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Sample records for myocardial blood oxygen

  1. Myocardial Ischemia: Lack of Coronary Blood Flow or Myocardial Oxygen Supply/Demand Imbalance?

    PubMed

    Heusch, Gerd

    2016-07-01

    Regional myocardial blood flow and contractile function in ischemic myocardium are well matched, and there is no evidence for an oxygen supply/demand imbalance. Thus, myocardial ischemia is lack of coronary blood flow with electric, functional, metabolic, and structural consequences for the myocardium. All therapeutic interventions must aim to improve blood flow to ischemic myocardium as much and as quickly as possible. PMID:27390331

  2. Phenylephrine does not limit myocardial blood flow or oxygen delivery during isoflurane-induced hypotension in dogs.

    PubMed

    Abdel-Latif, M; Kim, S J; Salem, M R; Crystal, G J

    1992-06-01

    Experiments were performed on seven fentanyl-pentobarbital-anesthetized, open-chest dogs to determine whether stimulation of coronary alpha 1-adrenergic receptors by phenylephrine causes coronary vasoconstriction and impaired myocardial oxygen delivery when phenylephrine is infused to correct isoflurane-induced hypotension. Myocardial blood flow was measured with radioactive microspheres, and myocardial oxygen and lactate extraction were determined. The Fick equation was used to calculate myocardial oxygen consumption. Measurements were obtained (a) under control conditions, (b) after a 30-min inhalation of isoflurane sufficient to decrease mean aortic pressure by 30%, and (c) while maintaining administration of isoflurane, 5-10 min after restoration of mean aortic pressure by intravenous infusion of phenylephrine. Isoflurane-induced hypotension was accompanied by a baroreceptor-mediated increase in heart rate and by a decrease in myocardial oxygen consumption; however, myocardial blood flow was maintained, resulting in decreased oxygen extraction and increased coronary sinus PO2, thus implying a direct coronary vasodilating effect for isoflurane. Lactate extraction was unaffected. Phenylephrine infusion during inhalation of isoflurane returned mean aortic pressure and heart rate to their respective control values, and it did not change myocardial oxygen consumption, myocardial blood flow, myocardial oxygen extraction, coronary sinus PO2, or lactate extraction from values obtained during isoflurane alone. These latter findings are consistent with undiminished coronary vasodilation by isoflurane in the presence of phenylephrine. In conclusion, infused phenylephrine to restore aortic pressure during isoflurane administration had no vasoconstrictor effect in the coronary circulation and did not impair myocardial oxygen delivery. Apparently, the direct coronary vasodilating action of isoflurane completely nullified phenylephrine-induced vasoconstriction via local alpha

  3. Myocardial blood flow and its transit time, oxygen utilization, and efficiency of highly endurance-trained human heart.

    PubMed

    Heinonen, Ilkka; Kudomi, Nobuyuki; Kemppainen, Jukka; Kiviniemi, Antti; Noponen, Tommi; Luotolahti, Matti; Luoto, Pauliina; Oikonen, Vesa; Sipilä, Hannu T; Kopra, Jaakko; Mononen, Ilkka; Duncker, Dirk J; Knuuti, Juhani; Kalliokoski, Kari K

    2014-07-01

    Highly endurance-trained athlete's heart represents the most extreme form of cardiac adaptation to physical stress, but its circulatory alterations remain obscure. In the present study, myocardial blood flow (MBF), blood mean transit time (MTT), oxygen extraction fraction (OEF) and consumption (MVO2), and efficiency of cardiac work were quantified in highly trained male endurance athletes and control subjects at rest and during supine cycling exercise using [(15)O]-labeled radiotracers and positron emission tomography. Heart rate and MBF were lower in athletes both at rest and during exercise. OEF increased in response to exercise in both groups, but was higher in athletes (70 ± 21 vs. 63 ± 11 % at rest and 86 ± 13 vs. 73 ± 10 % during exercise). MTT was longer and vascular resistance higher in athletes both at rest and during exercise, but arterial content of 2,3-diphosphoglycerate (oxygen affinity) was unchanged. MVO2 per gram of myocardium trended (p = 0.08) lower in athletes both at rest and during exercise, while myocardial efficiency of work and MVO2 per beat were not different between groups. Arterial levels of free fatty acids were ~twofold higher in athletes likely leading to higher myocardial fatty acid oxidation and hence oxygen cost, which may have blunted the bradycardia-induced decrease in MVO2. Finally, the observed group differences in MBF, OEF, MTT and vascular resistance remained significant also after they were controlled for differences in MVO2. In conclusion, in highly endurance-trained human heart, increased myocardial blood transition time enables higher oxygen extraction levels with a lower myocardial blood flow and higher vascular resistance. These physiological adaptations to exercise training occur independently of the level of oxygen consumption and together with training-induced bradycardia may serve as mechanisms to increase functional reserve of the human heart. PMID:24866583

  4. Synthetic Generation of Myocardial Blood-Oxygen-Level-Dependent MRI Time Series via Structural Sparse Decomposition Modeling

    PubMed Central

    Rusu, Cristian; Morisi, Rita; Boschetto, Davide; Dharmakumar, Rohan; Tsaftaris, Sotirios A.

    2014-01-01

    This paper aims to identify approaches that generate appropriate synthetic data (computer generated) for Cardiac Phase-resolved Blood-Oxygen-Level-Dependent (CP–BOLD) MRI. CP–BOLD MRI is a new contrast agent- and stress-free approach for examining changes in myocardial oxygenation in response to coronary artery disease. However, since signal intensity changes are subtle, rapid visualization is not possible with the naked eye. Quantifying and visualizing the extent of disease relies on myocardial segmentation and registration to isolate the myocardium and establish temporal correspondences and ischemia detection algorithms to identify temporal differences in BOLD signal intensity patterns. If transmurality of the defect is of interest pixel-level analysis is necessary and thus a higher precision in registration is required. Such precision is currently not available affecting the design and performance of the ischemia detection algorithms. In this work, to enable algorithmic developments of ischemia detection irrespective to registration accuracy, we propose an approach that generates synthetic pixel-level myocardial time series. We do this by (a) modeling the temporal changes in BOLD signal intensity based on sparse multi-component dictionary learning, whereby segmentally derived myocardial time series are extracted from canine experimental data to learn the model; and (b) demonstrating the resemblance between real and synthetic time series for validation purposes. We envision that the proposed approach has the capacity to accelerate development of tools for ischemia detection while markedly reducing experimental costs so that cardiac BOLD MRI can be rapidly translated into the clinical arena for the noninvasive assessment of ischemic heart disease. PMID:24691119

  5. The effects of graded changes in oxygen and carbon dioxide tension on coronary blood velocity independent of myocardial energy demand.

    PubMed

    Boulet, Lindsey M; Stembridge, Mike; Tymko, Michael M; Tremblay, Joshua C; Foster, Glen E

    2016-08-01

    In humans, coronary blood flow is tightly regulated by microvessels within the myocardium to match myocardial energy demand. However, evidence regarding inherent sensitivity of the microvessels to changes in arterial partial pressure of carbon dioxide and oxygen is conflicting because of the accompanied changes in myocardial energy requirements. This study aimed to investigate the changes in coronary blood velocity while manipulating partial pressures of end-tidal CO2 (Petco2) and O2 (Peto2). It was hypothesized that an increase in Petco2 (hypercapnia) or decrease in Peto2 (hypoxia) would result in a significant increase in mean blood velocity in the left anterior descending artery (LADVmean) due to an increase in both blood gases and energy demand associated with the concomitant cardiovascular response. Cardiac energy demand was assessed through noninvasive measurement of the total left ventricular mechanical energy. Healthy subjects (n = 13) underwent a euoxic CO2 test (Petco2 = -8, -4, 0, +4, and +8 mmHg from baseline) and an isocapnic hypoxia test (Peto2 = 64, 52, and 45 mmHg). LADVmean was assessed using transthoracic Doppler echocardiography. Hypercapnia evoked a 34.6 ± 8.5% (mean ± SE; P < 0.01) increase in mean LADVmean, whereas hypoxia increased LADVmean by 51.4 ± 8.8% (P < 0.05). Multiple stepwise regressions revealed that both mechanical energy and changes in arterial blood gases are important contributors to the observed changes in LADVmean (P < 0.01). In summary, regulation of the coronary vasculature in humans is mediated by metabolic changes within the heart and an inherent sensitivity to arterial blood gases. PMID:27233761

  6. The Relationships between Arterial Oxygen Flow Rate, Oxygen Binding by Hemoglobin, and Oxygen Utilization after Myocardial Infarction

    PubMed Central

    Lichtman, Marshall A.; Cohen, Jules; Young, Jerald A.; Whitbeck, April A.; Murphy, Marion

    1974-01-01

    The interrelationships of arterial oxygen flow rate index, oxygen binding by hemoglobin, and oxygen consumption have been examined in patients with acute myocardial infarction. Proportional extraction of oxygen increased in close association with decreasing oxygen flow rate, and hence, whole body oxygen consumption was constant over nearly a three-fold variation in arterial oxygen flow rate. A reduction in hemoglobin-oxygen affinity at in vivo conditions of pH. Pco2 and temperature also occurred in proportion to the reduction in arterial oxygen flow rate. Therefore, the increased proportional removal of oxygen from arterial blood at low oxygen flow rates, required to maintain oxygen consumption, may have been facilitated by the reduced affinity of hemoglobin for oxygen at in vivo conditions. However, the decrease in affinity did not appear to explain more than 30-40% of the increased extraction. Respiratory alkalosis was a frequent occurrence in these patients and 2,3-diphosphoglycerate was positively associated with blood pH as well as with the time-averaged proportion of deoxyhemoglobin in arterial and venous blood. Hemoglobin-oxygen affinity measured at standard conditions and the mixed venous oxygen saturation were equally good indicators of reduced arterial oxygen flow rate in patients without shock. However, S̄vo2 is more easily measured and is a more useful indicator of reduced oxygen flow rate, since its relationship to oxygen flow appears to be independent of affinity changes and time. PMID:4855047

  7. The effects of hypoxemia on myocardial blood flow during exercise.

    PubMed

    Paridon, S M; Bricker, J T; Dreyer, W J; Reardon, M; Smith, E O; Porter, C B; Michael, L; Fisher, D J

    1989-03-01

    We evaluated the adequacy of regional and transmural blood flow during exercise and rapid pacing after 1 wk of hypoxemia. Seven mature mongrel dogs were made hypoxemic (mean O2 saturation = 72.4%) by anastomosis of left pulmonary artery to left atrial appendage. Catheters were placed in the left atrium, right atrium, pulmonary artery, and aorta. Atrial and ventricular pacing wires were placed. An aortic flow probe was placed to measure cardiac output. Ten nonshunted dogs, similarly instrumented, served as controls. Recovery time was approximately 1 wk. Cardiac output, mean aortic pressure, and oxygen saturation were measured at rest, with ventricular pacing, atrial pacing, and with treadmill exercise. Ventricular and atrial pace and exercise were at a heart rate of 200. Right ventricular free wall, left ventricular free wall, and septal blood flow were measured with radionuclide-labeled microspheres. Cardiac output, left atrial blood pressure, and aortic blood pressure were similar between the two groups of dogs in all testing states. Myocardial blood flow was significantly higher in the right and left ventricular free wall in the hypoxemic animals during resting and exercise testing states. Myocardial oxygen delivery was similar between the two groups of animals. Pacing resulted in an increase in myocardial blood flow in the control animals but not the hypoxemic animals.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2704596

  8. Simultaneous Noninvasive Determination of Regional Myocardial Perfusion and Oxygen Content in Rabbits: Toward Direct Measurement of Myocardial Oxygen Consumption at MR Imaging1

    PubMed Central

    Reeder, Scott B.; Holmes, A. Alexander; McVeigh, Elliot R.; Forder, John R.

    2007-01-01

    PURPOSE To determine whether myocardial arterial perfusion and oxygen concentration can be quantified simultaneously from the same images by using spin labeling and the blood oxygenation level-dependent (BOLD) effect with fast spin-echo (SE) imaging. MATERIALS AND METHODS A T2-weighted fast SE pulse sequence was written to image isolated, arrested, blood-perfused rabbit hearts (n = 6) at 4.7 T. Perfusion images with intensity in units of milliliters per minute per gram that covered the entire left ventricle with 0.39 × 0.39 × 3.00-mm resolution were obtained in less than 15 minutes with a 32-fold reduction in imaging time from that of a previous study. Estimates of oxygen concentration were made from the same images acquired for calculation of perfusion images. RESULTS Estimates of regional myocardial oxygen content could be made from the perfusion images; this demonstrated the feasibility of three-dimensional calculation of regional oxygen consumption, which requires concomitant measurement of both oxygen content and flow. Fast SE imaging was shown to bas sensitive to hemoglobin desaturation as standard SE imaging. Perfusion abnormalities and oxygen deficits were easily identified and verified qualitatively with gadopentetate dimeglumine on both perfusion and BOLD images obtained after coronary arterial ligation. CONCLUSION T2-weighted fast SE imaging combined with perfusion-sensitive spin labeling can be used to measure myocardial arterial perfusion and oxygen concentration. This provides the groundwork for calculation of regional myocardial oxygen consumption. PMID:10478241

  9. Abnormal Myocardial Blood Flow Reserve Observed in Cardiac Amyloidosis

    PubMed Central

    Nel, Karen; Senior, Roxy; Greaves, Kim

    2016-01-01

    We performed real-time myocardial contrast echocardiography on a patient with cardiac amyloidosis and previous normal coronary angiography presenting with atypical chest pain to assess myocardial blood flow reserve (MBFR). Myocardial contrast echocardiography was performed and flash microbubble destruction and replenishment analysis was used to calculate myocardial blood flow. Dipyridamole was used to achieve hyperemia. MBFR was derived from the ratio of peak myocardial blood flow at hyperemia and rest. The results show a marked reduction in MBFR in our patient. Previous reports of luminal obstruction of intramyocardial rather than epicardial vessels by amyloid deposition may be causing microvascular dysfunction. PMID:27081447

  10. Quantification of Regional Myocardial Oxygenation by Magnetic Resonance Imaging: Validation with Positron Emission Tomography

    PubMed Central

    McCommis, Kyle S.; Goldstein, Thomas A.; Abendschein, Dana R.; Herrero, Pilar; Misselwitz, Bernd; Gropler, Robert J.; Zheng, Jie

    2011-01-01

    Background A comprehensive evaluation of myocardial ischemia requires measures of both oxygen supply and demand. Positron emission tomography (PET) is currently the gold standard for such evaluations, but its use is limited due to its ionizing radiation, limited availability, and high cost. A cardiac magnetic resonance imaging (MRI) method was developed for assessing myocardial oxygenation. The purpose of this study was to evaluate and validate this technique compared to PET during pharmacologic stress in a canine model of coronary artery stenosis. Methods and Results Twenty-one beagles and small mongrel dogs without coronary artery stenosis (controls), or with moderate to severe acute coronary artery stenosis underwent MRI and PET imaging at rest and during dipyridamole vasodilation or dobutamine stress to induce a wide range of changes in cardiac perfusion and oxygenation. MRI first-pass perfusion imaging was performed to quantify myocardial blood flow (MBF) and volume (MBV). The MRI blood-oxygen-level-dependent (BOLD) technique was used to determine the myocardial oxygen extraction fraction (OEF) during pharmacologic hyperemia. Myocardial oxygen consumption (MVO2) was determined by Fick’s law. In the same dogs, 15O-water and 11C-acetate were used to measure MBF and MVO2, respectively, by PET. Regional assessments were performed for both MR and PET. MRI data correlated nicely with PET values for MBF (R2 = 0.79, P < 0.001), MVO2 (R2 = 0.74, P < 0.001), and OEF (R2 = 0.66, P < 0.01). Conclusions Cardiac MRI methods may provide an alternative to radionuclide imaging in settings of myocardial ischemia. Our newly developed quantitative MRI oxygenation imaging technique may be a valuable non-invasive tool to directly evaluate myocardial energetics and efficiency. PMID:19933371

  11. Caffeine reduces myocardial blood flow during exercise.

    PubMed

    Higgins, John P; Babu, Kavita M

    2013-08-01

    Caffeine consumption has been receiving increased interest from both the medical and lay press, especially given the increased amounts now available in energy products. Acute ingestion of caffeine usually increases cardiac work; however, caffeine impairs the expected proportional increase in myocardial blood flow to match this increased work of the heart, most notably during exercise. This appears to be mainly due to caffeine's effect on blocking adenosine-induced vasodilatation in the coronary arteries in normal healthy subjects. This review summarizes the available medical literature specifically relating to pure caffeine tablet ingestion and reduced exercise coronary blood flow, and suggests possible mechanisms. Further studies are needed to evaluate this effect for other common caffeine-delivery systems, including coffee, energy beverages, and energy gels, which are often used for exercise performance enhancement, especially in teenagers and young athletes. PMID:23764265

  12. Effects of human immunodeficiency virus and metabolic complications on myocardial nutrient metabolism, blood flow, and oxygen consumption: a cross-sectional analysis

    PubMed Central

    2011-01-01

    Background In the general population, peripheral metabolic complications (MC) increase the risk for left ventricular dysfunction. Human immunodeficiency virus infection (HIV) and combination anti-retroviral therapy (cART) are associated with MC, left ventricular dysfunction, and a higher incidence of cardiovascular events than the general population. We examined whether myocardial nutrient metabolism and left ventricular dysfunction are related to one another and worse in HIV infected men treated with cART vs. HIV-negative men with or without MC. Methods Prospective, cross-sectional study of myocardial glucose and fatty acid metabolism and left ventricular function in HIV+ and HIV-negative men with and without MC. Myocardial glucose utilization (GLUT), and fatty acid oxidation and utilization rates were quantified using 11C-glucose and 11C-palmitate and myocardial positron emission tomography (PET) imaging in four groups of men: 23 HIV+ men with MC+ (HIV+/MC+, 42 ± 6 yrs), 15 HIV+ men without MC (HIV+/MC-, 41 ± 6 yrs), 9 HIV-negative men with MC (HIV-/MC+, 33 ± 5 yrs), and 22 HIV-negative men without MC (HIV-/MC-, 25 ± 6 yrs). Left ventricular function parameters were quantified using echocardiography. Results Myocardial glucose utilization was similar among groups, however when normalized to fasting plasma insulin concentration (GLUT/INS) was lower (p < 0.01) in men with metabolic complications (HIV+: 9.2 ± 6.2 vs. HIV-: 10.4 ± 8.1 nmol/g/min/μU/mL) than men without metabolic complications (HIV+: 45.0 ± 33.3 vs. HIV-: 60.3 ± 53.0 nmol/g/min/μU/mL). Lower GLUT/INS was associated with lower myocardial relaxation velocity during early diastole (r = 0.39, p < 0.001). Conclusion Men with metabolic complications, irrespective of HIV infection, had lower basal myocardial glucose utilization rates per unit insulin that were related to left ventricular diastolic impairments, indicating that well-controlled HIV infection is not an independent risk factor for

  13. Concentrated Ambient Particles Alter Myocardial Blood Flow during Acute Ischemia in Conscious Canines

    PubMed Central

    Bartoli, Carlo R.; Wellenius, Gregory A.; Coull, Brent A.; Akiyama, Ichiro; Diaz, Edgar A.; Lawrence, Joy; Okabe, Kazunori; Verrier, Richard L.; Godleski, John J.

    2009-01-01

    Background Experimental and observational studies have demonstrated that short-term exposure to ambient particulate matter (PM) exacerbates myocardial ischemia. Objectives We conducted this study to investigate the effects of concentrated ambient particles (CAPs) on myocardial blood flow during myocardial ischemia in chronically instrumented conscious canines. Methods Eleven canines were instrumented with a balloon occluder around the left anterior descending coronary artery and catheters for determination of myocardial blood flow using fluorescent microspheres. Telemetric electrocardiographic and blood pressure monitoring was available for four of these animals. After recovery, we exposed animals by inhalation to 5 hr of either filtered air or CAPs (mean concentration ± SD, 349.0 ± 282.6 μg/m3) in a crossover protocol. We determined myocardial blood flow during a 5-min coronary artery occlusion immediately after each exposure. Data were analyzed using mixed models for repeated measures. The primary analysis was based on four canines that completed the protocol. Results CAPs exposure decreased total myocardial blood flow during coronary artery occlusion by 0.12 mL/min/g (p < 0.001) and was accompanied by a 13% (p < 0.001) increase in coronary vascular resistance. Rate–pressure product, an index of myocardial oxygen demand, did not differ by exposure (p = 0.90). CAPs effects on myocardial blood flow were significantly more pronounced in myocardium within or near the ischemic zone versus more remote myocardium (p interaction < 0.001). Conclusions These results suggest that PM exacerbates myocardial ischemia by increased coronary vascular resistance and decreased myocardial perfusion. Further studies are needed to elucidate the mechanism of these effects. PMID:19337504

  14. Noninvasive estimation of regional myocardial oxygen consumption by positron emission tomography with carbon-11 acetate in patients with myocardial infarction

    SciTech Connect

    Walsh, M.N.; Geltman, E.M.; Brown, M.A.; Henes, C.G.; Weinheimer, C.J.; Sobel, B.E.; Bergmann, S.R. )

    1989-11-01

    We previously demonstrated in experimental studies that myocardial oxygen consumption (MVO2) can be estimated noninvasively with positron emission tomography (PET) from analysis of the myocardial turnover rate constant (k) after administration of carbon-11 (11C) acetate. To determine regional k in healthy human subjects and to estimate alterations in MVO2 accompanying myocardial ischemia, we administered (11C)acetate to five healthy human volunteers and to six patients with myocardial infarction. Extraction of (11C)acetate by the myocardium was avid and clearance from the blood-pool rapid yielding myocardial images of excellent quality. Regional k was homogeneous in myocardium of healthy volunteers (coefficient variation = 11%). In patients, k in regions remote from the area of infarction was not different from values in myocardium of healthy human volunteers (0.061 +/- 0.025 compared with 0.057 +/- 0.008 min-1). In contrast, MVO2 in the center of the infarct region was only 6% of that in remote regions (p less than 0.01). In four patients studied within 48 hr of infarction and again more than seven days after the acute event, regional k and MVO2 did not change. The approach developed should facilitate evaluation of the efficacy of interventions designed to enhance recovery of jeopardized myocardium and permit estimation of regional MVO2 and metabolic reserve underlying cardiac disease of diverse etiologies.

  15. No Evidence of Myocardial Oxygen Deprivation in Nonischemic Heart Failure

    PubMed Central

    Dass, Sairia; Holloway, Cameron J.; Cochlin, Lowri E.; Rider, Oliver J.; Mahmod, Masliza; Robson, Matthew; Sever, Emily; Clarke, Kieran; Watkins, Hugh; Ashrafian, Houman; Karamitsos, Theodoros D.

    2015-01-01

    Background— Whether the myocardium in nonischemic heart failure experiences oxygen limitation remains a long-standing controversy. We addressed this question in patients with dilated cardiomyopathy (DCM) using a dual approach. First, we tested the changes in myocardial oxygenation between rest and stress states, using oxygenation-sensitive cardiovascular magnetic resonance. Second, we sought to assess the functional consequences of oxygen limitation at rest by measuring myocardial energetics before and after short-term oxygen supplementation. Methods and Results— Twenty-six subjects (14 DCM and 12 normal) underwent cardiac magnetic resonance imaging at 3 Tesla to assess cardiac volumes, function, oxygenation, and first-pass perfusion (0.03 mmol/kg Gd-DTPA bolus) at stress and rest (4–6 minutes IV adenosine, 140 μg/kg per minute). Signal intensity change (SIΔ) and myocardial perfusion reserve index (MPRI) were measured from oxygenation and perfusion images, respectively. Furthermore, the effect of oxygen supplementation on resting myocardial energy metabolism was tested using 31P MR spectroscopy, measuring PCr/ATP ratios in both groups at baseline and after 4 hours of oxygen via facemask in the DCM group. During stress, there were equivalent rises in rate pressure product in both groups (DCM, 76±15% and normal, 79±9%; P=0.84). MPRI was significantly reduced in DCM (1.51±0.11 versus normal 1.86±0.10; P=0.03). However, there was no difference in oxygenation between groups: SIΔ in DCM 17±3% versus normal 20±2% (P=0.38). Furthermore, at a left ventricular segmental level, there was no correlation between oxygenation-sensitive SIΔ and MPRI (R=0.06; P=0.43). Resting PCr/ATP was reduced in DCM (1.66±0.07 versus normal 2.12±0.06; P=0.002). With oxygen supplementation, there was no change in PCr/ATP (1.61±0.08; P=0.58; Δ=0.04±0.05). There was also no effect of oxygen on systolic function (ejection fraction pre oxygen, 34±1%; post oxygen, 36±2%; P=0

  16. SPECT Myocardial Blood Flow Quantitation Concludes Equivocal Myocardial Perfusion SPECT Studies to Increase Diagnostic Benefits.

    PubMed

    Chen, Lung-Ching; Lin, Chih-Yuan; Chen, Ing-Jou; Ku, Chi-Tai; Chen, Yen-Kung; Hsu, Bailing

    2016-01-01

    Recently, myocardial blood flow quantitation with dynamic SPECT/CT has been reported to enhance the detection of coronary artery disease in human. This advance has created important clinical applications to coronary artery disease diagnosis and management for areas where myocardial perfusion PET tracers are not available. We present 2 clinical cases that undergone a combined test of 1-day rest/dipyridamole-stress dynamic SPECT and ECG-gated myocardial perfusion SPECT scans using an integrated imaging protocol and demonstrate that flow parameters are capable to conclude equivocal myocardial perfusion SPECT studies, therefore increasing diagnostic benefits to add value in making clinical decisions. PMID:26053731

  17. Blood flow and oxygen uptake during exercise

    NASA Technical Reports Server (NTRS)

    Mitchell, J. W.; Stolwijk, J. A. J.; Nadel, E. R.

    1973-01-01

    A model is developed for predicting oxygen uptake, muscle blood flow, and blood chemistry changes under exercise conditions. In this model, the working muscle mass system is analyzed. The conservation of matter principle is applied to the oxygen in a unit mass of working muscle under transient exercise conditions. This principle is used to relate the inflow of oxygen carried with the blood to the outflow carried with blood, the rate of change of oxygen stored in the muscle myoglobin, and the uptake by the muscle. Standard blood chemistry relations are incorporated to evaluate venous levels of oxygen, pH, and carbon dioxide.

  18. Impaired Myocardial Oxygenation Response to Stress in Patients With Chronic Kidney Disease

    PubMed Central

    Parnham, Susie; Gleadle, Jonathan M; Bangalore, Sripal; Grover, Suchi; Perry, Rebecca; Woodman, Richard J; De Pasquale, Carmine G; Selvanayagam, Joseph B

    2015-01-01

    Background Coronary artery disease and left ventricular hypertrophy are prevalent in the chronic kidney disease (CKD) and renal transplant (RT) population. Advances in cardiovascular magnetic resonance (CMR) with blood oxygen level–dependent (BOLD) technique provides capability to assess myocardial oxygenation as a measure of ischemia. We hypothesized that the myocardial oxygenation response to stress would be impaired in CKD and RT patients. Methods and Results Fifty-three subjects (23 subjects with CKD, 10 RT recipients, 10 hypertensive (HT) controls, and 10 normal controls without known coronary artery disease) underwent CMR scanning. All groups had cine and BOLD CMR at 3 T. The RT and HT groups also had late gadolinium CMR to assess infarction/replacement fibrosis. The CKD group underwent 2-dimensional echocardiography strain to assess fibrosis. Myocardial oxygenation was measured at rest and under stress with adenosine (140 μg/kg per minute) using BOLD signal intensity. A total of 2898 myocardial segments (1200 segments in CKD patients, 552 segments in RT, 480 segments in HT, and 666 segments in normal controls) were compared using linear mixed modeling. Diabetes mellitus (P=0.47) and hypertension (P=0.57) were similar between CKD, RT, and HT groups. The mean BOLD signal intensity change was significantly lower in the CKD and RT groups compared to HT controls and normal controls (−0.89±10.63% in CKD versus 5.66±7.87% in RT versus 15.54±9.58% in HT controls versus 16.19±11.11% in normal controls, P<0.0001). BOLD signal intensity change was associated with estimated glomerular filtration rate (β=0.16, 95% CI=0.10 to 0.22, P<0.0001). Left ventricular mass index and left ventricular septal wall diameter were similar between the CKD predialysis, RT, and HT groups. None of the CKD patients had impaired global longitudinal strain and none of the RT group had late gadolinium hyperenhancement. Conclusions Myocardial oxygenation response to stress is

  19. Molecular Characterization of Reactive Oxygen Species in Myocardial Ischemia-Reperfusion Injury

    PubMed Central

    Zhou, Tingyang; Chuang, Chia-Chen; Zuo, Li

    2015-01-01

    Myocardial ischemia-reperfusion (I/R) injury is experienced by individuals suffering from cardiovascular diseases such as coronary heart diseases and subsequently undergoing reperfusion treatments in order to manage the conditions. The occlusion of blood flow to the tissue, termed ischemia, can be especially detrimental to the heart due to its high energy demand. Several cellular alterations have been observed upon the onset of ischemia. The danger created by cardiac ischemia is somewhat paradoxical in that a return of blood to the tissue can result in further damage. Reactive oxygen species (ROS) have been studied intensively to reveal their role in myocardial I/R injury. Under normal conditions, ROS function as a mediator in many cell signaling pathways. However, stressful environments significantly induce the generation of ROS which causes the level to exceed body's antioxidant defense system. Such altered redox homeostasis is implicated in myocardial I/R injury. Despite the detrimental effects from ROS, low levels of ROS have been shown to exert a protective effect in the ischemic preconditioning. In this review, we will summarize the detrimental role of ROS in myocardial I/R injury, the protective mechanism induced by ROS, and potential treatments for ROS-related myocardial injury. PMID:26509170

  20. Spin label oximetry to assess extracellular oxygen during myocardial ischemia.

    PubMed

    Baker, J E; Froncisz, W; Joseph, J; Kalyanaraman, B

    1997-01-01

    We describe real-time measurement of myocardial oxygen consumption during ischemia in the intact heart. Measurement of extracellular oxygen concentration during myocardial ischemia by spin label oximetry has been limited by ischemia-induced reduction of the neutral, water-soluble nitroxide TEMPONE. We have overcome this problem by encapsulating the nitroxides. Isolated immature (7-10 d old) rabbit hearts (n = 8) were perfused aerobically within the cavity of a loop gap resonator with bicarbonate buffer containing an oxygen-sensitive, lipid-soluble nitroxide (14N-TEMPO laurate in FC-43 perfluorocarbon micelles) and a much less oxygen-sensitive and positively charged nitroxide (15N-TEMPO choline in multilamellar vesicles) as an internal standard. The ratio of the ESR signal amplitudes of these nitroxides was used as a sensitive index of oxygen concentration. Sequestration of the nitroxides decreased their reduction rate by ascorbate in comparison with nonsequestered nitroxides. Hearts were subjected to 60 min of global no-flow ischemia at 20 degrees C. Extracellular oxygen content (mean +/- SD) during aerobic perfusion was 1195 +/- 55 mumol/liter. The electron spin resonance signal from TEMPO laurate increased with the onset and progression of ischemia, consistent with a decrease in extracellular oxygen, while the signal for TEMPO choline was relatively unchanged. Extracellular oxygen content after 40 and 60 min of ischemia was reduced to 393 +/- 27 mumol/liter (p < .05) and 61 +/- 5 mumol/liter (p < .05), respectively. We conclude that spin-label oximetry can directly and precisely measure myocardial oxygen consumption at constant temperature during ischemia in the intact heart. PMID:8958135

  1. Regional myocardial blood flow in man during dipyridamole coronary vasodilation

    SciTech Connect

    Sorensen, S.G.; Groves, B.M.; Horwitz, L.D.; Chaudhuri, T.K.

    1985-06-01

    Regional myocardial blood flow before and after intravenous dipyridamole (0.56 mg/kg) was measured during cardiac catheterization in 11 patients using the /sup 133/Xe washout technique. Significant increases in heart rate and decreases in systolic blood pressure were observed with dipyridamole infusion. However, double product and cardiac output did not differ before or after drug infusion. Regional myocardial blood flow increased from 67 to 117 ml/100 mg/min in myocardial segments supplied by nonobstructed coronary arteries. In stenotic coronary arteries, flow increased from 57 to 79 ml/100 mg/min with dipyridamole. We conclude that dipyridamole infusion results in flow differences which discriminate stenotic from nonstenotic coronary arteries.

  2. Modeling to link regional myocardial work, metabolism and blood flows

    PubMed Central

    Bassingthwaighte, James B.; Beard, Daniel A; Carlson, Brian E.; Dash, Ranjan K.; Vinnakota, Kalyan

    2012-01-01

    Given the mono-functional, highly coordinated processes of cardiac excitation and contraction, the observations that regional myocardial blood flows, rMBF, are broadly heterogeneous has provoked much attention, but a clear explanation has not emerged. In isolated and in vivo heart studies the total coronary flow is found to be proportional to the rate-pressure product (systolic mean blood pressure times heart rate), a measure of external cardiac work. The same relationship might be expected on a local basis: more work requires more flow. The validity of this expectation has never been demonstrated experimentally. In this article we review the concepts linking cellular excitation and contractile work to cellular energetics and ATP demand, substrate utilization, oxygen demand, vasoregulation, and local blood flow. Mathematical models of these processes are now rather well developed. We propose that the construction of an integrated model encompassing the biophysics, biochemistry and physiology of cardiomyocyte contraction, then combined with a detailed three-dimensional structuring of the fiber bundle and sheet arrangements of the heart as a whole will frame an hypothesis that can be quantitatively evaluated to settle the prime issue: Does local work drive local flow in a predictable fashion that explains the heterogeneity? While in one sense one can feel content that work drives flow is irrefutable, there are no cardiac contractile models that demonstrate the required heterogeneity in local strain-stress-work; quite the contrary, cardiac contraction models have tended toward trying to show that work should be uniform. The object of this review is to argue that uniformity of work does not occur, and is impossible in any case, and that further experimentation and analysis are necessary to test the hypothesis. PMID:22915334

  3. Feasibility Study of Myocardial Perfusion and Oxygenation by Non-Contrast MRI: Comparison with PET Study in a Canine Model

    PubMed Central

    McCommis, Kyle S.; Zhang, Haosen; Herrero, Pilar; Gropler, Robert J.; Zheng, Jie

    2008-01-01

    The purpose of this study was to examine the feasibility of quantifying myocardial blood flow (MBF) and rate of myocardial oxygen consumption (MVO2) during pharmacologically induced stress without using a contrast agent. The former was measured by the arterial spin labeling (ASL) method and the later was obtained by measuring the oxygen extraction fraction (OEF) with the magnetic resonance imaging (MRI) blood oxygenation level-dependent (BOLD) effect and Fick's law. The MRI results were compared with the established positron emission tomography (PET) methods. Six mongrel dogs with induced acute moderate left coronary artery stenosis were scanned using a clinical PET and a 1.5T MRI system, in the same day. Regional MBF, myocardial OEF, and MVO2 were measured with both imaging modalities. Correlation coefficients (R2) of the three myocardial indexes (MBF, OEF, and MVO2) between MRI and PET methods ranged from 0.70 to 0.93. Bland-Altman statistics demonstrated that the estimated precision of the limits of agreement between MRI and PET measurements varied from 18% (OEF), to 37% (MBF), and 45% (MVO2). The detected changes in these indexes, at rest and during dobutamine stress, were similar between two image modalities. The proposed non-contrast MRI technique is a promising method to quantitatively assess myocardial perfusion and oxygenation. PMID:17566684

  4. Human Umbilical Cord Blood for Transplantation Therapy in Myocardial Infarction

    PubMed Central

    Acosta, Sandra A; Franzese, Nick; Staples, Meaghan; Weinbren, Nathan L.; Babilonia, Monica; Patel, Jason; Merchant, Neil; Simancas, Alejandra Jacotte; Slakter, Adam; Caputo, Mathew; Patel, Milan; Franyuti, Giorgio; Franzblau, Max H.; Suarez, Lyanne; Gonzales-Portillo, Chiara; Diamandis, Theo; Shinozuka, Kazutaka; Tajiri, Naoki; Sanberg, Paul R.; Kaneko, Yuji; Miller, Leslie W.; Borlongan, Cesar V.

    2013-01-01

    Cell-based therapy is a promising therapy for myocardial infarction. Endogenous repair of the heart muscle after myocardial infarction is a challenge because adult cardiomyocytes have a limited capacity to proliferate and replace damaged cells. Pre-clinical and clinical evidence has shown that cell based therapy may promote revascularization and replacement of damaged myocytes after myocardial infarction. Adult stem cells can be harvested from different sources including bone marrow, skeletal myoblast, and human umbilical cord blood cells. The use of these cells for the repair of myocardial infarction presents various advantages over other sources of stem cells. Among these are easy harvesting, unlimited differentiation capability, and robust angiogenic potential. In this review, we discuss the milestone findings and the most recent evidence demonstrating the therapeutic efficacy and safety of the transplantation of human umbilical cord blood cells as a stand-alone therapy or in combination with gene therapy, highlighting the importance of optimizing the timing, dose and delivery methods, and a better understanding of the mechanisms of action that will guide the clinical entry of this innovative treatment for ischemic disorders, specifically myocardial infarction. PMID:24307973

  5. Direct measurement of myocardial oxygen tension and high energy phosphate content under varying ventilatory conditions in rabbits.

