rarefaction have existed for some time but no such solution exists for PD.We have derived exact formulae for the mean and variance of PD under rarefaction. We confirm that these formulae are correct by comparing exact solution mean and variance to that calculated by repeated random (Monte Carlo) subsampling of a dataset of stem counts of woody shrubs of Toohey Forest, Queensland, Australia. We also demonstrate the application of the method using two examples: identifying hotspots of mammalian diversity in Australasian ecoregions, and characterising the human vaginal microbiome.There is a very high degree of correspondence between the analytical and random subsampling methods for calculating mean and variance of PD under rarefaction, although the Monte Carlo method requires a large number of random draws to converge on the exact solution for the variance.Rarefaction of mammalian PD of ecoregions in Australasia to a common standard of 25 species reveals very different rank orderings of ecoregions, indicating quite different hotspots of diversity than those obtained for unrarefied PD. The application of these methods to the vaginal microbiome shows that a classical score used to quantify bacterial vaginosis is correlated with the shape of the rarefaction curve.The analytical formulae for the mean and variance of PD under rarefaction are both exact and more efficient than repeated subsampling. Rarefaction of PD allows for many applications where comparisons of samples of different depth is required.

A Mass Tracking Formulation for Bubbles in Incompressible Flow

DTIC Science & Technology

2012-10-14

incompressible flow to fully nonlinear compressible flow including the effects of shocks and rarefactions , and then subsequently making a number of...using the ideas from [19] to couple together incompressible flow with fully nonlinear compressible flow including shocks and rarefactions . The results...compressible flow including the effects of shocks and rarefactions , and then subsequently making a number of simplifying assumptions on the air flow

Microvascular remodelling in preeclampsia: quantifying capillary rarefaction accurately and independently predicts preeclampsia.

PubMed

Antonios, Tarek F T; Nama, Vivek; Wang, Duolao; Manyonda, Isaac T

2013-09-01

Preeclampsia is a major cause of maternal and neonatal mortality and morbidity. The incidence of preeclampsia seems to be rising because of increased prevalence of predisposing disorders, such as essential hypertension, diabetes, and obesity, and there is increasing evidence to suggest widespread microcirculatory abnormalities before the onset of preeclampsia. We hypothesized that quantifying capillary rarefaction could be helpful in the clinical prediction of preeclampsia. We measured skin capillary density according to a well-validated protocol at 5 consecutive predetermined visits in 322 consecutive white women, of whom 16 subjects developed preeclampsia. We found that structural capillary rarefaction at 20-24 weeks of gestation yielded a sensitivity of 0.87 with a specificity of 0.50 at the cutoff of 2 capillaries/field with the area under the curve of the receiver operating characteristic value of 0.70, whereas capillary rarefaction at 27-32 weeks of gestation yielded a sensitivity of 0.75 and a higher specificity of 0.77 at the cutoff of 8 capillaries/field with area under the curve of the receiver operating characteristic value of 0.82. Combining capillary rarefaction with uterine artery Doppler pulsatility index increased the sensitivity and specificity of the prediction. Multivariable analysis shows that the odds of preeclampsia are increased in women with previous history of preeclampsia or chronic hypertension and in those with increased uterine artery Doppler pulsatility index, but the most powerful and independent predictor of preeclampsia was capillary rarefaction at 27-32 weeks. Quantifying structural rarefaction of skin capillaries in pregnancy is a potentially useful clinical marker for the prediction of preeclampsia.

[Microcirculation in patients with paranoid schizophrenia].

PubMed

Sakharov, A V; Ozornin, A S; Golygina, S E; Vinogradova, A O; Shvets, M S

2018-01-01

To study microcirculation in patients with paranoid schizophrenia by laser Doppler flowmetry. Fifty-three patients at the age from 18 to 38 years with a diagnosis of 'paranoid schizophrenia' (F20.0) were examined in the acute psychotic state and after 3 weeks of therapy. The control group consisted of 20 healthy volunteers. To assess microcirculation, the noninvasive technique of laser Doppler flowmetry using a laser blood flow analyzer was used. Significant changes in the microcirculation persisting even over three weeks of therapy in patients were identified. The total microcirculation index was increased by 1.4 times which indicated the acceleration of blood flow. An increase in the average fluctuations of perfusion by 3.7 times and in the coefficient of variation by 1.9 times, which reflect the excessive strengthening of local mechanisms of regulation of microcirculation, were found. There were an increase in the myogenic tone and neurogenic tone of metarteriole and precapillary sphincters as well as bypass index.

Anesthesia, Microcirculation and Wound Repair in Aging

PubMed Central

Bentov, Itay; Reed, May J.

2014-01-01

Age related changes in skin contribute to impaired wound healing after surgical procedures. Changes in skin with age include decline in thickness and composition, a decrease in the number of most cell types and diminished microcirculation. The microcirculation provides tissue perfusion, fluid homeostasis, and delivery of oxygen and other nutrients. It also controls temperature and the inflammatory response. Surgical incisions cause further disruption of the microvasculature of aged skin. Perioperative management can be modified to minimize insults to aged tissues. Judicious use of fluids, maintenance of normal body temperature, pain control and increased tissue oxygen tension are examples of adjustable variables that support the microcirculation. Anesthetic agents influence the microcirculation from a combination of effects on cardiac output, arterial pressure and local micro-vascular changes. We examine the role of anesthetic management in optimizing the microcirculation and potentially improving post-operative wound repair in older persons. PMID:24195972

Blast waves from violent explosive activity at Yasur Volcano, Vanuatu

NASA Astrophysics Data System (ADS)

Marchetti, E.; Ripepe, M.; Delle Donne, D.; Genco, R.; Finizola, A.; Garaebiti, E.

2013-11-01

and seismic waveforms were collected during violent strombolian activity at Yasur Volcano (Vanuatu). Averaging ~3000 seismic events showed stable waveforms, evidencing a low-frequency (0.1-0.3 Hz) signal preceding ~5-6 s the explosion. Infrasonic waveforms were mostly asymmetric with a sharp compressive (5-106 Pa) onset, followed by a small long-lasting rarefaction phase. Regardless of the pressure amplitude, the ratio between the positive and negative phases was constant. These waveform characteristics closely resembled blast waves. Infrared imagery showed an apparent cold spherical front ~20 m thick, which moved between 342 and 405 m/s before the explosive hot gas/fragments cloud. We interpret this cold front as that produced by the vapor condensation induced by the passage of the shock front. We suggest that violent strombolian activity at Yasur was driven by supersonic dynamics with gas expanding at 1.1 Mach number inside the conduit.

Low Intensity Laser Therapy (LILT) Versus Transcutaneous Electrical Nerve Stimulation On Microcirculation In Diabetic Neuropathy

NASA Astrophysics Data System (ADS)

Battecha, Kadria H.; Atya, Azza M.

2011-09-01

Reduced microcirculation is a morbid element of neuropathy and one of the most common complications of uncontrolled diabetes. Many physical modalities have gained a considerable attention for enhancing cutaneous microcirculation in diabetic patients and prevent its serious complications. Accordingly, the present study was conducted to compare between the effect of low intensity laser therapy (LILT) and transcutaneous electrical nerve stimulation (TENS) on microcirculation in diabetic neuropathy. Thirty diabetic polyneuropathic patients ranged in age from 45-60 years participated in this study. They were randomly divided into two groups of equal number; patients in group (A) received LILT on plantar surface of foot with a dose of 3 J/cm2 and wavelength (904 nm), while those in group (B) received TENS on lower leg for 30 minutes with frequency (2 HZ). Treatment was conducted 3 times/week for 6 weeks. The cutaneous microcirculation was evaluated by Laser Doppler flowmetry at the baseline and at the end of treatment. Results revealed that group (A) showed statistically significant increase in the cutaneous microcirculation compared with group (B). So, it was concluded that LILT has to be more efficient than TENS in increasing cutaneous microcirculation in patients with diabetic neuropathy.

An encapsulated fruit and vegetable juice concentrate increases skin microcirculation in healthy women.

PubMed

De Spirt, S; Sies, H; Tronnier, H; Heinrich, U

2012-01-01

Microcirculation in the dermis of the skin is important for nutrient delivery to this tissue. In this study, the effects of a micronutrient concentrate (Juice Plus+®; 'active group'), composed primarily of fruit and vegetable juice powder, on skin microcirculation and structure were compared to placebo. This 12-week study had a monocentric, double-blind placebo and randomized controlled design with two treatment groups consisting of 26 healthy middle-aged women each. The 'oxygen to see' device was used to evaluate microcirculation. Skin density and thickness were measured using ultrasound. Measurements for skin hydration (Corneometer®), transepidermal water loss and serum analysis for carotenoids and α-tocopherol were also performed. By 12 weeks, microcirculation of the superficial plexus increased by 39%. Furthermore, skin hydration increased by 9% while skin thickness increased by 6% and skin density by 16% in the active group. In the placebo group, microcirculation decreased, and a slight increase in skin density was observed. Ingestion of a fruit- and vegetable-based concentrate increases microcirculation of the skin at 12 weeks of intervention and positively affects skin hydration, density and thickness. Copyright © 2011 S. Karger AG, Basel.

Algorithmic Foundation of Spectral Rarefaction for Measuring Satellite Imagery Heterogeneity at Multiple Spatial Scales

PubMed Central

Rocchini, Duccio

2009-01-01

Measuring heterogeneity in satellite imagery is an important task to deal with. Most measures of spectral diversity have been based on Shannon Information theory. However, this approach does not inherently address different scales, ranging from local (hereafter referred to alpha diversity) to global scales (gamma diversity). The aim of this paper is to propose a method for measuring spectral heterogeneity at multiple scales based on rarefaction curves. An algorithmic solution of rarefaction applied to image pixel values (Digital Numbers, DNs) is provided and discussed. PMID:22389600

Rarefaction waves, solitons, and holes in a pure electron plasma

NASA Astrophysics Data System (ADS)

Moody, J. D.; Driscoll, C. F.

1995-12-01

The propagation of holes, solitons, and rarefaction waves along the axis of a magnetized pure electron plasma column is described. The time dependence of the radially averaged density perturbation produced by the nonlinear waves is measured at several locations along the plasma column for a wide range of plasma parameters. The rarefaction waves are studied by measuring the free expansion of the plasma into a vacuum. A new hydrodynamic theory is described that quantitatively predicts the free expansion measurements. The rarefaction is initially characterized by a self-similar plasma flow, resulting in a perturbed density and velocity without a characteristic length scale. The electron solitons show a small increase in propagation speed with increasing amplitude and exhibit electron bursts. The holes show a decrease in propagation speed with increasing amplitude. Collisions between holes and solitons show that these objects pass through each other undisturbed, except for a small offset.

Stability of Planar Rarefaction Wave to 3D Full Compressible Navier-Stokes Equations

NASA Astrophysics Data System (ADS)

Li, Lin-an; Wang, Teng; Wang, Yi

2018-05-01

We prove time-asymptotic stability toward the planar rarefaction wave for the three-dimensional full, compressible Navier-Stokes equations with the heat-conductivities in an infinite long flat nozzle domain {R × T^2} . Compared with one-dimensional case, the proof here is based on our new observations on the cancellations on the flux terms and viscous terms due to the underlying wave structures, which are crucial for overcoming the difficulties due to the wave propagation in the transverse directions x 2 and x 3 and its interactions with the planar rarefaction wave in x 1 direction.

Digital capillaroscopy as important tool for early diagnostics of arterial hypertension

NASA Astrophysics Data System (ADS)

Gurfinkel, Yu. I.; Sasonko, M. L.; Priezzhev, A. V.

2015-03-01

The study is aimed to determine the digital capillaroscopy possibilities in early diagnostics of an arterial hypertension. A total of 123 adult persons were examined in the study. The first group consisted of 40 patients with prehypertension (BP 130-139/85-89 mm Hg). The second group included 36 patients with 1-2 stage of hypertension (mean systolic BP 152.7±12 mm Hg). Patients in both groups did not receive regular drug therapy. The group of volunteers (n=47) included healthy adults without signs of cardiovascular pathology. The capillary circulation was examined on the nailbed using the optical digital capillaroscope developed by the company "AET", Russia. Diameters of the arterial and venous segments, perivascular zone size, capillary blood velocity, the degree of arterial loops narrowing and the density of the capillary network were estimated. In patients with arterial hypertension and even in patients with prehypertension remodeling and rarefaction of capillaries and the expressed narrowing their arterial loops were manifested. The results of the study revealed the presence of abnormalities of microcirculation parameters in patients of both groups. The capillaries density in both groups of patients was significantly lower than in healthy persons. The significant narrowing of arterial loops was revealed in patients with both arterial hypertension and prehypertension, in comparison with healthy volunteers. Capillary blood velocity did not differ significantly between healthy volunteers group and the group of prehypertensive patients. However in patients with hypertension this parameter was significantly lower in comparison with control group.

Monitoring microcirculation.

PubMed

Ocak, Işık; Kara, Atila; Ince, Can

2016-12-01

The clinical relevance of microcirculation and its bedside observation started gaining importance in the 1990s since the introduction of hand-held video microscopes. From then, this technology has been continuously developed, and its clinical relevance has been established in more than 400 studies. In this paper, we review the different types of video microscopes, their application techniques, the microcirculation of different organ systems, the analysis methods, and the software and scoring systems. The main focus of this review will be on the state-of-art technique, CytoCam-incident dark-field imaging, and the most recent technological and technical updates concerning microcirculation monitoring. Copyright © 2016 Elsevier Ltd. All rights reserved.

Correlation mapping: rapid method for retrieving microcirculation morphology from optical coherence tomography intensity images

NASA Astrophysics Data System (ADS)

Jonathan, E.; Enfield, J.; Leahy, M. J.

2011-03-01

The microcirculation plays a critical role is maintaining organ health and function by serving as a vascular are where trophic metabolism exchanges between blood and tissue takes place. To facilitate regular assessment in vivo, noninvasive microcirculation imagers are required in clinics. Among this group of clinical devices, are those that render microcirculation morphology such as nailfold capillaroscopy, a common device for early diagnosis and monitoring of microangiopathies. However, depth ambiguity disqualify this and other similar techniques in medical tomography where due to the 3-D nature of biological organs, imagers that support depth-resolved 2-D imaging and 3-D image reconstruction are required. Here, we introduce correlation map OCT (cmOCT), a promising technique for microcirculation morphology imaging that combines standard optical coherence tomography and an agile imaging analysis software based on correlation statistic. Promising results are presented of the microcirculation morphology images of the brain region of a small animal model as well as measurements of vessel geometry at bifurcations, such as vessel diameters, branch angles. These data will be useful for obtaining cardiovascular related characteristics such as volumetric flow, velocity profile and vessel-wall shear stress for circulatory and respiratory system.

Restoration of Delta Streams: A Case History and Conceptual Model

DTIC Science & Technology

2008-02-01

Hydrobiologia 303:211-9. Raup, D. M. 1975. Taxonomic diversity estimation using rarefaction. Paleobiology 1: 333-342. Schlosser, I. J. 1995. Critical...Rarefaction and rarefiction — The use and abuse of a method in paleoecology. Paleobiology 5: 423-434. U.S. Environmental Protection Agency (USEPA). 1986

Effect of hypokinesia on blood microcirculation

NASA Technical Reports Server (NTRS)

Chernukh, A. M.; Gazenko, O. G.; Fedorov, B. M.; Krupina, T. N.; Aleksandrov, P. N.; Shagal, D. I.; Ranferova, N. Y.; Proskurina, T. N.

1980-01-01

Blood microcirculation in the region of the scleral bulbar conjunctiva and the nail folds on the fingers and toes was studied in 18 practically healthy men during 182 day antiorthostatic hypokinesia and 30 day rehabilitation period. Marked changes in microcirculation in the sclera and feet and less evident changes on the hands was revealed. A complex of special prophylactic physical exercises had a distinctly favorable effect on circulation in the hands.

Association of locally produced IL10 and TGFb1 with tumor size, histological type and presence of metastases in patients with lung carcinoma.

PubMed

Karlicic, Vukoica; Vukovic, Jelena; Stanojevic, Ivan; Sotirovic, Jelena; Peric, Aleksandar; Jovic, Milena; Cvijanovic, Vlado; Djukic, Mirjana; Banovic, Tatjana; Vojvodic, Danilo

2016-01-01

Advanced lung carcinoma is charasterized with fast disease progression. Interleukin (IL)10 and transforming growth factor (TGF)b1 are immunosuppressive mediators and their role in lung carcinoma pathogenesis and in the antitumor response has not yet been elucidated. The purpose of this study was to correlate IL10 and TGFb1 levels in the serum and lung tumor microcirculation with clinical stage, disease extent, histological features and TNM stage. The study included 41 lung cancer patients in clinical stage III and IV. Histological type was determined immunohistochemically, while tumor size, localization and dissemination were determined radiologically by multislice computerized tomography (MSCT). IL10 and TGFb1 levels were quantified with commercial flow cytometric test in serum and lung tumor microcirculation samples. Non small cell lung cancer (NSCLC) patients had significantly elevated TGFb1 while small cell lung cancer (SCLC) patients had significantly increased IL10 in tumor microcirculation. IL10 was significantly elevated in patients with the largest tumors, as well as in patients with III clinical stage and without metastases, both in the serum and tumor microcirculation. TGFb1 was significantly increased in serum and tumor microcirculation in patients with larger tumors. We found significant correlation between these two immunosuppressive cytokines, IL10 and TGFb1, in tumor microcirculation but not in patient serum samples. IL10 and TGFb1 in systemic and tumor microcirculation are significantly associated with particular histological type of lung cancer, tumor size and degree of disease extent.

Cerebral Microcirculation during Experimental Normovolaemic Anemia

PubMed Central

Bellapart, Judith; Cuthbertson, Kylie; Dunster, Kimble; Diab, Sara; Platts, David G.; Raffel, O. Christopher; Gabrielian, Levon; Barnett, Adrian; Paratz, Jenifer; Boots, Rob; Fraser, John F.

2016-01-01

Anemia is accepted among critically ill patients as an alternative to elective blood transfusion. This practice has been extrapolated to head injury patients with only one study comparing the effects of mild anemia on neurological outcome. There are no studies quantifying microcirculation during anemia. Experimental studies suggest that anemia leads to cerebral hypoxia and increased rates of infarction, but the lack of clinical equipoise, when testing the cerebral effects of transfusion among critically injured patients, supports the need of experimental studies. The aim of this study was to quantify cerebral microcirculation and the potential presence of axonal damage in an experimental model exposed to normovolaemic anemia, with the intention of describing possible limitations within management practices in critically ill patients. Under non-recovered anesthesia, six Merino sheep were instrumented using an intracardiac transeptal catheter to inject coded microspheres into the left atrium to ensure systemic and non-chaotic distribution. Cytometric analyses quantified cerebral microcirculation at specific regions of the brain. Amyloid precursor protein staining was used as an indicator of axonal damage. Animals were exposed to normovolaemic anemia by blood extractions from the indwelling arterial catheter with simultaneous fluid replacement through a venous central catheter. Simultaneous data recording from cerebral tissue oxygenation, intracranial pressure, and cardiac output was monitored. A regression model was used to examine the effects of anemia on microcirculation with a mixed model to control for repeated measures. Homogeneous and normal cerebral microcirculation with no evidence of axonal damage was present in all cerebral regions, with no temporal variability, concluding that acute normovolaemic anemia does not result in short-term effects on cerebral microcirculation in the ovine brain. PMID:26869986

The Difference Between the Healing and the Nonhealing Diabetic Foot Ulcer: A Review of the Role of the Microcirculation.

PubMed

Lowry, Danielle; Saeed, Mujahid; Narendran, Parth; Tiwari, Alok

2017-09-01

Diabetic foot disease carries a high morbidity and is a leading cause of lower limb amputation. This may in part be due to the effect diabetes mellitus (DM) has on the microcirculation including in the skin. We conducted a review of studies that have examined the relationship between microcirculatory function and wound healing in patients with DM. A search of the Medline, Embase, and Web of Science databases was performed coupled with a review of references for the period 1946 to March 2015. Nineteen studies of diverse methodology and cohort selection were identified. Poor function of the microcirculation was related to poor outcome. Transcutaneous oxygen pressure (TcPO 2 ) was the most commonly used method to measure the microcirculation and thresholds for poor outcome proposed ranged from 10 mmHg to <34 mmHg. Two studies reexamined microcirculatory function following revascularization. Both found an increase in TcPO 2 , however only 1 reached statistical significance. No significant difference in the results of microcirculation tests was found between diabetic and nondiabetic patients. While it is not possible to draw firm conclusions from the evidence currently available there are clear areas that warrant research. Good microcirculation unsurprisingly appears to associate with better wound healing. The influence of DM is not clear, and neither is the degree of improvement required to achieve healing. Studies that examine a clearly defined cohort both with and without DM are urgently required. Accurate quantitative assessment of microcirculation will aid prediction of wound healing identifying those at greatest risk of amputation.

In vivo assessment of the human cerebral microcirculation and its glycocalyx: A technical report.

PubMed

Haeren, R H L; Rijkers, K; Schijns, O E M G; Dings, J; Hoogland, G; van Zandvoort, M A M J; Vink, H; van Overbeeke, J J

2018-06-01

The cerebral microcirculation and its glycocalyx, a matrix coating the luminal endothelium, are key regulators of capillary permeability and cerebral blood flow. Microvascular abnormalities are described in several neurological disorders. However, assessment of the cerebral microcirculation and glycocalyx has mainly been performed ex vivo. Here, the technical feasibility of in vivo assessment of the human cerebral microcirculation and its glycocalyx using sidestream dark field (SDF) imaging is discussed. Intraoperative assessment requires the application of a sterile drape covering the camera (slipcover). First, sublingual measurements with and without slipcover were performed in a healthy control to assess the impact of this slipcover. Subsequently, using SDF imaging, the sublingual (reference), cortical, and hippocampal microcirculation and glycocalyx were evaluated in patients who underwent resective brain surgery as treatment for drug-resistant temporal lobe epilepsy. Finally, vessel density, and the perfused boundary region (PBR), a validated gauge of glycocalyx health, were calculated using GlycoCheck © software. The addition of a slipcover affects vessel density and PBR values in a control subject. The cerebral measurements in five patients were more difficult to obtain than the sublingual ones. This was probably at least partly due to the introduction of a sterile slipcover. Results on vessel density and PBR showed similar patterns at all three measurement sites. This is the first report on in vivo assessment of the human cerebrovascular glycocalyx. Assessment of the glycocalyx is an additional application of in vivo imaging of the cerebral microcirculation using SDF technique. This method enables functional analysis of the microcirculation and glycocalyx, however the addition of a sterile slipcover affects the measurements. SDF imaging is a safe, quick, and straightforward technique to evaluate the functional cerebral microcirculation and glycocalyx. Because of their eminent role in cerebral homeostasis, this method may significantly add to research on the role of vascular pathophysiology underling various neurological disorders. Copyright © 2018 Elsevier B.V. All rights reserved.

Rarefaction Effects in Low Reynolds Number Subsonic and Transonic Aerodynamics

NASA Astrophysics Data System (ADS)

Pekardan, Cem

The quantification of rarefaction effects for low Reynolds number (Re<10,000) transonic (M=0.8) flows is essential for the aerodynamic design of vehicles moving in vacuum environments approaching slip regime. Potential future applications in these conditions include low-pressure high-speed ground transportation, high-altitude unmanned aerial vehicles, Martian aircraft and rotorcraft. For the quantification of rarefaction effects, the NACA 0012 airfoil was analyzed using the traditional Navier-Stokes equations in the low-Reynolds transonic regime. The results were compared to the deterministic solution of the ES-BGK type Boltzmann equation with the Runge-Kutta Discontinuous Galerkin Method (RKDG). Numerical simulations using these computational methods were compared to the electron beam fluorescence experiments at a Re=73 and a M=0.8, and it was observed that the numerical solution of the ES-BGK model using the RKDG method with 3rd order accuracy is computationally the most efficient. It was also shown that when the Reynolds number of the flow decreased from 10,000 to 1,000, slip effects become dominant. The flow becomes fully rarefied at Re=10. Furthermore, rarefaction effects were quantified for the NACA 0007 and the NACA 2407 at 0 and 10 degrees of angle of attack to investigate the effects of thickness, camber, and the angle of attack. It was observed that flow separation due to increase in thickness resulted in higher rarefaction effects. It was concluded that thin airfoils with very smooth shape changes minimize continuum breakdown / rarefaction effects. Rarefied gas phenomena that only appear in low pressures (such as thermal effects) can be exploited for performance enhancement of applications in slightly rarefied aerodynamics. In this study, feasibility and advantages of using thermal control to reduce drag and mitigate vortex shedding for airfoils are studied. NACA 0012 airfoil with a temperature difference applied between the upper and the lower surface is simulated in the continuum regime with a Navier-Stokes solver and compared to experimental data for verification of parameters and turbulence modelling. At lower pressures, an elevated temperature on the bottom surface of the airfoil is investigated to create lift and understand the rarefaction effects. Continuum NS results were compared to the rarefied ES-BGK solver for the rarefaction effects. It was shown that an elevated temperature enhances the lift by 25 % and reduces the drag at high angles of attack. In the second part, a temperature gradient on the upper surface is applied and it was seen that drag is reduced by 4 % and vortex shedding frequency is reduced due to gradients introduced in the flow by thermal transpiration.

Vasopressin attenuates TNF-mediated inflammation in the rat cremaster microcirculation.

PubMed

McMahon, Paul J; Proctor, Kenneth G

2009-09-01

Our previous study in a swine polytrauma model suggested that equieffective systemic pressor doses of arginine vasopressin (AVP) versus phenylephrine (PE) have differential effects on the systemic and cerebral microcirculation. The purpose of this study was to directly observe the effects of AVP versus PE on inflammatory changes evoked by tumor necrosis factor alpha (TNF) in the skeletal muscle microcirculation. Seventy-five male rats (180-250 g) were anesthetized with isoforane, intubated and mechanically ventilated with 100% oxygen. The cremaster muscle microcirculation was prepared for intravital video microscopy while being suffused with a heated hetastarch-electrolyte solution. Fluorescein isothiocyanate-labeled albumin (100 mg/kg) was administered intravenously (i.v.) before one of five protocols. In series 1 (n = 20), either AVP (0.2 U/mL) or its vehicle was added to the suffusate for 10 minutes, washed out for 30 minutes, then TNF was suffused (5 ng/mL) for 30 minutes. In series 2 (n = 16), the protocol was similar, except AVP (0.2 U/mL) or an equieffective dose of PE (0.04 mg/mL) was administered i.v. (4.5 mL/h) for 15 minutes before, during, and 45 minutes after TNF suffusion. In series 3 (n = 12), the protocol was similar to series 2, except venous hemorrhage preceded i.v. AVP or PE. In series 4 (n = 15), the protocol was similar to series 3, except an AVP antagonist (vaprisol, 1 mg/kg i.v.) or its vehicle was administered after hemorrhage. In the control series (n = 13), inflammation was evaluated either with a different suffusate (lactated Ringers instead of hetastarch solution), different antigen (histamine instead of TNF), or hemorrhage with no antigen. In series 1, the TNF-evoked increase in leukocyte infiltration (i.e., rolling), leukocyte activation (i.e., sticking), and macromolecular permeability (i.e., albumin extravasation) were attenuated with topical AVP versus vehicle (both p < 0.05), with no effect on venular blood flow (which determines sheer stress). In series 2, the TNF-evoked increase in infiltration, activation, and permeability were all attenuated, and arteriolar blood flow (which determines perfused capillary surface area and hydrostatic pressure) was reduced with i.v. AVP versus i.v. PE (all p < 0.05). In series 3, after hemorrhage to mean arterial pressure <50 mm Hg for 30 minutes, the TNF-evoked increase in infiltration and activation was attenuated, and arteriolar and venular blood flow were both reduced with i.v. AVP versus PE (all p < 0.05). In series 4, after hemorrhage, the TNF-evoked increase in leukocyte activation was potentiated with the vaprisol versus vehicle (p < 0.05) with no effect on arteriolar or venular blood flow. In series 5 (controls), suffusion with lactated Ringers' versus hetastarch solution more than doubled the TNF-evoked increase in activation (p < 0.05). (1) AVP can attenuate TNF-evoked leukocyte infiltration, activation or permeability changes in the skeletal muscle microcirculation. (2) The mechanism is probably receptor mediated and does not entirely depend on sheer stress in venules or Starling forces in capillaries. (3) The magnitude of this anti-inflammatory effect is influenced by several conditions, including volume status, the colloid or crystalloid suffusion fluid, and is possibly specific to the antigenic stimulus (TNF vs. histamine).

Hemodynamic coherence and the rationale for monitoring the microcirculation.

PubMed

Ince, Can

2015-01-01

This article presents a personal viewpoint of the shortcoming of conventional hemodynamic resuscitation procedures in achieving organ perfusion and tissue oxygenation following conditions of shock and cardiovascular compromise, and why it is important to monitor the microcirculation in such conditions. The article emphasizes that if resuscitation procedures are based on the correction of systemic variables, there must be coherence between the macrocirculation and microcirculation if systemic hemodynamic-driven resuscitation procedures are to be effective in correcting organ perfusion and oxygenation. However, in conditions of inflammation and infection, which often accompany states of shock, vascular regulation and compensatory mechanisms needed to sustain hemodynamic coherence are lost, and the regional circulation and microcirculation remain in shock. We identify four types of microcirculatory alterations underlying the loss of hemodynamic coherence: type 1, heterogeneous microcirculatory flow; type 2, reduced capillary density induced by hemodilution and anemia; type 3, microcirculatory flow reduction caused by vasoconstriction or tamponade; and type 4, tissue edema. These microcirculatory alterations can be observed at the bedside using direct visualization of the sublingual microcirculation with hand-held vital microscopes. Each of these alterations results in oxygen delivery limitation to the tissue cells despite the presence of normalized systemic hemodynamic variables. Based on these concepts, we propose how to optimize the volume of fluid to maximize the oxygen-carrying capacity of the microcirculation to transport oxygen to the tissues.

In vivo assessment of the structure of skin microcirculation by reflectance confocal-laser-scanning microscopy

NASA Astrophysics Data System (ADS)

Sugata, Keiichi; Osanai, Osamu; Kawada, Hiromitsu

2012-02-01

One of the major roles of the skin microcirculation is to supply oxygen and nutrition to the surrounding tissue. Regardless of the close relationship between the microcirculation and the surrounding tissue, there are few non-invasive methods that can evaluate both the microcirculation and its surrounding tissue at the same site. We visualized microcapillary plexus structures in human skin using in vivo reflectance confocal-laser-scanning microscopy (CLSM), Vivascope 3000® (Lucid Inc., USA) and Image J software (National Institutes of Health, USA) for video image processing. CLSM is a non-invasive technique that can visualize the internal structure of the skin at the cellular level. In addition to internal morphological information such as the extracellular matrix, our method reveals capillary structures up to the depth of the subpapillary plexus at the same site without the need for additional optical systems. Video images at specific depths of the inner forearm skin were recorded. By creating frame-to-frame difference images from the video images using off-line video image processing, we obtained images that emphasize the brightness depending on changes of intensity coming from the movement of blood cells. Merging images from different depths of the skin elucidates the 3-dimensional fine line-structure of the microcirculation. Overall our results show the feasibility of a non-invasive, high-resolution imaging technique to characterize the skin microcirculation and the surrounding tissue.

Demonstration of Dispersive Rarefaction Shocks in Hollow Elliptical Cylinder Chains

NASA Astrophysics Data System (ADS)

Kim, H.; Kim, E.; Chong, C.; Kevrekidis, P. G.; Yang, J.

2018-05-01

We report an experimental and numerical demonstration of dispersive rarefaction shocks (DRS) in a 3D-printed soft chain of hollow elliptical cylinders. We find that, in contrast to conventional nonlinear waves, these DRS have their lower amplitude components travel faster, while the higher amplitude ones propagate slower. This results in the backward-tilted shape of the front of the wave (the rarefaction segment) and the breakage of wave tails into a modulated waveform (the dispersive shock segment). Examining the DRS under various impact conditions, we find the counterintuitive feature that the higher striker velocity causes the slower propagation of the DRS. These unique features can be useful for mitigating impact controllably and efficiently without relying on material damping or plasticity effects.

Demonstration of Dispersive Rarefaction Shocks in Hollow Elliptical Cylinder Chains.

PubMed

Kim, H; Kim, E; Chong, C; Kevrekidis, P G; Yang, J

2018-05-11

We report an experimental and numerical demonstration of dispersive rarefaction shocks (DRS) in a 3D-printed soft chain of hollow elliptical cylinders. We find that, in contrast to conventional nonlinear waves, these DRS have their lower amplitude components travel faster, while the higher amplitude ones propagate slower. This results in the backward-tilted shape of the front of the wave (the rarefaction segment) and the breakage of wave tails into a modulated waveform (the dispersive shock segment). Examining the DRS under various impact conditions, we find the counterintuitive feature that the higher striker velocity causes the slower propagation of the DRS. These unique features can be useful for mitigating impact controllably and efficiently without relying on material damping or plasticity effects.

Comparative evaluation of the effects of high-intensity and low-intensity laser radiation on microcirculation among patients with knee arthritis

NASA Astrophysics Data System (ADS)

Kulchitskaya, D. B.; Konchugova, T. V.; E Fedorova, N.

2017-04-01

Sixty patients with knee arthritis aged from 40 to 75 years old were examined. The patients were randomly divided into two groups: 1st group (30 patients) received high intensity laser radiation; 2nd group (20 patients) received low intensity laser radiation. As a result of the conducted research it was found that high intensity laser radiation is more efficient and leads to more vivid positive changes in the microcirculation of patients with knee arthritis. The changes in microcirculation were based on the normalization of the myogenic and neurogenic tonus of the arterioles, strengthening oscillation of the endothelial range. As a result of local mechanisms activation of tissue blood flow there occurs adequate modulation of the microcirculatory bloodstream, which is aimed at the elimination of congestive phenomena in the capillary and venular level of the microcirculation bloodstream. We should note that in the long-term more significant were the positive changes in the state of the venular level of the microcirculation bloodstream. in constructing both.

Design of sensors for microcirculation investigation in pharyngeal mucosa

NASA Astrophysics Data System (ADS)

Mareew, Gleb O.; Mareew, Oleg V.; Fedosov, Ivan V.; Tuchin, Valery V.

2004-08-01

Sensors designed for research of blood microcirculation in pharyngeal mucosa by a laser Doppler flowmetry, are described and considered in view of anatomic and physiological features of objects of research. Two designs of sensors for laser Doppler flowmetry are described - non-contact and contact. The results of and clinical testing at norm and different pathologies of pharynx of on calibration of sensors, and also their comparative technical characteristics and materials of clinical researches of microcirculation are resulted at norm and at a various pathology.

Factors Affecting Tissue Oxygenation in Erythrocyte Transfusions

PubMed Central

Aykut, Güçlü; Yürük, Koray; İnce, Can

2014-01-01

Red blood cell transfusions are used to increase the oxygen-carrying capacity of blood in anemic states. But, because of the changes during storage of blood components and the specifics of preparation, erythrocytes may have controversial effects on tissue oxygenation and microcirculation. Also, the patient situation may play a role in the differing responses in oxygenation and microcirculation. In this review, the studies concerning the effects of banked blood and patient characteristics on microcirculation and tissue oxygenation are summarized. PMID:27366403

Mesenchymal stem cell-derived microparticles ameliorate peritubular capillary rarefaction via inhibition of endothelial-mesenchymal transition and decrease tubulointerstitial fibrosis in unilateral ureteral obstruction.

PubMed

Choi, Hoon Young; Lee, Hyun Gyu; Kim, Beom Seok; Ahn, Sun Hee; Jung, Ara; Lee, Mirae; Lee, Jung Eun; Kim, Hyung Jong; Ha, Sung Kyu; Park, Hyeong Cheon

2015-03-11

Microparticles (MPs) derived from kidney-derived mesenchymal stem cells (KMSCs) have recently been reported to ameliorate rarefaction of peritubular capillaries (PTC) in ischemic kidneys via delivery of proangiogenic effectors. This study aimed to investigate whether KMSC-derived MPs show anti-fibrotic effects by ameliorating endothelial-to-mesenchymal transition (EndoMT) in human umbilical vein endothelial cells (HUVEC) in vitro and by preserving PTC in kidneys with unilateral ureteral obstruction (UUO) in vivo. MPs isolated from the supernatants of KMSC were co-cultured with HUVEC to assess their in vitro biologic effects on endothelial cells. Mice were treated with MPs via the tail vein after UUO injury to assess their anti-fibrotic and PTC sparing effects. Renal tubulointerstitial damage and inflammatory cell infiltration were examined with Masson's trichrome, F4/80 and α-smooth muscle actin (α-SMA) staining and PTC rarefaction index was determined by CD31 staining. KMSC-derived MPs significantly ameliorated EndoMT and improved in vitro proliferation of TGF-β1 treated HUVEC. In vivo administration of KMSC-derived MPs significantly inhibited EndoMT of PTC endothelial cells and improved PTC rarefaction in UUO kidneys. Furthermore, administration of KMSC-derived MPs inhibited inflammatory cell infiltration as well as tubulointerstitial fibrosis in UUO mice as demonstrated by decreased F4/80 and α-SMA-positive cells and Masson's trichrome staining, respectively. Our results suggest that KMSC-derived MPs ameliorate PTC rarefaction via inhibition of EndoMT and protect against progression of renal damage by inhibiting tubulointerstitial fibrosis.

Improvement in Retinal Capillary Rarefaction After Valsartan Treatment in Hypertensive Patients.

PubMed

Jumar, Agnes; Harazny, Joanna M; Ott, Christian; Kistner, Iris; Friedrich, Stefanie; Schmieder, Roland E

2016-11-01

Decreased capillary density influences vascular resistance and perfusion. The authors aimed to investigate the influence of the renin-angiotensin receptor blocker valsartan on retinal capillary rarefaction in hypertensive patients. Retinal vascular parameters were measured noninvasively and in vivo by scanning laser Doppler flowmetry before and after 4 weeks of treatment with valsartan in 95 patients with hypertension stage 1 or 2 and compared with 55 healthy individuals. Retinal capillary rarefaction was determined with the parameters intercapillary distance (ICD) and capillary area (CapA). In hypertensive patients, ICD decreased (23.4±5.5 μm vs 21.5±5.6 μm, P<.001) and CapA increased (1564±621 vs 1776±795, P=.001) after valsartan treatment compared with baseline. Compared with healthy normotensive controls (ICD 20.2±4.2 μm, CapA 1821±652), untreated hypertensive patients showed greater ICD (P<.001) and smaller CapA (P=.019), whereas treated hypertensive patients showed no difference in ICD (P=.126) and CapA (P=.728). Therapy with valsartan for 4 weeks diminished capillary rarefaction in hypertensive patients. © 2016 Wiley Periodicals, Inc.

Polycythemia, capillary rarefaction, and focal glomerulosclerosis in two adolescents born extremely low birth weight and premature.

PubMed

Asada, Nariaki; Tsukahara, Takanori; Furuhata, Megumi; Matsuoka, Daisuke; Noda, Shunsuke; Naganuma, Kuniaki; Hashiguchi, Akinori; Awazu, Midori

2017-07-01

Low birthweight infants have a reduced number of nephrons and are at high risk of chronic kidney disease. Preterm birth and/or intrauterine growth restriction (IUGR) may also affect peritubular capillary development, as has been shown in other organs. We report two patients with a history of preterm birth and extremely low birthweight who showed polycythemia and renal capillary rarefaction. Patient 1 and 2, born at 25 weeks of gestation with a birthweight of 728 and 466 g, showed mild proteinuria at age 8 and 6 years, respectively. In addition to increasing proteinuria, hemoglobin levels became elevated towards adolescence and their serum erythropoietin (EPO) was high despite polycythemia. Light microscopic examination of renal biopsy specimens showed glomerular hypertrophy, focal segmental glomerulosclerosis, and only mild tubulointerstitial fibrosis. A decrease in the immunohistochemical staining of CD31 and CD34 endothelial cells in renal biopsy specimens was consistent with peritubular capillary rarefaction. Since kidney function was almost normal and fibrosis was not severe, we consider that the capillary rarefaction and polycythemia associated with elevated EPO levels were largely attributable to preterm birth and/or IUGR.

PIC simulation of compressive and rarefactive dust ion-acoustic solitary waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhong-Zheng; Zhang, Heng; Hong, Xue-Ren

The nonlinear propagations of dust ion-acoustic solitary waves in a collisionless four-component unmagnetized dusty plasma system containing nonextensive electrons, inertial negative ions, Maxwellian positive ions, and negatively charged static dust grains have been investigated by the particle-in-cell method. By comparing the simulation results with those obtained from the traditional reductive perturbation method, it is observed that the rarefactive KdV solitons propagate stably at a low amplitude, and when the amplitude is increased, the prime wave form evolves and then gradually breaks into several small amplitude solitary waves near the tail of soliton structure. The compressive KdV solitons propagate unstably andmore » oscillation arises near the tail of soliton structure. The finite amplitude rarefactive and compressive Gardner solitons seem to propagate stably.« less

Monitoring peripheral perfusion and microcirculation.

PubMed

Dubin, Arnaldo; Henriquez, Elizabeth; Hernández, Glenn

2018-06-01

Microcirculatory alterations play a major role in the pathogenesis of shock. Monitoring tissue perfusion might be a relevant goal for shock resuscitation. The goal of this review was to revise the evidence supporting the monitoring of peripheral perfusion and microcirculation as goals of resuscitation. For this purpose, we mainly focused on skin perfusion and sublingual microcirculation. Although there are controversies about the reproducibility of capillary refill time in monitoring peripheral perfusion, it is a sound physiological variable and suitable for the ICU settings. In addition, observational studies showed its strong ability to predict outcome. Moreover, a preliminary study suggested that it might be a valuable goal for resuscitation. These results should be confirmed by the ongoing ANDROMEDA-SHOCK randomized controlled trial. On the other hand, the monitoring of sublingual microcirculation might also provide relevant physiological and prognostic information. On the contrary, methodological drawbacks mainly related to video assessment hamper its clinical implementation at the present time. Measurements of peripheral perfusion might be useful as goal of resuscitation. The results of the ANDROMEDA-SHOCK will clarify the role of skin perfusion as a guide for the treatment of shock. In contrast, the assessment of sublingual microcirculation mainly remains as a research tool.

PRotective Effect on the coronary microcirculation of patients with DIabetes by Clopidogrel or Ticagrelor (PREDICT): study rationale and design. A randomized multicenter clinical trial using intracoronary multimodal physiology.

PubMed

Cerrato, Enrico; Quirós, Alicia; Echavarría-Pinto, Mauro; Mejia-Renteria, Hernan; Aldazabal, Andres; Ryan, Nicola; Gonzalo, Nieves; Jimenez-Quevedo, Pilar; Nombela-Franco, Luis; Salinas, Pablo; Núñez-Gil, Iván J; Rumoroso, José Ramón; Fernández-Ortiz, Antonio; Macaya, Carlos; Escaned, Javier

2017-05-19

In diabetic patients a predisposed coronary microcirculation along with a higher risk of distal particulate embolization during primary percutaneous intervention (PCI) increases the risk of peri-procedural microcirculatory damage. However, new antiplatelet agents, in particular Ticagrelor, may protect the microcirculation through its adenosine-mediated vasodilatory effects. PREDICT is an original, prospective, randomized, multicenter controlled study designed to investigate the protective effect of Ticagrelor on the microcirculation during PCI in patient with diabetes mellitus type 2 or pre-diabetic status. The primary endpoints of this study aim to test (i) the decrease in microcirculatory resistance with antiplatelet therapy (Ticagrelor > Clopidogrel; mechanistic effect) and (ii) the relative microcirculatory protection of Ticagrelor compared to Clopidogrel during PCI (Ticagrelor < Clopidogrel; protective effect). PREDICT will be the first multicentre clinical trial to test the adenosine-mediated vasodilatory effect of Ticagrelor on the microcirculation during PCI in diabetic patients. The results will provide important insights into the prospective beneficial effect of this drug in preventing microvascular impairment related to PCI ( http://www.clinicaltrials.gov No. NCT02698618).

OXYGEN TRANSPORT IN THE MICROCIRCULATION AND ITS REGULATION

PubMed Central

Pittman, Roland N.

2012-01-01

Cells require energy to carry out their functions and they typically use oxidative phosphorylation to generate the needed ATP. Thus, cells have a continuous need for oxygen which they receive by diffusion from the blood through the interstitial fluid. The circulatory system pumps oxygen-rich blood through a network of increasingly minute vessels, the microcirculation. The structure of the microcirculation is such that all cells have at least one nearby capillary for diffusive exchange of oxygen and red blood cells release the oxygen bound to hemoglobin as they traverse capillaries. This review focuses first on the historical development of techniques to measure oxygen at various sites in the microcirculation, including the blood, interstitium and cells. Next, approaches are described as to how these techniques have been employed to make discoveries about different aspects of oxygen transport. Finally, ways in which oxygen might participate in the regulation of blood flow toward matching oxygen supply to oxygen demand is discussed. Overall, the transport of oxygen to the cells of the body is one of the most critical functions of the cardiovascular system and it is in the microcirculation where the final local determinants of oxygen supply, oxygen demand and their regulation are decided. PMID:23025284

Association of Endodontic Lesions with Coronary Artery Disease.

PubMed

Liljestrand, J M; Mäntylä, P; Paju, S; Buhlin, K; Kopra, K A E; Persson, G R; Hernandez, M; Nieminen, M S; Sinisalo, J; Tjäderhane, L; Pussinen, P J

2016-11-01

An endodontic lesion (EL) is a common manifestation of endodontic infection where Porphyromonas endodontalis is frequently encountered. EL may associate with increased risk for coronary artery disease (CAD) via similar pathways as marginal periodontitis. The aim of this cross-sectional study was to delineate the associations between EL and CAD. Subgingival P. endodontalis, its immune response, and serum lipopolysaccharide were examined as potential mediators between these 2 diseases. The Finnish Parogene study consists of 508 patients (mean age, 62 y) who underwent coronary angiography and extensive clinical and radiographic oral examination. The cardiovascular outcomes included no significant CAD ( n = 123), stable CAD ( n = 184), and acute coronary syndrome (ACS; n = 169). EL was determined from a panoramic tomography. We combined data of widened periapical spaces (WPSs) and apical rarefactions to a score of EL: 1, no EL ( n = 210); 2, ≥1 WPS per 1 apical rarefaction ( n = 222); 3, ≥2 apical rarefactions ( n = 76). Subgingival P. endodontalis was defined by checkerboard DNA-DNA hybridization analysis, and corresponding serum antibodies were determined by ELISA. In our population, 50.4% had WPSs, and 22.8% apical rarefactions. A total of 51.2% of all teeth with apical rarefactions had received endodontic procedures. Subgingival P. endodontalis levels and serum immunoglobulin G were associated with a higher EL score. In the multiadjusted model (age, sex, smoking, diabetes, body mass index, alveolar bone loss, and number of teeth), having WPSs associated with stable CAD (odds ratio [OR] = 1.94, 95% confidence interval [95% CI] = 1.13 to 3.32, P = 0.016) and highest EL score were associated with ACS (OR = 2.46, 95% CI = 1.09 to 5.54, P = 0.030). This association was especially notable in subjects with untreated teeth with apical rarefactions ( n = 59, OR = 2.72, 95% CI = 1.16 to 6.40, P = 0.022). Our findings support the hypothesis that ELs are independently associated with CAD and in particular with ACS. This is of high interest from a public health perspective, considering the high prevalence of ELs and CAD.

Two alternative models concerning the perialveolar microcirculation in mammalian lungs.

PubMed

Günther, Bruno; Morgado, Enrique; Cociña, Manuela

2005-01-01

Despite the fact that the concept of sheet-flow in the pulmonary microcirculation of mammals was introduced more than three decades ago, the capillary circulatory model still prevails in the physiological literature. Since cardiac output is identical in the systemic and in pulmonary circulations, it is noteworthy that in the former, the resulting arterial pressure is five times higher than that of the latter, which means that the corresponding microcirculations must be radically different. The present study addresses this problem from both morphological and physiological perspectives.

Correlation mapping microscopy

NASA Astrophysics Data System (ADS)

McGrath, James; Alexandrov, Sergey; Owens, Peter; Subhash, Hrebesh M.; Leahy, Martin J.

2015-03-01

Changes in the microcirculation are associated with conditions such as Raynauds disease. Current modalities used to assess the microcirculation such as nailfold capillaroscopy are limited due to their depth ambiguity. A correlation mapping technique was recently developed to extend the capabilities of Optical Coherence Tomography to generate depth resolved images of the microcirculation. Here we present the extension of this technique to microscopy modalities, including confocal microscopy. It is shown that this correlation mapping microscopy technique can extend the capabilities of conventional microscopy to enable mapping of vascular networks in vivo with high spatial resolution.

Interrater Reliability and Diagnostic Performance of Subjective Evaluation of Sublingual Microcirculation Images by Physicians and Nurses: A Multicenter Observational Study.

PubMed

Lima, Alexandre; López, Alejandra; van Genderen, Michel E; Hurtado, Francisco Javier; Angulo, Martin; Grignola, Juan C; Shono, Atsuko; van Bommel, Jasper

2015-09-01

This was a cross-sectional multicenter study to investigate the ability of physicians and nurses from three different countries to subjectively evaluate sublingual microcirculation images and thereby discriminate normal from abnormal sublingual microcirculation based on flow and density abnormalities. Forty-five physicians and 61 nurses (mean age, 36 ± 10 years; 44 males) from three different centers in The Netherlands (n = 61), Uruguay (n = 12), and Japan (n = 33) were asked to subjectively evaluate a sample of 15 microcirculation videos randomly selected from an experimental model of endotoxic shock in pigs. All videos were first analyzed offline using the A.V.A. software by an independent, experienced investigator and were categorized as good, bad, or very bad microcirculation based on the microvascular flow index, perfused capillary density, and proportion of perfused capillaries. Then, the videos were randomly assigned to the examiners, who were instructed to subjectively categorize each image as good, bad, or very bad. An interrater analysis was performed, and sensitivity and specificity tests were calculated to evaluate the proportion of A.V.A. score abnormalities that the examiners correctly identified. The κ statistics indicated moderate agreement in the evaluation of microcirculation abnormalities using three categories, i.e., good, bad, or very bad (κ = 0.48), and substantial agreement using two categories, i.e., normal (good) and abnormal (bad or very bad) (κ = 0.66). There was no significant difference between the κ three and κ two statistics. We found that the examiner's subjective evaluations had good diagnostic performance and were highly sensitive (84%; 95% confidence interval, 81%-86%) and specific (87%; 95% confidence interval, 84%-90%) for sublingual microcirculatory abnormalities as assessed using the A.V.A. software. The subjective evaluations of sublingual microcirculation by physicians and nurses agreed well with a conventional offline analysis and were highly sensitive and specific for sublingual microcirculatory abnormalities.

The macro- and microcirculation of the kidney.

PubMed

Guerci, Philippe; Ergin, Bulent; Ince, Can

2017-09-01

Acute kidney injury (AKI) remains one of the main causes of morbidity and mortality in the intensive care medicine today. Its pathophysiology and progress to chronic kidney disease is still under investigation. In addition, the lack of techniques to adequately monitor renal function and microcirculation at the bedside makes its therapeutic resolution challenging. In this article, we review current concepts related to renal hemodynamics compromise as being the event underlying AKI. In doing so, we discuss the physiology of the renal circulation and the effects of alterations in systemic hemodynamics that lead to renal injury specifically in the context of reperfusion injury and sepsis. The ultimate key culprit of AKI leading to failure is the dysfunction of the renal microcirculation. The cellular and subcellular components of the renal microcirculation are discussed and how their injury contributes to AKI is described. Copyright © 2017. Published by Elsevier Ltd.

Compressive and rarefactive double layers in non-uniform plasma with q-nonextensive distributed electrons

NASA Astrophysics Data System (ADS)

Shan, S. Ali; Saleem, H.

2018-05-01

Electrostatic solitary waves and double layers (DLs) formed by the coupled ion acoustic (IA) and drift waves have been investigated in non-uniform plasma using q-nonextensive distribution function for the electrons and assuming ions to be cold Ti< Te. It is found that both compressive and rarefactive nonlinear structures (solitary waves and DLs) are possible in such a system. The steeper gradients are supportive for compressive solitary (and double layers) and destructive for rarefactive ones. The q-nonextensivity parameter q and the magnitudes of gradient scale lengths of density and temperature have significant effects on the amplitude of the double layers (and double layers) as well as on the speed of these structures. This theoretical model is general which has been applied here to the F-region ionosphere for illustration.

Formation of rarefaction waves in origami-based metamaterials

NASA Astrophysics Data System (ADS)

Yasuda, H.; Chong, C.; Charalampidis, E. G.; Kevrekidis, P. G.; Yang, J.

2016-04-01

We investigate the nonlinear wave dynamics of origami-based metamaterials composed of Tachi-Miura polyhedron (TMP) unit cells. These cells exhibit strain softening behavior under compression, which can be tuned by modifying their geometrical configurations or initial folded conditions. We assemble these TMP cells into a cluster of origami-based metamaterials, and we theoretically model and numerically analyze their wave transmission mechanism under external impact. Numerical simulations show that origami-based metamaterials can provide a prototypical platform for the formation of nonlinear coherent structures in the form of rarefaction waves, which feature a tensile wavefront upon the application of compression to the system. We also demonstrate the existence of numerically exact traveling rarefaction waves in an effective lumped-mass model. Origami-based metamaterials can be highly useful for mitigating shock waves, potentially enabling a wide variety of engineering applications.

Composite nonlinear structure within the magnetosonic soliton interactions in a spin-1/2 degenerate quantum plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Jiu-Ning, E-mail: hanjiuning@126.com; Luo, Jun-Hua; Li, Jun-Xiu

2015-06-15

We study the basic physical properties of composite nonlinear structure induced by the head-on collision of magnetosonic solitons. Solitary waves are assumed to propagate in a quantum electron-ion magnetoplasma with spin-1/2 degenerate electrons. The main interest of the present work is to investigate the time evolution of the merged composite structure during a specific time interval of the wave interaction process. We consider three cases of colliding-situation, namely, compressive-rarefactive solitons interaction, compressive-compressive solitons interaction, and rarefactive-rarefactive solitons interaction, respectively. Compared with the last two colliding cases, the changing process of the composite structure is more complex for the first situation.more » Moreover, it is found that they are obviously different for the last two colliding cases.« less

Dynamic Contrast-Enhanced Ultrasound Identifies Microcirculatory Alterations in Sepsis-Induced Acute Kidney Injury.

PubMed

Lima, Alexandre; van Rooij, Tom; Ergin, Bulent; Sorelli, Michele; Ince, Yasin; Specht, Patricia A C; Mik, Egbert G; Bocchi, Leonardo; Kooiman, Klazina; de Jong, Nico; Ince, Can

2018-05-15

We developed quantitative methods to analyze microbubble kinetics based on renal contrast-enhanced ultrasound imaging combined with measurements of sublingual microcirculation on a fixed area to quantify early microvascular alterations in sepsis-induced acute kidney injury. Prospective controlled animal experiment study. Hospital-affiliated animal research institution. Fifteen female pigs. The animals were instrumented with a renal artery flow probe after surgically exposing the kidney. Nine animals were given IV infusion of lipopolysaccharide to induce septic shock, and six were used as controls. Contrast-enhanced ultrasound imaging was performed on the kidney before, during, and after having induced shock. Sublingual microcirculation was measured continuously using the Cytocam on the same spot. Contrast-enhanced ultrasound effectively allowed us to develop new analytical methods to measure dynamic variations in renal microvascular perfusion during shock and resuscitation. Renal microvascular hypoperfusion was quantified by decreased peak enhancement and an increased ratio of the final plateau intensity to peak enhancement. Reduced intrarenal blood flow could be estimated by measuring the microbubble transit times between the interlobar arteries and capillary vessels in the renal cortex. Sublingual microcirculation measured using the Cytocam in a fixed area showed decreased functional capillary density associated with plugged sublingual capillary vessels that persisted during and after fluid resuscitation. In our lipopolysaccharide model, with resuscitation targeted at blood pressure, the contrast-enhanced ultrasound imaging can identify renal microvascular alterations by showing prolonged contrast enhancement in microcirculation during shock, worsened by resuscitation with fluids. Concomitant analysis of sublingual microcirculation mirrored those observed in the renal microcirculation.

High-sensitivity detection and monitoring of microcirculation using cutaneous and catheter probes for Doppler optical coherence tomography

NASA Astrophysics Data System (ADS)

Yang, Victor X.; Gordon, M. L.; Qi, B.; Yue, E. Seng; Tang, S.; Bisland, Stuart K.; Pekar, J.; Lo, S.; Marcon, Norman E.; Wilson, B.; Vitkin, Alex

2003-07-01

Background: Currently clinical Doppler ultrasound cannot detect microvascular blood flow and it is difficult to provide depth discrimination using laser Doppler flowmetry. Doppler optical coherence tomography (DOCT) is a novel technique for noninvasive subsurface imaging of microcirculation and tissue structure. Aims: To design handheld and catheter-based DOCT probes for clinical cutaneous and endoscopic imaging. To develop signal processing techniques for real-time detection and quantification of microvascular blood flow. Methods: A DOCT system, with interchangeable cutaneous and catheter probes, was developed. The axial spatial resolution was 10 μm, and the velocity resolution was 20 μm/s, using a 1300 nm broadband infrared light. The system achieved real-time imaging with frame rates up to 32 Hz at 512 x 256 pixels per frame. We used the system to detect microcirculation in human skin and rat esophagus, and to monitor microvascular responses to photodynamic therapy (PDT) in a rat tumor model. Results: We present experimental results from in vivo DOCT imaging of microcirculation in human skin arterio-venous malformations (AVM), normal rat esophagus, and a rat gliosarcoma PDT model. In the PDT model, we followed microvascular responses to PDT and observed differences in the microcirculation during and after therapy, which can have important implications for PDT dosimetry and treatment optimization. Conclusions: To our knowledge, this is the first demonstration of endoscopic catheter-based DOCT detection of microcirculation in vivo. In addition, AVM can be detected using handheld cutaneous DOCT probes under clinical settings. DOCT may serve as a real-time monitoring tool for PDT dosimetry, especially for vascular targeting photosensitizers.

Binge drinking disturbs hepatic microcirculation after transplantation: prevention with free radical scavengers.

PubMed

Zhong, Z; Arteel, G E; Connor, H D; Schemmer, P; Chou, S C; Raleigh, J A; Mason, R P; Lemasters, J J; Thurman, R G

1999-08-01

Disturbances in hepatic microcirculation increase graft injury and failure; therefore, this study evaluates the effects of ethanol on microcirculation after liver transplantation. Donor rats were given one dose of ethanol (5 g/kg) by gavage 20 h before explantation, and grafts were stored in University of Wisconsin solution for 24 h before implantation. Acute ethanol treatment decreased 7-day survival of grafts from about 90 to 30%, increased transaminase release nearly 4-fold, and decreased bile production by 60%. Moreover, portal pressure increased significantly and liver surface oxygen tension decreased about 50%, indicating that ethanol disturbs hepatic microcirculation. Pimonidazole, a 2-nitroimidazole hypoxia marker, was given i.v. to recipients 30 min after implantation, and grafts were harvested 1 h later. Ethanol increased hepatic pimonidazole binding about 3-fold, indicating that ethanol led to hypoxia in fatty grafts. Ethanol also significantly increased free radicals in bile. Catechin (30 mg/kg i.v. upon reperfusion), a free radical scavenger, and Carolina Rinse solution, which contains several agents that inhibit free radical formation, minimized disturbances in microcirculation and prevented pimonidazole adduct formation significantly. These treatments also blunted increases in transaminase release and improved survival of fatty grafts. Destruction of Kupffer cells with GdCl(3) (20 mg/kg i.v. 24 h before explantation) or inhibition of formation of leukotrienes with MK-886 (50 microM in University of Wisconsin or rinse solution) also minimized hypoxia and improved survival after transplantation. Taken together, these results demonstrate that ethanol disturbs hepatic microcirculation, leading to graft hypoxia after transplantation, most likely by activating Kupffer cells and increasing free radical production.

Interactions of solitary waves and compression/expansion waves in core-annular flows

NASA Astrophysics Data System (ADS)

Maiden, Michelle; Anderson, Dalton; El, Gennady; Franco, Nevil; Hoefer, Mark

2017-11-01

The nonlinear hydrodynamics of an initial step leads to the formation of rarefaction waves and dispersive shock waves in dispersive media. Another hallmark of these media is the soliton, a localized traveling wave whose speed is amplitude dependent. Although compression/expansion waves and solitons have been well-studied individually, there has been no mathematical description of their interaction. In this talk, the interaction of solitons and shock/rarefaction waves for interfacial waves in viscous, miscible core-annular flows are modeled mathematically and explored experimentally. If the interior fluid is continuously injected, a deformable conduit forms whose interfacial dynamics are well-described by a scalar, dispersive nonlinear partial differential equation. The main focus is on interactions of solitons with dispersive shock waves and rarefaction waves. Theory predicts that a soliton can either be transmitted through or trapped by the extended hydrodynamic state. The notion of reciprocity is introduced whereby a soliton interacts with a shock wave in a reciprocal or dual fashion as with the rarefaction. Soliton reciprocity, trapping, and transmission are observed experimentally and are found to agree with the modulation theory and numerical simulations. This work was partially supported by NSF CAREER DMS-1255422 (M.A.H.) and NSF GRFP (M.D.M.).

Rarefaction acceleration in magnetized gamma-ray burst jets

NASA Astrophysics Data System (ADS)

Sapountzis, Konstantinos; Vlahakis, Nektarios

2013-09-01

Relativistic jets associated with long/soft gamma-ray bursts are formed and initially propagate in the interior of the progenitor star. Because of the subsequent loss of their external pressure support after they cross the stellar surface, these flows can be modelled as moving around a corner. A strong steady-state rarefaction wave is formed, and the sideways expansion is accompanied by a rarefaction acceleration. We investigate the efficiency and the general characteristics of this mechanism by integrating the steady-state, special relativistic, magnetohydrodynamic equations, using a special set of partial exact solutions in planar geometry (r self-similar with respect to the `corner'). We also derive analytical approximate scalings in the ultrarelativistic cold/magnetized, and hydrodynamic limits. The mechanism is more effective in magnetized than in purely hydrodynamic flows. It substantially increases the Lorentz factor without much affecting the opening of the jet; the resulting values of their product can be much greater than unity, allowing for possible breaks in the afterglow light curves. These findings are similar to the ones from numerical simulations of axisymmetric jets by Komissarov et al. and Tchekhovskoy et al., although in our approach we describe the rarefaction as a steady-state simple wave and self-consistently calculate the opening of the jet that corresponds to zero external pressure.

Application of LASCA imaging for detection of disorders of blood microcirculation in chicken embryo, infected by Chlamydia trachomatis

NASA Astrophysics Data System (ADS)

Ulianova, Onega; Subbotina, Irina; Filonova, Nadezhda; Zaitsev, Sergey; Saltykov, Yury; Polyanina, Tatiana; Lyapina, Anna; Ulyanov, Sergey; Larionova, Olga; Feodorova, Valentina

2018-04-01

Methods of t-LASCA and s-LASCA imaging have been firstly adapted to the problem of monitoring of blood microcirculation in chicken embryo model. Set-up for LASCA imaging of chicken embryo is mounted. Disorders of blood microcirculation in embryonated chicken egg, infected by Chlamydia trachomatis, are detected. Speckle-imaging technique is compared with white-light ovoscopy and new method of laser ovoscopy, based on the scattering of coherent light, advantages of LASCA imaging for the early detection of developmental process of chlamydial agent is demonstrated.

Physiopathology of the cochlear microcirculation.

PubMed

Shi, Xiaorui

2011-12-01

Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature. Published by Elsevier B.V.

Physiopathology of the Cochlear Microcirculation

PubMed Central

Shi, Xiaorui

2011-01-01

Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature. PMID:21875658

Effects of Mangifera indica (Careless) on Microcirculation and Glucose Metabolism in Healthy Volunteers.

PubMed

Buchwald-Werner, Sybille; Schön, Christiane; Frank, Sonja; Reule, Claudia

2017-07-01

A commercial Mangifera indica fruit powder (Careless) showed beneficial acute effects on microcirculation in a randomized, double-blind, crossover pilot study. Here, long-term effects on microcirculation and glucose metabolism were investigated in a double-blind, randomized, placebo-controlled, 3-arm parallel-design study in healthy individuals. A daily dose of 100 mg or 300 mg of the fruit powder was compared to placebo after supplementation for 4 weeks. Microcirculation and endothelial function were assessed by the Oxygen-to-see System and pulse amplitude tonometry, respectively. Glucose metabolism was assessed under fasting and postprandial conditions by capillary glucose and HbA1c values.Microcirculatory reactive hyperemia flow increased, especially in the 100 mg group (p = 0.025). The 300 mg of the M. indica fruit preparation reduced postprandial glucose levels by trend if compared to placebo (p = 0.0535) accompanied by significantly lower HbA1c values compared to baseline. Furthermore, 300 mg intake significantly improved postprandial endothelial function in individuals with decreased endothelial function after high-dose glucose intake (p = 0.0408; n = 11).In conclusion, the study suggests moderate beneficial effects of M. indica fruit preparation on microcirculation, endothelial function, and glucose metabolism. Georg Thieme Verlag KG Stuttgart · New York.

Localization of the ANG II type 2 receptor in the microcirculation of skeletal muscle

NASA Technical Reports Server (NTRS)

Nora, E. H.; Munzenmaier, D. H.; Hansen-Smith, F. M.; Lombard, J. H.; Greene, A. S.; Cowley, A. W. (Principal Investigator)

1998-01-01

Only functional studies have suggested the presence of the ANG II type 2 (AT2) receptor in the microcirculation. To determine the distribution of this receptor in the rat skeletal muscle microcirculation, a polyclonal rabbit anti-rat antiserum was developed and used for immunohistochemistry and Western blot analysis. The antiserum was prepared against a highly specific and antigenic AT2-receptor synthetic peptide and was validated by competition and sensitivity assays. Western blot analysis demonstrated a prominent, single band at approximately 40 kDa in cremaster and soleus muscle. Immunohistochemical analysis revealed a wide distribution of AT2 receptors throughout the skeletal muscle microcirculation in large and small microvessels. Microanatomic studies displayed an endothelial localization of the AT2 receptor, whereas dual labeling with smooth muscle alpha-actin also showed colocalization of the AT2 receptor with vascular smooth muscle cells. Other cells associated with the microvessels also stained positive for AT2 receptors. Briefly, this study confirms previous functional data and localizes the AT2 receptor to the microcirculation. These studies demonstrate that the AT2 receptor is present on a variety of vascular cell types and that it is situated in a fashion that would allow it to directly oppose ANG II type 1 receptor actions.

Blood microcirculation of ischemic pancreatitis

NASA Astrophysics Data System (ADS)

Dmitrieva, Irina V.; Arakelian, Sergei M.; Antonov, Olga V.

1998-06-01

Blood Microcirculation includes many of different components, which are joined by unique multiple system. Capillaries are one of the main link in this morpho-functional chain. Changes in any components of blood microcirculation are revealed by many of pathological processes in different organs and systems of the whole organism. We investigated 250 patients from 30 to 77 ages. Men included 149, women -- 101. The main diagnosis of all patients was the ischaemic pancreatitis. For verification of this diagnosis we used the whole spectrum of clinical, laboratorial and instrumental methods. These were the following: the definition of amylase of blood and urine, sonography and computer's tomography of pancreas, angiography of vessels of pancreas and Doppler's sonography of abdominal aorta and her branches: arteria mesenterica superior (AMS), truncus coeliacus (TC), arteria hepatica communis (AHC) and arteria lienalis (AL). We investigated the blood microcirculation of the mucous of the inferior lip, using Laser Dopplerography. The equipment for this research was LACC-01 with modified computer's program. The normal levels of blood microcirculation were from 120 to 180 Units. But patients with ischaemic pancreatitis had more lower level than in normal situation. This method are suggested as express diagnostic in the cases of abdominal ischaemic pathology. It can used as singel method or in combined with ultrasound Dopplerography.

Relationship between the Direction of Ophthalmic Artery Blood Flow and Ocular Microcirculation before and after Carotid Artery Stenting.

PubMed

Ishii, Masashi; Hayashi, Morito; Yagi, Fumihiko; Sato, Kenichiro; Tomita, Goji; Iwabuchi, Satoshi

2016-01-01

When internal carotid artery stenosis is accompanied by ocular ischemic syndrome, intervention is recommended to prevent irreversible visual loss. In this study, we used laser speckle flowgraphy to measure the ocular microcirculation in the optic nerve head before and after carotid artery stenting (CAS) of 40 advanced internal carotid stenosis lesions from 37 patients. The aim was to investigate the relationship between ocular microcirculation and the direction of ophthalmic artery blood flow obtained by angiography. We found that there was a significant increase in blood flow after CAS ( P = 0.003). Peak systolic velocity as an indicator of the rate of stenosis was also significantly higher in the group with retrograde/undetected flow of the ophthalmic artery than in the group with antegrade flow ( P = 0.002). In all cases where retrograde flow of the ophthalmic artery was observed before stenting, the flow changed to antegrade after stenting. Through the use of laser speckle flowgraphy, this study found that CAS can improve ocular microcirculation. Furthermore, while patients displaying retrograde flow of the ophthalmic artery before stenting have a poor prognosis, CAS corrected the flow to antegrade, suggesting that visual loss can be prevented by improving the ocular microcirculation.

Characterization of rarefaction waves in van der Waals fluids

NASA Astrophysics Data System (ADS)

Yuen, Albert; Barnard, John J.

2015-12-01

We calculate the isentropic evolution of an instantaneously heated foil, assuming a van der Waals equation of state with the Maxwell construction. The analysis by Yuen and Barnard [Phys. Rev. E 92, 033019 (2015), 10.1103/PhysRevE.92.033019] is extended for the particular case of three degrees of freedom. We assume heating to temperatures in the vicinity of the critical point. The self-similar profiles of the rarefaction waves describing the evolution of the foil display plateaus in density and temperature due to a phase transition from the single-phase to the two-phase regime. The hydrodynamic equations are expressed in a dimensionless form and the solutions form a set of universal curves, depending on a single parameter: the dimensionless initial entropy. We characterize the rarefaction waves by calculating how the plateau length, density, pressure, temperature, velocity, internal energy, and sound speed vary with dimensionless initial entropy.

Rarefaction effects in gas flows over curved surfaces

NASA Astrophysics Data System (ADS)

Dongari, Nishanth; White, Craig; Scanlon, Thomas J.; Zhang, Yonghao; Reese, Jason M.

2012-11-01

The fundamental test case of gas flow between two concentric rotating cylinders is considered in order to investigate rarefaction effects associated with the Knudsen layers over curved surfaces. We carry out direct simulation Monte Carlo simulations covering a wide range of Knudsen numbers and accommodation coefficients, and for various outer-to-inner cylinder radius ratios. Numerical data is compared with classical slip flow theory and a new power-law (PL) wall scaling model. The PL model incorporates Knudsen layer effects in near-wall regions by taking into account the boundary limiting effects on the molecular free paths. The limitations of both theoretical models are explored with respect to rarefaction and curvature effects. Torque and velocity profile comparisons also convey that mere prediction of integral flow parameters does not guarantee the accuracy of a theoretical model, and that it is important to ensure that prediction of the local flowfield is in agreement with simulation data.

Formation of rarefaction waves in origami-based metamaterials

DOE PAGES

Yasuda, H.; Chong, C.; Charalampidis, E. G.; ...

2016-04-15

Here, we investigate the nonlinear wave dynamics of origami-based metamaterials composed of Tachi-Miura polyhedron (TMP) unit cells. These cells exhibit strain softening behavior under compression, which can be tuned by modifying their geometrical configurations or initial folded conditions. We assemble these TMP cells into a cluster of origami-based metamaterials, and we theoretically model and numerically analyze their wave transmission mechanism under external impact. Numerical simulations show that origami-based metamaterials can provide a prototypical platform for the formation of nonlinear coherent structures in the form of rarefaction waves, which feature a tensile wavefront upon the application of compression to the system.more » We also demonstrate the existence of numerically exact traveling rarefaction waves in an effective lumped-mass model. Origami-based metamaterials can be highly useful for mitigating shock waves, potentially enabling a wide variety of engineering applications.« less

[The relationship between ophthalmic nerve lesion in glaucoma and ocular and systemic haemodynamic disturbance].

PubMed

Liu, L; Yuan, S; Yang, W

1999-04-01

To explore the relationship between the optic nerve lesion in glaucoma and ocular and systemic haemodynamic disturbance. The color Doppler imaging was used to study blood velocity in the ophthalmic, the central retinal and the short posterior ciliary arteries in 34 patients with primary open angle glaucoma, 31 patients with low tension glaucoma and 90 healthy controls. The peak systolic velocity(PSV), the end diastolic velocity (EDV) and resistive index (RI) in each artery were measured, moreover the nailfold microcirculation and blood viscosity in each patient were examined. Compared with the control group, the PSV and EDV of the central retinal arteries were significantly lower while the RI of the central retinal arteries was significantly higher in both POAG and LTG patients. The RI of the short posterior ciliary arteries however was significantly higher in POAG. Nailfold microcirculation shows that some important parameters, including flow pattern, loop surrounding, morphological weighted value, total weighted value and capillary deformity rate in the two glaucoma groups were higher, whereas the flow velocity was lower than in the control group. The plasm viscosity and the whole blood viscosity (low spear) were higher than normal. According to our measurements, the nailfold microcirculation and blood viscosity was worse at the end stage of glaucoma than at early stage. The correlative analysis between measurement results of color doppler imaging and microcirculation and heamorrheology showed that nailfold microcirculation morphological weighted value was negatively correlated with the EDV of the central retinal artery and positively correlated with the RI of the central retinal artery in LTG patients. The abnormity of ocular haemodynamics and systemic microcirculation and blood viscosity is one important factor of optic nerve damage in glaucoma.

Chemotherapy impedes in vitro microcirculation and promotes migration of leukemic cells with impact on metastasis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prathivadhi-Bhayankaram, Sruti V.; Ning, Jianhao; Mimlitz, Michael

Although most cancer drugs target the proliferation of cancer cells, it is metastasis, the complex process by which cancer cells spread from the primary tumor to other tissues and organs of the body where they form new tumors, that leads to over 90% of all cancer deaths. Thus, there is an urgent need for anti-metastasis therapy. Surprisingly, emerging evidence suggests that certain anti-cancer drugs such as paclitaxel and doxorubicin can actually promote metastasis, but the mechanism(s) behind their pro-metastatic effects are still unclear. Here, we use a microfluidic microcirculation mimetic (MMM) platform which mimics the capillary constrictions of the pulmonarymore » and peripheral microcirculation, to determine if in-vivo-like mechanical stimuli can evoke different responses from cells subjected to various cancer drugs. In particular, we show that leukemic cancer cells treated with doxorubicin and daunorubicin, commonly used anti-cancer drugs, have over 100% longer transit times through the device, compared to untreated leukemic cells. Such delays in the microcirculation are known to promote extravasation of cells, a key step in the metastatic cascade. Furthermore, we report a significant (p < 0.01) increase in the chemotactic migration of the doxorubicin treated leukemic cells. Both enhanced retention in the microcirculation and enhanced migration following chemotherapy, are pro-metastatic effects which can serve as new targets for anti-metastatic drugs. - Highlights: • Doxorubicin enhances migration of leukemic cancer cells before cell death. • Doxorubicin and Daunorubicin stiffen and delay cells in mimicked microcirculation. • Some cancer drugs cause changes in cell mechanics that lead to pro-metastatic effects. • Cell mechanics becomes a new target for anti-metastatic drugs.« less

The effect of a cryotherapy gel wrap on the microcirculation of skin affected by chronic venous disorders.

PubMed

Kelechi, Teresa J; Mueller, Martina; Zapka, Jane G; King, Dana E

2011-11-01

The aim of this randomized clinical trial was to investigate a cryotherapy (cooling) gel wrap applied to lower leg skin affected by chronic venous disorders to determine whether therapeutic cooling improves skin microcirculation. Chronic venous disorders are under-recognized vascular health problems that result in severe skin damage and ulcerations of the lower legs. Impaired skin microcirculation contributes to venous leg ulcer development, thus new prevention therapies should address the microcirculation to prevent venous leg ulcers. Sixty participants (n = 30 per group) were randomized to receive one of two daily 30-minute interventions for four weeks. The treatment group applied the cryotherapy gel wrap around the affected lower leg skin, or compression and elevated the legs on a special pillow each evening at bedtime. The standard care group wore compression and elevated the legs only. Laboratory pre- and post-measures included microcirculation measures of skin temperature with a thermistor, blood flow with a laser Doppler flowmeter, and venous refill time with a photoplethysmograph. Data were collected between 2008 2009 and analysed using descriptive statistics, paired t-tests or Wilcoxon signed ranks tests, logistic regression analyses, and mixed model analyses. Fifty-seven participants (treatment = 28; standard care = 29) completed the study. The mean age was 62 years, 70% female, 50% African American. In the final adjusted model, there was a statistically significant decrease in blood flow between the two groups (-6.2[-11.8; -0.6], P = 0.03). No statistically significant differences were noted in temperature or venous refill time. Study findings suggest that cryotherapy improves blood flow by slowing movement within the microcirculation and thus might potentially provide a therapeutic benefit to prevent leg ulcers. © 2011 Blackwell Publishing Ltd.

The effect of a cryotherapy gel wrap on the microcirculation of skin affected by Chronic Venous Disorders

PubMed Central

Mueller, Martina; Zapka, Jane G.; King, Dana E.

2011-01-01

Aim This randomized clinical trial was conducted 2008 – 2009 to investigate a cryotherapy (cooling) gel wrap applied to lower leg skin affected by chronic venous disorders to determine whether therapeutic cooling improves skin microcirculation. Impaired skin microcirculation contributes to venous leg ulcer development, thus new prevention therapies should address the microcirculation to prevent venous leg ulcers. Data Sources Sixty participants (n = 30 per group) were randomized to receive one of two daily 30-minute interventions for four weeks. The treatment group applied the cryotherapy gel wrap around the affected lower leg skin, or compression and elevated the legs on a special pillow each evening at bedtime. The standard care group wore compression and elevated the legs only. Laboratory pre- and post-measures included microcirculation measures of skin temperature with a thermistor, blood flow with a laser Doppler flowmeter, and venous refill time with a photoplethysmograph. Review methods Data were analysed using descriptive statistics, paired t-tests or Wilcoxon signed ranks tests, logistic regression analyses, and mixed model analyses. Results Fifty-seven participants (treatment = 28; standard care = 29) completed the study. The mean age was 62 years, 70% female, 50% African American. In the final adjusted model, there was a statistically significant decrease in blood flow between the two groups (−6.2[−11.8; −0.6], P = 0.03). No statistically significant differences were noted in temperature or venous refill time. Conclusion Study findings suggest that cryotherapy improves blood flow by slowing movement within the microcirculation and thus might potentially provide a therapeutic benefit to prevent leg ulcers. PMID:21592186

Comparison of cerebral microcirculation of alloxan diabetes and healthy mice using laser speckle contrast imaging

NASA Astrophysics Data System (ADS)

Timoshina, Polina A.; Shi, Rui; Zhang, Yang; Zhu, Dan; Semyachkina-Glushkovskaya, Oxana V.; Tuchin, Valery V.; Luo, Qingming

2015-03-01

The study of blood microcirculation is one of the most important problems of the medicine. This paper presents results of experimental study of cerebral blood flow microcirculation in mice with alloxan-induced diabetes using Temporal Laser Speckle Imaging (TLSI). Additionally, a direct effect of glucose water solution (concentration 20% and 45%) on blood flow microcirculation was studied. In the research, 20 white laboratory mice weighing 20-30 g were used. The TLSI method allows one to investigate time dependent scattering from the objects with complex dynamics, since it possesses greater temporal resolution. Results show that in brain of animal diabetic group diameter of sagittal vein is increased and the speed of blood flow reduced relative to the control group. Topical application of 20%- or 45%-glucose solutions also causes increase of diameter of blood vessels and slows down blood circulation. The results obtained show that diabetes development causes changes in the cerebral microcirculatory system and TLSI techniques can be effectively used to quantify these alterations.

