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Sample records for microvascular resistance methods

  1. Microvascular resistance in essential hypertension and flowmetry as a diagnostic method

    NASA Astrophysics Data System (ADS)

    Lukjanov, Valdimir F.

    2001-08-01

    New Doppler-Laser flowmetry diagnostic test of functional condition of microcirculation was worked out of find precapillar and postcapillar resistance. Flowmetry was used to measure vasomotion and blood flow after arterial compression, decompression and venous hyperemia were held. Patients of essential hypertension were examined with the help of Doppler-Laser Flowmetry, optical photometry (540 nm). Precapillar resistance included next basis parameters: vasomotion with high frequency (10-16 per/min) and low amplitude, latent time after decompression, large postocclusive reactive hyperemia, absent venous hyperemia. Postcapillar resistance included next basis parameters: vasomotion with low frequency (4-8 per/min) and high amplitude, paradoxical hyperemia in arterial compression, little or absent postocclusive reactive hyperemia, large venous hyperemia. This test-method was applied to select patogenetic treatment of essential hypertension.

  2. Hypertension Management and Microvascular Insulin Resistance in Diabetes

    PubMed Central

    Ko, Seung-Hyun; Cao, Wenhong; Liu, Zhenqi

    2011-01-01

    Type 2 diabetes is in essence a vascular disease and is frequently associated with hypertension, macrovascular events, and microvascular complications. Microvascular dysfunction, including impaired recruitment and capillary rarefaction, has been implicated in the pathogenesis of diabetic complications. Microvascular insulin resistance and renin-angiotensin system upregulation are present in diabetes, and each contributes to the development of hypertension and microvascular dysfunction. In the insulin-sensitive state, insulin increases microvascular perfusion by increasing endothelial nitric oxide production, but this effect is abolished by insulin resistance. Angiotensin II, acting via the type 1 receptors, induces inflammation and oxidative stress, leading to impaired insulin signaling, reduced nitric oxide availability, and vasoconstriction. Conversely, it acts on the type 2 receptors to cause vasodilatation. Because substrate and hormonal exchanges occur in the microvasculature, antihypertensive agents targeted to improve microvascular insulin sensitivity and function may have beneficial effects beyond their capacity to lower blood pressure in patients with diabetes. PMID:20582734

  3. Microvascular resistance of the culprit coronary artery in acute ST-elevation myocardial infarction

    PubMed Central

    Carrick, David; Haig, Caroline; Carberry, Jaclyn; McCartney, Peter; Welsh, Paul; Ahmed, Nadeem; McEntegart, Margaret; Petrie, Mark C.; Eteiba, Hany; Lindsay, Mitchell; Hood, Stuart; Watkins, Stuart; Rauhalammi, Samuli M.O.; Mordi, Ify; Ford, Ian; Radjenovic, Aleksandra; Sattar, Naveed; Oldroyd, Keith G.

    2016-01-01

    BACKGROUND. Failed myocardial reperfusion is common and prognostically important after acute ST-elevation myocardial infarction (STEMI). The purpose of this study was to investigate coronary flow reserve (CFR), a measure of vasodilator capacity, and the index of microvascular resistance (IMR; mmHg × s) in the culprit artery of STEMI survivors. METHODS. IMR (n = 288) and CFR (n = 283; mean age [SD], 60 [12] years) were measured acutely using guide wire–based thermodilution. Cardiac MRI disclosed left ventricular pathology, function, and volumes at 2 days (n = 281) and 6 months after STEMI (n = 264). All-cause death or first heart failure hospitalization was independently adjudicated (median follow-up 845 days). RESULTS. Myocardial hemorrhage and microvascular obstruction occurred in 89 (42%) and 114 (54%) patients with evaluable T2*-MRI maps. IMR and CFR were associated with microvascular pathology (none vs. microvascular obstruction only vs. microvascular obstruction and myocardial hemorrhage) (median [interquartile range], IMR: 17 [12.0–33.0] vs. 17 [13.0–39.0] vs. 37 [21.0–63.0], P < 0.001; CFR: 1.7 [1.4–2.5] vs. 1.5 [1.1–1.8] vs. 1.4 [1.0–1.8], P < 0.001), whereas thrombolysis in myocardial infarction blush grade was not. IMR was a multivariable associate of changes in left ventricular end-diastolic volume (regression coefficient [95% CI] 0.13 [0.01, 0.24]; P = 0.036), whereas CFR was not (P = 0.160). IMR (5 units) was a multivariable associate of all-cause death or heart failure hospitalization (n = 30 events; hazard ratio [95% CI], 1.09 [1.04, 1.14]; P < 0.001), whereas CFR (P = 0.124) and thrombolysis in myocardial infarction blush grade (P = 0.613) were not. IMR had similar prognostic value for these outcomes as <50% ST-segment resolution on the ECG. CONCLUSIONS. IMR is more closely associated with microvascular pathology, left ventricular remodeling, and health outcomes than the angiogram or CFR. TRIAL REGISTRATION. NCT02072850. FUNDING. A

  4. Microvascular resistance of the culprit coronary artery in acute ST-elevation myocardial infarction

    PubMed Central

    Carrick, David; Haig, Caroline; Carberry, Jaclyn; McCartney, Peter; Welsh, Paul; Ahmed, Nadeem; McEntegart, Margaret; Petrie, Mark C.; Eteiba, Hany; Lindsay, Mitchell; Hood, Stuart; Watkins, Stuart; Rauhalammi, Samuli M.O.; Mordi, Ify; Ford, Ian; Radjenovic, Aleksandra; Sattar, Naveed; Oldroyd, Keith G.

    2016-01-01

    BACKGROUND. Failed myocardial reperfusion is common and prognostically important after acute ST-elevation myocardial infarction (STEMI). The purpose of this study was to investigate coronary flow reserve (CFR), a measure of vasodilator capacity, and the index of microvascular resistance (IMR; mmHg × s) in the culprit artery of STEMI survivors. METHODS. IMR (n = 288) and CFR (n = 283; mean age [SD], 60 [12] years) were measured acutely using guide wire–based thermodilution. Cardiac MRI disclosed left ventricular pathology, function, and volumes at 2 days (n = 281) and 6 months after STEMI (n = 264). All-cause death or first heart failure hospitalization was independently adjudicated (median follow-up 845 days). RESULTS. Myocardial hemorrhage and microvascular obstruction occurred in 89 (42%) and 114 (54%) patients with evaluable T2*-MRI maps. IMR and CFR were associated with microvascular pathology (none vs. microvascular obstruction only vs. microvascular obstruction and myocardial hemorrhage) (median [interquartile range], IMR: 17 [12.0–33.0] vs. 17 [13.0–39.0] vs. 37 [21.0–63.0], P < 0.001; CFR: 1.7 [1.4–2.5] vs. 1.5 [1.1–1.8] vs. 1.4 [1.0–1.8], P < 0.001), whereas thrombolysis in myocardial infarction blush grade was not. IMR was a multivariable associate of changes in left ventricular end-diastolic volume (regression coefficient [95% CI] 0.13 [0.01, 0.24]; P = 0.036), whereas CFR was not (P = 0.160). IMR (5 units) was a multivariable associate of all-cause death or heart failure hospitalization (n = 30 events; hazard ratio [95% CI], 1.09 [1.04, 1.14]; P < 0.001), whereas CFR (P = 0.124) and thrombolysis in myocardial infarction blush grade (P = 0.613) were not. IMR had similar prognostic value for these outcomes as <50% ST-segment resolution on the ECG. CONCLUSIONS. IMR is more closely associated with microvascular pathology, left ventricular remodeling, and health outcomes than the angiogram or CFR. TRIAL REGISTRATION. NCT02072850. FUNDING. A

  5. Inflammation-induced microvascular insulin resistance is an early event in diet-induced obesity.

    PubMed

    Zhao, Lina; Fu, Zhuo; Wu, Jing; Aylor, Kevin W; Barrett, Eugene J; Cao, Wenhong; Liu, Zhenqi

    2015-12-01

    Endothelial dysfunction and vascular insulin resistance usually coexist and chronic inflammation engenders both. In the present study, we investigate the temporal relationship between vascular insulin resistance and metabolic insulin resistance. We assessed insulin responses in all arterial segments, including aorta, distal saphenous artery and the microvasculature, as well as the metabolic insulin responses in muscle in rats fed on a high-fat diet (HFD) for various durations ranging from 3 days to 4 weeks with or without sodium salicylate treatment. Compared with controls, HFD feeding significantly blunted insulin-mediated Akt (protein kinase B) and eNOS [endothelial nitric oxide (NO) synthase] phosphorylation in aorta in 1 week, blunted vasodilatory response in small resistance vessel in 4 weeks and microvascular recruitment in as early as 3 days. Insulin-stimulated whole body glucose disposal did not begin to progressively decrease until after 1 week. Salicylate treatment fully inhibited vascular inflammation, prevented microvascular insulin resistance and significantly improved muscle metabolic responses to insulin. We conclude that microvascular insulin resistance is an early event in diet-induced obesity and insulin resistance and inflammation plays an essential role in this process. Our data suggest microvascular insulin resistance contributes to the development of metabolic insulin resistance in muscle and muscle microvasculature is a potential therapeutic target in the prevention and treatment of diabetes and its related complications.

  6. Endurance, interval sprint, and resistance exercise training: impact on microvascular dysfunction in type 2 diabetes.

    PubMed

    Olver, T Dylan; Laughlin, M Harold

    2016-02-01

    Type 2 diabetes (T2D) alters capillary hemodynamics, causes capillary rarefaction in skeletal muscle, and alters endothelial and vascular smooth muscle cell phenotype, resulting in impaired vasodilatory responses. These changes contribute to altered blood flow responses to physiological stimuli, such as exercise and insulin secretion. T2D-induced microvascular dysfunction impairs glucose and insulin delivery to skeletal muscle (and other tissues such as skin and nervous), thereby reducing glucose uptake and perpetuating hyperglycemia and hyperinsulinemia. In patients with T2D, exercise training (EX) improves microvascular vasodilator and insulin signaling and attenuates capillary rarefaction in skeletal muscle. EX-induced changes subsequently augment glucose and insulin delivery as well as glucose uptake. If these adaptions occur in a sufficient amount of tissue, and skeletal muscle in particular, chronic exposure to hyperglycemia and hyperinsulinemia and the risk of microvascular complications in all vascular beds will decrease. We postulate that EX programs that engage as much skeletal muscle mass as possible and recruit as many muscle fibers within each muscle as possible will generate the greatest improvements in microvascular function, providing that the duration of the stimulus is sufficient. Primary improvements in microvascular function occur in tissues (skeletal muscle primarily) engaged during exercise, and secondary improvements in microvascular function throughout the body may result from improved blood glucose control. We propose that the added benefit of combined resistance and aerobic EX programs and of vigorous intensity EX programs is not simply "more is better." Rather, we believe the additional benefit is the result of EX-induced adaptations in and around more muscle fibers, resulting in more muscle mass and the associated microvasculature being changed. Thus, to acquire primary and secondary improvements in microvascular function and improved

  7. High fat diet induces central obesity, insulin resistance and microvascular dysfunction in hamsters.

    PubMed

    Costa, Rute R S; Villela, Nivaldo Ribeiro; Souza, Maria das Graças C; Boa, Beatriz C S; Cyrino, Fátima Z G A; Silva, Simone V; Lisboa, Patricia C; Moura, Egberto G; Barja-Fidalgo, Thereza Christina; Bouskela, Eliete

    2011-11-01

    Microvascular dysfunction is an early finding in obesity possibly related to co-morbidities like diabetes and hypertension. Therefore we have investigated changes on microvascular function, body composition, glucose and insulin tolerance tests (GTT and ITT) on male hamsters fed either with high fat (HFD, n=20) or standard (Control, n=21) diet during 16 weeks. Total body fat and protein content were determined by carcass analysis, aorta eNOS and iNOS expression by immunoblotting assay and mean blood pressure (MAP) and heart rate (HR) by an arterial catheter. Microvascular reactivity in response to acetylcholine and sodium nitroprusside, functional capillary density (FCD), capillary recruitment induced by a hyperinsulinemic status and macromolecular permeability after 30 min ischemia was assessed on either cheek pouch or cremaster muscle preparations. Compared to Control, HFD animals have shown increased visceral fat (6.0 ± 0.8 vs. 13.8 ± 0.6g/100g BW), impaired endothelial dependent vasodilatation, decreased FCD (11.3 ± 1.3 vs. 6.8 ± 1.2/field) and capillary recruitment during hyperinsulinemia and increased macromolecular permeability after ischemia/reperfusion (86.4 ± 5.2 vs.105.2 ± 5.1 leaks/cm(2)), iNOS expression and insulin resistance. MAP, HR, endothelial independent vasodilatation and eNOS expression were not different between groups. Our results have shown that HFD elicits an increase on visceral fat deposition, microvascular dysfunction and insulin resistance in hamsters.

  8. RESISTIVITY METHODS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resistivity methods were among the first geophysical techniques developed. The basic concept originated with Conrad Schlumberger, who conducted the initial resistivity field tests in Normandy, France during 1912. The resistivity method, employed in its earliest and most conventional form, uses an ex...

  9. Thiel embalming technique: a valuable method for microvascular exercise and teaching of flap raising.

    PubMed

    Wolff, Klaus-D; Kesting, Marco; Mücke, Thomas; Rau, Andrea; Hölzle, Frank

    2008-01-01

    Because of its high requirements on dexterity and microsurgical skills and the need of complete understanding of flap anatomy, microvascular free flap transfer belongs to the most demanding surgical procedures. Therefore, courses for flap raising and microvascular exercise are considered a prerequisite to prepare for clinical practise. To achieve teaching conditions as realistic as possible we used a novel cadaver embalming method enabling tissue dissection comparable to the living body. Thirty cadavers which were offered to us by the Institute of Anatomy for the purpose of running flap raising courses were embalmed in the technique described by Thiel. On each cadaver, nine free flaps were dissected according to a structured protocol by each course participant and afterwards used for microvascular exercise. The conservation of fine vascular structures and the suitability of the embalmed tissue for microvascular suturing were observed and photographically documented. The Thiel embalming technique provided flap raising procedures to be performed under realistic conditions similar to the living body. Vessels and nerves could be exposed and dissected up to a diameter of 1 mm and allowed for microvascular suturing even after weeks like fresh specimens. The Thiel embalming method is a unique technique and ideally suited to teach flap raising and microvascular suturing on human material.

  10. Aging alters reactivity of microvascular resistance networks in mouse gluteus maximus muscle

    PubMed Central

    Sinkler, Shenghua Y.

    2014-01-01

    Aging occurs with enhanced sympathetic nerve activity and endothelial dysfunction; however, little is known of how successive branches of microvascular resistance networks are affected in vivo. We questioned whether vascular reactivity is altered differentially along resistance networks with advanced age. The left gluteus maximus muscle of anesthetized 4-mo-old and 24-mo-old male C57BL/6 mice (Young and Old, respectively) was exposed for intravital microscopy and superfused with physiological salt solution (3 ml/min; pH 7.4, 34°C). Spontaneous vasomotor tone increased progressively from proximal feed arteries (FA) and first-order (1A) arterioles through distal second-order (2A) and third-order (3A) arterioles and was ∼15% greater in 2A and 3A of Old versus Young. Vasoconstriction during elevated superfusion Po2 increased with branch order and to a greater extent in Young. Peak constrictions to phenylephrine [α1 adrenoreceptor (α1AR) agonist] were similar for FA and 1A of both ages and ∼20% greater for 2A and 3A of Young. Across arterioles (but not FA), constrictions to UK 14304 (α2AR agonist) were depressed ∼30% in Old versus Young. Thus advanced age attenuated vasoconstriction to O2 throughout networks while blunting vasoconstriction to α1AR and α2AR activation in arterioles. With ACh, endothelium-dependent dilation (EDD) was ∼20% greater in FA of Young yet was approximately twofold greater for 2A and 3A of Old. Sodium nitroprusside evoked maximal dilations similar to ACh. Thus, with advanced age, EDD was attenuated in FA while robust in distal arterioles having enhanced vasomotor tone. We conclude that advanced age differentially alters reactivity among branches of microvascular resistance networks. PMID:25015968

  11. Human brain microvascular endothelial cells resist elongation due to shear stress.

    PubMed

    Reinitz, Adam; DeStefano, Jackson; Ye, Mao; Wong, Andrew D; Searson, Peter C

    2015-05-01

    Endothelial cells in straight sections of vessels are known to elongate and align in the direction of flow. This phenotype has been replicated in confluent monolayers of bovine aortic endothelial cells and human umbilical vein endothelial cells (HUVECs) in cell culture under physiological shear stress. Here we report on the morphological response of human brain microvascular endothelial cells (HBMECs) in confluent monolayers in response to shear stress. Using a microfluidic platform we image confluent monolayers of HBMECs and HUVECs under shear stresses up to 16 dyne cm(-2). From live-cell imaging we quantitatively analyze the cell morphology and cell speed as a function of time. We show that HBMECs do not undergo a classical transition from cobblestone to spindle-like morphology in response to shear stress. We further show that under shear stress, actin fibers are randomly oriented in the cells indicating that there is no cytoskeletal remodeling. These results suggest that HBMECs are programmed to resist elongation and alignment under shear stress, a phenotype that may be associated with the unique properties of the blood-brain barrier.

  12. Comparison of Different Methods for the Calculation of the Microvascular Flow Index

    PubMed Central

    Pozo, Mario O.; Kanoore Edul, Vanina S.; Ince, Can; Dubin, Arnaldo

    2012-01-01

    The microvascular flow index (MFI) is commonly used to semiquantitatively characterize the velocity of microcirculatory perfusion as absent (0), intermittent (1), sluggish (2), or normal (3). There are three approaches to compute MFI: (1) the average of the predominant flow in each of the four quadrants (MFIby quadrants), (2) the direct assessment during the bedside video acquisition (MFIpoint of care), and (3) the mean value of the MFIs determined in each individual vessel (MFIvessel by vessel). We hypothesized that the agreement between the MFIs is poor and that the MFIvessel by vessel better reflects the microvascular perfusion. For this purpose, we analyzed 100 videos from septic patients. In 25 of them, red blood cell (RBC) velocity was also measured. There were wide 95% limits of agreement between MFIby quadrants and MFIpoint of care (1.46), between MFIby quadrants and MFIvessel by vessel (2.85), and between MFIby point of care and MFIvessel by vessel (2.56). The MFIs significantly correlated with the RBC velocity and with the fraction of perfused small vessels, but MFIvessel by vessel showed the best R2. Although the different methods for the calculation of MFI reflect microvascular perfusion, they are not interchangeable and MFIvessel by vessel might be better. PMID:22593824

  13. In vivo microvascular network imaging of the human retina combined with an automatic three-dimensional segmentation method

    PubMed Central

    Huang, Shenghai; Piao, Zhonglie; Zhu, Jiang; Lu, Fan; Chen, Zhongping

    2015-01-01

    Abstract. Microvascular network of the retina plays an important role in diagnosis and monitoring of various retinal diseases. We propose a three-dimensional (3-D) segmentation method with intensity-based Doppler variance (IBDV) based on swept-source optical coherence tomography. The automatic 3-D segmentation method is used to obtain seven surfaces of intraretinal layers. The microvascular network of the retina, which is acquired by the IBDV method, can be divided into six layers. The microvascular network of the six individual layers is visualized, and the morphology and contrast images can be improved by using the segmentation method. This method has potential for earlier diagnosis and precise monitoring in retinal vascular diseases. PMID:26169790

  14. CEREBRAL CORTICAL MICROVASCULAR RAREFACTION IN METABOLIC SYNDROME IS DEPENDENT ON INSULIN RESISTANCE AND LOSS OF NITRIC OXIDE BIOAVAILABILITY

    PubMed Central

    Chantler, Paul D.; Shrader, Carl D.; Tabone, Lawrence E.; d’Audiffret, Alexandre C.; Huseynova, Khumara; Brooks, Steven D.; Branyan, Kayla W.; Grogg, Kristin A.; Frisbee, Jefferson C.

    2015-01-01

    Objective Chronic presentation of the metabolic syndrome (MS) is associated with an increased likelihood for stroke and poor stroke outcomes following occlusive cerebrovascular events. However, the physiological mechanisms contributing to compromised outcomes remain unclear, and the degree of cerebral cortical microvascular density (MVD) may represent a central determinant of stroke outcomes. Methods This study used the obese Zucker rat (OZR) model of MS and clinically-relevant, chronic interventions to determine the impact on cerebral cortical microvascular rarefaction via immunohistochemistry with a parallel determination of cerebrovascular function to identify putative mechanistic contributors. Results OZR exhibited a progressive rarefaction (to ~80% control MVD) of the cortical microvascular networks vs. lean Zucker rats. Chronic treatment with anti-hypertensive agents (captopril/hydralazine) had limited effectiveness in blunting rarefaction, although treatments improving glycemic control (metformin/rosiglitazone) were superior, maintaining ~94% control MVD. Chronic treatment with the antioxidant TEMPOL severely blunted rarefaction in OZR, although this ameliorative effect was prevented by concurrent NOS inhibition. Conclusions Further analyses revealed that the maintenance of glycemic control and vascular nitric oxide bioavailability were stronger predictors of cerebral cortical MVD in OZR than was prevention of hypertension, and this may have implications for chronic treatment of CVD risk under stroke-prone conditions. PMID:26014499

  15. The influence of elective percutaneous coronary intervention on microvascular resistance: a serial assessment using the index of microcirculatory resistance.

    PubMed

    Murai, Tadashi; Lee, Tetsumin; Kanaji, Yoshihisa; Matsuda, Junji; Usui, Eisuke; Araki, Makoto; Niida, Takayuki; Hishikari, Keiichi; Ichijyo, Sadamitsu; Hamaya, Rikuta; Yonetsu, Taishi; Isobe, Mitsuaki; Kakuta, Tsunekazu

    2016-09-01

    This study investigates whether hyperemic microvascular resistance (MR) is influenced by elective percutaneous coronary intervention (PCI) by using the index of microcirculatory resistance (IMR). Seventy-one consecutive patients with stable angina pectoris undergoing elective PCI were prospectively studied. The IMR was measured before and after PCI and at the 10-mo follow-up. The IMR significantly decreased until follow-up; the pre-PCI, post-PCI, and follow-up IMRs had a median of 19.8 (interquartile range, 14.6-28.9), 16.2 (11.8-22.1), and 14.8 (11.8-18.7), respectively (P < 0.001). The pre-PCI IMR was significantly correlated with the change in IMR between pre- and post-PCI (r = 0.84, P < 0.001) and between pre-PCI and follow-up (r = 0.93, P < 0.001). Pre-PCI IMR values were significantly higher in territories with decreases in IMR than in those with increases in IMR [pre-PCI IMR: 25.4 (18.4-35.5) vs. 12.5 (9.4-16.8), P < 0.001]. At follow-up, IMR values in territories showing decreases in IMR were significantly lower than those with increases in IMR [IMR at follow-up: 13.9 (10.9-17.6) vs. 16.6 (14.0-21.4), P = 0.013]. The IMR decrease was significantly associated with a greater shortening of mean transit time, indicating increases in coronary flow (P < 0.001). The optimal cut-off values of pre-PCI IMR to predict a decrease in IMR after PCI and at follow-up were 16.8 and 17.0, respectively. In conclusion, elective PCI affected hyperemic MR and its change was associated with pre-PCI MR, resulting in showing a wide distribution. Overall hyperemic MR significantly decreased until follow-up. The modified hyperemic MR introduced by PCI may affect post-PCI coronary flow. PMID:27342881

  16. Abnormalities of CSF flow patterns in the cerebral aqueduct in treatment-resistant late-life depression: a potential biomarker of microvascular angiopathy.

    PubMed

    Naish, Josephine H; Baldwin, Robert C; Patankar, Tufail; Jeffries, Suzanne; Burns, Alistair S; Taylor, Christopher J; Waterton, John C; Jackson, Alan

    2006-09-01

    There is growing evidence that microvascular angiopathy (MVA) plays an important role in the development of dementia and affective disorders in older people. At currently available image resolutions it is not possible to image directly the vascular changes associated with MVA, but the effects on blood and cerebrospinal fluid (CSF) flow may be detectable. The aim of this study was to investigate a potential biomarker for MVA based on MRI of abnormalities in CSF flow. Since there is considerable indirect evidence that treatment resistance in late-onset depressive disorder is related to MVA, we assessed the method in a group of 22 normal volunteers and 29 patients with responsive (N=21) or treatment-resistant (N=8) late-onset depressive disorder. Single-slice quantified phase-contrast (PC) images of cerebral blood and CSF flow were collected at 15 points over a cardiac cycle, and the resulting flow curves were parameterized. Significant differences in the CSF flow (width of systolic flow peak and diastolic flow volume, both P<0.01) through the cerebral aqueduct were observed for the group of treatment-resistant patients when compared to age matched controls. No significant difference was observed for a group of 21 patients with treatment-responsive depression. The findings support the hypothesis that MR measurement of CSF flow abnormalities provides a biomarker of MVA, and thus could have application in a wide range of age-related diseases.

  17. Differential effects of glucagon-like peptide-1 on microvascular recruitment and glucose metabolism in short- and long-term insulin resistance

    PubMed Central

    Sjøberg, Kim A; Rattigan, Stephen; Jeppesen, Jacob F; Lundsgaard, Anne-Marie; Holst, Jens J; Kiens, Bente

    2015-01-01

    Abstract Acute infusion of glucagon-like peptide-1 (GLP-1) has potent effects on blood flow distribution through the microcirculation in healthy humans and rats. A high fat diet induces impairments in insulin-mediated microvascular recruitment (MVR) and muscle glucose uptake, and here we examined whether this could be reversed by GLP-1. Using contrast-enhanced ultrasound, microvascular recruitment was assessed by continuous real-time imaging of gas-filled microbubbles in the microcirculation after acute (5 days) and prolonged (8 weeks) high fat diet (HF)-induced insulin resistance in rats. A euglycaemic hyperinsulinaemic clamp (3 mU min−1 kg−1), with or without a co-infusion of GLP-1 (100 pmol l−1), was performed in anaesthetized rats. Consumption of HF attenuated the insulin-mediated MVR in both 5 day and 8 week HF interventions which was associated with a 50% reduction in insulin-mediated glucose uptake compared to controls. Acute administration of GLP-1 restored the normal microvascular response by increasing the MVR after both 5 days and 8 weeks of HF intervention (P < 0.05). This effect of GLP-1 was associated with a restoration of both whole body insulin sensitivity and increased insulin-mediated glucose uptake in skeletal muscle by 90% (P < 0.05) after 5 days of HF but not after 8 weeks of HF. The present study demonstrates that GLP-1 increases MVR in rat skeletal muscle and can reverse early stages of high fat diet-induced insulin resistance in vivo. Key points Acute glucagon-like peptide-1 (GLP-1) infusion reversed the high fat diet-induced microvascular insulin resistance that occurred after both 5 days and 8 weeks of a high fat diet intervention. When GLP-1 was co-infused with insulin it had overt effects on whole body insulin sensitivity as well as insulin-mediated skeletal muscle glucose uptake after 5 days of a high fat diet, but not after 8 weeks of high fat diet intervention. Acute GLP-1 infusion did not have an additive

  18. Microvascular decompression for intractable singultus.

    PubMed

    Saito, Atsushi; Hatayama, Toru; Kon, Hiroyuki; Nakamura, Taigen; Sasaki, Tatsuya

    2016-10-01

    Intractable singultus due to cerebrovascular disease is very rare. We report a case of intractable singultus that improved after microvascular decompression and present a literature review. The patient was a 58-year-old man with a 30-year history of persistent singultus. Its frequency and duration gradually increased and it was resistant to multiple medical treatments. Microvascular decompression to relieve pressure on the anterolateral surface of the lower medulla oblongata from the vertebral artery resulted in the resolution of singultus. Patients with intractable idiopathic singultus who fail to respond to medical therapy need to be considered for the evaluation of cerebrovascular diseases and microvascular decompression. PMID:27335312

  19. Transfer of nitric oxide by blood from upstream to downstream resistance vessels causes microvascular dilation

    PubMed Central

    Zhou, X.; Unthank, J. L.; Miller, S. J.; Bills, R.

    2009-01-01

    The discovery that hemoglobin, albumin, and glutathione carry and release nitric oxide (NO) may have consequences for movement of NO by blood within microvessels. We hypothesize that NO in plasma or bound to proteins likely survives to downstream locations. To confirm this hypothesis, there must be a finite NO concentration ([NO]) in arteriolar blood, and upstream resistance vessels must be able to increase the vessel wall [NO] of downstream arterioles. Arteriolar blood NO was measured with NO-sensitive microelectrodes, and vessel wall [NO] was consistently 25–40% higher than blood [NO]. Localized suppression of NO production in large arterioles over 500–1,000 μm with l-nitroarginine reduced the [NO] ∼40%, indicating as much as 60% of the wall NO was from blood transfer. Flow in mesenteric arteries was elevated by occlusion of adjacent arteries to induce a flow-mediated increase in arterial NO production. Both arterial wall and downstream arteriolar [NO] increased and the arterioles dilated as the blood [NO] was increased. To study receptor-mediated NO generation, bradykinin was locally applied to upstream large arterioles and NO measured there and in downstream arterioles. At both sites, [NO] increased and both sets of vessels dilated. When isoproterenol was applied to the upstream vessels, they dilated, but neither the [NO] or diameter downstream arterioles increased. These observations indicate that NO can move in blood from upstream to downstream resistance vessels. This mechanism allows larger vessels that generate large [NO] to influence vascular tone in downstream vessels in response to both flow and receptor stimuli. PMID:19666847

  20. Microvascular rarefaction

    PubMed Central

    2010-01-01

    The goals of this presentation are twofold: (1) to briefly sketch the field of vascular rarefaction as a key component of various fibrotic diseases and (2) to illustrate it with four vignettes depicting diverse mechanisms of microvascular rarefaction. Specifically, I shall describe migratory and angiogenic incompetence of endothelial cells under conditions of reduced bioavailability of nitric oxide, role of endothelial-to-mesenchymal cell and mesenchymal stem cell-to-endothelial reprogramming, and potential role of antiangiogenic peptides in the development of graft vascular disease as exemplified by chronic allograft nephropathy PMID:20592859

  1. Studies of pathological dynamics after microvascular injury using nonlinear optical methods

    NASA Astrophysics Data System (ADS)

    Rosidi, Nathanael L.

    Microvascular lesions are a common feature in the aging brain and clinical evidence has correlated microvascular pathology with the development of neurodegenerative diseases such as Alzheimer's disease and dementia. Traditional animal models that replicate hemorrhagic and ischemic lesions in the brain typically affect large regions in the cortex and do not reproduce the small-scale lesions linked to neurodegeneration that likely stem from injuries to single microvessels. Due in part to this lack of small-scale injury animal models, there remains an incomplete understanding of the cellular and pathophysiological dynamics following small-scale vascular lesions, making progress on therapeutic strategies difficult. We used tightly focused femtosecond laser pulses to injure single penetrating arterioles (PA) (i.e., arterioles that plunge into the brain) in the cortex of live anesthetized rodents and used two-photon excited fluorescence (2PEF) imaging to quantify blood flow changes and to determine the time course of pathological consequences in the brain after injury. We find that after ischemic occlusion of a PA, nearby pial and penetrating arterioles do not actively compensate for the reduction of blood flow observed near the occluded blood vessel. We find that capillaries connected downstream to the clotted vessel dilate but other capillaries in the vicinity do not, suggesting that any compensatory signal that results in a physiological response travels vascularly. We ruptured individual PAs to induce microhemorrhages that resulted in extravasation of blood into the parenchyma. We find that tissue compression due to the hematoma does not collapse capillaries and cause acute ischemia. 2PEF imaging of mice expressing yellow fluorescent protein (YFP) in a subset of cortical neurons revealed no dendrite degeneration out to seven days after microhemorrhage. However, we did observe an inflammatory response by microglia/macrophages as quickly as 1.5-hrs after

  2. Mechanical behavior of pathological and normal red blood cells in microvascular flow based on modified level-set method

    NASA Astrophysics Data System (ADS)

    Zhang, XiWen; Ma, FangChao; Hao, PengFei; Yao, ZhaoHui

    2016-01-01

    The research of the motion and deformation of the RBCs is important to reveal the mechanism of blood diseases. A numerical method has been developed with level set formulation for elastic membrane immersed in incompressible fluid. The numerical model satisfies mass and energy conservation without the leaking problems in classical Immersed Boundary Method (IBM), at the same time, computing grid we used can be much smaller than the general literatures. The motion and deformation of a red blood cell (including pathological & normal status) in microvascular flow are simulated. It is found that the Reynolds number and membrane's stiffness play an important role in the transmutation and oscillation of the elastic membrane. The normal biconcave shape of the RBC is propitious to create high deformation than other pathological shapes. With reduced viscosity of the interior fluid both the velocity of the blood and the deformability of the cell reduced. With increased viscosity of the plasma both the velocity of the blood and the deformability of the cell reduced. The tank treading of the RBC membrane is observed at low enough viscosity contrast in shear flow. The tank tread fixed inclination angle of the cell depends on the shear ratio and viscosity contrast, which can be compared with the experimental observation well.

  3. Methods of airway resistance assessment.

    PubMed

    Urbankowski, Tomasz; Przybyłowski, Tadeusz

    2016-01-01

    Airway resistance is the ratio of driving pressure to the rate of the airflow in the airways. The most frequent methods used to measure airway resistance are whole-body plethysmography, the interrupter technique and the forced oscillation technique. All these methods allow to measure resistance during respiration at the level close to tidal volume, they do not require forced breathing manoeuvres or deep breathing during measurement. The most popular method for measuring airway resistance is whole-body plethysmography. The results of plethysmography include among others the following parameters: airway resistance (Raw), airway conductance (Gaw), specific airway resistance (sRaw) and specific airway conductance (sGaw). The interrupter technique is based on the assumption that at the moment of airway occlusion, air pressure in the mouth is equal to the alveolar pressure . In the forced oscillation technique (FOT), airway resistance is calculated basing on the changes in pressure and flow caused by air vibration. The methods for measurement of airway resistance that are described in the present paper seem to be a useful alternative to the most common lung function test - spirometry. The target group in which these methods may be widely used are particularly the patients who are unable to perform spirometry.

  4. Microvascular dysfunction in the context of diabetic neuropathy.

    PubMed

    Stirban, Alin

    2014-01-01

    Microvascular dysfunction in diabetes plays a crucial role in the development of diabetic complications. The skin, as one of the most accessible organs, serves as a model for the investigation of microvascular dysfunction. Several non-invasive, mostly laser-Doppler-based methods have been developed lately to assess microvascular function in the skin. Microvascular functional changes occur even in the prediabetic state and become more complex with overt diabetes, being exacerbated by the presence of peripheral and/or autonomic diabetic neuropathy. The present article aims at shedding light on the implication of endothelial and neurovascular dysfunction in microvascular changes in diabetes, highlighting the contribution of different forms of diabetic neuropathy.

  5. Laser Speckle Flowmetry Method for Measuring Spatial and Temporal Hemodynamic Alterations Throughout Large Microvascular Networks

    PubMed Central

    Meisner, Joshua K.; Sumer, Suna; Murrell, Kelsey P.; Higgins, Timothy J.; Price, Richard J.

    2012-01-01

    Objectives 1) Develop and validate laser speckle flowmetry (LSF) as a quantitative tool for individual microvessel hemodynamics in large networks. 2) Use LSF to determine if structural differences in the dorsal skinfold microcirculation (DSFWC) of C57BL/6 and BALB/c mice impart differential network hemodynamic responses to occlusion. Methods We compared LSF velocity measurements to known/measured velocities in vitro using capillary tube tissue phantoms and in vivo using mouse DSFWCs and cremaster muscles. Hemodynamic changes induced by feed arteriole occlusion were measured using LSF in DSFWCs implanted on C57BL/6 and BALB/c. Results In vitro, we found that the normalized speckle intensity (NSI) versus velocity linear relationship (R2≥0.97) did not vary with diameter or hematocrit and can be shifted to meet an expected operating range. In vivo, DSFWC and cremaster muscle preparations (R2=0.92 and 0.95, respectively) demonstrated similar linear relationships between NSI and centerline velocity. Stratification of arterioles into predicted collateral pathways revealed significant differences between C57BL/6 and BALB/c strains in response to feed arteriole occlusion. Conclusions These data demonstrate the applicability of LSF to intravital microscopy microcirculation preparations for determining both relative and absolute hemodynamics on a network-wide scale while maintaining the resolution of individual microvessels. PMID:22591575

  6. Contactless method of measuring resistivity

    NASA Technical Reports Server (NTRS)

    Crowley, J. D.; Rabson, T. A.

    1976-01-01

    A method is described for measuring the conductivity of materials without having to make electrical contact with the material. Currents which are magnetically induced in the conducting sample are measured by means of the magnetic fields they produce. Although induction techniques have been used in the past for this type of measurement, the configuration presented here makes it possible to perform absolute measurements of resistivity over a wide range of values for relatively small samples. The theory of the technique, the results of measurements made with it, and a comparison of the technique with other methods are presented.

  7. Skin microvascular endothelial function as a biomarker in cardiovascular diseases?

    PubMed

    Hellmann, Marcin; Roustit, Matthieu; Cracowski, Jean-Luc

    2015-08-01

    Skin microvascular endothelial function is impaired in many cardiovascular diseases, and could be therefore considered as a representative vascular bed. However, today, available evidence allows considering skin microvascular endothelial function neither as a diagnostic biomarker nor as a prognostic biomarker in cardiovascular diseases. Large follow-up studies using standardized methods should now be conducted to assess the potential predictive value of skin microvascular function in cardiovascular diseases.

  8. Hemorheology and Microvascular Disorders

    PubMed Central

    Cho, Daniel J

    2011-01-01

    The present review presents basic concepts of blood rheology related to vascular diseases. Blood flow in large arteries is dominated by inertial forces exhibited at high flow velocities, while viscous forces (i.e., blood rheology) play an almost negligible role. When high flow velocity is compromised by sudden deceleration as at a bifurcation, endothelial cell dysfunction can occur along the outer wall of the bifurcation, initiating inflammatory gene expression and, through mechanotransduction, the cascade of events associated with atherosclerosis. In sharp contrast, the flow of blood in microvessels is dominated by viscous shear forces since the inertial forces are negligible due to low flow velocities. Shear stress is a critical parameter in microvascular flow, and a force-balance approach is proposed for determining microvascular shear stress, accounting for the low Reynolds numbers and the dominance of viscous forces over inertial forces. Accordingly, when the attractive forces between erythrocytes (represented by the yield stress of blood) are greater than the shear force produced by microvascular flow, tissue perfusion itself cannot be sustained, leading to capillary loss. The yield stress parameter is presented as a diagnostic candidate for future clinical research, specifically, as a fluid dynamic biomarker for microvascular disorders. The relation between the yield stress and diastolic blood viscosity (DBV) is described using the Casson model for viscosity, from which one may be able determine thresholds of DBV where the risk of microvascular disorders is high. PMID:21779279

  9. What Causes Coronary Microvascular Disease?

    MedlinePlus

    ... Living With Clinical Trials Links Related Topics Angina Atherosclerosis Coronary Heart Disease Coronary Heart Disease Risk Factors ... Microvascular Disease? The same risk factors that cause atherosclerosis may cause coronary microvascular disease. Atherosclerosis is a ...

  10. Microvascular invasion in hepatocellular carcinoma

    PubMed Central

    Ünal, Emre; İdilman, İlkay Sedakat; Akata, Deniz; Özmen, Mustafa Nasuh; Karçaaltıncaba, Muşturay

    2016-01-01

    Microvascular invasion is a crucial histopathologic prognostic factor for hepatocellular carcinoma. We reviewed the literature and aimed to draw attention to clinicopathologic and imaging findings that may predict the presence of microvascular invasion in hepatocellular carcinoma. Imaging findings suggesting microvascular invasion are disruption of capsule, irregular tumor margin, peritumoral enhancement, multifocal tumor, increased tumor size, and increased glucose metabolism on positron emission tomography-computed tomography. In the presence of typical findings, microvascular invasion may be predicted. PMID:26782155

  11. Acute Alcohol Intoxication-Induced Microvascular Leakage

    PubMed Central

    Doggett, Travis M.; Breslin, Jerome W.

    2014-01-01

    Background Alcohol intoxication can increase inflammation and worsen injury, yet the mechanisms involved are not clear. We investigated whether acute alcohol intoxication elevates microvascular permeability, and investigated potential signaling mechanisms in endothelial cells that may be involved. Methods Conscious rats received a 2.5 g/kg alcohol bolus via gastric catheters to produce acute intoxication. Microvascular leakage of intravenously administered FITC-albumin from the mesenteric microcirculation was assessed by intravital microscopy. Endothelial-specific mechanisms were studied using cultured endothelial cell monolayers. Transendothelial electrical resistance (TER) served as an index of barrier function, before and after treatment with alcohol or its metabolite acetaldehyde. Pharmacologic agents were used to test the roles of alcohol metabolism, oxidative stress, p38 mitogen-activated protein (MAP) kinase, myosin light chain kinase (MLCK), rho kinase (ROCK), and exchange protein activated by cAMP (Epac). VE-cadherin localization was investigated to assess junctional integrity. Rac1 and RhoA activation were assessed by ELISA assays. Results Alcohol significantly increased FITC-albumin extravasation from the mesenteric microcirculation. Alcohol also significantly decreased TER and disrupted VE-cadherin organization at junctions. Acetaldehyde significantly decreased TER, but inhibition of ADH or application of a superoxide dismutase mimetic failed to prevent alcohol-induced decreases in TER. Inhibition of p38 MAP kinase, but not MLCK or ROCK, significantly attenuated the alcohol-induced barrier dysfunction. Alcohol rapidly decreased GTP-bound Rac1 but not RhoA during the drop in TER. Activation of Epac increased TER, but did not prevent alcohol from decreasing TER. However, activation of Epac after initiation of alcohol-induced barrier dysfunction quickly resolved TER to baseline levels. Conclusions Our results suggest that alcohol intoxication increases

  12. Methods for resistive switching of memristors

    DOEpatents

    Mickel, Patrick R.; James, Conrad D.; Lohn, Andrew; Marinella, Matthew; Hsia, Alexander H.

    2016-05-10

    The present invention is directed generally to resistive random-access memory (RRAM or ReRAM) devices and systems, as well as methods of employing a thermal resistive model to understand and determine switching of such devices. In particular example, the method includes generating a power-resistance measurement for the memristor device and applying an isothermal model to the power-resistance measurement in order to determine one or more parameters of the device (e.g., filament state).

  13. Antimicrobial resistance in campylobacter: susceptibility testing methods and resistance trends.

    PubMed

    Ge, Beilei; Wang, Fei; Sjölund-Karlsson, Maria; McDermott, Patrick F

    2013-10-01

    Most Campylobacter infections are self-limiting but antimicrobial treatment (e.g., macrolides, fluoroquinolones) is necessary in severe or prolonged cases. Susceptibility testing continues to play a critical role in guiding therapy and epidemiological monitoring of resistance. The methods of choice for Campylobacter recommended by the Clinical and Laboratory Standards Institute (CLSI) are agar dilution and broth microdilution, while a disk diffusion method was recently standardized by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Macrolides, quinolones, and tetracyclines are among the common antimicrobials recommended for testing. Molecular determination of Campylobacter resistance via DNA sequencing or PCR-based methods has been performed. High levels of resistance to tetracycline and ciprofloxacin are frequently reported by many national surveillance programs, but resistance to erythromycin and gentamicin in Campylobacter jejuni remains low. Nonetheless, variations in susceptibility observed over time underscore the need for continued public health monitoring of Campylobacter resistance from humans, animals, and food.

  14. A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging.

    PubMed

    Borges, J P; Lopes, G O; Verri, V; Coelho, M P; Nascimento, P M C; Kopiler, D A; Tibirica, E

    2016-01-01

    Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61) and healthy age-matched subjects (n=24). Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; P<0.01). With regard to post-occlusive reactive hyperemia-induced vasodilation, the patients also presented reduced responses compared to the controls (0.42±0.15 vs 0.50±0.13 APU/mmHg; P=0.04). In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men. PMID:27599202

  15. A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging

    PubMed Central

    Borges, J.P.; Lopes, G.O.; Verri, V.; Coelho, M.P.; Nascimento, P.M.C.; Kopiler, D.A.; Tibirica, E.

    2016-01-01

    Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61) and healthy age-matched subjects (n=24). Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; P<0.01). With regard to post-occlusive reactive hyperemia-induced vasodilation, the patients also presented reduced responses compared to the controls (0.42±0.15 vs 0.50±0.13 APU/mmHg; P=0.04). In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men. PMID:27599202

  16. A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging.

    PubMed

    Borges, J P; Lopes, G O; Verri, V; Coelho, M P; Nascimento, P M C; Kopiler, D A; Tibirica, E

    2016-09-01

    Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61) and healthy age-matched subjects (n=24). Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; P<0.01). With regard to post-occlusive reactive hyperemia-induced vasodilation, the patients also presented reduced responses compared to the controls (0.42±0.15 vs 0.50±0.13 APU/mmHg; P=0.04). In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men.

  17. Method Analysis of Microbial Resistant Gypsum Products

    EPA Science Inventory

    Abstract: Several commercially available gypsum products are marketed as microbial-resistant. During previous test method research on a microbial resistant gypsum wallboard study, a common theme from both stakeholders and product vendors was the need for a unified and accepted m...

  18. Oxidation resistant alloys, method for producing oxidation resistant alloys

    DOEpatents

    Dunning, John S.; Alman, David E.

    2002-11-05

    A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800 C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800 C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700 C. at a low cost

  19. Oxidation resistant alloys, method for producing oxidation resistant alloys

    DOEpatents

    Dunning, John S.; Alman, David E.

    2002-11-05

    A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

  20. Reduced cortical microvascular oxygenation in multiple sclerosis: a blinded, case-controlled study using a novel quantitative near-infrared spectroscopy method

    NASA Astrophysics Data System (ADS)

    Yang, Runze; Dunn, Jeff F.

    2015-11-01

    Hypoxia (low oxygen) is associated with many brain disorders as well as inflammation, but the lack of widely available technology has limited our ability to study hypoxia in human brain. Multiple sclerosis (MS) is a poorly understood neurological disease with a significant inflammatory component which may cause hypoxia. We hypothesized that if hypoxia were to occur, there should be reduced microvascular hemoglobin saturation (StO2). In this study, we aimed to determine if reduced StO2 can be detected in MS using frequency domain near-infrared spectroscopy (fdNIRS). We measured fdNIRS data in cortex and assessed disability of 3 clinical isolated syndrome (CIS), 72 MS patients and 12 controls. Control StO2 was 63.5 ± 3% (mean ± SD). In MS patients, 42% of StO2 values were more than 2 × SD lower than the control mean. There was a significant relationship between StO2 and clinical disability. A reduced microvascular StO2 is supportive (although not conclusive) that there may be hypoxic regions in MS brain. This is the first study showing how quantitative NIRS can be used to detect reduced StO2 in patients with MS, opening the door to understanding how microvascular oxygenation impacts neurological conditions.

  1. Microvascular dysfunction in the course of metabolic syndrome induced by high-fat diet

    PubMed Central

    2014-01-01

    Background Metabolic syndrome (MetS) is associated with increased risk of cardiovascular disease (CVD). One important feature underlying the pathophysiology of many types of CVD is microvascular dysfunction. Although components of MetS are themselves CVD risk factors, the risk is increased when the syndrome is considered as one entity. We aimed to characterize microvascular function and some of its influencing factors in the course of MetS development. Methods Development of MetS in C57BL/6 mice on a high-fat diet (HFD, 51% of energy from fat) was studied. The initial phase of MetS (I-MetS) was defined as the first 2 weeks of HFD feeding, with the fully developed phase occurring after 8 weeks of HFD. We characterized these phases by assessing changes in adiposity, blood pressure, and microvascular function. All data are presented as mean ± standard error (SEM). Differences between cumulative dose–response curves of myograph experiments were calculated using non-linear regression analysis. In other experiments, comparisons between two groups were made with Student’s t-test. Comparisons between more than two groups were made using one-way ANOVA with Tukey post-hoc test. A probability value <0.05 was considered statistically significant. Results I-MetS mice presented with weight gain, blood pressure elevation, and microvascular dysfunction characterized by augmented vasoconstriction. This finding, contrary to those in mice with fully developed MetS, was not associated with endothelial dysfunction, insulin resistance, or systemic inflammation. In the initial phase, perivascular adipose tissue showed no sign of inflammation and had no influence on the pattern of vasoconstriction. These findings suggest that the onset of hypertension in MetS is strongly influenced by vascular smooth muscle cell dysfunction and independent of important factors known to influence microvascular function and consequently blood pressure levels. Conclusion We identified in I

  2. Systemic Microvascular Dysfunction and Inflammation after Pulmonary Particulate Matter Exposure

    PubMed Central

    Nurkiewicz, Timothy R.; Porter, Dale W.; Barger, Mark; Millecchia, Lyndell; Rao, K. Murali K.; Marvar, Paul J.; Hubbs, Ann F.; Castranova, Vincent; Boegehold, Matthew A.

    2006-01-01

    polymorphonuclear leukocytes (PMNLs). In ROFA- and TiO2-exposed rats, MPO was found in PMNLs adhering to the systemic microvascular wall. Evidence suggests that some of this MPO had been deposited in the microvascular wall. There was also evidence for oxidative stress in the microvascular wall. These results indicate that after PM exposure, the impairment of endothelium-dependent dilation in the systemic microcirculation coincides with PMNL adhesion, MPO deposition, and local oxidative stress. Collectively, these microvascular observations are consistent with events that contribute to the disruption of the control of peripheral resistance and/or cardiac dysfunction associated with PM exposure. PMID:16507465

  3. Systemic microvascular dysfunction and inflammation after pulmonary particulate matter exposure.

    PubMed

    Nurkiewicz, Timothy R; Porter, Dale W; Barger, Mark; Millecchia, Lyndell; Rao, K Murali K; Marvar, Paul J; Hubbs, Ann F; Castranova, Vincent; Boegehold, Matthew A

    2006-03-01

    polymorphonuclear leukocytes (PMNLs). In ROFA- and TiO2-exposed rats, MPO was found in PMNLs adhering to the systemic microvascular wall. Evidence suggests that some of this MPO had been deposited in the microvascular wall. There was also evidence for oxidative stress in the microvascular wall. These results indicate that after PM exposure, the impairment of endothelium-dependent dilation in the systemic microcirculation coincides with PMNL adhesion, MPO deposition, and local oxidative stress. Collectively, these microvascular observations are consistent with events that contribute to the disruption of the control of peripheral resistance and/or cardiac dysfunction associated with PM exposure. PMID:16507465

  4. Microvascular dysfunction in schizophrenia: a case–control study

    PubMed Central

    Vetter, Martin W; Martin, Billie-Jean; Fung, Marinda; Pajevic, Milada; Anderson, Todd J; Raedler, Thomas J

    2015-01-01

    Background: Schizophrenia is a mental illness associated with cardiovascular disease at a younger age than in the general population. Endothelial dysfunction has predictive value for future cardiovascular events; however, the impact of a diagnosis of schizophrenia on this marker is unknown. Aims: We tested the hypothesis that subjects with schizophrenia have impaired endothelial function. Methods: A total of 102 subjects (34.5±7.5 years) participated in this study. This sample consisted of 51 subjects with a diagnosis of schizophrenia and 51 healthy subjects, who were matched for age (P=0.442), sex (P>0.999), and smoking status (P=0.842). Peripheral artery microvascular and conduit vessel endothelial function was measured using hyperemic velocity time integral (VTI), pulse arterial tonometry (PAT), and flow-mediated dilation (FMD). Results: Significantly lower values of VTI were noted in subjects with schizophrenia (104.9±33.0 vs. 129.1±33.8 cm, P<0.001), whereas FMD (P=0.933) and PAT (P=0.862) did not differ between the two groups. A multivariable-linear-regression analysis, built on data from univariate and partial correlations, showed that only schizophrenia, sex, lipid-lowering medications, antihypertensive medications, and low-density lipoprotein (LDL)-cholesterol were predictive of attenuated VTI, whereas age, ethnicity, family history of cardiovascular disease, smoking status, systolic blood pressure, waist circumference, HDL-cholesterol, triglycerides, C-reactive protein, and homeostatic model assessment-insulin resistance (HOMA-IR), antidiabetic medications, antidepressant medications, mood stabilizers, benzodiazepines, and anticholinergic medications did not predict VTI in this model (adjusted R 2=0.248). Conclusions: Our findings suggest that a diagnosis of schizophrenia is associated with impaired microvascular function as indicated by lower values of VTI, irrespective of many other clinical characteristics. It might be an early indicator of

  5. Soil Identification using Field Electrical Resistivity Method

    NASA Astrophysics Data System (ADS)

    Hazreek, Z. A. M.; Rosli, S.; Chitral, W. D.; Fauziah, A.; Azhar, A. T. S.; Aziman, M.; Ismail, B.

    2015-06-01

    Geotechnical site investigation with particular reference to soil identification was important in civil engineering works since it reports the soil condition in order to relate the design and construction of the proposed works. In the past, electrical resistivity method (ERM) has widely being used in soil characterization but experienced several black boxes which related to its results and interpretations. Hence, this study performed a field electrical resistivity method (ERM) using ABEM SAS (4000) at two different types of soils (Gravelly SAND and Silty SAND) in order to discover the behavior of electrical resistivity values (ERV) with type of soils studied. Soil basic physical properties was determine thru density (p), moisture content (w) and particle size distribution (d) in order to verify the ERV obtained from each type of soil investigated. It was found that the ERV of Gravelly SAND (278 Ωm & 285 Ωm) was slightly higher than SiltySAND (223 Ωm & 199 Ωm) due to the uncertainties nature of soils. This finding has showed that the results obtained from ERM need to be interpreted based on strong supported findings such as using direct test from soil laboratory data. Furthermore, this study was able to prove that the ERM can be established as an alternative tool in soil identification provided it was being verified thru other relevance information such as using geotechnical properties.

  6. The electrical resistivity method in cased boreholes

    SciTech Connect

    Schenkel, C.J.

    1991-05-01

    The use of downhole current sources in resistivity mapping can greatly enhance the detection and delineation of subsurface features. The purpose of this work is to examine the resistivity method for current sources in wells cased with steel. The resistivity method in cased boreholes with downhole current sources is investigated using the integral equation (IE) technique. The casing and other bodies are characterized as conductivity inhomogeneities in a half-space. For sources located along the casing axis, an axially symmetric Green's function is used to formulate the surface potential and electric field (E-field) volume integral equations. The situations involving off-axis current sources and three-dimensional (3-D) bodies is formulated using the surface potential IE method. The solution of the 3-D Green's function is presented in cylindrical and Cartesian coordinate systems. The methods of moments is used to solve the Fredholm integral equation of the second kind for the response due to the casing and other bodies. The numerical analysis revealed that the current in the casing can be approximated by its vertical component except near the source and the axial symmetric approximation of the casing is valid even for the 3-D problem. The E-field volume IE method is an effective and efficient technique to simulate the response of the casing in a half-space, whereas the surface potential approach is computationally better when multiple bodies are involved. Analyzing several configurations of the current source indicated that the casing response is influenced by four characteristic factors: conduction length, current source depth,casing depth, and casing length. 85 refs., 133 figs., 11 tabs.

  7. Globular Adiponectin Enhances Muscle Insulin Action via Microvascular Recruitment and Increased Insulin Delivery

    PubMed Central

    Zhao, Lina; Chai, Weidong; Fu, Zhuo; Dong, Zhenhua; Aylor, Kevin W.; Barrett, Eugene J.; Cao, Wenhong; Liu, Zhenqi

    2014-01-01

    Rationale Adiponectin enhances insulin action and induces nitric oxide–dependent vasodilatation. Insulin delivery to muscle microcirculation and transendothelial transport are 2 discrete steps that limit insulin's action. We have shown that expansion of muscle microvascular surface area increases muscle insulin delivery and action. Objective To examine whether adiponectin modulates muscle microvascular recruitment thus insulin delivery and action in vivo. Methods and Results Overnight fasted adult male rats were studied. We determined the effects of adiponectin on muscle microvascular recruitment, using contrast-enhanced ultrasound, on insulin-mediated microvascular recruitment and whole-body glucose disposal, using contrast-enhanced ultrasound and insulin clamp, and on muscle insulin clearance and uptake with 125I-insulin. Globular adiponectin potently increased muscle microvascular blood volume without altering microvascular blood flow velocity, leading to a significantly increased microvascular blood flow. This was paralleled by a ≈30% to 40% increase in muscle insulin uptake and clearance, and ≈30% increase in insulin-stimulated whole-body glucose disposal. Inhibition of endothelial nitric oxide synthase abolished globular adiponectin-mediated muscle microvascular recruitment and insulin uptake. In cultured endothelial cells, globular adiponectin dose-dependently increased endothelial nitric oxide synthase phosphorylation but had no effect on endothelial cell internalization of insulin. Conclusions Globular adiponectin increases muscle insulin uptake by recruiting muscle microvasculature, which contributes to its insulin-sensitizing action. PMID:23459195

  8. Comparing the effect of clopidogrel versus ticagrelor on coronary microvascular dysfunction in acute coronary syndrome patients (TIME trial): study protocol for a randomized controlled trial

    PubMed Central

    2014-01-01

    Background Although prompt reperfusion treatment restores normal epicardial flow, microvascular dysfunction may persist in some patients with acute coronary syndrome (ACS). Impaired myocardial perfusion is caused by intraluminal platelets, fibrin thrombi and neutrophil plugging; antiplatelet agents play a significant role in terms of protecting against thrombus microembolization. A novel antiplatelet agent, ticagrelor, is a non-thienopyridine, direct P2Y12 blocker that has shown greater, more rapid and more consistent platelet inhibition than clopidogrel. However, the effects of ticagrelor on the prevention of microvascular dysfunction are uncertain. The present study is a comparison between clopidogrel and ticagrelor use for preventing microvascular dysfunction in patients with ST elevation or non-ST elevation myocardial infarction (STEMI or NSTEMI, respectively). Methods/design The TIME trial is a single-center, randomized, open-label, parallel-arm study designed to demonstrate the superiority of ticagrelor over clopidogrel. A total of 152 patients with a spectrum of STEMI or NSTEMI will undergo prospective random assignment to clopidogrel or ticagrelor (1:1 ratio). The primary endpoint is an index of microcirculatory resistance (IMR) measured after percutaneous coronary intervention (PCI); the secondary endpoint is wall motion score index assessed at 3 months by using echocardiography. Discussion The TIME trial is the first study designed to compare the protective effect of clopidogrel and ticagrelor on coronary microvascular dysfunction in patients with STEMI and NSTEMI. Trial registration ClinicalTrials.gov: NCT02026219. Registration date: 24 December 2013. PMID:24885437

  9. Safety of guidewire-based measurement of fractional flow reserve and the index of microvascular resistance using intravenous adenosine in patients with acute or recent myocardial infarction

    PubMed Central

    Ahmed, Nadeem; Layland, Jamie; Carrick, David; Petrie, Mark C.; McEntegart, Margaret; Eteiba, Hany; Hood, Stuart; Lindsay, Mitchell; Watkins, Stuart; Davie, Andrew; Mahrous, Ahmed; Carberry, Jaclyn; Teng, Vannesa; McConnachie, Alex; Curzen, Nick; Oldroyd, Keith G.; Berry, Colin

    2016-01-01

    Aims Coronary guidewire-based diagnostic assessments with hyperemia may cause iatrogenic complications. We assessed the safety of guidewire-based measurement of coronary physiology, using intravenous adenosine, in patients with an acute coronary syndrome. Methods We prospectively enrolled invasively managed STEMI and NSTEMI patients in two simultaneously conducted studies in 6 centers (NCT01764334; NCT02072850). All of the participants underwent a diagnostic coronary guidewire study using intravenous adenosine (140 μg/kg/min) infusion for 1–2 min. The patients were prospectively assessed for the occurrence of serious adverse events (SAEs) and symptoms and invasively measured hemodynamics were also recorded. Results 648 patients (n = 298 STEMI patients in 1 hospital; mean time to reperfusion 253 min; n = 350 NSTEMI in 6 hospitals; median time to angiography from index chest pain episode 3 (2, 5) days) were included between March 2011 and May 2013. Two NSTEMI patients (0.3% overall) experienced a coronary dissection related to the guidewire. No guidewire dissections occurred in the STEMI patients. Chest symptoms were reported in the majority (86%) of patient's symptoms during the adenosine infusion. No serious adverse events occurred during infusion of adenosine and all of the symptoms resolved after the infusion ceased. Conclusions In this multicenter analysis, guidewire-based measurement of FFR and IMR using intravenous adenosine was safe in patients following STEMI or NSTEMI. Self-limiting symptoms were common but not associated with serious adverse events. Finally, coronary dissection in STEMI and NSTEMI patients was noted to be a rare phenomenon. PMID:26418191

  10. Methods for engineering resistance to plant viruses.

    PubMed

    Sudarshana, Mysore R; Roy, Gourgopal; Falk, Bryce W

    2007-01-01

    The development of genetically engineered resistance to plant viruses is a result of efforts to understand the plant-virus interactions involved in "crossprotection," a phenomenon observed with several plant virus diseases. Historically, expression of the coat protein gene of Tobacco mosaic virus in transgenic tobacco (Nicotiana tabacum) plants is the first example of transgene-mediated resistance to a plant virus. Subsequently, virus-derived sequences of several plant viruses were shown to confer virus resistance in experimental and/or natural hosts. For plant RNA viruses, virus complementary DNA sequences shown to confer resistance include wild-type genes, mutated genes that produced truncated protein products, and nontranslatable sense or antisense transcripts to various regions of the virus genome. Resistance also has been demonstrated for some viruses by mutant trans-dominant gene products, derived from the movement protein and replication-associated protein genes. In addition to virus-derived sequences, gene sequences of plant origin have also been used for transgenic resistance, and such resistance can be virus-specific, for instance, R genes isolated from resistant plant genotypes, or nonspecific, for example, ribosome inactivating proteins and proteinase inhibitors. Plantibodies and 2-5A synthetase, a class of proteins of mammalian origin, have also been useful in engineering plant virus resistance. In the case of transgenic resistance mediated by viral coat protein, the mechanism of resistance was suggested to operate during the early events of virus infection. However, transgene-mediated RNA silencing and generation of small interfering RNAs appears to be the primary mechanism that confers resistance to plant viruses. Despite the advantages of transgene-mediated resistance, current interest in the development and use of transgenic virus resistant plants is low in most parts of the world. However, because of its real potential, we believe that this

  11. Effect of Qi-regulating,Phlegm-resolving,and Blood-promoting Prescription on Rat Coronary Microvascular Thrombosis and Coronary Microvascular Occlusion.

    PubMed

    2016-06-10

    Objective To explore the effect of qi-regulating,phlegm-resolving,and blood-promoting prescription on coronary microvascular thrombosis and coronary microvascular occlusion in rat models. Methods Totally 125 healthy clean-grade male SD rats weighing (300±25) g were sequentially numbered and then randomly divided into treatment group (n=60),control group (n=60) and blank group (n=5).Rats in the treatment group and control group received apical left ventricular injection of sodium laurate to establish rat models of coronary microvascular thrombosis. Then,rats in the control group were given distilled water by gavage one day before operation and after surgery. In contrast,rats in the treatment group were given qi-regulating,phlegm-resolving,and blood-promoting prescription by gavage one day before operation and after surgery. Five rats from both treatment group and control group were killed at each of six time points (1 hour,24th hour,7th day,14th day,21th day,and 28th day),and the myocardium specimens were harvested. The 5 rats in the blank group did not receive any special treatment and were given normal feeding;in the 28th day,they were sacrificed to obtain the myocardial specimens. Pathological sections of rat myocardial tissues were made to observe and compare the degrees of coronary microvascular thrombosis and coronary microvascular obstruction. Results In the treatment group and the control group,coronary microvascular thrombosis occurred 1 hour after apical sodium laurate injection and reached the peak at the 24th hour. Compared with the blank group,the treatment group and the control group showed different degree of coronary microvascular obstruction. Comparison between the treatment group and the control group at each time point showed that the coronary microvascular thrombosis in the treatment group was significantly lower than that in the control group (P<0.05 or P<0.01).The severity of coronary

  12. Method for producing heat-resistant semi-inorganic compounds

    NASA Technical Reports Server (NTRS)

    Yajima, S.; Okamura, K.; Shishido, T.; Hasegawa, Y.

    1983-01-01

    The method for producing a heat resistant, semi-inorganic compound is discussed. Five examples in which various alcohols, phenols, and aromatic carbonic acids are used to test heat resistance and solubility are provided.

  13. Normal Muscle Oxygen Consumption and Fatigability in Sickle Cell Patients Despite Reduced Microvascular Oxygenation and Hemorheological Abnormalities

    PubMed Central

    Waltz, Xavier; Pichon, Aurélien; Lemonne, Nathalie; Mougenel, Danièle; Lalanne-Mistrih, Marie-Laure; Lamarre, Yann; Tarer, Vanessa; Tressières, Benoit; Etienne-Julan, Maryse; Hardy-Dessources, Marie-Dominique; Hue, Olivier; Connes, Philippe

    2012-01-01

    Background/Aim Although it has been hypothesized that muscle metabolism and fatigability could be impaired in sickle cell patients, no study has addressed this issue. Methods We compared muscle metabolism and function (muscle microvascular oxygenation, microvascular blood flow, muscle oxygen consumption and muscle microvascular oxygenation variability, which reflects vasomotion activity, maximal muscle force and local muscle fatigability) and the hemorheological profile at rest between 16 healthy subjects (AA), 20 sickle cell-hemoglobin C disease (SC) patients and 16 sickle cell anemia (SS) patients. Results Muscle microvascular oxygenation was reduced in SS patients compared to the SC and AA groups and this reduction was not related to hemorhelogical abnormalities. No difference was observed between the three groups for oxygen consumption and vasomotion activity. Muscle microvascular blood flow was higher in SS patients compared to the AA group, and tended to be higher compared to the SC group. Multivariate analysis revealed that muscle oxygen consumption was independently associated with muscle microvascular blood flow in the two sickle cell groups (SC and SS). Finally, despite reduced muscle force in sickle cell patients, their local muscle fatigability was similar to that of the healthy subjects. Conclusions Sickle cell patients have normal resting muscle oxygen consumption and fatigability despite hemorheological alterations and, for SS patients only, reduced muscle microvascular oxygenation and increased microvascular blood flow. Two alternative mechanisms can be proposed for SS patients: 1) the increased muscle microvascular blood flow is a way to compensate for the lower muscle microvascular oxygenation to maintain muscle oxygen consumption to normal values or 2) the reduced microvascular oxygenation coupled with a normal resting muscle oxygen consumption could indicate that there is slight hypoxia within the muscle which is not sufficient to limit

  14. A history of vascular and microvascular surgery.

    PubMed

    Rickard, Rory F; Hudson, Donald A

    2014-10-01

    The history of microvascular surgery is intimately linked to that of vascular surgery. Microvascular techniques, developed mainly in China, Japan, Australia, and the United States of America, built on the principles of vascular anastomosis established by pioneers in France, Germany, Italy, and the United States of America. We present a history of the technique here.

  15. Surgical variation of microvascular decompression for trigeminal neuralgia: A technical note and anatomical study

    PubMed Central

    da Silva, Otávio T.; de Almeida, César C.; Iglesio, Ricardo F.; de Navarro, Jessie M.; Teixeira, Manoel J.; Duarte, Kleber P.

    2016-01-01

    Background: In this article, the authors described their experience in microvascular decompression for trigeminal neuralgia. Methods: The microvascular decompression technique used in the authors’ institution is described in a step by step manner with some illustrative cases as well as a cadaver dissection to highlight the differences with other previously described techniques. Results: Since 2013, 107 patients were operated in the Neurosurgery Division of the University of São Paulo using the described technique, with a shorter operative time and avoiding cerebellar retractor compared with classic techniques. Conclusion: Our modified microvascular decompression technique for trigeminal neuralgia can be used with safety and efficiency for treating trigeminal neuralgia. PMID:27625893

  16. Surgical variation of microvascular decompression for trigeminal neuralgia: A technical note and anatomical study

    PubMed Central

    da Silva, Otávio T.; de Almeida, César C.; Iglesio, Ricardo F.; de Navarro, Jessie M.; Teixeira, Manoel J.; Duarte, Kleber P.

    2016-01-01

    Background: In this article, the authors described their experience in microvascular decompression for trigeminal neuralgia. Methods: The microvascular decompression technique used in the authors’ institution is described in a step by step manner with some illustrative cases as well as a cadaver dissection to highlight the differences with other previously described techniques. Results: Since 2013, 107 patients were operated in the Neurosurgery Division of the University of São Paulo using the described technique, with a shorter operative time and avoiding cerebellar retractor compared with classic techniques. Conclusion: Our modified microvascular decompression technique for trigeminal neuralgia can be used with safety and efficiency for treating trigeminal neuralgia.

  17. Metagenomics and other Methods for Measuring Antibiotic Resistance in Agroecosystems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: There is broad concern regarding antibiotic resistance on farms and in fields, however there is no standard method for defining or measuring antibiotic resistance in environmental samples. Methods: We used metagenomic, culture-based, and molecular methods to characterize the amount, t...

  18. 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

  19. Apparatus and method for measuring and imaging surface resistance

    DOEpatents

    Martens, Jon S.; Hietala, Vincent M.; Hohenwarter, Gert K. G.

    1993-08-24

    Apparatus and method for determining and imaging superconductor surface resistance. The apparatus comprises modified Gaussian confocal resonator structure with the sample remote from the radiating mirror. Surface resistance is determined by analyzing and imaging reflected microwaves; imaging reveals anomalies due to surface impurities, non-stoichiometry, and the like, in the surface of the superconductor.

  20. Three inoculation methods for evaluating Sclerotinia blight resistance in peanut

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Laboratory-based assays for screening germplasm for resistance to Sclerotinia blight in peanuts can be conducted year-round, and thus may accelerate progress in breeding for resistant plants. Three previously proposed inoculation methods (using main stems of intact plants, detached main stems, or de...

  1. The ratio method of estimating water resistivity and TDS from resistivity logs

    USGS Publications Warehouse

    Jorgensen, D.G.

    1996-01-01

    It is a general belief that useful estimates of total dissolved solids concentrations of ground water cannot be made from borehole geophysical logs. A case study of estimating total dissolved solids concentration of ground water in the local area using the ratio method yielded estimates with an average error of less than 25 percent. The results do not support the hypothesis that useful estimates of total dissolved solids concentration cannot be made from borehole geophysical logs. The case study included a comparison of estimates of total dissolved solids concentration utilizing a resistivity of the mud input versus using resistivity of the mud filtrate input. Estimates made using resistivity of mud had a correlation coefficient of 0.97 whereas estimates using resistivity of mud filtrate had a correlation coefficient of only 0.27. The results from the case study suggest that at least in some cases the resistivity of the mud (Rm) produce a better estimate of the resistivity of water (Rw) in the fully flushed zone than an estimate using the resistivity of the mud filtrate Rmf. The ratio method can be easily used to estimate ground-water resistivity and total dissolved solids concentration of the formation water based only on data from resistivity logs. The advantage of the method is that data on porosity, cementation exponent, temperature, and volume of clay are not required. The method, which has been used by the oil industry to crudely estimate water resistivity, is based in part on the ratio of the resistivity of a fully water-saturated formation to the resistivity of the fully flushed zone adjacent to the annulus in a mud-filled borehole. The method, which is very robust, requires only an estimate of the resistivity of a fully water-saturated formation from a deep looking induction or resistivity log, an estimate of the resistivity of the fully flushed zone from a microresistivity or short normal log, and a measurement of resistivity of the mud or mud filtrate

  2. Interactions of the Gasotransmitters Contribute to Microvascular Tone (Dys)regulation in the Preterm Neonate

    PubMed Central

    Dyson, Rebecca M.; Palliser, Hannah K.; Latter, Joanna L.; Kelly, Megan A.; Chwatko, Grazyna; Glowacki, Rafal; Wright, Ian M. R.

    2015-01-01

    Background & Aims Hydrogen sulphide (H2S), nitric oxide (NO), and carbon monoxide (CO) are involved in transitional microvascular tone dysregulation in the preterm infant; however there is conflicting evidence on the interaction of these gasotransmitters, and their overall contribution to the microcirculation in newborns is not known. The aim of this study was to measure the levels of all 3 gasotransmitters, characterise their interrelationships and elucidate their combined effects on microvascular blood flow. Methods 90 preterm neonates were studied at 24h postnatal age. Microvascular studies were performed by laser Doppler. Arterial COHb levels (a measure of CO) were determined through co-oximetry. NO was measured as nitrate and nitrite in urine. H2S was measured as thiosulphate by liquid chromatography. Relationships between levels of the gasotransmitters and microvascular blood flow were assessed through partial correlation controlling for the influence of gestational age. Structural equation modelling was used to examine the combination of these effects on microvascular blood flow and derive a theoretical model of their interactions. Results No relationship was observed between NO and CO (p = 0.18, r = 0.18). A positive relationship between NO and H2S (p = 0.008, r = 0.28) and an inverse relationship between CO and H2S (p = 0.01, r = -0.33) exists. Structural equation modelling was used to examine the combination of these effects on microvascular blood flow. The model with the best fit is presented. Conclusions The relationships between NO and H2S, and CO and H2S may be of importance in the preterm newborn, particularly as NO levels in males are associated with higher H2S levels and higher microvascular blood flow and CO in females appears to convey protection against vascular dysregulation. Here we present a theoretical model of these interactions and their overall effects on microvascular flow in the preterm newborn, upon which future mechanistic studies may

  3. Microorganisms having enhanced resistance to acetate and methods of use

    SciTech Connect

    Brown, Steven D; Yang, Shihui

    2014-10-21

    The present invention provides isolated or genetically modified strains of microorganisms that display enhanced resistance to acetate as a result of increased expression of a sodium proton antiporter. The present invention also provides methods for producing such microbial strains, as well as related promoter sequences and expression vectors. Further, the present invention provides methods of producing alcohol from biomass materials by using microorganisms with enhanced resistance to acetate.

  4. Microvascular endothelium and pericytes: high yield, low passage cultures.

    PubMed

    Carson, M P; Haudenschild, C C

    1986-06-01

    Cultured microvascular endothelial cells (MEC) have become a valuable model for studies of microvascular physiology and pathology. Most current techniques involve manual removal of undesirable cell types or cloning, require one to several months, and yield high population doubling level cultures derived from a relatively small sample of the original population. We have devised a technique to more rapidly produce larger numbers of MEC. This method provided primary cultures consisting predominantly of MEC within 1 wk. The technique involves selective aspiration of gray matter from the bovine cerebral cortex followed by homogenization, sieving, enzymatic dissociation, and then dense plating (10(4) to 10(5) vessel fragments/cm2) onto gelatin- or fibronectin-coated plastic. Typical yields were 0.1 to 0.5 X 10(6) fragments/g of aspirated gray matter. The optimal culture medium for these cells was 15% equine plasma derived serum, 20% conditioned medium, 2% retinal extract, 60% fresh medium, and 500 micrograms/ml heparin. Cells attached within 24 h, well-spread colonies were present within 1 to 2 d, and cultures approached confluence within 2 to 3 d. Alkaline phosphatase staining confirmed the microvascular origin of the material plated. Morphology, Factor VIII-related antigen staining and 1,1'-dioctacecyl-3,3,3'3,-tetramethyl-indocarbocyanine perchlorate acetylated low density lipoprotein uptake suggested that MEC predominated. Cultures could be passaged and additionally purified by sequential exposure to pancreatin and trypsin-EDTA. Pancreatin selectively removed MEC colonies leaving a relatively homogeneous pericyte population. The relative ease with which such cultures can be produced should facilitate the in vitro study of brain microvascular function and may also provide insights useful for growing MEC from other vascular beds.