    PubMed

    Vogt, Sebastian; Troitzsch, Dirk; Spath, Silvia; Portig, Irene; Moosdorf, Rainer

    2009-08-01

    Effective myocardial oxygen supply should not be compromised during cardiac surgery as it is essential to avoid circulatory and cardiac dysfunction. Local measurement of myocardial oxygen partial pressure (pO2) was therefore introduced into the operative monitoring of myocardial ischemia. The aim of the present study was to assess whether myocardial oxygen partial pressure correlates with the content of high energy phosphates (HEPs). Seven male rabbits were examined in parallel with measurement of myocardial pO2 by an implanted Clark electrode and 31phosphorus-NMR spectroscopy. The ventilatory management established hyperoxygenation followed by systemic hypoxia with hypercapnia for 20 min. Additionally, analysis of end-expiratory gas composition in combination with blood gas analysis was performed simultaneously, and hemodynamic parameter was recorded. Under hypoxic conditions the cardiovascular system was severely compromised, whereas the myocardial pO2 was only moderately impaired (pO2M 45.0+/-16.0 mm Hg). Immediately before cardiac arrest, low values of arterial and venous pO2 were found (17.6+/-6.0 and 12.9+/-6.1 mm Hg). In contrast to near normal myocardial pO2, HEP content in the myocardium was considerably reduced and inorganic phosphorus was increased. Artificial ventilation leading to systemic hypoxia and eventually circulatory arrest resulted in almost normal myocardial pO2 but severely compromised HEP content. This somewhat unexpected finding requires further clarification, but is in accordance with findings reported previously where regulatory mechanisms have been shown to play a role in the pathophysiology of severe hypoxic conditions such as those for cellular oxygen delivery and demand, P/O coupling and finally control of HEP production facilitating the interaction between respiratory chain and myoglobin oxygen transport. PMID:19807283

  6. Quantitative Assessment of Myocardial Blood Flow with SPECT.

    PubMed

    Petretta, Mario; Storto, Giovanni; Pellegrino, Teresa; Bonaduce, Domenico; Cuocolo, Alberto

    2015-01-01

    The quantitative assessment of myocardial blood flow (MBF) and coronary flow reserve (CFR) may be useful for the functional evaluation of coronary artery disease, allowing judgment of its severity, tracking of disease progression, and evaluation of the anti-ischemic efficacy of therapeutic strategies. Quantitative estimates of myocardial perfusion and CFR can be derived from single-photon emission computed tomography (SPECT) myocardial perfusion images by use of equipment, tracers, and techniques that are available in most nuclear cardiology laboratories. However, this method underestimates CFR, particularly at high flow rates. The recent introduction of cardiac-dedicated gamma cameras with solid-state detectors provides very fast perfusion imaging with improved resolution, allowing fast acquisition of serial dynamic images during the first pass of a flow agent. This new technology holds great promise for MBF and CFR quantification with dynamic SPECT. Future studies will clarify the effectiveness of dynamic SPECT flow imaging. PMID:25560327

  7. Altered filtrability of white blood cells after myocardial infarction.

    PubMed

    Bogár, L; Mikita, J; Nash, G B; Smith, M J; Dormandy, J A; Tekeres, M

    1989-01-01

    Abnormal white blood cell rheological behaviour has been implicated as a cause of blood flow disturbances under conditions of ischaemia and reduced perfusion pressure. Accordingly, we have tested the mechanical properties of white cells following myocardial infarction by measuring the rate at which suspension of these cells cause plugging of Nuclepore filters. The number of clogging particles in a standard white cell suspension increased by the third day after infarction but subsequently decreased to the control levels. Since white cells can cause blockage of narrow blood vessels, it is assumed that such changes in cellular properties may influence the eventual extent of infarction. PMID:2812961

  8. Optoacoustic monitoring of cerebral venous blood oxygenation through extracerebral blood

    PubMed Central

    Petrov, I. Y.; Petrov, Y.; Prough, D. S.; Deyo, D. J.; Cicenaite, I.; Esenaliev, R. O.

    2011-01-01

    There is strong clinical evidence that controlling cerebral venous oxygenation (oxyhemoglobin saturation) is critically important for patients with severe traumatic brain injury as well as for patients undergoing cardiac surgery. However, the only available method for cerebral venous blood oxygenation monitoring is invasive and requires catheterization of the internal jugular vein. We designed and built a novel optoacoustic monitor of cerebral venous oxygenation as measured in the superior sagittal sinus (SSS), the large midline cerebral vein. To the best of our knowledge, optical monitoring of cerebral venous blood oxygenation through overlying extracerebral blood is reported for the first time in this paper. The system was capable of detecting SSS signals in vivo at 700, 800, and 1064 nm through the thick (5–6 mm) sheep skull containing the circulating blood. The high (submillimeter) in-depth resolution of the system provided identification of the SSS peaks in the optoacoustic signals. The SSS peak amplitude closely followed the actual SSS blood oxygenation measured invasively using catheterization, blood sampling, and “gold standard” CO-Oximetry. Our data indicate the system may provide accurate measurement of the SSS blood oxygenation in patients with extracerebral blood over the SSS. PMID:22254173

  9. Assessment of myocardial blood perfusion improved by CD151 in a pig myocardial infarction model

    PubMed Central

    Zuo, Hou-juan; Liu, Zheng-xiang; Liu, Xiao-chun; Yang, Jun; Liu, Tao; Wen, Sha; Wang, Dao-wen; Zhang, Xin

    2009-01-01

    Aim: To appraise the efficacy of CD151-induced myocardial therapeutic angiogenesis in a pig myocardial infarction model. Methods: CD151 and anti-CD151 were constructed into the recombinant adeno-associated virus (rAAV) vector. All 26 pigs were subjected to coronary artery ligation or no surgery. Eight weeks after coronary artery ligation, the expression of CD151 was measured by Western blot and immunostaining. Capillary density was evaluated using immunostaining for von Willebrand factor (vWF). 13N-labeled NH3 positron emission computed tomography ([13N]NH3 PET) was measured to assess regional myocardial perfusion and the defect area. Results: CD151 gene delivery could increase the expression of CD151 at protein level. Over-expression of CD151 increased the density of total capillaries in the ischemic myocardium, significantly improved the blood perfusion and reduced the defect area percentage. Conclusion: This study demonstrated that the rAAV-mediated CD151 gene delivery promoted efficient neovascularization and increased the blood perfusion after myocardial infarction in pigs. PMID:19079294

  10. Preservation of canine myocardial high-energy phosphates during low-flow ischemia with modification of hemoglobin–oxygen affinity

    PubMed Central

    Weiss, Robert G.; Mejia, Marco A.; Kass, David A.; DiPaula, Anthony F.; Becker, Lewis C.; Gerstenblith, Gary; Chacko, V.P.

    1999-01-01

    Conventional approaches for the treatment of myocardial ischemia increase coronary blood flow or reduce myocardial demand. To determine whether a rightward shift in the hemoglobin–oxygen saturation curve would reduce the metabolic and contractile effects of a myocardial oxygen-supply imbalance, we studied the impact of a potent synthetic allosteric modifier of hemoglobin–oxygen affinity, a 2-[4-[[(3,5-disubstituted anilino)carbonyl]methyl] phenoxy] -2-methylproprionic acid derivative (RSR13), during low-flow ischemia. Changes in myocardial high-energy phosphate levels and pH were studied by 31P nuclear magnetic resonance (NMR) spectroscopy in 12 open-chest dogs randomized to receive RSR13 or vehicle control during a reversible reduction of left anterior descending (LAD) coronary artery blood flow. Changes in cardiac metabolites and regional ventricular function studied by pressure segment–length relations were also investigated in additional animals before and after RSR13 administration during low-flow LAD ischemia. The intravenous administration of RSR13 before ischemia resulted in a substantial increase in the mean hemoglobin p50 and attenuated the decline in cardiac creatine phosphate/adenosine triphosphate (PCr/ATP), percent PCr, and pH during ischemia without a change in regional myocardial blood flow, heart rate, or systolic blood pressure. RSR13 given after the onset of low-flow ischemia also improved cardiac PCr/ATP ratios and regional function as measured by fractional shortening and regional work. Thus, synthetic allosteric reduction in hemoglobin–oxygen affinity may be a new and important therapeutic strategy to ameliorate the metabolic and functional consequences of cardiac ischemia. J. Clin. Invest. 103:739–746 (1999) PMID:10074492

  11. Preservation of canine myocardial high-energy phosphates during low-flow ischemia with modification of hemoglobin-oxygen affinity.

    PubMed

    Weiss, R G; Mejia, M A; Kass, D A; DiPaula, A F; Becker, L C; Gerstenblith, G; Chacko, V P

    1999-03-01

    Conventional approaches for the treatment of myocardial ischemia increase coronary blood flow or reduce myocardial demand. To determine whether a rightward shift in the hemoglobin-oxygen saturation curve would reduce the metabolic and contractile effects of a myocardial oxygen-supply imbalance, we studied the impact of a potent synthetic allosteric modifier of hemoglobin-oxygen affinity, a 2-[4-[[(3,5-disubstituted anilino)carbonyl]methyl] phenoxy] -2-methylproprionic acid derivative (RSR13), during low-flow ischemia. Changes in myocardial high-energy phosphate levels and pH were studied by 31P nuclear magnetic resonance (NMR) spectroscopy in 12 open-chest dogs randomized to receive RSR13 or vehicle control during a reversible reduction of left anterior descending (LAD) coronary artery blood flow. Changes in cardiac metabolites and regional ventricular function studied by pressure segment-length relations were also investigated in additional animals before and after RSR13 administration during low-flow LAD ischemia. The intravenous administration of RSR13 before ischemia resulted in a substantial increase in the mean hemoglobin p50 and attenuated the decline in cardiac creatine phosphate/adenosine triphosphate (PCr/ATP), percent PCr, and pH during ischemia without a change in regional myocardial blood flow, heart rate, or systolic blood pressure. RSR13 given after the onset of low-flow ischemia also improved cardiac PCr/ATP ratios and regional function as measured by fractional shortening and regional work. Thus, synthetic allosteric reduction in hemoglobin-oxygen affinity may be a new and important therapeutic strategy to ameliorate the metabolic and functional consequences of cardiac ischemia. PMID:10074492

  12. Myocardial blood flow: Roentgen videodensitometry techniques

    NASA Technical Reports Server (NTRS)

    Smith, H. C.; Robb, R. A.; Wood, E. H.

    1975-01-01

    The current status of roentgen videodensitometric techniques that provide an objective assessment of blood flow at selected sites within the coronary circulation were described. Roentgen videodensitometry employs conventional radiopaque indicators, radiological equipment and coronary angiographic techniques. Roentgen videodensitometry techniques developed in the laboratory during the past nine years, and for the past three years were applied to analysis of angiograms in the clinical cardiac catheterization laboratory.

  13. Rate-pressure product and myocardial oxygen consumption during surgery for coronary artery bypass.

    PubMed

    Wilkinson, P L; Moyers, J R; Ports, T; Chatterjee, K; Ullyott, D; Hamilton, W K

    1979-08-01

    Rate-pressure product (RPP) is a sensitive index of myocardial oxygen consumption (mVO2) in awake people. We wished to determine whether this relationship persisted under anesthesia and in the face of concurrent large changes in myocardial contractility and left ventricular filling pressures. In 16 patients scheduled for coronary artery bypass surgery, we inserted coronary sinus and Swan-Ganz catheters, and a central aortic catheter via the brachial artery, before induction of anesthesia with either morphine (2 mg/kg) or halothane, chosen in random order. We measured aortic, pulmonary, and venous pressures, cardiac output, systolic time intervals, and thermodilution coronary sinus flow. We calculated mVO2 as coronary sinus flow times myocardial arteriovenous oxygen content difference. We found significant correlations between mVO2 and heart rate (r = 0.57), systolic blood pressure (r = 0.52), the index delta /delta T (r = 0.53, and RPP (r = 0.78). Multiple regression of RPP and delta P/delta T against mVO2 increased their correlation (r = 0.86), while multiple regression of RPP and pulmonary wedge pressure against mVo2 did not significantly improve the correlation of RPP alone (r = 0.75). We conclude that hemodynamic changes anesthesia and surgery do not decrease the sensitivity of RPP as an index of mVO2. PMID:312708

  14. Oxygenation of human blood using photocatalytic reaction.

    PubMed

    Subrahmanyam, Aryasomayajula; Ramesh, Thangaraj P; Ramakrishnan, Nagarajan

    2007-01-01

    This report, as a proof of concept, presents the results of oxygenation of human blood using photocatalytic reaction (at lambda = 352 nm) involving the semiconductor thin film junction: tin doped indium oxide (ITO)/nano titanium oxide (TiO2 in anatase structure). These thin films were prepared at room temperature (300 K) on quartz, using reactive DC Magnetron sputtering techniques from pure metallic targets. The results indicate that when 10.0 mL of blood was exposed to ITO/nano TiO2 (14.32 cm surface area) at a wavelength of 352 nm for 120 minutes, the absolute increase in the whole blood oxygen content was 10.13 mL of oxygen per 100.0 mL of blood. This experiment, to our knowledge, is the first of its kind on human blood. PMID:17667227

  15. Effect of alpha 1-adrenergic blockade on myocardial blood flow during exercise after myocardial infarction.

    PubMed

    Herzog, C A; Dai, X Z; Bache, R J

    1991-08-01

    The effect of alpha 1-adrenergic blockade with prazosin on myocardial blood flow at rest and during two levels of treadmill exercise was assessed in 16 chronically instrumented dogs 9-14 days after myocardial infarction had been produced by occlusion of the left circumflex coronary artery. During resting conditions prazosin did not alter mean myocardial blood flow or the subendocardial-to-subepicardial flow ratio in either normally perfused or collateral-dependent myocardium. However, during exercise at comparable external work loads and comparable rate-pressure products, prazosin significantly increased blood flow to normally perfused (27% increase at the second level of exercise, P less than 0.001) and collateral-dependent myocardium (35% increase at the second level of exercise, P less than 0.001) compared with control. In addition, prazosin caused a small but significant decrease in the subendocardial-to-subepicardial flow ratio in both normal (1.27 +/- 0.04 to 1.19 +/- 0.04; P less than 0.01) and collateral-dependent myocardium (0.57 +/- 0.11 to 0.52 +/- 0.11; P less than 0.01) compared with control, reflecting a disproportionally greater increase in subepicardial flow in response to alpha 1-adrenergic blockade. These data demonstrate that alpha 1-adrenergic vasoconstriction inhibits coronary vasodilation during exercise, even in areas of collateral-dependent myocardium relatively early after coronary artery occlusion. PMID:1678929

  16. Hyperoxia causes oxygen free radical-mediated membrane injury and alters myocardial function and hemodynamics in the newborn.

    PubMed

    Bandali, K S; Belanger, M P; Wittnich, C

    2004-08-01

    Newborn children can be exposed to high oxygen levels (hyperoxia) for hours to days during their medical and/or surgical management, and they also can have poor myocardial function and hemodynamics. Whether hyperoxia alone can compromise myocardial function and hemodynamics in the newborn and whether this is associated with oxygen free radical release that overwhelms naturally occurring antioxidant enzymes leading to myocardial membrane injury was the focus of this study. Yorkshire piglets were anesthetized with pentobarbital sodium (65 mg/kg), intubated, and ventilated to normoxia. Once normal blood gases were confirmed, animals were randomly allocated to either 5 h of normoxia [arterial Po(2) (Pa(O(2))) = 83 +/- 5 mmHg, n = 4] or hyperoxia (Pa(O(2)) = 422 +/- 33 mmHg, n = 6), and myocardial functional and hemodynamic assessments were made hourly. Left ventricular (LV) biopsies were taken for measurements of antioxidant enzyme activities [superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)] and malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) as an indicator of oxygen free radical-mediated membrane injury. Hyperoxic piglets suffered significant reductions in contractility (P < 0.05), systolic blood pressure (P < 0.03), and mean arterial blood pressure (P < 0.05). Significant increases were seen in heart rate (P < 0.05), whereas a significant 11% (P < 0.05) and 61% (P < 0.001) reduction was seen in LV SOD and GPx activities, respectively, after 5 h of hyperoxia. Finally, MDA and 4-HNE levels were significantly elevated by 45% and 38% (P < 0.001 and P = 0.02), respectively, in piglets exposed to hyperoxia. Thus, in the newborn, hyperoxia triggers oxygen free radical-mediated membrane injury together with an inability of the newborn heart to upregulate its antioxidant enzyme defenses while impairing myocardial function and hemodynamics. PMID:15277198

  17. Control of intraoperative hypertension with isoflurane in patients with coronary artery disease: effects on regional myocardial blood flow and metabolism.

    PubMed

    Sahlman, L; Milocco, I; Appelgren, L; William-Olsson, G; Ricksten, S E

    1989-02-01

    The effect of isoflurane on regional myocardial metabolism and blood flow, when used as an adjunct to fentanyl-nitrous oxide anesthesia, to control intraoperative hypertension was investigated. Twenty-two patients with two- or three-vessel coronary artery disease with an ejection fraction greater than 0.5 and on beta-blockers up to the morning of surgery were studied during elective coronary artery by-pass grafting. Systemic and pulmonary hemodynamics, and regional (great cardiac vein, GCVF) myocardial blood flow and myocardial metabolic parameters were measured. In 10 patients, both GCVF and global (coronary sinus, CSF) myocardial blood flows were recorded. Measurements were made 1) after induction of anesthesia but prior to skin incision, 2) during sternotomy, and 3) during isoflurane administration after its use to reduce arterial pressure to the presternotomy level. The increase in systemic arterial pressure during sternotomy was due to an increase in systemic vascular resistance accompanied by increases in heart rate, pulmonary capillary wedge pressure, (PCWP) regional myocardial oxygen consumption and extraction, GCVF and total coronary vascular resistance. Isoflurane reduced systemic arterial pressure but not PCWP, to presternotomy levels within 6.9 +/- 0.7 minutes at an end-tidal concentration of 1.5 +/- 0.2%. Isoflurane induced a pronounced systemic and coronary vasodilatation and increases in cardiac index, heart rate and regional myocardial oxygen extraction while the GCVF/CSF ratio remained unchanged. While mean regional--MLE% values were not effected by sternotomy, in two patients myocardial lactate production was seen during sternotomy but not during isoflurane. In another two patients, isoflurane induced lactate production.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2783640

  18. Blood conservation for myocardial revascularization. Is it cost effective?

    PubMed

    Breyer, R H; Engelman, R M; Rousou, J A; Lemeshow, S

    1987-04-01

    A total of 284 patients undergoing myocardial revascularization were prospectively studied to determine if the use of intraoperative autotransfusion or intraoperative autotransfusion plus postoperative reinfusion of shed mediastinal blood decreased transfusion requirements and the use of one or both techniques was cost effective. The Haemonetics Cell Saver System was used for intraoperative autotransfusion and the Sorenson Receptaseal autotransfusion system for postoperative reinfusion of shed mediastinal blood. During Phase 1, the Cell Saver System was used for 57 patients and 93 patients served as a control group. During Phase 2, the Cell Saver System plus the autotransfusion system were used in 43 patients and 91 patients were in the control group. Separate parallel analyses to compare the blood conservation groups to control groups were conducted for each phase of the study. The patient groups were comparable with regard to age, sex, preoperative red cell mass, preoperative hematocrit value, number of bypasses, and use of internal mammary grafts. Blood conservation techniques resulted in significant reductions in the use of bank blood. During Phase 1, Cell Saver System patients received an average of 2.8 units of packed cells versus 4.7 units for control patients. Transfusion was avoided entirely in 14% of Cell Saver System patients compared to 3% of control patients. During Phase 2, patients subjected to both the Cell Saver System and the autotransfusion system received an average of 1 unit of packed red cells versus 3 units for control patients. Transfusion was required in only 42% of patients subjected to both the Cell Saver System and the autotransfusion system compared to 85% of control patients. Multiple logistic regression analysis confirmed that the use of the Cell Saver System in Phase 1 and the Cell Saver System and autotransfusion system in Phase 2 were each independently predictive of decreased transfusion requirements. The total "blood

  19. Myocardial function after polarizing versus depolarizing cardiac arrest with blood cardioplegia in a porcine model of cardiopulmonary bypass†

    PubMed Central

    Aass, Terje; Stangeland, Lodve; Moen, Christian Arvei; Salminen, Pirjo-Riitta; Dahle, Geir Olav; Chambers, David J.; Markou, Thomais; Eliassen, Finn; Urban, Malte; Haaverstad, Rune; Matre, Knut; Grong, Ketil

    2016-01-01

    OBJECTIVES Potassium-based depolarizing St Thomas' Hospital cardioplegic solution No 2 administered as intermittent, oxygenated blood is considered as a gold standard for myocardial protection during cardiac surgery. However, the alternative concept of polarizing arrest may have beneficial protective effects. We hypothesize that polarized arrest with esmolol/adenosine/magnesium (St Thomas' Hospital Polarizing cardioplegic solution) in cold, intermittent oxygenated blood offers comparable myocardial protection in a clinically relevant animal model. METHODS Twenty anaesthetized young pigs, 42 ± 2 (standard deviation) kg on standardized tepid cardiopulmonary bypass (CPB) were randomized (10 per group) to depolarizing or polarizing cardiac arrest for 60 min with cardioplegia administered in the aortic root every 20 min as freshly mixed cold, intermittent, oxygenated blood. Global and local baseline and postoperative cardiac function 60, 120 and 180 min after myocardial reperfusion was evaluated with pressure–conductance catheter and strain by Tissue Doppler Imaging. Regional tissue blood flow, cleaved caspase-3 activity, GRK2 phosphorylation and mitochondrial function and ultrastructure were evaluated in myocardial tissue samples. RESULTS Left ventricular function and general haemodynamics did not differ between groups before CPB. Cardiac asystole was obtained and maintained during aortic cross-clamping. Compared with baseline, heart rate was increased and left ventricular end-systolic and end-diastolic pressures decreased in both groups after weaning. Cardiac index, systolic pressure and radial peak systolic strain did not differ between groups. Contractility, evaluated as dP/dtmax, gradually increased from 120 to 180 min after declamping in animals with polarizing cardioplegia and was significantly higher, 1871 ± 160 (standard error) mmHg/s, compared with standard potassium-based cardioplegic arrest, 1351 ± 70 mmHg/s, after 180 min of reperfusion (P = 0

  20. Longitudinal myocardial blood flow gradient and CAD detection.

    PubMed

    Valenta, Ines; Wahl, Richard L; Schindler, Thomas H

    2015-01-01

    Conventional myocardial perfusion scintigraphy with SPECT/CT or with PET/CT has been established as pivotal clinical imaging modality for the identification of hemodynamically obstructive coronary artery disease (CAD) and risk stratification of patients with suspected or known CAD. While the assessment of the relative distribution of radiotracer uptake in the left-ventricular (LV) myocardium during vasomotor stress identifies the "culprit" or most severe CAD lesion in multivessel disease, flow-limiting effects of remaining but less severe epicardial lesions may be missed. This limitation principally may be overcome by the possibility of PET/CT with radiotracer-kinetic modeling to concurrently assess left-ventricular (LV) myocardial blood flow (MBF) in ml/g/min at rest and during vasomotor stress and the resulting myocardial flow reserve (MFR). While a stress-induced regional reduction in radiotracer uptake or perfusion identifies the most advanced epicardial lesion, flow-limiting effects of the other epicardial lesions may principally be identified by regional reductions in MFR. Conversely, reductions in MFR in CAD may be appreciated as suboptimal as they reflect not only the consequences of flow-limiting effects of epicardial stenosis but also of microvascular dysfunction. The relatively low specificity of a reduced therefore MFR may hamper a clear identification of the downstream hemodynamic effects of an epicardial lesion on hyperemic coronary flow increases. In this scenario, there is increasing evidence that the PET assessment of an abnormal decrease in MBF from the base to the apex of the LV during hyperemic flows, a so-called longitudinal flow gradient, is primarily related to fluid dynamic consequences of CAD-induced diffuse luminal and/or focal narrowing of the epicardial artery. The combined evaluation of the MFR and corresponding longitudinal MBF gradient could emerge as new a novel analytic concept to further optimize the identification and

  1. Effects of commonly used inotropes on myocardial function and oxygen consumption under constant ventricular loading conditions.

    PubMed

    DeWitt, Elizabeth S; Black, Katherine J; Thiagarajan, Ravi R; DiNardo, James A; Colan, Steven D; McGowan, Francis X; Kheir, John N

    2016-07-01

    Inotropic medications are routinely used to increase cardiac output and arterial blood pressure during critical illness. However, few comparative data exist between these medications, particularly independent of their effects on venous capacitance and systemic vascular resistance. We hypothesized that an isolated working heart model that maintained constant left atrial pressure and aortic blood pressure could identify load-independent differences between inotropic medications. In an isolated heart preparation, the aorta and left atrium of Sprague Dawley rats were cannulated and placed in working mode with fixed left atrial and aortic pressure. Hearts were then exposed to common doses of a catecholamine (dopamine, epinephrine, norepinephrine, or dobutamine), milrinone, or triiodothyronine (n = 10 per dose per combination). Cardiac output, contractility (dP/dtmax), diastolic performance (dP/dtmin and tau), stroke work, heart rate, and myocardial oxygen consumption were compared during each 10-min infusion to an immediately preceding baseline. Of the catecholamines, dobutamine increased cardiac output, contractility, and diastolic performance more than clinically equivalent doses of norepinephrine (second most potent), dopamine, or epinephrine (P < 0.001). The use of triiodothyronine and milrinone was not associated with significant changes in cardiac output, contractility or diastolic function, either alone or added to a baseline catecholamine infusion. Myocardial oxygen consumption was closely related to dP/dtmax (r(2) = 0.72), dP/dtmin (r(2) = 0.70), and stroke work (r(2) = 0.53). In uninjured, isolated working rodent hearts under constant ventricular loading conditions, dobutamine increased contractility and cardiac output more than clinically equivalent doses of norepinephrine, dopamine, and epinephrine; milrinone and triiodothyronine did not have significant effects on contractility. PMID:27150829

  2. Blood oxygenation monitoring by diffuse optical tomography

    SciTech Connect

    Patachia, M; Dutu, D.C.A.; Dumitras, D.C.

    2011-01-24

    Diffuse optical tomography (DOT) makes it possible to reconstruct, in two or three dimensions, the internal structure of the biological tissues based on the distribution of the absorption coefficient and the reduced scattering coefficient, using optical measurements at multiple source - detector positions on the tissue surface. The measurement of the light intensity transmitted through the tissue can be also used to compute the haemoglobin and oxyhaemoglobin concentrations, measuring the selective absorption of the main blood chromophores by near infrared spectroscopy (NIRS). The spectral selectivity of the system and the evaluation of the blood volume and blood oxygenation (BV and OXY distributions), together with the reconstruction of the inner structure of the tissue, can improve the accuracy of early cancer diagnosis, based on the tissue angiogenesis characterisation. (application of lasers and laser-optical methods in life sciences)

  3. [The content of selen in blood plasma in patients with acute Q-wave myocardial infarction].

    PubMed

    Radchenko, E N; Nizov, A A; Ivanova, A Yu; Sidorova, Yu S

    2015-01-01

    The level of blood plasma selenium was analyzed by microfluorimetric method in in-patients and out-patients with acute coronary syndrome with ST-elevation resulting in acute Q-wave myocardial infarction. 72 patients, 40-75 years old, with acute Q-wave myocardial infarction were followed during a month. The initial decreased concentration of blood plasma selenium was recorded in most patients in the acute period of the myocardial infarction: deficiency of the microelement (< 90 mcg/l) was found in 30 subjects, the critical ranges (< 70 mcg/l) were stated in 33 patients. Just 2 patients had optimal concentration and 7 patients had a suboptimal one (90-114 mcg/l). Blood plasma level of the microelement increased in 2 weeks after myocardial infarction (in subacute stage) but it was still within deficient or critical levels. No difference was detected in selen concentration depending on gender, age, location on myocardial infarction, accompanying diseases, presence of some risk factors (smoking, alcohol abuse, hereditary predisposition to coronary artery disease). At the same time we revealed a significant Spearman rank correlation in patients with Q-wave myocardial infarction between basal level of blood serum selenium on the one hand, and electrocardiography indices (reflecting the rate of myocardial lesion and necrosis), echocardiography. data (which characterize myocardium reparation processes and remodeling), CPK (a prognostic marker of the myocardial necrosis), HDL-cholesterol (lipid profile index), blood potassium level and BMI on the other. PMID:26863808

  4. Effect of streptozotocin-induced diabetes on myocardial blood flow reserve assessed by myocardial contrast echocardiography in rats

    PubMed Central

    Cosyns, Bernard; Droogmans, Steven; Hernot, Sophie; Degaillier, Céline; Garbar, Christian; Weytjens, Caroline; Roosens, Bram; Schoors, Danny; Lahoutte, Tony; Franken, Philippe R; Van Camp, Guy

    2008-01-01

    The role of structural and functional abnormalities of small vessels in diabetes cardiomyopathy remains unclear. Myocardial contrast echocardiography allows the quantification of myocardial blood flow at rest and during dipyridamole infusion. The aim of the study was to determine the myocardial blood flow reserve in normal rats compared with Streptozotocin-induced diabetic rats using contrast echocardiography. We prospectively studied 40 Wistar rats. Diabetes was induced by intravenous streptozotocin in 20 rats. All rats underwent baseline and stress (dipyridamole: 20 mg/kg) high power intermittent imaging in short axis view under anaesthesia baseline and after six months. Myocardial blood flow was determined and compared at rest and after dipyridamole in both populations. The myocardial blood flow reserve was calculated and compared in the 2 groups. Parameters of left ventricular function were determined from the M-mode tracings and histological examination was performed in all rats at the end of the study. At six months, myocardial blood flow reserve was significantly lower in diabetic rats compared to controls (3.09 ± 0.98 vs. 1.28 ± 0.67 ml min-1 g-1; p < 0.05). There were also a significant decrease in left ventricular function and a decreased capillary surface area and diameter at histology in the diabetic group. In this animal study, diabetes induced a functional alteration of the coronary microcirculation, as demonstrated by contrast echocardiography, a decrease in capillary density and of the cardiac systolic function. These findings may offer new insights into the underlying mechanisms of diabetes cardiomyopathy. PMID:18764943

  5. Myocardial extraction of teboroxime: effects of teboroxime interaction with blood.

    PubMed

    Rumsey, W L; Rosenspire, K C; Nunn, A D

    1992-01-01

    The isolated perfused rat heart preparation was used to determine whether the interaction of blood with either 99mTc-teboroxime, 99mTc-sestamibi or 201TI affects the extraction of these myocardial perfusion agents. Hearts were retrogradely perfused at 72 cm H2O with Krebs-Henseleit buffer equilibrated with O2:CO2 (95:5). The hearts were paced at 5 Hz. Single-pass extraction of 99mTc-teboroxime (96% +/- 1%) was greater than that of 99mTc-sestamibi (15% +/- 1%) or 201TI (30% +/- 5%). Extraction of the hydroxide form of 99mTc-teboroxime was only 43% +/- 4%. When arterial blood obtained from rats administered 99mTc-teboroxime was injected into the perfused heart, extraction of 99mTc-teboroxime decreased progressively as its time in circulation was lengthened. Similar experiments using either 99mTc-sestamibi or 201TI showed that extraction of these agents was neither affected by the presence of blood nor residence in circulation. For 99mTc-teboroxime, extraction was 99.5% +/- 0.5%, 57% +/- 13%, 20% +/- 2% at 1, 5, and 60 min postinjection, respectively. In separate experiments, HPLC analysis of blood at 5, 15 and 60 min postinjection indicated that only 34% +/- 4%, 13% +/- 2%, and 2% +/- 1%, respectively, of the total 99mTc-teboroxime was free and was associated with extraction values of 44% +/- 7%, 28% +/- 5%, and 19% +/- 3%, respectively. The percentage of this free radioactivity that converted from the chloro to the hydroxide form was 9% +/- 2%, 6% +/- 2%, and 2% +/- 1%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1530970

  6. Exercise Training Reduces Peripheral Arterial Stiffness and Myocardial Oxygen Demand in Young Prehypertensive Subjects

    PubMed Central

    2013-01-01

    BACKGROUND Large artery stiffness is a major risk factor for the development of hypertension and cardiovascular disease. Persistent prehypertension accelerates the progression of arterial stiffness. METHODS Forty-three unmedicated prehypertensive (systolic blood pressure (SBP) = 120–139mm Hg or diastolic blood pressure (DBP) = 80–89mm Hg) men and women and 15 normotensive time-matched control subjects (NMTCs; n = 15) aged 18–35 years of age met screening requirements and participated in the study. Prehypertensive subjects were randomly assigned to a resistance exercise training (PHRT; n = 15), endurance exercise training (PHET; n = 13) or time-control group (PHTC; n = 15). Treatment groups performed exercise training 3 days per week for 8 weeks. Pulse wave analysis, pulse wave velocity (PWV), and central and peripheral blood pressures were evaluated before and after exercise intervention or time-matched control. RESULTS PHRT and PHET reduced resting SBP by 9.6±3.6mm Hg and 11.9±3.4mm Hg, respectively, and DBP by 8.0±5.1mm Hg and 7.2±3.4mm Hg, respectively (P < 0.05). PHRT and PHET decreased augmentation index (AIx) by 7.5% ± 2.8% and 8.1% ± 3.2% (P < 0.05), AIx@75 by 8.0% ± 3.2% and 9.2% ± 3.8% (P < 0.05), and left ventricular wasted pressure energy, an index of extra left ventricular myocardial oxygen requirement due to early systolic wave reflection, by 573±161 dynes s/cm2 and 612±167 dynes s/cm2 (P < 0.05), respectively. PHRT and PHET reduced carotid–radial PWV by 1.02±0.32 m/sec and 0.92±0.36 m/sec (P < 0.05) and femoral–distal PWV by 1.04±0.31 m/sec and 1.34±0.33 m/sec (P < 0.05), respectively. No significant changes were observed in the time-control groups. CONCLUSIONS This study suggests that both resistance and endurance exercise alone effectively reduce peripheral arterial stiffness, central blood pressures, augmentation index, and myocardial oxygen demand in young prehypertensive subjects. PMID:23736111

  7. Thoracic epidural anesthesia during coronary artery bypass surgery: effects on cardiac sympathetic activity, myocardial blood flow and metabolism, and central hemodynamics.

    PubMed

    Kirnö, K; Friberg, P; Grzegorczyk, A; Milocco, I; Ricksten, S E; Lundin, S

    1994-12-01

    The effects of high thoracic epidural anesthesia (TEA) on cardiac sympathetic nerve activity, myocardial blood flow and metabolism, and central hemodynamics were studied in 20 patients undergoing coronary artery bypass grafting (CABG). In 10 of the patients, TEA (T1-5 block) was used as an adjunct to a standardized fentanyl-nitrous oxide anesthesia. Hemodynamic measurements and blood sampling were performed after induction of anesthesia but prior to skin incision and after sternotomy. Assessment of total and cardiac sympathetic activity was performed by means of the norepinephrine kinetic approach. Prior to surgery, mean arterial pressure (MAP), great cardiac vein flow (GCVF), and regional myocardial oxygen consumption (Reg-MVO2) were lower in the TEA group compared to the control group. During sternotomy there was a pronounced increase in cardiac norepinephrine spillover, MAP, systemic vascular resistance index (SVRI), pulmonary capillary wedge pressure (PCWP), GCVF, and Reg-MVO2 in the control group. These changes were clearly attenuated in the TEA group. None of the patients in the TEA group had metabolic (lactate) or electrocardiographic signs of myocardial ischemia. Three patients in the control group had indices of myocardial ischemia prior to and/or during surgery. We conclude that TEA attenuates the surgically mediated sympathetic stress response to sternotomy, thereby preventing the increase in myocardial oxygen demand in the pre-bypass period without jeopardizing myocardial perfusion. PMID:7978429

  8. Influence of glyceryl trinitrate and nifedipine on coronary sinus blood flow and global myocardial metabolism during coronary artery operation.

    PubMed

    van Wezel, H B; Bovill, J G; Koolen, J J; Patrick, M R; Fiolet, J W; van der Stroom, J G

    1986-09-01

    The effects of intravenous infusions of glyceryl trinitrate and nifedipine on systemic haemodynamic function, coronary haemodynamic function, and global myocardial metabolism were compared in two groups of eleven patients with unimpaired left ventricular function undergoing elective coronary artery operation who were anaesthetised with high dose fentanyl. Severe post-sternotomy hypertension developed in three patients in the glyceryl trinitrate group who were resistant to the hypotensive effect of this agent. All patients given nifedipine remained haemodynamically stable. Coronary sinus blood flow and myocardial oxygen consumption increased and coronary vascular resistance decreased after sternotomy in the nifedipine group but not in the glyceryl trinitrate group. There is no satisfactory explanation for the apparently paradoxical increase in myocardial oxygen consumption in the patients given nifedipine. This phenomenon did not appear to be associated with any detrimental effect of left ventricular function. Thus nifedipine was better than glyceryl trinitrate for the control of post-sternotomy hypertension in patients with good left ventricular function. Intravenous nifedipine is not recommended, however, for the intraoperative control of blood pressure in patients with unstable angina or impaired left ventricular function. PMID:3092847

  9. Oxygen surrounding the heart during ischemic conservation determines the myocardial injury during reperfusion.

    PubMed

    Feng, Yansheng; Bopassa, Jean Chrisostome

    2015-01-01

    There is discrepancy regarding the duration of reperfusion required using 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) staining to assess myocardial infarction in an isolated, perfused heart model. Several investigators prefer long-term reperfusion (120 minutes) to determine myocardial injury, while others have used a shorter duration (30-40 minutes). We investigated whether oxygen surrounding the myocardium during ischemia plays a critical role in the installation of myocardial infarction during reperfusion. Mice hearts were perfused with a Langendorff apparatus using Krebs Henseleit (KH) buffer oxygenated with 95% O2 plus 5% CO2 at 37°C. Hearts were either immersed in KH or suspended in air during 18 minutes of global ischemia in a normothermic, water-jacketed chamber. Hearts then were reperfused for 40, 60, or 90 minutes. We found that hearts immersed in KH had decreased recovery of function and increased myocardial infarct size, reaching a steady-state level after 40 minutes of reperfusion. In contrast, hearts suspended in air approached steady-state after 90 minutes of reperfusion. Thus, mitochondrial reactive oxygen species (ROS) production was much lower in air-maintained hearts than in KH-immersed hearts. To investigate whether an increase in oxygen surrounding the myocardium during ischemia might cause further damage, we bubbled the KH solution with nitrogen (KH+N2) rather than oxygen (KH+O2). With this alteration, recovery of cardiac function was improved and myocardial infarct size and mitochondrial ROS production were reduced compared with hearts immersed in KH+O2. In conclusion, short-term (40 minutes) reperfusion is sufficient to reach steady-state myocardial infarct size when hearts are immersed in physiologic solution during ischemia; however, a longer duration of reperfusion (90 minutes) is required if hearts are suspended in air. Thus, oxygen surrounding the heart during ischemia determines the extent of myocardium injury during reperfusion

  10. Optoacoustic measurements of human placenta and umbilical blood oxygenation

    NASA Astrophysics Data System (ADS)

    Nanovskaya, T. N.; Petrov, I. Y.; Petrov, Y.; Patrikeeva, S. L.; Ahmed, M. S.; Hankins, G. D. V.; Prough, D. S.; Esenaliev, R. O.