[Unintended cooling, active warming, and microcirculation in cardiosurgical patients].

PubMed

Aksel'rod, B A; Trekova, N A; Guleshov, V A; Tolstova, I A; Gus'kov, D A; Babaev, M A

2010-01-01

The study was undertaken to compare various methods to maintain a patient's body temperature and to evaluate their impact on microcirculation during myocardial revascularization under normothermal extracorporeal circulation (NTEC). The study enrolled 50 patients with NYHA Functional Classes III-IV coronary heart disease, who underwent aortocoronary bypass surgery under NTEC. A HICO-AQUATHERM 660 water-warming unit (Hirtz, Germany) was used in Group 1 patients (n=30). A Bair Hugger air-warming unit (Arizant, U.S.A.) with a mattress located under a patient was employed in Group 2 (n=20). Intraoperative microcirculation monitoring was carried out by a laser analyzer (Lazma, Moscow).

On Exact Solutions of Rarefaction-Rarefaction Interactions in Compressible Isentropic Flow

NASA Astrophysics Data System (ADS)

Jenssen, Helge Kristian

2017-12-01

Consider the interaction of two centered rarefaction waves in one-dimensional, compressible gas flow with pressure function p(ρ )=a^2ρ ^γ with γ >1. The classic hodograph approach of Riemann provides linear 2nd order equations for the time and space variables t, x as functions of the Riemann invariants r, s within the interaction region. It is well known that t( r, s) can be given explicitly in terms of the hypergeometric function. We present a direct calculation (based on works by Darboux and Martin) of this formula, and show how the same approach provides an explicit formula for x( r, s) in terms of Appell functions (two-variable hypergeometric functions). Motivated by the issue of vacuum and total variation estimates for 1-d Euler flows, we then use the explicit t-solution to monitor the density field and its spatial variation in interactions of two centered rarefaction waves. It is found that the variation is always non-monotone, and that there is an overall increase in density variation if and only if γ >3. We show that infinite duration of the interaction is characterized by approach toward vacuum in the interaction region, and that this occurs if and only if the Riemann problem defined by the extreme initial states generates a vacuum. Finally, it is verified that the minimal density in such interactions decays at rate O(1)/ t.

Cardiac frequency and cutaneous microcirculation during and after exercising in the view of physical condition.

PubMed

Saemann, Lars; Lachner, Karin; Wenzel, Folker

2017-01-01

In the field of cardiovascular diseases an ergometer test is a common diagnostical method in which a change in microcirculation can be reached. In this paper cardiac frequency and cutaneous microcirculation during and after exercising will be compared with each other. The cutaneous microcirculation of  6 healthy volunteers (2 females, 4 males) is measured. As an instrument the PeriFlux 5000 combined with a Laser-Doppler-Flow(LDF)-Probe (Perimed Instruments) is used. The cardiac frequency (CF) is measured by the POLAR T31 sensor and as an ergometer the ERGO-FIT ® 457 is used. The mean initial LDF (97,7±57,3 PU) decreases at the beginning (64,5±21,7 PU), increases during theexercise, reaches its maximum (247,8±82,1 PU) after the end of the exercise and drops to lower values (256,4±69,5 PU)after a few minutes. Contrasting to the LDF the mean initial CF (86±22/min) increases at the beginning (97±9/min),furthermore during the whole exercise (103±9/min) and then falls after having finished the exercise (96±3/min).Furthermore, during regeneration, one can see the CF decreasing towards its initial value, while LDF reaches its maximum. In further studies, realized with volunteers with well-known levels of physical condition, a directconnection between cutaneous microcirculation and physical condition might be found.

Low-Magnitude High-Frequency Vibration Accelerated the Foot Wound Healing of n5-streptozotocin-induced Diabetic Rats by Enhancing Glucose Transporter 4 and Blood Microcirculation.

PubMed

Yu, Caroline Oi-Ling; Leung, Kwok-Sui; Jiang, Jonney Lei; Wang, Tina Bai-Yan; Chow, Simon Kwoon-Ho; Cheung, Wing-Hoi

2017-09-14

Delayed wound healing is a Type 2 diabetes mellitus (DM) complication caused by hyperglycemia, systemic inflammation, and decreased blood microcirculation. Skeletal muscles are also affected by hyperglycemia, resulting in reduced blood flow and glucose uptake. Low Magnitude High Frequency Vibration (LMHFV) has been proven to be beneficial to muscle contractility and blood microcirculation. We hypothesized that LMHFV could accelerate the wound healing of n5-streptozotocin (n5-STZ)-induced DM rats by enhancing muscle activity and blood microcirculation. This study investigated the effects of LMHFV in an open foot wound created on the footpad of n5-STZ-induced DM rats (DM_V), compared with no-treatment DM (DM), non-DM vibration (Ctrl_V) and non-DM control rats (Ctrl) on Days 1, 4, 8 and 13. Results showed that the foot wounds of DM_V and Ctrl_V rats were significantly reduced in size compared to DM and Ctrl rats, respectively, at Day 13. The blood glucose level of DM_V rats was significantly reduced, while the glucose transporter 4 (GLUT4) expression and blood microcirculation of DM_V rats were significantly enhanced in comparison to those of DM rats. In conclusion, LMHFV can accelerate the foot wound healing process of n5-STZ rats.

Preliminary clinical evaluation of automated analysis of the sublingual microcirculation in the assessment of patients with septic shock: Comparison of automated versus semi-automated software.

PubMed

Sharawy, Nivin; Mukhtar, Ahmed; Islam, Sufia; Mahrous, Reham; Mohamed, Hassan; Ali, Mohamed; Hakeem, Amr A; Hossny, Osama; Refaa, Amera; Saka, Ahmed; Cerny, Vladimir; Whynot, Sara; George, Ronald B; Lehmann, Christian

2017-01-01

The outcome of patients in septic shock has been shown to be related to changes within the microcirculation. Modern imaging technologies are available to generate high resolution video recordings of the microcirculation in humans. However, evaluation of the microcirculation is not yet implemented in the routine clinical monitoring of critically ill patients. This is mainly due to large amount of time and user interaction required by the current video analysis software. The aim of this study was to validate a newly developed automated method (CCTools®) for microcirculatory analysis of sublingual capillary perfusion in septic patients in comparison to standard semi-automated software (AVA3®). 204 videos from 47 patients were recorded using incident dark field (IDF) imaging. Total vessel density (TVD), proportion of perfused vessels (PPV), perfused vessel density (PVD), microvascular flow index (MFI) and heterogeneity index (HI) were measured using AVA3® and CCTools®. Significant differences between the numeric results obtained by the two different software packages were observed. The values for TVD, PVD and MFI were statistically related though. The automated software technique successes to show septic shock induced microcirculation alterations in near real time. However, we found wide degrees of agreement between AVA3® and CCTools® values due to several technical factors that should be considered in the future studies.

Time Evolution of Sublingual Microcirculatory Changes in Recreational Marathon Runners

PubMed Central

Arstikyte, Justina; Vaitkaitiene, Egle; Vaitkaitis, Dinas

2017-01-01

We aimed to evaluate changes in sublingual microcirculation induced by a marathon race. Thirteen healthy male controls and 13 male marathon runners volunteered for the study. We performed sublingual microcirculation, using a Cytocam-IDF device (Braedius Medical, Huizen, Netherlands), and systemic hemodynamic measurements four times: 24 hours prior to their participation in the Kaunas Marathon (distance: 41.2 km), directly after finishing the marathon, 24 hours after the marathon, and one week after the marathon. The marathon runners exhibited a higher functional capillary density (FCD) and total vascular density of small vessels at the first visit compared with the controls. Overall, we did not find any changes in sublingual microcirculation of the marathon runners at any of the other visits. However, in a subgroup of marathon runners with a decreased FCD compared to the subgroup with increased FCD, the subgroup with decreased FCD had shorter running time (190.37 ± 30.2 versus 221.80 ± 23.4 min, p = 0.045), ingested less fluids (907 ± 615 versus 1950 ± 488 mL, p = 0.007) during the race, and lost much more weight (−2.4 ± 1.3 versus −1.0 ± 0.8 kg, p = 0.041). Recreational marathon running is not associated with an alteration of sublingual microcirculation. However, faster running and dehydration may be crucial for further impairing microcirculation. PMID:28828386

Basal sympathetic activity to the microcirculation in tetraplegic man revealed by wavelet transform of laser Doppler flowmetry.

PubMed

Bernjak, A; Deitrick, G A; Bauman, W A; Stefanovska, A; Tuckman, J

2011-05-01

The 1984/86 published neurogram results showing only rare sympathetic nerve activity (SNA) to the muscles and skin in tetraplegia are still accepted. The present study by a different method attempted to confirm or deny those findings. The effect of basal SNA to the microcirculation of the feet and calf in 10 complete (AIS A) traumatic tetraplegic and 10 healthy age matched subjects were evaluated by wavelet transform of laser Doppler flowmetry (LDF) recordings. The results clearly indicated there is significant basal SNA from the decentralized spinal cord in tetraplegia. In addition, wavelet analysis allowed a study of other influences on the microcirculation besides SNA. Collectively, in tetraplegia compared with controls, the powers of the low frequency oscillations in blood flow were reduced; in that the endothelium caused less vasodilatation while the SNA and intrinsic vascular smooth muscles induced smaller degrees of vasoconstriction. However, the high frequency and especially the cardiac powers were greater. The latter presenting an obvious important factor for the preservation of blood flow in the microcirculation. It is suggested that basal SNA to the cutaneous microcirculation occurs in complete tetraplegia, and the significant levels of circulating noradrenaline reported by others indicate this is also true in other parts of the body. This may explain the usual absence of severe, incapacitating, autonomic deficiency in this condition. Published by Elsevier Inc.

Rarefaction acceleration of ultrarelativistic magnetized jets in gamma-ray burst sources

NASA Astrophysics Data System (ADS)

Komissarov, Serguei S.; Vlahakis, Nektarios; Königl, Arieh

2010-09-01

When a magnetically dominated superfast-magnetosonic long/soft gamma-ray burst (GRB) jet leaves the progenitor star, the external pressure support will drop and the jet may enter the regime of ballistic expansion, during which additional magnetic acceleration becomes ineffective. However, recent numerical simulations by Tchekhovskoy et al. have suggested that the transition to this regime is accompanied by a spurt of acceleration. We confirm this finding numerically and attribute the acceleration to a sideways expansion of the jet, associated with a strong magnetosonic rarefaction wave that is driven into the jet when it loses pressure support, which induces a conversion of magnetic energy into kinetic energy of bulk motion. This mechanism, which we dub rarefaction acceleration, can only operate in a relativistic outflow because in this case the total energy can still be dominated by the magnetic component even in the superfast-magnetosonic regime. We analyse this process using the equations of relativistic magnetohydrodynamics and demonstrate that it is more efficient at converting internal energy into kinetic energy when the flow is magnetized than in a purely hydrodynamic outflow, as was found numerically by Mizuno et al. We show that, just as in the case of the magnetic acceleration of a collimating jet that is confined by an external pressure distribution - the collimation-acceleration mechanism - the rarefaction-acceleration process in a magnetized jet is a consequence of the fact that the separation between neighbouring magnetic flux surfaces increases faster than their cylindrical radius. However, whereas in the case of effective collimation-acceleration the product of the jet opening angle and its Lorentz factor does not exceed ~1, the addition of the rarefaction-acceleration mechanism makes it possible for this product to become >>1, in agreement with the inference from late-time panchromatic breaks in the afterglow light curves of long/soft GRBs.

Colloids and the Microcirculation.

PubMed

He, Huaiwu; Liu, Dawei; Ince, Can

2018-05-01

Colloid solutions have been advocated for use in treating hypovolemia due to their expected effect on improving intravascular retention compared with crystalloid solutions. Because the ultimate desired effect of fluid resuscitation is the improvement of microcirculatory perfusion and tissue oxygenation, it is of interest to study the effects of colloids and crystalloids at the level of microcirculation under conditions of shock and fluid resuscitation, and to explore the potential benefits of using colloids in terms of recruiting the microcirculation under conditions of hypovolemia. This article reviews the physiochemical properties of the various types of colloid solutions (eg, gelatin, dextrans, hydroxyethyl starches, and albumin) and the effects that they have under various conditions of hypovolemia in experimental and clinical scenarios.

Renovascular disease, microcirculation, and the progression of renal injury: role of angiogenesis

PubMed Central

2011-01-01

Emerging evidence supports the pivotal role of renal microvascular disease as a determinant of tubulo-interstitial and glomerular fibrosis in chronic kidney disease. An intact microcirculation is vital to restore blood flow to the injured tissues, which is a crucial step to achieve a successful repair response. The purpose of this review is to discuss the impact and mechanisms of the functional and structural changes of the renal microvascular network, as well as the role of these changes in the progression and irreversibility of renal injury. Damage of the renal microcirculation and deterioration of the angiogenic response may constitute early steps in the complex pathways involved in progressive renal injury. There is limited but provocative evidence that stimulation of vascular proliferation and repair may stabilize renal function and slow the progression of renal disease. The feasibility of novel potential therapeutic interventions for stabilizing the renal microvasculature is also discussed. Targeted interventions to enhance endogenous renoprotective mechanisms focused on the microcirculation, such as cell-based therapy or the use of angiogenic cytokines have shown promising results in some experimental and clinical settings. PMID:21307362

Partial Rarefaction as Way to Reduce Distortion Curve of double-glazed unit

NASA Astrophysics Data System (ADS)

Plotnikov, Alexander

2017-10-01

Use of Insulated Glass Units (IGU) as glazing on building façades causes optical distortions of mirrored images of neighboring buildings in glazed surfaces. Optical distortions are caused by varying distances between glass panes in IGUs as a result of climate factors. This paper examines available engineering solutions that reduce such distortions: use of more rigid outer glasses, encasing the building in a shell of single glass panes, known as the ‘double façade’, and use of vacuum IGUs. A new way is proposed to reduce optical distortions by installing additional pointed or linear supports and creating pre-stress with partial rarefaction inside the IGU. Overpressure that can cause IGU expansion and glass deformation was calculated. In the urban environment of Moscow, reduction of air pressure with simultaneous increase of air pressure inside the IGU during summer heat waves can be as high as 5%, and this figure determines the level of rarefaction.

Areal Mass Oscillations in Planar Targets Due to Feedout: Theory and Simulations.

NASA Astrophysics Data System (ADS)

Velikovich, A. L.; Schmitt, A. J.; Karasik, M.; Obenschain, S. P.; Serlin, V.; Pawley, C. J.; Gardner, J. H.; Aglitskiy, Y.; Metzler, N.

2001-10-01

When a planar shock wave breaks out at a rippled rear surface of a laser-driven target, the lateral pressure gradient in a rippled rarefaction wave propagating back to the front surface causes a lateral mass redistribution that reverses the phase of mass variation. If the driving laser pulse has no foot, then the RT growth, starting when the rarefaction wave reaches the front surface, causes the second phase reversal of mass variation, and continues at the initial phase, as consistently observed in feedout experiments on Nike. A foot of the laser pulse can cause an early phase reversal of mass variation, making the strong shock wave driven by the main pulse interact with a density variation in a rippled rarefaction wave rather than with static rear surface ripples. Theory and simulations predict that this interaction can make the phase of mass variation reverse one or three times. Then the phase of the RT growing mode would be opposite to that of the initial mass variation.

Rarefaction effects in microchannel gas flow driven by rhythmic wall contractions

NASA Astrophysics Data System (ADS)

Chatterjee, Krishnashis; Staples, Anne; Department of Biomedical Engineering; Mechanics, Virginia Tech Collaboration

2015-11-01

Current state of the art microfluidic devices employ precise and timely operation of a complex arrangement of micropumps and valves for fluid transport. A much more novel flow transport mechanism is found in entomological respiratory systems, which involve rhythmic wall contractions for driving the fluid flow. The practical viability of using this technique in future microfluidic devices has been studied earlier. The present study investigates the incorporation of rarefaction effects in the above model of microscale gas flow by including slip boundary conditions. The Navier Stokes equations for gas flow in rectangular microchannel are solved analytically with microscale and lubrication theory assumptions. First order slip boundary conditions are incorporated to account for the rarefaction effects. The dependence of fluid velocities and pressure gradient on the slip boundary conditions is studied. Time averaged unidirectional fluid flow rates are plotted for different phase lags between the contractions, with and without slip in order to obtain an optimum range under different conditions.

In Vitro Activation of eNOS by Mangifera indica (Careless™) and Determination of an Effective Dosage in a Randomized, Double-Blind, Human Pilot Study on Microcirculation.

PubMed

Gerstgrasser, Alexandra; Röchter, Sigrid; Dressler, Dirk; Schön, Christiane; Reule, Claudia; Buchwald-Werner, Sybille

2016-03-01

Mangifera indica fruit preparation (Careless™) activates the evolutionary conserved metabolic sensors sirtuin 1 and adenosine monophosphate-activated protein kinase, which have been identified as playing a key role in microcirculation and endothelial function. Here, an acute effect of a single dose of 100 mg or 300 mg Careless™ on microcirculation was investigated in a randomized, double-blind, crossover pilot study in ten healthy women to determine the effective dosage. Microcirculation and endothelial function were assessed by the Oxygen-to-see system and pulse amplitude tonometry (EndoPAT™), respectively. Cutaneous blood flow was increased over time by 100 mg (54% over pre-values, p = 0.0157) and 300 mg (35% over pre-value, p = 0.209) Careless™. The EndoPAT™ reactive hyperemia response was slightly improved 3 h after intake compared to pretesting with 300 mg Careless™. Furthermore, activation of endothelial nitric oxide synthase, as an important regulator for endothelial function, was tested in vitro in primary human umbilical vein endothelial cells. Careless™, after simulation of digestion, increased the activated form of endothelial nitric oxide synthase dose-dependently by 23% (300 µg/mL), 42% (1500 µg/mL), and 60% (3000 µg/mL) compared to the untreated control. In conclusion, the study suggests moderate beneficial effects of Careless™ on microcirculation, which is at least partly mediated by endothelial nitric oxide synthase activation. Georg Thieme Verlag KG Stuttgart · New York.

[Does autonomic diabetic neuropathy influence microcirculation reactivity in adolescents with diabetes type 1?].

PubMed

Urban, Mirosława; Peczyńska, Jadwiga; Kowalewski, Marek; Głowińska-Olszewska, Barbara

2007-01-01

Microcirculation is known to be disturbed in many organs of diabetic patients. Retinopathy, nephropathy and neuropathy might be considered as the cause of the functional and morphological changes at the level of microcirculation. The aim of the study was to assess by means of dynamic capillaroscopy the influence of autonomic diabetic nephropathy (CAN) in adolescents with type 1 diabetes mellitus on capillary blood flow (CBV) in skin microcirculation. The study group consisted of 18 patients with type 1 diabetes mellitus (mean age 15+/-2 years). In 9 of them the diagnosis of CAN was made on the basis of Ewing tests. The control group consisted of 10 healthy persons aged 15+/-1.5 years. CBV was measured in capillars of the nailfold of the fourth finger during rest and after 2 minutes of arterial occlusion (the occlusion pressure - above 20 mmHg systolic blood pressure - was obtained by the occlusion of brachial artery using sphygnomanometer cuff). The resting CBV did not differ between patients with CAN, without CAN and healthy controls (0.39+/-0.06, 0.41+0.05 i 0.42+/-0.07). The values of the peak CBV significantly differ between the examined groups (CAN: 0.75+0.1; without CAN: 0.86+/-0.11; control group: 0.98+/-0.09, p<0.01). The obtained results indicate that the presence of the autonomic diabetic neuropathy significantly influences the regulatory function of microcirculation, which may predispose to occurrence of different late diabetic complications.

In situ assessment of the renal microcirculation in mechanically ventilated rats using sidestream dark-field imaging.

PubMed

Astapenko, D; Jor, O; Lehmann, C; Cerny, V

2015-02-01

For microcirculation research there is a need for baseline data and feasibility protocols describing microcirculation of various organs. The aim of our study was to examine the reliability and reproducibility of sidestream dark-field (SDF) imaging within the renal cortical microcirculation in rats. Renal microcirculation was observed using SDF probe placed on the exposed renal surface via the upper midline laparotomy. Video sequences recorded intermittently in short apneic pauses were analyzed off-line by using AVA 3.0 software (MicroVision Medical, Amsterdam, the Netherlands). Results are expressed as mean (SD) or median (25-75% percentiles). We obtained 60 clear sequences from all recorded analyzable videos from all the animals. The total small vessel and all vessel density (in mm.mm(-2) ) were (28.79 ± 0.40) and (28.95 ± 0.40), respectively. The perfused small and all vessel density were (28.79 ± 0.40) and (28.95 ± 0.40), respectively. The DeBacker Score was (19.14 ± 0.43), the proportion of perfused vessels was 100% (100-100%) and the microvascular flow index was 3.49 (3-3.75). We conclude SDF imaging provides a reliable method to examine the renal microvascular bed in vivo and thus can be used for the study of the renal cortical vascular network in various experimental diseases models and clinical settings. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

In vivo microcirculation imaging of the sub surface fingertip using correlation mapping optical coherence tomography (cmOCT)

NASA Astrophysics Data System (ADS)

Dsouza, Roshan I.; Zam, Azhar; Subhash, Hrebesh M.; Larin, Kirill V.; Leahy, Martin

2013-02-01

We describe a novel application of correlation mapping optical coherence tomography (cmOCT) for sub-surface fingerprint biometric identification. Fingerprint biometrics including automated fingerprint identification systems, are commonly used to recognise the fingerprint, since they constitute simple, effective and valuable physical evidence. Spoofing of biometric fingerprint devices can be easily done because of the limited information obtained from the surface topography. In order to overcome this limitation a potentially more secure source of information is required for biometric identification applications. In this study, we retrieve the microcirculation map of the subsurface fingertip by use of the cmOCT technique. To increase probing depth of the sub surface microcirculation, an optical clearing agent composed of 75% glycerol in aqueous solution was applied topically and kept in contact for 15 min. OCT intensity images were acquired from commercial research grade swept source OCT system (model OCT1300SS, Thorlabs Inc. USA). A 3D OCT scan of the fingertip was acquired over an area of 5x5 mm using 1024x1024 A-scans in approximately 70 s. The resulting volume was then processed using the cmOCT technique with a 7x7 kernel to provide a microcirculation map. We believe these results will demonstrate an enhanced security level over artificial fingertips. To the best of our knowledge, this is the first demonstration of imaging microcirculation map of the subsurface fingertip.

[Comparison of bulbar conjunctival microcirculation in rabbits of five subtypes of blood stasis syndrome].

PubMed

Hu, Wen-Juan; Zhang, Bing-Tao; Wu, Rui

2013-09-01

To observe changes of bulbar conjunctival microcirculation in rabbits of five kinds subtypes of blood stasis syndrome (BSS), and to analyze their different properties. Totally 60 Japanese big-ear rabbits were randomly divided into six groups, i.e., qi deficiency blood stasis group, qi stagnation blood stasis group, cold coagulation blood stasis group, heat toxin blood stasis group, external injury blood stasis group, and the normal control group, 10 in each group. Changes of rabbit bulbar conjunctiva microcirculation were observed before and after modeling. Compared with the normal control group, the total integral of bulbar conjunctiva microcirculation obviously increased in the 5 BSS groups (P < 0.05). There was no statistical difference among the 5 BSS groups (P > 0.05). But there was statistical difference in any concrete integral among the 5 BSS groups (P < 0.05). Thickening blood vessels and errhysis of vascular walls were dominant in the heat toxin blood stasis group. Ischemia, partial cystic dilatation, vascular engorgement and twist were dominant in the qi deficiency blood stasis group. Partial vascular buckling, aneurysmal changes, flow velocity slowed down were dominant in the qi stagnation blood stasis group. Vascular buckling, hyperemia, vascular engorgement, blood flow slowed down were dominant in the external injury blood stasis group. Vascular buckling, ischemia, dark color were dominant in the cold coagulation blood stasis group. Changes of bulbar conjunctival microcirculation were different in 5 kinds of BSS types, which could reflect their various features.

Aging Exacerbates Obesity-induced Cerebromicrovascular Rarefaction, Neurovascular Uncoupling, and Cognitive Decline in Mice

PubMed Central

Tucsek, Zsuzsanna; Toth, Peter; Tarantini, Stefano; Sosnowska, Danuta; Gautam, Tripti; Warrington, Junie P.; Giles, Cory B.; Wren, Jonathan D.; Koller, Akos; Ballabh, Praveen; Sonntag, William E.; Csiszar, Anna

2014-01-01

Epidemiological studies show that obesity has deleterious effects on the brain and cognitive function in the elderly population. However, the specific mechanisms through which aging and obesity interact to promote cognitive decline remain unclear. To test the hypothesis that aging exacerbates obesity-induced cerebromicrovascular impairment, we compared young (7 months) and aged (24 months) high-fat diet–fed obese C57BL/6 mice. We found that aging exacerbates the obesity-induced decline in microvascular density both in the hippocampus and in the cortex. The extent of hippocampal microvascular rarefaction and the extent of impairment of hippocampal-dependent cognitive function positively correlate. Aging exacerbates obesity-induced loss of pericyte coverage on cerebral microvessels and alters hippocampal angiogenic gene expression signature, which likely contributes to microvascular rarefaction. Aging also exacerbates obesity-induced oxidative stress and induction of NADPH oxidase and impairs cerebral blood flow responses to whisker stimulation. Collectively, obesity exerts deleterious cerebrovascular effects in aged mice, promoting cerebromicrovascular rarefaction and neurovascular uncoupling. The morphological and functional impairment of the cerebral microvasculature in association with increased blood–brain barrier disruption and neuroinflammation (Tucsek Z, Toth P, Sosnowsk D, et al. Obesity in aging exacerbates blood–brain barrier disruption, neuroinflammation and oxidative stress in the mouse hippocampus: effects on expression of genes involved in beta-amyloid generation and Alzheimer’s disease. J Gerontol Biol Med Sci. 2013. In press, PMID: 24269929) likely contribute to obesity-induced cognitive decline in aging. PMID:24895269

[Minimal work-up for Raynaud syndrome: a consensus report. Microcirculation working group of the Société française de médecine vasculaire].

PubMed

Pistorius, M-A; Carpentier, P-H

2013-01-01

About ten to fifteen percent of the French population suffer from Raynaud's phenomenon. Most of the time, it is considered as primary Raynaud's phenomenon, without underlying disease. The aim of this expert consensus from the "microcirculation group" for the French Society of Vascular Medicine and the French Society for Microcirculation, was to define clinical guidelines in patients consulting for Raynaud's phenomenon. The recommended minimal screening includes clinical examination, nailfold capillaroscopy and antinuclear antibodies. In particular, the aim of this screening is to identify patients with a significant risk for scleroderma, who would need a careful follow up. Copyright © 2013. Published by Elsevier Masson SAS.

Impact of antibiotics on the microcirculation in local and systemic inflammation.

PubMed

Al-Banna, N A; Pavlovic, D; Gründling, M; Zhou, J; Kelly, M; Whynot, S; Hung, O; Johnston, B; Issekutz, T B; Kern, H; Cerny, V; Lehmann, Ch

2013-01-01

The main function of antibiotics is related to their capacity to eliminate a microorganism. In addition to the antimicrobial function of antibiotics, they are known to have anti-inflammatory and vasomodulatory effects on the microcirculation. The ability of non-antimicrobial derivatives of antibiotics to control inflammation illustrates the distinct anti-microbial and anti-inflammatory roles of antibiotics. In this review, we discuss the impact of antibiotics on leukocyte recruitment and the state of the microcirculation. Literature reporting the effect of antibiotics in non-infectious inflammatory conditions is reviewed as well as the studies demonstrating the anti-inflammatory effects of antibiotics in animal models of infection. In addition, the effect of the antibiotics on the immune system is summarized in this review, in order to postulate some mechanisms of action for the proand anti-inflammatory contribution of antibiotics. Literature reported the effect of antibiotics on the production of cytokines, chemotaxis and recruitment of leukocytes, production of reactive oxygen species, process of phagocytosis and autophagy, and apoptosis of leukocytes. Yet, all antibiotics may not necessarily exert an anti-inflammatory effect on the microcirculation. Thus, we suggest a model for spectrum of anti-inflammatory and vasomodulatory effects of antibiotics in the microcirculation of animals in local and systemic inflammation. Although the literature suggests the ability of antibiotics to modulate leukocyte recruitment and microperfusion, the process and the mechanism of action are not fully characterized. Studying this process will expand the knowledge base that is required for the selection of antibiotic treatment based on its anti-inflammatory functions, which might be particularly important for critically ill patients.

Ultra-high-sensitive optical micro-angiography provides depth resolved visualization of microcirculations within human skin under psoriatic conditions

NASA Astrophysics Data System (ADS)

Qin, Jia; An, Lin; Wang, Ruikang

2011-03-01

Adequate functioning of the peripheral micro vascular in human skin is necessary to maintain optimal tissue perfusion and preserve normal hemodynamic function. There is a growing body of evidence suggests that vascular abnormalities may directly related to several dermatologic diseases, such as psoriasis, port-wine stain, skin cancer, etc. New in vivo imaging modalities to aid volumetric microvascular blood perfusion imaging are there for highly desirable. To address this need, we demonstrate the capability of ultra-high sensitive optical micro angiography to allow blood flow visualization and quantification of vascular densities of lesional psoriasis area in human subject in vivo. The microcirculation networks of lesion and non-lesion skin were obtained after post processing the data sets captured by the system. With our image resolution (~20 μm), we could compare these two types of microcirculation networks both qualitatively and quantitatively. The B-scan (lateral or x direction) cross section images, en-face (x-y plane) images and the volumetric in vivo perfusion map of lesion and non-lesion skin areas were obtained using UHS-OMAG. Characteristic perfusion map features were identified between lesional and non-lesional skin area. A statistically significant difference between vascular densities of lesion and non-lesion skin area was also found using a histogram based analysis. UHS-OMAG has the potential to differentiate the normal skin microcirculation from abnormal human skin microcirculation non-invasively with high speed and sensitivity. The presented data demonstrates the great potential of UHS-OMAG for detecting and diagnosing skin disease such as psoriasis in human subjects.

Effects of a new piezoelectric device on periosteal microcirculation after subperiosteal preparation.

PubMed

Stoetzer, Marcus; Felgenträger, Dörthe; Kampmann, Andreas; Schumann, Paul; Rücker, Martin; Gellrich, Nils-Claudius; von See, Constantin

2014-07-01

Subperiosteal preparation using a periosteal elevator leads to disturbances of local periosteal microcirculation. Soft-tissue damage can usually be considerably reduced using piezoelectric technology. For this reason, we investigated the effects of a novel piezoelectric device on local periosteal microcirculation and compared this approach with the conventional preparation of the periosteum using a periosteal elevator. A total of 20 Lewis rats were randomly assigned to one of two groups. Subperiosteal preparation was performed using either a piezoelectric device or a periosteal elevator. Intravital microscopy was performed immediately after the procedure as well as three and eight days postoperatively. Statistical analysis of microcirculatory parameters was performed offline using analysis of variance (ANOVA) on ranks (p<0.05). At all time points investigated, intravital microscopy demonstrated significantly higher levels of periosteal perfusion in the group of rats that underwent piezosurgery than in the group of rats that underwent treatment with a periosteal elevator. The use of a piezoelectric device for subperiosteal preparation is associated with better periosteal microcirculation than the use of a conventional periosteal elevator. As a result, piezoelectric devices can be expected to have a positive effect on bone metabolism. Copyright © 2014 Elsevier Inc. All rights reserved.

Quantification of video-taped images in microcirculation research using inexpensive imaging software (Adobe Photoshop).

PubMed

Brunner, J; Krummenauer, F; Lehr, H A

2000-04-01

Study end-points in microcirculation research are usually video-taped images rather than numeric computer print-outs. Analysis of these video-taped images for the quantification of microcirculatory parameters usually requires computer-based image analysis systems. Most software programs for image analysis are custom-made, expensive, and limited in their applicability to selected parameters and study end-points. We demonstrate herein that an inexpensive, commercially available computer software (Adobe Photoshop), run on a Macintosh G3 computer with inbuilt graphic capture board provides versatile, easy to use tools for the quantification of digitized video images. Using images obtained by intravital fluorescence microscopy from the pre- and postischemic muscle microcirculation in the skinfold chamber model in hamsters, Photoshop allows simple and rapid quantification (i) of microvessel diameters, (ii) of the functional capillary density and (iii) of postischemic leakage of FITC-labeled high molecular weight dextran from postcapillary venules. We present evidence of the technical accuracy of the software tools and of a high degree of interobserver reliability. Inexpensive commercially available imaging programs (i.e., Adobe Photoshop) provide versatile tools for image analysis with a wide range of potential applications in microcirculation research.

A third-order moving mesh cell-centered scheme for one-dimensional elastic-plastic flows

NASA Astrophysics Data System (ADS)

Cheng, Jun-Bo; Huang, Weizhang; Jiang, Song; Tian, Baolin

2017-11-01

A third-order moving mesh cell-centered scheme without the remapping of physical variables is developed for the numerical solution of one-dimensional elastic-plastic flows with the Mie-Grüneisen equation of state, the Wilkins constitutive model, and the von Mises yielding criterion. The scheme combines the Lagrangian method with the MMPDE moving mesh method and adaptively moves the mesh to better resolve shock and other types of waves while preventing the mesh from crossing and tangling. It can be viewed as a direct arbitrarily Lagrangian-Eulerian method but can also be degenerated to a purely Lagrangian scheme. It treats the relative velocity of the fluid with respect to the mesh as constant in time between time steps, which allows high-order approximation of free boundaries. A time dependent scaling is used in the monitor function to avoid possible sudden movement of the mesh points due to the creation or diminishing of shock and rarefaction waves or the steepening of those waves. A two-rarefaction Riemann solver with elastic waves is employed to compute the Godunov values of the density, pressure, velocity, and deviatoric stress at cell interfaces. Numerical results are presented for three examples. The third-order convergence of the scheme and its ability to concentrate mesh points around shock and elastic rarefaction waves are demonstrated. The obtained numerical results are in good agreement with those in literature. The new scheme is also shown to be more accurate in resolving shock and rarefaction waves than an existing third-order cell-centered Lagrangian scheme.

Laser speckle contrast imaging of cerebral autoregulation in rats at a macro- and microcirculation level

NASA Astrophysics Data System (ADS)

Semyachkina-Glushkovskaya, O. V.; Abdurashitov, A. S.; Sindeev, S. S.; Tuchin, V. V.

2016-06-01

Using the method of laser speckle imaging for the simultaneous study of macro- and microcirculation in cerebral vessels of healthy rats, we show that the mechanisms underlying cerebral autoregulation depend on the initial condition of the organism and the sex of individual animals. The pharmacological dose-dependent stimulation of the peripheral arterial pressure increase is not accompanied by the cerebral circulation responses of analogous intensity, but manifests itself as 'compensating' reactions, namely, the redistribution of the blood flow at the level of macro- (in females) and microcirculation (in females and males). The obtained results extend our understanding of the capabilities of laser speckle imaging technique in neurophysiological studies of reserve abilities of cerebral circulation autoregulation under the conditions of hypertensive status formation.

Laser speckle-imaging of blood microcirculation in the brain cortex of laboratory rats in stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vilensky, M A; Semyachkina-Glushkovskaya, Oxana V; Timoshina, P A

2012-06-30

The results of experimental approbation of the method of laser full-field speckle-imaging for monitoring the changes in blood microcirculation state of the brain cortex of laboratory rats under the conditions of developing stroke and administration of vasodilating and vasoconstrictive agents are presented. The studies aimed at the choice of the optimal conditions of speckle-image formation and recording were performed and the software implementing an adaptive algorithm for processing the data of measurements was created. The transfer of laser radiation to the probed region of the biotissue was implemented by means of a silica-polymer optical fibre. The problems and prospects ofmore » speckle-imaging of cerebral microcirculation of blood in laboratory and clinical conditions are discussed.« less

Intravital Fluorescence Videomicroscopy to Study Tumor Angiogenesis and Microcirculation1

PubMed Central

Vajkoczy, Peter; Ullrich, Axel; Meager, Michael D

2000-01-01

Abstract Angiogenesis and microcirculation play a central role in growth and metastasis of human neoplasms, and, thus, represent a major target for novel treatment strategies. Mechanistic analysis of processes involved in tumor vascularization, however, requires sophisticated in vivo experimental models and techniques. Intravital microscopy allows direct assessment of tumor angiogenesis, microcirculation and overall perfusion. Its application to the study of tumor-induced neovascularization further provides information on molecular transport and delivery, intra- and extravascular cell-to-cell and cell-to-matrix interaction, as well as tumor oxygenation and metabolism. With the recent advances in the field of bioluminescence and fluorescent reporter genes, appropriate for in vivo imaging, the intravital fluorescent microscopic approach has to be considered a powerful tool to study microvascular, cellular and molecular mechanisms of tumor growth. PMID:10933068

The laser Doppler flowmeter for measuring microcirculation in human nasal mucosa.

PubMed

Olsson, P; Bende, M; Ohlin, P

1985-01-01

A new technique, based on the laser doppler principle, for measuring nasal mucosal microcirculation in humans, is presented. With this technique the relation between the blood flow and the temperature of the nasal mucosa was evaluated in healthy subjects exposed to peripheral cold stimulus. A decrease in blood flow and in mucosal temperature was found in all subjects when the feet were exposed to cold water for 5 min. The decrease in blood flow occurred almost momentarily and was restored to normal within the 5 min of exposure, while the drop in mucosal temperature was more gradual and persisted for a longer time. The implication of this study is that the laser doppler flowmeter seems to be a useful tool for estimation of changes in nasal mucosal microcirculation.

The rarefaction wave propagation in transparent windows

NASA Astrophysics Data System (ADS)

Glam, B.; Porat, E.; Horovitz, Y.; Yosef-Hai, A.

2017-01-01

The radial (lateral) rarefaction wave velocity of polymethyl methacrylate (PMMA) and Lithium Fluoride (LiF) windows were studied by plate impact experiments that were carried out at Soreq NRC up to a pressure of 146 kbar in the PMMA and 334 kbar in the LiF. The windows were glued to Lead targets that were impacted by a copper impactor. The VISAR measurement was done in the window interface with the target. This information was utilized to identify the radial rarefaction arrival time at the center of different diameter windows after the shock event, and served as a measurement to the radial wave velocity in the shocked material. It was found that for both windows, LiF or PMMA, the measured radial wave velocity increases with the pressure. Furthermore, this velocity is significantly higher compared to the expected longitudinal sound velocity at the same pressure, calculated by the Steinberg EOS in the PMMA and by ab initio calculation in the LiF. Here we present the experimental results and a comparison with analytical calculation of the sound velocity using the Steinberg EOS.

Vascular rarefaction mediates whitening of brown fat in obesity

PubMed Central

Shimizu, Ippei; Aprahamian, Tamar; Kikuchi, Ryosuke; Shimizu, Ayako; Papanicolaou, Kyriakos N.; MacLauchlan, Susan; Maruyama, Sonomi; Walsh, Kenneth

2014-01-01

Brown adipose tissue (BAT) is a highly vascularized organ with abundant mitochondria that produce heat through uncoupled respiration. Obesity is associated with a reduction of BAT function; however, it is unknown how obesity promotes dysfunctional BAT. Here, using a murine model of diet-induced obesity, we determined that obesity causes capillary rarefaction and functional hypoxia in BAT, leading to a BAT “whitening” phenotype that is characterized by mitochondrial dysfunction, lipid droplet accumulation, and decreased expression of Vegfa. Targeted deletion of Vegfa in adipose tissue of nonobese mice resulted in BAT whitening, supporting a role for decreased vascularity in obesity-associated BAT. Conversely, introduction of VEGF-A specifically into BAT of obese mice restored vascularity, ameliorated brown adipocyte dysfunction, and improved insulin sensitivity. The capillary rarefaction in BAT that was brought about by obesity or Vegfa ablation diminished β-adrenergic signaling, increased mitochondrial ROS production, and promoted mitophagy. These data indicate that overnutrition leads to the development of a hypoxic state in BAT, causing it to whiten through mitochondrial dysfunction and loss. Furthermore, these results link obesity-associated BAT whitening to impaired systemic glucose metabolism. PMID:24713652

Chronological changes in the eighth cranial nerve compound action potential (CAP) in experimental endolymphatic hydrops: the effects of altering the polarity of click sounds.

PubMed

Morizono, Tetsuo; Kondo, Tsuyoshi; Yamano, Takafumi; Miyagi, Morimichi; Shiraishi, Kimio

2009-02-01

Using a guinea pig model of experimental endolymphatic hydrops, click sounds of altered polarity showed different latencies and amplitudes in hydropic compared with normal cochleae. Latency changes appeared as early as 1 week after endolymphatic obstruction. This method can help diagnose endolymphatic hydrops. The goal of the study was to develop an objective electrophysiological diagnosis of endolymphatic hydrops. Endolymphatic hydrops were created surgically in guinea pigs. The latency and the amplitude of the eighth cranial nerve compound action potential (CAP) for click sounds of altered polarity were measured up to 8 weeks after the surgery. At early stages after surgery, the latency for condensation clicks became longer, and at later stages the latencies for both condensation and rarefaction became longer. The discrepancy in the latencies for rarefaction and condensation click sounds (rarefaction minus condensation) became larger by the first week after surgery, but no further discrepancy occurred thereafter. Compared with latency changes, amplitude changes in the CAP were rapid and progressive following surgery, suggesting ongoing damage to hair cells.

Rarefaction windows in a high-power impulse magnetron sputtering plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmucci, Maria; Britun, Nikolay; Konstantinidis, Stephanos

2013-09-21

The velocity distribution function of the sputtered particles in the direction parallel to the planar magnetron cathode is studied by spatially- and time-resolved laser-induced fluorescence spectroscopy in a short-duration (20 μs) high-power impulse magnetron sputtering discharge. The experimental evidence for the neutral and ionized sputtered particles to have a constant (saturated) velocity at the end of the plasma on-time is demonstrated. The velocity component parallel to the target surface reaches the values of about 5 km/s for Ti atoms and ions, which is higher that the values typically measured in the direct current sputtering discharges before. The results point outmore » on the presence of a strong gas rarefaction significantly reducing the sputtered particles energy dissipation during a certain time interval at the end of the plasma pulse, referred to as “rarefaction window” in this work. The obtained results agree with and essentially clarify the dynamics of HiPIMS discharge studied during the plasma off-time previously in the work: N. Britun, Appl. Phys. Lett. 99, 131504 (2011)« less

[The characteristics of the geroprotective action of magnetotherapy in elderly patients with combined cardiovascular pathology].

PubMed

Abramovich, S G; Fedotchenko, A A; Koriakina, A V; Pogodin, K V; Smirnov, S N

1999-01-01

Central hemodynamics, diastolic and pumping functions of the heart, myocardial reactivity, microcirculation and biological age of cardiovascular system were studied in 66 elderly patients suffering from hypertension and ischemic heart disease. The patients received systemic magnetotherapy which produced a geroprotective effect as shown by improved microcirculation, myocardial reactivity, central hemodynamics reducing biological age of cardiovascular system and inhibiting its ageing.

Paradoxical attenuation of leukocyte rolling in response to ischemia- reperfusion and extracorporeal blood circulation in inflamed tissue.

PubMed

Schäfer, Stephan C; Sehrt, Desiree N; Kamler, Markus; Jakob, Heinz; Lehr, Hans-Anton

2005-07-01

In contrast to acute preparations such as the exteriorized mesentery or the cremaster muscle, chronically instrumented chamber models allow one to study the microcirculation under "physiological" conditions, i.e., in the absence of trauma-induced leukocyte rolling along the venular endothelium. To underscore the importance of studying the naive microcirculation, we implanted titanium dorsal skinfold chambers in hamsters and used intravital fluorescence microscopy to study venular leukocyte rolling in response to ischemia-reperfusion injury or extracorporeal blood circulation. The experiments were performed in chambers that fulfilled all well-established criteria for a physiological microcirculation as well as in chambers that showed various extents of leukocyte rolling due to trauma, hemorrhage, or inflammation. In ideal chambers with a physiological microcirculation (<30 rolling leukocytes/mm vessel circumference in 30 s), ischemia-reperfusion injury and extracorporeal blood circulation significantly stimulated leukocyte rolling along the venular endothelium and, subsequently, firm leukocyte adhesion. In contrast, both stimuli failed to elicit leukocyte rolling in borderline chambers (30-100 leukocytes/mm), and in blatantly inflamed chambers with yet higher numbers of rolling leukocytes at baseline (>100 leukocytes/mm), we observed a paradoxical reduction of leukocyte rolling after ischemia-reperfusion injury or extracorporeal blood circulation. A similar effect was observed when we superfused leukotriene B4 (LTB4) onto the chamber tissue. The initial increase in leukocyte rolling in response to an LTB4 challenge was reversed by a second superfusion 90 min later. These observations underscore 1) the benefit of studying leukocyte-endothelial cell interaction in chronically instrumented chamber models and 2) the necessity to strictly adhere to well-established criteria of a physiological microcirculation.

Inhibition of glycogen synthase kinase (GSK)-3-β improves liver microcirculation and hepatocellular function after hemorrhagic shock.

PubMed

Jellestad, Lena; Fink, Tobias; Pradarutti, Sascha; Kubulus, Darius; Wolf, Beate; Bauer, Inge; Thiemermann, Chris; Rensing, Hauke

2014-02-05

Ischemia and reperfusion may cause liver injury and are characterized by hepatic microperfusion failure and a decreased hepatocellular function. Inhibition of glycogen synthase kinase (GSK)-3β, a serine-threonine kinase that has recently emerged as a key regulator in the modulation of the inflammatory response after stress events, may be protective in conditions like sepsis, inflammation and shock. Therefore, aim of the study was to assess the role of GSK-3β in liver microcirculation and hepatocellular function after hemorrhagic shock and resuscitation (H/R). Anesthetized male Sprague-Dawley rats underwent pretreatment with Ringer´s solution, vehicle (DMSO) or TDZD-8 (1 mg/kg), a selective GSK-3β inhibitor, 30 min before induction of hemorrhagic shock (mean arterial pressure 35±5 mmHg for 90 min) and were resuscitated with shed blood and Ringer´s solution (2h). 5h after resuscitation hepatic microcirculation was assessed by intravital microscopy. Propidium iodide (PI) positive cells, liver enzymes and alpha-GST were measured as indicators of hepatic injury. Liver function was estimated by assessment of indocyanine green plasma disappearance rate. H/R led to a significant decrease in sinusoidal diameters and impairment of liver function compared to sham operation. Furthermore, the number of PI positive cells in the liver as well as serum activities of liver enzymes and alpha-GST increased significantly after H/R. Pretreatment with TDZD-8 prevented the changes in liver microcirculation, hepatocellular injury and liver function after H/R. A significant rise in the plasma level of IL-10 was observed. Thus, inhibition of GSK-3β before hemorrhagic shock modulates the inflammatory response and improves hepatic microcirculation and hepatocellular function. Copyright © 2013 Elsevier B.V. All rights reserved.

Why Rudolph’s nose is red: observational study

PubMed Central

van Kuijen, Anne-Marije; Milstein, Dan M J; Yürük, Koray; Folkow, Lars P; Fokkens, Wytske J; Blix, Arnoldus S

2012-01-01

Objective To characterise the functional morphology of the nasal microcirculation in humans in comparison with reindeer as a means of testing the hypothesis that the luminous red nose of Rudolph, one of the most well known reindeer pulling Santa Claus’s sleigh, is due to the presence of a highly dense and rich nasal microcirculation. Design Observational study. Setting Tromsø, Norway (near the North Pole), and Amsterdam, the Netherlands. Participants Five healthy human volunteers, two adult reindeer, and a patient with grade 3 nasal polyposis. Main outcome measures Architecture of the microvasculature of the nasal septal mucosa and head of the inferior turbinates, kinetics of red blood cells, and real time reactivity of the microcirculation to topical medicines. Results Similarities between human and reindeer nasal microcirculation were uncovered. Hairpin-like capillaries in the reindeers’ nasal septal mucosa were rich in red blood cells, with a perfused vessel density of 20 (SD 0.7) mm/mm2. Scattered crypt or gland-like structures surrounded by capillaries containing flowing red blood cells were found in human and reindeer noses. In a healthy volunteer, nasal microvascular reactivity was demonstrated by the application of a local anaesthetic with vasoconstrictor activity, which resulted in direct cessation of capillary blood flow. Abnormal microvasculature was observed in the patient with nasal polyposis. Conclusions The nasal microcirculation of reindeer is richly vascularised, with a vascular density 25% higher than that in humans. These results highlight the intrinsic physiological properties of Rudolph’s legendary luminous red nose, which help to protect it from freezing during sleigh rides and to regulate the temperature of the reindeer’s brain, factors essential for flying reindeer pulling Santa Claus’s sleigh under extreme temperatures. PMID:23247980

Active nitric oxide produced in the red cell under hypoxic conditions by deoxyhemoglobin-mediated nitrite reduction.

PubMed

Nagababu, Enika; Ramasamy, Somasundaram; Abernethy, Darrell R; Rifkind, Joseph M

2003-11-21

Recent studies have generated a great deal of interest in a possible role for red blood cells in the transport of nitric oxide (NO) to the microcirculation and the vascular effect of this nitric oxide in facilitating the flow of blood through the microcirculation. Many questions have, however, been raised regarding such a mechanism. We have instead identified a completely new mechanism to explain the role of red cells in the delivery of NO to the microcirculation. This new mechanism results in the production of NO in the microcirculation where it is needed. Nitrite produced when NO reacts with oxygen in arterial blood is reutilized in the arterioles when the partial pressure of oxygen decreases and the deoxygenated hemoglobin formed reduces the nitrite regenerating NO. Nitrite reduction by hemoglobin results in a major fraction of the NO generated retained in the intermediate state where NO is bound to Hb(III) and in equilibrium with the nitrosonium cation bound to Hb(II). This pool of NO, unlike Hb(II)NO, is weakly bound and can be released from the heme. The instability of Hb(III)NO in oxygen and its displacement when flushed with argon requires that reliable determinations of red blood cell NO must be performed on freshly lysed samples without permitting the sample to be oxygenated. In fresh blood samples Hb(III)NO accounts for 75% of the red cell NO with appreciably higher values in venous blood than arterial blood. These findings confirm that nitrite reduction at reduced oxygen pressures is a major source for red cell NO. The formation and potential release from the red cell of this NO could have a major impact in regulating the flow of blood through the microcirculation.

Facial microcirculatory and biomechanical skin properties after single high energy (Er):YAG laser application.

PubMed

Medved, Fabian; Wurm, Antonia; Held, Manuel

2017-12-01

Owing to skin aging and the growing demand for skin rejuvenation, minimal invasive aesthetic treatments such as laser procedures are increasingly coming into focus. However, until now, little has been known about the objective effects of these procedures with respect to skin microcirculation or changes in skin elasticity. Facial skin rejuvenation was performed on 32 volunteers using ablative Erbium: YAG laser. Skin microcirculation and skin elasticity have then been evaluated objectively. Microcirculation (flow, SO 2 , velocity, and rHB) has been analyzed before and directly after the laser session by using the O2C device. Skin elasticity has been evaluated by using the Cutometer device (Uf, Ua, Ur, and Ue) before and directly after the laser treatment, as well as 1 week and then 1, 3, and 6 months post treatment. Further, the outcome for the volunteers regarding their satisfactory level after laser treatment was evaluated. Twenty volunteers were available for a complete follow-up. Microcirculation displayed statistically significant increase in all values to 2 mm depth. The biomechanical skin parameter of firmness of skin displayed statistically significant improvement in superficial skin layer after 6 months. Concerning microcirculation and skin elasticity the ablative Erbium: YAG laser treatment revealed similar effects on the skin like a superficial burn injury. In contrast to the determined skin elasticity parameters, firmness of skin objectively revealed a skin tightening effect after 6 months. Along with the important epidermal effect, the suitability of ablative laser treatment for skin rejuvenation has been proved in a long-term follow-up. Lasers Surg. Med. 49:891-898, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Impairment of skin blood flow during post-occlusive reactive hyperhemy assessed by laser Doppler flowmetry correlates with renal resistive index.

PubMed

Coulon, P; Constans, J; Gosse, P

2012-01-01

We lack non-invasive tools for evaluating the coronary and renal microcirculations. Since cutaneous Doppler laser exploration has evidenced impaired cutaneous microvascular responses in coronary artery disease and in impaired renal function, we wanted to find out if there was a link between the impairments in the cutaneous and renal microcirculations. To specify the significance of the rise in the renal resistive index (RI), which is still unclear, we also sought relations between RI and arterial stiffness. We conducted a cross-sectional controlled study in a heterogeneous population including hypertensive patients of various ages with or without a history of cardiovascular disease along with a healthy control group. The cutaneous microcirculation was evaluated by laser Doppler flowmetry of the post-occlusive reactive hyperhemy (PORH) and of the hyperhemy to heat. The renal microcirculation was evaluated by measurement of the RI. Arterial stiffness was evaluated from an ambulatory measurement of the corrected QKD(100-60) interval. We included 22 hypertensives and 11 controls of mean age 60.6 vs 40.8 years. In this population, there was a correlation between RI and basal zero to peak flow variation (BZ-PF) (r=-0.42; P=0.02) and a correlation between RI and rest flow to peak flow variation (RF-PF) (r=-0.44; P=0.01). There was also a significant correlation between RI and the corrected QKD(100-60) (r=-0.47; P=0.01). The significant correlation between PORH parameters and RI indicates that the functional modifications of the renal and cutaneous microcirculations tend to evolve in parallel during ageing or hypertension. The relation between RI and arterial stiffness shows that RI is a compound index of both renal microvascular impairment and the deterioration of macrovascular mechanics.

MuSIC report III: tumour microcirculation patterns and development of metastasis in long-term follow-up of melanocytic uveal tumours.

PubMed

Klingenstein, Annemarie; Schaumberger, Markus M; Freeman, William R; Folberg, Robert; Mueller, Arthur J; Schaller, Ulrich C

2016-03-01

To statistically determine differences in microcirculation patterns between nevi and uveal melanomas and the influence of these patterns on metastatic potential in the long-term follow-up of 112 patients with melanocytic uveal tumours. In vivo markers indicating malignancy and metastatic potential have implications for treatment decision. Primary diagnosis and work-up included clinical examination, fundus photography, standardized A and B scan echography as well as evaluation of tumour microcirculation patterns via confocal fluorescein and indocyanine green angiography (ICGA). Patient data were collected from the patient files, the tumour registry or personal contact. Statistical analysis was performed with spss 22.0 using chi-square, Fisher's exact test and Kaplan-Meier survival analysis. Forty-three uveal melanocytic lesions remained untreated and were retrospectively classified as benign nevi, whereas 69 lesions were malignant melanomas (T1: 32, T2: 28, T3: 6 and T4: 3). 'Silent' and 'arcs without branching' were found significantly more often in nevi (p = 0.001 and p = 0.010), whereas 'parallel with cross-linking' and 'networks' were significantly more frequent in melanomas (p = 0.022 and p = 0.029). The microcirculation pattern 'parallel with cross-linking' proved significantly more frequent in patients who developed metastases (p = 0.001). Certain microcirculation patterns may guide us in differentiating uveal nevi from malignant melanomas. A non-invasive prognostic marker can be of great value for borderline lesions in which cytology is less likely taken. 'Parallel with cross-linking' did not only indicate malignancy, but it was also associated with later tumour metastasis. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Evaluation of peripheral microcirculation improvement of foot after tarsal tunnel release in diabetic patients by transcutaneous oximetry.

PubMed

Trignano, Emilio; Fallico, Nefer; Chen, Hung-Chi; Faenza, Mario; Bolognini, Alfonso; Armenti, Andrea; Santanelli Di Pompeo, Fabio; Rubino, Corrado; Campus, Gian Vittorio

2016-01-01

According to recent studies, peripheral nerve decompression in diabetic patients seems to not only improve nerve function, but also to increase microcirculation; thus decreasing the incidence of diabetic foot wounds and amputations. However, while the postoperative improvement of nerve function is demonstrated, the changes in peripheral microcirculation have not been demonstrated yet. The aim of this study is to assess the degree of microcirculation improvement of foot after the tarsal tunnel release in the diabetic patients by using transcutaneous oximetry. Twenty diabetic male patients aged between 43 and 72 years old (mean age 61.2 years old) suffering from diabetic peripheral neuropathy with superimposed nerve compression underwent transcutaneous oximetry (PtcO2) before and after tarsal tunnel release by placing an electrode on the skin at the level of the dorsum of the foot. Eight lower extremities presented diabetic foot wound preoperatively. Thirty-six lower extremities underwent surgical release of the tibialis posterior nerve only, whereas four lower extremities underwent the combined release of common peroneal nerve, anterior tibialis nerve, and posterior tibialis nerve. Preoperative values of transcutaneous oximetry were below the critical threshold, that is, lower than 40 mmHg (29.1 ± 5.4 mmHg). PtcO2 values at one month after surgery (45.8 ± 6.4 mmHg) were significantly higher than the preoperative ones (P = 0.01). The results of postoperative increase in PtcO2 values demonstrate that the release of the tarsal tunnel determines a relevant increase in microcirculation in the feet of diabetic patients. © 2015 Wiley Periodicals, Inc.

The Effect of Aging on the Cutaneous Microvasculature

PubMed Central

Bentov, Itay; Reed, May J

2015-01-01

Aging is associated with a progressive loss of function in all organs. Under normal conditions the physiologic compensation for age-related deficits is sufficient, but during times of stress the limitations of this reserve become evident. Explanations for this reduction in reserve include the changes in the microcirculation that occur during the normal aging process. The microcirculation is defined as the blood flow through arterioles, capillaries and venules, which are the smallest vessels in the vasculature and are embedded within organs and tissues. Optimal strategies to maintain the microvasculature following surgery and other stressors must use multifactorial approaches. Using skin as the model organ, we will review the anatomical and functional changes in the microcirculation with aging, and some of the available clinical strategies to potentially mitigate the effect of these changes on important clinical outcomes. PMID:25917013

Wavelet-based analysis of gastric microcirculation in rats with ulcer bleedings

NASA Astrophysics Data System (ADS)

Pavlov, A. N.; Rodionov, M. A.; Pavlova, O. N.; Semyachkina-Glushkovskaya, O. V.; Berdnikova, V. A.; Kuznetsova, Ya. V.; Semyachkin-Glushkovskij, I. A.

2012-03-01

Studying of nitric oxide (NO) dependent mechanisms of regulation of microcirculation in a stomach can provide important diagnostic markers of the development of stress-induced ulcer bleedings. In this work we use a multiscale analysis based on the discrete wavelet-transform to characterize a latent stage of illness formation in rats. A higher sensitivity of stomach vessels to the NO-level in ill rats is discussed.

[Using combined magnetotherapy in patients with acne].

PubMed

Kul'chitskaia, D B; Orekhova, E M; Vasil'eva, E S

2004-01-01

Laser Doppler flowmetry discovered microcirculatory disorders in acne patients. Affected are arterioles as well as capillaries and venules. Combination of magnetotherapy with medication improves microcirculation in acne patients. More marked positive changes occurred in the microcirculatory system due to combined treatment compared to medication therapy only. Thus, laser Doppler flowmetry is a new, noninvasive method of assessing microcirculation in acne patients and can serve an objective criterion of treatment efficacy.

The effect of three different surgical techniques for colon anastomosis on regional postoperative microperfusion: Laser Doppler Flowmetry study in pigs.

PubMed

Kaska, Milan; Blazej, Slavomir; Turek, Zdenek; Ryska, Ales; Jegorov, Boris; Radochova, Vera; Bezouska, Jan; Paral, Jiri

2018-01-01

The optimal surgical approach to reconnecting bowel ends safely after resection is of great importance. This project is focused on assessment of the perianastomotic microcirculation quality in the short postoperative period when using three different anastomosis techniques in experimental animal. The experimental study involved 27 young female domestic pigs divided into three subgroups of 9 animals according to each surgical method of anastomosis construction in the sigmoid colon region: by manual suture, by stapler, or by gluing. Blood microcirculation in the anastomosis region was monitored using Laser Doppler Flowmetry (LDF). Anastomosis healing was evaluated by macroscopic and histological examination. Evaluation of the microcirculation in the anastomosis region showed the smallest decrease in perfusion values in animals reconstructed by suturing (Δ= -38.01%). A significantly more profound drop was observed postoperatively after stapling or gluing (Δ= -52.42% and Δ= -59.53%, respectively). All performed anastomoses healed without any signs of tissue and function pathology. Sewing, stapling, and gluing techniques for bowel anastomosis each have a different effect on regional microcirculation during 120 min. postoperatively. Nevertheless, the final results of anastomosis healing were found without of any pathology in all experimental animals managed by above mentioned anastomotic techniques.

TNF-α inhibition using etanercept prevents noise-induced hearing loss by improvement of cochlear blood flow in vivo.

PubMed

Arpornchayanon, Warangkana; Canis, Martin; Ihler, Friedrich; Settevendemie, Claudia; Strieth, Sebastian

2013-08-01

Exposure to loud noise can impair cochlear microcirculation and cause noise-induced hearing loss (NIHL). TNF-α signaling has been shown to be activated in NIHL and to control spiral modiolar artery vasoconstriction that regulates cochlear microcirculation. It was the aim of this experimental study to analyse the effects of the TNF-α inhibitor etanercept on cochlear microcirculation and hearing threshold shift in NIHL in vivo. After assessment of normacusis using ABR, loud noise (106 dB SPL, 30 minutes) was applied on both ears in guinea pigs. Etanercept was administered systemically after loud noise exposure while control animals received a saline solution. In vivo fluorescence microscopy of strial capillaries was performed after surgical exposure of the cochlea for microcirculatory analysis. ABR measurements were derived from the contralateral ear. Guinea pigs (n = 6, per group). Compared to controls, cochlear blood flow in strial capillary segments was significantly increased in etanercept-treated animals. Additionally, hearing threshold was preserved in animals receiving the TNF-α inhibitor in contrast to a significant threshold raising in controls. TNF-α inhibition using etanercept improves cochlear microcirculation and protects hearing levels after loud noise exposure and appears as a promising treatment strategy for human NIHL.

Disturbance of microcirculation due to unhealthy lifestyle: Cause of type 2 diabetes.

PubMed

Matsumoto, Yukihiro; Ohno, Hideki; Noguchi, Izumi; Kikuchi, Yuji; Kurihara, Takeshi

2006-01-01

Recently, type 2 diabetes seems to be increasing annually in all developed countries. The outcome of type 2 diabetes is often tragic due to succession of complications including renal disorders requiring hemodialysis, blindness, and limb amputation. The expenses for the care of diabetic patients are also a large burden on the society. These circumstances strongly indicate the necessity of prevention. For satisfactory prevention, the clarification of the etiology related to lifestyle is important, but it remains insufficient to date. In this paper, we present a hypothesis of the etiology of type 2 diabetes from the viewpoint of microcirculation. As mentioned later, an unhealthy lifestyle first causes disturbance of the microcirculation, and a portion of the blood is considered to bypass the capillaries via arteriovenous shunts. This prevents the delivery of glucose and insulin to cells of peripheral tissues, causing hyperglycemia unrelated to the cell insulin sensitivity or the endocrine state, i.e., apparent reduction of insulin sensitivity. Disturbance of the microcirculation also causes oxidative stress in peripheral tissues by inducing ischemia and hypoxia. This oxidative stress is considered to further exacerbate reduction of insulin sensitivity. This hypothesis is supported by the well-known fact that insulin sensitivity recovers with improvement in lifestyle including moderate exercise.

Endothelial sirtuin 1 inactivation enhances capillary rarefaction and fibrosis following kidney injury through Notch activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kida, Yujiro; Zullo, Joseph A.; Renal Research Institute, Department of Physiology, New York Medical College, Valhalla, NY

Peritubular capillary (PTC) rarefaction along with tissue fibrosis is a hallmark of chronic kidney disease (CKD). However, molecular mechanisms of PTC loss have been poorly understood. Previous studies have demonstrated that functional loss of endothelial sirtuin 1 (SIRT1) impairs angiogenesis during development and tissue damage. Here, we found that endothelial SIRT1 dysfunction causes activation of endothelial Notch1 signaling, which leads to PTC rarefaction and fibrosis following kidney injury. In mice lacking functional SIRT1 in the endothelium (Sirt1 mutant), kidney injury enhanced apoptosis and senescence of PTC endothelial cells with impaired endothelial proliferation and expanded myofibroblast population and collagen deposition. Comparedmore » to wild-type kidneys, Sirt1 mutant kidneys up-regulated expression of Delta-like 4 (DLL4, a potent Notch1 ligand), Hey1 and Hes1 (Notch target genes), and Notch intracellular domain-1 (NICD1, active form of Notch1) in microvascular endothelial cells (MVECs) post-injury. Sirt1 mutant primary kidney MVECs reduced motility and vascular assembly and enhanced senescence compared to wild-type kidney MVECs. This difference in the phenotype was negated with Notch inhibition. Concurrent stimulation of DLL4 and transforming growth factor (TGF)-β1 increased trans-differentiation of primary kidney pericytes into myofibroblast more than TGF-β1 treatment alone. Collectively, these results indicate that endothelial SIRT1 counteracts PTC rarefaction by repression of Notch1 signaling and antagonizes fibrosis via suppression of endothelial DLL4 expression. - Highlights: • SIRT1 represses Notch1 signaling in capillary endothelial cells in the kidney. • Endothelial SIRT1 is depleted in the kidney following injury. • Activation of endothelial Notch impairs angiogenesis in the kidney. • Increased expression of endothelial DLL4 enhances renal fibrosis.« less

Rarefaction-driven Rayleigh–Taylor instability. Part 1. Diffuse-interface linear stability measurements and theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, R. V.; Likhachev, O. A.; Jacobs, J. W.

Theory and experiments are reported that explore the behaviour of the Rayleigh–Taylor instability initiated with a diffuse interface. Experiments are performed in which an interface between two gases of differing density is made unstable by acceleration generated by a rarefaction wave. Well-controlled, diffuse, two-dimensional and three-dimensional, single-mode perturbations are generated by oscillating the gases either side to side, or vertically for the three-dimensional perturbations. The puncturing of a diaphragm separating a vacuum tank beneath the test section generates a rarefaction wave that travels upwards and accelerates the interface downwards. This rarefaction wave generates a large, but non-constant, acceleration of the order ofmore » $$1000g_{0}$$, where$$g_{0}$$is the acceleration due to gravity. Initial interface thicknesses are measured using a Rayleigh scattering diagnostic and the instability is visualized using planar laser-induced Mie scattering. Growth rates agree well with theoretical values, and with the inviscid, dynamic diffusion model of Duffet al. (Phys. Fluids, vol. 5, 1962, pp. 417–425) when diffusion thickness is accounted for, and the acceleration is weighted using inviscid Rayleigh–Taylor theory. The linear stability formulation of Chandrasekhar (Proc. Camb. Phil. Soc., vol. 51, 1955, pp. 162–178) is solved numerically with an error function diffusion profile using the Riccati method. This technique exhibits good agreement with the dynamic diffusion model of Duffet al. for small wavenumbers, but produces larger growth rates for large-wavenumber perturbations. Asymptotic analysis shows a$$1/k^{2}$$decay in growth rates as$$k\\rightarrow \\infty$$for large-wavenumber perturbations.« less

Rarefaction-driven Rayleigh–Taylor instability. Part 1. Diffuse-interface linear stability measurements and theory

DOE PAGES

Morgan, R. V.; Likhachev, O. A.; Jacobs, J. W.

2016-02-15

Theory and experiments are reported that explore the behaviour of the Rayleigh–Taylor instability initiated with a diffuse interface. Experiments are performed in which an interface between two gases of differing density is made unstable by acceleration generated by a rarefaction wave. Well-controlled, diffuse, two-dimensional and three-dimensional, single-mode perturbations are generated by oscillating the gases either side to side, or vertically for the three-dimensional perturbations. The puncturing of a diaphragm separating a vacuum tank beneath the test section generates a rarefaction wave that travels upwards and accelerates the interface downwards. This rarefaction wave generates a large, but non-constant, acceleration of the order ofmore » $$1000g_{0}$$, where$$g_{0}$$is the acceleration due to gravity. Initial interface thicknesses are measured using a Rayleigh scattering diagnostic and the instability is visualized using planar laser-induced Mie scattering. Growth rates agree well with theoretical values, and with the inviscid, dynamic diffusion model of Duffet al. (Phys. Fluids, vol. 5, 1962, pp. 417–425) when diffusion thickness is accounted for, and the acceleration is weighted using inviscid Rayleigh–Taylor theory. The linear stability formulation of Chandrasekhar (Proc. Camb. Phil. Soc., vol. 51, 1955, pp. 162–178) is solved numerically with an error function diffusion profile using the Riccati method. This technique exhibits good agreement with the dynamic diffusion model of Duffet al. for small wavenumbers, but produces larger growth rates for large-wavenumber perturbations. Asymptotic analysis shows a$$1/k^{2}$$decay in growth rates as$$k\\rightarrow \\infty$$for large-wavenumber perturbations.« less

Identification of capillary rarefaction using intracoronary wave intensity analysis with resultant prognostic implications for cardiac allograft patients.

PubMed

Broyd, Christopher J; Hernández-Pérez, Francisco; Segovia, Javier; Echavarría-Pinto, Mauro; Quirós-Carretero, Alicia; Salas, Clara; Gonzalo, Nieves; Jiménez-Quevedo, Pilar; Nombela-Franco, Luis; Salinas, Pablo; Núñez-Gil, Ivan; Del Trigo, Maria; Goicolea, Javier; Alonso-Pulpón, Luis; Fernández-Ortiz, Antonio; Parker, Kim; Hughes, Alun; Mayet, Jamil; Davies, Justin; Escaned, Javier

2018-05-21

Techniques for identifying specific microcirculatory structural changes are desirable. As such, capillary rarefaction constitutes one of the earliest changes of cardiac allograft vasculopathy (CAV) in cardiac allograft recipients, but its identification with coronary flow reserve (CFR) or intracoronary resistance measurements is hampered because of non-selective interrogation of the capillary bed. We therefore investigated the potential of wave intensity analysis (WIA) to assess capillary rarefaction and thereby predict CAV. Fifty-two allograft patients with unobstructed coronary arteries and normal left ventricular (LV) function were assessed. Adequate aortic pressure and left anterior descending artery flow measurements at rest and with intracoronary adenosine were obtained in 46 of which 2 were lost to follow-up. In a subgroup of 15 patients, simultaneous RV biopsies were obtained and analysed for capillary density. Patients were followed up with 1-3 yearly screening angiography. A significant relationship with capillary density was noted with CFR (r = 0.52, P = 0.048) and the backward decompression wave (BDW) (r = -0.65, P < 0.01). Over a mean follow-up of 9.3 ± 5.2 years patients with a smaller BDW had an increased risk of developing angiographic CAV (hazard ratio 2.89, 95% CI 1.12-7.39; P = 0.03). Additionally, the index BDW was lower in those who went on to have a clinical CAV-events (P = 0.04) as well as more severe disease (P = 0.01). Within cardiac transplant patients, WIA is able to quantify the earliest histological changes of CAV and can predict clinical and angiographic outcomes. This proof-of-concept for WIA also lends weight to its use in the assessment of other disease processes in which capillary rarefaction is involved.

Microvascular injury and the kidney in hypertension.

PubMed

Ruiz-Hurtado, G; Ruilope, L M

Renal macrocirculation participates in the development of arterial hypertension. The elevation in systemic blood pressure (BP) can damage the kidney starting in the microcirculation. Established arterial hypertension impinge upon the large arteries and stiffness develops. As a consequence central BP raises and BP pulsatility appear and contribute to further damage renal microcirculation by direct transmission of the elevated BP. Copyright © 2017 SEH-LELHA. Publicado por Elsevier España, S.L.U. All rights reserved.

Vasodilation by in vivo activation of astrocyte endfeet via two-photon calcium uncaging as a strategy to prevent brain ischemia

NASA Astrophysics Data System (ADS)

Chen, Yuanxin; Mancuso, James; Zhao, Zhen; Li, Xuping; Cheng, Jie; Roman, Gustavo; Wong, Stephen T. C.

2013-12-01

Decreased cerebral blood flow causes brain ischemia and plays an important role in the pathophysiology of many neurodegenerative diseases, including Alzheimer's disease and vascular dementia. In this study, we photomodulated astrocytes in the live animal by a combination of two-photon calcium uncaging in the astrocyte endfoot and in vivo imaging of neurovasculature and astrocytes by intravital two-photon microscopy after labeling with cell type specific fluorescent dyes. Our study demonstrates that photomodulation at the endfoot of a single astrocyte led to a 25% increase in the diameter of a neighboring arteriole, which is a crucial factor regulating cerebral microcirculation in downstream capillaries. Two-photon uncaging in the astrocyte soma or endfoot near veins does not show the same effect on microcirculation. These experimental results suggest that infrared photomodulation on astrocyte endfeet may be a strategy to increase cerebral local microcirculation and thus prevent brain ischemia.

[Value of condensation and rarefaction click evoked action potential latency difference in the diagnosis of Meniere's disease].

PubMed

Wang, Z; Shao, X; Yan, W; Lin, H

2000-06-01

To study the value of condensation and rarefaction clicks evoked action potential (AP) latency difference (LD) in diagnosis of Meniere's disease. AP was recorded with ECochG in controls (50 ears) and patients with Meniere's disease(90 ears) and sensorineural hearing loss(SNHL) of other origins(60 ears). LD was calculated and analyzed. LD in patients with Meniere's disease was (0.30 +/- 0.15) ms, which was significantly larger than that of controls(0.18 +/- 0.07) ms and of patients with SNHL of other origins(0.20 +/- 0.10) ms (P < 0.01). In the group of Meniere's disease, LD in patients with the mild and moderate hearing impairment was larger than those with severe hearing loss(P < 0.01) and LD in patients with low tone or high tone auditory sensation curve was larger than those with flat auditory sensation curve(P < 0.01). Positive rate was 4/60(6.7%) in other SNHL patients and 58/90(64.0%) in Meniere's disease group respectively. The increase in condensation and rarefaction click evoked AP latency difference can be an objective parameter in diagnosis of Meniere's disease.

The Decay of Stem Cell Nourishment at the Niche

PubMed Central

de Mora, Jaime Font

2013-01-01

Abstract One of the main features of human aging is the loss of adult stem cell homeostasis. Organs that are very dependent on adult stem cells show increased susceptibility to aging, particularly organs that present a vascular stem cell niche. Reduced regenerative capacity in tissues correlates with reduced stem cell function, which parallels a loss of microvascular density (rarefraction) and plasticity. Moreover, the age-related loss of microvascular plasticity and rarefaction has significance beyond metabolic support for tissues because stem cell niches are regulated co-ordinately with the vascular cells. In addition, microvascular rarefaction is related to increased inflammatory signals that may negatively regulate the stem cell population. Thus, the processes of microvascular rarefaction, adult stem cell dysfunction, and inflammation underlie the cycle of physiological decline that we call aging. Observations from new mouse models and humans are discussed here to support the vascular aging theory. We develop a novel theory to explain the complexity of aging in mammals and perhaps in other organisms. The connection between vascular endothelial tissue and organismal aging provides a potential evolutionary conserved mechanism that is an ideal target for the development of therapies to prevent or delay age-related processes in humans. PMID:23937078

Reshocks, rarefactions, and the generalized Layzer model for hydrodynamic instabilities

NASA Astrophysics Data System (ADS)

Mikaelian, Karnig O.

2009-02-01

We report numerical simulations and analytic modeling of shock tube experiments on Rayleigh-Taylor and Richtmyer-Meshkov instabilities. We examine single interfaces of the type A /B where the incident shock is initiated in A and the transmitted shock proceeds into B. Examples are He/air and air/He. In addition, we study finite-thickness or double-interface A /B/A configurations such as air/SF6/air gas-curtain experiments. We first consider conventional shock tubes that have a "fixed" boundary: A solid endwall which reflects the transmitted shock and reshocks the interface(s). Then we focus on new experiments with a "free" boundary—a membrane disrupted mechanically or by the transmitted shock, sending back a rarefaction toward the interface(s). Complex acceleration histories are achieved, relevant for inertial confinement fusion implosions. We compare our simulation results with a generalized Layzer model for two fluids with time-dependent densities and derive a new freeze-out condition whereby accelerating and compressive forces cancel each other out. Except for the recently reported failures of the Layzer model, the generalized Layzer model and hydrocode simulations for reshocks and rarefactions agree well with each other and remain to be verified experimentally.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verheest, Frank, E-mail: frank.verheest@ugent.be; School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000; Hellberg, Manfred A., E-mail: hellberg@ukzn.ac.za

The propagation of arbitrary amplitude electron-acoustic solitons and double layers is investigated in a plasma containing cold positive ions, cool adiabatic and hot isothermal electrons, with the retention of full inertial effects for all species. For analytical tractability, the resulting Sagdeev pseudopotential is expressed in terms of the hot electron density, rather than the electrostatic potential. The existence domains for Mach numbers and hot electron densities clearly show that both rarefactive and compressive solitons can exist. Soliton limitations come from the cool electron sonic point, followed by the hot electron sonic point, until a range of rarefactive double layers occurs.more » Increasing the relative cool electron density further yields a switch to compressive double layers, which ends when the model assumptions break down. These qualitative results are but little influenced by variations in compositional parameters. A comparison with a Boltzmann distribution for the hot electrons shows that only the cool electron sonic point limit remains, giving higher maximum Mach numbers but similar densities, and a restricted range in relative hot electron density before the model assumptions are exceeded. The Boltzmann distribution can reproduce neither the double layer solutions nor the switch in rarefactive/compressive character or negative/positive polarity.« less

On the interaction between turbulence and a planar rarefaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Bryan M.

2014-04-01

The modeling of turbulence, whether it be numerical or analytical, is a difficult challenge. Turbulence is amenable to analysis with linear theory if it is subject to rapid distortions, i.e., motions occurring on a timescale that is short compared to the timescale for nonlinear interactions. Such an approach (referred to as rapid distortion theory) could prove useful for understanding aspects of astrophysical turbulence, which is often subject to rapid distortions, such as supernova explosions or the free-fall associated with gravitational instability. As a proof of principle, a particularly simple problem is considered here: the evolution of vorticity due to amore » planar rarefaction in an ideal gas. Analytical solutions are obtained for incompressive modes having a wave vector perpendicular to the distortion; as in the case of gradient-driven instabilities, these are the modes that couple most strongly to the mean flow. Vorticity can either grow or decay in the wake of a rarefaction front, and there are two competing effects that determine which outcome occurs: entropy fluctuations couple to the mean pressure gradient to produce vorticity via baroclinic effects, whereas vorticity is damped due to the conservation of angular momentum as the fluid expands. Whether vorticity grows or decays depends upon the ratio of entropic to vortical fluctuations at the location of the front; growth occurs if this ratio is of order unity or larger. In the limit of purely entropic fluctuations in the ambient fluid, a strong rarefaction generates vorticity with a turbulent Mach number on the order of the rms of the ambient entropy fluctuations. The analytical results are shown to compare well with results from two- and three-dimensional numerical simulations. Analytical solutions are also derived in the linear regime of Reynolds-averaged turbulence models. This highlights an inconsistency in standard turbulence models that prevents them from accurately capturing the physics of rarefaction-turbulence interaction. In addition to providing physical insight, the solutions derived here can be used to verify algorithms of both the Reynolds-averaged and direct numerical simulation variety. Finally, dimensional analysis of the equations indicates that rapid distortion of turbulence can give rise to two distinct regimes in the turbulent spectrum: a distortion range at large scales where linear distortion effects dominate, and an inertial range at small scales where nonlinear effects dominate.« less

Effects of different cooling treatments on water diffusion, microcirculation, and water content within exercised muscles: evaluation by magnetic resonance T2-weighted and diffusion-weighted imaging.