  5. [Antibiotic resistance in Helicobacter pylori and molecular methods for the detection of resistance].

    PubMed

    Demiray, Ebru; Yilmaz, Ozlem

    2005-07-01

    Helicobacter pylori which is the major agent causing peptic ulcer, gastric cancer and gastric lymphoma, is identified as a class I carcinogen. Invasive and non-invasive tests have been used in the diagnosis of H. pylori infection. Clarithromycin resistance in H. pylori strains is increasing nowadays, thus leading to failures in eradication therapy. Fluorescence in situ hybridization (FISH) method which can simultaneously detect the presence of H. pylori and clarithromycin resistance is a non-culture dependent molecular technique. In this review article the prevalence and clinical outcome of antibiotic resistance in H. pylori, molecular mechanisms of the resistance and molecular methods to detect the resistance, with priority of FISH technique have been discussed. PMID:16358500

  6. Microvascular Abnormality in Schizophrenia as Shown by Retinal Imaging

    PubMed Central

    Meier, Madeline H.; Shalev, Idan; Moffitt, Terrie E.; Kapur, Shitij; Keefe, Richard S.E.; Wong, Tien; Belsky, Daniel W.; Harrington, HonaLee; Hogan, Sean; Houts, Renate; Caspi, Avshalom; Poulton, Richie

    2013-01-01

    Objective Retinal and cerebral microvessels are structurally and functionally homologous, but, unlike cerebral microvessels, retinal microvessels can be noninvasively measured in vivo via retinal imaging. Here we test the hypothesis that individuals with schizophrenia show microvascular abnormality and evaluate the utility of retinal imaging as a tool for future schizophrenia research. Methods Participants were members of the Dunedin Study, a population-representative cohort followed from birth with 95% retention. Study members underwent retinal imaging at age 38 years. We assessed retinal arteriolar and venular caliber for all members of the cohort, including individuals who developed schizophrenia. Results Study members who developed schizophrenia were distinguished by wider retinal venules, suggesting microvascular abnormality reflective of insufficient brain oxygen supply. Analyses that controlled for confounding health conditions suggested that wider retinal venules are not simply an artifact of co-occurring health problems in schizophrenia patients. Wider venules were also associated with a dimensional measure of adult psychosis symptoms and with psychosis symptoms reported in childhood. Conclusions Findings provide initial support for the hypothesis that individuals with schizophrenia show microvascular abnormality. Moreover, results suggest that the same vascular mechanisms underlie subthreshold symptoms and clinical disorder and that these associations may begin early in life. These findings highlight the promise of retinal imaging as a tool for understanding the pathogenesis of schizophrenia. PMID:24030514

  7. Microfabrication of cylindrical microfluidic channel networks for microvascular research.

    PubMed

    Huang, Zhouchun; Li, Xiang; Martins-Green, Manuela; Liu, Yuxin

    2012-10-01

    Current methods for formation of microvascular channel scaffolds are limited with non-circular channel cross-sections, complicated fabrication, and less flexibility in microchannel network design. To address current limitations in the creation of engineered microvascular channels with complex three-dimensional (3-D) geometries in the shape of microvessels, we have developed a reproducible, cost-effective, and flexible micromanufacturing process combined with photolithographic reflowable photoresist and soft lithography techniques to fabricate cylindrical microchannel and networks. A positive reflowable photoresist AZ P4620 was used to fabricate a master microchannel mold with semi-circular cross-sections. By the alignment and bonding of two polydimethylsiloxane (PDMS) microchannels replicated from the master mold together, a cylindrical microchannel or microchannel network was created. Further examination of the channel dimensions and surface profiles at different branching levels showed that the shape of the microfluidic channel was well approximated by a semi-circular surface, and a multi-level, multi-depth channel network was created. In addition, a computational fluidic dynamics (CFD) model was used to simulate shear flows and corresponding pressure distributions inside of the microchannel and channel network based on the dimensions of the fabricated channels. The fabricated multi-depth cylindrical microchannel network can provide platforms for the investigation of microvascular cells growing inside of cylindrical channels under shear flows and lumen pressures, and work as scaffolds for the investigation of morphogenesis and tubulogenesis. PMID:22729782

  8. Microfabrication of cylindrical microfluidic channel networks for microvascular research.

    PubMed

    Huang, Zhouchun; Li, Xiang; Martins-Green, Manuela; Liu, Yuxin

    2012-10-01

    Current methods for formation of microvascular channel scaffolds are limited with non-circular channel cross-sections, complicated fabrication, and less flexibility in microchannel network design. To address current limitations in the creation of engineered microvascular channels with complex three-dimensional (3-D) geometries in the shape of microvessels, we have developed a reproducible, cost-effective, and flexible micromanufacturing process combined with photolithographic reflowable photoresist and soft lithography techniques to fabricate cylindrical microchannel and networks. A positive reflowable photoresist AZ P4620 was used to fabricate a master microchannel mold with semi-circular cross-sections. By the alignment and bonding of two polydimethylsiloxane (PDMS) microchannels replicated from the master mold together, a cylindrical microchannel or microchannel network was created. Further examination of the channel dimensions and surface profiles at different branching levels showed that the shape of the microfluidic channel was well approximated by a semi-circular surface, and a multi-level, multi-depth channel network was created. In addition, a computational fluidic dynamics (CFD) model was used to simulate shear flows and corresponding pressure distributions inside of the microchannel and channel network based on the dimensions of the fabricated channels. The fabricated multi-depth cylindrical microchannel network can provide platforms for the investigation of microvascular cells growing inside of cylindrical channels under shear flows and lumen pressures, and work as scaffolds for the investigation of morphogenesis and tubulogenesis.

  9. 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

  10. A new measurement method for the dynamic resistance signal during the resistance spot welding process

    NASA Astrophysics Data System (ADS)

    Wang, Lijing; Hou, Yanyan; Zhang, Hongjie; Zhao, Jian; Xi, Tao; Qi, Xiangyang; Li, Yafeng

    2016-09-01

    To measure the dynamic resistance signal during the resistance spot welding process, some original work was carried out and a new measurement method was developed. Compared with the traditional method, using the instantaneous electrode voltage and welding current at peak current point in each half cycle, the resistance curve from the newly proposed method can provide more details of the dynamic resistance changes over time. To test the specific performance of the proposed method, a series of welding experiments were carried out and the tensile shear strengths of the weld samples were measured. Then, the measurement error of the proposed method was evaluated. Several features were extracted from the dynamic resistance curves. The correlations between the extracted features and weld strength were analyzed and the results show that these features are closely related to the weld strength and they can be used for welding quality monitoring. Moreover, the dynamic resistance curve from the newly proposed method can also be used to monitor some abnormal welding conditions.

  11. The Use of Resistivity Methods in Terrestrial Forensic Searches

    NASA Astrophysics Data System (ADS)

    Wolf, R. C.; Raisuddin, I.; Bank, C.

    2013-12-01

    The increasing use of near-surface geophysical methods in forensic searches has demonstrated the need for further studies to identify the ideal physical, environmental and temporal settings for each geophysical method. Previous studies using resistivity methods have shown promising results, but additional work is required to more accurately interpret and analyze survey findings. The Ontario Provincial Police's UCRT (Urban Search and Rescue; Chemical, Biolgical, Radiological, Nuclear and Explosives; Response Team) is collaborating with the University of Toronto and two additional universities in a multi-year study investigating the applications of near-surface geophysical methods to terrestrial forensic searches. In the summer of 2012, on a test site near Bolton, Ontario, the OPP buried weapons, drums and pigs (naked, tarped, and clothed) to simulate clandestine graves and caches. Our study aims to conduct repeat surveys using an IRIS Syscal Junior with 48 electrode switching system resistivity-meter. These surveys will monitor changes in resistivity reflecting decomposition of the object since burial, and identify the strengths and weaknesses of resistivity when used in a rural, clandestine burial setting. Our initial findings indicate the usefulness of this method, as prominent resistivity changes have been observed. We anticipate our results will help to assist law enforcement agencies in determining the type of resistivity results to expect based on time since burial, depth of burial and state of dress of the body.

  12. Perfusion MRI Derived Indices of Microvascular Shunting and Flow Control Correlate with Tumor Grade and Outcome in Patients with Cerebral Glioma

    PubMed Central

    Tietze, Anna; Mouridsen, Kim; Lassen-Ramshad, Yasmin; Østergaard, Leif

    2015-01-01

    Objectives Deficient microvascular blood flow control is thought to cause tumor hypoxia and increase resistance to therapy. In glioma patients, we tested whether perfusion-weighted MRI (PWI) based indices of microvascular flow control provide more information on tumor grade and patient outcome than does the established PWI angiogenesis marker, cerebral blood volume (CBV). Material and Methods Seventy-two glioma patients (sixty high-grade, twelve low-grade gliomas) were included. Capillary transit time heterogeneity (CTH) and the coefficient of variation (COV), its ratio to blood mean transit time, provide indices of microvascular flow control and the extent to which oxygen can be extracted by tumor tissue. The ability of these parameters and CBV to differentiate tumor grade were assessed by receiver operating characteristic curves and logistic regression. Their ability to predict time to progression and overall survival was examined by the Cox proportional-hazards regression model, and by survival curves using log-rank tests. Results The best prediction of grade (AUC = 0.876; p < 0.05) was achieved by combining knowledge of CBV and CTH in the enhancing tumor and peri-focal edema, and patients with glioblastoma multiforme were identified best by CTH (AUC = 0.763; p<0.001). CTH outperformed CBV and COV in predicting time to progression and survival in all gliomas and in a subgroup consisting of only high-grade gliomas. Conclusion Our study confirms the importance of microvascular flow control in tumor growth by demonstrating that determining CTH improves tumor grading and outcome prediction in glioma patients compared to CBV alone. PMID:25875182

  13. Method of preparing corrosion resistant composite materials

    DOEpatents

    Kaun, Thomas D.

    1993-01-01

    Method of manufacture of ceramic materials which require stability in severely-corrosive environment having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These surfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  14. Coronary microvascular obstruction in acute myocardial infarction.

    PubMed

    Niccoli, Giampaolo; Scalone, Giancarla; Lerman, Amir; Crea, Filippo

    2016-04-01

    The success of a primary percutaneous intervention (PCI) in the setting of ST elevation myocardial infarction depends on the functional and structural integrity of coronary microcirculation. Coronary microvascular dysfunction and obstruction (CMVO) occurs in up to half of patients submitted to apparently successful primary PCI and is associated to a much worse outcome. The current review summarizes the complex mechanisms responsible for CMVO, including pre-existing coronary microvascular dysfunction, and highlights the current limitations in the assessment of microvascular function. More importantly, at the light of the substantial failure of trials hitherto published on the treatment of CMVO, this review proposes a novel integrated therapeutic approach, which should overcome the limitations of previous studies.

  15. Method of stimulus combination impacts resistance to extinction.

    PubMed

    Podlesnik, Christopher A; Bai, John Y H

    2015-07-01

    Reinforcing an alternative response in the presence of the stimuli governing a target response increases resistance to extinction of target responding, relative to training target responding on its own. Conversely, training alternative and target responses in the presence of different stimuli and combining those stimuli only decreases resistance to extinction of target responding, relative to target responding on its own. The present study assessed how different methods of combining discriminative stimuli influence resistance to extinction of responding in pigeons. As in previous studies, combining stimuli across different keys only decreased resistance to extinction of target responding relative to target responding on its own. In comparison, combining stimuli on the same key initially increased resistance to extinction of target responding, but repeated tests resulted in similar levels of responding as target responding with stimuli combined on separate keys. Moreover, greater overall reinforcement rates produced greater resistance to extinction with both methods of combining stimuli, consistent with behavioral momentum theory. These findings reveal several behavioral processes influence the outcome of combining stimuli--including perceptual processes, discriminative control by contingencies, response competition, and behavioral momentum. PMID:25929758

  16. Method of stimulus combination impacts resistance to extinction.

    PubMed

    Podlesnik, Christopher A; Bai, John Y H

    2015-07-01

    Reinforcing an alternative response in the presence of the stimuli governing a target response increases resistance to extinction of target responding, relative to training target responding on its own. Conversely, training alternative and target responses in the presence of different stimuli and combining those stimuli only decreases resistance to extinction of target responding, relative to target responding on its own. The present study assessed how different methods of combining discriminative stimuli influence resistance to extinction of responding in pigeons. As in previous studies, combining stimuli across different keys only decreased resistance to extinction of target responding relative to target responding on its own. In comparison, combining stimuli on the same key initially increased resistance to extinction of target responding, but repeated tests resulted in similar levels of responding as target responding with stimuli combined on separate keys. Moreover, greater overall reinforcement rates produced greater resistance to extinction with both methods of combining stimuli, consistent with behavioral momentum theory. These findings reveal several behavioral processes influence the outcome of combining stimuli--including perceptual processes, discriminative control by contingencies, response competition, and behavioral momentum.

  17. Metabolic Actions of Angiotensin II and Insulin: A Microvascular Endothelial Balancing Act

    PubMed Central

    Muniyappa, Ranganath; Yavuz, Shazene

    2012-01-01

    Metabolic actions of insulin to promote glucose disposal are augmented by nitric oxide (NO)-dependent increases in microvascular blood flow to skeletal muscle. The balance between NO-dependent vasodilator actions and endothelin-1-dependent vasoconstrictor actions of insulin is regulated by phosphatidylinositol 3-kinase-dependent (PI3K) - and mitogen-activated protein kinase (MAPK)-dependent signaling in vascular endothelium, respectively. Angiotensin II acting on AT2 receptor increases capillary blood flow to increase insulin-mediated glucose disposal. In contrast, AT1 receptor activation leads to reduced NO bioavailability, impaired insulin signaling, vasoconstriction, and insulin resistance. Insulin-resistant states are characterized by dysregulated local renin-angiotensin-aldosterone system (RAAS). Under insulin-resistant conditions, pathway-specific impairment in PI3K-dependent signaling may cause imbalance between production of NO and secretion of endothelin-1, leading to decreased blood flow, which worsens insulin resistance. Similarly, excess AT1 receptor activity in the microvasculature may selectively impair vasodilation while simultaneously potentiating the vasoconstrictor actions of insulin. Therapeutic interventions that target pathway-selective impairment in insulin signaling and the imbalance in AT1 and AT2 receptor signaling in microvascular endothelium may simultaneously ameliorate endothelial dysfunction and insulin resistance. In the present review, we discuss molecular mechanisms in the endothelium underlying microvascular and metabolic actions of insulin and Angiotensin II, the mechanistic basis for microvascular endothelial dysfunction and insulin resistance in RAAS dysregulated clinical states, and the rationale for therapeutic strategies that restore the balance in vasodilator and constrictor actions of insulin and Angiotensin II in the microvasculature. PMID:22684034

  18. Computational design of microvascular biomimetic materials

    NASA Astrophysics Data System (ADS)

    Aragon, Alejandro Marcos

    Biomimetic microvascular materials are increasingly considered for a variety of autonomic healing, cooling and sensing applications. The microvascular material of interest in this work consists of a network of hollow microchannels, with diameters as small as 10 mum, embedded in a polymeric matrix. Recent advances in the manufacturing of this new class of materials have allowed for the creation of very complex 2D and 3D structures. The computational design of such network structures, which is the focus of this work, involves a set of particular challenges, including a large number of design variables (e.g., topology of the network, number of diameters to consider and their sizes) that define the network, and a large number of multidisciplinary objective functions and constraints that drive the optimization process. The computational design tool to be developed must be capable of capturing the trade-off between the different objective and constraint functions, as, for example, networks designed for flow efficiency are likely to have a topology that is very different from those designed for structural integrity or thermal control. In this work, we propose to design these materials using Genetic Algorithms (GAs), the most common methodology within a broader category of Evolutionary Algorithms (EAs). GAs can be combined with a Pareto-selection mechanism to create Multi-Objective Genetic Algorithms (MOGAs), which enable the optimization of an arbitrary number of objective functions. As a result, a Pareto-optimal front is obtained, where all candidates are optimal solutions to the optimization problem. Adding a procedure to deal with constraints results in a powerful tool for multi-objective constrained optimization. The method allows the use of discrete variable problems and it does not require any a priori knowledge of the optimal solution. Furthermore, GAs search the entire decision space so the optimal solutions found are likely to be global. The

  19. Roles of LOX-1 in microvascular dysfunction.

    PubMed

    Lubrano, Valter; Balzan, Silvana

    2016-05-01

    Studies from human and animal models with metabolic disease and hypertension highlight atrophic remodeling, reduced lumen size and thinner vascular walls of microvessels with profound density reduction. This impaired vascular response limits the perfusion of peripheral tissues inducing organ damage. These conditions are strongly associated with oxidative stress and in particular with the up-regulation of lectin-like oxidized low density lipoprotein receptor-1 (LOX-1). Several factors such as cytokines, shear stress, and advanced glycation end-products, especially oxLDL, can up-regulate LOX-1. The activation of this receptor induces the production of adhesion molecules, cytokines and the release of reactive oxygen species via NADPH oxidase. LOX-1 is considered a potent mediator of endothelial dysfunction and it is significantly associated with reduced microvascular endothelium NO-dependent vasodilation in hypercholesterolemia and hypertension. Microvascular endothelial cells increased the expression of IL-6 in association with the increased concentration of LDL and its degree of oxidation. Moreover, increased IL-6 levels are associated with up-regulation of LOX-1 in a dose-dependent manner. Another consequence of microvascular inflammation is the generation of small amounts of ROS, similar to those induced by low concentration of oxLDL (<5 μg/mL) which induces capillary tube formation of endothelial cells, through LOX-1 up-regulation. In light of its central role, LOX-1 represents an attractive therapeutic target for the treatment of human atherosclerotic diseases and microvascular disorders. PMID:26907636

  20. Method Analysis of Microbial-Resistant Gypsum Products

    EPA Science Inventory

    Method Analysis of Microbial-Resistant Gypsum ProductsD.A. Betancourt1, T.R.Dean1, A. Evans2, and G.Byfield2 1. US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory; RTP, NC 277112. RTI International, RTP, NCSeveral...

  1. Brain microvascular function during cardiopulmonary bypass

    SciTech Connect

    Sorensen, H.R.; Husum, B.; Waaben, J.; Andersen, K.; Andersen, L.I.; Gefke, K.; Kaarsen, A.L.; Gjedde, A.

    1987-11-01

    Emboli in the brain microvasculature may inhibit brain activity during cardiopulmonary bypass. Such hypothetical blockade, if confirmed, may be responsible for the reduction of cerebral metabolic rate for glucose observed in animals subjected to cardiopulmonary bypass. In previous studies of cerebral blood flow during bypass, brain microcirculation was not evaluated. In the present study in animals (pigs), reduction of the number of perfused capillaries was estimated by measurements of the capillary diffusion capacity for hydrophilic tracers of low permeability. Capillary diffusion capacity, cerebral blood flow, and cerebral metabolic rate for glucose were measured simultaneously by the integral method, different tracers being used with different circulation times. In eight animals subjected to normothermic cardiopulmonary bypass, and seven subjected to hypothermic bypass, cerebral blood flow, cerebral metabolic rate for glucose, and capillary diffusion capacity decreased significantly: cerebral blood flow from 63 to 43 ml/100 gm/min in normothermia and to 34 ml/100 gm/min in hypothermia and cerebral metabolic rate for glucose from 43.0 to 23.0 mumol/100 gm/min in normothermia and to 14.1 mumol/100 gm/min in hypothermia. The capillary diffusion capacity declined markedly from 0.15 to 0.03 ml/100 gm/min in normothermia but only to 0.08 ml/100 gm/min in hypothermia. We conclude that the decrease of cerebral metabolic rate for glucose during normothermic cardiopulmonary bypass is caused by interruption of blood flow through a part of the capillary bed, possibly by microemboli, and that cerebral blood flow is an inadequate indicator of capillary blood flow. Further studies must clarify why normal microvascular function appears to be preserved during hypothermic cardiopulmonary bypass.

  2. Method for starting operation of a resistance melter

    DOEpatents

    Chapman, Christopher Charles

    1977-01-01

    A method for starting the operation of a resistance furnace, where heating occurs by passing a current through the charge between two furnace electrodes and the charge is a material which is essentially electrically nonconductive when in a solid physical state but which becomes more electrically conductive when in a molten physical state, by connecting electrical resistance heating wire between the furnace electrodes, placing the wire in contact with the charge material between the electrodes and passing a current through the wire to heat the wire to a temperature sufficient to melt the material between the furnace electrodes so that as the material melts, current begins to pass between the electrodes through the melted material, further heating and melting more material until all current between the electrodes passes through the charge material without the aid or presence of the resistance element.

  3. Method for applying photographic resists to otherwise incompatible substrates

    NASA Technical Reports Server (NTRS)

    Fuhr, W. (Inventor)

    1981-01-01

    A method for applying photographic resists to otherwise incompatible substrates, such as a baking enamel paint surface, is described wherein the uncured enamel paint surface is coated with a non-curing lacquer which is, in turn, coated with a partially cured lacquer. The non-curing lacquer adheres to the enamel and a photo resist material satisfactorily adheres to the partially cured lacquer. Once normal photo etching techniques are employed the lacquer coats can be easily removed from the enamel leaving the photo etched image. In the case of edge lighted instrument panels, a coat of uncured enamel is placed over the cured enamel followed by the lacquer coats and the photo resists which is exposed and developed. Once the etched uncured enamel is cured, the lacquer coats are removed leaving an etched panel.

  4. Skeletal muscle microvascular function in girls with Turner syndrome

    PubMed Central

    West, Sarah L.; O'Gorman, Clodagh S.; Elzibak, Alyaa H.; Caterini, Jessica; Noseworthy, Michael D.; Rayner, Tammy; Hamilton, Jill; Wells, Greg D.

    2014-01-01

    Background Exercise intolerance is prevalent in individuals with Turner Syndrome (TS). We recently demonstrated that girls with TS have normal aerobic but altered skeletal muscle anaerobic metabolism compared to healthy controls (HC). The purpose of this study was to compare peripheral skeletal muscle microvascular function in girls with TS to HC after exercise. We hypothesized that girls with TS would have similar muscle blood-oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) signal responses during recovery from exercise compared to HC. Methods Thirteen TS participants and 8 HC completed testing. BOLD MRI was used to measure skeletal muscle microvascular response during 60 second recovery, following 60 s of exercise at 65% of maximal workload. Exercise and recovery were repeated four times, and the BOLD signal time course was fit to a four-parameter sigmoid function. Results Participants were 13.7 ± 3.1 years old and weighed 47.9 ± 14.6 kg. The mean change in BOLD signal intensity following exercise at the end of recovery, the mean response time of the function/the washout of deoxyhemoglobin, and the mean half-time of recovery were similar between the TS and HC groups. Conclusions Our results demonstrate that compared to HC, peripheral skeletal muscle microvascular function following exercise in girls with TS is not impaired. General significance This study supports the idea that the aerobic energy pathway is not impaired in children with TS in response to submaximal exercise. Other mechanisms are likely responsible for exercise intolerance in TS; this needs to be further investigated. PMID:26676172

  5. Segmental resection of the anterior mandibular arch with fibular microvascular reconstruction.

    PubMed

    Dierks, E J; Karakourtis, M H

    1997-09-01

    Segmental mandibular resection should be undertaken if there is a demonstrable invasion by cancer or if such invasion is suspected. Before the advent of microvascular free flaps, immediate osseous reconstruction of the anterior mandible was technically demanding and unreliable. Mandibular reconstruction with microvascular free flaps is no longer a novelty, nor is it reserved for unusually large resections. It has become the method of choice for the immediate reconstruction of defects resulting from mandibular cancer. This technique is particularly well-suited for defects of the anterior mandibular arch.

  6. Method of making sulfur-resistant composite metal membranes

    DOEpatents

    Way, J Douglas [Boulder, CO; Lusk, Mark [Golden, CO; Thoen, Paul [Littleton, CO

    2012-01-24

    The invention provides thin, hydrogen-permeable, sulfur-resistant membranes formed from palladium or palladium-alloy coatings on porous, ceramic or metal supports. Also disclosed are methods of making these membranes via sequential electroless plating techniques, wherein the method of making the membrane includes decomposing any organic ligands present on the substrate, reducing the palladium crystallites on the substrate to reduced palladium crystallites, depositing a film of palladium metal on the substrate and then depositing a second, gold film on the palladium film. These two metal films are then annealed at a temperature between about 200.degree. C. and about 1200.degree. C. to form a sulfur-resistant, composite PdAu alloy membrane.

  7. Treatment of hemimasticatory spasm with microvascular decompression.

    PubMed

    Wang, Yong-Nan; Dou, Ning-Ning; Zhou, Qiu-Meng; Jiao, Wei; Zhu, Jin; Zhong, Jun; Li, Shi-Ting

    2013-01-01

    Hemimasticatory spasm is a rare disorder characterized by paroxysmal involuntary contraction of the jaw-closing muscles. As the ideology and pathogenesis of the disease are still unclear, there has been no treatment that could give rise to a good outcome so far. Herein, we tried to use surgical management to cure the disease. Six patients with the disease were included in this study. These patients underwent microvascular decompression of the motor fibers of the trigeminal root. After the operation, all faces of the patients felt relaxed at varied degrees, except for 1 patient. Our study showed that microvascular decompression of the trigeminal nerve could lead to a better outcome. However, a control study with a large sample is needed before this technique is widely used.

  8. Coronary Microvascular Dysfunction and Microvascular Angina: A Systematic Review of Therapies

    PubMed Central

    Marinescu, Mark A; Löffler, Adrián I.; Ouellette, Michelle; Smith, Lavone; Kramer, Christopher M.; Bourque, Jamieson

    2015-01-01

    Angina without coronary artery disease (CAD) has substantial morbidity and is present in 10–30% of patients undergoing angiography. Coronary microvascular dysfunction (CMD) is present in 50–65% of these patients. The optimal treatment of this cohort is undefined. We performed a systematic review to evaluate treatment strategies for objectively defined CMD in the absence of CAD. We included studies assessing therapy in human subjects with angina and coronary flow reserve (CFR) or myocardial perfusion reserve (MPR) <2.5 by positron emission tomography (PET), cardiac magnetic resonance imaging (CMR), dilution methods, or intracoronary Doppler in the absence of coronary artery stenosis ≥50% or structural heart disease. Only 8 articles met strict inclusion criteria. The articles were heterogeneous, using different treatments, end-points, and definitions of CMD. Small sample sizes severely limit the power of these studies, with an average of 11 patients per analysis. Studies evaluating, sildenafil, quinapril, estrogen, and transcutaneous electrical nerve stimulation (TENS) application demonstrated benefits in their respective endpoints. No benefit was found with L-arginine, doxazosin, pravastatin, and diltiazem. Our systematic review highlights that there is little data to support therapies for CMD. We assess the data meeting rigorous inclusion criteria and review the related but excluded literature. We additionally describe the next steps needed to address this research gap, including a standardized definition of CMD, routine assessment of CMD in studies of chest pain without obstructive CAD, and specific therapy assessment in the population with confirmed CMD. PMID:25677893

  9. Predictors of Microvascular Invasion in Hepatocellular Carcinoma.

    PubMed

    Yamashita, Yo-Ichi; Shirabe, Ken; Aishima, Shinichi; Maehara, Yoshihiko

    2015-09-01

    This chapter covers a range of important topics in the evaluation of the microvascular invasion (MVI) in hepatocellular carcinoma (HCC) before treatment. The malignant potential of HCC is reflected by the types of MVI such as portal venous (vp), hepatic vein (vv) or bile duct (b) infiltration. The identification of the type of MVI in HCC has a key role in decisions regarding the effective treatment of HCC. Here, we describe the possible and important predictors of MVI in HCC. PMID:26398341

  10. Fabrication of 3-dimensional multicellular microvascular structures

    PubMed Central

    Barreto-Ortiz, Sebastian F.; Fradkin, Jamie; Eoh, Joon; Trivero, Jacqueline; Davenport, Matthew; Ginn, Brian; Mao, Hai-Quan; Gerecht, Sharon

    2015-01-01

    Despite current advances in engineering blood vessels over 1 mm in diameter and the existing wealth of knowledge regarding capillary bed formation, studies for the development of microvasculature, the connecting bridge between them, have been extremely limited so far. Here, we evaluate the use of 3-dimensional (3D) microfibers fabricated by hydrogel electrospinning as templates for microvascular structure formation. We hypothesize that 3D microfibers improve extracellular matrix (ECM) deposition from vascular cells, enabling the formation of freestanding luminal multicellular microvasculature. Compared to 2-dimensional cultures, we demonstrate with confocal microscopy and RT-PCR that fibrin microfibers induce an increased ECM protein deposition by vascular cells, specifically endothelial colony-forming cells, pericytes, and vascular smooth muscle cells. These ECM proteins comprise different layers of the vascular wall including collagen types I, III, and IV, as well as elastin, fibronectin, and laminin. We further demonstrate the achievement of multicellular microvascular structures with an organized endothelium and a robust multicellular perivascular tunica media. This, along with the increased ECM deposition, allowed for the creation of self-supporting multilayered microvasculature with a distinct circular lumen following fibrin microfiber core removal. This approach presents an advancement toward the development of human microvasculature for basic and translational studies.—Barreto-Ortiz, S. F., Fradkin, J., Eoh, J., Trivero, J., Davenport, M., Ginn, B., Mao, H.-Q., Gerecht, S. Fabrication of 3-dimensional multicellular microvascular structures. PMID:25900808

  11. Test method to measure resistance towards fragmentation by studded tires

    NASA Astrophysics Data System (ADS)

    Viman, L.

    1995-01-01

    In the Nordic countries most cars are equipped with studded tires during the winter. The studs increase the wear on the road surfaces and a special test method has been developed to measure the aggregates' resistance towards fragmentation by studded tires. The method has proven to correlate very well with the actual wear on the road surfaces. The Nordic countries Sweden, Norway and Finland have agreed to propose this method as a European Standard test method. One reason is to be able to set requirements on aggregates to be used in countries where studded tires are allowed. A cross-testing project regarding this Nordic abrasion test for studded tires was set up in order to determine the repeatability and the reproducibility of the methods to become European Standard.

  12. Microvascular Perfusion and Intramuscular Temperature of the Calf During Cooling

    PubMed Central

    Selkow, Noelle M; Day, Carly; Liu, Zhenqi; Hart, Joseph M; Hertel, Jay; Saliba, Susan A

    2011-01-01

    Purpose To examine how the microvascularity of the gastrocnemius changed after a cryotherapy intervention based on subcutaneous tissue thickness. A secondary purpose was to compare intramuscular temperature change to subcutaneous tissue thickness. Methods This was a single-blinded crossover study; each subject received both conditions (cryotherapy or sham). Subjects had baseline measurements of blood flow, blood volume, and intramuscular temperature recorded at 1cm into the muscle belly of the medial gastrocnemius. The randomized condition was applied for 10, 25, 40, or 60min depending on subcutaneous tissue thickness. Immediate post treatment microvascular measures were taken. After a designated rewarm period, again based on subcutaneous tissue thickness, measurements were retaken. At least 48 hours separated the two conditions. Results There were significant condition by time interactions for blood flow (p=0.01), blood volume (p=0.022), and intramuscular temperature (p<0.001). For blood flow and volume, the cryotherapy condition maintained baseline levels, while the sham condition increased at immediate-post treatment and rewarm. For intramuscular temperature, the cryotherapy condition caused a decrease in intramuscular temperature from baseline compared to no change in the sham condition from baseline. Intramuscular temperature change was significantly correlated to subcutaneous tissue thickness (r=.49; p=0.05). Conclusions Cryotherapy did not decrease blood flow and blood volume from resting levels, even though the intramuscular temperature decreased. An intramuscular change of 7–9°C may not be cold enough to cause local vasoconstriction. PMID:21988932

  13. Tissue viability imaging for assessment of microvascular events

    NASA Astrophysics Data System (ADS)

    O'Doherty, Jim; Nilsson, Gert E.; Henricson, Joakim; Sjoberg, Folke; Leahy, Martin J.

    2005-08-01

    A new technique for the investigation of microvascular tissue blood concentration is presented, based on the method of polarisation spectroscopy of blood in superficial skin tissue. Linearly polarised light incident on the skin is partly reflected by the surface layers, and partly backscattered from the dermal tissue. Use of orthogonal polarisation filters over both a light source and a CCD suppresses the reflections from the surface, and only the depolarised light backscattered from the dermal matrix reaches the CCD array. By separating the colour planes of an image acquired in this manner and applying a dedicated image processing algorithm, spectroscopic information about the amount of red blood cells (RBCs) in the underlying area of tissue can be discovered. The algorithm incorporates theory that utilises the differences in light absorption of RBCs and dermal tissue in the red and green wavelength regions. In vitro fluid models compare well to computer simulations in describing a linear relationship between output signal (called TiViindex) and RBC concentration in the physiological range of 0%-4%. In vivo evaluation of the technique via transepidermal application of acetylcholine by iontophoresis displayed a heterogeneity pattern of vasodilation, which is typical of the vasoactive agent. Extension of the technique to capture and process continuous real-time data creates a new possibility of online real-time image processing. Application of tissue viability (TiVi) imaging include skin care products and drug development, as well as investigations of microvascular angiogenesis.

  14. Optically measured microvascular blood flow contrast of malignant breast tumors.

    PubMed

    Choe, Regine; Putt, Mary E; Carlile, Peter M; Durduran, Turgut; Giammarco, Joseph M; Busch, David R; Jung, Ki Won; Czerniecki, Brian J; Tchou, Julia; Feldman, Michael D; Mies, Carolyn; Rosen, Mark A; Schnall, Mitchell D; DeMichele, Angela; Yodh, Arjun G

    2014-01-01

    Microvascular blood flow contrast is an important hemodynamic and metabolic parameter with potential to enhance in vivo breast cancer detection and therapy monitoring. Here we report on non-invasive line-scan measurements of malignant breast tumors with a hand-held optical probe in the remission geometry. The probe employs diffuse correlation spectroscopy (DCS), a near-infrared optical method that quantifies deep tissue microvascular blood flow. Tumor-to-normal perfusion ratios are derived from thirty-two human subjects. Mean (95% confidence interval) tumor-to-normal ratio using surrounding normal tissue was 2.25 (1.92-2.63); tumor-to-normal ratio using normal tissues at the corresponding tumor location in the contralateral breast was 2.27 (1.94-2.66), and using normal tissue in the contralateral breast was 2.27 (1.90-2.70). Thus, the mean tumor-to-normal ratios were significantly different from unity irrespective of the normal tissue chosen, implying that tumors have significantly higher blood flow than normal tissues. Therefore, the study demonstrates existence of breast cancer contrast in blood flow measured by DCS. The new, optically accessible cancer contrast holds potential for cancer detection and therapy monitoring applications, and it is likely to be especially useful when combined with diffuse optical spectroscopy/tomography. PMID:24967878

  15. Method of manufacturing a shapeable short-resistant capacitor

    DOEpatents

    Taylor, Ralph S.; Myers, John D.; Baney, William J.

    2013-04-02

    A method that employs a novel combination of conventional fabrication techniques provides a ceramic short-resistant capacitor that is bendable and/or shapeable to provide a multiple layer capacitor that is extremely compact and amenable to desirable geometries. The method allows thinner and more flexible ceramic capacitors to be made. The method includes forming a first thin metal layer on a substrate; depositing a thin, ceramic dielectric layer over the metal layer; depositing a second thin metal layer over the dielectric layer to form a capacitor exhibiting a benign failure mode; and separating the capacitor from the substrate. The method may also include bending the resulting capacitor into a serpentine arrangement with gaps between the layers that allow venting of evaporated electrode material in the event of a benign failure.

  16. Minimally implicit Runge-Kutta methods for Resistive Relativistic MHD

    NASA Astrophysics Data System (ADS)

    Aloy, Miguel-Á.; Cordero-Carrión, Isabel

    2016-05-01

    The Relativistic Resistive Magnetohydrodynamic (RRMHD) equations are a hyperbolic system of partial differential equations used to describe the dynamics of relativistic magnetized fluids with a finite conductivity. Close to the ideal magnetohydrodynamic regime, the source term proportional to the conductivity becomes potentially stiff and cannot be handled with standard explicit time integration methods. We propose a new class of methods to deal with the stiffness fo the system, which we name Minimally Implicit Runge-Kutta methods. These methods avoid the development of numerical instabilities without increasing the computational costs in comparison with explicit methods, need no iterative extra loop in order to recover the primitive (physical) variables, the analytical inversion of the implicit operator is trivial and the several stages can actually be viewed as stages of explicit Runge-Kutta methods with an effective time-step. We test these methods with two different one-dimensional test beds in varied conductivity regimes, and show that our second-order schemes satisfy the theoretical expectations.

  17. Direct ink writing of microvascular networks

    NASA Astrophysics Data System (ADS)

    Wu, Willie

    Nature is replete with examples of embedded microvascular systems that enable efficient fluid flow and distribution for autonomic healing, cooling, and energy harvesting. The ability to incorporate microvascular networks in functional materials systems is therefore both scientifically and technologically important. In this PhD thesis, the direct-write assembly of planar and 3D biomimetic microvascular networks within polymer and hydrogel matrices is demonstrated. In addition, the influence of network design of fluid transport efficiency is characterized. Planar microvascular networks composed of periodic lattices of uniformal microchannels and hierarchical, branching architectures are constructed by direct-write assembly of a fugitive organic ink. Several advancements are required to facilitate their patterning, including pressure valving, dual ink printing, and dynamic pressure variation to allow tunable control of ink deposition. The hydraulic conductance is measured using a high pressure flow meter as a function of network design. For a constant vascular volume and areal coverage, 2- and 4-generation branched architectures that obey Murray's Law exhibited the highest hydraulic conductivity. These experimental observations are in good agreement with predictions made by analytic models. 3D microvascular networks are fabricated by omnidirectional printing a fugitive organic ink into a photopolymerizable hydrogel matrix that is capped with fluid filler of nearly identical composition. Using this approach, 3D networks of arbitrary design can be patterned. After ink deposition is complete, the matrix and fluid filler are chemically cross-linked via UV irradiation, and the ink is removed by liquefication. Aqueous solutions composed of a triblock copolymer of polyethylene oxide (PEO)-polypropylene oxide (PPO)-PEO constitute the materials system of choice due to their thermal- and concentration-dependent phase behavior. Specifically, the fugitive ink consists of a 23 w

  18. Sonothrombolysis with BR38 Microbubbles Improves Microvascular Patency in a Rat Model of Stroke

    PubMed Central

    Kampschulte, Marian; Hyvelin, Jean-Marc; Botteron, Catherine; Juenemann, Martin; Yeniguen, Mesut; Krombach, Gabriele A.; Kaps, Manfred; Spratt, Neil J.; Gerriets, Tibo; Nedelmann, Max

    2016-01-01

    Background Early recanalization of large cerebral vessels in ischemic stroke is associated with improved clinical outcome, however persisting hypoperfusion leads to poor clinical recovery despite large vessel recanalization. Limited experimental sonothrombolysis studies have shown that addition of microbubbles during treatment can improve microvascular patency. We aimed to determine the effect of two different microbubble formulations on microvascular patency in a rat stroke model. Methods We tested BR38 and SonoVue® microbubble-enhanced sonothrombolysis in Wistar rats submitted to 90-minute filament occlusion of the middle cerebral artery. Rats were randomized to treatment (n = 6/group): control, rt-PA, or rt-PA+3-MHz ultrasound insonation with BR38 or SonoVue® at full or 1/3 dose. Treatment duration was 60 minutes, beginning after withdrawal of the filament, and sacrifice was immediately after treatment. Vascular volumes were evaluated with microcomputed tomography. Results Total vascular volume of the ipsilateral hemisphere was reduced in control and rt-PA groups (p<0.05), but was not significantly different from the contralateral hemisphere in all microbubble-treated groups (p>0.1). Conclusions Microbubble-enhanced sonothrombolysis improves microvascular patency. This effect is not dose- or microbubble formulation-dependent suggesting a class effect of microbubbles promoting microvascular reopening. This study demonstrates that microbubble-enhanced sonothrombolysis may be a therapeutic strategy for patients with persistent hypoperfusion of the ischemic territory. PMID:27077372

  19. Directed assembly of three-dimensional microvascular networks

    NASA Astrophysics Data System (ADS)

    Therriault, Daniel

    Three-dimensional (3-D) microvascular networks with pervasive, interconnected channels less than 300 mum in diameter may find widespread application in microfluidic devices, biotechnology, sensors, and autonomic healing materials. Although microchannel arrays are readily constructed in two-dimensions by photolithographic or soft lithographic techniques, their construction in three-dimensions remains a challenging problem. The development of a microfabrication method to build 3-D microvascular networks based on direct-write assembly is described is this thesis. The method is based on the robotic deposition of a fugitive organic ink to form a free-standing scaffold structure. Secondary infiltration of a structural resin followed by setting of the matrix and removal of the scaffold yields an embedded pervasive network of smooth cylindrical channels (˜10--500 mum) with defined connectivity. Rheological and other material properties studies of fugitive organic ink were performed in order to identify the critical characteristics required for successful deposition of 3-D scaffolds by direct-write assembly. Guided by the results of these studies, several new ink formulations were screened for improved deposition performance. The most successful of these inks (40wt% microcrystalline wax, 60wt% petroleum jelly) showed excellent deposition and had an equilibrium modulus at room temperature (G 'eq ˜ 7.70 kPa 1 Hz) nearly two orders of magnitude higher than the original ink. The optimized ink was used to successfully build thick (i.e., ˜100 layers) scaffold structures at room temperature with negligible time-dependent deformation post-deposition. Secondary infiltration of the resin was accomplished at room temperature while maintaining the scaffold architecture. The optimized ink was also successfully extruded through small micronozzles (1 mum). The construction of 3-D microvascular networks enables microfluidic devices with unparallel geometric complexity. In one example, a

  20. Listeriolysin O mediates cytotoxicity against human brain microvascular

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Penetration of the brain microvascular endothelial layer is one of the routes L. monocytogenes use to breach the blood-brain barrier. Because host factors in the blood severely limit direct invasion of human brain microvascular endothelial cells (HBMECs) by L. monocytogenes, alternative mechanisms m...

  1. Rapid homogeneous endothelialization of high aspect ratio microvascular networks.

    PubMed

    Naik, Nisarga; Hanjaya-Putra, Donny; Haller, Carolyn A; Allen, Mark G; Chaikof, Elliot L

    2015-08-01

    Microvascularization of an engineered tissue construct is necessary to ensure the nourishment and viability of the hosted cells. Microvascular constructs can be created by seeding the luminal surfaces of microfluidic channel arrays with endothelial cells. However, in a conventional flow-based system, the uniformity of endothelialization of such an engineered microvascular network is constrained by mass transfer of the cells through high length-to-diameter (L/D) aspect ratio microchannels. Moreover, given the inherent limitations of the initial seeding process to generate a uniform cell coating, the large surface-area-to-volume ratio of microfluidic systems demands long culture periods for the formation of confluent cellular microconduits. In this report, we describe the design of polydimethylsiloxane (PDMS) and poly(glycerol sebacate) (PGS) microvascular constructs with reentrant microchannels that facilitates rapid, spatially homogeneous endothelial cell seeding of a high L/D (2 cm/35 μm; > 550:1) aspect ratio microchannels. MEMS technology was employed for the fabrication of a monolithic, elastomeric, reentrant microvascular construct. Isotropic etching and PDMS micromolding yielded a near-cylindrical microvascular channel array. A 'stretch - seed - seal' operation was implemented for uniform incorporation of endothelial cells along the entire microvascular area of the construct yielding endothelialized microvascular networks in less than 24 h. The feasibility of this endothelialization strategy and the uniformity of cellularization were established using confocal microscope imaging. PMID:26227213

  2. Rapid homogeneous endothelialization of high aspect ratio microvascular networks.

    PubMed

    Naik, Nisarga; Hanjaya-Putra, Donny; Haller, Carolyn A; Allen, Mark G; Chaikof, Elliot L

    2015-08-01

    Microvascularization of an engineered tissue construct is necessary to ensure the nourishment and viability of the hosted cells. Microvascular constructs can be created by seeding the luminal surfaces of microfluidic channel arrays with endothelial cells. However, in a conventional flow-based system, the uniformity of endothelialization of such an engineered microvascular network is constrained by mass transfer of the cells through high length-to-diameter (L/D) aspect ratio microchannels. Moreover, given the inherent limitations of the initial seeding process to generate a uniform cell coating, the large surface-area-to-volume ratio of microfluidic systems demands long culture periods for the formation of confluent cellular microconduits. In this report, we describe the design of polydimethylsiloxane (PDMS) and poly(glycerol sebacate) (PGS) microvascular constructs with reentrant microchannels that facilitates rapid, spatially homogeneous endothelial cell seeding of a high L/D (2 cm/35 μm; > 550:1) aspect ratio microchannels. MEMS technology was employed for the fabrication of a monolithic, elastomeric, reentrant microvascular construct. Isotropic etching and PDMS micromolding yielded a near-cylindrical microvascular channel array. A 'stretch - seed - seal' operation was implemented for uniform incorporation of endothelial cells along the entire microvascular area of the construct yielding endothelialized microvascular networks in less than 24 h. The feasibility of this endothelialization strategy and the uniformity of cellularization were established using confocal microscope imaging.

  3. Current Diagnostic and Therapeutic Strategies in Microvascular Angina

    PubMed Central

    Mumma, Bryn; Flacke, Nathalie

    2014-01-01

    Microvascular angina is common among patients with signs and symptoms of acute coronary syndrome and is associated with an increased risk of cardiovascular and cerebrovascular events. Unfortunately, microvascular is often under-recognized in clinical settings. The diagnosis of microvascular angina relies on assessment of the functional status of the coronary microvasculature. Invasive strategies include acetylcholine provocation, intracoronary Doppler ultrasound, and intracoronary thermodilution; noninvasive strategies include cardiac positron emission tomography (PET), cardiac magnetic resonance, and Doppler echocardiography. Once the diagnosis of microvascular angina is established, treatment is focused on improving symptoms and reducing future risk of cardiovascular and cerebrovascular events. Pharmacologic options and lifestyle modifications for patients with microvascular angina are similar to those for patients with coronary artery disease. PMID:25685641

  4. Early Systemic Microvascular Damage in Pigs with Atherogenic Diabetes Mellitus Coincides with Renal Angiopoietin Dysbalance

    PubMed Central

    Khairoun, Meriem; van den Heuvel, Mieke; van den Berg, Bernard M.; Sorop, Oana; de Boer, Rients; van Ditzhuijzen, Nienke S.; Bajema, Ingeborg M.; Baelde, Hans J.; Zandbergen, Malu; Duncker, Dirk J.; Rabelink, Ton J.; Reinders, Marlies E. J.; Rotmans, Joris I.

    2015-01-01

    Background Diabetes mellitus (DM) is associated with a range of microvascular complications including diabetic nephropathy (DN). Microvascular abnormalities in the kidneys are common histopathologic findings in DN, which represent one manifestation of ongoing systemic microvascular damage. Recently, sidestream dark-field (SDF) imaging has emerged as a noninvasive tool that enables one to visualize the microcirculation. In this study, we investigated whether changes in the systemic microvasculature induced by DM and an atherogenic diet correlated spatiotemporally with renal damage. Methods Atherosclerotic lesion development was triggered in streptozotocin-induced DM pigs (140 mg/kg body weight) by administering an atherogenic diet for approximately 11 months. Fifteen months following induction of DM, microvascular morphology was visualized in control pigs (n = 7), non-diabetic pigs fed an atherogenic diet (ATH, n = 5), and DM pigs fed an atherogenic diet (DM+ATH, n = 5) using SDF imaging of oral mucosal tissue. Subsequently, kidneys were harvested from anethesized pigs and the expression levels of well-established markers for microvascular integrity, such as Angiopoietin-1 (Angpt1) and Angiopoietin-2 (Angpt2) were determined immunohistochemically, while endothelial cell (EC) abundance was determined by immunostaining for von Willebrand factor (vWF). Results Our study revealed an increase in the capillary tortuosity index in DM+ATH pigs (2.31±0.17) as compared to the control groups (Controls 0.89±0.08 and ATH 1.55±0.11; p<0.05). Kidney biopsies showed marked glomerular lesions consisting of mesangial expansion and podocyte lesions. Furthermore, we observed a disturbed Angpt2/ Angpt1balance in the cortex of the kidney, as evidenced by increased expression of Angpt2 in DM+ATH pigs as compared to Control pigs (p<0.05). Conclusion In the setting of DM, atherogenesis leads to the augmentation of mucosal capillary tortuosity, indicative of systemic microvascular damage

  5. Myocardial perfusion echocardiography and coronary microvascular dysfunction

    PubMed Central

    Barletta, Giuseppe; Del Bene, Maria Riccarda

    2015-01-01

    Our understanding of coronary syndromes has evolved in the last two decades out of the obstructive atherosclerosis of epicardial coronary arteries paradigm to include anatomo-functional abnormalities of coronary microcirculation. No current diagnostic technique allows direct visualization of coronary microcirculation, but functional assessments of this circulation are possible. This represents a challenge in cardiology. Myocardial contrast echocardiography (MCE) was a breakthrough in echocardiography several years ago that claimed the capability to detect myocardial perfusion abnormalities and quantify coronary blood flow. Research demonstrated that the integration of quantitative MCE and fractional flow reserve improved the definition of ischemic burden and the relative contribution of collaterals in non-critical coronary stenosis. MCE identified no-reflow and low-flow within and around myocardial infarction, respectively, and predicted the potential functional recovery of stunned myocardium using appropriate interventions. MCE exhibited diagnostic performances that were comparable to positron emission tomography in microvascular reserve and microvascular dysfunction in angina patients. Overall, MCE improved echocardiographic evaluations of ischemic heart disease in daily clinical practice, but the approval of regulatory authorities is lacking. PMID:26730291

  6. Microvascular Repair: Post-Angiogenesis Vascular Dynamics

    PubMed Central

    LeBlanc, Amanda J.; Krishnan, Laxminarayanan; Sullivan, Christopher J.; Williams, Stuart K.; Hoying, James B.

    2013-01-01

    Vascular compromise and the accompanying perfusion deficits cause or complicate a large array of disease conditions and treatment failures. This has prompted the exploration of therapeutic strategies to repair or regenerate vasculatures thereby establishing more competent microcirculatory beds. Growing evidence indicates that an increase in vessel numbers within a tissue does not necessarily promote an increase in tissue perfusion. Effective regeneration of a microcirculation entails the integration of new stable microvessel segments into the network via neovascularization. Beginning with angiogenesis, neovascularization entails an integrated series of vascular activities leading to the formation of a new mature microcirculation and includes vascular guidance and inosculation, vessel maturation, pruning, arterio-venous specification, network patterning, structural adaptation, intussusception, and microvascular stabilization. While the generation of new vessel segments is necessary to expand a network, without the concomitant neovessel remodeling and adaptation processes intrinsic to microvascular network formation, these additional vessel segments give rise to a dysfunctional microcirculation. While many of the mechanisms regulating angiogenesis have been detailed, a thorough understanding of the mechanisms driving post-angiogenesis activities specific to neovascularization has yet to be fully realized, but is necessary in order to develop effective therapeutic strategies for repairing compromised microcirculations as a means to treat disease. PMID:22734666

  7. Effects of radiation therapy in microvascular anastomoses

    SciTech Connect

    Fried, M.P.

    1985-07-01

    The otolaryngologist, as a head and neck surgeon, commonly cares for patients with upper aerodigestive tract malignancies. Therapy of these neoplasms often requires wide excision. One standard reconstructive procedure utilizes pedicled regional flaps, both dermal and myodermal which have some disadvantages. The shortcomings of these pedicled regional flaps have led to the use of the vascularized free flap in certain cases. The occasional case may lead to catastrophe if microanastomoses fail when combined with radiation. Notwithstanding, many surgical series have reported success when radiation has been given. The present investigation was undertaken to assess the effects of radiation therapy on microvascular anastomoses when radiation is administered pre- or postoperatively or when nonradiated tissue is transferred to an irradiated recipient site. These effects were observed serially in an experimental rat model using a tubed superficial epigastric flap that adequately reflected tissue viability and vascular patency. The histologic changes were then noted over a three month period after completion of both radiation and surgery. This study adds credence to the observation of the lack of deleterious effects of radiation on experimental microvascular anastomotic patency whether the radiation is given before or after surgery or if radiated tissue is approximated to nonradiated vessels.

  8. Graphite having improved thermal stress resistance and method of preparation

    DOEpatents

    Kennedy, Charles R.

    1980-01-01

    An improved method for fabricating a graphite article comprises the steps of impregnating a coke article by first heating the coke article in contact with a thermoplastic pitch at a temperature within the range of 250.degree.-300.degree. C. at a pressure within the range of 200-2000 psig for at least 4-10 hours and then heating said article at a temperature within the range of 450.degree.-485.degree. C. at a pressure of 200-2000 psig for about 16-24 hours to provide an impregnated article; heating the impregnated article for sufficient time to carbonize the impregnant to provide a second coke article, and graphitizing the second coke article. A graphite having improved thermal stress resistance results when the coke to be impregnated contains 1-3 wt.% sulfur and no added puffing inhibitors. An additional improvement in thermal stress resistance is achieved when the second coke article is heated above about 1400.degree. C. at a rate of at least 10.degree. C./minute to a temperature above the puffing temperature.

  9. Heparin-binding EGF-like Growth Factor Increases Intestinal Microvascular Blood Flow in Necrotizing Enterocolitis

    PubMed Central

    Yu, Xiaoyi; Radulescu, Andrei; Zorko, Nicholas; Besner, Gail E.

    2009-01-01

    Background & Aims Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in neonates. Although the exact etiology remains unknown, decreased intestinal blood flow is thought to play a critical role. We have shown that heparin-binding EGF-like growth factor (HB-EGF) protects the intestines from injury in a rodent model of NEC. Our current goal was to assess the effect of HB-EGF on intestinal microvascular blood flow and intestinal injury in rat pups subjected to experimental NEC. Methods Newborn rat pups were subjected to stress by exposure to hypoxia, hypothermia, hypertonic feedings and lipopolysaccharide, with some pups receiving HB-EGF (800 μg/kg/dose) added to the feeds. Control animals received breast milk. Intestinal injury was graded using a standard histologic injury scoring system. Microvascular blood flow was assessed by FITC-dextran angiography with fluorescent images subjected to quantification, and by scanning electron microscopy. Results Intestinal microvascular blood flow (defined as the extent of vascular filling with FITC-dextran) was significantly decreased in pups subjected to stress compared to breast fed pups. Stressed pups treated with HB-EGF had significantly increased microvascular blood flow. The changes in villous microvasculature correlated with histologic injury scores, with stressed pups treated with HB-EGF showing decreased histologic injury. Conclusions HB-EGF significantly preserved intestinal microvascular blood flow in pups subjected to experimental NEC, indicating that HB-EGF may play a critical role in the therapy of various diseases manifested by decreased intestinal blood flow, including NEC. PMID:19361505

  10. Method for characterizing the contact resistance of metal-vanadium dioxide thin film interfaces

    SciTech Connect

    Percy, R.; Stan, M.; Weikle, R. M.; Kittiwatanakul, S.; Lu, J.; Wolf, S.

    2014-07-14

    The standard method for determining the contact resistance of planar metal-semiconductor interfaces can underestimate the true contact resistance under normal operating conditions, as it relies on the resistivity of the semiconductor material remaining constant during measurement. However, the strong temperature dependence of the resistivity of VO{sub 2} requires a modified approach that maintains a constant power density dissipated within the film to account for Joule heating. We develop a method for measuring contact resistance in semiconductors with a high thermal coefficient of resistivity, demonstrate this method with an example, and compare the results with the standard technique.

  11. Transmural variation and anisotropy of microvascular flow conductivity in the rat myocardium

    PubMed Central

    Smith, Amy F.; Shipley, Rebecca J.; Lee, Jack; Sands, Gregory B.; LeGrice, Ian J.; Smith, Nicolas P.

    2015-01-01

    Transmural variations in the relationship between structural and fluid transport properties of myocardial capillary networks are determined via continuum modelling approaches using recent three-dimensional (3D) data on the microvascular structure. Specifically, the permeability tensor, which quantifies the inverse of the blood flow resistivity of the capillary network, is computed by volume-averaging flow solutions in synthetic networks with geometrical and topological properties derived from an anatomically-detailed microvascular data set extracted from the rat myocardium. Results show that the permeability is approximately ten times higher in the principal direction of capillary alignment (the ‘longitudinal’ direction) than perpendicular to this direction, reflecting the strong anisotropy of the microvascular network. Additionally, a 30% increase in capillary diameter from subepicardium to subendocardium is shown to translate to a 130% transmural rise in permeability in the longitudinal capillary direction. This result supports the hypothesis that perfusion is preferentially facilitated during diastole in the subendocardial microvasculature to compensate for the severely-reduced systolic perfusion in the subendocardium. PMID:24866569

  12. Ion implantation method for preparing polymers having oxygen erosion resistant surfaces

    DOEpatents

    Lee, E.H.; Mansur, L.K.; Heatherly, L. Jr.

    1995-04-18

    Hard surfaced polymers and the method for making them are generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface, improved wear resistance, and improved oxygen erosion resistance. 8 figs.

  13. Ion implantation method for preparing polymers having oxygen erosion resistant surfaces

    DOEpatents

    Lee, Eal H.; Mansur, Louis K.; Heatherly, Jr., Lee

    1995-01-01

    Hard surfaced polymers and the method for making them are generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface, improved wear resistance, and improved oxygen erosion resistance.

  14. Differentiation state determines neural effects on microvascular endothelial cells

    SciTech Connect

    Muffley, Lara A.; Pan, Shin-Chen; Smith, Andria N.; Ga, Maricar; Hocking, Anne M.; Gibran, Nicole S.

    2012-10-01

    Growing evidence indicates that nerves and capillaries interact paracrinely in uninjured skin and cutaneous wounds. Although mature neurons are the predominant neural cell in the skin, neural progenitor cells have also been detected in uninjured adult skin. The aim of this study was to characterize differential paracrine effects of neural progenitor cells and mature sensory neurons on dermal microvascular endothelial cells. Our results suggest that neural progenitor cells and mature sensory neurons have unique secretory profiles and distinct effects on dermal microvascular endothelial cell proliferation, migration, and nitric oxide production. Neural progenitor cells and dorsal root ganglion neurons secrete different proteins related to angiogenesis. Specific to neural progenitor cells were dipeptidyl peptidase-4, IGFBP-2, pentraxin-3, serpin f1, TIMP-1, TIMP-4 and VEGF. In contrast, endostatin, FGF-1, MCP-1 and thrombospondin-2 were specific to dorsal root ganglion neurons. Microvascular endothelial cell proliferation was inhibited by dorsal root ganglion neurons but unaffected by neural progenitor cells. In contrast, microvascular endothelial cell migration in a scratch wound assay was inhibited by neural progenitor cells and unaffected by dorsal root ganglion neurons. In addition, nitric oxide production by microvascular endothelial cells was increased by dorsal root ganglion neurons but unaffected by neural progenitor cells. -- Highlights: Black-Right-Pointing-Pointer Dorsal root ganglion neurons, not neural progenitor cells, regulate microvascular endothelial cell proliferation. Black-Right-Pointing-Pointer Neural progenitor cells, not dorsal root ganglion neurons, regulate microvascular endothelial cell migration. Black-Right-Pointing-Pointer Neural progenitor cells and dorsal root ganglion neurons do not effect microvascular endothelial tube formation. Black-Right-Pointing-Pointer Dorsal root ganglion neurons, not neural progenitor cells, regulate

  15. Microvascularization on collared peccary placenta: a microvascular cast study [corrected] in late pregnancy.

    PubMed

    Santos, Tatiana Carlesso; Oliveira, Moacir Franco; Dantzer, Vibeke; Miglino, Maria Angélica

    2012-07-01

    The microvascularization of the collared peccary (Tayassu tajacu) placenta was studied by vascular casts and immunolocalization of α-smooth muscle actin and vimentin, to identify the three dimensional organization and vascular flow interrelation in the microvasculature between the maternal and fetal compartments of the placentae. The immunolocalization of vimentin in the vascular endothelium and in the smooth muscle cells of blood vessels showed indented capillaries along the uterine epithelium and the trophoblast at the sides of complementary maternal and fetal microfolds, or rugae. This confers the three-dimensional structure observed in vascular casts. On the maternal side, casts demonstrated uterine folds coated by with primary and secondary ridges, and by areolae dispersed between these ridges. The arteriole runs through the center/middle of ridges, branching at the top into a microvascular network wall in a basket-like fashion. At the base of these baskets venules were formed. On the fetal side, arterioles branched centrally in the fetal rugae into a capillary network in a bulbous form, complementary to the opposite maternal depressions forming the baskets. At the base of the bulbous protrusions, the fetal venules arise. The blood vessel orientation in the materno-fetal interface of the placentae of collared peccaries suggests a blood flow pattern of the type countercurrent to cross current. The same pattern has been reported in domestic swine demonstrating that, even after 38 million years, the Tayassuidae and Suidae families exhibit similar placental morphology, which is here characterized at the microvascular level.

  16. Self-healing materials with microvascular networks.

    PubMed

    Toohey, Kathleen S; Sottos, Nancy R; Lewis, Jennifer A; Moore, Jeffrey S; White, Scott R

    2007-08-01

    Self-healing polymers composed of microencapsulated healing agents exhibit remarkable mechanical performance and regenerative ability, but are limited to autonomic repair of a single damage event in a given location. Self-healing is triggered by crack-induced rupture of the embedded capsules; thus, once a localized region is depleted of healing agent, further repair is precluded. Re-mendable polymers can achieve multiple healing cycles, but require external intervention in the form of heat treatment and applied pressure. Here, we report a self-healing system capable of autonomously repairing repeated damage events. Our bio-inspired coating-substrate design delivers healing agent to cracks in a polymer coating via a three-dimensional microvascular network embedded in the substrate. Crack damage in the epoxy coating is healed repeatedly. This approach opens new avenues for continuous delivery of healing agents for self-repair as well as other active species for additional functionality.

  17. Impact of the arterial input function on microvascularization parameter measurements using dynamic contrast-enhanced ultrasonography

    PubMed Central

    Gauthier, Marianne; Pitre-Champagnat, Stéphanie; Tabarout, Farid; Leguerney, Ingrid; Polrot, Mélanie; Lassau, Nathalie

    2012-01-01

    AIM: To evaluate the sources of variation influencing the microvascularization parameters measured by dynamic contrast-enhanced ultrasonography (DCE-US). METHODS: Firstly, we evaluated, in vitro, the impact of the manual repositioning of the ultrasound probe and the variations in flow rates. Experiments were conducted using a custom-made phantom setup simulating a tumor and its associated arterial input. Secondly, we evaluated, in vivo, the impact of multiple contrast agent injections and of examination day, as well as the influence of the size of region of interest (ROI) associated with the arterial input function (AIF). Experiments were conducted on xenografted B16F10 female nude mice. For all of the experiments, an ultrasound scanner along with a linear transducer was used to perform pulse inversion imaging based on linear raw data throughout the experiments. Semi-quantitative and quantitative analyses were performed using two signal-processing methods. RESULTS: In vitro, no microvascularization parameters, whether semi-quantitative or quantitative, were significantly correlated (P values from 0.059 to 0.860) with the repositioning of the probe. In addition, all semi-quantitative microvascularization parameters were correlated with the flow variation while only one quantitative parameter, the tumor blood flow, exhibited P value lower than 0.05 (P = 0.004). In vivo, multiple contrast agent injections had no significant impact (P values from 0.060 to 0.885) on microvascularization parameters. In addition, it was demonstrated that semi-quantitative microvascularization parameters were correlated with the tumor growth while among the quantitative parameters, only the tissue blood flow exhibited P value lower than 0.05 (P = 0.015). Based on these results, it was demonstrated that the ROI size of the AIF had significant influence on microvascularization parameters: in the context of larger arterial ROI (from 1.17 ± 0.6 mm3 to 3.65 ± 0.3 mm3), tumor blood flow and

  18. Phase transition of the microvascular network architecture in human pathologies.

    PubMed

    Bianciardi, Giorgio; Traversi, Claudio; Cattaneo, Ruggero; De Felice, Claudia; Monaco, Annalisa; Tosi, Gianmarco; Parrini, Stefano; Latini, Giuseppe

    2012-01-01

    We have investigated the microvascular pattern in acquired or genetic diseases in humans. The lower gingival and vestibular oral mucosa, as well as the optic nerve head, was chosen to characterize the vascular pattern complexity due to the simple accessibility and visibility Local fractal dimensions, fractal dimension of the minimum path and Lempel-Ziv complexity have been used as operational numerical tools to characterize the microvascular networks. In the normal healthy subjects microvascular networks show nonlinear values corresponding to the complexity of a diffusion limited aggregation (DLA) model, while in several acquired or genetic diseases they are approaching the ones of an invasion percolation model. PMID:23193796

  19. Method for applying corrosion resistant metallic coating of zirconium nitride

    SciTech Connect

    Bryan, W.J.; Corsetti, L.V.

    1993-07-13

    A process is described for enhancing the wear and corrosion resistance of a cladding tube for a nuclear fuel rod, comprising reactively depositing zirconium nitride on the surface of said cladding tube by a cathodic arc plasma deposition process to form a thin wear resistant coating.

  20. [Postoperative monitoring of microvascular flap repair with pulse oximetry--initial experience].

    PubMed

    Strauss, J M; Neukam, F W; Krohn, S; Schmelzeisen, R; Borchard, F

    1994-03-01

    The surgical success of microvascular free flaps or pedicled flaps depends on the function of the nutritive vessels. Complications such as thrombosis or vessel kinking, are dangerous and may result in flap loss. During the last decade, different methods were tested for their capability of monitoring flap perfusion. We report our preliminary experience with the continuous and non-invasive pulse oximetry by using a special reflection sensor positioned on the surface of the flap. PMID:8020852

  1. Method for resisting corrosion in geothermal fluid handling systems

    SciTech Connect

    Love, W.W.; Cron, C.J.

    1988-05-24

    A method for resisting corrosion while conducting a flow of hot, corrosive geothermal fluid is described comprising the steps of: (a) forming a fluid conducting element of a beta and alpha titanium-base product produced by heating to form a metastable beta titantium matrix, and thereafter heat treating the matrix to form sufficient alpha phase therein providing an increase in ultimate tensile strength of at least about 10,000 psi over that of the matrix before the heat treating, the beta and alpha titantium-base product so formed having an average valence electron density of between about 4.15 and about 4.35. The composition consisting essentially of: (i) a total of between about 2 and about 10 weight percent of one or more beta eutectoid elements; (ii) between about 4 and about 10 weight percent of vanadium; (iii) between about 3 and about 6 weight percent of molybdenum; (iv) between about 2 and about 5 weight percent of aluminum; and (v) the balance titanium; and (b) following the geothermal fluid through the fluid conducting element.

  2. Microvascular temporalis fascia transfer for penile girth enhancement.

    PubMed

    Küçükçelebi, A; Ertaş, N M; Aydin, A; Eroğlu, A; Ozmen, E; Velidedeoğlu, H

    2001-07-01

    The authors report a 44-year-old man with inadequate penile girth that caused psychological problems. Using microvascular temporalis fascia transfer, they achieved satisfactory penile girth enhancement based on reliable vascularity in a single stage. PMID:11756810

  3. Protein osmotic pressure gradients and microvascular reflection coefficients.

    PubMed

    Drake, R E; Dhother, S; Teague, R A; Gabel, J C

    1997-08-01

    Microvascular membranes are heteroporous, so the mean osmotic reflection coefficient for a microvascular membrane (sigma d) is a function of the reflection coefficient for each pore. Investigators have derived equations for sigma d based on the assumption that the protein osmotic pressure gradient across the membrane (delta II) does not vary from pore to pore. However, for most microvascular membranes, delta II probably does vary from pore to pore. In this study, we derived a new equation for sigma d. According to our equation, pore-to-pore differences in delta II increase the effect of small pores and decrease the effect of large pores on the overall membrane osmotic reflection coefficient. Thus sigma d for a heteroporous membrane may be much higher than previously derived equations indicate. Furthermore, pore-to-pore delta II differences increase the effect of plasma protein osmotic pressure to oppose microvascular fluid filtration. PMID:9277520

  4. Analysis of microvascular density in early gastric carcinoma using magnifying endoscopy with narrow-band imaging

    PubMed Central

    Kawamura, Masashi; Naganuma, Hiroshi; Shibuya, Rie; Kikuchi, Tatsuya; Sakai, Yoshitaka; Nagasaki, Futoshi; Nomura, Eiki; Suzuki, Noriaki; Saito, Eri

    2016-01-01

    Background and study aims: Intramucosal vascular density differs between differentiated and undifferentiated type gastric carcinomas. This study aimed to evaluate the microvascular density characteristics of these two types of carcinoma using magnifying endoscopy with narrow-band imaging (ME-NBI). Patients and methods: In total, 42 differentiated and 10 undifferentiated types were evaluated. The microvessels observed using ME-NBI were extracted from stored still images and the microvascular density in the two carcinoma types was analyzed. Histological vascular density in resected specimens was also evaluated using CD34 immunostaining. Results: There were significant differences between the microvascular density in the differentiated and undifferentiated types of carcinoma (10.02 ± 4.72 % vs 4.02 ± 0.40 %; P < 0.001) using ME-NBI. Vascular density assessed histologically also differed significantly between differentiated and undifferentiated types in both the whole mucosal (5.81 ± 3.17 % vs 3.25 ± 1.21 %) and the superficial mucosal layers (0 – 100 μm) (6.38 ± 3.73 % vs 3.66 ± 1.46 %). However, the vascular density in the surrounding non-carcinomatous mucosa assessed using ME-NBI and histologically, was significantly lower in the differentiated than in the undifferentiated types (P < 0.001). There was good agreement between ME-NBI and histologically assessed microvascular density in both the whole (r = 0.740; P < 0.001) and superficial mucosal layers (r = 0.764; P < 0.001). White opaque substance (WOS) was seen in eight patients who had the differentiated type carcinoma. In almost all cases with WOS, the appearance of the carcinoma was discolored. Conclusions: There was a close relationship between ME-NBI assessed microvascular density and histologically assessed vascular density in the mucosal layer. Microvascular density differed significantly between the differentiated and undifferentiated

  5. Microvascular Plasticity: Angiogenesis in Health and Disease--Preface.

    PubMed

    Secomb, Timothy W; Pries, Axel R

    2016-02-01

    This Special Topic Issue is concerned with the mechanisms that determine the structure of microvascular networks. The vast number of vessels and the highly plastic character of the microcirculation give evidence that microvascular network structures emerge as a result of responses of individual vessels and cells to the local stimuli that they experience, through a combination of angiogenesis, remodeling and pruning. The articles in this issue of Microcirculation address a range of cellular and molecular mechanisms involved in these processes. PMID:26639099

  6. Microvascular complications and diabetic retinopathy: recent advances and future implications.

    PubMed

    Barot, Megha; Gokulgandhi, Mitan R; Patel, Sulabh; Mitra, Ashim K

    2013-03-01

    Retinal microvascular alterations have been observed during diabetic retinopathy (DR) due to the retinal susceptibility towards subtle pathological alterations. Therefore, retinal microvascular pathology is essential to understand the nature of retinal degenerations during DR. In this review, the role of retinal microvasculature complications during progression of DR, along with recent efforts to normalize such alterations for better therapeutic outcome, will be underlined. In addition, current therapeutics and future directions for advancement of standard treatment for DR patients will be discussed. PMID:23464520

  7. A new detection method for a newly revealed mechanism of pyrethroid resistance development in Varroa destructor.

    PubMed

    Strachecka, Aneta; Borsuk, Grzegorz; Olszewski, Krzysztof; Paleolog, Jerzy

    2015-11-01

    The Varroa destructor mite has recently displayed an ever increasing resistance to new drugs, contributing to CCD proliferation. This work was aimed at determining new viable methods for identifying the pyrethroid resistance of V. destructor and DNA methylation in resistant and sensitive mites. DNA was extracted from Varroa mites. Nucleotide changes in the DNA of pyrethroid-resistant, pyrethroid-sensitive, and control mites were identified with polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) in the case of five mitochondrial gene fragments. More bands were observed in the drug-resistant mites than in the other two groups. Sequencing confirmed these observations. Decreased global DNA methylation levels were observed in the pyrethroid-resistant mites. There exists a previously undescribed mechanism of pyrethroid resistance development in Varroa mites. The PCR-SSCP methods can be considered and further developed as useful tools for detecting V. destructor resistance. PMID:26210302

  8. Method of lift-off patterning thin films in situ employing phase change resists

    SciTech Connect

    Bahlke, Matthias Erhard; Baldo, Marc A; Mendoza, Hiroshi Antonio

    2014-09-23

    Method for making a patterned thin film of an organic semiconductor. The method includes condensing a resist gas into a solid film onto a substrate cooled to a temperature below the condensation point of the resist gas. The condensed solid film is heated selectively with a patterned stamp to cause local direct sublimation from solid to vapor of selected portions of the solid film thereby creating a patterned resist film. An organic semiconductor film is coated on the patterned resist film and the patterned resist film is heated to cause it to sublime away and to lift off because of the phase change.

  9. Method for restoring the resistance of indium oxide semiconductors after heating while in sealed structures

    DOEpatents

    Seager, Carleton H.; Evans, Jr., Joseph Tate

    1998-01-01

    A method for counteracting increases in resistivity encountered when Indium Oxide resistive layers are subjected to high temperature annealing steps during semiconductor device fabrication. The method utilizes a recovery annealing step which returns the Indium Oxide layer to its original resistivity after a high temperature annealing step has caused the resistivity to increase. The recovery anneal comprises heating the resistive layer to a temperature between 100.degree. C. and 300.degree. C. for a period of time that depends on the annealing temperature. The recovery is observed even when the Indium Oxide layer is sealed under a dielectric layer.

  10. Method for restoring the resistance of indium oxide semiconductors after heating while in sealed structures

    DOEpatents

    Seager, C.H.; Evans, J.T. Jr.

    1998-11-24

    A method is described for counteracting increases in resistivity encountered when Indium Oxide resistive layers are subjected to high temperature annealing steps during semiconductor device fabrication. The method utilizes a recovery annealing step which returns the Indium Oxide layer to its original resistivity after a high temperature annealing step has caused the resistivity to increase. The recovery anneal comprises heating the resistive layer to a temperature between 100 C and 300 C for a period of time that depends on the annealing temperature. The recovery is observed even when the Indium Oxide layer is sealed under a dielectric layer. 1 fig.

  11. Contact resistance extraction methods for short- and long-channel carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Pacheco-Sanchez, Anibal; Claus, Martin; Mothes, Sven; Schröter, Michael

    2016-11-01

    Three different methods for the extraction of the contact resistance based on both the well-known transfer length method (TLM) and two variants of the Y-function method have been applied to simulation and experimental data of short- and long-channel CNTFETs. While for TLM special CNT test structures are mandatory, standard electrical device characteristics are sufficient for the Y-function methods. The methods have been applied to CNTFETs with low and high channel resistance. It turned out that the standard Y-function method fails to deliver the correct contact resistance in case of a relatively high channel resistance compared to the contact resistances. A physics-based validation is also given for the application of these methods based on applying traditional Si MOSFET theory to quasi-ballistic CNTFETs.

  12. Electrical resistivity characteristics of diesel oil-contaminated kaolin clay and a resistivity-based detection method.