    2016-03-01

    Adequate oxygenation is essential for normal embryogenesis and fetal growth. Perturbations in the intrauterine oxidative environment during pregnancy are associated with several pathophysiological disorders such as pregnancy loss, preeclampsia, and intrauterine growth restriction. We proposed to use optoacoustic technology for monitoring placental and fetal umbilical blood oxygenation. In this work, we studied optoacoustic monitoring of oxygenation in placenta and umbilical cord blood ex vivo using technique of placenta perfusion. We used a medical grade, nearinfrared, tunable, optoacoustic system developed and built for oxygenation monitoring in blood vessels and in tissues. First, we calibrated the system for cord blood oxygenation measurements by using a CO-Oximeter (gold standard). Then we performed validation in cord blood circulating through the catheters localized on the fetal side of an isolated placental lobule. Finally, the oxygenation measurements were performed in the perfused placental tissue. To increase or decrease blood oxygenation, we used infusion of a gas mixture of 95% O2 + 5% CO2 and 95% N2 + 5% CO2, respectively. In placental tissue, up to four cycles of changes in oxygenation were performed. The optoacoustically measured oxygenation in circulating cord blood and in placental lobule closely correlated with the actual oxygenation data measured by CO-Oximeter. We plan to further test the placental and cord blood oxygenation monitoring with optoacoustics in animal and clinical studies.

  11. Evaluation of the effect of myocardial segmentation errors on myocardial blood flow estimates from DCE-MRI

    NASA Astrophysics Data System (ADS)

    Biglands, J.; Magee, D.; Boyle, R.; Larghat, A.; Plein, S.; Radjenović, A.

    2011-04-01

    Quantitative analysis of cardiac dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) perfusion datasets is dependent on the drawing (manually or automatically) of myocardial contours. The required accuracy of these contours for myocardial blood flow (MBF) estimation is not well understood. This study investigates the relationship between myocardial contour errors and MBF errors. Myocardial contours were manually drawn on DCE-MRI perfusion datasets of healthy volunteers imaged in systole. Systematic and random contour errors were simulated using spline curves and the resulting errors in MBF were calculated. The degree of contour error was also evaluated by two recognized segmentation metrics. We derived contour error tolerances in terms of the maximum deviation (MD) a contour could deviate radially from the 'true' contour expressed as a fraction of each volunteer's mean myocardial width (MW). Significant MBF errors were avoided by setting tolerances of MD <= 0.4 MW, when considering the whole myocardium, MD <= 0.3 MW, when considering six radial segments, and MD <= 0.2 MW for further subdivision into endo- and epicardial regions, with the exception of the anteroseptal region, which required greater accuracy. None of the considered segmentation metrics correlated with MBF error; thus, both segmentation metrics and MBF errors should be used to evaluate contouring algorithms.

  12. Effects of graded doses of epinephrine on regional myocardial blood flow during cardiopulmonary resuscitation in swine

    SciTech Connect

    Brown, C.G.; Werman, H.A.; Davis, E.A.; Hobson, J.; Hamlin, R.L.

    1987-02-01

    Although epinephrine has been shown to improve myocardial blood flow during cardiopulmonary resuscitation (CPR), the effects of standard as well as larger doses of epinephrine on regional myocardial blood flow have not been examined. In this study we compared the effects of various doses of epinephrine on regional myocardial blood flow after a 10 min arrest in a swine preparation. Fifteen swine weighing greater than 15 kg each were instrumented for regional myocardial blood flow measurements with tracer microspheres. Regional blood flow was measured during normal sinus rhythm. After 10 min of ventricular fibrillation, CPR was begun and regional myocardial blood flow was determined. Animals were then randomly assigned to receive 0.02, 0.2, or 2.0 mg/kg epinephrine by peripheral injection. One minute after drug administration, regional myocardial blood flow measurements were repeated. The adjusted regional myocardial blood flows (ml/min/100 g) for animals given 0.02, 0.2, and 2.0 mg/kg epinephrine, respectively, were as follows: left atrium, 0.9, 67.4, and 58.8; right atrium, 0.3, 46.2, and 38.5; right ventricle, 0.7, 82.3, and 66.9; right interventricular septum, 1.7, 125.5, and 99.1; left interventricular septum, 2.8, 182.8, 109.5; mesointerventricular septum, 16.8, 142.2, and 79.2; left ventricular epicardium, 19.2, 98.5 and 108.7; left ventricular mesocardium, 22.8, 135.0, and 115.8; and left ventricular endocardium, 2.5, 176.1, and 132.9). All comparisons between the groups receiving 0.02 and 0.2 mg/kg epinephrine were statistically significant (p less than .05).

  13. Variance Estimation for Myocardial Blood Flow by Dynamic PET.

    PubMed

    Moody, Jonathan B; Murthy, Venkatesh L; Lee, Benjamin C; Corbett, James R; Ficaro, Edward P

    2015-11-01

    The estimation of myocardial blood flow (MBF) by (13)N-ammonia or (82)Rb dynamic PET typically relies on an empirically determined generalized Renkin-Crone equation to relate the kinetic parameter K1 to MBF. Because the Renkin-Crone equation defines MBF as an implicit function of K1, the MBF variance cannot be determined using standard error propagation techniques. To overcome this limitation, we derived novel analytical approximations that provide first- and second-order estimates of MBF variance in terms of the mean and variance of K1 and the Renkin-Crone parameters. The accuracy of the analytical expressions was validated by comparison with Monte Carlo simulations, and MBF variance was evaluated in clinical (82)Rb dynamic PET scans. For both (82)Rb and (13)N-ammonia, good agreement was observed between both (first- and second-order) analytical variance expressions and Monte Carlo simulations, with moderately better agreement for second-order estimates. The contribution of the Renkin-Crone relation to overall MBF uncertainty was found to be as high as 68% for (82)Rb and 35% for (13)N-ammonia. For clinical (82)Rb PET data, the conventional practice of neglecting the statistical uncertainty in the Renkin-Crone parameters resulted in underestimation of the coefficient of variation of global MBF and coronary flow reserve by 14-49%. Knowledge of MBF variance is essential for assessing the precision and reliability of MBF estimates. The form and statistical uncertainty in the empirical Renkin-Crone relation can make substantial contributions to the variance of MBF. The novel analytical variance expressions derived in this work enable direct estimation of MBF variance which includes this previously neglected contribution. PMID:25974932

  14. Skin Blood Perfusion and Oxygenation Colour Affect Perceived Human Health

    PubMed Central

    Stephen, Ian D.; Coetzee, Vinet; Law Smith, Miriam; Perrett, David I.

    2009-01-01

    Skin blood perfusion and oxygenation depends upon cardiovascular, hormonal and circulatory health in humans and provides socio-sexual signals of underlying physiology, dominance and reproductive status in some primates. We allowed participants to manipulate colour calibrated facial photographs along empirically-measured oxygenated and deoxygenated blood colour axes both separately and simultaneously, to optimise healthy appearance. Participants increased skin blood colour, particularly oxygenated, above basal levels to optimise healthy appearance. We show, therefore, that skin blood perfusion and oxygenation influence perceived health in a way that may be important to mate choice. PMID:19337378

  15. Blood storage device and method for oxygen removal

    DOEpatents

    Bitensky, Mark W.; Yoshida, Tatsuro

    2000-01-01

    The present invention relates to a storage device and method for the long-term storage of blood and, more particularly, to a blood storage device and method capable of removing oxygen from the stored blood and thereby prolonging the storage life of the deoxygenated blood.

  16. Design and optimization of a widely tunable semiconductor laser for blood oxygenation and blood flow measurements

    NASA Astrophysics Data System (ADS)

    Feng, Yafei; Deng, Haoyu; Song, Guangyi; He, Jian-Jun

    2014-11-01

    A method for measuring blood oxygenation and blood flow rate using a single widely tunable semiconductor laser is proposed and investigated. It is shown that a 700-nm-band tunable laser gives the highest sensitivity for blood oxygen measurement. The corresponding tunable laser is designed using the V-coupled cavity structure. The wavelength tuning range can reach 8 nm, which is sufficient for the blood oxygenation measurement in the 700-nm-band by using the Beer- Lambert law. In contrast to conventional blood oxygenation measurement method based on two LEDs, the laser can be used at the same time to measure the blood flow rate based on the Doppler principle.

  17. Improvement in Myocardial Function and Coronary Blood Flow in Ischemic Myocardium after Mannitol

    PubMed Central

    Willerson, James T.; Powell, Wm. John; Guiney, Timothy E.; Stark, James J.; Sanders, Charles A.; Leaf, Alexander

    1972-01-01

    The purpose of this study was to evaluate the effect of hyperosmolality on the performance of, and the collateral blood flow to, ischemic myocardium. The myocardial response to mannitol, a hyperosmolar agent which remains extracellular, was evaluated in anesthetized dogs. Mannitol was infused into the aortic roots of 31 isovolumic hearts and of 15 dogs on right heart bypass, before and during ischemia. Myocardial ischemia was produced by temporary ligation of either the proximal or mid-left anterior descending coronary artery. Mannitol significantly improved the depressed ventricular function curves which occurred with left anterior descending coronary artery occlusion. Mannitol also significantly lessened the S-T segment elevation (epicardial electrocardiogram) occurring during myocardial ischemia in the isovolumic hearts and this reduction was associated with significant increases in total coronary blood flow (P < 0.005) and with increased collateral coronary blood flow to the ischemia area (P < 0.005). Thus, increases in serum osmolality produced by mannitol result in the following beneficial changes during myocardial ischemia: (a) improved myocardial function, (b) reduced S-T segment elevation, (c) increased total coronary blood flow, and (d) increased collateral coronary blood flow. PMID:4640943

  18. Salutary effect of adjunctive intracoronary nicorandil administration on restoration of myocardial blood flow and functional improvement in patients with acute myocardial infarction.

    PubMed

    Sakata, Y; Kodama, K; Komamura, K; Lim, Y J; Ishikura, F; Hirayama, A; Kitakaze, M; Masuyama, T; Hori, M

    1997-06-01

    Salutary effect of nicorandil, a K+ adenosine triphosphate channel opener, on restoration of myocardial blood flow and functional improvement after coronary revascularization was investigated in 20 patients with first anterior acute myocardial infarction. Ten patients received intracoronary administration of nicorandil (2 mg) after coronary revascularization; the other 10 patients received coronary revascularization only and served as control subjects. Myocardial contrast echocardiography and two-dimensional echocardiography were performed to assess microvascular integrity and regional function in the infarcted area. Nicorandil improved peak contrast intensity ratio (p < 0.001), calculated as the ratio of peak contrast intensity in the infarcted and noninfarcted areas, indicating the restoration of myocardial blood flow to the infarcted myocardium. Regional wall motion improved more significantly in 1 month in patients who received nicorandil (p < 0.01). Thus our results suggested the usefulness of intracoronary nicorandil administration after coronary revascularization for restoring blood flow and functional improvement in patients with acute myocardial infarction. PMID:9200388

  19. Noncoronary Collateral Myocardial Blood Flow: The Human Heart’s Forgotten Blood Supply

    PubMed Central

    Picichè, Marco

    2015-01-01

    The “noncoronary collateral circulation” (NCCC) or “noncoronary collateral myocardial blood flow” (NCCMBF), reaches the heart through a micro-vascular network arising from the bronchial, esophageal, pericardial, diaphragmatic, and aortic arteries. The left and right internal thoracic arteries (ITAs) along with their collateral branches also serve as a source of NCCMBF-a feature seen in other mammals. Under certain circumstances the ITAs have a high potential for developing collateral branches. In the case of severe Leriche syndrome or with chronic obstruction of the abdominal aorta, the ITAs can serve as the main or even sole source of blood supply to the lower limbs. It is also possible for the ITAs to develop angiographically visible branches that directly connect with the coronary arteries. In ischemic conditions there is a functional, ischemia-reducing extracardiac coronary artery supply via natural ipsilateral ITA anastomosis. To date we know little about NCCMBF and its potential benefits in clinical applications, which makes this a challenging and intriguing field of research. This paper reviews all available data on noncoronary collateral blood supply to the human heart. PMID:27006713

  20. Case-Based Learning of Blood Oxygen Transport

    ERIC Educational Resources Information Center

    Cliff, William H.

    2006-01-01

    A case study about carbon monoxide poisoning was used help students gain a greater understanding of the physiology of oxygen transport by the blood. A review of student answers to the case questions showed that students can use the oxygen-hemoglobin dissociation curve to make meaningful determinations of oxygen uptake and delivery. However, the…

  1. Brain magnetic resonance imaging with contrast dependent on blood oxygenation

    SciTech Connect

    Ogawa, S.; Lee, T.M.; Kay, A.R.; Tank, D.W. )

    1990-12-01

    Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high yields, the authors demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complement other techniques that are attempting to provide position emission tomography-like measurements related to regional neural activity.

  2. Brain Magnetic Resonance Imaging with Contrast Dependent on Blood Oxygenation

    NASA Astrophysics Data System (ADS)

    Ogawa, S.; Lee, T. M.; Kay, A. R.; Tank, D. W.

    1990-12-01

    Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high fields, we demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complements other techniques that are attempting to provide positron emission tomography-like measurements related to regional neural activity.

  3. Rodent Working Heart Model for the Study of Myocardial Performance and Oxygen Consumption.

    PubMed

    DeWitt, Elizabeth S; Black, Katherine J; Kheir, John N

    2016-01-01

    Isolated working heart models have been used to understand the effects of loading conditions, heart rate and medications on myocardial performance in ways that cannot be accomplished in vivo. For example, inotropic medications commonly also affect preload and afterload, precluding load-independent assessments of their myocardial effects in vivo. Additionally, this model allows for sampling of coronary sinus effluent without contamination from systemic venous return, permitting assessment of myocardial oxygen consumption. Further, the advent of miniaturized pressure-volume catheters has allowed for the precise quantification of markers of both systolic and diastolic performance. We describe a model in which the left ventricle can be studied while performing both volume and pressure work under controlled conditions. In this technique, the heart and lungs of a Sprague-Dawley rat (weight 300-500 g) are removed en bloc under general anesthesia. The aorta is dissected free and cannulated for retrograde perfusion with oxygenated Krebs buffer. The pulmonary arteries and veins are ligated and the lungs removed from the preparation. The left atrium is then incised and cannulated using a separate venous cannula, attached to a preload block. Once this is determined to be leak-free, the left heart is loaded and retrograde perfusion stopped, creating the working heart model. The pulmonary artery is incised and cannulated for collection of coronary effluent and determination of myocardial oxygen consumption. A pressure-volume catheter is placed into the left ventricle either retrograde or through apical puncture. If desired, atrial pacing wires can be placed for more precise control of heart rate. This model allows for precise control of preload (using a left atrial pressure block), afterload (using an afterload block), heart rate (using pacing wires) and oxygen tension (using oxygen mixtures within the perfusate). PMID:27584550

  4. Role of reactive oxygen species in myocardial remodeling.

    PubMed

    Zhang, Min; Shah, Ajay M

    2007-03-01

    Adverse cardiac remodeling is a fundamental process in the progression to chronic heart failure. Although the mechanisms underlying cardiac remodeling are multi-factorial, a significant body of evidence points to the crucial roles of increased reactive oxygen species. This article reviews recent advances in delineating the different sources of production for reactive oxygen species (namely mitochondria, xanthine oxidase, uncoupled nitric oxide synthases, and NADPH oxidases) that may be involved in cardiac remodeling and the aspects of the remodeling process that they affect. These data could suggest new ways of targeting redox pathways for the prevention and treatment of adverse cardiac remodeling. PMID:17386182

  5. Blood oxygen saturation determined by transmission spectrophotometry of hemolyzed blood samples

    NASA Technical Reports Server (NTRS)

    Malik, W. M.

    1967-01-01

    Use of the Lambert-Beer Transmission Law determines blood oxygen saturation of hemolyzed blood samples. This simplified method is based on the difference in optical absorption properties of hemoglobin and oxyhemoglobin.

  6. Hyperpolarized (129)Xe T (1) in oxygenated and deoxygenated blood

    NASA Technical Reports Server (NTRS)

    Albert, M. S.; Balamore, D.; Kacher, D. F.; Venkatesh, A. K.; Jolesz, F. A.

    2000-01-01

    The viability of the new technique of hyperpolarized (129)Xe MRI (HypX-MRI) for imaging organs other than the lungs depends on whether the spin-lattice relaxation time, T(1), of (129)Xe is sufficiently long in the blood. In previous experiments by the authors, the T(1) was found to be strongly dependent upon the oxygenation of the blood, with T(1) increasing from about 3 s in deoxygenated samples to about 10 s in oxygenated samples. Contrarily, Tseng et al. (J. Magn. Reson. 1997; 126: 79-86) reported extremely long T(1) values deduced from an indirect experiment in which hyperpolarized (129)Xe was used to create a 'blood-foam'. They found that oxygenation decreased T(1). Pivotal to their experiment is the continual and rapid exchange of hyperpolarized (129)Xe between the gas phase (within blood-foam bubbles) and the dissolved phase (in the skin of the bubbles); this necessitated a complicated analysis to extract the T(1) of (129)Xe in blood. In the present study, the experimental design minimizes gas exchange after the initial bolus of hyperpolarized (129)Xe has been bubbled through the sample. This study confirms that oxygenation increases the T(1) of (129)Xe in blood, from about 4 s in freshly drawn venous blood, to about 13 s in blood oxygenated to arterial levels, and also shifts the red blood cell resonance to higher frequency. Copyright 2000 John Wiley & Sons, Ltd. Abbreviations used BOLD blood oxygen level dependent NOE nuclear overhouses effect PO(2) oxygen partial pressure RBC red blood cells RF radio frequency SNR signal-to-noise ratio.

  7. Non-invasive measurement of blood oxygen levels.

    PubMed

    Beyerl, D

    1982-05-01

    Comparison of transcutaneous (TC) monitoring of blood oxygen levels to arterial blood gas analyses was made on patients at rest with room air, during exercise, and at rest with oxygen. Three different transcutaneous monitors were evaluated: Novametrix TC O2 Mette, Biochem Sensomat, and Radiometer TC M1. The Hewlett-Packard ear oximeter for measuring oxygen saturation was also compared to oxygen saturation values calculated on the Severinghaus slide rule. Using at least one measured PO2 as a baseline, either TC monitoring or ear oximetry were valuable tools in monitoring pulmonary function. PMID:7102718

  8. Influence of myocardial substrate utilization on the oxygen consumption of the heart.

    PubMed

    Kahles, H; Hellige, G; Hunneman, D H; Mezger, V A; Bretschneider, H J

    1982-04-01

    The effect of changing myocardial metabolism from predominantly lipid to predominantly carbohydrate utilization on myocardial oxygen consumption (MVO2) was studied in 10 closed-chest dogs. Oxygen saving potency of different metabolic interventions was quantified over a wide hemodynamic range by comparing the directly determined MVO2 with the hemodynamic parameter total left ventricular energy demand (Et), which correlates closely under control conditions with MVO2 (r = 0.98). Stimulation of carbohydrate metabolism by addition of glucose and beta-pyridyl carbinol or by activation of pyruvate dehydrogenase with dichloroacetate (DCA) shifted the cardiac respiratory quotient during beta-stimulation from 0.73 to 1.00 and 0.89, respectively, the nonesterified fatty acid/albumin ratio decreased from 4.0 to 0.5, or remained unchanged with DCA, and MVO2 was reduced by 25 and 16%, respectively. Therapeutic approaches aimed at decreasing MVO2 by changing substrate utilization are discussed. PMID:7083652

  9. Quantitative myocardial blood flow with Rubidium-82 PET: a clinical perspective.

    PubMed

    Hagemann, Christoffer E; Ghotbi, Adam A; Kjær, Andreas; Hasbak, Philip

    2015-01-01

    Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1) identification of the extent of a multivessel coronary artery disease (CAD) burden, 2) patients with balanced 3-vessel CAD, 3) patients with subclinical CAD, and 4) patients with regional flow variance, despite of a high global MFR. A more accurate assessment of the ischemic burden in patients with intermediate pretest probability of CAD can support the clinical decision-making in treatment of CAD patients as a complementary tool to the invasive coronary angiography (CAG). Recently, several studies have proven Rubidium-82 ((82)Rb) PET's long-term prognostic value by a significant association between compromised global MFR and major adverse cardiovascular events (MACE), and together with new diagnostic possibilities from measuring the longitudinal myocardial perfusion gradient, cardiac (82)Rb PET faces a promising clinical future. This article reviews current evidence on quantitative (82)Rb PET's ability to diagnose and risk stratify CAD patients, while assessing the potential of the modality in clinical practice. PMID:26550537

  10. Quantitative myocardial blood flow with Rubidium-82 PET: a clinical perspective

    PubMed Central

    Hagemann, Christoffer E; Ghotbi, Adam A; Kjær, Andreas; Hasbak, Philip

    2015-01-01

    Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1) identification of the extent of a multivessel coronary artery disease (CAD) burden, 2) patients with balanced 3-vessel CAD, 3) patients with subclinical CAD, and 4) patients with regional flow variance, despite of a high global MFR. A more accurate assessment of the ischemic burden in patients with intermediate pretest probability of CAD can support the clinical decision-making in treatment of CAD patients as a complementary tool to the invasive coronary angiography (CAG). Recently, several studies have proven Rubidium-82 (82Rb) PET’s long-term prognostic value by a significant association between compromised global MFR and major adverse cardiovascular events (MACE), and together with new diagnostic possibilities from measuring the longitudinal myocardial perfusion gradient, cardiac 82Rb PET faces a promising clinical future. This article reviews current evidence on quantitative 82Rb PET’s ability to diagnose and risk stratify CAD patients, while assessing the potential of the modality in clinical practice. PMID:26550537

  11. Radionuclide Tracers for Myocardial Perfusion Imaging and Blood Flow Quantification.

    PubMed

    deKemp, Robert A; Renaud, Jennifer M; Klein, Ran; Beanlands, Rob S B

    2016-02-01

    Myocardial perfusion imaging is performed most commonly using Tc-99m-sestamibi or tetrofosmin SPECT as well as Rb-82-rubidium or N-13-ammonia PET. Diseased-to-normal tissue contrast is determined by the tracer retention fraction, which decreases nonlinearly with flow. Reduced tissue perfusion results in reduced tracer retention, but the severity of perfusion defects is typically underestimated by 20% to 40%. Compared to SPECT, retention of the PET tracers is more linearly related to flow, and therefore, the perfusion defects are measured more accurately using N-13-ammonia or Rb-82. PMID:26590778

  12. Determination of the Role of Oxygen in Suspected Acute Myocardial Infarction by Biomarkers

    ClinicalTrials.gov

    2016-01-25

    Acute Myocardial Infarction (AMI); Acute Coronary Syndrome (ACS); ST Elevation (STEMI) Myocardial Infarction; Ischemic Reperfusion Injury; Non-ST Elevation (NSTEMI) Myocardial Infarction; Angina, Unstable

  13. Patient-specific coronary artery blood flow simulation using myocardial volume partitioning

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Hwan; Kang, Dongwoo; Kang, Nahyup; Kim, Ji-Yeon; Lee, Hyong-Euk; Kim, James D. K.

    2013-03-01

    Using computational simulation, we can analyze cardiovascular disease in non-invasive and quantitative manners. More specifically, computational modeling and simulation technology has enabled us to analyze functional aspect such as blood flow, as well as anatomical aspect such as stenosis, from medical images without invasive measurements. Note that the simplest ways to perform blood flow simulation is to apply patient-specific coronary anatomy with other average-valued properties; in this case, however, such conditions cannot fully reflect accurate physiological properties of patients. To resolve this limitation, we present a new patient-specific coronary blood flow simulation method by myocardial volume partitioning considering artery/myocardium structural correspondence. We focus on that blood supply is closely related to the mass of each myocardial segment corresponding to the artery. Therefore, we applied this concept for setting-up simulation conditions in the way to consider many patient-specific features as possible from medical image: First, we segmented coronary arteries and myocardium separately from cardiac CT; then the myocardium is partitioned into multiple regions based on coronary vasculature. The myocardial mass and required blood mass for each artery are estimated by converting myocardial volume fraction. Finally, the required blood mass is used as boundary conditions for each artery outlet, with given average aortic blood flow rate and pressure. To show effectiveness of the proposed method, fractional flow reserve (FFR) by simulation using CT image has been compared with invasive FFR measurement of real patient data, and as a result, 77% of accuracy has been obtained.

  14. Noninvasive optoacoustic monitoring of cerebral venous blood oxygenation in newborns

    NASA Astrophysics Data System (ADS)

    Petrov, Irene Y.; Wynne, Karon E.; Petrov, Yuriy; Esenaliev, Rinat O.; Richardson, C. Joan; Prough, Donald S.

    2012-02-01

    Cerebral ischemia after birth and during labor is a major cause of death and severe complications such as cerebral palsy. In the USA alone, cerebral palsy results in permanent disability of 10,000 newborns per year and approximately 500,000 of the total population. Currently, no technology is capable of direct monitoring of cerebral oxygenation in newborns. This study proposes the use of an optoacoustic technique for noninvasive cerebral ischemia monitoring by probing the superior sagittal sinus (SSS), a large central cerebral vein. We developed and built a multi-wavelength, near-infrared optoacoustic system suitable for noninvasive monitoring of cerebral ischemia in newborns with normal weight (NBW), low birth-weight (LBW, 1500 - 2499 g) and very low birth-weight (VLBW, < 1500 g). The system was capable of detecting SSS signals through the open anterior and posterior fontanelles as well as through the skull. We tested the system in NBW, LBW, and VLBW newborns (weight range: from 675 g to 3,000 g) admitted to the neonatal intensive care unit. We performed single and continuous measurements of the SSS blood oxygenation. The data acquisition, processing and analysis software developed by our group provided real-time, absolute SSS blood oxygenation measurements. The SSS blood oxygenation ranged from 60% to 80%. Optoacoustic monitoring of the SSS blood oxygenation provides valuable information because adequate cerebral oxygenation would suggest that no therapy was necessary; conversely, evidence of cerebral ischemia would prompt therapy to increase cerebral blood flow.

  15. Myocardial Reloading after Extracorporeal Membrane Oxygenation Alters Substrate Metabolism While Promoting Protein Synthesis

    SciTech Connect

    Kajimoto, Masaki; Priddy, Colleen M.; Ledee, Dolena; Xu, Chun; Isern, Nancy G.; Olson, Aaron; Des Rosiers, Christine; Portman, Michael A.

    2013-08-19

    Extracorporeal membrane oxygenation (ECMO) unloads the heart providing a bridge to recovery in children after myocardial stunning. Mortality after ECMO remains high.Cardiac substrate and amino acid requirements upon weaning are unknown and may impact recovery. We assessed the hypothesis that ventricular reloading modulates both substrate entry into the citric acid cycle (CAC) and myocardial protein synthesis. Fourteen immature piglets (7.8-15.6 kg) were separated into 2 groups based on ventricular loading status: 8 hour-ECMO (UNLOAD) and post-wean from ECMO (RELOAD). We infused [2-13C]-pyruvate as an oxidative substrate and [13C6]-L-leucine, as a tracer of amino acid oxidation and protein synthesis into the coronary artery. RELOAD showed marked elevations in myocardial oxygen consumption above baseline and UNLOAD. Pyruvate uptake was markedly increased though RELOAD decreased pyruvate contribution to oxidative CAC metabolism.RELOAD also increased absolute concentrations of all CAC intermediates, while maintaining or increasing 13C-molar percent enrichment. RELOAD also significantly increased cardiac fractional protein synthesis rates by >70% over UNLOAD. Conclusions: RELOAD produced high energy metabolic requirement and rebound protein synthesis. Relative pyruvate decarboxylation decreased with RELOAD while promoting anaplerotic pyruvate carboxylation and amino acid incorporation into protein rather than to the CAC for oxidation. These perturbations may serve as therapeutic targets to improve contractile function after ECMO.

  16. Acute Myocardial Infarction Complicated by Cardiogenic Shock: An Algorithm-Based Extracorporeal Membrane Oxygenation Program Can Improve Clinical Outcomes.

    PubMed

    Unai, Shinya; Tanaka, Daizo; Ruggiero, Nicholas; Hirose, Hitoshi; Cavarocchi, Nicholas C

    2016-03-01

    Extracorporeal membrane oxygenation (ECMO) in our institution resulted in near total mortality prior to the establishment of an algorithm-based program in July 2010. We hypothesized that an algorithm-based ECMO program improves the outcome of patients with acute myocardial infarction complicated with cardiogenic shock. Between March 2003 and July 2013, 29 patients underwent emergent catheterization for acute myocardial infarction due to left main or proximal left anterior descending artery occlusion complicated with cardiogenic shock (defined as systolic blood pressure <90 mm Hg despite multiple inotropes, with or without intra-aortic balloon pump, lactic acidosis). Of 29 patients, 15 patients were treated before July 2010 (Group 1, old program), and 14 patients were treated after July 2010 (Group 2, new program). There were no significant differences in the baseline characteristics, including age, sex, coronary risk factors, and left ventricular ejection fraction between the two groups. Cardiopulmonary resuscitation prior to ECMO was performed in two cases (13%) in Group 1 and four cases (29%) in Group 2. ECMO support was performed in one case (6.7%) in Group 1 and six cases (43%) in Group 2. The 30-day survival of Group 1 versus Group 2 was 40 versus 79% (P = 0.03), and 1-year survival rate was 20 versus 56% (P = 0.01). The survival rate for patients who underwent ECMO was 0% in Group 1 versus 83% in Group 2 (P = 0.09). In Group 2, the mean duration on ECMO was 9.8 ± 5.9 days. Of the six patients who required ECMO in Group 2, 100% were successfully weaned off ECMO or were bridged to ventricular assist device implantation. Initiation of an algorithm-based ECMO program improved the outcomes in patients with acute myocardial infarction complicated by cardiogenic shock. PMID:26148217

  17. Altered Gene Expression Pattern in Peripheral Blood Mononuclear Cells in Patients with Acute Myocardial Infarction

    PubMed Central

    Kiliszek, Marek; Burzynska, Beata; Michalak, Marcin; Gora, Monika; Winkler, Aleksandra; Maciejak, Agata; Leszczynska, Agata; Gajda, Ewa; Kochanowski, Janusz; Opolski, Grzegorz

    2012-01-01

    Background Despite a substantial progress in diagnosis and therapy, acute myocardial infarction (MI) is a major cause of mortality in the general population. A novel insight into the pathophysiology of myocardial infarction obtained by studying gene expression should help to discover novel biomarkers of MI and to suggest novel strategies of therapy. The aim of our study was to establish gene expression patterns in leukocytes from acute myocardial infarction patients. Methods and Results Twenty-eight patients with ST-segment elevation myocardial infarction (STEMI) were included. The blood was collected on the 1st day of myocardial infarction, after 4–6 days, and after 6 months. Control group comprised 14 patients with stable coronary artery disease, without history of myocardial infarction. Gene expression analysis was performed with Affymetrix Human Gene 1.0 ST microarrays and GCS3000 TG system. Lists of genes showing altered expression levels (fold change >1.5, p<0.05) were submitted to Ingenuity Pathway Analysis. Gene lists from each group were examined for canonical pathways and molecular and cellular functions. Comparing acute phase of MI with the same patients after 6 months (stable phase) and with control group we found 24 genes with changed expression. In canonical analysis three pathways were highlighted: signaling of PPAR (peroxisome proliferator-activated receptor), IL-10 and IL-6 (interleukin 10 and 6). Conclusions In the acute phase of STEMI, dozens of genes from several pathways linked with lipid/glucose metabolism, platelet function and atherosclerotic plaque stability show altered expression. Up-regulation of SOCS3 and FAM20 genes in the first days of myocardial infarction is observed in the vast majority of patients. PMID:23185530

  18. Myocardial imaging in dogs treated with grisorixin: relationship between thallium-201 uptake and coronary blood flow

    SciTech Connect

    Moins, N.; Gachon, P.; Maublant, J.

    1982-04-01

    Thallium-201 myocardial imaging was performed in dogs after pretreatment with grisorixin, which appeared to increase the myocardial uptake of Tl-201. This effect of grisorixin was found to be dose dependent, with an optimal dose of 60 ..mu..g/kg. The myocardial-to-background ratio, which was 1.92 in the control dogs, rose to 4.45. The increase in the absolute myocardial uptake was demonstrated in guinea pigs that received Tl-201 after similar pretreatment with grisorixin. In the animals treated with 500 ..mu..g/kg, the uptake of Tl-201 by the heart was 35% over the control value. With 60 ..mu..g/kg grisorixin, the coronary blood flow increased from 40 to 176 ml/min 5 min after the injection. This dose, optimal for imaging, induced the maximum vasodilator effect with only a very slight concomitant increase in the left-ventricular pressure and myocardial contractility. Above 60 ..mu..g/kg, grisorixin appeared to be a potent inotropic agent, whereas below this dose it showed only coronary vasodilator properties. Some evidence for an inophore effect of this compound was found in dogs pretreated with 60 ..mu..g/kg. In these the radionuclide was injected when the coronary vasodilation had become insignificant, but a significant improvement of the M/B ratio was still evident.