PubMed

Yanagisawa, Osamu; Takahashi, Hideyuki; Fukubayashi, Toru

2010-09-01

In this study, we determined the effects of different cooling treatments on exercised muscles. Seven adults underwent four post-exercise treatments (20-min ice-bag application, 60-min gel-pack application at 10 degrees C and 17 degrees C, and non-cooling treatment) with at least 1 week between treatments. Magnetic resonance diffusion- and T2-weighted images were obtained to calculate the apparent diffusion coefficients (apparent diffusion coefficient 1, which reflects intramuscular water diffusion and microcirculation, and apparent diffusion coefficient 2, which is approximately equal to the true diffusion coefficient that excludes as much of the effect of intramuscular microcirculation as possible) and the T2 values (intramuscular water content level) of the ankle dorsiflexors, respectively, before and after ankle dorsiflexion exercise and after post-exercise treatment. The T2 values increased significantly after exercise and returned to pre-exercise values after each treatment; no significant differences were observed among the four post-exercise treatments. Both apparent diffusion coefficients also increased significantly after exercise and decreased significantly after the three cooling treatments; no significant difference was detected among the three cooling treatments. Local cooling suppresses both water diffusion and microcirculation within exercised muscles. Moreover, although the treatment time was longer, adequate cooling effects could be achieved using the gel-pack applications at relatively mild cooling temperatures.

Prototype of an in vitro model of the microcirculation.

PubMed

Shevkoplyas, Sergey S; Gifford, Sean C; Yoshida, Tatsuro; Bitensky, Mark W

2003-03-01

We have used microfabrication technology to construct a network of microchannels, patterned after the dimensions and architecture of the mammalian microcirculation. The network is cast in transparent silicone elastomer and the channels are coated with silanated mPEG to provide lubrication. Flow of red and white blood cells through the network is readily visualized by the use of high-speed digital image acquisition. The acquired sequences of high-quality images are used to calculate hematocrits and rates of red cell movement in the microchannels. Our prototype system has significant advantages over scaled-up room-size experimental systems in that it permits experimentation with actual human blood cells. Experiments can be carried out under well-controlled conditions in a network of microchannels with precisely known dimensions using cell suspensions of defined composition. Moreover, there is no need to counteract or anticipate the host's adaptive responses that may confound live animal experiments. Notwithstanding its limitations, the current prototype demonstrates certain features characteristic of the microcirculation, such as parachute and bullet shapes of red cells deformed in capillary channels, rouleaux formation, plasma skimming, and the utilization of collateral flow pathways due to flow obstruction caused by a white cell blocking a microchannel. We present this device as a prototype scale-to-scale model of the mammalian microcirculation. Limitations of the system as well as a variety of possible applications are described.

Decreased Reactivity of Skin Microcirculation in Response to l-Arginine in Later-Onset Type 1 Diabetes

PubMed Central

Neubauer-Geryk, Jolanta; Kozera, Grzegorz M.; Wolnik, Bogumil; Szczyrba, Sebastian; Nyka, Walenty M.; Bieniaszewski, Leszek

2013-01-01

OBJECTIVE The aim of our study was to evaluate the vasodilatory effect of l-arginine infusion on the skin microcirculation and to assess the relationship between this effect and the presence of microangiopathy in patients with type 1 diabetes. RESEARCH DESIGN AND METHODS Capillaroscopy was performed before and after l-arginine infusion in 48 diabetic patients (26 women and 22 men; age, 39.8 ± 6.3 years) and 24 volunteers free of any chronic disease (13 women and 11 men; age, 38.0 ± 6.7 years). The skin microcirculation reactivity, as expressed by the percentage of area covered by capillaries (coverage) and the distance between capillaries (distance), and the relationship between microcirculation reactivity and the presence of microangiopathic complications were assessed. RESULTS The distance before l-arginine infusion was significantly lower in patients than in controls (221 [153–311] vs. 240 [185–356] µm; P = 0.02) and did not differ after l-arginine infusion (223.5 [127–318] vs. 242.5 [181–341] µm; P = 0.27). The difference between the coverage values obtained before and after l-arginine infusion (Δcoverage) was significantly different from zero in the control group but not in the diabetes group. Patients with later onset of diabetes were characterized by decreased skin microcirculation reactivity when compared with patients with earlier onset of diabetes (−1.18 [−5.07 to 11.60] vs. 1.36 [−6.00 to 8.06]; P = 0.02) despite the higher prevalence of retinopathy in patients with earlier onset of diabetes (64% vs. 26%; P = 0.02). CONCLUSIONS Skin microvascular reactivity is impaired in patients with later onset of type 1 diabetes. Capillaroscopy with l-arginine infusion is useful for the identification of skin microangiopathy in type 1 diabetes. PMID:23150282

Effect of anti-vertigo granule on the opening number and blood flow of mouse ear capillary network

NASA Astrophysics Data System (ADS)

Li, Chongxian; Liu, Xiaobin; Li, Jun; Hao, Shaojun; Wang, Xidong; Li, Wenjun; Zhang, Zhengchen

2018-04-01

To observe the effects of anti-glare particles on the open number and blood flow in the auricle of mice with microcirculation disturbance model. Sixty mice, half male and half female, were randomly divided into 6 groups. The mice were given Kangxuan granule suspension, serum brain granule suspension and normal saline of the same volume, respectively, once a day. The mice were anesthetized by intraperitoneal injection of chloral hydrate at 1 hour after the last administration. The mouse was fixed on the observation platform and the auricle was placed on the transmission stage. BZ-2000 microcirculation microscope and microcirculation analysis system were used to observe the changes of blood velocity and capillary opening volume in auricle of mice before administration. The changes of blood velocity and capillaries opening volume of mouse auricle were observed 2 min after epinephrine injection into tail vein of mice. Bear fruit: Compared with those before epinephrine, the opening number of capillary reticulum of auricle in large dose Kangxuan granule group was significantly decreased (P<0.05), and in normal saline group and middle group. In the small dose Kangxuan granule group, the opening number of capillary network of auricle decreased significantly (P<0.01). Compared with the model group, the large dose Kangxuan granule group could significantly increase the opening number of the auricle capillary network in mice (P<0.01). Yangxuannao granule group could significantly increase the opening number of auricle capillary reticulum in mice (P<0.05), compared with the model group by Ridit test. Both Kangxuan granule group and Yangxuannao granule group could significantly improve the auricle hair of mice with microcirculation disorder. The blood flow in fine blood vessels (P<0.01). Kangxuan granule has a good effect on the opening number of capillary network of auricle and blood flow in mice with microcirculation disorder.

Endothelial dysfunction in the microcirculation of patients with obstructive sleep apnea.

PubMed

Patt, Brian T; Jarjoura, David; Haddad, Diane N; Sen, Chandan K; Roy, Sashwati; Flavahan, Nicholas A; Khayat, Rami N

2010-12-15

Obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease. We hypothesized that patients with OSA and no cardiovascular disease have oxidant-related microcirculatory endothelial dysfunction. To evaluate the microcirculation in OSA. This study included seven patients with OSA and seven age- and weight-matched control subjects (mean age, 38 yr; mean body mass index, 32.5 kg/m²). All participants were free of cardiovascular risk factors. Participants received measurement of brachial artery flow-mediated dilation and forearm subcutaneous biopsy. Patients underwent repeated tests 12 weeks after treatment. Microcirculatory endothelial cells were isolated, and immunohistochemistry staining for peroxynitrite in the microcirculation was performed. Flow-mediated dilation was lower in patients than in control subjects at baseline (mean ± SEM: 5.7 ± 0.5 vs. 9.5 ± 0.6; P = 0.02) and increased after treatment (5.7-7.3; change, 1.7 ± 0.6; P = 0.04). Microcirculatory peroxynitrite deposit was higher in patients compared with control subjects (44.0 ± 1.6 vs. 21.8 ± 1.9 stain density units; P < 0.001) and decreased after treatment from 44.0 to 30.5 stain density units (change, -13.5 ± 2.9; P = 0.009). In patients, transcription of endothelial nitric oxide synthase decreased from 5.2 to -1.3 after treatment (change, 6.5 ± 2.5; P = 0.05), and transcription of superoxide dismutase1 decreased from -4.0 to -12.3 after treatment (change, -8.3 ± 2.1; P = 0.01). These changes persisted after adjustment for weight and underlying severity of OSA. This is the first direct evaluation of the microcirculation in OSA. Patients with OSA with low cardiovascular risk status had increased oxidant production in the microcirculation and endothelial dysfunction, both of which improved with treatment. Endothelial nitric oxide synthase transcription decreased with treatment.

Endothelial Dysfunction in the Microcirculation of Patients with Obstructive Sleep Apnea

PubMed Central

Patt, Brian T.; Jarjoura, David; Haddad, Diane N.; Sen, Chandan K.; Roy, Sashwati; Flavahan, Nicholas A.; Khayat, Rami N.

2010-01-01

Rationale: Obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease. We hypothesized that patients with OSA and no cardiovascular disease have oxidant-related microcirculatory endothelial dysfunction. Objectives: To evaluate the microcirculation in OSA. Methods: This study included seven patients with OSA and seven age- and weight-matched control subjects (mean age, 38 yr; mean body mass index, 32.5 kg/m2). All participants were free of cardiovascular risk factors. Participants received measurement of brachial artery flow-mediated dilation and forearm subcutaneous biopsy. Patients underwent repeated tests 12 weeks after treatment. Microcirculatory endothelial cells were isolated, and immunohistochemistry staining for peroxynitrite in the microcirculation was performed. Measurements and Main Results: Flow-mediated dilation was lower in patients than in control subjects at baseline (mean ± SEM: 5.7 ± 0.5 vs. 9.5 ± 0.6; P = 0.02) and increased after treatment (5.7–7.3; change, 1.7 ± 0.6; P = 0.04). Microcirculatory peroxynitrite deposit was higher in patients compared with control subjects (44.0 ± 1.6 vs. 21.8 ± 1.9 stain density units; P < 0.001) and decreased after treatment from 44.0 to 30.5 stain density units (change, −13.5 ± 2.9; P = 0.009). In patients, transcription of endothelial nitric oxide synthase decreased from 5.2 to −1.3 after treatment (change, 6.5 ± 2.5; P = 0.05), and transcription of superoxide dismutase1 decreased from −4.0 to −12.3 after treatment (change, −8.3 ± 2.1; P = 0.01). These changes persisted after adjustment for weight and underlying severity of OSA. Conclusions: This is the first direct evaluation of the microcirculation in OSA. Patients with OSA with low cardiovascular risk status had increased oxidant production in the microcirculation and endothelial dysfunction, both of which improved with treatment. Endothelial nitric oxide synthase transcription decreased with treatment. PMID:20656942

ACh-induced endothelial NO synthase translocation, NO release and vasodilatation in the hamster microcirculation in vivo

PubMed Central

Figueroa, Xavier F; González, Daniel R; Martínez, Agustín D; Durán, Walter N; Boric, Mauricio P

2002-01-01

Studies in cultured cells show that activation of endothelial nitric oxide (NO) synthase (eNOS) requires the dissociation of this enzyme from its inhibitory association with caveolin-1 (Cav-1), and perhaps its translocation from plasma membrane caveolae to other cellular compartments. We investigated the hypothesis that in vivo NO-dependent vasodilatation is associated with the translocation of eNOS from the cell membrane. To this end, we applied ACh topically (10-100 μm for 10 min) to the hamster cheek pouch microcirculation and measured NO production, blood flow and vessel diameter, and assessed subcellular eNOS distribution by Western blotting. Baseline NO production was 54.4 ± 5.2 pmol min−1 (n = 16). ACh increased NO release, caused arteriolar and venular dilatation and elevated microvascular flow. These responses were inhibited by NG-nitro-L-arginine (30 μm). The maximal increase in NO production induced by 10 μm and 100 μm ACh was 45 ± 20 % and 111 ± 33 %, respectively; the corresponding blood flow increases were 50 ± 10 % and 130 ± 24 %, respectively (n = 4-6). Both responses followed a similar time course, although increases in NO preceded flow changes. In non-stimulated tissues, eNOS was distributed mainly in the microsomal fraction. ACh-induced vasodilatation was associated with eNOS translocation to the cytosolic and Golgi-enriched fractions. After 1.5, 3.0 or 6.0 min of application, 10 μm ACh decreased the level of membrane-bound eNOS by -13 ± 4 %, -60 ± 4 % and -19 ± 17 %, respectively; at the same time points, 100 μm ACh reduced microsomal eNOS content by -38 ± 9 %, -61 ± 16 % and -40 ± 18 %, respectively (n = 4-5). In all cases, microsomal Cav-1 content did not change. The close ACh concentration dependence and the concomitance between eNOS subcellular redistribution and NO release support the concept that eNOS translocation from the plasma membrane is part of an activation mechanism that induces NO-dependent vasodilatation in vivo. PMID:12411531

Expanding the UniFrac Toolbox

PubMed Central

2016-01-01

The UniFrac distance metric is often used to separate groups in microbiome analysis, but requires a constant sequencing depth to work properly. Here we demonstrate that unweighted UniFrac is highly sensitive to rarefaction instance and to sequencing depth in uniform data sets with no clear structure or separation between groups. We show that this arises because of subcompositional effects. We introduce information UniFrac and ratio UniFrac, two new weightings that are not as sensitive to rarefaction and allow greater separation of outliers than classic unweighted and weighted UniFrac. With this expansion of the UniFrac toolbox, we hope to empower researchers to extract more varied information from their data. PMID:27632205

Comparison of an automatic analysis and a manual analysis of conjunctival microcirculation in a sheep model of haemorrhagic shock.

PubMed

Arnemann, Philip-Helge; Hessler, Michael; Kampmeier, Tim; Morelli, Andrea; Van Aken, Hugo Karel; Westphal, Martin; Rehberg, Sebastian; Ertmer, Christian

2016-12-01

Life-threatening diseases of critically ill patients are known to derange microcirculation. Automatic analysis of microcirculation would provide a bedside diagnostic tool for microcirculatory disorders and allow immediate therapeutic decisions based upon microcirculation analysis. After induction of general anaesthesia and instrumentation for haemodynamic monitoring, haemorrhagic shock was induced in ten female sheep by stepwise blood withdrawal of 3 × 10 mL per kilogram body weight. Before and after the induction of haemorrhagic shock, haemodynamic variables, samples for blood gas analysis, and videos of conjunctival microcirculation were obtained by incident dark field illumination microscopy. Microcirculatory videos were analysed (1) manually with AVA software version 3.2 by an experienced user and (2) automatically by AVA software version 4.2 for total vessel density (TVD), perfused vessel density (PVD) and proportion of perfused vessels (PPV). Correlation between the two analysis methods was examined by intraclass correlation coefficient and Bland-Altman analysis. The induction of haemorrhagic shock decreased the mean arterial pressure (from 87 ± 11 to 40 ± 7 mmHg; p < 0.001); stroke volume index (from 38 ± 14 to 20 ± 5 ml·m -2 ; p = 0.001) and cardiac index (from 2.9 ± 0.9 to 1.8 ± 0.5 L·min -1 ·m -2 ; p < 0.001) and increased the heart rate (from 72 ± 9 to 87 ± 11 bpm; p < 0.001) and lactate concentration (from 0.9 ± 0.3 to 2.0 ± 0.6 mmol·L -1 ; p = 0.001). Manual analysis showed no change in TVD (17.8 ± 4.2 to 17.8 ± 3.8 mm*mm -2 ; p = 0.993), whereas PVD (from 15.6 ± 4.6 to 11.5 ± 6.5 mm*mm -2 ; p = 0.041) and PPV (from 85.9 ± 11.8 to 62.7 ± 29.6%; p = 0.017) decreased significantly. Automatic analysis was not able to identify these changes. Correlation analysis showed a poor correlation between the analysis methods and a wide spread of values in Bland-Altman analysis. As characteristic changes in microcirculation during ovine haemorrhagic shock were not detected by automatic analysis and correlation between automatic and manual analyses (current gold standard) was poor, the use of the investigated software for automatic analysis of microcirculation cannot be recommended in its current version at least in the investigated model. Further improvements in automatic vessel detection are needed before its routine use.

PIC simulation of a thermal anisotropy-driven Weibel instability in a circular rarefaction wave

NASA Astrophysics Data System (ADS)

Dieckmann, M. E.; Sarri, G.; Murphy, G. C.; Bret, A.; Romagnani, L.; Kourakis, I.; Borghesi, M.; Ynnerman, A.; O'C Drury, L.

2012-02-01

The expansion of an initially unmagnetized planar rarefaction wave has recently been shown to trigger a thermal anisotropy-driven Weibel instability (TAWI), which can generate magnetic fields from noise levels. It is examined here whether the TAWI can also grow in a curved rarefaction wave. The expansion of an initially unmagnetized circular plasma cloud, which consists of protons and hot electrons, into a vacuum is modelled for this purpose with a two-dimensional particle-in-cell (PIC) simulation. It is shown that the momentum transfer from the electrons to the radially accelerating protons can indeed trigger a TAWI. Radial current channels form and the aperiodic growth of a magnetowave is observed, which has a magnetic field that is oriented orthogonal to the simulation plane. The induced electric field implies that the electron density gradient is no longer parallel to the electric field. Evidence is presented here that this electric field modification triggers a second magnetic instability, which results in a rotational low-frequency magnetowave. The relevance of the TAWI is discussed for the growth of small-scale magnetic fields in astrophysical environments, which are needed to explain the electromagnetic emissions by astrophysical jets. It is outlined how this instability could be examined experimentally.

Implosion of Cylindrical Cavities via Short Duration Impulsive Loading

NASA Astrophysics Data System (ADS)

Huneault, Justin; Higgins, Andrew

2014-11-01

An apparatus has been developed to study the collapse of a cylindrical cavity in gelatin subjected to a symmetric impact-driven impulsive loading. A gas-driven annular projectile is accelerated to approximately 50 m/s, at which point it impacts a gelatin casting confined by curved steel surfaces that allow a transition from an annular geometry to a cylindrically imploding motion. The implosion is visualized by a high-speed camera through a window which forms the top confining wall of the implosion cavity. The initial size of the cavity is such that the gelatin wall is two to five times thicker than the impacting projectile. Thus, during impact the compression wave which travels towards the cavity is closely followed by a rarefaction resulting from the free surface reflection of the compression wave in the projectile. As the compression wave in the gelatin reaches the inner surface, it will also reflect as a rarefaction wave. The interaction between the rarefaction waves from the gelatin and projectile free surfaces leads to large tensile stresses resulting in the spallation of a relatively thin shell. The study focuses on the effect of impact parameters on the thickness and uniformity of the imploding shell formed by the cavitation in the imploding gelatin cylinder.

Numerical investigation of rarefaction effects in the vicinity of a sharp leading edge

NASA Astrophysics Data System (ADS)

Pan, Shaowu; Gao, Zhenxun; Lee, Chunhian

2014-12-01

This paper presents a study of rarefaction effect on hypersonic flow over a sharp leading edge. Both continuum approach and kinetic method: a widely spread commercial Computational Fluid Dynamics-Navior-Stokes-Fourier (CFD-NSF) software - Fluent together with a direct simulation Monte Carlo (DSMC) code developed by the authors are employed for simulation of transition regime with Knudsen number ranging from 0.005 to 0.2. It is found that Fluent can predict the wall fluxes in the case of hypersonic argon flow over the sharp leading edge for the lowest Kn case (Kn = 0.005) in current paper while for other cases it also has a good agreement with DSMC except at the location near the sharp leading edge. Among all of the wall fluxes, it is found that coefficient of pressure is the most sensitive to rarefaction while heat transfer is the least one. A parameter based on translational nonequilibrium and a cut-off value of 0.34 is proposed for continuum breakdown in this paper. The structure of entropy and velocity profile in boundary layer is analyzed. Also, it is found that the ratio of heat transfer coefficient to skin friction coefficient remains uniform along the surface for the four cases in this paper.

2-D Model for Normal and Sickle Cell Blood Microcirculation

NASA Astrophysics Data System (ADS)

Tekleab, Yonatan; Harris, Wesley

2011-11-01

Sickle cell disease (SCD) is a genetic disorder that alters the red blood cell (RBC) structure and function such that hemoglobin (Hb) cannot effectively bind and release oxygen. Previous computational models have been designed to study the microcirculation for insight into blood disorders such as SCD. Our novel 2-D computational model represents a fast, time efficient method developed to analyze flow dynamics, O2 diffusion, and cell deformation in the microcirculation. The model uses a finite difference, Crank-Nicholson scheme to compute the flow and O2 concentration, and the level set computational method to advect the RBC membrane on a staggered grid. Several sets of initial and boundary conditions were tested. Simulation data indicate a few parameters to be significant in the perturbation of the blood flow and O2 concentration profiles. Specifically, the Hill coefficient, arterial O2 partial pressure, O2 partial pressure at 50% Hb saturation, and cell membrane stiffness are significant factors. Results were found to be consistent with those of Le Floch [2010] and Secomb [2006].

Simulations of the Microcirculation in the Human Conjunctiva

NASA Astrophysics Data System (ADS)

Dow, William; Jacobitz, Frank; Chen, Peter

2012-11-01

The microcirculation in the conjunctiva of a healthy human subject is analyzed using a simulation approach. A comparison between healthy and diseased states may lead to early diagnosis for a variety of vascular related disorders. Previous work suggests that hypertension, arteriosclerosis, and diabetes mellitus have noticeable very early changes in the microvasculature (Davis and Landau, 1957; Ditzel, 1968; Kunitomo, 1974) and the vessels of the conjunctiva are specifically useful for this research because they can be studied non-invasively. The microcirculation in the conjunctiva has been documented over the course of disease treatments, providing both still images and video footage for information on vessel length, diameter, and connectivity as well as the direction of blood flow. The numerical method is based on a Hagen-Poiseuille balance in the microvessels and a sparse matrix solver is used to obtain the solution. The simulations use realistic vessel topology for the microvasculature, reconstructed from microscope images of tissue samples, and consider blood rheology as well as passive and active vessel properties.

A new fluorescent imaging procedure in vivo for evaluation of the retinal microcirculation in rats.

PubMed

Kimura, H; Kiryu, J; Nishiwaki, H; Ogura, Y

1995-03-01

We investigated a new method for in vivo evaluation of the retinal microcirculation in rats using a cell-permeant fluorescent dye, acridine orange (AO), which stains cell nuclei and cytoplasm, and a scanning laser ophthalmoscope (SLO). AO, which binds and interacts with DNA and RNA, and thus stains cell nuclei and cytoplasm, was administered intravenously to rats. Fluorescein angiography was performed after administration of the AO, and fundus images were recorded on S-VHS videotape by means of an SLO. Argon laser was used as an exciter of the dye. The retinal vessels were stained with the dye, rendering the retinal microvasculature clearly visible. Cell nuclei and vessel walls were observed as greater fluorescence and lesser fluorescence, respectively. Leukocytes were also observed as highly fluorescent dots moving through the vessels. The results suggest that SLO visualization of AO uptake by cells may be a useful procedure for the evaluation of retinal microcirculation in vivo in rats.

High sensitive volumetric imaging of renal microcirculation in vivo using ultrahigh sensitive optical microangiography

NASA Astrophysics Data System (ADS)

Zhi, Zhongwei; Jung, Yeongri; Jia, Yali; An, Lin; Wang, Ruikang K.

2011-03-01

We present a non-invasive, label-free imaging technique called Ultrahigh Sensitive Optical Microangiography (UHSOMAG) for high sensitive volumetric imaging of renal microcirculation. The UHS-OMAG imaging system is based on spectral domain optical coherence tomography (SD-OCT), which uses a 47000 A-line scan rate CCD camera to perform an imaging speed of 150 frames per second that takes only ~7 seconds to acquire a 3D image. The technique, capable of measuring slow blood flow down to 4 um/s, is sensitive enough to image capillary networks, such as peritubular capillaries and glomerulus within renal cortex. We show superior performance of UHS-OMAG in providing depthresolved volumetric images of rich renal microcirculation. We monitored the dynamics of renal microvasculature during renal ischemia and reperfusion. Obvious reduction of renal microvascular density due to renal ischemia was visualized and quantitatively analyzed. This technique can be helpful for the assessment of chronic kidney disease (CKD) which relates to abnormal microvasculature.

Blood flow and blood cell interactions and migration in microvessels

NASA Astrophysics Data System (ADS)

Fedosov, Dmitry; Fornleitner, Julia; Gompper, Gerhard

2011-11-01

Blood flow in microcirculation plays a fundamental role in a wide range of physiological processes and pathologies in the organism. To understand and, if necessary, manipulate the course of these processes it is essential to investigate blood flow under realistic conditions including deformability of blood cells, their interactions, and behavior in the complex microvascular network which is characteristic for the microcirculation. We employ the Dissipative Particle Dynamics method to model blood as a suspension of deformable cells represented by a viscoelastic spring-network which incorporates appropriate mechanical and rheological cell-membrane properties. Blood flow is investigated in idealized geometries. In particular, migration of blood cells and their distribution in blood flow are studied with respect to various conditions such as hematocrit, flow rate, red blood cell aggregation. Physical mechanisms which govern cell migration in microcirculation and, in particular, margination of white blood cells towards the vessel wall, will be discussed. In addition, we characterize blood flow dynamics and quantify hemodynamic resistance. D.F. acknowledges the Humboldt Foundation for financial support.

Nitric oxide bioavailability in the microcirculation: insights from mathematical models.

PubMed

Tsoukias, Nikolaos M

2008-11-01

Over the last 30 years nitric oxide (NO) has emerged as a key signaling molecule involved in a number of physiological functions, including in the regulation of microcirculatory tone. Despite significant scientific contributions, fundamental questions about NO's role in the microcirculation remain unanswered. Mathematical modeling can assist in investigations of microcirculatory NO physiology and address experimental limitations in quantifying vascular NO concentrations. The number of mathematical models investigating the fate of NO in the vasculature has increased over the last few years, and new models are continuously emerging, incorporating an increasing level of complexity and detail. Models investigate mechanisms that affect NO availability in health and disease. They examine the significance of NO release from nonendothelial sources, the effect of transient release, and the complex interaction of NO with other substances, such as heme-containing proteins and reactive oxygen species. Models are utilized to test and generate hypotheses for the mechanisms that regulate NO-dependent signaling in the microcirculation.

Repeatability of Bolus Kinetics Ultrasound Perfusion Imaging for the Quantification of Cerebral Blood Flow.

PubMed

Vinke, Elisabeth J; Eyding, Jens; de Korte, Chris L; Slump, Cornelis H; van der Hoeven, Johannes G; Hoedemaekers, Cornelia W E

2017-12-01

Ultrasound perfusion imaging (UPI) can be used for the quantification of cerebral perfusion. In a neuro-intensive care setting, repeated measurements are required to evaluate changes in cerebral perfusion and monitor therapy. The aim of this study was to determine the repeatability of UPI in quantification of cerebral perfusion. UPI measurement of cerebral perfusion was performed three times in healthy patients. The coefficients of variation of the three bolus injections were calculated for both time- and volume-derived perfusion parameters in the macro- and microcirculation. The UPI time-dependent parameters had overall the lowest CVs in both the macro- and microcirculation. The volume-related parameters had poorer repeatability, especially in the microcirculation. Both intra-observer variability and inter-observer variability were low. Although UPI is a promising tool for the bedside measurement of cerebral perfusion, improvement of the technique is required before implementation in routine clinical practice. Copyright © 2017 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.

Evaluation of species richness estimators based on quantitative performance measures and sensitivity to patchiness and sample grain size

NASA Astrophysics Data System (ADS)

Willie, Jacob; Petre, Charles-Albert; Tagg, Nikki; Lens, Luc

2012-11-01

Data from forest herbaceous plants in a site of known species richness in Cameroon were used to test the performance of rarefaction and eight species richness estimators (ACE, ICE, Chao1, Chao2, Jack1, Jack2, Bootstrap and MM). Bias, accuracy, precision and sensitivity to patchiness and sample grain size were the evaluation criteria. An evaluation of the effects of sampling effort and patchiness on diversity estimation is also provided. Stems were identified and counted in linear series of 1-m2 contiguous square plots distributed in six habitat types. Initially, 500 plots were sampled in each habitat type. The sampling process was monitored using rarefaction and a set of richness estimator curves. Curves from the first dataset suggested adequate sampling in riparian forest only. Additional plots ranging from 523 to 2143 were subsequently added in the undersampled habitats until most of the curves stabilized. Jack1 and ICE, the non-parametric richness estimators, performed better, being more accurate and less sensitive to patchiness and sample grain size, and significantly reducing biases that could not be detected by rarefaction and other estimators. This study confirms the usefulness of non-parametric incidence-based estimators, and recommends Jack1 or ICE alongside rarefaction while describing taxon richness and comparing results across areas sampled using similar or different grain sizes. As patchiness varied across habitat types, accurate estimations of diversity did not require the same number of plots. The number of samples needed to fully capture diversity is not necessarily the same across habitats, and can only be known when taxon sampling curves have indicated adequate sampling. Differences in observed species richness between habitats were generally due to differences in patchiness, except between two habitats where they resulted from differences in abundance. We suggest that communities should first be sampled thoroughly using appropriate taxon sampling curves before explaining differences in diversity.

Local microcirculation disorders in uterus under laser tissue welding and their influence in the healing process

NASA Astrophysics Data System (ADS)

Kozlov, Valentine I.; Skobelkin, Oleg K.; Fatkullin, Ildar; Terman, Oleg A.; Chizhov, Gennadii; Gabidullina, Rushania

1994-12-01

To study the possibility of using Nd:YAG laser to weld the tissues of the uterus experiments in rats and dogs have been conducted. With the biomicroscopy and the laser Doppler flowmetry we have evaluated the microcirculation in the uterus wall under traditional suture and laser welding suture. As a model of the wound, the dissection of serosa and muscles of the organ wall have been used. In laser welding suture we have welded the zone of tissue about 1 mm3 with the laser (power density 270 W/cm2). Histological control has been fulfilled on various phases of the healing process. The investigation of the uterus wall demonstrates that there are zones of microcirculation disorders in tissues: (1) the zone of coagulation of microvessels and adjacent tissues (about 100 micrometers ); (2) the zone of stasis (150 - 200 micrometers ); (3) the zone of reactive-destructive changes of microvessels (300 micrometers ), (4) the zone of malfunctional microcirculatory changes (600 micrometers ). The coagulation of microvessels changes the character of inflammation and the healing process, decreases the exudation phase and the leucocyte infiltration of tissues, and accelerates the capillary growth. In contrast with traditional suture, in the case of laser welding suture the edema and hemorrhagic signs are less expressed. The complete restoration of microcirculation under laser welding suture has been observed by the fourteenth day of the healing process. Under the traditional suture method normalization of tissue nutritious blood flow has been achieved by 21 days.

Deterioration of endothelial function of micro- and macrocirculation in patients with diabetes type 1 and 2.

PubMed

Besic, Hana; Jeraj, Luka; Spirkoska, Ana; Jezovnik, Mateja K; Poredoš, Pavel

2017-08-01

Vascular complications are an important cause of morbidity in patients with diabetes mellitus (DM). Endothelial dysfunction is an early marker of atherosclerosis and has already been shown in macrocirculation of diabetic patients; however, data on endothelial function of microcirculation is scarce. Our aim was to evaluate endothelial function in macro- and microcirculation and their interrelationship in patients with type 1 and 2 DM. The study included 30 patients with type 1 DM, 30 patients with type 2 DM and 25 healthy controls. The endothelial function of large arteries was studied measuring flow-mediated dilation (FMD). Peripheral arterial tonometry was used for investigation of the endothelial function of microcirculation, measuring Reactive Hyperemia Index (RHI) and Augmentation Index (AI). In comparison to controls, both DM groups had decreased FMD: type 1 (4.0±5.0% vs. 10.0±7.8%, P=0.005) and type 2 (5.0±0.6% vs. 10.0±7.8%, P=0.007). However, only type 2 DM group had a lower RHI (1.71±0.44 vs. 2.05±0.54, P=0.017) in comparison to controls. Patients with type 1 and 2 DM had deteriorated functional capability of macrocirculation. However, endothelial dysfunction of microcirculation was present only in type 2 DM patients. Type 2 DM patients were also at higher risk for atherosclerosis because of the more frequent presence of risk factors.

Effects of Gas Rarefaction on Dynamic Characteristics of Micro Spiral-Grooved Thrust Bearing.

PubMed

Liu, Ren; Wang, Xiao-Li; Zhang, Xiao-Qing

2012-04-01

The effects of gas-rarefaction on dynamic characteristics of micro spiral-grooved-thrust-bearing are studied. The Reynolds equation is modified by the first order slip model, and the corresponding perturbation equations are then obtained on the basis of the linear small perturbation method. In the converted spiral-curve-coordinates system, the finite-volume-method (FVM) is employed to discrete the surface domain of micro bearing. The results show, compared with the continuum-flow model, that under the slip-flow regime, the decrease in the pressure and stiffness become obvious with the increasing of the compressibility number. Moreover, with the decrease of the relative gas-film-thickness, the deviations of dynamic coefficients between slip-flow-model and continuum-flow-model are increasing.

Rarefaction effects on Galileo probe aerodynamics

NASA Technical Reports Server (NTRS)

Moss, James N.; LeBeau, Gerald J.; Blanchard, Robert C.; Price, Joseph M.

1996-01-01

Solutions of aerodynamic characteristics are presented for the Galileo Probe entering Jupiter's hydrogen-helium atmosphere at a nominal relative velocity of 47.4 km/s. Focus is on predicting the aerodynamic drag coefficient during the transitional flow regime using the direct simulation Monte Carlo (DSMC) method. Accuracy of the probe's drag coefficient directly impacts the inferred atmospheric properties that are being extracted from the deceleration measurements made by onboard accelerometers as part of the Atmospheric Structure Experiment. The range of rarefaction considered in the present study extends from the free molecular limit to continuum conditions. Comparisons made with previous calculations and experimental measurements show the present results for drag to merge well with Navier-Stokes and experimental results for the least rarefied conditions considered.

Impacts of road conditions on the energy consumption of electric vehicular flow

NASA Astrophysics Data System (ADS)

Xiao, Hong; Huang, Hai-Jun; Tang, Tie-Qiao

2017-04-01

In this paper, we use the electricity consumption model for electric vehicular flow [H. Xiao, H. J. Huang and T. Q. Tang, Mod. Phys. Lett. B 30 (2016) 1650325] to study the effects of road conditions on the electricity consumption of electric vehicular flow during the evolutions of shock, rarefaction wave and small perturbation. The numerical results indicate that road conditions have negative influences on the electricity consumption during the evolutions of shock and rarefaction wave (i.e. the electricity consumption increases when road conditions become better) and positive impacts on the electricity consumption during the evolution of small perturbation when the traffic flow is unstable (i.e. the electricity consumption produces oscillation, but its amplitude decreases when road conditions become better).

The blood perfusion and NADH/FAD content combined analysis in patients with diabetes foot

NASA Astrophysics Data System (ADS)

Dremin, Victor V.; Sidorov, Victor V.; Krupatkin, Alexander I.; Galstyan, Gagik R.; Novikova, Irina N.; Zherebtsova, Angelina I.; Zherebtsov, Evgeny A.; Dunaev, Andrey V.; Abdulvapova, Zera N.; Litvinova, Karina S.; Rafailov, Ilya E.; Sokolovski, Sergei G.; Rafailov, Edik U.

2016-03-01

Skin blood microcirculation and the metabolism activity of tissue were examined on the patients with type 2 diabetes. Laser Doppler flowmetry (LDF) with 1064 nm laser light source and fluorescence spectroscopy (FS) with excitation light of 365 nm and 450 nm have been used to monitor the blood perfusion and the content of coenzymes NADH and FAD. Concluding, the proposed combined LDF and tissue FS approach allows to identify the significant violations in the blood microcirculation and metabolic activity for type 2 diabetes patients.

Quantitative laser speckle flowmetry of the in vivo microcirculation using sidestream dark field microscopy

PubMed Central

Nadort, Annemarie; Woolthuis, Rutger G.; van Leeuwen, Ton G.; Faber, Dirk J.

2013-01-01

We present integrated Laser Speckle Contrast Imaging (LSCI) and Sidestream Dark Field (SDF) flowmetry to provide real-time, non-invasive and quantitative measurements of speckle decorrelation times related to microcirculatory flow. Using a multi exposure acquisition scheme, precise speckle decorrelation times were obtained. Applying SDF-LSCI in vitro and in vivo allows direct comparison between speckle contrast decorrelation and flow velocities, while imaging the phantom and microcirculation architecture. This resulted in a novel analysis approach that distinguishes decorrelation due to flow from other additive decorrelation sources. PMID:24298399

Quantitative depth resolved microcirculation imaging with optical coherence tomography angiography (Part ΙΙ): Microvascular network imaging.

PubMed

Gao, Wanrong

2017-04-17

In this work, we review the main phenomena that have been explored in OCT angiography to image the vessels of the microcirculation within living tissues with the emphasis on how the different processing algorithms were derived to circumvent specific limitations. Parameters are then discussed that can quantitatively describe the depth-resolved microvascular network for possible clinic diagnosis applications. Finally,future directions in continuing OCT development are discussed. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

[Temperature-dependent changes in the microcirculation of the dental pulp].

PubMed

Raab, W H; Müller, H

1989-07-01

Laser Doppler flowmetry was used to study the changes in the blood flow within the dental pulp as a reaction to thermal stimuli between 17 degrees C and 57 degree C. Temperatures below 31 degrees C resulted in a reduction, temperatures above 43 degrees C in an increase in blood flow. Temperatures higher than 49 degrees C caused irreversible damage to the pulp's microcirculation. Experimental nerve blocks showed that the reactive increase is linked to the afferent rather than the sympathetic innervation of the tooth pulp.

Investigation of Doppler spectra of laser radiation scattered inside hand skin during occlusion test

NASA Astrophysics Data System (ADS)

Kozlov, I. O.; Zherebtsov, E. A.; Zherebtsova, A. I.; Dremin, V. V.; Dunaev, A. V.

2017-11-01

Laser Doppler flowmetry (LDF) is a method widely used in diagnosis of microcirculation diseases. It is well known that information about frequency distribution of Doppler spectrum of the laser radiation scattered by moving red blood cells (RBC) usually disappears after signal processing procedure. Photocurrent’s spectrum distribution contains valuable diagnostic information about velocity distribution of the RBC. In this research it is proposed to compute the indexes of microcirculation in the sub-ranges of the Doppler spectrum as well as investigate the frequency distribution of the computed indexes.

[Rehabilitative medical technology for the correction of microcirculatory disorders in patients with arterial hypertension].

PubMed

Kul'chitskaia, D B

2009-01-01

The study with the use of laser Doppler flowmetry has revealed pathological changes in the microcirculatory system of patients with arterial hypertension. Their treatment with a low-frequency magnetic field showed that its effect on microcirculation depends on the regime and site of application of magnetotherapy as well as its combination with other physical factors. Frontal application of the magnetic field had the most pronounced beneficial effect on dynamic characteristics of microcirculation. Pulsed regime of magnetotherapy was more efficacious than conventional one. Amplipulse magnetotherapy produced better results than monotherapy.

Citrulline a More Suitable Substrate than Arginine to Restore NO Production and the Microcirculation during Endotoxemia

PubMed Central

Wijnands, Karolina A. P.; Vink, Hans; Briedé, Jacob J.; van Faassen, Ernst E.; Lamers, Wouter H.; Buurman, Wim A.; Poeze, Martijn

2012-01-01

Background Impaired microcirculation during endotoxemia correlates with a disturbed arginine-nitric oxide (NO) metabolism and is associated with deteriorating organ function. Improving the organ perfusion in endotoxemia, as often seen in patients with severe infection or systemic inflammatory response syndrome (SIRS) is, therefore, an important therapeutic target. We hypothesized that supplementation of the arginine precursor citrulline rather than arginine would specifically increase eNOS-induced intracellular NO production and thereby improve the microcirculation during endotoxemia. Methodology/Principal Findings To study the effects of L-Citrulline and L-Arginine supplementation on jejunal microcirculation, intracellular arginine availability and NO production in a non-lethal prolonged endotoxemia model in mice. C57/Bl6 mice received an 18 hrs intravenous infusion of endotoxin (LPS, 0.4 µg•g bodyweight−1•h−1), combined with either L-Citrulline (6.25 mg•h-1), L-Arginine (6.25 mg•h−1), or L-Alanine (isonitrogenous control; 12.5 mg•h−1) during the last 6 hrs. The control group received an 18 hrs sterile saline infusion combined with L-Alanine or L-Citrulline during the last 6 hrs. The microcirculation was evaluated at the end of the infusion period using sidestream dark-field imaging of jejunal villi. Plasma and jejunal tissue amino-acid concentrations were measured by HPLC, NO tissue concentrations by electron-spin resonance spectroscopy and NOS protein concentrations using Western blot. Conclusion/Significance L-Citrulline supplementation during endotoxemia positively influenced the intestinal microvascular perfusion compared to L-Arginine-supplemented and control endotoxemic mice. L-Citrulline supplementation increased plasma and tissue concentrations of arginine and citrulline, and restored intracellular NO production in the intestine. L-Arginine supplementation did not increase the intracellular arginine availability. Jejunal tissues in the L-Citrulline-supplemented group showed, compared to the endotoxemic and L-Arginine-supplemented endotoxemic group, an increase in degree of phosphorylation of eNOS (Ser 1177) and a decrease in iNOS protein level. In conclusion, L-Citrulline supplementation during endotoxemia and not L-Arginine reduced intestinal microcirculatory dysfunction and increased intracellular NO production, likely via increased intracellular citrulline and arginine availability. PMID:22666356

Characteristics of Intratendinous Microcirculation Shortly After an Achilles Rupture and Subsequent Treatment Outcomes.

PubMed

Chang, Yi-Ping; Shih, Kao-Shang; Chiang, Hongsen; Ma, Hsiao-Li; Lin, Leou-Chyr; Peng, Wei-Chen; Wen, Che-Sheng; Wang, Hsing-Kuo

2017-01-01

Early microcirculatory responses after experimental tenotomy are critical to the healing of tendons and their ultimate tensile strength. The effects of changes in microcirculation on the outcomes of tendon healing, however, have not been determined. To assess microcirculation values in injured Achilles tendons in the first 3 months after surgical repair and to correlate the inter-limb microcirculatory changes with functional outcomes at 3 and 6 months after surgery. Case-control study. A university sports physiotherapy laboratory. Thirteen subjects (median age: 45 years; range: 34.8-51.9 years) with a repaired Achilles tendon were recruited. Surgical repair. Measurements were obtained at 1, 2, 3, and 6 months after surgery. Bilateral measurements of tendon microcirculation (total hemoglobin [THb] and oxygen saturation [StO 2 ]) were recorded at the first 3 time points, whereas outcome measures of a Taiwan Chinese version of the Victorian Institute of Sport Assessment Scale-Achilles questionnaire, one-leg hopping distance, the star excursion balance test, and the heel raise index were conducted at the third and fourth time points. Correlations between the inter-limb microcirculatory changes, eg, between the measurements at 2 months and 1 month (2-1) after surgery, at 3 months and 2 months (3-2) after surgery, and at 3 months and 1 month (3-1) after surgery, and the outcome measures were investigated. Compared with the noninjured tendons, the repaired Achilles demonstrated greater THb (at 1, 2, and 3 months; P = .017, .008, and .012 respectively) and StO 2 (at 3 months; P = .017). Furthermore, the THb2-1 and THb3-2, StO 2 2-1, and StO 2 3-2 showed correlations with the heel raise index, differences in the star excursion balance test and one-leg hopping distance between the noninjured leg and injured leg, and Taiwan Chinese version of the Victorian Institute of Sport Assessment Scale-Achilles questionnaire scores (rho -0.921 to 0.855). Changes in the inter-limb microcirculation shortly after Achilles repair were correlated with subsequent symptoms and functional symmetry. III. Copyright © 2017 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Conjunctival microcirculatory blood flow is altered but not abolished in brain dead patients: a prospective observational study.

PubMed

Tamosuitis, Tomas; Pranskunas, Andrius; Balciuniene, Neringa; Pilvinis, Vidas; Boerma, E Christiaan

2016-07-11

The conjunctival microcirculation has potential as a window to cerebral perfusion due to related blood supply, close anatomical proximity and easy accessibility for microcirculatory imaging technique, such as sidestream dark field (SDF) imaging. Our study aims to evaluate conjunctival and sublingual microcirculation in brain dead patients and to compare it with healthy volunteers in two diametrically opposed conditions: full stop versus normal arterial blood supply to the brain. In a prospective observational study we analyzed conjunctival and sublingual microcirculation using SDF imaging in brain dead patients after reaching systemic hemodynamic targets to optimize perfusion of donor organs, and in healthy volunteers. All brain death diagnoses were confirmed by cerebral angiography. Microcirculatory images were obtained and analyzed using standardized published recommendations. Study registered at ClinicalTrials.gov, number NCT02483273. Eleven brain dead patients and eleven apparently healthy controls were enrolled in the study. Microvascular flow index (MFI) of small vessels was significantly lower in brain dead patients in comparison to healthy controls in ocular conjunctiva (2.7 [2.4-2.9] vs. 3.0 [2.9-3.0], p = 0.01) and in sublingual mucosa (2.8 [2.6-2.9] vs. 3.0 [2.9-3.0], p = 0.02). Total vessel density (TVD) and perfused vessel density (PVD) of small vessels were significantly lower in brain dead patients in comparison to healthy controls in ocular conjunctiva (10.2 [6.6-14.8] vs. 18.0 [18.0-25.4] mm/mm(2), p = 0.001 and 5.0 [3.5-7.3] vs. 10.9 [10.9-13.5] 1/mm, p = 0.001), but not in sublingual mucosa. In comparison to healthy controls brain dead patients had a significant reduction in conjunctival microvascular blood flow and density. However, the presence of conjunctival flow in case general cerebral flow is completely absent makes it impossible to use the conjunctival microcirculation as a substitute for brain flow, and further research should focus on the link between the ocular microcirculation, intracranial pressure and alternative ocular circulation.

Microcirculation and its relation to continuous subcutaneous glucose sensor accuracy in cardiac surgery patients in the intensive care unit.

PubMed

Siegelaar, Sarah E; Barwari, Temo; Hermanides, Jeroen; van der Voort, Peter H J; Hoekstra, Joost B L; DeVries, J Hans

2013-11-01

Continuous glucose monitoring could be helpful for glucose regulation in critically ill patients; however, its accuracy is uncertain and might be influenced by microcirculation. We investigated the microcirculation and its relation to the accuracy of 2 continuous glucose monitoring devices in patients after cardiac surgery. The present prospective, observational study included 60 patients admitted for cardiac surgery. Two continuous glucose monitoring devices (Guardian Real-Time and FreeStyle Navigator) were placed before surgery. The relative absolute deviation between continuous glucose monitoring and the arterial reference glucose was calculated to assess the accuracy. Microcirculation was measured using the microvascular flow index, perfused vessel density, and proportion of perfused vessels using sublingual sidestream dark-field imaging, and tissue oxygenation using near-infrared spectroscopy. The associations were assessed using a linear mixed-effects model for repeated measures. The median relative absolute deviation of the Navigator was 11% (interquartile range, 8%-16%) and of the Guardian was 14% (interquartile range, 11%-18%; P = .05). Tissue oxygenation significantly increased during the intensive care unit admission (maximum 91.2% [3.9] after 6 hours) and decreased thereafter, stabilizing after 20 hours. A decrease in perfused vessel density accompanied the increase in tissue oxygenation. Microcirculatory variables were not associated with sensor accuracy. A lower peripheral temperature (Navigator, b = -0.008, P = .003; Guardian, b = -0.006, P = .048), and for the Navigator, also a higher Acute Physiology and Chronic Health Evaluation IV predicted mortality (b = 0.017, P < .001) and age (b = 0.002, P = .037) were associated with decreased sensor accuracy. The results of the present study have shown acceptable accuracy for both sensors in patients after cardiac surgery. The microcirculation was impaired to a limited extent compared with that in patients with sepsis and healthy controls. This impairment was not related to sensor accuracy but the peripheral temperature for both sensors and patient age and Acute Physiology and Chronic Health Evaluation IV predicted mortality for the Navigator were. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Blood-filled cerebrospinal fluid-enhanced pericyte microvasculature contraction in rat retina: A novel in vitro study of subarachnoid hemorrhage

PubMed Central

Liu, Zhi; Li, Qiang; Cui, Gaoyu; Zhu, Gang; Tang, Weihua; Zhao, Hengli; Zhang, John H.; Chen, Yujie; Feng, Hua

2016-01-01

Previously, it was widely accepted that the delayed ischemic injury and poor clinical outcome following subarachnoid hemorrhage (SAH) was caused by cerebral vasospasm. This classical theory was challenged by a clazosentan clinical trial, which failed to improve patient outcome, despite reversing angiographic vasospasm. One possible explanation for the results of this trial is the changes in microcirculation following SAH, particularly in pericytes, which are the primary cell type controlling microcirculation in the brain parenchyma. However, as a result of technical limitations and the lack of suitable models, there was no direct evidence of microvessel dysfunction following SAH. In the present study, whole-mount retinal microvasculature has been introduced to study microcirculation in the brain following experimental SAH in vitro. Artificial blood-filled cerebrospinal fluid (BSCF) was applied to the retinal microvasculature to test the hypothesis that the presence of subarachnoid blood affects the contractile properties of the pericytes containing cerebral microcirculation during the early phase of SAH. It was observed that BCSF induced retina microvessel contraction and that this contraction could be resolved by BCSF wash-out. Furthermore, BCSF application accelerated pericyte-populated collagen gel contraction and increased the expression of α-smooth muscle actin. In addition, BCSF induced an influx of calcium in cultured retinal pericytes. In conclusion, the present study demonstrates increased contractility of retinal microvessels and pericytes in the presence of BCSF in vitro. These findings suggest that pericyte contraction and microvascular dysfunction is induced following SAH, which could lead to greater susceptibility to SAH-induced ischemia. PMID:27698742

Oxygen gradients in the microcirculation.

PubMed

Pittman, R N

2011-07-01

Early in the last century August Krogh embarked on a series of seminal studies to understand the connection between tissue metabolism and mechanisms by which the cardiovascular system supplied oxygen to meet those needs. Krogh recognized that oxygen was supplied from blood to the tissues by passive diffusion and that the most likely site for oxygen exchange was the capillary network. Studies of tissue oxygen consumption and diffusion coefficient, coupled with anatomical studies of capillarity in various tissues, led him to formulate a model of oxygen diffusion from a single capillary. Fifty years after the publication of this work, new methods were developed which allowed the direct measurement of oxygen in and around microvessels. These direct measurements have confirmed the predictions by Krogh and have led to extensions of his ideas resulting in our current understanding of oxygenation within the microcirculation. Developments during the last 40 years are reviewed, including studies of oxygen gradients in arterioles, capillaries, venules, microvessel wall and surrounding tissue. These measurements were made possible by the development and use of new methods to investigate oxygen in the microcirculation, so mention is made of oxygen microelectrodes, microspectrophotometry of haemoglobin and phosphorescence quenching microscopy. Our understanding of oxygen transport from the perspective of the microcirculation has gone from a consideration of oxygen gradients in capillaries and tissue to the realization that oxygen has the ability to diffuse from any microvessel to another location under the conditions that there exists a large enough PO(2) gradient and that the permeability for oxygen along the intervening pathway is sufficient. © 2011 The Author. Acta Physiologica © 2011 Scandinavian Physiological Society.

Micro- and Macrocirculatory Changes During Sepsis and Septic Shock in a Rat Model.

PubMed

Hua, Tianfeng; Wu, Xiaobo; Wang, Wei; Li, Hao; Bradley, Jennifer; Peberdy, Mary A; Ornato, Joseph P; Tang, Wanchun

2018-05-01

Microcirculation is the motor of sepsis. In the present study, we investigated whether microcirculatory alterations occur before changes of systemic hemodynamics in a rat model of cecum ligation and puncture (CLP)-induced sepsis. We further investigated renal microcirculatory changes during sepsis and compared those with buccal microcirculation. Twelve male Sprague-Dawley rats were randomized into a sham control group (n = 6) and a CLP group (n = 6). Perfused microvessel density (PVD) and microvascular flow index (MFI) were evaluated using sidestream dark field (SDF) video microscopy at baseline-60, 120, 180, 240, 300, and 360 min following CLP. A semiquantitative score was calculated for vessels of less than 20 μm, primarily representing the capillaries. Hemodynamic measurements such as cardiac output (CO), aortic pressure (AP), heart rate (HR), end-tidal CO2 (ETCO2), blood pH, and lactate were measured simultaneously. The serum cytokine interleukin 6 (IL-6) was measured at baseline-120, 240, and 360 min. In the CLP group, buccal PVD and MFI were reduced at 180 min (P < 0.05 vs. baseline); renal PVD and MFI were reduced at 180 min (P < 0.05 vs. baseline), but MAP and CO did not change until 300 min after CLP. In the rat model of peritonitis-induced sepsis, microcirculatory alterations of both peripheral mucosa and kidney occurred earlier than global hemodynamics. Monitoring the microcirculation may provide a means of early detection of circulatory failure during sepsis. The changes of renal microcirculation correlate with that of buccal during sepsis and septic shock.

Compliance with dietary guidelines affects capillary recruitment in healthy middle-aged men and women.

PubMed

Govoni, Virginia; Sanders, Thomas A B; Reidlinger, Dianne P; Darzi, Julia; Berry, Sarah E E; Goff, Louise M; Seed, Paul T; Chowienczyk, Philip J; Hall, Wendy L

2017-04-01

Healthy microcirculation is important to maintain the health of tissues and organs, most notably the heart, kidney and retina. Single components of the diet such as salt, lipids and polyphenols may influence microcirculation, but the effects of dietary patterns that are consistent with current dietary guidelines are uncertain. It was hypothesized that compliance to UK dietary guidelines would have a favourable effect on skin capillary density/recruitment compared with a traditional British diet (control diet). A 12-week randomized controlled trial in men and women aged 40-70 years was used to test whether skin microcirculation, measured by skin video-capillaroscopy on the dorsum of the finger, influenced functional capillary density (number of capillaries perfused under basal conditions), structural capillary density (number of anatomical capillaries perfused during finger cuff inflation) and capillary recruitment (percentage difference between structural and functional capillary density). Microvascular measures were available for 137 subjects out of the 165 participants randomized to treatment. There was evidence of compliance to the dietary intervention, and participants randomized to follow dietary guidelines showed significant falls in resting supine systolic, diastolic and mean arterial pressure of 3.5, 2.6 and 2.9 mmHg compared to the control diet. There was no evidence of differences in capillary density, but capillary recruitment was 3.5 % (95 % CI 0.2, 6.9) greater (P = 0.04) on dietary guidelines compared with control. Adherence to dietary guidelines may help maintain a healthy microcirculation in middle-aged men and women. This study is registered at www.isrctn.com as ISRCTN92382106.

Verification and calibration of laser Doppler flowmetry (LDF) prototype for measurement of microcirculation

NASA Astrophysics Data System (ADS)

Li, Yung-Hui; Hu, Chia-Ming; Tsai, Ming-Lun

2017-10-01

Laser Doppler Flowmetry (LDF), a non-invasive microcirculation measurement equipment, is designed to be used in measuring microcirculation and perfusion in the skin. LDF is very applicable to healthcare. However, the cost of commercial LDF prevents its prevalence and popularity. In this paper, continuing previous researches, a LDF prototype was built from the combination of the off-the-shelf electronic components. The raw signals acquired from the proposed LDF prototype is validated to be relevant to the microcirculation flux. Furthermore, we would like to verify the consistency between the signals measured from both model, and find an implicit transformation rule to transform the LDF prototype signals. For the purpose of verification and calibration of the LDF prototype signal feature, we first collected a parallel database consisting of flux signals measured by commercial and prototype LDF at the same time. Second, we extract signals with specific frequency of normalized signals as features and use these features to establish a model to allow us to map signals measured by LDF prototype to the commercial model. The result of the experiment showed that after we used the linear regression models to calibrate physiological feature, the correlation coefficient reached nearly 0.9999, which is close to a perfect positive correlation. The overall evaluation results showed that the proposed method can verify and ensure the validity of the LDF prototype. Through the proposed transformation, the flux signals measured by the proposed LDF prototype can successfully be transformed to its parallel form as if it is measured by commercial LDF.

Oxygen Gradients in the Microcirculation

PubMed Central

Pittman, Roland N.

2010-01-01

Early in the last century August Krogh embarked on a series of seminal studies to understand the connection between tissue metabolism and mechanisms by which the cardiovascular system supplied oxygen to meet those needs. Krogh recognized that oxygen was supplied from blood to the tissues by passive diffusion and that the most likely site for oxygen exchange was the capillary network. Studies of tissue oxygen consumption and diffusion coefficient, coupled with anatomical studies of capillarity in various tissues, led him to formulate a model of oxygen diffusion from a single capillary. Fifty years after the publication of this work, new methods were developed which allowed the direct measurement of oxygen in and around microvessels. These direct measurements have confirmed the predictions by Krogh and have led to extensions of his ideas resulting in our current understanding of oxygenation within the microcirculation. Developments during the last 40 years are reviewed, including studies of oxygen gradients in arterioles, capillaries, venules, microvessel wall and surrounding tissue. These measurements were made possible by the development and use of new methods to investigate oxygen in the microcirculation, so mention is made of oxygen microelectrodes, microspectrophotometry of haemoglobin and phosphorescence quenching microscopy. Our understanding of oxygen transport from the perspective of the microcirculation has gone from a consideration of oxygen gradients in capillaries and tissue to the realization that oxygen has the ability to diffuse from any microvessel to another location under the conditions that there exists a large enough PO2 gradient and that the permeability for oxygen along the intervening pathway is sufficient. PMID:21281453

Is there a stimulation of blood microcirculation at low level laser irradiation

NASA Astrophysics Data System (ADS)

Rogatkin, Dmitry; Dunaev, Andrey

2014-05-01

In 1980-2000 besides the laser surgery an intensive evolution of Low Level Laser Therapy (LLLT) had started in medicine, especially in Russia as well as in several other East-European countries. At the same time the biophysical mechanisms of LLLT are still the subject of disputes. One of the most popular clinical effects at Low Level Laser Irradiation (LLLI) being mentioned in medical publications for justification of the LLLT healing outcome is a stimulation of blood microcirculation in irradiated area. It was declared a priori at a dawn of LLLT and is now a basis of medical interpretation of healing mechanisms of LLLT at least in Russia. But in past 20 years a lot of investigation was carried out on optical registration of microhaemodynamic parameters in vivo as well as a number of noninvasive diagnostic tools was created for that. So, today it is possible to experimentally check the blood microcirculation stimulation hypothesis. Our study was aimed on that during the past 10 years. The most precision and accurate experiments we have carried out recently using simultaneously three different noninvasive diagnostic techniques: Laser Doppler Flowmetry, Tissue Reflectance Oximetry and Infrared Thermography. All these methods didn't confirm the effect on the blood microcirculation stimulation in skin or mucosa at irradiation with the power density below 50 mW/cm2 and irradiation time up to 5-6 minutes. Above this threshold the heating on 0,8…1 °C of tissue in the field of irradiation and the corresponding synchronous increase of all parameters of microhemodynamics were observed.

Choroidal microcirculation in patients with rotary cardiac assist device.

PubMed

Polska, Elzbieta; Schima, Heinrich; Wieselthaler, Georg; Schmetterer, Leopold

2007-06-01

In recent years, fully implanted rotary blood pumps have been used for long-term cardiac assist in patients with end-stage heart failure. With these pumps, the pulsatility of arterial blood flow and arterial pressure pulse is considerably reduced. Effects on end-organ perfusion, particularly microcirculation, have been assessed. The ocular choroid offers a unique opportunity to study the pulsatile component of blood flow by measurement of fundus pulsation amplitude (FPA) as well as the microcirculation by laser Doppler flowmetry. Both techniques were applied in three male patients with rotary pumps (MicroMed DeBakey VAD), in whom pump velocity was adjusted to four levels of flow between individual minimal need and maximal support. In addition, blood flow velocities in the ophthalmic artery (peak, end-diastolic and mean flow velocity--PSV, EDV and MFV, respectively) were measured using color Doppler imaging. Systolic blood pressure increased by 6 to 22 mm Hg with increasing support. At maximal support FPA was reduced by -60% to -52% as compared with minimal pump support. Blood flow in the choroidal microvasculature, however, did not show relevant changes. A reduction in PSV (-31%, range -47% to -21%) and a pronounced rise in EDV (+93%, range +28% to +147%) was observed, whereas MFV was independent of pump flow. Our data indicate that mean choroidal blood flow is maintained when pump support is varied within therapeutic values, whereas the ratio of pulsatile to non-pulsatile choroidal flow changes. This study shows that, in patients with ventricular assist devices, a normal perfusion rate in the ocular microcirculation is maintained over a wide range of support conditions.

Verification test of the SURF and SURFplus models in xRage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menikoff, Ralph

2016-05-18

As a verification test of the SURF and SURFplus models in the xRage code we use a propagating underdriven detonation wave in 1-D. This is about the only test cases for which an accurate solution can be determined based on the theoretical structure of the solution. The solution consists of a steady ZND reaction zone profile joined with a scale invariant rarefaction or Taylor wave and followed by a constant state. The end of the reaction profile and the head of the rarefaction coincide with the sonic CJ state of the detonation wave. The constant state is required to matchmore » a rigid wall boundary condition. For a test case, we use PBX 9502 with the same EOS and burn rate as previously used to test the shock detector algorithm utilized by the SURF model. The detonation wave is propagated for 10 μs (slightly under 80mm). As expected, the pointwise errors are largest in the neighborhood of discontinuities; pressure discontinuity at the lead shock front and pressure derivative discontinuities at the head and tail of the rarefaction. As a quantitative measure of the overall accuracy, the L2 norm of the difference of the numerical pressure and the exact solution is used. Results are presented for simulations using both a uniform grid and an adaptive grid that refines the reaction zone.« less

Robust optimal design of diffusion-weighted magnetic resonance experiments for skin microcirculation

NASA Astrophysics Data System (ADS)

Choi, J.; Raguin, L. G.

2010-10-01

Skin microcirculation plays an important role in several diseases including chronic venous insufficiency and diabetes. Magnetic resonance (MR) has the potential to provide quantitative information and a better penetration depth compared with other non-invasive methods such as laser Doppler flowmetry or optical coherence tomography. The continuous progress in hardware resulting in higher sensitivity must be coupled with advances in data acquisition schemes. In this article, we first introduce a physical model for quantifying skin microcirculation using diffusion-weighted MR (DWMR) based on an effective dispersion model for skin leading to a q-space model of the DWMR complex signal, and then design the corresponding robust optimal experiments. The resulting robust optimal DWMR protocols improve the worst-case quality of parameter estimates using nonlinear least squares optimization by exploiting available a priori knowledge of model parameters. Hence, our approach optimizes the gradient strengths and directions used in DWMR experiments to robustly minimize the size of the parameter estimation error with respect to model parameter uncertainty. Numerical evaluations are presented to demonstrate the effectiveness of our approach as compared to conventional DWMR protocols.

Evaluation of three inverse problem models to quantify skin microcirculation using diffusion-weighted MRI

NASA Astrophysics Data System (ADS)

Cordier, G.; Choi, J.; Raguin, L. G.

2008-11-01

Skin microcirculation plays an important role in diseases such as chronic venous insufficiency and diabetes. Magnetic resonance imaging (MRI) can provide quantitative information with a better penetration depth than other noninvasive methods, such as laser Doppler flowmetry or optical coherence tomography. Moreover, successful MRI skin studies have recently been reported. In this article, we investigate three potential inverse models to quantify skin microcirculation using diffusion-weighted MRI (DWI), also known as q-space MRI. The model parameters are estimated based on nonlinear least-squares (NLS). For each of the three models, an optimal DWI sampling scheme is proposed based on D-optimality in order to minimize the size of the confidence region of the NLS estimates and thus the effect of the experimental noise inherent to DWI. The resulting covariance matrices of the NLS estimates are predicted by asymptotic normality and compared to the ones computed by Monte-Carlo simulations. Our numerical results demonstrate the effectiveness of the proposed models and corresponding DWI sampling schemes as compared to conventional approaches.

Evaluation of gingival vascularisation using laser Doppler flowmetry

NASA Astrophysics Data System (ADS)

Vitez, B.; Todea, C.; Velescu, A.; Şipoş, C.

2016-03-01

Aim: The present study aims to assess the level of vascularisation of the lower frontal gingiva of smoker patients, in comparison with non-smokers by using Laser Doppler Flowmetry (LDF), in order to determine the changes in gingival microcirculation. Material & methods: 16 volunteers were included in this study and separated into 2 equal groups: non-smoker subjects in Group I and smoker subjects in Group II. All patients were submitted to a visual examination and professional cleaning The gingival bloodflow of each patient was recorded in 5 zones using LDF, resulting in a total of 80 recordings. LDF was done with the Moor Instruments Ltd. "moorLAB" Laser Doppler. All data were collected as graphs, raw values and statistically analyzed. Results: After strict analysis results show that Group II presents a steady level of gingival microcirculation with even patterns in the graph, while Group I shows many signs of damage to it`s microvascular system through many irregularities in the microcirculation level and graph patterns. Conclusion: The results suggest that prolonged smoking has a definitive effect on the gingival vascularisation making it a key factor in periodontal pathology.

High-Efficiency Multiscale Modeling of Cell Deformations in Confined Microenvironments in Microcirculation and Microfluidic Devices

NASA Astrophysics Data System (ADS)

Lu, Huijie; Peng, Zhangli

2017-11-01

Our goal is to develop a high-efficiency multiscale modeling method to predict the stress and deformation of cells during the interactions with their microenvironments in microcirculation and microfluidic devices, including red blood cells (RBCs) and circulating tumor cells (CTCs). There are more than 1 billion people in the world suffering from RBC diseases, e.g. anemia, sickle cell diseases, and malaria. The mechanical properties of RBCs are changed in these diseases due to molecular structure alternations, which is not only important for understanding the disease pathology but also provides an opportunity for diagnostics. On the other hand, the mechanical properties of cancer cells are also altered compared to healthy cells. This can lead to acquired ability to cross the narrow capillary networks and endothelial gaps, which is crucial for metastasis, the leading cause of cancer mortality. Therefore, it is important to predict the deformation and stress of RBCs and CTCs in microcirculations. We are developing a high-efficiency multiscale model of cell-fluid interaction to study these two topics.

Wavelet-analysis of gastric microcirculation in rats with ulcer bleedings

NASA Astrophysics Data System (ADS)

Pavlov, A. N.; Semyachkina-Glushkovskaya, O. V.; Pavlova, O. N.; Bibikova, O. A.; Kurths, J.

2013-10-01

Nitric oxide (NO) plays an important role in regulation of central and peripheral circulation in normal state and during hemorrhagic stress. Because the impaired gastric mucosal blood flow is the major cause of gastroduodenal lesions including ulcer bleeding (UB), we study in this work the NO-ergic mechanism responsible for regulation of this blood flow. Our study is performed in rats with a model of stress-induced UB using laser Doppler flowmetry (LDF) that characterizes the rate of blood flow by measuring a Doppler shift of the laser beam scattered by the moving red blood cells. Numerical analysis of LDF-data is based on the discrete wavelet-transform (DWT) using Daubechies wavelets aiming to quantify influences of NO on the gastric microcirculation. We show that the stress-induced UB is associated with an increased level of NO in the gastric tissue and a stronger vascular sensitivity to pharmacological modulation of NO-production by L-NAME. We demonstrate that wavelet-based analyses of NO-dependent regulation of gastric microcirculation can provide an effective endoscopic diagnostics of a risk of UB.

The hydrodynamic theory of detonation

NASA Technical Reports Server (NTRS)

Langweiler, Heinz

1939-01-01

This report derives equations containing only directly measurable constants for the quantities involved in the hydrodynamic theory of detonation. The stable detonation speed, D, is revealed as having the lowest possible value in the case of positive material velocity, by finding the minimum of the Du curve (u denotes the speed of the gases of combustion). A study of the conditions of energy and impulse in freely suspended detonating systems leads to the disclosure of a rarefaction front traveling at a lower speed behind the detonation front; its velocity is computed. The latent energy of the explosive passes into the steadily growing detonation zone - the region between the detonation front and the rarefaction front. The conclusions lead to a new definition of the concept of shattering power. The calculations are based on the behavior of trinitrotoluene.

Electrostatic shocks and solitons in pair-ion plasmas in a two-dimensional geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masood, W.; Mahmood, S.; Imtiaz, N.

2009-12-15

Nonlinear electrostatic waves are studied in unmagnetized, dissipative pair-ion plasmas in the presence of weak transverse perturbations. The dissipation in the system is taken into account by incorporating the kinematic viscosity of both positive and negative ions in plasmas. The Kadomtsev-Petviashvili-Burger equation is derived using the small amplitude expansion method. The Kadomtsev-Petviashvili equation for pair-ion plasmas is also presented by ignoring the dissipative effects. Both compressive and rarefactive shocks and solitary waves are found to exist in pair-ion plasmas. The dependence of compression and rarefaction on the temperature ratios between the ion species is numerically shown. The present study maymore » have relevance to the understanding of the formation of electrostatic shocks and solitons in laboratory produced pair-ion plasmas.« less

Rarefaction waves in van der Waals fluids with an arbitrary number of degrees of freedom

DOE PAGES

Yuen, Albert; Barnard, John J.

2015-09-30

The isentropic expansion of an instantaneously and homogeneously heated foil is calculated using a 1D fluid model. The initial temperature and density are assumed to be in the vicinity of the critical temperature and solid density, respectively. The fluid is assumed to satisfy the van der Waals equation of state with an arbitrary number of degrees of freedom. Self-similar Riemann solutions are found. With a larger number of degrees of freedom f, depending on the initial dimensionless entropymore » $$˜\\atop{s_0}$$, a richer family of foil expansion behaviors have been found. We calculate the domain in parameter space where these behaviors occur. In total, eight types of rarefaction waves are found and described.« less

Estimates of the magnitudes of major marine mass extinctions in earth history

PubMed Central

2016-01-01

Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor–Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record. Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ∼81% of marine species died out in the great terminal Permian crisis, whereas levels of 90–96% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed. PMID:27698119

Estimates of the magnitudes of major marine mass extinctions in earth history

NASA Astrophysics Data System (ADS)

Stanley, Steven M.

2016-10-01

Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor-Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record. Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ˜81% of marine species died out in the great terminal Permian crisis, whereas levels of 90-96% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed.

Estimates of the magnitudes of major marine mass extinctions in earth history.

PubMed

Stanley, Steven M

2016-10-18

Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor-Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record. Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ∼81% of marine species died out in the great terminal Permian crisis, whereas levels of 90-96% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed.

Changes in the cerebral blood flow in newborn rats assessed by LSCI and DOCT before and after the hemorrhagic stroke

NASA Astrophysics Data System (ADS)

Semyachkina-Glushkovskaya, O. V.; Lychagov, V. V.; Abdurashitov, A. S.; Sindeeva, O. V.; Sindeev, S. S.; Zinchenko, E. M.; Kajbeleva, E. I.; Pavlov, A. N.; Kassim, M.; Tuchin, V. V.

2015-03-01

The incidence of perinatal hemorrhagic stroke (HS) is very similar to that in the elderly and produces a significant morbidity and long-term neurologic and cognitive deficits. There is strong evidence that cerebral blood flow (CBF) abnormalities make considerable contribution to HS development. However, the mechanisms responsible for pathological changes in CBF in infants with HS are not established. Therefore, quantitative assessment of CBF may significantly advance the understanding of the nature of neonatal stroke. The aim of this investigation was to determine the particularities of alterations in macro- microcirculation in the brain of newborn rats in the different stages of stress-related development of HS using three-dimensional Doppler optical coherence tomography (DOCT) and laser speckle contrast imaging (LSCI).Our results show that cerebral veins are more sensitive to harmful effect of stress compared with microcirculatory vessels. Stress-induced progressive dilation of cerebral veins with the fall of blood flow velocity precedes HS while pathological changes in microcirculatory vessels are accompanied by development of HS. The further detailed study of cerebral venous and microcirculatory circulation would be a significant advance in development of prognostic criteria for a HS risk during the first days after birthday.

Parameters of Microcirculation in the Broad Ligament of the Uterus in Wistar Rats after Injection of Autologous Biomedical Cell Product.

PubMed

Dergacheva, T I; Lykov, A P; Shurlygina, A V; Starkova, E V; Poveshchenko, O V; Bondarenko, N A; Kim, I I; Tenditnik, M V; Borodin, Yu I; Konenkov, V I

2015-10-01

We studied the effects of autologous biomedical cell product (bone marrow multipotent mesenchymal stromal cells and their conditioned media) on the parameters of the microcirculatory bed in the broad ligament of the uterus of normal Wistar rats were studied. The parameters of microcirculation and lymph drainage in the broad ligament changed in opposite directions in response to injection of autologous biomedical cell product via different routes. This fact should be taken into consideration when prescribing cell therapy for inflammatory degenerative processes in the pelvic organs.

Impaired cerebral microcirculation induced by ammonium chloride in rats is due to cortical adenosine release.

PubMed

Bjerring, Peter Nissen; Bjerrum, Esben Jannik; Larsen, Fin Stolze

2018-06-01

Liver failure results in hyperammonaemia, impaired regulation of cerebral microcirculation, encephalopathy, and death. However, the key mediator that alters cerebral microcirculation remains unidentified. In this study we show that topically applied ammonium significantly increases periarteriolar adenosine tone on the brain surface of healthy rats and is associated with a disturbed microcirculation. Cranial windows were prepared in anaesthetized Wistar rats. The flow velocities were measured by speckle contrast imaging and compared before and after 30 min of exposure to 10 mM ammonium chloride applied on the brain surface. These flow velocities were compared with those for control groups exposed to artificial cerebrospinal fluid or ammonium plus an adenosine receptor antagonist. A flow preservation curve was obtained by analysis of flow responses to a haemorrhagic hypotensive challenge and during stepwise exsanguination. The periarteriolar adenosine concentration was measured with enzymatic biosensors inserted in the cortex. After ammonium exposure the arteriolar flow velocity increased by a median (interquartile range) of 21.7% (23.4%) vs. 7.2% (10.2%) in controls (n = 10 and n = 6, respectively, p <0.05), and the arteriolar surface area increased. There was a profound rise in the periarteriolar adenosine concentration. During the hypotensive challenge the flow decreased by 27.8% (14.9%) vs. 9.2% (14.9%) in controls (p <0.05). The lower limit of flow preservation remained unaffected, 27.7 (3.9) mmHg vs. 27.6 (6.4) mmHg, whereas the autoregulatory index increased, 0.29 (0.33) flow units per millimetre of mercury vs. 0.03 (0.21) flow units per millimetre of mercury (p <0.05). When ammonium exposure was combined with topical application of an adenosine receptor antagonist, the autoregulatory index was normalized. Vasodilation of the cerebral microcirculation during exposure to ammonium chloride is associated with an increase in the adenosine tone. Application of a specific adenosine receptor antagonist restores the regulation of the microcirculation. This indicates that adenosine could be a key mediator of the brain dysfunction seen during hyperammonaemia and is a potential therapeutic target. In patients with liver failure, disturbances in brain function are caused in part by ammonium toxicity. In our project we studied how ammonia, through adenosine release, affects the blood flow in the brain of rats. In our experimental model we demonstrated that the detrimental effect of ammonia on blood flow regulation was counteracted by blocking the adenosine receptors in the brain. With this observation we identified a novel potential treatment target. If we can confirm our findings in a future clinical study, this might help patients with liver failure and the severe condition called hepatic encephalopathy. Copyright © 2018 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Rarefaction and blood pressure in systemic and pulmonary arteries

PubMed Central

OLUFSEN, METTE S.; HILL, N. A.; VAUGHAN, GARETH D. A.; SAINSBURY, CHRISTOPHER; JOHNSON, MARTIN

2012-01-01

The effects of vascular rarefaction (the loss of small arteries) on the circulation of blood are studied using a multiscale mathematical model that can predict blood flow and pressure in the systemic and pulmonary arteries. We augmented a model originally developed for the systemic arteries (Olufsen et al. 1998, 1999, 2000, 2004) to (a) predict flow and pressure in the pulmonary arteries, and (b) predict pressure propagation along the small arteries in the vascular beds. The systemic and pulmonary arteries are modelled as separate, bifurcating trees of compliant and tapering vessels. Each tree is divided into two parts representing the `large' and `small' arteries. Blood flow and pressure in the large arteries are predicted using a nonlinear cross-sectional area-averaged model for a Newtonian fluid in an elastic tube with inflow obtained from magnetic resonance measurements. Each terminal vessel within the network of the large arteries is coupled to a vascular bed of small `resistance' arteries, which are modelled as asymmetric structured trees with specified area and asymmetry ratios between the parent and daughter arteries. For the systemic circulation, each structured tree represents a specific vascular bed corresponding to major organs and limbs. For the pulmonary circulation, there are four vascular beds supplied by the interlobar arteries. This manuscript presents the first theoretical calculations of the propagation of the pressure and flow waves along systemic and pulmonary large and small arteries. Results for all networks were in agreement with published observations. Two studies were done with this model. First, we showed how rarefaction can be modelled by pruning the tree of arteries in the microvascular system. This was done by modulating parameters used for designing the structured trees. Results showed that rarefaction leads to increased mean and decreased pulse pressure in the large arteries. Second, we investigated the impact of decreasing vessel compliance in both large and small arteries. Results showed, that the effects of decreased compliance in the large arteries far outweigh the effects observed when decreasing the compliance of the small arteries. We further showed that a decrease of compliance in the large arteries results in pressure increases consistent with observations of isolated systolic hypertension, as occurs in ageing. PMID:22962497

Effect of different dialyzer membranes on cutaneous microcirculation during hemodialysis.

PubMed

Sato, M; Morita, H; Ema, H; Yamaguchi, S; Amano, I

2006-12-01

Biocompatibility profiles of synthetic membranes may vary. In this prospective crossover study, we examined the effect of various membranes on cutaneous microcirculation during HD. 11 HD patients without cardiovascular complications were enrolled in this study. They were dialyzed using three types of membrane in a randomized order: ethylene-vinyl alcohol copolymer (EVAL), vitamin E-bonded cellulose (VE-C) and polysulfone (PS). The transcutaneous oxygen tension (TcPO2) was examined on the dorsum of foot to assess the cutaneous microcirculation. Serum biochemical parameters were also measured. The TcPO2 as a percentage of the predialysis level decreased from the beginning of HD, and significant differences were observed after 15 min of HD between EVAL and the other 2 membranes (98 +/- 6% (mean +/- SD) for EVAL versus 89 +/- 7% for VE-C (p < 0.01) and 88 +/- 10% for PS (p < 0.01)). Furthermore, there were significant differences at 30 and 60 min between EVAL and PS (30 min: 93 +/- 9% for EVAL versus 85 +/- 7% for PS (p < 0.05); 60 min: 92 +/- 10% for EVAL versus 79 +/- 10% for PS (p < 0.01)). The serum level of thiobarbituric acid reactants (TBARs), a marker of lipid peroxidation, increased significantly at the end of HD relative to that at the beginning of HD when using a PS membrane (from 1.9 +/- 0.5 to 2.1 +/- 0.5 nmol/ml, p < 0.05). Our results indicate that an EVAL membrane is superior to PS and VE-C membranes in terms of its smaller influence on cutaneous microcirculation. The repeated occurrence of microcirculatory disturbance during HD sessions may cause chronic endothelial dysfunction and even cardiovascular complications in HD patients.