    PubMed

    Liu, Zhibin; Liu, Songyu; Cai, Yi; Fang, Wei

    2015-06-01

    As the dielectric constant and conductivity of petroleum products are different from those of the pore water in soil, the electrical resistivity characteristics of oil-contaminated soil will be changed by the corresponding oil type and content. The contaminated soil specimens were manually prepared by static compaction method in the laboratory with commercial kaolin clay and diesel oil. The water content and dry density of the first group of soil specimens were controlled at 10 % and 1.58 g/cm(3). Corresponding electrical resistivities of the contaminated specimens were measured at the curing periods of 7, 14, and 28 and 90, 120, and 210 days on a modified oedometer cell with an LCR meter. Then, the electrical resistivity characteristics of diesel oil-contaminated kaolin clay were discussed. In order to realize a resistivity-based oil detection method, the other group of oil-contaminated kaolin clay specimens was also made and tested, but the initial water content, oil content, and dry density were controlled at 0~18 %, 0~18 %, 1.30~1.95 g/cm(3), respectively. Based on the test data, a resistivity-based artificial neural network (ANN) was developed. It was found that the electrical resistivity of kaolin clay decreased with the increase of oil content. Moreover, there was a good nonlinear relationship between electrical resistivity and corresponding oil content when the water content and dry density were kept constant. The decreasing velocity of the electrical resistivity of oil-contaminated kaolin clay was higher before the oil content of 12 % than after 12 %, which indicated a transition of the soil from pore water-controlled into oil-controlled electrical resistivity characteristics. Through microstructural analysis, the decrease of electrical resistivity could be explained by the increase of saturation degree together with the collapse of the electrical double layer. Environmental scanning electron microscopy (ESEM) photos indicated that the diesel oil

  13. Scalp reconstruction by microvascular free tissue transfer

    SciTech Connect

    Furnas, H.; Lineaweaver, W.C.; Alpert, B.S. )

    1990-05-01

    We report on a series of patients with scalp defects who have been treated with a variety of free flaps, spanning the era of microvascular free tissue transfer from its incipient stages to the present. Between 1971 and 1987, 18 patients underwent scalp reconstruction with 21 free flaps: 11 latissimus dorsi, 3 scalp transfers between identical twins, 3 groin, one combined latissimus dorsi and serratus anterior, two serratus anterior, and one omentum. These flaps were used to cover scalp defects resulting from burns, trauma, radiation, and tumors in patients ranging from 7 to 79 years of age. Follow-up has ranged from 3 weeks to 7 years. All of our flaps survived and covered complex defects, many of which had failed more conservative attempts at cover. One patient received radiation therapy to his flap without unfavorable sequelae. This experience began with a pioneering omental flap and includes cutaneous and muscle flaps. The latissimus dorsi is our first choice for free flap reconstruction of extensive, complicated scalp wounds because of its large size, predictable blood supply, ease of harvesting, and provision of excellent vascularity to compromised beds.

  14. Influence of silicone sheets on microvascular anastomosis.

    PubMed

    Hoang Nguyen, The; Kloeppel, Marcus; Hoehnke, Christoph; Staudenmaier, Rainer

    2008-12-01

    The use of silicone products combined with free flap transfer is well established in reconstructive surgery. We determined the risk of thrombosis as a result of direct contact between the silicone sheet and the point of microanastomosis. We performed microvascular surgery in 24 female Chinchilla Bastard rabbits weighing 3500 to 4000 g using two groups: Group 1 (n = 12), microanastomosis directly in contact with silicone sheets; and Group 2 (n = 12), microanastomosis protected by a 2 x 3 x 1-cm muscle cuff before being placed in contact with the silicone. We assessed flow-through of the microanastomosis by selective microangiography and histology at 1 and 3 weeks. All microanastomoses in Group 1 were occluded by postoperative thromboses, whereas all microanastomoses in Group 2 had adequate flow-through. Histologic analysis revealed thromboses in Group 1 formed from collagenous bundles of fiber securely attached to the intraluminal wall of the vessel. Three weeks after the procedure, these thromboses were canalized by varying small vessels. In Group 2, a slight luminal stenosis with evidence of infiltration of inflammatory cells at the microanastomosis line was observed histologically in all cases. Prefabricated flaps using silicone sheets and muscular cuffs placed around the anastomoses appear to reduce the risk of thrombosis and enhance neovascularization. PMID:18636304

  15. Colistin and tigecycline resistance in carbapenemase-producing Gram-negative bacteria: emerging resistance mechanisms and detection methods.

    PubMed

    Osei Sekyere, J; Govinden, U; Bester, L A; Essack, S Y

    2016-09-01

    A literature review was undertaken to ascertain the molecular basis for tigecycline and colistin resistance mechanisms and the experimental basis for the detection and delineation of this resistance particularly in carbapenemase-producing Gram-negative bacteria. Pubmed, Google Scholar and Science Direct were searched with the keywords colistin, tigecycline, resistance mechanisms and detection methods. Trans-complementation and comparative MIC studies, mass spectrometry, chromatography, spectrofluorometry, PCR, qRT-PCR and whole genome sequencing (WGS) were commonly used to determine tigecycline and colistin resistance mechanisms, specifically modifications in the structural and regulatory efflux (acrAB, OqxAB, kpgABC adeABC-FGH-IJK, mexAB-XY-oprJM and soxS, rarA robA, ramRAB marRABC, adeLRS, mexRZ and nfxb) and lipid A (pmrHFIJFKLM, lpxA, lpxC lpxD and mgrB, pmrAB, phoPQ,) genes respectively. Mutations in the ribosomal 16S rRNA operon rrnBC, also yielded resistance to tigecycline through target site modifications. The mcr-1 gene conferring resistance to colistin was identified via WGS, trans-complementation and a murine thigh infection model studies. Common detection methods are mainly antibiotic sensitivity testing with broth microdilution while molecular identification tools are mostly PCR and WGS. Spectrofluorometry, MALDI-TOF MS, micro-array and real-time multiplex PCR hold much promise for the future as new detection tools.

  16. Citrulline does not enhance blood flow, microvascular circulation, or myofibrillar protein synthesis in elderly men at rest or following exercise.

    PubMed

    Churchward-Venne, Tyler A; Cotie, Lisa M; MacDonald, Maureen J; Mitchell, Cameron J; Prior, Todd; Baker, Steven K; Phillips, Stuart M

    2014-07-01

    Aging is associated with anabolic resistance, a reduced sensitivity of myofibrillar protein synthesis (MPS) to postprandial hyperaminoacidemia, particularly with low protein doses. Impairments in postprandial skeletal muscle blood flow and/or microvascular perfusion with hyperaminoacidemia and hyperinsulinemia may contribute to anabolic resistance. We examined whether providing citrulline, a precursor for arginine and nitric oxide synthesis, would increase arterial blood flow, skeletal muscle microvascular perfusion, MPS, and signaling through mTORC1. Twenty-one elderly males (65-80 yr) completed acute unilateral resistance exercise prior to being assigned to ingest a high dose (45 g) of whey protein (WHEY) or a low dose (15 g) of whey protein with 10 g of citrulline (WHEY + CIT) or with 10 g of nonessential amino acids (WHEY + NEAA). A primed, continuous infusion of L-[ring-(13)C6] phenylalanine with serial muscle biopsies was used to measure MPS and protein phosphorylation, whereas ultrasound was used to measure microvascular circulation under basal and postprandial conditions in both a rested (FED) and exercised (EX-FED) leg. Argininemia was greater in WHEY + CIT vs. WHEY and WHEY + NEAA from 30 to 300 min postexercise (P < 0.001), but there were no treatment differences in blood flow or microvascular perfusion (all P > 0.05). Phosphorylation of p70S6K-Thr(389) was greater in WHEY vs. WHEY + NEAA (P = 0.02). Postprandial MPS was greater in WHEY vs. WHEY + CIT and WHEY + NEAA under both FED (WHEY: ~128%; WHEY + CIT: ~56%; WHEY + NEAA: ~38%) and EX-FED (WHEY: ~251%; WHEY + CIT: ~124%; WHEY + NEAA: ~108%) conditions (P = 0.003). Citrulline coingestion with a low quantity of protein was ineffective in augmenting the anabolic properties of protein compared with nonessential amino acids.

  17. Withdrawing intra-aortic balloon pump support paradoxically improves microvascular flow

    PubMed Central

    2010-01-01

    Introduction The Intra-Aortic Balloon Pump (IABP) is frequently used to mechanically support the heart. There is evidence that IABP improves microvascular flow during cardiogenic shock but its influence on the human microcirculation in patients deemed ready for discontinuing IABP support has not yet been studied. Therefore we used sidestream dark field imaging (SDF) to test our hypothesis that human microcirculation remains unaltered with or without IABP support in patients clinically ready for discontinuation of mechanical support. Methods We studied 15 ICU patients on IABP therapy. Measurements were performed after the clinical decision was made to remove the balloon catheter. We recorded global hemodynamic parameters and performed venous oximetry during maximal IABP support (1:1) and 10 minutes after temporarily stopping the IABP therapy. At both time points, we also recorded video clips of the sublingual microcirculation. From these we determined indices of microvascular perfusion including perfused vessel density (PVD) and microvascular flow index (MFI). Results Ceasing IABP support lowered mean arterial pressure (74 ± 8 to 71 ± 10 mmHg; P = 0.048) and increased diastolic pressure (43 ± 10 to 53 ± 9 mmHg; P = 0.0002). However, at the level of the microcirculation we found an increase of PVD of small vessels <20 μm (5.47 ± 1.76 to 6.63 ± 1.90; P = 0.0039). PVD for vessels >20 μm and MFI for both small and large vessels were unaltered. During the procedure global oxygenation parameters (ScvO2/SvO2) remained unchanged. Conclusions In patients deemed ready for discontinuing IABP support according to current practice, SDF imaging showed an increase of microcirculatory flow of small vessels after ceasing IABP therapy. This observation may indicate that IABP impairs microvascular perfusion in recovered patients, although this warrants confirmation. PMID:20738876

  18. Prevalence of Microvascular Complications in Newly Diagnosed Patients with Type 2 Diabetes

    PubMed Central

    Ali, Alia; Iqbal, Farrukh; Taj, Azeem; Iqbal, Zafar; Amin, Muhammad Joher; Iqbal, Qasim Zafar

    2013-01-01

    Background & Objective: Microvascular complications are the major outcome of type 2 Diabetes Mellitus progression, which reduce the quality of life, incur heavy economic burdens to the health care system and increase diabetic mortality. The aims of this study were to assess the prevalence of microvascular complications among newly diagnosed type 2 diabetic patients and to analyze the association between these complications and poor glycemic control. Methods: This cross sectional hospital based study was carried out in Diabetic Clinic of Shaikh Zayed Postgraduate Medical Institute, Lahore Pakistan. The study was conducted from November 2011 to November 2012 among newly diagnosed type 2 diabetic patients. Relevant information of all patients was recorded with the help of a proforma. They were investigated for retinopathy, nephropathy and neuropathy. Results: We have divided the patients into two groups: Group I with good glycemic control (HbA1c <6.5) and group II with poor glycemic control (HbA1c >6.5). In group II microvascular complications were 89.8%. Neuropathy, nephropathy and retinopathy were present in 68.5%, 56.2% and 31.4% respectively. These similar percentages in Group I were 50%, 0% and 31% respectively and are significantly lower. Conclusion: The study showed that even in newly diagnosed type 2 diabetic patients who had poor glycemic control, frequency of microvascular complications is much higher as compared to those who had average glycemic control. Thus tight glycemic control does count even in newly diagnosed type 2 diabetics to prevent and minimize the occurrence of complications. PMID:24353655

  19. Differential resistances to anthracnose in Capsicum baccatum as responding to two Colletotrichum pathotypes and inoculation methods.

    PubMed

    Mahasuk, Pitchayapa; Chinthaisong, Jittima; Mongkolporn, Orarat

    2013-09-01

    Chili anthracnose, caused by Colletotrichum spp., is one of the major diseases to chili production in the tropics and subtropics worldwide. Breeding for durable anthracnose resistance requires a good understanding of the resistance mechanisms to different pathotypes and inoculation methods. This study aimed to investigate the inheritances of differential resistances as responding to two different Colletotrichum pathotypes, PCa2 and PCa3 and as by two different inoculation methods, microinjection (MI) and high pressure spray (HP). Detached ripe fruit of Capsicum baccatum 'PBC80' derived F2 and BC1s populations was assessed for anthracnose resistance. Two dominant genes were identified responsible for the differential resistance to anthracnose. One was responsible for the resistance to PCa2 and PCa3 by MI and the other was responsible for the resistance to PCa3 by HP. The two genes were linked with 16.7 cM distance. PMID:24273429

  20. A Micro-delivery Approach for Studying Microvascular Responses to Localized Oxygen Delivery

    PubMed Central

    Ghonaim, Nour W.; Lau, Leo W. M.; Goldman, Daniel; Ellis, Christopher G.; Yang, Jun

    2011-01-01

    In vivo video microscopy has been used to study blood flow regulation as a function of varying oxygen concentration in microcirculatory networks. However, previous studies have measured the collective response of stimulating large areas of the microvascular network at the tissue surface. Objective We aim to limit the area being stimulated by controlling oxygen availability to highly localized regions of the microvascular bed within intact muscle. Design and Method Gas of varying O2 levels was delivered to specific locations on the surface of the Extensor Digitorum Longus muscle of rat through a set of micro-outlets (100 μm diameter) patterned in ultrathin glass using state-of-the-art microfabrication techniques. O2 levels were oscillated and digitized video sequences were processed for changes in capillary hemodynamics and erythrocyte O2 saturation. Results and Conclusions Oxygen saturations in capillaries positioned directly above the micro-outlets were closely associated with the controlled local O2 oscillations. Radial diffusion from the micro-outlet is limited to ~75 μm from the center as predicted by computational modelling and as measured in vivo. These results delineate a key step in the design of a novel micro-delivery device for controlled oxygen delivery to the microvasculature to understand fundamental mechanisms of microvascular regulation of O2 supply. PMID:21914035

  1. Air Pollution Particulate Matter Collected from an Appalachian Mountaintop Mining Site Induces Microvascular Dysfunction

    PubMed Central

    KNUCKLES, TRAVIS L.; STAPLETON, PHOEBE A.; MINARCHICK, VALERIE C.; ESCH, LAURA; MCCAWLEY, MICHAEL; HENDRYX, MICHAEL; NURKIEWICZ, TIMOTHY R.

    2016-01-01

    Objective Air pollution PM is associated with cardiovascular morbidity and mortality. In Appalachia, PM from mining may represent a health burden to this sensitive population that leads the nation in cardiovascular disease, among others. Cardiovascular consequences following inhalation of PMMTM are unclear, but must be identified to establish causal effects. Methods PM was collected within 1 mile of an active MTM site in southern WV. The PM was extracted and was primarily <10μm in diameter (PM10), consisting largely of sulfur (38%) and silica (24%). Adult male rats were IT with 300 μg PMMTM. Twenty-four hours following exposure, rats were prepared for intravital microscopy, or isolated arteriole experiments. Results PMMTM exposure blunted endothelium-dependent dilation in mesenteric and coronary arterioles by 26%, and 25%, respectively, as well as endothelium-independent dilation. In vivo, PMMTM exposure inhibited endothelium-dependent arteriolar dilation (60% reduction). α-adrenergic receptor blockade inhibited PVNS-induced vasoconstriction in exposed animals compared with sham. Conclusions These data suggest that PMMTM exposure impairs microvascular function in disparate microvascular beds, through alterations in NO-mediated dilation and sympathetic nerve influences. Microvascular dysfunction may contribute to cardiovascular disease in regions with MTM sites. PMID:22963349

  2. Microvascular Reconstruction of Free Jejunal Graft in Larynx-preserving Esophagectomy for Cervical Esophageal Carcinoma

    PubMed Central

    Natori, Yuhei; Komoto, Masakazu; Matsumura, Takashi; Horiguchi, Masatoshi; Yoshizawa, Hidekazu; Iwanuma, Yoshimi; Tsurumaru, Masahioko; Kajiyama, Yoshiaki; Mizuno, Hiroshi

    2016-01-01

    Background: Losing the ability to speak severely affects the quality of life, and patients who have undergone laryngectomy tend to become depressed, which may lead to social withdrawal. Recently, with advancements in chemoradiotherapy and with alternative perspectives on postoperative quality of life, larynx preservation has been pursued; however, the selection of candidates and the optimal reconstructive procedure remain controversial. In this study, we retrospectively reviewed our experience with free jejunal graft for larynx-preserving cervical esophagectomy (LPCE), focusing on microvascular reconstruction. Methods: Seven patients underwent LPCE for cervical esophageal carcinoma, and defects were reconstructed by free jejunal transfer subsequently. We collected preoperative and postoperative data of the patients and assessed the importance of the procedure. Results: We mostly used the transverse cervical artery as the recipient, and a longer operative time was required, particularly for the regrowth cases. The operative field for microvascular anastomosis was more limited and deeper than those in the laryngectomy cases. Two graft necrosis cases were confirmed at postoperative day 9 or 15, and vessels contralateral from the graft were chosen as recipients in both patients. Conclusions: Microvascular reconstruction for free jejunal graft in LPCE differed in several ways from the procedure combined with laryngectomy. Compression from the tracheal cartilage to the pedicle was suspected as the reason of the necrosis clinically and pathologically. Therefore, we should select recipient vessels from the ipsilateral side of the graft, and careful and extended monitoring of the flap should be considered to make this procedure successful. PMID:27257562

  3. Resistivity Imaging of Spring Valley, Nevada Using the Audiomagnetotelluric Method

    NASA Astrophysics Data System (ADS)

    McPhee, D. K.; Pellerin, L.; Chuchel, B.; Dixon, G. L.

    2005-05-01

    Audiomagnetotelluric (AMT) sounding data collected in Spring Valley, NV show significant two-dimensional (2D) structure within the upper kilometer of the valley and help define the shallow basement surface. We collected AMT data along two profiles in the southern part of Spring Valley in the Fall 2004, using the Geometrics StrataGem EH4 system, a four channel, natural and controlled-source tensor system recording in the range of 10 to 92,000 Hz. To augment the low signal in the natural field a transmitter of two horizontal-magnetic dipoles was used from 1,000 to 70,000 Hz. Profile A extends 12.6 km from the Fortification Range on the west across southern Spring Valley to the Limestone Hills in the east with soundings recorded every 200 m. Profile B is a 2-km long, roughly E-W trending line located at the northern margin of the Fortification Range, roughly parallel to and 12 km NW of Profile A, with sounding spacings of 200-400 m. Data were recorded with the electrical field (E) parallel and perpendicular to the regional geological strike direction. We computed our preferred two-dimensional, inverse models from the E perpendicular mode data using the conjugate gradient, finite-difference method of Rodi and Mackie (2001) and a 100 ohm-m half-space, starting model. Inverse models were also computed using both modes and an equivalent model resulted, with a slightly higher RMS fit, indicating the two-dimensionality of the structure. Various starting models were used to test the depth of investigation. The model along Profile A shows detailed structure within the alluvial basin. Preliminary interpretation shows a clear transition between unsaturated (200-500 ohm-m) and saturated alluvium/volcanic rocks (20-50 ohm-m) at roughly 100 m depth. Highly-resistive (>1000 ohm-m) carbonate rocks are clearly defined at the east end of Profile A, and the locations and dips of several range-front and inter-basin faults, which lack surface expression, are delineated throughout the

  4. Adaptive Motor Resistance Video Game Exercise Apparatus and Method of Use Thereof

    NASA Technical Reports Server (NTRS)

    Reich, Alton (Inventor); Shaw, James (Inventor)

    2015-01-01

    The invention comprises a method and/or an apparatus using computer configured exercise equipment and an electric motor provided physical resistance in conjunction with a game system, such as a video game system, where the exercise system provides real physical resistance to a user interface. Results of user interaction with the user interface are integrated into a video game, such as running on a game console. The resistance system comprises: a subject interface, software control, a controller, an electric servo assist/resist motor, an actuator, and/or a subject sensor. The system provides actual physical interaction with a resistance device as input to the game console and game run thereon.

  5. A novel Direct MIC-gradient Strip Method to screen for antibiotic-resistant faecal Enterobacteriaceae.

    PubMed

    Gammelsrud, Karianne Wiger; Knudsen, Per Kristian; Høiby, E Arne

    2016-10-01

    A novel method to detect resistant faecal Enterobacteriaceae was developed by applying MIC-gradient strips directly onto agar plates inoculated with faeces. The method provided the susceptibility pattern (MICs) of the dominant bacterial population directly on the plates and also detected smaller resistant subpopulations with a sensitivity of 1/10(5).

  6. Evaluation of coronary microvascular function in patients with vasospastic angina

    PubMed Central

    Teragawa, Hiroki; Mitsuba, Naoya; Ishibashi, Ken; Nishioka, Kenji; Kurisu, Satoshi; Kihara, Yasuki

    2013-01-01

    AIM: To investigate endothelium-dependent and -independent coronary microvascular functions in patients with vasospastic angina (VSA). METHODS: Thirty-six patients with VSA (30 men and 6 women; mean age, 58 years) were enrolled in this study. VSA was defined as ≥ 90% narrowing of the epicardial coronary arteries on angiography performed during a spasm provocation test, presence of chest pain, and/or ST-segment deviation on an electrocardiogram (ECG). Patients (n = 36) with negative spasm provocation test results and those matched for age and sex were enrolled as a control group (nonVSA group). Low-dose acetylcholine (ACh; 3 μg/min) was infused into the left coronary ostium for 2 min during the spasm provocation test. Following the spasm provocation test, nitroglycerin (0.2 mg) was administered intracoronally. Coronary blood flow (was calculated from quantitative angiography and Doppler flow velocity measurements, and the coronary flow reserve was calculated as the ratio of coronary flow velocity after injection of adenosine triphosphate (20 μg) to the baseline value. Changes in the coronary artery diameter in response to ACh and nitroglycerin infusion were expressed as percentage changes from baseline measurements. RESULTS: Body mass index was significantly lower in the VSA group than in the nonVSA group. The frequency of conventional coronary risk factors and the rate of statin use were similar between the 2 groups. The left ventricular ejection fraction as evaluated by echocardiography was similar between the 2 groups. The duration of angina was 9 ± 2 mo. The results of blood chemistry analysis were similar between the 2 groups. Low-dose ACh did not cause coronary spasms. The change in coronary artery diameter in response to ACh was lower in the VSA group (-1.4% ± 9.3%) than in the nonVSA group (3.1% ± 6.5%, P < 0.05), whereas nitroglycerin-induced coronary artery dilatation and coronary blood flow increase in response to ACh or coronary flow reserve did

  7. Modeling of Cerebral Oxygen Transport Based on In vivo Microscopic Imaging of Microvascular Network Structure, Blood Flow, and Oxygenation

    PubMed Central

    Gagnon, Louis; Smith, Amy F.; Boas, David A.; Devor, Anna; Secomb, Timothy W.; Sakadžić, Sava

    2016-01-01

    Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These “bottom-up” models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans.

  8. Modeling of Cerebral Oxygen Transport Based on In vivo Microscopic Imaging of Microvascular Network Structure, Blood Flow, and Oxygenation

    PubMed Central

    Gagnon, Louis; Smith, Amy F.; Boas, David A.; Devor, Anna; Secomb, Timothy W.; Sakadžić, Sava

    2016-01-01

    Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These “bottom-up” models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans. PMID:27630556

  9. Modeling of Cerebral Oxygen Transport Based on In vivo Microscopic Imaging of Microvascular Network Structure, Blood Flow, and Oxygenation.

    PubMed

    Gagnon, Louis; Smith, Amy F; Boas, David A; Devor, Anna; Secomb, Timothy W; Sakadžić, Sava

    2016-01-01

    Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These "bottom-up" models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans. PMID:27630556

  10. Methicillin Resistant Staphylococcus aureus: Inconsistencies in Vancomycin Susceptibility Testing Methods, Limitations and Advantages of each Method

    PubMed Central

    Himani; Madan, Molly; Pandey, Anita; Thakuria, Bhaskar

    2015-01-01

    Background Vancomycin may be ineffective against an increasing proportion of methicillin resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentrations (MICs) well within the susceptible range. On the other hand it is common knowledge that determination of vancomycin MICs is method dependent. Therefore, given the apparent variability in vancomycin MIC results obtained with the different methods, the use of the vancomycin MIC to predict the outcome of serious S. aureus infections needs to take into account the method used and the results of studies using that particular method. Aim Comparative study was carried out to evaluate the MICs obtained by BMD method, E-test, and Vitek 2 method and to detect inconsistencies in these vancomycin for 66 MRSA isolates obtained from various samples of patients attending the OPDs & IPDs within a period of one year. Materials and Methods A comparative study was carried out to evaluate the MICs obtained by BMD method, E-test, and Vitek 2 method to detect vancomycin susceptibility in 66 clinical isolates of MRSA obtained from various samples of patients attending the OPDs & IPDs within a period of one year. The study was conducted in Department of Microbiology, Subharti Medical College, Meerut from January to December 2012. Results On determination of MICs for vancomycin for the MRSA isolates, all were identified as VSSA by BMD, E-Test & Vitek 2 methods. However, the vancomycin MIC values obtained by E-test correlated better with BMD method (correlation factor= 0.6727) than Vitek 2 (correlation factor=0.5316), indicating E-Test to be a better method for determination of vancomycin MICs as compared to Vitek 2. Conclusion MRSA isolates with higher vancomycin MICs, even within the susceptibility range, are being observed more frequently which result in treatment failures with vancomycin. Because of the discrepancy that exists in vancomycin MIC results from different methods, the prediction of outcome of serious S

  11. Bariatric surgery and microvascular complications of type 2 diabetes mellitus.

    PubMed

    Jackson, Sabrina; le Roux, Carel W; Docherty, Neil G

    2014-11-01

    Metabolic dysregulation is the defining characteristic of type 2 diabetes mellitus (T2DM) and can give rise to microvascular complications, specifically retinopathy, nephropathy and neuropathy. Pharmacological targeting of risk factors for microvascular complications can yield therapeutic gains, particularly in relation to retinopathy and nephropathy. Bariatric surgery is superior to intensified pharmacotherapy in relation to glycaemic control and can remediate dyslipidaemia and hypertension. Consequently, evidence of the effect of bariatric surgery on microvascular complications is now emerging in the literature. Examination of the recent published evidence base (covering the period 2011-2014) on the effects of bariatric surgery on microvascular complications reveals further evidence supportive of the efficacy of bariatric surgery in preventing the incidence and progression of albuminuria and arresting renal functional decline. Data on retinopathy are more ambivalent potentially representing the potential in some cases for a degree of surgery associated reactive hypoglycaemia to detract from the benefits of amelioration of hyperglycaemia. A significant gap in the literature remains in relation to the effects of surgery on diabetic neuropathy. Overall, there is a pressing need for prospective randomised controlled trials examining long-term microvascular outcomes following bariatric surgery in patients with T2DM.

  12. Evaluation of microvascular structure in humans: a 'state-of-the-art' document of the Working Group on Macrovascular and Microvascular Alterations of the Italian Society of Arterial Hypertension.

    PubMed

    Virdis, Agostino; Savoia, Carmine; Grassi, Guido; Lembo, Giuseppe; Vecchione, Carmine; Seravalle, Gino; Taddei, Stefano; Volpe, Massimo; Rosei, Enrico Agabiti; Rizzoni, Damiano

    2014-11-01

    The evaluation of microvascular structure is, in general, not an easy task. Among the methods that may be applied to humans, plethysmographic evaluation of small arteries and wire or pressure micromyography were extensively used in the last decades. The media-to-lumen ratio of small arteries evaluated by micromyography was demonstrated to possess a strong prognostic significance; however, its extensive evaluation is limited by the local invasiveness of the assessment. Noninvasive approaches were then proposed, including capillaroscopy, which provides information about microvascular rarefaction. Recently, the interest of investigators was focused on the retinal microvascular bed. In particular, a noninvasive measurement of the wall-to-lumen ratio of retinal arterioles using scanning laser Doppler flowmetry has been introduced.Recent data suggest a rather good agreement between this approach and micromyographic measurements, generally considered the gold standard approach. Therefore, the evaluation of microvascular structure is progressively moving from bench to bedside, and it could represent, in the immediate future, an evaluation to be performed in all hypertensive patients, in order to obtain a better stratification of cardiovascular risk.

  13. Hypercholesterolemia and microvascular dysfunction: interventional strategies.

    PubMed

    Stapleton, Phoebe A; Goodwill, Adam G; James, Milinda E; Brock, Robert W; Frisbee, Jefferson C

    2010-01-01

    Hypercholesterolemia is defined as excessively high plasma cholesterol levels, and is a strong risk factor for many negative cardiovascular events. Total cholesterol levels above 200 mg/dl have repeatedly been correlated as an independent risk factor for development of peripheral vascular (PVD) and coronary artery disease (CAD), and considerable attention has been directed toward evaluating mechanisms by which hypercholesterolemia may impact vascular outcomes; these include both results of direct cholesterol lowering therapies and alternative interventions for improving vascular function. With specific relevance to the microcirculation, it has been clearly demonstrated that evolution of hypercholesterolemia is associated with endothelial cell dysfunction, a near-complete abrogation in vascular nitric oxide bioavailability, elevated oxidant stress, and the creation of a strongly pro-inflammatory condition; symptoms which can culminate in profound impairments/alterations to vascular reactivity. Effective interventional treatments can be challenging as certain genetic risk factors simply cannot be ignored. However, some hypercholesterolemia treatment options that have become widely used, including pharmaceutical therapies which can decrease circulating cholesterol by preventing either its formation in the liver or its absorption in the intestine, also have pleiotropic effects with can directly improve peripheral vascular outcomes. While physical activity is known to decrease PVD/CAD risk factors, including obesity, psychological stress, impaired glycemic control, and hypertension, this will also increase circulating levels of high density lipoprotein and improving both cardiac and vascular function. This review will provide an overview of the mechanistic consequences of the predominant pharmaceutical interventions and chronic exercise to treat hypercholesterolemia through their impacts on chronic sub-acute inflammation, oxidative stress, and microvascular structure

  14. METHOD FOR REDUCING THE IMPURITY RESISTIVITY OF SODIUM

    DOEpatents

    Post, R.F.; Taylor, C.E.

    1963-08-13

    The inherent resistivity of sodium, at cryogenic temperatures, can be reduced by clustering the impurity atoms within the crystal latiice structure of the sodium, thereby reducing the effective electron collision cross section and thus reducing the number of collisions between the electrons and such lattice imperfections. The clustering is effected by heating the sodium to a temperature approaching its melting point, and maintaining the temperature for a period of time ranging generally from two to six days. (AEC)

  15. Isolation and characterization of equine microvascular endothelial cells in vitro.

    PubMed

    Bochsler, P N; Slauson, D O; Chandler, S K; Suyemoto, M M

    1989-10-01

    The use of cultured tissue has not yet become widespread in research involving equine disease, and this may be attributable in part to the scarcity of published reports concerning tissue culture methods for this species. We report here the isolation of equine microvascular endothelium (EMVE) from fresh omental tissue of horses and ponies. Fresh donor tissue was minced, subjected to collagenase digestion, and filtered. Cells were layered on 5% bovine serum albumin for gravity sedimentation, the bottom layer was collected, and the cells were plated onto fibronectin-coated flasks. Medium consisted of Dulbecco modified Eagle medium with 10% whole fetal bovine serum (wFBS) and 20 micrograms of endothelial cell growth supplement/ml. The EMVE grew readily in culture, had the cobblestone morphologic feature at confluence, stained positively for factor VIII-related antigen, and metabolized acetylated low-density lipoprotein. Fibroblast and smooth muscle cell contamination was minimal in primary cell cultures, which were successfully passed and maintained in culture for 3 to 5 serial passages, using various media and substrates. Preliminary studies were undertaken to determine optimal growth conditions with a range of variables: serum concentration, extracellular matrix components, and growth factors, Optimal conditions were achieved with a minimum of 10% wFBS, and with either fibronectin or laminin as extracellular matrix substrates. The EMVE grew adequately in Dulbecco modified Eagle medium plus 10% wFBS, and the added growth factors or serum supplements did not appear necessary for growth of EMVE.

  16. Holographic laser Doppler imaging of microvascular blood flow.

    PubMed

    Magnain, C; Castel, A; Boucneau, T; Simonutti, M; Ferezou, I; Rancillac, A; Vitalis, T; Sahel, J A; Paques, M; Atlan, M

    2014-12-01

    We report on local superficial blood flow monitoring in biological tissue from laser Doppler holographic imaging. In time-averaging recording conditions, holography acts as a narrowband bandpass filter, which, combined with a frequency-shifted reference beam, permits frequency-selective imaging in the radio frequency range. These Doppler images are acquired with an off-axis Mach-Zehnder interferometer. Microvascular hemodynamic components mapping is performed in the cerebral cortex of the mouse and the eye fundus of the rat with near-infrared laser light without any exogenous marker. These measures are made from a basic inverse-method analysis of local first-order optical fluctuation spectra at low radio frequencies, from 0 Hz to 100 kHz. Local quadratic velocity is derived from Doppler broadenings induced by fluid flows, with elementary diffusing wave spectroscopy formalism in backscattering configuration. We demonstrate quadratic mean velocity assessment in the 0.1-10 mm/s range in vitro and imaging of superficial blood perfusion with a spatial resolution of about 10 micrometers in rodent models of cortical and retinal blood flow.

  17. Multimodal reconstruction of microvascular-flow distributions using combined two-photon microscopy and Doppler optical coherence tomography

    PubMed Central

    Gagnon, Louis; Sakadžić, Sava; Lesage, Fréderic; Mandeville, Emiri T.; Fang, Qianqian; Yaseen, Mohammad A.; Boas, David A.

    2015-01-01

    Abstract. Computing microvascular cerebral blood flow (μCBF) in real cortical angiograms is challenging. Here, we investigated whether the use of Doppler optical coherence tomography (DOCT) flow measurements in individual vessel segments can help in reconstructing μCBF across the entire vasculature of a truncated cortical angiogram. A μCBF computational framework integrating DOCT measurements is presented. Simulations performed on a synthetic angiogram showed that the addition of DOCT measurements, especially close to large inflowing or outflowing vessels, reduces the impact of pressure boundary conditions and estimated vessel resistances resulting in a more accurate reconstruction of μCBF. Our technique was then applied to reconstruct microvascular flow distributions in the mouse cortex down to 660  μm by combining two-photon laser scanning microscopy angiography with DOCT. PMID:26157987

  18. Multimodal reconstruction of microvascular-flow distributions using combined two-photon microscopy and Doppler optical coherence tomography.

    PubMed

    Gagnon, Louis; Sakadžić, Sava; Lesage, Fréderic; Mandeville, Emiri T; Fang, Qianqian; Yaseen, Mohammad A; Boas, David A

    2015-01-01

    Computing microvascular cerebral blood flow ([Formula: see text]) in real cortical angiograms is challenging. Here, we investigated whether the use of Doppler optical coherence tomography (DOCT) flow measurements in individual vessel segments can help in reconstructing [Formula: see text] across the entire vasculature of a truncated cortical angiogram. A [Formula: see text] computational framework integrating DOCT measurements is presented. Simulations performed on a synthetic angiogram showed that the addition of DOCT measurements, especially close to large inflowing or outflowing vessels, reduces the impact of pressure boundary conditions and estimated vessel resistances resulting in a more accurate reconstruction of [Formula: see text]. Our technique was then applied to reconstruct microvascular flow distributions in the mouse cortex down to [Formula: see text] by combining two-photon laser scanning microscopy angiography with DOCT.

  19. Free and microvascular bone grafting in the irradiated dog mandible

    SciTech Connect

    Altobelli, D.E.; Lorente, C.A.; Handren, J.H. Jr.; Young, J.; Donoff, R.B.; May, J.W. Jr.

    1987-01-01

    Microvascular and free rib grafts were placed in 4.5 cm defects in an edentate mandibular body defect 18 to 28 days after completion of 50 Gy of irradiation from a /sup 60/Co source. The animals were sacrificed from two to forty weeks postoperatively and evaluated clinically, radiographically, and histologically. There was a marked difference in the alveolar mucosal viability with the two grafts. Mucosal dehiscence was not observed over any of the microvascular grafts, but was present in seven-eighths of the free grafts. Union of the microvascular bone graft to the host bone occurred within six weeks. In contrast, after six weeks the free graft was sequestered in all the animals. An unexpected finding with both types of graft was the marked subperiosteal bone formation. This bone appeared to be derived from the host bed, stabilizing and bridging the defects bilaterally. The results suggest that radiated periosteum may play an important role in osteogenesis.

  20. Regional cutaneous microvascular flow responses during gravitational and LBNP stresses

    NASA Technical Reports Server (NTRS)

    Breit, Gregory A.; Watenpaugh, Donald E.; Ballard, Richard E.; Murthy, Gita; Hargens, Alan R.

    1993-01-01

    Due to the regional variability of local hydrostatic pressures, microvascular flow responses to gravitational stress probably vary along the length of the body. Although these differences in local autoregulation have been observed previously during whole-body tilting, they have not been investigated during application of artificial gravitational stresses, such as lower body negative pressure or high gravity centrifugation. Although these stresses can create equivalent G-levels at the feet, they result in distinct distributions of vascular transmural pressure along the length of the body, and should consequently elicit different magnitudes and distributions of microvascular response. In the present study, the effects of whole-body tilting and lower body negative pressure on the level and distribution of microvascular flows within skin along the length of the body were compared.

  1. Vascular grafts in microvascular surgery. An experimental study

    SciTech Connect

    Marrangoni, A.G.; Marcelli, G.; Culig, M.; Simone, S.T.

    1988-02-01

    The patency of microvascular grafts depends on the luminal diameter, which is determined by the amount of fibrin and platelets deposited on the intraluminal surface and the anastomotic site, and the extent of pseudointimal formation. An experimental microvascular model in rats has been developed in our laboratory using Indium-111-labeled platelets to measure the amount of deposition on grafts inserted into the infrarenal aorta. This study was designed to assess the patency rates in these grafts and the pathologic maturation as determined by light and electron microscopy. Our study suggests that substantial patency rates can be achieved in aspirin-treated rats, although there was little influence on the pathologic maturation. Indium-111 oxine-labeled platelets can be used to document platelet aggregation, and the technique can be a valuable adjunct in the study of microvascular grafts.

  2. Glycogen Synthase Kinase-3 Inhibitor Protects Against Microvascular Hyperpermeability Following Hemorrhagic Shock

    PubMed Central

    Sawant, Devendra A.; Tharakan, Binu; Hunter, Felicia A.; Childs, Ed W.

    2015-01-01

    Background Hemorrhagic shock (HS)-induce microvascular hyperpermeability involves disruption of endothelial cell adherens junctions leading to increase in paracellular permeability. β-Catenin, an integral component of the adherens junctional complex and Wnt pathway, and caspase-3 via its apoptotic signaling regulate endothelial cell barrier integrity. We have hypothesized that inhibiting phosphorylation of β-catenin and caspase-3 activity using glycogen synthase kinase-3 (GSK-3) specific inhibitor SB216763, would attenuate microvascular hyperpermeability following HS. Methods In Sprague-Dawley rats, HS was induced by withdrawing blood to reduce mean arterial pressure to 40 mmHg for 60 minutes followed by resuscitation. Rats were given SB216763 (600 μg/kg) intravenously 10 minutes prior to shock. To study microvascular permeability, the rats were injected intravenously with FITC-albumin (50 mg/kg) and its flux across the mesenteric post-capillary venules was determined using intravital microscopy. In cell-culture studies, rat lung microvascular endothelial cell (RLMEC) monolayers grown on Transwell plates were pre-treated with SB216763 (5 μM) followed by BAK (5 μg/mL) and caspase-3 (5 μg/mL) protein transfection. FITC-albumin (5 mg/mL) flux across cell monolayers indicates change in monolayer permeability. Activity of canonical Wnt pathway was determined by luciferase assay. Caspase-3 enzyme activity was assayed fluorometrically. Results The HS group showed significant increase in FITC-albumin extravasation (p<0.05) compared with sham. SB216763 significantly decrease HS-induced FITC-albumin extravasation (p<0.05). Pre-treatment with SB216763, protected against a BAK-induced increase in RLMEC monolayer permeability and caspase-3 activity, but failed to show similar results with a caspase-3-induced increase in monolayer permeability. Wnt3a treatment showed an increase in β-catenin dependent TCF-mediated transcription. Conclusion Inhibiting phosphorylation of

  3. Oxygen-resistant hydrogenases and methods for designing and making same

    DOEpatents

    King, Paul; Ghirardi, Maria Lucia; Seibert, Michael

    2014-03-04

    The invention provides oxygen-resistant iron-hydrogenases ([Fe]-hydrogenases) for use in the production of H.sub.2. Methods used in the design and engineering of the oxygen-resistant [Fe]-hydrogenases are disclosed, as are the methods of transforming and culturing appropriate host cells with the oxygen-resistant [Fe]-hydrogenases. Finally, the invention provides methods for utilizing the transformed, oxygen insensitive, host cells in the bulk production of H.sub.2 in a light catalyzed reaction having water as the reactant.

  4. Oxygen-resistant hydrogenases and methods for designing and making same

    DOEpatents

    King, Paul; Ghirardi, Maria L; Seibert, Michael

    2009-03-10

    The invention provides oxygen- resistant iron-hydrogenases ([Fe]-hydrogenases) for use in the production of H2. Methods used in the design and engineering of the oxygen-resistant [Fe]-hydrogenases are disclosed, as are the methods of transforming and culturing appropriate host cells with the oxygen-resistant [Fe]-hydrogenases. Finally, the invention provides methods for utilizing the transformed, oxygen insensitive, host cells in the bulk production of H.sub.2 in a light catalyzed reaction having water as the reactant.

  5. Mixed-Methods Resistance Training Increases Power and Strength of Young and Older Men.

    ERIC Educational Resources Information Center

    Newton, Robert U.; Hakkinen, Keijo; Hakkinen, Arja; McCormick, Matt; Volek, Jeff; Kraemer, William J.

    2002-01-01

    Examined the effects of a 10-week, mixed-methods resistance training program on young and older men. Although results confirmed some age-related reductions in muscle strength and power, the older men demonstrated similar capacity to the younger men for increases in muscle strength and power via an appropriate, periodized resistance training…

  6. Diagnostic Ultrasound Induced Inertial Cavitation to Non-Invasively Restore Coronary and Microvascular Flow in Acute Myocardial Infarction

    PubMed Central

    Xie, Feng; Gao, Shunji; Wu, Juefei; Lof, John; Radio, Stanley; Vignon, Francois; Shi, William; Powers, Jeffry; Unger, Evan; Everbach, E. Carr; Liu, Jinjin; Porter, Thomas R.

    2013-01-01

    Ultrasound induced cavitation has been explored as a method of dissolving intravascular and microvascular thrombi in acute myocardial infarction. The purpose of this study was to determine the type of cavitation required for success, and whether longer pulse duration therapeutic impulses (sustaining the duration of cavitation) could restore both microvascular and epicardial flow with this technique. Accordingly, in 36 hyperlipidemic atherosclerotic pigs, thrombotic occlusions were induced in the mid-left anterior descending artery. Pigs were then randomized to either a) ½ dose tissue plasminogen activator (0.5 mg/kg) alone; or same dose plasminogen activator and an intravenous microbubble infusion with either b) guided high mechanical index short pulse (2.0 MI; 5 usec) therapeutic ultrasound impulses; or c) guided 1.0 mechanical index long pulse (20 usec) impulses. Passive cavitation detectors indicated the high mechanical index impulses (both long and short pulse duration) induced inertial cavitation within the microvasculature. Epicardial recanalization rates following randomized treatments were highest in pigs treated with the long pulse duration therapeutic impulses (83% versus 59% for short pulse, and 49% for tissue plasminogen activator alone; p<0.05). Even without epicardial recanalization, however, early microvascular recovery occurred with both short and long pulse therapeutic impulses (p<0.005 compared to tissue plasminogen activator alone), and wall thickening improved within the risk area only in pigs treated with ultrasound and microbubbles. We conclude that although short pulse duration guided therapeutic impulses from a diagnostic transducer transiently improve microvascular flow, long pulse duration therapeutic impulses produce sustained epicardial and microvascular re-flow in acute myocardial infarction. PMID:23922797

  7. The association between microvascular and macrovascular endothelial function in patients with rheumatoid arthritis: a cross-sectional study

    PubMed Central

    2011-01-01

    Introduction Patients with rheumatoid arthritis (RA) are at an increased risk for cardiovascular disease (CVD). One of the earliest manifestations of CVD is endothelial dysfunction (ED). ED can occur in both the microcirculation and the macrocirculation, and these manifestations might be relatively independent of each other. Little is known about the association between endothelial function in the microcirculation and the macrocirculation in RA. The objectives of the present study were to examine the relationship between microvascular and macrovascular endothelial function in patients with RA. Methods Ninety-nine RA patients (72 females, mean age (± SD) 56 ± 12 years), underwent assessments of endothelial-dependent (acetylcholine) and endothelial-independent (sodium nitroprusside) microvascular vasodilatory function (laser Doppler imaging with iontophoresis), as well as endothelial-dependent (flow-mediated dilation) and endothelial-independent (glyceryl trinitrate-mediated dilation) macrovascular vasodilatory function. Vasodilatory function was calculated as the percentage increase after each stimulus was applied relative to baseline values. Results Pearson correlations showed that microvascular endothelial-dependent function was not associated with macrovascular endothelial-dependent function (r (90 patients) = 0.10, P = 0.34). Similarly, microvascular endothelial-independent function was not related to macrovascular endothelial-independent function (r (89 patients) = 0.00, P = 0.99). Conclusions Microvascular and macrovascular endothelial function were independent of each other in patients with RA, suggesting differential regulation of endothelial function in these two vascular beds. Assessments of both vascular beds may provide more meaningful clinical information on vascular risk in RA, but this hypothesis needs to be confirmed in long-term prospective studies. PMID:21693023

  8. Does Pre-Treatment with High Dose Atorvastatin Prevent Microvascular Dysfunction after Percutaneous Coronary Intervention in Patients with Acute Coronary Syndrome?

    PubMed Central

    Lee, Bong-Ki; Nam, Chang-Wook; Doh, Joon-Hyung; Chung, Woo-Young; Cho, Byung-Ryul; Fearon, William F.

    2016-01-01

    Background and Objectives There is controversy surrounding whether or not high dose statin administration before percutaneous coronary intervention (PCI) decreases peri-procedural microvascular injury. We performed a prospective randomized study to investigate the mechanisms and effects of pre-treatment high dose atorvastatin on myocardial damage in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) undergoing PCI. Subjects and Methods Seventy seven patients with NSTE-ACS were randomly assigned to either the high dose group (atorvastatin 80 mg loading 12 to 24 h before PCI with a further 40 mg loading 2 h before PCI, n=39) or low dose group (atorvastatin 10 mg administration 12 to 24 h before PCI, n=38). Index of microcirculatory resistance (IMR) was measured after stent implantation. Creatine kinase-myocardial band (CK-MB) and high sensitivity C-reactive protein (CRP) levels were measured before and after PCI. Results The baseline characteristics were not different between the two patient groups. Compared to the low dose group, the high dose group had lower post PCI IMR (14.1±5.0 vs. 19.2±9.3 U, p=0.003). Post PCI CK-MB was also lower in the high dose group (median: 1.40 ng/mL (interquartile range [IQR: 0.75 to 3.45] vs. 4.00 [IQR: 1.70 to 7.37], p=0.002) as was the post-PCI CRP level (0.09 mg/dL [IQR: 0.04 to 0.16] vs. 0.22 [IQR: 0.08 to 0.60], p=0.001). Conclusion Pre-treatment with high dose atorvastatin reduces peri-PCI microvascular dysfunction verified by post-PCI IMR and exerts an immediate anti-inflammatory effect in patients with NSTE-ACS. PMID:27482255

  9. Microvascular destruction identifies murine allografts that cannot be rescued from airway fibrosis

    PubMed Central

    Babu, Ashok N.; Murakawa, Tomohiro; Thurman, Joshua M.; Miller, Edmund J.; Henson, Peter M.; Zamora, Martin R.; Voelkel, Norbert F.; Nicolls, Mark R.

    2007-01-01

    Small airway fibrosis (bronchiolitis obliterans syndrome) is the primary obstacle to long-term survival following lung transplantation. Here, we show the importance of functional microvasculature in the prevention of epithelial loss and fibrosis due to rejection and for the first time, relate allograft microvascular injury and loss of tissue perfusion to immunotherapy-resistant rejection. To explore the role of alloimmune rejection and airway ischemia in the development of fibroproliferation, we used a murine orthotopic tracheal transplant model. We determined that transplants were reperfused by connection of recipient vessels to donor vessels at the surgical anastomosis site. Microcirculation through the newly formed vascular anastomoses appeared partially dependent on VEGFR2 and CXCR2 pathways. In the absence of immunosuppression, the microvasculature in rejecting allografts exhibited vascular complement deposition, diminished endothelial CD31 expression, and absent perfusion prior to the onset of fibroproliferation. Rejecting grafts with extensive endothelial cell injury were refractory to immunotherapy. After early microvascular loss, neovascularization was eventually observed in the membranous trachea, indicating a reestablishment of graft perfusion in established fibrosis. One implication of this study is that bronchial artery revascularization at the time of lung transplantation may decrease the risk of subsequent airway fibrosis. PMID:18060031

  10. Selection of the appropriate method for the assessment of insulin resistance.

    PubMed

    Borai, Anwar; Livingstone, Callum; Kaddam, Ibrahim; Ferns, Gordon

    2011-01-01

    Insulin resistance is one of the major aggravating factors for metabolic syndrome. There are many methods available for estimation of insulin resistance which range from complex techniques down to simple indices. For all methods of assessing insulin resistance it is essential that their validity and reliability is established before using them as investigations. The reference techniques of hyperinsulinaemic euglycaemic clamp and its alternative the frequently sampled intravenous glucose tolerance test are the most reliable methods available for estimating insulin resistance. However, many simple methods, from which indices can be derived, have been assessed and validated e.g. homeostasis model assessment (HOMA), quantitative insulin sensitivity check index (QUICKI). Given the increasing number of simple indices of IR it may be difficult for clinicians and researchers to select the most appropriate index for their studies. This review therefore provides guidelines and advices which must be considered before proceeding with a study.

  11. Abrasion resistant coating and method of making the same

    SciTech Connect

    Sordelet, Daniel J.; Besser, Matthew F.

    2001-06-05

    An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al--Cu--Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

  12. Abrasion Resistant Coating and Method of making the same

    SciTech Connect

    Sordelet, Daniel J.; Besser, Matthew F.

    1999-06-25

    An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al-Cu-Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

  13. Thermal provocation to evaluate microvascular reactivity in human skin

    PubMed Central

    2010-01-01

    With increased interest in predictive medicine, development of a relatively noninvasive technique that can improve prediction of major clinical outcomes has gained considerable attention. Current tests that are the target of critical evaluation, such as flow-mediated vasodilation of the brachial artery and pulse-wave velocity, are specific to the larger conduit vessels. However, evidence is mounting that functional changes in the microcirculation may be an early sign of globalized microvascular dysfunction. Thus development of a test of microvascular reactivity that could be used to evaluate cardiovascular risk or response to treatment is an exciting area of innovation. This mini-review is focused on tests of microvascular reactivity to thermal stimuli in the cutaneous circulation. The skin may prove to be an ideal site for evaluation of microvascular dysfunction due to its ease of access and growing evidence that changes in skin vascular reactivity may precede overt clinical signs of disease. Evaluation of the skin blood flow response to locally applied heat has already demonstrated prognostic utility, and the response to local cooling holds promise in patients in whom cutaneous disorders are present. Whether either of these tests can be used to predict cardiovascular morbidity or mortality in a clinical setting requires further evaluation. PMID:20507974

  14. Xenobiotic Particle Exposure and Microvascular Endpoints: A Call to Arms

    PubMed Central

    Stapleton, Phoebe A.; Minarchick, Valerie C.; McCawley, Michael; Knuckles, Travis L.; Nurkiewicz, Timothy R.

    2011-01-01

    Xenobiotic particles can be considered in two genres: air pollution particulate matter and engineered nanoparticles. Particle exposures can occur in the greater environment, the workplace, and our homes. The majority of research in this field has, justifiably, focused on pulmonary reactions and outcomes. More recent investigations indicate that cardiovascular effects are capable of correlating with established mortality and morbidity epidemiological data following particle exposures. While the preliminary and general cardiovascular toxicology has been defined, the mechanisms behind these effects, specifically within the microcirculation, are largely unexplored. Therefore, the purpose of this review is several fold: first, a historical background on toxicological aspects of particle research is presented. Second, essential definitions, terminology, and techniques that may be unfamiliar to the microvascular scientist will be discussed. Third, the most current concepts and hypotheses driving cardiovascular research in this field will be reviewed. Lastly, potential future directions for the microvascular scientist will be suggested. Collectively speaking, microvascular research in the particle exposure field represents far more than a “niche”. The immediate demand for basic, translational, and clinical studies is high and diverse. Microvascular scientists at all career stages are strongly encouraged to expand their research interests to include investigations associated with particle exposures. PMID:21951337

  15. Detection of drug resistance in Mycobacterium tuberculosis: Methods, principles and applications.

    PubMed

    Gupta, Anamika; Anupurba, Shampa

    2015-01-01

    The growing emergence of multidrug resistant tuberculosis (MDR-TB) strains is obstructing efforts for the control and management of TB. Proper management of MDR-TB relies on early recognition of drug resistance followed by timely treatment initiation. Several diagnostic methods, both phenotypic and molecular, have been developed in last few years for rapid identification of drug resistant (DR)-TB. Revised national tuberculosis control programmes (RNTPs) may find it tough to choose from the puzzling variety of rapid tests. Here, we present an outline of the available methods, discussing their basis, advantages and deficiencies. PMID:25857561

  16. Comparison of several methods for determining the internal resistance of lithium ion cells.

    PubMed

    Schweiger, Hans-Georg; Obeidi, Ossama; Komesker, Oliver; Raschke, André; Schiemann, Michael; Zehner, Christian; Gehnen, Markus; Keller, Michael; Birke, Peter

    2010-01-01

    The internal resistance is the key parameter for determining power, energy efficiency and lost heat of a lithium ion cell. Precise knowledge of this value is vital for designing battery systems for automotive applications. Internal resistance of a cell was determined by current step methods, AC (alternating current) methods, electrochemical impedance spectroscopy and thermal loss methods. The outcomes of these measurements have been compared with each other. If charge or discharge of the cell is limited, current step methods provide the same results as energy loss methods. PMID:22219678

  17. Targeting brain microvascular endothelial cells: a therapeutic approach to neuroprotection against stroke

    PubMed Central

    Yu, Qi-jin; Tao, Hong; Wang, Xin; Li, Ming-chang

    2015-01-01

    Brain microvascular endothelial cells form the interface between nervous tissue and circulating blood, and regulate central nervous system homeostasis. Brain microvascular endothelial cells differ from peripheral endothelial cells with regards expression of specific ion transporters and receptors, and contain fewer fenestrations and pinocytotic vesicles. Brain microvascular endothelial cells also synthesize several factors that influence blood vessel function. This review describes the morphological characteristics and functions of brain microvascular endothelial cells, and summarizes current knowledge regarding changes in brain microvascular endothelial cells during stroke progression and therapies. Future studies should focus on identifying mechanisms underlying such changes and developing possible neuroprotective therapeutic interventions. PMID:26807131

  18. Comparison of Methods for Assessing Resistance to Meloidogyne arenaria in Peanut

    PubMed Central

    Dong, Weibo; Holbrook, C. Corley; Timper, Patricia; Brenneman, Timothy B.; Mullinix, Benjamin G.

    2007-01-01

    Use of resistant cultivars is a desirable approach to manage the peanut root-knot nematode (Meloidogyne arenaria). To incorporate resistance into commercially acceptable cultivars requires reliable, efficient screening methods. To optimize the resistance screening protocol, a series of greenhouse tests were done using seven genotypes with three levels of resistance to M. arenaria. The three resistance levels could be separated based on gall indices as early as two weeks after inoculation (WAI) using 8,000 eggs of M. arenaria per plant, while four or more weeks were needed when 1,000–6,000 eggs/plant were used. High inoculum densities (over 8,000 eggs/plant) were needed to separate the three resistance levels based on eggs per gram of root within eight WAI. A gall index based on percentage of galled roots could separate the three resistance levels at lower inoculum levels and earlier harvest dates than other assessment methods. The use of eggs vs. second-stage juveniles (J2) as inoculum provided similar results; however, it took three to five more days to collect J2 than to collect eggs from roots. Plant age affected gall index and nematode reproduction on peanut, especially on the susceptible genotypes AT201 and D098. The genotypes were separated into their correct resistance classes when inoculated 10 to 30 days after planting, but were not separated correctly when inoculated on day 40. PMID:19259486

  19. A Simple Echocardiographic Method To Estimate Pulmonary Vascular Resistance

    PubMed Central

    Opotowsky, Alexander R.; Clair, Mathieu; Afilalo, Jonathan; Landzberg, Michael J.; Waxman, Aaron B.; Moko, Lilamarie; Maron, Bradley; Vaidya, Anjali; Forfia, Paul R.

    2015-01-01

    Pulmonary hypertension is comprised of heterogeneous diagnoses with distinct hemodynamic pathophysiology. Identifying elevated pulmonary vascular resistance (PVR) is critical for appropriate treatment. We reviewed data for patients seen at referral PH clinics who underwent echocardiography and right heart catheterization within 1 year. We derived equations to estimate PVR based on the ratio of estimated pulmonary artery (PA) systolic pressure (PASPDoppler) to RVOT VTI. We validated these equations in a separate sample and compared them to a published model based on the ratio of transtricuspid flow velocity to RVOT VTI (Model 1, Abbas et al 2003). The derived models were: (Model 2)PVR=1.2×PASPRVOT VTI (Model 3)PVR=PASPRVOT VTI+3if notch present The cohort included 217 patients with mean PA pressure=45.3±11.9mmHg, PVR=7.3±5.0WU and PA wedge pressure=14.8±8.1mmHg; just over 1/3rd had PA wedge pressure >15mmHg (35.5%) and 82.0% had PVR>3WU. Model 1 systematically underestimated PVR, especially with high PVR. The derived models demonstrated no systematic bias. Model 3 correlated best with PVR (r=0.80 vs. 0.73 and 0.77 for Models 1 and 2 respectively). Model 3 had superior discriminatory power for PVR>3WU (AUC=0.946) and PVR>5WU (AUC=0.924), though all models discriminated well. Model 3 estimated PVR>3 was 98.3% sensitive and 61.1% specific for PVR>3WU (PPV=93%; NPV=88%). In conclusion, we present an equation to estimate PVR, using the ratio of PASPDoppler to RVOT VTI and a constant designating presence of RVOT VTI mid-systolic notching, which provides superior agreement with PVR across a wide range of values. PMID:23735649

  20. Methods for Specific Electrode Resistance Measurement during Transcranial Direct Current Stimulation

    PubMed Central

    Khadka, Niranjan; Rahman, Asif; Sarantos, Chris; Truong, Dennis Q.; Bikson, Marom

    2014-01-01

    Background Transcranial Direct Current Stimulation (tDCS) is investigated to treat a wide range of neuropsychiatric disorders, for rehabilitation, and for enhancing cognitive performance. The monitoring of electrode resistance before and during tDCS is considered important for tolerability and safety, where an unusually high resistance is indicative of undesired electrode or poor skin contact conditions. Conventional resistance measurement methods do not isolate individual electrode resistance but rather measures overall voltage. Moreover, for HD-tDCS devices, cross talk across electrodes makes concurrent resistance monitoring unreliable. Objective We propose a novel method for monitoring of the individual electrode resistance during tDCS, using a super-position of direct current with a test-signal (low-intensity and low-frequency sinusoids with electrode– specific frequencies) and a single sentinel electrode (not used for DC). Methods To validate this methodology, we developed lumped-parameter models of two and multi-electrode tDCS. Approaches with and without a sentinel electrode were solved and underlying assumptions identified. Assumptions were tested and parameterized in healthy participants using forearm stimulation combining tDCS (2 mA) and sinusoidal test-signals (38 μA and 76 μA peak to peak at 1 Hz, 10 Hz, and 100 Hz) and an in vitro test (where varied electrode failure modes were created). DC and AC component voltages across the electrodes were compared and participants were asked to rate subjective pain. Results A sentinel electrode is required to isolate electrode resistance in a two-electrode tDCS system. For multi-electrode resistance tracking, cross talk was aggravated with electrode proximity and current/resistance mismatches, but could be corrected using proposed approaches. Average voltage and average pain scores were not significantly different across test current intensities and frequencies (two-way repeated measures ANOVA) indicating the

  1. Determining the base resistance of InP HBTs: An evaluation of methods and structures

    NASA Astrophysics Data System (ADS)

    Nardmann, Tobias; Krause, Julia; Pawlak, Andreas; Schroter, Michael

    2016-09-01

    Many different methods can be found in the literature for determining both the internal and external base series resistance based on single transistor terminal characteristics. Those methods are not equally reliable or applicable for all technologies, device sizes and speeds. In this review, the most common methods are evaluated regarding their suitability for InP heterojunction bipolar transistors (HBTs) based on both measured and simulated data. Using data generated by a sophisticated physics-based compact model allows an evaluation of the extraction method precision by comparing the extracted parameter value to its known value. Based on these simulations, this study provides insight into the limitations of the applied methods, causes for errors and possible error mitigation. In addition to extraction methods based on just transistor terminal characteristics, test structures for separately determining the components of the base resistance from sheet and specific contact resistances are discussed and applied to serve as reference for the experimental evaluation.

  2. A Novel Microvascular Flow Technique: Initial Results in Thyroids.

    PubMed

    Machado, Priscilla; Segal, Sharon; Lyshchik, Andrej; Forsberg, Flemming

    2016-03-01

    To evaluate the flow imaging capabilities of a new prototype ultrasound (US) image processing technique (superb micro-vascular imaging [SMI]; Toshiba Medical Systems, Tokyo, Japan) for depiction of microvascular flow in normal thyroid tissue and thyroid nodules compared with standard color and power Doppler US imaging.Ten healthy volunteers and 22 patients, with a total of 25 thyroid nodules, scheduled for US-guided fine needle aspiration were enrolled in this prospective study. Subjects underwent US examination consisting of grayscale, color and power Doppler imaging (CDI and PDI) followed by color and monochrome SMI and pulsed Doppler. SMI is a novel, microvascular flow imaging mode implemented on the Aplio 500 US system (Toshiba). SMI uses advanced clutter suppression to extract flow signals from large to small vessels and depicts this information at high frame rates as a color overlay image or as a monochrome map of flow. Two radiologists independently scored still images and digital clips for overall flow detection, vessel branching details and noise on a visual-analog scale of 1 (worst) to 10 (best).For the volunteers SMI visualized microvasculature with significantly lower velocity than CDI and PDI (P < 0.012). In all thyroid nodules, SMI demonstrated microvascular flow with significantly higher image scores and provided better depiction of the vessel branching details compared with CDI and PDI (P < 0.0001). Clutter noise was significantly higher in monochrome SMI mode than in the other modes, including color SMI (P < 0.001).The novel SMI mode consistently improved the depiction of thyroid microvascular flow compared with standard CDI and PDI.

  3. A Novel Microvascular Flow Technique: Initial Results in Thyroids.

    PubMed

    Machado, Priscilla; Segal, Sharon; Lyshchik, Andrej; Forsberg, Flemming

    2016-03-01

    To evaluate the flow imaging capabilities of a new prototype ultrasound (US) image processing technique (superb micro-vascular imaging [SMI]; Toshiba Medical Systems, Tokyo, Japan) for depiction of microvascular flow in normal thyroid tissue and thyroid nodules compared with standard color and power Doppler US imaging.Ten healthy volunteers and 22 patients, with a total of 25 thyroid nodules, scheduled for US-guided fine needle aspiration were enrolled in this prospective study. Subjects underwent US examination consisting of grayscale, color and power Doppler imaging (CDI and PDI) followed by color and monochrome SMI and pulsed Doppler. SMI is a novel, microvascular flow imaging mode implemented on the Aplio 500 US system (Toshiba). SMI uses advanced clutter suppression to extract flow signals from large to small vessels and depicts this information at high frame rates as a color overlay image or as a monochrome map of flow. Two radiologists independently scored still images and digital clips for overall flow detection, vessel branching details and noise on a visual-analog scale of 1 (worst) to 10 (best).For the volunteers SMI visualized microvasculature with significantly lower velocity than CDI and PDI (P < 0.012). In all thyroid nodules, SMI demonstrated microvascular flow with significantly higher image scores and provided better depiction of the vessel branching details compared with CDI and PDI (P < 0.0001). Clutter noise was significantly higher in monochrome SMI mode than in the other modes, including color SMI (P < 0.001).The novel SMI mode consistently improved the depiction of thyroid microvascular flow compared with standard CDI and PDI. PMID:25900162

  4. Numerical simulation of red blood cell distributions in three-dimensional microvascular bifurcations.

    PubMed

    Hyakutake, Toru; Nagai, Shinya

    2015-01-01

    We constructed three-dimensional microvascular bifurcation models using a parent vessel of diameter 10μm and investigated the flow behavior of the red blood cells (RBCs) through bifurcations. We considered symmetric and asymmetric model types. Two cases of equal daughter vessel diameter were employed for the asymmetric models, where the first was 10μm, which is the same as the parent vessel and the second was 7.94μm, which satisfies Murray's law. Simulated blood flow was computed using the lattice Boltzmann method in conjunction with the immersed boundary method for incorporating fluid-membrane interactions between the flow field and deformable RBCs. First, we investigated the flow behavior of a single RBC through microvascular bifurcations. In the case of the symmetric bifurcation, the turning point of the fractional plasma flow wherein the RBC flow changed from one daughter vessel to the other was 0.50. This turning point was however different for asymmetric bifurcations. Additionally, we varied the initial offset of RBCs from the centerline of the parent vessel. The simulation results indicated that the RBCs preferentially flow through the branch of a larger flow ratio. Next, we investigated the distribution characteristics of multiple RBCs. Simulations indicated that the results of the symmetric model were similar to those predicted by a previously published empirical model. On the other hand, results of asymmetric models deviated from those of the symmetric and empirical models. These results suggest that the distribution of RBCs varies according to the bifurcation angle and daughter vessel diameter in a microvascular bifurcation of the size considered.

  5. Diet Induced Obesity in Sprague Dawley Rats Causes Microvascular and Neural Dysfunction

    PubMed Central

    Davidson, Eric P.; Coppey, Lawrence J.; Calcutt, Nigel A.; Oltman, Christine L.; Yorek, Mark A.

    2010-01-01

    Background The objective was to determine the effect of diet induced obesity (DIO) on microvascular and neural function. Methods Rats were fed a standard or high fat diet for up to 32 weeks. Measurements were performed of vasodilation in epineurial arterioles by videomicroscopy, endoneurial blood flow by hydrogen clearance, nerve conduction velocity by electrical stimulation, size-frequency distribution of myelinated fibers of the sciatic nerve, intraepidermal nerve fiber density using confocal microscopy and thermal nociception using the Hargreaves method. Results Rats fed a high fat diet for 32 weeks developed sensory neuropathy as indicated by slowing of sensory nerve conduction velocity and thermal hypoalgesia. Motor nerve conduction velocity and endoneurial blood flow were not impaired. Mean axonal diameter of myelinated fibers of the sciatic nerve was unchanged in high fat fed rats compared to control. Intraepidermal nerve fiber density was significantly reduced in high fat fed rats. Vascular relaxation to acetylcholine and calcitonin gene-related peptide was decreased and expression of neutral endopeptidase (NEP) increased in epineurial arterioles of rats fed a high fat diet. In contrast, insulin-mediated vascular relaxation was increased in epineurial arterioles. NEP activity was significantly increased in the skin of the hindpaw. Markers of oxidative stress were increased in the aorta and serum of high fat fed rats but not in epineurial arterioles. Conclusion Chronic obesity causes microvascular and neural dysfunction. This is associated with increased expression of NEP but not oxidative stress in epineurial arterioles. NEP degrades vasoactive peptides which may explain the decrease in microvascular function. PMID:20503263

  6. Monolithic multigrid methods for two-dimensional resistive magnetohydrodynamics

    DOE PAGESBeta

    Adler, James H.; Benson, Thomas R.; Cyr, Eric C.; MacLachlan, Scott P.; Tuminaro, Raymond S.

    2016-01-06

    Magnetohydrodynamic (MHD) representations are used to model a wide range of plasma physics applications and are characterized by a nonlinear system of partial differential equations that strongly couples a charged fluid with the evolution of electromagnetic fields. The resulting linear systems that arise from discretization and linearization of the nonlinear problem are generally difficult to solve. In this paper, we investigate multigrid preconditioners for this system. We consider two well-known multigrid relaxation methods for incompressible fluid dynamics: Braess--Sarazin relaxation and Vanka relaxation. We first extend these to the context of steady-state one-fluid viscoresistive MHD. Then we compare the two relaxationmore » procedures within a multigrid-preconditioned GMRES method employed within Newton's method. To isolate the effects of the different relaxation methods, we use structured grids, inf-sup stable finite elements, and geometric interpolation. Furthermore, we present convergence and timing results for a two-dimensional, steady-state test problem.« less

  7. Simple Molecular Methods for Early Detection of Chloroquine Drug Resistance in Plasmodium vivax and Plasmodium falciparum

    PubMed Central

    Singh, Raksha; Urhehar, Anant Dattatraya

    2016-01-01

    Introduction Malaria is a human disease of which causes high morbidity and mortality. In Plasmodium falciparum malaria, the resistance to antimalarial drugs, especially chloroquine (CQ) is one of the paramount factors contributing to the global increase in morbidity and mortality, due to malaria. Hence, there is a need for detection of chloroquine drug resistance genes i.e., pfcrt-o (Plasmodium falciparum chloroquine resistance transporter-o) and pfmdr-1 (Plasmodium falciparum multidrug resistance-1) of P. falciparum and pvcrt-o (Plasmodium vivax chloroquine resistance transporter-o) and pvmdr-1 (Plasmodium vivax multidrug resistance-1) of P. vivax by using molecular methods to prevent mortality in malarial cases. Aim To standardize chloroquine drug sensitivity testing by molecular method so as to provide reports of chloroquine within 6-8 hours to physicians for better treatment. Materials and Methods This study was conducted over a period of one year from January to December 2014. A Total of 300 blood samples were collected from malaria suspected patient attending MGM Hospital, Kamothe, Navi Mumbai, India. Out of 300 blood samples, 44 were malaria positive as assessed by Thick and Thin blood smear stained, by Leishman’s method and examination with light microscope. Chloroquine drug sensitivity testing was performed using WHO III plate method (micro test). Nested PCR was done for detection of pfcrt-o and pfmdr-1 for P. falciparum and pvcrt-o, pvmdr-1 genes for P. vivax. Results Total 44 samples were included in this study, out of which 22 samples confirmed for Plasmodium falciparum and 22 samples confirmed for Plasmodium vivax. Out of 22 P. falciparum 15 (68.18%) samples were chloroquine resistant. P. vivax showed chloroquine resistance to 5 samples (22.73%) by method similar to WHO III plate method (micro test) and nested PCR. Conclusion Drug resistance testing by molecular methods is useful for early detection of antimalarial drug resistance. pfmdr-1 along with

  8. Simple Molecular Methods for Early Detection of Chloroquine Drug Resistance in Plasmodium vivax and Plasmodium falciparum

    PubMed Central

    Singh, Raksha; Urhehar, Anant Dattatraya

    2016-01-01

    Introduction Malaria is a human disease of which causes high morbidity and mortality. In Plasmodium falciparum malaria, the resistance to antimalarial drugs, especially chloroquine (CQ) is one of the paramount factors contributing to the global increase in morbidity and mortality, due to malaria. Hence, there is a need for detection of chloroquine drug resistance genes i.e., pfcrt-o (Plasmodium falciparum chloroquine resistance transporter-o) and pfmdr-1 (Plasmodium falciparum multidrug resistance-1) of P. falciparum and pvcrt-o (Plasmodium vivax chloroquine resistance transporter-o) and pvmdr-1 (Plasmodium vivax multidrug resistance-1) of P. vivax by using molecular methods to prevent mortality in malarial cases. Aim To standardize chloroquine drug sensitivity testing by molecular method so as to provide reports of chloroquine within 6-8 hours to physicians for better treatment. Materials and Methods This study was conducted over a period of one year from January to December 2014. A Total of 300 blood samples were collected from malaria suspected patient attending MGM Hospital, Kamothe, Navi Mumbai, India. Out of 300 blood samples, 44 were malaria positive as assessed by Thick and Thin blood smear stained, by Leishman’s method and examination with light microscope. Chloroquine drug sensitivity testing was performed using WHO III plate method (micro test). Nested PCR was done for detection of pfcrt-o and pfmdr-1 for P. falciparum and pvcrt-o, pvmdr-1 genes for P. vivax. Results Total 44 samples were included in this study, out of which 22 samples confirmed for Plasmodium falciparum and 22 samples confirmed for Plasmodium vivax. Out of 22 P. falciparum 15 (68.18%) samples were chloroquine resistant. P. vivax showed chloroquine resistance to 5 samples (22.73%) by method similar to WHO III plate method (micro test) and nested PCR. Conclusion Drug resistance testing by molecular methods is useful for early detection of antimalarial drug resistance. pfmdr-1 along with

  9. Energy requirements for methods improving gas detection by modulating physical properties of resistive gas sensors

    NASA Astrophysics Data System (ADS)

    Trawka, M.; Kotarski, M.

    2016-01-01

    One of the most important disadvantage of resistive gas sensors is their limited gas selectivity. Therefore, various methods modulating their physical properties are used to improve gas detection. These methods are usually limited to temperature modulation or UV light irradiation for the layers exhibiting photocatalytic effect. These methods cause increased energy consumption. In our study we consider how much energy has to be supplied to utilize such methods and what kind of additional information can be gathered. We present experimental results of selected resistive gas sensors, including commercial and prototype constructions, and practical solutions of modulating their physical properties.

  10. Explosion resistant insulator and method of making same

    DOEpatents

    Meyer, Jeffry R.; Billings, Jr., John S.; Spindle, Harvey E.; Hofmann, Charles F.

    1983-01-01

    An electrical insulator assembly and method of manufacturing same, having a generally cylindrical or conical body portion formed of a breakable cast solid insulation system and a reinforcing member having a corrugated configuration and formed of a web or mesh type reinforcing fabric. When the breakable body member has been broken, the corrugated configured reinforcing web member provides a path of escape for pressurized insulating fluid while limiting the movement of body member fragments in the direction of escape of the pressurized fluid.

  11. A new method for measuring the Faradic resistance of a single electrode-electrolyte interface.

    PubMed

    Mayer, S; Geddes, L A; Bourland, J D; Ogborn, L

    1992-03-01

    A new method is described for measuring the Faradic resistance of a single electrode-electrolyte interface. The method employs a test (monopolar) electrode, a potential-sensing electrode and a large reference (indifferent) electrode, along with a constant-current source capable of providing a step function of current. The method was used to measure the Faradic resistance of a 0.1 cm2 platinum electrode in contact with saline (p = 150 ohm-cm) at room temperature. It was found that for both a positive and negative current pulse, the Faradic resistance decreased almost hyperbolically with increasing current density. When the reciprocal of the Faradic resistance (Gf) was plotted versus current density and the data were fit to a polynomial curve, the results showed that for the positive pulse Gf = 0.009 + 0.05J - 0.0001J2; (SEE = 0.117); for the negative pulse, Gf = 0.007 + 0.067J - 0.0001J2; (SEE = 0.028); where Gf is in millisiemens and J is in mA/cm2 for this 0.1 cm2 electrode. These relationships permit estimating the Faradic resistance (Rf) for zero current density. For the positive pulse, Rf = 111 kilohms and for the negative pulse Rf = 143 kilohms. The method is applicable to the measurement of the Faradic resistance of a wide variety of metal electrodes.