  19. Precision and accuracy of clinical quantification of myocardial blood flow by dynamic PET: A technical perspective.

    PubMed

    Moody, Jonathan B; Lee, Benjamin C; Corbett, James R; Ficaro, Edward P; Murthy, Venkatesh L

    2015-10-01

    A number of exciting advances in PET/CT technology and improvements in methodology have recently converged to enhance the feasibility of routine clinical quantification of myocardial blood flow and flow reserve. Recent promising clinical results are pointing toward an important role for myocardial blood flow in the care of patients. Absolute blood flow quantification can be a powerful clinical tool, but its utility will depend on maintaining precision and accuracy in the face of numerous potential sources of methodological errors. Here we review recent data and highlight the impact of PET instrumentation, image reconstruction, and quantification methods, and we emphasize (82)Rb cardiac PET which currently has the widest clinical application. It will be apparent that more data are needed, particularly in relation to newer PET technologies, as well as clinical standardization of PET protocols and methods. We provide recommendations for the methodological factors considered here. At present, myocardial flow reserve appears to be remarkably robust to various methodological errors; however, with greater attention to and more detailed understanding of these sources of error, the clinical benefits of stress-only blood flow measurement may eventually be more fully realized. PMID:25868451

  20. Assessment of regional myocardial and renal blood flow with copper-PTSM and positron emission tomography.

    PubMed

    Shelton, M E; Green, M A; Mathias, C J; Welch, M J; Bergmann, S R

    1990-09-01

    We recently demonstrated in isolated, perfused hearts that radiolabeled pyruvaldehyde bis(N4-methylthiosemicarbazonato)copper(II) (Cu-PTSM) is well extracted throughout a range of conditions including ischemia, hypoxia, and hyperemia. Once extracted, binding of radioactivity by the isolated heart was essentially irreversible, giving this tracer microspherelike qualities. Because Cu-PTSM can be readily prepared with the generator-produced positron-emitting copper 62 and other gamma- or positron-emitting copper radionuclides, we evaluated its usefulness for measuring regional myocardial and renal blood flow in vivo in intact dogs at rest, after ischemia, or after coronary hyperemia was induced by intravenous administration of dipyridamole. After intravenous administration of radiolabeled Cu-PTSM, the tracer cleared rapidly from the blood. Myocardial uptake of single photon-emitting 67Cu-labeled Cu-PTSM was measured directly in myocardial samples 15 minutes after tracer administration, and it increased proportionally with blood flow throughout the flow range (estimated concomitantly with radiolabeled microspheres) of 0.0-6.0 ml/g/min (n = 340 samples from 17 dogs, r = 0.99, Ycopper radioactivity = 85Xmicrosphere flow -7 chi 2 + 17). Renal uptake of radiolabeled Cu-PTSM was also proportional to blood flow. Positron emission tomography was performed in four intact dogs after intravenous administration of 64Cu-labeled Cu-PTSM (19% positron decay, t1/2 = 12.8 hours). High-quality images of heart and kidney were obtained. Accordingly, radiolabeled Cu-PTSM should be a useful, generator-produced tracer for estimating regional myocardial and renal blood flow with positron emission tomography. PMID:2394015

  1. Myocardial perfusion and oxygenation are impaired during stress in severe aortic stenosis and correlate with impaired energetics and subclinical left ventricular dysfunction

    PubMed Central

    2014-01-01

    Background Left ventricular (LV) hypertrophy in aortic stenosis (AS) is characterized by reduced myocardial perfusion reserve due to coronary microvascular dysfunction. However, whether this hypoperfusion leads to tissue deoxygenation is unknown. We aimed to assess myocardial oxygenation in severe AS without obstructive coronary artery disease, and to investigate its association with myocardial energetics and function. Methods Twenty-eight patients with isolated severe AS and 15 controls underwent cardiovascular magnetic resonance (CMR) for assessment of perfusion (myocardial perfusion reserve index-MPRI) and oxygenation (blood-oxygen level dependent-BOLD signal intensity-SI change) during adenosine stress. LV circumferential strain and phosphocreatine/adenosine triphosphate (PCr/ATP) ratios were assessed using tagging CMR and 31P MR spectroscopy, respectively. Results AS patients had reduced MPRI (1.1 ± 0.3 vs. controls 1.7 ± 0.3, p < 0.001) and BOLD SI change during stress (5.1 ± 8.9% vs. controls 18.2 ± 10.1%, p = 0.001), as well as reduced PCr/ATP (1.45 ± 0.21 vs. 2.00 ± 0.25, p < 0.001) and LV strain (−16.4 ± 2.7% vs. controls −21.3 ± 1.9%, p < 0.001). Both perfusion reserve and oxygenation showed positive correlations with energetics and LV strain. Furthermore, impaired energetics correlated with reduced strain. Eight months post aortic valve replacement (AVR) (n = 14), perfusion (MPRI 1.6 ± 0.5), oxygenation (BOLD SI change 15.6 ± 7.0%), energetics (PCr/ATP 1.86 ± 0.48) and circumferential strain (−19.4 ± 2.5%) improved significantly. Conclusions Severe AS is characterized by impaired perfusion reserve and oxygenation which are related to the degree of derangement in energetics and associated LV dysfunction. These changes are reversible on relief of pressure overload and hypertrophy regression. Strategies aimed at improving oxygen demand–supply balance to preserve myocardial

  2. Inner retinal metabolic rate of oxygen by oxygen tension and blood flow imaging in rat

    PubMed Central

    Wanek, Justin; Teng, Pang-yu; Albers, John; Blair, Norman P.; Shahidi, Mahnaz

    2011-01-01

    Abstract The metabolic function of inner retinal cells relies on the availability of nutrients and oxygen that are supplied by the retinal circulation. Assessment of retinal tissue vitality and function requires knowledge of both the rate of oxygen delivery and consumption. The purpose of the current study is to report a novel technique for assessment of the inner retinal metabolic rate of oxygen (MO2) by combined measurements of retinal blood flow and vascular oxygen tension (PO2) in rat. The application of this technology has the potential to broaden knowledge of retinal oxygen dynamics and advance understanding of disease pathophysiology. PMID:21991548

  3. Improved myocardial oxygen utilization following propranolol infusion in adolescents with postburn hypermetabolism.

    PubMed

    Minifee, P K; Barrow, R E; Abston, S; Desai, M; Herndon, D N

    1989-08-01

    The purpose of this study was to determine if propranolol (0.5 mg/kg and 1 mg/kg), administered intravenously (IV) at the height of the postburn hypermetabolic response, would decrease myocardial oxygen requirements, without adversely affecting overall oxygen delivery or total body oxygen consumption. To test this hypothesis, six nonseptic patients age 17 +/- 3 years with burns over 82% +/- 11% total body surface area were given propranolol with continuous hemodynamic monitoring. Propranolol was administered to these patients 20 +/- 15 days postburn. Two clinically derived indices of myocardial oxygen consumption, pressure-work index (PWI) and rate-pressure product (RPP), were used to estimate the energy expenditure of the working heart. Both PWI and RPP were significantly decreased from baseline after 0.5 mg/kg propranolol, 31% for PWI (P less than .001) and 30% for RPP (P less than .01). Similarly, a decrease from baseline was seen after 1.0 mg/kg propranolol, 32% for PWI (P less than .001) and 35% for RPP (P less than .01). Cardiac index (L/min/m2) demonstrated no significant change [7.4 +/- 1.1 (prepropranolol), 6.5 +/- 1.3 (after 0.5 mg/kg propranolol), and 6.8 +/- 1.0 (after 1.0 mg/kg propranolol)] and exceeded the upper limits of normal (hyperdynamic state) throughout the study. Oxygen delivery index (962 +/- 209 mL/min/m2) and oxygen consumption indices [(254 +/- 78 mL/min/m2 by Fick method and 236 +/- 78 mL/min/m2 by inspired and expired gases)] were elevated at baseline and unaffected by propranolol. The decrease in PWI and RPP was achieved mainly by propranolol's effect to lower both heart rate and BP.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2769550

  4. Adaptation of myocardial blood flow to increased metabolic demand is not dependent on endothelial vasodilators in the rat heart.

    PubMed Central

    Tiefenbacher, C. P.; Tillmanns, H.; Niroomand, F.; Zimmermann, R.; Kübler, W.

    1997-01-01

    OBJECTIVE: To investigate the role of endothelial vasodilating factors in adaptation of myocardial blood flow to increased metabolic demands. DESIGN: Alterations in the effects of endothelium dependent (acetylcholine) and independent (sodium nitroprusside) vasodilators and the beta 1 receptor agonist dobutamine were studied after inhibition of endothelium derived relaxing factor (EDRF) with L-NG-nitro-arginine methyl ester (L-NAME), prostanoid synthesis with indomethacin, and ATP sensitive potassium channels with glibenclamide. EXPERIMENTAL ANIMALS: Female Wistar rats, in situ perfused heart. MAIN OUTCOME MEASURES: Myocardial blood flow (H2 clearance); systolic fractional thickening (pulsed Doppler); mean arterial blood pressure. RESULTS: L-NAME reduced myocardial blood flow by 58 (12)% (mean (SD), P < 0.001) and systolic thickening fraction (FT) by 36 (9)% (P < 0.05). These effects were significantly reversed by administration of L-arginine but not D-arginine. Pretreatment with L-NAME inhibited the increase in myocardial blood flow caused by acetylcholine (control: +42 (9)%; L-NAME: -29 (7)%, P < 0.001) but did not affect the increase in myocardial blood flow caused by sodium nitroprusside (control: +44 (5)%; L-NAME: +34 (10)%, NS). Pretreatment with L-NAME did not change the effect of dobutamine on myocardial blood flow (+61 (3)%) and FT (+32 (8)%) compared with baseline values (P < 0.001). Neither pretreatment with indomethacin nor with glibenclamide reduced the dobutamine induced increase in myocardial blood flow. CONCLUSIONS: Inhibition of EDRF, prostanoid synthesis, and ATP sensitive potassium channels did not reduce the vasodilator reserve during increased metabolic demands induced by beta 1 adrenergic stimulation. Therefore, adaptation of myocardial blood flow to increased metabolic demands is independent of endothelial relaxing factors in the rat heart. PMID:9068398

  5. The acute effects of nicotine, tobacco smoke and carbon monoxide on myocardial oxygen tension in the anaesthetized cat

    PubMed Central

    Rink, Richard D.

    1978-01-01

    1 The acute effects of nicotine, tobacco smoke, and carbon monoxide on myocardial oxygen tension (MPo2) were estimated amperometrically in 33 anaesthetized open-chest cats with a glass-insulated 25 μm platinum cathode within a 22-gauge needle implanted in the left ventricular wall. 2 MPo2 was 1.6-60 mmHg (mean 23.5 mmHg) when arterial Po2 was >80 mmHg. Sequential intravenous infusions of nicotine (2-3 μg/kg every 45 s) or intracheal puffs (3-5 ml) of tobacco smoke commonly produced transitory increases (25-35 mmHg) of arterial pressure and 4-6 mmHg increments of MPo2. Intratracheal puffs (5 ml) of 5% carbon monoxide sufficient to increase carboxyhaemoglobin from 0.8 to 1.5% to 4-7% had no effect on arterial Po2 or blood pressure but typically decreased MPo2 by approximately 1-4 mmHg. Augmentation of MPo2 often succeeded carbon monoxide administration. 3 Arterial hypoxia (arterial Po2 < 60 mmHg) reduced mean MPo2 to 14.4 mmHg but anoxic levels were not observed. Pressor responses to nicotine and tobacco smoke were accompanied by small increases (usually 1-3 mmHg) of MPo2. Puffs of 5% carbon monoxide had less effect than during normoxia. Locations of low MPo2 (<10 mmHg) were unaffected as carboxyhaemoglobin was raised to 7-11% during hypoxaemia. 4 It is concluded that nicotine and tobacco smoke cause augmentation of myocardial oxygen supply, even during moderate hypoxaemia. By contrast, smoking dosages of carbon monoxide have the potential of producing a small reduction of MPo2 during normoxia, but the effect is negligible during moderate hypoxaemia. PMID:656704

  6. Relationship between myocardial flow reserve by oxygen-15 water positron emission tomography in the subacute phase of myocardial infarction and left ventricular remodeling in the chronic phase.

    PubMed

    Ohara, Minako; Yukiiri, Kazushi; Masugata, Hisashi; Iwado, Yasuyoshi; Takinami, Hiroyuki; Nishiyama, Yoshihiro; Ohkawa, Motoomi; Senda, Shoichi; Ohmori, Koji; Kohno, Masakazu

    2008-07-01

    The purposes of this study were to examine the effects of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) on myocardial flow reserve in patients with acute myocardial infarction (AMI) in the subacute phase using oxygen-15 positron emission tomography (PET) and to elucidate the relationship between the myocardial flow reserve and remodeling in the chronic phase. Sixty patients who had been treated with coronary angioplasty within 12 h after the onset of AMI were enrolled. Patients were divided into an enalapril (ACEI) group and a candesartan (ARB) group. The myocardial flow reserve was measured by oxygen-15 water PET in the subacute phase from the 20th to the 30th day after the onset of AMI. Left ventriculography was performed to measure the left ventricular ejection fraction in the chronic phase about 6 months after the onset. Ten patients (33%) in the enalapril group and 4 patients (13%) in the candesartan group stopped taking their respective medications within a few days of starting, because of side effects such as cough or hypotension. Thus, the prevalence of medication intolerance was higher in the enalapril group. The myocardial flow reserve in the subacute phase and the left ventricular ejection fraction in the chronic phase were lower in the enalapril group (2.08 +/- 0.30 and 42 +/- 6%) than in the candesartan group (2.25 +/- 0.20 and 49 +/- 5%) (p < 0.05). The myocardial flow reserve significantly correlated with the left ventricular ejection fraction in all patients (r = 0.45, p < 0.01). The myocardial flow reserve assessed by PET in the subacute phase after AMI was found to be related to left ventricular remodeling in the chronic phase. PMID:18957800

  7. Preoxygenated hemoglobin-based oxygen carrier HBOC-201 annihilates myocardial ischemia during brief coronary artery occlusion in pigs.

    PubMed

    Te Lintel Hekkert, Maaike; Dubé, Gregory P; Regar, Evelyn; de Boer, Martine; Vranckx, Pascal; van der Giessen, Wim J; Serruys, Patrick W; Duncker, Dirk J

    2010-03-01

    Because of their ability to perfuse remote regions and deliver oxygen, hemoglobin-based oxygen carriers (HBOCs) may be considered in the treatment of several ischemic conditions such as acute coronary syndromes or high-risk percutaneous intervention. Here we studied the effects of intracoronary infusion of ex vivo preoxygenated HBOC-201 during brief total coronary artery occlusion (CAOs) on myocardial oxygenation and left ventricular (LV) function in a large animal model and investigated the influence of HBOC-201 temperature and infusion rate on these effects. Thirteen open-chest anesthetized swine were instrumented for measurement of global and regional LV function and metabolism. CAOs were induced by inflating an intracoronary balloon catheter; preoxygenated HBOC-201 (12 g/dL) was infused distally through the central lumen of the balloon catheter. Animals underwent consecutive 3-min CAOs interspersed by 30 min of reperfusion, accompanied by different HBOC-201 infusion rates (0, 15, 23, 30, 40, and 50 ml/min) and/or two infusion temperatures (18 degrees C or 37 degrees C) in random order. CAO elicited immediate loss of systolic shortening (SS) in the ischemic region (19 +/- 1% at baseline vs. -3 +/- 2% at end of CAO), resulting in decreases in maximum rate of rise in LV pressure (15 +/- 5%) and stroke volume (12 +/- 4%; all P < 0.05). Balloon deflation resulted in marked coronary reactive hyperemia (to 472 +/- 74% of baseline), increases in coronary venous concentrations of adenosine + inosine (to 218 +/- 26% of baseline; both P < 0.05) and rapid restoration of SS toward baseline. HBOC-201 ameliorated the CAO-induced changes in SS, stroke volume, reactive hyperemia, and coronary venous adenosine + inosine. The effects were temperature and flow dependent with full preservation of SS at 50 ml/min HBOC-201 of 37 degrees C. In conclusion, intracoronary preoxygenated HBOC-201 preserved myocardial oxygenation and LV function in swine during CAO in a dose- and

  8. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  9. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  10. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  11. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  12. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  13. Autonomic control of cardiac function and myocardial oxygen consumption during hypoxic hypoxia.

    NASA Technical Reports Server (NTRS)

    Erickson, H. H.; Stone, H. L.

    1972-01-01

    Investigation in 19 conscious dogs of the importance of the sympathetic nervous system in the coronary and cardiac response to altitude (hypoxic) hypoxia. Beta-adrenergic blockade was used to minimize the cardiac effect associated with sympathetic receptors. It is shown that the autonomic nervous system, and particularly the sympathetic nervous system, is responsible for the increase in ventricular function and myocardial oxygen consumption that occurs during hypoxia. Minimizing this response through appropriate conditioning and training may improve the operating efficiency of the heart and reduce the hazard of hypoxia and other environmental stresses, such as acceleration, which are encountered in advanced aircraft systems.

  14. [New Developments in CKD-MBD. Imbalance of myocardial oxygen supply and demand in CKD patients with cardiovascular calcification].

    PubMed

    Joki, Nobuhiko; Hayashi, Toshihide

    2014-12-01

    Cardiovascular calcification is well known as an important factor for poor prognosis in CKD patients. It is not well understood why even no significant narrowing the presence of vascular calcification have a great impact for tissue ischemia, especially myocardial ischemia. Many studies have demonstrated that the presence of coronary calcification, aortic calcification, arterial calcification and aortic valve calcification is susceptible to induce an imbalance of myocardial oxygen supply and demand. PMID:25423922

  15. N-13 ammonia as an indicator of myocardial blood flow. [Dogs

    SciTech Connect

    Schelbert, H.R.; Phelps, M.E.; Huang, S.C.; MacDonald, N.S.; Hansen, H.; Selin, C.; Kuhl, D.E.

    1981-06-01

    We have characterized N-13 ammonia as a myocardial blood flow imaging agent suitable for positron-emission computed tomography. However, the mechanisms of uptake and retention of this agent in myocardium are not known, and effects of altered metabolism were not considered. Therefore, we studied the uptake and retention of N-13 ammonia in myocardium under various hemodynamic and metabolic conditions in open-chest dogs. N-13 ammonia was extracted nearly 100% during its initial capillary transit, followed by metabolic trapping that competed with flow-dependent back diffusion. At control flows, the first capillary transit extraction fraction (E) of N-13 ammonia averaged 0.82 +- 0.06. Inhibition of glutamine synthetase with L-methionine sulfoximine impaired metabolic trapping of N-13 ammonia and implicates te glutamic acid-glutamine reaction as the primary mechanism for ammonia fixation. Blood flow and metabolic trapping are the primary determinants of myocardial uptake and retention of N-13 ammonia. The relative constancy of metabolic trapping over a wide range of hemodynamic and metabolic conditions demonstrates the value of N-13 ammonia as a myocardial blood flow imaging agent.

  16. Modelling cerebral blood oxygenation using Monte Carlo XYZ-PA

    NASA Astrophysics Data System (ADS)

    Zam, Azhar; Jacques, Steven L.; Alexandrov, Sergey; Li, Youzhi; Leahy, Martin J.

    2013-02-01

    Continuous monitoring of cerebral blood oxygenation is critically important for the management of many lifethreatening conditions. Non-invasive monitoring of cerebral blood oxygenation with a photoacoustic technique offers advantages over current invasive and non-invasive methods. We introduce a Monte Carlo XYZ-PA to model the energy deposition in 3D and the time-resolved pressures and velocity potential based on the energy absorbed by the biological tissue. This paper outlines the benefits of using Monte Carlo XYZ-PA for optimization of photoacoustic measurement and imaging. To the best of our knowledge this is the first fully integrated tool for photoacoustic modelling.

  17. Single-cell measurement of red blood cell oxygen affinity

    PubMed Central

    Di Caprio, Giuseppe; Stokes, Chris; Higgins, John M.; Schonbrun, Ethan

    2015-01-01

    Oxygen is transported throughout the body by hemoglobin (Hb) in red blood cells (RBCs). Although the oxygen affinity of blood is well-understood and routinely assessed in patients by pulse oximetry, variability at the single-cell level has not been previously measured. In contrast, single-cell measurements of RBC volume and Hb concentration are taken millions of times per day by clinical hematology analyzers, and they are important factors in determining the health of the hematologic system. To better understand the variability and determinants of oxygen affinity on a cellular level, we have developed a system that quantifies the oxygen saturation, cell volume, and Hb concentration for individual RBCs in high throughput. We find that the variability in single-cell saturation peaks at an oxygen partial pressure of 2.9%, which corresponds to the maximum slope of the oxygen–Hb dissociation curve. In addition, single-cell oxygen affinity is positively correlated with Hb concentration but independent of osmolarity, which suggests variation in the Hb to 2,3-diphosphoglycerate (2–3 DPG) ratio on a cellular level. By quantifying the functional behavior of a cellular population, our system adds a dimension to blood cell analysis and other measurements of single-cell variability. PMID:26216973

  18. Integration of Quantitative Positron Emission Tomography Absolute Myocardial Blood Flow Measurements in the Clinical Management of Coronary Artery Disease.

    PubMed

    Gewirtz, Henry; Dilsizian, Vasken

    2016-05-31

    In the >40 years since planar myocardial imaging with(43)K-potassium was introduced into clinical research and management of patients with coronary artery disease (CAD), diagnosis and treatment have undergone profound scientific and technological changes. One such innovation is the current state-of-the-art hardware and software for positron emission tomography myocardial perfusion imaging, which has advanced it from a strictly research-oriented modality to a clinically valuable tool. This review traces the evolving role of quantitative positron emission tomography measurements of myocardial blood flow in the evaluation and management of patients with CAD. It presents methodology, currently or soon to be available, that offers a paradigm shift in CAD management. Heretofore, radionuclide myocardial perfusion imaging has been primarily qualitative or at best semiquantitative in nature, assessing regional perfusion in relative terms. Thus, unlike so many facets of modern cardiovascular practice and CAD management, which depend, for example, on absolute values of key parameters such as arterial and left ventricular pressures, serum lipoprotein, and other biomarker levels, the absolute levels of rest and maximal myocardial blood flow have yet to be incorporated into routine clinical practice even in most positron emission tomography centers where the potential to do so exists. Accordingly, this review focuses on potential value added for improving clinical CAD practice by measuring the absolute level of rest and maximal myocardial blood flow. Physiological principles and imaging fundamentals necessary to understand how positron emission tomography makes robust, quantitative measurements of myocardial blood flow possible are highlighted. PMID:27245647

  19. [Current views on oxygen transport from blood to tissues].

    PubMed

    Ivanov, K P

    2001-01-01

    During the recent 25-30 years, sophisticated experiments and mathematical simulation significantly changed the generally accepted theory of oxygen transport in tissue, which was based on two major postulates, namely: 1) Blood flows in capillaries continuously at uniform velocity, 2) Gas circulation between blood and tissue takes place exclusively in capillaries. As was shown by modern research techniques, blood flow in microvessels has irregular sharp velocity fluctuations in very short time intervals (seconds). In addition, mean velocity of blood flow in microvessels of the same caliber and the same micro-region of tissue may differ several times. Therefore, efficiency of microcirculation reactions may be assessed exclusively witH mean blood velocity in capillaries of the whole micro-region, and with complicated changes of the histogram of mean velocity distribution in capillaries. It was shown that arteriolas and venulas of inactive muscles and brain account for 30 to 50% of gas circulation between blood and tissue. This resulted in fundamental change of the previous postulates in the area of tissue gas circulation physiology, and, in effect, in replacement of oxygen transport paradigm created by A. Krog. This study is an attempt to present a new modern concept of oxygen transport in tissue, to show its research significance, and possible applications. PMID:11764645

  20. Effects of nicardipine on coronary blood flow, left ventricular inotropic state and myocardial metabolism in patients with angina pectoris

    PubMed Central

    Rousseau, M. F.; Vincent, M. F.; Cheron, P.; Van Den Berghe, G.; Charlier, A. A.; Pouleur, H.

    1985-01-01

    1 The effects of intravenous nicardipine (2.5 mg) on the left ventricular (LV) inotropic state, LV metabolism, and coronary haemodynamics were analysed in 22 patients with angina pectoris. 2 Measurements were made at fixed heart rate (atrial pacing), under basal state, and during a cold pressor test. 3 After nicardipine, coronary blood flow and oxygen content in the coronary sinus increased significantly. 4 The indices of inotropic state increased slightly, and the rate of isovolumic LV pressure fall improved. 5 Myocardial oxygen consumption was unchanged despite the significant reduction in pressure-rate product, but LV lactate uptake increased, particularly during the cold pressor test. 6 When nicardipine was administered after propranolol, the indices of inotropic state were unaffected. 7 The lack of direct effect of nicardipine on LV inotropic state was further confirmed by intracoronary injection of 0.1 and 0.2 mg in a separate group of 10 patients. 8 It is concluded that the nicardipine-induced coronary dilatation seems to improve perfusion and aerobic metabolism in areas with chronic ischaemia, resulting in reduced lactate production and augmented oxygen consumption. PMID:2862900

  1. Blood banking-induced alteration of red blood cell oxygen release ability

    PubMed Central

    Li, Yaojin; Xiong, Yanlian; Wang, Ruofeng; Tang, Fuzhou; Wang, Xiang

    2016-01-01

    Background Current blood banking procedures may not fully preserve red blood cell (RBC) function during storage, contributing to the decrease of RBC oxygen release ability. This study was undertaken to evaluate the impact of routine cold storage on RBC oxygen release ability. Materials and methods RBC units were collected from healthy donors and each unit was split into two parts (whole blood and suspended RBC) to exclude possible donor variability. Oxygen dissociation measurements were performed on blood units stored at 4 °C during a 5-week period. 2,3-diphosphoglycerate levels and fluorescent micrographs of erythrocyte band 3 were also analysed. Results P50 and oxygen release capacity decreased rapidly during the first 3 weeks, and then did not change significantly. In contrast, the kinetic properties (PO2-t curve and T*50) of oxygen release changed slowly during the first 3 weeks of storage, but then decreased significantly in the last 2 weeks. 2,3-diphosphoglycerate decreased quickly during the first 3 weeks of storage to almost undetectable levels. Band 3 aggregated significantly during the last 2 weeks of storage. Discussion RBC oxygen release ability appears to be sensitive to routine cold storage. The thermodynamic characteristics of RBC oxygen release ability changed mainly in the first 3 weeks of storage, due to the decrease of 2,3-diphosphoglycerate, whereas the kinetic characteristics of RBC oxygen release ability decreased significantly at the end of storage, probably affected by alterations of band 3. PMID:26674824

  2. Myocardial Oxidative Metabolism and Protein Synthesis during Mechanical Circulatory Support by Extracorporeal Membrane Oxygenation

    SciTech Connect

    Priddy, MD, Colleen M.; Kajimoto, Masaki; Ledee, Dolena; Bouchard, Bertrand; Isern, Nancy G.; Olson, Aaron; Des Rosiers, Christine; Portman, Michael A.

    2013-02-01

    Extracorporeal membrane oxygenation (ECMO) provides mechanical circulatory support essential for survival in infants and children with acute cardiac decompensation. However, ECMO also causes metabolic disturbances, which contribute to total body wasting and protein loss. Cardiac stunning can also occur which prevents ECMO weaning, and contributes to high mortality. The heart may specifically undergo metabolic impairments, which influence functional recovery. We tested the hypothesis that ECMO alters oxidative. We focused on the amino acid leucine, and integration with myocardial protein synthesis. We used a translational immature swine model in which we assessed in heart (i) the fractional contribution of leucine (FcLeucine) and pyruvate (FCpyruvate) to mitochondrial acetyl-CoA formation by nuclear magnetic resonance and (ii) global protein fractional synthesis (FSR) by gas chromatography-mass spectrometry. Immature mixed breed Yorkshire male piglets (n = 22) were divided into four groups based on loading status (8 hours of normal circulation or ECMO) and intracoronary infusion [13C6,15N]-L-leucine (3.7 mM) alone or with [2-13C]-pyruvate (7.4 mM). ECMO decreased pulse pressure and correspondingly lowered myocardial oxygen consumption (~ 40%, n = 5), indicating decreased overall mitochondrial oxidative metabolism. However, FcLeucine was maintained and myocardial protein FSR was marginally increased. Pyruvate addition decreased tissue leucine enrichment, FcLeucine, and Fc for endogenous substrates as well as protein FSR. Conclusion: The heart under ECMO shows reduced oxidative metabolism of substrates, including amino acids, while maintaining (i) metabolic flexibility indicated by ability to respond to pyruvate, and (ii) a normal or increased capacity for global protein synthesis, suggesting an improved protein balance.

  3. Myocardial Reloading After Extracorporeal Membrane Oxygenation Alters Substrate Metabolism While Promoting Protein Synthesis

    PubMed Central

    Kajimoto, Masaki; O'Kelly Priddy, Colleen M.; Ledee, Dolena R.; Xu, Chun; Isern, Nancy; Olson, Aaron K.; Rosiers, Christine Des; Portman, Michael A.

    2013-01-01

    Background Extracorporeal membrane oxygenation (ECMO) unloads the heart, providing a bridge to recovery in children after myocardial stunning. ECMO also induces stress which can adversely affect the ability to reload or wean the heart from the circuit. Metabolic impairments induced by altered loading and/or stress conditions may impact weaning. However, cardiac substrate and amino acid requirements upon weaning are unknown. We assessed the hypothesis that ventricular reloading with ECMO modulates both substrate entry into the citric acid cycle (CAC) and myocardial protein synthesis. Methods and Results Sixteen immature piglets (7.8 to 15.6 kg) were separated into 2 groups based on ventricular loading status: 8‐hour ECMO (UNLOAD) and postwean from ECMO (RELOAD). We infused into the coronary artery [2‐13C]‐pyruvate as an oxidative substrate and [13C6]‐L‐leucine as an indicator for amino acid oxidation and protein synthesis. Upon RELOAD, each functional parameter, which were decreased substantially by ECMO, recovered to near‐baseline level with the exclusion of minimum dP/dt. Accordingly, myocardial oxygen consumption was also increased, indicating that overall mitochondrial metabolism was reestablished. At the metabolic level, when compared to UNLOAD, RELOAD altered the contribution of various substrates/pathways to tissue pyruvate formation, favoring exogenous pyruvate versus glycolysis, and acetyl‐CoA formation, shifting away from pyruvate decarboxylation to endogenous substrate, presumably fatty acids. Furthermore, there was also a significant increase of tissue concentrations for all CAC intermediates (≈80%), suggesting enhanced anaplerosis, and of fractional protein synthesis rates (>70%). Conclusions RELOAD alters both cytosolic and mitochondrial energy substrate metabolism, while favoring leucine incorporation into protein synthesis rather than oxidation in the CAC. Improved understanding of factors governing these metabolic perturbations may

  4. Myocardial oxidative metabolism and protein synthesis during mechanical circulatory support by extracorporeal membrane oxygenation

    PubMed Central

    Priddy, Colleen M. O′Kelly; Kajimoto, Masaki; Ledee, Dolena R.; Bouchard, Bertrand; Isern, Nancy; Olson, Aaron K.; Rosiers, Christine Des

    2013-01-01

    Extracorporeal membrane oxygenation (ECMO) provides essential mechanical circulatory support necessary for survival in infants and children with acute cardiac decompensation. However, ECMO also causes metabolic disturbances, which contribute to total body wasting and protein loss. Cardiac stunning can also occur, which prevents ECMO weaning, and contributes to high mortality. The heart may specifically undergo metabolic impairments, which influence functional recovery. We tested the hypothesis that ECMO alters oxidative metabolism and protein synthesis. We focused on the amino acid leucine and integration with myocardial protein synthesis. We used a translational immature swine model in which we assessed in heart 1) the fractional contribution of leucine (FcLeucine) and pyruvate to mitochondrial acetyl-CoA formation by nuclear magnetic resonance and 2) global protein fractional synthesis (FSR) by gas chromatography-mass spectrometry. Immature mixed breed Yorkshire male piglets (n = 22) were divided into four groups based on loading status (8 h of normal circulation or ECMO) and intracoronary infusion [13C6,15N]-L-leucine (3.7 mM) alone or with [2-13C]-pyruvate (7.4 mM). ECMO decreased pulse pressure and correspondingly lowered myocardial oxygen consumption (∼40%, n = 5), indicating decreased overall mitochondrial oxidative metabolism. However, FcLeucine was maintained and myocardial protein FSR was marginally increased. Pyruvate addition decreased tissue leucine enrichment, FcLeucine, and Fc for endogenous substrates as well as protein FSR. The heart under ECMO shows reduced oxidative metabolism of substrates, including amino acids, while maintaining 1) metabolic flexibility indicated by ability to respond to pyruvate and 2) a normal or increased capacity for global protein synthesis. PMID:23203964

  5. Arterial blood oxygen saturation during blood pressure cuff-induced hypoperfusion

    NASA Astrophysics Data System (ADS)

    Kyriacou, P. A.; Shafqat, K.; Pal, S. K.

    2007-10-01

    Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO2) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Pulse oximeters estimate arterial oxygen saturation by shining light at two different wavelengths, red and infrared, through vascular tissue. In this method the ac pulsatile photoplethysmographic (PPG) signal associated with cardiac contraction is assumed to be attributable solely to the arterial blood component. The amplitudes of the red and infrared ac PPG signals are sensitive to changes in arterial oxygen saturation because of differences in the light absorption of oxygenated and deoxygenated haemoglobin at these two wavelengths. From the ratios of these amplitudes, and the corresponding dc photoplethysmographic components, arterial blood oxygen saturation (SpO2) is estimated. Hence, the technique of pulse oximetry relies on the presence of adequate peripheral arterial pulsations, which are detected as photoplethysmographic (PPG) signals. The aim of this study was to investigate the effect of pressure cuff-induced hypoperfusion on photoplethysmographic signals and arterial blood oxygen saturation using a custom made finger blood oxygen saturation PPG/SpO2 sensor and a commercial finger pulse oximeter. Blood oxygen saturation values from the custom oxygen saturation sensor and a commercial finger oxygen saturation sensor were recorded from 14 healthy volunteers at various induced brachial pressures. Both pulse

  6. Studies on the oxygenation of human blood by photocatalytic action.

    PubMed

    Subrahmanyam, Aryasomayajula; Arokiadoss, Thevasahayam; Ramesh, T Paul

    2007-11-01

    The present article gave the proof of concept for oxygenating human blood using the established principles of photocatalytic action of anatase TiO2 thin films in generating oxygen from water. The photocatalytic action involves the absorption of the UV optical energy (365 nm) to split water available in the blood into oxygen and hydrogen, and the generated oxygen is attached to the hemoglobin. In the present study, an enhanced catalytic action was achieved by preparing the nanosized anatase TiO2 thin films on tin-doped indium oxide (ITO) thin films, forming TiO2/ITO semiconducting junction. These TiO2 and ITO thin films and the semiconducting junctions were grown by the reactive DC Magnetron sputtering technique (using pure metallic targets) at room temperature (300 K) and subsequently annealed at 870 K for 60 min. The annealing process (i) influenced the formation of the anatase phase of TiO2; and (ii) diffused indium from ITO into TiO2, forming InTi(2)O(5). The work functions of ITO and InTi(2)O(5) were measured to be 4.72 and 4.76 eV, respectively. The higher efficacy of the photocatalytic action was attributed to the lower work function of ITO. The results clearly show that the photocatalytic action increases the oxygen content in the blood significantly. PMID:18001391

  7. Reproducibility of measurements of regional resting and hyperemic myocardial blood flow assessed with PET

    SciTech Connect

    Nagamachi, S.; Czernin, J.; Kim, A.S.

    1996-10-01

    PET with {sup 13}N-ammonia permits the noninvasive quantification of myocardial blood flow (MBF) in humans. The present study was done to assess the reproducibility of quantitative blood flow measurements at rest and during pharmacologically induced hyperemia in healthy individuals. Thirty healthy volunteers (26 men, 4 women) were studied. Paired measurements of MBF at rest (n = 21), during adenosine (n = 15) and during dipyridamole (n = 7) were performed using a two-compartment model for {sup 13}N-ammonia PET. The mean difference between baseline and follow-up blood flow (% difference) was calculated to assess reproducibility. No significant difference was observed between resting blood flow at baseline or follow-up (15.8% {plus_minus} 15.8%; p = ns). Baseline and follow-up resting blood flow were linearly correlated (r = 0.63, p < 0.005). Normalization of resting blood flow to the rate pressure product improved the reproducibility significantly (15.8% {plus_minus} 15.8% versus 10.1% {plus_minus} 10.5%, p < 0.05). Baseline and follow-up hyperemic myocardial blood flow did not differ (11.8% {plus_minus} 9.4%; p = ns) and were linearly correlated (r = 0.69, p < 0.0005). MBF at rest can be measured reproducibly with {sup 13}N-ammonia PET. The individual response to pharmacologic stress appears to be relatively consistent. Thus, serial blood flow measurements with {sup 13}N-ammonia PET can be used to quantify the effect of various interventions on MBF and vasodilatory reserve. 41 refs., 3 figs., 4 tabs.

  8. Which blood oxygen can sensitively indicate shock severity?

    NASA Astrophysics Data System (ADS)

    Pan, Boan; Li, Kai; Gao, Yuan; Ruan, Zhengshang; Li, Ting

    2016-03-01

    Clinical shock-monitoring mainly depends on measuring oxygen saturations from SVC blood samples invasively. The golden standard indicator is the central internal jugular vein oxygenation (SjvO2). Using near-infrared spectroscopy (NIRS) also can monitor shock in some papers published, but there is no discussion about which oxygen saturation (cerebral venous oxygen saturation, ScvO2; tissue oxygen saturation of internal jugular area; tissue oxygen saturation of extremities areas) can monitor shock patient more sensitively and accurately. The purpose of this paper is to examine which one is most effective. In order to discuss the problem, we continuously detected 56 critical patients who may be into shock state using NIRS oximeter at prefrontal, internal jugular vein area and forearm, and chose 24 patients who were into shock and then out of shock from the 56 critical patients. Combined with the patients' condition, the pulse oxygen saturation is most sensitively to monitoring shock than the others, and the internal jugular vein area oxygen saturation is most effective.

  9. Continuous blood oxygen saturation detection with single-wavelength photoacoustics

    NASA Astrophysics Data System (ADS)

    Peng, Qiwen; Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin

    2015-03-01

    Blood oxygen saturation (SO2) reflects the oxygenation level in blood transport and tissue. Previous studies have shown the capability of non-invasive quantitative measurements of SO2 by multi-wavelength photoacoustic (PA) spectroscopy for diagnosis of brain, tumor hemodynamics and other pathophysiological phenomena. However, those multi-wavelength methods require a tunable laser or multiple lasers which are relatively expensive and bulky for filed measurement environment and applications. Besides, the operation of multiple wavelengths, calibration procedures and data processing gets system complicated, which reduces the feasibility and flexibility for continuous real-time monitoring. Here we report a newly proposed method by combining PA and scattered light signals wherein imposing a hypothesis that scattering intensity is linear to the concentrations of oxygenated hemoglobin and deoxygenated hemoglobin weighed by blood scattering coefficients. A rigorous theoretical relationship between PA and scattering signals is thus established, making it possible that SO2 can be measured with only one excitation wavelength. To verify the theory basis, both dual-ink phantoms and fresh porcine blood sample have been employed in the experiments. The phantom experiment is able to quantify the concentration of mixed red-green ink that is in precise agreement with pre-set values. The ex vivo experiment with fresh porcine blood was conducted and the results of the proposed single-wavelength method achieved high accuracy of 1% - 4% errors. These demonstrated that the proposed single-wavelength SO2 detection is able to provide non-invasive, accurate measurement of blood oxygenation, and herein create potential for applying it to real clinical applications with low cost and high flexibility.

  10. Effects of modified pharmacologic stress approaches on hyperemic myocardial blood flow

    SciTech Connect

    Czernin, J.; Auerbach, M.; Sun, K.T.

    1995-04-01

    Pharmacologic stress testing with 0.56 mg/kg of intravenous dipyridamole is frequently used to noninvasively detect coronary artery disease (CAD). However, high-dose dipyridamole (0.80 mg/kg) or the combination of standard-dose dipyridamole (0.56 mg/kg) with the isometric handgrip maneuver might evoke a greater coronary hyperemic response. To evaluate the effect of modified pharmacologic stress tests, myocardial blood flow was quantified in 11 male subjects (mean age: 27 {plus_minus} 7 yr) during standard-dose dipyridamole (0.56 mg/kg), high-dose dipyridamole (0.80 mg/kg) and standard-dose dipyridamole combined with the isometric handgrip exercise using dynamic PET and a two-compartment model for {sup 13}N-ammonia. Systolic blood pressure, heart rate and rate pressure product remained unchanged from standard to high-dose dipyridamole but increased with the addition of the isometric handgrip. Myocardial blood flow was unchanged from standard to high-dose dipyridamole but was lower with the addition of the isometric handgrip. The hyperemic response induced by standard-dose dipyridamole cannot be further enhanced by high-dose dipyridamole. The addition of the isometric handgrip exercise results in a modest, but significant decline in hyperemic blood flow possibly due to increased extravascular resistive forces or an increase in a mediated coronary vasoconstriction associated with exercise. 31 refs., 2 figs., 1 tab.