Inhalation of methane preserves the epithelial barrier during ischemia and reperfusion in the rat small intestine.

PubMed

Mészáros, András T; Büki, Tamás; Fazekas, Borbála; Tuboly, Eszter; Horváth, Kitti; Poles, Marietta Z; Szűcs, Szilárd; Varga, Gabriella; Kaszaki, József; Boros, Mihály

2017-06-01

Methane is part of the gaseous environment of the intestinal lumen. The purpose of this study was to elucidate the bioactivity of exogenous methane on the intestinal barrier function in an antigen-independent model of acute inflammation. Anesthetized rats underwent sham operation or 45-min occlusion of the superior mesenteric artery. A normoxic methane (2.2%)-air mixture was inhaled for 15 min at the end of ischemia and at the beginning of a 60-min or 180-min reperfusion. The integrity of the epithelial barrier of the ileum was assessed by determining the lumen-to-blood clearance of fluorescent dextran, while microvascular permeability changes were detected by the Evans blue technique. Tissue levels of superoxide, nitrotyrosine, myeloperoxidase, and endothelin-1 were measured, the superficial mucosal damage was visualized and quantified, and the serosal microcirculation and mesenteric flow was recorded. Erythrocyte deformability and aggregation were tested in vitro. Reperfusion significantly increased epithelial permeability, worsened macro- and microcirculation, increased the production of proinflammatory mediators, and resulted in a rapid loss of the epithelium. Exogenous normoxic methane inhalation maintained the superficial mucosal structure, decreased epithelial permeability, and improved local microcirculation, with a decrease in reactive oxygen and nitrogen species generation. Both the deformability and aggregation of erythrocytes improved with incubation of methane. Normoxic methane decreases the signs of oxidative and nitrosative stress, improves tissue microcirculation, and thus appears to modulate the ischemia-reperfusion-induced epithelial permeability changes. These findings suggest that the administration of exogenous methane may be a useful strategy for maintaining the integrity of the mucosa sustaining an oxido-reductive attack. Copyright © 2017 Elsevier Inc. All rights reserved.

Calf Muscle Oxygen Saturation During Six-Minute Walk Test And Its Relationship With Walking Impairment In Symptomatic Peripheral Artery Disease.

PubMed

Andrade-Lima, Aluísio; Cucato, Gabriel G; Domingues, Wagner J R; Germano-Soares, Antônio H; Cavalcante, Bruno R; Correia, Marilia A; Saes, Glauco F; Wolosker, Nelson; Gardner, Andrew W; Zerati, Antônio E; Ritti-Dias, Raphael M

2018-05-21

Impaired microcirculation is associated with poor walking capacity in symptomatic peripheral artery disease (PAD) patients during treadmill test, however, this test does not simulate the efforts of daily walking of these patients. Thus, the aim of the study was to describe the microcirculation responses during six-minute walk test (6MWT) and to analyze the relationship between microcirculation indicators and walking impairment in symptomatic PAD patients. Thirty-four patients were included (mean age = 67.6 ± 11.2). The clinical characteristics were collected and they performed a 6MWT in which initial claudication distance (ICD) and total walking distance (TWD) were recorded. During and after the 6MWT, calf muscle oxygen saturation (StO 2 ) parameters were monitored continuously to measure microcirculation behavior. The association between calf muscle StO 2 parameters and walking impairment was analyzed by Pearson or Spearman correlations. Walking impairment was not associated with any StO 2 parameters during exercise. In contrast, after 6MWT, recovery time of StO 2 (r = -0.472, P = .008) and recovery time to maximal StO 2 (r= -0.402, P = .019) were negatively correlated with ICD. Furthermore, the distance walked under claudication symptoms (ΔTWD - ICD) was positively correlated with recovery time to maximal StO 2 (r = 0.347, P = .048). In symptomatic PAD patients, shorter ICD values during a 6MWT are associated with a delayed recovery in calf muscle StO 2 after exercise. Calf muscle StO 2 parameters decrease subtly during 6MWT, suggesting that the degree of ischemia in the calf muscle during ground walking, simulating efforts of the daily walking, is relatively low. Copyright © 2018 Elsevier Inc. All rights reserved.

Early Healing Events after Periodontal Surgery: Observations on Soft Tissue Healing, Microcirculation, and Wound Fluid Cytokine Levels.

PubMed

Kaner, Doğan; Soudan, Mouaz; Zhao, Han; Gaßmann, Georg; Schönhauser, Anna; Friedmann, Anton

2017-01-27

Early wound healing after periodontal surgery with or without enamel matrix derivative/biphasic calcium phosphate (EMD/BCP) was characterized in terms of soft tissue closure, changes of microcirculation, and expression of pro- and anti-inflammatory cytokines in gingival crevicular fluid/wound fluid (GCF/WF). Periodontal surgery was carried out in 30 patients (18 patients: application of EMD/BCP for regeneration of bony defects; 12 patients: surgical crown lengthening (SCL)). Healthy sites were observed as untreated controls. GCF/WF samples were collected during two post-surgical weeks. Flap microcirculation was measured using laser Doppler flowmetry (LDF). Soft tissue healing was evaluated after two weeks. GCF/WF levels of interleukin 1β (IL-1β), tumour necrosis factor (TNF-α), IL-6, and IL-10 were determined using a multiplex immunoassay. Surgery caused similar reductions of flap microcirculation followed by recovery within two weeks in both EMD/BCP and SCL groups. GCF/WF and pro-inflammatory cytokine levels were immediately increased after surgery, and returned only partially to baseline levels within the two-week observation period. Levels of IL-10 were temporarily reduced in all surgical sites. Flap dehiscence caused prolonged elevated levels of GCF/WF, IL-1β, and TNF-α. These findings show that periodontal surgery triggers an immediate inflammatory reaction corresponding to the early inflammatory phase of wound healing, and these inflammation measures are temporary in case of maintained closure of the flap. However, flap dehiscence causes prolonged inflammatory exudation from the periodontal wound. If the biological pre-conditions for periodontal wound healing are considered important for the clinical outcome, care should be taken to maintain primary closure of the flap.

Thermodiffusion for continuous quantification of hepatic microcirculation--validation and potential in liver transplantation.

PubMed

Klar, E; Kraus, T; Bleyl, J; Newman, W H; Bowman, H F; Hofmann, W J; Kummer, R; Bredt, M; Herfarth, C

1999-09-01

Hepatic microcirculation is a main determinant of reperfusion injury and graft quality in liver transplantation. Methods available for the quantification of hepatic microcirculation are indirect, are invasive, or preclude postoperative application. The aim of this study was the validation of thermodiffusion in a new modification allowing long-term use in the clinical setting. In six pigs Doppler flowmeters were positioned around the hepatic artery and portal vein for the measurement of total liver blood flow. Liver perfusion was quantified by thermodiffusion and compared to H(2) clearance as an established technique under baseline conditions, during different degrees of portal venous obstruction and during occlusion of the hepatic artery. Thermodiffusion measurements were recorded for five days postoperatively followed by histological evaluation of the hepatic puncture site. Perfusion data obtained by thermodiffusion were significantly correlated to H(2) clearance (r = 0.94, P < 0. 001) and to liver blood flow (r = 0.9, P < 0.05). The agreement between thermodiffusion and H(2) clearance was excellent (mean difference -2.1 ml/100 g/min; limits of agreement -12.5 and 8.3 ml/100 g/min). Occlusion of the portal vein or hepatic artery was immediately detected by thermodiffusion, indicating a decrease of perfusion by 64 +/- 7% or 27 +/- 5% of baseline, respectively. Perfusion values at baseline and during vascular occlusion were reproducible during the entire observation period. Histological changes of the liver tissue adjacent to the thermodiffusion probes were minute and did not influence long-term measurements. In vivo validation proved that enhanced thermodiffusion is a minimally invasive technique for the continuous, real-time quantification of hepatic microcirculation. Changes in liver perfusion can be safely detected over several days postoperatively. The implication for liver transplantation has led to the clinical application of thermodiffusion. Copyright 1999 Academic Press.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menikoff, Ralph

The Zel’dovich-von Neumann-Doering (ZND) profile of a detonation wave is derived. Two basic assumptions are required: i. An equation of state (EOS) for a partly burned explosive; P(V, e, λ). ii. A burn rate for the reaction progress variable; d/dt λ = R(V, e, λ). For a steady planar detonation wave the reactive flow PDEs can be reduced to ODEs. The detonation wave profile can be determined from an ODE plus algebraic equations for points on the partly burned detonation loci with a specified wave speed. Furthermore, for the CJ detonation speed the end of the reaction zone is sonic.more » A solution to the reactive flow equations can be constructed with a rarefaction wave following the detonation wave profile. This corresponds to an underdriven detonation wave, and the rarefaction is know as a Taylor wave.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yasuda, H.; Chong, C.; Charalampidis, E. G.

Here, we investigate the nonlinear wave dynamics of origami-based metamaterials composed of Tachi-Miura polyhedron (TMP) unit cells. These cells exhibit strain softening behavior under compression, which can be tuned by modifying their geometrical configurations or initial folded conditions. We assemble these TMP cells into a cluster of origami-based metamaterials, and we theoretically model and numerically analyze their wave transmission mechanism under external impact. Numerical simulations show that origami-based metamaterials can provide a prototypical platform for the formation of nonlinear coherent structures in the form of rarefaction waves, which feature a tensile wavefront upon the application of compression to the system.more » We also demonstrate the existence of numerically exact traveling rarefaction waves in an effective lumped-mass model. Origami-based metamaterials can be highly useful for mitigating shock waves, potentially enabling a wide variety of engineering applications.« less

Aerothermodynamics of Satellite During Atmospheric Reentry for the Whole Range of Gas Rarefaction: Influence of Inelastic Intermolecular Collisions

NASA Astrophysics Data System (ADS)

Kozak, Dalton Vinicius; Sharipov, Felix

2012-08-01

The aerothermodynamic characteristics of the Brazilian satellite Satélite de Reentrada Atmosférica were calculated for orbital-flight and atmospheric-reentry conditions with the direct simulation Monte Carlo method for a diatomic gas. The internal modes of molecule energy in the intermolecular interaction, such as the rotational energy, were taken into account. The numerical calculations cover a range of gas rarefactions wide enough to embrace the free-molecule and hydrodynamic regimes. Two Mach numbers were considered: 10 and 20. Numerical results include the drag force of the satellite, the energy flux, pressure coefficient, and skin friction coefficient over the satellite surface, the density and temperature distributions, and streamlines of the gas flow around the satellite. The influence of the satellite temperature upon these characteristics was evaluated at different satellite temperatures.

Pickup ion acceleration in the successive appearance of corotating interaction regions

NASA Astrophysics Data System (ADS)

Tsubouchi, K.

2017-04-01

Acceleration of pickup ions (PUIs) in an environment surrounded by a pair of corotating interaction regions (CIRs) was investigated by numerical simulations using a hybrid code. Energetic particles associated with CIRs have been considered to be a result of the acceleration at their shock boundaries, but recent observations identified the ion flux peaks in the sub-MeV to MeV energy range in the rarefaction region, where two separate CIRs were likely connected by the magnetic field. Our simulation results confirmed these observational features. As the accelerated PUIs repeatedly bounce back and forth along the field lines between the reverse shock of the first CIR and the forward shock of the second one, the energetic population is accumulated in the rarefaction region. It was also verified that PUI acceleration in the dual CIR system had two different stages. First, because PUIs have large gyroradii, multiple shock crossing is possible for several tens of gyroperiods, and there is an energy gain in the component parallel to the magnetic field via shock drift acceleration. Second, as the field rarefaction evolves and the radial magnetic field becomes dominant, Fermi-type reflection takes place at the shock. The converging nature of two shocks results in a net energy gain. The PUI energy acquired through these processes is close to 0.5 MeV, which may be large enough for further acceleration, possibly resulting in the source of anomalous cosmic rays.

Reversing cooling flows with AGN jets: shock waves, rarefaction waves and trailing outflows

NASA Astrophysics Data System (ADS)

Guo, Fulai; Duan, Xiaodong; Yuan, Ye-Fei

2018-01-01

The cooling flow problem is one of the central problems in galaxy clusters, and active galactic nucleus (AGN) feedback is considered to play a key role in offsetting cooling. However, how AGN jets heat and suppress cooling flows remains highly debated. Using an idealized simulation of a cool-core cluster, we study the development of central cooling catastrophe and how a subsequent powerful AGN jet event averts cooling flows, with a focus on complex gasdynamical processes involved. We find that the jet drives a bow shock, which reverses cooling inflows and overheats inner cool-core regions. The shocked gas moves outward in a rarefaction wave, which rarefies the dense core and adiabatically transports a significant fraction of heated energy to outer regions. As the rarefaction wave propagates away, inflows resume in the cluster core, but a trailing outflow is uplifted by the AGN bubble, preventing gas accumulation and catastrophic cooling in central regions. Inflows and trailing outflows constitute meridional circulations in the cluster core. At later times, trailing outflows fall back to the cluster centre, triggering central cooling catastrophe and potentially a new generation of AGN feedback. We thus envisage a picture of cool cluster cores going through cycles of cooling-induced contraction and AGN-induced expansion. This picture naturally predicts an anti-correlation between the gas fraction (or X-ray luminosity) of cool cores and the central gas entropy, which may be tested by X-ray observations.

Correction for frequency-dependent hydrophone response to nonlinear pressure waves using complex deconvolution and rarefactional filtering: application with fiber optic hydrophones.

PubMed

Wear, Keith; Liu, Yunbo; Gammell, Paul M; Maruvada, Subha; Harris, Gerald R

2015-01-01

Nonlinear acoustic signals contain significant energy at many harmonic frequencies. For many applications, the sensitivity (frequency response) of a hydrophone will not be uniform over such a broad spectrum. In a continuation of a previous investigation involving deconvolution methodology, deconvolution (implemented in the frequency domain as an inverse filter computed from frequency-dependent hydrophone sensitivity) was investigated for improvement of accuracy and precision of nonlinear acoustic output measurements. Timedelay spectrometry was used to measure complex sensitivities for 6 fiber-optic hydrophones. The hydrophones were then used to measure a pressure wave with rich harmonic content. Spectral asymmetry between compressional and rarefactional segments was exploited to design filters used in conjunction with deconvolution. Complex deconvolution reduced mean bias (for 6 fiber-optic hydrophones) from 163% to 24% for peak compressional pressure (p+), from 113% to 15% for peak rarefactional pressure (p-), and from 126% to 29% for pulse intensity integral (PII). Complex deconvolution reduced mean coefficient of variation (COV) (for 6 fiber optic hydrophones) from 18% to 11% (p+), 53% to 11% (p-), and 20% to 16% (PII). Deconvolution based on sensitivity magnitude or the minimum phase model also resulted in significant reductions in mean bias and COV of acoustic output parameters but was less effective than direct complex deconvolution for p+ and p-. Therefore, deconvolution with appropriate filtering facilitates reliable nonlinear acoustic output measurements using hydrophones with frequency-dependent sensitivity.

Dependence of thresholds for pulmonary capillary hemorrhage on diagnostic ultrasound frequency.

PubMed

Miller, Douglas L; Dou, Chunyan; Raghavendran, Krishnan

2015-06-01

Pulmonary ultrasound examination has become routine for diagnosis in many clinical and point-of-care medical settings. However, the phenomenon of pulmonary capillary hemorrhage (PCH) induction during diagnostic ultrasound imaging presents a poorly understood risk factor. PCH was observed in anesthetized rats exposed to 1.5-, 4.5- and 12.0-MHz diagnostic ultrasound to investigate the frequency dependence of PCH thresholds. PCH was detected in the ultrasound images as growing comet tail artifacts and was assessed using photographs of the surface of excised lungs. Previous photographs acquired after exposure to 7.6-MHz diagnostic ultrasound were included for analysis. In addition, at each frequency we measured dosimetric parameters, including peak rarefactional pressure amplitude and spatial peak, pulse average intensity attenuated by rat chest wall samples. Peak rarefactional pressure amplitude thresholds determined at each frequency, based on the proportion of PCH in groups of five rats, were 1.03 ± 0.02, 1.28 ± 0.14, 1.18 ± 0.12 and 1.36 ± 0.15 MPa at 1.5, 4.5, 7.6 and 12.0 MHz, respectively. Although the PCH lesions decreased in size with increasing ultrasonic frequency, owing to the smaller beam widths and scan lengths, the peak rarefactional pressure amplitude thresholds remained approximately constant. This dependence was different from that of the mechanical index, which indicates a need for a specific dosimetric parameter for safety guidance in pulmonary ultrasound. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Comparative Evaluation of Enalapril and Losartan in Pharmacological Correction of Experimental Osteoporosis and Fractures of Its Background

PubMed Central

Rajkumar, D. S. R.; Faitelson, A. V.; Gudyrev, O. S.; Dubrovin, G. M.; Pokrovski, M. V.; Ivanov, A. V.

2013-01-01

In the experiment on the white Wistar female rats (222 animals), the osteoprotective effect of enalapril and losartan was studied on experimental models of osteoporosis and osteoporotic fractures. It was revealed that in rats after ovariectomy, the endothelial dysfunction of microcirculation vessels of osteal tissue develops, resulting in occurrence of osteoporosis and delay of consolidation of experimental fractures. Enalapril and losartan prevented the reduction of microcirculation in bone, which was reflected in slowing the thinning of bone trabeculae and in preventing the occurrence of these microfractures, as well as increasing quality of experimental fractures healing. PMID:23401845

Skin microcirculation and vasopressin infusion: a laser Doppler study

PubMed Central

Bernard, Francis; Vinet, Alain; Verdant, Colin

2006-01-01

Use of arginine vasopressin in the management of refractory vasodilatory shock has been associated with development of ischaemic skin lesions. Because of the increasing popularity of arginine vasopressin, it is important to evaluate its effects on microcirculatory blood flow. Such studies are crucial if we are to appreciate the microcirculatory consequences of our various resuscitation strategies. However, methodological issues must always be considered because they can significantly influence interpretation of the results. Some aspects of use of laser Doppler to evaluate the microcirculation are reviewed within the context of recent findings presented by Luckner and coworkers in this issue of Critical Care. PMID:16594988

Effect of zero magnetic field on cardiovascular system and microcirculation

NASA Astrophysics Data System (ADS)

Gurfinkel, Yu. I.; At'kov, O. Yu.; Vasin, A. L.; Breus, T. K.; Sasonko, M. L.; Pishchalnikov, R. Yu.

2016-02-01

The effects of zero magnetic field conditions on cardiovascular system of healthy adults have been studied. In order to generate zero magnetic field, the facility for magnetic fields modeling ;ARFA; has been used. Parameters of the capillary blood flow, blood pressure, and the electrocardiogram (ECG) monitoring were measured during the study. All subjects were tested twice: in zero magnetic field and, for comparison, in sham condition. The obtained results during 60 minutes of zero magnetic field exposure demonstrate a clear effect on cardiovascular system and microcirculation. The results of our experiments can be used in studies of long-term stay in hypo-magnetic conditions during interplanetary missions.

Structural and functional bases of laser-microvessels interaction

NASA Astrophysics Data System (ADS)

Kozlov, Valentine I.; Terman, Oleg A.; Builin, Vitalij; Lebedeva, Natalia A.; Samoilov, Nickolai

1993-07-01

Structural and functional microcirculatory changes in tissues and organs (muscles, liver, derma, epinephros, brain cortex) under various dosages and powers of laser irradiation in the red (633 nm) and near infrared (890 nm) spectrum regions have been studied in experiments and clinic. In case of nonsensitized tissues the `photoactivation' range of power densities and doses of laser irradiation has been established. We have identified a short-term reaction of microvessels and a long-term reaction (adaptation). The former consists of intensification of microcirculation and metabolism rise in parenchymatous cells; the latter is connected with neoangiogenesis acceleration. The intensification of the blood microcirculation includes a dilation of microvessels of all orders, an amplification of arteriolar vasomotions and an opening of `reserved' capillaries. Data on the structural reconstruction of myocytes and endotheliocytes have shown that the high differential parenchymatous cells and its membrane structures are sensitive to low energy laser irradiation and, on the other hand, under low energy laser irradiation there is an activation of synthetic processes in the cells. Thus, during the laser-tissue interaction in such complex system as human organism the microcirculation plays the key role among the other systems.

Diffusing wave spectroscopy and its application for monitoring of skin blood microcirculation

NASA Astrophysics Data System (ADS)

Meglinski, Igor V.

2003-10-01

Diffusing Wave Spectroscopy (DWS) is a novel modern technique uniquely suited for the non-invasive measurements of the particles size and their motion within the randomly inhomogeneous highly scattering and absorbing media, including biological tissues as a human skin. The technique is based on the illuminating the media (tissues) with a coherent laser light, and analyzing the loss of coherence of the scattered field arises from motion of the scattering particles with respect to each other. Both theoretical and experimental results has shown the potentialities and viability of DWS application for the express non-invasive quantitative monitoring and functional diagnostics of skin blood microcirculation, with down to 1 μm/sec resolution. This is likely lead to quantitative monitoring in general diagnostics, diabetes studies, pharmacological intervention for the failing surgical skin flaps or replants, blood microcirculation monitoring during sepsis, assess burn depth, diagnose atherosclerotic disease, and investigate mechanisms of photodynamic therapy for cancer treatment. In frame of current report we describe the recent developments of DWS further to the point that skin blood micro-flow can be routinely and accurately obtained in a separate skin vascular bed on normal skin tissues.

Anatomical evaluation of oral microcirculation: capillary characteristics associated with sex or age group.

PubMed

Scardina, Giuseppe Alessandro; Giuseppe Alessandro, Scardina; Cacioppo, Antonino; Antonino, Cacioppo; Messina, Pietro

2009-10-01

There are various types of oral mucosa specific to different parts of the mouth and each of these has a unique histological structure. The variations in the epithelial structure are consistently related to observable differences in the underlying microcirculation: i.e. differences in the course, conformation, and density of capillaries. The aim of this research has been to investigate oral microcirculatory differences between men and women as well as between various age groups, in order to map the oral mucosa, and to highlight changes occurring during aging. A total of 45 healthy subjects were enrolled for this study (12 men and 33 women; mean age 60.37; range 30-82). A complete in-vivo videocapillaroscopic mapping of the oral mucosa was done on each subject. The capillaroscopic patterns of the various areas differ particularly in the course of the loops in relation to the mucosal surface. On the basis of statistical analysis of the collected data, it emerges that there are many differences in capillary loop density between men and women and between different age groups. This study demonstrates the necessity of approaching the investigation of patient microcirculation in different ways depending on sex or age.

Imaging photoplethysmography for clinical assessment of cutaneous microcirculation at two different depths

NASA Astrophysics Data System (ADS)

Marcinkevics, Zbignevs; Rubins, Uldis; Zaharans, Janis; Miscuks, Aleksejs; Urtane, Evelina; Ozolina-Moll, Liga

2016-03-01

The feasibility of bispectral imaging photoplethysmography (iPPG) system for clinical assessment of cutaneous microcirculation at two different depths is proposed. The iPPG system has been developed and evaluated for in vivo conditions during various tests: (1) topical application of vasodilatory liniment on the skin, (2) skin local heating, (3) arterial occlusion, and (4) regional anesthesia. The device has been validated by the measurements of a laser Doppler imager (LDI) as a reference. The hardware comprises four bispectral light sources (530 and 810 nm) for uniform illumination of skin, video camera, and the control unit for triggering of the system. The PPG signals were calculated and the changes of perfusion index (PI) were obtained during the tests. The results showed convincing correlations for PI obtained by iPPG and LDI at (1) topical liniment (r=0.98) and (2) heating (r=0.98) tests. The topical liniment and local heating tests revealed good selectivity of the system for superficial microcirculation monitoring. It is confirmed that the iPPG system could be used for assessment of cutaneous perfusion at two different depths, morphologically and functionally different vascular networks, and thus utilized in clinics as a cost-effective alternative to the LDI.

Imaging photoplethysmography for clinical assessment of cutaneous microcirculation at two different depths.

PubMed

Marcinkevics, Zbignevs; Rubins, Uldis; Zaharans, Janis; Miscuks, Aleksejs; Urtane, Evelina; Ozolina-Moll, Liga

2016-03-01

The feasibility of bispectral imaging photoplethysmography (iPPG) system for clinical assessment of cutaneous microcirculation at two different depths is proposed. The iPPG system has been developed and evaluated for in vivo conditions during various tests: (1) topical application of vasodilatory liniment on the skin, (2) skin local heating, (3) arterial occlusion, and (4) regional anesthesia. The device has been validated by the measurements of a laser Doppler imager (LDI) as a reference. The hardware comprises four bispectral light sources (530 and 810 nm) for uniform illumination of skin, video camera, and the control unit for triggering of the system. The PPG signals were calculated and the changes of perfusion index (PI) were obtained during the tests. The results showed convincing correlations for PI obtained by iPPG530 nm and LDI at (1) topical liniment (r = 0.98) and (2) heating (r = 0.98) tests. The topical liniment and local heating tests revealed good selectivity of the system for superficial microcirculation monitoring. It is confirmed that the iPPG system could be used for assessment of cutaneous perfusion at two different depths, morphologically and functionally different vascular networks, and thus utilized in clinics as a cost-effective alternative to the LDI.

Label-free in vivo optical imaging of functional microcirculations within meninges and cortex in mice

PubMed Central

Jia, Yali; Wang, Ruikang K.

2010-01-01

Abnormal microcirculation within meninges is common in many neurological diseases. There is a need for an imaging method that is capable of monitoring dynamic meningeal microcirculations, preferably decoupled from cortical blood flow. Optical microangiography (OMAG) is a recently developed label-free imaging method capable of producing 3D images of dynamic blood perfusion within micro-circulatory tissue beds at an imaging depth up to ~2 mm, with an unprecedented imaging sensitivity to blood flow at ~4 µm/s. In this paper, we demonstrate the utility of OMAG in imaging the detailed blood flow distributions, at a capillary level resolution, within the meninges and cortex in mice with the cranium left intact. Using a thrombotic mouse model, we show that the OMAG can yield longitudinal measurements of meningeal vascular responses to the insult and can decouple these responses from those in the cortex, giving valuable information regarding the localized hemodynamics along with the dynamic formation of thrombotic event. The results indicate that OMAG can be a useful tool to study therapeutic strategies in preclinical animal models in order to mitigate various pathologies that are mainly related to the meningeal circulations. PMID:20933005

[Angina pectoris and coronary insufficiency with a normal coronary angiogram: pathophysiological principles, diagnosis and therapeutic consequences].

PubMed

Strauer, B E

1988-01-01

The clinical syndrome "coronary insufficience at normal coronary arteriogram" is found in approximately 10-20% of patients with exercise-induced coronary insufficience. In most of these cases disturbances of coronary microcirculation are present. They can appear in vascular diseases (arterial hypertension, systemic immunopathies, immune complex vasculitis, etc.), in rheological diseases (paraproteinemia, hyperlipoproteinemia, polyglobulia, etc.), and in disturbances of transport and diffusion of oxygen (carbon monoxide intoxication, methemoglobinemia, hyperlipoproteinemia). The clinical diagnosis is based on usual diagnostic programs (electrocardiogram, exercise electrocardiogram, responsiveness to nitroglycerin, etc.), as well as on newer, functionally orientated diagnostic procedures (determinations of coronary blood flow and of coronary vascular reserve, production of lactate, serological findings, histology and immune histology of peripheral arteries, measurements of viscosities in both plasma and blood, etc.). Many clinically relevant disturbances in coronary microcirculation can thus be detected and treated on a rational basis by the management of the internal main disease, that is, by the treatment of the vascular, rheological, and metabolic disorders. Persistent angina pectoris in the presence of normal coronary arteriogram represents no termination of coronary diagnostics, but moreover implies the clinical task for using diagnostic possibilities to enable functional and therapeutical assessment of coronary microcirculation.

Quantification of Macrocirculation and Microcirculation in Brain Using Ultrasound Perfusion Imaging.

PubMed

Vinke, Eline J; Eyding, Jens; de Korte, Chris; Slump, Cornelis H; van der Hoeven, Johannes G; Hoedemaekers, Cornelia W E

2018-01-01

The aim of this study was to investigate the feasibility of simultaneous visualization of the cerebral macrocirculation and microcirculation, using ultrasound perfusion imaging (UPI). In addition, we studied the sensitivity of this technique for detecting changes in cerebral blood flow (CBF). We performed an observational study in ten healthy volunteers. Ultrasound contrast was used for UPI measurements during normoventilation and hyperventilation. For the data analysis of the UPI measurements, an in-house algorithm was used to visualize the DICOM files, calculate parameter images and select regions of interest (ROIs). Next, time intensity curves (TIC) were extracted and perfusion parameters calculated. Both volume- and velocity-related perfusion parameters were significantly different between the macrocirculation and the parenchymal areas. Hyperventilation-induced decreases in CBF were detectable by UPI in both the macrocirculation and microcirculation, most consistently by the volume-related parameters. The method was safe, with no adverse effects in our population. Bedside quantification of CBF seems feasible and the technique has a favourable safety profile. Adjustment of current method is required to improve its diagnostic accuracy. Validation studies using a 'gold standard' are needed to determine the added value of UPI in neurocritical care monitoring.

Protective effects of a selective neutrophil elastase inhibitor (sivelestat) on lipopolysaccharide-induced acute dysfunction of the pulmonary microcirculation.

PubMed

Inoue, Yoshiaki; Seiyama, Akitoshi; Tanaka, Hiroshi; Ukai, Isao; Akimau, Pavel; Nishino, Masato; Shimazu, Takeshi; Sugimoto, Hisashi

2005-08-01

The purpose of this study was to evaluate the effect of a neutrophil elastase inhibitor, sivelestat, on lipopolysaccharide-induced acute lung injury through analysis of hemodynamic changes in the pulmonary microcirculation. Randomized animal study. Medical school laboratory. Twenty-seven Wistar rats (15 rats for microspectroscopic observations, 12 rats for measurements of neutrophil elastase activity and wet-to-dry ratio). Thoracosternotomy was performed on male Wistar rats under continuous anesthesia and mechanical ventilation. Rats were divided into three groups (n = 5 each groups) on the basis of the reagent used: lipopolysaccharide group (100 microg/kg lipopolysaccharide intravenously), sivelestat group (10 mg/kg sivelestat; 100 microg/kg lipopolysaccharide intravenously), and control group (saline only, intravenously). We measured morphologic changes and hemodynamic variables, including tissue blood flow, erythrocyte velocity, erythrocyte count, thickness of interalveolar septa, and leukocyte adhesion in the pulmonary microcirculation, with a video-rate (33 msec/frame) dual-spot microspectroscopy system (DSMSS) and a laser-Doppler flowmeter. Blood-free wet-to-dry ratio and neutrophil elastase activity in bronchoalveolar lavage fluid, serum, and supernatant of lung homogenate were measured in another set of experiments (n = 4 for each group). Sixty minutes after lipopolysaccharide administration, severe thickening of the interalveolar septa was observed in the lipopolysaccharide but not the sivelestat group. In the lipopolysaccharide group, DSMSS measurements of erythrocyte velocity and hemoglobin oxygenation in single capillaries were decreased significantly (vs. control p < .05, vs. sivelestat p < .01), whereas tissue blood flow and erythrocyte velocity measurements from laser-Doppler flowmeter were increased significantly (vs. control p < .05, vs. sivelestat p < .01). The number of adherent leukocytes was increased significantly in the lipopolysaccharide group at 30, 45, and 60 mins after lipopolysaccharide administration (vs. control p < .01, vs. sivelestat p < .05). The number of adherent leukocytes did not increase in the sivelestat group. The wet-to-dry ratio was significantly higher in the lipopolysaccharide group than in control (p < .05) and sivelestat (p < .05) groups. Neutrophil elastase activities in the bronchoalveolar lavage fluid, serum, and lung tissue were all significantly lower in the sivelestat group than in the lipopolysaccharide group (p < .05). Lipopolysaccharide induces leukocyte adhesion in the pulmonary microcirculation, resulting in decreased tissue hemoglobin oxygen and alveolar and interstitial edema. The selective neutrophil elastase inhibitor sivelestat reduces neutrophil elastase activity and attenuates acute changes in the pulmonary microcirculation.

EFFECTS OF LOW-FREQUENCY ULTRASOUND ON MICROCIRCULATION IN VENOUS LEG ULCERS

PubMed Central

Wollina, Uwe; Heinig, Birgit; Naumann, Gunther; Scheibe, Armin; Schmidt, Wolf-Dieter; Neugebauer, Reimund

2011-01-01

Background: Therapeutic low-frequency ultrasound (US) has been used for many years to improve wound healing in chronic wounds like venous leg ulcers. No human data are available for the possible effects of single US applications on microcirculation and their frequency-dependency. Aims: To investigated the role of therapeutic low-frequency US on microcirculation of venous leg ulcers in vivo. Patients and Methods: This is a pilot study on an inpatient basis. We use a newly developed low-frequency continuous-wave US-equipment composed of a US transducer based on piezo-fiber composites that allow the change of frequency. In this study, we apply US of 34 kHz, 53.5 kHz, and 75 kHz respectively. Twelve patients with chronic venous leg ulcers are analyzed. As an adjunct to good ulcer care, therapeutic US is applied, non-contacting, once a day, in a subaqual position for 10 minutes. Microcirculation is assessed in the ulcers adjacent to skin before US-therapy, immediately after the treatment and 30 minutes later. We use a micro-light guide spectrophotometer (O2C, LEA Medizintechnik GmbH, Gieίen, Germany) for calculation of blood flow velocity, hemoglobin oxygen saturation (SCO2) and relative hemoglobin concentration (rHb) in 2 and 8 mm depth. Contact-free remission spectroscopy (SkinREM3, Color Control Chemnitz GmbH, Chemnitz, Germany) allows contact free measurements in the VIS-NIR range of the spectrum (400 ± 1600 nm). Results: It is seen that therapeutic US is well tolerated. One patient dropped out from a treatment series since he developed erysipelas responding to standard antibiotic. Effects were seen at 34 kHz only. The SO2 values increased after single US application. The values for rHb were higher in the superficial layer of the wound bed (depth 2 mm) compared to deeper parts (8 mm depth). US treatment did not result in significant changes of rHb and blood cell velocity. The data obtained by remission spectroscopy disclose an increase of oxygenized hemoglobin. Conclusions: The major findings are that continuous-wave low-frequency US of 34 kHz, but not, 53.5 kHz or 75 kHz, has a temporary stimulatory effect on microcirculation mainly due to an improved oxygenation. Further studies with treatment series are necessary. PMID:21716543

Numerical modeling of fluid and oxygen exchanges through microcirculation for the assessment of microcirculation alterations caused by type 2 diabetes.

PubMed

Tang, Yuanliang; He, Ying

2018-05-01

Type 2 diabetes mellitus (DM2) is frequently accompanied by microcirculation complications, including structural and functional alterations, which may have serious effects on substance exchanges between blood and interstitial tissue and the health of organs. In this paper, we aim to study the influence of microcirculation alterations in DM2 patients on fluid and oxygen exchanges through a model analysis. A fluid flow and oxygen transport model were developed by considering the interplay between blood in capillary network and interstitial tissue. The two regions were separately represented by 1D network model and 3D volume model, and the immersed boundary method (IBM) was adopted to solve fluid and mass transfer between these two regions. By using the model, the steady flow field and the distributions of oxygen in capillary network and surrounding tissue were firstly simulated. In the interstitial volume, fluid pressure and oxygen tension decreased with the increase of distance from the network; in the network, oxygen tension in blood plasma dropped from 100 mm Hg at the entrance to about 40 mm Hg at the exit. We further tested several structural and functional disorders related to diabetic pathological conditions. Simulated results show that the impaired connectivity of the network could result in poor robustness in maintaining blood flow and perfused surface; under high fluid permeability conditions of capillary walls, the pressure gradient was much larger around the capillary bed, and this alteration led to a saturation level of the interstitial pressure when lymphatic flow drainage can't work effectively; the variations in network connectivity and permeability of capillary wall also had unfavorable influence on oxygen distributions in interstitial tissue. In addition, when the oxygen releasing capacity of hemoglobin was confined by glycosylated hemoglobin (HbA1) in the case of diabetes, the plasma could not be complemented with adequate oxygen and thus the hypoxic tissue range will be extended. This study illustrates that when microcirculation disturbances, including the structure of capillary network, the wall osmosis property and the capacity of blood binding oxygen occur in DM2, some negative impacts are raised on microvascular hemodynamics and metabolism circumstance of interstitial tissue. Copyright © 2018 Elsevier Inc. All rights reserved.

Location and analysis of acoustic infrasound pulses in lightning

NASA Astrophysics Data System (ADS)

Arechiga, R.; Stock, M.; Thomas, R.; Erives, H.; Rison, W.; Edens, H.; Lapierre, J.

2014-07-01

Acoustic, VHF, and electrostatic measurements throw new light onto the origin and production mechanism of the thunder infrasound signature (<10 Hz) from lightning. This signature, composed of an initial compression followed by a rarefaction pulse, has been the subject of several unconfirmed theories and models. The observations of two intracloud flashes which each produced multiple infrasound pulses were analyzed for this work. Once the variation of the speed of sound with temperature is taken into account, both the compression and rarefaction portions of the infrasound pulses are found to originate very near lightning channels mapped by the Lightning Mapping Array. We found that none of the currently proposed models can explain infrasound generation by lightning, and thus propose an alternate theory: The infrasound compression pulse is produced by electrostatic interaction of the charge deposited on the channel and in the streamer zone of the lightning channel.

Response of Jupiter's auroras to conditions in the interplanetary medium as measured by the Hubble Space Telescope and Juno

NASA Astrophysics Data System (ADS)

Nichols, J. D.; Badman, S. V.; Bagenal, F.; Bolton, S. J.; Bonfond, B.; Bunce, E. J.; Clarke, J. T.; Connerney, J. E. P.; Cowley, S. W. H.; Ebert, R. W.; Fujimoto, M.; Gérard, J.-C.; Gladstone, G. R.; Grodent, D.; Kimura, T.; Kurth, W. S.; Mauk, B. H.; Murakami, G.; McComas, D. J.; Orton, G. S.; Radioti, A.; Stallard, T. S.; Tao, C.; Valek, P. W.; Wilson, R. J.; Yamazaki, A.; Yoshikawa, I.

2017-08-01

We present the first comparison of Jupiter's auroral morphology with an extended, continuous, and complete set of near-Jupiter interplanetary data, revealing the response of Jupiter's auroras to the interplanetary conditions. We show that for ˜1-3 days following compression region onset, the planet's main emission brightened. A duskside poleward region also brightened during compressions, as well as during shallow rarefaction conditions at the start of the program. The power emitted from the noon active region did not exhibit dependence on any interplanetary parameter, though the morphology typically differed between rarefactions and compressions. The auroras equatorward of the main emission brightened over ˜10 days following an interval of increased volcanic activity on Io. These results show that the dependence of Jupiter's magnetosphere and auroras on the interplanetary conditions are more diverse than previously thought.

Review of blunt body wake flows at hypersonic low density conditions

NASA Technical Reports Server (NTRS)

Moss, J. N.; Price, J. M.

1996-01-01

Recent results of experimental and computational studies concerning hypersonic flows about blunted cones including their near wake are reviewed. Attention is focused on conditions where rarefaction effects are present, particularly in the wake. The experiments have been performed for a common model configuration (70 deg spherically-blunted cone) in five hypersonic facilities that encompass a significant range of rarefaction and nonequilibrium effects. Computational studies using direct simulation Monte Carlo (DSMC) and Navier-Stokes solvers have been applied to selected experiments performed in each of the facilities. In addition, computations have been made for typical flight conditions in both Earth and Mars atmospheres, hence more energetic flows than produced in the ground-based tests. Also, comparisons of DSMC calculations and forebody measurements made for the Japanese Orbital Reentry Experiment (OREX) vehicle (a 50 deg spherically-blunted cone) are presented to bridge the spectrum of ground to flight conditions.

Community assessment techniques and the implications for rarefaction and extrapolation with Hill numbers.

PubMed

Cox, Kieran D; Black, Morgan J; Filip, Natalia; Miller, Matthew R; Mohns, Kayla; Mortimor, James; Freitas, Thaise R; Greiter Loerzer, Raquel; Gerwing, Travis G; Juanes, Francis; Dudas, Sarah E

2017-12-01

Diversity estimates play a key role in ecological assessments. Species richness and abundance are commonly used to generate complex diversity indices that are dependent on the quality of these estimates. As such, there is a long-standing interest in the development of monitoring techniques, their ability to adequately assess species diversity, and the implications for generated indices. To determine the ability of substratum community assessment methods to capture species diversity, we evaluated four methods: photo quadrat, point intercept, random subsampling, and full quadrat assessments. Species density, abundance, richness, Shannon diversity, and Simpson diversity were then calculated for each method. We then conducted a method validation at a subset of locations to serve as an indication for how well each method captured the totality of the diversity present. Density, richness, Shannon diversity, and Simpson diversity estimates varied between methods, despite assessments occurring at the same locations, with photo quadrats detecting the lowest estimates and full quadrat assessments the highest. Abundance estimates were consistent among methods. Sample-based rarefaction and extrapolation curves indicated that differences between Hill numbers (richness, Shannon diversity, and Simpson diversity) were significant in the majority of cases, and coverage-based rarefaction and extrapolation curves confirmed that these dissimilarities were due to differences between the methods, not the sample completeness. Method validation highlighted the inability of the tested methods to capture the totality of the diversity present, while further supporting the notion of extrapolating abundances. Our results highlight the need for consistency across research methods, the advantages of utilizing multiple diversity indices, and potential concerns and considerations when comparing data from multiple sources.

Growth and regression of vasculature in healthy and diabetic mice after hindlimb ischemia.

PubMed

Landázuri, Natalia; Joseph, Giji; Guldberg, Robert E; Taylor, W Robert

2012-07-01

The formation of vascular networks during embryogenesis and early stages of development encompasses complex and tightly regulated growth of blood vessels, followed by maturation of some vessels, and spatially controlled disconnection and pruning of others. The adult vasculature, while more quiescent, is also capable of adapting to changing physiological conditions by remodeling blood vessels. Numerous studies have focused on understanding key factors that drive vessel growth in the adult in response to ischemic injury. However, little is known about the extent of vessel rarefaction and its potential contribution to the final outcome of vascular recovery. We addressed this topic by characterizing the endogenous phases of vascular repair in a mouse model of hindlimb ischemia. We showed that this process is biphasic. It encompasses an initial rapid phase of vessel growth, followed by a later phase of vessel rarefaction. In healthy mice, this process resulted in partial recovery of perfusion and completely restored the ability of mice to run voluntarily. Given that the ability to revascularize can be compromised by a cardiovascular risk factor such as diabetes, we also examined vascular repair in diabetic mice. We found that paradoxically both the initial growth and subsequent regression of collateral vessels were more pronounced in the setting of diabetes and resulted in impaired recovery of perfusion and impaired functional status. In conclusion, our findings demonstrate that the formation of functional collateral vessels in the hindlimb requires vessel growth and subsequent vessel rarefaction. In the setting of diabetes, the physiological defect was not in the initial formation of vessels but rather in the inability to sustain newly formed vessels.

Systemic influences contribute to prolonged microvascular rarefaction after brain irradiation: a role for endothelial progenitor cells

PubMed Central

Ashpole, Nicole M.; Warrington, Junie P.; Mitschelen, Matthew C.; Yan, Han; Sosnowska, Danuta; Gautam, Tripti; Farley, Julie A.; Csiszar, Anna; Ungvari, Zoltan

2014-01-01

Whole brain radiation therapy (WBRT) induces profound cerebral microvascular rarefaction throughout the hippocampus. Despite the vascular loss and localized cerebral hypoxia, angiogenesis fails to occur, which subsequently induces long-term deficits in learning and memory. The mechanisms underlying the absence of vessel recovery after WBRT are unknown. We tested the hypotheses that vascular recovery fails to occur under control conditions as a result of loss of angiogenic drive in the circulation, chronic tissue inflammation, and/or impaired endothelial cell production/recruitment. We also tested whether systemic hypoxia, which is known to promote vascular recovery, reverses these chronic changes in inflammation and endothelial cell production/recruitment. Ten-week-old C57BL/6 mice were subjected to a clinical series of fractionated WBRT: 4.5-Gy fractions 2 times/wk for 4 wk. Plasma from radiated mice increased in vitro endothelial cell proliferation and adhesion compared with plasma from control mice, indicating that WBRT did not suppress the proangiogenic drive. Analysis of cytokine levels within the hippocampus revealed that IL-10 and IL-12(p40) were significantly increased 1 mo after WBRT; however, systemic hypoxia did not reduce these inflammatory markers. Enumeration of endothelial progenitor cells (EPCs) in the bone marrow and circulation indicated that WBRT reduced EPC production, which was restored with systemic hypoxia. Furthermore, using a bone marrow transplantation model, we determined that bone marrow-derived endothelial-like cells home to the hippocampus after systemic hypoxia. Thus, the loss of production and homing of EPCs have an important role in the prolonged vascular rarefaction after WBRT. PMID:25038144

Evaluation of Laser Speckle Contrast Imaging for the Assessment of Oral Mucosal Blood Flow following Periodontal Plastic Surgery: An Exploratory Study

PubMed Central

Molnár, Eszter; Molnár, Bálint; Lohinai, Zsolt; Tóth, Zsuzsanna; Benyó, Zoltán; Hricisák, Laszló; Windisch, Péter

2017-01-01

The laser speckle contrast imaging (LSCI) is proved to be a reliable tool in flap monitoring in general surgery; however, it has not been evaluated in oral surgery yet. We applied the LSCI to compare the effect of a xenogeneic collagen matrix (Geistlich Mucograft®) to connective tissue grafts (CTG) on the microcirculation of the modified coronally advanced tunnel technique (MCAT) for gingival recession coverage. Gingival microcirculation and wound fluid were measured before and after surgery for six months at twenty-seven treated teeth. In males, the flap microcirculation was restored within 3 days for both grafts followed by a hyperemic response. During the first 8 days the blood flow was higher at xenogeneic graft comparing to the CTG. In females, the ischemic period lasted for 7–12 days depending on the graft and no hyperemic response was observed. Females had more intense and prolonged wound fluid production. The LSCI method is suitable to capture the microcirculatory effect of the surgical intervention in human oral mucosa. The application of xenogeneic collagen matrices as a CTG substitute does not seem to restrain the recovery of graft bed circulation. Gender may have an effect on postoperative circulation and inflammation. PMID:28232940

Impact of different antithrombotics on the microcirculation and viability of perforator-based ischaemic skin flaps in a small animal model.

PubMed

Fichter, Andreas M; Ritschl, Lucas M; Robitzky, Luisa K; Wagenpfeil, Stefan; Mitchell, David A; Wolff, Klaus-Dietrich; Mücke, Thomas

2016-10-21

The effects of antithrombotic drugs on random and free flap survival have been investigated in the past, but the experimental and clinical results are not in agreement. A perforator-based critical ischaemia model was used to evaluate the effects of different perioperatively administered pharmaceutical agents on tissue ischaemia and to assess the potential additional haemorheological or vasodilative effects of antithrombotics on flap microcirculation. Combined laser Doppler flowmetry and remission spectroscopy revealed an increase in certain microcirculation parameters in most groups in comparison with saline controls, and these changes correlated with flap survival. Clopidogrel and hirudin significantly improved the amount of viable flap tissue in comparison with controls, while unfractioned heparin had a negative effect on flap survival. Low molecular weight heparin, aspirin, pentoxifylline, and hydroxyethyl starch had no impact on the amount of viable flap tissue. A higher complication rate was observed in all experimental groups, but only clopidogrel had a negative impact on the flap viability. Our results add to the body of evidence supporting the conclusion that perioperative antithrombotic treatment improves flap survival. Clopidogrel and hirudin are effective pharmacological agents that significantly increased the viability of perforator-based skin flaps in rats, but at a higher risk of postoperative bleeding.

Evaluation of Laser Speckle Contrast Imaging for the Assessment of Oral Mucosal Blood Flow following Periodontal Plastic Surgery: An Exploratory Study.

PubMed

Molnár, Eszter; Molnár, Bálint; Lohinai, Zsolt; Tóth, Zsuzsanna; Benyó, Zoltán; Hricisák, Laszló; Windisch, Péter; Vág, János

2017-01-01

The laser speckle contrast imaging (LSCI) is proved to be a reliable tool in flap monitoring in general surgery; however, it has not been evaluated in oral surgery yet. We applied the LSCI to compare the effect of a xenogeneic collagen matrix (Geistlich Mucograft®) to connective tissue grafts (CTG) on the microcirculation of the modified coronally advanced tunnel technique (MCAT) for gingival recession coverage. Gingival microcirculation and wound fluid were measured before and after surgery for six months at twenty-seven treated teeth. In males, the flap microcirculation was restored within 3 days for both grafts followed by a hyperemic response. During the first 8 days the blood flow was higher at xenogeneic graft comparing to the CTG. In females, the ischemic period lasted for 7-12 days depending on the graft and no hyperemic response was observed. Females had more intense and prolonged wound fluid production. The LSCI method is suitable to capture the microcirculatory effect of the surgical intervention in human oral mucosa. The application of xenogeneic collagen matrices as a CTG substitute does not seem to restrain the recovery of graft bed circulation. Gender may have an effect on postoperative circulation and inflammation.

Anethole and eugenol reduce in vitro and in vivo leukocyte migration induced by fMLP, LTB4, and carrageenan.

PubMed

Estevão-Silva, Camila Fernanda; Kummer, Raquel; Fachini-Queiroz, Fernanda Carolina; Grespan, Renata; Nogueira de Melo, Gessilda Alcântara; Baroni, Silmara; Cuman, Roberto Kenji Nakamura; Bersani-Amado, Ciomar Aparecida

2014-07-01

The aim of this study was to investigate the effect of anethole (AN) and eugenol (EUG) on leukocyte migration using in vitro chemotaxis and in situ microcirculation assays. BALB/c mice were used for the in vitro chemotaxis assay, and Wistar rats for the in situ microcirculation assay. We evaluated (a) the in vitro leukocyte migration in response to chemotactic factors (formyl-methionyl-leucyl-phenylalanine [fMLP] and leukotriene B4 [LTB4]) and (b) the rolling, adhesion, and migration of leukocytes induced by an injection of carrageenan (100 µg/cavity) into the scrotum of the animal. In the in vitro chemotaxis assay, AN and EUG at doses of 1, 3, 9, and 27 µg/ml significantly inhibited leukocyte migration when stimulated by the chemotactic agents fMLP and LTB4. In the in situ microcirculation assay, AN at doses of 125 and 250 mg/kg and EUG at a dose of 250 mg/kg significantly decreased the number of leukocytes that rolled, adhered, and migrated to perivascular tissue. The results indicate that AN and EUG exert inhibitory effects on leukocyte migration, highlighting their possible use to diminish excessive leukocyte migration in the inflammatory process.

Optical monitoring of cerebral microcirculation in neurointensive care.

PubMed

Rejmstad, Peter; Haj-Hosseini, Neda; Åneman, Oscar; Wårdell, Karin

2017-12-08

Continuous optical monitoring of local cerebral microcirculation could benefit neurointensive care patients treated for subarachnoid hemorrhage (SAH). The aim of the study was to evaluate laser Doppler flowmetry (LDF) and diffuse reflectance spectroscopy (DRS) for long-term monitoring of brain microcirculation and oxygen saturation (SO 2 ) in the neurointensive care unit (NICU). A fiber optic probe was designed for intraparenchymal use and connected to LDF and DRS for assessment of the local blood flow (perfusion and tissue reflectance (TLI)) and SO 2 in the brain. The optically monitored parameters were compared with conventional NICU monitors and Xe-CT. The LDF signals were low with median and 25 to 75% interquartiles of perfusion = 70 (59 to 83) a.u. and TLI = 2.0 (1.0 to 2.4) a.u. and showed correlation with the NICU monitors in terms of heart rate. Median and interquartiles of SO 2 were 17.4 (15.7 to 19.8) %. The lack of correlation between local perfusion and cerebral perfusion pressure indicated intact cerebral autoregulation. The systems were capable of monitoring both local perfusion and SO 2 with stable signals in the NICU over 4 days. Further clinical studies are required to evaluate the optical systems' potential for assessing the onset of secondary brain injury.

Improvement of small intestinal microcirculation by postconditioning after lower limb ischemia.

PubMed

Turóczi, Zsolt; Fülöp, András; Czigány, Zoltán; Varga, Gabriella; Rosero, Oliver; Tökés, Tünde; Kaszaki, József; Lotz, Gábor; Harsányi, László; Szijártó, Attila

2015-03-01

Major lower limb vascular surgeries may result in severe, remote injury of the gastrointestinal system, which has high mortality rates. Postconditioning is a technique with potential capability of reducing remote gastrointestinal complications. Our aim was to assess the remote macro- and micro-hemodynamic changes of the small intestine following an infrarenal aortic occlusion and to evaluate the effects of postconditioning on these alterations. Rats underwent 3h of infrarenal aortic occlusion followed by 4h of reperfusion. In one group, postconditioning was applied. Blood pressure, superior mesenteric artery flow and mucosal microcirculation of the duodenum, jejunum and ileum were assessed. Samples were taken from each intestinal segment for histological examinations. Superior mesenteric artery flow, as well as microcirculation of the duodenum, jejunum and ileum showed significant impairment in the IR group, while histological damage was significantly worsened. Postconditioning was able to limit flow reduction in all three small bowel segments and in the superior mesenteric artery, and was able to significantly reduce histological damage. Strong negative correlation was found between microcirculatory values and histological damage. Microcirculatory impairment might be responsible for remote intestinal injury following infrarenal aortic occlusion. Postconditioning was able to reduce this remote intestinal damage. Copyright © 2015 Elsevier Inc. All rights reserved.

Monitoring of small lymphatics function under different impact on animal model by integrated optical imaging

NASA Astrophysics Data System (ADS)

Galanzha, Ekaterina I.; Tuchin, Valery V.; Chowdhury, Parimal; Zharov, Vladimir P.

2004-08-01

The digital transmission microscopy is very informative, noninvasive for vessels, simple and available method for studying and measuring lymph microvessels function in vivo. Rat mesentery can use as promising animal model of lymph microvessels in vivo. Such imaging system allowed visualizing the entire lymphangion (with input and output valves), its wall, lymphatic valves, lymph flow as well as single cells in flow; obtaining anew basic information on lymph microcirculation and quantitative data on lymphatic function including indexes of phasic contractions and valve function, the quantitative parameters of lymph-flow velocity. Rat mesentery is good model to create different types of lymphedemas in acute and chronic experiments. The obtained data revealed that significant edema started immediately after lymph node dissection in one-half of cases and was accompanied by lymphatic disturbances. The greatest degree of edema was found after 1 week. After 4 weeks, the degree of edema sometimes decreased, but functional lymphatic disturbances progressed. Nicotine had significant direct dose-dependent effect on microlymphatic function at the acute local application, but the same dose of this drug was not effect on microcirculation in chronic intoxication. Despite yielding interesting data, transmittance microscopy had some limitations when applied to microcirculation studies. The problems could be solved at the application of integrated measuring technique.

Effect of Tea Theaflavins and Catechins on Microvascular Function

PubMed Central

Fuchs, Dagmar; de Graaf, Young; van Kerckhoven, Roeland; Draijer, Richard

2014-01-01

Beneficial effects of flavonoid-rich black and green tea on macrocirculation have been well established. Theaflavins are unique to black tea as they are formed from catechins during the enzymatic oxidation of tea leaves. The study was performed to gain more insight into the effects of theaflavins on microcirculation and to compare effects with another important flavonoid class, the green tea derived catechins, which have been reported to improve vascular function. Twenty-four healthy subjects were included in a double-blind, placebo-controlled, randomised, cross-over study. On six different days, subjects received capsules with a single dose of catechins (500 mg), four varying doses of theaflavins (100 to 500 mg) or placebo. Microcirculation was assessed after each treatment by Pulse Amplitude Tonometry (EndoPAT) at baseline and 2, 4 and 6 h after test product intake. The EndoPAT reactive hyperemia response was improved by 500 mg catechins (reactive hyperemia index (RHI): 0.2; p = 0.04) and by 500 mg theaflavins (RHI: 0.19; p = 0.06) compared to placebo. Also, 300 mg theaflavins increased the RHI (0.28; p = 0.02), but no effects were observed at lower doses. The study suggests moderate effects of single doses of catechins and theaflavins on peripheral microcirculation. PMID:25514559

Evaluation of a pointwise microcirculation assessment method using liquid and multilayered tissue simulating phantoms

NASA Astrophysics Data System (ADS)

Fredriksson, Ingemar; Saager, Rolf B.; Durkin, Anthony J.; Strömberg, Tomas

2017-11-01

A fiber-optic probe-based instrument, designed for assessment of parameters related to microcirculation, red blood cell tissue fraction (fRBC), oxygen saturation (S), and speed resolved perfusion, has been evaluated using state-of-the-art tissue phantoms. The probe integrates diffuse reflectance spectroscopy (DRS) at two source-detector separations and laser Doppler flowmetry, using an inverse Monte Carlo method for identifying the parameters of a multilayered tissue model. Here, we characterize the accuracy of the DRS aspect of the instrument using (1) liquid blood phantoms containing yeast and (2) epidermis-dermis mimicking solid-layered phantoms fabricated from polydimethylsiloxane, titanium oxide, hemoglobin, and coffee. The root-mean-square (RMS) deviations for fRBC for the two liquid phantoms were 11% and 5.3%, respectively, and 11% for the solid phantoms with highest hemoglobin signatures. The RMS deviation for S was 5.2% and 2.9%, respectively, for the liquid phantoms, and 2.9% for the solid phantoms. RMS deviation for the reduced scattering coefficient (μs‧), for the solid phantoms was 15% (475 to 850 nm). For the liquid phantoms, the RMS deviation in average vessel diameter (D) was 1 μm. In conclusion, the skin microcirculation parameters fRBC and S, as well as, μs‧ and D are estimated with reasonable accuracy.

[Microcirculatory blood and lymph flow examination in eyelid skin by laser Doppler flowmetry].

PubMed

Safonova, T N; Kintyukhina, N P; Sidorov, V V; Gladkova, O V; Reyn, E S

to study normal blood and lymph microcirculation of the upper and lower eyelids in different age groups. The study included 108 volunteers (216 eyes) aged from 20 to 80 years with no signs of changes in anterior segment structures, who were grouped by age ranges (20-30 years, 31-40 years, 41-50 years, 51-60 years, 61-70 years, and 71-80 years) into 6 groups equal in gender and quantitative composition. In all volunteers, microcirculation of the upper and lower eyelids was examined by laser Doppler flowmetry (LDF) ('LASMA MC-1' peripheral blood and lymph flow analyzer and 'LASMA MC' laser diagnostic complex, LASMA LLC). The average perfusion changes in blood and lymph flow as well as blood and lymph flow oscillations were analyzed. Blood and lymph flow in the microvasculature of the upper and lower eyelids is variable and depends on neither the age, nor gender of the test subject. On LDF-gram, every increase in amplitude of blood flow corresponds to a decrease in that of lymph flow. The non-invasive method of LDF expands our diagnostic capabilities as it enables assessment of not only blood, but also lymph flow. The data obtained can serve as a starting point for exploring microcirculation in different age groups in the presence of different pathological processes.

Effects of carbogen on cochlear blood flow and hearing function following acute acoustic trauma in guinea pigs.

PubMed

Zhao, Jing; Sun, Jianjun; Liu, Yang

2012-10-01

Disturbances of microcirculation and hemorheological changes in the inner ear are the results of noise-induced hearing loss (NIHL). Both the disturbances of microcirculation and hemorheological changes are the etiologies of NIHL development, but they are also the results. Although previous reports that inhalation of high concentration of CO(2) may increase cochlear blood flow (CoBF), the effects of carbogen on the cochlear microcirculation and NIHL remain unclear. Changes induced by noise, carbogen and pure oxygen within the cochlear lateral wall microvasculature and in hearing thresholds were observed in guinea pigs using intravital microscopy and the auditory brainstem response. At the same time, arterial oxygen saturation and morphologic changes of cochlear hair cells were observed. Carbogen inhalation increased vessel diameters and blood flow velocities. Hearing thresholds elevation in the carbogen group was smaller than those in the control and oxygen group (p <0.05). Carbogen inhalation produced a trend toward less threshold shift after noise exposure, which reached statistical significance after day 3 (p <0.01). Respiratory acidosis was not found in our study. The segmented basal membranes of Corti in three groups indicated that no losses or discorders of hair cells were found. Carbogen inhalation can preserve hearing in animal models after acute acoustic trauma. Copyright © 2012 IMSS. All rights reserved.

Cerebral Microcirculation and Oxygen Tension in the Human Secondary Cortex

PubMed Central

Linninger, A. A.; Gould, I. G.; Marinnan, T.; Hsu, C.-Y.; Chojecki, M.; Alaraj, A.

2013-01-01

The three-dimensional spatial arrangement of the cortical microcirculatory system is critical for understanding oxygen exchange between blood vessels and brain cells. A three-dimensional computer model of a 3 × 3 × 3 mm3 subsection of the human secondary cortex was constructed to quantify oxygen advection in the microcirculation, tissue oxygen perfusion, and consumption in the human cortex. This computer model accounts for all arterial, capillary and venous blood vessels of the cerebral microvascular bed as well as brain tissue occupying the extravascular space. Microvessels were assembled with optimization algorithms emulating angiogenic growth; a realistic capillary bed was built with space filling procedures. The extravascular tissue was modeled as a porous medium supplied with oxygen by advection–diffusion to match normal metabolic oxygen demand. The resulting synthetic computer generated network matches prior measured morphometrics and fractal patterns of the cortical microvasculature. This morphologically accurate, physiologically consistent, multi-scale computer network of the cerebral microcirculation predicts the oxygen exchange of cortical blood vessels with the surrounding gray matter. Oxygen tension subject to blood pressure and flow conditions were computed and validated for the blood as well as brain tissue. Oxygen gradients along arterioles, capillaries and veins agreed with in vivo trends observed recently in imaging studies within experimental tolerances and uncertainty. PMID:23842693

High-Efficiency Multiscale Modeling of Cell Deformations in Confined Microenvironments in Microcirculation and Microfluidics

NASA Astrophysics Data System (ADS)

Lu, Huijie; Peng, Zhangli

2017-11-01

We developed a high-efficiency multiscale modeling method to predict the stress and deformation of cells during the interactions with their microenvironments in microcirculation and microfluidics, including red blood cells (RBCs) and circulating tumor cells (CTCs). There are more than 1 billion people in the world suffering from RBC diseases. The mechanical properties of RBCs are changed in these diseases due to molecular structure alternations, which is not only important for understanding the disease pathology but also provides an opportunity for diagnostics. On the other hand, the mechanical properties of cancer cells are also altered compared to healthy cells. This can lead to acquired ability to cross the narrow capillary networks and endothelial gaps, which is crucial for metastasis, the leading cause of cancer mortality. Therefore, it is important to predict the deformation and stress of RBCs and CTCs in microcirculations. We develop a high-efficiency multiscale model of cell-fluid interaction. We pass the information from our molecular scale models to the cell scale to study the effect of molecular mutations. Using our high-efficiency boundary element methods of fluids, we will be able to run 3D simulations using a single CPU within several hours, which will enable us to run extensive parametric studies and optimization.

Dynamic Flow Velocity Mapping from Fluorescent Dye Transit Times in the Brain Surface Microcirculation of Anesthetized Rats and Mice.

PubMed

Hoshikawa, Ryo; Kawaguchi, Hiroshi; Takuwa, Hiroyuki; Ikoma, Yoko; Tomita, Yutaka; Unekawa, Miyuki; Suzuki, Norihiro; Kanno, Iwao; Masamoto, Kazuto

2016-08-01

This study aimed to develop a new method for mapping blood flow velocity based on the spatial evolution of fluorescent dye transit times captured with CLSFM in the cerebral microcirculation of anesthetized rodents. The animals were anesthetized with isoflurane, and a small amount of fluorescent dye was intravenously injected to label blood plasma. The CLSFM was conducted through a closed cranial window to capture propagation of the dye in the cortical vessels. The transit time of the dye over a certain distance in a single vessel was determined with automated image analyses, and average flow velocity was mapped in each vessel. The average flow velocity measured in the rat pial artery and vein was 4.4 ± 1.2 and 2.4 ± 0.5 mm/sec, respectively. A similar range of flow velocity to those of the rats was observed in the mice; 4.9 ± 1.4 and 2.0 ± 0.9 mm/sec, respectively, although the vessel diameter in the mice was about half of that in the rats. Flow velocity in the cerebral microcirculation can be mapped based on fluorescent dye transit time measurements with conventional CLSFM in experimental animals. © 2016 John Wiley & Sons Ltd.

Label-free in vivo optical imaging of functional microcirculations within meninges and cortex in mice.

PubMed

Jia, Yali; Wang, Ruikang K

2010-12-15

Abnormal microcirculation within meninges is common in many neurological diseases. There is a need for an imaging method that is capable of monitoring dynamic meningeal microcirculations, preferably decoupled from cortical blood flow. Optical microangiography (OMAG) is a recently developed label-free imaging method capable of producing 3D images of dynamic blood perfusion within micro-circulatory tissue beds at an imaging depth up to ∼2 mm, with an unprecedented imaging sensitivity to blood flow at ∼4 μm/s. In this paper, we demonstrate the utility of OMAG in imaging the detailed blood flow distributions, at a capillary level resolution, within the meninges and cortex in mice with the cranium left intact. Using a thrombotic mouse model, we show that the OMAG can yield longitudinal measurements of meningeal vascular responses to the insult and can decouple these responses from those in the cortex, giving valuable information regarding the localized hemodynamics along with the dynamic formation of thrombotic event. The results indicate that OMAG can be a useful tool to study therapeutic strategies in preclinical animal models in order to mitigate various pathologies that are mainly related to the meningeal circulations. Copyright © 2010 Elsevier B.V. All rights reserved.

Amazon rainforest exchange of carbon and subcanopy air flow: Manaus LBA site--a complex terrain condition.

PubMed

Tóta, Julio; Fitzjarrald, David Roy; da Silva Dias, Maria A F

2012-01-01

On the moderately complex terrain covered by dense tropical Amazon Rainforest (Reserva Biologica do Cuieiras--ZF2--02°36'17.1'' S, 60°12'24.4'' W), subcanopy horizontal and vertical gradients of the air temperature, CO(2) concentration and wind field were measured for the dry and wet periods in 2006. We tested the hypothesis that horizontal drainage flow over this study area is significant and can affect the interpretation of the high carbon uptake rates reported by previous works at this site. A similar experimental design as the one by Tóta et al. (2008) was used with a network of wind, air temperature, and CO(2) sensors above and below the forest canopy. A persistent and systematic subcanopy nighttime upslope (positive buoyancy) and daytime downslope (negative buoyancy) flow pattern on a moderately inclined slope (12%) was observed. The microcirculations observed above the canopy (38 m) over the sloping area during nighttime presents a downward motion indicating vertical convergence and correspondent horizontal divergence toward the valley area. During the daytime an inverse pattern was observed. The micro-circulations above the canopy were driven mainly by buoyancy balancing the pressure gradient forces. In the subcanopy space the microcirculations were also driven by the same physical mechanisms but probably with the stress forcing contribution. The results also indicated that the horizontal and vertical scalar gradients (e.g., CO(2)) were modulated by these micro-circulations above and below the canopy, suggesting that estimates of advection using previous experimental approaches are not appropriate due to the tridimensional nature of the vertical and horizontal transport locally. This work also indicates that carbon budget from tower-based measurement is not enough to close the system, and one needs to include horizontal and vertical advection transport of CO(2) into those estimates.

In vivo imaging of mammalian cochlear blood flow using fluorescence microendoscopy.

PubMed

Monfared, Ashkan; Blevins, Nikolas H; Cheung, Eunice L M; Jung, Juergen C; Popelka, Gerald; Schnitzer, Mark J

2006-02-01

We sought to develop techniques for visualizing cochlear blood flow in live mammalian subjects using fluorescence microendoscopy. Inner ear microcirculation appears to be intimately involved in cochlear function. Blood velocity measurements suggest that intense sounds can alter cochlear blood flow. Disruption of cochlear blood flow may be a significant cause of hearing impairment, including sudden sensorineural hearing loss. However, inability to image cochlear blood flow in a nondestructive manner has limited investigation of the role of inner ear microcirculation in hearing function. Present techniques for imaging cochlear microcirculation using intravital light microscopy involve extensive perturbations to cochlear structure, precluding application in human patients. The few previous endoscopy studies of the cochlea have suffered from optical resolution insufficient for visualizing cochlear microvasculature. Fluorescence microendoscopy is an emerging minimally invasive imaging modality that provides micron-scale resolution in tissues inaccessible to light microscopy. In this article, we describe the use of fluorescence microendoscopy in live guinea pigs to image capillary blood flow and movements of individual red blood cells within the basal turn of the cochlea. We anesthetized eight adult guinea pigs and accessed the inner ear through the mastoid bulla. After intravenous injection of fluorescein dye, we made a limited cochleostomy and introduced a compound doublet gradient refractive index endoscope probe 1 mm in diameter into the inner ear. We then imaged cochlear blood flow within individual vessels in an epifluorescence configuration using one-photon fluorescence microendoscopy. We observed single red blood cells passing through individual capillaries in several cochlear structures, including the round window membrane, spiral ligament, osseous spiral lamina, and basilar membrane. Blood flow velocities within inner ear capillaries varied widely, with observed speeds reaching up to approximately 500 microm/s. Fluorescence microendoscopy permits visualization of cochlear microcirculation with micron-scale optical resolution and determination of blood flow velocities through analysis of video sequences.

Temporal and spatiotemporal variability in comprehensive forearm skin microcirculation assessment during occlusion protocols.

PubMed

Strömberg, Tomas; Sjöberg, Folke; Bergstrand, Sara

2017-09-01

Forearm skin hyperemia during release after brachial occlusion has been proposed for evaluating peripheral arterial disease and endothelial dysfunction. We used a novel fiberoptic system integrating Laser Doppler Flowmetry and Diffuse Reflectance Spectroscopy for a comprehensive pointwise model based microcirculation characterization. The aim was to evaluate and compare the temporal and the spatiotemporal variabilities in forearm skin microcirculation parameters (speed resolved perfusion; low speed <1mm/s, Perf SR, <1 ; mid-speed 1-10mm/s, high speed >10mm/s, and total perfusion (Perf SR, tot ); the concentration and oxygenation of red blood cells, C RBC and S O2 ). Ten healthy subjects underwent arterial and venous forearm occlusions (AO, VO), repeated within one week. The repeatability was calculated as the coefficient of variation (CV) and the agreement as the intra-class correlation coefficient (ICC). The temporal CVs for conventional perfusion, Perf conv , Perf SR, tot , C RBC and S O2 were 14%, 12%, 9% and 9%, respectively, while the ICC were >0.75 (excellent). The perfusion measures generally had a higher spatiotemporal than temporal variability, which was not the case for S O2 and C RBC . The corresponding spatiotemporal CVs were 33%, 32%, 18% and 15%, respectively. During VO, C RBC had a CV<35% and ICC>0.40 (fair-good), and after release this was the case for C RBC (AO and VO), S O2 (VO) and Perf SR, <1 (VO). In conclusion, the skin microcirculation parameters showed excellent temporal repeatability, while the spatiotemporal repeatability especially for perfusion was poorer. The parameters with acceptable repeatability and fair-good agreement were: C RBC during and after release of VO, the Perf SR, <1 after release of VO, the S O2 and the C RBC after release of AO. However, the value of these parameters in discriminating endothelial function remains to be studied. Copyright © 2017 Elsevier Inc. All rights reserved.

Amazon Rainforest Exchange of Carbon and Subcanopy Air Flow: Manaus LBA Site—A Complex Terrain Condition

PubMed Central

Tóta, Julio; Roy Fitzjarrald, David; da Silva Dias, Maria A. F.

2012-01-01

On the moderately complex terrain covered by dense tropical Amazon Rainforest (Reserva Biologica do Cuieiras—ZF2—02°36′17.1′′ S, 60°12′24.4′′ W), subcanopy horizontal and vertical gradients of the air temperature, CO2 concentration and wind field were measured for the dry and wet periods in 2006. We tested the hypothesis that horizontal drainage flow over this study area is significant and can affect the interpretation of the high carbon uptake rates reported by previous works at this site. A similar experimental design as the one by Tóta et al. (2008) was used with a network of wind, air temperature, and CO2 sensors above and below the forest canopy. A persistent and systematic subcanopy nighttime upslope (positive buoyancy) and daytime downslope (negative buoyancy) flow pattern on a moderately inclined slope (12%) was observed. The microcirculations observed above the canopy (38 m) over the sloping area during nighttime presents a downward motion indicating vertical convergence and correspondent horizontal divergence toward the valley area. During the daytime an inverse pattern was observed. The micro-circulations above the canopy were driven mainly by buoyancy balancing the pressure gradient forces. In the subcanopy space the microcirculations were also driven by the same physical mechanisms but probably with the stress forcing contribution. The results also indicated that the horizontal and vertical scalar gradients (e.g., CO2) were modulated by these micro-circulations above and below the canopy, suggesting that estimates of advection using previous experimental approaches are not appropriate due to the tridimensional nature of the vertical and horizontal transport locally. This work also indicates that carbon budget from tower-based measurement is not enough to close the system, and one needs to include horizontal and vertical advection transport of CO2 into those estimates. PMID:22619608

Microcirculation and structural reorganization of the bladder mucosa in chronic cystitis under conditions of ozone therapy.

PubMed

Neimark, A I; Nepomnyashchikh, L M; Lushnikova, E L; Bakarev, M A; Abdullaev, N A; Sizov, K A

2014-01-01

Structural reorganization of the bladder mucosa in chronic cystitis and its correction by ozone therapy were studied. A relationship between the epithelial layer restructuring of different kinds (dystrophy, metaplasia, and degeneration), level of cell proliferation, and ultrastructural organization of urotheliocytes was detected. This complex of structural reactions was combined with dysregulation of tissue bloodflow in the bladder mucosa, shown by laser Doppler flowmetry. Positive structural changes were most marked in intravesical and less so in parenteral ozone therapy added to the therapeutic complex and manifested in reduction of inflammation and alteration in parallel with more intense reparative reactions. A special feature of parenteral ozone therapy was a significant improvement of microcirculation in the bladder mucosa.

Ultrasound microscope: the new field in ultrasound diagnostics

NASA Astrophysics Data System (ADS)

Novyc'kyy, Victor V.; Lushchyk, Ulyana B.

2001-06-01

A device which is a new stage in the development of medical equipment has been developed. The device works as an ultrasound microscope in vivo and provides 4 up to 32 colored histological image. It gives possibility to estimate tissue acoustic density with the help of 4 up to 32 gradation coloring different tissues and enables tissue microcirculation visualization. With the help of the device a doctor can objectify fatty hepatitis and cirrhosis, edema of different organs and tissues as well as microcirculation in organs and tissues (e.g. muscles, myocard and bone system). New promising applications of ultrasound systems in diagnostics and for choosing individual treatment tactics, with pathogenesis being taken into account, may be developed with the help of the device.

An endoscopic laser Doppler flowmetry of a gastroduodenal mucosa at bleeding ulcer

NASA Astrophysics Data System (ADS)

Shapkin, U. G.; Kapralov, C. V.; Gogolev, A. A.; Lychagov, V. V.; Tuchin, V. V.

2006-08-01

One of the important problems of a bleeding gastroduodenal ulcer surgery is a prognosis of the recurrent hemorrhage and appraisal of endoscopic hemostasis quality. Endoscopic Laser Doppler Flowmetry of a mucous coat of stomach and a duodenum was made on 34 patients for the purpose of investigation of features of microcirculation. Analogous researches are made on 30 patients with a peptic ulcer and on 28 practically healthy people. Analysis of LDF-grams has shown certain differences in regional microcirculations in stomach and duodenal at normal and at a pathology. Increase of regional perfusion in periulcerose zone with its pathology disbalance can serve as a criterion for activities of an alteration processes in gastroduodenal ulcer defining the risk of possible hemorrhage.

Maturation of the auditory system in clinically normal puppies as reflected by the brain stem auditory-evoked potential wave V latency-intensity curve and rarefaction-condensation differential potentials.

PubMed

Poncelet, L C; Coppens, A G; Meuris, S I; Deltenre, P F

2000-11-01

To evaluate auditory maturation in puppies. Ten clinically normal Beagle puppies. Puppies were examined repeatedly from days 11 to 36 after birth (8 measurements). Click-evoked brain stem auditory-evoked potentials (BAEP) were obtained in response to rarefaction and condensation click stimuli from 90 dB normal hearing level to wave V threshold, using steps of 10 dB. Responses were added, providing an equivalent to alternate polarity clicks, and subtracted, providing the rarefaction-condensation differential potential (RCDP). Steps of 5 dB were used to determine thresholds of RCDP and wave V. Slope of the low-intensity segment of the wave V latency-intensity curve was calculated. The intensity range at which RCDP could not be recorded (ie, pre-RCDP range) was calculated by subtracting the threshold of wave V from threshold of RCDP RESULTS: Slope of the wave V latency-intensity curve low-intensity segment evolved with age, changing from (mean +/- SD) -90.8 +/- 41.6 to -27.8 +/- 4.1 micros/dB. Similar results were obtained from days 23 through 36. The pre-RCDP range diminished as puppies became older, decreasing from 40.0 +/- 7.5 to 20.5 +/- 6.4 dB. Changes in slope of the latency-intensity curve with age suggest enlargement of the audible range of frequencies toward high frequencies up to the third week after birth. Decrease in the pre-RCDP range may indicate an increase of the audible range of frequencies toward low frequencies. Age-related reference values will assist clinicians in detecting hearing loss in puppies.

The Radial Variation of the Solar Wind Temperature-Speed Relationship

NASA Astrophysics Data System (ADS)

Elliott, H. A.; McComas, D. J.

2010-12-01

Generally, the solar wind temperature (T) and speed (V) are well correlated except in Interplanetary Coronal Mass Ejections where this correlation breaks down. We have shown that at 1 AU the speed-temperature relationship is often well represented by a linear fit for a speed range spanning both the slow and fast wind. By examining all of the ACE and OMNI measurements, we found that when coronal holes are large the fast wind can have a different T-V relationship than the slow wind. The best example of this was in 2003 when there was a very large and long-lived outward polarity coronal hole at low latitudes. The long-lived nature of the hole made it possible to clearly distinguish that large holes can have a different T-V relationship. We found it to be rare that holes are large enough and last long enough to have enough data points to clearly demonstrate this effect. In this study we compare the 2003 coronal hole observations from ACE with the Ulysses polar coronal hole measurements. In an even earlier ACE study we found that both the compressions and rarefactions curves are linear, but the compression curve is shifted to higher temperatures. In this presentation we use Helios, Ulysses, and ACE measurements to examine how the T-V relationship varies with distance. The dynamic evolution of the solar wind parameters is revealed when we first separate compressions and rarefactions and then determine the radial profiles of the solar wind parameters. We find that T-V relationship varies with distance and in particular beyond 3 AU the differences between the compressions and rarefactions are quite important and at such distances a simple linear fit does not represent the T-V distribution very well.