  12. Method for contact resistivity measurements on photovoltaic cells and cell adapted for such measurement

    NASA Technical Reports Server (NTRS)

    Burger, Dale R. (Inventor)

    1986-01-01

    A method is disclosed for scribing at least three grid contacts of a photovoltaic cell to electrically isolate them from the grid contact pattern used to collect solar current generated by the cell, and using the scribed segments for determining parameters of the cell by a combination of contact end resistance (CER) measurements using a minimum of three equally or unequally spaced lines, and transmission line modal (TLM) measurements using a minimum of four unequally spaced lines. TLM measurements may be used to determine sheet resistance under the contact, R.sub.sk, while CER measurements are used to determine contact resistivity, .rho..sub.c, from a nomograph of contact resistivity as a function of contact end resistance and sheet resistivity under the contact. In some cases, such as the case of silicon photovoltaic cells, sheet resistivity under the contact may be assumed to be equal to the known sheet resistance, R.sub.s, of the semiconductor material, thereby obviating the need for TLM measurements to determine R.sub.sk.

  13. Helicobacter pylori resistance to antibiotics in 2014 in France detected by phenotypic and genotypic methods.

    PubMed

    Ducournau, A; Bénéjat, L; Sifré, E; Bessède, E; Lehours, P; Mégraud, F

    2016-08-01

    A large survey of antimicrobial resistance of Helicobacter pylori was performed in France in 2014: 984 patients were enrolled by 75 gastroenterologists all over the country. Among the 783 patients who had never received eradication treatment before, 266 (33.9%) were H. pylori positive. The strains showed a high rate of clarithromycin resistance (22.2%), moderate rate of resistance to levofloxacin (15.4%) and high rate of resistance to metronidazole (45.9%). In all, 187 patients had received previous treatment, of which 115 were H. pylori positive with very high resistance to clarithromycin (73.9%) and metronidazole (78.3%). None of the patients receiving PYLERA (Bismuth salt-Tetracycline HCl-Metronidazole) proton-pump inhibitor developed resistance to tetracycline. A real-time PCR applied to gastric biopsy specimens detected all the cases that were positive by culture as well as 30 additional cases. A good correlation was found between the clarithromycin resistance detected by phenotypic methods and the associated mutations for clarithromycin resistance, which has continued to increase in the last decade but at a lower rate than previously observed. PMID:27345177

  14. Computer-based analysis of microvascular alterations in a mouse model for Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Heinzer, Stefan; Müller, Ralph; Stampanoni, Marco; Abela, Rafael; Meyer, Eric P.; Ulmann-Schuler, Alexandra; Krucker, Thomas

    2007-03-01

    Vascular factors associated with Alzheimer's disease (AD) have recently gained increased attention. To investigate changes in vascular, particularly microvascular architecture, we developed a hierarchical imaging framework to obtain large-volume, high-resolution 3D images from brains of transgenic mice modeling AD. In this paper, we present imaging and data analysis methods which allow compiling unique characteristics from several hundred gigabytes of image data. Image acquisition is based on desktop micro-computed tomography (µCT) and local synchrotron-radiation µCT (SRµCT) scanning with a nominal voxel size of 16 µm and 1.4 µm, respectively. Two visualization approaches were implemented: stacks of Z-buffer projections for fast data browsing, and progressive-mesh based surface rendering for detailed 3D visualization of the large datasets. In a first step, image data was assessed visually via a Java client connected to a central database. Identified characteristics of interest were subsequently quantified using global morphometry software. To obtain even deeper insight into microvascular alterations, tree analysis software was developed providing local morphometric parameters such as number of vessel segments or vessel tortuosity. In the context of ever increasing image resolution and large datasets, computer-aided analysis has proven both powerful and indispensable. The hierarchical approach maintains the context of local phenomena, while proper visualization and morphometry provide the basis for detailed analysis of the pathology related to structure. Beyond analysis of microvascular changes in AD this framework will have significant impact considering that vascular changes are involved in other neurodegenerative diseases as well as in cancer, cardiovascular disease, asthma, and arthritis.

  15. AST-120 Improves Microvascular Endothelial Dysfunction in End-Stage Renal Disease Patients Receiving Hemodialysis

    PubMed Central

    Ryu, Jung-Hwa; Yu, Mina; Lee, Sihna; Ryu, Dong-Ryeol; Kim, Seung-Jung; Kang, Duk-Hee

    2016-01-01

    Purpose Endothelial dysfunction (ED) is a pivotal phenomenon in the development of cardiovascular disease (CVD) in patients receiving hemodialysis (HD). Indoxyl sulfate (IS) is a known uremic toxin that induces ED in patients with chronic kidney disease. The aim of this study was to investigate whether AST-120, an absorbent of IS, improves microvascular or macrovascular ED in HD patients. Materials and Methods We conducted a prospective, case-controlled trial. Fourteen patients each were enrolled in respective AST-120 and control groups. The subjects in the AST-120 group were treated with AST-120 (6 g/day) for 6 months. Microvascular function was assessed by laser Doppler flowmetry using iontophoresis of acetylcholine (Ach) and sodium nitroprusside (SNP) at baseline and again at 3 and 6 months. Carotid arterial intima-media thickness (cIMT) and flow-mediated vasodilation were measured at baseline and 6 months. The Wilcoxon rank test was used to compare values before and after AST-120 treatment. Results Ach-induced iontophoresis (endothelium-dependent response) was dramatically ameliorated at 3 months and 6 months in the AST-120 group. SNP-induced response showed delayed improvement only at 6 months in the AST-120 group. The IS level was decreased at 3 months in the AST-120 group, but remained stable thereafter. cIMT was significantly reduced after AST-120 treatment. No significant complications in patients taking AST-120 were reported. Conclusion AST-120 ameliorated microvascular ED and cIMT in HD patients. A randomized study including a larger population will be required to establish a definitive role of AST-120 as a preventive medication for CVD in HD patients. PMID:27189289

  16. Effect of Irradiation on Microvascular Endothelial Cells of Parotid Glands in the Miniature Pig

    SciTech Connect

    Xu Junji; Yan Xing; Gao Runtao; Mao Lisha; Cotrim, Ana P.; Zheng Changyu; Zhang Chunmei; Baum, Bruce J.; Wang Songlin

    2010-11-01

    Purpose: To evaluate the effect of irradiation on microvascular endothelial cells in miniature pig parotid glands. Methods and Materials: A single 25-Gy dose of irradiation (IR) was delivered to parotid glands of 6 miniature pigs. Three other animals served as non-IR controls. Local blood flow rate in glands was measured pre- and post-IR with an ultrasonic Doppler analyzer. Samples of parotid gland tissue were taken at 4 h, 24 h, 1 week, and 2 weeks after IR for microvascular density (MVD) analysis and sphingomyelinase (SMase) assay. Histopathology and immunohistochemical staining (anti-CD31 and anti-AQP1) were used to assess morphological changes. MVD was determined by calculating the number of CD31- or AQP1-stained cells per field. A terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay was used to detect apoptotic cells. The activity of acid and neutral Mg{sup 2+}-dependent SMase (ASMase and NSMase, respectively) was also assayed. Results: Local parotid gland blood flow rate decreased rapidly at 4 h post-IR and remained below control levels throughout the 14-day observation period. Parotid MVD also declined from 4 to 24 hours and remained below control levels thereafter. The activity levels of ASMase and NSMase in parotid glands increased rapidly from 4 to 24 h post-IR and then declined gradually. The frequency of detecting apoptotic nuclei in the glands followed similar kinetics. Conclusions: Single-dose IR led to a significant reduction of MVD and local blood flow rate, indicating marked damage to microvascular endothelial cells in miniature pig parotid glands. The significant and rapid increases of ASMase and NSMase activity levels may be important in this IR-induced damage.

  17. Zingiber officinale attenuates retinal microvascular changes in diabetic rats via anti-inflammatory and antiangiogenic mechanisms

    PubMed Central

    Dongare, Shirish; Mathur, Rajani; Saxena, Rohit; Mathur, Sandeep; Agarwal, Renu; Nag, Tapas C.; Srivastava, Sushma; Kumar, Pankaj

    2016-01-01

    Purpose Diabetic retinopathy is a common microvascular complication of long-standing diabetes. Several complex interconnecting biochemical pathways are activated in response to hyperglycemia. These pathways culminate into proinflammatory and angiogenic effects that bring about structural and functional damage to the retinal vasculature. Since Zingiber officinale (ginger) is known for its anti-inflammatory and antiangiogenic properties, we investigated the effects of its extract standardized to 5% 6-gingerol, the major active constituent of ginger, in attenuating retinal microvascular changes in rats with streptozotocin-induced diabetes. Methods Diabetic rats were treated orally with the vehicle or the ginger extract (75 mg/kg/day) over a period of 24 weeks along with regular monitoring of bodyweight and blood glucose and weekly fundus photography. At the end of the 24-week treatment, the retinas were isolated for histopathological examination under a light microscope, transmission electron microscopy, and determination of the retinal tumor necrosis factor-α (TNF-α), nuclear factor-kappa B (NF-κB), and vascular endothelial growth factor (VEGF) levels. Results Oral administration of the ginger extract resulted in significant reduction of hyperglycemia, the diameter of the retinal vessels, and vascular basement membrane thickness. Improvement in the architecture of the retinal vasculature was associated with significantly reduced expression of NF-κB and reduced activity of TNF-α and VEGF in the retinal tissue in the ginger extract–treated group compared to the vehicle-treated group. Conclusions The current study showed that ginger extract containing 5% of 6-gingerol attenuates the retinal microvascular changes in rats with streptozotocin-induced diabetes through anti-inflammatory and antiangiogenic actions. Although precise molecular targets remain to be determined, 6-gingerol seems to be a potential candidate for further investigation. PMID:27293376

  18. Glaucocalyxin A Ameliorates Myocardial Ischemia-Reperfusion Injury in Mice by Suppression of Microvascular Thrombosis

    PubMed Central

    Liu, Xiaohui; Xu, Dongzhou; Wang, Yuxin; Chen, Ting; Wang, Qi; Zhang, Jian; You, Tao; Zhu, Li

    2016-01-01

    Background The aim of this study was to evaluate the cardio-protective roles of glaucocalyxin A (GLA) in myocardial ischemia-reperfusion injury and to explore the underlying mechanism. Material/Methods Myocardial ischemia-reperfusion in wild-type C57BL/6J mice was induced by transient ligation of the left anterior descending artery. GLA or vehicle (solvent) was administrated intraperitoneally to the mice before reperfusion started. After 24 h of myocardial reperfusion, ischemic size was revealed by Evans blue/TTC staining. Cardiac function was evaluated by echocardiography and microvascular thrombosis was assessed by immunofluorescence staining of affected heart tissue. We also measured the phosphorylation of AKT, ERK, P-GSK-3β, and cleaved caspase 3 in the myocardium. Results Compared to the solvent-treated control group, GLA administration significantly reduced infarct size (GLA 13.85±2.08% vs. Control 18.95±0.97%, p<0.05) and improved left ventricular ejection fraction (LVEF) (GLA 53.13±1.11% vs. Control 49.99±1.25%, p<0.05) and left ventricular fractional shortening (LVFS) (28.34±0.71% vs. Control 25.11±0.74%, p<0.05) in mice subjected to myocardial ischemia-reperfusion. GLA also attenuated microvascular thrombosis (P<0.05) and increased the phosphorylation of pro-survival kinase AKT (P<0.05) and GSK-3β (P<0.05) in the myocardium upon reperfusion injury. Conclusions Administration of GLA before reperfusion ameliorates myocardial ischemia-reperfusion injury in mice. The cardio-protective roles of GLA may be mediated through the attenuation of microvascular thrombosis. PMID:27716735

  19. Propionyl-L-Carnitine Enhances Wound Healing and Counteracts Microvascular Endothelial Cell Dysfunction

    PubMed Central

    Scioli, Maria Giovanna; Lo Giudice, Pietro; Bielli, Alessandra; Tarallo, Valeria; De Rosa, Alfonso; De Falco, Sandro; Orlandi, Augusto

    2015-01-01

    Background Impaired wound healing represents a high cost for health care systems. Endothelial dysfunction characterizes dermal microangiopathy and contributes to delayed wound healing and chronic ulcers. Endothelial dysfunction impairs cutaneous microvascular blood flow by inducing an imbalance between vasorelaxation and vasoconstriction as a consequence of reduced nitric oxide (NO) production and the increase of oxidative stress and inflammation. Propionyl-L-carnitine (PLC) is a natural derivative of carnitine that has been reported to ameliorate post-ischemic blood flow recovery. Methods and Results We investigated the effects of PLC in rat skin flap and cutaneous wound healing. A daily oral PLC treatment improved skin flap viability and associated with reactive oxygen species (ROS) reduction, inducible nitric oxide synthase (iNOS) and NO up-regulation, accelerated wound healing and increased capillary density, likely favoring dermal angiogenesis by up-regulation for iNOS, vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and reduction of NADPH-oxidase 4 (Nox4) expression. In serum-deprived human dermal microvascular endothelial cell cultures, PLC ameliorated endothelial dysfunction by increasing iNOS, PlGF, VEGF receptors 1 and 2 expression and NO level. In addition, PLC counteracted serum deprivation-induced impairment of mitochondrial β-oxidation, Nox4 and cellular adhesion molecule (CAM) expression, ROS generation and leukocyte adhesion. Moreover, dermal microvascular endothelial cell dysfunction was prevented by Nox4 inhibition. Interestingly, inhibition of β-oxidation counteracted the beneficial effects of PLC on oxidative stress and endothelial dysfunction. Conclusion PLC treatment improved rat skin flap viability, accelerated wound healing and dermal angiogenesis. The beneficial effects of PLC likely derived from improvement of mitochondrial β-oxidation and reduction of Nox4-mediated oxidative stress and endothelial dysfunction

  20. Printing Cancer Cells into Intact Microvascular Networks: A Model for Investigating Cancer Cell Dynamics during Angiogenesis

    PubMed Central

    Phamduy, Theresa B.; Sweat, Richard S.; Azimi, Mohammad S.; Burow, Matthew E.; Murfee, Walter L.; Chrisey, Douglas B.

    2016-01-01

    While cancer cell invasion and metastasis is dependent on cancer cell-stroma, cancer cell-blood vessel, and cancer cell-lymphatic vessel interactions, our understanding of these interactions remain largely unknown. A need exists for physiologically-relevant models that more closely mimic the complexity of cancer cell dynamics in a real tissue environment. The objective of this study was to combine laser-based cell printing and tissue culture methods to create a novel ex vivo model in which cancer cell dynamics can be tracked during angiogenesis in an intact microvascular network. Laser direct-write (LDW) was utilized to reproducibly deposit breast cancer cells (MDA-MB-231 and MCF-7) and fibroblasts into spatially-defined patterns on cultured rat mesenteric tissues. In addition, heterogeneous patterns containing co-printed MDA-MB-231/fibroblasts or MDA-MB-231/MCF-7 cells were generated for fibroblast-directed and collective cell invasion models. Printed cells remained viable and the cells retained the ability to proliferate in serum-rich media conditions. Over a culture period of five days, time-lapse imaging confirmed fibroblast and MDA-MB-231 cell migration within the microvascular networks. Confocal microscopy indicated that printed MDA-MB-231 cells infiltrated the tissue thickness and were capable of interacting with endothelial cells. Angiogenic network growth in tissue areas containing printed cancer cells was characterized by significantly increased capillary sprouting compared to control tissue areas containing no printed cells. Our results establish an innovative ex vivo experimental platform that enables time-lapse evaluation of cancer cell dynamics during angiogenesis within a real microvascular network scenario. PMID:26190039

  1. Neuropathological analysis of lacunes and microvascular lesions in late-onset depression

    PubMed Central

    Santos, Micaela; Gold, Gabriel; Kövari, Enikö; Herrmann, François R.; Hof, Patrick R.; Bouras, Constantin; Giannakopoulos, Panteleimon

    2010-01-01

    Aims Previous neuropathological studies documented that small vascular and microvascular pathology is associated with cognitive decline. More recently, we showed that thalamic and basal ganglia lacunes are associated with post-stroke depression and may affect emotional regulation. The present study examines whether this is also the case for late-onset depression. Methods We performed a detailed analysis of small macrovascular and microvascular pathology in the postmortem brains of 38 patients with late-onset major depression (LOD) and 29 healthy elderly controls. A clinical diagnosis of LOD was established while the subjects were alive using the DSM-IV criteria. Additionally, we retrospectively reviewed all charts for the presence of clinical criteria of vascular depression. Neuropathological evaluation included bilateral semiquantitative assessment of lacunes, deep white matter and periventricular demyelination, cortical microinfarcts and both focal and diffuse gliosis. The association between vascular burden and LOD was investigated using Fisher’s exact test and univariate and multivariate logistic regression models. Results Neither the existence of lacunes nor the presence of microvascular ischaemic lesions was related to occurrence of LOD. Similarly, there was no relationship between vascular lesion scores and LOD. This was also the case within the subgroup of LOD patients fulfilling the clinical criteria for vascular depression. Conclusions Our results challenge the vascular depression hypothesis by showing that neither deep white matter nor periventricular demyelination is associated with LOD. In conjunction with our previous observations in stroke patients, they also imply that the impact of lacunes on mood may be significant solely in the presence of acute brain compromise. PMID:20609111

  2. Retinal Microvascular Abnormalities and Risk of Renal Failure in Asian Populations

    PubMed Central

    Yip, WanFen; Sabanayagam, Charumathi; Teo, Boon Wee; Tay, Wan Ting; Ikram, M. Kamran; Tai, E. Shyong; Chow, Khuan Yew; Wong, Tien Y.; Cheung, Carol Y.

    2015-01-01

    Background Retinal microvascular signs may provide insights into the structure and function of small vessels that are associated with renal disease. We examined the relationship of retinal microvascular signs with both prevalent and incident end-stage renal disease (ESRD) in a multi-ethnic Asian population. Methods A total of 5763 subjects (aged ≥40 years) from two prospective population-based studies (the Singapore Malay Eye Study and the Singapore Prospective Study) were included for the current analysis. Retinopathy was graded using the modified Airlie House classification system. Retinal vascular parameters were measured using computer-assisted programs to quantify the retinal vessel widths (arteriolar and venular caliber) and retinal vascular network (fractal dimension). Data on ESRD was obtained by record linkage with the ESRD cases registered by National Registry of Diseases Office, Singapore. Multi-variable adjusted regression analyses were performed to assess the associations of baseline retinal vascular parameters and prevalent and incident ESRD. Results At baseline, 21(0.36%) persons had prevalent ESRD. During a median follow-up of 4.3 years, 33 (0.57%) subjects developed ESRD. In our analyses, retinopathy was associated with prevalent ESRD (multi-variable adjusted odds ratio [OR], 3.21, 95% confidence interval [CI]: 1.28–8.05) and incident ESRD (multi-variable adjusted hazard ratio [HR], 2.51, 95%CI: 1.14–5.54). This association was largely seen in person with diabetes (HR, 2.60, 95%CI: 1.01–6.66) and not present in persons without diabetes (HR, 1.65, 95%CI: 0.14–18.98). Retinal arteriolar caliber, retinal venular caliber and retinal vascular fractal dimension were not associated with ESRD. Conclusion Retinopathy signs in persons with diabetes are related to an increased risk of ESRD; however, other microvascular changes in the retina are not associated with ESRD. PMID:25658337

  3. ROLE OF ATP IN REGULATING RENAL MICROVASCULAR FUNCTION AND IN HYPERTENSION

    PubMed Central

    Guan, Zhengrong; Inscho, Edward W.

    2011-01-01

    Adenosine triphosphate (ATP) is an essential energy substrate for cellular metabolism but it can also influence many biological processes when released into the extracellular milieu. Research has established that extracellular ATP acts as an autocrine/paracrine factor that regulates many physiological functions. Alternatively, excessive extracellular ATP levels contribute to pathophysiological processes such as inflammation, cell proliferation and apoptosis, and atherosclerosis. Renal P2 receptors are widely distributed throughout glomeruli, vasculature and tubular segments, and participate in controlling renal vascular resistance, mediating renal autoregulation, and regulating tubular transport function. This review will focus on the role of ATP-P2 receptor signaling in regulating renal microvascular function and autoregulation, recent advances on the role of ATP-P2 signaling in hypertension-associated renal vascular injury, and emerging new directions. PMID:21768526

  4. Hydrofluoric acid-resistant composite window and method for its fabrication

    DOEpatents

    Ostenak, C.A.; Mackay, H.A.

    1985-07-18

    A hydrofluoric acid-resistant composite window and method for its fabrication are disclosed. The composite window comprises a window having first and second sides. The first side is oriented towards an environment containing hydrofluoric acid. An adhesive is applied to the first side. A layer of transparent hydrofluoric acid-resistant material, such as Mylar, is applied to the adhesive and completely covers the first side. The adhesive is then cured.

  5. Hydrofluoric acid-resistant composite window and method for its fabrication

    DOEpatents

    Ostenak, Carl A.; Mackay, Harold A.

    1987-01-01

    A hydrofluoric acid-resistant composite window and method for its fabrication are disclosed. The composite window comprises a window having first and second sides. The first side is oriented towards an environment containing hydrofluoric acid. An adhesive is applied to the first side. A layer of transparent hydrofluoric acid-resistant material, such as Mylar, is applied to the adhesive and completely covers the first side. The adhesive is then cured.

  6. Effect of the processing method on the treeing resistance of polymeric dielectrics

    NASA Astrophysics Data System (ADS)

    Gefle, O. S.; Lebedev, S. M.

    2012-10-01

    Results of investigation into the effect of the processing method on the treeing resistance of polystyrene, polymethylmethacrilate, and polycarbonate are presented. It is demonstrated that in the presence of residual internal strain arising at the stage of processing, the highest treeing resistance possess polymers with a higher tensile yield strength. The tree propagation rate can be decreased and the time to breakdown of polymeric dielectrics can be increased by decreasing the thermal diffusivity of the base polymers.

  7. Regional cutaneous microvascular flow responses during gravitational and LBNP stresses.

    PubMed

    Breit, G A; Watenpaugh, D E; Ballard, R E; Murthy, G; Hargens, A R

    1993-01-01

    The most significant cardiovascular event during the transition to microgravity is the redistribution of vascular transmural pressures that results from the loss of hydrostatic gradients along the length of the body. The well-documented effects of this redistribution include facial venous engorgement, headache, and a significant decrease in leg volume. These effects predominantly represent bulk fluid volume shifts, especially in the venous macro- and microcirculation, where volume is a direct function of pressure, related by the mechanical compliance of the vascular compartment. When considering the effect of gravitational pressure alterations on microcirculatory blood flow and volume, however, this direct monotonic relationship no longer applies. Regional microvascular perfusion is largely a function of local arteriolar tone, which is subject to a variety of central and local controls. Lower body venous pooling during application of footward gravitational stress unloads arterial and cardiopulmonary baroreceptors, increasing sympathetic arteriolar tone to elicit vasoconstriction and a general decrease in microvascular perfusion. The same stimulus also triggers an increase in the levels of circulating vasoactive hormones, such as norepinephrine and angiotensin II, further augmenting arteriolar tone. Vasomotor tone is also mediated by local mechanisms such as myogenic autoregulation and veno-arteriolar reflexes, which enhance microvascular tone in response to elevated local arteriolar and venular pressure, respectively. Due to the regional variability of local hydrostatic pressures, microvascular flow responses to gravitational stress probably vary along the length of the body. Although these differences in local autoregulation have been observed previously during whole-body tilting, they have not been investigated during application of artificial gravitational stresses, such as lower body negative pressure (LBNP) or +Gz centrifugation. Although these stresses can

  8. An Alternative Field Method for Screening Soybean Genotypes for Resistance to Heterodera glycines

    PubMed Central

    Arantes, N. E.; Mauro, A. O.; Tihohood, D.

    1998-01-01

    The soybean cyst nematode (Heterodera glycines) has become an increasingly severe problem in soybean production areas in Brazil. The development and use of resistant cultivars is the most efficient method of minimizing losses due to this pathogen. Our objective was to test the efficiency of an alternative method for screening soybean genotypes for resistance to H. glycines in field plots. The alternative method was compared to the standard method of sowing the test genotypes in fields found to be infested during the previous crop season. In the alternative method, the test genotypes are sown in the furrow following the uprooting of 45-day-old infected plants. The alternative method resulted in twice the cyst population and fewer escapes, and more consistent results than the standard method. The major advantage of the alternative method is that it permits screening in a more homogeneous distribution of H. glycines in the soil. PMID:19274244

  9. A simple and accurate resist parameter extraction method for sub-80-nm DRAM patterns

    NASA Astrophysics Data System (ADS)

    Lee, Sook; Hwang, Chan; Park, Dong-Woon; Kim, In-Sung; Kim, Ho-Chul; Woo, Sang-Gyun; Cho, Han-Ku; Moon, Joo-Tae

    2004-05-01

    Due to the polarization effect of high NA lithography, the consideration of resist effect in lithography simulation becomes increasingly important. In spite of the importance of resist simulation, many process engineers are reluctant to consider resist effect in lithography simulation due to time-consuming procedure to extract required resist parameters and the uncertainty of measurement of some parameters. Weiss suggested simplified development model, and this model does not require the complex kinetic parameters. For the device fabrication engineers, there is a simple and accurate parameter extraction and optimizing method using Weiss model. This method needs refractive index, Dill"s parameters and development rate monitoring (DRM) data in parameter extraction. The parameters extracted using referred sequence is not accurate, so that we have to optimize the parameters to fit the critical dimension scanning electron microscopy (CD SEM) data of line and space patterns. Hence, the FiRM of Sigma-C is utilized as a resist parameter-optimizing program. According to our study, the illumination shape, the aberration and the pupil mesh point have a large effect on the accuracy of resist parameter in optimization. To obtain the optimum parameters, we need to find the saturated mesh points in terms of normalized intensity log slope (NILS) prior to an optimization. The simulation results using the optimized parameters by this method shows good agreement with experiments for iso-dense bias, Focus-Exposure Matrix data and sub 80nm device pattern simulation.

  10. Multilayer sulfur-resistant composite metal membranes and methods of making and repairing the same

    DOEpatents

    Way, J. Douglas; Hatlevik, Oyvind

    2014-07-15

    The invention relates to thin, hydrogen-permeable, sulfur-resistant membranes formed from multi-layers of palladium or palladium-alloy coatings on porous, ceramic or metal supports, methods of making these membranes, methods of repairing layers of these membranes and devices that incorporate these membranes.

  11. Association of low educational status with microvascular complications in type 2 diabetes: Jaipur diabetes registry-1

    PubMed Central

    Sharma, Niharikaa; Sharma, Surendra Kumar; Maheshwari, Vitthal D.; Sharma, Krishna Kumar; Gupta, Rajeev

    2015-01-01

    Objective: To determine the association of educational status (ES), as a marker of socioeconomic status, with the prevalence of microvascular complications in diabetes. Methods: Successive patients (n = 1214) presenting to our centre were evaluated for sociodemographic, anthropometric, clinical, and therapeutic variables. Subjects were classified according to ES into Group 1 (illiterate, 216); Group 2 (microvascular disease (peripheral, ocular or renal) in 20.7%. Microvascular disease was significantly greater in illiterate (25.9%) and low (23.6%) compared to middle (15.0%) and high (14.7%) ES groups (P < 0.05). Age- and sex-adjusted logistic regression analysis revealed that in illiterate and low ES groups respectively, prevalence of smoking/tobacco use (odds ratio 3.84, confidence intervals 2.09–7.05 and 2.15, 1.36–3.41); low fruit/vegetable (2.51, 1.53–4.14 and 1.99, 1.30–3.04) and low fibre intake (4.02, 2.50–6.45 and 1.78, 1.23–2.59) was greater compared to high ES. Poor diabetes control (HbA1c >8.0%) was significantly greater in illiterate (38.0%), low (46.0%) and middle (41.0%) compared to high (31.5%) ES subjects (P < 0.05). Conclusions: There is a greater prevalence of the microvascular disease in illiterate and low ES diabetes patients in India. This is associated with the higher prevalence of smoking/tobacco use, poor quality diet and sub-optimal diabetes control. PMID:26425480

  12. Association of low educational status with microvascular complications in type 2 diabetes: Jaipur diabetes registry

    PubMed Central

    Sharma, Niharikaa; Sharma, Surendra Kumar; Maheshwari, Vitthal D.; Sharma, Krishna Kumar; Gupta, Rajeev

    2015-01-01

    Objective: To determine the association of educational status (ES), as marker of socioeconomic status, with the prevalence of microvascular complications in diabetes. Methods: Successive patients (n = 1214) presenting to our center were evaluated for sociodemographic, anthropometric, clinical, and therapeutic variables. Subjects were classified according to ES into Group 1 (illiterate, 216); Group 2 (≤ primary, 537), Group 3 (≤ higher secondary, 312), and Group 4 (any college, 149). Descriptive statistics is reported. Results: Mean age of patients was 52 ± 10 years, duration of diabetes 7 ± 7 years and 55% were men. Prevalence of various risk factors was smoking/tobacco 25.5%, obesity body mass index ≥25 kg/m2 64.0%, abdominal obesity 63.4%, hypertension 67.5%, high fat diet 14.5%, low fruits/vegetables 31.8%, low fiber intake 60.0%, high salt diet 16.9%, physical inactivity 27.5%, coronary or cerebrovascular disease 3.0%, and microvascular disease (peripheral, ocular or renal) in 20.7%. Microvascular disease was significantly greater in illiterate (25.9%) and low (23.6%) compared to middle (15.0%) and high (14.7%) ES groups (P < 0.05). Age- and sex-adjusted logistic regression analysis revealed that in illiterate and low ES groups respectively, prevalence of smoking/tobacco use (odds ratio 3.84, confidence interval: 09–7.05 and 2.15, 1.36–3.41); low fruit/vegetable (2.51, 1.53–4.14 and 1.99, 1.30–3.04) and low fiber intake (4.02, 2.50–6.45 and 1.78, 1.23–2.59) was greater compared to high ES. Poor diabetes control (HbA1c >.0%) was significantly greater in illiterate (38.0%), low (46.0%), and middle (41.0%) compared to high (31.5%) ES subjects (P < 0.05). Conclusions: There is a greater prevalence of the microvascular disease in illiterate and low ES diabetes patients in India. This is associated with the higher prevalence of smoking/tobacco use, poor quality diet, and sub-optimal diabetes control. PMID:26693427

  13. Non-Invasive Measurement of Skin Microvascular Response during Pharmacological and Physiological Provocations

    PubMed Central

    Iredahl, Fredrik; Löfberg, Andreas; Sjöberg, Folke; Farnebo, Simon; Tesselaar, Erik

    2015-01-01

    Introduction Microvascular changes in the skin due to pharmacological and physiological provocations can be used as a marker for vascular function. While laser Doppler flowmetry (LDF) has been used extensively for measurement of skin microvascular responses, Laser Speckle Contrast Imaging (LSCI) and Tissue Viability Imaging (TiVi) are novel imaging techniques. TiVi measures red blood cell concentration, while LDF and LSCI measure perfusion. Therefore, the aim of this study was to compare responses to provocations in the skin using these different techniques. Method Changes in skin microcirculation were measured in healthy subjects during (1) iontophoresis of sodium nitroprusside (SNP) and noradrenaline (NA), (2) local heating and (3) post-occlusive reactive hyperemia (PORH) using LDF, LSCI and TiVi. Results Iontophoresis of SNP increased perfusion (LSCI: baseline 40.9±6.2 PU; 10-min 100±25 PU; p<0.001) and RBC concentration (TiVi: baseline 119±18; 10-min 150±41 AU; p = 0.011). No change in perfusion (LSCI) was observed after iontophoresis of NA (baseline 38.0±4.4 PU; 10-min 38.9±5.0 PU; p = 0.64), while RBC concentration decreased (TiVi: baseline 59.6±11.8 AU; 10-min 54.4±13.3 AU; p = 0.021). Local heating increased perfusion (LDF: baseline 8.8±3.6 PU; max 112±55 PU; p<0.001, LSCI: baseline 50.8±8.0 PU; max 151±22 PU; p<0.001) and RBC concentration (TiVi: baseline 49.2±32.9 AU; max 99.3±28.3 AU; p<0.001). After 5 minutes of forearm occlusion with prior exsanguination, a decrease was seen in perfusion (LDF: p = 0.027; LSCI: p<0.001) and in RBC concentration (p = 0.045). Only LSCI showed a significant decrease in perfusion after 5 minutes of occlusion without prior exsanguination (p<0.001). Coefficients of variation were lower for LSCI and TiVi compared to LDF for most responses. Conclusion LSCI is more sensitive than TiVi for measuring microvascular changes during SNP-induced vasodilatation and forearm occlusion. TiVi is more sensitive to noradrenaline

  14. Fast and Accurate Microplate Method (Biolog MT2) for Detection of Fusarium Fungicides Resistance/Sensitivity

    PubMed Central

    Frąc, Magdalena; Gryta, Agata; Oszust, Karolina; Kotowicz, Natalia

    2016-01-01

    The need for finding fungicides against Fusarium is a key step in the chemical plant protection and using appropriate chemical agents. Existing, conventional methods of evaluation of Fusarium isolates resistance to fungicides are costly, time-consuming and potentially environmentally harmful due to usage of high amounts of potentially toxic chemicals. Therefore, the development of fast, accurate and effective detection methods for Fusarium resistance to fungicides is urgently required. MT2 microplates (BiologTM) method is traditionally used for bacteria identification and the evaluation of their ability to utilize different carbon substrates. However, to the best of our knowledge, there is no reports concerning the use of this technical tool to determine fungicides resistance of the Fusarium isolates. For this reason, the objectives of this study are to develop a fast method for Fusarium resistance to fungicides detection and to validate the effectiveness approach between both traditional hole-plate and MT2 microplates assays. In presented study MT2 microplate-based assay was evaluated for potential use as an alternative resistance detection method. This was carried out using three commercially available fungicides, containing following active substances: triazoles (tebuconazole), benzimidazoles (carbendazim) and strobilurins (azoxystrobin), in six concentrations (0, 0.0005, 0.005, 0.05, 0.1, 0.2%), for nine selected Fusarium isolates. In this study, the particular concentrations of each fungicides was loaded into MT2 microplate wells. The wells were inoculated with the Fusarium mycelium suspended in PM4-IF inoculating fluid. Before inoculation the suspension was standardized for each isolates into 75% of transmittance. Traditional hole-plate method was used as a control assay. The fungicides concentrations in control method were the following: 0, 0.0005, 0.005, 0.05, 0.5, 1, 2, 5, 10, 25, and 50%. Strong relationships between MT2 microplate and traditional hole

  15. Fast and Accurate Microplate Method (Biolog MT2) for Detection of Fusarium Fungicides Resistance/Sensitivity.

    PubMed

    Frąc, Magdalena; Gryta, Agata; Oszust, Karolina; Kotowicz, Natalia

    2016-01-01

    The need for finding fungicides against Fusarium is a key step in the chemical plant protection and using appropriate chemical agents. Existing, conventional methods of evaluation of Fusarium isolates resistance to fungicides are costly, time-consuming and potentially environmentally harmful due to usage of high amounts of potentially toxic chemicals. Therefore, the development of fast, accurate and effective detection methods for Fusarium resistance to fungicides is urgently required. MT2 microplates (Biolog(TM)) method is traditionally used for bacteria identification and the evaluation of their ability to utilize different carbon substrates. However, to the best of our knowledge, there is no reports concerning the use of this technical tool to determine fungicides resistance of the Fusarium isolates. For this reason, the objectives of this study are to develop a fast method for Fusarium resistance to fungicides detection and to validate the effectiveness approach between both traditional hole-plate and MT2 microplates assays. In presented study MT2 microplate-based assay was evaluated for potential use as an alternative resistance detection method. This was carried out using three commercially available fungicides, containing following active substances: triazoles (tebuconazole), benzimidazoles (carbendazim) and strobilurins (azoxystrobin), in six concentrations (0, 0.0005, 0.005, 0.05, 0.1, 0.2%), for nine selected Fusarium isolates. In this study, the particular concentrations of each fungicides was loaded into MT2 microplate wells. The wells were inoculated with the Fusarium mycelium suspended in PM4-IF inoculating fluid. Before inoculation the suspension was standardized for each isolates into 75% of transmittance. Traditional hole-plate method was used as a control assay. The fungicides concentrations in control method were the following: 0, 0.0005, 0.005, 0.05, 0.5, 1, 2, 5, 10, 25, and 50%. Strong relationships between MT2 microplate and traditional hole

  16. A Novel Method of Modeling the Deformation Resistance for Clad Sheet

    SciTech Connect

    Hu Jianliang; Yi Youping; Xie Mantang

    2011-08-22

    Because of the excellent thermal conductivity, the clad sheet (3003/4004/3003) of aluminum alloy is extensively used in various heat exchangers, such as radiator, motorcar air conditioning, evaporator, and so on. The deformation resistance model plays an important role in designing the process parameters of hot continuous rolling. However, the complex behaviors of the plastic deformation of the clad sheet make the modeling very difficult. In this work, a novel method for modeling the deformation resistance of clad sheet was proposed by combining the finite element analysis with experiments. The deformation resistance model of aluminum 3003 and 4004 was proposed through hot compression test on the Gleeble-1500 thermo-simulation machine. And the deformation resistance model of clad sheet was proposed through finite element analysis using DEFORM-2D software. The relationship between cladding ratio and the deformation resistance was discussed in detail. The results of hot compression simulation demonstrate that the cladding ratio has great effects on the resistance of the clad sheet. Taking the cladding ratio into consideration, the mathematical model of the deformation resistance for clad sheet has been proved to have perfect forecasting precision of different cladding ratio. Therefore, the presented model can be used to predict the rolling force of clad sheet during the hot continuous rolling process.

  17. Photoacoustic microscopy of microvascular responses to cortical electrical stimulation

    NASA Astrophysics Data System (ADS)

    Tsytsarev, Vassiliy; Hu, Song; Yao, Junjie; Maslov, Konstantin; Barbour, Dennis L.; Wang, Lihong V.

    2011-07-01

    Advances in the functional imaging of cortical hemodynamics have greatly facilitated the understanding of neurovascular coupling. In this study, label-free optical-resolution photoacoustic microscopy (OR-PAM) was used to monitor microvascular responses to direct electrical stimulations of the mouse somatosensory cortex through a cranial opening. The responses appeared in two forms: vasoconstriction and vasodilatation. The transition between these two forms of response was observed in single vessels by varying the stimulation intensity. Marked correlation was found between the current-dependent responses of two daughter vessels bifurcating from the same parent vessel. Statistical analysis of twenty-seven vessels from three different animals further characterized the spatial-temporal features and the current dependence of the microvascular response. Our results demonstrate that OR-PAM is a valuable tool to study neurovascular coupling at the microscopic level.

  18. Multiple equilibrium states for blood flow in microvascular networks

    NASA Astrophysics Data System (ADS)

    Pollock-Muskin, Halley; Diehl, Cecilia; Mohamed, Nora; Karst, Nathan; Geddes, John; Storey, Brian

    2015-11-01

    When blood flows through a vessel bifurcation at the microvascular scale, the hematocrits in the downstream daughter vessels are generally not equal. This phenomenon, known as plasma skimming, can cause heterogeneity in the distribution of red blood cells inside a vessel network. Using established models for plasma skimming, we investigate the equilibrium states in a microvascular network with simple topologies. We find that even simple networks can have multiple equilibrium states for the flow rates and distributions of red blood cells inside the network for fixed inlet conditions. In a ladder network, we find that for certain inlet conditions the network can have 2N observable equilibrium states where N is the number of rungs in the ladder. For ladders with even just a few rungs, the complex equilibrium curves make it seemingly impossible to set the internal state of the network by controlling the inlet flows. Microfluidic experiments are being used to confirm the model predictions.

  19. Treatment of Angina Pectoris Associated with Coronary Microvascular Dysfunction.

    PubMed

    Ong, Peter; Athanasiadis, Anastasios; Sechtem, Udo

    2016-08-01

    Treatment of angina pectoris associated with coronary microvascular dysfunction is challenging as the underlying mechanisms are often diverse and overlapping. Patients with type 1 coronary microvascular dysfunction (i.e. absence of epicardial coronary artery disease and myocardial disease) should receive strict control of their cardiovascular risk factors and thus receive statins and ACE-inhibitors in most cases. Antianginal medication consists of ß-blockers and/or calcium channel blockers. Second line drugs are ranolazine and nicorandil with limited evidence. Despite individually titrated combinations of these drugs up to 30 % of patients have refractory angina. Rho-kinase inhibitors and endothelin-receptor antagonists represent potential drugs that may prove useful in these patients in the future.

  20. Impact of simulated microgravity on microvascular endothelial cell apoptosis.

    PubMed

    Kang, Chun-Yan; Zou, Lin; Yuan, Ming; Wang, Yang; Li, Tian-Zhi; Zhang, Ye; Wang, Jun-Feng; Li, Yan; Deng, Xiao-Wei; Liu, Chang-Ting

    2011-09-01

    Cardiovascular deconditioning is known to occur in astronauts exposed to microgravity. Endothelial dysfunction at microcirculatory sites might contribute to cardiovascular deconditioning induced by weightlessness. Recent studies have reported changes in the morphology and gene expression of endothelial cells exposed to conditions of simulated microgravity. The present study was aimed at examining the effects of microgravity on the apoptosis of microvascular endothelial cells and the mechanism underlying these effects. We simulated a microgravity environment and found that microgravity induced microvascular endothelial cell apoptosis and that this effect was correlated with the downregulation of the PI3K/Akt pathway, increased expression of NF-κB, and depolymerization of F-actin. These findings may provide important insights into the origin of the adverse physiological changes occurring due to exposure to microgravity conditions. PMID:21287193

  1. Impact of simulated microgravity on microvascular endothelial cell apoptosis.

    PubMed

    Kang, Chun-Yan; Zou, Lin; Yuan, Ming; Wang, Yang; Li, Tian-Zhi; Zhang, Ye; Wang, Jun-Feng; Li, Yan; Deng, Xiao-Wei; Liu, Chang-Ting

    2011-09-01

    Cardiovascular deconditioning is known to occur in astronauts exposed to microgravity. Endothelial dysfunction at microcirculatory sites might contribute to cardiovascular deconditioning induced by weightlessness. Recent studies have reported changes in the morphology and gene expression of endothelial cells exposed to conditions of simulated microgravity. The present study was aimed at examining the effects of microgravity on the apoptosis of microvascular endothelial cells and the mechanism underlying these effects. We simulated a microgravity environment and found that microgravity induced microvascular endothelial cell apoptosis and that this effect was correlated with the downregulation of the PI3K/Akt pathway, increased expression of NF-κB, and depolymerization of F-actin. These findings may provide important insights into the origin of the adverse physiological changes occurring due to exposure to microgravity conditions.

  2. Evaluation of Colorimetric Methods Using Nicotinamide for Rapid Detection of Pyrazinamide Resistance in Mycobacterium tuberculosis▿

    PubMed Central

    Mirabal, Niuris C.; Yzquierdo, Sergio L.; Lemus, Dihadenys; Madruga, Mariela; Milián, Yoslaine; Echemendía, Miguel; Takiff, Howard; Martin, Anandi; Van der Stuyf, Patrick; Palomino, Juan Carlos; Montoro, Ernesto

    2010-01-01

    The direct detection of pyrazinamide resistance in Mycobacterium tuberculosis is sufficiently difficult that many laboratories do not attempt it. Most pyrazinamide resistance is caused by mutations that inactivate the pyrazinamidase enzyme needed to convert the prodrug pyrazinamide to its active form. We evaluated two newer and simpler methods to assess pyrazinamidase activity, the nitrate reductase and malachite green microtube assays, using nicotinamide in place of pyrazinamide. A total of 102 strains were tested by these methods and the results compared with those obtained by the classic Wayne assay. Mutations in the pncA gene were identified by sequencing the pncA genes from all isolates in which pyrazinamide resistance was detected by any of the three methods. Both the nitrate reductase and malachite green microtube assays showed sensitivities of 93.75% and specificities of 97.67%. Mutations in the pncA gene were found in 14 of 16 strains that were pyrazinamide resistant and in 1 of 4 strains that were sensitive by the Wayne assay. Both of these simple methods, used with nicotinamide, are promising and inexpensive alternatives for the rapid detection of pyrazinamide resistance in limited-resource countries. PMID:20554826

  3. Forward modeling of marine DC resistivity method for a layered anisotropic earth

    NASA Astrophysics Data System (ADS)

    Yin, Chang-Chun; Zhang, Ping; Cai, Jing

    2016-06-01

    Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell's equations for an anisotropic model, we introduce scalar potentials based on the divergence-free characteristic of the electric and magnetic (EM) fields. We then continue the EM fields down into the deep earth and upward into the seawater and couple them at the ocean bottom to the transmitting source. By studying both the DC apparent resistivity curves and their polar plots, we can resolve the anisotropy of the ocean bottom. Forward modeling of a high-resistivity thin layer in an anisotropic half-space demonstrates that the marine DC resistivity method in shallow water is very sensitive to the resistive reservoir but is not influenced by airwaves. As such, it is very suitable for oil and gas exploration in shallowwater areas but, to date, most modeling algorithms for studying marine DC resistivity are based on isotropic models. In this paper, we investigate one-dimensional anisotropic forward modeling for marine DC resistivity method, prove the algorithm to have high accuracy, and thus provide a theoretical basis for 2D and 3D forward modeling.

  4. Preventing microvascular complications in type 1 diabetes mellitus.

    PubMed

    Viswanathan, Vijay

    2015-04-01

    Patients with complications of diabetes such as retinopathy, nephropathy, and cardiovascular complications have increased hospital stay with greater economic burden. Prevention of complications should be started before the onset of type 1 diabetes mellitus (T1DM) by working on risk factors and thereafter by intervention upon confirmatory diagnosis which can prevent further damage to β-cells. The actual risk of getting microvascular complications like microalbuminuria and retinopathy progression starts at glycated hemoglobin (HbA1c) level of 7%. As per the American Diabetes Association, a new pediatric glycemic control target of HbA1c <7.5% across all ages replaces previous guidelines that had called for different targets by age. Evidence shows that prevalence of microvascular complications is greater in patients with age >20 years as compared to patients <10 years of age. Screening of these complications should be done regularly, and appropriate preventive strategies should be followed. Angiotensin converting enzyme inhibitors and angiotensin II receptor blocker reduce progression from microalbuminuria to macroalbuminuria and increase the regression rate to normoalbuminuria. Diabetic microvascular complications can be controlled with tight glycemic therapy, dyslipidemia management and blood pressure control along with renal function monitoring, lifestyle changes, including smoking cessation and low-protein diet. An integrated and personalized care would reduce the risk of development of microvascular complications in T1DM patients. The child with diabetes who receives limited care is more likely to develop long-term complications at an earlier age. Screening for subclinical complications and early interventions with intensive therapy is the need of the hour.

  5. Hemimasticatory spasm treated with microvascular decompression of the trigeminal nerve.

    PubMed

    Chon, Kyu-Hyon; Lee, Jong-Myong; Koh, Eun-Jeong; Choi, Ha-Young

    2012-09-01

    Hemimasticatory spasm is a very rare disorder of the trigeminal nerve characterized by paroxysmal involuntary contraction of the jaw-closing muscles. The mechanisms leading to hemimasticatory spasm are still unclear. Recently, injection of botulinum toxin has become the treatment of choice due to its excellent results. We report a case of a successful treatment of hemimasticatory spasm via microvascular decompression of the motor branch of the trigeminal nerve.

  6. Patterns and Variations in Microvascular Decompression for Trigeminal Neuralgia

    PubMed Central

    TODA, Hiroki; GOTO, Masanori; IWASAKI, Koichi

    2015-01-01

    Microvascular decompression (MVD) is a highly effective surgical treatment for trigeminal neuralgia (TN). Although there is little prospective clinical evidence, accumulated observational studies have demonstrated the benefits of MVD for refractory TN. In the current surgical practice of MVD for TN, there have been recognized patterns and variations in surgical anatomy and various decompression techniques. Here we provide a stepwise description of surgical procedures and relevant anatomical characteristics, as well as procedural options. PMID:25925756

  7. Evaluation of intraoperative anticoagulants in microvascular free-flap surgery.

    PubMed Central

    Pugh, C. M.; Dennis, R. H.; Massac, E. A.

    1996-01-01

    This retrospective study evaluated anticoagulants used during surgery to determine efficacy and associated complications. The patient population was comprised of 15 patients who underwent microvascular free-flap surgery for wound coverage of the lower one third of the leg. Results indicated that the use of heparin in conjunction with other anticoagulants was associated with the development of more hematomas compared with the use of aspirin and dextran, both separately and together. PMID:8918071

  8. Reversibility of retinal microvascular changes in severe falciparum malaria.

    PubMed

    Maude, Richard J; Kingston, Hugh W F; Joshi, Sonia; Mohanty, Sanjib; Mishra, Saroj K; White, Nicholas J; Dondorp, Arjen M

    2014-09-01

    Malarial retinopathy allows detailed study of central nervous system vascular pathology in living patients with severe malaria. An adult with cerebral malaria is described who had prominent retinal whitening with corresponding retinal microvascular obstruction, vessel dilatation, increased vascular tortuosity, and blood retinal barrier leakage with decreased visual acuity, all of which resolved on recovery. Additional study of these features and their potential role in elucidating the pathogenesis of cerebral malaria is warranted.

  9. Microvascular Transport and Tumor Cell Adhesion in the Microcirculation

    PubMed Central

    Fu, Bingmei M.; Liu, Yang

    2016-01-01

    One critical step in tumor metastasis is tumor cell adhesion to the endothelium forming the microvessel wall. Understanding this step may lead to new therapeutic concepts for tumor metastasis. Vascular endothelium forming the microvessel wall and the glycocalyx layer at its surface are the principal barriers to, and regulators of the material exchange between circulating blood and body tissues. The cleft between adjacent ECs (interendothelial cleft) is the principal pathway for water and solutes transport through the microvessel wall in health. It is also suggested to be the pathway for high molecular weight plasma proteins, leukocytes and tumor cells across microvessel walls in disease. Thus the first part of the review introduced the mathematical models for water and solutes transport through the interendothelial cleft. These models, combined with the experimental results from in vivo animal studies and electron microscopic observations, are used to evaluate the role of the endothelial surface glycocalyx, the junction strand geometry in the interendothelial cleft, and the surrounding extracellular matrix and tissue cells, as the determinants of microvascular transport. The second part of the review demonstrated how the microvascular permeability, hydrodynamic factors, microvascular geometry and cell adhesion molecules affect tumor cell adhesion in the microcirculation. PMID:22476895

  10. Obesity Related Coronary Microvascular Dysfunction: From Basic to Clinical Practice

    PubMed Central

    Selthofer-Relatić, K.; Bošnjak, I.; Kibel, A.

    2016-01-01

    Obesity related coronary microvascular disease is a medical entity which is not yet fully elucidated. The pathophysiological basis of coronary microcirculatory dysfunction consists of a heterogeneous group of disorders with individual morphologic/functional/clinical presentation and prognosis. Coronary microcirculatory changes include mechanisms connected with vascular dysfunction, as well as extravascular and vasostructural changes in responses to neural, mechanical, and metabolic factors. Cardiometabolic changes that include obesity, dyslipidemia, diabetes mellitus type II, and hypertension are associated with atherosclerosis of epicardial coronary arteries and/or microvascular coronary dysfunction, with incompletely understood underlying mechanisms. In obesity, microvascular disease is mediated via adipokines/cytokines causing chronic, subclinical inflammation with (a) reduced NO-mediated dilatation, (b) changed endothelial- and smooth muscle-dependent vasoregulating mechanisms, (c) altered vasomotor control with increased sympathetic activity, and (d) obesity related hypertension with cardiomyocytes hypertrophy and impaired cardiac vascular adaptation to metabolic needs. From a clinical point of view it can present itself in acute or chronic form with different prognosis, as a practice problem for real-life diagnosis and treatment. PMID:27092288

  11. Evaluation of gravimetric techniques to estimate the microvascular filtration coefficient.

    PubMed

    Dongaonkar, R M; Laine, G A; Stewart, R H; Quick, C M

    2011-06-01

    Microvascular permeability to water is characterized by the microvascular filtration coefficient (K(f)). Conventional gravimetric techniques to estimate K(f) rely on data obtained from either transient or steady-state increases in organ weight in response to increases in microvascular pressure. Both techniques result in considerably different estimates and neither account for interstitial fluid storage and lymphatic return. We therefore developed a theoretical framework to evaluate K(f) estimation techniques by 1) comparing conventional techniques to a novel technique that includes effects of interstitial fluid storage and lymphatic return, 2) evaluating the ability of conventional techniques to reproduce K(f) from simulated gravimetric data generated by a realistic interstitial fluid balance model, 3) analyzing new data collected from rat intestine, and 4) analyzing previously reported data. These approaches revealed that the steady-state gravimetric technique yields estimates that are not directly related to K(f) and are in some cases directly proportional to interstitial compliance. However, the transient gravimetric technique yields accurate estimates in some organs, because the typical experimental duration minimizes the effects of interstitial fluid storage and lymphatic return. Furthermore, our analytical framework reveals that the supposed requirement of tying off all draining lymphatic vessels for the transient technique is unnecessary. Finally, our numerical simulations indicate that our comprehensive technique accurately reproduces the value of K(f) in all organs, is not confounded by interstitial storage and lymphatic return, and provides corroboration of the estimate from the transient technique.

  12. Delayed, bilateral, non-microvascular ear replantation after violent amputation.

    PubMed

    García-Murray, E; Adán-Rivas, O; Salcido-Calzadilla, H

    2009-06-01

    Amputation of any body part is undoubtedly a traumatic experience leaving a terrible deformity, especially when the part or parts involved are visible and constitute an essential component of someone's facial whole. Bilateral ear amputation and successful subsequent replantation has been reported historically, but not in the modern surgical literature. We report the case of a 27-year-old female who was abducted and suffered a bilateral ear amputation at the hands of one of her captors to speed delivery of ransom money; the severed parts were sent to the parents approximately 2 hours after the amputation had taken place, and the girl was released some 48 hours after the ears were delivered. Microvascular replantation was attempted immediately after admission to the hospital some 2 hours after her release, but failed, and so a non-microvascular replantation was performed and was successful, after approximately 54 hours of ischaemia time. We consider this the first report of a complete bilateral, delayed, non-microvascular, successful ear replantation in a human being in the modern literature. PMID:18083644

  13. Inflammatory pathways and microvascular responses in the lung.

    PubMed

    Kuebler, Wolfgang M

    2005-01-01

    Neutrophil granulocytes constitute an important host defense mechanism, but may at the same time damage functional tissue and propagate acute organ failure. This balance is particularly vulnerable in the lung which provides a large surface area for invading pathogens and microorganisms, and simultaneously harbors a large pool of physiologically marginated neutrophils within its microvascular bed. Pathophysiological stimuli further amplify this accumulation of blood cells and promote the emigration of neutrophils into the pulmonary interstitium and the airspaces by different mechanisms depending on the pathophysiological stimulus, its route of entry into or site of production in the lung, and the time course of its action. Importantly, the pulmonary microvascular endothelium plays a key role in regulating not only sequestration and emigration of neutrophils, but by initiating the inflammatory response to a variety of diverse stimuli many of which do not directly target the circulating neutrophil, but elicit microvascular reactions by primarily acting on the endothelium. This review highlights the inflammatory process in the pulmonary microvasculature with special emphasis on the role of the pulmonary endothelium.

  14. Microvascular architecture of the filiform papillae in primates and insectivores.

    PubMed

    Okada, S; Ohta, Y; Matsukawa, N; Sugioka, S

    1993-03-01

    The microvascular architecture of filiform papillae was investigated under a scanning electron microscope in man, Japanese monkeys, common squirrel monkeys, common marmosets, common tree shrews, large Japanese moles and dwarf shrews utilizing microvascular corrosion casts. Filiform papillae were circularly arranged in primates, and each of them was supplied by a hairpin capillary loop. These papillae sometimes were aggregated. The filiform papillae of Japanese monkeys exhibited markedly locational differences on the lingual dorsum and were supplied by circularly arranged capillary loops or by an intrapapillary capillary network. Small filiform papillae were located on an epithelial eminence in the lingual radix, each of them supplied by a low and simple hairpin capillary loop. The aggregated filiform papillae of common squirrel monkeys were less frequent without any locational differences. Low filiform papillae of common marmosets and tree shrews were simpler in form, being arranged in a circle and supplied by a simple hairpin capillary loop. The filiform papillae of insectivores were not arranged in a circle. The filiform papillae of dwarf shrews were supplied by an incomplete capillary ring without a loop. With respect to species differences, the circularly arranged capillary loops in man were most complicated and highly developed. Microvascular architecture of the filiform papillae of insectivores was much simpler, different from those observed in primates.

  15. Evaluation of gravimetric techniques to estimate the microvascular filtration coefficient.

    PubMed

    Dongaonkar, R M; Laine, G A; Stewart, R H; Quick, C M

    2011-06-01

    Microvascular permeability to water is characterized by the microvascular filtration coefficient (K(f)). Conventional gravimetric techniques to estimate K(f) rely on data obtained from either transient or steady-state increases in organ weight in response to increases in microvascular pressure. Both techniques result in considerably different estimates and neither account for interstitial fluid storage and lymphatic return. We therefore developed a theoretical framework to evaluate K(f) estimation techniques by 1) comparing conventional techniques to a novel technique that includes effects of interstitial fluid storage and lymphatic return, 2) evaluating the ability of conventional techniques to reproduce K(f) from simulated gravimetric data generated by a realistic interstitial fluid balance model, 3) analyzing new data collected from rat intestine, and 4) analyzing previously reported data. These approaches revealed that the steady-state gravimetric technique yields estimates that are not directly related to K(f) and are in some cases directly proportional to interstitial compliance. However, the transient gravimetric technique yields accurate estimates in some organs, because the typical experimental duration minimizes the effects of interstitial fluid storage and lymphatic return. Furthermore, our analytical framework reveals that the supposed requirement of tying off all draining lymphatic vessels for the transient technique is unnecessary. Finally, our numerical simulations indicate that our comprehensive technique accurately reproduces the value of K(f) in all organs, is not confounded by interstitial storage and lymphatic return, and provides corroboration of the estimate from the transient technique. PMID:21346245

  16. A siphon method of determining resistivities of thin heat-pipe wicks

    NASA Technical Reports Server (NTRS)

    Katzoff, S.

    1978-01-01

    A simple siphon method is described for determining the resistivities of thin heat pipe wicks as a function of the pressure difference between the liquid in the wick and the vapor above it. The method was applied to wicks of one layer and two layers of 100 mesh (40 per centimeter) stainless steel screens diffusion bonded to stainless steel substrates. Some possible improvements in the method are suggested.

  17. A method for the field assessment of rolling resistance properties of manual wheelchairs.

    PubMed

    Bascou, Joseph; Sauret, Christophe; Pillet, Hélène; Vaslin, Philippe; Thoreux, Patricia; Lavaste, François

    2013-04-01

    This article presents an examination and validation of a method to measure the field deceleration of a manual wheelchair (MWC) and to calculate the rolling resistances properties of the front and rear wheels. This method was based on the measurements of the MWC deceleration for various load settings from a 3D accelerometer. A mechanical model of MWC deceleration was developed which allowed computing the rolling resistance factors of front and rear wheels on a tested surface. Four deceleration sets were conducted on two paths on the same ground to test the repeatability. Two other deceleration sets were conducted using different load settings to compute the rolling resistance parameters (RPs). The theoretical decelerations of three load settings were computed and compared with the measured decelerations. The results showed good repeatability (variations of measures represented 6-11% of the nominal values) and no statistical difference between the path results. The rolling RPs were computed and their confidence intervals were assessed. For the last three sets, no significant difference was found between the theoretical and measured decelerations. This method can determine the specific rolling resistance properties of the wheels of a MWC, and be employed to establish a catalogue of the rolling resistance properties of wheels on various surfaces.

  18. Using simulations to evaluate Mantel-based methods for assessing landscape resistance to gene flow.

    PubMed

    Zeller, Katherine A; Creech, Tyler G; Millette, Katie L; Crowhurst, Rachel S; Long, Robert A; Wagner, Helene H; Balkenhol, Niko; Landguth, Erin L

    2016-06-01

    Mantel-based tests have been the primary analytical methods for understanding how landscape features influence observed spatial genetic structure. Simulation studies examining Mantel-based approaches have highlighted major challenges associated with the use of such tests and fueled debate on when the Mantel test is appropriate for landscape genetics studies. We aim to provide some clarity in this debate using spatially explicit, individual-based, genetic simulations to examine the effects of the following on the performance of Mantel-based methods: (1) landscape configuration, (2) spatial genetic nonequilibrium, (3) nonlinear relationships between genetic and cost distances, and (4) correlation among cost distances derived from competing resistance models. Under most conditions, Mantel-based methods performed poorly. Causal modeling identified the true model only 22% of the time. Using relative support and simple Mantel r values boosted performance to approximately 50%. Across all methods, performance increased when landscapes were more fragmented, spatial genetic equilibrium was reached, and the relationship between cost distance and genetic distance was linearized. Performance depended on cost distance correlations among resistance models rather than cell-wise resistance correlations. Given these results, we suggest that the use of Mantel tests with linearized relationships is appropriate for discriminating among resistance models that have cost distance correlations <0.85 with each other for causal modeling, or <0.95 for relative support or simple Mantel r. Because most alternative parameterizations of resistance for the same landscape variable will result in highly correlated cost distances, the use of Mantel test-based methods to fine-tune resistance values will often not be effective. PMID:27516868

  19. Using simulations to evaluate Mantel-based methods for assessing landscape resistance to gene flow.

    PubMed

    Zeller, Katherine A; Creech, Tyler G; Millette, Katie L; Crowhurst, Rachel S; Long, Robert A; Wagner, Helene H; Balkenhol, Niko; Landguth, Erin L

    2016-06-01

    Mantel-based tests have been the primary analytical methods for understanding how landscape features influence observed spatial genetic structure. Simulation studies examining Mantel-based approaches have highlighted major challenges associated with the use of such tests and fueled debate on when the Mantel test is appropriate for landscape genetics studies. We aim to provide some clarity in this debate using spatially explicit, individual-based, genetic simulations to examine the effects of the following on the performance of Mantel-based methods: (1) landscape configuration, (2) spatial genetic nonequilibrium, (3) nonlinear relationships between genetic and cost distances, and (4) correlation among cost distances derived from competing resistance models. Under most conditions, Mantel-based methods performed poorly. Causal modeling identified the true model only 22% of the time. Using relative support and simple Mantel r values boosted performance to approximately 50%. Across all methods, performance increased when landscapes were more fragmented, spatial genetic equilibrium was reached, and the relationship between cost distance and genetic distance was linearized. Performance depended on cost distance correlations among resistance models rather than cell-wise resistance correlations. Given these results, we suggest that the use of Mantel tests with linearized relationships is appropriate for discriminating among resistance models that have cost distance correlations <0.85 with each other for causal modeling, or <0.95 for relative support or simple Mantel r. Because most alternative parameterizations of resistance for the same landscape variable will result in highly correlated cost distances, the use of Mantel test-based methods to fine-tune resistance values will often not be effective.

  20. 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

  1. Early postoperative bone scintigraphy in the evaluation of microvascular bone grafts in head and neck reconstruction

    PubMed Central

    Schuepbach, Jonas; Dassonville, Olivier; Poissonnet, Gilles; Demard, Francois

    2007-01-01

    Background Bone scintigraphy was performed to monitor anastomotic patency and bone viability. Methods In this retrospective study, bone scans were carried out during the first three postoperative days in a series of 60 patients who underwent microvascular bone grafting for reconstruction of the mandible or maxilla. Results In our series, early bone scans detected a compromised vascular supply to the bone with high accuracy (p < 10-6) and a sensitivity that was superior to the sensitivity of clinical monitoring (92% and 75% respectively). Conclusion When performing bone scintigraphy during the first three postoperative days, it not only helps to detect complications with high accuracy, as described in earlier studies, but it is also an additional reliable monitoring tool to decide whether or not microvascular revision surgery should be performed. Bone scans were especially useful in buried free flaps where early postoperative monitoring depended exclusively on scans. According to our experience, we recommend bone scans as soon as possible after surgery and immediately in cases suspicious of vascularized bone graft failure. PMID:17448223

  2. Intraoperative microvascular Doppler ultrasonography in cerebral aneurysm surgery

    PubMed Central

    Stendel, R.; Pietila, T.; Al, H; Schilling, A.; Brock, M.

    2000-01-01

    OBJECTIVES—Outcome of surgical treatment of cerebral aneurysms may be severely compromised by local cerebral ischaemia or infarction resulting from the inadvertent occlusion of an adjacent vessel by the aneurysm clip, or by incomplete aneurysm closure. It is therefore mandatory to optimise clip placement in situ to reduce the complication rate. The present study was performed to investigate the reliability of intraoperative microvascular Doppler ultrasonography (MDU) in cerebral aneurysm surgery, and to assess the impact of this method on the surgical procedure itself.
METHODS—Seventy five patients (19 men, 56 women, mean age 54.8 years, range 22-84 years) with 90 saccular cerebral aneurysms were evaluated. Blood flow velocities in the aneurysmal sac and in the adjacent vessels were determined by MDU before and after aneurysm clipping. The findings of MDU were analysed and compared with those of visual inspection of the surgical site and of postoperative angiography. Analysis was also made of the cases in which the clip was repositioned due to MDU findings.
RESULTS—A relevant stenosis of an adjacent vessel induced by clip positioning that had escaped detection by visual inspection was identified by Doppler ultrasonography in 17 out of 90 (18.9%) aneurysms. In addition, Doppler ultrasound demonstrated a primarily unoccluded aneurysm in 11 out of 90 (12.2%) patients. The aneurysm clip was repositioned on the basis of the MDU findings in 26 out of 90 (28.8%) cases. In middle cerebral artery (MCA) aneurysms, the MDU results were relevant to the surgical procedure in 17out of 44 (38.6%) cases. Whereas with aneurysms of the anterior cerebral artery significant findings occurred in only five of 32cases (15.6%; p<0.05). The clip was repositioned on the basis of the MDU results in 18 out of 50 (36%) aneurysms in patients with subarachnoid haemorrhage (SAH) grade I-V compared with only eight out of 40 (20%) aneurysms in patients without SAH (p<0.05).

  3. A pressure-based high resolution numerical method for resistive MHD

    NASA Astrophysics Data System (ADS)

    Xisto, Carlos M.; Páscoa, José C.; Oliveira, Paulo J.

    2014-10-01

    In the paper we describe in detail a numerical method for the resistive magnetohydrodynamic (MHD) equations involving viscous flow and report the results of application to a number of typical MHD test cases. The method is of the finite volume type but mixes aspects of pressure-correction and density based solvers; the algorithm arrangement is patterned on the well-known PISO algorithm, which is a pressure method, while the flux computation makes use of the AUSM-MHD scheme, which originates from density based methods. Five groups of test cases are addressed to verify and validate the method. We start with two resistive MHD cases, namely the Shercliff and Hunt flow problems, which are intended to validate the method for low-speed resistive MHD flows. The remaining three test cases, namely the cloud-shock interaction, the MHD rotor and the MHD blast wave, are standard 2D ideal MHD problems that serve to validate the method under high-speed flow and complex interaction of MHD shocks. Finally, we demonstrate the method with a more complex application problem, and discuss results of simulation for a quasi-bi-dimensional self-field magnetoplasmadynamic (MPD) thruster, for which we study the effect of cathode length upon the electromagnetic nozzle performance.

  4. Detection of clarithromycin-resistant Helicobacter pylori in clinical specimens by molecular methods: A review.

    PubMed

    Xuan, Shi-Hai; Wu, Li-Pei; Zhou, Yu-Gui; Xiao, Ming-Bing

    2016-03-01

    Various molecular methods have been developed to rapidly detect clarithromycin (CLR) resistance in Helicobacter pylori isolates in clinical specimens. All of these assays for detecting CLR resistance in H. pylori are based on detection of mutations in the 23S rRNA gene. In this article, we summarise current knowledge regarding the detection of H. pylori CLR resistance in clinical specimens by molecular tests. The available data showed that restriction fragment length polymorphism (RFLP), 3'-mismatch PCR, DNA sequencing, the PCR line probe assay (PCR-LiPA) and fluorescence in situ hybridisation assay (FISH) are able to detect CLR-resistant H. pylori in clinical specimens with excellent specificity and sensitivity. However, several factors limit their clinical application, including fastidious, time-consuming preparation and low-throughput as well as carrying a risk of contamination. Furthermore, as an invasive method, FISH is not suitable for children or the elderly. Among the molecular methods, one that is most promising for the future is real-time PCR probe hybridisation technology using fluorescence resonance energy transfer (FRET) probes, which can rapidly detect CLR resistance with high sensitivity and specificity in biopsies and stool specimens, even though mixed infections are present in clinical specimens. Moreover, due to the advantages that this method is simple, rapid and economical, real-time PCR is technically feasible for clinical application in small- and medium-sized hospitals in developing countries. Second, with high sensitivity, specificity and throughput, DNA chips will also be a valuable tool for detecting resistant H. pylori isolates from cultures and clinical specimens. PMID:27436390

  5. Case study on the evaluation of the ground reinforcement with complex resistivity method

    NASA Astrophysics Data System (ADS)

    Son, J.; Kim, J.; Park, S.

    2008-12-01

    Recently complex resistivity (CR) method is applied to the various engineering purpose mainly due to the development of measurement instruments, which enables the detection of small IP effect in the subsurface. CR method is one of frequency-domain IP method, and it measures the amplitude and absolute phase with respect to the transmitted current. It is known as a spectral IP (SIP) method. With the recent development of instrument, the modeling and analysis algorithm for the CR method were already developed and nearly completed. In this study, we applied CR method to characterize the effect of ground reinforcement which uses grouting with the injection of cement mortar material. As curing the injected cement mortar, the electric conductivity changes, and average conductivity of it is very high. Because of it, we used the DC resistivity monitoring as the way of evaluating the grouting performance. In addition to this, we applied the CR method after that the ground reinforcement with grouting was completed because we thought that cement mortar may show a strong IP effect. For the DC monitoring, we acquired the surface resistivity data before, during and after grouting. Total six data sets were acquired and processed with the recently developed 4D inversion algorithm. CR data is also processed with the developed two-dimensional inversion algorithm and then inverted sections from CR method were compared to the results of DC monitoring data. The area which was identified by 4D DC monitoring as the region where the cement mortar was injected and infiltrated were well matched the anomalous area shown in the phase section of CR method. Resistivity change was not clear with the injection of cement mortar, but phase change was clearly noticeable in the inverted section. From this, we hoped that CR method could provide a way of the quantitative estimation of ground improvement.

  6. Skin microvascular flow during hypobaric exposure with and without a mechanical counter-pressure space suit glove

    NASA Technical Reports Server (NTRS)

    Tanaka, Kunihiko; Waldie, James; Steinbach, Gregory C.; Webb, Paul; Tourbier, Dietmar; Knudsen, Jeffrey; Jarvis, Christine W.; Hargens, Alan R.

    2002-01-01

    INTRODUCTION: Current space suits are rigid, gas-pressurized shells that protect astronauts from the vacuum of space. A tight elastic garment or mechanical-counter-pressure (MCP) suit generates pressure by compression and may have several advantages over current space suit technology. In this study, we investigated local microcirculatory effects produced with and without a prototype MCP glove. METHODS: The right hand of eight normal volunteers was studied at normal ambient pressure and during exposure to -50, -100 and -150 mm Hg with and without the MCP glove. Measurements included the pressure against the hand, skin microvascular flow, temperature on the dorsum of the hand, and middle finger girth. RESULTS: Without the glove, skin microvascular flow and finger girth significantly increased with negative pressure, and the skin temperature decreased compared with the control condition. The MCP glove generated approximately 200 mm Hg at the skin surface; all measured values remained at control levels during exposure to negative pressure. DISCUSSION: Without the glove, skin microvascular flow and finger girth increased with negative pressure, probably due to a blood shift toward the hand. The elastic compression of the material of the MCP glove generated pressure on the hand similar to that in current gas-pressurized space suit gloves. The MCP glove prevented the apparent blood shift and thus maintained baseline values of the measured variables despite exposure of the hand to negative pressure.

  7. [Quantification and monitoring of vascular resistance in the lower limbs by the Doppler method (animal model)

    NASA Technical Reports Server (NTRS)

    Arbeille, P.; Berson, M.; Blondeau, B.; Durand, A.; Bodard, S.; Locatelli, A.; Fox, G. E. (Principal Investigator)

    1995-01-01

    The object of this study was to define and validate a non-invasive method of evaluation and monitoring of vascular resistances in the leg. Blood flow velocity was measured by Doppler ultrasound in an animal model (ewe) with similar blood flow characteristics in the lower limb as man and allowing access to the required invasive measurements for validation of the method (pressure and flow). Vascular resistances distal to the measuring point (femoral, for example) were assessed using the resistance index R = D/S, S being the peak systolic deflection and D that of diastolic reflux of the Doppler spectral analysis of flow in the femoral artery. The values and variations of this resistance index were compared with the vascular resistances calculated from measurements of pressure and flow at the point of Doppler sampling and expressed in mmHg/ml/min. Femoral flow was measured by Doppler ultrasound (Doppler-echo), and mean pressure by an arterial catheter introduced into the abdominal aorta. Compression of the lower limb veins induced a venous return resulting in a reduction of cardiac output and femoral flow. During compression, femoral flow decreased by an average of 29% (p < 0.001) although mean pressure and heart rate did not change significantly. The femoral resistance index (Rf) increased by an average of 37.5% (p < 0.01) and vascular resistances increased by 45.9% (p < 0.01). Injection of 1 mg adrenaline induced peripheral vasoconstriction with an increase in blood pressure and a decrease in heart rate and femoral flow.(ABSTRACT TRUNCATED AT 250 WORDS).

  8. Imaging geological contact utilizing 2D resistivity method for light rail transit (LRT) track alignment

    NASA Astrophysics Data System (ADS)

    Ali, Nisa'; Saad, Rosli; Muztaza, Nordiana M.; Ismail, Noer E. H.

    2013-05-01

    The purpose of this study was to locate the geological contact using 2D resistivity method for Light Rail Transit (LRT) track alignment. The resistivity method was conducted on eight survey lines with the length of line 1 was 600m. The length of line 2, 3, 4, 5, 6, and 7 were 200m each while line 8 is 115m. All the survey used minimum electrode spacing of 5m and using Pole-dipole array with minimum current is 2mA and maximum was 20mA. The result obtained from the pseudosection showed that the area generally divided into three main zones, fill materials/residual soil with a resistivity value of <500 Ωm, saturated zone with a resistivity value of 30-100 Ωm and bedrock with a resistivity value of >2000 Ωm. Three fractured zones were detected along line L1 and a lot of boulders were detected at L1, L3, L4, L5 and L6. The geological contact was between the residual soil and granite bedrock.

  9. Alkaline resistant phosphate glasses and method of preparation and use thereof

    DOEpatents

    Brow, Richard K.; Reis, Signo T.; Velez, Mariano; Day, Delbert E.

    2010-01-26

    A substantially alkaline resistant calcium-iron-phosphate (CFP) glass and methods of making and using thereof. In one application, the CFP glass is drawn into a fiber and dispersed in cement to produce glass fiber reinforced concrete (GFRC) articles having the high compressive strength of concrete with the high impact, flexural and tensile strength associated with glass fibers.

  10. Method and device with adjustable focusing for measuring the electric resistivity of geological formations

    SciTech Connect

    Desbrandes, R.

    1983-10-25

    The method of the invention comprises determining the variation of the electric potential on both sides of a central electrode in a borehole, detecting the two levels of the borehole where the potential gradient is zero, and measuring the electric resistivity of the geological formation between these two levels.

  11. DELINEATION OF SUBSURFACE HYDROCARBON CONTAMINANT DISTRIBUTION USING A DIRECT PUSH RESISTIVITY METHOD

    EPA Science Inventory

    A direct push resistivity method was evaluated as a complementary screening tool to provide rapid in-situ contaminant detection to aid in better defining locations for drilling, sampling, and monitoring well installation at hazardous waste sites. Nine continuous direct push resi...