  11. Red blood cell (RBC) deformability, RBC aggregability and tissue oxygenation in hypertension.

    PubMed

    Cicco, G; Pirrelli, A

    1999-01-01

    Arterial hypertension could be considered a progressive ischaemic syndrome interesting the macro and the microcirculation. In order to improve the clinical and therapeutic approach to the treatment of arterial hypertension, research has centered on blood flow to evaluate the different components and their very intricate relationships influencing the micro- and the macrocirculation. Of course the main problem is to study the link between the blood flow and the peripheral tissue oxygenation. During hypertension very important alterations in rheological, mechanical and biochemical characteristics of erythrocytes and of blood flow have been shown. It is very relevant the increase in blood viscosity, the decrease in red blood cell (RBC) deformability, the formation of RBC "rouleaux" and RBC aggregates. These hemorheological determinants can favour an increase of peripheral resistances and of arterial blood pressure, causing or worsening hypertension, a decrease in oxygen transport to tissue and peripheral perfusion, a decrease of the active exchange surface area in the microvasculature, especially in complicated hypertension. We have studied 320 patients: 123 with Essential Hypertension (EH) (M 59, F 64 aged 50 +/- 25 years); 81 with Secondary Hypertension (SH) without associated other pathologies influencing hemorheology (M 42, F 39 aged 48 +/- 20 years); 116 SH with other pathologies or conditions associated influencing hemorheology such as: diabetes, lipoidoproteinosis, obesity, smoking, HD, elderly, etc. (M 48, F 68 aged 46 +/- 20 years). Using a Laser-assisted Optical Rotational Red Cell Analyzer (LORCA) acc. to Hardeman (1994) we studied Elongation Index (EI) and aggregation kinetics of red blood cells in these patients. We also evaluated TcpO2 and TcpCO2 using a transcutaneous oxymeter (Microgas 7650, Kontron Instruments). In hypertensives we found a decrease in erythrocyte deformability (evaluated with EI), in erythrocyte aggregation time, a fibrinogenaemia

  12. DNA Content in Extracellular Vesicles Isolated from Porcine Coronary Venous Blood Directly after Myocardial Ischemic Preconditioning

    PubMed Central

    Rodsand, Pouria; Hellman, Urban; Waldenström, Anders; Lundholm, Marie; Ahrén, Dag; Biber, Björn; Ronquist, Gunnar; Haney, Michael

    2016-01-01

    Background Extracellular vesicles (EV) are nano-sized membranous structures released from most cells. They have the capacity to carry bioactive molecules and gene expression signals between cells, thus mediating intercellular communication. It is believed that EV confer protection after ischemic preconditioning (IPC). We hypothesize that myocardial ischemic preconditioning will lead to rapid alteration of EV DNA content in EV collected from coronary venous effluent. Materials and Methods In a porcine myocardial ischemic preconditioning model, EV were isolated from coronary venous blood before and after IPC by differential centrifugation steps culminating in preparative ultracentrifugation combined with density gradient ultracentrifugation. The EV preparation was validated, the DNA was extracted and further characterized by DNA sequencing followed by bioinformatics analysis. Results Porcine genomic DNA fragments representing each chromosome, including mitochondrial DNA sequences, were detected in EV isolated before and after IPC. There was no difference detected in the number of sequenced gene fragments (reads) or in the genomic coverage of the sequenced DNA fragments in EV isolated before and after IPC. Gene ontology analysis showed an enrichment of genes coding for ion channels, enzymes and proteins for basal metabolism and vesicle biogenesis and specific cardiac proteins. Conclusions This study demonstrates that porcine EV isolated from coronary venous blood plasma contain fragments of DNA from the entire genome, including the mitochondria. In this model we did not find specific qualitative or quantitative changes of the DNA content in EV collected immediately after an in vivo myocardial IPC provocation. This does not rule out the possibility that EV DNA content changes in response to myocardial IPC which could occur in a later time frame. PMID:27434143

  13. Blood

    MedlinePlus

    ... solid part of your blood contains red blood cells, white blood cells, and platelets. Red blood cells (RBC) deliver oxygen from your lungs to your tissues and organs. White blood cells (WBC) fight infection and are part of your ...

  14. Roles of mitochondrial fragmentation and reactive oxygen species in mitochondrial dysfunction and myocardial insulin resistance

    SciTech Connect

    Watanabe, Tomoyuki; Saotome, Masao; Nobuhara, Mamoru; Sakamoto, Atsushi; Urushida, Tsuyoshi; Katoh, Hideki; Satoh, Hiroshi; Funaki, Makoto; Hayashi, Hideharu

    2014-05-01

    Purpose: Evidence suggests an association between aberrant mitochondrial dynamics and cardiac diseases. Because myocardial metabolic deficiency caused by insulin resistance plays a crucial role in heart disease, we investigated the role of dynamin-related protein-1 (DRP1; a mitochondrial fission protein) in the pathogenesis of myocardial insulin resistance. Methods and Results: DRP1-expressing H9c2 myocytes, which had fragmented mitochondria with mitochondrial membrane potential (ΔΨ{sub m}) depolarization, exhibited attenuated insulin signaling and 2-deoxy-D-glucose (2-DG) uptake, indicating insulin resistance. Treatment of the DRP1-expressing myocytes with Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride (TMPyP) significantly improved insulin resistance and mitochondrial dysfunction. When myocytes were exposed to hydrogen peroxide (H{sub 2}O{sub 2}), they increased DRP1 expression and mitochondrial fragmentation, resulting in ΔΨ{sub m} depolarization and insulin resistance. When DRP1 was suppressed by siRNA, H{sub 2}O{sub 2}-induced mitochondrial dysfunction and insulin resistance were restored. Our results suggest that a mutual enhancement between DRP1 and reactive oxygen species could induce mitochondrial dysfunction and myocardial insulin resistance. In palmitate-induced insulin-resistant myocytes, neither DRP1-suppression nor TMPyP restored the ΔΨ{sub m} depolarization and impaired 2-DG uptake, however they improved insulin signaling. Conclusions: A mutual enhancement between DRP1 and ROS could promote mitochondrial dysfunction and inhibition of insulin signal transduction. However, other mechanisms, including lipid metabolite-induced mitochondrial dysfunction, may be involved in palmitate-induced insulin resistance. - Highlights: • DRP1 promotes mitochondrial fragmentation and insulin-resistance. • A mutual enhancement between DRP1 and ROS ipromotes insulin-resistance. • Palmitate increases DRP1 expression and induces insulin

  15. Quantitative comparison of myocardial blood flow in normal and infarcted hearts by high resolution scintigraphy

    SciTech Connect

    Hung, C.Y.; Burow, R.D.; Scherlag, B.J.; Basmadjian, G.P.; Lazzara, R.

    1984-01-01

    The standard method for measuring myocardial blood flow (MBF) with radioactive microspheres requires processing of selected tissue samples and consequent loss of exact relation to myocardial morphology. Also, in myocardial infarction (MI) there are inaccuracies due to overlap of tissues from borders of normal and MI. A new method uses Tc-99m labeled microspheres (20..mu..) which were injected into the left atrium in 18 normal dogs and 12 dogs with MI (5 had 1 day and 7 had 4 day old MI). The excised hearts were rinsed and frozen before ''bread-loaf'' sections, 3 mm thick, were cut. Images were acquired on a gamma camera with a volume resolution of 12 mm/sup 3/. A computer program for determining MBF was checked against the conventional microsphere method. The volume resolution of the latter method was 100 mm/sup 3/. The correlation coefficient between the two methods was r=0.96. Average MBF for a given section of normal RV and LV was 95 +- 13 and 119 +- 15 ml/min/100 g of tissue, respectively. Average MBF was compared in normal LV and from ischemic epicardium (IsZ) of the central MI and endocardial infarcted zone (IZ). The authors' new method, accurately and with high resolution, delineates zones of differing MBF and confirms the increase of MBF in surviving myocardium with healing.

  16. PERFUSION FOR MYOCARDIAL REVASCULARIZATION WITHOUT AN ARTIFICIAL OXYGENATOR (New Method to Reduce Surgical Morbidity)

    PubMed Central

    De Moraes, Domingos Junqueira; Abilio, Fued Michel; Cunha, Marcos; Feitosa, Lionicio A.; Aragão, Esmeraldino; Cysne, Eumenes; Vieira, Roberto; Glavam, Haroldo C. C.; Zaniolo, Waldomiro; Netto, Mario Salles; Villela, Ronaldo De A.; Labrunie, Pierre

    1979-01-01

    Thirteen patients were submitted to direct myocardial revascularization (saphenous vein graft) without the use of an artificial oxygenator. The perfusion was done by a left ventricle-to-aorta bypass and autogenous oxygenation. Most patients had three grafts implanted plus endarterectomy of the distal right coronary artery. There was one hospital death that was apparently not related to the method used. Perfusion time ranged from 45 minutes to 4 hours. Body temperature during perfusion was kept between 25 and 30° C. Perfusion flow was maintained between 25 to 50 ml per kg of body weight per minute. Ischemic, hypothermic cardiac arrest was employed. We demonstrated for the first time that perfusion for this kind of heart surgery could be done with no artificial oxygenators and, apparently, is safer for the patients. There were no bleeding problems even in perfusions as long as 4 hours. There was no respiratory dysfunction, and artificial respiration was used for only 6 to 12 hours. The patients awoke at the end of surgery with no signs or symptoms of central nervous system damage, and vasopressor drugs were rarely used after surgery. Although the experience is very small, it suggests that many postoperative problems, especially those related to bleeding and respiratory dysfunction may be reduced or eliminated by this new method. PMID:15216319

  17. Texturing Blood-Glucose-Monitoring Optics Using Oxygen Beams

    NASA Technical Reports Server (NTRS)

    Banks, Bruce

    2005-01-01

    A method has been invented for utilizing directed, hyperthermal oxygen atoms and ions for texturing tips of polymeric optical fibers or other polymeric optical components for use in optical measurement of concentration of glucose in blood. The required texture of the sensory surface of such a component amounts to a landscape of microscopic hills having high aspect ratios (hills taller than they are wide), with an average distance between hills of no more than about 5 m. This limit on the average distance between hills is chosen so that blood cells (which are wider) cannot enter the valleys between the hills, where they could obstruct optical sensing of glucose in the blood plasma. On the other hand, the plasma is required to enter the valleys, and a high aspect ratio is intended to maximize the hillside and valley surface area in contact with the plasma, thereby making it possible to obtain a given level of optical glucose- measurement sensitivity with a relatively small volume of blood. The present method of texturing by use of directed, hyperthermal (particle energy >1 eV) oxygen atoms and ions stands in contrast to a prior method of texturing by use of thermal monatomic oxygen characterized by a temperature of the order of 0.5 eV. The prior method yields low-aspect- ratio (approximately hemispherical) craters that are tens of microns wide . too wide to exclude blood cells. The figure schematically depicts parts of a typical apparatus for texturing according to the present method. One or more polymeric optical components to be textured (e.g., multiple optical fibers bundled together for simultaneous processing) are mounted in a vacuum chamber facing a suitable ion- or atom-accelerating device capable of generating a beam of oxygen atoms and/or ions having kinetic energies >1 eV. Typically, such a device includes a heated cathode, in which case it is desirable to interpose a water-cooled thermal-radiation shield to prevent melting of the polymeric component(s) to

  18. Deoxygenation Reduces Sickle Cell Blood Flow at Arterial Oxygen Tension.

    PubMed

    Lu, Xinran; Wood, David K; Higgins, John M

    2016-06-21

    The majority of morbidity and mortality in sickle cell disease is caused by vaso-occlusion: circulatory obstruction leading to tissue ischemia and infarction. The consequences of vaso-occlusion are seen clinically throughout the vascular tree, from the relatively high-oxygen and high-velocity cerebral arteries to the relatively low-oxygen and low-velocity postcapillary venules. Prevailing models of vaso-occlusion propose mechanisms that are relevant only to regions of low oxygen and low velocity, leaving a wide gap in our understanding of the most important pathologic process in sickle cell disease. Progress toward understanding vaso-occlusion is further challenged by the complexity of the multiple processes thought to be involved, including, but not limited to 1) deoxygenation-dependent hemoglobin polymerization leading to impaired rheology, 2) endothelial and leukocyte activation, and 3) altered cellular adhesion. Here, we chose to focus exclusively on deoxygenation-dependent rheologic processes in an effort to quantify their contribution independent of the other processes that are likely involved in vivo. We take advantage of an experimental system that, to our knowledge, uniquely enables the study of pressure-driven blood flow in physiologic-sized tubes at physiologic hematocrit under controlled oxygenation conditions, while excluding the effects of endothelium, leukocyte activation, adhesion, inflammation, and coagulation. We find that deoxygenation-dependent rheologic processes are sufficient to increase apparent viscosity significantly, slowing blood flow velocity at arterial oxygen tension even without additional contributions from inflammation, adhesion, and endothelial and leukocyte activation. We quantify the changes in apparent viscosity and define a set of functional regimes of sickle cell blood flow personalized for each patient that may be important in further dissecting mechanisms of in vivo vaso-occlusion as well as in assessing risk of patient

  19. Myocardial ischemia and reperfusion: the role of oxygen radicals in tissue injury.

    PubMed

    Werns, S W; Lucchesi, B R

    1989-01-01

    Thrombolytic therapy has gained widespread acceptance as a means of treating coronary artery thrombosis in patients with acute myocardial infarction. Although experimental data have demonstrated that timely reperfusion limits the extent of infarction caused by regional ischemia, there is growing evidence that reperfusion is associated with an inflammatory response to ischemia that exacerbates the tissue injury. Ischemic myocardium releases archidonate and complement-derived chemotactic factors, e.g., leukotriene B4 and C5a, which attract and activate neutrophils. Reperfusion of ischemic myocardium accelerates the influx of neutrophils, which release reactive oxygen products, such as superoxide anion and hydrogen peroxide, resulting in the formation of a hydroxyl radical and hypochlorous acid. The latter two species may damage viable endothelial cells and myocytes via the peroxidation of lipids and oxidation of protein sulfhydryl groups, leading to perturbations of membrane permeability and enzyme function. Neutrophil depletion by antiserum and inhibition of neutrophil function by drugs, e.g., ibuprofen, prostaglandins (prostacyclin and PGE1), or a monoclonal antibody, to the adherence-promoting glycoprotein Mo-1 receptor, have been shown to limit the extent of canine myocardial injury due to coronary artery occlusion/reperfusion. Recent studies have challenged the hypothesis that xanthine-oxidase-derived oxygen radicals are a cause of reperfusion injury. Treatment with allopurinol or oxypurinol may exert beneficial effects on ischemic myocardium that are unrelated to the inhibition of xanthine oxidase. Furthermore, the human heart may lack xanthine oxidase activity. Further basic research is needed, therefore, to clarify the importance of xanthine oxidase in the pathophysiology of reperfusion injury.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2488090

  20. Influence of oxygen tension on myocardial performance. Evaluation by tissue Doppler imaging

    PubMed Central

    Frøbert, Ole; Moesgaard, Jacob; Toft, Egon; Poulsen, Steen Hvitfeldt; Søgaard, Peter

    2004-01-01

    Background Low O2 tension dilates coronary arteries and high O2 tension is a coronary vasoconstrictor but reports on O2-dependent effects on ventricular performance diverge. Yet oxygen supplementation remains first line treatment in cardiovascular disease. We hypothesized that hypoxia improves and hyperoxia worsens myocardial performance. Methods Seven male volunteers (mean age 38 ± 3 years) were examined with echocardiography at respiratory equilibrium during: 1) normoxia (≈21% O2, 79% N2), 2) while inhaling a hypoxic gas mixture (≈11% O2, 89% N2), and 3) while inhaling 100% O2. Tissue Doppler recordings were acquired in the apical 4-chamber, 2-chamber, and long-axis views. Strain rate and tissue tracking displacement analyses were carried out in each segment of the 16-segment left ventricular model and in the basal, middle and apical portions of the right ventricle. Results Heart rate increased with hypoxia (68 ± 4 bpm at normoxia vs. 79 ± 5 bpm, P < 0.001) and decreased with hyperoxia (59 ± 5 bpm, P < 0.001 vs. normoxia). Hypoxia increased strain rate in four left ventricular segments and global systolic contraction amplitude was increased (normoxia: 9.76 ± 0.41 vs hypoxia: 10.87 ± 0.42, P < 0.001). Tissue tracking displacement was reduced in the right ventricular segments and tricuspid regurgitation increased with hypoxia (7.5 ± 1.9 mmHg vs. 33.5 ± 1.8 mmHg, P < 0.001). The TEI index and E/E' did not change with hypoxia. Hyperoxia reduced strain rate in 10 left ventricular segments, global systolic contraction amplitude was decreased (8.83 ± 0.38, P < 0.001 vs. normoxia) while right ventricular function was unchanged. The spectral and tissue Doppler TEI indexes were significantly increased but E/E' did not change with hyperoxia. Conclusion Hypoxia improves and hyperoxia worsens systolic myocardial performance in healthy male volunteers. Tissue Doppler measures of diastolic function are unaffected by hypoxia/hyperoxia which support that the changes

  1. Improved Arterial Blood Oxygenation Following Intravenous Infusion of Cold Supersaturated Dissolved Oxygen Solution

    PubMed Central

    Grady, Daniel J; Gentile, Michael A; Riggs, John H; Cheifetz, Ira M

    2014-01-01

    BACKGROUND One of the primary goals of critical care medicine is to support adequate gas exchange without iatrogenic sequelae. An emerging method of delivering supplemental oxygen is intravenously rather than via the traditional inhalation route. The objective of this study was to evaluate the gas-exchange effects of infusing cold intravenous (IV) fluids containing very high partial pressures of dissolved oxygen (>760 mm Hg) in a porcine model. METHODS Juvenile swines were anesthetized and mechanically ventilated. Each animal received an infusion of cold (13 °C) Ringer’s lactate solution (30 mL/kg/hour), which had been supersaturated with dissolved oxygen gas (39.7 mg/L dissolved oxygen, 992 mm Hg, 30.5 mL/L). Arterial blood gases and physiologic measurements were repeated at 15-minute intervals during a 60-minute IV infusion of the supersaturated dissolved oxygen solution. Each animal served as its own control. RESULTS Five swines (12.9 ± 0.9 kg) were studied. Following the 60-minute infusion, there were significant increases in PaO2 and SaO2 (P < 0.05) and a significant decrease in PaCO2 (P < 0.05), with a corresponding normalization in arterial blood pH. Additionally, there was a significant decrease in core body temperature (P < 0.05) when compared to the baseline preinfusion state. CONCLUSIONS A cold, supersaturated dissolved oxygen solution may be intravenously administered to improve arterial blood oxygenation and ventilation parameters and induce a mild therapeutic hypothermia in a porcine model. PMID:25249764

  2. Fractal regional myocardial blood flows pattern according to metabolism, not vascular anatomy.

    PubMed

    Yipintsoi, Tada; Kroll, Keith; Bassingthwaighte, James B

    2016-02-01

    Regional myocardial blood flows are markedly heterogeneous. Fractal analysis shows strong near-neighbor correlation. In experiments to distinguish control by vascular anatomy vs. local vasomotion, coronary flows were increased in open-chest dogs by stimulating myocardial metabolism (catecholamines + atropine) with and without adenosine. During control states mean left ventricular (LV) myocardial blood flows (microspheres) were 0.5-1 ml·g(-1)·min(-1) and increased to 2-3 ml·g(-1)·min(-1) with catecholamine infusion and to ∼4 ml·g(-1)·min(-1) with adenosine (Ado). Flow heterogeneity was similar in all states: relative dispersion (RD = SD/mean) was ∼25%, using LV pieces 0.1-0.2% of total. During catecholamine infusion local flows increased in proportion to the mean flows in 45% of the LV, "tracking" closely (increased proportionately to mean flow), while ∼40% trended toward the mean. Near-neighbor regional flows remained strongly spatially correlated, with fractal dimension D near 1.2 (Hurst coefficient 0.8). The spatial patterns remain similar at varied levels of metabolic stimulation inferring metabolic dominance. In contrast, adenosine vasodilation increased flows eightfold times control while destroying correlation with the control state. The Ado-induced spatial patterns differed from control but were self-consistent, inferring that with full vasodilation the relaxed arterial anatomy dominates the distribution. We conclude that vascular anatomy governs flow distributions during adenosine vasodilation but that metabolic vasoregulation dominates in normal physiological states. PMID:26589329

  3. Pentobarbital-Induced Myocardial Stunning in Status Epilepticus Requiring Extracorporeal Membrane Oxygenation: A Case Report and Literature Review

    PubMed Central

    Molaie, Donna; Nurok, Michael; Rosengart, Axel; Lahiri, Shouri

    2016-01-01

    Introduction. Mild hypotension is a well-recognized complication of intravenous pentobarbital; however fulminant cardiopulmonary failure has not been previously reported. Case Report. A 28-year-old woman developed pentobarbital-induced cardiopulmonary failure that was successfully treated with maximal medical management including arteriovenous extracorporeal membrane oxygenation. She made an excellent cardiopulmonary and neurological recovery. Discussion and Conclusion. Pentobarbital is underrecognized as a potential cause of myocardial stunning. The mechanism involves direct myocardial depression and inhibition of autonomic neuroanatomical structures including the medulla and hypothalamus. Early recognition and implementation of aggressive cardiopulmonary support are essential to optimize the likelihood of a favorable outcome. PMID:27529037

  4. Pentobarbital-Induced Myocardial Stunning in Status Epilepticus Requiring Extracorporeal Membrane Oxygenation: A Case Report and Literature Review.

    PubMed

    Kavi, Tapan; Molaie, Donna; Nurok, Michael; Rosengart, Axel; Lahiri, Shouri

    2016-01-01

    Introduction. Mild hypotension is a well-recognized complication of intravenous pentobarbital; however fulminant cardiopulmonary failure has not been previously reported. Case Report. A 28-year-old woman developed pentobarbital-induced cardiopulmonary failure that was successfully treated with maximal medical management including arteriovenous extracorporeal membrane oxygenation. She made an excellent cardiopulmonary and neurological recovery. Discussion and Conclusion. Pentobarbital is underrecognized as a potential cause of myocardial stunning. The mechanism involves direct myocardial depression and inhibition of autonomic neuroanatomical structures including the medulla and hypothalamus. Early recognition and implementation of aggressive cardiopulmonary support are essential to optimize the likelihood of a favorable outcome. PMID:27529037

  5. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle.

    PubMed

    Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

    2012-07-01

    This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (V̇O(2)) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and V̇O(2) in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO(2)], [Hb], and THC), tissue oxygen saturation (S(t)O(2)), relative BF (rBF), and relative oxygen consumption rate (rV̇O(2)). The rBF and rV̇O(2) signals were calibrated with absolute baseline BF and V̇O(2) obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology. PMID:22894482

  6. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

    PubMed Central

    Gurley, Katelyn; Shang, Yu

    2012-01-01

    Abstract. This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (V˙O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and V˙O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (rV˙O2). The rBF and rV˙O2 signals were calibrated with absolute baseline BF and V˙O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology. PMID:22894482

  7. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

    NASA Astrophysics Data System (ADS)

    Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

    2012-07-01

    This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (\\Vdot O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and \\Vdot O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (r\\Vdot O2). The rBF and r\\Vdot O2 signals were calibrated with absolute baseline BF and \\Vdot O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.

  8. Renal blood flow and oxygenation drive nephron progenitor differentiation.

    PubMed

    Rymer, Christopher; Paredes, Jose; Halt, Kimmo; Schaefer, Caitlin; Wiersch, John; Zhang, Guangfeng; Potoka, Douglas; Vainio, Seppo; Gittes, George K; Bates, Carlton M; Sims-Lucas, Sunder

    2014-08-01

    During kidney development, the vasculature develops via both angiogenesis (branching from major vessels) and vasculogenesis (de novo vessel formation). The formation and perfusion of renal blood vessels are vastly understudied. In the present study, we investigated the regulatory role of renal blood flow and O2 concentration on nephron progenitor differentiation during ontogeny. To elucidate the presence of blood flow, ultrasound-guided intracardiac microinjection was performed, and FITC-tagged tomato lectin was perfused through the embryo. Kidneys were costained for the vasculature, ureteric epithelium, nephron progenitors, and nephron structures. We also analyzed nephron differentiation in normoxia compared with hypoxia. At embryonic day 13.5 (E13.5), the major vascular branches were perfused; however, smaller-caliber peripheral vessels remained unperfused. By E15.5, peripheral vessels started to be perfused as well as glomeruli. While the interior kidney vessels were perfused, the peripheral vessels (nephrogenic zone) remained unperfused. Directly adjacent and internal to the nephrogenic zone, we found differentiated nephron structures surrounded and infiltrated by perfused vessels. Furthermore, we determined that at low O2 concentration, little nephron progenitor differentiation was observed; at higher O2 concentrations, more differentiation of the nephron progenitors was induced. The formation of the developing renal vessels occurs before the onset of blood flow. Furthermore, renal blood flow and oxygenation are critical for nephron progenitor differentiation. PMID:24920757

  9. Renal blood flow and oxygenation drive nephron progenitor differentiation

    PubMed Central

    Rymer, Christopher; Paredes, Jose; Halt, Kimmo; Schaefer, Caitlin; Wiersch, John; Zhang, Guangfeng; Potoka, Douglas; Vainio, Seppo; Gittes, George K.; Bates, Carlton M.

    2014-01-01

    During kidney development, the vasculature develops via both angiogenesis (branching from major vessels) and vasculogenesis (de novo vessel formation). The formation and perfusion of renal blood vessels are vastly understudied. In the present study, we investigated the regulatory role of renal blood flow and O2 concentration on nephron progenitor differentiation during ontogeny. To elucidate the presence of blood flow, ultrasound-guided intracardiac microinjection was performed, and FITC-tagged tomato lectin was perfused through the embryo. Kidneys were costained for the vasculature, ureteric epithelium, nephron progenitors, and nephron structures. We also analyzed nephron differentiation in normoxia compared with hypoxia. At embryonic day 13.5 (E13.5), the major vascular branches were perfused; however, smaller-caliber peripheral vessels remained unperfused. By E15.5, peripheral vessels started to be perfused as well as glomeruli. While the interior kidney vessels were perfused, the peripheral vessels (nephrogenic zone) remained unperfused. Directly adjacent and internal to the nephrogenic zone, we found differentiated nephron structures surrounded and infiltrated by perfused vessels. Furthermore, we determined that at low O2 concentration, little nephron progenitor differentiation was observed; at higher O2 concentrations, more differentiation of the nephron progenitors was induced. The formation of the developing renal vessels occurs before the onset of blood flow. Furthermore, renal blood flow and oxygenation are critical for nephron progenitor differentiation. PMID:24920757

  10. Oxygen tension measurement using an automatic blood gas analyser1

    PubMed Central

    Becket, J; Chakrabarti, M K; Gillies, I D S; Orchard, C; Hall, G M; Bourdillon, P J

    1981-01-01

    Two different methods of assessing the reliability of the oxygen electrode of one model of an automatic blood gas analyser (BGA) have been studied. In the first, a single automatic BGA was assessed by using outdated bank blood which was pumped around a small extracorporeal circuit into which known gas mixtures were passed. Oxygen tension was varied between 2 and 16 kPa. In the second, fresh heparinized blood was tonometered with calibrated gases and submitted to the automatic BGA used in the first part of the study and also to three other identical machines. Each of the machines was between 3 and 4 years old. Eighteen different units of blood were used in the first part of the study. The correlation coefficient between the automatic BGA and the Po2 in the extracorporeal circuit varied between 0.29 and 0.99. 31% of the total of 209 measurements made by the automatic BGA were more than 1.2 kPa from the reference value, 25% of them being between 1.2 and 4.0 kPa from the reference value. In the second part of the study, the correlation coefficient between this automatic BGA and the tonometered blood was 0.96. The correlation coefficients for the 3 other identical BGAs were 0.84, 0.97 and 0.88, indicating that the BGA used in the first part of the study was no worse than any of the others. It is suggested that although clinicians are likely to ignore readings of an automatic BGA that are more than 4.0 kPa from the true value and are likely to repeat the investigation, readings between 1.2 and 4.0 kPa from the true value may adversely affect patient management. PMID:7288796

  11. Oxygen tension measurement using an automatic blood gas analyser.

    PubMed

    Becket, J; Orchard, C; Chakrabarti, M K; Hall, G M; Gillies, I D; Bourdillon, P J

    1981-08-01

    Two different methods of assessing the reliability of the oxygen electrode of one model of an automatic blood gas analyser (BGA) have been studied. In the first, a single automatic BGA was assessed by using outdated bank blood which was pumped around a small extracorporeal circuit into which known gas mixtures were passed. Oxygen tension was varied between 2 and 16 kPa. In the second, fresh heparinized blood was tonometered with calibrated gases and submitted to the automatic BGA used in the first part of the study and also to three other identical machines. Each of the machines was between 3 and 4 years old.Eighteen different units of blood were used in the first part of the study. The correlation coefficient between the automatic BGA and the Po(2) in the extracorporeal circuit varied between 0.29 and 0.99. 31% of the total of 209 measurements made by the automatic BGA were more than 1.2 kPa from the reference value, 25% of them being between 1.2 and 4.0 kPa from the reference value. In the second part of the study, the correlation coefficient between this automatic BGA and the tonometered blood was 0.96. The correlation coefficients for the 3 other identical BGAs were 0.84, 0.97 and 0.88, indicating that the BGA used in the first part of the study was no worse than any of the others.It is suggested that although clinicians are likely to ignore readings of an automatic BGA that are more than 4.0 kPa from the true value and are likely to repeat the investigation, readings between 1.2 and 4.0 kPa from the true value may adversely affect patient management. PMID:7288796

  12. A Investigation of Partially Extracted Tracers Used to Determine Myocardial Blood Flow with PET.

    NASA Astrophysics Data System (ADS)

    Christian, Bradley Thomas

    Positron Emission Tomography (PET) provides the ability to quantitatively measure mass-specific blood flow to myocardial tissue (ml/min/g tissue). The partially extracted tracers ^{62}Cu -PTSM and two single photon emission computed tomography(SPECT) agents, teboroxime and sestamibi were studied. The latter two demonstrate the effectiveness of PET as a pharmacological tool for SPECT perfusion tracer development. The characteristics of these tracers were compared to commonly used partially extracted tracers ^{13}rm NH_3 and ^{82} Rb. Positron emitting ^{rm 94m}Tc was used to label ligands originally developed for ^{rm 99m} Tc labeling. ^{rm 94m }Tc can be produced by the bombardment of a natural molybdenum foil with an 11Mev proton beam, via the ^{94}rm Mo(p,n)^ {94m}Tc reaction. The production of ^{rm94m}Tc is accompanied by ^{92}Tc, ^ {94}Tc, ^{95} Tc, ^{rm 95m}Tc, ^{96}Tc, and ^{rm 99m}Tc due to the isotopic mixture of natural Mo. The presence of these radionuclidic impurities increase the radiation dose received by the patient and radio chemist. The elimination of these impurities was achieved by irradiating an isotopically enriched target material, ^{94}rm MoO_3. The ability to reclaim the enriched target is essential due to the high cost of the material. Recovery was accomplished by a solvent extraction technique yielding an activity recovery of 80% and target material recovery of 95%. Preliminary data was measured for the myocardial perfusion tracer ^{62}Cu -PTSM. It was found that the uptake of ^ {62}Cu-PTSM is linear for resting flows but a high degree of variability is observed at stress induced flows. This same result was found in the human studies when compared to ^{13} rm NH_3 measured myocardial perfusion values. The dynamic analysis of multiple tracers in the sequence of protocols: (1) acute canine prep ( ^{11}rm CO, ^{82 }Rb, ^{62}Cu-PTSM, ^{13}rm NH_3, ^{94m,99m}Tc-BATO, H_2 ^{14}rm O, ^{18 }FCH_3), (2) chronic canine prep ( ^{82}rm Rb, ^{13 }NH_3

  13. Cerebral Blood Oxygenation Measurement Based on Oxygen-dependent Quenching of Phosphorescence

    PubMed Central

    Sakadžić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A.; Mandeville, Emiri T.; Srinivasan, Vivek J.; Arai, Ken; Ruvinskaya, Svetlana; Wu, Weicheng; Devor, Anna; Lo, Eng H.; Vinogradov, Sergei A.; Boas, David A.

    2011-01-01

    Monitoring of the spatiotemporal characteristics of cerebral blood and tissue oxygenation is crucial for better understanding of the neuro-metabolic-vascular relationship. Development of new pO2 measurement modalities with simultaneous monitoring of pO2 in larger fields of view with higher spatial and/or temporal resolution will enable greater insight into the functioning of the normal brain and will also have significant impact on diagnosis and treatment of neurovascular diseases such as stroke, Alzheimer's disease, and head injury. Optical imaging modalities have shown a great potential to provide high spatiotemporal resolution and quantitative imaging of pO2 based on hemoglobin absorption in visible and near infrared range of optical spectrum. However, multispectral measurement of cerebral blood oxygenation relies on photon migration through the highly scattering brain tissue. Estimation and modeling of tissue optical parameters, which may undergo dynamic changes during the experiment, is typically required for accurate estimation of blood oxygenation. On the other hand, estimation of the partial pressure of oxygen (pO2) based on oxygen-dependent quenching of phosphorescence should not be significantly affected by the changes in the optical parameters of the tissue and provides an absolute measure of pO2. Experimental systems that utilize oxygen-sensitive dyes have been demonstrated in in vivo studies of the perfused tissue as well as for monitoring the oxygen content in tissue cultures, showing that phosphorescence quenching is a potent technology capable of accurate oxygen imaging in the physiological pO2 range. Here we demonstrate with two different imaging modalities how to perform measurement of pO2 in cortical vasculature based on phosphorescence lifetime imaging. In first demonstration we present wide field of view imaging of pO2 at the cortical surface of a rat. This imaging modality has relatively simple experimental setup based on a CCD camera and a

  14. Effects of Hemoglobin-Based Oxygen Carriers on Blood Coagulation

    PubMed Central

    Roghani, Kimia; Holtby, Randall J.; Jahr, Jonathan S.

    2014-01-01

    For many decades, Hemoglobin-based oxygen carriers (HBOCs) have been central in the development of resuscitation agents that might provide oxygen delivery in addition to simple volume expansion. Since 80% of the world population lives in areas where fresh blood products are not available, the application of these new solutions may prove to be highly beneficial (Kim and Greenburg 2006). Many improvements have been made to earlier generation HBOCs, but various concerns still remain, including coagulopathy, nitric oxide scavenging, platelet interference and decreased calcium concentration secondary to volume expansion (Jahr et al. 2013). This review will summarize the current challenges faced in developing HBOCs that may be used clinically, in order to guide future research efforts in the field. PMID:25514567

  15. Effect of {beta}{sub 1} adrenergic receptor blockade on myocardial blood flow and vasodilatory capacity

    SciTech Connect

    Boettcher, M.; Czernin, J.; Sun, K.

    1997-03-01

    The {beta}{sub 1} receptor blockade reduces cardiac work and may thereby lower myocardial blood flow (MBF) at rest. The effect of {beta}{sub 1} receptor blockade on hyperemic MBF is unknown. To evaluate the effect of selective {beta}{sub 1} receptor blockade on MBF at rest and during dipyridamole induced hyperemia, 10 healthy volunteers (8 men, 2 women, mean age 24 {+-} 5 yr) were studied using {sup 13}N-ammonia PET (two-compartment model) under control conditions and again during metoprolol (50 mg orally 12 hr and 1 hr before the study). The resting rate pressure product (6628 {+-} 504 versus 5225 {+-} 807) and heart rate (63 {+-} 6-54 {plus_minus} 5 bpm) declined during metoprolol (p < 0.05). Similarly, heart rate and rate pressure product declined from the baseline dipyridamole study to dipyridamole plus metoprolol (p < 0.05). Resting MBF declined in proportion to cardiac work by approximately 20% from 0.61 {+-} 0.09-0.51 {+-} 0.10 ml/g/min (p < 0.05). In contrast, hyperemic MBF increased when metoprolol was added to dipyridamole (1.86 {plus_minus} 0.27 {+-} 0.45 ml/g/min; p<0.05). The decrease in resting MBF together with the increase in hyperemic MBF resulted in a significant increase in the myocardial flow reserve during metoprolol (3.14 {+-} 0.80-4.61 {+-} 0.68; p<0.01). The {beta}{sub 1} receptor blockade increases coronary vasodilatory capacity and myocardial flow reserve. However, the mechanisms accounting for this finding remain uncertain. 32 refs., 2 figs., 2 tabs.

  16. Use of blood-pool imaging in evaluation of diffuse activity patterns in technetium-99m pyrophosphate myocardial scintigraphy.