Stability of Nonlinear Wave Patterns to the Bipolar Vlasov-Poisson-Boltzmann System

NASA Astrophysics Data System (ADS)

Li, Hailiang; Wang, Yi; Yang, Tong; Zhong, Mingying

2018-04-01

The main purpose of the present paper is to investigate the nonlinear stability of viscous shock waves and rarefaction waves for the bipolar Vlasov-Poisson-Boltzmann (VPB) system. To this end, motivated by the micro-macro decomposition to the Boltzmann equation in Liu and Yu (Commun Math Phys 246:133-179, 2004) and Liu et al. (Physica D 188:178-192, 2004), we first set up a new micro-macro decomposition around the local Maxwellian related to the bipolar VPB system and give a unified framework to study the nonlinear stability of the basic wave patterns to the system. Then, as applications of this new decomposition, the time-asymptotic stability of the two typical nonlinear wave patterns, viscous shock waves and rarefaction waves are proved for the 1D bipolar VPB system. More precisely, it is first proved that the linear superposition of two Boltzmann shock profiles in the first and third characteristic fields is nonlinearly stable to the 1D bipolar VPB system up to some suitable shifts without the zero macroscopic mass conditions on the initial perturbations. Then the time-asymptotic stability of the rarefaction wave fan to compressible Euler equations is proved for the 1D bipolar VPB system. These two results are concerned with the nonlinear stability of wave patterns for Boltzmann equation coupled with additional (electric) forces, which together with spectral analysis made in Li et al. (Indiana Univ Math J 65(2):665-725, 2016) sheds light on understanding the complicated dynamic behaviors around the wave patterns in the transportation of charged particles under the binary collisions, mutual interactions, and the effect of the electrostatic potential forces.

Coronary microvascular rarefaction and myocardial fibrosis in heart failure with preserved ejection fraction.

PubMed

Mohammed, Selma F; Hussain, Saad; Mirzoyev, Sultan A; Edwards, William D; Maleszewski, Joseph J; Redfield, Margaret M

2015-02-10

Characterization of myocardial structural changes in heart failure with preserved ejection fraction (HFpEF) has been hindered by the limited availability of human cardiac tissue. Cardiac hypertrophy, coronary artery disease (CAD), coronary microvascular rarefaction, and myocardial fibrosis may contribute to HFpEF pathophysiology. We identified HFpEF patients (n=124) and age-appropriate control subjects (noncardiac death, no heart failure diagnosis; n=104) who underwent autopsy. Heart weight and CAD severity were obtained from the autopsy reports. With the use of whole-field digital microscopy and automated analysis algorithms in full-thickness left ventricular sections, microvascular density (MVD), myocardial fibrosis, and their relationship were quantified. Subjects with HFpEF had heavier hearts (median, 538 g; 169% of age-, sex-, and body size-expected heart weight versus 335 g; 112% in controls), more severe CAD (65% with ≥1 vessel with >50% diameter stenosis in HFpEF versus 13% in controls), more left ventricular fibrosis (median % area fibrosis, 9.6 versus 7.1) and lower MVD (median 961 versus 1316 vessels/mm(2)) than control (P<0.0001 for all). Myocardial fibrosis increased with decreasing MVD in controls (r=-0.28, P=0.004) and HFpEF (r=-0.26, P=0.004). Adjusting for MVD attenuated the group differences in fibrosis. Heart weight, fibrosis, and MVD were similar in HFpEF patients with CAD versus without CAD. In this study, patients with HFpEF had more cardiac hypertrophy, epicardial CAD, coronary microvascular rarefaction, and myocardial fibrosis than controls. Each of these findings may contribute to the left ventricular diastolic dysfunction and cardiac reserve function impairment characteristic of HFpEF. © 2014 American Heart Association, Inc.

The properties of fast and slow oblique solitons in a magnetized plasma

NASA Astrophysics Data System (ADS)

McKenzie, J. F.; Doyle, T. B.

2002-01-01

This work builds on a recent treatment by McKenzie and Doyle [Phys. Plasmas 8, 4367 (2001)], on oblique solitons in a cold magnetized plasma, to include the effects of plasma thermal pressure. Conservation of total momentum in the direction of wave propagation immediately shows that if the flow is supersonic, compressive (rarefactive) changes in the magnetic pressure induce decelerations (accelerations) in the flow speed, whereas if the flow is subsonic, compressive (rarefactive) changes in the magnetic pressure induce accelerations (decelerations) in the flow speed. Such behavior is characteristic of a Bernoulli-type plasma momentum flux which exhibits a minimum at the plasma sonic point. The plasma energy flux (kinetic plus enthalpy) also shows similar Bernoulli-type behavior. This transonic effect is manifest in the spatial structure equation for the flow speed (in the direction of propagation) which shows that soliton structures may exist if the wave speed lies either (i) in the range between the fast and Alfven speeds or (ii) between the sound and slow mode speed. These conditions follow from the requirement that a defined, characteristic "soliton parameter" m exceeds unity. It is in this latter slow soliton regime that the effects of plasma pressure are most keenly felt. The equilibrium points of the structure equation define the center of the wave. The structure of both fast and slow solitons is elucidated through the properties of the energy integral function of the structure equation. In particular, the slow soliton, which owes its existence to plasma pressure, may have either a compressive or rarefactive nature, and exhibits a rich structure, which is revealed through the spatial structure of the longitudinal speed and its corresponding transverse velocity hodograph.

Slip and accommodation coefficients from rarefaction and roughness in rotating microscale disk flows

NASA Astrophysics Data System (ADS)

Blanchard, Danny; Ligrani, Phil

2007-06-01

Accommodation coefficients are determined from experimental results and analysis based on the Navier-Stokes equations for rotation-induced flows in C-shaped fluid chamber passages formed between a rotating disk and a stationary surface. A first-order boundary condition is used to model the slip flow. The fluid chamber passage height ranges from 6.85to29.2μm to give Knudsen numbers from 0.0025 to 0.031 for air and helium. In all cases, roughness size is large compared to molecular mean free path. The unique method presented for deducing tangential momentum accommodation coefficients gives values with less uncertainty compared to procedures that rely on flows in stationary tubes and channels. When channel height is defined at the tops of the roughness elements, slip velocity magnitudes and associated accommodation coefficients are a result of rarefaction at solid-gas interfaces and shear at the gas-gas interfaces. With this arrangement, tangential accommodation coefficients obtained with this approach decrease, and slip velocity magnitudes increase, at a particular value of Knudsen number, as the level of surface roughness increases. At values of the mean roughness height greater than 500nm, accommodation coefficients then appear to be lower in air flows than in helium flows, when compared for a particular roughness configuration. When channel height is defined midway between the crests and troughs of the roughness elements, nondimensional pressure rise data show little or no dependence on the level of disk surface roughness and working fluid. With this arrangement, slip is largely independent of surface roughness magnitude and mostly due to rarefaction, provided the appropriate channel height is chosen to define the roughness height.

Citrulline Supplementation Improves Organ Perfusion and Arginine Availability under Conditions with Enhanced Arginase Activity

PubMed Central

Wijnands, Karolina A.P.; Meesters, Dennis M.; van Barneveld, Kevin W.Y.; Visschers, Ruben G.J.; Briedé, Jacob J.; Vandendriessche, Benjamin; van Eijk, Hans M.H.; Bessems, Babs A.F.M.; van den Hoven, Nadine; von Wintersdorff, Christian J.H.; Brouckaert, Peter; Bouvy, Nicole D.; Lamers, Wouter H.; Cauwels, Anje; Poeze, Martijn

2015-01-01

Enhanced arginase-induced arginine consumption is believed to play a key role in the pathogenesis of sickle cell disease-induced end organ failure. Enhancement of arginine availability with l-arginine supplementation exhibited less consistent results; however, l-citrulline, the precursor of l-arginine, may be a promising alternative. In this study, we determined the effects of l-citrulline compared to l-arginine supplementation on arginine-nitric oxide (NO) metabolism, arginine availability and microcirculation in a murine model with acutely-enhanced arginase activity. The effects were measured in six groups of mice (n = 8 each) injected intraperitoneally with sterile saline or arginase (1000 IE/mouse) with or without being separately injected with l-citrulline or l-arginine 1 h prior to assessment of the microcirculation with side stream dark-field (SDF)-imaging or in vivo NO-production with electron spin resonance (ESR) spectroscopy. Arginase injection caused a decrease in plasma and tissue arginine concentrations. l-arginine and l-citrulline supplementation both enhanced plasma and tissue arginine concentrations in arginase-injected mice. However, only the citrulline supplementation increased NO production and improved microcirculatory flow in arginase-injected mice. In conclusion, the present study provides for the first time in vivo experimental evidence that l-citrulline, and not l-arginine supplementation, improves the end organ microcirculation during conditions with acute arginase-induced arginine deficiency by increasing the NO concentration in tissues. PMID:26132994

Longitudinal studies on the microcirculation around the TheraCyte immunoisolation device, using the laser Doppler technique.

PubMed

Rafael, E; Gazelius, B; Wu, G S; Tibell, A

2000-01-01

Encapsulation of cellular grafts in an immunoisolation membrane device may make it possible to perform transplantation without having to give immunosuppressive drugs. A common problem is the development of an avascular fibrotic zone around the implants, leading to impaired graft survival. The TheraCyte macroencapsulation device has therefore been designed to facilitate neovascularization of the device's surface. In this study, we evaluated the microcirculation around empty TheraCyte devices implanted SC in rats at various times after implantation, using a laser Doppler probe introduced via the device port. Studies were performed on day 1 or at 1, 2, and 4 weeks or at 2, 3, and 12 months after implantation. The mean flow was 158+/-42, 148+/-50, 133+/-28, 72+/-17, 138+/-41, 165+/-43, and 160+/-29 perfusion units (PU), respectively. Thus, the microcirculation around the device was significantly reduced at 4 weeks after implantation (p < 0.01) while, from 2 months onwards the circulation had improved and did not differ significantly from that on day 1. The present study shows time-related changes in the microcirculatory flow around TheraCyte macroencapsulation devices that agree with our previous microdialysis studies on in vivo exchange of insulin and glucose between the device and the circulation. Laser Doppler flowmetry seems to provide a reliable technique for screening blood perfusion around macroencapsulation devices.

Endothelin-a receptor antagonist treatment improves the periosteal microcirculation after hindlimb ischemia and reperfusion in the rat.

PubMed

Wolfárd, Antal; Császár, József; Gera, László; Petri, András; Simonka, János Aurél; Balogh, Adáa; Boros, Mihály

2002-12-01

To examine the microcirculatory changes in the rat tibial periosteum after hindlimb ischemia and reperfusion and to evaluate the effects of endothelin-A (ET-A) receptor antagonist therapy in this condition. The healing and functioning of vascularized bone autografts depend mainly on the patency of the microcirculation, and the activation of ET-A receptors may be an important component of the tissue response that occurs during ischemia-reoxygenation injuries. Wistar rats were subjected to 1 hour of hindlimb ischemia and 3 hours of reperfusion. The periosteal microcirculation was visualized by intravital fluorescence microscopy. The leukocyte rolling and adherence in the postcapillary venules and the functional capillary density of the periosteum were determined. Two separate groups were treated with the selective ET-A receptor antagonist BQ 610 or the novel ET-A receptor antagonist ETR-p1/fl peptide at the onset of reperfusion. Reperfusion was accompanied by a significant decrease in functional capillary density and by an increase in the primary and secondary leukocyte-endothelial cell interactions. ET-A receptor inhibition reduced the leukocyte rolling and firm adherence and attenuated the decrease in functional capillary density in both treated groups. ET-1 plays a major role in microvascular dysfunction in the periosteum during reperfusion. The ET-1-ET-A receptor system might be an important target for tissue salvage therapy in transplantation surgery.

Cerebral microcirculation shear stress levels determine Neisseria meningitidis attachment sites along the blood–brain barrier

PubMed Central

Mairey, Emilie; Genovesio, Auguste; Donnadieu, Emmanuel; Bernard, Christine; Jaubert, Francis; Pinard, Elisabeth; Seylaz, Jacques; Olivo-Marin, Jean-Christophe; Nassif, Xavier; Duménil, Guillaume

2006-01-01

Neisseria meningitidis is a commensal bacterium of the human nasopharynx. Occasionally, this bacterium reaches the bloodstream and causes meningitis after crossing the blood–brain barrier by an unknown mechanism. An immunohistological study of a meningococcal sepsis case revealed that neisserial adhesion was restricted to capillaries located in low blood flow regions in the infected organs. This study led to the hypothesis that drag forces encountered by the meningococcus in the bloodstream determine its attachment site in vessels. We therefore investigated the ability of N. meningitidis to bind to endothelial cells in the presence of liquid flow mimicking the bloodstream with a laminar flow chamber. Strikingly, average blood flows reported for various organs strongly inhibited initial adhesion. As cerebral microcirculation is known to be highly heterogeneous, cerebral blood velocity was investigated at the level of individual vessels using intravital imaging of rat brain. In agreement with the histological study, shear stress levels compatible with meningococcal adhesion were only observed in capillaries, which exhibited transient reductions in flow. The flow chamber assay revealed that, after initial attachment, bacteria resisted high blood velocities and even multiplied, forming microcolonies resembling those observed in the septicemia case. These results argue that the combined mechanical properties of neisserial adhesion and blood microcirculation target meningococci to transiently underperfused cerebral capillaries and thus determine disease development. PMID:16864659

Microcirculation in the murine liver: a computational fluid dynamic model based on 3D reconstruction from in vivo microscopy.

PubMed

Piergiovanni, Monica; Bianchi, Elena; Capitani, Giada; Li Piani, Irene; Ganzer, Lucia; Guidotti, Luca G; Iannacone, Matteo; Dubini, Gabriele

2017-10-03

The liver is organized in hexagonal functional units - termed lobules - characterized by a rather peculiar blood microcirculation, due to the presence of a tangled network of capillaries - termed sinusoids. A better understanding of the hemodynamics that governs liver microcirculation is relevant to clinical and biological studies aimed at improving our management of liver diseases and transplantation. Herein, we built a CFD model of a 3D sinusoidal network, based on in vivo images of a physiological mouse liver obtained with a 2-photon microscope. The CFD model was developed with Fluent 16.0 (ANSYS Inc., Canonsburg, PA), particular care was taken in imposing the correct boundary conditions representing a physiological state. To account for the remaining branches of the sinusoids, a lumped parameter model was used to prescribe the correct pressure at each outlet. The effect of an adhered cell on local hemodynamics is also investigated for different occlusion degrees. The model here proposed accurately reproduces the fluid dynamics in a portion of the sinusoidal network in mouse liver. Mean velocities and mass flow rates are in agreement with literature values from in vivo measurements. Our approach provides details on local phenomena, hardly described by other computational studies, either focused on the macroscopic hepatic vasculature or based on homogeneous porous medium model. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantitative estimation of antioxidant therapy efficiency in diabetes mellitus patients

NASA Astrophysics Data System (ADS)

Gurfinkel, Youri I.; Ishunina, Angela M.; Ovsyannickov, Konstantin V.; Strokov, Igor A.

2000-11-01

The aim of this work was to find out to which degree Tanakan affects the microcirculation parameters and the malonic dialdehyde level as a parameter of intense lipid peroxidation in insulin-independent diabetes patients with different disease durations. We used computerized capillaroscope GY-0.04 designed by the Centre for Analysis of Substances, Russia for the non-invasive measurement of capillary blood velocity as well as the size of the perivascular zone and density of blood aggregates and lipid inclusions. The microcirculation parameters were studied in two groups of insulin-independent diabetes patients. The basic group included 58 patients (61+/-9,0 years, disease duration 14,7+/-7,8 years). The patients had late diabetic complications as retinopathy and nephrophathy, neuropathy, confirmed by clinical and tool investigation. In this group we also studied the level of serum malonic dialdehyde, as a parameter of intense lipid peroxidation. The reference group included 31 patients (57+/-1,3 years, disease duration 3,6+/-0,6 years) with minimum diabetic complication. We show that Tanakan in daily dosage 120 mg for 2 months reduces the malonic dialdehyde level in the blood serum and the erythrocyte membranes of type II diabetes patients and improves the microcirculation parameters. There are correspondences between the density of lipid inclusions as determined with computerized capillaroscopy and the lipid exchange parameters as determined using a routing blood test. Thus, noninvasive blood lipid quantification is feasible and reliable.

Pilot Study of Laser Doppler Measurement of Flow Variability in the Microcirculation of the Palatal Mucosa

PubMed Central

Le Bars, Pierre; Niagha, Gaston; Kouadio, Ayepa Alain; Demoersman, Julien; Roy, Elisabeth; Armengol, Valérie; Soueidan, Assem

2016-01-01

Background. Histopathological alterations can arise when the denture-supporting mucosa experiences microbial and mechanical stress through the denture base and diagnosis of these diseases usually follows microvascular changes. Microcirculation measurement could allow for detection of such dysfunction and aid in the early diagnosis of palatal mucosa pathologies. Materials and Methods. We tested the sensitivity of laser Doppler for measuring the microcirculation of the palatal mucosa, assessing the median raphe (MR), Schroeder area (SA), and retroincisive papilla (RP). A Doppler PeriFlux 5000 System, containing a laser diode, was used. 54 healthy participants were recruited. We compare the measurements of PU (perfusion unit) using ANOVA test. Results. The numerical values for palatal mucosa blood flow differed significantly among the anatomical areas (p = 0.0167). The mean value of Schroeder area was 92.6 (SD: 38.4) and was significantly higher than the retroincisive papilla (51.9) (SD: 20.2) (p < 0.05), which in turn was higher than that of median raphe (31.9) (SD: 24.2) (p < 0.0001). Conclusion. Schroeder area appeared to have the greatest sensitivity, and vascular flow variability among individuals was also greatest in this region. We suggest that analysis of blood stream modification with laser Doppler of the palatal mucosa can help to detect onset signs of pathological alterations. PMID:27340663

Refraction of dispersive shock waves

NASA Astrophysics Data System (ADS)

El, G. A.; Khodorovskii, V. V.; Leszczyszyn, A. M.

2012-09-01

We study a dispersive counterpart of the classical gas dynamics problem of the interaction of a shock wave with a counter-propagating simple rarefaction wave, often referred to as the shock wave refraction. The refraction of a one-dimensional dispersive shock wave (DSW) due to its head-on collision with the centred rarefaction wave (RW) is considered in the framework of the defocusing nonlinear Schrödinger (NLS) equation. For the integrable cubic nonlinearity case we present a full asymptotic description of the DSW refraction by constructing appropriate exact solutions of the Whitham modulation equations in Riemann invariants. For the NLS equation with saturable nonlinearity, whose modulation system does not possess Riemann invariants, we take advantage of the recently developed method for the DSW description in non-integrable dispersive systems to obtain main physical parameters of the DSW refraction. The key features of the DSW-RW interaction predicted by our modulation theory analysis are confirmed by direct numerical solutions of the full dispersive problem.

Orion Aerodynamics for Hypersonic Free Molecular to Continuum Conditions

NASA Technical Reports Server (NTRS)

Moss, James N.; Greene, Francis A.; Boyles, Katie A.

2006-01-01

Numerical simulations are performed for the Orion Crew Module, previously known as the Crew Exploration Vehicle (CEV) Command Module, to characterize its aerodynamics during the high altitude portion of its reentry into the Earth's atmosphere, that is, from free molecular to continuum hypersonic conditions. The focus is on flow conditions similar to those that the Orion Crew Module would experience during a return from the International Space Station. The bulk of the calculations are performed with two direct simulation Monte Carlo (DSMC) codes, and these data are anchored with results from both free molecular and Navier-Stokes calculations. Results for aerodynamic forces and moments are presented that demonstrate their sensitivity to rarefaction, that is, for free molecular to continuum conditions (Knudsen numbers of 111 to 0.0003). Also included are aerodynamic data as a function of angle of attack for different levels of rarefaction and results that demonstrate the aerodynamic sensitivity of the Orion CM to a range of reentry velocities (7.6 to 15 km/s).

A simple nonlinear element model

NASA Astrophysics Data System (ADS)

Mikhailov, S. G.; Rudenko, O. V.

2017-05-01

We study experimentally the behavior of a nonlinear element, a light plate pressed to the opening in the cavity of an acoustic resonator. Measurements of field oscillations inside and outside the cavity have shown that for large amplitudes, they become essentially anharmonic. The time dependences of displacement of the plate with increasing amplitude of the exciting voltage demonstrates a gradual change in the shape of vibrations from harmonic to half-period oscillation. A constant component appears in the cavity: rarefaction or outflow of the medium through the orifice. We construct a theory for nonlinear oscillations of a plate taking into account its different elastic reactions to compression and rarefaction with allowance for monopole radiation by the small-wave-size plate or radiation of a plane wave by the plate. We calculate the amplitudes of the harmonics and solve the problem of low-frequency stationary noise acting on the plate. We obtain expressions for the correlation function and mean power at the output given a normal random process at the input.

Existence regimes for the formation of nonlinear dissipative structures in inhomogeneous magnetoplasmas with non-Maxwellian electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masood, W.; National Centre for Physics, Shahdara Valley Road, Islamabad; Zahoor, Sara

2016-09-15

Nonlinear dissipative structures are studied in one and two dimensions in nonuniform magnetized plasmas with non-Maxwellian electrons. The dissipation is incorporated in the system through ion-neutral collisions. Employing the drift approximation, nonlinear drift waves are derived in 1D, whereas coupled drift-ion acoustic waves are derived in 2D in the weak nonlinearity limit. It is found that the ratio of the diamagnetic drift velocity to the velocity of nonlinear structure determines the nature (compressive or rarefactive) of the shock structure. The upper and lower bounds for velocity of the nonlinear shock structures are also found. It is noticed that the existencemore » regimes for the drift shock waves in one and two dimensions for Cairns distributed electrons are very distinct from those with kappa distributed electrons. Interestingly, it is found that both compressive and rarefactive shock structures could be obtained for the one dimensional drift waves with kappa distributed electrons.« less

Magnetosonic waves interactions in a spin-1/2 degenerate quantum plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Sheng-Chang, E-mail: lsc1128lsc@126.com; Han, Jiu-Ning

2014-03-15

We investigate the magnetosonic waves and their interactions in a spin-1/2 degenerate quantum plasma. With the help of the extended Poincaré-Lighthill-Kuo perturbation method, we derive two Korteweg-de Vries-Burgers equations to describe the magnetosonic waves. The parameter region where exists magnetosonic waves and the phase diagram of the compressive and rarefactive solitary waves with different plasma parameters are shown. We further explore the effects of quantum diffraction, quantum statistics, and electron spin magnetization on the head-on collisions of magnetosonic solitary waves. We obtain the collision-induced phase shifts (trajectory changes) analytically. Both for the compressive and rarefactive solitary waves, it is foundmore » that the collisions only lead to negative phase shifts. Our present study should be useful to understand the collective phenomena related to the magnetosonic wave collisions in degenerate plasmas like those in the outer shell of massive white dwarfs as well as to the potential applications of plasmas.« less

Existence regimes for the formation of nonlinear dissipative structures in inhomogeneous magnetoplasmas with non-Maxwellian electrons

NASA Astrophysics Data System (ADS)

Masood, W.; Zahoor, Sara; Gul-e-Ali, Ahmad, Ali

2016-09-01

Nonlinear dissipative structures are studied in one and two dimensions in nonuniform magnetized plasmas with non-Maxwellian electrons. The dissipation is incorporated in the system through ion-neutral collisions. Employing the drift approximation, nonlinear drift waves are derived in 1D, whereas coupled drift-ion acoustic waves are derived in 2D in the weak nonlinearity limit. It is found that the ratio of the diamagnetic drift velocity to the velocity of nonlinear structure determines the nature (compressive or rarefactive) of the shock structure. The upper and lower bounds for velocity of the nonlinear shock structures are also found. It is noticed that the existence regimes for the drift shock waves in one and two dimensions for Cairns distributed electrons are very distinct from those with kappa distributed electrons. Interestingly, it is found that both compressive and rarefactive shock structures could be obtained for the one dimensional drift waves with kappa distributed electrons.

Modeling malaria infected cells in microcirculation

NASA Astrophysics Data System (ADS)

Raffiee, Amir Hossein; Dabiri, Sadegh; Motavalizadeh Ardekani, Arezoo

2016-11-01

Plasmodim (P.) falciparum is one of the deadliest types of malaria species that invades healthy red blood cells (RBC) in human blood flow. This parasite develops through 48-hour intra-RBC process leading to significant morphological and mechanical (e.g., stiffening) changes in RBC membrane. These changes have remarkable effects on blood circulation such as increase in flow resistance and obstruction in microcirculation. In this work a computational framework is developed to model RBC suspension in blood flow using front-tracking technique. The present study focuses on blood flow behavior under normal and infected circumstances and predicts changes in blood rheology for different levels of parasitemia and hematocrit. This model allows better understanding of blood flow circulation up to a single cell level and provides us with realistic and deep insight into hematologic diseases such as malaria.

Label-free and highly sensitive optical imaging of detailed microcirculation within meninges and cortex in mice with the cranium left intact

NASA Astrophysics Data System (ADS)

Jia, Yali; An, Lin; Wang, Ruikang K.

2010-05-01

We demonstrate for the first time that the detailed blood flow distribution within intracranial dura mater and cortex can be visualized by an ultrahigh sensitive optical microangiography (UHS-OMAG). The study uses an UHS-OMAG system operating at 1310 nm with an imaging speed at 150 frames per second that requires ~10 s to complete one 3-D scan of ~2.5×2.5 mm2. The system is sensitive to blood flow with a velocity ranging from ~4 μm/s to ~23 mm/s. We show superior performance of UHS-OMAG in providing functional images of capillary level microcirculation within meninges in mice with the cranium left intact, the results of which correlate well with the standard dural histopathology.

Microcirculation and the physiome projects.

PubMed

Bassingthwaighte, James B

2008-11-01

The Physiome projects comprise a loosely knit worldwide effort to define the Physiome through databases and theoretical models, with the goal of better understanding the integrative functions of cells, organs, and organisms. The projects involve developing and archiving models, providing centralized databases, and linking experimental information and models from many laboratories into self-consistent frameworks. Increasingly accurate and complete models that embody quantitative biological hypotheses, adhere to high standards, and are publicly available and reproducible, together with refined and curated data, will enable biological scientists to advance integrative, analytical, and predictive approaches to the study of medicine and physiology. This review discusses the rationale and history of the Physiome projects, the role of theoretical models in the development of the Physiome, and the current status of efforts in this area addressing the microcirculation.

Intravoxel incoherent motion (IVIM) imaging in human achilles tendon.

PubMed

Wengler, Kenneth; Fukuda, Takeshi; Tank, Dharmesh; Huang, Mingqian; Gould, Elaine S; Schweitzer, Mark E; He, Xiang

2018-05-09

Limited microcirculation has been implicated in Achilles tendinopathy and may affect healing and disease progression. Existing invasive and noninvasive approaches to evaluate tendon microcirculation lack sensitivity and spatial coverage. To develop a novel Achilles tendon intravoxel incoherent motion (IVIM) MRI protocol to overcome the limitations from low tendon T 2 /T 2 * value and low intratendinous blood volume and blood velocity to evaluate tendon microcirculation. Prospective. Sixteen healthy male participants (age 31.0 ± 2.1) were recruited. A stimulated echo readout-segmented echo planar imaging (ste-RS-EPI) IVIM sequence at 3.0T. The feasibility of the proposed ste-RS-EPI IVIM protocol combined with Achilles tendon magic angle effect was evaluated. The sensitivity of the protocol was assessed by an exercise-induced intratendinous hemodynamic response in healthy participants. The vascular origin of the observed IVIM signal was validated by varying the diffusion mixing time and echo time. Two-tailed t-tests were used to evaluate differences (P < 0.05 was considered significant). Consistent with known tendon hypovascularity, the midportion Achilles tendon at baseline showed significantly lower IVIM-derived perfusion fraction (f p ) (3.1 ± 0.9%) compared to the proximal and distal Achilles tendon (6.0 ± 1.8% and 6.1 ± 2.0%, respectively; P < 0.01). Similarly, the midportion Achilles tendon exhibited significantly lower baseline blood flow index (D*×f p ) (40.9 ± 19.2, 18.3 ± 5.3, and 32.0 ± 9.4 in proximal, midportion, and distal Achilles tendon, respectively; P < 0.01). Eccentric heel-raise exercise led to ∼2 times increase of Achilles tendon blood flow in healthy participants. Consistent with its vascular origin, the estimated f p demonstrated a high dependency to IVIM protocol parameters, while the T 1 /T 2 -corrected absolute intratendinous microvascular blood volume fraction (V b ) did not vary. Achilles tendon ste-RS-EPI IVIM noninvasively assessed baseline values and exercise-induced changes to tendon microcirculation in healthy tendon. 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018. © 2018 International Society for Magnetic Resonance in Medicine.

Midportion achilles tendon microcirculation after intermittent combined cryotherapy and compression compared with cryotherapy alone: a randomized trial.

PubMed

Knobloch, Karsten; Grasemann, Ruth; Spies, Marcus; Vogt, Peter M

2008-11-01

The effect of combined cryotherapy/compression versus cryotherapy alone on the Achilles tendon is undetermined. Standardized combined cryotherapy/compression changes in midportion Achilles tendon microcirculation are superior to those with cryotherapy during intermittent application. Controlled laboratory study. Sixty volunteers were randomized for either combined cryotherapy/compression (Cryo/Cuff, DJO Inc, Vista, California: n = 30; 32 +/- 11 years) or cryotherapy alone (KoldBlue, TLP Industries, Kent, United Kingdom: n = 30; 33 +/- 12 years) with intermittent 3 x 10-minute application. Midportion Achilles tendon microcirculation was determined (O2C, LEA Medizintechnik, Giessen, Germany). Both Cryo/Cuff and KoldBlue significantly reduced superficial and deep capillary tendon blood flow within the first minute of application (43 +/- 46 arbitrary units [AU] vs 10 +/- 19 AU and 42 +/- 46 AU vs 12 +/- 10 AU; P = .0001) without a significant difference throughout all 3 applications. However, during recovery, superficial and deep capillary blood flow was reestablished significantly faster using Cryo/Cuff (P = .023). Tendon oxygen saturation was reduced in both groups significantly (3 minutes Cryo/Cuff: 36% +/- 20% vs 16% +/- 15%; KoldBlue: 42% +/- 19% vs 28% +/- 20%; P < .05) with significantly stronger effects using Cryo/Cuff (P = .014). Cryo/Cuff led to significantly higher tendon oxygenation (Cryo/Cuff: 62% +/- 28% vs baseline 36% +/- 20%; P = .0001) in superficial and deep tissue (Cryo/Cuff: 73% +/- 14% vs baseline 65% +/- 17%; P = .0001) compared with KoldBlue during all recoveries. Postcapillary venous filling pressures were significantly reduced in both groups during application; however, Cryo/Cuff led to significantly, but marginally, lower pressures (Cryo/Cuff: 41 +/- 7 AU vs baseline 51 +/- 13 AU; P = .0001 and KoldBlue: 46 +/- 7 AU vs baseline 56 +/- 11 AU; P = .026 for Cryo/Cuff vs KoldBlue). Increased tendon oxygenation is achieved as tendon preconditioning by combined cryotherapy and compression with significantly increased tendon oxygen saturation during recovery in contrast to cryotherapy alone. Both regimens lead to a significant amelioration of tendinous venous outflow. Combined cryotherapy and compression is superior to cryotherapy alone regarding the Achilles tendon microcirculation. Further studies in tendinopathy and tendon rehabilitation are warranted to elucidate its value regarding functional issues.

2×2 systems of conservation laws with L data

NASA Astrophysics Data System (ADS)

Bianchini, Stefano; Colombo, Rinaldo M.; Monti, Francesca

Consider a hyperbolic system of conservation laws with genuinely nonlinear characteristic fields. We extend the classical Glimm-Lax (1970) result [13, Theorem 5.1] proving the existence of solutions for L initial datum, relaxing the assumptions taken therein on the geometry of the shock-rarefaction curves.

Vanishing White Matter Disease: A Review with Focus on Its Genetics

ERIC Educational Resources Information Center

Pronk, Jan C.; van Kollenburg, Barbara; Scheper, Gert C.; van der Knaap, Marjo S.

2006-01-01

Leukoencephalopathy with vanishing white matter (VWM) is an autosomal recessive brain disorder, most often with a childhood onset. Magnetic resonance imaging and spectroscopy indicate that, with time, increasing amounts of cerebral white matter vanish and are replaced by fluid. Autopsy confirms white matter rarefaction and cystic degeneration. The…

Numerical Simulations of Shock Wave Refraction at Inclined Gas Contact Discontinuity

ERIC Educational Resources Information Center

Bulat, Pavel V.; Volkov, Konstantin N.

2016-01-01

When a shock wave interacts with a contact discontinuity, there may appear a reflected rarefaction wave, a deflected contact discontinuity and a refracted supersonic shock. The numerical simulation of shock wave refraction at a plane contact discontinuity separating gases with different densities is performed. Euler equations describing inviscid…

Novel Molecular Imaging Approach for Subclinical Detection of Iritis and Evaluation of Therapeutic Success

PubMed Central

Xie, Fang; Sun, Dawei; Schering, Alexander; Nakao, Shintaro; Zandi, Souska; Liu, Ping; Hafezi-Moghadam, Ali

2010-01-01

There is an urgent need for early diagnosis in medicine, whereupon effective treatments could prevent irreversible tissue damage. Acute anterior chamber inflammation is the most common form of uveitis and a major cause of vision loss. The proximity of the iris vasculature to the light-permeable cornea and its involvement in ocular inflammation make it an ideal target for noninvasive molecular imaging. To accomplish this, carboxylated fluorescent microspheres (MSs) were conjugated with recombinant P-selectin glycoprotein ligand-1 and systemically injected in endotoxin-induced uveitic animals. MS adhesion in the microcirculation of the anterior and posterior chamber was visualized by intravital microscopy and scanning laser ophthalmoscopy. In iritic animals, significantly higher numbers of recombinant P-selectin glycoprotein ligand-1-conjugated MSs adhered to the endothelium (P = 0.03) matching the increase in leukocyte adhesion. Conjugated MSs specifically interacted with firmly adhering leukocytes, allowing quantification of the endogenous immune response. Topical eye drop treatment with dexamethasone (P < 0.01) or cyclosporine A (P < 0.01) significantly lowered MS adhesion in iris vessels. Surprisingly, topical dexamethasone significantly reduced MS interaction in the fundus vessels (P < 0.01), while cyclosporine A did not. In vivo MS accumulation preceded clinical signs of anterior uveitis and leukocyte adhesion in iris vasculature. This work introduces noninvasive subclinical detection of endothelial injury in the iris vasculature, providing a unique opportunity for quantifying vascular injury and immune response in vivo. PMID:20581051

[transcutaneous oximetry--between theory and practice].

PubMed

Zulec, Mirna

2014-10-01

Transcutaneous oximetry is a procedure used to measure the pressure of oxygen in tissue and to determine oxygenation level. It is essential to determine the state of microcirculation and is used to assess the necessity and level of amputation and the effect of revascularization procedures, as a predictor of wound healing and hyperbaric oxygen therapy (HBOT) effectiveness tool. The measurement is done by the application electrode measuring point and the result is measured in mm Hg. Tissue with adequate oxygen level has a value greater than 50 mm Hg. Values between 20 and 40 mm Hg are considered hypoxic, while those below 20 mm Hg indicate extreme hypoxia. In Croatia, TcPO2 is commonly used for HBOT assessment but there is the need of broader application to objectify and facilitate procedures in the care of persons with impaired microcirculation.

[Physiological features of skin ageing in human].

PubMed

Tikhonova, I V; Tankanag, A V; Chemeris, N K

2013-01-01

The issue deals with the actual problem of gerontology, notably physiological features of human skin ageing. In the present review the authors have considered the kinds of ageing, central factors, affected on the ageing process (ultraviolet radiation and oxidation stress), as well as the research guidelines of the ageing changes in the skin structure and fuctions: study of mechanical properties, microcirculation, pH and skin thickness. The special attention has been payed to the methods of assessment of skin blood flow, and to results of investigations of age features of peripheral microhemodynamics. The laser Doppler flowmetry technique - one of the modern, noninvasive and extensively used methods for the assessmant of skin blood flow microcirculation system has been expanded in the review. The main results of the study of the ageing changes of skin blood perfusion using this method has been also presented.

Video-rate imaging of microcirculation with single-exposure oblique back-illumination microscopy

NASA Astrophysics Data System (ADS)

Ford, Tim N.; Mertz, Jerome

2013-06-01

Oblique back-illumination microscopy (OBM) is a new technique for simultaneous, independent measurements of phase gradients and absorption in thick scattering tissues based on widefield imaging. To date, OBM has been used with sequential camera exposures, which reduces temporal resolution, and can produce motion artifacts in dynamic samples. Here, a variation of OBM that allows single-exposure operation with wavelength multiplexing and image splitting with a Wollaston prism is introduced. Asymmetric anamorphic distortion induced by the prism is characterized and corrected in real time using a graphics-processing unit. To demonstrate the capacity of single-exposure OBM to perform artifact-free imaging of blood flow, video-rate movies of microcirculation in ovo in the chorioallantoic membrane of the developing chick are presented. Imaging is performed with a high-resolution rigid Hopkins lens suitable for endoscopy.

Haemodynamic coherence - The relevance of fluid therapy.

PubMed

Arnemann, Philip; Seidel, Laura; Ertmer, Christian

2016-12-01

The ultimate goal of fluid therapy is to improve the oxygenation of cells by improving the cardiac output, thus improving microcirculation by optimizing macrocirculation. This haemodynamic coherence is often altered in patients with haemorrhagic shock and sepsis. The loss of haemodynamic coherence is associated with adverse outcomes. It may be influenced by the mechanisms of the underlying disease and properties of different fluids used for resuscitation in these critically ill patients. Monitoring microcirculation and haemodynamic coherence may be an additional tool to predict the response to fluid administration. In addition, microcirculatory analysis may support the clinician in his decision to not administer fluids when microcirculatory blood flow is preserved. In future, the indication, guidance and termination of fluid therapy may be assessed by bedside microvascular analysis in combination with standard haemodynamic monitoring. Copyright © 2016 Elsevier Ltd. All rights reserved.

Video-rate imaging of microcirculation with single-exposure oblique back-illumination microscopy.

PubMed

Ford, Tim N; Mertz, Jerome

2013-06-01

Oblique back-illumination microscopy (OBM) is a new technique for simultaneous, independent measurements of phase gradients and absorption in thick scattering tissues based on widefield imaging. To date, OBM has been used with sequential camera exposures, which reduces temporal resolution, and can produce motion artifacts in dynamic samples. Here, a variation of OBM that allows single-exposure operation with wavelength multiplexing and image splitting with a Wollaston prism is introduced. Asymmetric anamorphic distortion induced by the prism is characterized and corrected in real time using a graphics-processing unit. To demonstrate the capacity of single-exposure OBM to perform artifact-free imaging of blood flow, video-rate movies of microcirculation in ovo in the chorioallantoic membrane of the developing chick are presented. Imaging is performed with a high-resolution rigid Hopkins lens suitable for endoscopy.

Label-free and highly sensitive optical imaging of detailed microcirculation within meninges and cortex in mice with the cranium left intact.

PubMed

Jia, Yali; An, Lin; Wang, Ruikang K

2010-01-01

We demonstrate for the first time that the detailed blood flow distribution within intracranial dura mater and cortex can be visualized by an ultrahigh sensitive optical microangiography (UHS-OMAG). The study uses an UHS-OMAG system operating at 1310 nm with an imaging speed at 150 frames per second that requires approximately 10 s to complete one 3-D scan of approximately 2.5 x 2.5 mm(2). The system is sensitive to blood flow with a velocity ranging from approximately 4 microms to approximately 23 mms. We show superior performance of UHS-OMAG in providing functional images of capillary level microcirculation within meninges in mice with the cranium left intact, the results of which correlate well with the standard dural histopathology.

Label-free and highly sensitive optical imaging of detailed microcirculation within meninges and cortex in mice with the cranium left intact

PubMed Central

Jia, Yali; An, Lin; Wang, Ruikang K.

2010-01-01

We demonstrate for the first time that the detailed blood flow distribution within intracranial dura mater and cortex can be visualized by an ultrahigh sensitive optical microangiography (UHS-OMAG). The study uses an UHS-OMAG system operating at 1310 nm with an imaging speed at 150 frames per second that requires ∼10 s to complete one 3-D scan of ∼2.5×2.5 mm2. The system is sensitive to blood flow with a velocity ranging from ∼4 μm∕s to ∼23 mm∕s. We show superior performance of UHS-OMAG in providing functional images of capillary level microcirculation within meninges in mice with the cranium left intact, the results of which correlate well with the standard dural histopathology. PMID:20614993

Nailfold Capillaroscopy in Rheumatic Diseases: Which Parameters Should Be Evaluated?

PubMed Central

Etehad Tavakol, Mahnaz; Erlandsson, Björn-Erik

2015-01-01

Video nailfold capillaroscopy (NFC), considered as an extension of the widefield technique, allows a more accurate measuring and storing of capillary data and a better defining, analyzing, and quantifying of capillary abnormalities. Capillaroscopic study is often performed on the patients suspected of having microcirculation problems such as Raynaud's phenomenon as the main indication for nailfold capillaroscopy. Capillaroscopic findings based on microcirculation studies can provide useful information in the fields of pathophysiology, differential diagnosis, and monitoring therapy. Nailfold capillaroscopy provides a vital assessment in clinical practices and research; for example, its reputation in the early diagnosis of systemic sclerosis is well established and it is also used as a classification criterion in this regard. This review focuses on the manner of performing video nailfold capillaroscopy and on a common approach for measuring capillary dimensions in fingers and toes. PMID:26421308

Nailfold Capillaroscopy in Rheumatic Diseases: Which Parameters Should Be Evaluated?

PubMed

Etehad Tavakol, Mahnaz; Fatemi, Alimohammad; Karbalaie, Abdolamir; Emrani, Zahra; Erlandsson, Björn-Erik

2015-01-01

Video nailfold capillaroscopy (NFC), considered as an extension of the widefield technique, allows a more accurate measuring and storing of capillary data and a better defining, analyzing, and quantifying of capillary abnormalities. Capillaroscopic study is often performed on the patients suspected of having microcirculation problems such as Raynaud's phenomenon as the main indication for nailfold capillaroscopy. Capillaroscopic findings based on microcirculation studies can provide useful information in the fields of pathophysiology, differential diagnosis, and monitoring therapy. Nailfold capillaroscopy provides a vital assessment in clinical practices and research; for example, its reputation in the early diagnosis of systemic sclerosis is well established and it is also used as a classification criterion in this regard. This review focuses on the manner of performing video nailfold capillaroscopy and on a common approach for measuring capillary dimensions in fingers and toes.

[Transcranial magnetotherapy for the correction of initial manifestations of diabetic retinopathy in children].

PubMed

Nikolaeva, N V; Bolotova, N V; Kamenskikh, T G; Raĭgorodskiĭ, Iu M; Kolbenev, I O; Luk'ianov, V F

2009-01-01

This study included 45 children at the age from 5 to 17 years with type I diabetes mellitus complicated by diabetic retinopathy. All the patients showed retinal thickening at the macula and reduced amplitude of local electroretinogram suggesting compromised capillary circulation. The capillary blood flow was corrected by transcranial magnetotherapy with the use of an AMO-ATOS Ogolovie unit. The results of the treatment were evaluated from characteristics of laser Doppler flometry. A course of transcranial magnetotherapy comprising 10 daily seances resulted in a significant increase of microcirculation index, respiratory rhythm, and myogenic tone (by 1.64, 1.35, and 1.16 times respectively). In addition, morphometric and electrophysiological properties of the retina underwent positive changes. Transcranial exposure to the traveling magnetic field is recommended for the correction of intraocular microcirculation and prevention of diabetic macular oedema.

A new contrast-assisted method in microcirculation volumetric flow assessment

NASA Astrophysics Data System (ADS)

Lu, Sheng-Yi; Chen, Yung-Sheng; Yeh, Chih-Kuang

2007-03-01

Microcirculation volumetric flow rate is a significant index in diseases diagnosis and treatment such as diabetes and cancer. In this study, we propose an integrated algorithm to assess microcirculation volumetric flow rate including estimation of blood perfused area and corresponding flow velocity maps based on high frequency destruction/contrast replenishment imaging technique. The perfused area indicates the blood flow regions including capillaries, arterioles and venules. Due to the echo variance changes between ultrasonic contrast agents (UCAs) pre- and post-destruction two images, the perfused area can be estimated by the correlation-based approach. The flow velocity distribution within the perfused area can be estimated by refilling time-intensity curves (TICs) after UCAs destruction. Most studies introduced the rising exponential model proposed by Wei (1998) to fit the TICs. Nevertheless, we found the TICs profile has a great resemblance to sigmoid function in simulations and in vitro experiments results. Good fitting correlation reveals that sigmoid model was more close to actual fact in describing destruction/contrast replenishment phenomenon. We derived that the saddle point of sigmoid model is proportional to blood flow velocity. A strong linear relationship (R = 0.97) between the actual flow velocities (0.4-2.1 mm/s) and the estimated saddle constants was found in M-mode and B-mode flow phantom experiments. Potential applications of this technique include high-resolution volumetric flow rate assessment in small animal tumor and the evaluation of superficial vasculature in clinical studies.

Sublingual microcirculatory alterations in cirrhotic patients.

PubMed

Gonzalez Ballerga, Esteban; Pozo, Mario O; Rubatto Birri, Paolo N; Kanoore Edul, Vanina Siham; Sorda, Juan A; Daruich, Jorge; Dubin, Arnaldo

2018-05-01

To assess sublingual microcirculation in cirrhotic patients and its relationship to spider angiomas, complications, and outcome. Thirty-one cirrhotic patients were prospectively compared to 31 matched controls. Sublingual microcirculation was evaluated by videomicroscopy. We specifically looked for capillaries with increased RBCV, which was defined as a velocity higher than the percentile 100th of controls. Compared to controls, cirrhotic patients showed decreased total and PVD (14.4 ± 2.2 vs 16.0 ± 1.3 and 14.1 ± 2.3 vs 15.9 ± 1.6 mm/mm 2 , respectively, P < .001 for both) and increased HFI (0.64 ± 0.39 vs 0.36 ± 0.21, P = .001). They also exhibited high RBCV in 2% of the microvessels (P < .0001). Patients with MELD score ≥10 had higher RBCV than patients with score <10 (1414 ± 290 vs 1206 ± 239 μm/s, P < .05). Patients with spider angiomas showed lower vascular densities. Microcirculation did not differ between survivors and nonsurvivors. Cirrhosis is associated with microcirculatory alterations that can be easily monitored in the sublingual mucosa. Alterations included decreased density and PPV and hyperdynamic microvessels. The most striking finding, however, was the microvascular heterogeneity. Patients with spider angiomas had more severe alterations. Larger studies should clarify the relationship between microcirculatory abnormalities and outcome. © 2018 John Wiley & Sons Ltd.

Evaluation of angiogenesis, epithelialisation and microcirculation after application of polyhexanide, chitosan and sodium chloride in rodents.

PubMed

Goertz, Ole; Lauer, Henrik; Hirsch, Tobias; Daigeler, Adrien; Harati, Kamran; Stricker, Ingo; Lehnhardt, Marcus; von der Lohe, Leon

2016-12-01

The purpose of this study was to investigate the effect of polyhexanide and a new developed chitin-based wound dressing on skin microcirculation, epithelialisation and angiogenesis. A full-thickness dermal layer extending to the underlying cartilage was excised on the dorsal side of hairless mice (n = 27; 2·3 ± 0·3 mm 2 ). A polyhexanide ointment, a chitosan solution and a sodium chloride group as control were analysed using intravital fluorescence microscopy. Angiogenesis, epithelialisation and microcirculatory standard parameters were measured over a time period of 20 days. The non-perfused area is regarded as a parameter for angiogenesis and showed the following results: on days 12, 16 and 20, the sodium chloride group was significantly superior to chitosan solution (P < 0·05) and, on days 8, 12, 16 and 20, the polyhexanide group was superior to chitosan solution (P < 0·05). The epithelialisation was measured significantly faster in the polyhexanide and control group on day 8 versus chitosan solution. Whereas polyhexanide and sodium chloride were nearly completely epithelialised, treatment with chitosan solution showed still an open wound of 11% of the initial wound size. Altogether, we could demonstrate the advantageous effects of a polyhexanide ointment on microcirculation, angiogenesis and epithelialisation. Chitosan solution appears to inhibit angiogenesis and delays epithelialisation. Further studies in different models would be worthwhile to confirm these results. © 2015 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Using a laser-Doppler flowmetry to measure pulsatile microcirculation on the kidney in rats

NASA Astrophysics Data System (ADS)

Jan, Ming-Yie; Chao, Pin-Tsun; Hsu, Tse-Lin; Wang, Yuh-Yin L.; Wang, Wei-Kung

2001-10-01

Although Laser Doppler flowmetery (LDF) been extensively used in measurement of microvascular blood flow of different tissues. However, due to some physiological vibrations, fast oscillations of the renal cortical flux (RCF) are hard to be measured. In the study, a commercial 3mW 780nm Laser Doppler flowmetery, with a single fiber and a de-vibration holder, was used to measure the pulsatile RCF in rats. Considering the fast response due to the heart rate of rats, the time constant (TC) was set to 0.05 second and thus the frequency response is up to 20Hz. Furthermore, a calibration standard and a static blood sample were also measured as the references without the pulsatile driving force. In order not to perturb the RCF with tiny momentum, the applying force that the fiber exerted on the renal surface was controlled below 100 dyne. To enhance the signal to noise ratio (SNR), an averaged periodogram was used to estimate the frequency components of the pulsatile microcirculation. It is found that the dominating fast oscillation of RCF is pulsatile and its harmonic components are directly correlated with those of the heartbeat (correlation coefficient =0.999, P<0.001, n=17). The result shows that, in the kidney, the pulsatile RCF is the dominating component of microcirculation oscillation and driven by the fast propagating blood pressure. This technique could be further utilized to analyze the pharmacological effect and hemodynamic parameters on renal function.

Modeling the measurements of cochlear microcirculation and hearing function after loud noise.

PubMed

Arpornchayanon, Warangkana; Canis, Martin; Suckfuell, Markus; Ihler, Fritz; Olzowy, Bernhard; Strieth, Sebastian

2011-09-01

Recent findings support the crucial role of microcirculatory disturbance and ischemia for hearing impairment especially after noise-induced hearing loss (NIHL). The aim of this study was to establish an animal model for in vivo analysis of cochlear microcirculation and hearing function after a loud noise to allow precise measurements of both parameters in vivo. Randomized controlled trial. Setting. Animal study. Subjects and Methods. After assessment of normacusis (0 minutes) using evoked auditory brainstem responses (ABRs), noise (106-dB sound pressure level [SPL]) was applied to both ears in 6 guinea pigs for 30 minutes while unexposed animals served as controls. In vivo fluorescence microscopy of the stria vascularis capillaries was performed after surgical exposure of 1 cochlea. ABR measurements were derived from the contralateral ear. After noise exposure, red blood cell velocity was reduced significantly by 24.3% (120 minutes) and further decreased to 44.5% at the end of the observation (210 minutes) in contrast to stable control measurements. Vessel diameters were not affected in both groups. A gradual decrease of segmental blood flow became significant (38.1%) after 150 minutes compared with controls. Hearing thresholds shifted significantly from 20.0 ± 5.5 dB SPL (0 minutes) to 32.5 ± 4.2 dB SPL (60 minutes) only in animals exposed to loud noise. With regard to novel treatments targeting the stria vascularis in NIHL, this standardized model allows us to analyze in detail cochlear microcirculation and hearing function in vivo.

Aescin-based topical formulation to prevent foot wounds and ulcerations in diabetic microangiopathy.

PubMed

Hu, S; Belcaro, G; Dugall, M; Hosoi, M; Togni, S; Maramaldi, G; Giacomelli, L

2016-10-01

Impairment of the peripheral microcirculation in diabetic patients often leads to severe complications in the lower extremities, such as foot infections and ulcerations. In this study, a novel aescin-based formulation has been evaluated as a potential approach to prevent skin breaks and ulcerations by improving the peripheral microcirculation and skin hydration. In this registry study, 63 patients with moderate diabetic microangiopathy were recruited. Informed participants freely decided to follow either a standard management (SM) to prevent diabetic foot diseases (n = 31) or SM associated with topical application of the aescin-based cream (n = 32). Peripheral microcirculatory parameters such as resting skin flux, venoarteriolar response and transcutaneous gas tension were evaluated at inclusion and after 8 weeks. In addition, several skin parameters of the foot area, such as integrity (as number of skin breaks/patients), hydration and content of dead cells were assessed at the defined observational study periods. Improvements in cutaneous peripheral microcirculation parameters were observed at 8 weeks in both groups; however, a remarkable and significant beneficial effect resulted to be exerted by the aescin-based cream treatment. In fact, the microcirculatory parameters evaluated significantly improved in the standard management + aescin-based cream group, compared with baseline and with the standard management group. Similar findings were reported for skin parameters of the foot area. The topical formulation containing aescin could represent a valid approach to manage skin wounds and prevent skin ulcerations in patients affected by moderate diabetic microangiopathy.

Cyanotic congenital heart disease the coronary arterial circulation.

PubMed

Perloff, Joseph K

2012-02-01

The coronary circulation in cyanotic congenital heart disease (CCHD) includes the extramural coronary arteries, basal coronary blood flow, flow reserve, the coronary microcirculation, and coronary atherogenesis. Coronary arteriograms were analyzed in 59 adults with CCHD. Dilated extramural coronaries were examined histologically in six patients. Basal coronary blood flow was determined with N-13 positron emission tomography in 14 patients and in 10 controls. Hyperemic flow was induced by intravenous dipyridamole pharmacologic stress. Immunostaining against SM alpha-actin permitted microcirculatory morphometric analysis. Non-fasting total cholesterols were retrieved in 279 patients divided into four groups: Group A---143 cyanotic unoperated, Group B---47 rendered acyanotic by reparative surgery, Group C---41 acyanotic unoperated, Group D---48 acyanotic before and after operation. Extramural coronary arteries were mildly or moderately dilated to ectatic in 49/59 angiograms. Histologic examination disclosed loss of medial smooth muscle, increased medial collagen, and duplication of internal elastic lamina. Basal coronary flow was appreciably increased. Hyperemic flow was comparable to controls. Remodeling of the microcirculation was based upon coronary arteriolar length, volume and surface densities. Coronary atherosclerosis was absent in both the arteriograms and the necropsy specimens. Extramural coronary arteries in CCHD dilate in response to endothelial vasodilator substances supplemented by mural attenuation caused by medial abnormalities. Basal coronary flow was appreciably increased, but hyperemic flow was normal. Remodeling of the microcirculation was responsible for preservation of flow reserve. The coronaries were atheroma-free because of the salutory effects of hypocholesterolemia, hypoxemia, upregulated nitric oxide, low platelet counts, and hyperbilirubinrmia.

[Influences of high-voltage electrical burns on microcirculation perfusion on serosal surface of small intestine of rats and the interventional effects of pentoxifylline].

PubMed

Zhang, Q F; Xu, S J; Liang, L M; Feng, J K; Xu, Y F; Tu, L L

2017-03-20

Objective: To investigate influences of high-voltage electrical burns on microcirculation perfusion on serosal surface of small intestine of rats and the interventional effects of pentoxifylline (PTX). Methods: Totally 180 SD rats were divided into sham injury group, simple electrical burn group, and treatment group according to the random number table, with 60 rats in each group. The electrical current was applied to the outside proximal part of left forelimb of rats and exited from the outside proximal part of right hind limb of rats. Rats in simple electrical burn group and treatment group were inflicted with high-voltage electrical burn wounds of 1cm×1cm at current entrances and exits, with the voltage regulator and experimental transformer. Rats in sham injury group were sham injured through connecting the same equipments without electricity. At 2 min post injury, rats in sham injury group and simple electrical burn group were intraperitoneally injected with 2 mL normal saline, and rats in treatment group were injected with 2 mL PTX injection (50 mg/mL). At 15 min before injury and 5 min, 1 h, 2 h, 4 h, and 8 h post injury, 10 rats in each group were selected to collect blood of heart respectively. Serum were separated from the blood to determine the level of soluble vascular cell adhesion molecule-1(sVCAM-1) with enzyme-linked immunosorbent assay method. The number of adhesional leukocyte in mesenteric venule of rats was determined with Bradford variable projection microscope system. The microcirculation perfusion on serosal surface of small intestine of rats was detected with laser Doppler perfusion imager. Data were processed with analysis of variance of factorial design and LSD test. Results: (1) At 5 min, 1 h, 2 h, 4 h, 8 h post injury, the serum content of sVCAM-1 in rats of simple electrical burn group were (8 502±1 158), (11 793±3 310), (9 960±2 146), (9 708±1 429), (7 292±1 386) ng/mL respectively, higher than that in sham injury group and treatment group [ (1 897±946), (1 882±940), (1 882±938), (1 888±946), (1 884±942) ng/mL, and (6 840±1 558), (6 742±2 465), (5 625±2 593), (2 373±1 463), (5 187±2 797) ng/mL, respectively, with P values below 0.001]. The serum content of sVCAM-1 in rats of sham injury group and treatment group at all time points post injury, except 4 h post injury of treatment group, was higher than that of the same group at 15 min before injury (with P values below 0.001). (2) At all time points post injury, the number of adhesional leukocyte in mesenteric venule of rats in simple electrical burn group was higher than that in sham injury group and treatment group (with P values below 0.001). The number of adhesional leukocyte in mesenteric venule of rats in simple electrical burn group and treatment group at all time points post injury was higher than that of the same group at 15 min before injury (with P values below 0.001). (3) At all time points post injury, the microcirculation perfusion on serosal surface of small intestine of rats in simple electrical burn group was lower than that in sham injury group and treatment group (with P values below 0.001). The microcirculation perfusion on serosal surface of small intestine of rats in simple electrical burn group and treatment group at all time points post injury was lower than that of the same group at 15 min before injury (with P values below 0.001). Conclusions: High-voltage electrical burns can increase the serum content of sVCAM-1, the number of adhesional leukocyte in mesenteric venule, and reduce microcirculation perfusion on serosal surface of small intestine of rats. PTX can inhibit secretion of serum sVCAM-1, reduce the number of adhensional leukocyte in mesenteric venule to alleviate microcirculation disturbance caused by high-voltage electrical burns.

A multigear protocol for sampling crayfish assemblages in Gulf of Mexico coastal streams

Treesearch

William R. Budnick; William E. Kelso; Susan B. Adams; Michael D. Kaller

2018-01-01

Identifying an effective protocol for sampling crayfish in streams that vary in habitat and physical/chemical characteristics has proven problematic. We evaluated an active, combined-gear (backpack electrofishing and dipnetting) sampling protocol in 20 Coastal Plain streams in Louisiana. Using generalized linear models and rarefaction curves, we evaluated environmental...

Modeling of the 35-mm Rarefaction Wave Gun

DTIC Science & Technology

2006-05-01

16 Figure 9. Shot 2-6-2; light piston, early vent, high- pressure group : gauge P1 (line) and...2-6-3; light piston, early vent, low- pressure group : gauge P1 (line) and simulation (dot...18 Figure 11. Gun travel; light piston, early vent, high- pressure group : shot 2-6-1

Rarefaction Wave Eliminator Concepts For A Large Blast/Thermal Simulator.

DTIC Science & Technology

1985-02-01

hard copies of the pressure-time records. Final data process- ing was completed with the computer, printer , and plotter. Plots of pressure- time records...F ATTN: Prof 0. Zinke Fayetteville, AR 72701 Cdr, CRDC, AMCCOM ATTI: 4O-SPS-IL University of California PM=-J Lawrence Livermore Lab SOM-RSP-A ATTN

Limited sampling hampers “big data” estimation of species richness in a tropical biodiversity hotspot

PubMed Central

Engemann, Kristine; Enquist, Brian J; Sandel, Brody; Boyle, Brad; Jørgensen, Peter M; Morueta-Holme, Naia; Peet, Robert K; Violle, Cyrille; Svenning, Jens-Christian

2015-01-01

Macro-scale species richness studies often use museum specimens as their main source of information. However, such datasets are often strongly biased due to variation in sampling effort in space and time. These biases may strongly affect diversity estimates and may, thereby, obstruct solid inference on the underlying diversity drivers, as well as mislead conservation prioritization. In recent years, this has resulted in an increased focus on developing methods to correct for sampling bias. In this study, we use sample-size-correcting methods to examine patterns of tropical plant diversity in Ecuador, one of the most species-rich and climatically heterogeneous biodiversity hotspots. Species richness estimates were calculated based on 205,735 georeferenced specimens of 15,788 species using the Margalef diversity index, the Chao estimator, the second-order Jackknife and Bootstrapping resampling methods, and Hill numbers and rarefaction. Species richness was heavily correlated with sampling effort, and only rarefaction was able to remove this effect, and we recommend this method for estimation of species richness with “big data” collections. PMID:25692000

Global effects of land use on local terrestrial biodiversity.

PubMed

Newbold, Tim; Hudson, Lawrence N; Hill, Samantha L L; Contu, Sara; Lysenko, Igor; Senior, Rebecca A; Börger, Luca; Bennett, Dominic J; Choimes, Argyrios; Collen, Ben; Day, Julie; De Palma, Adriana; Díaz, Sandra; Echeverria-Londoño, Susy; Edgar, Melanie J; Feldman, Anat; Garon, Morgan; Harrison, Michelle L K; Alhusseini, Tamera; Ingram, Daniel J; Itescu, Yuval; Kattge, Jens; Kemp, Victoria; Kirkpatrick, Lucinda; Kleyer, Michael; Correia, David Laginha Pinto; Martin, Callum D; Meiri, Shai; Novosolov, Maria; Pan, Yuan; Phillips, Helen R P; Purves, Drew W; Robinson, Alexandra; Simpson, Jake; Tuck, Sean L; Weiher, Evan; White, Hannah J; Ewers, Robert M; Mace, Georgina M; Scharlemann, Jörn P W; Purvis, Andy

2015-04-02

Human activities, especially conversion and degradation of habitats, are causing global biodiversity declines. How local ecological assemblages are responding is less clear--a concern given their importance for many ecosystem functions and services. We analysed a terrestrial assemblage database of unprecedented geographic and taxonomic coverage to quantify local biodiversity responses to land use and related changes. Here we show that in the worst-affected habitats, these pressures reduce within-sample species richness by an average of 76.5%, total abundance by 39.5% and rarefaction-based richness by 40.3%. We estimate that, globally, these pressures have already slightly reduced average within-sample richness (by 13.6%), total abundance (10.7%) and rarefaction-based richness (8.1%), with changes showing marked spatial variation. Rapid further losses are predicted under a business-as-usual land-use scenario; within-sample richness is projected to fall by a further 3.4% globally by 2100, with losses concentrated in biodiverse but economically poor countries. Strong mitigation can deliver much more positive biodiversity changes (up to a 1.9% average increase) that are less strongly related to countries' socioeconomic status.

Shock, release and reshock of PBX 9502: experiments and modeling

NASA Astrophysics Data System (ADS)

Aslam, Tariq; Gustavsen, Richard; Whitworh, Nicholas; Menikoff, Ralph; Tarver, Craig; Handley, Caroline; Bartram, Brian

2017-06-01

We examine shock, release and reshock into the tri-amino-tri-nitro-benzene (TATB) based explosive PBX 9502 (95% TATB, 5% Kel-F 800) from both an experimental and modeling point of view. The experiments are performed on the 2-stage light gas gun at Los Alamos National Laboratory and are composed of a multi-layered impactor impinging on PBX 9502 backed by a polymethylmethacrylate window. The objective is to initially shock the PBX 9502 in the 7 GPa range (too weak to start significant reaction), then allow a rarefaction fan to release the material to a lower pressure/temperature state. Following this release, a strong second shock will recompress the PBX. If the rarefaction fan releases the PBX to a very low pressure, the ensuing second shock can increase the entropy and temperature substantially more than in previous double-shock experiments without an intermediate release. Predictions from a variety of reactive burn models (AWSD, CREST, Ignition and Growth, SURF) demonstrate significantly different behaviors and thus the experiments are an excellent validation test of the models, and may suggest improvements for subsequent modeling efforts.

Conceptual and statistical problems associated with the use of diversity indices in ecology.

PubMed

Barrantes, Gilbert; Sandoval, Luis

2009-09-01

Diversity indices, particularly the Shannon-Wiener index, have extensively been used in analyzing patterns of diversity at different geographic and ecological scales. These indices have serious conceptual and statistical problems which make comparisons of species richness or species abundances across communities nearly impossible. There is often no a single statistical method that retains all information needed to answer even a simple question. However, multivariate analyses could be used instead of diversity indices, such as cluster analyses or multiple regressions. More complex multivariate analyses, such as Canonical Correspondence Analysis, provide very valuable information on environmental variables associated to the presence and abundance of the species in a community. In addition, particular hypotheses associated to changes in species richness across localities, or change in abundance of one, or a group of species can be tested using univariate, bivariate, and/or rarefaction statistical tests. The rarefaction method has proved to be robust to standardize all samples to a common size. Even the simplest method as reporting the number of species per taxonomic category possibly provides more information than a diversity index value.

Limited sampling hampers "big data" estimation of species richness in a tropical biodiversity hotspot.

PubMed

Engemann, Kristine; Enquist, Brian J; Sandel, Brody; Boyle, Brad; Jørgensen, Peter M; Morueta-Holme, Naia; Peet, Robert K; Violle, Cyrille; Svenning, Jens-Christian

2015-02-01

Macro-scale species richness studies often use museum specimens as their main source of information. However, such datasets are often strongly biased due to variation in sampling effort in space and time. These biases may strongly affect diversity estimates and may, thereby, obstruct solid inference on the underlying diversity drivers, as well as mislead conservation prioritization. In recent years, this has resulted in an increased focus on developing methods to correct for sampling bias. In this study, we use sample-size-correcting methods to examine patterns of tropical plant diversity in Ecuador, one of the most species-rich and climatically heterogeneous biodiversity hotspots. Species richness estimates were calculated based on 205,735 georeferenced specimens of 15,788 species using the Margalef diversity index, the Chao estimator, the second-order Jackknife and Bootstrapping resampling methods, and Hill numbers and rarefaction. Species richness was heavily correlated with sampling effort, and only rarefaction was able to remove this effect, and we recommend this method for estimation of species richness with "big data" collections.

On the Asymmetric Zero-Range in the Rarefaction Fan

NASA Astrophysics Data System (ADS)

Gonçalves, Patrícia

2014-02-01

We consider one-dimensional asymmetric zero-range processes starting from a step decreasing profile leading, in the hydrodynamic limit, to the rarefaction fan of the associated hydrodynamic equation. Under that initial condition, and for totally asymmetric jumps, we show that the weighted sum of joint probabilities for second class particles sharing the same site is convergent and we compute its limit. For partially asymmetric jumps, we derive the Law of Large Numbers for a second class particle, under the initial configuration in which all positive sites are empty, all negative sites are occupied with infinitely many first class particles and there is a single second class particle at the origin. Moreover, we prove that among the infinite characteristics emanating from the position of the second class particle it picks randomly one of them. The randomness is given in terms of the weak solution of the hydrodynamic equation, through some sort of renormalization function. By coupling the constant-rate totally asymmetric zero-range with the totally asymmetric simple exclusion, we derive limiting laws for more general initial conditions.

Solitary waves in dusty plasmas with weak relativistic effects in electrons and ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalita, B. C., E-mail: bckalita123@gmail.com; Choudhury, M., E-mail: choudhurymamani@gmail.com

2016-10-15

Two distinct classes of dust ion acoustic (DIA) solitary waves based on relativistic ions and electrons, dust charge Z{sub d} and ion-to-dust mass ratio Q’ = m{sub i}/m{sub d} are established in this model of multicomponent plasmas. At the increase of mass ratio Q’ due to increase of relativistic ion mass and accumulation of more negative dust charges into the plasma causing decrease of dust mass, relativistic DIA solitons of negative potentials are abundantly observed. Of course, relativistic compressive DIA solitons are also found to exist simultaneously. Further, the decrease of temperature inherent in the speed of light c causesmore » the nonlinear term to be more active that increases the amplitude of the rarefactive solitons and dampens the growth of compressive solitons for relatively low and high mass ratio Q’, respectively. The impact of higher initial streaming of the massive ions is observed to identify the point of maximum dust density N{sub d} to yield rarefactive relativistic solitons of maximum amplitude.« less

Global effects of land use on local terrestrial biodiversity

NASA Astrophysics Data System (ADS)

Newbold, Tim; Hudson, Lawrence N.; Hill, Samantha L. L.; Contu, Sara; Lysenko, Igor; Senior, Rebecca A.; Börger, Luca; Bennett, Dominic J.; Choimes, Argyrios; Collen, Ben; Day, Julie; de Palma, Adriana; Díaz, Sandra; Echeverria-Londoño, Susy; Edgar, Melanie J.; Feldman, Anat; Garon, Morgan; Harrison, Michelle L. K.; Alhusseini, Tamera; Ingram, Daniel J.; Itescu, Yuval; Kattge, Jens; Kemp, Victoria; Kirkpatrick, Lucinda; Kleyer, Michael; Correia, David Laginha Pinto; Martin, Callum D.; Meiri, Shai; Novosolov, Maria; Pan, Yuan; Phillips, Helen R. P.; Purves, Drew W.; Robinson, Alexandra; Simpson, Jake; Tuck, Sean L.; Weiher, Evan; White, Hannah J.; Ewers, Robert M.; Mace, Georgina M.; Scharlemann, Jörn P. W.; Purvis, Andy

2015-04-01

Human activities, especially conversion and degradation of habitats, are causing global biodiversity declines. How local ecological assemblages are responding is less clear--a concern given their importance for many ecosystem functions and services. We analysed a terrestrial assemblage database of unprecedented geographic and taxonomic coverage to quantify local biodiversity responses to land use and related changes. Here we show that in the worst-affected habitats, these pressures reduce within-sample species richness by an average of 76.5%, total abundance by 39.5% and rarefaction-based richness by 40.3%. We estimate that, globally, these pressures have already slightly reduced average within-sample richness (by 13.6%), total abundance (10.7%) and rarefaction-based richness (8.1%), with changes showing marked spatial variation. Rapid further losses are predicted under a business-as-usual land-use scenario; within-sample richness is projected to fall by a further 3.4% globally by 2100, with losses concentrated in biodiverse but economically poor countries. Strong mitigation can deliver much more positive biodiversity changes (up to a 1.9% average increase) that are less strongly related to countries' socioeconomic status.

Anomalous width variations for ion acoustic rarefactive solitary waves in a warm ion plasma with two electron temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, S.S.; Sekar Iyengar, A.N.

1997-09-01

Anomalous width{endash}amplitude variations were observed in large amplitude rarefactive solitary waves which show increasing width with increasing amplitude, contrasting the usual reciprocal relation between the square of the width and the amplitude, beyond a certain value of the plasma parameters [S. S. Ghosh, K. K. Ghosh, and A. N. Sekar Iyengar, Phys. Plasmas, {bold 3}, 3939 (1996)]. For the limiting maximum amplitude, the {open_quotes}increasing width{close_quotes} solitary wave tends to a double layer-like solution. The overall variation was found to depend crucially on the specific parameter space. From a detailed investigation of the above behavior, a plausible physical explanation has beenmore » presented for such increases in the width. It is found that the ions{close_quote} initial kinetic energies and the cold electron concentration within the perturbed region play a significant role in determining the observed width{endash}amplitude variation. This contradicts the investigation of Sayal, Yadav, and Sharma [Phys. Scr. {bold 47}, 576 (1993)]. {copyright} {ital 1997 American Institute of Physics.}« less

Verification Test of the SURF and SURFplus Models in xRage: Part II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menikoff, Ralph

2016-06-20

The previous study used an underdriven detonation wave (steady ZND reaction zone profile followed by a scale invariant rarefaction wave) for PBX 9502 as a validation test of the implementation of the SURF and SURFplus models in the xRage code. Even with a fairly fine uniform mesh (12,800 cells for 100mm) the detonation wave profile had limited resolution due to the thin reaction zone width (0.18mm) for the fast SURF burn rate. Here we study the effect of finer resolution by comparing results of simulations with cell sizes of 8, 2 and 1 μm, which corresponds to 25, 100 andmore » 200 points within the reaction zone. With finer resolution the lead shock pressure is closer to the von Neumann spike pressure, and there is less noise in the rarefaction wave due to fluctuations within the reaction zone. As a result the average error decreases. The pointwise error is still dominated by the smearing the pressure kink in the vicinity of the sonic point which occurs at the end of the reaction zone.« less

A Standardized Composition Comprised of Extracts from Rosmarinus officinalis, Annona squamosa and Zanthoxylum clava-herculis for Cellulite

PubMed Central

Yimam, Mesfin; Lee, Young-Chul; Jiao, Ping; Hong, Mei; Brownell, Lidia; Jia, Qi

2017-01-01

Background: Cellulite, characterized by changes in the skin morphology presented as dimpled or puckered skin appearance, is highly prevalent among postadolescent women. Cellulite management ranges from topical cream applications to invasive procedures. While some interventions showed improvements in physical appearances of affected areas, so far, none have reversed the condition to a full recovery. These unsuccessful measures signify the intricate nature of cellulite etiology highlighting its complexity leading to the possibility for a combination treatment approach to target multiple mechanisms. Materials and Methods: We screened our plant library for extracts that reduce cellular lipid accumulation, improve microcirculation, possess high total antioxidant capacity, significant anti-platelet aggregation, and anti-inflammatory activities using lipid accumulation assay in 3T3-L1 cells, Croton oil-induced hemorrhoid test in rats as a model for microcirculation, anti-platelet aggregation assay, nitric oxide (NO) inhibition assay, and 1,1-diphenyl-2-picrylhydrazyl assay. Results: Three known botanicals such as Rosemary officinalis, Annona squamosa and Zanthoxylum clava-herculis were identified as lead extracts in these tests. Treatment of 3T3 cell with A. squamosa at 1 μg/ml resulted in 68.8% reduction in lipid accumulation. In croton oil-induced hemorrhoid study, Z. clava-herculis reduced the recto-anus coefficient by 79.6% at 6 mg/kg indicating improvement in microcirculations. Similarly, R. officinalis caused inhibition of 82%, 71.8%, and 91.8% in platelet aggregation, NO production and free radical generation at 31.25 μg/ml, 6.2 μg/ml, and 40 μg/ml concentrations suggesting its anti-oxidant, and anti-inflammatory activities. Conclusions: Data depicted here suggest that formulation of these well-known botanicals at a specific ratio perhaps may yield a composition with a much wider spectrum of mechanisms of actions to impact the multiple pathways involved in cellulite onset, continuation, or exacerbations. SUMMARY Cellulite represents one of the main esthetic concerns of women with a likely cause of psychological insecurities. Its pathophysiology involves multiple pathways that include vascular, adipose tissues, inflammation, structural and physiological.Treatment strategies for cellulite comprises increasing microcirculation flow, reducing lipogenesis, promoting lipolysis, free radicals scavenging or formation reduction, anti-inflammation and other invasive procedures.We screened our plant library for extracts that reduces cellular lipid accumulation, improves microcirculation, possesses high total antioxidant capacity, inhibits platelet aggregation, and moderates inflammation.Botanical extracts from Rosmarinus officinalis, Annona squamosa and Zanthoxylum clava-herculis were identified as leads and formulated to yield a standardized composition designated as UP1307 and suggested its usage for cellulite. Abbreviations Used: GMP: Good Manufacturing Practice; CA: Carnosic acid; NF-kB: nuclear factor-kB; HPLC: high-performance liquid chromatography; EtOH: Ethanol; DMEM: Dulbecco's modified Eagle's medium; FBS: fetal bovine serum; SD: Sprague Dawley; RAC: recto-anus coefficient; LPS: Lipopolysaccharide; DPPH: 1,1-diphenyl-2-picryl-hydrazyl; TNF-α: tumor necrosis factor; NO: Nitric oxide PMID:29263624

Multimodal OCT for complex assessment of tumors response to therapy

NASA Astrophysics Data System (ADS)

Sirotkina, Marina A.; Kiseleva, Elena B.; Gubarkova, Ekaterina V.; Matveev, Lev A.; Zaitsev, Vladimir Yu.; Matveyev, Alexander L.; Shirmanova, Marina V.; Sovetsky, Alexander A.; Moiseev, Alexander A.; Zagaynova, Elena V.; Vitkin, Alex; Gladkova, Natalia D.

2017-07-01

Multimodal OCT is a promising tool for monitoring of individual tumor response to antitumor therapies. The changes of tumor cells, connective tissue, microcirculation and stiffness can be estimated simultaneously in real time with high resolution.

Wavelet analysis of skin perfusion to assess the effects of FREMS therapy before and after occlusive reactive hyperemia.

PubMed

Popa, Stefan Octavian; Ferrari, Myriam; Andreozzi, Giuseppe Maria; Martini, Romeo; Bagno, Andrea

2015-11-01

Laser Doppler Fluxmetry is used to evaluate the hemodynamics of skin microcirculation. Laser Doppler signals contain oscillations due to fluctuations of microvascular perfusion. By performing spectral analysis, six frequency intervals from 0.005 to 2 Hz have been identified and assigned to distinct cardiovascular structures: heart, respiration, vascular myocites, sympathetic terminations and endothelial cells (dependent and independent on nitric oxide). Transcutaneous electrical pulses are currently applied to treat several diseases, i.e. neuropathies and chronic painful leg ulcers. Recently, FREMS (Frequency Rhythmic Electrical Modulation System) has been applied to vasculopathic patients, too. In this study Laser Doppler signals of skin microcirculation were measured in five patients with intermittent claudication, before and after the FREMS therapy. Changes in vascular activities were assessed by wavelet transform analysis. Preliminary results demonstrate that FREMS induces alterations in vascular activities. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Microcirculation of the pancreas. A quantitative study of physiology and changes in pancreatitis.

PubMed

Klar, E; Endrich, B; Messmer, K

1990-02-01

A rabbit model was designed to study the microcirculation of the pancreas with special reference to changes occurring during acute pancreatitis. Intravital microscopy was used in conjunction with video techniques allowing for continuous observation and off-line evaluation of microvessel diameters and blood cell velocities. Based on the microvessel geometry a functional microvascular unit could be defined at the level of the pancreatic lobule consisting of intralobular arteries and veins and an arcade-like preferential pathway framing the capillary network. Experimental acute pancreatitis resulted in immediate leakage of the macromolecular plasma marker (FITC-Dextran 70) from the microvasculature suggesting increased permeability. In contrast to control conditions, pancreatic capillaries were excluded from the circulation during acute pancreatitis starting 30 min after induction with only single capillaries remaining perfused after 3 hours. At the same time, there was constant blood flow through the preferential pathways representing shunt perfusion.

Evaluation of blood microcirculation parameters by combined use of laser Doppler flowmetry and videocapillaroscopy methods

NASA Astrophysics Data System (ADS)

Volkov, M. V.; Kostrova, D. A.; Margaryants, N. B.; Gurov, I. P.; Erofeev, N. P.; Dremin, V. V.; Zharkikh, E. V.; Zherebtsov, E. A.; Kozlov, I. O.; Dunaev, A. V.

2017-03-01

Laser Doppler flowmetry (LDF) is widely used for diagnosing blood microcirculation diseases. It is well known that the Doppler shift of laser radiation scattered by moving red blood cells (RBC) can be assessed through analyzing photocurrent produced by a photodetector. LDF signal contains information about regulating blood flow rhythms: myogenic, cardiac, nervous and endothelial. The method of videocapillaroscopy (VCS) allows local capillary blood flow velocity evaluation and, using video data processing algorithms, is able to assess RBC velocity changes into capillary. We present the results of simultaneous investigations of changes in tissue perfusion of the distal phalanx of human finger by the LDF as well as changes in capillary blood flow velocity in the nail bed evaluated by the VCS method during arterial occlusion test. The experimental results confirmed the correspondence between blood perfusion and blood flow velocity.

Two dimensional microcirculation mapping with real time spatial frequency domain imaging

NASA Astrophysics Data System (ADS)

Zheng, Yang; Chen, Xinlin; Lin, Weihao; Cao, Zili; Zhu, Xiuwei; Zeng, Bixin; Xu, M.