  12. Measurement of the resistivity of porous materials with an alternating air-flow method.

    PubMed

    Dragonetti, Raffaele; Ianniello, Carmine; Romano, Rosario A

    2011-02-01

    Air-flow resistivity is a main parameter governing the acoustic behavior of porous materials for sound absorption. The international standard ISO 9053 specifies two different methods to measure the air-flow resistivity, namely a steady-state air-flow method and an alternating air-flow method. The latter is realized by the measurement of the sound pressure at 2 Hz in a small rigid volume closed partially by the test sample. This cavity is excited with a known volume-velocity sound source implemented often with a motor-driven piston oscillating with prescribed area and displacement magnitude. Measurements at 2 Hz require special instrumentation and care. The authors suggest an alternating air-flow method based on the ratio of sound pressures measured at frequencies higher than 2 Hz inside two cavities coupled through a conventional loudspeaker. The basic method showed that the imaginary part of the sound pressure ratio is useful for the evaluation of the air-flow resistance. Criteria are discussed about the choice of a frequency range suitable to perform simplified calculations with respect to the basic method. These criteria depend on the sample thickness, its nonacoustic parameters, and the measurement apparatus as well. The proposed measurement method was tested successfully with various types of acoustic materials.

  13. Method for estimating crack-extension resistance curve from residual strength data

    NASA Technical Reports Server (NTRS)

    Orange, T. W.

    1980-01-01

    A method is presented for estimating the crack extension resistance curve (R curve) from residual strength (maximum load against initial crack length) data for precracked fracture specimens. The method allows additional information to be inferred from simple test results, and that information is used to estimate the failure loads of more complicated structures. Numerical differentiation of the residual strength data is required, and the problems that it may present are discussed.

  14. A new method to induce molecular low bias negative differential resistance with multi-peaks.

    PubMed

    Min, Y; Zhong, C G; Dong, Z C; Zhao, Z Y; Zhou, P X; Yao, K L

    2016-02-14

    According to a first-principles study of the transport properties of two thiolated anthracene-9,10-diono molecules sandwiching ethyl, a new method to induce molecular low bias negative differential resistance with multi-peaks for strong n- or p-type molecules is proposed. The anthracene-9,10-diono molecule shows strong n-type characteristics when in contact with Au and Ag electrodes via a thiolate. The multiple negative differential resistance effect originated from the molecule-electrode couple is different between Ag and Au electrodes. Our investigations may promise potential for applications in molecular devices with low power dissipation and multifunction in the future.

  15. Methods for developing jam-resistant security communications networks at fixed-site facilities

    NASA Astrophysics Data System (ADS)

    Gangel, D. J.; Heustess, J. E.; Snell, M. K.

    Considerable work has been done identifying and developing equipment and procedures that can be used to improve the survivability of a security communications network during a jamming assault. Insight is given into alternate communications methods that can be used to develop resistance to jamming by supplementing existing radio communications. The spatial properties of jamming are then discussed and examples of how these properties can be exploited are examined. Also discussed are spread-spectrum radios that are highly resistant to jamming and the importance of jamming exercises.

  16. Methods for developing jam-resistant security communications networks at fixed-site facilities

    NASA Astrophysics Data System (ADS)

    Gangel, D. J.; Heustess, J. E.; Snell, M. K.

    Considerable work has been done identifying and developing equipment and procedures that can be used to improve the survivability of a security communications network during a jamming assault. Insight is given into alternate communications methods that can be used to develop resistance to jamming by supplementing existing radio communications. The spatial properties of jamming are then discussed and examples of how these properties can be explocited are examined. Also discussed are spread-spectrum radios that are highly resistant to jamming and the importance of jamming exercises.

  17. Counterfeit-resistant materials and a method and apparatus for authenticating materials

    SciTech Connect

    Ramsey, J.M.; Klatt, L.N.

    2000-03-14

    Fluorescent dichroic fibers randomly incorporated within a media provide an improved method for authentication and counterfeiting protection. The dichroism is provided by an alignment of fluorescent molecules along the length of the fibers. The fluorescent fibers provide an authentication mechanism of varying levels of capability. The authentication signature depends on four parameters; the x,y position, the dichroism and the local environment. The availability of so many non-deterministic variables makes production of counterfeit articles (e.g., currency, credit cards, etc.) essentially impossible. Counterfeit-resistant articles, an apparatus for authenticating articles, and a process for forming counterfeit-resistant media are also provided.

  18. Counterfeit-resistant materials and a method and apparatus for authenticating materials

    DOEpatents

    Ramsey, J. Michael; Klatt, Leon N.

    2000-01-01

    Fluorescent dichroic fibers randomly incorporated within a media provide an improved method for authentication and counterfeiting protection. The dichroism is provided by an alignment of fluorescent molecules along the length of the fibers. The fluorescent fibers provide an authentication mechanism of varying levels of capability. The authentication signature depends on four parameters; the x,y position, the dichroism and the local environment. The availability of so many non-deterministic variables makes production of counterfeit articles (e.g., currency, credit cards, etc.) essentially impossible. Counterfeit-resistant articles, an apparatus for authenticating articles, and a process for forming counterfeit-resistant media are also provided.

  19. Counterfeit-resistant materials and a method and apparatus for authenticating materials

    DOEpatents

    Ramsey, J. Michael; Klatt, Leon N.

    2001-01-01

    Fluorescent dichroic fibers randomly incorporated within a media provide an improved method for authentication and counterfeiting protection. The dichroism is provided by an alignment of fluorescent molecules along the length of the fibers. The fluorescent fibers provide an authentication mechanism of varying levels of capability. The authentication signature depends on four parameters, the x,y position, the dichroism and the local environment. The availability of so many non-deterministic variables makes production of counterfeit articles (e.g., currency, credit cards, etc.) essentially impossible Counterfeit-resistant articles, an apparatus for authenticating articles, and a process for forming counterfeit-resistant media are also provided&

  20. Methods for developing jam-resistant security communications networks at fixed-site facilities

    SciTech Connect

    Gangel, D.J.; Heustess, J.E.; Snell, M.K.

    1985-01-01

    Considerable work has been done identifying and developing equipment and procedures that can be used to improve the survivability of a security communications network during a jamming assault. Insight is given into alternate communications methods that can be used to develop resistance to jamming by supplementing existing radio communications. The spatial properties of jamming are then discussed and examples of how these properties can be exploited are examined. Also discussed are spread-spectrum radios that are highly resistant to jamming and the importance of jamming exercises.

  1. Methods for developing jam-resistant security communications networks at fixed-site facilities

    SciTech Connect

    Gangel, D.J.; Heustess, J.E.; Snell, M.K.

    1986-01-01

    Considerable work has been done identifying and developing equipment and procedures that can be used to improve the survivability of a security communications network during a jamming assault. Insight is given into alternate communications methods that can be used to develop resistance to jamming by supplementing existing radio communications. The spatial properties of jamming are then discussed and examples of how these properties can be exploited are examined. Also discussed are spread-spectrum radios that are highly resistant to jamming and the importance of jamming exercises.

  2. Advanced fire-resistant forms of activated carbon and methods of adsorbing and separating gases using same

    DOEpatents

    Xiong, Yongliang; Wang, Yifeng

    2016-04-19

    A method of removing a target gas from a gas stream is disclosed. The method uses advanced, fire-resistant activated carbon compositions having vastly improved fire resistance. Methods for synthesizing the compositions are also provided. The advanced compositions have high gas adsorption capacities and rapid adsorption kinetics (comparable to commercially-available activated carbon), without having any intrinsic fire hazard.

  3. A novel role for epidermal growth factor receptor tyrosine kinase and its downstream endoplasmic reticulum stress in cardiac damage and microvascular dysfunction in type 1 diabetes mellitus.

    PubMed

    Galán, Maria; Kassan, Modar; Choi, Soo-Kyoung; Partyka, Megan; Trebak, Mohamed; Henrion, Daniel; Matrougui, Khalid

    2012-07-01

    Epidermal growth factor receptor tyrosine kinase (EGFRtk) and endoplasmic reticulum (ER) stress are important factors in cardiovascular complications. Understanding whether enhanced EGFRtk activity and ER stress induction are involved in cardiac damage, and microvascular dysfunction in type 1 diabetes mellitus is an important question that has remained unanswered. Cardiac fibrosis and microvascular function were determined in C57BL/6J mice injected with streptozotocin only or in combination with EGFRtk inhibitor (AG1478), ER stress inhibitor (Tudca), or insulin for 2 weeks. In diabetic mice, we observed an increase in EGFRtk phosphorylation and ER stress marker expression (CHOP, ATF4, ATF6, and phosphorylated-eIF2α) in heart and mesenteric resistance arteries, which were reduced with AG1478, Tudca, and insulin. Cardiac fibrosis, enhanced collagen type I, and plasminogen activator inhibitor 1 were decreased with AG1478, Tudca, and insulin treatments. The impaired endothelium-dependent relaxation and -independent relaxation responses were also restored after treatments. The inhibition of NO synthesis reduced endothelium-dependent relaxation in control and treated streptozotocin mice, whereas the inhibition of NADPH oxidase improved endothelium-dependent relaxation only in streptozotocin mice. Moreover, in mesenteric resistance arteries, the mRNA levels of Nox2 and Nox4 and the NADPH oxidase activity were augmented in streptozotocin mice and reduced with treatments. This study unveiled novel roles for enhanced EGFRtk phosphorylation and its downstream ER stress in cardiac fibrosis and microvascular endothelial dysfunction in type 1 diabetes mellitus.

  4. RNA-seq analysis of transcriptomes in thrombin-treated and control human pulmonary microvascular endothelial cells.

    PubMed

    Cheranova, Dilyara; Gibson, Margaret; Chaudhary, Suman; Zhang, Li Qin; Heruth, Daniel P; Grigoryev, Dmitry N; Ye, Shui Qing

    2013-01-01

    The characterization of gene expression in cells via measurement of mRNA levels is a useful tool in determining how the transcriptional machinery of the cell is affected by external signals (e.g. drug treatment), or how cells differ between a healthy state and a diseased state. With the advent and continuous refinement of next-generation DNA sequencing technology, RNA-sequencing (RNA-seq) has become an increasingly popular method of transcriptome analysis to catalog all species of transcripts, to determine the transcriptional structure of all expressed genes and to quantify the changing expression levels of the total set of transcripts in a given cell, tissue or organism. RNA-seq is gradually replacing DNA microarrays as a preferred method for transcriptome analysis because it has the advantages of profiling a complete transcriptome, providing a digital type datum (copy number of any transcript) and not relying on any known genomic sequence. Here, we present a complete and detailed protocol to apply RNA-seq to profile transcriptomes in human pulmonary microvascular endothelial cells with or without thrombin treatment. This protocol is based on our recent published study entitled "RNA-seq Reveals Novel Transcriptome of Genes and Their Isoforms in Human Pulmonary Microvascular Endothelial Cells Treated with Thrombin," in which we successfully performed the first complete transcriptome analysis of human pulmonary microvascular endothelial cells treated with thrombin using RNA-seq. It yielded unprecedented resources for further experimentation to gain insights into molecular mechanisms underlying thrombin-mediated endothelial dysfunction in the pathogenesis of inflammatory conditions, cancer, diabetes, and coronary heart disease, and provides potential new leads for therapeutic targets to those diseases. The descriptive text of this protocol is divided into four parts. The first part describes the treatment of human pulmonary microvascular endothelial cells with

  5. RNA-seq analysis of transcriptomes in thrombin-treated and control human pulmonary microvascular endothelial cells.

    PubMed

    Cheranova, Dilyara; Gibson, Margaret; Chaudhary, Suman; Zhang, Li Qin; Heruth, Daniel P; Grigoryev, Dmitry N; Ye, Shui Qing

    2013-02-13

    The characterization of gene expression in cells via measurement of mRNA levels is a useful tool in determining how the transcriptional machinery of the cell is affected by external signals (e.g. drug treatment), or how cells differ between a healthy state and a diseased state. With the advent and continuous refinement of next-generation DNA sequencing technology, RNA-sequencing (RNA-seq) has become an increasingly popular method of transcriptome analysis to catalog all species of transcripts, to determine the transcriptional structure of all expressed genes and to quantify the changing expression levels of the total set of transcripts in a given cell, tissue or organism. RNA-seq is gradually replacing DNA microarrays as a preferred method for transcriptome analysis because it has the advantages of profiling a complete transcriptome, providing a digital type datum (copy number of any transcript) and not relying on any known genomic sequence. Here, we present a complete and detailed protocol to apply RNA-seq to profile transcriptomes in human pulmonary microvascular endothelial cells with or without thrombin treatment. This protocol is based on our recent published study entitled "RNA-seq Reveals Novel Transcriptome of Genes and Their Isoforms in Human Pulmonary Microvascular Endothelial Cells Treated with Thrombin," in which we successfully performed the first complete transcriptome analysis of human pulmonary microvascular endothelial cells treated with thrombin using RNA-seq. It yielded unprecedented resources for further experimentation to gain insights into molecular mechanisms underlying thrombin-mediated endothelial dysfunction in the pathogenesis of inflammatory conditions, cancer, diabetes, and coronary heart disease, and provides potential new leads for therapeutic targets to those diseases. The descriptive text of this protocol is divided into four parts. The first part describes the treatment of human pulmonary microvascular endothelial cells with

  6. Oxidation resistant nanocrystalline MCrAl(Y) coatings and methods of forming such coatings

    DOEpatents

    Cheruvu, Narayana S.; Wei, Ronghua

    2014-07-29

    The present disclosure relates to an oxidation resistant nanocrystalline coating and a method of forming an oxidation resistant nanocrystalline coating. An oxidation resistant coating comprising an MCrAl(Y) alloy may be deposited on a substrate, wherein M, includes iron, nickel, cobalt, or combinations thereof present greater than 50 wt % of the MCrAl(Y) alloy, chromium is present in the range of 15 wt % to 30 wt % of the MCrAl(Y) alloy, aluminum is present in the range of 6 wt % to 12 wt % of the MCrAl(Y) alloy and yttrium, is optionally present in the range of 0.1 wt % to 0.5 wt % of the MCrAl(Y) alloy. In addition, the coating may exhibit a grain size of 200 nm or less as deposited.

  7. Development and field evaluation of a method for detecting carbapenem-resistant bacteria in drinking water.

    PubMed

    Tanner, Windy D; VanDerslice, James A; Toor, Devinder; Benson, L Scott; Porucznik, Christina A; Goel, Ramesh K; Atkinson, Robyn M

    2015-07-01

    In this study, a fluorogenic heterotrophic plate count test for drinking water was modified in order to detect the presence of carbapenem-resistant bacteria. Antimicrobial agents and concentrations were selected based on recoveries of known carbapenem-resistant and carbapenem-susceptible strains inoculated into simulated samples. The modified method was field-tested on 19 drinking water samples from the New Delhi, India distribution system. Samples exhibiting fluorescence indicated bacterial growth in the presence of the supplemented antimicrobial agents, and organisms from these samples were cultured. Twenty-one Gram-negative isolates were identified from nine of the 19 samples and the meropenem minimum inhibitory concentrations were determined. Ultimately, eight carbapenem-resistant organisms were isolated from five sampling sites within the New Delhi water distribution system.

  8. Establishment of a nested-ASP-PCR method to determine the clarithromycin resistance of Helicobacter pylori

    PubMed Central

    Luo, Xiao-Feng; Jiao, Jian-Hua; Zhang, Wen-Yue; Pu, Han-Ming; Qu, Bao-Jin; Yang, Bing-Ya; Hou, Min; Ji, Min-Jun

    2016-01-01

    AIM: To investigate clarithromycin resistance positions 2142, 2143 and 2144 of the 23SrRNA gene in Helicobacter pylori (H. pylori) by nested-allele specific primer-polymerase chain reaction (nested-ASP-PCR). METHODS: The gastric tissue and saliva samples from 99 patients with positive results of the rapid urease test (RUT) were collected. The nested-ASP-PCR method was carried out with the external primers and inner allele-specific primers corresponding to the reference strain and clinical strains. Thirty gastric tissue and saliva samples were tested to determine the sensitivity of nested-ASP-PCR and ASP-PCR methods. Then, clarithromycin resistance was detected for 99 clinical samples by using different methods, including nested-ASP-PCR, bacterial culture and disk diffusion. RESULTS: The nested-ASP-PCR method was successfully established to test the resistance mutation points 2142, 2143 and 2144 of the 23SrRNA gene of H. pylori. Among 30 samples of gastric tissue and saliva, the H. pylori detection rate of nested-ASP-PCR was 90% and 83.33%, while the detection rate of ASP-PCR was just 63% and 56.67%. Especially in the saliva samples, nested-ASP-PCR showed much higher sensitivity in H. pylori detection and resistance mutation rates than ASP-PCR. In the 99 RUT-positive gastric tissue and saliva samples, the H. pylori-positive detection rate by nested-ASP-PCR was 87 (87.88%) and 67 (67.68%), in which there were 30 wild-type and 57 mutated strains in gastric tissue and 22 wild-type and 45 mutated strains in saliva. Genotype analysis showed that three-points mixed mutations were quite common, but different resistant strains were present in gastric mucosa and saliva. Compared to the high sensitivity shown by nested-ASP-PCR, the positive detection of bacterial culture with gastric tissue samples was 50 cases, in which only 26 drug-resistant strains were found through analyzing minimum inhibitory zone of clarithromycin. CONCLUSION: The nested-ASP-PCR assay showed higher

  9. Cable Crosstalk Suppression with Two-Wire Voltage Feedback Method for Resistive Sensor Array.

    PubMed

    Wu, Jianfeng; He, Shangshang; Li, Jianqing; Song, Aiguo

    2016-01-01

    Using a long, flexible test cable connected with a one-wire voltage feedback circuit, a resistive tactile sensor in a shared row-column fashion exhibited flexibility in robotic operations but suffered from crosstalk caused by the connected cable due to its wire resistances and its contacted resistances. Firstly, we designed a new non-scanned driving-electrode (VF-NSDE) circuit using two wires for every row line and every column line to reduce the crosstalk caused by the connected cables in the circuit. Then, an equivalent resistance expression of the element being tested (EBT) for the two-wire VF-NSDE circuit was analytically derived. Following this, the one-wire VF-NSDE circuit and the two-wire VF-NSDE circuit were evaluated by simulation experiments. Finally, positive features of the proposed method were verified with the experiments of a two-wire VF-NSDE prototype circuit. The experiment results show that the two-wire VF-NSDE circuit can greatly reduce the crosstalk error caused by the cables in the 2-D networked resistive sensor array.

  10. Corrosion Resistance Analysis of Sintered NdFeB Magnets Using Ultrasonic-Aided EDM Method

    NASA Astrophysics Data System (ADS)

    Li, L.; Wei, X. T.; Li, Z. Y.; Cheng, X.

    2015-01-01

    Sintered neodymium-iron-boron (NdFeB) permanent magnets are widely used in many fields because of their excellent magnetic property. However, their poor corrosion resistance has been cited as a potential problem that limits their extensive application. This paper presents an experimental investigation into the improvement of surface corrosion resistance with the ultrasonic-aided electrical discharge machining (U-EDM) method. A scanning electron microscope was used to analyze the surface morphology of recast layers formed through the EDM and U-EDM processes. The chemical structure and elements of these recast layers were characterized using x-ray diffraction and energy dispersive spectroscopy. Corrosion resistance was also studied by means of potentiodynamic polarization, electrochemical impedance spectroscopy, and immersion tests in 0.5 mol/L H2SO4 solution. Experimental results show that an amorphous structure was formed in the recast layer during the EDM and U-EDM processes and that this structure could improve the corrosion resistance of sintered NdFeB magnets. Moreover, the corrosion resistance of U-EDM-treated surface was better than that of the EDM-treated surface.

  11. Sampling and Pooling Methods for Capturing Herd Level Antibiotic Resistance in Swine Feces using qPCR and CFU Approaches

    PubMed Central

    Mellerup, Anders; Ståhl, Marie

    2015-01-01

    The aim of this article was to define the sampling level and method combination that captures antibiotic resistance at pig herd level utilizing qPCR antibiotic resistance gene quantification and culture-based quantification of antibiotic resistant coliform indicator bacteria. Fourteen qPCR assays for commonly detected antibiotic resistance genes were developed, and used to quantify antibiotic resistance genes in total DNA from swine fecal samples that were obtained using different sampling and pooling methods. In parallel, the number of antibiotic resistant coliform indicator bacteria was determined in the same swine fecal samples. The results showed that the qPCR assays were capable of detecting differences in antibiotic resistance levels in individual animals that the coliform bacteria colony forming units (CFU) could not. Also, the qPCR assays more accurately quantified antibiotic resistance genes when comparing individual sampling and pooling methods. qPCR on pooled samples was found to be a good representative for the general resistance level in a pig herd compared to the coliform CFU counts. It had significantly reduced relative standard deviations compared to coliform CFU counts in the same samples, and therefore differences in antibiotic resistance levels between samples were more readily detected. To our knowledge, this is the first study to describe sampling and pooling methods for qPCR quantification of antibiotic resistance genes in total DNA extracted from swine feces. PMID:26114765

  12. Sampling and Pooling Methods for Capturing Herd Level Antibiotic Resistance in Swine Feces using qPCR and CFU Approaches.

    PubMed

    Schmidt, Gunilla Veslemøy; Mellerup, Anders; Christiansen, Lasse Engbo; Ståhl, Marie; Olsen, John Elmerdahl; Angen, Øystein

    2015-01-01

    The aim of this article was to define the sampling level and method combination that captures antibiotic resistance at pig herd level utilizing qPCR antibiotic resistance gene quantification and culture-based quantification of antibiotic resistant coliform indicator bacteria. Fourteen qPCR assays for commonly detected antibiotic resistance genes were developed, and used to quantify antibiotic resistance genes in total DNA from swine fecal samples that were obtained using different sampling and pooling methods. In parallel, the number of antibiotic resistant coliform indicator bacteria was determined in the same swine fecal samples. The results showed that the qPCR assays were capable of detecting differences in antibiotic resistance levels in individual animals that the coliform bacteria colony forming units (CFU) could not. Also, the qPCR assays more accurately quantified antibiotic resistance genes when comparing individual sampling and pooling methods. qPCR on pooled samples was found to be a good representative for the general resistance level in a pig herd compared to the coliform CFU counts. It had significantly reduced relative standard deviations compared to coliform CFU counts in the same samples, and therefore differences in antibiotic resistance levels between samples were more readily detected. To our knowledge, this is the first study to describe sampling and pooling methods for qPCR quantification of antibiotic resistance genes in total DNA extracted from swine feces.

  13. Remote sensing of freeze-thaw transitions in Arctic soils using the complex resistivity method

    SciTech Connect

    Wu, Yuxin; Hubbard, Susan S; Ulrich, Craig; Wullschleger, Stan D

    2013-01-01

    Our ability to monitor freeze - thaw transitions is critical to developing a predictive understanding of biogeochemical transitions and carbon dynamics in high latitude environments. In this study, we conducted laboratory column experiments to explore the potential of the complex resistivity method for monitoring the freeze - thaw transitions of the arctic permafrost soils. Samples for the experiment were collected from the upper active layer of Gelisol soils at the Barrow Environmental Observatory, Barrow Alaska. Freeze - thaw transitions were induced through exposing the soil column to controlled temperature environments at 4 C and -20 C. Complex resistivity and temperature measurements were collected regularly during the freeze - thaw transitions using electrodes and temperature sensors installed along the column. During the experiments, over two orders of magnitude of resistivity variations were observed when the temperature was increased or decreased between -20 C and 0 C. Smaller resistivity variations were also observed during the isothermal thawing or freezing processes that occurred near 0 C. Single frequency electrical phase response and imaginary conductivity at 1 Hz were found to be exclusively related to the unfrozen water in the soil matrix, suggesting that these geophysical 24 attributes can be used as a proxy for the monitoring of the onset and progression of the freeze - thaw transitions. Spectral electrical responses and fitted Cole Cole parameters contained additional information about the freeze - thaw transition affected by the soil grain size distribution. Specifically, a shift of the observed spectral response to lower frequency was observed during isothermal thawing process, which we interpret to be due to sequential thawing, first from fine then to coarse particles within the soil matrix. Our study demonstrates the potential of the complex resistivity method for remote monitoring of freeze - thaw transitions in arctic soils. Although

  14. Determination of natural resistance frequencies in Penicillium digitatum using a new air-sampling method and characterization of fludioxonil- and pyrimethanil-resistant isolates.

    PubMed

    Kanetis, L; Förster, H; Adaskaveg, J E

    2010-08-01

    ABSTRACT Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use. Using a new air-sampling method where large populations of the pathogen in citrus packinghouses were exposed to agar plates with a continuous, wide-range fungicide concentration gradient, isolates with reduced sensitivity to fludioxonil or pyrimethanil were obtained. Resistance frequencies to fludioxonil and pyrimethanil were calculated as 9.5 x 10(-7) to 1.5 x 10(-5) and 7.3 x 10(-6) to 6.2 x 10(-5), respectively. No isolates resistant to azoxystrobin were detected. Isolates with reduced sensitivity to fludioxonil or pyrimethanil were also obtained in laboratory selection studies, where high concentrations of conidial mixtures of isolates sensitive to the three fungicides were plated onto agar amended with each fungicide at 10 microg/ml. Isolates obtained from fludioxonil selection plates in laboratory and packinghouse experiments were placed into two categories based on mycelial growth: moderately resistant isolates had 50% effective concentration (EC(50)) values of 0.1 to 0.82 microg/ml and highly resistant isolates had EC(50) values > 1.5 microg/ml. Isolates resistant to pyrimethanil all had EC(50) values >8 microg/ml. Representative isolates of the two categories with reduced sensitivity to fludioxonil varied widely in their virulence and sporulation capacity as measured by the incidence of decay and degree of sporulation on inoculated fruit, respectively, whereas pyrimethanil-resistant isolates were mostly similar to the wild-type isolate. Fungicide sensitivity characteristics for isolates from fludioxonil and pyrimethanil selection plates remained stable after passages on nonamended agar, and disease could not be controlled after treatment with the respective fungicides. Types of fungicide resistance were visualized on thiabendazole- (TBZ) and imazalil

  15. Correction of the heat loss method for calculating clothing real evaporative resistance.

    PubMed

    Wang, Faming; Zhang, Chengjiao; Lu, Yehu

    2015-08-01

    In the so-called isothermal condition (i.e., Tair [air temperature]=Tmanikin [manikin temperature]=Tr [radiant temperature]), the actual energy used for moisture evaporation detected by most sweating manikins was underestimated due to the uncontrolled fabric 'skin' temperature Tsk,f (i.e., Tsk,fresistance. In this study, correction of the real evaporative heat loss from the wet fabric 'skin'-clothing system was proposed and experimentally validated on a 'Newton' sweating manikin. The real evaporative resistance of five clothing ensembles and the nude fabric 'skin' calculated by the corrected heat loss method was also reported and compared with that by the mass loss method. Results revealed that, depending on the types of tested clothing, different amounts of heat were drawn from the ambient environment. In general, a greater amount of heat was drawn from the ambient environment by the wet fabric 'skin'-clothing system in lower thermal insulation clothing than that in higher insulation clothing. There were no significant differences between clothing real evaporative resistances calculated by the corrected heat loss method and those by the mass loss method. It was therefore concluded that the correction method proposed in this study has been successfully validated. PMID:26267497

  16. [Comparison of chosen methods for identification of methicillin-resistant Staphylococcus aureus].

    PubMed

    Kaczmarek, Agnieszka; Budzyńska, Anna; Gospodarek, Eugenia

    2009-01-01

    The aim of this study was to estimate effectiveness of methicillin-resistant S. aureus identification using screening method with oxacillin (6 microg/ml), latex agglutination test--Slidex MRSA Detection and a chromogenic agar medium--MRSA ID. The investigation were carried out on 120 S. aureus strains isolated from clinical materials of patients hospitalized in the University Hospital at the L. Rydygier Collegium Medicum in Bydgoszcz, University of Nicolaus Copernicus in Torún. Consistency of results between chromogenic medium and latex agglutination test amounted 97.5%, chromogenic medium and screening method--96.7%. Identical correspondence of results took a stand in case screening method and latex agglutination test. Results consistency of detecting methicillin resistance in S. aureus strains between this three methods concerned 95.8% strains. Our investigation demonstrated 96.7% sensitivity and 100% specificity for MRSA ID medium for the detection of methicillin resistance. The sensitivity of MRSA-Screen was 95.0% and its specificity reached 100%. The sensitivity and specificity of screening method amounted 96.7%.

  17. Apparatus and method for in-situ cleaning of resist outgassing windows

    DOEpatents

    Klebanoff, Leonard E.; Haney, Steven J.

    2001-01-01

    An apparatus and method for in-situ cleaning of resist outgassing windows. The apparatus includes a chamber located in a structure, with the chamber having an outgassing window to be cleaned positioned in alignment with a slot in the chamber, whereby radiation energy passes through the window, the chamber, and the slot onto a resist-coated wafer mounted in the structure. The chamber is connected to a gas supply and the structure is connected to a vacuum pump. Within the chamber are two cylindrical sector electrodes and a filament is electrically connected to one sector electrode and a power supply. In a first cleaning method the sector electrodes are maintained at the same voltage, the filament is unheated, the chamber is filled with argon (Ar) gas under pressure, and the window is maintained at a zero voltage, whereby Ar ions are accelerated onto the window surface, sputtering away carbon deposits that build up as a result of resist outgassing. A second cleaning method is similar except oxygen gas (O.sub.2) is admitted to the chamber instead of Ar. These two methods can be carried out during lithographic operation. A third method, carried out during a maintenance period, involves admitting CO.sub.2 into the chamber, heating the filament to a point of thermionic emission, the sector electrodes are at different voltages, excited CO.sub.2 gas molecules are created which impact the carbon contamination on the window, and gasify it, producing CO gaseous products that are pumped away.

  18. Dietary nitrite prevents hypercholesterolemic microvascular inflammation and reverses endothelial dysfunction.

    PubMed

    Stokes, Karen Y; Dugas, Tammy R; Tang, Yaoping; Garg, Harsha; Guidry, Eric; Bryan, Nathan S

    2009-05-01

    The nitrite anion is an endogenous product of mammalian nitric oxide (NO) metabolism, a key intermediate in the nitrogen cycle in plants, and a constituent of many foods. Research over the past 6 years has revealed surprising biological and cytoprotective activity of this anion. Hypercholesterolemia causes a proinflammatory phenotype in the microcirculation. This phenotype appears to result from a decline in NO bioavailability that results from a reduction in NO biosynthesis, inactivation of NO by superoxide, or both. Since nitrite has been shown to be potently cytoprotective and restore NO biochemical homeostasis, we investigated if supplemental nitrite could attenuate microvascular inflammation caused by a high cholesterol diet. C57Bl/6J mice were fed either a normal diet or a high cholesterol diet for 3 wk to induce microvascular inflammation. Mice on the high cholesterol diet received either nitrite-free drinking water or supplemental nitrite at 33 or 99 mg/l ad libitum in their drinking water. The results from this investigation reveal that mice fed a cholesterol-enriched diet exhibited significantly elevated leukocyte adhesion to and emigration through the venular endothelium as well as impaired endothelium-dependent relaxation in arterioles. Administration of nitrite in the drinking water inhibited the leukocyte adhesion and emigration and prevented the arteriolar dysfunction. This was associated with sparing of reduced tetrahydrobiopterin and decreased levels of C-reactive protein. These data reveal novel anti-inflammatory properties of nitrite and implicate the use of nitrite as a new natural therapy for microvascular inflammation and endothelial dysfunction associated with hypercholesterolemia.

  19. Reduced toxicity polyester resins and microvascular pre-preg tapes for advanced composites manufacturing

    NASA Astrophysics Data System (ADS)

    Poillucci, Richard

    Advanced composites manufacturing broadly encapsulates topics ranging from matrix chemistries to automated machines that lay-up fiber-reinforced materials. Environmental regulations are stimulating research to reduce matrix resin formulation toxicity. At present, composites fabricated with polyester resins expose workers to the risk of contact with and inhalation of styrene monomer, which is a potential carcinogen, neurotoxin, and respiratory irritant. The first primary goal of this thesis is to reduce the toxicity associated with polyester resins by: (1) identification of potential monomers to replace styrene, (2) determination of monomer solubility within the polyester, and (3) investigation of approaches to rapidly screen a large resin composition parameter space. Monomers are identified based on their ability to react with polyester and their toxicity as determined by the Globally Harmonized System (GHS) and a green screen method. Solubilities were determined by the Hoftyzer -- Van Krevelen method, Hansen solubility parameter database, and experimental mixing of monomers. A combinatorial microfluidic mixing device is designed and tested to obtain distinct resin compositions from two input chemistries. The push for safer materials is complemented by a thrust for multifunctional composites. The second primary goal of this thesis is to design and implement the manufacture of sacrificial fiber materials suitable for use in automated fiber placement of microvascaular multifunctional composites. Two key advancements are required to achieve this goal: (1) development of a roll-to-roll method to place sacrificial fibers onto carbon fiber pre-preg tape; and (2) demonstration of feasible manufacture of microvascular carbon fiber plates with automated fiber placement. An automated method for placing sacrificial fibers onto carbon fiber tapes is designed and a prototype implemented. Carbon fiber tows with manual placement of sacrificial fibers is implemented within an

  20. Effect of subchronic in vivo exposure to nitrogen dioxide on lung tissue inflammation, airway microvascular leakage, and in vitro bronchial muscle responsiveness in rats.

    PubMed Central

    Chitano, P; Rado, V; Di Stefano, A; Papi, A; Boniotti, A; Zancuoghi, G; Boschetto, P; Romano, M; Salmona, M; Ciaccia, A; Fabbri, L M; Mapp, C E

    1996-01-01

    OBJECTIVES: In a previous study on bronchoalveolar lavage fluid from rats exposed in vivo for seven days to 10 ppm nitrogen dioxide (NO2), it has been shown that there is an influx of macrophages into the airways. The present study investigated the effect of seven day exposure to 10 ppm NO2, on: (a) lung tissue inflammation and morphology; (b) airway microvascular leakage; (c) in vitro contractile response of main bronchi. METHODS: Lung tissue was studied by light microscopy, after fixing the lungs by inflation with 4% formalin at a pressure of 20 cm H2O. Microvascular leakage was measured by extravasation of Evans blue dye in the larynx, trachea, main bronchi, and intrapulmonary airways. Smooth muscle responsiveness was evaluated by concentration-responses curves to acetylcholine (10(-9)-10(-3) M), serotonin (10(-9)-10(-4) M), and voltage-response curves (12-28 V) to electrical field stimulation. RESULTS: Histology showed an increased total inflammation at the level of respiratory bronchioles and alveoli. No influx of inflammatory cells was found in the main bronchi. A loss of cilia in the epithelium of small airways and ectasia of alveolar capillaries was also found. By contrast, no alterations to microvascular permeability or modification of bronchial smooth muscle responsiveness was found. CONCLUSIONS: Subchronic exposure to 10 ppm NO2 causes airway inflammation and structural damage, but does not cause any persistent alteration to microvascular permeability or bronchial smooth muscle responsiveness in rats. Images Figure 1 PMID:8758032

  1. Antiproliferative effect of elevated glucose in human microvascular endothelial cells

    NASA Technical Reports Server (NTRS)

    Kamal, K.; Du, W.; Mills, I.; Sumpio, B. E.

    1998-01-01

    Diabetic microangiopathy has been implicated as a fundamental feature of the pathological complications of diabetes including retinopathy, neuropathy, and diabetic foot ulceration. However, previous studies devoted to examining the deleterious effects of elevated glucose on the endothelium have been performed largely in primary cultured cells of macrovessel origin. Difficulty in the harvesting and maintenance of microvascular endothelial cells in culture have hindered the study of this relevant population. Therefore, the objective of this study was to characterize the effect of elevated glucose on the proliferation and involved signaling pathways of an immortalized human dermal microvascular endothelial cell line (HMEC-1) that possess similar characteristics to their in vivo counterparts. Human dermal microvascular endothelial cells (HMEC-1) were grown in the presence of normal (5 mM) or high D-glucose (20 mM) for 14 days. The proliferative response of HMEC-1 was compared under these conditions as well as the cAMP and PKC pathways by in vitro assays. Elevated glucose significantly inhibited (P < 0.05) HMEC-1 proliferation after 7, 10, and 14 days. This effect was not mimicked by 20 mM mannitol. The antiproliferative effect was more pronounced with longer exposure (1-14 days) to elevated glucose and was irreversible 4 days after a 10-day exposure. The antiproliferative effect was partially reversed in the presence of a PKA inhibitor, Rp-cAMP (10-50 microM), and/or a PKC inhibitor, Calphostin C (10 nM). HMEC-1 exposed to elevated glucose (20 mM) for 14 days caused an increase in cyclic AMP accumulation, PKA, and PKC activity but was not associated with the activation of downstream events such as CRE and AP-1 binding activity. These data support the hypothesis that HMEC-1 is a suitable model to study the deleterious effects of elevated glucose on microvascular endothelial cells. Continued studies with HMEC-1 may prove advantageous in delineation of the molecular

  2. Quantifying Therapeutic and Diagnostic Efficacy in 2D Microvascular Images

    NASA Technical Reports Server (NTRS)

    Parsons-Wingerter, Patricia; Vickerman, Mary B.; Keith, Patricia A.

    2009-01-01

    VESGEN is a newly automated, user-interactive program that maps and quantifies the effects of vascular therapeutics and regulators on microvascular form and function. VESGEN analyzes two-dimensional, black and white vascular images by measuring important vessel morphology parameters. This software guides the user through each required step of the analysis process via a concise graphical user interface (GUI). Primary applications of the VESGEN code are 2D vascular images acquired as clinical diagnostic images of the human retina and as experimental studies of the effects of vascular regulators and therapeutics on vessel remodeling.

  3. Alternative venous outflow vessels in microvascular breast reconstruction.

    PubMed

    Mehrara, Babak J; Santoro, Timothy; Smith, Andrew; Arcilla, Eric A; Watson, James P; Shaw, William W; Da Lio, Andrew L

    2003-08-01

    The lack of adequate recipient vessels often complicates microvascular breast reconstruction in patients who have previously undergone mastectomy and irradiation. In addition, significant size mismatch, particularly in the outflow veins, is an important contributor to vessel thrombosis and flap failure. The purpose of this study was to review the authors' experience with alternative venous outflow vessels for microvascular breast reconstruction. In a retrospective analysis of 1278 microvascular breast reconstructions performed over a 10-year period, the authors identified all patients in whom the external jugular or cephalic veins were used as the outflow vessels. Patient demographics, flap choice, the reasons for the use of alternative venous drainage vessels, and the incidence of microsurgical complications were analyzed. The external jugular was used in 23 flaps performed in procedures with 22 patients. The superior gluteal and transverse rectus abdominis musculocutaneous (TRAM) flaps were used in the majority of the cases in which the external jugular vein was used (72 percent gluteal, 20 percent TRAM flap). The need for alternative venous outflow vessels was usually due to a significant vessel size mismatch between the superior gluteal and internal mammary veins (74 percent). For three of the external jugular vein flaps (13 percent), the vein was used for salvage after the primary draining vein thrombosed, and two of three flaps in these cases were eventually salvaged. In three patients, the external jugular vein thrombosed, resulting in two flap losses, while the third was salvaged using the cephalic vein. A total of two flaps were lost in the external jugular vein group. The cephalic vein was used in 11 flaps (TRAM, 64.3 percent; superior gluteal, 35.7 percent) performed in 11 patients. In five patients (54.5 percent), the cephalic vein was used to salvage a flap after the primary draining vein thrombosed; the procedure was successful in four cases. In three

  4. Microvascular alterations and the role of complement in dermatomyositis.

    PubMed

    Lahoria, Rajat; Selcen, Duygu; Engel, Andrew G

    2016-07-01

    Different mechanisms have been proposed to explain the pathological basis of perifascicular muscle fibre atrophy in dermatomyositis. These include ischaemia due to immune-mediated microvascular injury, enhanced expression of type 1 interferon-induced gene transcripts in perifascicular capillaries and muscle fibres, and occlusion of larger perimysial blood vessels. Microvascular complement deposition is a feature of dermatomyositis pathology but the trigger for complement activation, the predominant complement pathway involved, or its role in the pathogenesis of the disease, has not been clearly defined. In the first step of this study we examined the density of capillaries and transverse vessels and searched for occlusion or depletion of larger perimysial blood vessels in 10 patients with dermatomyositis. This revealed an invariable association of perifascicular atrophy with capillary and transverse vessel depletion. The capillary and transverse vessel densities in non-atrophic fibre regions were not significantly different from those in muscle specimens of 10 age-matched controls. Next, in the same 10, as well as in 40 additional dermatomyositis patients, we searched for vascular deposits of IgG, IgM, and the C5b-9 complement membrane attack complex. Thirty-one of 50 dermatomyositis specimens contained C5b-9 reactive endomysial microvessels but none of these or other vessels reacted for IgG. Ten of 50 specimens harboured IgM-positive capillaries but only a few of these reacted for C5b-9. Finally, we analysed and compared different pathways of complement activation in dermatomyositis, lupus nephritis, and necrotic muscle fibres in Duchenne dystrophy. In lupus nephritis, C5-b9 deposits co-localized with IgG, IgM, C1q, and C4d, consistent with immune complex dependent activation of the classical complement pathway. In both dermatomyositis and Duchenne dystrophy, C5-b9 deposits co-localized with C1q and C4d and rarely with IgM indicating activation of the classical

  5. Method to measure ethylene oxide/propylene oxide surfactants in resist developers

    NASA Astrophysics Data System (ADS)

    Holt, Rodica; Oberlander, Joseph E.; Calindas, Maria Fides Y.; Gonzalez, Eleazar; Ranque, Pilarcita L.

    1998-06-01

    Controlling the exact level of surfactants in resist developers is critical. Surfactant concentrations can influence parameters such as photospeed, resolution, and linearity. Too much or too little surfactant can have a significant impact on the performance of the developer. In our laboratory an analytical procedure was developed to quantitate an Ethylene Oxide/Propylene Oxide (EO/PO) surfactant in an aqueous Tetra Alkyl Ammonium Hydroxide developer. The procedure takes advantage of the chemical property of the EO/PO surfactant to complex with aqueous cobalt thiocyanate solution to form a blue cobalt containing dye. The coupled dye is soluble in methylene chloride and visible at lambda 620 nm. The amount of dye formation is directly proportional to the amount of EO/PO surfactant present in the sample, over an established range. The analytical method provides precise and accurate quantitation of the EO/PO surfactant in the resist developers. It is relatively easy to perform and enables the user to qualify a resist developer with respect to its surfactant content. Also, the method developed is sufficiently general and can be applied to other types of nonionic surfactants presented in resist developers.

  6. Testing for bacterial resistance to arsenic in monitoring well water by the direct viable counting method.

    PubMed

    Zelibor, J L; Doughten, M W; Grimes, D J; Colwell, R R

    1987-12-01

    Direct viable counting of metal-resistant bacteria (DVCMR) has been found to be useful in both enumerating and differentiating metal-resistant and metal-sensitive strains of bacteria. The DVCMR bioassay was used to detect effects of low and high concentrations of arsenic and arsenicals on bacterial populations in groundwater. The level of resistance of the bacterial populations to arsenate was determined by the DVCMR bioassay, and the results showed a linear correlation with the total arsenic concentrations in the monitoring well water samples; no correlation was observed by culture methods with the methods employed. Bacteria resistant to 2,000 micrograms of arsenate per ml were isolated from all monitoring well water samples studied. Strains showed similar antibiotic and heavy-metal profiles, suggesting that the arsenic was not a highly selective pressure for arsenic alone. The monitoring well water samples were amended with arsenate and nutrients to determine the biotransformation mechanisms involved. Preliminary results suggest that bacteria indigenous to the monitoring well water samples did not directly transform, i.e., precipitate or volatilize, dissolved arsenic. It was concluded that arsenic contamination of the groundwater can be monitored by the DVCMR bioassay.

  7. Recursion-transform method for computing resistance of the complex resistor network with three arbitrary boundaries.

    PubMed

    Tan, Zhi-Zhong

    2015-05-01

    We develop a general recursion-transform (R-T) method for a two-dimensional resistor network with a zero resistor boundary. As applications of the R-T method, we consider a significant example to illuminate the usefulness for calculating resistance of a rectangular m×n resistor network with a null resistor and three arbitrary boundaries, a problem never solved before, since Green's function techniques and Laplacian matrix approaches are invalid in this case. Looking for the exact calculation of the resistance of a binary resistor network is important but difficult in the case of an arbitrary boundary since the boundary is like a wall or trap which affects the behavior of finite network. In this paper we obtain several general formulas of resistance between any two nodes in a nonregular m×n resistor network in both finite and infinite cases. In particular, 12 special cases are given by reducing one of the general formulas to understand its applications and meanings, and an integral identity is found when we compare the equivalent resistance of two different structures of the same problem in a resistor network. PMID:26066134

  8. Oxide Defect Engineering Methods for Valence Change (VCM) Resistive Random Access Memories

    NASA Astrophysics Data System (ADS)

    Capulong, Jihan O.

    Electrical switching requirements for resistive random access memory (ReRAM) devices are multifaceted, based on device application. Thus, it is important to obtain an understanding of these switching properties and how they relate to the oxygen vacancy concentration and oxygen vacancy defects. Oxygen vacancy defects in the switching oxide of valence-change-based ReRAM (VCM ReRAM) play a significant role in device switching properties. Oxygen vacancies facilitate resistive switching as they form the conductive filament that changes the resistance state of the device. This dissertation will present two methods of modulating the defect concentration in VCM ReRAM composed of Pt/HfOx/Ti stack: 1) rapid thermal annealing (RTA) in Ar using different temperatures, and 2) doping using ion implantation under different dose levels. Metrology techniques such as x-ray diffractometry (XRD), x-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy were utilized to characterize the HfOx switching oxide, which provided insight on the material properties and oxygen vacancy concentration in the oxide that was used to explain the changes in the electrical properties of the ReRAM devices. The resulting impact on the resistive switching characteristics of the devices, such as the forming voltage, set and reset threshold voltages, ON and OFF resistances, resistance ratio, and switching dispersion or uniformity were explored and summarized. Annealing in Ar showed significant impact on the forming voltage, with as much as 45% (from 22V to 12 V) of improvement, as the annealing temperature was increased. However, drawbacks of a higher oxide leakage and worse switching uniformity were seen with increasing annealing temperature. Meanwhile, doping the oxide by ion implantation showed significant effects on the resistive switching characteristics. Ta doping modulated the following switching properties with increasing dose: a) the reduction of the forming voltage, and Vset

  9. Genome-Scale Identification Method Applied to Find Cryptic Aminoglycoside Resistance Genes in Pseudomonas aeruginosa

    PubMed Central

    Struble, Julie M.; Gill, Ryan T.

    2009-01-01

    Background The ability of bacteria to rapidly evolve resistance to antibiotics is a critical public health problem. Resistance leads to increased disease severity and death rates, as well as imposes pressure towards the discovery and development of new antibiotic therapies. Improving understanding of the evolution and genetic basis of resistance is a fundamental goal in the field of microbiology. Results We have applied a new genomic method, Scalar Analysis of Library Enrichments (SCALEs), to identify genomic regions that, given increased copy number, may lead to aminoglycoside resistance in Pseudomonas aeruginosa at the genome scale. We report the result of selections on highly representative genomic libraries for three different aminoglycoside antibiotics (amikacin, gentamicin, and tobramycin). At the genome-scale, we show significant (p<0.05) overlap in genes identified for each aminoglycoside evaluated. Among the genomic segments identified, we confirmed increased resistance associated with an increased copy number of several genomic regions, including the ORF of PA5471, recently implicated in MexXY efflux pump related aminoglycoside resistance, PA4943-PA4946 (encoding a probable GTP-binding protein, a predicted host factor I protein, a δ 2-isopentenylpyrophosphate transferase, and DNA mismatch repair protein mutL), PA0960–PA0963 (encoding hypothetical proteins, a probable cold shock protein, a probable DNA-binding stress protein, and aspartyl-tRNA synthetase), a segment of PA4967 (encoding a topoisomerase IV subunit B), as well as a chimeric clone containing two inserts including the ORFs PA0547 and PA2326 (encoding a probable transcriptional regulator and a probable hypothetical protein, respectively). Conclusions The studies reported here demonstrate the application of new a genomic method, SCALEs, which can be used to improve understanding of the evolution of antibiotic resistance in P. aeruginosa. In our demonstration studies, we identified a

  10. Chances and limits of an improved method to assess water resistance of cosmetic sunscreen products in vitro on polymethylmethacrylate plates.

    PubMed

    Bielfeldt, S; Röck, C; Wilhelm, K-P

    2013-02-01

    While sun protection factor (SPF) and UVA protection are the most important determinants of a cosmetic sunscreen product, water resistance is the third important feature. The Colipa in vivo method is the internationally accepted standard method to assess water resistance. It is time-consuming and expensive. A screening method to quickly predict water resistance properties on low cost therefore is a specific request of product developers. Several in vitro screening methods are published but the predictive power of all these methods is limited. In this paper, we describe an adaptation of the in vitro UVA protection method of Colipa for a water resistance screening. Although the method is quick and most parts are standardized and approved by Colipa, the results were not in advantage of other published screening methods. Taking into account, the scatter of the results, seven of 16 sunscreen products that were developed as water resistant formulations could be unambiguously estimated to be water resistant by the in vivo water resistance screening method on five subjects while nine failed. In 10 of these 16 results, the in vitro SPF-based method was in accordance with in vivo findings, whereas in six cases, the method was not predicting correctly. Based on these results, the authors recommend to use the in vitro screening methods to pre-select from candidates which cannot all be tested in vivo. The pre-selected products can be screened in the Colipa in vivo water resistance method with a reduced number of volunteers (usually 5) to predict water resistance. In case, the water resistance estimated in such an in vivo screening is found at about 65% or higher the study can be deemed successful and completed with further subjects to fulfil the Colipa requirements.

  11. Obesity and coronary microvascular disease - implications for adipose tissue-mediated remote inflammatory response.

    PubMed

    Bagi, Zsolt; Broskova, Zuzana; Feher, Attila

    2014-05-01

    It is believed that obesity has detrimental effects on the coronary circulation. These include immediate changes in coronary arterial vasomotor responsiveness and the development of occlusive large coronary artery disease. Despite its critical role in regulating myocardial perfusion, the altered behavior of coronary resistance arteries, which gives rise to coronary microvascular disease (CMD) is poorly understood in obesity. A chronic, low-grade vascular inflammation has been long considered as one of the main underlying pathology behind CMD. The expanded adipose tissue and the infiltrating macrophages are the major sources of pro-inflammatory mediators that have been implicated in causing inadequate myocardial perfusion and, in a long term, development of heart failure in obese patients. Much less is known the mechanisms regulating the release of these cytokines into the circulation that enable them to exert their remote effects in the coronary microcirculation. This mini review aims to examine recent studies describing alterations in the vasomotor function of coronary resistance arteries and the role of adipose tissue-derived pro-inflammatory cytokines and adipokines in contributing to CMD in obesity. We provide examples of regulatory mechanisms by which adipokines are released from adipose tissue to exert their remote inflammatory effects on coronary microvessels. We identify some of the important challenges and opportunities going forward.

  12. [Psychological resistances of women to the principal female methods of contraception. Clinical classification].

    PubMed

    Wauty-Dancot, M C; Rucquoy, G

    1975-01-01

    According to the literature and to the experience of the authors gathered at the family department at the Louvain Faculty of Medicine, these psychological resistances may schematically be classified as follows: normative and socio-cultural resistances; medical resistances (wish of pregnancy, personality traits, narcissm, sexual and technical resistances); psychopathological resistances (unspecific neurotic behavior, phobias, hypochondriasis, obsessive-compulsive neurosis, character neurosis); secondary resistances.

  13. Method for in-situ restoration of platinum resistance thermometer calibration

    SciTech Connect

    Carroll, R.M.

    1989-01-03

    A method is described for the in situ restoration of a platinum resistance thermometer, which has become decalibrated due to oxide surface film formation and/or strain-related damage, to a stress-free calibration condition wherein the thermometer includes a platinum resistor sensing element whose resistance varies with the temperature of the element in accordance with a known relationship. The method consists of: passing a controlled dc current through the platinum resistor sensing element, the current having a magnitude sufficient to raise the temperature of the element to its oxide decomposition and annealing temperature. The current is maintained for a heating period sufficient to restore the element to an oxide free surface and stress-free calibration condition.

  14. New method of extrapolation of the resistance of a model planing boat to full size

    NASA Technical Reports Server (NTRS)

    Sottorf, W

    1942-01-01

    The previously employed method of extrapolating the total resistance to full size with lambda(exp 3) (model scale) and thereby foregoing a separate appraisal of the frictional resistance, was permissible for large models and floats of normal size. But faced with the ever increasing size of aircraft a reexamination of the problem of extrapolation to full size is called for. A method is described by means of which, on the basis of an analysis of tests on planing surfaces, the variation of the wetted surface over the take-off range is analytically obtained. The friction coefficients are read from Prandtl's curve for turbulent boundary layer with laminar approach. With these two values a correction for friction is obtainable.

  15. Method for in-situ restoration of platinum resistance thermometer calibration

    DOEpatents

    Carroll, R.M.

    1987-10-23

    A method is provided for in-situ restoration of platinum resistance thermometers (PRT's) that have undergone surface oxide contamination and/or stain-related damage causing decalibration. The method, which may be automated using a programmed computer control arrangement, consists of applying a dc heating current to the resistive sensing element of the PRT of sufficient magnitude to heat the element to an annealing temperature and maintaining the temperature for a specified period to restore the element to a stress-free calibration condition. The process anneals the sensing element of the PRT without subjecting the entire PRT assembly to the annealing temperature and may be used in the periodic maintenance of installed PRT's. 1 fig.

  16. Method for in-situ restoration of plantinum resistance thermometer calibration

    DOEpatents

    Carroll, Radford M.

    1989-01-01

    A method is provided for in-situ restoration of platinum resistance thermometers (PRT's) that have undergone surface oxide contamination and/or strain-related damage causing decalibration. The method, which may be automated using a programmed computer control arrangement, consists of applying a dc heating current to the resistive sensing element of the PRT of sufficient magnitude to heat the element to an annealing temperature and maintaining the temperature for a specified period to restore the element to a stress-free calibration condition. The process anneals the sensing element of the PRT without subjecting the entire PRT assembly to the annealing temperature and may be used in the periodic maintenance of installed PRT's.

  17. Method of making bearing materials. [self-lubricating, oxidation resistant composites for high temperature applications

    NASA Technical Reports Server (NTRS)

    Sliney, H. E. (Inventor)

    1979-01-01

    A method is described for making a composite material which provides low friction surfaces for materials in rolling or sliding contact. The composite material which is self-lubricating and oxidation resistant up to and in excess of about 930 C is comprised of a metal component which lends strength and elasticity to the structure and a fluorine salt component which provides oxidation protection to the metal but may also enhance the lubrication qualities of the composite.

  18. Method of making silicon carbide-silicon composite having improved oxidation resistance

    NASA Technical Reports Server (NTRS)

    Luthra, Krishan Lal (Inventor); Wang, Hongyu (Inventor)

    2002-01-01

    A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

  19. Silicon carbide-silicon composite having improved oxidation resistance and method of making

    NASA Technical Reports Server (NTRS)

    Luthra, Krishan Lal (Inventor); Wang, Hongyu (Inventor)

    1999-01-01

    A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

  20. A novel videography method for generating crack-extension resistance curves in small bone samples.

    PubMed

    Katsamenis, Orestis L; Jenkins, Thomas; Quinci, Federico; Michopoulou, Sofia; Sinclair, Ian; Thurner, Philipp J

    2013-01-01

    Assessment of bone quality is an emerging solution for quantifying the effects of bone pathology or treatment. Perhaps one of the most important parameters characterising bone quality is the toughness behaviour of bone. Particularly, fracture toughness, is becoming a popular means for evaluating bone quality. The method is moving from a single value approach that models bone as a linear-elastic material (using the stress intensity factor, K) towards full crack extension resistance curves (R-curves) using a non-linear model (the strain energy release rate in J-R curves). However, for explanted human bone or small animal bones, there are difficulties in measuring crack-extension resistance curves due to size constraints at the millimetre and sub-millimetre scale. This research proposes a novel "whitening front tracking" method that uses videography to generate full fracture resistance curves in small bone samples where crack propagation cannot typically be observed. Here we present this method on sharp edge notched samples (<1 mm×1 mm×Length) prepared from four human femora tested in three-point bending. Each sample was loaded in a mechanical tester with the crack propagation recorded using videography and analysed using an algorithm to track the whitening (damage) zone. Using the "whitening front tracking" method, full R-curves and J-R curves could be generated for these samples. The curves for this antiplane longitudinal orientation were similar to those found in the literature, being between the published longitudinal and transverse orientations. The proposed technique shows the ability to generate full "crack" extension resistance curves by tracking the whitening front propagation to overcome the small size limitations and the single value approach. PMID:23405186

  1. Repeated self-healing of microvascular carbon fibre reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Coope, T. S.; Wass, D. F.; Trask, R. S.; Bond, I. P.

    2014-11-01

    A self-healing, high performance, carbon fibre reinforced polymer (CFRP) composite is demonstrated by embedding a Lewis-acid catalytic curing agent within a laminate, manufactured using out of autoclave (OOA) composite manufacturing methods. Two configurations of healing agent delivery, pre-mixed and autonomous mixing, are investigated via injection of a healing agent through bio-inspired microvascular channels exposed on Mode I fractured crack planes. Healing is effected when an epoxy resin-solvent healing agent mixture reaches the boundary of embedded solid-state scandium(III) triflate (Sc(OTf)3) catalyst, located on the crack plane, to initiate the ring-opening polymerisation (ROP) of epoxides. Tailored self-healing agents confer high healing efficiency values after multiple healing cycles (69-108%) to successfully mitigate against crack propagation within the composite microstructure.

  2. Mechanisms for microvascular damage induced by ultrasound-activated microbubbles

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Brayman, Andrew A.; Evan, Andrew P.; Matula, Thomas J.

    2012-10-01

    To provide insight into the mechanisms of microvascular damage induced by ultrasound-activated microbubbles, experimental studies were performed to correlate microvascular damage to the dynamics of bubble-vessel interactions. High-speed photomicrography was used to record single microbubbles interacting with microvessels in ex vivo tissue, under the exposure of short ultrasound pulses with a center frequency of 1 MHz and peak negative pressures (PNP) ranging from 0.8-4 MPa. Vascular damage associated with observed bubble-vessel interactions was either indicated directly by microbubble extravasation or examined by transmission electron microscopy (TEM) analyses. As observed previously, the high-speed images revealed that ultrasound-activated microbubbles could cause distention and invagination of adjacent vessel walls, and could form liquid jets in microvessels. Vessel distention, invagination, and liquid jets were associated with the damage of microvessels whose diameters were smaller than those of maximally expanded microbubbles. However, vessel invagination appeared to be the dominant mechanism for the damage of relative large microvessels.

  3. Mechanisms for microvascular damage induced by ultrasound-activated microbubbles

    SciTech Connect

    Chen Hong; Brayman, Andrew A.; Evan, Andrew P.; Matula, Thomas J.

    2012-10-03

    To provide insight into the mechanisms of microvascular damage induced by ultrasound-activated microbubbles, experimental studies were performed to correlate microvascular damage to the dynamics of bubble-vessel interactions. High-speed photomicrography was used to record single microbubbles interacting with microvessels in ex vivo tissue, under the exposure of short ultrasound pulses with a center frequency of 1 MHz and peak negative pressures (PNP) ranging from 0.8-4 MPa. Vascular damage associated with observed bubble-vessel interactions was either indicated directly by microbubble extravasation or examined by transmission electron microscopy (TEM) analyses. As observed previously, the high-speed images revealed that ultrasound-activated microbubbles could cause distention and invagination of adjacent vessel walls, and could form liquid jets in microvessels. Vessel distention, invagination, and liquid jets were associated with the damage of microvessels whose diameters were smaller than those of maximally expanded microbubbles. However, vessel invagination appeared to be the dominant mechanism for the damage of relative large microvessels.

  4. Effects of hyperoxia on microvascular cells in vitro

    SciTech Connect

    D'Amore, P.A.; Sweet, E.

    1987-02-01

    Microvascular cells are most vulnerable to direct oxygen damage. Using an in vitro model system we have investigated the effect of elevated oxygen on the proliferation, morphology, and integrity of microvascular endothelial cells (EC) and pericytes. Cultivation of these cells at oxygen concentrations of 40% for 1 wk resulted in the inhibition of EC proliferation but had no effect on the growth of the pericytes. Similarly, hyperoxia induced a dramatic change in the shape of the EC, increasing their spread area by close to six-fold. Under the same conditions, the spread area of the pericytes was unaffected. To understand the effect of the hyperoxic treatment on the cells, the integrity of various membrane systems was assessed. /sup 51/Cr release was used to monitor plasma membrane integrity. There was no difference in chromium release by EC and pericytes over the 7 d of growth under normoxic and hyperoxic conditions. Mitochondrial integrity was examined by staining the cells with Rhodamine 123, which is selectively accumulated by the mitochondria. The staining pattern of the mitochondria of both EC and pericytes was altered by growth in the elevated oxygen. Finally, the lysosomes were visualized using acridine orange. The acridine orange staining pattern revealed enlarged and perinuclear lysosomes in the EC but no change in the pericyte lysosomal staining pattern. Thus, the cells of the microvasculature seem to be differentially affected by hyperoxia, a fact that may be significant in the etiology of reperfusion injury, ischemic disease, and pathologies associated with prematurity.

  5. Modulation of cerebral microvascular permeability by endothelial nicotinic acetylcholine receptors.

    PubMed

    Hawkins, Brian T; Egleton, Richard D; Davis, Thomas P

    2005-07-01

    Nicotine increases the permeability of the blood-brain barrier in vivo. This implies a possible role for nicotinic acetylcholine receptors in the regulation of cerebral microvascular permeability. Expression of nicotinic acetylcholine receptor subunits in cerebral microvessels was investigated with immunofluorescence microscopy. Positive immunoreactivity was found for receptor subunits alpha3, alpha5, alpha7, and beta2, but not subunits alpha4, beta3, or beta4. Blood-brain barrier permeability was assessed via in situ brain perfusion with [14C]sucrose. Nicotine increased the rate of sucrose entry into the brain from 0.3 +/- 0.1 to 1.1 +/- 0.2 microl.g(-1).min(-1), as previously described. This nicotine-induced increase in blood-brain barrier permeability was significantly attenuated by both the blood-brain barrier-permeant nicotinic antagonist mecamylamine and the blood-brain barrier-impermeant nicotinic antagonist hexamethonium to 0.5 +/- 0.2 and 0.3 +/- 0.2 microl.g(-1).min(-1), respectively. These data suggest that nicotinic acetylcholine receptors expressed on the cerebral microvascular endothelium mediate nicotine-induced changes in blood-brain barrier permeability.

  6. Angina pectoris in women: focus on microvascular disease.

    PubMed

    Zuchi, Cinzia; Tritto, Isabella; Ambrosio, Giuseppe

    2013-02-20

    Ischemic heart disease (IHD) is the leading cause of death among women in Western countries, and it is associated with higher morbidity and mortality than in men. Nevertheless, IHD in women remains underdiagnosed and undertreated, and the misperception that females are "protected" against cardiovascular disease leads to underestimation of their cardiovascular risk; instead, women with chest pain have a high risk of cardiovascular events. Women suffering from angina pectoris tend to have different characteristics compared to men, with a high prevalence of non-significant coronary artery disease. Angina in women is more commonly microvascular in origin than in men, and therefore standard diagnostic algorithms may be suboptimal for women. This different pathophysiology impacts clinical management of IHD in women. While response to medical therapy may differ in women, they are scarcely represented in clinical trials. Therefore, solid data in terms of gender efficacy of antianginal drugs are lacking, and particularly when angina is microvascular in origin women often continue to be symptomatic despite maximal therapy with classical antianginal drugs. Recently, new molecules have shown promising results in women. In conclusion, women with angina are a group of patients in whom it seems appropriate to concentrate efforts aimed at reducing morbidity and improving quality of life.

  7. Albumin microvascular leakage in brains with diabetes mellitus.

    PubMed

    Fujihara, Ryuji; Chiba, Yoichi; Nakagawa, Toshitaka; Nishi, Nozomu; Murakami, Ryuta; Matsumoto, Koichi; Kawauchi, Machi; Yamamoto, Tetsuji; Ueno, Masaki

    2016-09-01

    Their aim was to examine whether microvascular leakage of endogenous albumin, a representative marker for blood-brain barrier (BBB) damage, was induced in the periventricular area of diabetic db/db mice because periventricular white matter hyperintensity formation in magnetic resonance images was accelerating in elderly patients with diabetes mellitus. Using light and electron microscopes, and semi-quantitative analysis techniques, immunoreactivity of endogenous albumin, indicating vascular permeability, was examined in the periventricular area and spinal cord of db/db mice and db/+m control mice. Greater immunoreactivity of albumin was observed in the vessel wall of the periventricular area of db/db mice than in controls. Additionally, weak immunoreactivity was observed in the spinal cord of both db/db mice and controls. The number of gold particles, indicating immunoreactivity of albumin, in the perivascular area of db/db mice was significantly higher than that of control mice, but there was no significant difference in the number of particles in the spinal cord between db/db mice and controls. These findings suggest that albumin microvascular leakage, or BBB breakdown, is induced in the periventricular area of diabetic mice. Microsc. Res. Tech. 79:833-837, 2016. © 2016 Wiley Periodicals, Inc. PMID:27333535

  8. 3D resistivity inversion using an improved Genetic Algorithm based on control method of mutation direction

    NASA Astrophysics Data System (ADS)

    Liu, B.; Li, S. C.; Nie, L. C.; Wang, J.; L, X.; Zhang, Q. S.

    2012-12-01

    Traditional inversion method is the most commonly used procedure for three-dimensional (3D) resistivity inversion, which usually takes the linearization of the problem and accomplish it by iterations. However, its accuracy is often dependent on the initial model, which can make the inversion trapped in local optima, even cause a bad result. Non-linear method is a feasible way to eliminate the dependence on the initial model. However, for large problems such as 3D resistivity inversion with inversion parameters exceeding a thousand, main challenges of non-linear method are premature and quite low search efficiency. To deal with these problems, we present an improved Genetic Algorithm (GA) method. In the improved GA method, smooth constraint and inequality constraint are both applied on the object function, by which the degree of non-uniqueness and ill-conditioning is decreased. Some measures are adopted from others by reference to maintain the diversity and stability of GA, e.g. real-coded method, and the adaptive adjustment of crossover and mutation probabilities. Then a generation method of approximately uniform initial population is proposed in this paper, with which uniformly distributed initial generation can be produced and the dependence on initial model can be eliminated. Further, a mutation direction control method is presented based on the joint algorithm, in which the linearization method is embedded in GA. The update vector produced by linearization method is used as mutation increment to maintain a better search direction compared with the traditional GA with non-controlled mutation operation. By this method, the mutation direction is optimized and the search efficiency is improved greatly. The performance of improved GA is evaluated by comparing with traditional inversion results in synthetic example or with drilling columnar sections in practical example. The synthetic and practical examples illustrate that with the improved GA method we can eliminate

  9. Effect of two sweating simulation methods on clothing evaporative resistance in a so-called isothermal condition.

    PubMed

    Lu, Yehu; Wang, Faming; Peng, Hui

    2016-07-01

    The effect of sweating simulation methods on clothing evaporative resistance was investigated in a so-called isothermal condition (T manikin  = T a  = T r ). Two sweating simulation methods, namely, the pre-wetted fabric "skin" (PW) and the water supplied sweating (WS), were applied to determine clothing evaporative resistance on a "Newton" thermal manikin. Results indicated that the clothing evaporative resistance determined by the WS method was significantly lower than that measured by the PW method. In addition, the evaporative resistances measured by the two methods were correlated and exhibited a linear relationship. Validation experiments demonstrated that the empirical regression equation showed highly acceptable estimations. The study contributes to improving the accuracy of measurements of clothing evaporative resistance by means of a sweating manikin. PMID:26542017

  10. Effect of two sweating simulation methods on clothing evaporative resistance in a so-called isothermal condition

    NASA Astrophysics Data System (ADS)

    Lu, Yehu; Wang, Faming; Peng, Hui

    2016-07-01

    The effect of sweating simulation methods on clothing evaporative resistance was investigated in a so-called isothermal condition ( T manikin = T a = T r ). Two sweating simulation methods, namely, the pre-wetted fabric "skin" (PW) and the water supplied sweating (WS), were applied to determine clothing evaporative resistance on a "Newton" thermal manikin. Results indicated that the clothing evaporative resistance determined by the WS method was significantly lower than that measured by the PW method. In addition, the evaporative resistances measured by the two methods were correlated and exhibited a linear relationship. Validation experiments demonstrated that the empirical regression equation showed highly acceptable estimations. The study contributes to improving the accuracy of measurements of clothing evaporative resistance by means of a sweating manikin.

  11. Evaluation of different methods for the detection of methicillin resistance in coagulase-negative staphylococci.

    PubMed

    Jarløv, J O; Busch-Sørensen, C; Espersen, F; Mortensen, I; Hougaard, D M; Rosdahl, V T

    1997-08-01

    The efficacy of 19 agar diffusion methods for the detection of methicillin resistance among coagulase-negative staphylococci (CoNS) within 24 h was evaluated. A total of 359 CoNS isolates were tested, of which 204 were Staphylococcus epidermidis. In 164 isolates, the presence of mecA was investigated; 61 strains were mecA-positive and 103 were mecA-negative by Southern blot analysis. Based on the best agreement shown with the mecA determination (94%) among four agar dilution assays for determining methicillin MIC, an assay with Columbia agar supplemented with NaCl and incubation with a heavy bacterial inoculum of 10(5)-10(6) cfu/spot was used as the reference MIC method. The best agar diffusion results were obtained with a 1 microg oxacillin disc on Columbia agar with 4.5% NaCl supplement. With this method, 99% of S. epidermidis and 94% of non-S. epidermidis were in agreement with the MIC determination. However, Columbia (without NaCl), Mueller-Hinton and Isosensitest agars were almost as useful when a 1 microg oxacillin disc was used. The zone breakpoints for S. epidermidis were, in general, considerably larger than those for other CoNS species and, consequently, differentiation according to species is recommended. Furthermore, resistance to other antibiotics, such as gentamicin and erythromycin, makes methicillin resistance highly likely.

  12. Evaluation of different methods for the detection of methicillin resistance in coagulase-negative staphylococci.

    PubMed

    Jarløv, J O; Busch-Sørensen, C; Espersen, F; Mortensen, I; Hougaard, D M; Rosdahl, V T

    1997-08-01

    The efficacy of 19 agar diffusion methods for the detection of methicillin resistance among coagulase-negative staphylococci (CoNS) within 24 h was evaluated. A total of 359 CoNS isolates were tested, of which 204 were Staphylococcus epidermidis. In 164 isolates, the presence of mecA was investigated; 61 strains were mecA-positive and 103 were mecA-negative by Southern blot analysis. Based on the best agreement shown with the mecA determination (94%) among four agar dilution assays for determining methicillin MIC, an assay with Columbia agar supplemented with NaCl and incubation with a heavy bacterial inoculum of 10(5)-10(6) cfu/spot was used as the reference MIC method. The best agar diffusion results were obtained with a 1 microg oxacillin disc on Columbia agar with 4.5% NaCl supplement. With this method, 99% of S. epidermidis and 94% of non-S. epidermidis were in agreement with the MIC determination. However, Columbia (without NaCl), Mueller-Hinton and Isosensitest agars were almost as useful when a 1 microg oxacillin disc was used. The zone breakpoints for S. epidermidis were, in general, considerably larger than those for other CoNS species and, consequently, differentiation according to species is recommended. Furthermore, resistance to other antibiotics, such as gentamicin and erythromycin, makes methicillin resistance highly likely. PMID:9301990

  13. The `L' Array, a method to model 3D Electrical Resistivity Tomography (ERT) data

    NASA Astrophysics Data System (ADS)

    Chavez Segura, R. E.; Chavez-Hernandez, G.; Delgado, C.; Tejero-Andrade, A.

    2010-12-01

    The electrical resistivity tomography (ERT) is a method designed to calculate the distribution of apparent electrical resistivities in the subsoil by means of a great number of observations with the aim of determining an electrical image displaying the distribution of true resistivities in the subsoil. Such process can be carried out to define 2D or 3D models of the subsurface. For a 3D ERT, usually, the electrodes are placed in a squared grid keeping the distance between adjacent electrodes constant in the x and y directions. Another design employed, consists of a series of parallel lines whose space inter-lines must be smaller or equal to four times the electrode separation. The most common electrode arrays frequently employed for this type of studies are the pole-pole, pole-dipole and dipole-dipole. Unfortunately, ERT surface sampling schemes are limited by physical conditions or obstacles, like buildings, highly populated urban zones, and geologic/topographic features, where the lines of electrodes cannot be set. However, it is always necessary to characterize the subsoil beneath such anthropogenic or natural features. The ‘L’ shaped array has the main purpose to overcome such difficulties by surrounding the study area with a square of electrode lines. The measurements are obtained by switching automatically current and potential electrodes from one line to the other. Each observation adds a level of information, from one profile to the other. Once the total levels of data are completed, the opposite ‘L’ array can be measured following the same process. The complete square is computed after the parallel profiles are observed as well. At the end, the computed resistivities are combined to form a 3D matrix of observations. Such set of data can be inverted to obtain the true resistivity distribution at depth in the form of a working cube, which can be interpreted. The method was tested with theoretical models, which included a set of two resistive cubes

  14. Potential of Lattice Boltzmann Method to Determine the Ohmic Resistance in Porous Materials

    NASA Astrophysics Data System (ADS)

    Espinoza-Andaluz, Mayken; Andersson, Martin; Sundén, Bengt

    2016-08-01

    The lattice Boltzmann method (LBM) is a suitable tool for solving transport phenomena that occur in gas- and liquid phases at different length scales, especially when complex geometries such as porous media are involved. However, investigations about applications of LBM in the solid electrical conducting material have not been carried out yet. Since in fuel cells (FCs) the multifunctional layers play an important role during the energy conversion process, and such layers consist of porous material, the ohmic resistance of porous materials represents a crucial characteristic to be studied to predict the internal ohmic losses. The purpose of this paper is to show the feasibility of LBM to determine the ohmic resistance of electrical conducting materials whose dimensions are modified considering the crosssectional area and length. Characteristics, limitations and recommendations of LBM applied to solid electrical conducting materials calculating the ohmic resistance are presented considering the coupling of the methodology with the Ohm's Law. Additionally, the behavior of the ohmic resistance for a given porous material is presented.

  15. Methods of Calculation of Resistance to Polarization (Corrosion Rate) Using ASTM G 59

    SciTech Connect

    Wong, L L; King, K J; Martin, S I; Rebak, R B

    2006-02-05

    The corrosion rate of a metal (alloy) can be measured using: (1) Immersion tests or weight loss such as in ASTM G 1 and G 31 or (2) Electrochemical techniques such as in ASTM G 59. In the polarization resistance (PR) or linear polarization method (G 59), the resistance to polarization (Rp) of a metal is measured in the electrolyte of interest in the vicinity of the corrosion potential (E{sub corr}). This polarization resistance can be mathematically converted into corrosion rates (CR). A plot of E vs. I in the vicinity of E{sub corr} is generated by increasing the potential at a fixed rate of 0.1667 mV/s and measuring the output current. The polarization resistance (Rp) is defined as the slope of a potential (E) (Y axis) vs. Current (I) (X axis) plot in the vicinity of the corrosion potential (E{sub corr}). When the potential is ramped and the current is measured, E is the independent variable and I is the dependent variable. In a proper mathematical plot, E should be represented in the X axis and I in the Y axis. However, in the conventions of the corrosion community, E is always plotted in the Y axis and I in the X axis. Therefore, how this plot of Delta E/Delta I is analyzed is a matter of current debate.