    PubMed

    Cowley, M J; Mantle, J A; Rogers, W J; Russell, R O; Rackley, C E; Logic, J R

    1979-06-01

    It has been suggested that diffuse Tc-99m pyrophosphate precordial activity may be due to persistent blood-pool activity in routine delayed views during myocardial imaging. To answer this question, we reviewed myocardial scintigrams recorded 60--90 min following the injection of 12--15 mCi of Tc-99m pyrophosphate for the presence of diffuse precordial activity, and compared these with early images of the blood pool in 265 patients. Diffuse activity in the delayed images was identified in 48 patients: in 20 with acute myocardial infarction and in 28 with no evidence of it. Comparison of these routine delayed images with early views of the blood pool revealed two types of patterns. In patients with acute infarction, 95% had delayed images that were distinguishable from blood pool either because the activity was smaller than the early blood pool, or by the presence of localized activity superimposed on diffuse activity identical to blood pool. In those without infarction, 93% had activity distribution in routine delayed views matching that in the early blood-pool images. The usefulness of the diffuse TcPPi precordial activity in myocardial infarction is improved when early blood-pool imaging is used to exclude persistence of blood-pool activity as its cause. Moreover, it does not require additional amounts of radioactivity nor complex computer processing, a feature that may be of value in the community hospital using the technique to "rule out" infarction 24--72 hr after onset of suggestive symptoms. PMID:231644

  17. Cerebral blood oxygenation measurement based on oxygen-dependent quenching of phosphorescence.

    PubMed

    Sakadžić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A; Mandeville, Emiri T; Srinivasan, Vivek J; Arai, Ken; Ruvinskaya, Svetlana; Wu, Weicheng; Devor, Anna; Lo, Eng H; Vinogradov, Sergei A; Boas, David A

    2011-01-01

    Monitoring of the spatiotemporal characteristics of cerebral blood and tissue oxygenation is crucial for better understanding of the neuro-metabolic-vascular relationship. Development of new pO2 measurement modalities with simultaneous monitoring of pO2 in larger fields of view with higher spatial and/or temporal resolution will enable greater insight into the functioning of the normal brain and will also have significant impact on diagnosis and treatment of neurovascular diseases such as stroke, Alzheimer's disease, and head injury. Optical imaging modalities have shown a great potential to provide high spatiotemporal resolution and quantitative imaging of pO2 based on hemoglobin absorption in visible and near infrared range of optical spectrum. However, multispectral measurement of cerebral blood oxygenation relies on photon migration through the highly scattering brain tissue. Estimation and modeling of tissue optical parameters, which may undergo dynamic changes during the experiment, is typically required for accurate estimation of blood oxygenation. On the other hand, estimation of the partial pressure of oxygen (pO2) based on oxygen-dependent quenching of phosphorescence should not be significantly affected by the changes in the optical parameters of the tissue and provides an absolute measure of pO2. Experimental systems that utilize oxygen-sensitive dyes have been demonstrated in in vivo studies of the perfused tissue as well as for monitoring the oxygen content in tissue cultures, showing that phosphorescence quenching is a potent technology capable of accurate oxygen imaging in the physiological pO2 range. Here we demonstrate with two different imaging modalities how to perform measurement of pO2 in cortical vasculature based on phosphorescence lifetime imaging. In first demonstration we present wide field of view imaging of pO2 at the cortical surface of a rat. This imaging modality has relatively simple experimental setup based on a CCD camera and a

  18. Test-Retest Repeatability of Myocardial Blood Flow Measurements using Rubidium-82 Positron Emission Tomography

    NASA Astrophysics Data System (ADS)

    Efseaff, Matthew

    Rubidium-82 positron emission tomography (PET) imaging has been proposed for routine myocardial blood flow (MBF) quantification. Few studies have investigated the test-retest repeatability of this method. Same-day repeatability of rest MBF imaging was optimized with a highly automated analysis program using image-derived input functions and a dual spillover correction (SOC). The effects of heterogeneous tracer infusion profiles and subject hemodynamics on test-retest repeatability were investigated at rest and during hyperemic stress. Factors affecting rest MBF repeatability included gender, suspected coronary artery disease, and dual SOC (p < 0.001). The best repeatability coefficient for same-day rest MBF was 0.20 mL/min/g using a six-minute scan-time, iterative reconstruction, dual SOC, resting rate-pressure-product (RPP) adjustment, and a left atrium image-derived input function. The serial study repeatabilities of the optimized protocol in subjects with homogeneous RPPs and tracer infusion profiles was 0.19 and 0.53 mL/min/g at rest and stress, and 0.95 for stress / rest myocardial flow reserve (MFR). Subjects with heterogeneous tracer infusion profiles and hemodynamic conditions had significantly less repeatable MBF measurements at rest, stress, and stress/rest flow reserve (p < 0.05).

  19. Quantitative photoacoustic blood oxygenation measurement of whole porcine blood samples using a multi-wavelength semiconductor laser system

    NASA Astrophysics Data System (ADS)

    Friedrich, Claus-Stefan; Mienkina, Martin P.; Brenner, Carsten; Gerhardt, Nils C.; Jörger, Manfred; Strauß, Andreas; Beckmann, Martin F.; Schmitz, Georg; Hofmann, Martin R.

    2011-07-01

    We present a photoacoustic measurement system based on semiconductor lasers for blood oxygenation measurements. It permits to use four different optical wavelengths (650nm, 808nm, 850nm, 905nm) to generate photoacoustic signals. As the optical extinction coefficient of oxygenated hemoglobin and deoxygenated hemoglobin is different at specific wavelengths, a blood oxygenation measurement by a multi-wavelength photoacoustic laser system is feasible. Especially at 650nm, the clear difference between the extinction coefficients of the two hemoglobin derivates permits to determine the blood oxygenation in combination with other near infrared wavelengths. A linear model based on tabulated values of extinction coefficients for fully oxygenated and fully deoxygenated hemoglobin is presented. We used heparin stabilized whole porcine blood samples to model the optical behavior of human blood, as the optical absorption behavior of porcine hemoglobin does not differ significantly from human hemoglobin. To determine the real oxygen saturation values of the blood samples, we measured the partial oxygen pressure with an IRMA Trupoint Blood Analysis System. The oxygen saturation values were calculated from a dissociation curve for porcine blood. The results of the photoacoustic measurement are in qualitatively good agreement with the predicted linear model. Further, we analyze the abilities and the limitations of quantitative oxygenation measurements.

  20. Simultaneous blood-tissue exchange of oxygen, carbon dioxide, bicarbonate, and hydrogen ion.

    PubMed

    Dash, Ranjan K; Bassingthwaighte, James B

    2006-07-01

    A detailed nonlinear four-region (red blood cell, plasma, interstitial fluid, and parenchymal cell) axially distributed convection-diffusion-permeation-reaction-binding computational model is developed to study the simultaneous transport and exchange of oxygen (O2) and carbon dioxide (CO2) in the blood-tissue exchange system of the heart. Since the pH variation in blood and tissue influences the transport and exchange of O2 and CO2 (Bohr and Haldane effects), and since most CO2 is transported as HCO3(-) (bicarbonate) via the CO2 hydration (buffering) reaction, the transport and exchange of HCO3(-) and H+ are also simulated along with that of O2 and CO2. Furthermore, the model accounts for the competitive nonlinear binding of O2 and CO2 with the hemoglobin inside the red blood cells (nonlinear O2-CO2 interactions, Bohr and Haldane effects), and myoglobin-facilitated transport of O2 inside the parenchymal cells. The consumption of O2 through cytochrome-c oxidase reaction inside the parenchymal cells is based on Michaelis-Menten kinetics. The corresponding production of CO2 is determined by respiratory quotient (RQ), depending on the relative consumption of carbohydrate, protein, and fat. The model gives a physiologically realistic description of O2 transport and metabolism in the microcirculation of the heart. Furthermore, because model solutions for tracer transients and steady states can be computed highly efficiently, this model may be the preferred vehicle for routine data analysis where repetitive solutions and parameter optimization are required, as is the case in PET imaging for estimating myocardial O2 consumption. PMID:16775761

  1. Relationship between PVA and myocardial oxygen consumption can be derived from thermodynamics.

    PubMed

    Denslow, S

    1996-02-01

    The pressure-volume area (PVA) has been shown to be an excellent, linear index of myocardial oxygen consumption. The thermodynamic basis for this result, however, has not been elucidated. The present study was undertaken to determine what information could be gained from analyzing the cardiac pressure-volume (P-V) cycle as an approximation to some "ideal" thermodynamic cycle operating under the constraints imposed by cardiovascular anatomy and physiology. The myocardium was approximated as a linear, chemically driven elastance in accordance with the time-varying elastance model. Analysis provided descriptions of a Carnot cycle for myocardium and a suboptimal ideal cycle, including isovolumic phases. Further analysis of the ideal cycle indicated that the end-systolic P-V relationship (ESPVR) is an approximation to the adiabatic P-V trajectory that primarily determines total energy consumption. Analysis also indicated possible explanations of current results that seem to be at odds with the time-varying elastance model. These results suggest that thermodynamic cycle analysis may provide a useful analytic tool for investigation of the cardiac cycle. PMID:8779851

  2. Chronic Lead Exposure Increases Blood Pressure and Myocardial Contractility in Rats

    PubMed Central

    Fioresi, Mirian; Simões, Maylla Ronacher; Furieri, Lorena Barros; Broseghini-Filho, Gilson Brás; Vescovi, Marcos Vinícius A.; Stefanon, Ivanita; Vassallo, Dalton Valentim

    2014-01-01

    We investigated the cardiovascular effects of lead exposure, emphasising its direct action on myocardial contractility. Male Wistar rats were sorted randomly into two groups: control (Ct) and treatment with 100 ppm of lead (Pb) in the drinking water. Blood pressure (BP) was measured weekly. At the end of the treatment period, the animals were anaesthetised and haemodynamic parameters and contractility of the left ventricular papillary muscles were recorded. Blood and tissue samples were properly stored for further biochemical investigations. Statistical analyses were considered to be significant at p<0.05. The lead concentrations in the blood reached approximately 13 µg/dL, while the bone was the site of the highest deposition of this metal. BP in the Pb-treated group was higher from the first week of lead exposure and remained at the same level over the next four weeks. Haemodynamic evaluations revealed increases in systolic (Ct: 96±3.79 vs. Pb: 116±1.37 mmHg) and diastolic blood pressure (Ct: 60±2.93 vs. Pb: 70±3.38 mmHg), left ventricular systolic pressure (Ct: 104±5.85 vs. Pb: 120±2.51 mmHg) and heart rate (Ct: 307±10 vs. Pb: 348±16 bpm). Lead treatment did not alter the force and time derivatives of the force of left ventricular papillary muscles that were contracting isometrically. However, our results are suggestive of changes in the kinetics of calcium (Ca++) in cardiomyocytes increased transarcolemmal Ca++ influx, low Ca++ uptake by the sarcoplasmic reticulum and high extrusion by the sarcolemma. Altogether, these results show that despite the increased Ca++ influx that was induced by lead exposure, the myocytes had regulatory mechanisms that prevented increases in force, as evidenced in vivo by the increased systolic ventricular pressure. PMID:24841481

  3. Reduction of oxidative stress does not affect recovery of myocardial function: warm continuous versus cold intermittent blood cardioplegia.

    PubMed Central

    Biagioli, B.; Borrelli, E.; Maccherini, M.; Bellomo, G.; Lisi, G.; Giomarelli, P.; Sani, G.; Toscano, M.

    1997-01-01

    OBJECTIVE: To compare oxidative stress after cardiac surgery in patients treated with two different methods of myocardial protection: warm continuous versus cold intermittent blood cardioplegia. To correlate oxidative stress with postoperative myocardial dysfunction. DESIGN: Prospective, randomised, double blind, trial. SETTING: Institutional centre of cardiovascular surgery. PATIENTS: 20 patients were selected for coronary artery bypass surgery (CABG) on the following basis: stable angina, ejection fraction > 50%, double or triple vessel disease, no previous CABG or associated disease. Patients were randomised to two groups of 10 patients each. INTERVENTIONS: Patients underwent CABG with one of two different methods of myocardial protection and cardiopulmonary bypass. CBC group: intermittent cold blood antegrade-retrograde cardioplegia with moderate hypothermic cardiopulmonary bypass; WBC group: continuous warm blood antegrade-retrograde cardioplegia with mild hypothermic cardiopulmonary bypass. MAIN OUTCOME MEASURE: The index of oxidative stress used was the alteration of whole blood and plasma glutathione redox status. Samples were collected from the coronary sinus and peripheral vein before anaesthesia (T1), before aortic unclamping (T2), 15 minutes (T3), and 30 minutes (T4) after unclamping. Haemodynamic parameters were measured with thermodilution techniques. RESULTS: Oxidised glutathione and glutathione-cysteine mixed disulphide significantly increased in the coronary sinus plasma in the CBC group, and the overall redox balance of glutathione was decreased (P < 0.01) at T2-T4 versus T1, and compared with the WBC group. Comparable results were obtained for coronary sinus blood. There was no correlation between postoperative haemodynamic measurements and oxidative stress markers. CONCLUSIONS: Oxidative stress was significant in patients undergoing CABG using cold blood cardioplegia, while the warm technique minimised the effects of ischaemia. However

  4. Photoacoustic microscopy of cerebral blood-oxygenation dynamics in mice

    NASA Astrophysics Data System (ADS)

    Maslov, Konstantin; Stein, Erich W.; Wang, Lihong V.

    2009-02-01

    In this work, we exploit the high depth and temporal resolutions of PAM to noninvasively image the blood-oxygenation dynamics of multiple cortex vessels in the mouse brain simultaneously in response to controlled hypoxic and hyperoxic challenges. The dark-field photoacoustic microscopy (PAM) technique was enhanced to image the cortex vasculature of the mouse brain in vivo using endogenous hemoglobin contrast with one second temporal resolution. The maximum values of about 20% with standard deviation +/- 1.2% were found to vary significantly among the cortex vessels studied. The hypoxic response time to rise from 10 % to 90 % of maximum was 63 +/- 6 sec. The reverse response time for this event was 16 +/- 2 sec.

  5. Changes in the flow properties of white blood cells after acute myocardial infarction.

    PubMed

    Nash, G B; Christopher, B; Morris, A J; Dormandy, J A

    1989-11-01

    Because they can obstruct blood vessels and release noxious substances, white blood cells may contribute to the development of tissue ischaemia. The flow properties of white cells were tested after myocardial infarction, by measuring the filtration rates of cell suspensions through 8 microns pore filters. Compared with mononuclear cells from age matched controls, mononuclear cells from patients with infarction showed impaired filterability within the first day after the onset of pain; this condition persisted for at least two days and by day 10 it was improved. On day 1, granulocyte filterability and the proportion showing morphological evidence of activation were nearly normal. By day 3 the flow resistance and activation had increased, but the changes seen depended on the age of the patient. The filterability and activation of granulocytes from patients aged less than 60 were significantly increased from day 1, whereas there were no changes in granulocytes from patients aged greater than 60 years. Suspensions of unfractionated white cells showed changes intermediate between the mononuclear cells and granulocytes. A group of five patients who presented with chest pain but who were subsequently found not to have had an infarction showed no evidence of abnormal filterability or activation. The changes in filterability probably reflect white cell activation, which may have an adverse effect on the perfusion of the ischaemic myocardium. PMID:2590586

  6. Method for Studying the Myocardial Blood Flow Reserve by Load Dynamic Single-Photon Emission Computed Tomography.

    PubMed

    Mochula, A V; Zavadovsky, K V; Lishmanov, Yu B

    2016-04-01

    We developed a method for collection and processing of scintigraphic data to estimate myocardial reserve in a gamma-chamber with cadmium-zinc-telluride detectors. Dynamic single-photon emission computed tomography of the heart with (99m)Tc-Technetril was performed in 16 coronary heart disease patients at rest and during pharmacological load. During data processing, regions of interest from the cavity and the myocardium of the left ventricle were formed and activity-time curves were constructed. The index of myocardial blood fl ow reserve was calculated as the difference between two ratios of the mean gamma-count from the myocardial area to the area under the left ventricle cavity curve (peak) during load and at rest. The mean indices of myocardial reserve in healthy volunteers and patients with coronary artery atherosclerosis were 1.86 (1.59; 2.20) and 1.39 (1.12; 1.69), respectively. The development of the method for studying myocardial reserve by single-photon emission computed tomography is an urgent problem and requires further investigations. PMID:27165060

  7. Myocardial imaging in dogs treated with grisorixin: relationship between /sup 201/Tl uptake and coronary blood flow

    SciTech Connect

    Moins, N.; Gachon, P.; Maublant, J.

    1982-04-01

    /sup 201/Tl myocardial imaging was performed in dogs after pretreatment with grisorixin, which appeared to increase the myocardial uptake of /sup 201/Tl. This effect of grisorixin was found to be dose dependent, with an optimal dose of 60 microgram/kg. The myocardial-to-background ratio, which was 1.92 in the control dogs, rose to 4.45. The increase in the absolute myocardial uptake was demonstrated in guinea pigs that received /sup 201/Tl after similar pretreatment with grisorixin. In the animals treated with 500 microgram/kg, the uptake of /sup 201/Tl by the heart was 35% over the control value. With 60 microgram/kg grisorixin, the coronary blood flow increased from 40 to 176 ml/min 5 min after the injection. This dose, optimal for imaging, induced the maximum vasodilator effect with only a very slight concomitant increase in the left-ventricular pressure and myocardial contractility. Above 60 microgram/kg, grisorixin appeared to be a potent inotropic agent, whereas below this dose it showed only coronary vasodilator properties. Some evidence for an ionophore effect of this compound was found in dogs pretreated with 60 microgram/kg. In these the radionuclide was injected when the coronary vasodilatation had become insignificant, but a significant improvement of the M/B ratio was still evident.

  8. Relation of retinal blood flow and retinal oxygen extraction during stimulation with diffuse luminance flicker

    PubMed Central

    Palkovits, Stefan; Lasta, Michael; Told, Reinhard; Schmidl, Doreen; Werkmeister, René; Cherecheanu, Alina Popa; Garhöfer, Gerhard; Schmetterer, Leopold

    2015-01-01

    Cerebral and retinal blood flow are dependent on local neuronal activity. Several studies quantified the increase in cerebral blood flow and oxygen consumption during activity. In the present study we investigated the relation between changes in retinal blood flow and oxygen extraction during stimulation with diffuse luminance flicker and the influence of breathing gas mixtures with different fractions of O2 (FiO2; 100% 15% and 12%). Twenty-four healthy subjects were included. Retinal blood flow was studied by combining measurement of vessel diameters using the Dynamic Vessel Analyser with measurements of blood velocity using laser Doppler velocimetry. Oxygen saturation was measured using spectroscopic reflectometry and oxygen extraction was calculated. Flicker stimulation increased retinal blood flow (57.7 ± 17.8%) and oxygen extraction (34.6 ± 24.1%; p < 0.001 each). During 100% oxygen breathing the response of retinal blood flow and oxygen extraction was increased (p < 0.01 each). By contrast, breathing gas mixtures with 12% and 15% FiO2 did not alter flicker–induced retinal haemodynamic changes. The present study indicates that at a comparable increase in blood flow the increase in oxygen extraction in the retina is larger than in the brain. During systemic hyperoxia the blood flow and oxygen extraction responses to neural stimulation are augmented. The underlying mechanism is unknown. PMID:26672758

  9. Relation of retinal blood flow and retinal oxygen extraction during stimulation with diffuse luminance flicker.

    PubMed

    Palkovits, Stefan; Lasta, Michael; Told, Reinhard; Schmidl, Doreen; Werkmeister, René; Cherecheanu, Alina Popa; Garhöfer, Gerhard; Schmetterer, Leopold

    2015-01-01

    Cerebral and retinal blood flow are dependent on local neuronal activity. Several studies quantified the increase in cerebral blood flow and oxygen consumption during activity. In the present study we investigated the relation between changes in retinal blood flow and oxygen extraction during stimulation with diffuse luminance flicker and the influence of breathing gas mixtures with different fractions of O2 (FiO2; 100% 15% and 12%). Twenty-four healthy subjects were included. Retinal blood flow was studied by combining measurement of vessel diameters using the Dynamic Vessel Analyser with measurements of blood velocity using laser Doppler velocimetry. Oxygen saturation was measured using spectroscopic reflectometry and oxygen extraction was calculated. Flicker stimulation increased retinal blood flow (57.7 ± 17.8%) and oxygen extraction (34.6 ± 24.1%; p < 0.001 each). During 100% oxygen breathing the response of retinal blood flow and oxygen extraction was increased (p < 0.01 each). By contrast, breathing gas mixtures with 12% and 15% FiO2 did not alter flicker-induced retinal haemodynamic changes. The present study indicates that at a comparable increase in blood flow the increase in oxygen extraction in the retina is larger than in the brain. During systemic hyperoxia the blood flow and oxygen extraction responses to neural stimulation are augmented. The underlying mechanism is unknown. PMID:26672758

  10. Absolute Quantitation of Myocardial Blood Flow in Human Subjects with or without Myocardial Ischemia using Dynamic Flurpiridaz F 18 Positron Emission Tomography

    PubMed Central

    Packard, René R. S.; Huang, Sung-Cheng; Dahlbom, Magnus; Czernin, Johannes; Maddahi, Jamshid

    2015-01-01

    Absolute quantitation of myocardial blood flow (MBF) by positron emission tomography (PET) is an established method of analyzing coronary artery disease (CAD) but subject to the various shortcomings of available radiotracers. Flurpiridaz F 18 is a novel PET radiotracer which exhibits properties of an ideal tracer. Methods A new absolute perfusion quantitation method with Flurpiridaz was developed, taking advantage of the early kinetics and high first-pass extraction by the myocardium of this radiotracer, and the first in human measurements of MBF performed in 7 normal subjects and 8 patients with documented CAD. PET images with time-activity curves were acquired at rest and during adenosine stress. Results In normal subjects, regional MBF between coronary artery territories did not differ significantly, leading to a mean global MBF of 0.73 mL/min/g at rest and 2.53 mL/min/g during stress, with a mean global myocardial flow reserve (MFR) of 3.70. CAD vascular territories with <50% stenosis demonstrated a mean MBF of 0.73 at rest and 2.02 during stress, leading to a mean MFR of 2.97. CAD vascular territories with ≥50% stenosis exhibited a mean MBF of 0.86 at rest and 1.43 during stress, leading to a mean MFR of 1.86. Differences in stress MBF and MFR between normal and CAD territories, as well as between <50% and ≥50% stenosis vascular territories, were significant (P<0.01). Conclusion Absolute quantitation of MBF in humans with the novel PET radiotracer Flurpiridaz is feasible over a wide range of cardiac flow in the presence or absence of stress-inducible myocardial ischemia. The significant decrease in stress MBF and ensuing MFR in CAD territories allows a clear distinction between vascular territories exhibiting stress-inducible myocardial ischemia and those with normal perfusion. PMID:25071096

  11. Modulation of Perfusion and Oxygenation by Red Blood Cell Oxygen Affinity during Acute Anemia

    PubMed Central

    Cabrales, Pedro; Tsai, Amy G.; Intaglietta, Marcos

    2008-01-01

    Responses to exchange transfusion using red blood cells (RBCs) with modified hemoglobin (Hb) oxygen (O2) affinity were studied in the hamster window chamber model during acute anemia to determine its role on microvascular perfusion and tissue oxygenation. Allosteric effectors were introduced in the RBCs by electroporation. Inositol hexaphosphate (IHP) and 5-hydroxymethyl-2-furfural (5HMF) were used to decrease and increase Hb-O2 affinity. In vitro P50s (partial pressure of O2 at 50% Hb saturation) were modified to 10, 25, 45, and 50 mm Hg (normal P50 is 32 mm Hg). Allosteric effectors also decreased the Hill coefficient. Anemic condition was induced by isovolemic hemodilution exchanges using 6% dextran 70 kD to 18% hematocrit (Hct). Modified RBCs (at 18% Hct in 5% albumin solution) were infused by exchange transfusion of 35% of blood volume. Systemic parameters, microvascular perfusion, capillary perfusion (functional capillary density, FCD), and microvascular Po2 levels were measured. RBcs with P50 of 45 mm Hg increased tissue Po2 and decreased O2 delivery (Do2) and extraction (Vo2) and RBCs with P50 of 60 mmHg reduced FCD, microvascular flow, tissue Po2, Do2 and Vo2. Erythrocytes with increased Hb-O2 affinity maintained hemodynamic conditions, Do2 and decreased tissue Po2. This study shows that in an anemic condition, maximal tissue Po2 does not correspond to maximal Do2 and Vo2. PMID:17884988

  12. The Effect of Chronic Hypoxemia on Regional Myocardial Blood Flow in the Conscious Dog After Acute Coronary Artery Occlusion

    PubMed Central

    Bishop, Sanford P.; White, Francis C.; Bloor, Colin M.

    1977-01-01

    Chronic hypoxemia was produced in 16 dogs by surgical transposition of the caudal vena cava to the left atrium to determine if chronic hypoxemia would alter the response of the myocardium to acute ischemia. An electromagnetic aortic flow probe, left atrial tube, and occlusive cuff on the left circumflex coronary artery were permanently implanted in 11 hypoxemic and 26 normal control dogs. The animals were studied in the conscious state after recovery from the surgery. Dogs with hypoxemia had a blood hematocrit value of 54.3 ± 1.0% (SE), arterial PO2 of 43.2 ± 1.4 mm Hg, and 80.2 ± 1.6% oxygen saturation. There was no difference from control animals in the ratio of left ventricular weight to body weight, but the right ventricular weight was significantly decreased in the hypoxemic dogs. Cardiac output from the left ventricle was twice that of the right ventricle. Aortic blood flow was 3.68 ± 0.22 liters/min in hypoxemic animals and 2.64 ± 0.19 liters/min in normal dogs. Myocardial blood flow measured with 15-μ diameter tracer microspheres was increased from 79 ± 10 and 59 ± 8 ml/100 g/min in left ventricular endocardial and epicardial halves, respectively, in normal dogs to 212 ± 48 and 172 ± 39 in dogs with chronic hypoxemia. There were no deaths in 10 hypoxemic dogs within 24 hours after complete circumflex coronary artery occlusion; 7 of 26 (27%) normal dogs died after circumflex coronary artery occlusion during the conscious state. Gross infarct size was extremely variable in both groups. Median infarct size was smaller in dogs with hypoxemia and was directly correlated with arterial PO2 in hypoxemic dogs. There was a mild, but statistically not significant, increase in the anastomotic index of hypoxemic dogs compared with that of normal animals, suggesting that a metabolic adaptive change rather than increased collateral circulation may have been responsible for the decreased mortality and smaller infarct size in hypoxemic dogs. PMID:596417

  13. Relationship between regional myocardial blood flow and thallium-201 distribution in the presence of coronary artery stenosis and dipyridamole-induced vasodilation

    SciTech Connect

    Mays, A.E. Jr.; Cobb, F.R.

    1984-05-01

    This study assesses the relationship between the distribution of thallium-201 and myocardial blood flow during coronary vasodilation induced by intravenous dipyridamole in canine models of partial and complete coronary artery stenosis. 10 dogs were chronically instrumented with catheters in the left atrium and aorta and with a balloon occluder and electromagnetic flow probe on the proximal left circumflex coronary artery. Regional myocardial blood flow was measured during control conditions with radioisotope-labeled microspheres, and the phasic reactive hyperemic response to a 20-s transient occlusion was then recorded. Dipyridamole was then infused intravenously until phasic coronary blood flow increased to match peak hyperemic values. The left circumflex coronary artery was either partially occluded to reduce phasic blood flow to control values (group 1) or it was completely occluded (group 2), and thallium-201 and a second microsphere label were injected. 5 min later, the animals were sacrificed, the left ventricle was sectioned into 1-2-g samples, and thallium-201 activity and regional myocardial blood flow were measured. Curvilinear regression analyses between thallium-201 localization and myocardial blood flow during dipyridamole infusion demonstrated a slightly better fit to a second- as compared with a first-order model, indicating a slight roll-off of thallium activity as myocardial blood flow increases. During the dipyridamole infusion, the increases in phasic blood flow, the distributions of regional myocardial blood flow, and the relationships between thallium-201 localization and regional blood flow were comparable to values previously observed in exercising dogs with similar occlusions. These data provide basic validation that supports the use of intravenous dipyridamole and thallium-201 as an alternative to exercise stress and thallium-201 for evaluating the effects of coronary occlusive lesions on the distribution of regional myocardial blood flow.

  14. Quantification of myocardial blood flow using PET to improve the management of patients with stable ischemic coronary artery disease.

    PubMed

    Ohira, Hiroshi; Dowsley, Taylor; Dwivedi, Girish; deKemp, Robert A; Chow, Benjamin J; Ruddy, Terrence D; Davies, Ross A; DaSilva, Jean; Beanlands, Rob S B; Hessian, Renee

    2014-09-01

    Cardiac PET has been evolving over the past 30 years. Today, it is accepted as a valuable imaging modality for the noninvasive assessment of coronary artery disease. PET has demonstrated superior diagnostic accuracy for the detection of coronary artery disease compared with single-photon emission computed tomography, and also has a well-established prognostic value. The routine addition of absolute quantification of myocardial blood flow increases the diagnostic accuracy for three-vessel disease and provides incremental functional and prognostic information. Moreover, the characterization of the vasodilator capacity of the coronary circulation may guide proper decision-making and monitor the effects of lifestyle changes, exercise training, risk factor modification or medical therapy for improving regional and global myocardial blood flow. This type of image-guided approach to individualized patient therapy is now attainable with the routine use of cardiac PET flow reserve imaging. PMID:25354033

  15. Heart rate in the pathophysiology of coronary blood flow and myocardial ischaemia: benefit from selective bradycardic agents

    PubMed Central

    Heusch, G

    2008-01-01

    Starting out from a brief description of the determinants of coronary blood flow (perfusion, pressure, extravascular compression, autoregulation, metabolic regulation, endothelium-mediated regulation and neurohumoral regulation) the present review highlights the overwhelming importance of metabolic regulation such that coronary blood flow is increased at increased heart rate under physiological circumstances and the overwhelming importance of extravascular compression such that coronary blood flow is decreased at increased heart rate through reduction of diastolic duration in the presence of severe coronary stenoses. The review goes on to characterize the role of heart rate in the redistribution of regional myocardial blood flow between a normal coronary vascular tree with preserved autoregulation and a poststenotic vasculature with exhausted coronary reserve. When flow is normalized by heart rate, there is a consistent close relationship of regional myocardial blood flow and contractile function for each single cardiac cycle no matter whether or not there is a coronary stenosis and what the actual blood flow is. β-Blockade improves both flow and function along this relationship. When the heart rate reduction associated with β-blockade is prevented by pacing, α-adrenergic coronary vasoconstriction is unmasked and both flow and function are deteriorated. Selective heart rate reduction, however, improves both flow and function without any residual negative effect such as unmasked α-adrenergic coronary vasoconstriction or negative inotropic action. PMID:18223669

  16. Optimized dynamic framing for PET-based myocardial blood flow estimation

    NASA Astrophysics Data System (ADS)

    Kolthammer, Jeffrey A.; Muzic, Raymond F.

    2013-08-01

    An optimal experiment design methodology was developed to select the framing schedule to be used in dynamic positron emission tomography (PET) for estimation of myocardial blood flow using 82Rb. A compartment model and an arterial input function based on measured data were used to calculate a D-optimality criterion for a wide range of candidate framing schedules. To validate the optimality calculation, noisy time-activity curves were simulated, from which parameter values were estimated using an efficient and robust decomposition of the estimation problem. D-optimized schedules improved estimate precision compared to non-optimized schedules, including previously published schedules. To assess robustness, a range of physiologic conditions were simulated. Schedules that were optimal for one condition were nearly-optimal for others. The effect of infusion duration was investigated. Optimality was better for shorter than for longer tracer infusion durations, with the optimal schedule for the shortest infusion duration being nearly optimal for other durations. Together this suggests that a framing schedule optimized for one set of conditions will also work well for others and it is not necessary to use different schedules for different infusion durations or for rest and stress studies. The method for optimizing schedules is general and could be applied in other dynamic PET imaging studies.

  17. [Changes of endotoxin concentration in blood serum in patients with uncomplicated acute myocardial Q-infarction].

    PubMed

    Anikhovskaya, I A; Kubatiev, A A; Salakhov, I M; Tebloev, K I; Yakovlev, M Yu

    2015-01-01

    The effectiveness of acute myocardial infarction (AMI) treatment does not correspond to high material costs for the study of its pathogenesis and development of new drugs. This circumstance gives the grounds to assume existence of nowadays unknown mechanisms of emergence and development of this disease. High probability of participation of endotoxin (ET) in the pathogenesis of AMI was theoretically proved by us for more than a quarter of the century ago, but it's clinical evidence to date is not found yet. As a result of the study a significant increase of endotoxin (ET) concentration in the blood serum of patients with AMI increasing from 1 to 14 day of the disease has been found. In women the concentration of ET was higher than in men. It allows to qualify the EA as a factor probably influencing the known difference in AMI tolerance in men and women. The source of ET were Bacteroides (most often--67.8% of patients), Klebsiella, Pseudomonas, Proteus, Escherichia coli. One or two bacteria more often took part in the development of EA. In 9.1% of patients the etiology of EA could not be verified, what indicates the presence of other sources of EA, not evaluated in this study. In 25% of patients with AMI serologic evidence of systemic candidiasis, caused by candida Albicans, has been found, what is able to enhance the biological effects of ET. PMID:26852597

  18. Will 3-dimensional PET-CT enable the routine quantification of myocardial blood flow?

    PubMed

    deKemp, Robert A; Yoshinaga, Keiichiro; Beanlands, Rob S B

    2007-01-01

    Quantification of myocardial blood flow (MBF) and flow reserve has been used extensively with positron emission tomography (PET) to investigate the functional significance of coronary artery disease. Increasingly, flow quantification is being applied to investigations of microvascular dysfunction in early atherosclerosis and in nonatherosclerotic microvascular disease associated with primary and secondary cardiomyopathies. Fully three-dimensional (3D) acquisition is becoming the standard imaging mode on new equipment, bringing with it certain challenges for cardiac PET, but also the potential for MBF to be measured simultaneously with routine electrocardiography (ECG)-gated perfusion imaging. Existing 3D versus 2D comparative studies support the use of 3D cardiac PET for flow quantification, and these protocols can be translated to PET-CT, which offers a virtually noise-free attenuation correction. This technology combines the strengths of cardiac CT for evaluation of anatomy with cardiac PET for quantification of the hemodynamic impact on the myocardium. High throughput clinical imaging protocols are needed to evaluate the incremental diagnostic and prognostic value of this technology. PMID:17556173

  19. Sinogram smoothing techniques for myocardial blood flow estimation from dose-reduced dynamic computed tomography

    PubMed Central

    Modgil, Dimple; Alessio, Adam M.; Bindschadler, Michael D.; La Rivière, Patrick J.

    2014-01-01

    Abstract. Dynamic contrast-enhanced computed tomography (CT) could provide an accurate and widely available technique for myocardial blood flow (MBF) estimation to aid in the diagnosis and treatment of coronary artery disease. However, one of its primary limitations is the radiation dose imparted to the patient. We are exploring techniques to reduce the patient dose by either reducing the tube current or by reducing the number of temporal frames in the dynamic CT sequence. Both of these dose reduction techniques result in noisy data. In order to extract the MBF information from the noisy acquisitions, we have explored several data-domain smoothing techniques. In this work, we investigate two specific smoothing techniques: the sinogram restoration technique in both the spatial and temporal domains and the use of the Karhunen–Loeve (KL) transform to provide temporal smoothing in the sinogram domain. The KL transform smoothing technique has been previously applied to dynamic image sequences in positron emission tomography. We apply a quantitative two-compartment blood flow model to estimate MBF from the time-attenuation curves and determine which smoothing method provides the most accurate MBF estimates in a series of simulations of different dose levels, dynamic contrast-enhanced cardiac CT acquisitions. As measured by root mean square percentage error (% RMSE) in MBF estimates, sinogram smoothing generally provides the best MBF estimates except for the cases of the lowest simulated dose levels (tube current=25  mAs, 2 or 3 s temporal spacing), where the KL transform method provides the best MBF estimates. The KL transform technique provides improved MBF estimates compared to conventional processing only at very low doses (<7  mSv). Results suggest that the proposed smoothing techniques could provide high fidelity MBF information and allow for substantial radiation dose savings. PMID:25642441

  20. A Model of Anterograde Oxygenated Lung Blood Flow in Acardia.

    PubMed

    Marinakis, Sotirios; Burki, Marco; Abdel-Sayed, Saad; von Segesser, Ludwig Karl

    2016-01-01

    In extreme situations such as hyperacute rejection of heart transplant or major heart trauma, heart explantation and extracorporeal membrane oxygenation (ECMO) hemodynamic support might be the only means for survival. In our previous model of acardia, pulmonary artery (PA) was clamped and did not receive any anterograde blood flow. A model of anterograde PA perfusion might be necessary to avoid ischemic pulmonary damage in prolonged ECMO in acardia. The aim of this study was to describe the surgical technique and to determine the feasibility of an anterograde lung perfusion in acardia through the anastomosis of the right internal mammary artery (RIMA) to the PA. A venoarterial cardiopulmonary bypass was established in three pigs (72 ± 2.6 kg) by the transjugular insertion to the caval axis of a double-staged cannula with carotid artery return. Heart was excised and ECMO was established as previously reported. Right internal mammary artery was harvested and after measurement of its output (93.3 ± 5.8 ml/min, representing 2.17% ± 0.15% of total pump flow), it was anastomosed to PA. Right internal mammary artery anastomosis to PA is a feasible, safe, and easy to perform maneuver assuring an anterograde lung perfusion in acardia. PMID:27442854

  1. 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.

  2. Clinical importance of hyperemic coronary blood flow (thrombolysis in myocardial infarction-intravenous flow) after primary percutaneous coronary intervention.