2018-02-01

We present a spatial frequency domain imaging (SFDI) study of local hemodynamics in the human finger cuticle of healthy volunteers performing paced breathing and the forearm of healthy young adults performing normal breathing with our recently developed Real Time Single Snapshot Multiple Frequency Demodulation - Spatial Frequency Domain Imaging (SSMD-SFDI) system. A two-layer model was used to map the concentrations of deoxy-, oxy-hemoglobin, melanin, epidermal thickness and scattering properties at the subsurface of the forearm and the finger cuticle. The oscillations of the concentrations of deoxy- and oxy-hemoglobin at the subsurface of the finger cuticle and forearm induced by paced breathing and normal breathing, respectively, were found to be close to out-of-phase, attributed to the dominance of the blood flow modulation by paced breathing or heartbeat. Our results suggest that the real time SFDI platform may serve as one effective imaging modality for microcirculation monitoring.

The vascular neural network—a new paradigm in stroke pathophysiology

PubMed Central

Zhang, John H.; Badaut, Jerome; Tang, Jiping; Obenaus, Andre; Hartman, Richard; Pearce, William J.

2013-01-01

The concept of the neurovascular unit as the key brain component affected by stroke is controversial, because current definitions of this entity neglect mechanisms that control perfusion and reperfusion of arteries and arterioles upstream of the cerebral microcirculation. Indeed, although definitions vary, many researchers consider the neurovascular unit to be restricted to endothelial cells, neurons and glia within millimetres of the cerebral capillary microcirculation. This Perspectives article highlights the roles of vascular smooth muscle, endothelial cells and perivascular innervation of cerebral arteries in the initiation and progression of, and recovery from, ischaemic stroke. The concept of the vascular neural network—which includes cerebral arteries, arterioles, and downstream neuronal and glial cell types and structures—is introduced as the fundamental component affected by stroke pathophysiology. The authors also propose that the vascular neural network should be considered the main target for future therapeutic intervention after cerebrovascular insult. PMID:23070610

Label-free in vivo optical micro-angiography imaging of cerebral capillary blood flow within meninges and cortex in mice with the skull left intact

NASA Astrophysics Data System (ADS)

Jia, Yali; Wang, Ruikang K.

2011-03-01

Abnormal microcirculation within meninges is common in many neurological diseases. There is a need for an imaging method that is capable of visualizing functional meningeal microcirculations alone, preferably decoupled from the cortical blood flow. Optical microangiography (OMAG) is a recently developed label-free imaging method capable of producing 3D images of dynamic blood perfusion within micro-circulatory tissue beds at an imaging depth up to ~2 mm, with an unprecedented imaging sensitivity to the blood flow at ~4 μm/s. In this study, we demonstrate the utility of ultra-high sensitive OMAG in imaging the detailed blood flow distributions, at a capillary level resolution, within meninges and cortex in mice with the cranium left intact. The results indicate that OMAG can be a valuable tool for the study of meningeal circulations.

State of the art on nailfold capillaroscopy: a reliable diagnostic tool and putative biomarker in rheumatology?

PubMed

Cutolo, Maurizio; Smith, Vanessa

2013-11-01

Capillaroscopy is a non-invasive and safe tool to morphologically study the microcirculation. In rheumatology it has a dual use. First, it has a role in differential diagnosis of patients with RP. Second, it may have a role in the prediction of clinical complications in CTDs. In SSc, pilot studies have shown predictive associations with peripheral vascular and lung involvement hinting at a role of capillaroscopy as putative biomarker. Also and logically, in SSc, microangiopathy, as assessed by capillaroscopy, has been associated with markers of the disease such as angiogenic/static factors and SSc-specific antibodies. Moreover, morphological assessments of the microcirculation (capillaroscopy) seem to correlate with functional assessments (such as laser Doppler). Because of its clinical and research role, eyes are geared in Europe to expand the knowledge of this tool. Both the European League Against Rheumatism (EULAR) and the ACR are stepping forward to this need.

Application of optical non-invasive methods to diagnose the state of the lower limb tissues in patients with diabetes mellitus

NASA Astrophysics Data System (ADS)

Zharkikh, E. V.; Dremin, V. V.; Filina, M. A.; Makovik, I. N.; Potapova, E. V.; Zherebtsov, E. A.; Zherebtsova, A. I.; Dunaev, A. V.

2017-11-01

The paper shows the possibility of assessing the functional state of microcirculatory-tissue systems of patients with diabetes mellitus by laser Doppler flowmetry (LDF), diffuse reflectance spectroscopy (DRS) and fluorescence spectroscopy (FS) methods. A review of the existing non-invasive optical technologies used to assess the state of microcirculation and oxygen metabolism in tissues of patients with diabetes is conducted. A series of experimental studies involving 76 patients with diabetes and 46 healthy volunteers was carried out. A wavelet analysis of LDF-grams was used to evaluate the adaptive changes of microcirculation during the temperature tests. The obtained data revealed that the proposed methodology in the form of combined use of several diagnostic technologies (LDF, FS and DRS) allows us to detect the presence or absence of trophic disorders and to evaluate adaptation processes during thermal tests.

Cyanotic Congenital Heart Disease The Coronary Arterial Circulation

PubMed Central

Perloff, Joseph K

2012-01-01

Background: The coronary circulation in cyanotic congenital heart disease (CCHD) includes the extramural coronary arteries, basal coronary blood flow, flow reserve, the coronary microcirculation, and coronary atherogenesis. Methods: Coronary arteriograms were analyzed in 59 adults with CCHD. Dilated extramural coronaries were examined histologically in six patients. Basal coronary blood flow was determined with N-13 positron emission tomography in 14 patients and in 10 controls. Hyperemic flow was induced by intravenous dipyridamole pharmacologic stress. Immunostaining against SM alpha-actin permitted microcirculatory morphometric analysis. Non-fasting total cholesterols were retrieved in 279 patients divided into four groups: Group A---143 cyanotic unoperated, Group B---47 rendered acyanotic by reparative surgery, Group C---41 acyanotic unoperated, Group D---48 acyanotic before and after operation. Results: Extramural coronary arteries were mildly or moderately dilated to ectatic in 49/59 angiograms. Histologic examination disclosed loss of medial smooth muscle, increased medial collagen, and duplication of internal elastic lamina. Basal coronary flow was appreciably increased. Hyperemic flow was comparable to controls. Remodeling of the microcirculation was based upon coronary arteriolar length, volume and surface densities. Coronary atherosclerosis was absent in both the arteriograms and the necropsy specimens. Conclusions: Extramural coronary arteries in CCHD dilate in response to endothelial vasodilator substances supplemented by mural attenuation caused by medial abnormalities. Basal coronary flow was appreciably increased, but hyperemic flow was normal. Remodeling of the microcirculation was responsible for preservation of flow reserve. The coronaries were atheroma-free because of the salutory effects of hypocholesterolemia, hypoxemia, upregulated nitric oxide, low platelet counts, and hyperbilirubinrmia. PMID:22845810

Analysis of serial coronary artery flow patterns early after primary angioplasty: new insights into the dynamics of the microcirculation.

PubMed

Sharif, Dawod; Rofe, Guy; Sharif-Rasslan, Amal; Goldhammer, Ehud; Makhoul, Nabeel; Shefer, Arie; Hassan, Amin; Rauchfleisch, Shmuel; Rosenschein, Uri

2008-06-01

The temporal behavior of the coronary microcirculation in acute myocardial infarction may affect outcome. Diastolic deceleration time and early systolic flow reversal derived from coronary artery blood flow velocity patterns reflect microcirculatory function. To assess left anterior descending coronary artery flow velocity patterns using Doppler transthoracic echocardiography after primary percutaneous coronary intervention, in patients with anterior AMI. Patterns of flow velocity patterns of the LAD were obtained using transthoracic echocardiography-Doppler in 31 consecutive patients who presented with anterior AMI. Measurements were done at 6 hours, 36-48 hours, and 5 days after successful PPCI. Measurements of DDT and pressure half times (Pt%), as well as observation for ESFR were performed. In the first 2 days following PPCI, the average DDT (600 +/- 340 msec) was shorter than on day 5 (807 +/- 332 msec) (P < 0.012), FVP in the first 2 days were dynamic and bidirectional: from short DDT (< 600 msec) to long DDT (> 600 msec) and vice versa. On day 5 most DDTs became longer. Pt1/2 at 6 hours was not different than at day 2 (174 +/- 96 vs. 193 +/- 99 msec, P = NS) and became longer on day 5 (235 +/- 98 msec, P = 0.012). Bidirectional patterns were also observed in the ESFR in 6 patients (19%) at baseline, in 4 (13%) at 36 hours, and in 2 (6.5%) on day 5 after PPCI. Flow velocity patterns of the LAD after PPCI in AMI are dynamic and reflect unpredictable changes in microcirculation.

Quantitative intravital two-photon excitation microscopy reveals absence of pulmonary vaso-occlusion in unchallenged Sickle Cell Disease mice

PubMed Central

Bennewitz, Margaret F; Watkins, Simon C; Sundd, Prithu

2014-01-01

Sickle cell disease (SCD) is a genetic disorder that leads to red blood cell (RBC) sickling, hemolysis and the upregulation of adhesion molecules on sickle RBCs. Chronic hemolysis in SCD results in a hyper-inflammatory state characterized by activation of circulating leukocytes, platelets and endothelial cells even in the absence of a crisis. A crisis in SCD is often triggered by an inflammatory stimulus and can lead to the acute chest syndrome (ACS), which is a type of lung injury and a leading cause of mortality among SCD patients. Although it is believed that pulmonary vaso-occlusion could be the phenomenon contributing to the development of ACS, the role of vaso-occlusion in ACS remains elusive. Intravital imaging of the cremaster microcirculation in SCD mice has been instrumental in establishing the role of neutrophil-RBC-endothelium interactions in systemic vaso-occlusion; however, such studies, although warranted, have never been done in the pulmonary microcirculation of SCD mice. Here, we show that two-photon excitation fluorescence microscopy can be used to perform quantitative analysis of neutrophil and RBC trafficking in the pulmonary microcirculation of SCD mice. We provide the experimental approach that enables microscopic observations under physiological conditions and use it to show that RBC and neutrophil trafficking is comparable in SCD and control mice in the absence of an inflammatory stimulus. The intravital imaging scheme proposed in this study can be useful in elucidating the cellular and molecular mechanism of pulmonary vaso-occlusion in SCD mice following an inflammatory stimulus. PMID:25995970

Acute effects of local cold therapy in superficial burns on pain, in vivo microcirculation, edema formation and histomorphology.

PubMed

Altintas, B; Altintas, A A; Kraemer, R; Sorg, H; Vogt, P M; Altintas, M A

2014-08-01

Local cold therapy for burns is generally recommended to relief pain and limit tissue damage, however, there is limited data of its physiological benefit. This study aimed to evaluate pathophysiological effects of cold therapy in superficial burn on microcirculation, edema formation, and histomorphology. In 12 volunteers (8f, 4m; aged 30.4±14.1 years) circumscribed superficial burn was induced on both hand back and either left untreated as control (control-group) or treated by local-cold-application (cold-treatment-group). Prior to burn (t0), immediately (t1), 15 min (t2), and 30 min (t3) following cold therapy, following parameter was evaluated using intravital-microscopy; epidermal-thickness (ET), granular-cell-size (GCS), individual-blood-cell-flow (IBCF), and functional-capillary-density (FCD). Both ET and GCS increased significantly more in control-group and slightly in cold-treatment-group in t1, while turns to insignificant t2 onwards. IBCF and FCD raised up in control-group compared to dramatically decrease in cold-treatment-group in t1. In t2 both parameter remains in control-group and increased in cold-treatment-group. Comparison of both groups for IBCF and FCD indicates significant difference in t1 and t2, however, insignificant in t0 and t3. Microcirculation, edema formation, and histomorphology of superficial burn has been significantly influenced through immediate cold therapy, however, this alterations are transient and turns to ineffective after 30 min. Copyright © 2013 Elsevier Ltd and ISBI. All rights reserved.

Second consensus on the assessment of sublingual microcirculation in critically ill patients: results from a task force of the European Society of Intensive Care Medicine.

PubMed

Ince, Can; Boerma, E Christiaan; Cecconi, Maurizio; De Backer, Daniel; Shapiro, Nathan I; Duranteau, Jacques; Pinsky, Michael R; Artigas, Antonio; Teboul, Jean-Louis; Reiss, Irwin K M; Aldecoa, Cesar; Hutchings, Sam D; Donati, Abele; Maggiorini, Marco; Taccone, Fabio S; Hernandez, Glenn; Payen, Didier; Tibboel, Dick; Martin, Daniel S; Zarbock, Alexander; Monnet, Xavier; Dubin, Arnaldo; Bakker, Jan; Vincent, Jean-Louis; Scheeren, Thomas W L

2018-03-01

Hand-held vital microscopes (HVMs) were introduced to observe sublingual microcirculatory alterations at the bedside in different shock states in critically ill patients. This consensus aims to provide clinicians with guidelines for practical use and interpretation of the sublingual microcirculation. Furthermore, it aims to promote the integration of routine application of HVM microcirculatory monitoring in conventional hemodynamic monitoring of systemic hemodynamic variables. In accordance with the Delphi method we organized three international expert meetings to discuss the various aspects of the technology, physiology, measurements, and clinical utility of HVM sublingual microcirculatory monitoring to formulate this consensus document. A task force from the Cardiovascular Dynamics Section of the European Society of Intensive Care Medicine (with endorsement of its Executive Committee) created this consensus as an update of a previous consensus in 2007. We classified consensus statements as definitions, requirements, and/or recommendations, with a minimum requirement of 80% agreement of all participants. In this consensus the nature of microcirculatory alterations is described. The nature of variables, which can be extracted from analysis of microcirculatory images, is presented and the needed dataset of variables to identify microcirculatory alterations is defined. Practical aspects of sublingual HVM measurements and the nature of artifacts are described. Eleven statements were formulated that pertained to image acquisitions and quality statements. Fourteen statements addressed the analysis of the images, and 13 statements are related to future developments. This consensus describes 25 statements regarding the acquisition and interpretation of microcirculatory images needed to guide the assessment of the microcirculation in critically ill patients.

A new model for studying the revascularization of skin grafts in vivo: the role of angiogenesis.

PubMed

Lindenblatt, Nicole; Calcagni, Maurizio; Contaldo, Claudio; Menger, Michael D; Giovanoli, Pietro; Vollmar, Brigitte

2008-12-01

Models of skin graft revascularization are based mostly on histologic evaluations but lack the possibility of analyzing the vascular biology in vivo. The aim of the present study was therefore to develop an animal model that allows continuous monitoring of the microcirculation during skin graft healing. Skin and subcutaneous tissue were removed from the back of dorsal skinfold chamber preparations in mice, leaving one layer of striated muscle and subcutaneous tissue as a wound bed (n = 5). A corresponding full-thickness skin graft was harvested from the groin and sutured into the defect in the back of the chamber. To study graft healing, repetitive intravital microscopy was performed during the first 10 days after engraftment. Capillary widening in the wound bed appeared at day 1 after grafting and increased until day 4. Capillary buds and sprouts first appeared at day 2. Blood filling of autochthonous graft capillaries occurred at day 3, resulting in almost complete restoration of the original skin microcirculation on day 5. This was achieved by interconnections between the microvasculature of the wound bed and the skin graft through a temporary angiogenic response. In principle, angiogenic blood vessel growth originated in the wound bed and was directed toward the graft. This new model allows for repetitive analysis of the microcirculation during skin graft healing. It provides ideal in vivo conditions to further delineate the exact mechanisms of blood vessel interconnection during the complex process of angiogenesis, and may also allow study of the vascularization of tissue-engineered skin substitutes.

[Obesity as pathology of adipocytes: number of cells, volume of arterial bloodstream,local pools of circulation in vivo, natriuretic peptides and arterial hypertension].

PubMed

Titov, V N; Dmitriev, V A

2015-03-01

The non-specific systemic biological reaction of arterial pressure from the level of organism. vasomotor center and proximal section of arterial bloodstream is appealed to compensate disorders of metabolism and microcirculation in distal section of arteries. This phenomenon occurs in several cases. The primarily local disorders of metabolism at autocrine level, physiological (aphysiological) death of cells, "littering" of intercellular medium become the cause of disorder of microcirculation in paracrin cenosises and deteriorate realization of biological functions of homeostasis, trophology, endoecology and adaptation. The local compensation of affected perfusion in paracrin cenosises at the expense of function of peripheral peristaltic pumps, redistribution of local bloodflow in biological reaction of endothelium-depended vaso-dilation has no possibility to eliminate disorders in realization of biological functions. The systemic increase of arterial pressure under absence of specific symptoms of symptomatic arterial hypertension is a test to detect disorder of biological functions of homeostasis, trophology, biological function of endoecology and adaptation. Allforms of arterial hypertension develop by common algorithm independently from causes of disorders of blood flow, microcirculation in distal section of arteries. The non-specific systemic compensation ofdisorders of metabolism from level of organism, in proximal section of arterial bloodstream always is the same one and results in aphysiological alterations in organs-targets. To comprehend etiological characteristics of common pathogenesis of arterial hypertension is possible in case of application of such technically complicated and still unclear in differential diagnostic of deranged functions modes of metabolomics.

SEM corrosion-casts study of the microcirculation of the flat bones in the rat.

PubMed

Pannarale, L; Morini, S; D'Ubaldo, E; Gaudio, E; Marinozzi, G

1997-04-01

Little is known about the organization of microcirculation in flat bones in comparison with long bones. This study, therefore, helps us to determine the design of this vascular system in flat bones in relation to their structure and function. The organization of microvasculature in parietal, scapula, and ileum bones of 15 young sexually mature rats, aged 6-7 weeks, was studied by light and scanning electron microscopy (SEM) from vascular corrosion cast (vcc), a resin-cast obtained material. Our observations show that the pattern of the microcirculation in flat bones is different in the thick and thin parts of such bones. Where the bone is thinner than 0.4 mm, only periosteal and dural network exist. Larger vessels which do not form a real network connect the two tables of the bones in these regions. In thicker areas, the organization of the microvasculature is similar to that in long bones, with distinct periosteal, cortical and bone marrow networks. Moreover, in different bones, outer networks show slightly different characteristics according to the different adjacent structures (dura mater, muscles etc.). Different types of vessels were recognized by comparing their different diameter, course and endothelial imprints. The microvascular patterns of the flat bones are strongly influenced by the bone thickness. The different microvascular systems can interact both with the bone modelling and remodeling and with the variable metabolic needs, modifying the microvascular pattern and the blood flow. This is even more important in view of the reciprocal influence of the different networks within the same bone.

The asymmetric facial skin perfusion distribution of Bell's palsy discovered by laser speckle imaging technology.

PubMed

Cui, Han; Chen, Yi; Zhong, Weizheng; Yu, Haibo; Li, Zhifeng; He, Yuhai; Yu, Wenlong; Jin, Lei

2016-01-01

Bell's palsy is a kind of peripheral neural disease that cause abrupt onset of unilateral facial weakness. In the pathologic study, it was evidenced that ischemia of facial nerve at the affected side of face existed in Bell's palsy patients. Since the direction of facial nerve blood flow is primarily proximal to distal, facial skin microcirculation would also be affected after the onset of Bell's palsy. Therefore, monitoring the full area of facial skin microcirculation would help to identify the condition of Bell's palsy patients. In this study, a non-invasive, real time and full field imaging technology - laser speckle imaging (LSI) technology was applied for measuring facial skin blood perfusion distribution of Bell's palsy patients. 85 participants with different stage of Bell's palsy were included. Results showed that Bell's palsy patients' facial skin perfusion of affected side was lower than that of the normal side at the region of eyelid, and that the asymmetric distribution of the facial skin perfusion between two sides of eyelid is positively related to the stage of the disease (P <  0.001). During the recovery, the perfusion of affected side of eyelid was increasing to nearly the same with the normal side. This study was a novel application of LSI in evaluating the facial skin perfusion of Bell's palsy patients, and we discovered that the facial skin blood perfusion could reflect the stage of Bell's palsy, which suggested that microcirculation should be investigated in patients with this neurological deficit. It was also suggested LSI as potential diagnostic tool for Bell's palsy.

Hypersonic Flow over a Cylinder with a Nanosecond-Pulse Electrical Discharge

DTIC Science & Technology

2013-01-01

variation in bow-shock location, but no other factors, including rarefaction effects due to partial-slip walls, made an appreciable difference in the bow...heat transfer coefficient, Ch = 2 q/(ρ∞ u 3 ∞) along the surface of the cylinder at various times after the ns-DBD pulse. The curves were spanwise

The Influence of Shock-Induced Air Bubble Collapse Resulting from Underwater Explosive Events

DTIC Science & Technology

2012-06-01

Pressure-Time History Results When comparing the pressure-time history in Figure 26, it is important to note the general shape of the curve . The...Indian Head, MD, Final Rep. IHTR 2589, May 28, 2004. [10] V. K. Kedrinskii, “ Rarefaction Waves and Bubbly Cavitation in Real Liquid,” presented at the

Modeling of the 105-mm Rarefaction Wave Gun

DTIC Science & Technology

2009-08-01

10  5.4  Recoil Brakes and Recuperators...guN (RAVEN) was invented by Kathe (1) to substantially reduce the recoil and, hence, the mass of the system that absorbs the recoil, while minimally...free recoil velocity is the velocity of the tube/piston system after the velocities equilibrate. The system utilizes a free recoil mount. The

[Treatment of small and sublingual salivary glands cysts by laser].

PubMed

Bogatov, V V; Vybornov, V V; Malinovskiĭ, I Iu

2011-01-01

The differents variants of treatment of retention cysts of mucous membrane of oral cavity and sublingual salivary gland cysts were presented and analysed. Results of doppler examination as a method of research blood microcirculation in postoperation time were presented.

[AETIOLOGY AND PATHOGENESIS GASTRO-DUODENALES ULCERATIVE LESIONS IN ELDERLY].

PubMed

Chernekhovskaya, N E; Povalayev, A V; Layshenko, G A

2015-01-01

In review today conceptions of view to aetiology and pathogenesis gastro-duodenales ulcerative lesions in elderly. Atherosclerosis, ischemic disease of the heart and hypertension are reasons of acute ulcers and erosions in elderly. The breaking of microcirculation are very importance.

Disruption of the blood-brain barrier as the primary effect of CNS irradiation.

PubMed

Rubin, P; Gash, D M; Hansen, J T; Nelson, D F; Williams, J P

1994-04-01

The blood-brain barrier (BBB) is believed to be unique in organ microcirculation due to the 'tight junctions' which exist between endothelial cells and, some argue, the additional functional components represented by the perivascular boundary of neuroglial cells; these selectively exclude proteins and drugs from the brain parenchyma. This study was designed to examine the effects of irradiation on the BBB and determine the impact of the altered pathophysiology on the production of central nervous system (CNS) late effects such as demyelination, gliosis and necrosis. Rats, irradiated at 60 Gy, were serially sacrificed at 2, 6, 12 and 24 weeks. Magnetic resonance image analysis (MRI) was obtained prior to sacrifice with selected animals from each group. The remaining animals underwent horse-radish peroxidase (HRP) perfusion at the time of sacrifice. The serial studies showed a detectable disruption of the BBB at 2 weeks post-irradiation and this was manifested as discrete leakage; late injury seen at 24 weeks indicated diffuse vasculature leakage, severe loss of the capillary network, cortical atrophy and white matter necrosis. Reversal or repair of radiation injury was seen between 6 and 12 weeks, indicating a bimodal peak in events. Blood-brain barrier disruption is an early, readily recognizable pathophysiological event occurring after radiation injury, is detectable in vivo/in vitro by MRI and HRP studies, and appears to precede white matter necrosis. Dose response studies over a wide range of doses, utilizing both external and interstitial irradiation, are in progress along with correlative histopathologic and ultrastructural studies.

Hypersonic Flow over a Cylinder with a Nanosecond Pulse Electrical Discharge

DTIC Science & Technology

2014-03-01

which found the uncertainty in freestream conditions accounted for a 3% variation in bow shock location, but no other factors, including rarefaction ...The curves were Flow X Y Z dρ/dx 200 100 Ring of Polyimide Tape (approx. 0.15 mm thick) a) Side-view Flow Shock Y X Z d /dx 200 100 b) Top-down view

Rarefaction Shock Wave Cutter for Offshore Oil-Gas Platform Removal Final Report CRADA No. TC02009.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glenn, L. A.; Barker, J.

This was a collaborative effort between Lawrence Livermore National Security, LLC/Lawrence Livermore National Laboratory (LLNL) (formerly the University of California) and Jet Research Center, a wholly owned division of Halliburton Energy Services, Inc. to design and prototype an improved explosive cutter for cutting the support legs of offshore oil and gas platforms.

Muscle-Specific Vascular Endothelial Growth Factor Deletion Induces Muscle Capillary Rarefaction Creating Muscle Insulin Resistance

PubMed Central

Bonner, Jeffrey S.; Lantier, Louise; Hasenour, Clinton M.; James, Freyja D.; Bracy, Deanna P.; Wasserman, David H.

2013-01-01

Muscle insulin resistance is associated with a reduction in vascular endothelial growth factor (VEGF) action and muscle capillary density. We tested the hypothesis that muscle capillary rarefaction critically contributes to the etiology of muscle insulin resistance in chow-fed mice with skeletal and cardiac muscle VEGF deletion (mVEGF−/−) and wild-type littermates (mVEGF+/+) on a C57BL/6 background. The mVEGF−/− mice had an ∼60% and ∼50% decrease in capillaries in skeletal and cardiac muscle, respectively. The mVEGF−/− mice had augmented fasting glucose turnover. Insulin-stimulated whole-body glucose disappearance was blunted in mVEGF−/− mice. The reduced peripheral glucose utilization during insulin stimulation was due to diminished in vivo cardiac and skeletal muscle insulin action and signaling. The decreased insulin-stimulated muscle glucose uptake was independent of defects in insulin action at the myocyte, suggesting that the impairment in insulin-stimulated muscle glucose uptake was due to poor muscle perfusion. The deletion of VEGF in cardiac muscle did not affect cardiac output. These studies emphasize the importance for novel therapeutic approaches that target the vasculature in the treatment of insulin-resistant muscle. PMID:23002035

Simulations of hypersonic, high-enthalpy separated flow over a 'tick' configuration

NASA Astrophysics Data System (ADS)

Moss, J. N.; O'Byrne, S.; Deepak, N. R.; Gai, S. L.

2012-11-01

The effect of slip is investigated in direct simulation Monte Carlo and Navier-Stokes-based computations of the separated flow between an expansion and a following compression surface, a geometry we call the 'tick' configuration. This configuration has been chosen as a test of separated flow with zero initial boundary layer thickness, a flowfield well suited to Chapman's analytical separated flow theories. The predicted size of the separated region is different for the two codes, although both codes meet their respective particle or grid resolution requirements. Unlike previous comparisons involving cylinder flares or double cones, the separation does not occur in a region of elevated density, and is therefore well suited to the direct simulation Monte Carlo method because the effect of slip at the surface is significant. The reasons for the difference between the two calculations are hypothesized to be a combination of significant rarefaction effects near the expansion surface and the non-zero radius of the leading edge. When the leading edge radius is accounted for, the rarefaction effect at the leading edge is less significant and the behavior of the flowfields predicted by the two methods becomes more similar.

Wave Refraction During the May 2002 Rarefaction Event

NASA Astrophysics Data System (ADS)

Smith, C. W.; Mullan, D. J.; Ness, N. F.; Skoug, R. M.

2002-12-01

In previous work [Smith et al., 2001] we examined IMF wave refraction during the May 1999 rarefaction interval known as ``The Day The Solar Wind Disappeared.'' On that day, Alfvén speeds remained elevated over an extended region. Analysis of the recorded ACE fields and plasma data revealed depressed magnetic fluctuation levels, reduced compression in the fluctuations, and a reduced wave-like component within the region of elevated Alfvén speed, all consistent with wave refraction. The May 2002 event provides a third such period (the second identified event occured 2 weeks prior to the May 1999 period) and it again demonstrates properties which are consistent with refraction. Smith, C.~W., D.~J. Mullan, N.~F. Ness, R.~M. Skoug, and J.~Steinberg, Day the solar wind almost disappeared: Magnetic field fluctuations, wave refraction and dissipation, J. Geophys. Res., A106, 18,625--18,634, 2001. Efforts at the Bartol Research Institute were supported by CIT subcontract PC251439 under NASA grant NAG5-6912 for support of the ACE magnetic field experiment and by the NASA Delaware Space College Grant. Work at Los Alamos was performed under the auspices of the U.S. Department of Energy with financial support from the NASA ACE program.

Infrasonic waves from volcanic eruptions on the Kamchatka peninsula

NASA Astrophysics Data System (ADS)

Gordeev, E. I.; Firstov, P. P.; Kulichkov, S. N.; Makhmudov, E. R.

2013-07-01

The IS44 station operates at the observation point of Nachiki on the Kamchatka peninsula, which is part of the International Monitoring System (IMS), and it helps verify compliance with the Comprehensive Nuclear Test-Ban Treaty (CTBT). The Kamchatka Branch, Geophysical Service, Russian Academy of Sciences (KB GS RAS), has a station operating in the village of Paratunka. Both of these stations allow one to monitor strong explosive eruptions of andesitic volcanoes.1 Both kinematic and dynamic parameters of acoustic signals accompanying the eruptions of the Bezymyannyi volcano (at a distance of 361 km from Nachiki) in 2009-2010 and the Kizimen volcano (at a distance of 275 km) on December 31, 2011, are considered. A low-frequency rarefaction phase 60 s in length has been revealed in the initial portion of the record of acoustic signals accompanying such strong eruptions. It is shown that the rarefaction phase occurs due to the rapid condensation of superheated juvenile vapor2 that enters the atmosphere during such explosions.3 The amount of volcanic ash emitted into the atmosphere has been estimated within (3.2-7.3) 106 m3 on the basis of acoustic signals recorded during the eruptions under consideration.

The Riemann problem for the relativistic full Euler system with generalized Chaplygin proper energy density-pressure relation

NASA Astrophysics Data System (ADS)

Shao, Zhiqiang

2018-04-01

The relativistic full Euler system with generalized Chaplygin proper energy density-pressure relation is studied. The Riemann problem is solved constructively. The delta shock wave arises in the Riemann solutions, provided that the initial data satisfy some certain conditions, although the system is strictly hyperbolic and the first and third characteristic fields are genuinely nonlinear, while the second one is linearly degenerate. There are five kinds of Riemann solutions, in which four only consist of a shock wave and a centered rarefaction wave or two shock waves or two centered rarefaction waves, and a contact discontinuity between the constant states (precisely speaking, the solutions consist in general of three waves), and the other involves delta shocks on which both the rest mass density and the proper energy density simultaneously contain the Dirac delta function. It is quite different from the previous ones on which only one state variable contains the Dirac delta function. The formation mechanism, generalized Rankine-Hugoniot relation and entropy condition are clarified for this type of delta shock wave. Under the generalized Rankine-Hugoniot relation and entropy condition, we establish the existence and uniqueness of solutions involving delta shocks for the Riemann problem.

In vivo reflectance-mode confocal microscopy assessments: impact of overweight on human skin microcirculation and histomorphology

NASA Astrophysics Data System (ADS)

Altintas, Ahmet A.; Aust, Matthias C.; Krämer, Robert; Vogt, Peter M.; Altintas, Mehmet A.

2016-03-01

Reflectance-mode confocal microscopy (RCM) enables in vivo assessment of the human skin. Impact of overweight on both human skin microcirculation and histomorphology has not been investigated in vivo. The purpose of this study is to evaluate both microcirculation and histomorphology in vivo in overweight. In 10 normotensive overweight nondiabetic individuals (OW-group, BMI 29.1±2.7 kg/m2) and 10 age- and sex-matched healthy lean controls (CO-group, BMI 20.4±1.9 kg/m2) the following parameters were evaluated using RCM: dermal blood cell flow (DBCF), density of dermal capillaries (DDC), epidermal thickness (ET), and epidermal cell size (ECS). DBCF was counted at 63.11±4.14 cells/min in OW-group and at 51.06±3.84 cells/min in CO-group (P<0.05). DDC was reduced in OW-group (4.91±0.39 capillaries/mm2) compared to the controls (6.02±0.64 capillaries/mm2, P<0.05). Histometric evaluation of ET reveals thickening in OW-group compared to the CO-group (54.79±4.25 μm versus 44.03±3.11 μm, P<0.05). ECS differed significantly (P<0.05) in OW-group (821.3±42.02 μm2) compared to the controls (772.6±34.79 μm2). Inverse correlation of dermal capillary density and overweight point to reduced total tissue perfusion while positive related blood cell flow reveals vasodilatation. Increase of both ET and cell size indicates remodeling of cutaneous histomorphology, maybe as an early stage of adiposity-related skin condition.

The effects of intra-aortic balloon pump support on macrocirculation and tissue microcirculation in patients with cardiogenic shock.

PubMed

den Uil, Corstiaan A; Lagrand, Wim K; van der Ent, Martin; Jewbali, Lucia S D; Brugts, Jasper J; Spronk, Peter E; Simoons, Maarten L

2009-01-01

It was the aim of this study to evaluate the effects of intra-aortic balloon pump (IABP) counterpulsation on sublingual microcirculation as a model for tissue perfusion. In 13 patients with cardiogenic shock treated with IABP, the IABP assist ratio was reduced from 1:1 to 1:8 for 15 min. Using sidestream dark field imaging, 117 movie files of the sublingual microcirculation were obtained and quantified at different IABP assist ratios at 3 time points: 1:1 (T0), 1:8 (T1) and 1:1 (T2), respectively. Data are presented as the median and interquartile range. The median age of the patients was 59 years (range 56-73), and 62% were males. Discontinuation of IABP decreased the mean arterial pressure [75 mm Hg (71-84) at T0 vs. 69 mm Hg (64-79) at T1; p < 0.001], cardiac index [2.9 l/min/m2 (1.6-3.3) at T0 vs. 2.4 l/min/m2 (1.5-2.8) at T1; p = 0.005] and cardiac power index [0.46 W/m2 (0.29-0.59) at T0 vs. 0.36 W/m2 (0.24-0.50) at T1; p = 0.006]. However, these modest changes in macrohemodynamics did not significantly influence sublingual perfused capillary density and capillary red blood cell velocity (p = 0.28 and 0.73, respectively). A temporary, modest decrease in microcirculatory driving force, induced by lowering the IABP assist ratio, does not impair sublingual microcirculatory perfusion as measured by a novel 2-dimensional imaging technique. Copyright 2009 S. Karger AG, Basel.

High-resolution label-free vascular imaging using a commercial, clinically approved dermatological OCT scanner

NASA Astrophysics Data System (ADS)

Byers, R. A.; Tozer, G.; Brown, N. J.; Matcher, S. J.

2016-02-01

Background and Aim: Recently developed decorrelative techniques such as speckle-variance optical coherence tomography (svOCT) have demonstrated non-invasive depth-resolved imaging of the microcirculation in-vivo. However, bulk tissue motion (BTM) originating from the subject's breathing or heartbeat remains problematic at low imaging speeds, often resulting in full frame decorrelation and a loss of vascular contrast. The aim of this study was to build upon existing svOCT techniques through utilisation of a commercially available, probe-based VivoSight OCT system running at 20 kHz Axial-scan rate. Methods and results: Custom four-dimensional scanning strategies were developed and utilised in order to maximise the interframe correlation during image acquisition. Volumes of structural OCT data were collected from various anatomical regions and processed using the aforementioned svOCT algorithm to reveal angiographic information. Following data collection, three dimensional image registration and novel filtering algorithms were applied to each volume in order to ensure that BTM artefacts were sufficiently suppressed. This enabled accurate visualisation of the microcirculation within the papillary dermis, to a depth of approximately 2mm. Applications of this technique, including quantitative capillary loop density measurement and visualisation of wound healing are demonstrated and enhanced through widefield mosaicing of the svOCT data. Conclusions: Non-invasive microcirculation imaging using an FDA 510(k) approved OCT scanner such as the VivoSight allows direct clinical utilisation of these techniques, in particular for the pathological analysis of skin diseases. This research was supported by BBSRC Doctoral Training Grant: BB/F016840/1. The authors also gratefully acknowledge the use of equipment funded by MRC grant: MR/L012669/1.

Collagen-induced arthritis increases inducible nitric oxide synthase not only in aorta but also in the cardiac and renal microcirculation of mice.

PubMed

Palma Zochio Tozzato, G; Taipeiro, E F; Spadella, M A; Marabini Filho, P; de Assis, M R; Carlos, C P; Girol, A P; Chies, A B

2016-03-01

Rheumatoid arthritis (RA) may promote endothelial dysfunction. This phenomenon requires further investigation, especially in collagen-induced arthritis (CIA), as it is considered the experimental model most similar to RA. The objectives of this study were to identify CIA-induced changes in noradrenaline (NE) and acetylcholine (ACh) responses in mice aortas that may suggest endothelial dysfunction in these animals. Moreover, we characterize CIA-induced modifications in inducible nitric oxide synthase (iNOS) expression in the aortas and cardiac and renal tissues taken from these mice that may be related to possible endothelial dysfunction. Male DBA/1J mice were immunized with 100 μg of emulsified bovine collagen type II (CII) plus complete Freund's adjuvant. Twenty-one days later, these animals received a boost of an additional 100 μg plus incomplete Freund's adjuvant. Fifteen days after the onset of the disease, aortic rings from CIA and control mice were challenged with NE and ACh in an organ bath. In these animals, iNOS was detected through immunohistochemical analysis of aorta, heart and kidneys. Plasma nitrite concentration was determined using the Griess reaction. CIA did not change NE or ACh responses in mice aorta but apparently increased the iNOS expression not only in aorta, but also in cardiac and renal microcirculation. In parallel, CIA reduced nitrite plasma concentration. In mice, CIA appears to increase the presence of iNOS in aorta, as well as in heart and in kidney microcirculation. This iNOS increase occurs apparently in parallel to a reduction of the bioavailability of NO. This phenomenon does not appear to change NE or ACh responses in aorta. © 2015 British Society for Immunology, Clinical and Experimental Immunology.

Quantitative analysis of nailfold capillary morphology in patients with fibromyalgia

PubMed Central

Choi, Dug-Hyun

2015-01-01

Background/Aims Nailfold capillaroscopy (NFC) has been used to examine morphological and functional microcirculation changes in connective tissue diseases. It has been demonstrated that NFC patterns reflect abnormal microvascular dynamics, which may play a role in fibromyalgia (FM) syndrome. The aim of this study was to determine NFC patterns in FM, and their association with clinical features of FM. Methods A total of 67 patients with FM, and 30 age- and sex-matched healthy controls, were included. Nailfold capillary patterns were quantitatively analyzed using computerized NFC. The parameters of interest were as follows: number of capillaries within the central 3 mm, deletion score, apical limb width, capillary width, and capillary dimension. Capillary dimension was determined by calculating the number of capillaries using the Adobe Photoshop version 7.0. Results FM patients had a lower number of capillaries and higher deletion scores on NFC compared to healthy controls (17.3 ± 1.7 vs. 21.8 ± 2.9, p < 0.05; 2.2 ± 0.9 vs. 0.7 ± 0.6, p < 0.05, respectively). Both apical limb width (µm) and capillary width (µm) were significantly decreased in FM patients (1.1 ± 0.2 vs. 3.7 ± 0.6; 5.4 ± 0.5 vs. 7.5 ± 1.4, respectively), indicating that FM patients have abnormally decreased digital capillary diameter and density. Interestingly, there was no difference in capillary dimension between the two groups, suggesting that the length or tortuosity of capillaries in FM patients is increased to compensate for diminished microcirculation. Conclusions FM patients had altered capillary density and diameter in the digits. Diminished microcirculation on NFC may alter capillary density and increase tortuosity. PMID:26161020

Melatonin protects cardiac microvasculature against ischemia/reperfusion injury via suppression of mitochondrial fission-VDAC1-HK2-mPTP-mitophagy axis.

PubMed

Zhou, Hao; Zhang, Ying; Hu, Shunying; Shi, Chen; Zhu, Pingjun; Ma, Qiang; Jin, Qinhua; Cao, Feng; Tian, Feng; Chen, Yundai

2017-08-01

The cardiac microvascular system, which is primarily composed of monolayer endothelial cells, is the site of blood supply and nutrient exchange to cardiomyocytes. However, microvascular ischemia/reperfusion injury (IRI) following percutaneous coronary intervention is a woefully neglected topic, and few strategies are available to reverse such pathologies. Here, we studied the effects of melatonin on microcirculation IRI and elucidated the underlying mechanism. Melatonin markedly reduced infarcted area, improved cardiac function, restored blood flow, and lower microcirculation perfusion defects. Histological analysis showed that cardiac microcirculation endothelial cells (CMEC) in melatonin-treated mice had an unbroken endothelial barrier, increased endothelial nitric oxide synthase expression, unobstructed lumen, reduced inflammatory cell infiltration, and less endothelial damage. In contrast, AMP-activated protein kinase α (AMPKα) deficiency abolished the beneficial effects of melatonin on microvasculature. In vitro, IRI activated dynamin-related protein 1 (Drp1)-dependent mitochondrial fission, which subsequently induced voltage-dependent anion channel 1 (VDAC1) oligomerization, hexokinase 2 (HK2) liberation, mitochondrial permeability transition pore (mPTP) opening, PINK1/Parkin upregulation, and ultimately mitophagy-mediated CMEC death. However, melatonin strengthened CMEC survival via activation of AMPKα, followed by p-Drp1 S616 downregulation and p-Drp1 S37 upregulation, which blunted Drp1-dependent mitochondrial fission. Suppression of mitochondrial fission by melatonin recovered VDAC1-HK2 interaction that prevented mPTP opening and PINK1/Parkin activation, eventually blocking mitophagy-mediated cellular death. In summary, this study confirmed that melatonin protects cardiac microvasculature against IRI. The underlying mechanism may be attributed to the inhibitory effects of melatonin on mitochondrial fission-VDAC1-HK2-mPTP-mitophagy axis via activation of AMPKα. © 2017 The Authors. Journal of Pineal Research Published by John Wiley & Sons Ltd.

Effects of cadmium on the renal and skeletal muscle microcirculation in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Chong.

1990-01-01

The effects of cadmium on the arteriolar diameters of the kidney and skeletal muscle were quantified, because of the hypertensive effect of cacmium. The effect of cacmium on the constrictor response of the renal arterioles to angiotensin II (Ang II) were also assessed. In vivo preparations of the rat hydronephrotic kidney and cremaster muscle were used for direct visualization of the microvessels with intravital television microscopy. Hydronephrosis was induced in twenty-seven male Wistar-Kyoto rats (150-180 g) by unilateral ureter ligation. The hydronephrotic kidney, with intact cortical circulation and innervation, was exteriorized in a specially designed bath for microcirculation observation 6-8more » weeks following the ureter ligation. The cremaster muscle experiments were conducted in another thirty-seven male WKY rats (120-180 g). Disparate effects of cadmium were observed in these two microcirculation beds. Topical cadmium (1.35 [mu]M-0.45 mM) increased the diameters of the pre- and postglomerular vessels in the hydronephrotic kidney maximally by 15-26%. Cadmium (0.27 mM) inhibited the Ang II response of the arterioles non-competitively. However, intraperitoneally injected cadmium (2 mg/kg), which significantly increased the mean arterial pressure, did not dilate the arterioles nor alter the Ang II response. On the other hand, cadmium (13.5 [mu]M-0.72 mM) constricted the larger arterioles in the cremaster muscle (60-160 [mu]m) concentration-dependently, but not small arterioles (15-30 [mu]m). In summary, topical cadmium dilates renal arterioles and decreases their reactivity to Ang II, but constricts the larger cremaster arterioles. The disparate effects of cadmium suggest different Ca[sup 2+] utilization mechanisms in different vascular beds. The construction of the cremaster arterioles may contribute to cadmium-induced hypertension by increasing peripheral resistance.« less

The Effect of Polyhexanide, Octenidine Dihydrochloride, and Tea Tree Oil as Topical Antiseptic Agents on In Vivo Microcirculation of the Human Skin: A Noninvasive Quantitative Analysis.

PubMed

Rothenberger, Jens; Krauss, Sabrina; Tschumi, Christian; Rahmanian-Schwarz, Afshin; Schaller, Hans-Eberhard; Held, Manuel

2016-10-01

Antiseptics are indispensable for wound management and should focus not only on the efficacy in reducing the bacterial burden but also on how much they interfere in wound healing. In this study, the authors analyzed the direct effect of topical antiseptic agents on the microcirculation of intact human skin. The perfusion dynamics were assessed before, and 10 minutes after, the volunteers' fingers of the right hand (n = 20) were immersed in the following solutions - octenidine dihydrochloride, polyhexanide, tea tree oil, and saline solution. The authors used the Oxygen to See (LEA Medizintechnik GmbH, Giessen, Germany) diagnostic device for noninvasive determination of oxygen supply in microcirculation of blood perfused tissues, which combines a laser light to determine blood flow, as well as white light to determine hemoglobin oxygenation and the relative amount of hemoglobin. Tea tree oil (÷19.0%) (B. Braun Melsungen AG, Melsungen, Germany) and polyhexanide (÷12.4%) (Lavanid, Serag Wiessner GmbH, Naila, Germany) caused a significant increase in blood flow compared to the negative control (-25.6%). Octenidine (Octenisept, Schülke & Mayr GmbH, Norderstedt, Germany) showed a nonsignificant trend towards an increase in blood flow (÷7.2%). There were alterations in the values of hemoglobin oxygenation and the relative amount of hemoglobin, but these were not significant. Perfusion is an important factor for wound healing. Therefore, it might be advantageous if antiseptic agents would increase blood flow. Tea tree oil and polyhexanide have a positive effect on skin blood flow and can therefore be used especially in critically perfused wounds, provided the adverse reactions and the antimicrobial efficacy are comparable.

Pretreatment with endothelium-derived nitric oxide synthesis modulators on gastrointestinal microcirculation during NOTES: an experimental study.

PubMed

Taurà, Pilar; Ibarzabal, Aitnitze; Vendrell, Marina; Adelsdorfer, Cedric; Delitala, Alberto; de Lacy, Borja; Deulofeu, Ramon; Delgado, Salvadora; Lacy, Antonio M

2016-12-01

On-demand endoscopic insufflation during natural orifice transluminal endoscopic surgery (NOTES) adversely affects microcirculatory blood flow (MBF), even with low mean intra-abdominal pressure, suggesting that shear stress caused by time-varying flow fluctuations has a great impact on microcirculation. As shear stress is inversely related to vascular diameter, nitric oxide (NO) production acts as a brake to vasoconstriction. To assess whether pretreatment by NO synthesis modulators protects gastrointestinal MBF during transgastric peritoneoscopy. Fourteen pigs submitted to cholecystectomy by endoscope CO 2 insufflation for 60 min were randomized into 2 groups: (1) 150 mg/kg of N-acetyl cysteine (NAC, n = 7) and (2) 4 ml/kg of hypertonic saline 7.5 % (HS, n = 7), and compared to a non-treated NOTES group (n = 7). Five animals made up a sham group. Colored microspheres were used to assess changes in MBF. The average level of intra-abdominal pressure was similar in all groups (9 mmHg). In NOTES group microcirculation decrease compared with baseline was greater in renal cortex, mesocolon, and mesentery (41, 42, 44 %, respectively, p < 0.01) than in renal medulla, colon, and small bowel (29, 32, 34, respectively, p < 0.05). NAC avoided the peritoneoscopy effect on renal medulla and cortex (4 and 14 % decrease, respectively) and reduced the impact on colon and small bowel (20 % decrease). HS eliminated MBF changes in colon and small bowel (14 % decrease) and modulated MBF in renal medulla and cortex (19 % decrease). Neither treatment influenced mesentery MBF decrease. Both pretreatments can effectively attenuate peritoneoscopy-induced deleterious effects on gastrointestinal MBF.

Protection of cerebral microcirculation, mitochondrial function, and electrocortical activity by small-volume resuscitation with terlipressin in a rat model of haemorrhagic shock.

PubMed

Ida, K K; Chisholm, K I; Malbouisson, L M S; Papkovsky, D B; Dyson, A; Singer, M; Duchen, M R; Smith, K J

2018-06-01

During early treatment of haemorrhagic shock, cerebral perfusion pressure can be restored by small-volume resuscitation with vasopressors. Whether this therapy is improved with additional fluid remains unknown. We assessed the value of terlipressin and lactated Ringer's solution (LR) on early recovery of microcirculation, tissue oxygenation, and mitochondrial and electrophysiological function in the rat cerebral cortex. Animals treated with LR replacing three times (3LR) the volume bled (n=26), terlipressin (n=27), terlipressin plus 1LR (n=26), 2LR (n=16), or 3LR (n=15) were compared with untreated (n=36) and sham-operated rats (n=17). In vivo confocal microscopy was used to assess cortical capillary perfusion, changes in tissue oxygen concentration, and mitochondrial membrane potential and redox state. Electrophysiological function was assessed by cortical somatosensory evoked potentials, spinal cord dorsum potential, and peripheral electromyography. Compared with sham treatment, haemorrhagic shock reduced the mean (SD) area of perfused vessels [82% (sd 10%) vs 38% (12%); P<0.001] and impaired oxygen concentration, mitochondrial redox state [99% (4%) vs 59% (15%) of baseline; P<0.001], and somatosensory evoked potentials [97% (13%) vs 27% (19%) of baseline]. Administration of terlipressin plus 1LR or 2LR was able to recover these measures, but terlipressin plus 3LR or 3LR alone were not as effective. Spinal cord dorsum potential was preserved in all groups, but no therapy protected electromyographic function. Resuscitation from haemorrhagic shock using terlipressin with small-volume LR was superior to high-volume LR, with regard to cerebral microcirculation, and mitochondrial and electrophysiological functions. Copyright © 2018 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.

Inflamed phenotype of the mesenteric microcirculation of melanocortin type 3 receptor-null mice after ischemia-reperfusion

PubMed Central

Leoni, Giovanna; Patel, Hetal B.; Sampaio, André L. F.; Gavins, Felicity N. E.; Murray, Joanne F.; Grieco, Paolo; Getting, Stephen J.; Perretti, Mauro

2008-01-01

The existence of anti-inflammatory circuits centered on melanocortin receptors (MCRs) has been supported by the inhibitory properties displayed by melanocortin peptides in models of inflammation and tissue injury. Here we addressed the pathophysiological effect that one MCR, MCR type 3 (MC3R), might have on vascular inflammation. After occlusion (35 min) and reopening of the superior mesenteric artery, MC3R-null mice displayed a higher degree of plasma extravasation (45 min postreperfusion) and cell adhesion and emigration (90 min postreperfusion). These cellular alterations were complemented by higher expression of mesenteric tissue CCL2 and CXCL1 (mRNA and protein) and myeloperoxydase, as compared with wild-type animals. MC1R and MC3R mRNA and protein were both expressed in the inflamed mesenteric tissue; however, no changes in vascular responses were observed in a mouse colony bearing an inactive MC1R. Pharmacological treatment of animals with a selective MC3R agonist ([d-Trp8]-γ-melanocyte-stimulating hormone; 10 μg i.v.) produced marked attenuation of cell adhesion, emigration, and chemokine generation; such effects were absent in MC3R-null mice. These new data reveal the existence of a tonic inhibitory signal provided by MC3R in the mesenteric microcirculation of the mouse, acting to down-regulate cell trafficking and local mediator generation.—Leoni, G., Patel, H. B., Sampaio, A. L. F., Gavins, F. N. E., Murray, J. F., Grieco, P., Getting, S. J., Perretti, M. Inflamed phenotype of the mesenteric microcirculation of melanocortin type 3 receptor-null mice after ischemia-reperfusion. PMID:18757499

Use of intravoxel incoherent motion diffusion-weighted imaging in identifying the vascular and avascular zones of human meniscus.

PubMed

Guo, Tan; Chen, Juan; Wu, Bing; Zheng, Dandan; Jiao, Sheng; Song, Yan; Chen, Min

2017-04-01

To investigate the hypothesis that the intravoxel incoherent motion (IVIM) diffusion-weighted imaging may depict microcirculation of meniscus and the perfusion changes in meniscal disorder. Fifty patients received diffusion-weighted MRI with multiple b-values ranging from 0 to 400 s/mm 2 . The four horns of the menisci were divided into normal, degenerated, and torn groups. IVIM parameters including perfusion fraction (f), pseudo-diffusion coefficient (D*), true diffusion coefficient (D), and the product of f and D* (f D*) of normal meniscal red zone and white zone were derived and compared for microcirculation changes of normal, degenerated, and torn posterior horn of the medial meniscus (PMM). The parameters between red and white zones among the groups were compared. Significant differences were considered when P < 0.05. Mean f and fD* were significantly higher in the red zone than those in the white zone for the normal four meniscal horns (P < 0.05), whereas D* (P = 0.882, 0.011, 0.593, and 0.33) and D (P = 0.186, 0.099, 0.767, and 0.041) did not significantly differ between the two zones. Among the normal, degenerated, and torn PMM, f was observed to be lower in the red zone of torn horns as compared to the normal horns (P = 0.013). D*, fD*, and D did not exhibit statistically significant difference among different groups (P = 0.353, 0.661, and 0.327, respectively). This hypothesis driven work shows that IVIM imaging is able to depict microcirculation of meniscus and the perfusion changes in meniscal disorder. 3 J. Magn. Reson. Imaging 2017;45:1090-1096. © 2016 International Society for Magnetic Resonance in Medicine.

Healing process of venous ulcers: the role of microcirculation.

PubMed

Ambrózy, Ewald; Waczulíková, Iveta; Willfort, Andrea; Böhler, Kornelia; Cauza, Karla; Ehringer, Herbert; Heinz, Gottfried; Koppensteiner, Renate; Marić, Snezana; Gschwandtner, Michael E

2013-02-01

In order to describe adequately the process of healing in the intermediate degrees, we investigated microcirculatory changes in the venous ulcers at well-defined stages of wound repair. We investigated dynamic changes in microcirculation during the healing process of venous ulcers. Ten venous ulcers were investigated in three consecutive clinical stages of wound healing: non granulation tissue (NGTA), GTA and scar. Subpapillary microcirculation was measured by laser Doppler perfusion (LDP) imaging and expressed using LDP values in arbitrary units. Nutritive perfusion by capillary microscopy and expressed as capillary density (CD) - the number of capillaries per square millimetre. Before the development of GTA the LDP was low (median 1·35; lower-upper quartiles 0·71-1·83) accompanied with zero CD in all but one patient who had a density of 1. With the first appearance of GTA in the same area, the LDP was improved (2·22; 1·12-2·33; P = 0·0024) when compared with NGTA, in combination with a significant increase in CD (1·75; 0-3; P = 0·0054). In scar, the LDP was similar to that in the NGTA (1·03; 0·77-1·83; P = 0·278), combined with the highest CD (5·75; 4·5-8) in comparison with the previous stages of the area (for both pairs, P < 0·0001). Venous ulcers are caused by poor nutritive and subpapillary perfusion. Subpapillary perfusion plays a major role in the formation of GTA. In a scar, the increased nutritive perfusion is sufficient to cover the blood supply and keep skin viable while subpapillary perfusion is low. © 2012 The Authors. International Wound Journal © 2012 Blackwell Publishing Ltd and Medicalhelplines.com Inc.

Propionyl-L-carnitine improves endothelial function, microcirculation and pain management in critical limb ischemia.

PubMed

De Marchi, S; Zecchetto, S; Rigoni, A; Prior, M; Fondrieschi, L; Scuro, A; Rulfo, F; Arosio, E

2012-10-01

Chronic critical limb ischemia (CLI) is a severe condition of hypo-perfusion of lower limbs, which is associated with inflammation and a pro-coagulative state. It is a disease at high risk of amputation and cardiovascular death. Propionyl-L-carnitine (PLC) is efficacious in improving pain free walking distance in peripheral arterial disease with claudication; it also exerts favorable effects on the arterial wall and on endothelial function. The purpose of this study was to evaluate the effects of PLC on microcirculation, endothelial function and pain relief in patients affected by CLI not suitable for surgical intervention. We enrolled 48 patients with CLI. Patients were randomized into two groups: the first group was treated with PLC, the second was treated with saline solution. All of them underwent the following tests: laser Doppler flowmetry at the forefoot at rest and after ischemia, trans cutaneous oxygen partial pressure and carbon dioxide partial pressure at the forefoot at rest and after ischemia, endothelium dependent dilation of the brachial artery. All tests were repeated after treatments. Pain was assessed by visual analog pain scale. Endothelium dependent dilation increased after PLC (9.5 ± 3.2 vs 4.9 ± 1.4 %; p < 0.05). Post-ischemic peak flow with laser-Doppler flow increased after PLC. TcPO2 increased, while TcPCO2 decreased after PLC; CO2 production decreased after PLC. VAS showed a significant reduction in pain perception after active treatment. In CLI patients, PLC can improve microcirculation (post ischemic hyperemia, TcPO2 and TcPCO2 production). PLC also enhances endothelium dependent dilation and reduces analgesic consumption and pain perception.

How to evaluate the microcirculation: report of a round table conference

PubMed Central

De Backer, Daniel; Hollenberg, Steven; Boerma, Christiaan; Goedhart, Peter; Büchele, Gustavo; Ospina-Tascon, Gustavo; Dobbe, Iwan; Ince, Can

2007-01-01

Introduction Microvascular alterations may play an important role in the development of organ failure in critically ill patients and especially in sepsis. Recent advances in technology have allowed visualization of the microcirculation, but several scoring systems have been used so it is sometimes difficult to compare studies. This paper reports the results of a round table conference that was organized in Amsterdam in November 2006 in order to achieve consensus on image acquisition and analysis. Methods The participants convened to discuss the various aspects of image acquisition and the different scores, and a consensus statement was drafted using the Delphi methodology. Results The participants identified the following five key points for optimal image acquisition: five sites per organ, avoidance of pressure artifacts, elimination of secretions, adequate focus and contrast adjustment, and recording quality. The scores that can be used to describe numerically the microcirculatory images consist of the following: a measure of vessel density (total and perfused vessel density; two indices of perfusion of the vessels (proportion of perfused vessels and microcirculatory flow index); and a heterogeneity index. In addition, this information should be provided for all vessels and for small vessels (mostly capillaries) identified as smaller than 20 μm. Venular perfusion should be reported as a quality control index, because venules should always be perfused in the absence of pressure artifact. It is anticipated that although this information is currently obtained manually, it is likely that image analysis software will ease analysis in the future. Conclusion We proposed that scoring of the microcirculation should include an index of vascular density, assessment of capillary perfusion and a heterogeneity index. PMID:17845716

Functional and morphological evaluation of hand microcirculation with nailfold capillaroscopy and laser Doppler imaging in Raynaud's and Sjögren's syndrome and poly/dermatomyositis.

PubMed

Szabo, N; Csiki, Z; Szanto, A; Danko, K; Szodoray, P; Zeher, M

2008-01-01

Nailfold capillaroscopy is widely used in autoimmune patients to determine capillary morphology. Laser Doppler imaging (LDI) is a relatively new method for measuring the microcirculation of cutaneous perfusion. The aim of this study was to investigate the capillary morphology and microcirculation among patients with Sjögren's syndrome (SS) and poly/dermatomyositis (PM/DM) with these two non-invasive methods and to detect secondary Raynaud's syndrome (SRS) in these autoimmune diseases. Thirty patients with primary SS, 30 patients with PM/DM, 30 patients with primary Raynaud's syndrome (PRS), and 30 healthy volunteers were included in the study. Nailfold capillaroscopy and LDI were performed on each patient. A comprehensive analysis was performed among the patients and healthy individuals. Among SS patients avascularity and among PM/DM patients avascularity and capillary morphology changes were most often detected by capillaroscopy. With LDI the mean steady-state cutaneous perfusion was 1.25 perfusion units (PU) in region of interest 1 (ROI1), 1.22 in ROI2, and 1.49 at the fingertips in PRS patients; the corresponding values were 1.2, 1.03, and 1.48 PU in SS, 0.91, 0.76, and 1.19 PU in PM/DM, and 1.79, 1.62, and 2.2 PU in the controls. The differences were significant between each autoimmune group compared to the control group (p<0.02, p<0.001, and p<0.001, respectively). By using nailfold capillaroscopy, abnormalities in capillary morphology can be detected, and by using LDI, the reduced blood flow in the capillaries can be detected. These investigations can be useful in the detection of SRS, or in distinguishing whether the reduced blood flow is due to primary/systemic autoimmune diseases.

Arrest of B16 Melanoma Cells in the Mouse Pulmonary Microcirculation Induces Endothelial Nitric Oxide Synthase-Dependent Nitric Oxide Release that Is Cytotoxic to the Tumor Cells

PubMed Central

Qiu, Hongming; Orr, F.William; Jensen, Derrek; Wang, Hui Helen; McIntosh, Alan R.; Hasinoff, Brian B.; Nance, Dwight M.; Pylypas, Susan; Qi, Ke; Song, Chun; Muschel, Ruth J.; Al-Mehdi, Abu-Bakr

2003-01-01

Metastatic cancer cells seed the lung via blood vessels. Because endothelial cells generate nitric oxide (NO) in response to shear stress, we postulated that the arrest of cancer cells in the pulmonary microcirculation causes the release of NO in the lung. After intravenous injection of B16F1 melanoma cells, pulmonary NO increased sevenfold throughout 20 minutes and approached basal levels by 4 hours. NO induction was blocked by NG-nitro-l-arginine methyl ester (L-NAME) and was not observed in endothelial nitric oxide synthase (eNOS)-deficient mice. NO production, visualized ex vivo with the fluorescent NO probe diaminofluorescein diacetate, increased rapidly at the site of tumor cell arrest, and continued to increase throughout 20 minutes. Arrested tumor cells underwent apoptosis with apoptotic counts more than threefold over baseline at 8 and 48 hours. Neither the NO signals nor increased apoptosis were seen in eNOS knockout mice or mice pretreated with L-NAME. At 48 hours, 83% of the arrested cells had cleared from the lungs of wild-type mice but only ∼55% of the cells cleared from eNOS-deficient or L-NAME pretreated mice. eNOS knockout and L-NAME-treated mice had twofold to fivefold more metastases than wild-type mice, measured by the number of surface nodules or by histomorphometry. We conclude that tumor cell arrest in the pulmonary microcirculation induces eNOS-dependent NO release by the endothelium adjacent to the arrested tumor cells and that NO is one factor that causes tumor cell apoptosis, clearance from the lung, and inhibition of metastasis. PMID:12547699

The Nervous System and Gastrointestinal Function

ERIC Educational Resources Information Center

Altaf, Muhammad A.; Sood, Manu R.

2008-01-01

The enteric nervous system is an integrative brain with collection of neurons in the gastrointestinal tract which is capable of functioning independently of the central nervous system (CNS). The enteric nervous system modulates motility, secretions, microcirculation, immune and inflammatory responses of the gastrointestinal tract. Dysphagia,…

77 FR 2303 - Center for Scientific Review; Notice of Closed Meetings

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-17

...: Diabetes and Obesity. Date: January 26, 2012. Time: 9:30 a.m. to 4 p.m. Agenda: To review and evaluate..., Hypertension and Microcirculation A. Date: February 7, 2012. Time: 1 p.m. to 1:45 p.m. Agenda: To review and...

Enhanced in vivo visualization of the microcirculation by topical application of fructose solution confirmed with correlation mapping optical coherence tomography

NASA Astrophysics Data System (ADS)

Enfield, Joey; McGrath, James; Daly, Susan M.; Leahy, Martin

2016-08-01

Changes within the microcirculation can provide an early indication of the onset of a plethora of ailments. Various techniques have thus been developed that enable the study of microcirculatory irregularities. Correlation mapping optical coherence tomography (cmOCT) is a recently proposed technique, which enables mapping of vasculature networks at the capillary level in a noninvasive and noncontact manner. This technique is an extension of conventional optical coherence tomography (OCT) and is therefore likewise limited in the penetration depth of ballistic photons in biological media. Optical clearing has previously been demonstrated to enhance the penetration depth and the imaging capabilities of OCT. In order to enhance the achievable maximum imaging depth, we propose the use of optical clearing in conjunction with the cmOCT technique. We demonstrate in vivo a 13% increase in OCT penetration depth by topical application of a high-concentration fructose solution, thereby enabling the visualization of vessel features at deeper depths within the tissue.

Intravital imaging of a pulmonary endothelial surface layer in a murine sepsis model.

PubMed

Park, Inwon; Choe, Kibaek; Seo, Howon; Hwang, Yoonha; Song, Eunjoo; Ahn, Jinhyo; Hwan Jo, You; Kim, Pilhan

2018-05-01

Direct intravital imaging of an endothelial surface layer (ESL) in pulmonary microcirculation could be a valuable approach to investigate the role of a vascular endothelial barrier in various pathological conditions. Despite its importance as a marker of endothelial cell damage and impairment of the vascular system, in vivo visualization of ESL has remained a challenging technical issue. In this work, we implemented a pulmonary microcirculation imaging system integrated to a custom-design video-rate laser scanning confocal microscopy platform. Using the system, a real-time cellular-level microscopic imaging of the lung was successfully performed, which facilitated a clear identification of individual flowing erythrocytes in pulmonary capillaries. Subcellular level pulmonary ESL was identified in vivo by fluorescence angiography using a dextran conjugated fluorophore to label blood plasma and the red blood cell (RBC) exclusion imaging analysis. Degradation of ESL width was directly evaluated in a murine sepsis model in vivo , suggesting an impairment of pulmonary vascular endothelium and endothelial barrier dysfunction.

Intravital imaging of a pulmonary endothelial surface layer in a murine sepsis model

PubMed Central

Park, Inwon; Choe, Kibaek; Seo, Howon; Hwang, Yoonha; Song, Eunjoo; Ahn, Jinhyo; Hwan Jo, You; Kim, Pilhan

2018-01-01

Direct intravital imaging of an endothelial surface layer (ESL) in pulmonary microcirculation could be a valuable approach to investigate the role of a vascular endothelial barrier in various pathological conditions. Despite its importance as a marker of endothelial cell damage and impairment of the vascular system, in vivo visualization of ESL has remained a challenging technical issue. In this work, we implemented a pulmonary microcirculation imaging system integrated to a custom-design video-rate laser scanning confocal microscopy platform. Using the system, a real-time cellular-level microscopic imaging of the lung was successfully performed, which facilitated a clear identification of individual flowing erythrocytes in pulmonary capillaries. Subcellular level pulmonary ESL was identified in vivo by fluorescence angiography using a dextran conjugated fluorophore to label blood plasma and the red blood cell (RBC) exclusion imaging analysis. Degradation of ESL width was directly evaluated in a murine sepsis model in vivo, suggesting an impairment of pulmonary vascular endothelium and endothelial barrier dysfunction. PMID:29760995

Fluid therapy and the hypovolemic microcirculation.

PubMed

Gruartmoner, G; Mesquida, J; Ince, Can

2015-08-01

In shock states, optimizing intravascular volume is crucial to promote an adequate oxygen delivery to the tissues. Our current practice in fluid management pivots on the Frank-Starling law of the heart, and the effects of fluids are measured according to the induced changes on stroke volume. The purpose of this review is to evaluate the boundaries of current macrohemodynamic approach to fluid administration, and to introduce the microcirculatory integration as a fundamental part of tissue perfusion monitoring. Macrocirculatory changes induced by volume expansion are not always coupled to proportional changes in microcirculatory perfusion. Loss of hemodynamic coherence limits the value of guiding fluid therapy according to macrohemodynamics, and highlights the importance of evaluating the ultimate target of volume administration, the microcirculation. Current approach to intravascular volume optimization is made from a macrohemodynamic perspective. However, several situations wherein macrocirculatory and microcirculatory coherence is lost have been described. Future clinical trials should explore the usefulness of integrating the microcirculatory evaluation in fluid optimization.

Improvement of hepatic microhemodynamics by N-acetylcysteine after warm ischemia.

PubMed

Koeppel, T A; Thies, J C; Lehmann, T; Gebhard, M M; Herfarth, C; Otto, G; Post, S

1996-01-01

In this study we investigated the influence of N-acetylcysteine (NAC) on the hepatic microcirculation after warm ischemia by intravital fluorescence microscopy. Clamping of the left liver lobe was performed in 20 male Wistar rats for 70 min. The treatment group (n = 10) received 400 mg NAC/kg body weight 20 min prior to clamping. After reperfusion, acinar and sinusoidal perfusions were observed as well as the leukocyte-endothelium interaction. Phagocytic activity was assessed after application of latex beads. NAC reduced the number of nonperfused sinusoids in all acinar zones. A reduction in zone 1 (portal) was achieved from 15.5 to 7.1% (p < 0.0001), in zone 2 (midzonal) from 14.6 to 6.1% (p < 0.0001) and in zone 3 (central) from 11.9 to 2.9% (p < 0.0001). There were no significant differences in leukocyte adherence as well as in phagocytic activity detectable. We conclude that NAC improves hepatic microcirculation after warm ischemia by increasing sinusoidal blood flow.

The capillary bed offers the largest hemodynamic resistance to the cortical blood supply

PubMed Central

Gould, Ian Gopal; Tsai, Philbert; Kleinfeld, David

2016-01-01

The cortical angioarchitecture is a key factor in controlling cerebral blood flow and oxygen metabolism. Difficulties in imaging the complex microanatomy of the cortex have so far restricted insight about blood flow distribution in the microcirculation. A new methodology combining advanced microscopy data with large scale hemodynamic simulations enabled us to quantify the effect of the angioarchitecture on the cerebral microcirculation. High-resolution images of the mouse primary somatosensory cortex were input into with a comprehensive computational model of cerebral perfusion and oxygen supply ranging from the pial vessels to individual brain cells. Simulations of blood flow, hematocrit and oxygen tension show that the wide variation of hemodynamic states in the tortuous, randomly organized capillary bed is responsible for relatively uniform cortical tissue perfusion and oxygenation. Computational analysis of microcirculatory blood flow and pressure drops further indicates that the capillary bed, including capillaries adjacent to feeding arterioles (d < 10 µm), are the largest contributors to hydraulic resistance. PMID:27780904

Real time diffuse reflectance polarisation spectroscopy imaging to evaluate skin microcirculation

NASA Astrophysics Data System (ADS)

O'Doherty, Jim; Henricson, Joakim; Nilsson, Gert E.; Anderson, Chris; Leahy, Martin J.

2007-07-01

This article describes the theoretical development and design of a real-time microcirculation imaging system, an extension from a previously technology developed by our group. The technology utilises polarisation spectroscopy, a technique used in order to selectively gate photons returning from various compartments of human skin tissue, namely from the superficial layers of the epidermis, and the deeper backscattered light from the dermal matrix. A consumer-end digital camcorder captures colour data with three individual CCDs, and a custom designed light source consisting of a 24 LED ring light provides broadband illumination over the 400 nm - 700 nm wavelength region. Theory developed leads to an image processing algorithm, the output of which scales linearly with increasing red blood cell (RBC) concentration. Processed images are displayed online in real-time at a rate of 25 frames s -1, at a frame size of 256 x 256 pixels, and is limited only by computer RAM memory and processing speed. General demonstrations of the technique in vivo display several advantages over similar technology.

In vivo correlation mapping microscopy

NASA Astrophysics Data System (ADS)

McGrath, James; Alexandrov, Sergey; Owens, Peter; Subhash, Hrebesh; Leahy, Martin

2016-04-01

To facilitate regular assessment of the microcirculation in vivo, noninvasive imaging techniques such as nailfold capillaroscopy are required in clinics. Recently, a correlation mapping technique has been applied to optical coherence tomography (OCT), which extends the capabilities of OCT to microcirculation morphology imaging. This technique, known as correlation mapping optical coherence tomography, has been shown to extract parameters, such as capillary density and vessel diameter, and key clinical markers associated with early changes in microvascular diseases. However, OCT has limited spatial resolution in both the transverse and depth directions. Here, we extend this correlation mapping technique to other microscopy modalities, including confocal microscopy, and take advantage of the higher spatial resolution offered by these modalities. The technique is achieved as a processing step on microscopy images and does not require any modification to the microscope hardware. Results are presented which show that this correlation mapping microscopy technique can extend the capabilities of conventional microscopy to enable mapping of vascular networks in vivo with high spatial resolution in both the transverse and depth directions.

[Measurement of pancreatic microcirculation using hydrogen gas generated by electrolysis in dogs].

PubMed

Nishiwaki, H; Satake, K; Ko, I; Tanaka, H; Kanazawa, G; Nagai, Y; Umeyama, K

1986-11-01

Measurements of pancreatic microflow were investigated using hydrogen gas generated by electrolysis in dog. After laparatomy under general anesthesia, uncinate process of the pancreas was punctured by a needle electrode for electrolysis and determination of hydrogen gas. The consecutive measurements of pancreatic microflow revealed the good reproducibility at the same point of the pancreas. The simultaneous measurements of pancreatic microflow by electrolysis and pancreatic tissue blood flow by H2 inhalation method were carried out at the same point of the pancreas. Correlation analysis of both measurements revealed coefficient of 0.751 and a significant relationship was observed (p less than 0.05). However, the value was a little higher in pancreatic microflow as compared with pancreatic tissue blood flow. Pancreatic microflow and pancreatic exocrine secretion increased after intravenous administration of Dopamine and Secretin (10 micrograms/kg/min). It is concluded that the measurement of pancreatic microflow by hydrogen gas generated by electrolysis is a useful method on understanding the microcirculation of the pancreas.

Airblast Simulator Studies.

DTIC Science & Technology

1984-02-01

RAREFACTION WAVE ELIMINATOR CONSIDERATIONS 110 5.1 FLIP CALCULATIONS 110 5.2 A PASSIVE/ACTIVE RWE 118 6 DISTRIBUTED FUEL AIR EXPLOSIVES 120 REFERENCES 123 TA...conventional and distributed-charge fuel- air explosive charges used in a study of the utility of distributed charge FAE systems for blast simulation. The...limited investigation of distributed charge fuel air explosive configurations for blast simulator applications. During the course of this study

Trichilemmal cyst nevus of the scalp.

PubMed

Serra, David; Pereira, Sara; Robalo-Cordeiro, Margarida; Tellechea, Oscar

2011-04-01

We report the observation of a 24-year-old woman presenting a plaque-like lesion of the occipital scalp with hair rarefaction. This lesion was congenital and consisted of numerous, agminated, very small, trichilemmal cysts. It remained stable since birth, slowly growing in proportion with the patient during childhood. We discuss the nosological status of this intriguing lesion and its relationship with the recently described trichilemmal cyst nevus.

Diabetes Mellitus-Induced Microvascular Destabilization in the Myocardium.

PubMed

Hinkel, Rabea; Howe, Andrea; Renner, Simone; Ng, Judy; Lee, Seungmin; Klett, Katharina; Kaczmarek, Veronika; Moretti, Alessandra; Laugwitz, Karl-Ludwig; Skroblin, Philipp; Mayr, Manuel; Milting, Hendrik; Dendorfer, Andreas; Reichart, Bruno; Wolf, Eckhard; Kupatt, Christian

2017-01-17

Diabetes mellitus causes microcirculatory rarefaction and may impair the responsiveness of ischemic myocardium to proangiogenic factors. This study sought to determine whether microvascular destabilization affects organ function and therapeutic neovascularization in diabetes mellitus. The authors obtained myocardial samples from patients with end-stage heart failure at time of transplant, with or without diabetes mellitus. Diabetic (db) and wild-type (wt) pigs were used to analyze myocardial vascularization and function. Chronic ischemia was induced percutaneously (day 0) in the circumflex artery. At day 28, recombinant adeno-associated virus (rAAV) (5 × 10 12 viral particles encoding vascular endothelial growth factor-A [VEGF-A] or thymosin beta 4 [Tβ4]) was applied regionally. CD31+ capillaries per high power field (c/hpf) and NG2+ pericyte coverage were analyzed. Global myocardial function (ejection fraction [EF] and left ventricular end-diastolic pressure) was assessed at days 28 and 56. Diabetic human myocardial explants revealed capillary rarefaction and pericyte loss compared to nondiabetic explants. Hyperglycemia in db pigs, even without ischemia, induced capillary rarefaction in the myocardium (163 ± 14 c/hpf in db vs. 234 ± 8 c/hpf in wt hearts; p < 0.005), concomitant with a distinct loss of EF (44.9% vs. 53.4% in nondiabetic controls; p < 0.05). Capillary density further decreased in chronic ischemic hearts, as did EF (both p < 0.05). Treatment with rAAV.Tβ4 enhanced capillary density and maturation in db hearts less efficiently than in wt hearts, similar to collateral growth. rAAV.VEGF-A, though stimulating angiogenesis, induced neither pericyte recruitment nor collateral growth. As a result, rAAV.Tβ4 but not rAAV.VEGF-A improved EF in db hearts (34.5 ± 1.4%), but less so than in wt hearts (44.8 ± 1.5%). Diabetes mellitus destabilized microvascular vessels of the heart, affecting the amplitude of therapeutic neovascularization via rAAV.Tβ4 in a translational large animal model of hibernating myocardium. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Normal velocity freeze-out of the Richtmyer-Meshkov instability when a rarefaction is reflected

NASA Astrophysics Data System (ADS)

Wouchuk, J. G.; Sano, T.

2015-02-01

The Richtmyer-Meshkov instability (RMI) develops when a shock front hits a rippled contact surface separating two different fluids. After the incident shock refraction, a transmitted shock is always formed and another shock or a rarefaction is reflected back. The pressure-entropy-vorticity fields generated by the rippled wave fronts are responsible for the generation of hydrodynamic perturbations in both fluids. In linear theory, the contact surface ripple reaches an asymptotic normal velocity which is dependent on the incident shock Mach number, fluids density ratio, and compressibilities. It was speculated in the past about the possibility of getting a zero value for the asymptotic normal velocity, a phenomenon that was called "freeze-out" [G. Fraley, Phys. Fluids 29, 376 (1986), 10.1063/1.865722; K. Mikaelian, Phys. Fluids 6, 356 (1994), 10.1063/1.868091, A. L. Velikovich et al., Phys. Plasmas 8, 592 (2001), 10.1063/1.1335829]. In a previous paper, freeze-out was studied for the case when a shock is reflected at the contact surface [J. G. Wouchuk and K. Nishihara, Phys. Rev. E 70, 026305 (2004), 10.1103/PhysRevE.70.026305]. In this work the freeze-out of the RMI is studied for the case in which a rarefaction is reflected back. Two different regimes are found: nearly equal preshock densities at the interface at any shock intensity, and very large density difference for strong shocks. The contour curves that relate shock Mach number and preshock density ratio are obtained in both regimes for fluids with equal and different compressibilities. An analysis of the temporal evolution of different cases of freeze-out is shown. It is seen that the freeze-out is the result of the interaction between the unstable interface and the rippled wave fronts. As a general and qualitative criterion to look for freeze-out situations, it is seen that a necessary condition for freeze-out is the same orientation for the tangential velocities generated at each side of the contact surface at t =0 + . A comparison with the results of previous works is also shown.

Temporal and radial variation of the solar wind temperature-speed relationship

NASA Astrophysics Data System (ADS)

Elliott, H. A.; Henney, C. J.; McComas, D. J.; Smith, C. W.; Vasquez, B. J.