  16. Pericyte abundance affects sucrose permeability in cultures of rat brain microvascular endothelial cells.

    PubMed

    Parkinson, Fiona E; Hacking, Cindy

    2005-07-01

    The blood-brain barrier is a physical and metabolic barrier that restricts diffusion of blood-borne substances into brain. In vitro models of the blood-brain barrier are used to characterize this structure, examine mechanisms of damage and repair and measure permeability of test substances. The core component of in vitro models of the blood-brain barrier is brain microvascular endothelial cells. We cultured rat brain microvascular endothelial cells (RBMEC) from isolated rat cortex microvessels. After 2-14 days in vitro (DIV), immunohistochemistry of these cells showed strong labeling for zona occludens 1 (ZO-1), a tight junction protein expressed in endothelial cells. Pericytes were also present in these cultures, as determined by expression of alpha-actin. The present study was performed to test different cell isolation methods and to compare the resulting cell cultures for abundance of pericytes and for blood-brain barrier function, as assessed by 14C-sucrose flux. Two purification strategies were used. First, microvessels were preabsorbed onto uncoated plastic for 4 h, then unattached microvessels were transferred to coated culture ware. Second, microvessels were incubated with an antibody to platelet-endothelial cell adhesion molecule 1 (PECAM-1; CD31) precoupled to magnetic beads, and a magnetic separation procedure was performed. Our results indicate that immunopurification, but not preadsorption, was an effective method to purify microvessels and reduce pericyte abundance in the resulting cultures. This purification significantly reduced 14C-sucrose fluxes across cell monolayers. These data indicate that pericytes can interfere with the development of blood-brain barrier properties in in vitro models that utilize primary cultures of RBMECs.

  17. Deep-brain stimulation associates with improved microvascular integrity in the subthalamic nucleus in Parkinson's disease.

    PubMed

    Pienaar, Ilse S; Lee, Cecilia Heyne; Elson, Joanna L; McGuinness, Louisa; Gentleman, Stephen M; Kalaria, Raj N; Dexter, David T

    2015-02-01

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become an accepted treatment for motor symptoms in a subset of Parkinson's disease (PD) patients. The mechanisms why DBS is effective are incompletely understood, but previous studies show that DBS targeted in brain structures other than the STN may modify the microvasculature. However, this has not been studied in PD subjects who have received STN-DBS. Here we investigated the extent and nature of microvascular changes in post-mortem STN samples from STN-DBS PD patients, compared to aged controls and PD patients who had not been treated with STN-DBS. We used immunohistochemical and immunofluorescent methods to assess serial STN-containing brain sections from PD and STN-DBS PD cases, compared to similar age controls using specific antibodies to detect capillaries, an adherens junction and tight junction-associated proteins as well as activated microglia. Cellular features in stained sections were quantified by confocal fluorescence microscopy and stereological methods in conjunction with in vitro imaging tools. We found significant upregulation of microvessel endothelial cell thickness, length and density but lowered activated microglia density and striking upregulation of all analysed adherens junction and tight junction-associated proteins in STN-DBS PD patients compared to non-DBS PD patients and controls. Moreover, in STN-DBS PD samples, expression of an angiogenic factor, vascular endothelial growth factor (VEGF), was significantly upregulated compared to the other groups. Our findings suggest that overexpressed VEGF and downregulation of inflammatory processes may be critical mechanisms underlying the DBS-induced microvascular changes. PMID:25533682

  18. Glycosaminoglycan Regulation by VEGFA and VEGFC of the Glomerular Microvascular Endothelial Cell Glycocalyx in Vitro

    PubMed Central

    Foster, Rebecca R.; Armstrong, Lynne; Baker, Siân; Wong, Dickson W.L.; Wylie, Emma C.; Ramnath, Raina; Jenkins, Robert; Singh, Anurag; Steadman, Robert; Welsh, Gavin I.; Mathieson, Peter W.; Satchell, Simon C.

    2014-01-01

    Damage to endothelial glycocalyx impairs vascular barrier function and may contribute to progression of chronic vascular disease. An early indicator is microalbuminuria resulting from glomerular filtration barrier damage. We investigated the contributions of hyaluronic acid (HA) and chondroitin sulfate (CS) to glomerular microvascular endothelial cell (GEnC) glycocalyx and examined whether these are modified by vascular endothelial growth factors A and C (VEGFA and VEGFC). HA and CS were imaged on GEnCs and their resynthesis was examined. The effect of HA and CS on transendothelial electrical resistance (TEER) and labeled albumin flux across monolayers was assessed. Effects of VEGFA and VEGFC on production and charge characteristics of glycosaminoglycan (GAG) were examined via metabolic labeling and liquid chromatography. GAG shedding was quantified using Alcian Blue. NDST2 expression was examined using real-time PCR. GEnCs expressed HA and CS in the glycocalyx. CS contributed to the barrier to both ion (TEER) and protein flux across the monolayer; HA had only a limited effect. VEGFC promoted HA synthesis and increased the charge density of synthesized GAGs. In contrast, VEGFA induced shedding of charged GAGs. CS plays a role in restriction of macromolecular flux across GEnC monolayers, and VEGFA and VEGFC differentially regulate synthesis, charge, and shedding of GAGs in GEnCs. These observations have important implications for endothelial barrier regulation in glomerular and other microvascular beds. PMID:23770346

  19. Quercetin protects human brain microvascular endothelial cells from fibrillar β-amyloid1–40-induced toxicity

    PubMed Central

    Li, Yongjie; Zhou, Sibai; Li, Jinze; Sun, Yuhua; Hasimu, Hamlati; Liu, Rui; Zhang, Tiantai

    2015-01-01

    Amyloid beta-peptides (Aβ) are known to undergo active transport across the blood-brain barrier, and cerebral amyloid angiopathy has been shown to be a prominent feature in the majority of Alzheimer׳s disease. Quercetin is a natural flavonoid molecule and has been demonstrated to have potent neuroprotective effects, but its protective effect on endothelial cells under Aβ-damaged condition is unclear. In the present study, the protective effects of quercetin on brain microvascular endothelial cells injured by fibrillar Aβ1–40 (fAβ1–40) were observed. The results show that fAβ1–40-induced cytotoxicity in human brain microvascular endothelial cells (hBMECs) can be relieved by quercetin treatment. Quercetin increases cell viability, reduces the release of lactate dehydrogenase, and relieves nuclear condensation. Quercetin also alleviates intracellular reactive oxygen species generation and increases superoxide dismutase activity. Moreover, it strengthens the barrier integrity through the preservation of the transendothelial electrical resistance value, the relief of aggravated permeability, and the increase of characteristic enzyme levels after being exposed to fAβ1–40. In conclusion, quercetin protects hBMECs from fAβ1–40-induced toxicity. PMID:26579424

  20. The Path Resistance Method for Bounding the Smallest Nontrivial Eigenvalue of a Laplacian

    NASA Technical Reports Server (NTRS)

    Guattery, Stephen; Leighton, Tom; Miller, Gary L.

    1997-01-01

    We introduce the path resistance method for lower bounds on the smallest nontrivial eigenvalue of the Laplacian matrix of a graph. The method is based on viewing the graph in terms of electrical circuits; it uses clique embeddings to produce lower bounds on lambda(sub 2) and star embeddings to produce lower bounds on the smallest Rayleigh quotient when there is a zero Dirichlet boundary condition. The method assigns priorities to the paths in the embedding; we show that, for an unweighted tree T, using uniform priorities for a clique embedding produces a lower bound on lambda(sub 2) that is off by at most an 0(log diameter(T)) factor. We show that the best bounds this method can produce for clique embeddings are the same as for a related method that uses clique embeddings and edge lengths to produce bounds.

  1. Comparison of a quantitative microtiter method, a quantitative automated method, and the plate-count method for determining microbial complement resistance.

    PubMed

    Lee, M D; Wooley, R E; Brown, J; Spears, K R; Nolan, L K; Shotts, E B

    1991-01-01

    A quantitative microtiter method for determining the degree of complement resistance or sensitivity of microorganisms is described. The microtiter method is compared with a quantitative automated system and the standard plate-count technique. Data were accumulated from 30 avian Escherichia coli isolates incubated at 35 C with either chicken plasma or heat-inactivated chicken plasma. Analysis of data generated by the automated system and plate-count techniques resulted in a classification of the microorganisms into three groups: those sensitive to the action of complement; those of intermediate sensitivity to the action of complement; and those resistant to the action of complement. Although the three methods studied did not agree absolutely, there were statistically significant correlations among them.

  2. A stochastic simulation method for the assessment of resistive random access memory retention reliability

    SciTech Connect

    Berco, Dan Tseng, Tseung-Yuen

    2015-12-21

    This study presents an evaluation method for resistive random access memory retention reliability based on the Metropolis Monte Carlo algorithm and Gibbs free energy. The method, which does not rely on a time evolution, provides an extremely efficient way to compare the relative retention properties of metal-insulator-metal structures. It requires a small number of iterations and may be used for statistical analysis. The presented approach is used to compare the relative robustness of a single layer ZrO{sub 2} device with a double layer ZnO/ZrO{sub 2} one, and obtain results which are in good agreement with experimental data.

  3. Temperature measurement method using temperature coefficient timing for resistive or capacitive sensors

    DOEpatents

    Britton, C.L. Jr.; Ericson, M.N.

    1999-01-19

    A method and apparatus for temperature measurement especially suited for low cost, low power, moderate accuracy implementation. It uses a sensor whose resistance varies in a known manner, either linearly or nonlinearly, with temperature, and produces a digital output which is proportional to the temperature of the sensor. The method is based on performing a zero-crossing time measurement of a step input signal that is double differentiated using two differentiators functioning as respective first and second time constants; one temperature stable, and the other varying with the sensor temperature. 5 figs.

  4. Temperature measurement method using temperature coefficient timing for resistive or capacitive sensors

    DOEpatents

    Britton, Jr., Charles L.; Ericson, M. Nance

    1999-01-01

    A method and apparatus for temperature measurement especially suited for low cost, low power, moderate accuracy implementation. It uses a sensor whose resistance varies in a known manner, either linearly or nonlinearly, with temperature, and produces a digital output which is proportional to the temperature of the sensor. The method is based on performing a zero-crossing time measurement of a step input signal that is double differentiated using two differentiators functioning as respective first and second time constants; one temperature stable, and the other varying with the sensor temperature.

  5. Resistivity, induced polarization, and self-potential methods in geothermal exploration

    SciTech Connect

    Ward, S.H.; Sill, W.R.

    1982-01-01

    An overview of the literature is presented. This is followed by a statement of some elementary electromagnetic theory necessary to establish the MKS system of units and the fundamental physics governing electrical methods of exploration. Next there is presented a reasonably detailed discussion of the electrical properties of earth materials including normal mode of conduction, surface conduction, electrode polarization, membrane polarization, semiconduction, melt conduction, real and complex resistivity, and the origin of self-potentials in geothermal systems. To illustrate how electrical methods are used within the framework of integrated geological, geochemical, and geophysical exploration, the case history of the Monroe-Red Hill hot springs system is presented.

  6. Peculiarities of Enhancing Resistant Starch in Ruminants Using Chemical Methods: Opportunities and Challenges

    PubMed Central

    Deckardt, Kathrin; Khol-Parisini, Annabella; Zebeli, Qendrim

    2013-01-01

    High-producing ruminants are fed high amounts of cereal grains, at the expense of dietary fiber, to meet their high energy demands. Grains consist mainly of starch, which is easily degraded in the rumen by microbial glycosidases, providing energy for rapid growth of rumen microbes and short-chain fatty acids (SCFA) as the main energy source for the host. Yet, low dietary fiber contents and the rapid accumulation of SCFA lead to rumen disorders in cattle. The chemical processing of grains has become increasingly important to confer their starch resistances against rumen microbial glycosidases, hence generating ruminally resistant starch (RRS). In ruminants, unlike monogastric species, the strategy of enhancing resistant starch is useful, not only in lowering the amount of carbohydrate substrates available for digestion in the upper gut sections, but also in enhancing the net hepatic glucose supply, which can be utilized by the host more efficiently than the hepatic gluconeogenesis of SCFA. The use of chemical methods to enhance the RRS of grains and the feeding of RRS face challenges in the practice; therefore, the present article attempts to summarize the most important achievements in the chemical processing methods used to generate RRS, and review advantages and challenges of feeding RRS to ruminants. PMID:23736826

  7. Compensation effect analysis in DIE method for through-casing measuring formation resistivity

    NASA Astrophysics Data System (ADS)

    Qing, Chen; Pardo, David; Hong-bin, Li; Fu-rong, Wang

    2011-08-01

    The measuring technique based on Double-Injection-Electrodes (DIE) and its compensation arithmetic method have been proven to be very useful for eliminating the errors caused by electrode-scale mechanical tolerances in formation resistivity measurement through metal case. In this paper, we found that even minor casing joint or casing corrosion may deteriorate the measurement accuracy. Based on theoretical analysis and self-adaptive goal oriented hp-Finite Element (FE) simulations, the compensation effects of DIE measurement technique were estimated. The calculated results from this measuring method are always close to the real formation resistivity, regardless of whether the metal casing is ideal or not. Meanwhile, large errors occur when recording measurements based on Single-Injection-Electrodes (SIE), since the calculated formation resistivity may provide negative values when casing joint or casing corrosion exists. The Double-Injection-Electrode (DIE) measurement technique is predicted to have good compensation effects in many non-ideal situations with uneven metal casing besides electrode-scale mechanical tolerances.

  8. Research on theoretical optimization and experimental verification of minimum resistance hull form based on Rankine source method

    NASA Astrophysics Data System (ADS)

    Zhang, Bao-Ji; Zhang, Zhu-Xin

    2015-09-01

    To obtain low resistance and high efficiency energy-saving ship, minimum total resistance hull form design method is studied based on potential flow theory of wave-making resistance and considering the effects of tail viscous separation. With the sum of wave resistance and viscous resistance as objective functions and the parameters of B-Spline function as design variables, mathematical models are built using Nonlinear Programming Method (NLP) ensuring the basic limit of displacement and considering rear viscous separation. We develop ship lines optimization procedures with intellectual property rights. Series60 is used as parent ship in optimization design to obtain improved ship (Series60-1) theoretically. Then drag tests for the improved ship (Series60-1) is made to get the actual minimum total resistance hull form.

  9. Electrically resistive coating for remediation (regeneration) of a diesel particulate filter and method

    DOEpatents

    Phelps, Amanda C.; Kirby, Kevin K.; Gregoire, Daniel J.

    2012-02-14

    A resistively heated diesel particulate filter (DPF). The resistively heated DPF includes a DPF having an inlet surface and at least one resistive coating on the inlet surface. The at least one resistive coating is configured to substantially maintain its resistance in an operating range of the DPF. The at least one resistive coating has a first terminal and a second terminal for applying electrical power to resistively heat up the at least one resistive coating in order to increase the temperature of the DPF to a regeneration temperature. The at least one resistive coating includes metal and semiconductor constituents.

  10. Methods and apparatus for measurement of the resistivity of geological formations from within cased boreholes

    DOEpatents

    Vail, III, William B.

    1989-01-01

    Methods and apparatus are disclosed which allow measurement of the resistivity of a geological formation through borehole casing which may be surrounded by brine saturated cement. A.C. current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. The A.C. voltage difference is measured between two additional vertically disposed electrodes on the interior of the casing which provides a measure of the resistivity of the geological formation. A calibration and nulling procedure is presented which minimizes the influence of variations in the thickness of the casing. The procedure also minimizes the influence of inaccurate placements of the additional vertically disposed electrodes.

  11. Methods and apparatus for measurement of the resistivity of geological formations from within cased boreholes

    DOEpatents

    Vail, W.B. III.

    1989-04-11

    Methods and apparatus are disclosed which allow measurement of the resistivity of a geological formation through borehole casing which may be surrounded by brine saturated cement. A.C. current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. The A.C. voltage difference is measured between two additional vertically disposed electrodes on the interior of the casing which provides a measure of the resistivity of the geological formation. A calibration and nulling procedure is presented which minimizes the influence of variations in the thickness of the casing. The procedure also minimizes the influence of inaccurate placements of the additional vertically disposed electrodes. 3 figs.

  12. System and method for determining stator winding resistance in an AC motor using motor drives

    DOEpatents

    Lu, Bin; Habetler, Thomas G; Zhang, Pinjia

    2013-02-26

    A system and method for determining the stator winding resistance of AC motors is provided. The system includes an AC motor drive having an input connectable to an AC source and an output connectable to an input terminal of an AC motor, a pulse width modulation (PWM) converter having switches therein to control current flow and terminal voltages in the AC motor, and a control system connected to the PWM converter. The control system generates a command signal to cause the PWM converter to control an output of the AC motor drive corresponding to an input to the AC motor, selectively generates a modified command signal to cause the PWM converter to inject a DC signal into the output of the AC motor drive, and determines a stator winding resistance of the AC motor based on the DC signal of at least one of the voltage and current.

  13. System and method for determining stator winding resistance in an AC motor

    DOEpatents

    Lu, Bin; Habetler, Thomas G.; Zhang, Pinjia; Theisen, Peter J.

    2011-05-31

    A system and method for determining stator winding resistance in an AC motor is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of an AC motor. The circuit includes at least one contactor and at least one switch to control current flow and terminal voltages in the AC motor. The system also includes a controller connected to the circuit and configured to modify a switching time of the at least one switch to create a DC component in an output of the system corresponding to an input to the AC motor and determine a stator winding resistance of the AC motor based on the injected DC component of the voltage and current.

  14. Substantiation of Reference Method For Determining Concrete's Freeze-Thaw Resistance

    NASA Astrophysics Data System (ADS)

    Nikolskiy, S.; Pertseva, O.

    2016-04-01

    It has been analytically proved that using concrete's rate of set e as a measure of damage, instead of decreasing of tensile strength R, increases freeze-thaw resistance's accuracy of estimation a lot under otherwise equal conditions by the time of freeze-thaw cycling. Also it has been experimentally shown that ratio of relative decreasing R to ε in direction, perpendicular to compression, is assumed to be independent on values R and ε for a given concrete and on the ways of achieving them during mechanical or freeze-thaw cycling. Taking this into account patented methods for estimation of concrete's freeze-thaw resistance as per values R and e received after freezing and thawing cycles of some specimens and their postliminary failure by linear compression was substantiated.

  15. Screening for disease resistance in barley cultivars against Bipolaris sorokiniana using callus culture method.

    PubMed

    Chand, Ramesh; Sen, Devyani; Prasad, K D; Singh, A K; Bashyal, B M; Prasad, L C; Joshi, A K

    2008-04-01

    Screening for resistant barley genotypes in response to fungal toxin of Bipolaris sorokiniana was assessed on standing barley plants as well as in selected callus lines of the same. For the standing lines tested, those manifesting chlorosis in response to toxin infiltration showed a significantly slower disease progress as compared to the necrotic lines. Also, necrosis in the callus tissues of the susceptible cultivar in MS medium supplemented with different concentrations of the crude toxin was significantly higher than in the callus tissues of the chlorotic lines studied. Similar host response to the toxin in in vitro and field situations open up the possibility of screening barley cultivars for resistance to spot blotch using callus culture as against classical methods of screening in order to increase accuracy and save time and space.

  16. Microvascular reactivity in normotensive subjects with a familial predisposition to hypertension.

    PubMed

    Maver, J; Strucl, M

    2000-11-01

    Using the laser-Doppler method we measured blood flow on the nailfold skin to compare the reactivity of cutaneous microcirculation in three groups of normotensive subjects: 11 subjects with a familial predisposition to hypertension without a previous record of high blood pressure, 6 predisposed subjects with a previous record of high blood pressure, and 13 subjects with no predisposition to hypertension. The flow was measured after direct and indirect skin cooling and heating and during postocclusive reactive hyperemia (PRH) after a 10-min occlusion of digital arteries. The frequency of flow oscillations in the second part of the PRH was established. Heart rate spectral analysis was performed based on the monitoring of the peripheral pulse frequency by means of the finapres device. In comparison to the other two groups of subjects, the group with a predisposition and a previous record of high blood pressure displayed a larger surface area in the low frequency band (0.05 to 0.15 Hz) of the heart rate variability power spectrum (the Bonferroni test, P < 0.05). As compared to subjects without predisposition, both groups of predisposed subjects exhibited higher frequency of flow oscillations in the second part of the PRH (the Bonferroni test, P < 0.05). Our results indicate that there could be a change in cutaneous microvascular reactivity of local (most probably myogenic) origin even in normotensive subjects with a predisposition to hypertension, whereas in normotensives with a predisposition and a previous record of high blood pressure there could be also a different cutaneous microvascular reactivity of central (nonvascular) origin. PMID:11078640

  17. Malvidin’s Effects on Rat Pial Microvascular Permeability Changes Due to Hypoperfusion and Reperfusion Injury

    PubMed Central

    Lapi, Dominga; Chiurazzi, Martina; Di Maro, Martina; Mastantuono, Teresa; Battiloro, Laura; Sabatino, Lina; Ricci, Serena; Di Carlo, Angelina; Starita, Noemy; Guida, Bruna; Santillo, Mariarosaria; Colantuoni, Antonio

    2016-01-01

    The present study was aimed to evaluate the malvidin’s protective effects on damage induced by 30 min bilateral common carotid artery occlusion (BCCAO) and 60 min reperfusion (RE) in rat pial microcirculation. Rat pial microcirculation was observed using fluorescence microscopy through a closed cranial window. Western blotting analysis was performed to investigate the endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS) and matrix metalloproteinase 9 (MMP-9) expression. Moreover, MMP-9 activity was evaluated by zymography. Finally, neuronal damage and radical oxygen species (ROS) formation were assessed. In all animals, pial arterioles were classified in five orders of branching according to Strahler’s method. In hypoperfused rats, 30 min BCCAO and 60 min RE caused a decrease in arteriolar diameter, an increase in microvascular leakage and leukocyte adhesion, accompanied by decreased capillary perfusion and red blood cell velocity (VRBC). Moreover, marked neuronal damage and evident ROS generation were detected. Conversely, malvidin administration induced arteriolar dilation in dose-related manner, reducing microvascular leakage as well as leukocyte adhesion. Capillary perfusion and VRBC were protected. Nitric oxide (NO) synthase inhibition significantly attenuated malvidin’s effects on arteriolar diameter. Western blotting analysis revealed an increase in eNOS and p-eNOS expression, while zymography indicated a decrease in MMP-9 activity after malvidin’s administration. Furthermore, malvidin was able to prevent neuronal damage and to decrease ROS generation. In conclusion, malvidin protects rat pial microcirculation against BCCAO/RE injury, preventing blood-brain impairment and neuronal loss. Malvidin’s effects appear to be mediated by eNOS activation and scavenger activity. PMID:27445688

  18. Pulmonary Microvascular Blood Flow in Mild Chronic Obstructive Pulmonary Disease and Emphysema. The MESA COPD Study

    PubMed Central

    Hueper, Katja; Vogel-Claussen, Jens; Parikh, Megha A.; Austin, John H. M.; Bluemke, David A.; Carr, James; Choi, Jiwoong; Goldstein, Thomas A.; Gomes, Antoinette S.; Hoffman, Eric A.; Kawut, Steven M.; Lima, Joao; Michos, Erin D.; Post, Wendy S.; Po, Ming Jack; Prince, Martin R.; Liu, Kiang; Rabinowitz, Dan; Skrok, Jan; Smith, Ben M.; Watson, Karol; Yin, Youbing; Zambeli-Ljepovic, Alan M.

    2015-01-01

    Rationale: Smoking-related microvascular loss causes end-organ damage in the kidneys, heart, and brain. Basic research suggests a similar process in the lungs, but no large studies have assessed pulmonary microvascular blood flow (PMBF) in early chronic lung disease. Objectives: To investigate whether PMBF is reduced in mild as well as more severe chronic obstructive pulmonary disease (COPD) and emphysema. Methods: PMBF was measured using gadolinium-enhanced magnetic resonance imaging (MRI) among smokers with COPD and control subjects age 50 to 79 years without clinical cardiovascular disease. COPD severity was defined by standard criteria. Emphysema on computed tomography (CT) was defined by the percentage of lung regions below −950 Hounsfield units (−950 HU) and by radiologists using a standard protocol. We adjusted for potential confounders, including smoking, oxygenation, and left ventricular cardiac output. Measurements and Main Results: Among 144 participants, PMBF was reduced by 30% in mild COPD, by 29% in moderate COPD, and by 52% in severe COPD (all P < 0.01 vs. control subjects). PMBF was reduced with greater percentage emphysema−950HU and radiologist-defined emphysema, particularly panlobular and centrilobular emphysema (all P ≤ 0.01). Registration of MRI and CT images revealed that PMBF was reduced in mild COPD in both nonemphysematous and emphysematous lung regions. Associations for PMBF were independent of measures of small airways disease on CT and gas trapping largely because emphysema and small airways disease occurred in different smokers. Conclusions: PMBF was reduced in mild COPD, including in regions of lung without frank emphysema, and may represent a distinct pathological process from small airways disease. PMBF may provide an imaging biomarker for therapeutic strategies targeting the pulmonary microvasculature. PMID:26067761

  19. Forced expirations against a variable resistance: a new chest physiotherapy method in cystic fibrosis.

    PubMed

    Oberwaldner, B; Evans, J C; Zach, M S

    1986-01-01

    Twenty patients with cystic fibrosis (CF) were trained to mobilize intrabronchial secretions by a new method of positive expiratory pressure mask (PEP mask) physiotherapy (PT). Patients repeatedly expired forcefully through the PEP mask; expiratory resistance was varied by eight different internal diameter resistors at the outlet. Forced vital capacity with the mask (FVCPEP) was determined for each resistor and was compared with the one measured without the instrument (FVC); simultaneously the sustained expiratory pressure (SEP) developed against the resistance was recorded. After training, each patient exceeded FVC with one or more resistors; "optimum" FVCPEP was 124 +/- 16% FVC at a SEP of 61 +/- 21 cm H2O. Using the PEP mask, patients cleared a higher percentage of their daily sputum volume than with conventional PT (78 +/- 22% versus 53 +/- 17%, p less than 0.01). In 11 patients (subgroup 1), multiple aspects of lung function were measured at the beginning of the study, after 10 months with PEP mask PT, after two further months without using the mask but with conventional PT, and after six more months with PEP mask PT. Results showed significantly increased expiratory flow rates, significantly decreased hyperinflation and airway instability with PEP mask PT, and a marked decline of lung function without it. The remaining nine patients (subgroup 2) entered into the same protocol; based on findings in subgroup 1 and on ethical considerations, however, the control period without PEP mask PT was then omitted, resulting in a steady and statistically significant improvement of lung function over the entire observation period. In the course of preliminary trials, two children transiently used a suboptimal resistance (FVCPEP less than FVC) and responded with a deterioration of lung function. By dilating airways and evacuating trapped gas, this method of PEP mask PT improves lung function and mucus clearance in CF. Thorough practice with the technique and frequent

  20. Cerebral microvascular effects of nimodipine in combination with soman.

    PubMed

    Koskinen, Lars-Owe D; Runnerstam, Magnus; Koch, Mona; Karlsson, Britt M

    2012-11-01

    Nimodipine, a calcium antagonist, has been shown to increase the detoxification of soman. In this study the cerebral microcirculatory effects of nimodipine and the acetylcholinesterase inhibitor soman was studied. Anaesthetised rats were administered nimodipine, 10 mg kg(-1) or vehicle intra-peritoneally, and 1h later exposed to 45 μg kg(-1) soman intravenously. The regional blood flows were measured using the microsphere method. Nimodipine and soman markedly increased the cerebral blood flow (CBF) and reduced the vascular resistance. Total CBF increased by 146% after nimodipine and by 105% after soman administration. Combined administration of nimodipine and soman caused additional but not fully additive effects on CBF and vascular resistance, indicating possible different mechanisms of the two agents. A part of the nimodipine induced increased detoxification after AChE-inhibition may be associated with this cerebral vasodilation.

  1. Microvascular Injury in Ketamine-Induced Bladder Dysfunction

    PubMed Central

    Lin, Chih-Chieh; Lin, Alex Tong-Long; Yang, An-Hang; Chen, Kuang-Kuo

    2016-01-01

    The pathogenesis of ketamine-induced cystitis (KC) remains unclear. In this study, bladder microvascular injury was investigated as a possible contributing mechanism. A total of 36 KC patients with exposure to ketamine for more than 6 months, and 9 control subjects, were prospectively recruited. All participants completed questionnaires, including the O’Leary–Sant interstitial cystitis symptom index (ICSI) and the interstitial cystitis problem index (ICPI). All KC patients received a urodynamic study and radiological exams. Bladder tissues were obtained from cystoscopic biopsies in the control group and after hydrodistention in the KC group. Double-immunofluorescence staining of N-methyl-d-aspartate receptor subunit 1 (NMDAR1) and the endothelial marker, cluster of differentiation 31 (CD31), was performed to reveal the existence of NMDAR1 on the endothelium. Electron microscopy (EM) was applied to assess the microvascular change in the urinary bladder and to measure the thickening of the basement membrane (BM). A proximity ligation assay (PLA) was used to quantify the co-localization of the endothelial CD31 receptor and the mesenchymal marker [fibroblast-specific protein 1 (FSP-1)]. The Mann–Whitney U test and Spearman’s correlation coefficient were used for statistical analysis. The mean ICSI [14.38 (± 4.16)] and ICPI [12.67 (± 3.54)] scores of the KC group were significantly higher than those (0 and 0, respectively) of the control group (both p < 0.001). The KC patients had decreasing cystometric bladder capacity (CBC) with a mean volume of 65.38 (± 48.67) mL. NMDAR1 was expressed on endothelial cells in both groups under immunofluorescence staining. Moreover, KC patients had significant BM duplication of microvessels in the mucosa of the urinary bladder under EM. The co-expression of the endothelial marker CD31 and mesenchymal marker FSP1 was significantly stained and calculated under PLA. In conclusion, microvascular injury and mesenchymal phenotypic

  2. Intrinsic sex-specific differences in microvascular endothelial cell phosphodiesterases

    PubMed Central

    Bingaman, Susan; Huxley, Virginia H.

    2010-01-01

    The importance of gonadal hormones in the regulation of vascular function has been documented. An alternate and essential contribution of the sex chromosomes to sex differences in vascular function is poorly understood. We reported previously sex differences in microvessel permeability (Ps) responses to adenosine that were mediated by the cAMP signaling pathway (Wang J, PhD thesis, 2005; Wang J and Huxley V, Proceedings of the VIII World Congress of Microcirculation, 2007; Wang J and Huxley VH, Am J Physiol Heart Circ Physiol 291: H3094–H3105, 2006). The two cyclic nucleotides, cAMP and cGMP, central to the regulation of vascular barrier integrity, are hydrolyzed by phosphodiesterases (PDE). We hypothesized that microvascular endothelial cells (EC) would retain intrinsic and inheritable sexually dimorphic genes with respect to the PDEs modulating EC barrier function. Primary cultured microvascular EC from skeletal muscles isolated from male and female rats, respectively, were used. SRY (a sex-determining region Y gene) mRNA expression was observed exclusively in male, not female, cells. The predominant isoform among PDE1–5, present in both XY and XX EC, was PDE4. Expression mRNA levels of PDE1A (male > female) and PDE3B (male < female) were sex dependent; PDE2A, PDE4D, and PDE5A were sex independent. Barrier function, Ps, was determined from measures of albumin flux across confluent primary cultured microvessel XY and XX EC monolayers. Consistent with intact in situ microvessels, basal monolayer Ps did not differ between XY (1.7 ± 0.2 × 10−6 cm/s; n = 8) and XX (1.8 ± 0.1 × 10−6 cm/s; n = 10) EC. Cilostazol, a PDE3 inhibitor, reduced (11%, P < 0.05) Ps in XX, not XY, cells. These findings demonstrate the presence and maintenance of intrinsic sex-related differences in gene expression and cellular phenotype by microvascular EC in a gonadal-hormone-free environment. Furthermore, intrinsic cell-sex likely contributes significantly to sexual dimorphism in

  3. Microvascular Injury in Ketamine-Induced Bladder Dysfunction.

    PubMed

    Lin, Chih-Chieh; Lin, Alex Tong-Long; Yang, An-Hang; Chen, Kuang-Kuo

    2016-01-01

    The pathogenesis of ketamine-induced cystitis (KC) remains unclear. In this study, bladder microvascular injury was investigated as a possible contributing mechanism. A total of 36 KC patients with exposure to ketamine for more than 6 months, and 9 control subjects, were prospectively recruited. All participants completed questionnaires, including the O'Leary-Sant interstitial cystitis symptom index (ICSI) and the interstitial cystitis problem index (ICPI). All KC patients received a urodynamic study and radiological exams. Bladder tissues were obtained from cystoscopic biopsies in the control group and after hydrodistention in the KC group. Double-immunofluorescence staining of N-methyl-d-aspartate receptor subunit 1 (NMDAR1) and the endothelial marker, cluster of differentiation 31 (CD31), was performed to reveal the existence of NMDAR1 on the endothelium. Electron microscopy (EM) was applied to assess the microvascular change in the urinary bladder and to measure the thickening of the basement membrane (BM). A proximity ligation assay (PLA) was used to quantify the co-localization of the endothelial CD31 receptor and the mesenchymal marker [fibroblast-specific protein 1 (FSP-1)]. The Mann-Whitney U test and Spearman's correlation coefficient were used for statistical analysis. The mean ICSI [14.38 (± 4.16)] and ICPI [12.67 (± 3.54)] scores of the KC group were significantly higher than those (0 and 0, respectively) of the control group (both p < 0.001). The KC patients had decreasing cystometric bladder capacity (CBC) with a mean volume of 65.38 (± 48.67) mL. NMDAR1 was expressed on endothelial cells in both groups under immunofluorescence staining. Moreover, KC patients had significant BM duplication of microvessels in the mucosa of the urinary bladder under EM. The co-expression of the endothelial marker CD31 and mesenchymal marker FSP1 was significantly stained and calculated under PLA. In conclusion, microvascular injury and mesenchymal phenotypic

  4. Role of C-reactive protein in determining microvascular function in patients with non-ST-segment elevation acute coronary syndrome undergoing percutaneous coronary intervention.

    PubMed

    Sezer, Murat; Akdeniz, Cansu; Aslanger, Emre; Kaplan, Abdullah; Yilmaz, Akar; Guz, Goksel; Umman, Berrin; Bugra, Zehra; Umman, Sabahattin

    2013-06-15

    The extent of coronary microvascular dysfunction might be related, not only to patient characteristics and procedural factors, but also to the inflammatory status. The aim of the present study was to examine a possible association between inflammation, as reflected by the serum C-reactive protein (CRP) levels, and the extent of baseline and post-percutaneous coronary intervention (PCI) coronary microvascular dysfunction in patients with non-ST-segment elevation acute coronary syndrome undergoing PCI. A total of 42 patients undergoing PCI for non-ST-segment elevation acute coronary syndrome were enrolled. Coronary microvascular resistance (MR) was determined in the territory of culprit artery using a Doppler probe- and a pressure sensor-equipped guidewire both before (taking the collateral blood into account) and after PCI. The periprocedural changes in MR were calculated. The CRP levels at admission were correlated with the pre-PCI MR (r = 0.498, p = 0.001), post-PCI MR (r = 0.429, p = 0.005), and periprocedural changes in MR (r = 0.785, p <0.001). On multivariate regression analysis, the only predictor of the pre-PCI (β = 0.531, p = 0.002) and post-PCI (β = 0.471, p = 0.012) MR was the serum CRP concentration. Likewise, the periprocedural changes in MR was predicted by the serum CRP levels (β = 0.677, p = 0.001) and the presence of angiographic thrombus (β = -0.275, p = 0.02). In conclusion, these results have shown that the CRP level is related to increased coronary MR in the territory of the culprit lesion. This suggests that inflammatory processes might play a role in microvascular impairment in patients with non-ST-segment elevation acute coronary syndrome. PMID:23558042

  5. Short-term microvascular response of striated muscle to cp-Ti, Ti-6Al-4V, and Ti-6Al-7Nb.

    PubMed

    Pennekamp, Peter H; Gessmann, Jan; Diedrich, Oliver; Burian, Björn; Wimmer, Markus A; Frauchiger, Vinzenz M; Kraft, Clayton N

    2006-03-01

    Due to excellent mechanical properties and good corrosion resistance, titanium-aluminium-vanadium (Ti-6Al-4V) and titanium-aluminium-niobium (Ti-6Al-7Nb) are extensively used for orthopedic surgery. Concern has been voiced concerning the implications of the constituent vanadium in Ti-6Al-4V on the surrounding environment. Particularly in osteosynthesis where the alloys stand in direct contact to skeletal muscle, undesirable biologic reactions may have severe consequences. In a comparative study, we assessed in vivo nutritive perfusion and leukocytic response of striated muscle to the metals Ti-6Al-4V, Ti-6Al-7Nb, and commercially pure titanium (cpTi), thereby drawing conclusions on their short-term inflammatory potential. In 28 hamsters, utilizing the dorsal skinfold chamber preparation and intravital microscopy, we quantified primary and secondary leukocyte-endothelial cell interaction, leukocyte extravasation, microvascular diameter change, and capillary perfusion in collecting and postcapillary venules of skeletal muscle. A manifest discrepancy between the metals concerning impact on local microvascular parameters was not found. All metals induced an only transient and moderate inflammatory response. Only a slight increase in leukocyte recruitment and a more sluggish recuperation of inflammatory parameters in animals treated with Ti-6Al-4V compared to the other two metals suggested a minor, overall not significant discrepancy in biocompatibility. Gross toxicity of bulk Ti-6Al-4V on surrounding tissue could not be found. Conclusively, the commonly used biomaterials Ti-6Al-4V, Ti-6Al-7Nb, and cpTi induce an only transient inflammatory answer of the skeletal muscle microvascular system. Our results indicate that on the microvascular level the tested bulk Ti-alloys and cpTi do not cause adverse biologic reactions in striated muscle.

  6. Structural characteristics and physicochemical properties of lotus seed resistant starch prepared by different methods.

    PubMed

    Zeng, Shaoxiao; Wu, Xiaoting; Lin, Shan; Zeng, Hongliang; Lu, Xu; Zhang, Yi; Zheng, Baodong

    2015-11-01

    Lotus seed resistant starch (LRS) is commonly known as resistant starch type 3 (LRS3). The objective of this study was to investigate the effect of different preparation methods on the structural characteristics and physicochemical properties of LRS3. The molar mass of LRS3 prepared by autoclaving method (GP-LRS3) and ultrasonic-autoclaving method (UP-LRS3) was mainly distributed in the range 1.0 × 10(4)-2 × 10(4) g/mol while a decrease of LRS3 prepared by microwave-moisture method (MP-LRS3) was observed. The particle of MP-LRS3 was smaller and relatively smoother while UP-LRS3 was bigger and rougher compared to GP-LRS3. Among these samples, GP-LRS3 exhibited the highest degree of ordered structure and crystallinity, the amorphous region of MP-LRS3 was the biggest and UP-LRS3 displayed the highest degree of double helical structure. Additionally, MP-LRS3 displayed the strongest solubility and swelling power while UP-LRS3 exhibited the strongest iodine absorption ability and thermostability, which were affected by their structural characteristics. PMID:25976813

  7. Structural characteristics and physicochemical properties of lotus seed resistant starch prepared by different methods.

    PubMed

    Zeng, Shaoxiao; Wu, Xiaoting; Lin, Shan; Zeng, Hongliang; Lu, Xu; Zhang, Yi; Zheng, Baodong

    2015-11-01

    Lotus seed resistant starch (LRS) is commonly known as resistant starch type 3 (LRS3). The objective of this study was to investigate the effect of different preparation methods on the structural characteristics and physicochemical properties of LRS3. The molar mass of LRS3 prepared by autoclaving method (GP-LRS3) and ultrasonic-autoclaving method (UP-LRS3) was mainly distributed in the range 1.0 × 10(4)-2 × 10(4) g/mol while a decrease of LRS3 prepared by microwave-moisture method (MP-LRS3) was observed. The particle of MP-LRS3 was smaller and relatively smoother while UP-LRS3 was bigger and rougher compared to GP-LRS3. Among these samples, GP-LRS3 exhibited the highest degree of ordered structure and crystallinity, the amorphous region of MP-LRS3 was the biggest and UP-LRS3 displayed the highest degree of double helical structure. Additionally, MP-LRS3 displayed the strongest solubility and swelling power while UP-LRS3 exhibited the strongest iodine absorption ability and thermostability, which were affected by their structural characteristics.

  8. A STUDY ON THE EARTHQUAKE RESPONSE AND EARTHQUAKE RESISTANT DESIGN METHOD OF AN OPEN TYPE WHARF WITH PNEUMATIC CAISSONS

    NASA Astrophysics Data System (ADS)

    Oishi, Masahiko; Nagao, Takashi; Shigeki, Kouji; Ouchi, Masatoshi; Sato, Yuske; Kinomiya, Osamu

    Seismic response of an open type wharf with pneumatic caisson was clarified using a dynamic finite element method. As a result, rocking behavior of caisson foundations were observed and applicability of a frame model analysis to the earthquake resistant design of a wharf was suggested. Authors proposed the framework of earthquake resistant design method of the wharf including the evaluation method of response acceleration of the wharf.

  9. New technique to quantitate regional pulmonary microvascular transit times from dynamic x-ray CT images

    NASA Astrophysics Data System (ADS)

    Tajik, Jehangir K.; Tran, Binh Q.; Hoffman, Eric A.

    1998-07-01

    Microvascular red blood cell mean transit time is a crucial parameter underlying basic pulmonary physiology. Dynamic x-ray CT imaging during bolus radiopaque tracer injection offers the ability to make functional measurements throughout the lungs, but is not able to resolve individual microvascular beds. We have implemented a model-free Fast Fourier Transform deconvolution algorithm to extract the microvascular transport characteristics from the acquired time-intensity data. The deconvolved feeding arterial bolus input curves and corresponding regional pulmonary parenchymal 'response' functions provide measures of regional pulmonary tracer residence times, allowing calculation of microvascular transit times for different spatial regions of the pulmonary system. The acquired feeding (main) pulmonary artery and regional pulmonary parenchyma time-intensity curves were fit to gamma variate functions which were then sampled with a temporal resolution of 0.1 seconds. Deconvolution of the feeding arterial and regional parenchymal curves consistently results in bimodal regional residue functions. The two modes consist of a relatively large, sharp, narrow peak approximating a delta function followed by a smaller more dispersed curve. The sharp, narrow peak appears to be due to small artery inclusion in the sampled parenchymal region (partial volume effects). The magnitude of the dominant arterial peak decreases as sampling locations are moved from the less expanded dependent to the more expanded non-dependent lung regions of supine dogs. Mathematical separation of the two modes allowed isolation of the arterial and microvascular components. The shape and transit times of the putative microvascular components agree well with results from similar measurements via microfocal angiography and in vivo microscopy. Reconvolving the microvascular component with the input curve results in a corrected parenchymal curve representing the regional microvascular transport characteristics

  10. [Psychological resistances of women to the principal female methods of contraception. Clinical classification].

    PubMed

    Wauty-Dancot, M C; Rucquoy, G

    1975-01-01

    According to the literature and to the experience of the authors gathered at the family department at the Louvain Faculty of Medicine, these psychological resistances may schematically be classified as follows: normative and socio-cultural resistances; medical resistances (wish of pregnancy, personality traits, narcissm, sexual and technical resistances); psychopathological resistances (unspecific neurotic behavior, phobias, hypochondriasis, obsessive-compulsive neurosis, character neurosis); secondary resistances. PMID:1232762

  11. An extended L-curve method for choosing a regularization parameter in electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Xu, Yanbin; Pei, Yang; Dong, Feng

    2016-11-01

    The L-curve method is a popular regularization parameter choice method for the ill-posed inverse problem of electrical resistance tomography (ERT). However the method cannot always determine a proper parameter for all situations. An investigation into those situations where the L-curve method failed show that a new corner point appears on the L-curve and the parameter corresponding to the new corner point can obtain a satisfactory reconstructed solution. Thus an extended L-curve method, which determines the regularization parameter associated with either global corner or the new corner, is proposed. Furthermore, two strategies are provided to determine the new corner-one is based on the second-order differential of L-curve, and the other is based on the curvature of L-curve. The proposed method is examined by both numerical simulations and experimental tests. And the results indicate that the extended method can handle the parameter choice problem even in the case where the typical L-curve method fails. Finally, in order to reduce the running time of the method, the extended method is combined with a projection method based on the Krylov subspace, which was able to boost the extended L-curve method. The results verify that the speed of the extended L-curve method is distinctly improved. The proposed method extends the application of the L-curve in the field of choosing regularization parameter with an acceptable running time and can also be used in other kinds of tomography.

  12. Methods to determine resistance to anthelmintics when continuing larval development occurs.

    PubMed

    Lyndal-Murphy, M; Swain, A J; Pepper, P M

    2014-01-31

    The in vivo faecal egg count reduction test (FECRT) is the most commonly used test to detect anthelmintic resistance (AR) in gastrointestinal nematodes (GIN) of ruminants in pasture based systems. However, there are several variations on the method, some more appropriate than others in specific circumstances. While in some cases labour and time can be saved by just collecting post-drench faecal worm egg counts (FEC) of treatment groups with controls, or pre- and post-drench FEC of a treatment group with no controls, there are circumstances when pre- and post-drench FEC of an untreated control group as well as from the treatment groups are necessary. Computer simulation techniques were used to determine the most appropriate of several methods for calculating AR when there is continuing larval development during the testing period, as often occurs when anthelmintic treatments against genera of GIN with high biotic potential or high re-infection rates, such as Haemonchus contortus of sheep and Cooperia punctata of cattle, are less than 100% efficacious. Three field FECRT experimental designs were investigated: (I) post-drench FEC of treatment and controls groups, (II) pre- and post-drench FEC of a treatment group only and (III) pre- and post-drench FEC of treatment and control groups. To investigate the performance of methods of indicating AR for each of these designs, simulated animal FEC were generated from negative binominal distributions with subsequent sampling from the binomial distributions to account for drench effect, with varying parameters for worm burden, larval development and drench resistance. Calculations of percent reductions and confidence limits were based on those of the Standing Committee for Agriculture (SCA) guidelines. For the two field methods with pre-drench FEC, confidence limits were also determined from cumulative inverse Beta distributions of FEC, for eggs per gram (epg) and the number of eggs counted at detection levels of 50 and 25. Two

  13. Attempts to Improve the Method of Screening Cowpea Germplasm for Resistance to Cucumber Mosaic Virus and Blackeye Cowpea Mosaic Virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Use of visual symptom screening for cowpea plants in field plots improved screening for Blackeye Cowpea Mosaic Virus (BICMV)-resistance. However, the method failed to improve the speed or accuracy of screening for Cucumber Mosaic Virus (CMV)-resistance. Plants that displayed few visual virus sympt...

  14. Blood flow in microvascular networks: A study in nonlinear biology

    PubMed Central

    Geddes, John B.; Carr, Russell T.; Wu, Fan; Lao, Yingyi; Maher, Meaghan

    2010-01-01

    Plasma skimming and the Fahraeus–Lindqvist effect are well-known phenomena in blood rheology. By combining these peculiarities of blood flow in the microcirculation with simple topological models of microvascular networks, we have uncovered interesting nonlinear behavior regarding blood flow in networks. Nonlinearity manifests itself in the existence of multiple steady states. This is due to the nonlinear dependence of viscosity on blood cell concentration. Nonlinearity also appears in the form of spontaneous oscillations in limit cycles. These limit cycles arise from the fact that the physics of blood flow can be modeled in terms of state dependent delay equations with multiple interacting delay times. In this paper we extend our previous work on blood flow in a simple two node network and begin to explore how topological complexity influences the dynamics of network blood flow. In addition we present initial evidence that the nonlinear phenomena predicted by our model are observed experimentally. PMID:21198135

  15. Diabetic microvascular complications: possible targets for improved macrovascular outcomes

    PubMed Central

    D’Elia, John A; Bayliss, George; Roshan, Bijan; Maski, Manish; Gleason, Ray E; Weinrauch, Larry A

    2011-01-01

    The results of recent outcome trials challenge hypotheses that tight control of both glycohemoglobin and blood pressure diminishes macrovascular events and survival among type 2 diabetic patients. Relevant questions exist regarding the adequacy of glycohemoglobin alone as a measure of diabetes control. Are we ignoring mechanisms of vasculotoxicity (profibrosis, altered angiogenesis, hypertrophy, hyperplasia, and endothelial injury) inherent in current antihyperglycemic medications? Is the polypharmacy for lowering cholesterol, triglyceride, glucose, and systolic blood pressure producing drug interactions that are too complex to be clinically identified? We review angiotensin–aldosterone mechanisms of tissue injury that magnify microvascular damage caused by hyperglycemia and hypertension. Many studies describe interruption of these mechanisms, without hemodynamic consequence, in the preservation of function in type 1 diabetes. Possible interactions between the renin–angiotensin–aldosterone system and physiologic glycemic control (through pulsatile insulin release) suggest opportunities for further clinical investigation. PMID:21694944

  16. Diagnosis of coronary microvascular dysfunction – Present status

    PubMed Central

    Mittal, S.R.

    2015-01-01

    Definite clinical diagnosis of microvascular angina is not possible with the existing knowledge. Resting electrocardiogram may be normal, and exercise electrocardiogram may be unremarkable. Echocardiography usually does not show regional wall motion abnormalities. Transthoracic Doppler echocardiography can satisfactorily evaluate only left anterior descending coronary artery and that too in some patients. Radio-isotope imaging can detect only severe localized disease. Noninvasive diagnosis needs high index of suspicion. At present, definite diagnosis is based on documentation of normal epicardial coronaries, coronary flow reserve less than 2.5 on adenosine induced hyperemia, and absence of spasm of epicardial coronaries on acetylcholine provocation. Invasive evaluation is costly, needs sophisticated equipments and expertise. Therapeutic and prognostic implications of various parameters remains to be evaluated. At present invasive evaluation is recommended only for patients with intractable symptoms with unconfirmed diagnosis, requiring repeated hospitalization and evaluation with failure of empirical therapy. PMID:26702685

  17. A simple classification method for residual antibiotics using E. coli cells transformed by the calcium chloride method and drug resistance plasmid DNA.

    PubMed

    Lin, S Y; Kondo, F

    2001-01-01

    Using three different plasmid DNA codings for kanamycin (KM), chloramphenicol (CP), and ampicillin- (AMP) and tetracycline- (TC) resistance, four different competent Escherichia coli strains were transformed by the calcium chloride method to produce KM-, CP- and AMP- and TC-resistant strains. Evaluation of minimum inhibitory concentrations (MIC) of 22 antibiotics, showed KM-resistant E. coli to be cross resistant only to fradiomycin (FRM); CP-resistant E. coli, especially HB101 and JM109 strains, exhibited cross-resistance only to thiamphenicol (TP). On the other hand, AMP- and TC-resistant E. coli showed cross resistance to several penicillins, tetracyclines and erythromycin. E. coli ATCC-27166, the strain most sensitive to all drugs in this experiment, was employed for disc diffusion experiments and from the pattern of appearance of the inhibition zone, eight major antibiotics were divided into three groups depending on their activity against containing each of the three plasmids. Only gentamicin (GM) activity was not affected by any of the drug resistant strains. Assay techniques utilizing three resistant strains may be the technique for screening foods for antibiotic residues in the future.

  18. Selection methods for resistance to and tolerance of helminths in livestock

    PubMed Central

    McManus, Concepta; Paim, Tiago do Prado; de Melo, Cristiano Barros; Brasil, Bruno S. A. F.; Paiva, Samuel R.

    2014-01-01

    Helminthiases are among the most important livestock diseases worldwide, in particular for small ruminants, which are the focus of this review. Resource Allocation Theory implies that high-productivity farm animals proportionate insufficient resources for adequate coping with stressful conditions. Significant differences between breeds and within breeds are seen, as well as genotype vs. environment interactions. With improvement of genetic host resistance to infection, transmission of infection will be impacted. On the other hand, genetic improvement of resilience can lead to a reduction in clinical signs of disease, but not necessarily reduce transmission of infection to other animals. Faecal egg count (FEC) is the main measurement used to evaluate helminthiasis load, despite the fact that the protocols and analytical methods can affect the results, and the FEC data frequently shows aggregative, negative skewed distribution, and a high coefficient of variation. Mass selection where heritability is generally medium to low generally produces slow results and low economic returns. Many studies have been published linking resistance to nematodes in livestock to Quantitative Trait Loci and most studies have concentrated on chromosomes where the major histocompatibility complex region is located. Nevertheless, these complex traits have been seen to be affected by thousands of variants that each has a small effect. More recent studies have shown that genome-wide selection strategies can be useful in selecting animals for improved production and resistance traits in this case. PMID:25350972

  19. Selection methods for resistance to and tolerance of helminths in livestock.

    PubMed

    McManus, Concepta; do Prado Paim, Tiago; de Melo, Cristiano Barros; Brasil, Bruno S A F; Paiva, Samuel R

    2014-01-01

    Helminthiases are among the most important livestock diseases worldwide, in particular for small ruminants, which are the focus of this review. Resource Allocation Theory implies that high-productivity farm animals proportionate insufficient resources for adequate coping with stressful conditions. Significant differences between breeds and within breeds are seen, as well as genotype vs. environment interactions. With improvement of genetic host resistance to infection, transmission of infection will be impacted. On the other hand, genetic improvement of resilience can lead to a reduction in clinical signs of disease, but not necessarily reduce transmission of infection to other animals. Faecal egg count (FEC) is the main measurement used to evaluate helminthiasis load, despite the fact that the protocols and analytical methods can affect the results, and the FEC data frequently shows aggregative, negative skewed distribution, and a high coefficient of variation. Mass selection where heritability is generally medium to low generally produces slow results and low economic returns. Many studies have been published linking resistance to nematodes in livestock to Quantitative Trait Loci and most studies have concentrated on chromosomes where the major histocompatibility complex region is located. Nevertheless, these complex traits have been seen to be affected by thousands of variants that each has a small effect. More recent studies have shown that genome-wide selection strategies can be useful in selecting animals for improved production and resistance traits in this case.

  20. The Utility of Cardiopulmonary Exercise Testing in the Assessment of Suspected Microvascular Ischemia

    PubMed Central

    Chaudhry, Sundeep; Arena, Ross; Wasserman, Karlman; Hansen, James E.; Lewis, Gregory D.; Myers, Jonathan; Belardinelli, Romualdo; LaBudde, Brian; Menasco, Nicholas; Boden, William E.

    2010-01-01

    Evidence demonstrating the potential value of cardiopulmonary exercise testing (CPET) to accurately detect myocardial ischemia secondary to macro-vascular disease is beginning to emerge. Despite distinct mechanisms mediating ischemia in micro-vascular and macrovascular coronary artery disease (CAD), the net physiologic effect of exercise-induced left ventricular (LV) dysfunction is common to both. The abnormal physiologic response to CPET may, therefore, be similar in patients with macro- and micro-vascular ischemia. The following case report describes the CPET abnormalities in a patient with suspected microvascular CAD and the subsequent improvement in LV function following three weeks of medical therapy with the anti-ischemic drug ranolazine. PMID:19233492

  1. Oxidative stress modulates nucleobase transport in microvascular endothelial cells.

    PubMed

    Bone, Derek B J; Antic, Milica; Vilas, Gonzalo; Hammond, James R

    2014-09-01

    Purine nucleosides and nucleobases play key roles in the physiological response to vascular ischemia/reperfusion events. The intra- and extracellular concentrations of these compounds are controlled, in part, by equilibrative nucleoside transporter subtype 1 (ENT1; SLC29A1) and by equilibrative nucleobase transporter subtype 1 (ENBT1). These transporters are expressed at the membranes of numerous cell types including microvascular endothelial cells. We studied the impact of reactive oxygen species on the function of ENT1 and ENBT1 in primary (CMVEC) and immortalized (HMEC-1) human microvascular endothelial cells. Both cell types displayed similar transporter expression profiles, with the majority (>90%) of 2-chloro[(3)H]adenosine (nucleoside) uptake mediated by ENT1 and [(3)H]hypoxanthine (nucleobase) uptake mediated by ENBT1. An in vitro mineral oil-overlay model of ischemia/reperfusion had no effect on ENT1 function, but significantly reduced ENBT1 Vmax in both cell types. This decrease in transport function was mimicked by the intracellular superoxide generator menadione and could be reversed by the superoxide dismutase mimetic MnTMPyP. In contrast, neither the extracellular peroxide donor TBHP nor the extracellular peroxynitrite donor 3-morpholinosydnonimine (SIN-1) affected ENBT1-mediated [(3)H]hypoxanthine uptake. SIN-1 did, however, enhance ENT1-mediated 2-chloro[(3)H]adenosine uptake. Our data establish HMEC-1 as an appropriate model for study of purine transport in CMVEC. Additionally, these data suggest that the generation of intracellular superoxide in ischemia/reperfusion leads to the down-regulation of ENBT1 function. Modification of purine transport by oxidant stress may contribute to ischemia/reperfusion induced vascular damage and should be considered in the development of therapeutic strategies.

  2. Alteration of the sublingual microvascular glycocalyx in critically ill patients.

    PubMed

    Donati, Abele; Damiani, Elisa; Domizi, Roberta; Romano, Rocco; Adrario, Erica; Pelaia, Paolo; Ince, Can; Singer, Mervyn

    2013-11-01

    Glycocalyx degradation may contribute to microvascular dysfunction and tissue hypoperfusion during systemic inflammation and sepsis. In this observational study we evaluated the alteration of the sublingual microvascular glycocalyx in 16 healthy volunteers and 50 critically ill patients. Sidestream Dark Field images of the sublingual microcirculation were automatically analyzed by dedicated software. The Perfused Boundary Region (PBR) was calculated as the dimensions of the permeable part of the glycocalyx allowing the penetration of circulating red blood cells, providing an index of glycocalyx damage. The PBR was increased in ICU patients compared to healthy controls (2.7 [2.59-2.88] vs. 2.46 [2.37-2.59]μm, p<0.0001) and tended to be higher in the 32 septic patients compared to non-septics (2.77 [2.62-2.93] vs. 2.67 [2.55-2.75]μm, p=0.05), suggesting more severe glycocalyx alterations. A PBR of 2.76 showed the best discriminative ability towards the presence of sepsis (sensitivity: 50%, specificity: 83%; area under the receiver operating characteristic curve: 0.67, 95% CI 0.52-0.82, p=0.05). A weak positive correlation was found between PBR and heart rate (r=0.3, p=0.03). In 17 septic patients, a correlation was found between PBR and number of rolling leukocytes in post-capillary venules (RL/venule) (r=0.55, p=0.02), confirming that glycocalyx shedding enhances leukocyte-endothelium interaction.

  3. Evaluation of Microvascular Perfusion and Resuscitation after Severe Injury.

    PubMed

    Lee, Yann-Leei L; Simmons, Jon D; Gillespie, Mark N; Alvarez, Diego F; Gonzalez, Richard P; Brevard, Sidney B; Frotan, Mohammad A; Schneider, Andrew M; Richards, William O

    2015-12-01

    Achieving adequate perfusion is a key goal of treatment in severe trauma; however, tissue perfusion has classically been measured by indirect means. Direct visualization of capillary flow has been applied in sepsis, but application of this technology to the trauma population has been limited. The purpose of this investigation was to compare the efficacy of standard indirect measures of perfusion to direct imaging of the sublingual microcirculatory flow during trauma resuscitation. Patients with injury severity scores >15 were serially examined using a handheld sidestream dark-field video microscope. In addition, measurements were also made from healthy volunteers. The De Backer score, a morphometric capillary density score, and total vessel density (TVD) as cumulative vessel area within the image, were calculated using Automated Vascular Analysis (AVA3.0) software. These indices were compared against clinical and laboratory parameters of organ function and systemic metabolic status as well as mortality. Twenty severely injured patients had lower TVD (X = 14.6 ± 0.22 vs 17.66 ± 0.51) and De Backer scores (X = 9.62 ± 0.16 vs 11.55 ± 0.37) compared with healthy controls. These scores best correlated with serum lactate (TVD R(2) = 0.525, De Backer R(2) = 0.576, P < 0.05). Mean arterial pressure, heart rate, oxygen saturation, pH, bicarbonate, base deficit, hematocrit, and coagulation parameters correlated poorly with both TVD and De Backer score. Direct measurement of sublingual microvascular perfusion is technically feasible in trauma patients, and seems to provide real-time assessment of microcirculatory perfusion. This study suggests that in severe trauma, many indirect measurements of perfusion do not correlate with microvascular perfusion. However, visualized perfusion deficiencies do reflect a shift toward anaerobic metabolism. PMID:26736167

  4. Autonomic dysfunction and microvascular damage in systemic sclerosis.

    PubMed

    Di Franco, Manuela; Paradiso, Michele; Riccieri, Valeria; Basili, Stefania; Mammarella, Antonio; Valesini, Guido

    2007-08-01

    Systemic sclerosis (SSc) is a connective tissue disease characterized by vascular damage and interstizial fibrosis of many organs. Our interest was focused on the evaluation of cardiac autonomic function by measurements of heart rate variability (HRV) and microvascular damage detected by nailfold capillaroscopy (NC) in SSc patients. We examined 25 consecutive outpatients affected by systemic sclerosis and 25 healthy controls. Exclusion criteria were the presence of cardiac disease, hypertension, diabetes mellitus, or neurological diseases. All subjects underwent 24-h ambulatory ECG Holter recording and NC examination. Heart rate variability was evaluated in the time domain, using appropriate software, computing the time series of all normal-to-normal (NN) QRS intervals throughout the 24-h recording period. A semiquantitative rating scale was adopted to score the NC abnormalities, as well as a rating system for avascular areas and morphological NC patterns. In SSc patients, HRV analysis showed significantly lower values of SDNN (standard deviation of all NN intervals) (p=0.009), SDANN (standard deviation of the averages of NN intervals in all 5-min segments of the entire recording) (p=0.01), and pNN50 (the percentage of adjacent NN intervals that differed by more than 50 ms) (p=0.02), compared to the control group. These parameters in SSc patients significantly decreased with the worsening of semiquantitative capillaroscopy score. In conclusion, an abnormal autonomic nervous control of the heart might contribute to identify subclinical cardiac involvement in SSc patients. The coexistence of autonomic dysfunction with a more severe microvascular damage could be considered a potential prognostic tool in the identification of those patients particularly at risk for cardiac mortality.

  5. X-Plate Technology: a new method for detecting fluconazole resistance in Candida species.

    PubMed

    Chadwick, Sean G; Schuyler, Jessica A; Vermitsky, John-Paul; Adelson, Martin E; Mordechai, Eli; Gygax, Scott E

    2013-05-01

    Candida species are responsible for many opportunistic fungal infections. Fluconazole is a well-tolerated antifungal drug, commonly used in the treatment of candidiasis. However, with fluconazole resistance ever increasing, rapid detection and antifungal susceptibility testing of Candida is imperative for proper patient treatment. This paper reports a cost-effective, simple and rapid chromogenic agar dilution method for simultaneous Candida species identification and fluconazole susceptibility testing. The results obtained by X-Plate Technology were in absolute concordance with standard microbroth dilution assays. Analysis of 1383 clinical patient samples with suspected vulvovaginal candidiasis revealed that this technology was able to detect and speciate the Candida isolate and determine the fluconazole susceptibility. The prevalence and susceptibility profiles of the clinical isolates using this method were highly similar to published reports using the microbroth dilution method.

  6. ISO test method to determine sustained-load-cracking resistance of aluminium cylinders

    SciTech Connect

    Bhuyan, G.S.; Rana, M.D.

    1999-08-01

    Leak as well as rupture types of failures related to sustained-load-cracking (SLC) have been observed in high-pressure gas cylinders fabricated from certain aluminium alloy. The stable crack growth mechanism observed primarily in the cylinder neck and shoulder area have been identified as the SLC mechanism occurring at room temperature without any environmental effect. The International Organization for standardization (ISO) Sub-Committee 3, Working Group 16 has developed a test method to measure the SLC resistance using fracture mechanics specimens along with an acceptance criterion for aluminium cylinders. The technical rationale for the proposed test method and the physical significance of the acceptance criterion to the cylinder performance in terms of critical stress-crack size relationship is presented. Application of the developed test method for characterizing new aluminium alloy for manufacturing cylinders is demonstrated. SLC characteristics of several aluminium cylinders as well as on-board cylinders for natural gas vehicles assessed by the authors are discussed.

  7. Prediction of multi-drug resistance transporters using a novel sequence analysis method

    PubMed Central

    McDermott, Jason E.; Bruillard, Paul; Overall, Christopher C.; Gosink, Luke; Lindemann, Stephen R.

    2015-01-01

    There are many examples of groups of proteins that have similar function, but the determinants of functional specificity may be hidden by lack of sequence similarity, or by large groups of similar sequences with different functions. Transporters are one such protein group in that the general function, transport, can be easily inferred from the sequence, but the substrate specificity can be impossible to predict from sequence with current methods. In this paper we describe a linguistic-based approach to identify functional patterns from groups of unaligned protein sequences and its application to predict multi-drug resistance transporters (MDRs) from bacteria. We first show that our method can recreate known patterns from PROSITE for several motifs from unaligned sequences. We then show that the method, MDRpred, can predict MDRs with greater accuracy and positive predictive value than a collection of currently available family-based models from the Pfam database. Finally, we apply MDRpred to a large collection of protein sequences from an environmental microbiome study to make novel predictions about drug resistance in a potential environmental reservoir. PMID:26913187

  8. [A new method for evaluation of beta-lactamase production of resistant enterobacteriaceae strains (author's transl)].

    PubMed

    Schassan, H H

    1978-01-01

    Resistant strains of Enterobacteriaceae were investigated with a chemical and microbiological test on beta-lactamase activity. The chemical method was needed as screening-test basing on the enzymatic hydrolysis of the chromogenic cephalosporin compound 87/312. The microbiological test is a modified cup plate method using Staph. aureus SG 511 as sensitive test strain for penicillins and cephalosporins. In one of the two cups of the blood agar plate 20 microliter of the beta-lactam antibiotic, in the other cup 20 microliter of the supernatant of the 24 h broth of the bacterial strain was pipettet. If the lactamase in the supernatant neutralises the antibiotic, a halfemoonlike blank is forming on the left site of the inhibition zone. An unchangeable inhibition zone demonstrates stability of the antibiotic to the enzyme. Each of 10 ampicillin- and/or cephalothin-resistant strains of E. coli, Klebsiella, Enterobacter and Serratia were investigated against 6 penicillins (penicillin G, ampicillin, ticarcillin, mezlocillin, azlocillin, bay k 4999) and 6 cephalosporins (cefoxitin, cefuroxime, cefamandol, cephalothin, cefazolin, cefradine). The microbiological method allows the statement, against which beta-lactam antibiotic the enzyme is effective. A correlation between the beta-lactamase activity and the MIC values in Enterobacteriaceae was not found. PMID:371259

  9. Resistive method for measuring the disintegration speed of Prince Rupert's drops

    NASA Astrophysics Data System (ADS)

    Bochkov, Mark; Gusenkova, Daria; Glushkov, Evgenii; Zotova, Julia; Zhabin, S. N.

    2016-09-01

    We have successfully applied the resistance grid technique to measure the disintegration speed in a special type of glass objects, widely known as Prince Rupert's drops. We use a fast digital oscilloscope and a simple electrical circuit, glued to the surface of the drops, to detect the voltage changes, corresponding to the breaks in the specific parts of the drops. The results obtained using this method are in good qualitative and quantitative agreement with theoretical predictions and previously published data. Moreover, the proposed experimental setup does not include any expensive equipment (such as a high-speed camera) and can therefore be widely used in high schools and universities.

  10. Method and apparatus for remote tube crevice detection by current and voltage probe resistance measurement

    DOEpatents

    Kikta, T.J.; Mitchell, R.D.

    1992-11-24

    A method and apparatus for determining the extent of contact between an electrically conducting tube and an electrically conductive tubesheet surrounding the tube, based upon the electrical resistance of the tube and tubesheet. A constant current source is applied to the interior of the electrically conducting tube by probes and a voltmeter is connected between other probes to measure the voltage at the point of current injection, which is inversely proportional to the amount of contact between the tube and tubesheet. Namely, the higher the voltage measured by the voltmeter, the less contact between the tube and tubesheet. 4 figs.

  11. Method and apparatus for remote tube crevice detection by current and voltage probe resistance measurement

    DOEpatents

    Kikta, Thomas J.; Mitchell, Ronald D.

    1992-01-01

    A method and apparatus for determining the extent of contact between an electrically conducting tube and an electrically conductive tubesheet surrounding the tube, based upon the electrical resistance of the tube and tubesheet. A constant current source is applied to the interior of the electrically conducting tube by probes and a voltmeter is connected between other probes to measure the voltage at the point of current injection, which is inversely proportional to the amount of contact between the tube and tubesheet. Namely, the higher the voltage measured by the voltmeter, the less contact between the tube and tubesheet.

  12. New high resolution Random Telegraph Noise (RTN) characterization method for resistive RAM

    NASA Astrophysics Data System (ADS)

    Maestro, M.; Diaz, J.; Crespo-Yepes, A.; Gonzalez, M. B.; Martin-Martinez, J.; Rodriguez, R.; Nafria, M.; Campabadal, F.; Aymerich, X.

    2016-01-01

    Random Telegraph Noise (RTN) is one of the main reliability problems of resistive switching-based memories. To understand the physics behind RTN, a complete and accurate RTN characterization is required. The standard equipment used to analyse RTN has a typical time resolution of ∼2 ms which prevents evaluating fast phenomena. In this work, a new RTN measurement procedure, which increases the measurement time resolution to 2 μs, is proposed. The experimental set-up, together with the recently proposed Weighted Time Lag (W-LT) method for the analysis of RTN signals, allows obtaining a more detailed and precise information about the RTN phenomenon.

  13. Hyperbaric oxygen induces a cytoprotective and angiogenic response in human microvascular endothelial cells.

    PubMed

    Godman, Cassandra A; Chheda, Kousanee P; Hightower, Lawrence E; Perdrizet, George; Shin, Dong-Guk; Giardina, Charles

    2010-07-01

    A genome-wide microarray analysis of gene expression was carried out on human microvascular endothelial cells (HMEC-1) exposed to hyperbaric oxygen treatment (HBOT) under conditions that approximated clinical settings. Highly up-regulated genes included immediate early transcription factors (FOS, FOSB, and JUNB) and metallothioneins. Six molecular chaperones were also up-regulated immediately following HBOT, and all of these have been implicated in protein damage control. Pathway analysis programs identified the Nrf-2-mediated oxidative stress response as one of the primary responders to HBOT. Several of the microarray changes in the Nrf2 pathway and a molecular chaperone were validated using quantitative PCR. For all of the genes tested (Nrf2, HMOX1, HSPA1A, M1A, ACTC1, and FOS), HBOT elicited large responses, whereas changes were minimal following treatment with 100% O(2) in the absence of elevated pressure. The increased expression of immediate early and cytoprotective genes corresponded with an HBOT-induced increase in cell proliferation and oxidative stress resistance. In addition, HBOT treatment enhanced endothelial tube formation on Matrigel plates, with particularly dramatic effects observed following two daily HBO treatments. Understanding how HBOT influences gene expression changes in endothelial cells may be beneficial for improving current HBOT-based wound-healing protocols. These data also point to other potential HBOT applications where stimulating protection and repair of the endothelium would be beneficial, such as patient preconditioning prior to major surgery.

  14. Hepatocyte growth factor enhances the barrier function in primary cultures of rat brain microvascular endothelial cells.

    PubMed

    Yamada, Narumi; Nakagawa, Shinsuke; Horai, Shoji; Tanaka, Kunihiko; Deli, Maria A; Yatsuhashi, Hiroshi; Niwa, Masami

    2014-03-01

    The effects of hepatocyte growth factor (HGF) on barrier functions were investigated by a blood-brain barrier (BBB) in vitro model comprising a primary culture of rat brain capillary endothelial cells (RBEC). In order to examine the response of the peripheral endothelial cells to HGF, human umbilical vascular endothelial cells (HUVEC) and human dermal microvascular endothelial cells (HMVEC) were also treated with HGF. HGF decreased the permeability of RBEC to sodium fluorescein and Evans blue albumin, and dose-dependently increased transendothelial electrical resistance (TEER) in RBEC. HGF altered the immunochemical staining pattern of F-actin bands and made ZO-1 staining more distinct on the linear cell borders in RBEC. In contrast, HGF increased sodium fluorescein and Evans blue albumin permeability in HMVEC and HUVEC, and decreased TEER in HMVEC. In HMVEC, HGF reduced cortical actin bands and increased stress fiber density, and increased the zipper-like appearance of ZO-1 staining. Western blot analysis showed that HGF significantly increased the amount of ZO-1 and VE-cadherin. HGF seems to act on the BBB to strengthen BBB integrity. These findings indicated that cytoskeletal rearrangement and cell-cell adhesion, such as through VE-cadherin and ZO-1, are candidate mechanisms for the influence of HGF on the BBB. The possibility that HGF has therapeutic significance in protecting the BBB from damage needs to be considered. PMID:24370951

  15. [Posterior fossa microvascular decompression for hemifacial spasm and trigeminal neuralgia--some improvements on operative devices and technique].

    PubMed

    Hongo, K; Kobayashi, S; Takemae, T; Sugita, K

    1985-12-01

    Microvascular decompression has been widely used as a method for the treatment of hemifacial spasm and trigeminal neuralgia. We have experienced 30 such cases in the last 2 years; 25 of them were hemifacial spasm and 5 trigeminal neuralgia. Excellent results were obtained in 26 cases; the remaining two cases, both hemifacial spasm, were partially cured. Mild facial paresis appeared several days after the operation in 3 patients. In all the cases, the facial paresis recovered completely within several weeks. The cause of the facial paresis was not known. In 2 cases a slight hearing deficits were noticed after surgery, which has been gradually improving over several months. As this operation is functional surgery, operative complications must be avoided as much as possible. It has been our policy that we first try medical treatment and/or some kinds of nerve block and if no effects are obtained, we recommend the microvascular decompression. For microvascular decompression, suboccipital craniectomy is performed in lateral position. From the point of view of surgical technique, we stress several important points as follows: The head is elevated about 30 degrees, and it is kept approximately horizontal and should not be excessively rotated. Craniectomy is made as far laterally as the sigmoid sinus; its shape is elongated oval. Retraction of the cerebellum should not be done in the direction of the cranial nerves to avoid post-operative hearing deficit. Two tapered retractors are effectively used for cerebellar retraction. A third slim, tapered retractor is useful for holding an offending artery when exploring the root exit zone or placing a sponge for decompression.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:4088451

  16. Developing and Studying the Methods of Hard-Facing with Heat-Resisting High-Hardness Steels

    NASA Astrophysics Data System (ADS)

    Malushin, N. N.; Kovalev, A. P.; Valuev, D. V.; Shats, E. A.; Borovikov, I. F.

    2016-08-01

    The authors develop the methods of hard-facing of mining-metallurgic equipment parts with heat-resisting high-hardness steels on the base of plasma-jet hard-facing in the shielding-alloying nitrogen atmosphere.