    PubMed

    Karakoyun, Süleyman; Tanboga, Ibrahim Halil; Kurt, Mustafa; Aksakal, Enbiya; Kaya, Ahmet; Isik, Turgay; Ekinci, Mehmet; Sevimli, Serdar; Acikel, Mahmut

    2014-10-01

    We aimed to investigate clinical, demographic and angiographic factors associated with hyperemic coronary blood flow (HCBF) and the relation of HCBF with mortality at 30 days. Our study included 809 consecutive patients with acute ST-segment elevation myocardial infarction who underwent primary percutaneous coronary intervention (PCI). We divided corrected thrombolysis in myocardial infarction (TIMI) frame count (TFC) values into three tertiles: less than 14, 14-28 and more than 28. Corrected TFC less than 14 was defined as HCBF or TIMI intravenous flow. The primary end-point of the present study was all-cause mortality within 30 days. Among the HCBF group (n = 58), the patients with poor myocardial perfusion demonstrated the highest mortality rate within the 30-day follow-up period (33%). Low TIMI myocardial perfusion grade, history of no smoking, left ventricular ejection fraction (LVEF), and high Killip status and low LVEF were found to be independently associated with 1-month all-cause mortality. The present study showed that HCBF after primary PCI has a high 30-day mortality when associated with impaired reperfusion. PMID:24842315

  3. Impact of red blood cell transfusion on global and regional measures of oxygenation.

    PubMed

    Roberson, Russell S; Bennett-Guerrero, Elliott

    2012-01-01

    Anemia is common in critically ill patients. Although the goal of transfusion of red blood cells is to increase oxygen-carrying capacity, there are contradictory results about whether red blood cell transfusion to treat moderate anemia (e.g., hemoglobin 7-10 g/dL) improves tissue oxygenation or changes outcomes. Whereas increasing levels of anemia eventually lead to a level of critical oxygen delivery, increased cardiac output and oxygen extraction are homeostatic mechanisms the body uses to prevent a state of dysoxia in the setting of diminished oxygen delivery due to anemia. In order for cardiac output to increase in the face of anemia, normovolemia must be maintained. Transfusion of red blood cells increases blood viscosity, which may actually decrease cardiac output (barring a state of hypovolemia prior to transfusion). Studies have generally shown that transfusion of red blood cells fails to increase oxygen uptake unless oxygen uptake/oxygen delivery dependency exists (e.g., severe anemia or strenuous exercise). Recently, near-infrared spectroscopy, which approximates the hemoglobin saturation of venous blood, has been used to investigate whether transfusion of red blood cells increases tissue oxygenation in regional tissue beds (e.g., brain, peripheral skeletal muscle). These studies have generally shown increases in near-infrared spectroscopy derived measurements of tissue oxygenation following transfusion. Studies evaluating the effect of transfusion on the microcirculation have shown that transfusion increases the functional capillary density. This article will review fundamental aspects of oxygen delivery and extraction, and the effects of red blood cell transfusion on tissue oxygenation as well as the microcirculation. PMID:22238040

  4. The relative risk of myocardial infarction in patients who have high blood pressure and non-cardiac pain.

    PubMed

    Psaty, B M; Koepsell, T D; LoGerfo, J P; Wagner, E H; Inui, T S

    1987-01-01

    The authors conducted a population-based case--control study to determine the risk of myocardial infarction in patients who reported angina-like symptoms. The cases studied were those of patients who had high blood pressure and had sought treatment in 1984 with myocardial infarction as the first manifestation of coronary artery disease. Controls, a random sample of patients who had hypertension, were frequency-matched to cases by age and gender. Blind to case--control status, the authors reviewed the medical records of the 32 cases and 64 controls for reports of angina-like symptoms. While controls reported such symptoms at a constant rate, the events for the cases clustered near their infarctions. When a patient with hypertension sought medical advice for angina-like symptoms, the risk of infarction within 30 days was 14.2 (95% confidence interval, 2.8 to 71), and after 30 days it fell to 1.03. Among patients who have high blood pressure but no history of angina, presentations with prodromal symptoms in the primary care setting are so common that only about one in 100 such visits actually heralds myocardial infarction. PMID:3694297

  5. [On Individualization of Therapeutic Doses of Optical Radiation according to Changes in Parameters of Blood Oxygenation].

    PubMed

    Zalesskaya, G A

    2015-01-01

    The effect of in vivo laser irradiation by optical radiation on blood from different patients is studied. The objects of research were three series of blood samples from patients whose treatment course included extracorporeal UV blood irradiation, intravenous laser blood irradiation and supra-venous blood laser irradiation. Before and after irradiation the results on optic oximetry and gas content of venous blood were compared. The results of positive and negative influence of blood irradiation on characteristics of an oxygen exchange in separate patients and on the maintenance of some products of metabolism are represented. It is shown that at the same power dose, their changes depend on individual, initial values of hemoglobin oxygen saturation of venous blood and its photoinduced changes which objectively reflect individual sensitivity of patients to the action of optical radiation on blood and can be used for assessment of the efficiency of phototherapy. PMID:26349218

  6. Hypoxemia, oxygen content, and the regulation of cerebral blood flow.

    PubMed

    Hoiland, Ryan L; Bain, Anthony R; Rieger, Mathew G; Bailey, Damian M; Ainslie, Philip N

    2016-03-01

    This review highlights the influence of oxygen (O2) availability on cerebral blood flow (CBF). Evidence for reductions in O2 content (CaO2 ) rather than arterial O2 tension (PaO2 ) as the chief regulator of cerebral vasodilation, with deoxyhemoglobin as the primary O2 sensor and upstream response effector, is discussed. We review in vitro and in vivo data to summarize the molecular mechanisms underpinning CBF responses during changes in CaO2 . We surmise that 1) during hypoxemic hypoxia in healthy humans (e.g., conditions of acute and chronic exposure to normobaric and hypobaric hypoxia), elevations in CBF compensate for reductions in CaO2 and thus maintain cerebral O2 delivery; 2) evidence from studies implementing iso- and hypervolumic hemodilution, anemia, and polycythemia indicate that CaO2 has an independent influence on CBF; however, the increase in CBF does not fully compensate for the lower CaO2 during hemodilution, and delivery is reduced; and 3) the mechanisms underpinning CBF regulation during changes in O2 content are multifactorial, involving deoxyhemoglobin-mediated release of nitric oxide metabolites and ATP, deoxyhemoglobin nitrite reductase activity, and the downstream interplay of several vasoactive factors including adenosine and epoxyeicosatrienoic acids. The emerging picture supports the role of deoxyhemoglobin (associated with changes in CaO2 ) as the primary biological regulator of CBF. The mechanisms for vasodilation therefore appear more robust during hypoxemic hypoxia than during changes in CaO2 via hemodilution. Clinical implications (e.g., disorders associated with anemia and polycythemia) and future study directions are considered. PMID:26676248

  7. Relationship between muscle oxygenation by NIRS and blood lactate

    NASA Astrophysics Data System (ADS)

    Xu, Guodong; Mao, Zongzhen; Ye, Yanjie; Lv, Kunru

    2011-01-01

    The aim of the study was to investigate the relationship of muscle oxygenation in term of oxy-hemoglobin concentration change (ΔHbO2) by NIRS and blood lactate (BLA) in local skeletal muscle and evaluate the capability of NIRS in the research of exercise physiology Twenty-three athlete in the national fin-swimming team took the increasing load training on the power bicycle while their ΔHbO2 and BLA were simultaneously recorded. The initial powers used in the training were set as 100 w for males and 40 w for females. During the experiment, the power kept constant for 3 min before each abrupt increment of 30 w until the limit of the athlete's capability. Statistical analysis and data visualization were performed. Following the increasing load training, ΔHbO2 step-likely increased in the phase of aerobic metabolism but linearly decreased in the phase of anaerobic metabolism. The variation tendency of BLA was the same as ΔHbO2 and the concurrency of crucial turning points between ΔHbO2 and BLA was revealed. This relationship between ΔHbO2 and BLA presented in the increasing load training suggested that ΔHbO2 might be capable for taking the place of the invasively measured parameter BLA. Considering that ΔHbO2 can be noninvasively measured by NIRS, ΔHbO2 has the potential in the evaluation of athletes' physiological function and training effect on the athletes and accordingly NIRS can be well used in this field.

  8. Blood Leukocyte Count on Admission Predicts Cardiovascular Events in Patients with Acute Non-ST Elevation Myocardial Infarction.

    PubMed

    Dharma, Surya; Hapsari, Rosmarini; Siswanto, Bambang B; van der Laarse, Arnoud; Jukema, J Wouter

    2015-06-01

    We aim to test the hypothesis that blood leukocyte count adds prognostic information in patients with acute non-ST-elevation myocardial infarction (non-STEMI). A total of 585 patients with acute non-STEMI (thrombolysis in myocardial infarction risk score ≥ 3) were enrolled in this cohort retrospective study. Blood leukocyte count was measured immediately after admission in the emergency department. The composite of death, reinfarction, urgent revascularization, and stroke during hospitalization were defined as the primary end point of the study. The mean age of the patients was 61 ± 9.6 years and most of them were male (79%). Using multivariate Cox regression analysis involving seven variables (history of smoking, hypertension, heart rate > 100 beats/minute, serum creatinine level > 1.5 mg/dL, blood leukocyte count > 11,000/µL, use of β-blocker, and use of angiotensin-converting enzyme inhibitor), leukocyte count > 11,000/µL demonstrated to be a strong predictor of the primary end point (hazard ratio = 3.028; 95% confidence interval = 1.69-5.40, p < 0.001). The high blood leukocyte count on admission is an independent predictor of cardiovascular events in patients with acute non-STEMI. PMID:26060384

  9. Photoacoustic assessment of oxygen saturation: effect of red blood cell aggregation

    NASA Astrophysics Data System (ADS)

    Hysi, Eno; Saha, Ratan K.; Kolios, Michael C.

    2013-03-01

    The simultaneous photoacoustic assessment of oxygen saturation and red blood cell aggregation is presented. Aggregation was induced on porcine red blood cells using Dextran-70 at multiple hematocrit levels. Samples were exposed to 750 nm and 1064 nm for each hematocrit and aggregate size in order to compute the oxygen saturation. As the size of the aggregate increased, the photoacoustic signal amplitude increased monotonically. The same trend was observed for increasing hematocrit at each aggregation level. The oxygen saturation of aggregated samples was 30% higher than non-aggregated samples at each hematocrit level. This suggests that the presence of red blood cell aggregates impairs the release of oxygen to the surrounding environment. Such a result has important implications for detecting red blood cell aggregation non-invasively and making clinical decisions based on the simulatenous assessment of oxygen saturation.

  10. [Studying the influence of some reactive oxygen species on physical and chemical parameters of blood].

    PubMed

    Martusevich, A K; Martusevich, A A; Solov'eva, A G; Peretyagin, S P

    2014-01-01

    The aim of this work was to estimate the dynamics of blood physical and chemical parameters when blood specimens were processed by singlet oxygen in vitro. Our experiments were executed with whole blood specimens of healthy people (n=10). Each specimen was divided into five separate portions of 5 ml. The first portion was a control (without any exposures). The second one was processed by an oxygen-ozone mixture (at ozone concentration of 500 mcg/l, the third portion--by oxygen, and the fourth and fifth ones were processed by a gas mixture with singlet oxygen (50 and 100% of generator power). In blood samples after processing we studied the activity of lactate dehydrogenase, aldehyde dehydrogenase and superoxide dismutase, erythrocyte and plasma levels of glucose and lactate, acid-base balance and the partial pressure of gases in blood. It was found out, that blood processing by singlet oxygen leads to optimization of energy, detoxication and antioxidant enzymes functioning with changes in plasma and erythrocyte level of glucose and lactate, normalization of blood gases level and acid-base balance. Our results show, that the effect of singlet oxygen on enzyme activity is more pronounced than exposure to an oxygen-ozone gas mixture. PMID:25702489

  11. A numerical model of blood oxygenation during veno-venous ECMO: analysis of the interplay between blood oxygenation and its delivery parameters.

    PubMed

    Messai, Elmi; Bouguerra, Abdesselam; Harmelin, Guy; Di Lascio, Gabriella; Bonizzoli, Manuela; Bonacchi, Massimo

    2016-06-01

    Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is an important tool in the management of most severe forms of acute respiratory failure. The determinants and management of oxygen delivery in patients treated with VV-ECMO is a complex topic. The physiological principles of oxygenation on VV-ECMO are reviewed in many textbooks. However a numerical model is an additional instrument to be used in understanding and exploring this intricate subject matter. We present a numerical model of blood oxygenation during VV-ECMO. Using this model we examined the role and impact of each determinant on blood oxygenation. The numerical analysis of variation and interplay between each oxygenation determinants during VV-ECMO is presented in graphical form. These results corroborate all the findings of previous studies. The proposed numerical model facilitates understanding of oxygenation physiology during VV-ECMO; it can be used for a medical simulation system and for teaching the principles of oxygenation during VV-ECMO. PMID:26091774

  12. A model for oxygen-dependent backscattering spectroscopic contrast from single red blood cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Rongrong; Yi, Ji; Chen, Siyu; Zhang, Hao F.; Backman, Vadim

    2016-03-01

    The oxygen-dependent absorption of hemoglobin provides the fundamental contrast for all label-free techniques measuring blood oxygenation. When hemoglobin is packaged into red blood cells (RBCs), the structure of the cells creates light scattering which also depends on the absorption based on the Kramers-Kronig relationship. Thus a proper characterization of the optical behaviors of blood has been a key to any accurate measurement of blood oxygenation, particularly at the capillary level where RBCs are dispersed individually in contrast to a densely packed whole blood. Here we provided a theoretical model under Born Approximation to characterize the oxygen dependent backscattering spectroscopic contrast from single RBCs. Using this theoretical model, we conducted simulations on both oxygenated and deoxygenated single RBCs with different sizes for standard and possible deformed cell geometries in blood flow, all which suggested similar backscattering spectroscopic contrast and were confirmed by Mie Theory and experiments using visible Optical Coherence Tomography (visOCT). As long as the cell size satisfies Gaussian distribution with a coefficient variance (C.V.) large enough, there is clear absorption contrast between the backscattering spectra of oxygenated and deoxygenated single RBCs calculated by this model, so oxygen saturation can then be characterized. Thus, this theoretical model can be extended to extract absorption features of other scattering particles as long as they satisfy Born Approximation.

  13. Myocardial uptake of thallium and rubidium during alterations in perfusion and oxygenation in isolated rabbit hearts

    SciTech Connect

    Leppo, J.A.

    1987-05-01

    The comparative effects of altered cellular function and coronary perfusion on myocardial /sup 201/Tl and /sup 83/Rb uptake were evaluated in three groups of isolated rabbit hearts having isovolumic contractions. Paired-indication dilution experiments were performed with /sup 201/Tl, /sup 83/Rb, and /sup 111/In-labeled albumin as an intravascular reference marker. In Group A hearts (n = 12), isotope transport was determined during control, hypoxia, and ischemia. In Group B hearts (n = 8), isotope transport was measured at control flow and again at a 50% and 80% reduction. In Group C hearts (n = 8) only /sup 201/Tl uptake was determined at control and following coronary reperfusion. Myocardial /sup 201/Tl and /sup 83/Rb transport were not significantly different and were proportional to flow. Although all interventions caused significant hemodynamic alterations, neither tracer was affected by hypoxia at constant flow. Thallium-201 permeation, however, was transiently decreased immediately after coronary reperfusion. We conclude that myocardial uptake of /sup 201/Tl and /sup 83/Rb are similar and directly related to flow, but do not reflect hypoxia induced cellular dysfunction.

  14. Oxygen cycling to improve survival of stem cells for myocardial repair: A review.

    PubMed

    Dall, Christopher; Khan, Mahmood; Chen, Chun-An; Angelos, Mark G

    2016-05-15

    Heart disease represents the leading cause of death among Americans. There is currently no clinical treatment to regenerate viable myocardium following myocardial infarction, and patients may suffer progressive deterioration and decreased myocardial function from the effects of remodeling of the necrotic myocardium. New therapeutic strategies hold promise for patients who suffer from ischemic heart disease by directly addressing the restoration of functional myocardium following death of cardiomyocytes. Therapeutic stem cell transplantation has shown modest benefit in clinical human trials with decreased fibrosis and increased functional myocardium. Moreover, autologous transplantation holds the potential to implement these therapies while avoiding the immunomodulation concerns of heart transplantation. Despite these benefits, stem cell therapy has been characterized by poor survival and low engraftment of injected stem cells. The hypoxic tissue environment of the ischemic/infracting myocardium impedes stem cell survival and engraftment in myocardial tissue. Hypoxic preconditioning has been suggested as a viable strategy to increase hypoxic tolerance of stem cells. A number of in vivo and in vitro studies have demonstrated improved stem cell viability by altering stem cell secretion of protein signals and up-regulation of numerous paracrine signaling pathways that affect inflammatory, survival, and angiogenic signaling pathways. This review will discuss both the mechanisms of hypoxic preconditioning as well as the effects of hypoxic preconditioning in different cell and animal models, examining the pitfalls in current research and the next steps into potentially implementing this methodology in clinical research trials. PMID:27091653

  15. Differential effects of octanoate and heptanoate on myocardial metabolism during extracorporeal membrane oxygenation in an infant swine model.

    PubMed

    Kajimoto, Masaki; Ledee, Dolena R; Olson, Aaron K; Isern, Nancy G; Des Rosiers, Christine; Portman, Michael A

    2015-10-01

    Nutritional energy support during extracorporeal membrane oxygenation (ECMO) should promote successful myocardial adaptation and eventual weaning from the ECMO circuit. Fatty acids (FAs) are a major myocardial energy source, and medium-chain FAs (MCFAs) are easily taken up by cell and mitochondria without membrane transporters. Odd-numbered MCFAs supply carbons to the citric acid cycle (CAC) via anaplerotic propionyl-CoA as well as acetyl-CoA, the predominant β-oxidation product for even-numbered MCFA. Theoretically, this anaplerotic pathway enhances carbon entry into the CAC, and provides superior energy state and preservation of protein synthesis. We tested this hypothesis in an immature swine model undergoing ECMO. Fifteen male Yorkshire pigs (26-45 days old) with 8-h ECMO received either normal saline, heptanoate (odd-numbered MCFA), or octanoate (even-numbered MCFA) at 2.3 μmol·kg body wt(-1)·min(-1) as MCFAs systemically during ECMO (n = 5/group). The 13-carbon ((13)C)-labeled substrates ([2-(13)C]lactate, [5,6,7-(13)C3]heptanoate, and [U-(13)C6]leucine) were systemically infused as metabolic markers for the final 60 min before left ventricular tissue extraction. Extracted tissues were analyzed for the (13)C-labeled and absolute concentrations of metabolites by nuclear magnetic resonance and gas chromatography-mass spectrometry. Octanoate produced markedly higher myocardial citrate concentration, and led to a higher [ATP]-to-[ADP] ratio compared with other groups. Unexpectedly, octanoate and heptanoate increased the flux of propionyl-CoA relative to acetyl-CoA into the CAC compared with control. MCFAs promoted increases in leucine oxidation, but were not associated with a difference in protein synthesis rate. In conclusion, octanoate provides energetic advantages to the heart over heptanoate. PMID:26232235

  16. Differential Effects Of Octanoate And Heptanoate On Myocardial Metabolism During Extracorporeal Membrane Oxygenation In An Infant Swine Model

    SciTech Connect

    Kajimoto, Masaki; Ledee, Dolena R.; Isern, Nancy G.; Olson, Aaron; Des Rosiers, Christine; Portman, Michael A.

    2015-10-01

    Background: Nutritional energy support during extracorporeal membrane oxygenation (ECMO) should promote successful myocardial adaptation and eventual weaning from the ECMO circuit. Fatty acids (FAs) are a major myocardial energy source, and medium-chain FAs (MCFAs) are easily taken up by cell and mitochondria without membrane transporters. Oddnumbered MCFAs supply carbons to the citric acid cycle (CAC) via anaplerotic propionyl-CoA as well as acetyl-CoA, the predominant betaoxidation product for even-numbered MCFA. Theoretically, this anaplerotic pathway enhances carbon entry into the CAC, and provides superior energy state and preservation of protein synthesis. We tested this hypothesis in an immature swine model undergoing ECMO. Methods: Fifteen male Yorkshire pigs (26-45 days old) with 8-hour ECMO were received either normal saline, heptanoate (odd-numbered MCFA) or octanoate (even-numbered MCFA) at 2.3 μmol/kg body wt/min as MCFAs systemically during ECMO (n = 5 per group). The 13-Carbon (13C)-labeled substrates ([2-13C]lactate, [5,6,7-13C3]heptanoate and [U-13C6]leucine) were systemically infused as metabolic markers for the final 60 minutes before left ventricular tissue extraction. Extracted tissues were analyzed for the 13C-labeled and absolute concentrations of metabolites by nuclear magnetic resonance and gas chromatography-mass spectrometry. Results: Octanoate produced markedly higher myocardial citrate concentration, and led to a higher [ATP]/[ADP] ratio compared with other http://mc.manuscriptcentral.com/jpen Journal of Parenteral and Enteral Nutrition For Peer Review groups. Unexpectedly, octanoate increased the flux of propionyl-CoA relative to acetyl-CoA into the CAC as well as heptanoate. MCFAs promoted increases in leucine oxidation, but were not associated with a difference in fractional protein synthesis rate. Conclusion: Octanoate provides energetic advantages to the heart over heptanoate, while preserving protein synthesis.

  17. The Effect of Acetazolamide on Cerebral Blood Flow and Oxygen Utilization in the Rhesus Monkey

    PubMed Central

    Laux, B. E.; Raichle, M. E.

    1978-01-01

    The brain is critically dependent for its moment to moment function and survival on an adequate supply of oxygen. The enzyme carbonic anhydrase (EC 4.2.1.1) may play an important role in oxygen delivery to brain tissue by facilitating the hydration of metabolically produced carbon dioxide in erythrocytes in brain capillaries, thus permitting the Bohr effect to occur. We examined the effect of 30 mg/kg i.v. acetazolamide, a potent inhibitor of carbonic anhydrase, upon cerebral blood flow and oxygen consumption in lightly anesthetized, passively ventilated rhesus monkeys. Cerebral blood flow and oxygen consumption were measured with oxygen-15-labeled water and oxygen-15-labeled oxyhemoglobin, respectively, injected into the internal carotid artery and monitored externally. Acetazolamide produced an immediate and significant increase in cerebral blood flow (from a mean of 64.7 to 83.8 ml/100 g per min), an increase in arterial carbon dioxide tension (from a mean of 40.7 to 47.5 torr), and a decrease in cerebral oxygen consumption (from a mean of 4.16 to 2.82 ml/100 g per min). Because the change in cerebral oxygen consumption occurred within minutes of the administration of acetazolamide, we believe that this effect probably was not due to a direct action on brain cells but was achieved by an interference with oxygen unloading in brain capillaries. A resultant tissue hypoxia might well explain part of the observed increase in cerebral blood flow. PMID:99455

  18. Comparison between the changes in muscle oxygenation and blood lactate concentration in finswimmers during incremental exercise

    NASA Astrophysics Data System (ADS)

    Wang, Bangde; Tian, Qingping; Zhang, Zhongxing; Gong, Hui

    2009-08-01

    For the purpose of comparing the response in local skeletal muscle oxygenation and blood lactate concentration during incremental exercise, 8 female finswimmers were recruited to take an incremental exercise on a cycle ergometer. Muscle oxygenation in right vastus lateralis (VL) were monitored by continuous wave near infrared spectroscopy (CW NIRS), respiratory gas exchange and blood lactate concentration ([La]b) were simultaneously measured by a metabolic system and a portable blood lactate analyzer respectively. NIRS measurements showed a muscle oxygenation index inflection point (OIip), from which the muscle oxygenation started to decrease dramatically. Significant correlations have been found between OIip and blood lactate threshold identified at the lowest [La]b value which was >0.5 mmol/L lower than that obtained at the following workload. These results might suggest that the CW NIRS measurement could be applied to monitor lactate threshold noninvasively.

  19. Comparison of blood flow models and acquisitions for quantitative myocardial perfusion estimation from dynamic CT.

    PubMed

    Bindschadler, Michael; Modgil, Dimple; Branch, Kelley R; La Riviere, Patrick J; Alessio, Adam M

    2014-04-01

    Myocardial blood flow (MBF) can be estimated from dynamic contrast enhanced (DCE) cardiac CT acquisitions, leading to quantitative assessment of regional perfusion. The need for low radiation dose and the lack of consensus on MBF estimation methods motivates this study to refine the selection of acquisition protocols and models for CT-derived MBF. DCE cardiac CT acquisitions were simulated for a range of flow states (MBF = 0.5, 1, 2, 3 ml (min g)(-1), cardiac output = 3, 5, 8 L min(-1)). Patient kinetics were generated by a mathematical model of iodine exchange incorporating numerous physiological features including heterogenenous microvascular flow, permeability and capillary contrast gradients. CT acquisitions were simulated for multiple realizations of realistic x-ray flux levels. CT acquisitions that reduce radiation exposure were implemented by varying both temporal sampling (1, 2, and 3 s sampling intervals) and tube currents (140, 70, and 25 mAs). For all acquisitions, we compared three quantitative MBF estimation methods (two-compartment model, an axially-distributed model, and the adiabatic approximation to the tissue homogeneous model) and a qualitative slope-based method. In total, over 11 000 time attenuation curves were used to evaluate MBF estimation in multiple patient and imaging scenarios. After iodine-based beam hardening correction, the slope method consistently underestimated flow by on average 47.5% and the quantitative models provided estimates with less than 6.5% average bias and increasing variance with increasing dose reductions. The three quantitative models performed equally well, offering estimates with essentially identical root mean squared error (RMSE) for matched acquisitions. MBF estimates using the qualitative slope method were inferior in terms of bias and RMSE compared to the quantitative methods. MBF estimate error was equal at matched dose reductions for all quantitative methods and range of techniques evaluated. This

  20. Comparison of blood flow models and acquisitions for quantitative myocardial perfusion estimation from dynamic CT

    NASA Astrophysics Data System (ADS)

    Bindschadler, Michael; Modgil, Dimple; Branch, Kelley R.; La Riviere, Patrick J.; Alessio, Adam M.

    2014-04-01

    Myocardial blood flow (MBF) can be estimated from dynamic contrast enhanced (DCE) cardiac CT acquisitions, leading to quantitative assessment of regional perfusion. The need for low radiation dose and the lack of consensus on MBF estimation methods motivates this study to refine the selection of acquisition protocols and models for CT-derived MBF. DCE cardiac CT acquisitions were simulated for a range of flow states (MBF = 0.5, 1, 2, 3 ml (min g)-1, cardiac output = 3, 5, 8 L min-1). Patient kinetics were generated by a mathematical model of iodine exchange incorporating numerous physiological features including heterogenenous microvascular flow, permeability and capillary contrast gradients. CT acquisitions were simulated for multiple realizations of realistic x-ray flux levels. CT acquisitions that reduce radiation exposure were implemented by varying both temporal sampling (1, 2, and 3 s sampling intervals) and tube currents (140, 70, and 25 mAs). For all acquisitions, we compared three quantitative MBF estimation methods (two-compartment model, an axially-distributed model, and the adiabatic approximation to the tissue homogeneous model) and a qualitative slope-based method. In total, over 11 000 time attenuation curves were used to evaluate MBF estimation in multiple patient and imaging scenarios. After iodine-based beam hardening correction, the slope method consistently underestimated flow by on average 47.5% and the quantitative models provided estimates with less than 6.5% average bias and increasing variance with increasing dose reductions. The three quantitative models performed equally well, offering estimates with essentially identical root mean squared error (RMSE) for matched acquisitions. MBF estimates using the qualitative slope method were inferior in terms of bias and RMSE compared to the quantitative methods. MBF estimate error was equal at matched dose reductions for all quantitative methods and range of techniques evaluated. This suggests that

  1. Near-infrared spectroscopy measurement of blood oxygenation content and its application in sports practice

    NASA Astrophysics Data System (ADS)

    Xu, Guodong; Gong, Hui; Ge, Xinfa; Luo, Qingming

    2003-12-01

    To research the change characteristics of blood oxygenation content in skeletal muscle, the change regularity between blood oxygenation content and exercise intensity as well as HbO2 and blood lactate acid while taking incremental exercises, we took an in vivo, real-time and continuous measurement on the blood oxygenation content of eight sportsmen when they did incremental exercises of five degrees on a power bicycle using a portable tissue oximeter which is based on the principle of near-infrared spectroscopy(NIRS), simultaneously, we detected the blood lactate acid of subjects after each degree of incremental physical load instantly using a blood lactate analysis equipment. The results showed that the content of HbO2 descended regularly while that of Hb ascended; blood volume decreased; and the density of lactate increased as the intensity of exercises was heightened. The statistics analyses showed that the relationship between HbO2 and blood lactate is rather close (correlation coefficient r=-0.918). With this discovery, a theoretical basis in measuring the relative change of blood oxygenation content non-invasively was evidenced, and a novel technology for assessing the physical situation of sportsman, grasping sports density and evaluating the training effect could be imported.

  2. Dual-wavelength photothermal optical coherence tomography for imaging microvasculature blood oxygen saturation

    PubMed Central

    Yin, Biwei; McElroy, Austin B.; Kazmi, Shams; Dunn, Andrew K.; Duong, Timothy Q.; Milner, Thomas E.

    2013-01-01

    Abstract. A swept-source dual-wavelength photothermal (DWP) optical coherence tomography (OCT) system is demonstrated for quantitative imaging of microvasculature oxygen saturation. DWP-OCT is capable of recording three-dimensional images of tissue and depth-resolved phase variation in response to photothermal excitation. A 1,064-nm OCT probe and 770-nm and 800-nm photothermal excitation beams are combined in a single-mode optical fiber to measure microvasculature hemoglobin oxygen saturation (SO2) levels in phantom blood vessels with a range of blood flow speeds (0 to 17  mm/s). A 50-μm-diameter blood vessel phantom is imaged, and SO2 levels are measured using DWP-OCT and compared with values provided by a commercial oximeter at various blood oxygen concentrations. The influences of blood flow speed and mechanisms of SNR phase degradation on the accuracy of SO2 measurement are identified and investigated. PMID:23640076

  3. Mechanisms of nocturnal angina pectoris: importance of increased myocardial oxygen demand in patients with severe coronary artery disease.

    PubMed

    Quyyumi, A A; Wright, C A; Mockus, L J; Fox, K M

    1984-06-01

    Changes in heart rate before and throughout episodes of ST-segment depression were recorded during ambulatory electrocardiographic monitoring in five patients with daytime and nocturnal resting angina and six patients with daytime angina only, who all had severe obstructive coronary disease. In 16 of 17 nocturnal episodes and in all the daytime episodes the heart rate increased before the onset of ST-segment depression. There were no significant differences in the sequence and magnitude of changes in daytime, nocturnal, painful, or painless episodes. The maximum heart rate during individual episodes preceded the maximum ST-segment depression by a mean 80.7 s and in the majority of episodes the heart rate returned to baseline before the ST segment. Thus, in severe coronary artery disease the mechanisms producing nocturnal resting ischaemia were apparently similar to those during daytime exertion; increased myocardial oxygen demand not coronary spasm seemed responsible for most of the episodes of nocturnal ischaemia. PMID:6144924

  4. Method of assessing blood oxygenation in microcirculation vessels based on Doppler approach

    NASA Astrophysics Data System (ADS)

    Sokolov, Vladimir G.; Korsi, Larissa V.; Egorov, Sergei Y.

    2001-06-01

    Combination of laser Doppler flowmetry and pulse oximetry methods allows for the direct assessment of oxygen supply to tissues at the microcirculatory level, namely, in that part of the vascular network where the transcapillary exchange takes place that is responsible for saturating tissues with oxygen. The microcirculation system comprises arterial and venous microvascular parts that differ in blood flow velocities. Frequency separation of the photodetector signal components related to different velocity ranges makes possible to distinguish the hemodynamic processes in these two parts of the microvascular system. Moreover, numerous studies of collective oscillatory processes in hemodynamics reveal that cardio-oscillations are more pronounced in arterioles, whereas venous hemodynamics is mostly influenced by the breath rhythm. Taking account of the above phenomena allows developing a signal-filtration system for separate characterization of blood-oxygenation states in arterial and venous blood flows. Light absorbance in the skin depends on both light wavelength and blood-oxygenation level. Processing the signals obtained with a two-channel dual-wavelength (630 and 1115 nm) laser Doppler flowmeter provides information about blood oxygenation levels at the entrance and exit of the microvascular system and allows assessing the specific levels of oxygenation levels at the entrance and exit of the microvascular system and allows assessing the specific levels of oxygen consumption in tissues. In particular, this approach allows revealing pathogenic processes resulting from hyper- and hypo-oxygenation in tissues. For instance, rapidly growing malignant tumors are characterized by intensive metabolism, rapid formation of capillaries, and active transcapillary oxygen exchange that results in higher level of oxygen diffusion into tissue, while the level of oxygen is lowered in the microvascular veins.

  5. Myocardial blood flow assessment with 82rubidium-PET imaging in patients with left bundle branch block

    PubMed Central

    Falcão, Andréa; Chalela, William; Giorgi, Maria Clementina; Imada, Rodrigo; Soares, José; Do Val, Renata; Oliveira, Marco Antonio; Izaki, Marisa; Filho, Roberto Kalil; Meneghetti, José C

    2015-01-01

    OBJECTIVES: Perfusion abnormalities are frequently seen in Single Photon Emission Computed Tomography (SPECT) when a left bundle branch block is present. A few studies have shown decreased coronary flow reserve in the left anterior descending territory, regardless of the presence of coronary artery disease. OBJECTIVE: We sought to investigate rubidium-82 (82Rb) positron emission tomography imaging in the assessment of myocardial blood flow and coronary flow reserve in patients with left bundle branch block. METHODS: Thirty-eight patients with left bundle branch block (GI), median age 63.5 years, 22 (58%) female, 12 with coronary artery disease (≥70%; GI-A) and 26 with no evidence of significant coronary artery disease (GI-B), underwent rest-dipyridamole stress 82Rb-positron emission tomography with absolute quantitative flow measurements using Cedars-Sinai software (mL/min/g). The relative myocardial perfusion and left ventricular ejection fraction were assessed in 17 segments. These parameters were compared with those obtained from 30 patients with normal 82Rb-positron emission tomography studies and without left bundle branch block (GII). RESULTS: Stress myocardial blood flow and coronary flow reserve were significantly lower in GI than in GII (p<0.05). The comparison of coronary flow reserve between GI-A and GI-B showed that it was different from the global coronary flow reserve (p<0.05) and the stress flow was significantly lower in the anterior than in the septal wall for both groups. Perfusion abnormalities were more prevalent in GI-A (p=0.06) and the left ventricular ejection fraction was not different between GI-A and GI-B, whereas it was lower in GI than in GII (p<0.001). CONCLUSION: The data confirm that patients with left bundle branch block had decreased myocardial blood flow and coronary flow reserve and coronary flow reserve assessed by 82Rb-positron emission tomography imaging may be useful in identifying coronary artery disease in patients with

  6. Notch1 Pathway Protects against Burn-Induced Myocardial Injury by Repressing Reactive Oxygen Species Production through JAK2/STAT3 Signaling

    PubMed Central

    Cai, Weixia; Yang, Xuekang; Han, Shichao; Guo, Haitao; Zheng, Zhao; Wang, Hongtao; Guan, Hao; Jia, Yanhui; Gao, Jianxin; Yang, Tao; Zhu, Xiongxiang; Hu, Dahai

    2016-01-01

    Oxidative stress plays an important role in burn-induced myocardial injury, but the cellular mechanisms that control reactive oxygen species (ROS) production and scavenging are not fully understood. This study demonstrated that blockade of Notch signaling via knockout of the transcription factor RBP-J or a pharmacological inhibitor aggravated postburn myocardial injury, which manifested as deteriorated serum CK, CK-MB, and LDH levels and increased apoptosis in vitro and in vivo. Interruption of Notch signaling increased intracellular ROS production, and a ROS scavenger reversed the exacerbated myocardial injury after Notch signaling blockade. These results suggest that Notch signaling deficiency aggravated postburn myocardial injury through increased ROS levels. Notch signaling blockade also decreased MnSOD expression in vitro and in vivo. Notably, Notch signaling blockade downregulated p-JAK2 and p-STAT3 expression. Inhibition of JAK2/STAT3 signaling with AG490 markedly decreased MnSOD expression, increased ROS production, and aggravated myocardial injury. AG490 plus GSI exerted no additional effects. These results demonstrate that Notch signaling protects against burn-induced myocardial injury through JAK2/STAT3 signaling, which activates the expression of MnSOD and leads to decreased ROS levels. PMID:27057278

  7. "Blood failure" time to view blood as an organ: how oxygen debt contributes to blood failure and its implications for remote damage control resuscitation.

    PubMed

    Bjerkvig, Christopher K; Strandenes, Geir; Eliassen, Håkon S; Spinella, Philip C; Fosse, Theodor K; Cap, Andrew P; Ward, Kevin R

    2016-04-01

    Hemorrhagic shock is both a local and systemic disorder. In the context of systemic effects, blood loss may lead to levels of reduced oxygen delivery (DO2 ) sufficient to cause tissue ischemia. Similar to other physiologic debts such as sleep, it is not possible to incur a significant oxygen debt and suffer no consequences for lack of timely repayment. While the linkage between oxygen debt and traditional organ failure (renal, hepatic, lung, and circulation) has been long recognized, we should consider failure in two additional linked and very dynamic organ systems, the endothelium and blood. These systems are very sensitive to oxygen debt and at risk for failing, having further implications on all other organ systems. The degree of damage to the endothelium is largely modulated by the degree of oxygen debt. Thus hypoperfusion is believed to begin a cascade of events leading to acute traumatic coagulopathy (ATC). This combination of oxygen debt driven endothelial damage and ATC might be considered collectively as "blood failure" due to the highly connected networks between these drivers. This article presents the implications of oxygen debt for remote damage control resuscitation strategies, such as permissive hypotension and hemostatic resuscitation. We review the impact of whole blood resuscitation and red blood cell efficacy in mitigation of oxygen debt. At last, this article recognizes the need for simple and durable, lightweight equipment that can detect the adequacy of tissue DO2 and thus patient needs for resuscitative care. Point-of-care lactate measuring may be a predictive tool for identifying high-risk trauma patients and occult shock because it provides information beyond that of vital signs and mechanism of injury as it may help predict the level of oxygen debt accumulation and need for resuscitation. Serial measurements may also be valuable as a tool in guiding resuscitative efforts. PMID:27100755

  8. Red blood cells in sports: effects of exercise and training on oxygen supply by red blood cells.

    PubMed

    Mairbäurl, Heimo

    2013-01-01

    During exercise the cardiovascular system has to warrant substrate supply to working muscle. The main function of red blood cells in exercise is the transport of O2 from the lungs to the tissues and the delivery of metabolically produced CO2 to the lungs for expiration. Hemoglobin also contributes to the blood's buffering capacity, and ATP and NO release from red blood cells contributes to vasodilation and improved blood flow to working muscle. These functions require adequate amounts of red blood cells in circulation. Trained athletes, particularly in endurance sports, have a decreased hematocrit, which is sometimes called "sports anemia." This is not anemia in a clinical sense, because athletes have in fact an increased total mass of red blood cells and hemoglobin in circulation relative to sedentary individuals. The slight decrease in hematocrit by training is brought about by an increased plasma volume (PV). The mechanisms that increase total red blood cell mass by training are not understood fully. Despite stimulated erythropoiesis, exercise can decrease the red blood cell mass by intravascular hemolysis mainly of senescent red blood cells, which is caused by mechanical rupture when red blood cells pass through capillaries in contracting muscles, and by compression of red cells e.g., in foot soles during running or in hand palms in weightlifters. Together, these adjustments cause a decrease in the average age of the population of circulating red blood cells in trained athletes. These younger red cells are characterized by improved oxygen release and deformability, both of which also improve tissue oxygen supply during exercise. PMID:24273518

  9. Whole-Body Vibration and Blood Flow and Muscle Oxygenation: A Meta-Analysis

    PubMed Central

    Games, Kenneth E.; Sefton, JoEllen M.; Wilson, Alan E.