2012-09-01

The solar wind temperature (T) and speed (V) are generally well correlated at ˜1 AU, except in Interplanetary Coronal Mass Ejections where this correlation breaks down. We perform a comprehensive analysis of both the temporal and radial variation in the temperature-speed (T-V) relationship of the non-transient wind, and our analysis provides insight into both the causes of the T-V relationship and the sources of the temperature variability. Often at 1 AU the speed-temperature relationship is well represented by a single linear fit over a speed range spanning both the slow and fast wind. However, at times the fast wind from coronal holes can have a different T-V relationship than the slow wind. A good example of this was in 2003 when there was a very large and long-lived outward magnetic polarity coronal hole at low latitudes that emitted wind with speeds as fast as a polar coronal hole. The long-lived nature of the hole made it possible to clearly distinguish that some holes can have a different T-V relationship. In an earlier ACE study, we found that both the compressions and rarefactions T-V curves are linear, but the compression curve is shifted to higher temperatures. By separating compressions and rarefactions prior to determining the radial profiles of the solar wind parameters, the importance of dynamic interactions on the radial evolution of the solar wind parameters is revealed. Although the T-V relationship at 1 AU is often well described by a single linear curve, we find that the T-V relationship continually evolves with distance. Beyond ˜2.5 AU the differences between the compressions and rarefactions are quite significant and affect the shape of the overall T-V distribution to the point that a simple linear fit no longer describes the distribution well. Since additional heating of the ambient solar wind outside of interaction regions can be associated with Alfvénic fluctuations and the turbulent energy cascade, we also estimate the heating rate radial profile from the solar wind speed and temperature measurements.

Non-Ideal Compressible Fluid Dynamics: A Challenge for Theory

NASA Astrophysics Data System (ADS)

Kluwick, A.

2017-03-01

The possibility that compression as well as rarefaction shocks may form in single phase vapours was envisaged first by Bethe (1942). However calculations based on the Van der Waals equation of state indicated that the latter type of shock is possible only if the specific heat at constant volume cv divided by the universal gas constant R is larger than about 17.5 which he considered too large to be satisfied by real fluids. This conclusion was contested by Thompson (1971) who showed that the type of shock capable of forming in arbitrary fluids is determined by the sign of the thermodynamic quantity to which he referred to as fundamental derivative of gas dynamics. Here v, p, s and c denote the specific volume, the pressure, the entropy and the speed of sound. Thompson and co-workers also showed that the required condition for the existence of rarefaction shocks, that Γ may take on negative values, is indeed satisfied for a number of hydrocarbon and fluorocarbon vapours. This finding spawned a burst of theoretical studies elaborating on the unusual and often counterintuitive behaviour of shocks with rarefaction shocks present. These produced both results of theoretical character but also results suggesting the practical importance of Non-Ideal Compressible Fluid Dynamics in general. The present paper addresses some of the challenges encountered in connection with the theoretical treatment of the associated flow behaviour. Weakly nonlinear acoustic waves of finite amplitude serve as a starting point. Here mixed rather than strictly positive nonlinearity generates a wealth of phenomena not possible in perfect gases. Examples of steady flows where these non-classical effects play a decisive role (and which may be useful also for future experimental work) are quasi one-dimensional nozzle flows and transonic two-dimensional flows past corners. The study of viscous effects concentrates on laminar flows of boundary layer type. Here non-classical phenomena are caused by the uncommon smallness of the Eckert number but also by the unconventional Mach number dependence on p in the external inviscid flow region.

Hydrodynamics, wall-slip, and normal-stress differences in rarefied granular Poiseuille flow

NASA Astrophysics Data System (ADS)

Gupta, Ronak; Alam, Meheboob

2017-02-01

Hydrodynamic fields, macroscopic boundary conditions, and non-Newtonian rheology of the acceleration-driven Poiseuille flow of a dilute granular gas are probed using "direct simulation Monte Carlo" method for a range of Knudsen numbers (Kn, the ratio between the mean free path and the macroscopic length), spanning the rarefied regime of slip and transitional flows. It is shown that the "dissipation-induced clustering" (for 1 -en>0 , where en is the restitution coefficient), leading to inhomogeneous density profiles along the transverse direction, competes with "rarefaction-induced declustering" (for Kn>0 ) phenomenon, leaving seemingly "anomalous" footprints on several hydrodynamic and rheological quantities; one example is the well-known rarefaction-induced temperature bimodality, which could also result from inelastic dissipation that dominates in the continuum limit (Kn→0 ) as found recently [Alam et al., J. Fluid Mech. 782, 99 (2015), 10.1017/jfm.2015.523]. The simulation data on the slip velocity and the temperature slip are contrasted with well-established boundary conditions for molecular gases. A modified Maxwell-Navier-type boundary condition is found to hold in granular Poiseuille flow, with the velocity slip length following a power-law relation with Knudsen number Knδ, with δ ≈0.95 , for Kn≤0.1 . Transverse profiles of both first [N1(y ) ] and second [N2(y ) ] normal stress differences seem to correlate well with respective density profiles at small Kn; their centerline values [N1(0 ) and N2(0 ) ] can be of "odd" sign with respect to their counterparts in molecular gases. The phase diagrams are constructed in the (Kn,1 -en ) plane that demarcates the regions of influence of inelasticity and rarefaction, which compete with each other resulting in the sign change of both N1(0 ) and N2(0 ) . The results on normal stress differences are rationalized via a comparison with a Burnett-order theory [Sela and Goldhirsch, J. Fluid Mech. 361, 41 (1998), 10.1017/S0022112098008660], which is able to predict their correct behavior at small values of the Knudsen number. Lastly, the Knudsen paradox and its dependence on inelasticity are analyzed and contrasted with related recent works.

In vivo transcranial cavitation threshold detection during ultrasound-induced blood-brain barrier opening in mice.

PubMed

Tung, Yao-Sheng; Vlachos, Fotios; Choi, James J; Deffieux, Thomas; Selert, Kirsten; Konofagou, Elisa E

2010-10-21

The in vivo cavitation response associated with blood-brain barrier (BBB) opening as induced by transcranial focused ultrasound (FUS) in conjunction with microbubbles was studied in order to better identify the underlying mechanism in its noninvasive application. A cylindrically focused hydrophone, confocal with the FUS transducer, was used as a passive cavitation detector (PCD) to identify the threshold of inertial cavitation (IC) in the presence of Definity® microbubbles (mean diameter range: 1.1-3.3 µm, Lantheus Medical Imaging, MA, USA). A vessel phantom was first used to determine the reliability of the PCD prior to in vivo use. A cerebral blood vessel was simulated by generating a cylindrical channel of 610 µm in diameter inside a polyacrylamide gel and by saturating its volume with microbubbles. The microbubbles were sonicated through an excised mouse skull. Second, the same PCD setup was employed for in vivo noninvasive (i.e. transdermal and transcranial) cavitation detection during BBB opening. After the intravenous administration of Definity® microbubbles, pulsed FUS was applied (frequency: 1.525 or 1.5 MHz, peak-rarefactional pressure: 0.15-0.60 MPa, duty cycle: 20%, PRF: 10 Hz, duration: 1 min with a 30 s interval) to the right hippocampus of twenty-six (n = 26) mice in vivo through intact scalp and skull. T1 and T2-weighted MR images were used to verify the BBB opening. A spectrogram was generated at each pressure in order to detect the IC onset and duration. The threshold of BBB opening was found to be at a 0.30 MPa peak-rarefactional pressure in vivo. Both the phantom and in vivo studies indicated that the IC pressure threshold had a peak-rarefactional amplitude of 0.45 MPa. This indicated that BBB opening may not require IC at or near the threshold. Histological analysis showed that BBB opening could be induced without any cellular damage at 0.30 and 0.45 MPa. In conclusion, the cavitation response could be detected without craniotomy in mice and IC may not be required for BBB opening at relatively low pressures.

Effects of heme oxygenase-1-modified bone marrow mesenchymal stem cells on microcirculation and energy metabolism following liver transplantation

PubMed Central

Yang, Liu; Shen, Zhong-Yang; Wang, Rao-Rao; Yin, Ming-Li; Zheng, Wei-Ping; Wu, Bin; Liu, Tao; Song, Hong-Li

2017-01-01

AIM To investigate the effects of heme oxygenase-1 (HO-1)-modified bone marrow mesenchymal stem cells (BMMSCs) on the microcirculation and energy metabolism of hepatic sinusoids following reduced-size liver transplantation (RLT) in a rat model. METHODS BMMSCs were isolated and cultured in vitro using an adherent method, and then transduced with HO-1-bearing recombinant adenovirus to construct HO-1/BMMSCs. A rat acute rejection model following 50% RLT was established using a two-cuff technique. Recipients were divided into three groups based on the treatment received: normal saline (NS), BMMSCs and HO-1/BMMSCs. Liver function was examined at six time points. The levels of endothelin-1 (ET-1), endothelial nitric-oxide synthase (eNOS), inducible nitric-oxide synthase (iNOS), nitric oxide (NO), and hyaluronic acid (HA) were detected using an enzyme-linked immunosorbent assay. The portal vein pressure (PVP) was detected by Power Lab ML880. The expressions of ET-1, iNOS, eNOS, and von Willebrand factor (vWF) protein in the transplanted liver were detected using immunohistochemistry and Western blotting. ATPase in the transplanted liver was detected by chemical colorimetry, and the ultrastructural changes were observed under a transmission electron microscope. RESULTS HO-1/BMMSCs could alleviate the pathological changes and rejection activity index of the transplanted liver, and improve the liver function of rats following 50% RLT, with statistically significant differences compared with those of the NS group and BMMSCs group (P < 0.05). In term of the microcirculation of hepatic sinusoids: The PVP on POD7 decreased significantly in the HO-1/BMMSCs and BMMSCs groups compared with that of the NS group (P < 0.01); HO-1/BMMSCs could inhibit the expressions of ET-1 and iNOS, increase the expressions of eNOS and inhibit amounts of NO production, and maintain the equilibrium of ET-1/NO (P < 0.05); and HO-1/BMMSCs increased the expression of vWF in hepatic sinusoidal endothelial cells (SECs), and promoted the degradation of HA, compared with those of the NS group and BMMSCs group (P < 0.05). In term of the energy metabolism of the transplanted liver, HO-1/BMMSCs repaired the damaged mitochondria, and improved the activity of mitochondrial aspartate aminotransferase (ASTm) and ATPase, compared with the other two groups (P <0.05). CONCLUSION HO-1/BMMSCs can improve the microcirculation of hepatic sinusoids significantly, and recover the energy metabolism of damaged hepatocytes in rats following RLT, thus protecting the transplanted liver. PMID:28596681

Functional evaluation of sublingual microcirculation indicates successful weaning from VA-ECMO in cardiogenic shock.

PubMed

Akin, Sakir; Dos Reis Miranda, Dinis; Caliskan, Kadir; Soliman, Osama I; Guven, Goksel; Struijs, Ard; van Thiel, Robert J; Jewbali, Lucia S; Lima, Alexandre; Gommers, Diederik; Zijlstra, Felix; Ince, Can

2017-10-26

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly adopted for the treatment of cardiogenic shock (CS). However, a marker of successful weaning remains largely unknown. Our hypothesis was that successful weaning is associated with sustained microcirculatory function during ECMO flow reduction. Therefore, we sought to test the usefulness of microcirculatory imaging in the same sublingual spot, using incident dark field (IDF) imaging in assessing successful weaning from VA-ECMO and compare IDF imaging with echocardiographic parameters. Weaning was performed by decreasing the VA-ECMO flow to 50% (F 50 ) from the baseline. The endpoint of the study was successful VA-ECMO explantation within 48 hours after weaning. The response of sublingual microcirculation to a weaning attempt (WA) was evaluated. Microcirculation was measured in one sublingual area (single spot (ss)) using CytoCam IDF imaging during WA. Total vessel density (TVDss) and perfused vessel density (PVDss) of the sublingual area were evaluated before and during 50% flow reduction (TVDss F50 , PVDss F50 ) after a WA and compared to conventional echocardiographic parameters as indicators of the success or failure of the WA. Patients (n = 13) aged 49 ± 18 years, who received VA-ECMO for the treatment of refractory CS due to pulmonary embolism (n = 5), post cardiotomy (n = 3), acute coronary syndrome (n = 2), myocarditis (n = 2) and drug intoxication (n = 1), were included. TVDss F50 (21.9 vs 12.9 mm/mm 2 , p = 0.001), PVDss F50 (19.7 vs 12.4 mm/mm 2 , p = 0.01) and aortic velocity-time integral (VTI) at 50% flow reduction (VTI F50 ) were higher in patients successfully weaned vs not successfully weaned. The area under the curve (AUC) was 0.99 vs 0.93 vs 0.85 for TVDss F50 (small vessels) >12.2 mm/mm 2 , left ventricular ejection fraction (LVEF) >15% and aortic VTI >11 cm. Likewise, the AUC was 0.91 vs 0.93 vs 0.85 for the PVDss F50 (all vessels) >14.8 mm/mm 2 , LVEF >15% and aortic VTI >11 cm. This study identified sublingual microcirculation as a novel potential marker for identifying successful weaning from VA-ECMO. Sustained values of TVDss F50 and PVDss F50 were found to be specific and sensitive indicators of successful weaning from VA-ECMO as compared to echocardiographic parameters.

[Thermoregulation in hypertensive elderly patients during physiotherapy].

PubMed

Abramovich, S G

2002-01-01

Effects of therapeutic physical factors on thermoregulation and thermoreactivity of skin were studied in 222 elderly patients with hypertension. It is shown that sodium chloride half-baths, "dry" carbon dioxide baths and general magnetotherapy correct thermal asymmetry and normalize skin thermoreactivity, i.e. produce a positive effect on microcirculation.

MgO melting curve constraints from shock temperature and rarefaction overtake measurements in samples preheated to 2300 K

NASA Astrophysics Data System (ADS)

Fat'yanov, O. V.; Asimow, P. D.

2014-05-01

Continuing our effort to obtain experimental constraints on the melting curve of MgO at 100-200 GPa, we extended our target preheating capability to 2300 K. Our new Mo capsule design holds a long MgO crystal in a controlled thermal gradient until impact by a Ta flyer launched at up to 7.5 km/s on the Caltech two-stage light-gas gun. Radiative shock temperatures and rarefaction overtake times were measured simultaneously by a 6-channel VIS/NIR pyrometer with 3 ns time resolution. The majority of our experiments showed smooth monotonic increases in MgO sound speed and shock temperature with pressure from 197 to 243 GPa. The measured temperatures as well as the slopes of the pressure dependences for both temperature and sound speed were in good agreement with those calculated numerically for the solid phase at our peak shock compression conditions. Most observed sound speeds, however, were ~800 m/s higher than those predicted by the model. A single unconfirmed data point at 239 GPa showed anomalously low temperature and sound speed, which could both be explained by partial melting in this experiment and could suggest that the Hugoniot of MgO preheated to 2300 K crosses its melting line just slightly above 240 GPa.

Primary proximal tubule injury leads to epithelial cell cycle arrest, fibrosis, vascular rarefaction, and glomerulosclerosis

PubMed Central

Bonventre, Joseph V

2014-01-01

Tubular injury has a major etiological role in fibrosis. For many years, this relationship has been dominated by the perception that epithelial cells are transformed into myofibroblasts that proliferate and generate fibrotic matrix—the so-called epithelial-to-mesenchymal transition. Here we focus on mechanisms by which injury to the tubule results in fibrosis because of paracrine mechanisms. Specific injury to the proximal tubule results in inflammation, reversible injury, and adaptive repair if the insult is mild, self-limited in time, and occurs in a background of a normal kidney. Repeated injury, in contrast, leads to maladaptive repair with sustained tubule injury, chronic inflammation, proliferation of interstitial myofibroblasts, vascular rarefaction, interstitial fibrosis, and glomerular sclerosis. During the maladaptive repair process after the renal insult, many tubular cells become arrested in the G2/M phase of the cell cycle. This results in activation of the DNA repair response with the resultant synthesis and secretion of pro-fibrotic factors. Pharmacologic interventions that enhance the movement through G2/M or facilitate apoptosis of cells that otherwise would be blocked in G2/M may reduce the development of fibrosis after kidney injury and reduce the progression of chronic kidney disease. PMID:26310195

MgO melting curve constraints from shock temperature and rarefaction overtake measurements in samples preheated to 2300 K

NASA Astrophysics Data System (ADS)

Fat'yanov, O.; Asimow, P.

2013-06-01

In a continuous effort to determine experimentally the melting curve of MgO at 100-200 GPa, we extended our target preheating capability to 2300 K. The limit was primarily caused by intense sublimation of pure MgO in vacuum above ~2050 K. Completely redesigned Mo capsules holding ~20 mm long MgO crystals with controlled thermal gradients were impacted by thin Ta flyers launched at 6.5 to 7.5 km/s on the Caltech two-stage light-gas gun. Radiative shock temperatures and rarefaction overtake times were measured simultaneously by a 6-channel pyrometer with 3 ns time resolution, over 440-750 nm spectral range. All our experiments showed smooth pressure dependence of MgO sound speed consistent with the solid phase at 204-239 GPa. Observed temperatures are ~1000 K lower than those predicted by the solid phase model, but the plot of measured shock temperature versus pressure exhibits a pattern typical of shock melting at the highest pressure investigated. This may suggest that the Hugoniot of MgO preheated to 2300 K crosses its melting line at 220-240 GPa. Sound speed data indistinguishable from the solid phase model do not exclude the possibility of melting there.

Comparison of bacterial and fungal communities between natural and planted pine forests in subtropical China.

PubMed

Nie, Ming; Meng, Han; Li, Ke; Wan, Jia-Rong; Quan, Zhe-Xue; Fang, Chang-Ming; Chen, Jia-Kuan; Li, Bo

2012-01-01

To improve our understanding of the changes in bacterial and fungal diversity in natural pine and planted forests in subtropical region of China, we examined bacterial and fungal communities from a native and a nearby planted pine forest of the Mt. Lushan by constructing clone libraries of 16S and 18S rRNA genes. For bacterial communities, Proteobacteria and Acidobacteria were dominant bacterial taxa in both two types of forest soils. The Shannon-Wiener diversity index, rarefaction curve analysis, and LibShuff analysis suggest that these two forests contained similar diversity of bacterial communities. Low soil acidity (pH ≈ 4) of our study forests might be one of the most important selection factors determining growth of acidophilic Acidobacteria and Proteobacteria. However, the natural forest harbored greater level of fungal diversity than the planted forest according to the Shannon-Wiener diversity index and rarefaction curve analysis. Basidiomycota and Ascomycota were dominant fungal taxa in the soils of natural and planted forests, respectively. Our results suggest that fungal community was more sensitive than the bacterial community in characterizing the differences in plant cover impacts on the microbial flora in the natural and planted forests. The natural and planted forests may function differently due to the differences in soil fungal diversity and relative abundance.

Initiation of long, free-standing z discharges by CO2 laser gas heating

NASA Astrophysics Data System (ADS)

Niemann, C.; Tauschwitz, A.; Penache, D.; Neff, S.; Knobloch, R.; Birkner, R.; Presura, R.; Hoffmann, D. H. H.; Yu, S. S.; Sharp, W. M.

2002-01-01

High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore, they are considered an interesting solution for final focus and beam transport in a heavy ion beam fusion reactor. At the Gesellschaft für Schwerionenforschung accelerator facility, 50 cm long, free-standing discharge channels were created in a 60 cm diameter metallic chamber. Discharges with currents of 45 kA in 2 to 25 mbar ammonia (NH3) gas are initiated by a CO2 laser pulse along the channel axis before the capacitor bank is triggered. Resonant absorption of the laser, tuned to the v2 vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. The influence of an electric prepulse on the high current discharge was investigated. This article describes the laser-gas interaction and the discharge initiation mechanism. We found that channels are magnetohydrodynamic stable up to currents of 45 kA, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a one-dimensional Lagrangian fluid code (CYCLOPS) and is identified as the dominant initiation mechanism of the discharge.

Existence regimes for shocks in inhomogeneous magneto-plasmas having entropy

NASA Astrophysics Data System (ADS)

Iqbal, Javed; Yaqub Khan, M.

2018-04-01

The finding of connection of plasma density and temperature with entropy gives an incitement to study different plasma models with respect to entropy. Nonlinear dissipative one- and two-dimensional structures (shocks) are investigated in nonuniform magnetized plasma with respect to entropy. The dissipation comes in the medium through ion-neutral collisions. The linear dispersion relation is derived. The Korteweg-deVries-Burgers and Kadomtsev-Petviashvili-Burgers equations are derived for nonlinear drift waves in 1-D and 2-D by employing the drift approximation. It is found that vd/u ( vd is the diamagnetic drift velocity and u is the velocity of nonlinear structure) plays a significant role in the shock formation. It is also found that entropy has a significant effect on the strength of shocks. It is noticed that v d/u determines the rarefactive and compressive nature of the shocks. It is observed that upper and lower bounds exist for the shock velocity. It is also observed that the existing regimes for both one- and two-dimensional shocks for kappa distributed electrons are different from shocks with Cairns distributed electrons. Both rarefactive and compressive shocks are found for the 1-D drift waves with kappa distributed electrons. Interestingly, it is noticed that entropy enhances the strength of one- and two-dimensional shocks.

Gauging the likelihood of stable cavitation from ultrasound contrast agents

NASA Astrophysics Data System (ADS)

Bader, Kenneth B.; Holland, Christy K.

2013-01-01

The mechanical index (MI) was formulated to gauge the likelihood of adverse bioeffects from inertial cavitation. However, the MI formulation did not consider bubble activity from stable cavitation. This type of bubble activity can be readily nucleated from ultrasound contrast agents (UCAs) and has the potential to promote beneficial bioeffects. Here, the presence of stable cavitation is determined numerically by tracking the onset of subharmonic oscillations within a population of bubbles for frequencies up to 7 MHz and peak rarefactional pressures up to 3 MPa. In addition, the acoustic pressure rupture threshold of an UCA population was determined using the Marmottant model. The threshold for subharmonic emissions of optimally sized bubbles was found to be lower than the inertial cavitation threshold for all frequencies studied. The rupture thresholds of optimally sized UCAs were found to be lower than the threshold for subharmonic emissions for either single cycle or steady state acoustic excitations. Because the thresholds of both subharmonic emissions and UCA rupture are linearly dependent on frequency, an index of the form ICAV = Pr/f (where Pr is the peak rarefactional pressure in MPa and f is the frequency in MHz) was derived to gauge the likelihood of subharmonic emissions due to stable cavitation activity nucleated from UCAs.

Head-on collision between two dust acoustic solitary waves and study of rogue waves in multicomponent dusty plasma

NASA Astrophysics Data System (ADS)

Singh, Kuldeep; Kaur, Nimardeep; Saini, N. S.

2017-06-01

In this investigation, the study of head-on collision between two dust acoustic solitary waves (DASWs) and characteristics of rogue waves in a dusty plasma composed of dust fluid, kappa distributed ions, electrons, and positrons has been presented. Two Korteweg-de Vries equations are derived by employing the extended Poincaré-Lighthill-Kuo reductive perturbation method. The analytical phase shifts and trajectories after head-on collision of two DA solitary waves have been studied numerically. It is found that the presence of superthermal ions, electrons, as well as positrons; concentrations of electrons and positrons; and temperature of electrons and dust have an emphatic influence on the phase shifts after the head-on collision of two rarefactive DA solitary waves. The time evolution of two rarefactive DASWs has also been presented. Further, the generation of dust acoustic rogue waves (DARWs) has been studied in the framework of rational solution of nonlinear Schrödinger equation. The dependence of the rogue wave profile on the relevant physical parameters has been discussed in detail. It is emphasized that the real implementation of our present results may be of great importance in different regions of space and astrophysical environments, especially in the interstellar medium and Jupiter rings.

Central Sympathetic Modulation Reverses Microvascular Alterations in a Rat Model of High-Fat Diet-Induced Metabolic Syndrome.

PubMed

Nascimento, Alessandro R; Machado, Marcus V; Gomes, Fabiana; Vieira, Aline B; Gonçalves-de-Albuquerque, Cassiano F; Lessa, Marcos A; Bousquet, Pascal; Tibiriçá, Eduardo

2016-05-01

The objective of this study was to investigate the role of the SNS on hemodynamic, metabolic, and microvascular alterations in a rat model of HFD-induced MS with salt supplementation. In total, 40 adult male Wistar rats were fed normal chow (n = 10) or a HFD (n = 30) for 20 weeks. Thereafter, the HFD group received the centrally acting sympatho-modulatory drugs clonidine (0.1 mg/kg) or rilmenidine (1 mg/kg) or vehicle (n = 10/group) orally by gavage. FCD was evaluated using intravital video microscopy, and the SCD was evaluated using histochemical analysis. The pharmacological modulation of the SNS induced concomitant reductions in SBP, HR and plasma catecholamine levels. These effects were accompanied by a reversal of functional and structural capillary rarefaction in the skeletal muscle in both treated groups and an increase in SCD in the left ventricle only in the rilmenidine group. Improvement of the lipid profile and of glucose intolerance was also obtained only with rilmenidine treatment. Modulation of sympathetic overactivity results in the reversal of microvascular rarefaction in the skeletal muscle and left ventricle and improves metabolic parameters in an experimental model of MS in rats. © 2016 John Wiley & Sons Ltd.

Gauging the likelihood of stable cavitation from ultrasound contrast agents.

PubMed

Bader, Kenneth B; Holland, Christy K

2013-01-07

The mechanical index (MI) was formulated to gauge the likelihood of adverse bioeffects from inertial cavitation. However, the MI formulation did not consider bubble activity from stable cavitation. This type of bubble activity can be readily nucleated from ultrasound contrast agents (UCAs) and has the potential to promote beneficial bioeffects. Here, the presence of stable cavitation is determined numerically by tracking the onset of subharmonic oscillations within a population of bubbles for frequencies up to 7 MHz and peak rarefactional pressures up to 3 MPa. In addition, the acoustic pressure rupture threshold of an UCA population was determined using the Marmottant model. The threshold for subharmonic emissions of optimally sized bubbles was found to be lower than the inertial cavitation threshold for all frequencies studied. The rupture thresholds of optimally sized UCAs were found to be lower than the threshold for subharmonic emissions for either single cycle or steady state acoustic excitations. Because the thresholds of both subharmonic emissions and UCA rupture are linearly dependent on frequency, an index of the form I(CAV) = P(r)/f (where P(r) is the peak rarefactional pressure in MPa and f is the frequency in MHz) was derived to gauge the likelihood of subharmonic emissions due to stable cavitation activity nucleated from UCAs.

Gauging the likelihood of stable cavitation from ultrasound contrast agents

PubMed Central

Bader, Kenneth B; Holland, Christy K

2015-01-01

The mechanical index (MI) was formulated to gauge the likelihood of adverse bioeffects from inertial cavitation. However, the MI formulation did not consider bubble activity from stable cavitation. This type of bubble activity can be readily nucleated from ultrasound contrast agents (UCAs) and has the potential to promote beneficial bioeffects. Here, the presence of stable cavitation is determined numerically by tracking the onset of subharmonic oscillations within a population of bubbles for frequencies up to 7 MHz and peak rarefactional pressures up to 3 MPa. In addition, the acoustic pressure rupture threshold of an UCA population was determined using the Marmottant model. The threshold for subharmonic emissions of optimally sized bubbles was found to be lower than the inertial cavitation threshold for all frequencies studied. The rupture thresholds of optimally sized UCAs were found to be lower than the threshold for subharmonic emissions for either single cycle or steady state acoustic excitations. Because the thresholds of both subharmonic emissions and UCA rupture are linearly dependent on frequency, an index of the form ICAV = Pr/f (where Pr is the peak rarefactional pressure in MPa and f is the frequency in MHz) was derived to gauge the likelihood of subharmonic emissions due to stable cavitation activity nucleated from UCAs. PMID:23221109

Coupled Hydrodynamic Instability Growth on Oblique Interfaces with a Reflected Rarefaction

NASA Astrophysics Data System (ADS)

Rasmus, A. M.; Flippo, K. A.; di Stefano, C. A.; Doss, F. W.; Hager, J. D.; Merritt, E. C.; Cardenas, T.; Schmidt, D. W.; Kline, J. L.; Kuranz, C. C.

2017-10-01

Hydrodynamic instabilities play an important role in the evolution of inertial confinement fusion and astrophysical phenomena. Three of the Omega-EP long pulse beams (10 ns square pulse, 14 kJ total energy, 1.1 mm spot size) drive a supported shock across a heavy-to-light, oblique, interface. Single- and double-mode initial conditions seed coupled Richtmyer-Meshkov (RM), Rayleigh-Taylor (RT), and Kelvin-Helmholtz (KH) growth. At early times, growth is dominated by RM and KH, whereas at late times a rarefaction from laser turn-off reaches the interface, leading to decompression and RT growth. The addition of a thirty degree tilt does not alter mix width to within experimental error bars, even while significantly altering spike and bubble morphology. The results of single and double-mode experiments along with simulations using the multi-physics hydro-code RAGE will be presented. This work performed under the auspices of the U.S. Department of Energy by LANL under contract DE-AC52-06NA25396. This work is funded by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, Grant Number DE-NA0002956. This material is partially supported by DOE Office of Science Graduate Student Research (SCGSR) program.

Development and Application of a Tendon Prosthesis for Early Functional Restoration of the Hand.

DTIC Science & Technology

1975-09-01

number of studies to fully elucidate this problem. A. Human Foetus Circulation This study dealt with the intrinsic microcirculation in the human... foetus . The work was done by Dr. Howard Caplan. This study resulted in an entirely new understanding of tendon vasculature. A copy of his paper is

[Capillaroscopy in patients with chronic alcoholic pancreatitis].

PubMed

Teixeira, G P; de Alencar, R; Fonseca, M de O; Bernardini, E M

1996-01-01

The aim of this study was verify frequency and morphological presentations of microangiopathy in patients with alcoholic chronic pancreatitis, using nailfold capillaroscopy. All patients showed morphological and functional capillary abnormalities. None of them had a normal capillaroscopy. Our findings may suggest an important role of microcirculation in Alcoholic Chronic Pancreatitis pathogenesis and/or its course.

78 FR 64961 - Center for Scientific Review; Amended Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-30

... DEPARTMENT OF HEALTH AND HUMAN SERVICES National Institutes of Health Center for Scientific Review; Amended Notice of Meeting Notice is hereby given of a change in the meeting of the Hypertension and Microcirculation Study Section, October 10, 2013, 08:00 a.m. to October 10, 2013, 07:30 p.m., Washington Hilton...

Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation

PubMed Central

Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

2016-01-01

Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type–III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

The Role of Aquaporins in Ocular Lens Homeostasis

PubMed Central

Schey, Kevin L.; Petrova, Rosica S.; Gletten, Romell B.; Donaldson, Paul J.

2017-01-01

Aquaporins (AQPs), by playing essential roles in the maintenance of ocular lens homeostasis, contribute to the establishment and maintenance of the overall optical properties of the lens over many decades of life. Three aquaporins, AQP0, AQP1 and AQP5, each with distinctly different functional properties, are abundantly and differentially expressed in the different regions of the ocular lens. Furthermore, the diversity of AQP functionality is increased in the absence of protein turnover by age-related modifications to lens AQPs that are proposed to alter AQP function in the different regions of the lens. These regional differences in AQP functionality are proposed to contribute to the generation and directionality of the lens internal microcirculation; a system of circulating ionic and fluid fluxes that delivers nutrients to and removes wastes from the lens faster than could be achieved by passive diffusion alone. In this review, we present how regional differences in lens AQP isoforms potentially contribute to this microcirculation system by highlighting current areas of investigation and emphasizing areas where future work is required. PMID:29231874

Blood Perfusion in Microfluidic Models of Pulmonary Capillary Networks: Role of Geometry and Hematocrit

NASA Astrophysics Data System (ADS)

Stauber, Hagit; Waisman, Dan; Sznitman, Josue; Technion-IIT Team; Department of Neonatology Carmel Medical Center; Faculty of Medicine-Technion IIT Collaboration

2015-11-01

Microfluidic platforms are increasingly used to study blood microflows at true physiological scale due to their ability to overcome manufacturing obstacle of complex anatomical morphologies, such as the organ-specific architectures of the microcirculation. In the present work, we utilize microfluidic platforms to devise in vitro models of the underlying pulmonary capillary networks (PCN), where capillary lengths and diameters are similar to the size of RBCs (~ 5-10 μm). To better understand flow characteristics and dispersion of red blood cells (RBCs) in PCNs, we have designed microfluidic models of alveolar capillary beds inspired by the seminal ``sheet flow'' model of Fung and Sobin (1969). Our microfluidic PCNs feature confined arrays of staggered pillars with diameters of ~ 5,7 and 10 μm, mimicking the dense structure of pulmonary capillary meshes. The devices are perfused with suspensions of RBCs at varying hematocrit levels under different flow rates. Whole-field velocity patterns using micro-PIV and single-cell tracking using PTV are obtained with fluorescently-labelled RBCs and discussed. Our experiments deliver a real-scale quantitative description of RBC perfusion characteristics across the pulmonary capillary microcirculation.

Microfluidic approach of Sickled Cell Anemia

NASA Astrophysics Data System (ADS)

Abkarian, Manouk; Loiseau, Etienne; Massiera, Gladys

2012-11-01

Sickle Cell Anemia is a disorder of the microcirculation caused by a genetic point mutation that produces an altered hemoglobin protein called HbS. HbS self-assembles reversibly into long rope like fibers inside the red blood cells. The resulting distorded sickled red blood cells are believed to block the smallest capillaries of the tissues producing anemia. Despite the large amount of work that provided a thorough understanding of HbS polymerization in bulk as well as in intact red blood cells at rest, no consequent cellular scale approaches of the study of polymerization and its link to the capillary obstruction have been proposed in microflow, although the problem of obstruction is in essence a circulatory problem. Here, we use microfluidic channels, designed to mimic physiological conditions (flow velocity, oxygen concentration, hematocrit...) of the microcirculation to carry out a biomimetic study at the cellular scale of sickled cell vaso-occlusion. We show that flow geometry, oxygen concentration, white blood cells and free hemoglobin S are essential in the formation of original cell aggregates which could play a role in the vaso-occlusion events.

Bifurcations: Focal Points of Particle Adhesion in Microvascular Networks

PubMed Central

Prabhakarpandian, Balabhaskar; Wang, Yi; Rea-Ramsey, Angela; Sundaram, Shivshankar; Kiani, Mohammad F.; Pant, Kapil

2011-01-01

Objective Particle adhesion in vivo is dependent on microcirculation environment which features unique anatomical (bifurcations, tortuosity, cross-sectional changes) and physiological (complex hemodynamics) characteristics. The mechanisms behind these complex phenomena are not well understood. In this study, we used a recently developed in vitro model of microvascular networks, called Synthetic Microvascular Network, for characterizing particle adhesion patterns in the microcirculation. Methods Synthetic microvascular networks were fabricated using soft lithography processes followed by particle adhesion studies using avidin and biotin-conjugated microspheres. Particle adhesion patterns were subsequently analyzed using CFD based modeling. Results Experimental and modeling studies highlighted the complex and heterogeneous fluid flow patterns encountered by particles in microvascular networks resulting in significantly higher propensity of adhesion (>1.5X) near bifurcations compared to the branches of the microvascular networks. Conclusion Bifurcations are the focal points of particle adhesion in microvascular networks. Changing flow patterns and morphology near bifurcations are the primary factors controlling the preferential adhesion of functionalized particles in microvascular networks. Synthetic microvascular networks provide an in vitro framework for understanding particle adhesion. PMID:21418388

Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation.

PubMed

Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

2016-08-02

Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type-III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications.

Ultrahigh sensitive optical microangiography reveals depth-resolved microcirculation and its longitudinal response to prolonged ischemic event within skeletal muscles in mice

NASA Astrophysics Data System (ADS)

Jia, Yali; Qin, Jia; Zhi, Zhongwei; Wang, Ruikang K.

2011-08-01

The primary pathophysiology of peripheral arterial disease is associated with impaired perfusion to the muscle tissue in the lower extremities. The lack of effective pharmacologic treatments that stimulate vessel collateralization emphasizes the need for an imaging method that can be used to dynamically visualize depth-resolved microcirculation within muscle tissues. Optical microangiography (OMAG) is a recently developed label-free imaging method capable of producing three-dimensional images of dynamic blood perfusion within microcirculatory tissue beds at an imaging depth of up to ~2 mm, with an unprecedented imaging sensitivity of blood flow at ~4 μm/s. In this paper, we demonstrate the utility of OMAG in imaging the detailed blood flow distributions, at a capillary-level resolution, within skeletal muscles of mice. By use of the mouse model of hind-limb ischemia, we show that OMAG can assess the time-dependent changes in muscle perfusion and perfusion restoration along tissue depth. These findings indicate that OMAG can represent a sensitive, consistent technique to effectively study pharmacologic therapies aimed at promoting the growth and development of collateral vessels.

Enhanced visualization of the retinal vasculature using depth information in OCT.

PubMed

de Moura, Joaquim; Novo, Jorge; Charlón, Pablo; Barreira, Noelia; Ortega, Marcos

2017-12-01

Retinal vessel tree extraction is a crucial step for analyzing the microcirculation, a frequently needed process in the study of relevant diseases. To date, this has normally been done by using 2D image capture paradigms, offering a restricted visualization of the real layout of the retinal vasculature. In this work, we propose a new approach that automatically segments and reconstructs the 3D retinal vessel tree by combining near-infrared reflectance retinography information with Optical Coherence Tomography (OCT) sections. Our proposal identifies the vessels, estimates their calibers, and obtains the depth at all the positions of the entire vessel tree, thereby enabling the reconstruction of the 3D layout of the complete arteriovenous tree for subsequent analysis. The method was tested using 991 OCT images combined with their corresponding near-infrared reflectance retinography. The different stages of the methodology were validated using the opinion of an expert as a reference. The tests offered accurate results, showing coherent reconstructions of the 3D vasculature that can be analyzed in the diagnosis of relevant diseases affecting the retinal microcirculation, such as hypertension or diabetes, among others.

Microvascular responsiveness in obesity: implications for therapeutic intervention

PubMed Central

Bagi, Zsolt; Feher, Attila; Cassuto, James

2012-01-01

Obesity has detrimental effects on the microcirculation. Functional changes in microvascular responsiveness may increase the risk of developing cardiovascular complications in obese patients. Emerging evidence indicates that selective therapeutic targeting of the microvessels may prevent life-threatening obesity-related vascular complications, such as ischaemic heart disease, heart failure and hypertension. It is also plausible that alterations in adipose tissue microcirculation contribute to the development of obesity. Therefore, targeting adipose tissue arterioles could represent a novel approach to reducing obesity. This review aims to examine recent studies that have been focused on vasomotor dysfunction of resistance arteries in obese humans and animal models of obesity. Particularly, findings in coronary resistance arteries are contrasted to those obtained in other vascular beds. We provide examples of therapeutic attempts, such as use of statins, ACE inhibitors and insulin sensitizers to prevent obesity-related microvascular complications. We further identify some of the important challenges and opportunities going forward. LINKED ARTICLES This article is part of a themed section on Fat and Vascular Responsiveness. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-3 PMID:21797844

Subtle exchange model of flow depended on the blood cell shape to enhance the micro-circulation in capillary

NASA Astrophysics Data System (ADS)

Chan, Iatneng

2012-02-01

In general the exchange of gases or other material in capillary system is conceptualized by the diffusion effect. But in this model, we investigate a micro-flow pattern by simulation and computation on a micro-exchange model in which the blood cell is a considered factor, especially on its shape. It shows that the cell benefits the circulation while it is moving in the capillary. In the study, the flow detail near the cell surface is mathematically analyzed, such that the Navier-Stokes equations are applied and the viscous factor is also briefly considered. For having a driven force to the motion of micro-circulation, a breathing mode is suggested to approximately compute on the flow rate in the blood capillary during the transfer of cell. The rate is also used to estimate the enhancement to the circulation in additional to the outcome of diffusion. Moreover in the research, the shape change of capillary wall under pressure influence is another element in the beginning calculation for the effect in the assistance to cell motion.

Retinal microvascular network alterations: potential biomarkers of cerebrovascular and neural diseases.

PubMed

Cabrera DeBuc, Delia; Somfai, Gabor Mark; Koller, Akos

2017-02-01

Increasing evidence suggests that the conditions of retinal microvessels are indicators to a variety of cerebrovascular, neurodegenerative, psychiatric, and developmental diseases. Thus noninvasive visualization of the human retinal microcirculation offers an exceptional opportunity for the investigation of not only the retinal but also cerebral microvasculature. In this review, we show how the conditions of the retinal microvessels could be used to assess the conditions of brain microvessels because the microvascular network of the retina and brain share, in many aspects, standard features in development, morphology, function, and pathophysiology. Recent techniques and imaging modalities, such as optical coherence tomography (OCT), allow more precise visualization of various layers of the retina and its microcirculation, providing a "microscope" to brain microvessels. We also review the potential role of retinal microvessels in the risk identification of cerebrovascular and neurodegenerative diseases. The association between vision problems and cerebrovascular and neurodegenerative diseases, as well as the possible role of retinal microvascular imaging biomarkers in cerebrovascular and neurodegenerative screening, their potentials, and limitations, are also discussed. Copyright © 2017 the American Physiological Society.

Tissue viability imaging for quantification of skin erythema and blanching

NASA Astrophysics Data System (ADS)

Nilsson, Gert E.; Leahy, Martin J.

2010-02-01

Naked eye observation has up to recently been the main method of determining skin erythema (vasodilatation) and blanching (vasoconstriction) in skin testing. Since naked eye observation is a highly subjective and investigatordependent method, it is difficult to attain reproducibility and to compare results reported by different researchers performing their studies at different laboratories. Consequently there is a need for more objective, quantitative and versatile methods in the assessment of alterations in skin erythema and blanching caused by internal and external factors such as the intake of vasoactive drugs, application of agents on the skin surface and by constituents in the environment. Since skin microcirculation is sensitive to applied pressure and heat, such methods should preferably be noninvasive and designed for remote use without touching the skin. As skin microcirculation further possesses substantial spatial variability, imaging techniques are to be preferred before single point measurements. An emerging technology based on polarization digital camera spectroscopy - Tissue Viability Imaging (TiVi) - fulfills these requirements. The principles of TiVi (1) and some of its early applications (2-5) are addressed in this paper.

Cauchy problem with general discontinuous initial data along a smooth curve for 2-d Euler system

NASA Astrophysics Data System (ADS)

Chen, Shuxing; Li, Dening

2014-09-01

We study the Cauchy problems for the isentropic 2-d Euler system with discontinuous initial data along a smooth curve. All three singularities are present in the solution: shock wave, rarefaction wave and contact discontinuity. We show that the usual restrictive high order compatibility conditions for the initial data are automatically satisfied. The local existence of piecewise smooth solution containing all three waves is established.

Experimental and Computational Modeling of Rarefaction Wave Eliminators Suitable for the BRL 2.44 m Shock Tube

DTIC Science & Technology

1983-06-01

made directly from the oscilloscope. Finai data processing was completed with the computer, printer , and plotter. Tables and plots of pressure-time...BASIC DATA ACQUISITION PRINTER FINAL DATA REDUCTION TEKTRONIX 4641 HARD COPY[ TEKTRONIX 4631 PLOTTER COMPUTER TEKTRONIX TEKTRONIX I 4662 4052 DIGITAL...79409 Columbus, OH 43201 1 University of Arkansas 1 Director Department of Physics Applied Physics Laboratory ATTN: Prof 0. Zinke The Johns Hopkins

Puerarin Attenuates Cerebral Damage by Improving Cerebral Microcirculation in Spontaneously Hypertensive Rats

PubMed Central

Wu, Xu-Dong; Wang, Chen; Zhang, Zhen-Ying; Fu, Yan; Liu, Feng-Ying; Liu, Xiu-Hua

2014-01-01

Puerariae Lobatae Radix (Gegen in Chinese) is the dried root of Pueraria lobata, a semiwoody, perennial, and leguminous vine native to China. Puerarin is one of the effective components of isoflavones isolated from the root of Pueraria lobata. Previous studies showed that extracts derived from the root of Pueraria lobata possessed antihypertensive effect. Our study is to investigate whether puerarin contributes to prevention of stroke by improving cerebral microcirculation in rats. Materials and Methods. Video microscopy and laser Doppler perfusion imaging on the pia mater were used to measure the diameter of microvessel and blood perfusion in 12-week old spontaneously hypertensive rats (SHRs) and age-matched normotensive WKY rats. Histological alterations were observed by hematoxylin and eosin staining, and microvessel density in cerebral tissue was measured by immunohistochemical analysis with anti-Factor VIII antibody. Cell proliferation was detected by [3H]-TdR incorporation, and activities of p42/44 mitogen activated protein kinases (p42/44 MAPKs) were detected by western blot analysis in cultured cerebral microvascular endothelial cells (MECs). Results. Intravenous injection of puerarin relaxed arterioles and increased the blood flow perfusion in the pia mater in SHRs. Puerarin treatment for 14 days reduced the blood pressure to a normal level in SHRs (P < 0.05) and increased the arteriole diameter in the pia mater significantly as compared with vehicle treatment. Arteriole remodeling, edema, and ischemia in cerebral tissue were attenuated in puerarin-treated SHRs. Microvessel density in cerebral tissue was greater with puerarin than with vehicle treatment. Puerarin-treated MECs showed greater proliferation and p42/44 MAPKs activities than vehicle treatment. Conclusions. Puerarin possesses effects of antihypertension and stroke prevention by improved microcirculation in SHRs, which results from the increase in cerebral blood perfusion both by arteriole relaxation and p42/44 MAPKs-mediated angiogenesis. PMID:24715930

Peripheral microcirculation during pregnancy and in women with pregnancy induced hypertension.

PubMed

Ohlmann, P; Jung, F; Mrowietz, C; Alt, T; Alt, S; Schmidt, W

2001-01-01

During pregnancy the cardiovascular system undergoes several changes so as to adapt the maternal organism to the strains of pregnancy. These adaptations can assume a pathological development in persons with a previous history of cardiovascular problems. On the other hand the absence of these adaptations may lead to a pathological course of pregnancy. Pregnancy induced hypertension (PIH) may be such a pathological development due to maladaptation. The causes are for the most part unknown. For some time it has been assumed that it is due to microcirculatory disorders. Using periungual capillary microscopy the present study prospectively investigated the changes in peripheral microcirculation during pregnancy focussing on pregnancy induced hypertension. Sixty-seven women with a normal course of pregnancy and 28 women with pregnancy induced hypertension were evaluated. Throughout the prospective study 3 examinations were performed during pregnancy and one during childbed. The women who developed a PIH were registered during the third trimester. Erythrocyte velocity at rest and vascular reagibility of capillaries following a 3 minute ischaemia were evaluated. In the course of pregnancy a significant increase of approximately 30% in erythrocyte velocity could be observed. Interpolation to obtain the best strait line result demonstrates that it is a continuous increase. Erythrocyte velocity returns to normal in the course of 14 weeks post partum. Due to a physiological vasodilatation during pregnancy, vascular reaction to ischaemic stress significantly decreases. During childbed these changes return to normal. Examinations on women with pregnancy induced hypertension not only showed a significant reduction of microcirculation under resting conditions but also a different pattern of reaction to ischaemic stress. Erythrocyte velocity under resting conditions lies 36% below normal values. Furthermore the distinctly shortened hyperaemic period indicates a hightened sensitivity to vasoconstrictive substances in women with PIH. While taking into account the clinical data a positive correlation with the severity of the illness was able to be established.

Eccentric exercises for the management of tendinopathy of the main body of the Achilles tendon with or without the AirHeel Brace. A randomized controlled trial. A: effects on pain and microcirculation.

PubMed

Knobloch, Karsten; Schreibmueller, Louisa; Longo, Umile Giuseppe; Vogt, Peter M

2008-01-01

To compare eccentric training and the combination of eccentric training with the AirHeel Brace for the management of tendinopathy of the main body of the Achilles tendon. We recruited 116 subjects with unilateral tendinopathy of the main body of the Achilles tendon, who were randomized in two groups. Group A performed a regimen of daily eccentric training associated with the AirHeel Brace (Donjoy Orthopedics, Vista, CA, USA). Group B performed the same eccentric training without the AirHeel Brace. Tendon microcirculatory mapping was performed using combined Laser-Doppler and spectrophotometry. Pre- and post-operative FAOS score and VAS score were used to evaluate the patients. The FAOS score and the VAS score showed significant improvements from pre-operative to post-operative values in both groups (A 5.1 +/- 2 vs. 2.9 +/- 2.4, 43% reduction and B: 5.4 +/- 2.1 vs. 3.6 +/- 2.4, 33% reduction, both p = 0.0001). There were no statistically significant differences in FAOS score and VAS score when comparing the two groups after the end of the intervention. In Group A, tendon oxygen saturation in the main body of the Achilles tendon showed significant increase from pre- to post-management values (68 +/- 12 vs.74 +/- 8%, p = 0.003). Post-capillary venous filling pressures showed significant reduction from pre- to post-intervention values. Eccentric training, associated or not with the AirHeel Brace, produces the same effect in patients with tendinopathy of the main body of the Achilles tendon. The combination of eccentric training with the AirHeel Brace can optimize tendon microcirculation, but these micro-circulator advantages do not translate into superior clinical performance when compared with eccentric training alone.

Progressive thermopreconditioning attenuates rat cardiac ischemia/reperfusion injury by mitochondria-mediated antioxidant and antiapoptotic mechanisms.

PubMed

Chien, Chen-Yen; Chien, Chiang-Ting; Wang, Shoei-Shen

2014-08-01

Progressive thermal preconditioning (PTP) provides vascular protection with less hemodynamic fluctuations, endoplasmic reticulum (ER), and oxidative stress compared with whole body hyperthermia. We suggest PTP might efficiently diminish cardiac ischemia/reperfusion-induced apoptosis and autophagy injury. A total of 67 male Wistar rats were divided into a non-PTP control group, 24 or 72 hours after a single cycle or 3 consecutive cycles of PTP in a 42°C water bath (1-24, 1-72, 3-24, and 3-72 groups). We measured the cardiac O2(-) amount in vivo in response to left anterior descending coronary artery ligation for 2 hours and reperfusion for 3 hours. Cardiac function and injury were determined by microcirculation, electrocardiography, and infarct size. The PTP-induced protective effects on nicotinamide adenine dinucleotide phosphate oxidase gp91-mediated oxidative stress, ER stress, and apoptosis- and autophagy-related mechanisms were examined using Western blot and immunohistochemistry. Coronary arterial ischemia/reperfusion depressed cardiac microcirculation, induced ST-segment elevation and increased infarct size in non-PTP and PTP rats. Ischemia/reperfusion enhanced the cardiac O2(-) levels by enhanced nicotinamide adenine dinucleotide phosphate oxidase gp91 expression, cytosolic cytochrome C release, and decreased mitochondrial Bcl-2 expression. Cardiac injury activated ER stress-78-kDa glucose-regulated protein expression, increased the Bax/Bcl-2 ratio, cleaved caspase 3 expression and poly-(ADP-ribose)-polymerase fragments, leading to apoptosis formation, and promoted LC3-II expression, resulting in autophagy formation. PTP treatment elevated heat shock protein 70, heat shock protein 32, Bcl-2, Bcl-xL, and manganese superoxide dismutase in the rat heart, especially in the 3-72 group. PTP treatment significantly restored cardiac microcirculation, decreased oxidative stress, ER stress, apoptosis, autophagy, and infarct size. PTP significantly reduced cardiac ischemia/reperfusion injury by upregulating antioxidant, antiapoptotic, and antiautophagic mechanisms. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Can intravoxel incoherent motion diffusion-weighted imaging characterize the cellular injury and microcirculation alteration in hepatic ischemia-reperfusion injury? An animal study.

PubMed

Ye, Weitao; Li, Jinglei; Guo, Chengwei; Chen, Shuting; Liu, Yu-Bao; Liu, Zaiyi; Wu, Haijun; Wang, Guangyi; Liang, Changhong

2016-06-01

To investigate whether intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) can be used to quantitatively analyze the cellular injury and microcirculation alterations in hepatic ischemia-reperfusion injury (HIRI). Thirty-two New Zealand white rabbits were randomly and equally assigned to the sham group, 1-hour, 4-hour, and 12-hour groups according to the reperfusion time after 1 hour of ischemia using a 70% liver ischemia-reperfusion injury model. All the animals underwent IVIM-DWI with 12 b values at 1.5T. The imaging parameters (IVIM parameters and apparent diffusion coefficient [ADC]) among different groups were compared. The correlations between imaging parameters and histological scores, and the ratio of serum aspartate aminotransferase to serum alanine aminotransferase (serum AST/ALT) were analyzed. During the first hour of HIRI, true diffusion coefficient (D) and ADC significantly decreased (P < 0.05), while there was no significant decrease in perfusion fraction (f) (P = 0.708). There was fair to good correlation between histological scores and f (rs  = -0.493 with the sham cases excluded, and -0.682 with all cases, both P < 0.05) and ADC (rs  = -0.479 with the sham cases excluded, and -0.766 with all cases, both P < 0.05). There was no correlation between imaging parameters and serum AST/ALT with the sham cases excluded (P = 0.673 for f, 0.568 for D, 0.403 for ADC), and good correlation between D, ADC, and serum AST/ALT (r = 0.747 and 0.748, both P < 0.001) with all cases. IVIM-DWI can quantitatively characterize an animal model of HIRI, with D and ADC sensitive in early detection of cellular injury, as well as fair to good correlation between f, ADC, and microcirculation alteration. J. Magn. Reson. Imaging 2016;43:1327-1336. © 2015 Wiley Periodicals, Inc.

Analyzing Structure and Function of Vascularization in Engineered Bone Tissue by Video-Rate Intravital Microscopy and 3D Image Processing.

PubMed

Pang, Yonggang; Tsigkou, Olga; Spencer, Joel A; Lin, Charles P; Neville, Craig; Grottkau, Brian

2015-10-01

Vascularization is a key challenge in tissue engineering. Three-dimensional structure and microcirculation are two fundamental parameters for evaluating vascularization. Microscopic techniques with cellular level resolution, fast continuous observation, and robust 3D postimage processing are essential for evaluation, but have not been applied previously because of technical difficulties. In this study, we report novel video-rate confocal microscopy and 3D postimage processing techniques to accomplish this goal. In an immune-deficient mouse model, vascularized bone tissue was successfully engineered using human bone marrow mesenchymal stem cells (hMSCs) and human umbilical vein endothelial cells (HUVECs) in a poly (D,L-lactide-co-glycolide) (PLGA) scaffold. Video-rate (30 FPS) intravital confocal microscopy was applied in vitro and in vivo to visualize the vascular structure in the engineered bone and the microcirculation of the blood cells. Postimage processing was applied to perform 3D image reconstruction, by analyzing microvascular networks and calculating blood cell viscosity. The 3D volume reconstructed images show that the hMSCs served as pericytes stabilizing the microvascular network formed by HUVECs. Using orthogonal imaging reconstruction and transparency adjustment, both the vessel structure and blood cells within the vessel lumen were visualized. Network length, network intersections, and intersection densities were successfully computed using our custom-developed software. Viscosity analysis of the blood cells provided functional evaluation of the microcirculation. These results show that by 8 weeks, the blood vessels in peripheral areas function quite similarly to the host vessels. However, the viscosity drops about fourfold where it is only 0.8 mm away from the host. In summary, we developed novel techniques combining intravital microscopy and 3D image processing to analyze the vascularization in engineered bone. These techniques have broad applicability for evaluating vascularization in other engineered tissues as well.

Endothelial glycocalyx dysfunction in disease: albuminuria and increased microvascular permeability.

PubMed

Salmon, Andrew H J; Satchell, Simon C

2012-03-01

Appreciation of the glomerular microcirculation as a specialized microcirculatory bed, rather than as an entirely separate entity, affords important insights into both glomerular and systemic microvascular pathophysiology. In this review we compare regulation of permeability in systemic and glomerular microcirculations, focusing particularly on the role of the endothelial glycocalyx, and consider the implications for disease processes. The luminal surface of vascular endothelium throughout the body is covered with endothelial glycocalyx, comprising surface-anchored proteoglycans, supplemented with adsorbed soluble proteoglycans, glycosaminoglycans and plasma constituents. In both continuous and fenestrated microvessels, this endothelial glycocalyx provides resistance to the transcapillary escape of water and macromolecules, acting as an integral component of the multilayered barrier provided by the walls of these microvessels (ie acting in concert with clefts or fenestrae across endothelial cell layers, basement membranes and pericytes). Dysfunction of any of these capillary wall components, including the endothelial glycocalyx, can disrupt normal microvascular permeability. Because of its ubiquitous nature, damage to the endothelial glycocalyx alters the permeability of multiple capillary beds: in the glomerulus this is clinically apparent as albuminuria. Generalized damage to the endothelial glycocalyx can therefore manifest as both albuminuria and increased systemic microvascular permeability. This triad of altered endothelial glycocalyx, albuminuria and increased systemic microvascular permeability occurs in a number of important diseases, such as diabetes, with accumulating evidence for a similar phenomenon in ischaemia-reperfusion injury and infectious disease. The detection of albuminuria therefore has implications for the function of the microcirculation as a whole. The importance of the endothelial glycocalyx for other aspects of vascular function/dysfunction, such as mechanotransduction, leukocyte-endothelial interactions and the development of atherosclerosis, indicate that alterations in the endothelial glycocalyx may also be playing a role in the dysfunction of other organs observed in these disease states. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

[Effect of extracts from Dendrobii ifficinalis flos on hyperthyroidism Yin deficiency mice].

PubMed

Lei, Shan-shan; Lv, Gui-yuan; Jin, Ze-wu; Li, Bo; Yang, Zheng-biao; Chen, Su-hong

2015-05-01

Some unhealthy life habits, such as long-term smoking, heavy drinking, sexual overstrain and frequent stay-up could induce the Yin deficiency symptoms of zygomatic red and dysphoria. Stems of Dendrobii officinalis flos (DOF) showed the efficacy of nourishing Yin. In this study, the hyperthyroidism Yin deficiency model was set up to study the yin nourishing effect and action mechanism of DOF, in order to provide the pharmacological basis for developing DOF resources and decreasing resource wastes. ICR mice were divided into five groups: the normal control group, the model control group, the positive control group and DOF extract groups (6.4 g · kg(-1)). Except for the normal group, the other groups were administrated with thyroxine for 30 d to set up the hyperthyroidism yin deficiency model. At the same time, the other groups were administrated with the corresponding drugs for 30 d. After administration for 4 weeks, the signs (facial temperature, pain domain, heart rate and autonomic activity) in mice were measured, and the facial and ear micro-circulation blood flow were detected by laser Doppler technology. After the last administration, all mice were fasted for 12 hours, blood were collected from their orbits, and serum were separated to detect AST, ALT, TG and TP by the automatic biochemistry analyzer and test T3, T4 and TSH levels by ELISA. (1) Compared with the normal control group, the model control group showed significant increases in facial and ear micro-circulation blood flow, facial temperature and heart rate (P < 0.05, P < 0.01), serum AST, ALT (P < 0.01), T3 level (P < 0.05), TSH level (P < 0.05) and notable deceases in pain domain (P < 0.01), TG level (P < 0.01). (2) Compared with the model control group, extracts from DOF (6 g · kg(-1)) could notably reduce facial and ear micro-circulation blood flow, facial temperature and heart rate (P < 0.05, P < 0.01) and AST (P < 0.05) and enhance pain domain (P < 0.01) and TG (P < 0.01). Extracts from DOF (4 g · kg(-1)) could remarkably reduce AST and ALT levels (P < 0.01, 0.05). Extracts from DOF (6 g · kg(-1) 4 g · kg(-1)) could significantly reduce T3 and increase serum TSH level (P < 0.05). DOF could improve Yin deficiency symptoms of zygomatic red and dysphoria in mice as well as liver function injury caused by overactive thyroid axis. According to its action mechanism, DOF may show yin nourishing and hepatic protective effects by impacting thyroxin substance metabolism, improving micro-circulation and reducing heart rate.

Double layers in expanding plasmas and their relevance to the auroral plasma processes

NASA Astrophysics Data System (ADS)

Singh, Nagendra; Khazanov, George

2003-04-01

When a dense plasma consisting of a cold and a sufficiently warm electron population expands, a rarefaction shock forms [, 1978]. In the expansion of the polar wind in the magnetosphere, it has been previously shown that when a sufficiently warm electron population also exists, in addition to the usual cold ionospheric one, a discontinuity forms in the electrostatic potential distribution along the magnetic field lines [, 1984]. Despite the lack of spatial resolution and the assumption of quasi-neutrality in the polar wind models, such discontinuities have been called double layers (DLs). Recently similar discontinuities have been invoked to partly explain the auroral acceleration of electrons and ions in the upward current region [, 2000]. By means of one-dimensional Vlasov simulations of expanding plasmas, for the first time we make here the connection between (1) the rarefaction shocks, (2) the discontinuities in the potential distributions, and (3) DLs. We show that when plasmas expand from opposite directions into a deep density cavity with a potential drop across it and when the plasma on the high-potential side contains hot and cold electron populations, the temporal evolution of the potential and the plasma distribution generates evolving multiple double layers with an extended density cavity between them. One of the DLs is the rarefaction-shock (RFS) and it forms by the reflections of the cold electrons coming from the high-potential side; it supports a part of the potential drop approximately determined by the hot electron temperature. The other DLs evolve from charge separations arising either from reflection of ions coming from the low-potential side or stemming from plasma instabilities; they support the rest of the potential drop. The instabilities forming these additional double layers involve electron-ion (e-i) Buneman or ion-ion (i-i) two-stream interactions. The electron-electron two-stream interactions on the high-potential side of the RFS generate electron-acoustic waves, which evolve into electron phase-space holes. The ion population originating from the low-potential side and trapped by the RFS is energized by the e-i and i-i instabilities and it eventually precipitates into the high-potential plasma along with an electron beam. Applications of these findings to the auroral plasma physics are discussed.

Double Layers in Expanding Plasmas and Their Relevance to the Auroral Plasma Processes

NASA Technical Reports Server (NTRS)

Singh, Nagendra; Khazanov, George

2003-01-01

When a dense plasma consisting of a cold and a sufficiently warm electron population expands, a rarefaction shock forms [Bezzerides et al., 1978]. In the expansion of the polar wind in the magnetosphere, it has been previously shown that when a sufficiently warm electron population also exists, in addition to the usual cold ionospheric one, a discontinuity forms in the electrostatic potential distribution along the magnetic field lines [Barakat and Schunk, 1984]. Despite the lack of spatial resolution and the assumption of quasi-neutrality in the polar wind models, such discontinuities have been called double layers (DLs). Recently similar discontinuities have been invoked to partly explain the auroral acceleration of electrons and ions in the upward current region [Ergun et al., 2000]. By means of one-dimensional Vlasov simulations of expanding plasmas, for the first time we make here the connection between (1) the rarefaction shocks, (2) the discontinuities in the potential distributions, and (3) DLs. We show that when plasmas expand from opposite directions into a deep density cavity with a potential drop across it and when the plasma on the high-potential side contains hot and cold electron populations, the temporal evolution of the potential and the plasma distribution generates evolving multiple double layers with an ,extended density cavity between them. One of the DLs is the rarefaction-shock (RFS) and it forms by the reflections of the cold electrons coming from the high-potential side; it supports a part of the potential drop approximately determined by the hot electron temperature. The other DLs evolve from charge separations arising either from reflection of ions coming from the low-potential side or stemming from plasma instabilities; they support the rest of the potential drop. The instabilities forming these additional double layers involve electron-ion (e-i) Buneman or ion-ion (i-i) two-stream interactions. The electron-electron two-stream interactions on the high-potential side of the RFS generate electron-acoustic waves, which evolve into electron phase-space holes. The ion population originating from the low-potential side and trapped by the RFS is energized by the e-i and i-i instabilities and it eventually precipitates into the high-potential plasma along with an electron beam. Applications of these findings to the auroral plasma physics are discussed.

Rarefaction-driven Rayleigh–Taylor instability. Part 2. Experiments and simulations in the nonlinear regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, R. V.; Cabot, W. H.; Greenough, J. A.

Experiments and large eddy simulation (LES) were performed to study the development of the Rayleigh–Taylor instability into the saturated, nonlinear regime, produced between two gases accelerated by a rarefaction wave. Single-mode two-dimensional, and single-mode three-dimensional initial perturbations were introduced on the diffuse interface between the two gases prior to acceleration. The rarefaction wave imparts a non-constant acceleration, and a time decreasing Atwood number,more » $$A=(\\unicode[STIX]{x1D70C}_{2}-\\unicode[STIX]{x1D70C}_{1})/(\\unicode[STIX]{x1D70C}_{2}+\\unicode[STIX]{x1D70C}_{1})$$, where$$\\unicode[STIX]{x1D70C}_{2}$$and$$\\unicode[STIX]{x1D70C}_{1}$$are the densities of the heavy and light gas, respectively. Experiments and simulations are presented for initial Atwood numbers of$A=0.49$$,$$A=0.63$$,$$A=0.82$$and$$A=0.94$$. Nominally two-dimensional (2-D) experiments (initiated with nearly 2-D perturbations) and 2-D simulations are observed to approach an intermediate-time velocity plateau that is in disagreement with the late-time velocity obtained from the incompressible model of Goncharov (Phys. Rev. Lett., vol. 88, 2002, 134502). Reacceleration from an intermediate velocity is observed for 2-D bubbles in large wavenumber,$$k=2\\unicode[STIX]{x03C0}/\\unicode[STIX]{x1D706}=0.247~\\text{mm}^{-1}$$, experiments and simulations, where$$\\unicode[STIX]{x1D706}$is the wavelength of the initial perturbation. At moderate Atwood numbers, the bubble and spike velocities approach larger values than those predicted by Goncharov’s model. These late-time velocity trends are predicted well by numerical simulations using the LLNL Miranda code, and by the 2009 model of Mikaelian (Phys. Fluids., vol. 21, 2009, 024103) that extends Layzer type models to variable acceleration and density. Large Atwood number experiments show a delayed roll up, and exhibit a free-fall like behaviour. Finally, experiments initiated with three-dimensional perturbations tend to agree better with models and a simulation using the LLNL Ares code initiated with an axisymmetric rather than Cartesian symmetry.« less

Rarefaction-driven Rayleigh–Taylor instability. Part 2. Experiments and simulations in the nonlinear regime

DOE PAGES

Morgan, R. V.; Cabot, W. H.; Greenough, J. A.; ...

2018-01-12

Experiments and large eddy simulation (LES) were performed to study the development of the Rayleigh–Taylor instability into the saturated, nonlinear regime, produced between two gases accelerated by a rarefaction wave. Single-mode two-dimensional, and single-mode three-dimensional initial perturbations were introduced on the diffuse interface between the two gases prior to acceleration. The rarefaction wave imparts a non-constant acceleration, and a time decreasing Atwood number,more » $$A=(\\unicode[STIX]{x1D70C}_{2}-\\unicode[STIX]{x1D70C}_{1})/(\\unicode[STIX]{x1D70C}_{2}+\\unicode[STIX]{x1D70C}_{1})$$, where$$\\unicode[STIX]{x1D70C}_{2}$$and$$\\unicode[STIX]{x1D70C}_{1}$$are the densities of the heavy and light gas, respectively. Experiments and simulations are presented for initial Atwood numbers of$A=0.49$$,$$A=0.63$$,$$A=0.82$$and$$A=0.94$$. Nominally two-dimensional (2-D) experiments (initiated with nearly 2-D perturbations) and 2-D simulations are observed to approach an intermediate-time velocity plateau that is in disagreement with the late-time velocity obtained from the incompressible model of Goncharov (Phys. Rev. Lett., vol. 88, 2002, 134502). Reacceleration from an intermediate velocity is observed for 2-D bubbles in large wavenumber,$$k=2\\unicode[STIX]{x03C0}/\\unicode[STIX]{x1D706}=0.247~\\text{mm}^{-1}$$, experiments and simulations, where$$\\unicode[STIX]{x1D706}$is the wavelength of the initial perturbation. At moderate Atwood numbers, the bubble and spike velocities approach larger values than those predicted by Goncharov’s model. These late-time velocity trends are predicted well by numerical simulations using the LLNL Miranda code, and by the 2009 model of Mikaelian (Phys. Fluids., vol. 21, 2009, 024103) that extends Layzer type models to variable acceleration and density. Large Atwood number experiments show a delayed roll up, and exhibit a free-fall like behaviour. Finally, experiments initiated with three-dimensional perturbations tend to agree better with models and a simulation using the LLNL Ares code initiated with an axisymmetric rather than Cartesian symmetry.« less

Hemorheological changes, the state of microcirculation, and blood acid-base balance in rats under conditions of a 30-day limiting of the motor activity

NASA Technical Reports Server (NTRS)

Shtykhno, Y. M.; Udovichenko, V. I.

1980-01-01

Changes were expressed in reduction in number of true capillaries, the appearance of nonfunctioning empty vessels and in the opening of the arteriolo-venular shunts. Changes in the acid-base balance in the direction of reduction of buffer blood content were also noted.

Instability of a Planar Expansion Wave

DTIC Science & Technology

2005-10-11

Israel 3E. T. S. I. Industriales , Universidad de Castilla-La Mancha, 13071 Cuidad Real, Spain Received 18 March 2005; published 11 October 2005 An...modulation amplitude m=dx. As first shown in 3, for ideal gases with moderate values of , like 5 3 or 7 5 , m in a rippled rarefaction wave exhibits...radiating gases . The accuracy of such approximation is beyond the scope of the present paper see 17 and refer- ences therein. A blast wave

Species richness in soil bacterial communities: a proposed approach to overcome sample size bias.

PubMed

Youssef, Noha H; Elshahed, Mostafa S

2008-09-01

Estimates of species richness based on 16S rRNA gene clone libraries are increasingly utilized to gauge the level of bacterial diversity within various ecosystems. However, previous studies have indicated that regardless of the utilized approach, species richness estimates obtained are dependent on the size of the analyzed clone libraries. We here propose an approach to overcome sample size bias in species richness estimates in complex microbial communities. Parametric (Maximum likelihood-based and rarefaction curve-based) and non-parametric approaches were used to estimate species richness in a library of 13,001 near full-length 16S rRNA clones derived from soil, as well as in multiple subsets of the original library. Species richness estimates obtained increased with the increase in library size. To obtain a sample size-unbiased estimate of species richness, we calculated the theoretical clone library sizes required to encounter the estimated species richness at various clone library sizes, used curve fitting to determine the theoretical clone library size required to encounter the "true" species richness, and subsequently determined the corresponding sample size-unbiased species richness value. Using this approach, sample size-unbiased estimates of 17,230, 15,571, and 33,912 were obtained for the ML-based, rarefaction curve-based, and ACE-1 estimators, respectively, compared to bias-uncorrected values of 15,009, 11,913, and 20,909.

Assessment of Local Biodiversity Loss in Uranium Mining-Tales And Its Projections On Global Scale

NASA Astrophysics Data System (ADS)

Sharshenova, D.; Zhamangulova, N.

2015-12-01

In Min-Kush, northern Kyrgyzstan there are 8 mining tales with an estimate of 1 961 000 tones of industrial Uranium. Local ecosystem services have declined rapidly. We analyzed a terrestrial assemblage database of Uranium mine-tale to quantify local biodiversity responses to land use and environmental changes. In the worst-affected habitats species richness reduced by 95.7%, total abundance by 60.9% and rarefaction-based richness by 72.5%. We estimate that, regional mountain ecosystem affected by this pressure reduced average within-sample richness (by 17.01%), total abundance (16.5%) and rarefaction-based richness (14.5%). Business-as-usual scenarios are the widely practiced in the region and moreover, due to economic constraints country can not afford any mitigation scenarios. We project that biodiversity loss and ecosystem service impairment will spread in the region through ground water, soil, plants, animals and microorganisms at the rate of 1km/year. Entire Tian-Shan mountain chain will be in danger within next 5-10 years. Our preliminary data shows that local people live in this area developed various forms of cancer, and the rate of premature death is as high as 40%. Strong international scientific and socio-economic partnership is needed to develop models and predictions.

Oblique propagation of solitary waves in weakly relativistic magnetized plasma with kappa distributed electrons in the presence of negative ions

NASA Astrophysics Data System (ADS)

Salmanpoor, H.; Sharifian, M.; Gholipour, S.; Borhani Zarandi, M.; Shokri, B.

2018-03-01

The oblique propagation of nonlinear ion acoustic solitary waves (solitons) in magnetized collisionless and weakly relativistic plasma with positive and negative ions and super thermal electrons has been examined by using reduced perturbation method to obtain the Korteweg-de Vries equation that admits an obliquely propagating soliton solution. We have investigated the effects of plasma parameters like negative ion density, electrons temperature, angle between wave vector and magnetic field, ions velocity, and k (spectral index in kappa distribution) on the amplitude and width of solitary waves. It has been found out that four modes exist in our plasma model, but the analysis of the results showed that only two types of ion acoustic modes (fast and slow) exist in the plasma and in special cases only one mode could be propagated. The parameters of plasma for these two modes (or one mode) determine which one is rarefactive and which one is compressive. The main parameter is negative ions density (β) indicating which mode is compressive or rarefactive. The effects of the other plasma parameters on amplitude and width of the ion acoustic solitary waves have been studied. The main conclusion is that the effects of the plasma parameters on amplitude and width of the solitary wave strongly depend on the value of the negative ion density.

The influence of superimposed DC current on electrical and spectroscopic characteristics of HiPIMS discharge

NASA Astrophysics Data System (ADS)

Zuo, Xiao; Chen, Rende; Liu, Jingzhou; Ke, Peiling; Wang, Aiying

2018-01-01

The electrical characteristics and spectroscopic properties have been comprehensively investigated in a DC superimposed high power impulse magnetron sputtering (DC-HiPIMS) deposition system in this paper. The influence of superimposed DC current on the variation of target and substrate current waveforms, active species and electron temperatures with pulse voltages are focused. The peak target currents in DC-HiPIMS are lower than in HiPIMS. The time scales of the two main discharge processes like ionization and gas rarefaction in DC-HiPIMS are analyzed. When the pulse voltage is higher than 600 V, the gas rarefaction effect becomes apparent. Overall, the ionization process is found to be dominant in the initial ˜100 μs during each pulse. The active species of Ar and Cr in DC-HiPIMS are higher than in HiPIMS unless that the pulse voltage reaches 900 V. However, the ionization degree in HiPIMS exceeds that in DC-HiPIMS at around 600 V. The electron temperature calculated by modified Boltzmann plot method based on corona model has a precipitous increase from 0.87 to 25.0 eV in HiPIMS, but varies mildly after the introduction of the superimposed DC current. Additionally, the current from plasma flowing to the substrate is improved when a DC current is superimposed with HiPIMS.

Instability analysis of cosmic viscoelastic gyro-gravitating clouds in the presence of dark matter

NASA Astrophysics Data System (ADS)

Karmakar, Pralay Kumar; Das, Papari

2017-08-01

A classical formalism for the weakly nonlinear instability analysis of a gravitating rotating viscoelastic gaseous cloud in the presence of gyratory dark matter is presented on the cosmic Jeans flat scales of space and time. The constituent neutral gaseous fluid (NGF) and dark matter fluid (DMF) are inter-coupled frictionally via mutual gravity alone. Application of standard nonlinear perturbation techniques over the complex gyro-gravitating clouds results in a unique conjugated pair of viscoelastic forced Burgers (VFB) equations. The VFB pair is conjointly twinned by correlational viscoelastic effects. There is no regular damping term here, unlike, in the conventional Burgers equation for the luminous (bright) matter solely. Instead, an interesting linear self-consistent derivative force-term naturalistically appears. A numerical illustrative platform is provided to reveal the micro-physical insights behind the weakly non-linear natural diffusive eigen-modes. It is fantastically seen that the perturbed NGF evolves as extended compressive solitons and compressive shock-like structures. In contrast, the perturbed DMF grows as rarefactive extended solitons and hybrid shocks. The latter is micro-physically composed of rarefactive solitons and compressive shocks. The consistency and reliability of the results are validated in the panoptic light of the existing reports based on the preeminent nonlinear advection-diffusion-based Burgers fabric. At the last, we highlight the main implications and non-trivial futuristic applications of the explored findings.

Experimental Characterization of Magnetogasdynamic Phenomena in Ultra-High Velocity Pulsed Plasma Jets

NASA Astrophysics Data System (ADS)

Loebner, Keith; Wang, Benjamin; Cappelli, Mark

2014-10-01

The formation and propagation of high velocity plasma jets in a pulsed, coaxial, deflagration-type discharge is examined experimentally. A sensitive, miniaturized, immersed probe array is used to map out magnetic flux density and associated radial current density as a function of time and axial position. This array is also used to probe the magnetic field gradient across the exit of the accelerator and in the jet formation region. Sensitive interferometry via a continuous-wave helium-neon laser source is used to probe the structure of the plasma jet over multiple chords and axial locations. A two dimensional plasma density gradient profile at an instant in time during jet formation is compiled via Shack-Hartmann wavefront sensor analysis. The qualitative characteristics of rarefaction and/or shock wave formation as a function of chamber back-pressure is examined via fast-framing ICCD imaging. These measurements are compared to existing resistive MHD simulations of the coaxial deflagration accelerator and the ensuing rarefaction jet that is expelled from the electrode assembly. The physical mechanisms governing the behavior of the discharge and the formation of these high energy density plasma jets are proposed and validated against both theoretical models and numerically simulated behavior. This research was conducted with Government support under and awarded by DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a.

An improved method to set significance thresholds for β diversity testing in microbial community comparisons.

PubMed

Gülay, Arda; Smets, Barth F

2015-09-01

Exploring the variation in microbial community diversity between locations (β diversity) is a central topic in microbial ecology. Currently, there is no consensus on how to set the significance threshold for β diversity. Here, we describe and quantify the technical components of β diversity, including those associated with the process of subsampling. These components exist for any proposed β diversity measurement procedure. Further, we introduce a strategy to set significance thresholds for β diversity of any group of microbial samples using rarefaction, invoking the notion of a meta-community. The proposed technique was applied to several in silico generated operational taxonomic unit (OTU) libraries and experimental 16S rRNA pyrosequencing libraries. The latter represented microbial communities from different biological rapid sand filters at a full-scale waterworks. We observe that β diversity, after subsampling, is inflated by intra-sample differences; this inflation is avoided in the proposed method. In addition, microbial community evenness (Gini > 0.08) strongly affects all β diversity estimations due to bias associated with rarefaction. Where published methods to test β significance often fail, the proposed meta-community-based estimator is more successful at rejecting insignificant β diversity values. Applying our approach, we reveal the heterogeneous microbial structure of biological rapid sand filters both within and across filters. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Fourth order difference methods for hyperbolic IBVP's

NASA Technical Reports Server (NTRS)

Gustafsson, Bertil; Olsson, Pelle

1994-01-01

Fourth order difference approximations of initial-boundary value problems for hyperbolic partial differential equations are considered. We use the method of lines approach with both explicit and compact implicit difference operators in space. The explicit operator satisfies an energy estimate leading to strict stability. For the implicit operator we develop boundary conditions and give a complete proof of strong stability using the Laplace transform technique. We also present numerical experiments for the linear advection equation and Burgers' equation with discontinuities in the solution or in its derivative. The first equation is used for modeling contact discontinuities in fluid dynamics, the second one for modeling shocks and rarefaction waves. The time discretization is done with a third order Runge-Kutta TVD method. For solutions with discontinuities in the solution itself we add a filter based on second order viscosity. In case of the non-linear Burger's equation we use a flux splitting technique that results in an energy estimate for certain different approximations, in which case also an entropy condition is fulfilled. In particular we shall demonstrate that the unsplit conservative form produces a non-physical shock instead of the physically correct rarefaction wave. In the numerical experiments we compare our fourth order methods with a standard second order one and with a third order TVD-method. The results show that the fourth order methods are the only ones that give good results for all the considered test problems.

[Mesenteric circulation evaluation during myocardial revascularization with different temperature modes of extracorporeal circulation].

PubMed

Iavorovskiĭ, A G; Novikova, O V; Aksel'rod, B A; Guleshov, V A; Amelina, M A; Bulganina, N A; Morozov, Iu A

2013-01-01

The Mesenteric blood circulation during myocardium revasculization was investigated 40 patients were divided in 2 groups: 1st group - normothermia CPB, 2nd group hypothermia CPB. It was found that reduced mesenteric perfusion occurred in both groups, but it was more pronounced in hypothermia CPB group and was caused by a significant deterioration of the microcirculation.