  17. New method to determine the mass transfer resistance of sterile closures for shaken bioreactors.

    PubMed

    Anderlei, Tibor; Mrotzek, Christian; Bartsch, Stefan; Amoabediny, Ghassem; Peter, Cyril P; Büchs, Jochen

    2007-12-01

    In this paper a novel and easily applied method to measure the mass transfer resistance of the sterile closures (e.g. cotton plug) of shaken bioreactors is introduced. This method requires no investment in special equipment (e.g. an oxygen sensor) and can be performed with the materials usually available in typical laboratories. The method is based on the model of Henzler et al. (1986), which mechanistically describes mass transfer through the sterile closure of a shaken bioreactor based on diffusion coupled with Stefan convection. The concentration dependency of the multi-component diffusion coefficients is taken into account. The water loss from two equivalent shaken bioreactors equipped with sterile closures during several days of shaking is measured. One flask contains distilled water, the other a saturated salt solution. From the water evaporation rate in each of the two flasks, the new model presented calculates the relative humidity in the environment, the average diffusion coefficient of oxygen in the sterile closure (D(O2)), and the diffusion coefficient of carbon dioxide (D(CO2)) . The diffusion coefficient of carbon dioxide (D(CO2)) only depends on the density and material properties of the sterile closure and not on the gas concentrations and is, therefore, an ideal parameter for the characterization of the mass transfer resistance. This new method is validated experimentally by comparing the diffusion coefficient of oxygen (D(O2)) to a measurement by the classic dynamic method; and by comparing the calculated relative humidity in the environment to a humidity sensor measurement. PMID:17497734

  18. Formation Wear Resistant Coatings on Martensite Steel Hardox 450 by Welding Methods

    NASA Astrophysics Data System (ADS)

    Konovalov, S. V.; Kormyshev, V. E.; Nevskii, S. A.; Ivanov, Yu F.; Gromov, V. E.

    2016-08-01

    By methods of modern physical materials science the investigations analysis of phase composition, defect substructure, mechanical and tribological properties of Cr-Nb-C-V containing coatings formed in surfacing on martensitic wear resistant steel Hardox 450 were carried out. It was shown that surfacing resulted in the formation of high strength surface layer 6 mm in thinness. This layer had wear resistance 138 times greater than that of the base and friction coefficient 2.5 times less. Having analyzed the deflected mode of the deposited material in conditions of friction, a conclusion is drawn that plastic shear deformation is localized in the surface layer due to the high friction factor, as the result, scratches are formed. The maximum of tangential stress is deflected deep into the material provided that friction factor is low. On the basis of the investigations by methods of X-ray structural analysis and transmission diffraction electron microscopy it was shown that increase strength and tribological properties of surfacing metal were caused by its phase composition and state of defect substructure, namely, availability of interstitial phases (more than 36%) and martensitic type of a-phase structure.

  19. A method to investigate the electron scattering characteristics of ultrathin metallic films by in situ electrical resistance measurements

    SciTech Connect

    Trindade, I. G.; Sousa, J. B.; Fermento, R.; Leitao, D.

    2009-07-15

    In this article, a method to measure the electrical resistivity/conductivity of metallic thin films during layer growth on specific underlayers is described. The in situ monitoring of an underlayer electrical resistance, its change upon the incoming of new material atoms/molecules, and the growth of a new layer are presented. The method is easy to implement and allows obtaining in situ experimental curves of electrical resistivity dependence upon film thickness with a subatomic resolution, providing insight in film growth microstructure characteristics, specular/diffuse electron scattering surfaces, and optimum film thicknesses.

  20. Cost-reduction method for delamination monitoring using electrical resistance changes of CFRP beam

    NASA Astrophysics Data System (ADS)

    Todoroki, A.; Ueda, M.

    2004-02-01

    Delamination is a significant defect of laminated composites. The present study employs an electrical resistance change method in an attempt to identify internal delaminations experimentally. The method adopts reinforcing carbon fibers as sensors. In our previous paper, an actual delamination crack in a Carbon Fiber Reinforced Plastics (CFRP) laminate was experimentally identified with artificial neural networks (ANN) or response surfaces created from a large number of experiments. The experimental results were used for learning of the ANN or regression of the response surfaces. For the actual application of the method, it is indispensable to reduce the number of experiments to suppress the total experimental cost. In the present study, therefore, FEM analyses are employed to make sets of data for learning of the ANN. First, electrical conductivity of the CFRP laminate is identified by means of the least estimation error method. After that, the results of FEM analyses are used for learning of the ANN. The method is applied to actual delamination monitoring of CFRP beams. As a result, the method successfully monitored the delamination location and size only with ten experiments.

  1. Long noncoding RNA-MEG3 is involved in diabetes mellitus-related microvascular dysfunction.

    PubMed

    Qiu, Gui-Zhen; Tian, Wei; Fu, Hai-Tao; Li, Chao-Peng; Liu, Ban

    2016-02-26

    Microvascular dysfunction is an important characteristic of diabetic retinopathy. Long non-coding RNAs (lncRNAs) play important roles in diverse biological processes. In this study, we investigated the role of lncRNA-MEG3 in diabetes-related microvascular dysfunction. We show that MEG3 expression level is significantly down-regulated in the retinas of STZ-induced diabetic mice, and endothelial cells upon high glucose and oxidative stress. MEG3 knockdown aggravates retinal vessel dysfunction in vivo, as shown by serious capillary degeneration, and increased microvascular leakage and inflammation. MEG3 knockdown also regulates retinal endothelial cell proliferation, migration, and tube formation in vitro. The role of MEG3 in endothelial cell function is mainly mediated by the activation of PI3k/Akt signaling. MEG3 up-regulation may serve as a therapeutic strategy for treating diabetes-related microvascular complications. PMID:26845358

  2. SPONTANEOUSLY HYPERTENSIVE RATS ARE SUSCEPTIBLE TO MICROVASCULAR THROMBOSIS IN RESPONSE TO PARTICULATE MATTER EXPOSURE

    EPA Science Inventory

    SPONTANEOUSLY HYPERTENSIVE RATS ARE SUSCEPTIBLE TO MICROVASCULAR THROMBOSIS IN RESPONSE TO PARTICULATE MATTER EXPOSURE.
    PS Gilmour, MC Schladweiler, AD Ledbetter, and UP Kodavanti. US EPA, ORD, NHEERL, ETD, PTB, Research Triangle Park, NC USA.
    Environmental particles (PM...

  3. Genetic Studies on Diabetic Microvascular Complications: Focusing on Genome-Wide Association Studies

    PubMed Central

    Kwak, Soo Heon

    2015-01-01

    Diabetes is a common metabolic disorder with a worldwide prevalence of 8.3% and is the leading cause of visual loss, end-stage renal disease and amputation. Recently, genome-wide association studies (GWASs) have identified genetic risk factors for diabetic microvascular complications of retinopathy, nephropathy, and neuropathy. We summarized the recent findings of GWASs on diabetic microvascular complications and highlighted the challenges and our opinion on future directives. Five GWASs were conducted on diabetic retinopathy, nine on nephropathy, and one on neuropathic pain. The majority of recent GWASs were underpowered and heterogeneous in terms of study design, inclusion criteria and phenotype definition. Therefore, few reached the genome-wide significance threshold and the findings were inconsistent across the studies. Recent GWASs provided novel information on genetic risk factors and the possible pathophysiology of diabetic microvascular complications. However, further collaborative efforts to standardize phenotype definition and increase sample size are necessary for successful genetic studies on diabetic microvascular complications. PMID:26194074

  4. [Determination of the corrosion resistance of dental alloys with a new measurement method].

    PubMed

    Schmidli, Fredy; Jungo, Markus; Jäger, Kurt; Lüthy, Heinz; Büchler, Markus

    2009-01-01

    A corrosion sensor newly developed by the Swiss Society for Corrosion, modified for a potential application in the oral cavity, was tested in vitro. By measuring the impedance with a special sensor in the size of a bur handpiece, it allows a quick determination of the corrosion resistance. For the evaluation of the method, measurements were done on six conventional dental alloys (two precious alloys, one Pd-based alloy and three non-precious alloys) which had been tested in crevice corrosion by the authors in an earlier stage. Qualitatively the results are quite in concordance with the ones got with the usual tests. On the base of the present results the use directly in the oral cavity of this corrosion test method appears to be very promising.

  5. Deleterious Effects of Intra-arterial Administration of Particulate Steroids on Microvascular Perfusion in a Mouse Model.

    PubMed

    Laemmel, Elisabeth; Segal, Nicolas; Mirshahi, Massoud; Azzazene, Dalel; Le Marchand, Sylvie; Wybier, Marc; Vicaut, Eric; Laredo, Jean-Denis

    2016-06-01

    Purpose To determine the in vivo effects of several particulate steroids on microvascular perfusion by using intravital microscopy in a mice model and to investigate the in vitro interactions between these particulate steroids and red blood cells (RBCs). Materials and Methods The study was conducted in agreement with the guidelines of the National Committee of Ethic Reflection on Animal Experimentation. By using intravital microscopy of mouse cremaster muscle, the in vivo effects of several particulate steroids on microvascular perfusion were assessed. Four to five mice were allocated to each of the following treatment groups: saline solution, dexamethasone sodium phosphate, a nonparticulate steroid, and the particulate steroids cortivazol, methylprednisolone, triamcinolone, and prednisolone. By using in vitro blood microcinematography and electron microscopy, the interactions between these steroids and human RBCs were studied. All results were analyzed by using nonparametric tests. Results With prednisolone, methylprednisolone, or triamcinolone, blood flow was rapidly and completely stopped in all the arterioles and venules (median RBC velocity in first-order arterioles, 5 minutes after administration was zero for these three groups) compared with a limited effect in mice treated with saline, dexamethasone, and cortivazol (20.3, 21.3, and 27.5 mm/sec, respectively; P < .003). This effect was associated with a large decrease in the functional capillary density (4.21, 0, and 0 capillaries per millimeter for methylprednisolone, triamcinolone, or prednisolone, respectively, vs 21.0, 21.4, and 19.1 capillaries per millimeter in mice treated with saline, dexamethasone, and cortivazol, respectively; P < .003). This was because of the rapid formation of RBC aggregates. However, no change in microvascular perfusion was associated with administration of cortivazol or dexamethasone. In vitro experiments confirmed the formation of RBC aggregates associated with the

  6. Influence of microvascular dysfunction on regional myocardial deformation post-acute myocardial infarction: insights from a novel angiographic index for assessing myocardial tissue-level reperfusion.

    PubMed

    He, Ben; Ding, Song; Qiao, Zhiqing; Gao, Lincheng; Wang, Wei; Ge, Heng; Shen, Xuedong; Pu, Jun

    2016-05-01

    To investigate the impact of microvascular dysfunction assessed by angiography on myocardial deformation assessed by two-dimensional speckle-tracking echocardiography in ST-segment elevation myocardial infarction (STEMI). A total of 121 STEMI patients who received primary percutaneous coronary intervention were included. Thrombolysis in myocardial infarction, Myocardial Perfusion Frame Count (TMPFC), a novel angiographic method to assess myocardial perfusion, was used to evaluate microvascular dysfunction. Two-dimensional speckle-tracking echocardiography was performed at 3-7 days after reperfusion. The infarction related regional longitudinal (RLS) strains as well as circumferential (RCS) and radial (RRS) ones, along with global longitudinal, circumferential (GCS), and radial (GRS) strains were measured. Patients with microvascular dysfunction had decreased peak amplitude of RLS (p = 0.012), RCS (p < 0.001), RRS (p = 0.012) at the regional level and decreased peak amplitude of GCS (p = 0.005), GRS (p = 0.012) at the global level. The RCS to RLS and RCS to RRS ratios were significantly different between patients without than with microvascular dysfunction (1.28 ± 0.31 vs. 1.07 ± 0.47, p = 0.027 and 0.69 ± 0.33 vs. 0.56 ± 0.28, p = 0.047). Receiver operator characteristics curves identified a cutoff value of 94 frames for TMPFC to differentiate between normal and abnormal wall motion score index in the sub-acute phase of STEMI (AUC = 0.72; p < 0.001). In the sub-acute phase of STEMI, the presence of microvascular dysfunction in infarcted tissue relates to reduced global and regional myocardial deformation. RCS alterations were more significant than RLS and RRS between patients with than without microvascular dysfunction. TMPFC was useful to predict left ventricular systolic dysfunction in the sub-acute phase of STEMI.

  7. Visualization of microvascularity in glioblastoma multiforme with 8-T high-spatial-resolution MR imaging.

    PubMed

    Christoforidis, Gregory A; Grecula, John C; Newton, Herbert B; Kangarlu, Allahyar; Abduljalil, Amir M; Schmalbrock, Petra; Chakeres, Donald W

    2002-10-01

    We used 8-T high-spatial-resolution gradient-echo MR imaging to directly visualize microvascularity in pathologically proved glioblastoma multiforme. Images were compared with 1.5-T high-spatial-resolution fast spin-echo T2-weighted images and digital subtraction angiograms. Preliminary data indicate that 8-T high-spatial-resolution MR imaging may enable the identification of areas of abnormal microvascularity in glioblastoma multiforme that are not visible with other routine clinical techniques.

  8. [THE AGING OF MICROVASCULAR NETWORK FORMED IN CORTEX FOLLOWING INTRACEREBRAL TRANSPLANTATION OF MESENCHYMAL STEM CELLS].

    PubMed

    Sokolova, I B; Anisimov, S V; Puzanov, M V; Sergeev, I V; Dvoretskiĭ, D P

    2015-01-01

    Using a TV device to study microcirculation in brain we found that intracerebral transplantation of mesenchymal stem cells to 12-months old rats led to a significant increase (circa 1,5-fold times) of microvascular density in pia tissue and to increased constriction reactions of pia arterioles in response to noradrenalin application on a brain surface. Both microvascular density and pia arterioles reactivity was completely preserved in aging until 22-24 months. PMID:26390610

  9. Microvascular patterns in the blubber of shallow and deep diving odontocetes.

    PubMed

    McClelland, Sara J; Gay, Mark; Pabst, D Ann; Dillaman, Richard; Westgate, Andrew J; Koopman, Heather N

    2012-08-01

    Blubber, a specialized form of subdermal adipose tissue, surrounds marine mammal bodies. Typically, adipose tissue is perfused by capillaries but information on blubber vascularization is lacking. This study's goals were to: 1) describe and compare the microvasculature (capillaries, microarterioles, and microvenules) of blubber across odontocete species; 2) compare microvasculature of blubber to adipose tissue; and 3) examine relationships between blubber's lipid composition and its microvasculature. Percent microvascularity, distribution, branching pattern, and diameter of microvessels were determined from images of histochemically stained blubber sections from shallow-diving bottlenose dolphins (Tursiops truncatus), deeper-diving pygmy sperm whales (Kogia breviceps), deep-diving beaked whales (Mesoplodon densirostris; Ziphius cavirostris), and the subdermal adipose tissue of domestic pigs (Sus scrofa). Tursiops blubber showed significant stratification in percent microvascularity among the superficial, middle, and deep layers and had a significantly higher percent microvascularity than all other animals analyzed, in which the microvasculature was more uniformly distributed. The percent microvasculature of Kogia blubber was lower than that of Tursiops but higher than that of beaked whales and the subdermal adipose tissue of domestic pigs. Tursiops had the most microvascular branching. Microvessel diameter was relatively uniform in all species. There were no clear patterns associating microvascular and lipid characteristics. The microvascular characteristics of the superficial layer of blubber resembled the adipose tissue of terrestrial mammals, suggesting some conservation of microvascular patterns in mammalian adipose tissue. The middle and deep layers of blubber, particularly in Tursiops, showed the greatest departure from typical mammalian microvascular arrangement. Factors such as metabolics or thermoregulation may be influencing the microvasculature in these

  10. a Method of Measuring the Dynamic Flow Resistance and the Acoustic Measurement of the Effective Static Flow Resistance in Stratified Rockwool Samples

    NASA Astrophysics Data System (ADS)

    Picard, M. A.; Solana, P.; Urchueguía, J. F.

    1998-09-01

    In our work we have analyzed different stratified rockwool samples, with considerable differences regarding density, mean pore diameter, and porosity, by means of a new method for the measurement of the dynamic flow resistance based on the electrical analogy. This method enables us to measure this parameter without the need for placing the sample between two microphones. Our experimental results have been compared to those obtained with a different measurement scheme and, from a theoretical point of view, we have examined the extent to which the capillary pore approximation can be utilized in intermediate flow regimes and Poiseuille flow regimes and in real situations. For this purpose, a static flow resistivity, which was also approximated using an acoustic method and a commonly accepted theoretical approximation, was calculated based on a microscopic study of the samples and the fibre's diameter. Regarding the conclusions obtained, the results show that the new experimental procedure for determining the dynamic flow resistance is of interest in the intermediate and Poiseuille flow regimes in which, within the limitation of our experimental set-up, good results were obtained. The acoustic procedure for measuring a static flow resistivity delivered good results only for a regime close to Poiseuille, which was obtained only with higher density samples.

  11. Syndrome of diminished vasodilator reserve of the coronary microcirculation (microvascular angina or syndrome X): Diagnosis by combined atrial pacing and thallium 201 imaging--a case report

    SciTech Connect

    Magarian, G.J.; Palac, R.; Reinhart, S. )

    1990-08-01

    Patients with angina-like chest pain without evidence of epicardial coronary artery disease or coronary arterial vasospasm are becoming increasingly recognized. These are often related to noncardiac causes including esophageal, musculoskeletal, and hyperventilatory or panic states. However, recently a subgroup of such patients are being recognized as having true myocardial ischemia and chest pain on the basis of diminished coronary microvascular vasodilatory reserve (microvascular ischemia or Syndrome X). The authors describe such a patient who was found to have replication of anginal pain associated with a reversible ischemic defect on thallium 201 imaging during atrial pacing, suggesting ischemia in this myocardial segment. Resolution of angina and ST segment electrocardiographic changes of ischemia occurred with cessation of pacing. We believe this is the first report of a patient with this form of myocardial ischemia diagnosed by this method and should be considered in patients with anginal chest pain after significant coronary artery disease and coronary vasospasm have been excluded.

  12. A New Matching Method for the Resistive Wall Mode Analysis of Rotating Plasmas

    NASA Astrophysics Data System (ADS)

    Shiraishi, Junya; Tokuda, Shinji; Aiba, Nobuyuki

    2008-11-01

    Stabilization of the Resistive Wall Modes (RWMs) by the plasma rotation is one of the most important physical issues for future reactors operated in the advanced tokamak regime [1]. For rotating plasmas, the linear stability problem, which is governed by the Frieman-Rotenberg equation [2], becomes non-self-adjoint, thus the conventional normal mode decomposition is not complete. Therefore, in this study, a new matching method is proposed, which solves the Frieman-Rotenberg equation as an initial value problem. The new method divides the plasma region into outer regions and inner layers as in the conventional asymptotic matching method. The essential difference is that the inner layers of the new method have finite width, thus, the Newcomb equation governing the outer regions has no singularity. The matching condition is numerically satisfied such that the normal components of the Lagrangian displacement are smooth. The new method can study the rotation effect around rational surfaces with high numerical accuracy and short computation time. [1] M. Takechi et al., Phys. Rev. Lett. 98, 055002 (2007). [2] E. Frieman and M. Rotenberg, Rev. Mod. Phys. 32, 898 (1960).

  13. Considerations on the European Standard EN 14157 Test Methods: Abrasion Resistance of Natural Stones Used for Flooring in Buildings

    NASA Astrophysics Data System (ADS)

    Karaca, Z.; Günes Yılmaz, N.; Goktan, R. M.

    2012-01-01

    In Europe, the Wide Wheel abrasion (WWA) test and the Böhme abrasion (BA) test are among the most widely used standard test methods for determining abrasion resistance of natural stones, the former being the reference test method in EN 14157 Standard. However, it is stated in the Annex-A (Informative) of EN 14157 Standard that very limited data are available to provide correlations between these two test methods. To be able to fill this gap, in this study, 25 different natural stones belonging to sedimentary, metamorphic and igneous groups were tested for their abrasion resistance as well as physico-mechanical properties. Also, for a better interpretation of abrasion resistance characteristics of the tested stone materials, relationships between abrasion resistance and physico-mechanical properties were statistically examined. A statistically significant linear correlation ( R 2 = 0.85; P value = 0.000) was established between the WWA test and the BA test, which could be used in practice for converting the measured abrasion resistance values from one testing method to another. It was also found that the correlation between these two test methods improved significantly ( R 2 = 0.93; P value = 0.001) when relatively high-porosity stone materials (porosity ≥1%) were separately evaluated. Both methods of abrasion resistance employed in the present study showed statistically significant linear correlations with uniaxial compressive strength and Brazilian tensile strength, the former proving to be a more influencing parameter on resistance to abrasion. Also, from the point view of representing actual abrasion mechanism of stone materials in practice, the necessity of simulating multi-directional foot traffic in abrasion testing methods was discussed. In this respect, the reference test method in the EN 14157 Standard was criticized for not fully meeting this requirement. It was also pointed out that the reference method could have some drawbacks when applied to coarse

  14. Deeper Penetration of Erythrocytes into the Endothelial Glycocalyx Is Associated with Impaired Microvascular Perfusion

    PubMed Central

    Lee, Dae Hyun; Dane, Martijn J. C.; van den Berg, Bernard M.; Boels, Margien G. S.; van Teeffelen, Jurgen W.; de Mutsert, Renée; den Heijer, Martin; Rosendaal, Frits R.; van der Vlag, Johan; van Zonneveld, Anton Jan; Vink, Hans; Rabelink, Ton J.

    2014-01-01

    Changes in endothelial glycocalyx are one of the earliest changes in development of cardiovascular disease. The endothelial glycocalyx is both an important biological modifier of interactions between flowing blood and the vessel wall, and a determinant of organ perfusion. We hypothesize that deeper penetration of erythrocytes into the glycocalyx is associated with reduced microvascular perfusion. The population-based prospective cohort study (the Netherlands Epidemiology of Obesity [NEO] study) includes 6,673 middle-aged individuals (oversampling of overweight and obese individuals). Within this cohort, we have imaged the sublingual microvasculature of 915 participants using sidestream darkfield (SDF) imaging together with a recently developed automated acquisition and analysis approach. Presence of RBC (as a marker of microvascular perfusion) and perfused boundary region (PBR), a marker for endothelial glycocalyx barrier properties for RBC accessibility, were assessed in vessels between 5 and 25 µm RBC column width. A wide range of variability in PBR measurements, with a mean PBR of 2.14 µm (range: 1.43–2.86 µm), was observed. Linear regression analysis showed a marked association between PBR and microvascular perfusion, reflected by RBC filling percentage (regression coefficient β: −0.034; 95% confidence interval: −0.037 to −0.031). We conclude that microvascular beds with a thick (“healthy”) glycocalyx (low PBR), reflects efficient perfusion of the microvascular bed. In contrast, a thin (“risk”) glycocalyx (high PBR) is associated with a less efficient and defective microvascular perfusion. PMID:24816787

  15. Drag-Reducing Polymer Enhances Microvascular Perfusion in the Traumatized Brain with Intracranial Hypertension.

    PubMed

    Bragin, Denis E; Thomson, Susan; Bragina, Olga; Statom, Gloria; Kameneva, Marina V; Nemoto, Edwin M

    2016-01-01

    Current treatments for traumatic brain injury (TBI) have not focused on improving microvascular perfusion. Drag-reducing polymers (DRP), linear, long-chain, blood-soluble, nontoxic macromolecules, may offer a new approach to improving cerebral perfusion by primary alteration of the fluid dynamic properties of blood. Nanomolar concentrations of DRP have been shown to improve hemodynamics in animal models of ischemic myocardium and ischemic limb, but have not yet been studied in the brain. We recently demonstrated that DRP improved microvascular perfusion and tissue oxygenation in a normal rat brain. We hypothesized that DRP could restore microvascular perfusion in hypertensive brain after TBI. Using in vivo two-photon laser scanning microscopy we examined the effect of DRP on microvascular blood flow and tissue oxygenation in hypertensive rat brains with and without TBI. DRP enhanced and restored capillary flow, decreased microvascular shunt flow, and, as a result, reduced tissue hypoxia in both nontraumatized and traumatized rat brains at high intracranial pressure. Our study suggests that DRP could constitute an effective treatment for improving microvascular flow in brain ischemia caused by high intracranial pressure after TBI. PMID:27165871

  16. Deeper penetration of erythrocytes into the endothelial glycocalyx is associated with impaired microvascular perfusion.

    PubMed

    Lee, Dae Hyun; Dane, Martijn J C; van den Berg, Bernard M; Boels, Margien G S; van Teeffelen, Jurgen W; de Mutsert, Renée; den Heijer, Martin; Rosendaal, Frits R; van der Vlag, Johan; van Zonneveld, Anton Jan; Vink, Hans; Rabelink, Ton J

    2014-01-01

    Changes in endothelial glycocalyx are one of the earliest changes in development of cardiovascular disease. The endothelial glycocalyx is both an important biological modifier of interactions between flowing blood and the vessel wall, and a determinant of organ perfusion. We hypothesize that deeper penetration of erythrocytes into the glycocalyx is associated with reduced microvascular perfusion. The population-based prospective cohort study (the Netherlands Epidemiology of Obesity [NEO] study) includes 6,673 middle-aged individuals (oversampling of overweight and obese individuals). Within this cohort, we have imaged the sublingual microvasculature of 915 participants using sidestream darkfield (SDF) imaging together with a recently developed automated acquisition and analysis approach. Presence of RBC (as a marker of microvascular perfusion) and perfused boundary region (PBR), a marker for endothelial glycocalyx barrier properties for RBC accessibility, were assessed in vessels between 5 and 25 µm RBC column width. A wide range of variability in PBR measurements, with a mean PBR of 2.14 µm (range: 1.43-2.86 µm), was observed. Linear regression analysis showed a marked association between PBR and microvascular perfusion, reflected by RBC filling percentage (regression coefficient β: -0.034; 95% confidence interval: -0.037 to -0.031). We conclude that microvascular beds with a thick ("healthy") glycocalyx (low PBR), reflects efficient perfusion of the microvascular bed. In contrast, a thin ("risk") glycocalyx (high PBR) is associated with a less efficient and defective microvascular perfusion.

  17. Drag-Reducing Polymer Enhances Microvascular Perfusion in the Traumatized Brain with Intracranial Hypertension.

    PubMed

    Bragin, Denis E; Thomson, Susan; Bragina, Olga; Statom, Gloria; Kameneva, Marina V; Nemoto, Edwin M

    2016-01-01

    Current treatments for traumatic brain injury (TBI) have not focused on improving microvascular perfusion. Drag-reducing polymers (DRP), linear, long-chain, blood-soluble, nontoxic macromolecules, may offer a new approach to improving cerebral perfusion by primary alteration of the fluid dynamic properties of blood. Nanomolar concentrations of DRP have been shown to improve hemodynamics in animal models of ischemic myocardium and ischemic limb, but have not yet been studied in the brain. We recently demonstrated that DRP improved microvascular perfusion and tissue oxygenation in a normal rat brain. We hypothesized that DRP could restore microvascular perfusion in hypertensive brain after TBI. Using in vivo two-photon laser scanning microscopy we examined the effect of DRP on microvascular blood flow and tissue oxygenation in hypertensive rat brains with and without TBI. DRP enhanced and restored capillary flow, decreased microvascular shunt flow, and, as a result, reduced tissue hypoxia in both nontraumatized and traumatized rat brains at high intracranial pressure. Our study suggests that DRP could constitute an effective treatment for improving microvascular flow in brain ischemia caused by high intracranial pressure after TBI.

  18. Added Qualifications in Microsurgery: Consideration for Subspecialty Certification in Microvascular Surgery in Europe.

    PubMed

    Heidekrueger, Paul I; Tanna, Neil; Weichman, Katie E; Szpalski, Caroline; Tos, Pierluigi; Ninkovic, Milomir; Broer, P Niclas

    2016-07-01

    Background While implementation of subspecializations may increase expertise in a certain area of treatment, there also exist downsides. Aim of this study was, across several disciplines, to find out if the technique of microsurgery warrants the introduction of a "Certificate of Added Qualifications (CAQ) in microsurgery." Methods An anonymous, web-based survey was administered to directors of microsurgical departments in Europe (n = 205). Respondents were asked, among other questions, whether they had completed a 12-month microvascular surgery fellowship and whether they believed a CAQ in microvascular surgery should be instituted. Results The response rate was 57%, and 33% of the respondents had completed a 12-month microvascular surgery fellowship.A total of 61% of all surgeons supported a CAQ in microsurgery. Answers ranged from 47% of support to 100% of support, depending on the countries surveyed. Discussion This is one of the few reports to evaluate the potential role of subspecialty certification of microvascular surgery across several European countries. The data demonstrate that the majority of directors of microsurgical departments support such a certificate. There was significantly greater support for a CAQ in microsurgery among those who have completed a formal microvascular surgery fellowship themselves. Conclusion This study supports the notion that further discussion and consideration of subspecialty certification in microvascular surgery appears necessary. There are multiple concerns surrounding this issue. Similar to the evolution of hand surgery certification, an exploratory committee of executive members of the respective medical boards and official societies may be warranted.

  19. A new method for measuring low resistivity contacts between silver and YBa2Cu3O(7-x) superconductor

    NASA Technical Reports Server (NTRS)

    Hsi, Chi-Shiung; Haertling, Gene H.; Sherrill, Max D.

    1991-01-01

    Several methods of measuring contact resistivity between silver electrodes and YBa2Cu3O(7-x) superconductors were investigated; including the two-point, the three point, and the lap-joint methods. The lap-joint method was found to yield the most consistent and reliable results and is proposed as a new technique for this measurement. Painting, embedding, and melting methods were used to apply the electrodes to the superconductor. Silver electrodes produced good ohmic contacts to YBa2Cu3O(7-x) superconductors with contact resistivities as low as 1.9 x 10 to the -9th ohm sq cm.

  20. Towards a Scalable Fully-Implicit Fully-coupled Resistive MHD Formulation with Stabilized FE Methods

    SciTech Connect

    Shadid, J N; Pawlowski, R P; Banks, J W; Chacon, L; Lin, P T; Tuminaro, R S

    2009-06-03

    This paper presents an initial study that is intended to explore the development of a scalable fully-implicit stabilized unstructured finite element (FE) capability for low-Mach-number resistive MHD. The discussion considers the development of the stabilized FE formulation and the underlying fully-coupled preconditioned Newton-Krylov nonlinear iterative solver. To enable robust, scalable and efficient solution of the large-scale sparse linear systems generated by the Newton linearization, fully-coupled algebraic multilevel preconditioners are employed. Verification results demonstrate the expected order-of-acuracy for the stabilized FE discretization of a 2D vector potential form for the steady and transient solution of the resistive MHD system. In addition, this study puts forth a set of challenging prototype problems that include the solution of an MHD Faraday conduction pump, a hydromagnetic Rayleigh-Bernard linear stability calculation, and a magnetic island coalescence problem. Initial results that explore the scaling of the solution methods are presented on up to 4096 processors for problems with up to 64M unknowns on a CrayXT3/4. Additionally, a large-scale proof-of-capability calculation for 1 billion unknowns for the MHD Faraday pump problem on 24,000 cores is presented.

  1. [Determination of nutrient elements in transgenic insect-resistant cotton tissues by three different spectroscopical methods].

    PubMed

    Sun, Cai-Xia; Zhang, Yu-Lan; Sun, Yu-Quan; Yang, Lei; Wang, Jie; Cui, Zhen-Bo

    2009-11-01

    In order to find out the effects of exogenous genes, such as Bt and Bt coupled with CpTI, on nutrition metabolism in transgenic plants, totally eleven types of nutrient elements in transgenic Bt (Z30) and Bt-CpTI (CCRI41 and SGK321) cotton were determined using methods of flame atomic absorption spectroscopy, flame atomic emission spectroscopy and spectrophotometry at flowering stage and boll-opening stage. The results showed that the chemical composition of plant nutrition in transgenic insect-resistant cotton differed in comparison with non-transgenic cotton counterparts related to varieties, tissues and stages. The content of total N in transgenic cotton changed most significantly. Especially, it increased by 21% for transgenic Bt cotton Z30 compared to non-transgenic cotton Z16. These changes in total N content were probably caused by both transgenes expression in transgenic cotton and other processes not studied in this experiment. The content of Mg, Na and Cu in transgenic cotton varied significantly only in some certain varieties or tissues. It was unobvious how the incorporation of transgenes impacted on the content of organic C, total P, total S, K, Ca, Fe and Zn in transgenic cotton. The authors speculated that there were no significant changes in utilization and accumulation of these nutrient elements between transgenic insect-resistant cotton and their non-transgenic cotton counterparts (Z16, CCRI23 and SY321, respectively).

  2. A protease substrate profiling method that links site-specific proteolysis with antibiotic resistance.

    PubMed

    Sandersjöö, Lisa; Kostallas, George; Löfblom, John; Samuelson, Patrik

    2014-01-01

    Proteases are involved in many biological processes and have become important tools in biomedical research and industry. Technologies for engineering and characterization of, for example, proteolytic activity and specificity are essential in protease research. Here, we present a novel method for assessment of site-specific proteolysis. The assay utilizes plasmid-encoded reporters that, upon processing by a co-expressed protease, confer antibiotic resistance to bacteria in proportion to the cleavage efficiency. We have demonstrated that cells co-expressing cleavable reporters together with tobacco etch virus protease (TEVp) could be discriminated from cells with non-cleavable reporters by growth in selective media. Importantly, the resistance to antibiotics proved to correlate with the substrate processing efficiency. Thus, by applying competitive growth of a mock library in antibiotic-containing medium, we could show that the substrate preferred by TEVp was enriched relative to less-efficient substrates. We believe that this simple methodology will facilitate protease substrate identification, and hold great promise for directed evolution of proteases and protease recognition sequences towards improved or even new functionality.

  3. Atorvastatin reduces endotoxin-induced microvascular inflammation via NOSII.

    PubMed

    McGown, Caroline C; Brookes, Zoë L S; Hellewell, Paul G; Ross, Jonathan J; Brown, Nicola J

    2015-05-01

    In a lipopolysaccharide (LPS)-induced rat model of sepsis (endotoxaemia), we previously demonstrated that pravastatin reduced microvascular inflammation via increased endothelial nitric oxide synthase III (NOSIII). This study aimed to determine whether atorvastatin, the most commonly used statin for lowering cholesterol, exerted beneficial pleiotropic effects via a similar mechanism. The mesenteric microcirculation of anaesthetised male Wistar rats (308 ± 63 g, n = 54) was prepared for fluorescent intravital microscopy. Over 4 h, animals received intravenous (i.v.) administration of either saline, LPS (150 μg kg(-1) h(-1)) or LPS + atorvastatin (200 μg kg(-1) s.c., 18 and 3 h before LPS), with/without the non-specific NOS inhibitor L-NG-Nitroarginine Methyl Ester (L-NAME) (10 μg kg(-1) h(-1)) or NOSII-specific inhibitor 1400 W (20 μg kg(-1) min(-1)). LPS decreased mean arterial blood pressure (MAP) (4 h, control 113 ± 20 mmHg; LPS 70 ± 23 mmHg), being reversed by atorvastatin (105 ± 3 mmHg) (p < 0.05). LPS also increased macromolecular leak measured after 100 mg kg(-1) of i.v FITC-BSA (arbitrary grey level adjacent to venules), which again was attenuated by atorvastatin (control 1.9 ± 4.0; LPS 12.0 ± 2.4; LPS + atorvastatin 4.5 ± 2.2) (p < 0.05). Furthermore, immunohistochemistry identified that atorvastatin decreased LPS-induced upregulation of endothelial cell NOSII expression, but NOSIII was unchanged in all groups. Atorvastatin improved MAP and reduced microvascular inflammation during endotoxaemia, associated with a reduction of pro-inflammatory NOSII. This differs from previous studies, whereby pravastatin increased expression of NOSIII. Thus preoperative statins have beneficial anti-inflammatory effects during endotoxaemia, but careful consideration must be given to the specific statin being used. PMID:25678054

  4. Identification of Karstic Caves by Utilizing Two-Dimensional Electrical Resistivity Imaging (ERI) Method

    NASA Astrophysics Data System (ADS)

    Uçar, Fatih; Aktürk, Özgür

    2015-04-01

    The region consisting of easily soluble rocks is generally defined as karstic terrain and it is characterized by surface collapse and small or large scale dissolution voids on rock surface. Formation and expansion of these voids may cause dangerous situation during surface/subsurface construction works. Therefore, it is important to determine the location, size and dimension of karstic caves. Geophysical investigations are very helpful in determining the boundaries of geological subsurface structures. In order to determine subsurface profile and characteristic of soil, surface geophysical methods can be successfully applied. Electrical Resistivity Imaging (ERI) is the most important methods among the convenient and commonly used methods to determine subsurface profile. By using this method, cavernous and weathered zones can be determined easily. Within the scope of this study, near surface profiles were determined by utilizing ERI at Akdeniz University Campus and Masa Dağı region located in the city of Antalya, Turkey. The results obtained from four different locations in the Akdeniz University campus compared only with Vertical Electrical Sounding (VES) analyses. Since topographic cross-section is clearly seen in two different locations around Masa Dağı location, ERI results were superimposed with topography and also compared with VES. As a result, presences of subsurface cavities were determined and illustrated using 2D colorful images. Keywords: ERI, VES, Karstic terrain, Cave, Antalya

  5. Effective plasmid DNA and small interfering RNA delivery to diseased human brain microvascular endothelial cells.

    PubMed

    Slanina, H; Schmutzler, M; Christodoulides, M; Kim, K S; Schubert-Unkmeir, A

    2012-01-01

    Expression of exogenous DNA or small interfering RNA (siRNA) in vitro is significantly affected by the particular delivery system utilized. In this study, we evaluated the transfection efficiency of plasmid DNA and siRNA into human brain microvascular endothelial cells (HBMEC) and meningioma cells, which constitute the blood-cerebrospinal fluid barrier, a target of meningitis-causing pathogens. Chemical transfection methods and various lipofection reagents including Lipofectamin™, FuGene™, or jetPRIME®, as well as physical transfection methods and electroporation techniques were applied. To monitor the transfection efficiencies, HBMEC and meningioma cells were transfected with the reporter plasmid pTagGFP2-actin vector, and efficiency of transfection was estimated by fluorescence microscopy and flow cytometry. We established protocols based on electroporation using Cell Line Nucleofector® Kit V with the Amaxa® Nucleofector® II system from Lonza and the Neon® Transfection system from Invitrogen resulting in up to 41 and 82% green fluorescent protein-positive HBMEC, respectively. Optimal transfection solutions, pulse programs and length were evaluated. We furthermore demonstrated that lipofection is an efficient method to transfect meningioma cells with a transfection efficiency of about 81%. Finally, we applied the successful electroporation protocols to deliver synthetic siRNA to HBMEC and analyzed the role of the actin-binding protein cortactin in Neisseria meningitidis pathogenesis. PMID:23036990

  6. Evaluation of genomic prediction methods for fusarium head blight resistance in wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium head blight (FHB) resistance is quantitative and difficult to evaluate. Genomic selection (GS) could accelerate FHB resistance breeding. We used US cooperative FHB wheat nursery data to evaluate GS models for several FHB resistance traits including deoxynivalenol (DON) levels. For all trait...

  7. Method For Creating Corrosion Resistant Surface On An Aluminum Copper Alloy

    DOEpatents

    Mansfeld, Florian B.; Wang, You; Lin, Simon H.

    1997-06-03

    A method for treating the surface of aluminum alloys hang a relatively high copper content is provided which includes the steps of removing substantially all of the copper from the surface, contacting the surface with a first solution containing cerium, electrically charging the surface while contacting the surface in an aqueous molybdate solution, and contacting the surface with a second solution containing cerium. The copper is substantially removed from the surface in the first step either by (i) contacting the surface with an acidic chromate solution or by (ii) contacting the surface with an acidic nitrate solution while subjecting the surface to an electric potential. The corrosion-resistant surface resulting from the invention is excellent, consistent and uniform throughout the surface. Surfaces treated by the invention may often be certified for use in salt-water services.

  8. Alkali resistant optical coatings for alkali lasers and methods of production thereof

    SciTech Connect

    Soules, Thomas F; Beach, Raymond J; Mitchell, Scott C

    2014-11-18

    In one embodiment, a multilayer dielectric coating for use in an alkali laser includes two or more alternating layers of high and low refractive index materials, wherein an innermost layer includes a thicker, >500 nm, and dense, >97% of theoretical, layer of at least one of: alumina, zirconia, and hafnia for protecting subsequent layers of the two or more alternating layers of high and low index dielectric materials from alkali attack. In another embodiment, a method for forming an alkali resistant coating includes forming a first oxide material above a substrate and forming a second oxide material above the first oxide material to form a multilayer dielectric coating, wherein the second oxide material is on a side of the multilayer dielectric coating for contacting an alkali.

  9. Method for reducing formation of electrically resistive layer on ferritic stainless steels

    SciTech Connect

    Rakowski, James M.

    2013-09-10

    A method of reducing the formation of electrically resistive scale on a an article comprising a silicon-containing ferritic stainless subjected to oxidizing conditions in service includes, prior to placing the article in service, subjecting the article to conditions under which silica, which includes silicon derived from the steel, forms on a surface of the steel. Optionally, at least a portion of the silica is removed from the surface to placing the article in service. A ferritic stainless steel alloy having a reduced tendency to form silica on at least a surface thereof also is provided. The steel includes a near-surface region that has been depleted of silicon relative to a remainder of the steel.

  10. Method and apparatus for duct sealing using a clog-resistant insertable injector

    DOEpatents

    Wang, Duo; Modera, Mark P.

    2007-01-02

    A clog-resistant injector spray nozzle allows relatively unobtrusive insertion through a small access aperture into existing ductwork in occupied buildings for atomized particulate sealing of a ductwork. The spray nozzle comprises an easily cleaned and easily replaced straight liquid tube whose liquid contents are principally propelled by a heated propellant gas, such as heated air. Heat transfer is minimized from the heated propellant gas to the liquid tube until they both exit the injector, thereby greatly reducing the likelihood of nozzle clogging. A method of duct sealing using particles driven by heated propellant gas is described, whereby duct-sealing operations become both faster, and commercially practicable in inhabited commercial and residential buildings.

  11. Remote Adaptive Motor Resistance Training Exercise Apparatus and Method of Use Thereof

    NASA Technical Reports Server (NTRS)

    Reich, Alton (Inventor); Shaw, James (Inventor)

    2016-01-01

    The invention comprises a method and/or an apparatus using a computer configured exercise system equipped with an electric motor to provide physical resistance to user motion in conjunction with means for sharing exercise system related data and/or user performance data with a secondary user, such as a medical professional, a physical therapist, a trainer, a computer generated competitor, and/or a human competitor. For example, the exercise system is used with a remote trainer to enhance exercise performance, with a remote medical professional for rehabilitation, and/or with a competitor in a competition, such as in a power/weightlifting competition or in a video game. The exercise system is optionally configured with an intelligent software assistant and knowledge navigator functioning as a personal assistant application.

  12. A Method for Amplicon Deep Sequencing of Drug Resistance Genes in Plasmodium falciparum Clinical Isolates from India.

    PubMed

    Rao, Pavitra N; Uplekar, Swapna; Kayal, Sriti; Mallick, Prashant K; Bandyopadhyay, Nabamita; Kale, Sonal; Singh, Om P; Mohanty, Akshaya; Mohanty, Sanjib; Wassmer, Samuel C; Carlton, Jane M

    2016-06-01

    A major challenge to global malaria control and elimination is early detection and containment of emerging drug resistance. Next-generation sequencing (NGS) methods provide the resolution, scalability, and sensitivity required for high-throughput surveillance of molecular markers of drug resistance. We have developed an amplicon sequencing method on the Ion Torrent PGM platform for targeted resequencing of a panel of six Plasmodium falciparum genes implicated in resistance to first-line antimalarial therapy, including artemisinin combination therapy, chloroquine, and sulfadoxine-pyrimethamine. The protocol was optimized using 12 geographically diverse P. falciparum reference strains and successfully applied to multiplexed sequencing of 16 clinical isolates from India. The sequencing results from the reference strains showed 100% concordance with previously reported drug resistance-associated mutations. Single-nucleotide polymorphisms (SNPs) in clinical isolates revealed a number of known resistance-associated mutations and other nonsynonymous mutations that have not been implicated in drug resistance. SNP positions containing multiple allelic variants were used to identify three clinical samples containing mixed genotypes indicative of multiclonal infections. The amplicon sequencing protocol has been designed for the benchtop Ion Torrent PGM platform and can be operated with minimal bioinformatics infrastructure, making it ideal for use in countries that are endemic for the disease to facilitate routine large-scale surveillance of the emergence of drug resistance and to ensure continued success of the malaria treatment policy.

  13. A Method for Amplicon Deep Sequencing of Drug Resistance Genes in Plasmodium falciparum Clinical Isolates from India

    PubMed Central

    Rao, Pavitra N.; Uplekar, Swapna; Kayal, Sriti; Mallick, Prashant K.; Bandyopadhyay, Nabamita; Kale, Sonal; Singh, Om P.; Mohanty, Akshaya; Mohanty, Sanjib; Wassmer, Samuel C.

    2016-01-01

    A major challenge to global malaria control and elimination is early detection and containment of emerging drug resistance. Next-generation sequencing (NGS) methods provide the resolution, scalability, and sensitivity required for high-throughput surveillance of molecular markers of drug resistance. We have developed an amplicon sequencing method on the Ion Torrent PGM platform for targeted resequencing of a panel of six Plasmodium falciparum genes implicated in resistance to first-line antimalarial therapy, including artemisinin combination therapy, chloroquine, and sulfadoxine-pyrimethamine. The protocol was optimized using 12 geographically diverse P. falciparum reference strains and successfully applied to multiplexed sequencing of 16 clinical isolates from India. The sequencing results from the reference strains showed 100% concordance with previously reported drug resistance-associated mutations. Single-nucleotide polymorphisms (SNPs) in clinical isolates revealed a number of known resistance-associated mutations and other nonsynonymous mutations that have not been implicated in drug resistance. SNP positions containing multiple allelic variants were used to identify three clinical samples containing mixed genotypes indicative of multiclonal infections. The amplicon sequencing protocol has been designed for the benchtop Ion Torrent PGM platform and can be operated with minimal bioinformatics infrastructure, making it ideal for use in countries that are endemic for the disease to facilitate routine large-scale surveillance of the emergence of drug resistance and to ensure continued success of the malaria treatment policy. PMID:27008882

  14. Discrepancy between simultaneous digital skin microvascular and brachial artery macrovascular post-occlusive hyperemia in systemic sclerosis

    PubMed Central

    Roustit, Matthieu; Simmons, Grant H.; Baguet, Jean-Philippe; Carpentier, Patrick H.; Cracowski, Jean-Luc

    2008-01-01

    Objective Vascular impairment, a main feature of the pathogenesis of systemic sclerosis (SSc), involves both the macro- and the microvasculature. We compared and correlated simultaneously measured skin microvascular and brachial artery macrovascular post-occlusive hyperemia in 3 groups: patients with SSc, patients with primary Raynaud’s phenomenon (RP), and healthy volunteers. Methods Thirty-three healthy volunteers, 36 patients with primary RP, and 42 patients with SSc were enrolled. For each subject, brachial artery flow-mediated dilation (FMD) and cutaneous post-occlusive reactive hyperemia (PORH) were simultaneously recorded after 5-minute occlusion of the brachial artery. Local thermal hyperemia, nitroglycerin-mediated dilation (NMD), intima-media thickness (IMT), and pulse wave velocity (PWV) were also assessed. Results Digital cutaneous peak PORH was altered in patients with primary RP and SSc compared to healthy controls, whereas FMD was not significantly different among all groups. We observed a correlation between digital peak cutaneous vascular conductance and brachial FMD in healthy controls (r = 0.49; p = 0.004), but not in patients with primary RP or SSc. Thermal hyperemia was altered only in patients with SSc. Brachial NMD, IMT, and PWV were not different among all groups. Conclusion We observed a loss of the correlation between brachial FMD and digital cutaneous PORH in patients with SSc and primary RP. Microvascular function is impaired in SSc, whereas brachial artery endothelial function is normal. (J Rheumatol First Release June 15 2008) PMID:18597404

  15. The Combination of Periostin Overexpression and Microvascular Invasion Is Related to a Poor Prognosis for Hepatocellular Carcinoma

    PubMed Central

    Jang, Se Young; Park, Soo Young; Lee, Hye Won; Choi, Yeon-Kyung; Park, Keun-Gyu; Yoon, Ghil Suk; Tak, Won Young; Kweon, Young Oh; Hur, Keun; Lee, Won Kee

    2016-01-01

    Background/Aims Periostin is an extracellular matrix protein and is known to be related to the metastatic potential and prognosis of cancer. However, few studies have investigated the expression level of periostin and its association with prognoses in hepatocellular carcinoma. Therefore, we analyzed periostin overexpression in hepatocellular carcinoma and its implication for prognoses. Methods We evaluated 149 patients who underwent surgical resection between 2006 and 2010. Tissue microarrays were constructed from hepatocellular carcinoma tissue and adjacent nontumor tissue, and immunohistochemistry was performed. Results A high periostin level was observed more frequently in cases of multiple tumors (odds ratio [OR], 2.826; 95% confidence interval [CI], 1.224 to 6.527; p=0.013), positive microvascular invasion (OR, 2.974; 95% CI, 1.431 to 6.181; p=0.003), and advanced stage disease (OR, 3.032; 95% CI, 1.424 to 6.452; p=0.003). Patients with high periostin expression had significantly (p=0.002) lower overall survival rates than those with low periostin expression (90.3%, 66.1%, and 56.2% vs 97.7%, 85.1%, and 77.5% at 1, 3, and 5 years). Conclusions We found that a combination of periostin overexpression and microvascular invasion in hepatocellular carcinoma was correlated with a poor prognosis and can be a good prognostic marker for hepatocellular carcinoma. PMID:27458178

  16. [Molecular diagnosis of methicillin-resistent Staphylococcus aureus: Methods and efficacy].

    PubMed

    Hell, M; Bauer, J W; Laimer, M

    2016-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) isolates are a serious public health problem whose ever-increasing rate is commensurate with the pressure it is exerting on the healthcare system. At present, more than 20% of clinical S. aureus isolates in German hospitals are methicillin-resistant, in Austria less than 10%. Strategies from low-prevalence countries show that this development is not necessarily inevitable. In the Scandinavian countries and the Netherlands, thanks to a rigorous prevention programme, MRSA prevalence has been kept at an acceptably low level (< 1-3%). Central to these search-and-destroy control strategies is an admission screening using several MRSA swabs taken from mucocutaneous colonisation sites of high-risk patients (MRSA surveillance). It has also been reported that the speed with which MRSA carriage is detected has an important role, as it is a key component of any effective strategy to prevent the pathogen from spreading. Since MRSA culturing involves a 2-3 day delay before the final results are available, rapid detection techniques (commonly referred to as MRSA rapid tests) using polymerase chain reaction (PCR) methods and, most recently, rapid culturing methods have been developed. The implementation of rapid tests reduces the time of detection of MRSA carriers from 48-72 to 2-5 h. Clinical evaluation data have shown that MRSA can thus be detected with very high sensitivity. Specificity, however, is sometimes impaired due to false-positive PCR signals occurring in mixed flora specimens. In order to rule out false-positive PCR results, a culture screen must always be carried out simultaneously. The data provide preliminary evidence that a PCR assay can reduce nosocomial MRSA transmission in high-risk patients or high-risk areas, whereas an approach that screens all patients admitted to the hospital is probably not effective. Information concerning the cost effectiveness of rapid MRSA tests is still sparse and thus the issue

  17. Brain microvascular endothelial cell transplantation ameliorates ischemic white matter damage.

    PubMed

    Puentes, Sandra; Kurachi, Masashi; Shibasaki, Koji; Naruse, Masae; Yoshimoto, Yuhei; Mikuni, Masahiko; Imai, Hideaki; Ishizaki, Yasuki

    2012-08-21

    Ischemic insults affecting the internal capsule result in sensory-motor disabilities which adversely affect the patient's life. Cerebral endothelial cells have been reported to exert a protective effect against brain damage, so the transplantation of healthy endothelial cells might have a beneficial effect on the outcome of ischemic brain damage. In this study, endothelin-1 (ET-1) was injected into the rat internal capsule to induce lacunar infarction. Seven days after ET-1 injection, microvascular endothelial cells (MVECs) were transplanted into the internal capsule. Meningeal cells or 0.2% bovine serum albumin-Hank's balanced salt solution were injected as controls. Two weeks later, the footprint test and histochemical analysis were performed. We found that MVEC transplantation improved the behavioral outcome based on recovery of hind-limb rotation angle (P<0.01) and induced remyelination (P<0.01) compared with the control groups. Also the inflammatory response was repressed by MVEC transplantation, judging from fewer ED-1-positive activated microglial cells in the MVEC-transplanted group than in the other groups. Elucidation of the mechanisms by which MVECs ameliorate ischemic damage of the white matter may provide important information for the development of effective therapies for white matter ischemia.

  18. Macro- and microvascular effects of nitrous oxide in the rat.

    PubMed Central

    Matheny, J. L.; Westphal, K. A.; Richardson, D. R.; Roth, G. I.

    1991-01-01

    The aims of this study were: (1) to determine the macro- and microvascular actions of nitrous oxide (N2O) in the rat, and (2) to determine whether the vascular actions of N2O involved specific interaction with alpha-adrenergic receptors or opioid receptors. Systolic blood pressure, heart rat, total tail blood flow, blood cell velocity in subepidermal capillaries of the tail, and percentage of capillaries exhibiting flow were monitored in conscious rats during the administration of N2O before and after administration of clonidine (an alpha 2-adrenergic agonist), prazosin (an alpha 1-adrenergic antagonist) or naloxone (an opioid antagonist). Total tail blood flow increased significantly in a dose-dependent manner with N2O at 20% and 40% with oxygen. This action of N2O was not blocked by clonidine, prazosin, or naloxone. Capillary flow velocity increased during 20% and 40% N2O compared to 100% O2, but the changes were not statistically significant nor did they correlate with the changes in tail blood flow. These data suggest that the peripheral vascular action of N2O does not involve specific actions at alpha-adrenergic receptors or opioid receptors and may be the result of direct actions on the peripheral vasculature. PMID:1667350

  19. Cardiac microvascular endothelial cells express a functional Ca+ -sensing receptor.

    PubMed

    Berra Romani, Roberto; Raqeeb, Abdul; Laforenza, Umberto; Scaffino, Manuela Federica; Moccia, Francesco; Avelino-Cruz, Josè Everardo; Oldani, Amanda; Coltrini, Daniela; Milesi, Veronica; Taglietti, Vanni; Tanzi, Franco

    2009-01-01

    The mechanism whereby extracellular Ca(2+) exerts the endothelium-dependent control of vascular tone is still unclear. In this study, we assessed whether cardiac microvascular endothelial cells (CMEC) express a functional extracellular Ca(2+)-sensing receptor (CaSR) using a variety of techniques. CaSR mRNA was detected using RT-PCR, and CaSR protein was identified by immunocytochemical analysis. In order to assess the functionality of the receptor, CMEC were loaded with the Ca(2+)-sensitive fluorochrome, Fura-2/AM. A number of CaSR agonists, such as spermine, Gd(3+), La(3+) and neomycin, elicited a heterogeneous intracellular Ca(2+) signal, which was abolished by disruption of inositol 1,4,5-trisphosphate (InsP(3)) signaling and by depletion of intracellular stores with cyclopiazonic acid. The inhibition of the Na(+)/Ca(2+) exchanger upon substitution of extracellular Na(+) unmasked the Ca(2+) signal triggered by an increase in extracellular Ca(2+) levels. Finally, aromatic amino acids, which function as allosteric activators of CaSR, potentiated the Ca(2+) response to the CaSR agonist La(3+). These data provide evidence that CMEC express CaSR, which is able to respond to physiological agonists by mobilizing Ca(2+) from intracellular InsP(3)-sensitive stores.

  20. Syndecan-2 downregulation impairs angiogenesis in human microvascular endothelial cells

    SciTech Connect

    Noguer, Oriol Villena, Joan; Lorita, Jordi; Vilaro, Senen; Reina, Manuel

    2009-03-10

    The formation of new blood vessels, or angiogenesis, is a necessary process during development but also for tumour growth and other pathologies. It is promoted by different growth factors that stimulate endothelial cells to proliferate, migrate, and generate new tubular structures. Syndecans, transmembrane heparan sulphate proteoglycans, bind such growth factors through their glycosaminoglycan chains and could transduce the signal to the cytoskeleton, thus regulating cell behaviour. We demonstrated that syndecan-2, the major syndecan expressed by human microvascular endothelial cells, is regulated by growth factors and extracellular matrix proteins, in both bidimensional and tridimensional culture conditions. The role of syndecan-2 in 'in vitro' tumour angiogenesis was also examined by inhibiting its core protein expression with antisense phosphorothioate oligonucleotides. Downregulation of syndecan-2 reduces spreading and adhesion of endothelial cells, enhances their migration, but also impairs the formation of capillary-like structures. These results suggest that syndecan-2 has an important function in some of the necessary steps that make up the angiogenic process. We therefore propose a pivotal role of this heparan sulphate proteoglycan in the formation of new blood vessels.

  1. Review: Cerebral microvascular pathology in aging and neurodegeneration

    PubMed Central

    Brown, William R.; Thore, Clara R.

    2010-01-01

    This review of age-related brain microvascular pathologies focuses on topics studied by this laboratory, including anatomy of the blood supply, tortuous vessels, venous collagenosis, capillary remnants, vascular density, and microembolic brain injury. Our studies feature thick sections, large blocks embedded in celloidin, and vascular staining by alkaline phosphatase (AP). This permits study of the vascular network in three dimensions, and the differentiation of afferent from efferent vessels. Current evidence suggests that there is decreased vascular density in aging, Alzheimer’s disease (AD), and leukoaraiosis (LA), and cerebrovascular dysfunction precedes and accompanies cognitive dysfunction and neurodegeneration. A decline in cerebrovascular angiogenesis may inhibit recovery from hypoxia-induced capillary loss. Cerebral blood flow (CBF) is inhibited by tortuous arterioles and deposition of excessive collagen in veins and venules. Misery perfusion due to capillary loss appears to occur before cell loss in LA, and CBF is also reduced in the normal-appearing white matter. Hypoperfusion occurs early in AD, inducing white matter lesions and correlating with dementia. In vascular dementia, cholinergic reductions are correlated with cognitive impairment, and cholinesterase inhibitors have some benefit. Most lipid microemboli from cardiac surgery pass through the brain in a few days, but some remain for weeks. They can cause what appears to be a type of vascular dementia years after surgery. Donepezil has shown some benefit. Emboli, such as clots, cholesterol crystals, and microspheres can be extruded through the walls of cerebral vessels, but there is no evidence yet that lipid emboli undergo such extravasation. PMID:20946471

  2. Brain microvascular endothelial cell transplantation ameliorates ischemic white matter damage.

    PubMed

    Puentes, Sandra; Kurachi, Masashi; Shibasaki, Koji; Naruse, Masae; Yoshimoto, Yuhei; Mikuni, Masahiko; Imai, Hideaki; Ishizaki, Yasuki

    2012-08-21

    Ischemic insults affecting the internal capsule result in sensory-motor disabilities which adversely affect the patient's life. Cerebral endothelial cells have been reported to exert a protective effect against brain damage, so the transplantation of healthy endothelial cells might have a beneficial effect on the outcome of ischemic brain damage. In this study, endothelin-1 (ET-1) was injected into the rat internal capsule to induce lacunar infarction. Seven days after ET-1 injection, microvascular endothelial cells (MVECs) were transplanted into the internal capsule. Meningeal cells or 0.2% bovine serum albumin-Hank's balanced salt solution were injected as controls. Two weeks later, the footprint test and histochemical analysis were performed. We found that MVEC transplantation improved the behavioral outcome based on recovery of hind-limb rotation angle (P<0.01) and induced remyelination (P<0.01) compared with the control groups. Also the inflammatory response was repressed by MVEC transplantation, judging from fewer ED-1-positive activated microglial cells in the MVEC-transplanted group than in the other groups. Elucidation of the mechanisms by which MVECs ameliorate ischemic damage of the white matter may provide important information for the development of effective therapies for white matter ischemia. PMID:22771710

  3. Finding fatigue resistant and lightweight designs using the optimization methods CAO and SKO

    NASA Astrophysics Data System (ADS)

    Mattheck, C.; Walther, Frank; Baumgartner, A.

    1992-07-01

    Computer Aided Optimization (CAO), a new method of shape optimization based on the computer simulation of biological growth and Soft Kill Option (SKO), and a strategy to find new design solutions with reduced weight are presented. CAO is used to improve the design of technical components by gaining a homogenized stress distribution on the surface of two and three dimensional finite element models. SKO helps to define new topologies starting from a general oversized 'design area'. With CAO it is also possible to simulate the 'adaptive growth' of biological load carriers, while SKO simulates the mineralization process of bones adapted to their loading. The main ideas of the methods are outlined and several examples of optimizations are shown. If completely new solutions for technical problems are desired, SKO is used first and the design proposal being found is then optimized by CAO in order to achieve a lightweight and fatigue resistant design. The efficiency of the combination of the two methods as a complete layout procedure is shown.

  4. Effect of Prewarming during Induction of Anesthesia on Microvascular Reactivity in Patients Undergoing Off-Pump Coronary Artery Bypass Surgery: A Randomized Clinical Trial

    PubMed Central

    Cho, Youn Joung; Lee, Seo Yun; Kim, Tae Kyong; Hong, Deok Man; Jeon, Yunseok

    2016-01-01

    Background General anesthesia may induce inadvertent hypothermia and this may be related to perioperative cardiovascular complications. Microvascular reactivity, measured by the recovery slope during a vascular occlusion test, is decreased during surgery and is also related to postoperative clinical outcomes. We hypothesized that microvascular changes during surgery may be related to intraoperative hypothermia. To evaluate this, we conducted a randomized study in patients undergoing off-pump coronary artery bypass surgery, in which the effect of prewarming on microvascular reactivity was evaluated. Methods Patients scheduled for off-pump coronary artery bypass surgery were screened. Enrolled patients were randomized to the prewarming group to receive forced-air warming during induction of anesthesia or to the control group. Measurement of core and skin temperatures and vascular occlusion test were conducted before anesthesia induction, 1, 2, and 3 h after induction, and at the end of surgery. Results In total, 40 patients were enrolled and finished the study (n = 20 in the prewarming group and n = 20 in the control group). During the first 3 h of anesthesia, core temperature was higher in the prewarming group than the control group (p < 0.001). The number of patients developing hypothermia was lower in the prewarming group than the control group (4/20 vs. 13/20, p = 0.004). However, tissue oxygen saturation and changes in recovery slope following a vascular occlusion test at 3 h after anesthesia induction did not differ between the groups. There was no difference in clinical outcome, including perioperative transfusion, wound infection, or hospital stay, between the groups. Conclusions Prewarming during induction of anesthesia decreased intraoperative hypothermia, but did not reduce the deterioration in microvascular reactivity in patients undergoing off-pump coronary artery bypass surgery. Trial Registration ClinicalTrials.gov NCT02186210 PMID:27442052

  5. QRS duration: a novel marker of microvascular reperfusion as assessed by myocardial blush grade in ST elevation myocardial infarction patients undergoing a primary percutaneous intervention

    PubMed Central

    Yaylak, Bariş; Uğurlu, Murat; Kaya, İlyas; Uçaman, Berzal; Öztürk, Önder

    2015-01-01

    Objectives Prolonged QRS duration is a predictor of poor prognosis in patients with coronary artery disease. The association between the duration of QRS and myocardial reperfusion is not very well understood. Our aim was to assess the relationship between the measurements of QRS duration and myocardial blush grade (MBG) in patients with ST elevation myocardial infarction (STEMI) who were treated with a primary percutaneous intervention. Patients and methods A total of 213 patients (mean age: 57.5±11 years) with STEMI were included. ECG recordings were obtained for the evaluation of the QRS duration before and after primary percutaneous coronary intervention. Angiographic assessment in the infarct-related artery was performed using the MBG. Patients were categorized into two groups of those with impaired microvascular reperfusion (MBG: 0–1) and those with normal microvascular reperfusion (MBG: 2–3). Results Overall, 105 and 108 patients had an MBG of 0–1 or 2–3, respectively. There is no significant difference between patient’s characteristics. Despite the absence of a difference between two groups in terms of the QRS duration at presentation (P: 0.57), patients with impaired microvascular reperfusion were found to have longer QRS duration at immediately postprocedure (P: 0.003) and postprocedure 60 min time-points (P<0.001). Correlation analyses showed a positive correlation between pain-to-balloon time and QRS duration at postprocedure 60 min time-points (r: 0.137 and P: 0.04). Conclusion Our results suggest that longer QRS duration after angioplasty seemed to indicate the presence of impaired microvascular reperfusion in patients with STEMI. PMID:26166018

  6. Comparison of methods to determine point-to-point resistance in nearly rectangular networks with application to a 'hammock' network.

    PubMed

    Essam, John W; Izmailyan, Nikolay Sh; Kenna, Ralph; Tan, Zhi-Zhong

    2015-04-01

    Considerable progress has recently been made in the development of techniques to exactly determine two-point resistances in networks of various topologies. In particular, two types of method have emerged. One is based on potentials and the evaluation of eigenvalues and eigenvectors of the Laplacian matrix associated with the network or its minors. The second method is based on a recurrence relation associated with the distribution of currents in the network. Here, these methods are compared and used to determine the resistance distances between any two nodes of a network with topology of a hammock. PMID:26064635

  7. A review of control methods and resistance mechanisms in stored-product insects.

    PubMed

    Boyer, S; Zhang, H; Lempérière, G

    2012-04-01

    This review describes the major stored-product insect species and their resistance to insecticides. The economic importance of the control of those pests is highlighted with a loss of more than one billion US dollars per year worldwide. A detailed common description of species resistance throughout the world has been developed, and we observed 28 recurrent studied species involved in resistance cases disseminated on the five continents. The different mechanisms, including behavioral resistance, were studied particularly on Oryzaephilus surinamensis. The role of detoxifying enzymes and studies on the genetic resistance, involving the kdr mutation mechanisms and the transmission of the genes of resistance, are also described. A chapter clarifying definitions on cross and multiple resistance is enclosed.

  8. A review of control methods and resistance mechanisms in stored-product insects.

    PubMed

    Boyer, S; Zhang, H; Lempérière, G

    2012-04-01

    This review describes the major stored-product insect species and their resistance to insecticides. The economic importance of the control of those pests is highlighted with a loss of more than one billion US dollars per year worldwide. A detailed common description of species resistance throughout the world has been developed, and we observed 28 recurrent studied species involved in resistance cases disseminated on the five continents. The different mechanisms, including behavioral resistance, were studied particularly on Oryzaephilus surinamensis. The role of detoxifying enzymes and studies on the genetic resistance, involving the kdr mutation mechanisms and the transmission of the genes of resistance, are also described. A chapter clarifying definitions on cross and multiple resistance is enclosed. PMID:22126937

  9. Beyond serial passages: new methods for predicting the emergence of resistance to novel antibiotics.

    PubMed

    Martínez, José Luis; Baquero, Fernando; Andersson, Dan I

    2011-10-01

    Market launching of a new antibiotic requires knowing in advance its benefits and possible risks, and among them how rapidly resistance will emerge and spread among bacterial pathogens. This information is not only useful from a public health point of view, but also for pharmaceutical industry, in order to reduce potential waste of resources in the development of a compound that might be discontinued at the short term because of resistance development. Most assays currently used for predicting the emergence of resistance are based on culturing the target bacteria by serial passages in the presence of increasing concentrations of antibiotics. Whereas these assays may be valuable for identifying mutations that might cause resistance, they are not useful to establish how fast resistance might appear, neither to address the risk of spread of resistance genes by horizontal gene transfer. In this article, we review recent information pertinent for a more accurate prediction on the emergence and dispersal of antibiotic resistance.

  10. Risk Factors for Macro- and Microvascular Complications among Older Adults with Diagnosed Type 2 Diabetes: Findings from The Irish Longitudinal Study on Ageing

    PubMed Central

    McHugh, Sheena M.; Fitzgerald, Anthony P.; Buckley, Claire M.; Canavan, Ronan J.

    2016-01-01

    Objective. To explore risk factors for macro- and microvascular complications in a nationally representative sample of adults aged 50 years and over with type 2 diabetes in Ireland. Methods. Data from the first wave of The Irish Longitudinal Study on Ageing (TILDA) (2009–2011) was used in cross-sectional analysis. The presence of doctor diagnosis of diabetes, risk factors, and macro- and microvascular complications were determined by self-report. Gender-specific differences in risk factor prevalence were assessed with the chi-squared test. Binomial regression analysis was conducted to explore independent associations between established risk factors and diabetes-related complications. Results. Among 8175 respondents, 655 were classified as having type 2 diabetes. Older age, being male, a history of smoking, a lower level of physical activity, and a diagnosis of high cholesterol were independent predictors of macrovascular complications. Diabetes diagnosis of 10 or more years, a history of smoking, and a diagnosis of hypertension were associated with an increased risk of microvascular complications. Older age, third-level education, and a high level of physical activity were protective factors (p < 0.05). Conclusions. Early intervention to target modifiable risk factors is urgently needed to reduce diabetes-related morbidity in the older population in Ireland. PMID:27294152

  11. Characterization of a dismissed landfill via electrical resistivity tomography and mise-à-la-masse method

    NASA Astrophysics Data System (ADS)

    De Carlo, Lorenzo; Perri, Maria Teresa; Caputo, Maria Clementina; Deiana, Rita; Vurro, Michele; Cassiani, Giorgio

    2013-11-01

    Electrical resistivity methods are widely used for environmental applications, and they are particularly useful for the characterization and monitoring of sites where the presence of contamination requires a thorough understanding of the location and movement of water, that can act as a carrier of solutes. One such application is landfill studies, where the strong electrical contrasts between waste, leachate and surrounding formations make electrical methods a nearly ideal tool for investigation. In spite of the advantages, however, electrical investigation of landfills poses also challenges, both logistical and interpretational. This paper presents the results of a study conducted on a dismissed landfill, close to the city of Corigliano d'Otranto, in the Apulia region (Southern Italy). The landfill is located in an abandoned quarry, that was subsequently re-utilized about thirty years ago as a site for urban waste disposal. The waste was thought to be more than 20 m thick, and the landfill bottom was expected to be confined with an HDPE (high-density poli-ethylene) liner. During the digging operations performed to build a nearby new landfill, leachate was found, triggering an in-depth investigation including also non-invasive methods. The principal goal was to verify whether the leachate is indeed confined, and to what extent, by the HDPE liner. We performed both surface electrical resistivity tomography (ERT) and mise-à-la-masse (MALM) surveys, facing the severe challenges posed by the rugged terrain of the abandoned quarry complex. A conductive body, probably associated with leachate, was found as deep as 40 m below the current landfill surface i.e. at a depth much larger than the expected 20 m thickness of waste. Given the logistical difficulties that limit the geometry of acquisition, we utilized synthetic forward modeling in order to confirm/dismiss interpretational hypotheses emerging from the ERT and MALM results. This integration between measurements and

  12. Experiments of the selection of a method evaluating the fire resistance of some materials based on macromolecular compounds

    NASA Technical Reports Server (NTRS)

    Stoica, Steln; Sebe, Mircea Octavian

    1987-01-01

    A comparative experimental study on the application of various tests for the evaluation of the fire-resistant properties of plastic materials is presented. On the basis of the results obtained conclusions are drawn on the advantages and disadvantages of the methods used, and a preferred test method is picked, i.e., the introduction of fire retardant materials into the polymers.

  13. Noninvasive Measurement of Microvascular and Interstitial Oxygen Profiles in a Human Tumor in SCID Mice

    NASA Astrophysics Data System (ADS)

    Torres Filho, Ivo P.; Leunig, Michael; Yuan, Fan; Intaglietta, Marcos; Jain, Rakesh K.

    1994-03-01

    Simultaneous measurements of intravascular and interstitial oxygen partial pressure (Po_2) in any tissue have not previously been reported, despite the importance of oxygen in health and in disease. This is due to the limitations of current techniques, both invasive and noninvasive. We have optically measured microscopic profiles of Po_2 with high spatial resolution in subcutaneous tissue and transplanted tumors in mice by combining an oxygen-dependent phosphorescence quenching method and a transparent tissue preparation. The strengths of our approach include the ability to follow Po_2 in the same location for several weeks and to relate these measurements to local blood flow and vascular architecture. Our results show that (i) Po_2 values in blood vessels in well-vascularized regions of a human colon adenocarcinoma xenograft are comparable to those in surrounding arterioles and venules, (ii) carbogen (95% O_2/5% CO_2) breathing increases microvascular Po_2 in tumors, and (iii) in unanesthetized and anesthetized mice Po_2 drops to hypoxic values at <200 μm from isolated vessels but drops by <5 mmHg (1 mmHg = 133 Pa) in highly vascularized tumor regions. Our method should permit noninvasive evaluations of oxygen-modifying agents and offer further mechanistic information about tumor pathophysiology in tissue preparations where the surface of the tissue can be observed.

  14. Early microvascular changes in the preterm neonate: a comparative study of the human and guinea pig

    PubMed Central

    Dyson, Rebecca M.; Palliser, Hannah K.; Lakkundi, Anil; de Waal, Koert; Latter, Joanna L.; Clifton, Vicki L.; Wright, Ian M. R.

    2014-01-01

    Abstract Dysfunction of the transition from fetal to neonatal circulatory systems may be a major contributor to poor outcome following preterm birth. Evidence exists in the human for both a period of low flow between 5 and 11 h and a later period of increased flow, suggesting a hypoperfusion–reperfusion cycle over the first 24 h following birth. Little is known about the regulation of peripheral blood flow during this time. The aim of this study was to conduct a comparative study between the human and guinea pig to characterize peripheral microvascular behavior during circulatory transition. Very preterm (≤28 weeks GA), preterm (29–36 weeks GA), and term (≥37 weeks GA) human neonates underwent laser Doppler analysis of skin microvascular blood flow at 6 and 24 h from birth. Guinea pig neonates were delivered prematurely (62 day GA) or at term (68–71 day GA) and laser Doppler analysis of skin microvascular blood flow was assessed every 2 h from birth. In human preterm neonates, there is a period of high microvascular flow at 24 h after birth. No period of low flow was observed at 6 h. In preterm animals, microvascular flow increased after birth, reaching a peak at 10 h postnatal age. Blood flow then steadily decreased, returning to delivery levels by 24 h. Preterm birth was associated with higher baseline microvascular flow throughout the study period in both human and guinea pig neonates. The findings do not support a hypoperfusion–reperfusion cycle in the microcirculation during circulatory transition. The guinea pig model of preterm birth will allow further investigation of the mechanisms underlying microvascular function and dysfunction during the initial extrauterine period. PMID:25350751

  15. Effect of Thrombus Composition and Viscosity on Sonoreperfusion Efficacy in a Model of Micro-Vascular Obstruction.

    PubMed

    Black, John J; Yu, Francois T H; Schnatz, Rick G; Chen, Xucai; Villanueva, Flordeliza S; Pacella, John J

    2016-09-01

    Distal embolization of micro-thrombi during stenting for myocardial infarction causes micro-vascular obstruction (MVO). We have previously shown that sonoreperfusion (SRP), a microbubble (MB)-mediated ultrasound (US) therapy, resolves MVO from venous micro-thrombi in vitro in saline. However, blood is more viscous than saline, and arterial thrombi that embolize during stenting are mechanically distinct from venous clot. Therefore, we tested the hypothesis that MVO created with arterial micro-thrombi are more resistant to SRP therapy compared with venous micro-thrombi, and higher viscosity further increases the US requirement for effective SRP in an in vitro model of MVO. Lipid MBs suspended in plasma with adjusted viscosity (1.1 cP or 4.0 cP) were passed through tubing bearing a mesh with 40-μm pores to simulate a micro-vascular cross-section; upstream pressure reflected thrombus burden. To simulate MVO, the mesh was occluded with either arterial or venous micro-thrombi to increase upstream pressure to 40 mmHg ± 5 mmHg. Therapeutic long-tone-burst US was delivered to the occluded area for 20 min. MB activity was recorded with a passive cavitation detector. MVO caused by arterial micro-thrombi at either blood or plasma viscosity resulted in less effective SRP therapy compared to venous thrombi. Higher viscosity further reduced the effectiveness of SRP therapy. The passive cavitation detector showed a decrease in inertial cavitation when viscosity was increased, while stable cavitation was affected in a more complex manner. Overall, these data suggest that arterial thrombi may require higher acoustic pressure US than venous thrombi to achieve similar SRP efficacy; increased viscosity decreases SRP efficacy; and both inertial and stable cavitation are implicated in observed SRP efficacy. PMID:27207018

  16. Palmitate-induced inflammatory pathways in human adipose microvascular endothelial cells promote monocyte adhesion and impair insulin transcytosis.