Systemic and Microvascular Effects of Resuscitation with Blood Products After Severe Hemorrhage in Rats

DTIC Science & Technology

2014-01-01

thickness, blood flow, and microvascular permeability were studied using intravital microscopy. Hemodynamics and coagulation tests (rotational...Microcirculation; packed red blood cells; intravital microscopy; ROTEM; plasma proteins; rats. Current US military guidance for the resuscitation of warfighters...was used for coagulation assays (rotational thromboelast- ometry [ROTEM], TEM Innovations GmbH, Germany). Intravital Microscopy and Animal Preparation

Study of toxic properties of prototypes of photo inactivated vaccines against tularemia and brucellosis by speckle microscopy

NASA Astrophysics Data System (ADS)

Ulianova, Onega V.; Ulyanov, Sergey

2010-10-01

Testing of prototypes of vaccines against extremely dangerous diseases, such as tularemia and brucellosis has been performed using speckle-microscopy. Changes of microcirculation caused by effect of toxins at applications of suspension of photoinactivated bacteria have been studied. Toxic properties of prototypes of vaccines against tularemia and brucellosis have been analyzed.

Study of toxic properties of prototypes of photo inactivated vaccines against tularemia and brucellosis by speckle microscopy

NASA Astrophysics Data System (ADS)

Ulianova, Onega V.; Ulyanov, Sergey

2011-03-01

Testing of prototypes of vaccines against extremely dangerous diseases, such as tularemia and brucellosis has been performed using speckle-microscopy. Changes of microcirculation caused by effect of toxins at applications of suspension of photoinactivated bacteria have been studied. Toxic properties of prototypes of vaccines against tularemia and brucellosis have been analyzed.

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

PubMed Central

Kazmi, S. M. Shams; Balial, Satyajit; Dunn, Andrew K.

2014-01-01

Improved Laser Speckle Contrast Imaging (LSCI) blood flow analyses that incorporate inverse models of the underlying laser-tissue interaction have been used to develop more quantitative implementations of speckle flowmetry such as Multi-Exposure Speckle Imaging (MESI). In this paper, we determine the optimal camera exposure durations required for obtaining flow information with comparable accuracy with the prevailing MESI implementation utilized in recent in vivo rodent studies. A looping leave-one-out (LOO) algorithm was used to identify exposure subsets which were analyzed for accuracy against flows obtained from analysis with the original full exposure set over 9 animals comprising n = 314 regional flow measurements. From the 15 original exposures, 6 exposures were found using the LOO process to provide comparable accuracy, defined as being no more than 10% deviant, with the original flow measurements. The optimal subset of exposures provides a basis set of camera durations for speckle flowmetry studies of the microcirculation and confers a two-fold faster acquisition rate and a 28% reduction in processing time without sacrificing accuracy. Additionally, the optimization process can be used to identify further reductions in the exposure subsets for tailoring imaging over less expansive flow distributions to enable even faster imaging. PMID:25071956

N-Acetylcysteine's Role in Sepsis and Potential Benefit in Patients With Microcirculatory Derangements.

PubMed

Chertoff, Jason

2018-02-01

To review the data surrounding the utility of N-acetylcysteine (NAC) in sepsis and identify areas needed for additional research. A review of articles describing the mechanisms of action and clinical use of NAC in sepsis. Despite many advances in critical care medicine, still as many as 50% of patients with septic shock die. Treatments thus far have focused on resuscitation and restoration of macrocirculatory targets in the early phases of sepsis, with less focus on microcirculatory dysfunction. N-acetylcysteine, due to its anti-inflammatory and antioxidative properties, has been readily investigated in sepsis and has yielded largely incongruous and disappointing results. In addition to its known anti-inflammatory and antioxidative roles, one underappreciated property of NAC is its ability to vasodilate the microcirculation and improve locoregional blood flow. Some investigators have sought to capitalize on this mechanism with promising results, as evidenced by microcirculatory vasodilation, improvements in regional blood flow and oxygen delivery, and reductions in lactic acidosis, organ failure, and mortality. In addition to its antioxidant and anti-inflammatory properties, N-acetylcysteine possesses vasodilatory properties that could benefit the microcirculation in sepsis. It is imperative that we investigate these properties to uncover NAC's full potential for benefit in sepsis.

Rheological effects of drag-reducing polymers improve cerebral blood flow and oxygenation after traumatic brain injury in rats.

PubMed

Bragin, Denis E; Kameneva, Marina V; Bragina, Olga A; Thomson, Susan; Statom, Gloria L; Lara, Devon A; Yang, Yirong; Nemoto, Edwin M

2017-03-01

Cerebral ischemia has been clearly demonstrated after traumatic brain injury (TBI); however, neuroprotective therapies have not focused on improvement of the cerebral microcirculation. Blood soluble drag-reducing polymers (DRP), prepared from high molecular weight polyethylene oxide, target impaired microvascular perfusion by altering the rheological properties of blood and, until our recent reports, has not been applied to the brain. We hypothesized that DRP improve cerebral microcirculation and oxygenation after TBI. DRP were studied in healthy and traumatized rat brains and compared to saline controls. Using in-vivo two-photon laser scanning microscopy over the parietal cortex, we showed that after TBI, nanomolar concentrations of intravascular DRP significantly enhanced microvascular perfusion and tissue oxygenation in peri-contusional areas, preserved blood-brain barrier integrity and protected neurons. The mechanisms of DRP effects were attributable to reduction of the near-vessel wall cell-free layer which increased near-wall blood flow velocity, microcirculatory volume flow, and number of erythrocytes entering capillaries, thereby reducing capillary stasis and tissue hypoxia as reflected by a reduction in NADH. Our results indicate that early reduction in CBF after TBI is mainly due to ischemia; however, metabolic depression of contused tissue could be also involved.

High quality optical microangiography of ocular microcirculation and measurement of total retinal blood flow in mouse eye

NASA Astrophysics Data System (ADS)

Zhi, Zhongwei; Yin, Xin; Dziennis, Suzan; Alpers, Charles E.; Wang, Ruikang K.

2013-03-01

Visualization and measurement of retinal blood flow (RBF) is important to the diagnosis and management of different eye diseases, including diabetic retinopathy. Optical microangiography (OMAG) is developed for generating 3D dynamic microcirculation image and later refined into ultra-high sensitive OMAG (UHS-OMAG) for true capillary vessels imaging. Here, we present the application of OMAG imaging technique for visualization of depth-resolved vascular network within retina and choroid as well as measurement of total retinal blood flow in mice. A fast speed spectral domain OCT imaging system at 820nm with a line scan rate of 140 kHz was developed to image mouse posterior eye. By applying UHS-OMAG scanning protocol and processing algorithm, we achieved true capillary level imaging of retina and choroid vasculature in mouse eye. The vascular pattern within different retinal layers and choroid was presented. An en face Doppler OCT approach [1] without knowing Doppler angle was adopted for the measurement of total retinal blood flow. The axial blood flow velocity is measured in an en face plane by raster scanning and the flow is calculated by integrating over the vessel area of the central retinal artery.

Skeletal muscle fiber, nerve, and blood vessel breakdown in space-flown rats

NASA Technical Reports Server (NTRS)

Riley, D. A.; Ilyina-Kakueva, E. I.; Ellis, S.; Bain, J. L.; Slocum, G. R.; Sedlak, F. R.

1990-01-01

Histochemical and ultrastructural analyses were performed postflight on hind limb skeletal muscles of rats orbited for 12.5 days aboard the unmanned Cosmos 1887 biosatellite and returned to Earth 2 days before sacrifice. The antigravity adductor longus (AL), soleus, and plantaris muscles atrophied more than the non-weight-bearing extensor digitorum longus, and slow muscle fibers were more atrophic than fast fibers. Muscle fiber segmental necrosis occurred selectively in the AL and soleus muscles; primarily, macrophages and neutrophils infiltrated and phagocytosed cellular debris. Granule-rich mast cells were diminished in flight AL muscles compared with controls, indicating the mast cell secretion contributed to interstitial tissue edema. Increased ubiquitination of disrupted myofibrils implicated ubiquitin in myofilament degradation. Mitochondrial content and succinic dehydrogenase activity were normal, except for subsarcolemmal decreases. Myofibrillar ATPase activity of flight AL muscle fibers shifted toward the fast type. Absence of capillaries and extravasation of red blood cells indicated failed microcirculation. Muscle fiber regeneration from activated satellite cells was detected. About 17% of the flight AL end plates exhibited total or partial denervation. Thus, skeletal muscle weakness associated with spaceflight can result from muscle fiber atrophy and segmental necrosis, partial motor denervation, and disruption of the microcirculation.

Two-photon NADH imaging exposes boundaries of oxygen diffusion in cortical vascular supply regions

PubMed Central

Kasischke, Karl A; Lambert, Elton M; Panepento, Ben; Sun, Anita; Gelbard, Harris A; Burgess, Robert W; Foster, Thomas H; Nedergaard, Maiken

2011-01-01

Oxygen transport imposes a possible constraint on the brain's ability to sustain variable metabolic demands, but oxygen diffusion in the cerebral cortex has not yet been observed directly. We show that concurrent two-photon fluorescence imaging of endogenous nicotinamide adenine dinucleotide (NADH) and the cortical microcirculation exposes well-defined boundaries of tissue oxygen diffusion in the mouse cortex. The NADH fluorescence increases rapidly over a narrow, very low pO2 range with a p50 of 3.4±0.6 mm Hg, thereby establishing a nearly binary reporter of significant, metabolically limiting hypoxia. The transient cortical tissue boundaries of NADH fluorescence exhibit remarkably delineated geometrical patterns, which define the limits of tissue oxygen diffusion from the cortical microcirculation and bear a striking resemblance to the ideal Krogh tissue cylinder. The visualization of microvessels and their regional contribution to oxygen delivery establishes penetrating arterioles as major oxygen sources in addition to the capillary network and confirms the existence of cortical oxygen fields with steep microregional oxygen gradients. Thus, two-photon NADH imaging can be applied to expose vascular supply regions and to localize functionally relevant microregional cortical hypoxia with micrometer spatial resolution. PMID:20859293

Two-photon NADH imaging exposes boundaries of oxygen diffusion in cortical vascular supply regions.

PubMed

Kasischke, Karl A; Lambert, Elton M; Panepento, Ben; Sun, Anita; Gelbard, Harris A; Burgess, Robert W; Foster, Thomas H; Nedergaard, Maiken

2011-01-01

Oxygen transport imposes a possible constraint on the brain's ability to sustain variable metabolic demands, but oxygen diffusion in the cerebral cortex has not yet been observed directly. We show that concurrent two-photon fluorescence imaging of endogenous nicotinamide adenine dinucleotide (NADH) and the cortical microcirculation exposes well-defined boundaries of tissue oxygen diffusion in the mouse cortex. The NADH fluorescence increases rapidly over a narrow, very low pO(2) range with a p(50) of 3.4 ± 0.6 mm Hg, thereby establishing a nearly binary reporter of significant, metabolically limiting hypoxia. The transient cortical tissue boundaries of NADH fluorescence exhibit remarkably delineated geometrical patterns, which define the limits of tissue oxygen diffusion from the cortical microcirculation and bear a striking resemblance to the ideal Krogh tissue cylinder. The visualization of microvessels and their regional contribution to oxygen delivery establishes penetrating arterioles as major oxygen sources in addition to the capillary network and confirms the existence of cortical oxygen fields with steep microregional oxygen gradients. Thus, two-photon NADH imaging can be applied to expose vascular supply regions and to localize functionally relevant microregional cortical hypoxia with micrometer spatial resolution.

Assessment of muscle tissue oxygen saturation after out-of-hospital cardiac arrest.

PubMed

Orban, Jean-Christophe; Scarlatti, Audrey; Danin, Pierre-Eric; Dellamonica, Jean; Bernardin, Gilles; Ichai, Carole

2015-12-01

Pathophysiology of cardiac arrest corresponds to an ischemia-reperfusion syndrome with deep impairment of microcirculation. Muscular tissue oxygen saturation (StO2) is a noninvasive method of evaluation of microcirculation. Our study was aimed at assessing the prognosis value of muscular StO2 in patients admitted for out-of-hospital cardiac arrest (OHCA) and treated with hypothermia. We conducted a prospective bicentric observational study including OHCA patients treated with therapeutic hypothermia. Baseline StO2, derived variables (desaturation and resaturation slopes), and lactate levels were compared at different times between patients with good and poor outcomes. Prognosis was assessed by the Cerebral Performance Category (CPC) score at 6 months after admission (CPC 1-2, good outcome; CPC 3-5, poor outcome). Forty-four patients were included, 17 good and 27 poor outcomes at 6 months. At admission, StO2 and lactate levels were lower in good outcome patients. Desaturation and resaturation slopes did not differ between groups. After an OHCA treated with therapeutic hypothermia, StO2 was correlated with outcome. Further research is needed to better understand the pathophysiological process underlying our results. Copyright © 2015 Elsevier Inc. All rights reserved.

[Investigation of postconditioning in intestinal ischemia-reperfusion experimental models].

PubMed

Rosero, Olivér; Onody, Péter; Stangl, Rita; Hegedus, Viktor; Lotz, Gábor; Blázovics, Anna; Kupcsulik, Péter; Szijártó, Attila

2011-02-01

The ischemic-reperfusion injury of the intestine, which occurs as a consequence of circulatory redistribution or occlusion of the superior mesenteric artery, is associated with high mortality rates. Postconditioning may reduce ischemic-reperfusion damage in such cases. Effects of this new surgical method were investigated in rats. Male Wistar rats underwent 60 minutes of superior mesenteric artery occlusion in four groups: sham-operated, control and two postconditioned groups with different algorithms. Postconditioning was performed immediately at the beginning of reperfusion, by repetitive cycles of reperfusion and reocclusion. 3 cycles of 1 minute and 6 cycles of 10 seconds were applied according to groups. Intestinal microcirculation was followed by laser Doppler flowmetry. Blood and tissue samples were taken after 60 minutes of reperfusion. Histological analayses of the small intestine, measurement of serum necroenzyme levels and IL-6, mesenterial venous blood gas analyses were preformed and antioxidant state of the mucosa was investigated. The microcirculation during the reperfusion showed significant improvement in both postconditioned groups. Histological damage, necroenzyme and IL-6 levels were significantly reduced, while antioxidant state was improved in the postconditioned groups. Postconditioning was capable of increasing the guts chance to survive ischemic-reperfusion injury caused by superior mesenteric artery occlusion.

The rationale for microcirculatory guided fluid therapy.

PubMed

Ince, Can

2014-06-01

The ultimate purpose of fluid administration in states of hypovolemia is to correct cardiac output to improve microcirculatory perfusion and tissue oxygenation. Observation of the microcirculation using handheld microscopes gives insight into the nature of convective and diffusive defect in hypovolemia. The purpose of this article is to introduce a new platform for hemodynamic-targeted fluid therapy based on the correction of tissue and microcirculatory perfusion assumed to be at risk during hypovolemia. Targeting systemic hemodynamic targets and/or clinical surrogates of hypovolemia gives inadequate guarantee for the correction of tissue perfusion by fluid therapy especially in conditions of distributive shock as occur in inflammation and sepsis. Findings are presented, which support the idea that only clinical signs of hypovolemia associated with low microcirculatory flow can be expected to benefit from fluid therapy and that fluid overload causes a defect in the diffusion of oxygen transport. We hypothesized that the optimal amount of fluid needed for correction of hypovolemia is defined by a physiologically based functional microcirculatory hemodynamic platform where convection and diffusion need to be optimized. Future clinical trials using handheld microscopes able to automatically evaluate the microcirculation at the bedside will show whether such a platform will indeed optimize fluid therapy.

Assessment of microcirculation dynamics during cutaneous wound healing phases in vivo using optical microangiography

PubMed Central

Yousefi, Siavash; Qin, Jia; Dziennis, Suzan; Wang, Ruikang K.

2014-01-01

Abstract. Cutaneous wound healing consists of multiple overlapping phases starting with blood coagulation following incision of blood vessels. We utilized label-free optical coherence tomography and optical microangiography (OMAG) to noninvasively monitor healing process and dynamics of microcirculation system in a mouse ear pinna wound model. Mouse ear pinna is composed of two layers of skin separated by a layer of cartilage and because its total thickness is around 500 μm, it can be utilized as an ideal model for optical imaging techniques. These skin layers are identical to human skin structure except for sweat ducts and glands. Microcirculatory system responds to the wound injury by recruiting collateral vessels to supply blood flow to hypoxic region. During the inflammatory phase, lymphatic vessels play an important role in the immune response of the tissue and clearing waste from interstitial fluid. In the final phase of wound healing, tissue maturation, and remodeling, the wound area is fully closed while blood vessels mature to support the tissue cells. We show that using OMAG technology allows noninvasive and label-free monitoring and imaging each phase of wound healing that can be used to replace invasive tissue sample histology and immunochemistry technologies. PMID:25036212

[Contrast-enhanced ultrasound in animal models].

PubMed

Paprottka, P M; Zengel, P; Ingrisch, M; Cyran, C C; Eichhorn, M; Reiser, M F; Nikolaou, K; Clevert, D-A

2011-06-01

In the past the detection of tumor perfusion was achieved solely via invasive procedures, such as intravital microscopy or with the help of costly modalities, such as multidetector computed tomography (MDCT), magnetic resonance tomography (MRT) or the combined use of positron emission tomography and computed tomography (PET/CT). Ultrasound offers the non-invasive display of organs without usage of ionizing radiation and it is widely available. However, colour-coded ultrasound and power Doppler do not allow the detection of tumor microcirculation. The introduction of contrast-enhanced ultrasound (CEUS) as well as new high-frequency ultrasound probes made it possible to detect and quantify tumor microcirculation with high resolution. CEUS has been used clinically on human beings for more than 10 years. During the last years different tumor models in experimental animals were used for the establishment of this new technique, e.g. in rats, hamsters and mice. CEUS allows the detection of functional parameters, such as the angiogenetic metabolic status of tissue pretreatment and posttreatment. Further research is required to solve the problems of absolute quantification of these perfusion parameters to allow the comparison of CEUS with other modalities (e.g. MRT and CT).

Betahistine metabolites, aminoethylpyridine, and hydroxyethylpyridine increase cochlear blood flow in guinea pigs in vivo.

PubMed

Bertlich, Mattis; Ihler, Fritz; Sharaf, Kariem; Weiss, Bernhard G; Strupp, Michael; Canis, Martin

2014-10-01

Betahistine is a histamine-like drug that is used in the treatment of Ménière's disease. It is commonly believed that betahistine increases cochlear blood flow and thus decreases the endolymphatic hydrops that is the cause of Ménière's. Despite common clinical use, there is little understanding of the kinetics or effects of its metabolites. This study investigated the effect of the betahistine metabolites aminoethylpyridine, hydroxyethylpyridine, and pyridylacetic acid on cochlear microcirculation. Guinea pigs were randomly assigned to one of the groups: placebo, betahistine, or equimolar amounts of aminoethylpyridine, hydroxyethylpyridine, or pyridylacetic acid. Cochlear blood flow and mean arterial pressure were recorded for three minutes before and 15 minutes after treatment. Thirty Dunkin-Hartley guinea pigs assigned to one of five groups with six guinea pigs per group. Betahistine, aminoethylpyridine, and hydroxyethylpyridine caused a significant increase in cochlear blood flow in comparison to placebo. The effect seen under aminoethylpyridin was greatest. The group treated with pyridylacetic acid showed no significant effect on cochlear blood flow. Aminoethylpyridine and hydroxyethylpyridine are, like betahistine, able to increase cochlear blood flow significantly. The effect of aminoethylpyridine was greatest. Pyridylacetic acid had no effect on cochlear microcirculation.

Acute hyperfibrinogenemia impairs cochlear blood flow and hearing function in guinea pigs in vivo.

PubMed

Ihler, Fritz; Strieth, Sebastian; Pieri, Nicos; Göhring, Peter; Canis, Martin

2012-03-01

Impairment of microcirculation is a possible cause of sudden sensorineural hearing loss (SSNHL). Fibrinogen is known as a risk factor for both microvascular dysfunction and SSNHL. Therefore, the aim of this study was to investigate the effect of elevated serum levels of fibrinogen on cochlear blood flow and hearing function in vivo. One group of guinea pigs received two consecutive injections of 100 mg fibrinogen while a control group received equimolar doses of albumin. Measurements of cochlear microcirculation by intravital microscopy and of hearing thresholds by auditory brainstem response (ABR) recordings were carried out before, after first and after second injection. Ten healthy guinea pigs were randomly assigned to a treatment group or a control group of five animals each. Serum fibrinogen levels were elevated after the first and second injections of fibrinogen compared to basal values and control group respectively. Increasing levels of fibrinogen were paralleled by decreasing cochlear blood flow as well as increasing hearing thresholds. Hearing threshold correlated negatively with cochlear blood flow. The effect of microcirculatory impairment on hearing function could be explained by a malfunction of the cochlear amplifier. Further investigation is needed to quantify cochlear potentials under elevated serum fibrinogen levels.

EASApprox® skin-stretching system: A secure and effective method to achieve wound closure.

PubMed

Song, Mingzhi; Zhang, Zhen; Liu, Tao; Liu, Song; Li, Gang; Liu, Zhaochang; Huang, Jingyang; Chen, Song; Li, Linan; Guo, Li; Qiu, Yang; Wan, Jiajia; Liu, Yuejian; Wu, Tao; Wang, Xiaoyong; Lu, Ming; Wang, Shouyu

2017-07-01

Large skin defects are commonly observed in the clinic and have attracted much attention recently. Therefore, finding an effective solution for large skin defects is a global problem. The objective of the present study was to assess the effectiveness of the EASApprox ® skin-stretching system for closing large skin defects. Skin defects (5×5 cm) were created on the forearms of 9 Bama miniature pigs, which were randomly divided into the following three groups: Direct suture, the new EASApprox ® skin-stretching device and Kirschner wires. Microcirculation was assessed before surgery and after wound closure. Following the different treatments, the defects were sutured, and wound healing was assessed based on a clinical score. Furthermore, microscopic and ultramicroscopic structures were evaluated, including collagen, elastic fibers and the microvessel density. Significant differences in the clinical score and microvessel density were observed among the groups. Additionally, the mean length obtained for elastic fibers was larger than that obtained for the other two groups. Finally, the new EASApprox ® skin-stretching device resulted in successful wound management and with only minor side effects on skin histology and microcirculation. Therefore, this method has the potential to be used for healing large skin defects.

In vivo functional photoacoustic microscopy of cutaneous microvasculature in human skin.

PubMed

Favazza, Christopher P; Cornelius, Lynn A; Wang, Lihong V

2011-02-01

Microcirculation is an important component of the cardiovascular system and can be used to assess systemic cardiovascular health. Numerous studies have investigated cutaneous microcirculation as an indicator of cardiovascular related diseases. Such research has shown promising results; however, there are many limitations regarding the employed measurement techniques, such as poor depth and spatial resolution and measurement versatility. Here we show the results of functional cutaneous microvascular experiments measured with photoacoustic microscopy, which provides high spatial resolution and multiparameter measurements. In a set of experiments, microvascular networks located in the palms of volunteers were perturbed by periodic ischemic events, and the subsequent hemodynamic response to the stimulus was recorded. Results indicate that during periods of arterial occlusion, the relative oxygen saturation of the capillary vessels decreased below resting levels, and temporarily increased above resting levels immediately following the occlusion. Furthermore, a hyperemic reaction to the occlusions was measured, and the observation agreed well with similar measurements using more conventional imaging techniques. Due to its exceptional capability to functionally image vascular networks with high spatial resolution, photoacoustic microscopy could be a beneficial biomedical tool to assess microvascular functioning and applied to patients with diseases that affect cardiovascular health. © 2011 Society of Photo-Optical Instrumentation Engineers.

Processing and interpretation of experiments in the microwave interferometry of shock waves in a weakly ionized plasma

NASA Astrophysics Data System (ADS)

Ershov, A. P.; Klishin, S. V.; Kuzovnikov, S. V.; Ponomareva, S. E.; Pyt'ev, Iu. P.

1990-12-01

The reduction method is applied to the microwave interferometry of shock waves in a weakly ionized plasma, making it possible to improve the spatial resolution of the instrument. It is shown experimentally that the structure of the shock wave electron component in a high-frequency discharge plasma in atomic and molecular gases is characterized by the presence of a precursor in the form of a rarefaction wave. The origin of the precursor is examined.

Proceedings of the Scientific Conference on Obscuration and Aerosol Research Held in Aberdeen Proving Ground, Maryland on 21-24 June 1988

DTIC Science & Technology

1989-06-01

fragmentation threshold power , can be determined by integrating the volumetric heating rate over time for each spatial position within the droplet. Since in...unless the heat is supplied at the shock surface. On the other hand, the rarefaction wave conditions rely upon adiabaticity along the stream line...the role 12 of entrainment in replenishing depleted supplies of oxidants. Figures 8 and 9 show the distribution with Z of L/LA and N respectively for

On real statistics of relaxation in gases

NASA Astrophysics Data System (ADS)

Kuzovlev, Yu. E.

2016-02-01

By example of a particle interacting with ideal gas, it is shown that the statistics of collisions in statistical mechanics at any value of the gas rarefaction parameter qualitatively differ from that conjugated with Boltzmann's hypothetical molecular chaos and kinetic equation. In reality, the probability of collisions of the particle in itself is random. Because of that, the relaxation of particle velocity acquires a power-law asymptotic behavior. An estimate of its exponent is suggested on the basis of simple kinematic reasons.

Mach Cones in a Coulomb Lattice and a Dusty Plasma

NASA Astrophysics Data System (ADS)

Samsonov, D.; Goree, J.; Ma, Z. W.; Bhattacharjee, A.; Thomas, H. M.; Morfill, G. E.

1999-11-01

Mach cones, or V-shaped disturbances created by supersonic objects, have been detected in a two-dimensional Coulomb crystal. Electrically charged microspheres levitated in a glow-discharge plasma formed a dusty plasma, with particles arranged in a hexagonal lattice in a horizontal plane. Beneath this lattice plane, a sphere moved faster than the lattice sound speed. Mach cones were double, first compressive then rarefactive, due to the strongly coupled crystalline state. Molecular dynamics simulations using a Yukawa potential also show multiple Mach cones.

Elementary wave interactions in blood flow through artery

NASA Astrophysics Data System (ADS)

Raja Sekhar, T.; Minhajul

2017-10-01

In this paper, we consider the Riemann problem and interaction of elementary waves for the quasilinear hyperbolic system of conservation laws that arises in blood flow through arteries. We study the properties of solution involving shocks and rarefaction waves and establish the existence and uniqueness conditions. We show that the Riemann problem is solvable for arbitrary initial data under certain condition and construct the condition for no-feasible solution. Finally, we present numerical examples with different initial data and discuss all possible interactions of elementary waves.

Pathophysiology of spontaneous venous gas embolism

NASA Technical Reports Server (NTRS)

Lambertsen, C. J.; Albertine, K. H.; Pisarello, J. B.; Flores, N. D.

1991-01-01

The use of controllable degrees and durations of continuous isobaric counterdiffusion venous gas embolism to investigate effects of venous gas embolism upon blood, cardiovascular, and respiratory gas exchange function, as well as pathological effects upon the lung and its microcirculation is discussed. Use of N2O/He counterdiffusion permitted performance of the pathophysiologic and pulmonary microstructural effects at one ATA without hyperbaric or hypobaric exposures.

Local fluid shifts and edema in humans during simulated microgravity

NASA Technical Reports Server (NTRS)

Hargens, Alan R.

1991-01-01

Local fluid shifts and edema in humans during simulated microgravity is studied. Recent results and significance and future plans on the following research topics are discussed: mechanisms of headward edema formation during head-down tilt; postural responses of head and foot microcirculations and their sensitivity to bed rest; and transcapillary fluid transport associated with lower body negative pressure (LBNP) with and without saline ingestion.

Laser Doppler assessment of dermal circulatory changes in people with coronary artery disease.

PubMed

Agarwal, Sharad C; Allen, John; Murray, Alan; Purcell, Ian F

2012-07-01

Dermal microcirculation provides an easily accessible vasculature bed which can be used to assess endothelial mediated vasodilatation. We studied and compared microcirculatory changes in response to acetylcholine iontophoresis (ACh), local heating of the skin and reactive hyperaemia in patients with coronary artery disease (CAD). Forty eight patients with CAD were studied and compared with 25 age and sex matched control subjects. Vasodilatory changes in the dermal microcirculation were assessed in response to ACh iontophoresis, local heating of the skin and reactive hyperaemia using a laser Doppler flowmeter (LDF). Body mass index (BMI) and systolic BP were higher in people with CAD, (p=0.001, 0.043). The perfusion change (measured as absolute in agreement with our previous publish results) in response to ACh iontophoresis, local heating of the skin and reactive hyperaemia, in healthy controls was 234 (190-286), 90 (69-118), 139(106-172) arbitrary perfusion units (APU) compared to 161 (121-214), 50 (39-63), 116(77-143) APU in patients with CAD; p<0.03. The time to peak perfusion in response to reactive hyperaemia was significantly higher in patients with CAD, 14.1±4.0 vs 10.9±1.7s; p=0.001. There was a small but significant positive correlation between the perfusion change in response to ACh iontophoresis and local heating (r=0.31, p=0.035). On ROC curve analysis, perfusion changes with heating had higher sensitivity and specificity in discriminating patients with CAD from the healthy controls with an area under the curve (AUC) of 0.86, with a specificity of 92% and sensitivity of 77% compared to a perfusion changes by reactive hyperaemia, AUC of 0.68 (41% sensitivity and 91% specificity) and ACh iontophoresis, AUC of 0.76 (88% sensitivity and 60% specificity). Vasodilatation in the dermal microcirculation measured by the three techniques is attenuated in patients with coronary artery disease. Local heating of the skin is a better discriminator of patients with CAD than ACh iontophoresis and reactive hyperaemia. Copyright © 2012 Elsevier Inc. All rights reserved.

Transmission of arterial oxygen partial pressure oscillations to the cerebral microcirculation in a porcine model of acute lung injury caused by cyclic recruitment and derecruitment.

PubMed

Klein, K U; Boehme, S; Hartmann, E K; Szczyrba, M; Heylen, L; Liu, T; David, M; Werner, C; Markstaller, K; Engelhard, K

2013-02-01

Cyclic recruitment and derecruitment (R/D) play a key role in the pathomechanism of acute lung injury (ALI) leading to respiration-dependent oscillations of arterial partial pressure of oxygen (Pa(O(2))). These Pa(O(2)) oscillations could also be forwarded to the cerebral microcirculation. In 12 pigs, partial pressure of oxygen was measured in the thoracic aorta (Pa(O(2))) and subcortical cerebral tissue (Pbr(O(2))). Cerebral cortical haemoglobin oxygen saturation (Sbr(O(2))), cerebral blood flow (CBF), and peripheral haemoglobin saturation (Sp(O(2))) were assessed by spectroscopy and laser Doppler flowmetry. Measurements at different fractions of inspired oxygen (F(I(O(2)))) were performed at baseline and during cyclic R/D. frequency domain analysis, the Mann-Whitney test, linear models to test the influence of Pa(O(2)) and systolic arterial pressure (SAP) oscillations on cerebral measurements. Parameters [mean (SD)] remained stable during baseline. Pa(O(2)) oscillations [10.6 (8) kPa, phase(reference)], systemic arterial pressure (SAP) oscillations [20 (9) mm Hg, phase(Pa(O(2))-SAP) -33 (72)°], and Sp(O(2))oscillations [1.9 (1.7)%, phase(Pa(O(2))-Sp(O(2))) 264 (72)°] were detected during lung R/D at 1.0. Pa(O(2)) oscillations decreased [2.7 (3.5) kPa, P=0.0008] and Sp(O(2)) oscillations increased [6.8 (3.9)%, P=0.0014] at F(I(O(2))) 0.3. In the brain, synchronized Pbr(O(2)) oscillations [0.6 (0.4) kPa, phase(Pa(O(2))-Pbr(O(2))) 90 (39)°], Sbr(O(2)) oscillations [4.1 (1.5)%, phase(Pa(O(2))-Sbr(O(2))) 182 (54)°], and CBF oscillations [198 (176) AU, phase(Pa(O(2))-CBF) 201 (63)°] occurred that were dependent on Pa(O(2)) and SAP oscillations. Pa(O(2)) oscillations caused by cyclic R/D are transmitted to the cerebral microcirculation in a porcine model of ALI. These cyclic oxygen alterations could play a role in the crosstalk of acute lung and brain injury.

Microvascular perfusion during focal vasogenic brain edema: a scanning laser fluorescence microscopy study.

PubMed

Lindsberg, P J; Sirén, A L; Hallenbeck, J M

1997-01-01

Controversy exists about the effect of tissue edema on cerebral microcirculation. High spatial resolution is required for observation of extravasation and microcirculation during focal vasogenic edema formation. To study the relationship between tissue edema and perfusion, we developed a technique for simultaneous visualization of extravasation and microvessel perfusion in rats. Focal intracortical microvascular injury was generated with a 1-sec Nd-YAG laser pulse. Evans blue albumin (EBA) was infused 30 min before decapitation to study extravasation and FITC-dextran was injected 30 sec prior to decapitation to examine microvessel perfusion. Computerized scanning laser-excited fluorescence microscopy followed by high resolution image analysis permitted quantitative assessment of both parameters on single fresh-frozen brain sections. Studied at 30 min (3.66 +/- 0.15 mm), 2 hr (4.14 +/- 0.08 mm, P < .05), and 8 hr (4.69 +/- 0.18 mm, P < .01) after injury, the diameter of the circular, sharply demarcated zone of EBA-extravasation increased progressively. At 30 min, microvessels at a zone surrounding the area of EBA-extravasation contained 69 +/- 14% (P < .05) more fluorescent FITC-filling than in the control hemisphere, but the density of perfused microvessels was unchanged. At 2 hr, secondary tissue changes had already occurred in a zone surrounding the initial laser lesion. While severe reduction in the density (-76 +/- 13%, P < .05) of perfused microvessels was observed within 400 to 240 microm inside the border of EBA extravasation, perfusion indexes were normal despite the presence of extravasated plasma constituents within 0-80 microm from the border. In a narrow zone (80 microm) outside the border of extravasation, individual microvessels contained 34 +/- 9% (P < .01) less FITC-fluorescence than those in a homologous area of the uninjured contralateral hemisphere. This report demonstrates the feasibility of simultaneous measurement and high-resolution mapping of indices of microvascular perfusion (density, filling) and extravasated plasma constituents in damaged and intact brain areas. In this model, the presence of extravasated plasma constituents the size of proteins did not immediately influence indices of cortical microcirculation. However, microvascular perfusion may be perturbed surrounding such an area of advancing vasogenic edema formation.

Study of the functional state of peripheral vessels in fingers of rheumatological patients by means of laser Doppler flowmetry and cutaneous thermometry measurements

NASA Astrophysics Data System (ADS)

Zherebtsova, Angelina I.; Zherebtsov, Evgeny A.; Dunaev, Andrey V.; Podmasteryev, Konstantin V.; Pilipenko, Olga V.; Krupatkin, Alexander I.; Khakhicheva, Lyudmila S.; Muradyan, Vadim F.

2016-04-01

Vasospastic disorders are a common class of rheumatic disease. These include syndromes such as vegetative dystonia, Raynaud's syndrome, vibration disease and rheumatoid arthritis among others. The aim of this work is to develop an original method of diagnosing the functional state of peripheral vessels of the fingers, based on the simultaneous recording of LDF- and thermograms during the occlusion test, for determining vascular disorders of rheumatological patients. A diagnostic method was developed for assessing the functional state of the peripheral vessels of fingers, based on carrying out occlusion test in a thermally stabilized environment, with simultaneous recording of signals of laser Doppler flowmetry and skin thermometry. To verify the diagnostic value of the proposed method, a series of experiments were carried out on 41 rheumatological patients: 5 male and 36 females (average age 56.0+/-12.2 years). The most common diagnoses in the patient group were rheumatoid arthritis, arthrosis, gout and systemic lupus erythematosus. The laser analyser of blood microcirculation "LAKK-02" (SPE "LAZMA" Ltd, Russia) and a custom developed multi-channel thermometry device for low inertia thermometry were used for experimental measurements. The measurements of cutaneous temperature and the index of microcirculation were performed on the distal phalanx of the third finger of the right hand. Occlusion tests were performed with water baths at 25 and 42 °C and a tonometer cuff with a pressure of 200-220 mmHg for 3 min on the upper arm. The results of experimental studies are presented and interpreted. These data indicate a violation of the blood supply regulation in the form of a pronounced tendency towards microvascular vasoconstriction in the fingers. Thus, the response displaying a tendency toward angiospasm among patients in the rheumatological diseases profile group was observed mainly in the most severe cases (49 % of this group). The prospects of the developed diagnostic method of microcirculatory disorders in rheumatic diseases are evaluated. Thus, cutaneous blood microcirculation and temperature measurements performed together can help in diagnosis of the functional state of peripheral vessels both in a healthy state and when expressing pathology.

Aging-induced dysregulation of dicer1-dependent microRNA expression impairs angiogenic capacity of rat cerebromicrovascular endothelial cells.

PubMed

Ungvari, Zoltan; Tucsek, Zsuzsanna; Sosnowska, Danuta; Toth, Peter; Gautam, Tripti; Podlutsky, Andrej; Csiszar, Agnes; Losonczy, Gyorgy; Valcarcel-Ares, M Noa; Sonntag, William E; Csiszar, Anna

2013-08-01

Age-related impairment of angiogenesis is likely to play a central role in cerebromicrovascular rarefaction and development of vascular cognitive impairment, but the underlying mechanisms remain elusive. To test the hypothesis that dysregulation of Dicer1 (ribonuclease III, a key enzyme of the microRNA [miRNA] machinery) impairs endothelial angiogenic capacity in aging, primary cerebromicrovascular endothelial cells (CMVECs) were isolated from young (3 months old) and aged (24 months old) Fischer 344 × Brown Norway rats. We found an age-related downregulation of Dicer1 expression both in CMVECs and in small cerebral vessels isolated from aged rats. In aged CMVECs, Dicer1 expression was increased by treatment with polyethylene glycol-catalase. Compared with young cells, aged CMVECs exhibited altered miRNA expression profile, which was associated with impaired proliferation, adhesion to vitronectin, collagen and fibronectin, cellular migration (measured by a wound-healing assay using electric cell-substrate impedance sensing technology), and impaired ability to form capillary-like structures. Overexpression of Dicer1 in aged CMVECs partially restored miRNA expression profile and significantly improved angiogenic processes. In young CMVECs, downregulation of Dicer1 (siRNA) resulted in altered miRNA expression profile associated with impaired proliferation, adhesion, migration, and tube formation, mimicking the aging phenotype. Collectively, we found that Dicer1 is essential for normal endothelial angiogenic processes, suggesting that age-related dysregulation of Dicer1-dependent miRNA expression may be a potential mechanism underlying impaired angiogenesis and cerebromicrovascular rarefaction in aging.

The role of trapped bubbles in kidney stone detection with the color Doppler ultrasound twinkling artifact.

PubMed

Simon, Julianna C; Sapozhnikov, Oleg A; Kreider, Wayne; Breshock, Michael; Williams, James C; Bailey, Michael R

2018-01-09

The color Doppler ultrasound twinkling artifact, which highlights kidney stones with rapidly changing color, has the potential to improve stone detection; however, its inconsistent appearance has limited its clinical utility. Recently, it was proposed stable crevice bubbles on the kidney stone surface cause twinkling; however, the hypothesis is not fully accepted because the bubbles have not been directly observed. In this paper, the micron or submicron-sized bubbles predicted by the crevice bubble hypothesis are enlarged in kidney stones of five primary compositions by exposure to acoustic rarefaction pulses or hypobaric static pressures in order to simultaneously capture their appearance by high-speed photography and ultrasound imaging. On filming stones that twinkle, consecutive rarefaction pulses from a lithotripter caused some bubbles to reproducibly grow from specific locations on the stone surface, suggesting the presence of pre-existing crevice bubbles. Hyperbaric and hypobaric static pressures were found to modify the twinkling artifact; however, the simple expectation that hyperbaric exposures reduce and hypobaric pressures increase twinkling by shrinking and enlarging bubbles, respectively, largely held for rough-surfaced stones but was inadequate for smoother stones. Twinkling was found to increase or decrease in response to elevated static pressure on smooth stones, perhaps because of the compression of internal voids. These results support the crevice bubble hypothesis of twinkling and suggest the kidney stone crevices that give rise to the twinkling phenomenon may be internal as well as external.

The role of trapped bubbles in kidney stone detection with the color Doppler ultrasound twinkling artifact

NASA Astrophysics Data System (ADS)

Simon, Julianna C.; Sapozhnikov, Oleg A.; Kreider, Wayne; Breshock, Michael; Williams, James C., Jr.; Bailey, Michael R.

2018-01-01

The color Doppler ultrasound twinkling artifact, which highlights kidney stones with rapidly changing color, has the potential to improve stone detection; however, its inconsistent appearance has limited its clinical utility. Recently, it was proposed stable crevice bubbles on the kidney stone surface cause twinkling; however, the hypothesis is not fully accepted because the bubbles have not been directly observed. In this paper, the micron or submicron-sized bubbles predicted by the crevice bubble hypothesis are enlarged in kidney stones of five primary compositions by exposure to acoustic rarefaction pulses or hypobaric static pressures in order to simultaneously capture their appearance by high-speed photography and ultrasound imaging. On filming stones that twinkle, consecutive rarefaction pulses from a lithotripter caused some bubbles to reproducibly grow from specific locations on the stone surface, suggesting the presence of pre-existing crevice bubbles. Hyperbaric and hypobaric static pressures were found to modify the twinkling artifact; however, the simple expectation that hyperbaric exposures reduce and hypobaric pressures increase twinkling by shrinking and enlarging bubbles, respectively, largely held for rough-surfaced stones but was inadequate for smoother stones. Twinkling was found to increase or decrease in response to elevated static pressure on smooth stones, perhaps because of the compression of internal voids. These results support the crevice bubble hypothesis of twinkling and suggest the kidney stone crevices that give rise to the twinkling phenomenon may be internal as well as external.

Indirect genetic estimates of breeding population size in the polyploid green sturgeon (Acipenser medirostris).

PubMed

Israel, J A; May, B

2010-03-01

The utility of genetic measures for kinship reconstruction in polysomic species is not well evaluated. We developed a framework to test hypotheses about estimating breeding population size indirectly from collections of outmigrating green sturgeon juveniles. We evaluated a polysomic dataset, in allelic frequency and phenotypic formats, from green sturgeon to describe the relationship among known progeny from experimental families. The distributions of relatedness values for kin classes were used for reconstructing green sturgeon pedigrees from juveniles of unknown relationship. We compared three rarefaction functions that described the relationship between the number of kin groups and number of samples in a pedigree to estimate the annual abundance of spawners contributing to the threatened green sturgeon Southern Distinct Population Segment in the upper Sacramento River. Results suggested the estimated abundance of breeding green sturgeon remained roughly constant in the upper Sacramento River over a 5-year period, ranging from 10 to 28 individuals depending on the year and rarefaction method. These results demonstrate an empirical understanding for the distribution of relatedness values among individuals is a benefit for assessing pedigree reconstruction methods and identifying misclassification rates. Monitoring of rare species using these indirect methods is feasible and can provide insight into breeding and ontogenetic behaviour. While this framework was developed for specific application to studying fish populations in a riverscape, the framework could be advanced to improve genetic estimation of breeding population size and to identify important breeding habitats of rare species when combined with finer-scaled sampling of offspring.

Modelling of the reactive sputtering process with non-uniform discharge current density and different temperature conditions

NASA Astrophysics Data System (ADS)

Vašina, P; Hytková, T; Eliáš, M

2009-05-01

The majority of current models of the reactive magnetron sputtering assume a uniform shape of the discharge current density and the same temperature near the target and the substrate. However, in the real experimental set-up, the presence of the magnetic field causes high density plasma to form in front of the cathode in the shape of a toroid. Consequently, the discharge current density is laterally non-uniform. In addition to this, the heating of the background gas by sputtered particles, which is usually referred to as the gas rarefaction, plays an important role. This paper presents an extended model of the reactive magnetron sputtering that assumes the non-uniform discharge current density and which accommodates the gas rarefaction effect. It is devoted mainly to the study of the behaviour of the reactive sputtering rather that to the prediction of the coating properties. Outputs of this model are compared with those that assume uniform discharge current density and uniform temperature profile in the deposition chamber. Particular attention is paid to the modelling of the radial variation of the target composition near transitions from the metallic to the compound mode and vice versa. A study of the target utilization in the metallic and compound mode is performed for two different discharge current density profiles corresponding to typical two pole and multipole magnetics available on the market now. Different shapes of the discharge current density were tested. Finally, hysteresis curves are plotted for various temperature conditions in the reactor.

The fluid-dynamic paradigm of the dust-acoustic soliton

NASA Astrophysics Data System (ADS)

McKenzie, J. F.

2002-06-01

In most studies, the properties of dust-acoustic solitons are derived from the first integral of the Poisson equation, in which the shape of the pseudopotential determines both the conditions in which a soliton may exist and its amplitude. Here this first integral is interpreted as conservation of total momentum, which, along with the Bernoulli-like energy equations for each species, may be cast as the structure equation for the dust (or heavy-ion) speed in the wave. In this fluid-dynamic picture, the significance of the sonic points of each species becomes apparent. In the wave, the heavy-ion (or dust) flow speed is supersonic (relative to its sound speed), whereas the protons and electrons are subsonic (relative to their sound speeds), and the dust flow is driven towards its sonic point. It is this last feature that limits the strength (amplitude) of the wave, since the equilibrium point (the centre of the wave) must be reached before the dust speed becomes sonic. The wave is characterized by a compression in the heavies and a compression (rarefaction) in the electrons and a rarefaction (compression) in the protons if the heavies have positive (negative) charge, and the corresponding potential is a hump (dip). These features are elucidated by an exact analytical soliton, in a special case, which provides the fully nonlinear counterpoint to the weakly nonlinear sech2-type solitons associated with the Korteweg de Vries equation, and indicates the parameter regimes in which solitons may exist.

Regional and latitudinal patterns of soft-bottom macrobenthic invertebrates along French coasts: Results from the RESOMAR database

NASA Astrophysics Data System (ADS)

Gallon, Régis K.; Lavesque, Nicolas; Grall, Jacques; Labrune, Céline; Gremare, Antoine; Bachelet, Guy; Blanchet, Hugues; Bonifácio, Paulo; Bouchet, Vincent M. P.; Dauvin, Jean-Claude; Desroy, Nicolas; Gentil, Franck; Guerin, Laurent; Houbin, Céline; Jourde, Jérôme; Laurand, Sandrine; Le Duff, Michel; Le Garrec, Vincent; de Montaudouin, Xavier; Olivier, Frédéric; Orvain, Francis; Sauriau, Pierre-Guy; Thiebaut, Éric; Gauthier, Olivier

2017-12-01

This study aims to describe the patterns of soft bottom macrozoobenthic richness along French coasts. It is based on a collaborative database developed by the "Réseau des Stations et Observatoires Marins" (RESOMAR). We investigated patterns of species richness in sublittoral soft bottom habitats (EUNIS level 3) at two different spatial scales: 1) seaboards: English Channel, Bay of Biscay and Mediterranean Sea and 2) 0.5° latitudinal and longitudinal grid. Total observed richness, rarefaction curves and three incidence-based richness estimators (Chao2, ICE and Jacknife1) were used to compare soft bottom habitats species richness in each seaboard. Overall, the Mediterranean Sea has the highest richness and despite higher sampling effort, the English Channel hosts the lowest number of species. The distribution of species occurrence within and between seaboards was assessed for each major phylum using constrained rarefaction curves. The Mediterranean Sea hosts the highest number of exclusive species. In pairwise comparisons, it also shares a lower proportion of taxa with the Bay of Biscay (34.1%) or the English Channel (27.6%) than that shared between these two seaboards (49.7%). Latitudinal species richness patterns along the Atlantic and English Channel coasts were investigated for each major phylum using partial LOESS regression controlling for sampling effort. This showed the existence of a bell-shaped latitudinal pattern, highlighting Brittany as a hotspot for macrobenthic richness at the confluence of two biogeographic provinces.

Nonlinear eigen-structures in star-forming gyratory nonthermal complex molecular clouds

NASA Astrophysics Data System (ADS)

Karmakar, Pralay Kumar; Dutta, Pranamika

2018-01-01

This paper deals with the nonlinear gravito-electrostatic fluctuations in star-forming rotating complex partially ionized dust molecular clouds, evolutionarily well-governed by a derived pair of the Korteweg-de Vries (KdV) equations of a unique analytical shape, in a bi-fluidic-model fabric. The lighter constituent species, such as electrons and ions, are considered thermo-statistically as the nonthermal ones in nature, governed by the anti-equilibrium kappa-distribution laws, due to inherent nonlocal gradient effects stemming from large-scale inhomogeneity. The heavier species, such as the constitutive identical neutral and charged dust micro-spheres, are treated as separate turbulent viscous fluids in the Larson logatropic tapestry. Application of a standard technique of multiple scale analysis over the nonlinearly perturbed cloud procedurally yields the pair KdV system. It comprises of the gravitational KdV and electrostatic KdV equations with exclusive constructs of diversified multi-parametric coefficients. A numerical constructive platform is provided to see the excitation and propagatory dynamics of gravitational rarefactive periodic soliton-trains and electrostatic rarefactive aperiodic damped soliton-trains of distinctive patterns as the pair-KdV-supported discrete coherent eigen-mode structures illustratively. The varied key stabilizing and tonality destabilizing factors behind the cloud dynamics are identified. An elaborated contrast of the eigen-mode conjugacy is reconnoitered. The main implications and applications of the semi-analytical results explored here are summarily outlined in the real astro-space-cosmic statuses.

Pulsatile pressure driven rarefied gas flow in long rectangular ducts

NASA Astrophysics Data System (ADS)

Tsimpoukis, Alexandros; Valougeorgis, Dimitris

2018-04-01

The pulsatile pressure driven fully developed flow of a rarefied gas through an orthogonal duct is investigated, based on the time-dependent linear Bhatnagar, Gross, and Krook equation, by decomposing the flow into its steady and oscillatory parts. The investigation is focused on the oscillatory part, which is characterized by the gas rarefaction and oscillation parameters, the duct aspect ratio, and the accommodation coefficient. As the oscillation frequency is increased, the amplitude of all macroscopic quantities is decreased, while their phase angle lag is increased reaching the limiting value of π/2. As the gas becomes more rarefied, higher frequencies are needed to trigger this behavior. At small and moderate frequencies, there is a critical degree of gas rarefaction, where a maximum flow rate is obtained. As the duct aspect ratio is decreased and tends to zero, the flow rate and mean wall shear stress amplitudes are increased, while their phase angle lags are slightly affected. The accommodation coefficient has a significant effect on the amplitude and a very weak one on the phase angle of the macroscopic quantities. The computation of the inertia and viscous forces clarifies when the flow consists of only one oscillating viscous region or of two regions, namely, the inviscid piston flow in the core and the oscillating Stokes layer at the wall with the velocity overshooting. Finally, the time average oscillatory pumping power is increased as the oscillation frequency is reduced and its maximum value is one half of the corresponding steady one.

Blood Vessel Adaptation with Fluctuations in Capillary Flow Distribution

PubMed Central

Hu, Dan; Cai, David; Rangan, Aaditya V.

2012-01-01

Throughout the life of animals and human beings, blood vessel systems are continuously adapting their structures – the diameter of vessel lumina, the thickness of vessel walls, and the number of micro-vessels – to meet the changing metabolic demand of the tissue. The competition between an ever decreasing tendency of luminal diameters and an increasing stimulus from the wall shear stress plays a key role in the adaptation of luminal diameters. However, it has been shown in previous studies that the adaptation dynamics based only on these two effects is unstable. In this work, we propose a minimal adaptation model of vessel luminal diameters, in which we take into account the effects of metabolic flow regulation in addition to wall shear stresses and the decreasing tendency of luminal diameters. In particular, we study the role, in the adaptation process, of fluctuations in capillary flow distribution which is an important means of metabolic flow regulation. The fluctuation in the flow of a capillary group is idealized as a switch between two states, i.e., an open-state and a close-state. Using this model, we show that the adaptation of blood vessel system driven by wall shear stress can be efficiently stabilized when the open time ratio responds sensitively to capillary flows. As micro-vessel rarefaction is observed in our simulations with a uniformly decreased open time ratio of capillary flows, our results point to a possible origin of micro-vessel rarefaction, which is believed to induce hypertension. PMID:23029014

Effect of ion beam on the characteristics of ion acoustic Gardner solitons and double layers in a multicomponent superthermal plasma

NASA Astrophysics Data System (ADS)

Kaur, Nimardeep; Singh, Kuldeep; Saini, N. S.

2017-09-01

The nonlinear propagation of ion acoustic solitary waves (IASWs) is investigated in an unmagnetized plasma composed of a positive warm ion fluid, two temperature electrons obeying kappa type distribution and penetrated by a positive ion beam. The reductive perturbation method is used to derive the nonlinear equations, namely, Korteweg-de Vries (KdV), modified KdV (mKdV), and Gardner equations. The characteristic features of both compressive and rarefactive nonlinear excitations from the solution of these equations are studied and compared in the context with the observation of the He+ beam in the polar cap region near solar maximum by the Dynamics Explorer 1 satellite. It is observed that the superthermality and density of cold electrons, number density, and temperature of the positive ion beam crucially modify the basic properties of compressive and rarefactive IASWs in the KdV and mKdV regimes. It is further analyzed that the amplitude and width of Gardner solitons are appreciably affected by different plasma parameters. The characteristics of double layers are also studied in detail below the critical density of cold electrons. The theoretical results may be useful for the observation of nonlinear excitations in laboratory and ion beam driven plasmas in the polar cap region near solar maximum and polar ionosphere as well in Saturn's magnetosphere, solar wind, pulsar magnetosphere, etc., where the population of two temperature superthermal electrons is present.

Tissue Oxygenation Monitoring using Resonance Raman Spectroscopy during Hemorrhage

DTIC Science & Technology

2013-12-27

saturation measurements using resonance Raman intravital micros- copy. Am J Physiol Heart Circ Physiol. 2005;289:H488 H495. 14. Ward KR, Ivatury RR, Barbee...Nighswander-Rempel SP, Kupriyanov VV, Shaw RA. Relative contribu- tions of hemoglobin and myoglobin to near-infrared spectroscopic images of cardiac tissue...DC, Shapiro NI. The microcirculation image quality score: development and preliminary evaluation of a proposed approach to grading quality of image

Laser diagnostics in orthodontics

NASA Astrophysics Data System (ADS)

Ryzhkova, Anastasia V.; Lebedeva, Nina G.; Sedykh, Alexey V.; Ulyanov, Sergey S.; Lepilin, Alexander V.; Kharish, Natalia A.

2003-10-01

The results of statistical analysis of Doppler spectra of intensity fluctuations of light, scattered from mucose membrane of oral cavity of healthy volunteers and patients, abused by the orthodontic diseases, are presented. Analysis of Doppler spectra, obtained from tooth pulp of patients, is carried out. New approach to monitoring of blood microcirculation in orthodontics is suggested. Influence of own noise of measuring system on formation of the speckle-interferometric signal is studied.

Laser Doppler diagnostics for orthodontia

NASA Astrophysics Data System (ADS)

Ryzhkova, Anastasia V.; Lebedeva, Nina G.; Sedykh, Alexey V.; Ulyanov, Sergey S.; Lepilin, Alexander V.; Kharish, Natalia A.

2004-06-01

The results of statistical analysis of Doppler spectra of intensity fluctuations of light, scattered from mucous membrane of oral cavity of healthy volunteers and patients, abused by the orthodontic diseases, are presented. Analysis of Doppler spectra, obtained from tooth pulp of patients, is carried out. New approach to monitoring of blood microcirculation in orthodontics is suggested. Influence of own noise of Doppler measuring system on formation of the output signal is studied.

[Effect of complex sanatorium treatment including magnetotherapy on hemodynamics in patients with arterial hypertension].

PubMed

Efremushkin, G G; Duruda, N V

2003-01-01

Forty nine patients with arterial hypertension of stage I-II received combined sanatorium treatment. Of them, 21 had adjuvant total magnetotherapy. All the patients were examined for parameters of central, cerebral hemodynamics and microcirculation. The adjuvant magnetotherapy produced a beneficial effect on hypertension: clinical symptoms attenuated, arterial pressure became more stable, hemodynamics improved, duration of hospitalization reduced, requirement in hypotensive drugs diminished.

Assessing the evidence: Exploring the effects of exercise on diabetic microcirculation.

PubMed

Lenasi, Helena; Klonizakis, Markos

2016-01-01

Diabetes mellitus (DM) is associated with cardiovascular complications. Impairment of glycemic control induces noxious glycations, an increase in oxydative stress and dearangement of various metabolic pathways. DM leads to dysfunction of micro- and macrovessels, connected to metabolic, endothelial and autonomic nervous system. Thus, assessing vascular reactivity might be one of the clinical tools to evaluate the impact of harmful effects of DM and potential benefit of treatment; skin and skeletal muscle microcirculation have usually been tested. Physical exercise improves vascular dysfunction through various mechanisms, and is regarded as an additional effective treatment strategy of DM as it positively impacts glycemic control, improves insulin sensitivity and glucose uptake in the target tissues, thus affecting glucose and lipid metabolism, and increases the endothelium dependent vasodilation. Yet, not all patients respond in the same way so titrating the exercise type individualy would be desirable. Resistance training has, apart from aerobic one, been shown to positively correlate to glycemic control, and improve vascular reactivity. It has been prescribed in various forms or in combination with aerobic training. This review would assess the impact of different modes of exercise, the mechanisms involved, and its potential positive and negative effects on treating patients with Type I and Type II DM, focusing on the recent literature.

Eye lens membrane junctional microdomains: a comparison between healthy and pathological cases

NASA Astrophysics Data System (ADS)

Buzhynskyy, Nikolay; Sens, Pierre; Behar-Cohen, Francine; Scheuring, Simon

2011-08-01

The eye lens is a transparent tissue constituted of tightly packed fiber cells. To maintain homeostasis and transparency of the lens, the circulation of water, ions and metabolites is required. Junctional microdomains connect the lens cells and ensure both tight cell-to-cell adhesion and intercellular flow of fluids through a microcirculation system. Here, we overview membrane morphology and tissue functional requirements of the mammalian lens. Atomic force microscopy (AFM) has opened up the possibility of visualizing the junctional microdomains at unprecedented submolecular resolution, revealing the supramolecular assembly of lens-specific aquaporin-0 (AQP0) and connexins (Cx). We compare the membrane protein assembly in healthy lenses with senile and diabetes-II cataract cases and novel data of the lens membranes from a congenital cataract. In the healthy case, AQP0s form characteristic square arrays confined by connexons. In the cases of senile and diabetes-II cataract patients, connexons were degraded, leading to malformation of AQP0 arrays and breakdown of the microcirculation system. In the congenital cataract, connexons are present, indicating probable non-membranous grounds for lens opacification. Further, we discuss the energetic aspects of the membrane organization in junctional microdomains. The AFM hence becomes a biomedical nano-imaging tool for the analysis of single-membrane protein supramolecular association in healthy and pathological membranes.

Rheological effects of drag-reducing polymers improve cerebral blood flow and oxygenation after traumatic brain injury in rats

PubMed Central

Kameneva, Marina V; Bragina, Olga A; Thomson, Susan; Statom, Gloria L; Lara, Devon A; Yang, Yirong; Nemoto, Edwin M

2016-01-01

Cerebral ischemia has been clearly demonstrated after traumatic brain injury (TBI); however, neuroprotective therapies have not focused on improvement of the cerebral microcirculation. Blood soluble drag-reducing polymers (DRP), prepared from high molecular weight polyethylene oxide, target impaired microvascular perfusion by altering the rheological properties of blood and, until our recent reports, has not been applied to the brain. We hypothesized that DRP improve cerebral microcirculation and oxygenation after TBI. DRP were studied in healthy and traumatized rat brains and compared to saline controls. Using in-vivo two-photon laser scanning microscopy over the parietal cortex, we showed that after TBI, nanomolar concentrations of intravascular DRP significantly enhanced microvascular perfusion and tissue oxygenation in peri-contusional areas, preserved blood–brain barrier integrity and protected neurons. The mechanisms of DRP effects were attributable to reduction of the near-vessel wall cell-free layer which increased near-wall blood flow velocity, microcirculatory volume flow, and number of erythrocytes entering capillaries, thereby reducing capillary stasis and tissue hypoxia as reflected by a reduction in NADH. Our results indicate that early reduction in CBF after TBI is mainly due to ischemia; however, metabolic depression of contused tissue could be also involved. PMID:28155574

Effect of Topical Iloprost and Nitroglycerin on Gastric Microcirculation and Barrier Function during Hemorrhagic Shock in Dogs.

PubMed

Truse, Richard; Hinterberg, Jonas; Schulz, Jan; Herminghaus, Anna; Weber, Andreas; Mettler-Altmann, Tabea; Bauer, Inge; Picker, Olaf; Vollmer, Christian

2017-01-01

Topical drug application is used to avoid systemic side effects. The aim of this study was to analyze whether locally applied iloprost or nitroglycerin influence gastric mucosal perfusion, oxygenation, and barrier function during physiological and hemorrhagic conditions. In repeated experiments, 5 anesthetized dogs received iloprost, nitroglycerin, or normal saline during physiological and hemorrhagic (-20% blood volume) conditions. Macro- and microcirculatory variables were recorded continuously. Gastric barrier function was assessed via translocation of sucrose into the blood. During hemorrhage, gastric mucosal oxygenation decreased from 77 ± 4 to 37 ± 7%. This effect was attenuated by nitroglycerin (78 ± 6 to 47 ± 13%) and iloprost (82 ± 4 to 54 ± 9%). Sucrose plasma levels increased during hemorrhage from 7 ± 4 to 55 ± 15 relative amounts. This was alleviated by nitroglycerin (5 ± 8 to 29 ± 38 relative amounts). These effects were independent of systemic hemodynamic variables. During hemorrhage, topical nitroglycerin and iloprost improve regional gastric oxygenation without affecting perfusion. Nitroglycerin attenuated the shock-induced impairment of the mucosal barrier integrity. Thus, local drug application improves gastric microcirculation without compromising systemic hemodynamic variables, and it may also protect mucosal barrier function. © 2017 S. Karger AG, Basel.

Age-related Changes in the Hepatic Microcirculation in Mice

PubMed Central

Ito, Yoshiya; Sørensen, Karen K.; Bethea, Nancy W.; Svistounov, Dmitri; McCuskey, Margaret K.; Smedsrød, Bård H.; McCuskey, Robert S.

2007-01-01

Aging of the liver is associated with impaired metabolism of drugs, adverse drug interactions, and susceptibility to toxins. Since reduced hepatic blood flow is suspected to contribute this impairment, we examined age-related alterations in hepatic microcirculation.. Livers of C57Bl/6 mice were examined at 0.8 (pre-pubertal), 3 (young adult), 14 (middle-aged) and 27 (senescent) months of age using in vivo and electron microscopic methods. The results demonstrated a 14% reduction in the numbers of perfused sinusoids between 0.8 and 27 month mice associated with 35% reduction in sinusoidal blood flow. This was accompanied by an inflammatory response evidenced by a 5-fold increase in leukocyte adhesion in 27 month mice, up-regulated expression of ICAM-1, and increases in intrahepatic macrophages. Sinusoidal diameter decreased 6-10%. Liver sinusoidal endothelial cell (LSEC) dysfunction was seen as early as 14 months when there was a 3-fold increase in the numbers of swollen LSEC. The endocytotic capacity of LSEC also was found to be reduced in older animals. The sinusoidal endothelium in 27 month old mice exhibited pseudocapillarization. In conclusion, the results suggest that leukocyte accumulation in the sinusoids and narrowing of sinusoidal lumens due to pseudocapillarization and dysfunction of LSEC reduce sinusoidal blood flow in aged livers. PMID:17582718

Milrinone attenuates arteriolar vasoconstriction and capillary perfusion deficits on endotoxemic hamsters.

PubMed

de Miranda, Marcos Lopes; Pereira, Sandra J; Santos, Ana O M T; Villela, Nivaldo R; Kraemer-Aguiar, Luiz Guilherme; Bouskela, Eliete

2015-01-01

Apart from its inotropic property, milrinone has vasodilator, anti-inflammatory and antithrombotic effects that could assist in the reversal of septic microcirculatory changes. This paper investigates the effects of milrinone on endotoxemia-related microcirculatory changes and compares them to those observed with the use of norepinephrine. After skinfold chamber implantation procedures and endotoxemia induction by intravenous Escherichia coli lipopolysaccharide administration (2 mg.kg-1), male golden Syrian hamsters were treated with two regimens of intravenous milrinone (0.25 or 0.5 μg.kg-1.min-1). Intravital microscopy of skinfold chamber preparations allowed quantitative analysis of microvascular variables. Macro-hemodynamic, biochemical, and hematological parameters and survival rate were also analyzed. Endotoxemic non-treated animals, endotoxemic animals treated with norepinephrine (0.2 μg.kg-1.min-1), and non-endotoxemic hamsters served as controls. Milrinone (0.5 μg.kg-1.min-1) was effective in reducing lipopolysaccharide-induced arteriolar vasoconstriction, capillary perfusion deficits, and inflammatory response, and in increasing survival. Norepinephrine treated animals showed the best mean arterial pressure levels but the worst functional capillary density values among all endotoxemic groups. Our data suggests that milrinone yielded protective effects on endotoxemic animals' microcirculation, showed anti-inflammatory properties, and improved survival. Norepinephrine did not recruit the microcirculation nor demonstrated anti-inflammatory effects.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reekers, Jim A., E-mail: j.a.reekers@amc.uva.nl; Koelemay, Mark J. W., E-mail: m.j.koelemaij@amc.uva.nl; Marquering, Henk A., E-mail: h.a.marquering@amc.uva.nl

PurposeTo report on the first clinical experience with perfusion angiography (PA) of the foot in patients with chronic critical limb ischemia.Materials and MethodsPA is a post-processing software algorithm and no extra digital subtraction angiography (DSA) has to be performed for this analysis. The data used to test the feasibility of PA were obtained from a consecutive group of 89 patients with CLI who were treated with standard below the knee angioplasty and 12 separate patients who were not suitable for endovascular revascularization.ResultsMotion artifacts in the dataset of the DSA made post-procedural analysis impossible in 10 % intervention. In the majority ofmore » patients (59/68) PA showed an increase in volume flow in the foot after successful angioplasty of the crural vessels. However, in 9/68 patients no increase was seen after successful angioplasty. With the use of a local administered competitive α-adrenergic receptor antagonist, it is also possible to test and quantify the capillary resistance index which is a parameter for the remaining functionality of the microcirculation in CLI patients.ConclusionPA might be used as a new endpoint for lower limb revascularization and can also be used to test the functionality the microcirculation to identify sub-types of patients with CLI. Clinical evaluation and standardization of PA is mandatory before introduction in daily practice.« less

Thermostatic tissue platform for intravital microscopy: 'the hanging drop' model.

PubMed

Pavlovic, Dragan; Frieling, Helge; Lauer, Kai-Stephan; Bac, Vo Hoai; Richter, Joern; Wendt, Michael; Lehmann, Christian; Usichenko, Taras; Meissner, Konrad; Gruendling, Matthias

2006-11-01

Intravital microscopy imposes the particular problem of the combined control of the body temperature of the animal and the local temperature of the observed organ or tissues. We constructed and tested, in the rat ileum microcirculation preparation, a new organ-support platform. The platform consisted of an organ bath filled with physiological solution, and contained a suction tube, a superfusion tube, an intestine-support hand that was attached to a micromanipulator and a thermometer probe. To cover the intestine we used a cover glass plate with a plastic ring glued on its upper surface. After a routine procedure (anaesthesia, monitoring and surgery), the intestine segment (2-3 cm long) was gently exteriorized and placed on the 'hand' of the organ support. A small part of the intestine formed a small 'island' in the bath that was filled with physiological salt solution. The cover glass was secured in place. The physiological salt solution from the superfusion tube, which was pointed to the lower surface of the cover glass, formed a 'hanging drop'. The objective of the microscope was then immersed into distilled water that was formed by the cover glass plastic ring. The 'hanging drop' technique prevented any tissue quenching, ensured undisturbed microcirculation, provided for stable temperature and humidity, and permitted a clear visual field.

Using synchrotron radiation angiography with a highly sensitive detector to identify impaired peripheral perfusion in rat pulmonary emphysema

PubMed Central

Ito, Hiromichi; Matsushita, Shonosuke; Hyodo, Kazuyuki; Sato, Yukio; Sakakibara, Yuzuru

2013-01-01

Owing to limitations in spatial resolution and sensitivity, it is difficult for conventional angiography to detect minute changes of perfusion in diffuse lung diseases, including pulmonary emphysema (PE). However, a high-gain avalanche rushing amorphous photoconductor (HARP) detector can give high sensitivity to synchrotron radiation (SR) angiography. SR angiography with a HARP detector provides high spatial resolution and sensitivity in addition to time resolution owing to its angiographic nature. The purpose of this study was to investigate whether this SR angiography with a HARP detector could evaluate altered microcirculation in PE. Two groups of rats were used: group PE and group C (control). Transvenous SR angiography with a HARP detector was performed and histopathological findings were compared. Peak density of contrast material in peripheral lung was lower in group PE than group C (p < 0.01). The slope of the linear regression line in scattering diagrams was also lower in group PE than C (p < 0.05). The correlation between the slope and extent of PE in histopathology showed significant negative correlation (p < 0.05, r = 0.61). SR angiography with a HARP detector made it possible to identify impaired microcirculation in PE by means of its high spatial resolution and sensitivity. PMID:23412496

[Comparative pathology of the microcirculatory bed].

PubMed

Strukov, A I; Vorob'eva, A A

1976-11-01

This paper presents an analysis of publications, mostly by Soviet authores, on clinical studies and morphological examinations of the microcirculatory bed in different pathology. It is concluded that the microcirculatory bed should be regarded as an integral system responding to the pathological effects by a local and general reaction of its structural components and by changing the rheological properties of blood. Two types of changes develop in the microcirculatory system -- sterotyped ones, typical for extreme states (various kinds of shock, hypertensive crisis, stress situations), and those specific for certain diseases (diabetes melitus, essential hypertension, athersclerosis, collagenoses, etc.). In all the above diseases the pathological process affects the functional structures of microcirculation that undergo a rearrangement in accordance with the requirements of the body. In the initial period of the disease this re-arrangement is of a compensatory nature and passes ahead of the clinical manifestations. A comparison of the pictutrs obtained by biomicroscopy of the bulbconjunctiva of the eye and of other mucosae with film preparations of the serosae demonstrates their complete similarity. Therefore, the method of biomicroscopy of the eyeball and of the mucosae as a method reflecting the state of microcirculation in the body as a whole should become an integral part of the clinical examination of patients.

Switchable skin window induced by optical clearing method for dermal blood flow imaging

NASA Astrophysics Data System (ADS)

Wang, Jing; Shi, Rui; Zhu, Dan

2013-06-01

Optical imaging techniques have shown tremendous potential for assessing cutaneous microcirculation, but the imaging depth and contrast is limited by the strong scattering of skin. Current skin windows have to be fulfilled by surgical operation and suffer from some side effects. In this study, a switchable skin window was developed by topical application of an optical clearing agent (OCA) and saline on rat skin in vivo. The validity of the skin window was evaluated by the laser speckle contrast imaging technique, and the safety of OCA to the body was tested through histologic examinations. The results indicated that administration of OCA or saline on rat skin in vivo can open or close the window of skin repeatedly for three days. With the repair effect of hyaluronic acid and Vaseline, it is able to repeatedly visualize the dermal blood vessels and flow distribution. Long-term observation shows that there is no abnormal reflection in micro-structure, body weight, organ coefficients, histopathologic lesions, or toxic reactions compared with a control group. This switchable window will provide an effective tool not only for cutaneous microcirculation with laser speckle contrast imaging, but also for diagnosis and treatment of peripheral vascular diseases, including tumor research with various optical imaging techniques.

Association of Microvascular Function and Endothelial Biomarkers With Clinical Outcome in Dengue: An Observational Study

PubMed Central

Yacoub, Sophie; Lam, Phung Khanh; Vu, Le Hoang Mai; Le, Thi Lien; Ha, Ngo Thanh; Toan, Tran Thi; Van, Nguyen Thu; Quyen, Nguyen Than Ha; Le Duyen, Huynh Thi; Van Kinh, Nguyen; Fox, Annette; Mongkolspaya, Juthathip; Wolbers, Marcel; Simmons, Cameron Paul; Screaton, Gavin Robert; Wertheim, Heiman; Wills, Bridget

2016-01-01

Background. The hallmark of severe dengue is increased microvascular permeability, but alterations in the microcirculation and their evolution over the course of dengue are unknown. Methods. We conducted a prospective observational study to evaluate the sublingual microcirculation using side-stream dark-field imaging in patients presenting early (<72 hours after fever onset) and patients hospitalized with warning signs or severe dengue in Vietnam. Clinical findings, microvascular function, global hemodynamics assessed with echocardiography, and serological markers of endothelial activation were determined at 4 time points. Results. A total of 165 patients were enrolled. No difference was found between the microcirculatory parameters comparing dengue with other febrile illnesses. The proportion of perfused vessels (PPV) and the mean flow index (MFI) were lower in patients with dengue with plasma than those without leakage (PPV, 88.1% vs 90.6% [P = .01]; MFI, 2.1 vs 2.4 [P = .007]), most markedly during the critical phase. PPV and MFI were correlated with the endothelial activation markers vascular cell adhesion molecule 1 (P < .001 for both) and angiopoietin 2 (P < .001 for both), negatively correlated. Conclusions. Modest microcirculatory alterations occur in dengue, are associated with plasma leakage, and are correlate with molecules of endothelial activation, angiopoietin 2 and vascular cell adhesion molecule 1. PMID:27230099

Retention of Plasmodium falciparum ring-infected erythrocytes in the slow, open microcirculation of the human spleen.

PubMed

Safeukui, Innocent; Correas, Jean-Michel; Brousse, Valentine; Hirt, Déborah; Deplaine, Guillaume; Mulé, Sébastien; Lesurtel, Mickael; Goasguen, Nicolas; Sauvanet, Alain; Couvelard, Anne; Kerneis, Sophie; Khun, Huot; Vigan-Womas, Inès; Ottone, Catherine; Molina, Thierry Jo; Tréluyer, Jean-Marc; Mercereau-Puijalon, Odile; Milon, Geneviève; David, Peter H; Buffet, Pierre A

2008-09-15

The current paradigm in Plasmodium falciparum malaria pathogenesis states that young, ring-infected erythrocytes (rings) circulate in peripheral blood and that mature stages are sequestered in the vasculature, avoiding clearance by the spleen. Through ex vivo perfusion of human spleens, we examined the interaction of this unique blood-filtering organ with P falciparum-infected erythrocytes. As predicted, mature stages were retained. However, more than 50% of rings were also retained and accumulated upstream from endothelial sinus wall slits of the open, slow red pulp microcirculation. Ten percent of rings were retained at each spleen passage, a rate matching the proportion of blood flowing through the slow circulatory compartment established in parallel using spleen contrast-enhanced ultrasonography in healthy volunteers. Rings displayed a mildly but significantly reduced elongation index, consistent with a retention process, due to their altered mechanical properties. This raises the new paradigm of a heterogeneous ring population, the less deformable subset being retained in the spleen, thereby reducing the parasite biomass that will sequester in vital organs, influencing the risk of severe complications, such as cerebral malaria or severe anemia. Cryptic ring retention uncovers a new role for the spleen in the control of parasite density, opening novel intervention opportunities.

In vivo functional photoacoustic microscopy of cutaneous microvasculature in human skin

PubMed Central

Favazza, Christopher P.; Cornelius, Lynn A.; Wang, Lihong V.

2011-01-01

Microcirculation is an important component of the cardiovascular system and can be used to assess systemic cardiovascular health. Numerous studies have investigated cutaneous microcirculation as an indicator of cardiovascular related diseases. Such research has shown promising results; however, there are many limitations regarding the employed measurement techniques, such as poor depth and spatial resolution and measurement versatility. Here we show the results of functional cutaneous microvascular experiments measured with photoacoustic microscopy, which provides high spatial resolution and multiparameter measurements. In a set of experiments, microvascular networks located in the palms of volunteers were perturbed by periodic ischemic events, and the subsequent hemodynamic response to the stimulus was recorded. Results indicate that during periods of arterial occlusion, the relative oxygen saturation of the capillary vessels decreased below resting levels, and temporarily increased above resting levels immediately following the occlusion. Furthermore, a hyperemic reaction to the occlusions was measured, and the observation agreed well with similar measurements using more conventional imaging techniques. Due to its exceptional capability to functionally image vascular networks with high spatial resolution, photoacoustic microscopy could be a beneficial biomedical tool to assess microvascular functioning and applied to patients with diseases that affect cardiovascular health. © 2011 Society of Photo-Optical Instrumentation Engineers. PMID:21361688

The venous-arterial difference in CO2 should be interpreted with caution in case of respiratory alkalosis in healthy volunteers.

PubMed

Morel, Jerome; Gergelé, Laurent; Dominé, Alexandre; Molliex, Serge; Perrot, Jean-Luc; Labeille, Bruno; Costes, Frederic

2017-08-01

The venous-arterial difference in CO 2 (ΔCO 2 ) has been proposed as an index of the adequacy of tissue perfusion in shock states. We hypothesized that the variation in PaCO 2 (hyper- or hypocapnia) could impact ΔCO 2 , partly through microcirculation adaptations. Fifteen healthy males volunteered to participate. For hypocapnia condition (hCO 2 ), the subjects were asked to hyperventilate, while they were asked to breathe a gas mixture containing 8 % CO 2 for hypercapnia condition (HCO 2 ). The 2 conditions were randomly assigned. Blood gases were measured at baseline before each condition, and after 5-7 min of either hCO 2 or HCO 2 condition. Microcirculation was assessed by the muscle reoxygenation slope measured with near infrared spectroscopy following a vascular occlusion test and by skin circulation with in vivo reflectance confocal microscopy. ΔCO 2 was significantly increased with hCO 2 while it tended to decrease with HCO 2 (non-significant). HCO 2 induced a moderate increase of the resaturation slope of NIRS oxygenation. Skin microcirculatory blood flow significantly dropped with hCO 2 , while it remained unchanged with hypercapnia. Our results warrant cautious interpretation of ΔCO 2 as an indicator of tissue perfusion during respiratory alkalosis.

An electricity consumption model for electric vehicular flow

NASA Astrophysics Data System (ADS)

Xiao, Hong; Huang, Hai-Jun; Tang, Tie-Qiao

2016-09-01

In this paper, we apply the relationships between the macro and micro variables of traffic flow to develop an electricity consumption model for electric vehicular flow. We use the proposed model to study the quantitative relationships between the electricity consumption/total power and speed/density under uniform flow, and the electricity consumptions during the evolution processes of shock, rarefaction wave and small perturbation. The numerical results indicate that the proposed model can perfectly describe the electricity consumption for electric vehicular flow, which shows that the proposed model is reasonable.

Hypersonic Viscous Shock Layer of Nonequilibrium Dissociating Gas

NASA Technical Reports Server (NTRS)

Chung, Paul M.

1961-01-01

The nonequilibrium chemical reaction of dissociation and recombination is studied theoretically for air in the viscous shock layer at the stagnation region af axisymmetric bodies. The flight regime considered is for speeds near satellite speed and for altitudes between 200,000 and 300,000 feet. The convective heat transfer to noncatalytic walls is obtained. The effects of nose radius, wall temperature, and flight altitude on the chemical state of the shock layer are studied. An analysis is also made on the simultaneous effect of nonequilibrium chemical reaction and air rarefaction on the shock layer thickness.