    PubMed

    Pillon, Nicolas J; Azizi, Paymon M; Li, Yujin E; Liu, Jun; Wang, Changsen; Chan, Kenny L; Hopperton, Kathryn E; Bazinet, Richard P; Heit, Bryan; Bilan, Philip J; Lee, Warren L; Klip, Amira

    2015-07-01

    Obesity is associated with inflammation and immune cell recruitment to adipose tissue, muscle and intima of atherosclerotic blood vessels. Obesity and hyperlipidemia are also associated with tissue insulin resistance and can compromise insulin delivery to muscle. The muscle/fat microvascular endothelium mediates insulin delivery and facilitates monocyte transmigration, yet its contribution to the consequences of hyperlipidemia is poorly understood. Using primary endothelial cells from human adipose tissue microvasculature (HAMEC), we investigated the effects of physiological levels of fatty acids on endothelial inflammation and function. Expression of cytokines and adhesion molecules was measured by RT-qPCR. Signaling pathways were evaluated by pharmacological manipulation and immunoblotting. Surface expression of adhesion molecules was determined by immunohistochemistry. THP1 monocyte interaction with HAMEC was measured by cell adhesion and migration across transwells. Insulin transcytosis was measured by total internal reflection fluorescence microscopy. Palmitate, but not palmitoleate, elevated the expression of IL-6, IL-8, TLR2 (Toll-like receptor 2), and intercellular adhesion molecule 1 (ICAM-1). HAMEC had markedly low fatty acid uptake and oxidation, and CD36 inhibition did not reverse the palmitate-induced expression of adhesion molecules, suggesting that inflammation did not arise from palmitate uptake/metabolism. Instead, inhibition of TLR4 to NF-κB signaling blunted palmitate-induced ICAM-1 expression. Importantly, palmitate-induced surface expression of ICAM-1 promoted monocyte binding and transmigration. Conversely, palmitate reduced insulin transcytosis, an effect reversed by TLR4 inhibition. In summary, palmitate activates inflammatory pathways in primary microvascular endothelial cells, impairing insulin transport and increasing monocyte transmigration. This behavior may contribute in vivo to reduced tissue insulin action and enhanced tissue

  17. The effect of passive tilting on microvascular parameters in the human calf: a strain gauge plethysmography study.

    PubMed Central

    Gamble, J; Christ, F; Gartside, I B

    1997-01-01

    1. Cumulative small steps in venous congestion pressure were used to study the effect of passive tilt on vascular parameters in dependent tissues. Using this protocol we have non-invasively assessed venous pressure (Pv,est), isovolumetric cuff pressure (Pv,i), which is the congestion cuff pressure (Pcuff) that has to be exceeded to induce fluid filtration. We have also assessed microvascular filtration capacity (Kf), which is the linear relationship between filtration rate (Jv) and Pcuff, when Pcuff > Pv,i, and is the product of the available exchange vessel surface area and wall conductance. 2. Subjects were passively tilted to increase the venous pressure at the level of the calf by 47.4 +/- 2.4 mmHg (mean +/- S.E.M.). The value of Pv,i increased from 20.6 +/- 1.8 to 48.5 +/- 3.8 mmHg after the imposition of the tilt. This change may reflect the increased colloid osmotic pressure at the microvascular interface that is known to occur in response to this manoeuvre. 3. The pre-tilt value of Kf did not change after the imposition of the passive tilt, the values being 3.2 +/- 0.4 x 10(-3) and 3.6 +/- 0.4 x 10(-3) ml min-1 (100 ml-1) mmHg-1, respectively, (n = 13). 4. These results support the notion that passive postural change alters the pre-capillary resistance, thereby altering the pressure and flow characteristics within the exchange vessels, but does not alter the surface area available for fluid exchange in the calf, contrary to previous findings in the dependent human foot using a single-step venous occlusion protocol. PMID:9032701

  18. Nitric oxide-mediated cutaneous microvascular function is impaired in polycystic ovary sydrome but can be improved by exercise training.

    PubMed

    Sprung, V S; Cuthbertson, D J; Pugh, C J A; Daousi, C; Atkinson, G; Aziz, N F; Kemp, G J; Green, D J; Cable, N T; Jones, H

    2013-03-15

    Polycystic ovary syndrome (PCOS) is associated with cardiovascular disease. The contribution of the nitric oxide (NO) dilator system to cutaneous endothelial dysfunction is currently unknown in PCOS. Our aim was to examine whether women with PCOS demonstrate impaired cutaneous microvascular NO function and whether exercise training can ameliorate any impairment. Eleven women with PCOS (age, 29 ± 7 years; body mass index, 34 ± 6 kg m(-2)) were compared with six healthy obese control women (age, 29 ± 7 years; body mass index, 34 ± 5 kg m(-2)). Six women with PCOS (30 ± 7 years; 31 ± 6 kg m(-2)) then completed 16 weeks of exercise training. Laser Doppler flowmetry, combined with intradermal microdialysis of l-N(G)-monomethyl-l-arginine, a nitric oxide antagonist, in response to incremental local heating of the forearm was assessed in women with PCOS and control women, and again in women with PCOS following exercise training. Cardiorespiratory fitness, homeostasis model assessment for insulin resistance, hormone and lipid profiles were also assessed. Differences between women with PCOS and control women and changes with exercise were analysed using Student's unpaired t tests. Differences in the contribution of NO to cutaneous blood flow [expressed as a percentage of maximal cutaneous vasodilatation (CVCmax)] were analysed using general linear models. At 42°C heating, cutaneous NO-mediated vasodilatation was attenuated by 17.5%CVCmax (95% confidence interval, 33.3, 1.7; P = 0.03) in women with PCOS vs. control women. Exercise training improved cardiorespiratory fitness by 5.0 ml kg(-1) min(-1) (95% confidence interval, 0.9, 9.2; P = 0.03) and NO-mediated cutaneous vasodilatation at 42°C heating by 19.6% CVCmax (95% confidence interval, 4.3, 34.9; P = 0.02). Cutaneous microvascular NO function is impaired in women with PCOS compared with obese matched control women but can be improved with exercise training.

  19. Role of Microvascular Tone and Extracellular Matrix Contraction in the Regulation of Interstitial Fluid: Implications for Aortic Dissection.

    PubMed

    Mallat, Ziad; Tedgui, Alain; Henrion, Daniel

    2016-09-01

    The pathophysiology of aortic dissection is poorly understood, and its risk is resistant to medical treatment. Most studies have focused on a proposed pathogenic role of transforming growth factor-β in Marfan disease and related thoracic aortic aneurysms and aortic dissections. However, clinical testing of this concept using angiotensin II type 1 receptor antagonists to block transforming growth factor-β signaling fell short of promise. Genetic mutations that predispose to thoracic aortic aneurysms and aortic dissections affect components of the extracellular matrix and proteins involved in cellular force generation. Thus, a role for dysfunctional mechanosensing in abnormal aortic wall remodeling is emerging. However, how abnormal mechanosensing leads to aortic dissection remains a mystery. Here, we review current knowledge about the regulation of interstitial fluid dynamics and myogenic tone and propose that alteration in contractile force reduces vascular tone in the microcirculation (here, aortic vasa vasorum) and leads to elevations of blood flow, transmural pressure, and fluid flux into the surrounding aortic media. Furthermore, reduced contractile force in medial smooth muscle cells coupled with alteration of structural components of the extracellular matrix limits extracellular matrix contraction, further promoting the formation of intramural edema, a critical step in the initiation of aortic dissection. The concept is supported by several pathophysiological and clinical observations. A direct implication of this concept is that drugs that lower blood pressure and limit interstitial fluid accumulation while preserving or increasing microvascular tone would limit the risk of dissection. In contrast, drugs that substantially lower microvascular tone would be ineffective or may accelerate the disease and precipitate aortic dissection. PMID:27444198

  20. Emerging Rapid Resistance Testing Methods for Clinical Microbiology Laboratories and Their Potential Impact on Patient Management

    PubMed Central

    Frickmann, Hagen; Zautner, Andreas E.

    2014-01-01

    Atypical and multidrug resistance, especially ESBL and carbapenemase expressing Enterobacteriaceae, is globally spreading. Therefore, it becomes increasingly difficult to achieve therapeutic success by calculated antibiotic therapy. Consequently, rapid antibiotic resistance testing is essential. Various molecular and mass spectrometry-based approaches have been introduced in diagnostic microbiology to speed up the providing of reliable resistance data. PCR- and sequencing-based approaches are the most expensive but the most frequently applied modes of testing, suitable for the detection of resistance genes even from primary material. Next generation sequencing, based either on assessment of allelic single nucleotide polymorphisms or on the detection of nonubiquitous resistance mechanisms might allow for sequence-based bacterial resistance testing comparable to viral resistance testing on the long term. Fluorescence in situ hybridization (FISH), based on specific binding of fluorescence-labeled oligonucleotide probes, provides a less expensive molecular bridging technique. It is particularly useful for detection of resistance mechanisms based on mutations in ribosomal RNA. Approaches based on MALDI-TOF-MS, alone or in combination with molecular techniques, like PCR/electrospray ionization MS or minisequencing provide the fastest resistance results from pure colonies or even primary samples with a growing number of protocols. This review details the various approaches of rapid resistance testing, their pros and cons, and their potential use for the diagnostic laboratory. PMID:25343142

  1. Emerging rapid resistance testing methods for clinical microbiology laboratories and their potential impact on patient management.

    PubMed

    Frickmann, Hagen; Masanta, Wycliffe Omurwa; Zautner, Andreas E

    2014-01-01

    Atypical and multidrug resistance, especially ESBL and carbapenemase expressing Enterobacteriaceae, is globally spreading. Therefore, it becomes increasingly difficult to achieve therapeutic success by calculated antibiotic therapy. Consequently, rapid antibiotic resistance testing is essential. Various molecular and mass spectrometry-based approaches have been introduced in diagnostic microbiology to speed up the providing of reliable resistance data. PCR- and sequencing-based approaches are the most expensive but the most frequently applied modes of testing, suitable for the detection of resistance genes even from primary material. Next generation sequencing, based either on assessment of allelic single nucleotide polymorphisms or on the detection of nonubiquitous resistance mechanisms might allow for sequence-based bacterial resistance testing comparable to viral resistance testing on the long term. Fluorescence in situ hybridization (FISH), based on specific binding of fluorescence-labeled oligonucleotide probes, provides a less expensive molecular bridging technique. It is particularly useful for detection of resistance mechanisms based on mutations in ribosomal RNA. Approaches based on MALDI-TOF-MS, alone or in combination with molecular techniques, like PCR/electrospray ionization MS or minisequencing provide the fastest resistance results from pure colonies or even primary samples with a growing number of protocols. This review details the various approaches of rapid resistance testing, their pros and cons, and their potential use for the diagnostic laboratory.

  2. Retinal Microvascular Responses to Short-Term Changes in Particulate Air Pollution in Healthy Adults

    PubMed Central

    Louwies, Tijs; Kicinski, Michal; De Boever, Patrick; Nawrot, Tim S.

    2013-01-01

    Background: Microcirculation plays an important role in the physiology of cardiovascular health. Air pollution is an independent risk factor for the development and progression of cardiovascular diseases, but the number of studies on the relation between air pollution and the microcirculation is limited. Objectives: We examined the relationship between short-term changes in air pollution and microvascular changes. Methods: We measured retinal microvasculature using fundus image analysis in a panel of 84 healthy adults (52% female), 22–63 years of age, during January–May 2012. Blood vessels were measured as central retinal arteriolar/venular equivalent (CRAE/CRVE), with a median of 2 measurements (range, 1–3). We used monitoring data on particulate air pollution (PM10) and black carbon (BC). Mixed-effect models were used to estimate associations between CRAE/CRVE and exposure to PM10 and BC using various exposure windows. Results: CRAE and CRVE were associated with PM10 and BC concentrations, averaged over the 24 hr before the retinal examinations. Each 10-µg/m3 increase in PM10 was associated with a 0.93-µm decrease (95% CI: –1.42, –0.45; p = 0.0003) in CRAE and a 0.86-µm decrease (95% CI: –1.42, –0.30; p = 0.004) in CRVE after adjusting for individual characteristics and time varying conditions such as ambient temperature. Each 1-µg/m3 increase in BC was associated with a 1.84-µm decrease (95% CI: –3.18, –0.51; p < 0.001) in CRAE. Conclusions: Our findings suggest that the retinal microvasculature responds to short-term changes in air pollution levels. These results support a mechanistic pathway through which air pollution can act as a trigger of cardiovascular events at least in part through effects on the microvasculature. Citation: Louwies T, Int Panis L, Kicinski M, De Boever P, Nawrot TS. 2013. Retinal microvascular responses to short-term changes in particulate air pollution in healthy adults. Environ Health Perspect 121:1011–1016;

  3. Cardiac Microvascular Barrier Function Mediates the Protection of Tongxinluo against Myocardial Ischemia/Reperfusion Injury

    PubMed Central

    Qi, Kang; Li, Lujin; Li, Xiangdong; Zhao, Jinglin; Wang, Yang; You, Shijie; Hu, Fenghuan; Zhang, Haitao; Cheng, Yutong; Kang, Sheng; Cui, Hehe; Duan, Lian; Jin, Chen; Zheng, Qingshan; Yang, Yuejin

    2015-01-01

    Objective Tongxinluo (TXL) has been shown to decrease myocardial necrosis after ischemia/reperfusion (I/R) by simulating ischemia preconditioning (IPC). However, the core mechanism of TXL remains unclear. This study was designed to investigate the key targets of TXL against I/R injury (IRI) among the cardiac structure-function network. Materials and Methods To evaluate the severity of lethal IRI, a mathematical model was established according to the relationship between myocardial no-reflow size and necrosis size. A total of 168 mini-swine were employed in myocardial I/R experiment. IRI severity among different interventions was compared and IPC and CCB groups were identified as the mildest and severest groups, respectively. Principal component analysis was applied to further determine 9 key targets of IPC in cardioprotection. Then, the key targets of TXL in cardioprotection were confirmed. Results Necrosis size and no-reflow size fit well with the Sigmoid Emax model. Necrosis reduction space (NRS) positively correlates with I/R injury severity and necrosis size (R2=0.92, R2=0.57, P<0.01, respectively). Functional and structural indices correlate positively with NRS (R2=0.64, R2=0.62, P<0.01, respectively). TXL recovers SUR2, iNOS activity, eNOS activity, VE-cadherin, β-catenin, γ-catenin and P-selectin with a trend toward the sham group. Moreover, TXL increases PKA activity and eNOS expression with a trend away from the sham group. Among the above nine indices, eNOS activity, eNOS, VE-cadherin, β-catenin and γ-catenin expression were significantly up-regulated by TXL compared with IPC (P>0.05) or CCB (P<0.05) and these five microvascular barrier-related indices may be the key targets of TXL in minimizing IRI. Conclusions Our study underlines the lethal IRI as one of the causes of myocardial necrosis. Pretreatment with TXL ameliorates myocardial IRI through promoting cardiac microvascular endothelial barrier function by simulating IPC. PMID:25781461

  4. Dielectric properties of highly resistive GaN crystals grown by ammonothermal method at microwave frequencies

    NASA Astrophysics Data System (ADS)

    Krupka, Jerzy; Zajåc, Marcin; Kucharski, Robert; Gryglewski, Daniel

    2016-03-01

    Permittivity, the dielectric loss tangent and conductivity of semi-insulating Gallium Nitride crystals have been measured as functions of frequency from 10 GHz to 50 GHz and temperature from 295 to 560 K employing quasi TE0np mode dielectric resonator technique. Crystals were grown using ammonothermal method. Two kinds of doping were used to obtain high resistivity crystals; one with deep acceptors in form of transition metal ions, and the other with shallow Mg acceptors. The sample compensated with transition metal ions exhibited semi-insulating behavior in the whole temperature range. The sample doped with Mg acceptors remained semi-insulating up to 390 K. At temperatures exceeding 390 K the conductivity term in the total dielectric loss tangent of Mg compensated sample becomes dominant and it increases exponentially with activation energy of 1.14 eV. It has been proved that ammonothermal method with appropriate doping allows growth of high quality, temperature stable semi-insulating GaN crystals.

  5. Multidrug-resistant tuberculosis treatment failure detection depends on monitoring interval and microbiological method

    PubMed Central

    White, Richard A.; Lu, Chunling; Rodriguez, Carly A.; Bayona, Jaime; Becerra, Mercedes C.; Burgos, Marcos; Centis, Rosella; Cohen, Theodore; Cox, Helen; D'Ambrosio, Lia; Danilovitz, Manfred; Falzon, Dennis; Gelmanova, Irina Y.; Gler, Maria T.; Grinsdale, Jennifer A.; Holtz, Timothy H.; Keshavjee, Salmaan; Leimane, Vaira; Menzies, Dick; Milstein, Meredith B.; Mishustin, Sergey P.; Pagano, Marcello; Quelapio, Maria I.; Shean, Karen; Shin, Sonya S.; Tolman, Arielle W.; van der Walt, Martha L.; Van Deun, Armand; Viiklepp, Piret

    2016-01-01

    Debate persists about monitoring method (culture or smear) and interval (monthly or less frequently) during treatment for multidrug-resistant tuberculosis (MDR-TB). We analysed existing data and estimated the effect of monitoring strategies on timing of failure detection. We identified studies reporting microbiological response to MDR-TB treatment and solicited individual patient data from authors. Frailty survival models were used to estimate pooled relative risk of failure detection in the last 12 months of treatment; hazard of failure using monthly culture was the reference. Data were obtained for 5410 patients across 12 observational studies. During the last 12 months of treatment, failure detection occurred in a median of 3 months by monthly culture; failure detection was delayed by 2, 7, and 9 months relying on bimonthly culture, monthly smear and bimonthly smear, respectively. Risk (95% CI) of failure detection delay resulting from monthly smear relative to culture is 0.38 (0.34–0.42) for all patients and 0.33 (0.25–0.42) for HIV-co-infected patients. Failure detection is delayed by reducing the sensitivity and frequency of the monitoring method. Monthly monitoring of sputum cultures from patients receiving MDR-TB treatment is recommended. Expanded laboratory capacity is needed for high-quality culture, and for smear microscopy and rapid molecular tests. PMID:27587552

  6. Design strategies for development of SCR catalyst: improvement of alkali poisoning resistance and novel regeneration method.

    PubMed

    Peng, Yue; Li, Junhua; Shi, Wenbo; Xu, Jiayu; Hao, Jiming

    2012-11-20

    Based on the ideas of the additives modification and regeneration method update, two different strategies were designed to deal with the traditional SCR catalyst poisoned by alkali metals. First, ceria doping on the V(2)O(5)-WO(3)/TiO(2) catalyst could promote the SCR performance even reducing the V loading, which resulted in the enhancement of the catalyst's alkali poisoning resistance. Then, a novel method, electrophoresis treatment, was employed to regenerate the alkali poisoned V(2)O(5)-WO(3)/TiO(2) catalyst. This novel technique could dramatically enhance the SCR activities of the alkali poisoned catalysts by removing approximately 95% K or Na ions from the catalyst and showed less hazardous to the environment. Finally, the deactivation mechanisms by the alkali metals were extensively studied by employing both the experimental and DFT theoretical approaches. Alkali atom mainly influences the active site V species rather than W oxides. The decrease of catalyst surface acidity might directly reduce the catalytic activity, while the reducibility of catalysts could be another important factor.

  7. A Method for Measuring the Volume of Transdermally Extracted Interstitial Fluid by a Three-Electrode Skin Resistance Sensor

    PubMed Central

    Li, Dachao; Wang, Ridong; Yu, Haixia; Li, Guoqing; Sun, Yue; Liang, Wenshuai; Xu, Kexin

    2014-01-01

    It is difficult to accurately measure the volume of transdermally extracted interstitial fluid (ISF), which is important for improving blood glucose prediction accuracy. Skin resistance, which is a good indicator of skin permeability, can be used to determine the volume of extracted ISF. However, it is a challenge to realize in vivo longitudinal skin resistance measurements of microareas. In this study, a three-electrode sensor was presented for measuring single-point skin resistance in vivo, and a method for determining the volume of transdermally extracted ISF using this sensor was proposed. Skin resistance was measured under static and dynamic conditions. The correlation between the skin resistance and the permeation rate of transdermally extracted ISF was proven. The volume of transdermally extracted ISF was determined using skin resistance. Factors affecting the volume prediction accuracy of transdermally extracted ISF were discussed. This method is expected to improve the accuracy of blood glucose prediction, and is of great significance for the clinical application of minimally invasive blood glucose measurement. PMID:24759111

  8. An experimental method to determine the resistance of a vertically aligned carbon nanotube forest in contact with a conductive layer

    NASA Astrophysics Data System (ADS)

    Vo, T. T.; Poulain, C.; Dijon, J.; Fournier, A.; Chevalier, N.; Mariolle, D.

    2012-08-01

    High density vertically aligned carbon nanotube (VACNT) forests are considered as a promising conductive material for many applications (interconnects in microelectronics or contact material layer in sliding contact applications). It is thus crucial to characterize the electrical resistance of these forests, especially in contact with the inherent top/bottom conductive substrates. This paper aims to develop an original method to determine the contribution of the different terms in this electrical resistance, which is measured with a tipless atomic force microscope used in high accuracy "force mode." VACNT stacks with different heights on AlCu substrate with or without Au/Pd top coating are studied. The electrical contact area between the probe tip and the forest is considered to be equivalent to the classical electrical contact area between a tip and a rough surface. With this assumption, the scattering resistance of a mono-wall CNT is 14.6 kΩ μm-1, the top/bottom contact resistance is, respectively, 265 kΩ/385 kΩ. The bottom resistance divided in half is obtained by an interface substrate/CNT catalyst treatment. The same assumption leads to an effective compressive modulus of 175 MPa. These results are consistent with the values published by other authors. The proposed method is effective to optimise the CNT interface contact resistance before integration in a more complex functional structure.

  9. Effects of cold on microvascular fluid movement in the cat limb.

    PubMed

    Zhang, J X; Wolf, M B

    1991-08-01

    We investigated the effects of low temperatures down to approximately 5 degrees C on postcapillary resistance (Rv) and isogravimetric capillary pressure (Pci) in the isolated constant-flow-perfused cat hindlimb to see if a low-temperature-induced increase in Rv and decrease in Pci could lead to an increase in filtration pressure and edema formation. A low-viscosity perfusate (20% cat plasma, 80% albumin-electrolyte solution; viscosity approximately 1 cP) was used. Isoproterenol (10(-7) M) was added to vasodilate the limb and achieve normal microvascular permeability. Rv and Pci were estimated from the slope and zero-flow intercept, respectively, of the straight-line fit to the isogravimetric venous pressure vs. flow data. Rv and Pci were determined in each experiment at an initial 37 degrees C control, at a lowered temperature (30, 23, 15, or 5-10 degrees C), and then at 37 degrees C again. The ratio of Rv at the low temperatures relative to the initial 37 degrees C control increased almost linearly as temperature was reduced. The increase was 3.4 times control at the lowest temperature. Pci decreased significantly from control only in the lowest temperature group where the change was -5.4 mmHg. Analysis of our data with the low-viscosity perfusate shows that the limb can become edematous if temperature is lowered to approximately 5 degrees C unless venous pressure (Pv) is lowered to venous collapse and flow reduced to less than approximately 20 ml.min-1.100g-1.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1938745

  10. Thrombin enhances the barrier function of rat microvascular endothelium in a PAR-1-dependent manner.

    PubMed

    Troyanovsky, B; Alvarez, D F; King, J A; Schaphorst, K L

    2008-02-01

    Thrombin is a multifunctional coagulation protease with pro- and anti-inflammatory vascular effects. We questioned whether thrombin may have segmentally differentiated effects on pulmonary endothelium. In cultured rat endothelial cells, rat thrombin (10 U/ml) recapitulated the previously reported decrease in transmonolayer electrical resistance (TER), F-actin stress fiber formation, paracellular gap formation, and increased permeability. In contrast, in rat pulmonary microvascular endothelial cells (PMVEC), isolated on the basis of Griffonia simplicifolia lectin recognition, thrombin increased TER, induced fewer stress fibers, and decreased permeability. To assess for differential proteinase-activated receptor (PAR) expression as a basis for the different responses, PAR family expression was analyzed. Both pulmonary artery endothelial cells and PMVEC expressed PAR-1 and PAR-2; however, only PMVEC expressed PAR-3, as shown by both RT-PCR and Western analysis. PAR-1 activating peptides (PAR-APs: SFLLRN-NH(2) and TFLLRN-NH(2)) were used to confirm a role for the PAR-1 receptor. PAR-APs (25-250 muM) also increased TER, formed fewer stress fibers, and did not induce paracellular gaps in PMVEC in contrast to that shown in pulmonary artery endothelial cells. These results were confirmed in isolated perfused rat lung preparations. PAR-APs (100 mug/ml) induced a 60% increase in the filtration coefficient over baseline. However, by transmission electron microscopy, perivascular fluid cuffs were seen only along conduit veins and arteries without evidence of intra-alveolar edema. We conclude that thrombin exerts a segmentally differentiated effect on endothelial barrier function in vitro, which corresponds to a pattern of predominant perivascular fluid cuff formation in situ. This may indicate a distinct role for thrombin in the microcirculation. PMID:18083763

  11. Methylene blue solder re-absorption in microvascular anastomoses

    NASA Astrophysics Data System (ADS)

    Birch, Jeremy F.; Hepplewhite, J.; Frier, Malcolm; Bell, Peter R. F.

    2003-06-01

    Soldered vascular anastomoses have been reported using several chromophores but little is known of the optimal conditions for microvascular anastomosis. There are some indications of the optimal protein contents of a solder, and the effects of methylene blue on anastomotic strength. The effects of varying laser power density in vivo have also been described, showing a high rate of thrombosis with laser power over 22.9Wcm-2. However no evidence exists to describe how long the solder remains at the site of the anastomosis. Oz et al reported that the fibrin used in their study had been almost completely removed by 90 days but without objective evidence of solder removal. In order to address the issue of solder re-absorption from the site of an anastomosis we used radio-labelled albumin (I-125) incorporated into methylene blue based solder. This was investigated in both the situation of the patent and thrombosed anastomosis with anastomoses formed at high and low power. Iodine-125 (half life: 60.2 days) was covalently bonded to porcine albumin and mixed with the solder solution. Radio-iodine has been used over many years to determine protein turnover using either I-125 or I-131. Iodine-125 labelled human albumin is regularly used as a radiopharmaceutical tool for the determination of plasma volume. Radio-iodine has the advantages of not affecting protein metabolism and the label is rapidly excreted after metabolic breakdown. Labelling with chromium (Cr-51) causes protein denaturation and is lost from the protein with time. Labelled albumin has been reported in human studies over a 21-day period, with similar results reported by Matthews. Most significantly McFarlane reported a different rate of catabolism of I-131 and I-125 over a 22-day period. The conclusion from this is that the rate of iodine clearance is a good indicator of protein catabolism. In parallel with the surgery a series of blank standards were prepared with a known mass of solder to correct for isotope

  12. Mst1 inhibits CMECs autophagy and participates in the development of diabetic coronary microvascular dysfunction

    PubMed Central

    Lin, Jie; Zhang, Lei; Zhang, Mingming; Hu, Jianqiang; Wang, Tingting; Duan, Yu; Man, Wanrong; Wu, Bin; Feng, Jiaxu; Sun, Lei; Li, Congye; Zhang, Rongqing; Wang, Haichang; Sun, Dongdong

    2016-01-01

    Cardiovascular complications account for a substantial proportion of morbidity and mortality in diabetic patients. Abnormalities of cardiac microvascular endothelial cells (CMECs) lead to impaired cardiac microvascular vessel integrity and subsequent cardiac dysfunction, underlining the importance of coronary microvascular dysfunction. In this study, experimental diabetes models were constructed using Mst1 transgenic, Mst1 knockout and sirt1 knockout mice. Diabetic Mst1 transgenic mice exhibited impaired cardiac microvessel integrity and decreased cardiac function. Mst1 overexpression deceased CMECs autophagy as evidenced by decreased LC3 expression and enhanced protein aggregation when subjected to high glucose culture. Mst1 knockout improved cardiac microvessel integrity and enhanced cardiac functions in diabetic mice. Mst1 knockdown up-regulated autophagy as indicated by more typical autophagosomes and increased LC3 expression in CMECs subjected to high glucose cultures. Mst1 knockdown also promoted autophagic flux in the presence of bafilomycin A1. Mst1 overexpression increased CMECs apoptosis, whereas Mst1 knockout decreased CMECs apoptosis. Sirt1 knockout abolished the effects of Mst1 overexpression in cardiac microvascular injury and cardiac dysfunction. In conclusion, Mst1 knockout preserved cardiac microvessel integrity and improved cardiac functions in diabetic mice. Mst1 decreased sirt1 activity, inhibited autophagy and enhanced apoptosis in CMECs, thus participating in the pathogenesis of diabetic coronary microvascular dysfunction. PMID:27680548

  13. Conditioned Media from Microvascular Endothelial Cells Cultured in Simulated Microgravity Inhibit Osteoblast Activity

    PubMed Central

    Cazzaniga, Alessandra; Castiglioni, Sara; Maier, Jeanette A. M.

    2014-01-01

    Background and Aims. Gravity contributes to the maintenance of bone integrity. Accordingly, weightlessness conditions during space flight accelerate bone loss and experimental models in real and simulated microgravity show decreased osteoblastic and increased osteoclastic activities. It is well known that the endothelium and bone cells cross-talk and this intercellular communication is vital to regulate bone homeostasis. Because microgravity promotes microvascular endothelial dysfunction, we anticipated that the molecular cross-talk between endothelial cells exposed to simulated microgravity and osteoblasts might be altered. Results. We cultured human microvascular endothelial cells in simulated microgravity using the rotating wall vessel device developed by NASA. Endothelial cells in microgravity show growth inhibition and release higher amounts of matrix metalloproteases type 2 and interleukin-6 than controls. Conditioned media collected from microvascular endothelial cells in simulated microgravity were used to culture human osteoblasts and were shown to retard osteoblast proliferation and inhibit their activity. Discussion. Microvascular endothelial cells in microgravity are growth retarded and release high amounts of matrix metalloproteases type 2 and interleukin-6, which might play a role in retarding the growth of osteoblasts and impairing their osteogenic activity. Conclusions. We demonstrate that since simulated microgravity modulates microvascular endothelial cell function, it indirectly impairs osteoblastic function. PMID:25210716

  14. [Coronary microvascular dysfunction : Clinical aspects, diagnosis and therapy].

    PubMed

    Ong, P; Sechtem, U

    2016-06-01

    Just as in epicardial coronary stenosis, coronary microvascular dysfunction (CMD) also leads to an imbalance of myocardial oxygen supply and demand. The dysfunction is located at the level of the coronary microcirculation with vessel diameters < 500 µm and structural as well as functional alterations have been described. The underlying mechanisms are diverse, frequently overlap and are still incompletely understood. Among others, conditions such as chronic inflammation, estrogen deficiency and a genetic familial predisposition have been reported. A common and often underdiagnosed clinical manifestation of CMD is found in patients who have symptoms of angina pectoris but no obstructive epicardial coronary artery disease or myocardial disease. The CMD can be diagnosed using non-invasive procedures, such as the combination of coronary computed tomography (CT) angiography and cardiac stress magnetic resonance imaging (MRI) or coronary CT and positron emission tomography (PET). In addition, invasive coronary vasomotor assessment is also suitable. Very little evidence is available regarding the effectiveness of pharmacological treatment of CMD. The current European Society of Cardiology (ESC) guidelines on the management of stable coronary artery disease from 2013 recommend using acetylsalicylic acid (ASS) and a statin as well as beta blockers and/or calcium channel blockers. Patients with CMD have an elevated risk for coronary events and death of approximately 1.7 % per year. Moreover, there is an increased morbidity with frequent presentations in practices and emergency admissions. Clinical research efforts should aim at a better characterization of the underlying mechanisms of CMD in order to develop targeted treatment approaches. PMID:27255117

  15. Novel Biomarkers of Arterial and Venous Ischemia in Microvascular Flaps

    PubMed Central

    Nguyen, Gerard K.; Monahan, John F. W.; Davis, Gabrielle B.; Lee, Yong Suk; Ragina, Neli P.; Wang, Charles; Zhou, Zhao Y.; Hong, Young Kwon; Spivak, Ryan M.; Wong, Alex K.

    2013-01-01

    both diagnose and successfully treat microvascular complications before irreversible tissue damage and flap loss occurs. PMID:23977093

  16. The analytical methods used in examining resistance of hydrogeological systems to anthropogenic pollution

    NASA Astrophysics Data System (ADS)

    Najman, Joanna; Bielewski, Jarosław; Śliwka, Ireneusz

    2013-04-01

    key words: gas chromatography (GC) measurement method, groundwater dating, He, SF6, F-11, F-12, Ar, Ne. In this work the method for evaluating resistance hydrogeological systems to anthropogenic pollution using environmental tracers is described. Resistance groundwater systems to anthropogenic pollution is correlated with the age of water, which can be determined by means of environmental tracers SF6, F-11, F-12 [1] and He. To correct measured values of He and SF6 the temperature of recharge and the excess air is needed and can be determined by measuring Ne and Ar concentrations in groundwater. This paper describes three measurement GC systems to determine the concentrations of greenhouse gases: sulfur hexafluoride (SF6) and chlorofluorocarbons F-11, F-12 [2], the noble gases neon (Ne), argon (Ar) [3] and helium (He) [4] in groundwater. The first system for measurements of the concentration of SF6, F-11 and F-12 consists of a gas chromatograph, type N504 is supplied with nitrogen carrier gas with a purity of 6.0. It is equipped with two packed columns K1 and K2 running at 60°C with the use of the "back-flush" column switching and electron capture detector (ECD) operating at 300°C. Second system for measuring the concentration of the noble gases argon and neon, is composed of a dual Shimadzu gas chromatograph. It is equipped with two columns K4 and K5 operating at 30°C, thermalconductivity detector (TCD) for analysis of argon and helium detector with pulse discharge (PDHID) for analysis of neon. This chromatograph is powered by helium carrier gas 6.0. The third system measures the concentration of helium, consists of a gas chromatograph equipped with a TCD detector and three packed columns filled with molecular sieve type 5A and activated carbon. The carrier gas in this system is argon 6.0. Detection limit, LOD for each measurement systems for the tested compounds are: 0,06 fmol/L for SF6, 15 fmol/L for F-11, 10 fmol/L for F-12, 1,9•10-8 cm3STP/cm3 for Ne, 3,1

  17. Microvascular hemodynamics in experimental arthritis: disparity between the distribution of microspheres and plasma flow in bone.

    PubMed

    Hansen, E S; Søballe, K; Kjølseth, D; Henriksen, T B; He, S Z

    1990-09-01

    The microcirculation in normal and arthritic juxtaarticular bone was studied in 16 young dogs with carragheenan-induced arthritis of one knee. The regional blood flow was determined by the tissue uptake of intracardially injected 15-microns 141Ce-labeled microspheres, and the microvascular plasma volume was determined by the distribution space of circulating 125I-fibrinogen. Disparities between the distribution of plasma flow and microspheres, introduced by plasma skimming or nonentrapment of spheres in the intraosseous circulation, were estimated by 59Fe-transferrin, a third intravascular tracer, injected as a bolus intracardially and trapped peripherally after 15 sec by prompt circulatory arrest. The tissue uptake of the plasma flow tracer was compared to that of microspheres by the ratio between observed and expected activity of 59Fe-transferrin, the expected activity being calculated from the microsphere distribution. The transferrin and microsphere uptake agreed well in patella, marginal epiphyseal bone, and cortical bone, whereas observed activity of transferrin was twice the expected in central epiphyseal bone, three times higher in marrow, and up to eightfold higher in metaphyses adjacent to growth plates. This discrepancy was significantly greater in arthritic bone when the metaphyses were examined in toto. The microsphere method thus appears to underestimate blood flow to cancellous bone and marrow due to uneven distribution of plasma and formed elements from profound plasma skimming and perhaps also by AV shunting. PMID:2250600

  18. Evidence of endoplasmic reticulum-related Ca sup 2+ ATPase in human microvascular endothelial cells

    SciTech Connect

    Bikfalvi, A.; Enouf, J.; Bredoux, R.; Dupuy, E.; Bourdeau, N.; Levy-Toledano, S.; Tobelem, G. ); Lompre, A. )

    1989-09-01

    The authors demonstrated by immunological and molecular methods the presence of a reticulum endoplasmic-related Ca{sup 2+}-ATPase in human omental microvascular endothelial cells (HOME cells). HOME cells reacted positively with a previously characterized sarcoplasmic reticulum Ca{sup 2+}-ATPase antibody as demonstrated by indirect immunofluorescence. Western blotting revealed that the antibody recognized a 95-100 kDa protein. {sup 35}S-Metabolic labeling led to the detection of a similar protein with which the purified sarcoplasmic reticulum Ca{sup 2+}-ATPase compete. Dot-blotting experiments indicated that a substantial amount of Ca{sup 2+}-ATPase was present in HOME cell membranes. In addition, Northern blot analysis using a cDNA probe from cardiac sarcoplasmic reticulum showed the presence of mRNA species of 4 kb. As these experiments were conducted in comparison with cell types with well-defined Ca{sup 2+}-ATPases, the results suggest the presence of a endoplasmic reticulum-related Ca{sup 2+}-ATPase in HOME cells.

  19. The Effect of Microvascular Decompression for Hemifacial Spasm Caused by Vertebrobasilar Dolichoectasia

    PubMed Central

    Kang, Jeong-Han; Kang, Dong-Wan; Chung, Sang Sup

    2012-01-01

    Objective Hemifacial spasm (HFS) caused by vertebrobasilar dolichoectasia (VBD) is very rare, and in theses cases, it is difficult to decompress the nerve from its vascular compression. The objective of this study was to investigate the outcome of microvascular decompression (MVD) for HFS caused by VBD. Methods There were 10 patients of HFS caused by VBD at our hospital between September 1978 and September 2008. We evaluated magnetic resonance angiography (MRA) and time of flight magnetic resonance imaginge (TOF MRI) findings using the criteria for VBD. We compared the clinical outcomes of MVD for the 10 patients with VBD with the overall outcomes of the total 2058 MVDs performed for HFS. Results The results of MVD for HFS caused by VBD were successful in 90.9% of cases. The postoperative complication rate in VBD was 45.5%. Offending vessels in patients with VBD were identified visually during surgery. Adverse effects after MVD were found in 4 patients. We found that the diameter of VBD was significantly greater in patients with complications than in those with no complications (p=0.028). Conclusion Our data shows that MVD may be a good treatment modality for HFS caused by VBD but care must be taken to avoid adverse effects from the procedure. It is important to detach the dolichoectatic artery from its surrounding structures sufficiently to allow it to be easily movable. In addition, attempts should be made to lessen the retraction of the cerebellum during release of the dolichoectatic artery. PMID:23091664

  20. Application of a Novel Microvascular Imaging Technique in Breast Lesion Evaluation.

    PubMed

    Yongfeng, Zhao; Ping, Zhou; Wengang, Liu; Yang, Shao; Shuangming, Tian

    2016-09-01

    Conventional power Doppler imaging (PDI) and the novel Superb Microvascular Imaging (SMI) technique were applied to observe the distribution of microvessels in 135 breast lesions, using semi-quantitative grading, penetrating vessel evaluation and flow distribution pattern to evaluate diagnostic efficacy. Compared with PDI, SMI detected more flow signals and details of microvessels. Further, when a centrally distributed branching or diffusing mode was used as a criterion for diagnosing malignancy, SMI improved diagnosis of breast masses. Sensitivity, specificity, positive predictive value and negative predictive value of SMI-assessed flow distribution were 85.4%, 92.6%, 83.3% and 93.5%, respectively, compared with 70.7%, 92.6%, 80.5% and 87.9% for PDI. We also found that flow distribution pattern analysis is superior to semi-quantitative grading and the penetrating vessel method in differentiating malignant breast lesions. Our work here further supports SMI as a novel and promising technique in visualizing microvasculature in breast lesions that may be of paramount use in initial diagnosis as well as follow-up assessment in various treatment regimes.

  1. The Diagnostic Value of Superb Microvascular Imaging (SMI) in Detecting Blood Flow Signals of Breast Lesions

    PubMed Central

    Ma, Yan; Li, Gang; Li, Jing; Ren, Wei-dong

    2015-01-01

    Abstract The correlation between color Doppler flow imaging (CDFI) and Superb Microvascular Imaging (SMI) for detecting blood flow in breast lesions was investigated, as was the diagnostic value of SMI in differentiating benign from malignant breast lesions. These lesions were evaluated using both CDFI and SMI according to Adler's method. Pathologic examination showed 57 malignant lesions and 66 benign lesions. The number of blood vessels in a single mass was detected by 2 techniques (SMI and CDFI), and the difference between the 2 values (SMI-CDFI) was calculated. The optimal threshold for the diagnosis of malignant neoplasms and the diagnostic performances of SMI, CDFI, and SMI-CDFI were calculated. For the total lesions and malignant lesions alone, the difference between SMI and CDFI for detecting blood flow was significant (P < 0.01), but the difference was not significant for benign lesions (P = 0.15). The area under the receiver operating characteristic curve was 0.73 (95% confidence interval [CI]: 0.64–0.82) for CDFI; 0.81 (95% CI: 0.74–0.89) for SMI; and 0.89 (95% CI: 0.82–0.95) for SMI-CDFI. Furthermore, the modality of “SMI-CDFI” showed the best diagnostic performance. SMI provides further microvessel information in breast lesions. The diagnostic modality of “SMI-CDFI” can improve the diagnostic performance of ultrasound in the differentiation between benign and malignant masses. PMID:26356718

  2. Bioglue-Coated Teflon Sling Technique in Microvascular Decompression for Hemifacial Spasm Involving the Vertebral Artery

    PubMed Central

    Lee, Seong Ho; Park, Jae Sung

    2016-01-01

    Objective Microvascular decompression (MVD) for hemifacial spasm (HFS) involving the vertebral artery (VA) can be technically challenging. We investigated the therapeutic effects of a bioglue-coated Teflon sling technique on the VA during MVD in 42 cases. Methods A bioglue-coated Teflon sling was crafted by the surgeon and applied to patients in whom neurovascular compression was caused by the VA. The radiologic data, intra-operative findings with detailed introduction of the procedure, and the clinical outcomes of each patient were reviewed and analyzed. Results The 42 patients included in the analysis consisted of 22 females and 20 males, with an average follow-up duration of 76 months (range 24–132 months). Intraoperative investigation revealed that an artery other than the VA was responsible for the neurovascular compression in all cases : posterior inferior cerebellar artery (PICA) in 23 patients (54.7%) and anterior inferior cerebellar artery (AICA) in 11 patients (26.2%). All patients became symptom-free after MVD. Neither recurrence nor postoperative neurological deficit was noted during the 2-year follow-up, except in one patient who developed permanent deafness. Cerebrospinal fluid (CSF) leak occurred in three patients, and one required dural repair. Conclusion Transposition of the VA using a bioglue-coated Teflon sling is a safe and effective surgical technique for HFS involving the VA. A future prospective study to compare clinical outcomes between groups with and without use of this novel technique is required. PMID:27651870

  3. Microvascular decompression for glossopharyngeal neuralgia using intraoperative neurophysiological monitoring: Technical case report

    PubMed Central

    Motoyama, Yasushi; Nakagawa, Ichiro; Takatani, Tsunenori; Park, Hun-Soo; Kotani, Yukiko; Tanaka, Yoshitaka; Gurung, Pritam; Park, Young-Soo; Nakase, Hiroyuki

    2016-01-01

    Background: Glossopharyngeal neuralgia (GN) is a rare functional disorder representing around 1% of cases of trigeminal neuralgia. Lancinating throat and ear pain while swallowing are the typical manifestations, and are initially treated using anticonvulsants such as carbamazepine. Medically refractory GN is treated surgically. Microvascular decompression (MVD) is reportedly effective against GN, superseding rhizotomy and tractotomy. Methods: We encountered three patients with medically refractory GN who underwent MVD using intraoperative neurophysiological monitoring (IONM). The offending vessels were the posterior inferior cerebellar arteries, which were confirmed intraoperatively via a transcondylar fossa approach to be affecting the root exit zones of the glossopharyngeal and vagus nerves. As IONM, facial motor-evoked potentials (MEPs) and brainstem auditory-evoked potentials were monitored during microsurgery in all three patients. Pharyngeal and vagal MEPs were added for two patients to avoid postoperative dysphagia. Results: GN disappeared immediately after surgery with complete preservation of hearing acuity and facial nerve function. Transient mild swallowing disturbance was observed in 1 patient without pharyngeal or vagal MEPs, whereas the remaining two patients with pharyngeal and vagal MEPs demonstrated no postoperative dysphagia. Conclusion: Although control of severe pain is expected in surgical intervention for GN, lower cranial nerves are easily damaged because of their fragility, even in MVD. IONM including pharyngeal and vagal MEPs appears very useful for avoiding postoperative sequelae during MVD for GN. PMID:26862458

  4. Microvascular Obstruction Evaluation Using Cardiovascular Magnetic Resonance (CMR) in ST-Elevated Myocardial Infarction (STEMI) Patients

    PubMed Central

    Piotrowska-Kownacka, Dorota; Kownacki, Łukasz; Kochman, Janusz; Kołodzińska, Agnieszka; Kobylecka, Małgorzata; Królicki, Leszek

    2015-01-01

    Summary Backround Restoration of blood flow in epicardial coronary artery in patients with acute myocardial infarction can, but does not have to restore efficient blood flow in coronary circulation. The aim of the study was a direct comparison of microvascular obstruction (MVO) detected by rest and stress perfusion imaging and gadolinium enhancement obtained 2 min. (early MVO) and 15 min. (delayed MVO) post contrast. Material/Methods 106 patients with first anterior myocardial infarction were studied. Cardiovascular magnetic resonance (CMR) was performed 5±2 days after primary percutaneous coronary intervention (pPCI). Stress and rest perfusion imaging was performed as well as early and delayed gadolinium enhancement and systolic function assessment. Scoring of segmental function, perfusion defect, MVO and scar transmurality was performed in 16 segment left ventricular model. Results The prevalence of MVO varies significantly between imaging techniques ranging from 48.8% for delayed MVO to 94% with stress perfusion. Median sum of scores was significantly different for each technique: stress perfusion 13 (7; 18), rest perfusion 3 (0.5; 6), early MVO 3 (0; 8), delayed MVO 0 (0; 4); p<0.05. Infarct size, stress and rest perfusion defects were independent predictors of LV EF at discharge from hospital. Conclusions Imaging protocol has a significant impact on MVO results. The study is the first to describe a stress-induced MVO in STEMI patients. Further research is needed to evaluate its impact on a long term prognosis. PMID:26740825

  5. Sacrificial component fabrication for optimised production of micro-vascular polymer composite

    NASA Astrophysics Data System (ADS)

    Dalton, B.; Dixon, D.; McIlhagger, A.; Archer, E.

    2015-02-01

    Smart functional materials are a viable future goal for advanced applications in aerospace, space and medical applications. In this work micro-vascular polymer composite systems have been developed using sacrificial fibres produced from catalyst loaded Poly(lactic acid). The sacrificial fibres have been produced via a published technique which treated PLA in a solvent catalyst mixture of 60% Trifluoroethanol, 40% H2O dispersed with 10 wt% tin (II) oxalate catalyst. A second process of polymer extrusion of PLA using graded fill contents of tin (II) oxalate has also been developed for the up scaled production of fibres as an alternative to solution treatment. Thermal analysis (TGA) was used to compare sacrificial fibre specimens. PLA fibres produced via the polymer extrusion method outperformed solution treated fibres displaying a lower degradation onset temperature (average 25°C lower), higher degradation rates (observed through a derivative curve comparison) and lower residual catalyst content (0.67% solvent treated fibre against 0.16% extruded fibre). The continuous extrusion process is solvent free and is suitable for high volume production. This work has been carried out to fully understand the fabrication issues with sacrificial components.

  6. Continuous Dynamic Registration of Microvascularization of Liver Tumors with Contrast-Enhanced Ultrasound

    PubMed Central

    Wiesinger, Isabel; Stroszczynski, Christian; Wiggermann, Philipp; Jung, Ernst-Michael

    2014-01-01

    Aim. To evaluate the diagnostic value of quantification of liver tumor microvascularization using contrast-enhanced ultrasound (CEUS) measured continuously from the arterial phase to the late phase (3 minutes). Material and Methods. We present a retrospective analysis of 20 patients with malignant (n = 13) or benign (n = 7) liver tumors. The tumors had histopathologically been proven or clearly identified using contrast-enhanced reference imaging with either 1.5 T MRI (liver specific contrast medium) or triphase CT and follow-up. CEUS was performed using a multifrequency transducer (1–5 MHz) and a bolus injection of 2.4 mL sulphur hexafluoride microbubbles. A retrospective perfusion analysis was performed to determine TTP (time-to-peak), RBV (regional blood volume), RBF (regional blood flow), and Peak. Results. Statistics revealed a significant difference (P < 0.05) between benign and malignant tumors in the RBV, RBF, and Peak but not in TTP (P = 0.07). Receiver operating curves (ROC) were generated for RBV, RBF, Peak, and TTP with estimated ROC areas of 0.97, 0.96, 0.98, and 0.76, respectively. Conclusion. RBV, RBF, and Peak continuously measured over a determined time period of 3 minutes could be of valuable support in differentiating malignant from benign liver tumors. PMID:24991432

  7. Bioglue-Coated Teflon Sling Technique in Microvascular Decompression for Hemifacial Spasm Involving the Vertebral Artery

    PubMed Central

    Lee, Seong Ho; Park, Jae Sung

    2016-01-01

    Objective Microvascular decompression (MVD) for hemifacial spasm (HFS) involving the vertebral artery (VA) can be technically challenging. We investigated the therapeutic effects of a bioglue-coated Teflon sling technique on the VA during MVD in 42 cases. Methods A bioglue-coated Teflon sling was crafted by the surgeon and applied to patients in whom neurovascular compression was caused by the VA. The radiologic data, intra-operative findings with detailed introduction of the procedure, and the clinical outcomes of each patient were reviewed and analyzed. Results The 42 patients included in the analysis consisted of 22 females and 20 males, with an average follow-up duration of 76 months (range 24–132 months). Intraoperative investigation revealed that an artery other than the VA was responsible for the neurovascular compression in all cases : posterior inferior cerebellar artery (PICA) in 23 patients (54.7%) and anterior inferior cerebellar artery (AICA) in 11 patients (26.2%). All patients became symptom-free after MVD. Neither recurrence nor postoperative neurological deficit was noted during the 2-year follow-up, except in one patient who developed permanent deafness. Cerebrospinal fluid (CSF) leak occurred in three patients, and one required dural repair. Conclusion Transposition of the VA using a bioglue-coated Teflon sling is a safe and effective surgical technique for HFS involving the VA. A future prospective study to compare clinical outcomes between groups with and without use of this novel technique is required.

  8. Meticillin-resistant Staphylococcus aureus (MRSA): global epidemiology and harmonisation of typing methods.

    PubMed

    Stefani, Stefania; Chung, Doo Ryeon; Lindsay, Jodi A; Friedrich, Alex W; Kearns, Angela M; Westh, Henrik; Mackenzie, Fiona M

    2012-04-01

    This article reviews recent findings on the global epidemiology of healthcare-acquired/associated (HA), community-acquired/associated (CA) and livestock-associated (LA) meticillin-resistant Staphylococcus aureus (MRSA) and aims to reach a consensus regarding the harmonisation of typing methods for MRSA. MRSA rates continue to increase rapidly in many regions and there is a dynamic spread of strains across the globe. HA-MRSA is currently endemic in hospitals in most regions. CA-MRSA clones have been spreading rapidly in the community and also infiltrating healthcare in many regions worldwide. To date, LA-MRSA is only prevalent in certain high-risk groups of workers in direct contact with live animals. CA-MRSA and LA-MRSA have become a challenge for countries that have so far maintained low rates of MRSA. These evolutionary changes have resulted in MRSA continuing to be a major threat to public health. Continuous efforts to understand the changing epidemiology of S. aureus infection in humans and animals are therefore necessary, not only for appropriate antimicrobial treatment and effective infection control but also to monitor the evolution of the species. The group made several consensus decisions with regard to harmonisation of typing methods. A stratified, three-level organisation of testing laboratories was proposed: local; regional; and national. The functions of, and testing methodology used by, each laboratory were defined. The group consensus was to recommend spa and staphylococcal cassette chromosome mec (SCCmec) typing as the preferred methods. Both are informative in defining particular strain characteristics and utilise standardised nomenclatures, making them applicable globally. Effective communication between each of the different levels and between national centres was viewed as being crucial to inform and monitor the molecular epidemiology of MRSA at national and international levels.

  9. Evaluation of a Cost Effective In-House Method for HIV-1 Drug Resistance Genotyping Using Plasma Samples

    PubMed Central

    Chaturbhuj, Devidas N.; Nirmalkar, Amit P.; Paranjape, Ramesh S.; Tripathy, Srikanth P.

    2014-01-01

    Objectives Validation of a cost effective in-house method for HIV-1 drug resistance genotyping using plasma samples. Design The validation includes the establishment of analytical performance characteristics such as accuracy, reproducibility, precision and sensitivity. Methods The accuracy was assessed by comparing 26 paired Virological Quality Assessment (VQA) proficiency testing panel sequences generated by in-house and ViroSeq Genotyping System 2.0 (Celera Diagnostics, US) as a gold standard. The reproducibility and precision were carried out on five samples with five replicates representing multiple HIV-1 subtypes (A, B, C) and resistance patterns. The amplification sensitivity was evaluated on HIV-1 positive plasma samples (n = 88) with known viral loads ranges from 1000–1.8 million RNA copies/ml. Results Comparison of the nucleotide sequences generated by ViroSeq and in-house method showed 99.41±0.46 and 99.68±0.35% mean nucleotide and amino acid identity respectively. Out of 135 Stanford HIVdb listed HIV-1 drug resistance mutations, partial discordance was observed at 15 positions and complete discordance was absent. The reproducibility and precision study showed high nucleotide sequence identities i.e. 99.88±0.10 and 99.82±0.20 respectively. The in-house method showed 100% analytical sensitivity on the samples with HIV-1 viral load >1000 RNA copies/ml. The cost of running the in-house method is only 50% of that for ViroSeq method (112$ vs 300$), thus making it cost effective. Conclusions The validated cost effective in-house method may be used to collect surveillance data on the emergence and transmission of HIV-1 drug resistance in resource limited countries. Moreover, the wide applications of a cost effective and validated in-house method for HIV-1 drug resistance testing will facilitate the decision making for the appropriate management of HIV infected patients. PMID:24533056

  10. Apparatus for measuring resistance change only in a cell analyzer and method for calibrating it

    DOEpatents

    Hoffman, Robert A.

    1980-01-01

    The disclosure relates to resistance only monitoring and calibration in an electrical cell analyzer. Sample and sheath fluid flows of different salinities are utilized, the sample flow being diameter modulated to produce a selected pattern which is compared to the resistance measured across the flows.

  11. Monolithic amplifier with stable, high resistance feedback element and method for fabricating the same

    DOEpatents

    O`Connor, P.

    1998-08-11

    A monolithic amplifier includes a stable, high resistance feedback circuit and a dynamic bias circuit. The dynamic bias circuit is formed with active elements matched to those in the amplifier and feedback circuit to compensate for variations in the operating and threshold voltages thereby maintaining a stable resistance in the feedback circuit. 11 figs.

  12. Monolithic amplifier with stable, high resistance feedback element and method for fabricating the same

    DOEpatents

    O'Connor, Paul

    1998-08-11

    A monolithic amplifier includes a stable, high resistance feedback circuit and a dynamic bias circuit. The dynamic bias circuit is formed with active elements matched to those in the amplifier and feedback circuit to compensate for variations in the operating and threshold voltages thereby maintaining a stable resistance in the feedback circuit.

  13. Slipping on pedestrian surfaces: methods for measuring and evaluating the slip resistance.

    PubMed

    Wetzel, Christoph; Windhövel, Ulrich; Mewes, Detlef; Ceylan, Orhan

    2015-01-01

    Tripping, slipping and falling accidents are among the types of accident with a high incidence. This article describes the requirements concerning slip resistance, as well as the state of the art of slip resistance measurement standards in the European Community and the USA. The article also describes how risk assessment can be performed in the field. PMID:26414511

  14. Resistive heater geometry and regeneration method for a diesel particulate filter

    DOEpatents

    Phelps, Amanda; Kirby, Kevin W.; Gregoir, Daniel J.

    2011-10-25

    One embodiment of the invention includes a diesel particulate filter comprising a first face and a second face; a bottom electrode layer formed over the first face of the diesel particulate filter; a middle resistive layer formed over a portion of the bottom electrode layer; and a top electrode layer formed over a portion of the middle resistive layer.

  15. Omega-3 fatty acids attenuate constitutive and insulin-induced CD36 expression through a suppression of PPAR α/γ activity in microvascular endothelial cells.

    PubMed

    Madonna, Rosalinda; Salerni, Sara; Schiavone, Deborah; Glatz, Jan F; Geng, Yong-Jian; De Caterina, Raffaele

    2011-09-01

    Microvascular dysfunction occurs in insulin resistance and/or hyperinsulinaemia. Enhanced uptake of free fatty acids (FFA) and oxidised low-density lipoproteins (oxLDL) may lead to oxidative stress and microvascular dysfunction interacting with CD36, a PPARα/γ-regulated scavenger receptor and long-chain FFA transporter. We investigated CD36 expression and CD36-mediated oxLDL uptake before and after insulin treatment in human dermal microvascular endothelial cells (HMVECs), ± different types of fatty acids (FA), including palmitic, oleic, linoleic, arachidonic, eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids. Insulin (10(-8) and 10(-7) M) time-dependently increased DiI-oxLDL uptake and CD36 surface expression (by 30 ± 13%, p<0.05 vs. untreated control after 24 hours incubation), as assessed by ELISA and flow cytometry, an effect that was potentiated by the PI3-kinase inhibitor wortmannin and reverted by the ERK1/2 inhibitor PD98059 and the PPARα/γ antagonist GW9662. A ≥ 24 hour exposure to 50 μM DHA or EPA, but not other FA, blunted both the constitutive (by 23 ± 3% and 29 ± 2%, respectively, p<0.05 for both) and insulin-induced CD36 expressions (by 45 ± 27 % and 12 ± 3 %, respectively, p<0.05 for both), along with insulin-induced uptake of DiI-oxLDL and the downregulation of phosphorylated endothelial nitric oxide synthase (P-eNOS). At gel shift assays, DHA reverted insulin-induced basal and oxLDL-stimulated transactivation of PPRE and DNA binding of PPARα/γ and NF-κB. In conclusion, omega-3 fatty acids blunt the increased CD36 expression and activity promoted by high concentrations of insulin. Such mechanisms may be the basis for the use of omega-3 fatty acids in diabetic microvasculopathy. PMID:21727988

  16. A low cost construction method for Graphene based resistive chemical sensors

    NASA Astrophysics Data System (ADS)

    Kona, Silpa; Harnett, Cindy K.

    2012-02-01

    Graphene is a 2D material with distinctive properties and a large surface area that can be exposed to surface adsorbates from a target gas, making it attractive as a sensing material. This enables studies on the interaction of gas molecules with the graphene surface and subsequent changes in its properties. Due to its high electron mobility at room temperature, graphene exhibits high sensitivity, making it a good candidate for environmental and industrial sensing applications. Several models of graphene based sensors have been put forth previously based on high-resolution lithographic techniques and for individual electrode attachment to the sensing film with e-beam lithography. These techniques can produce small numbers of devices that explore the limits of molecular scale sensing, but the methods are currently impractical for large scale production of low cost sensors. We present our graphene based sensor with the focus on designing small, cost effective and reliable sensors with high sensitivity towards the target gas, detailing the assembly of graphene/acrylic devices, their characterization and investigation of their performance as resistive chemical sensors using differential voltage measurements.

  17. Detection of Old Mine Tunnels in Mexico City Highlands by Electric Resistivity Image Methods

    NASA Astrophysics Data System (ADS)

    Chavez, R. E.; Tejero, A.; Cifuentes-Nava, G.; HernaNdez-Quintero, J.

    2013-12-01

    Electrical Resistivity Tomography (ERT) methods have been applied to study cavities or subsurface subsidence threatening urbanized areas. Unfortunately, ERT-3D techniques carried out on heavily urbanized areas become a difficult task, since parallel ERT arrays cannot be deployed. Then, a conventional regular grid cannot be carried out. We present a subsidence problem located in a densely populated portion of Mexico City highlands. Since the damaged houses are in the middle of a highly populated low-class neighborhood, an unconventional ERT array had to be applied. At first, a ';T'-array formed by two perpendicular transects was applied, deployed within a small alley, that stretched from the house entrance. This study determined a tubular structure beneath the houses following an irregular path at depth. Finally, houses were demolished due to the extensive damaged in their foundations. This made possible to carry out a second ERT-3D study, which included a dipolar array called ';L' and ';Corner' arrays. Such a new work defined a similar tubular structure. The cavity entrance was discovered, when excavations were made, although its precise shape could not be defined. The ERT-3D interpretation contributed to locate and accurately determine the geometrical characteristics of the geological feature that caused the collapse of dwellings.

  18. Humidity-resistant ambient-temperature solid-electrolyte amperometric sensing apparatus and methods

    DOEpatents

    Zaromb, Solomon

    2001-01-01

    Apparatus and methods for detecting selected chemical compounds in air or other gas streams at room or ambient temperature includes a liquid-free humidity-resistant amperometric sensor comprising a sensing electrode and a counter and reference electrode separated by a solid electrolyte. The sensing electrode preferably contains a noble metal, such as Pt black. The electrolyte is water-free, non-hygroscopic, and substantially water-insoluble, and has a room temperature ionic conductivity .gtoreq.10.sup.-4 (ohm-cm).sup.-1, and preferably .gtoreq.0.01 (ohm-cm).sup.-1. The conductivity may be due predominantly to Ag+ ions, as in Ag.sub.2 WO.sub.4.4AgI, or to F- ions, as in Ce.sub.0.95 Ca.sub.0.05 F.sub.2.95. Electrical contacts serve to connect the electrodes to potentiostating and detecting circuitry which controls the potential of the sensing electrode relative to the reference electrode, detects the signal generated by the sensor, and indicates the detected signal.

  19. Microvascular coronary dysfunction and ischemic heart disease: where are we in 2014?

    PubMed

    Petersen, John W; Pepine, Carl J

    2015-02-01

    Many patients with angina and signs of myocardial ischemia on stress testing have no significant obstructive epicardial coronary disease. There are many potential coronary and non-coronary mechanisms for ischemia without obstructive epicardial coronary disease, and prominent among these is coronary microvascular and/or endothelial dysfunction. Patients with coronary microvascular and/or endothelial dysfunction are often at increased risk of adverse cardiovascular events, including ischemic events and heart failure despite preserved ventricular systolic function. In this article, we will review the diagnosis and treatment of coronary microvascular and endothelial dysfunction, discuss their potential contribution to heart failure with preserved ejection fraction, and highlight recent advances in the evaluation of atherosclerotic morphology in these patients, many of whom have non-obstructive epicardial disease.

  20. Monitoring the healing process of laser-induced microvascular lesions using optical-resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Hu, Song; Maslov, Konstantin I.; Wang, Lihong V.

    2009-02-01

    Optical resolution photoacoustic microscopy (OR-PAM) possesses optical resolution and reveals endogenous optical absorption contrast, promising to be a valuable tool for in vivo microvascular imaging. In laser dermatology, OR-PAM can provide fruitful structural and functional information about the targeted microvascular lesions, such as their threedimensional (3D) morphology, precise location inside the tissue, and blood oxygenation within single vessels, which will facilitate accurate diagnosis and proper treatment. More importantly, the advantages of noninvasiveness and measurement consistency also permit OR-PAM to monitor the healing process of the laser-surgical wound noninvasively. In this work, we employed OR-PAM to monitor the healing process of microvascular lesions induced by nanosecond-pulsed laser. Our results indicate that OR-PAM could be a very useful tool in laser dermatology and laser microsurgery.

  1. The prevention of diabetic microvascular complications of diabetes: is there a role for lipid lowering?

    PubMed

    Leiter, Lawrence A

    2005-06-01

    The role of hyperglycemia in the development of microvascular complications of diabetes, such as nephropathy, retinopathy and neuropathy, has been well documented. Evidence is accumulating to support the concept that dyslipidemia can also contribute to the development of these complications. Lipid-lowering agents, such as statins, have been shown to prevent cardiovascular events in patients with diabetes. However, in addition to preventing macrovascular diseases, statins may also be able to retard the progression of microvascular complications of diabetes. Indeed, in addition to reducing lipid levels, these agents can improve endothelial function and reduce oxidative stress, which can improve microvascular function. These findings would provide further support for the use of lipid-lowering agents in patients with diabetes.

  2. Microvascular Branching as a Determinant of Blood Flow by Intravital Particle Imaging Velocimetry

    NASA Technical Reports Server (NTRS)

    Parsons-Wingerter, Patricia; McKay, Terri L.; Vickerman, Mary B.; Wernet, Mark P.; Myers, Jerry G.; Radhakrishnan, Krishnan

    2007-01-01

    The effects of microvascular branching on blood flow were investigated in vivo by microscopic particle imaging velocimetry (micro-PIV). We use micro-PIV to measure blood flow by tracking red blood cells (RBC) as the moving particles. Velocity flow fields, including flow pulsatility, were analyzed for the first four branching orders of capillaries, postcapillary venules and small veins of the microvascular network within the developing avian yolksac at embryonic day 5 (E5). Increasing volumetric flowrates were obtained from parabolic laminar flow profiles as a function of increasing vessel diameter and branching order. Maximum flow velocities increased approximately twenty-fold as the function of increasing vessel diameter and branching order compared to flow velocities of 100 - 150 micron/sec in the capillaries. Results from our study will be useful for the increased understanding of blood flow within anastomotic, heterogeneous microvascular networks.

  3. Applications of computational models to better understand microvascular remodelling: a focus on biomechanical integration across scales

    PubMed Central

    Murfee, Walter L.; Sweat, Richard S.; Tsubota, Ken-ichi; Gabhann, Feilim Mac; Khismatullin, Damir; Peirce, Shayn M.

    2015-01-01

    Microvascular network remodelling is a common denominator for multiple pathologies and involves both angiogenesis, defined as the sprouting of new capillaries, and network patterning associated with the organization and connectivity of existing vessels. Much of what we know about microvascular remodelling at the network, cellular and molecular scales has been derived from reductionist biological experiments, yet what happens when the experiments provide incomplete (or only qualitative) information? This review will emphasize the value of applying computational approaches to advance our understanding of the underlying mechanisms and effects of microvascular remodelling. Examples of individual computational models applied to each of the scales will highlight the potential of answering specific questions that cannot be answered using typical biological experimentation alone. Looking into the future, we will also identify the needs and challenges associated with integrating computational models across scales. PMID:25844149

  4. PILOT-SCALE FIELD VALIDATION OF THE LONG ELECTRODE ELECTRICAL RESISTIVITY TOMOGRAPHY METHOD

    SciTech Connect

    GLASER DR; RUCKER DF; CROOK N; LOKE MH

    2011-07-14

    Field validation for the long electrode electrical resistivity tomography (LE-ERT) method was attempted in order to demonstrate the performance of the technique in imaging a simple buried target. The experiment was an approximately 1/17 scale mock-up of a region encompassing a buried nuclear waste tank on the Hanford site. The target of focus was constructed by manually forming a simulated plume within the vadose zone using a tank waste simulant. The LE-ERT results were compared to ERT using conventional point electrodes on the surface and buried within the survey domain. Using a pole-pole array, both point and long electrode imaging techniques identified the lateral extents of the pre-formed plume with reasonable fidelity, but the LE-ERT was handicapped in reconstructing the vertical boundaries. The pole-dipole and dipole-dipole arrays were also tested with the LE-ERT method and were shown to have the least favorable target properties, including the position of the reconstructed plume relative to the known plume and the intensity of false positive targets. The poor performance of the pole-dipole and dipole-dipole arrays was attributed to an inexhaustive and non-optimal coverage of data at key electrodes, as well as an increased noise for electrode combinations with high geometric factors. However, when comparing the model resolution matrix among the different acquisition strategies, the pole-dipole and dipole-dipole arrays using long electrodes were shown to have significantly higher average and maximum values than any pole-pole array. The model resolution describes how well the inversion model resolves the subsurface. Given the model resolution performance of the pole-dipole and dipole-dipole arrays, it may be worth investing in tools to understand the optimum subset of randomly distributed electrode pairs to produce maximum performance from the inversion model.

  5. Effect of high altitude and exercise on microvascular parameters in acclimatized subjects.

    PubMed

    Bauer, Andreas; Demetz, Florian; Bruegger, Dirk; Schmoelz, Martin; Schroepfer, Sebastian; Martignoni, André; Baschnegger, Heiko; Hoelzl, Josef; Thiel, Manfred; Choukér, Alexander; Peter, Klaus; Gamble, John; Christ, Frank

    2006-02-01

    The role of microvascular fluid shifts in the adaptation to hypobaric hypoxia and its contribution to the pathophysiology of AMS (acute mountain sickness) is unresolved. In a systematic prospective study, we investigated the effects of hypobaric hypoxia and physical exercise alone, and in combination, on microvascular fluid exchange and related factors. We used computer-assisted VCP (venous congestion plethysmography) on the calves of ten altitude-acclimatized volunteers. We investigated the effects of: (i) actively climbing to an altitude of 3196 m, (ii) airlifting these subjects to the same altitude, and (iii) exercise at low altitude. CFC (capillary filtration capacity), Pvi (isovolumetric venous pressure) and Qa (calf blood flow) were assessed before and after each procedure and then repeated after an overnight rest. Measurements of CFC showed no evidence of increased microvascular permeability after any of the procedures. Pvi was significantly decreased (P<0.001) from 20.3+/-4.4 to 8.9+/-4.3 mmHg after active ascent, and was still significantly lower (P=0.009) after overnight rest at high altitude (13.6+/-5.9 mmHg). No such changes were observed after the passive ascent (16.7+/-4.0 mmHg at baseline; 17.3+/-4.5 mmHg after passive ascent; and 19.9+/-5.3 mmHg after overnight rest) or after exercise at low altitude. After the active ascent, Qa was significantly increased. We also found a significant correlation between Qa, Pvi and the number of circulating white blood cells. In conclusion, we found evidence to support the hypothesis that increased microvascular permeability associated with AMS does not occur in acclimatized subjects. We also observed that the microvascular equilibrium pressure (Pvi) fell in inverse relation to the increase in Qa, especially in hypoxic exercise. We hypothesize that this inverse relationship reflects the haemodynamic changes at the microvascular interface, possibly attributable to the flow-induced increases in endothelial surface

  6. A better resolution for integrating methods for monitoring Plasmodium falciparum resistance to antimalarial drugs.

    PubMed

    Abdul-Ghani, Rashad; Al-Maktari, Mohamed T; Al-Shibani, Latifa A; Allam, Amal F

    2014-09-01

    Effective chemotherapy is the mainstay of malaria control. However, resistance of falciparum malaria to antimalarial drugs compromised the efforts to eliminate the disease and led to the resurgence of malaria epidemics. Three main approaches are used to monitor antimalarial drug efficacy and drug resistance; namely, in vivo trials, in vitro/ex vivo assays and molecular markers of drug resistance. Each approach has its implications of use as well as its advantages and drawbacks. Therefore, there is a need to use an integrated approach that would give the utmost effect to detect resistance as early as its emergence and to track it once spread. Such integration becomes increasingly needed in the era of artemisinin-based combination therapy as a forward action to deter resistance. The existence of regional and global networks for the standardization of methodology, provision of high quality reagents for the assessment of antimalarial drug resistance and dissemination of open-access data would help in approaching an integrated resistance surveillance system on a global scale.

  7. Understanding the Mechanism of Atovaquone Drug Resistance in Plasmodium falciparum Cytochrome b Mutation Y268S Using Computational Methods

    PubMed Central

    Varshney, Megha; Gupta, Shishir K.; Shukla, Yogeshwar; Gupta, Shailendra K.

    2014-01-01

    The rapid appearance of resistant malarial parasites after introduction of atovaquone (ATQ) drug has prompted the search for new drugs as even single point mutations in the active site of Cytochrome b protein can rapidly render ATQ ineffective. The presence of Y268 mutations in the Cytochrome b (Cyt b) protein is previously suggested to be responsible for the ATQ resistance in Plasmodium falciparum (P. falciparum). In this study, we examined the resistance mechanism against ATQ in P. falciparum through computational methods. Here, we reported a reliable protein model of Cyt bc1 complex containing Cyt b and the Iron-Sulphur Protein (ISP) of P. falciparum using composite modeling method by combining threading, ab initio modeling and atomic-level structure refinement approaches. The molecular dynamics simulations suggest that Y268S mutation causes ATQ resistance by reducing hydrophobic interactions between Cyt bc1 protein complex and ATQ. Moreover, the important histidine contact of ATQ with the ISP chain is also lost due to Y268S mutation. We noticed the induced mutation alters the arrangement of active site residues in a fashion that enforces ATQ to find its new stable binding site far away from the wild-type binding pocket. The MM-PBSA calculations also shows that the binding affinity of ATQ with Cyt bc1 complex is enough to hold it at this new site that ultimately leads to the ATQ resistance. PMID:25334024

  8. Test method for the determination of crack-growth rates and crack growth resistance under cyclic loading

    SciTech Connect

    Yarema, S.Ya.

    1995-05-01

    This article describes the test method for the determination of crack growth rates and crack growth resistance under cyclic loading conditions. The text of the article is limited to two appendices with the following subjects: (1) general requirements for specimens for testing with a constant cycle of the stress intensity factor, and (2) descriptions of the loading fixtures.

  9. A Nondestructive Evaluation Method: Measuring the Fixed Strength of Spot-Welded Joint Points by Surface Electrical Resistivity.

    PubMed

    Shimamoto, Akira; Yamashita, Keitaro; Inoue, Hirofumi; Yang, Sung-Mo; Iwata, Masahiro; Ike, Natsuko

    2013-04-01

    Destructive tests are generally applied to evaluate the fixed strength of spot-welding nuggets of zinc-plated steel (which is a widely used primary structural material for automobiles). These destructive tests, however, are expensive and time-consuming. This paper proposes a nondestructive method for evaluating the fixed strength of the welded joints using surface electrical resistance. A direct current nugget-tester and probes have been developed by the authors for this purpose. The proposed nondestructive method uses the relative decrease in surface electrical resistance, α. The proposed method also considers the effect of the corona bond. The nugget diameter is estimated by two factors: R Quota, which is calculated from variation of resistance, and a constant that represents the area of the corona bond. Since the maximum tensile strength is correlated with the nugget diameter, it can be inferred from the estimated nugget diameter. When appropriate measuring conditions for the surface electrical resistance are chosen, the proposed method can effectively evaluate the fixed strength of the spot-welded joints even if the steel sheet is zinc-plated.

  10. Development of practical diagnostic methods for monitoring rice bacterial panicle blight disease and evaluation of rice germplasm for resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was initiated to understand Burkholderia glumae, the major causal agent for bacterial panicle blight disease of rice; to develop practical diagnostic methods for monitoring the disease; and to evaluate rice germplasm for resistance. Burkholderia glumae was frequently isolated from infected p...

  11. Development of practical diagnostic methods for monitoring rice bacterial panicle blight disease and evaluation of rice germplasm for resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was initiated to understand Burkholderia glumae (major causal agent for bacterial panicle blight disease of rice) to develop practical diagnostic methods for monitori