    2015-01-01

    Context: The use and popularity of whole-body vibration (WBV) has increased in recent years, but there is a lack of consensus in the literature about the effectiveness of the treatment. Objective: To quantitatively examine the effects of WBV on muscle oxygenation and peripheral blood flow in healthy adults. Data Sources: We searched Web of Science and PubMed databases and reference lists from relevant articles using the key terms whole body vibration, whole-body vibration, WBV, blood flow, peripheral blood flow, oxygenation, muscle oxygenation, circulation, circulatory, near infrared spectroscopy, NIRS, and power Doppler. Key terms were searched using single word and combination searches. No date range was specified. Study Selection: Criteria for inclusion were (1) use of a commercially available WBV device, (2) a human research model, (3) a pre-WBV condition and at least 1 WBV experimental condition, and (4) reporting of unstandardized means and standard deviations of muscle oxygenation or peripheral blood flow. Data Extraction: Means, standard deviations, and sample sizes were extracted from the text, tables, and figures of included studies. A total of 35 and 90 data points were extracted for the muscle-oxygenation and blood-flow meta-analyses, respectively. Data for each meta-analysis were combined and analyzed using meta-analysis software. Weighted, random-effects meta-analyses using the Hedges g metric were completed for muscle oxygenation and blood flow. We then conducted follow-up analyses using the moderator variables of vibration type, vibration time, vibration frequency, measurement location, and sample type. Data Synthesis: We found 18 potential articles. Further examination yielded 10 studies meeting the inclusion criteria. Whole-body vibration was shown to positively influence peripheral blood flow. Additionally, the moderators of vibration type and frequency altered the influence of WBV on blood flow. Overall, WBV did not alter muscle oxygenation

  10. The jumbo squid, Dosidicus gigas (Ommastrephidae), living in oxygen minimum zones II: Blood-oxygen binding

    NASA Astrophysics Data System (ADS)

    Seibel, Brad A.

    2013-10-01

    Dosidicus gigas is a large, metabolically active squid that migrates across a strong oxygen and temperature gradient in the Eastern Pacific. Here we analyze the oxygen-binding properties of the squid's respiratory protein (hemocyanin, Hc) that facilitate such activity. A high Hc-oxygen affinity, strong temperature dependence, and pronounced pH sensitivity (P50=0.009T2.03, pH 7.4; Bohr coefficient=ΔlogP50/ΔpH=-1.55+0.034T) of oxygen binding facilitate night-time foraging in the upper water column, and support suppressed oxygen demand in hypoxic waters at greater depths. Expanding hypoxia may act to alter the species habitable depth range. This analysis supports the contention that ocean acidification could limit oxygen carrying capacity in squids at warmer temperature leading to reduced activity levels or altered distribution.

  11. REACTIVE OXYGEN SPECIES IN WHOLE BLOOD, BLOOD PLASMA AND BREAST MILK: VALIDATION OF A POTENTIAL MARKER OF EXPOSURE AND EFFECT

    EPA Science Inventory

    Reactive oxygen species (ROS) are recognized to contribute to the pathobiology of many diseases. We have applied a simple chemiluminescent (CL) probe to detect ROS in various biological fluids (plasma, whole blood, urine and breast milk) in an environmental arsenic drinking wate...

  12. Novel optoacoustic system for noninvasive continuous monitoring of cerebral venous blood oxygenation

    NASA Astrophysics Data System (ADS)

    Petrov, Yuriy; Petrov, Irene Y.; Prough, Donald S.; Esenaliev, Rinat O.

    2012-02-01

    Traumatic brain injury (TBI) and spinal cord injury are a major cause of death for individuals under 50 years of age. In the USA alone, 150,000 patients per year suffer moderate or severe TBI. Moreover, TBI is a major cause of combatrelated death. Monitoring of cerebral venous blood oxygenation is critically important for management of TBI patients because cerebral venous blood oxygenation below 50% results in death or severe neurologic complications. At present, there is no technique for noninvasive, accurate monitoring of this clinically important variable. We proposed to use optoacoustic technique for noninvasive monitoring of cerebral venous blood oxygenation by probing cerebral veins such as the superior sagittal sinus (SSS) and validated it in animal studies. In this work, we developed a novel, medical grade optoacoustic system for continuous, real-time cerebral venous blood oxygenation monitoring and tested it in human subjects at normal conditions and during hyperventilation to simulate changes that may occur in patients with TBI. We designed and built a highly-sensitive optoacoustic probe for SSS signal detection. Continuous measurements were performed in the near infrared spectral range and the SSS oxygenation absolute values were automatically calculated in real time using a special algorithm developed by our group. Continuous measurements performed at normal conditions and during hyperventilation demonstrated that hyperventilation resulted in approximately 12% decrease of cerebral venous blood oxygenation.

  13. A comparative study of the concentrations of hypoxanthine, xanthine, uric acid and allantoin in the peripheral blood of normals and patients with acute myocardial infarction and other ischaemic diseases.

    PubMed

    Kock, R; Delvoux, B; Sigmund, M; Greiling, H

    1994-11-01

    The aim of this study was the elucidation of the role of the xanthine oxidoreductase in the purine metabolism in ischaemic diseases of man. The serum concentrations of hypoxanthine, xanthine, uric acid and allantoin were determined in peripheral blood samples from patients with angina pectoris, cerebral insult and myocardial infarction with thrombolytic therapy and were compared with the concentrations obtained for healthy males and females. No significant differences were observed for the serum hypoxanthine concentrations, xanthine concentrations, the sum (hypoxanthine+xanthine) and the ratio (xanthine/hypoxanthine) between the healthy males, healthy females, the patients suffering from angina pectoris and the patients suffering from cerebral insult. An increase of the serum xanthine concentration in patients with myocardial infarction indicates a significant metabolic involvement of xanthine oxidoreductase in this disease and therefore a possible role in the development of tissue damage in the postischaemic phase due to oxygen radicals generated by the oxidase activity of this enzyme. The serum concentrations of uric acid and allantoin showed no differences between any of the studied groups. Study of the non-enzymatic oxidation of uric acid to allantoin by oxygen radicals, a relevant radical-scavenging mechanism in other diseases, provided no indication of an increased concentration of oxygen radicals due to the xanthine oxidoreductase reaction or other radical-producing mechanisms. PMID:7888480

  14. The Choroidal Eye Oximeter - An instrument for measuring oxygen saturation of choroidal blood in vivo

    NASA Technical Reports Server (NTRS)

    Laing, R. A.; Danisch, L. A.; Young, L. R.

    1975-01-01

    The Choroidal Eye Oximeter is an electro-optical instrument that noninvasively measures the oxygen saturation of choroidal blood in the back of the human eye by a spectrophotometric method. Since choroidal blood is characteristic of blood which is supplied to the brain, the Choroidal Eye Oximeter can be used to monitor the amount of oxygen which is supplied to the brain under varying external conditions. The instrument consists of two basic systems: the optical system and the electronic system. The optical system produces a suitable bi-chromatic beam of light, reflects this beam from the fundus of the subject's eye, and onto a low-noise photodetector. The electronic system amplifies the weak composite signal from the photodetector, computes the average oxygen saturation from the area of the fundus that was sampled, and displays the value of the computed oxygen saturation on a panel meter.

  15. Multi-modal in vivo imaging of brain blood oxygenation, blood flow and neural calcium dynamics during acute seizures

    NASA Astrophysics Data System (ADS)

    Ringuette, Dene; Jeffrey, Melanie A.; Carlen, Peter L.; Levi, Ofer

    2016-03-01

    Dysfunction of the vascular endothelium has been implicated in the development of epilepsy. To better understand the relation between vascular function and seizure and provide a foundation for interpreting results from functional imaging in chronic disease models, we investigate the relationship between intracellular calcium dynamics and local cerebral blood flow and blood oxygen saturation during acute seizure-like events and pharmacological seizure rescue. To probe the relation between the aforementioned physiological markers in an acute model of epilepsy in rats, we integrated three different optical modalities together with electrophysiological recordings: Laser speckle contrast imaging (LSCI) was used to study changes in flow speeds, Intrinsic optical signal imaging (IOSI) was used to monitor changes in oxygenated, de-oxygenated, and total hemoglobin concentration, and Calcium-sensitive dye imaging was used to monitor intracellular calcium dynamics. We designed a dedicated cortical flow chamber to remove superficial blood and dye resulting from the injection procedure, which reduced spurious artifacts. The near infrared light used for IOSI and LSCI was delivered via a light pipe integrated with the flow chamber to minimize the effect of fluid surface movement on illumination stability. Calcium-sensitive dye was injected via a glass electrode used for recording the local field potential. Our system allowed us to observe and correlate increases in intracellular calcium, blood flow and blood volume during seizure-like events and provide a quantitative analysis of neurovascular coupling changes associated with seizure rescue via injection of an anti-convulsive agent.

  16. Hematocrit and oxygenation dependence of blood (1)H(2)O T(1) at 7 Tesla.

    PubMed

    Grgac, Ksenija; van Zijl, Peter C M; Qin, Qin

    2013-10-01

    Knowledge of blood (1)H2O T1 is critical for perfusion-based quantification experiments such as arterial spin labeling and cerebral blood volume-weighted MRI using vascular space occupancy. The dependence of blood (1)H2O T1 on hematocrit fraction (Hct) and oxygen saturation fraction (Y) was determined at 7 T using in vitro bovine blood in a circulating system under physiological conditions. Blood (1)H2O R1 values for different conditions could be readily fitted using a two-compartment (erythrocyte and plasma) model, which are described by a monoexponential longitudinal relaxation rate constant dependence. It was found that T1 = 2171 ± 39 ms for Y = 1 (arterial blood) and 2010 ± 41 ms for Y = 0.6 (venous blood), for a typical Hct of 0.42. The blood (1)H2O T1 values in the normal physiological range (Hct from 0.35 to 0.45, and Y from 0.6 to 1.0) were determined to range from 1900 to 2300 ms. The influence of oxygen partial pressure (pO2) and the effect of plasma osmolality for different anticoagulants were also investigated. It is discussed why blood (1)H2O T1 values measured in vivo for human blood may be about 10-20% larger than found in vitro for bovine blood at the same field strength. PMID:23169066

  17. Smart oxygen cuvette for optical monitoring of dissolved oxygen in biological blood samples

    NASA Astrophysics Data System (ADS)

    Dabhi, Harish; Alla, Suresh Kumar; Shahriari, Mahmoud R.

    2010-02-01

    A smart Oxygen Cuvette is developed by coating the inner surface of a cuvette with oxygen sensitive thin film material. The coating is glass like sol-gel based sensor that has an embedded ruthenium compound in the glass film. The fluorescence of the ruthenium is quenched depending on the oxygen level. Ocean Optics phase fluorometer, NeoFox is used to measure this rate of fluorescence quenching and computes it for the amount of oxygen present. Multimode optical fibers are used for transportation of light from an LED source to cuvette and from cuvette to phase fluorometer. This new oxygen sensing system yields an inexpensive solution for monitoring the dissolved oxygen in samples for biological and medical applications. In addition to desktop fluorometers, smart oxygen cuvettes can be used with the Ocean Optics handheld Fluorometers, NeoFox Sport. The Smart Oxygen Cuvettes provide a resolution of 4PPB units, an accuracy of less than 5% of the reading, and 90% response in less than 10 seconds.

  18. Prolonged cold storage of red blood cells by oxygen removal and additive usage

    DOEpatents

    Bitensky, M.W.; Yoshida, Tatsuro

    1998-08-04

    Prolonged cold storage of red blood cells by oxygen removal and additive usage. A cost-effective, 4 C storage procedure that preserves red cell quality and prolongs post-transfusion in vivo survival is described. The improved in vivo survival and the preservation of adenosine triphosphate levels, along with reduction in hemolysis and membrane vesicle production of red blood cells stored at 4 C for prolonged periods of time, is achieved by reducing the oxygen level therein at the time of storage; in particular, by flushing the cells with an inert gas, and storing them in an aqueous solution which includes adenine, dextrose, mannitol, citrate ion, and dihydrogen phosphate ion, but no sodium chloride, in an oxygen-permeable container which is located in an oxygen-free environment containing oxygen-scavenging materials. 8 figs.

  19. Prolonged cold storage of red blood cells by oxygen removal and additive usage

    DOEpatents

    Bitensky, Mark W.; Yoshida, Tatsuro

    1998-01-01

    Prolonged cold storage of red blood cells by oxygen removal and additive usage. A cost-effective, 4.degree. C. storage procedure that preserves red cell quality and prolongs post-transfusion in vivo survival is described. The improved in vivo survival and the preservation of adenosine triphosphate levels, along with reduction in hemolysis and membrane vesicle production of red blood cells stored at 4.degree. C. for prolonged periods of time, is achieved by reducing the oxygen level therein at the time of storage; in particular, by flushing the cells with an inert gas, and storing them in an aqueous solution which includes adenine, dextrose, mannitol, citrate ion, and dihydrogen phosphate ion, but no sodium chloride, in an oxygen-permeable container which is located in an oxygen-free environment containing oxygen-scavenging materials.

  20. Noninvasive cerebral blood oxygenation monitoring: clinical test of multiwavelength optoacoustic system

    NASA Astrophysics Data System (ADS)

    Petrov, Y. Y.; Prough, D. S.; Petrova, I.; Patrikeev, I. A.; Cicenaite, I.; Esenaliev, R. O.

    2007-02-01

    Continuous monitoring of cerebral blood oxygenation is critically important for treatment of patients with life-threatening conditions like severe brain injury or during cardiac surgery. We designed and built a novel multiwavelength optoacoustic system for noninvasive, continuous, and accurate monitoring of cerebral blood oxygenation. We use an Optical Parametric Oscillator as a light source. We successfully tested the system in vitro as well as in vivo in large animals (sheep) through thick tissues overlying blood vessels which drain venous blood out of the brain (e.g., superior sagittal sinus or jugular vein). Here we present the results of clinical tests of the system for continuous noninvasive cerebral blood oxygenation monitoring in the internal jugular vein of healthy volunteers. We applied our custom-built optoacoustic probe (which incorporated a wide-band acoustic transducer and an optical fiber) to the neck area overlying the internal jugular vein. We performed measurements with volunteers at 18 wavelengths in the near-infrared spectral range. Despite a thick layer of overlying connective tissue and low energy used in the experiments, we recorded signals with high signal-to-noise ratios for all volunteers. We found that the temporal (independent of signal amplitude) parameters of recorded profiles for different levels of blood oxygenation correlated well with the spectrum of effective attenuation coefficients of blood.

  1. Blood Pool Segmentation Results in Superior Virtual Cardiac Models than Myocardial Segmentation for 3D Printing.

    PubMed

    Farooqi, Kanwal M; Lengua, Carlos Gonzalez; Weinberg, Alan D; Nielsen, James C; Sanz, Javier

    2016-08-01

    The method of cardiac magnetic resonance (CMR) three-dimensional (3D) image acquisition and post-processing which should be used to create optimal virtual models for 3D printing has not been studied systematically. Patients (n = 19) who had undergone CMR including both 3D balanced steady-state free precession (bSSFP) imaging and contrast-enhanced magnetic resonance angiography (MRA) were retrospectively identified. Post-processing for the creation of virtual 3D models involved using both myocardial (MS) and blood pool (BP) segmentation, resulting in four groups: Group 1-bSSFP/MS, Group 2-bSSFP/BP, Group 3-MRA/MS and Group 4-MRA/BP. The models created were assessed by two raters for overall quality (1-poor; 2-good; 3-excellent) and ability to identify predefined vessels (1-5: superior vena cava, inferior vena cava, main pulmonary artery, ascending aorta and at least one pulmonary vein). A total of 76 virtual models were created from 19 patient CMR datasets. The mean overall quality scores for Raters 1/2 were 1.63 ± 0.50/1.26 ± 0.45 for Group 1, 2.12 ± 0.50/2.26 ± 0.73 for Group 2, 1.74 ± 0.56/1.53 ± 0.61 for Group 3 and 2.26 ± 0.65/2.68 ± 0.48 for Group 4. The numbers of identified vessels for Raters 1/2 were 4.11 ± 1.32/4.05 ± 1.31 for Group 1, 4.90 ± 0.46/4.95 ± 0.23 for Group 2, 4.32 ± 1.00/4.47 ± 0.84 for Group 3 and 4.74 ± 0.56/4.63 ± 0.49 for Group 4. Models created using BP segmentation (Groups 2 and 4) received significantly higher ratings than those created using MS for both overall quality and number of vessels visualized (p < 0.05), regardless of the acquisition technique. There were no significant differences between Groups 1 and 3. The ratings for Raters 1 and 2 had good correlation for overall quality (ICC = 0.63) and excellent correlation for the total number of vessels visualized (ICC = 0.77). The intra-rater reliability was good for Rater A (ICC = 0.65). Three models were successfully printed

  2. Cardiac resynchronization therapy and AV optimization increase myocardial oxygen consumption, but increase cardiac function more than proportionally☆

    PubMed Central

    Kyriacou, Andreas; Pabari, Punam A.; Mayet, Jamil; Peters, Nicholas S.; Davies, D. Wyn; Lim, P. Boon; Lefroy, David; Hughes, Alun D.; Kanagaratnam, Prapa; Francis, Darrel P.; I.Whinnett, Zachary

    2014-01-01

    Background The mechanoenergetic effects of atrioventricular delay optimization during biventricular pacing (“cardiac resynchronization therapy”, CRT) are unknown. Methods Eleven patients with heart failure and left bundle branch block (LBBB) underwent invasive measurements of left ventricular (LV) developed pressure, aortic flow velocity-time-integral (VTI) and myocardial oxygen consumption (MVO2) at 4 pacing states: biventricular pacing (with VV 0 ms) at AVD 40 ms (AV-40), AVD 120 ms (AV-120, a common nominal AV delay), at their pre-identified individualised haemodynamic optimum (AV-Opt); and intrinsic conduction (LBBB). Results AV-120, relative to LBBB, increased LV developed pressure by a mean of 11(SEM 2)%, p = 0.001, and aortic VTI by 11(SEM 3)%, p = 0.002, but also increased MVO2 by 11(SEM 5)%, p = 0.04. AV-Opt further increased LV developed pressure by a mean of 2(SEM 1)%, p = 0.035 and aortic VTI by 4(SEM 1)%, p = 0.017. MVO2 trended further up by 7(SEM 5)%, p = 0.22. Mechanoenergetics at AV-40 were no different from LBBB. The 4 states lay on a straight line for Δexternal work (ΔLV developed pressure × Δaortic VTI) against ΔMVO2, with slope 1.80, significantly > 1 (p = 0.02). Conclusions Biventricular pacing and atrioventricular delay optimization increased external cardiac work done but also myocardial oxygen consumption. Nevertheless, the increase in cardiac work was ~ 80% greater than the increase in oxygen consumption, signifying an improvement in cardiac mechanoenergetics. Finally, the incremental effect of optimization on external work was approximately one-third beyond that of nominal AV pacing, along the same favourable efficiency trajectory, suggesting that AV delay dominates the biventricular pacing effect — which may therefore not be mainly “resynchronization”. PMID:24332598

  3. Massive Pulmonary Embolism Mimicking Acute Myocardial Infarction: Successful use of extracorporeal membrane oxygenation support as bridge to diagnosis.

    PubMed

    Hsieh, Yung-Kun; Siao, Fu-Yuan; Chiu, Chun-Chieh; Yen, Hsu-Heng; Chen, Yao-Li

    2016-07-01

    Prolonged cardiac arrest with pulseless electrical activity (PEA) results in death if its aetiology cannot be corrected immediately. We describe the case of a 75-year-old man with chest pain and his electrocardiogram (ECG) revealing ST-segment elevation in leads II, III, and aVf. Inferior wall myocardial infarction was subsequently diagnosed. Before performing emergency coronary angiography, however, a sudden cardiac arrest with PEA developed and the patient was placed on advanced cardiac life support. Oxygenation support for the extracorporeal membrane was initiated approximately 65min after prolonged cardiopulmonary resuscitation. Emergency coronary arteriogram showed no obstructive lesions in the right coronary artery. This result, however, was not consistent with the ECG findings, and thus, a massive pulmonary embolism was suspected. Subsequent pulmonary artery angiography showed severe emboli in bilateral branches of the pulmonary arteries. Catheter-directed thrombolysis with urokinase was administered, which ultimately failed, and surgical embolectomy was performed with extracorporeal membrane oxygenation support. After the above intervention, the patient was discharged on hospital day 60 without any sequelae or neurological deficits. PMID:26935163

  4. Effects of i.v. amino acids on human splanchnic and whole body oxygen consumption, blood flow, and blood temperatures.

    PubMed

    Brundin, T; Wahren, J

    1994-03-01

    The thermic effect of amino acid administration was examined in healthy subjects. Pulmonary and splanchnic oxygen uptake, cardiac output, splanchnic blood flow, and blood temperatures were measured in eight healthy men before and during 2.5 h of intravenous infusion of 600 kJ of a mixture of 19 amino acids. Indirect calorimetry and catheter techniques were used, including thermometry in arterial and a hepatic venous blood. During the infusion, pulmonary oxygen uptake rose progressively from a basal value of 269 +/- 6 to 321 +/- 8 ml/min after 2.5 h. The splanchnic oxygen consumption increased from a basal level of 64 +/- 4 to a peak value of 91 +/- 7 ml/min after 2 h of infusion. The 2.5 h average splanchnic proportion of the amino acid-induced whole body thermogenesis was 51 +/- 11%. Cardiac output increased from 6.2 +/- 0.3 in the basal state to 7.3 +/- 0.4 l/min, whereas the splanchnic blood flow remained unchanged during the infusion period. The arteriohepatic venous oxygen difference increased from 51 +/- 4 in the basal state to 65 +/- 5 ml/l after 2 h of amino acid infusion. The blood temperature rose by approximately 0.25 degrees C during the amino acid infusion, reflecting an increased heat accumulation in the body. It is concluded that the splanchnic tissues account for approximately one-half of the amino acid-induced whole body thermogenesis, that amino acid infusion augments blood flow in the extrasplanchnic but not in the splanchnic tissues, and stimulates the accumulation of heat in the body most likely via a resetting of the central thermosensors. PMID:8166259

  5. Ambulatory 24-hour cardiac oxygen consumption and blood pressure-heart rate variability: effects of nebivolol and valsartan alone and in combination.

    PubMed

    Izzo, Joseph L; Khan, Safi U; Saleem, Osman; Osmond, Peter J

    2015-07-01

    We compared an angiotensin receptor blocker (valsartan; VAL), a beta-blocker (nebivolol; NEB) and the combination of NEB/VAL with respect to 24-hour myocardial oxygen consumption (determined by 24-hour ambulatory heart rate-central systolic pressure product [ACRPP]) and its components. Subjects with hypertension (systolic blood pressure >140 or diastolic blood pressure >90; n = 26) were studied in a double-blinded, double-dummy, forced-titration, crossover design with 3 random-order experimental periods: VAL 320 mg, NEB 40 mg, and NEB/VAL 320/40 mg daily. After 4 weeks of each drug, ambulatory pulse wave analysis (MobilOGraph) was performed every 20 minutes for 24 hours. All three treatments resulted in nearly identical brachial and central systolic blood pressures. NEB alone or in combination with VAL resulted in lower ACRPP (by 11%-14%; P < .001 each) and heart rate (by 18%-20%; P < .001 each) compared with VAL, but stroke work (ACRPP per beat) was lower with VAL. Relative and adjusted variability (standard deviation and coefficient of variation) of heart rate were also lower with NEB and NEB/VAL than VAL. Results in African Americans, the majority subpopulation, were similar to those of the entire treatment group. We conclude that the rate-slowing effects of NEB cause ambulatory cardiac myocardial oxygen consumption to be lower with NEB monotherapy or NEB/VAL combination therapy than with VAL monotherapy. NEB/VAL is not superior to NEB alone in controlling heart rate, blood pressure, or ACRPP. Heart rate variability but not ACRPP variability is reduced by NEB or the combination NEB/VAL. There is no attenuation of beta-blocker-induced rate-slowing effects of in African Americans. PMID:26116459

  6. Reproducibility and Accuracy of Quantitative Myocardial Blood Flow Using 82Rb-PET: Comparison with 13N-Ammonia

    PubMed Central

    Fakhri, Georges El

    2011-01-01

    82Rb cardiac PET allows the assessment of myocardial perfusion using a column generator in clinics that lack a cyclotron. We and others have previously shown that quantitation of myocardial blood flow (MBF) and coronary flow reserve (CFR) is feasible using dynamic 82Rb PET and factor and compartment analyses. The aim of the present work was to determine the intra- and inter-observer variability of MBF estimation using 82Rb PET as well as the reproducibility of our generalized factor + compartment analyses methodology to estimate MBF and assess its accuracy by comparing, in the same subjects, 82Rb estimates of MBF to those obtained using 13N-ammonia. Methods Twenty-two subjects were included in the reproducibility and twenty subjects in the validation study. Patients were injected with 60±5mCi of 82Rb and imaged dynamically for 6 minutes at rest and during dipyridamole stress Left and right ventricular (LV+RV) time-activity curves were estimated by GFADS and used as input to a 2-compartment kinetic analysis that estimates parametric maps of myocardial tissue extraction (K1) and egress (k2), as well as LV+RV contributions (fv,rv). Results Our results show excellent reproducibility of the quantitative dynamic approach itself with coefficients of repeatability of 1.7% for estimation of MBF at rest, 1.4% for MBF at peak stress and 2.8% for CFR estimation. The inter-observer reproducibility between the four observers that participated in this study was also very good with correlation coefficients greater than 0.87 between any two given observers when estimating coronary flow reserve. The reproducibility of MBF in repeated 82Rb studies was good at rest and excellent at peak stress (r2=0.835). Furthermore, the slope of the correlation line was very close to 1 when estimating stress MBF and CFR in repeated 82Rb studies. The correlation between myocardial flow estimates obtained at rest and during peak stress in 82Rb and 13N-ammonia studies was very good at rest (r2

  7. Overexpression of MMP-9 and Its Inhibitors in Blood Mononuclear Cells after Myocardial Infarction - Is It Associated with Depressive Symptomatology?

    PubMed Central

    Jönsson, Simon; Lundberg, Anna K.; Jonasson, Lena

    2014-01-01

    Background Matrix metalloproteinase (MMP)-9 may play a central role in the development and progression of atherosclerosis. Emerging evidence also indicates an association between MMP-9 and depressive symptomatology. Here, we investigated whether expression of MMP-9 and its inhibitors in blood mononuclear cells and plasma were related to depressive symptoms in patients with a recent myocardial infarction (MI). Methods and Results Blood sampling was performed between 6 and 18 months after MI in 57 patients. Forty-one clinically healthy subjects were included as controls. Gene expression of MMP-9 and its main tissue inhibitors TIMP-1 and -2 were analyzed in freshly isolated or cultured blood mononuclear cells. Corresponding protein levels were assessed in cell supernatants and plasma. In post-MI patients, mRNA levels of MMP-9 and TIMP-1 and -2 were significantly higher than in controls while protein levels in cell supernatants and plasma did not differ between groups. The Center for Epidemiological Studies - Depression (CES-D) scale was used to assess depressive symptomatology. Repeated assessments during the first 18 months after MI showed significantly higher CES-D scores in patients compared with controls. However, there were no relationships between depressive mood and any of the measurements of MMP-9 or TIMPs. Conclusion Our findings indicate that overexpression of MMP-9 and TIMPs in blood mononuclear cells and elevated depressive symptoms represent two unrelated phenomena after MI. PMID:25153995

  8. Noninvasive optical characterization of muscle blood flow, oxygenation, and metabolism in women with fibromyalgia

    PubMed Central

    2012-01-01

    Introduction Women with fibromyalgia (FM) have symptoms of increased muscular fatigue and reduced exercise tolerance, which may be associated with alterations in muscle microcirculation and oxygen metabolism. This study used near-infrared diffuse optical spectroscopies to noninvasively evaluate muscle blood flow, blood oxygenation and oxygen metabolism during leg fatiguing exercise and during arm arterial cuff occlusion in post-menopausal women with and without FM. Methods Fourteen women with FM and twenty-three well-matched healthy controls participated in this study. For the fatiguing exercise protocol, the subject was instructed to perform 6 sets of 12 isometric contractions of knee extensor muscles with intensity steadily increasing from 20 to 70% maximal voluntary isometric contraction (MVIC). For the cuff occlusion protocol, forearm arterial blood flow was occluded via a tourniquet on the upper arm for 3 minutes. Leg or arm muscle hemodynamics, including relative blood flow (rBF), oxy- and deoxy-hemoglobin concentration ([HbO2] and [Hb]), total hemoglobin concentration (THC) and blood oxygen saturation (StO2), were continuously monitored throughout protocols using a custom-built hybrid diffuse optical instrument that combined a commercial near-infrared oximeter for tissue oxygenation measurements and a custom-designed diffuse correlation spectroscopy (DCS) flowmeter for tissue blood flow measurements. Relative oxygen extraction fraction (rOEF) and oxygen consumption rate (rVO2) were calculated from the measured blood flow and oxygenation data. Post-manipulation (fatiguing exercise or cuff occlusion) recovery in muscle hemodynamics was characterized by the recovery half-time, a time interval from the end of manipulation to the time that tissue hemodynamics reached a half-maximal value. Results Subjects with FM had similar hemodynamic and metabolic response/recovery patterns as healthy controls during exercise and during arterial occlusion. However, tissue r

  9. Cells Expressing Early Cardiac Markers Reside in the Bone Marrow and Are Mobilized Into the Peripheral Blood After Myocardial Infarction

    PubMed Central

    Kucia, Magda; Dawn, Buddhadeb; Hunt, Greg; Guo, Yiru; Wysoczynski, Marcin; Majka, Marcin; Ratajczak, Janina; Rezzoug, Francine; Ildstad, Suzanne T.; Bolli, Roberto; Ratajczak, Mariusz Z.

    2013-01-01

    The concept that bone marrow (BM)– derived cells participate in cardiac regeneration remains highly controversial and the identity of the specific cell type(s) involved remains unknown. In this study, we report that the postnatal BM contains a mobile pool of cells that express early cardiac lineage markers (Nkx2.5/Csx, GATA-4, and MEF2C). These cells are present in significant amounts in BM harvested from young mice but their abundance decreases with age; in addition, the responsiveness of these cells to gradients of motomorphogens SDF-1, HGF, and LIF changes with age. FACS analysis, combined with analysis of early cardiac markers at the mRNA and protein levels, revealed that cells expressing these markers reside in the nonadherent, nonhematopoietic CXCR4+/Sca-1+/lin−/CD45− mononuclear cell (MNC) fraction in mice and in the CXCR4+/CD34+/AC133+/CD45− BMMNC fraction in humans. These cells are mobilized into the peripheral blood after myocardial infarction and chemoattracted to the infarcted myocardium in an SDF-1-CXCR4 −, HGF-c-Met−, and LIF-LIF-R− dependent manner. To our knowledge, this is the first demonstration that the postnatal BM harbors a nonhematopoietic population of cells that express markers for cardiac differentiation. We propose that these potential cardiac progenitors may account for the myocardial regenerative effects of BM. The present findings provide a novel paradigm that could reconcile current controversies and a rationale for investigating the use of BM-derived cardiac progenitors for myocardial regeneration. PMID:15550692

  10. Impact of High-Normal Blood Pressure Measured in Emergency Room on Adverse Cardiac Events in Acute Myocardial Infarction

    PubMed Central

    Yoon, Nam Sik; Ahn, Youngkeun; Kim, Jong Hyun; Chae, Shung Chull; Kim, Young Jo; Hur, Seung Ho; Seong, In Whan; Hong, Taek Jong; Choi, Donghoon; Cho, Myeong Chan; Kim, Chong Jin; Seung, Ki Bae; Chung, Wook Sung; Jang, Yang Soo; Cho, Jeong Gwan; Park, Seung Jung

    2012-01-01

    Background and Objectives Prehypertension according to JNC7 is common and is associated with increased vascular mortality. The importance of management in high-normal blood pressure (BP) is underemphasized. Subjects and Methods We analyzed major adverse cardiac events (MACEs) in the Korea Acute Myocardial Infarction Registry in normal BP (group I) and high-normal BP (group II) patients. Results Among 14871 patients, 159 (61±12.3 years, 122 males) satisfied the study indication. Six-month and one-year clinical follow-up rate was 88.9% and 85.8%, respectively. Group I had 78 patients (60.9±12.4 years). Group II had 81 patients (61.6±12.5 years). Demographics of patients were not different between groups. Treatment strategy was not different. Initial Thrombolysis in Myocardial Infarction flow grade 0 was less frequent in group II (n=32, 47.1%) than in group I (n=16, 21.9%) (p=0.001). Successful intervention rate was not different between group II (93.8%) and group I (97.1%) (p=0.590). Six-month MACE occurred in 3 patients in group I (4.4%) and 10 in group II (15.6%) (p=0.031). Compared with normal BP, the odds ratio for patients with high-normal BP was 1.147 (p=0.045, 95% confidence interval 1.011-1.402) for 6-month MACE. Conclusion Even though high-normal BP patients had a better baseline clinical status, the prognosis was poorer than patients with normal BP. Therapeutic BP target goal for the patients with acute myocardial infarction should be <140/90 mm Hg, which is recommended in JNC7. PMID:22701132

  11. Image-guided optical measurement of blood oxygen saturation within capillary vessels (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Akons, Kfir; Zeidan, Adel; Yeheskely-Hayon, Daniella; Minai, Limor; Yelin, Dvir

    2016-03-01

    Values of blood oxygenation levels are useful for assessing heart and lung conditions, and are frequently monitored during routine patient care. Independent measurement of the oxygen saturation in capillary blood, which is significantly different from that of arterial blood, is important for diagnosing tissue hypoxia and for increasing the accuracy of existing techniques that measure arterial oxygen saturation. Here, we developed a simple, non-invasive technique for measuring the reflected spectra from individual capillary vessels within a human lip, allowing local measurement of the blood oxygen saturation. The optical setup includes a spatially incoherent broadband light that was focused onto a specific vessel below the lip surface. Backscattered light was imaged by a camera for identifying a target vessel and pointing the illumination beam to its cross section. Scattered light from the vessel was then collected by a single-mode fiber and analyzed by a fast spectrometer. Spectra acquired from small capillary vessels within a volunteer lip showed the characteristic oxyhemoglobin absorption bands in real time and with a high signal-to-noise ratio. Measuring capillary oxygen saturation using this technique would potentially be more accurate compared to existing pulse oximetry techniques due to its insensitivity to the patient's skin color, pulse rate, motion, and medical condition. It could be used as a standalone endoscopic technique for measuring tissue hypoxia or in conjunction with conventional pulse oximetry for a more accurate measurement of oxygen transport in the body.

  12. Blood oxygen binding properties for the burrowing owl, Athene cunicularia.

    PubMed

    Maginniss, L A; Kilgore, D L

    1989-05-01

    Isocapnic O2 equilibrium curves (O2ECs) were generated for whole blood of 4 adult burrowing owls (Athene cunicularia) using thin film techniques. At in vivo pHa (7.49 +/- 0.02; mean +/- 1 SEM) and 41 degrees C, the PO2 at half saturation (P50) was 42.3 +/- 0.8 Torr. CO2 and fixed acid (H+) Bohr slopes (delta log P50/delta pH) were -0.46 +/- 0.01 and -0.42 +/- 0.02, respectively, demonstrating a small specific CO2 effect. CO2 and H+ Bohr slopes were saturation-independent between 0.1 and 0.9 S. Hill plots for Athene blood were non-linear; the Hill coefficient (n) increased from 2.6 below 0.4 S to 3.4 above 0.6 S. Owl equilibrium data were accurately described by the equation: S = [(7.7 x 10(6]/(P4 + 44P3 - 108P2 + 3.5 x 10(4)P) + 1]-1. This complex O2EC shape may result from Hb heterogeneity; isoelectric focusing showed 4 isoHbs with a molar ratio of 9:1:1:1. This study revealed no apparent adaptations of Athene blood for hypoxic and hypercapnic conditions. We conclude that the observed blood O2 binding properties promote tissue O2 delivery during periods of surface activity. While occupying its burrow, the owl compensates for moderate alterations in inspired gas composition partly through increased ventilation. PMID:2749025

  13. Reoxygenation‐Derived Toxic Reactive Oxygen/Nitrogen Species Modulate the Contribution of Bone Marrow Progenitor Cells to Remodeling After Myocardial Infarction

    PubMed Central

    Moldovan, Nicanor I.; Anghelina, Mirela; Varadharaj, Saradhadevi; Butt, Omer I.; Wang, Tiangshen; Yang, Fuchun; Moldovan, Leni; Zweier, Jay L.

    2014-01-01

    Background The core region of a myocardial infarction is notoriously unsupportive of cardiomyocyte survival. However, there has been less investigation of the potentially beneficial spontaneous recruitment of endogenous bone marrow progenitor cells (BMPCs) within infarcted areas. In the current study we examined the role of tissue oxygenation and derived toxic species in the control of BMPC engraftment during postinfarction heart remodeling. Methods and Results For assessment of cellular origin, local oxygenation, redox status, and fate of cells in the infarcted region, myocardial infarction in mice with or without LacZ+ bone marrow transplantation was induced by coronary ligation. Sham‐operated mice served as controls. After 1 week, LacZ+ BMPC‐derived cells were found inhomogeneously distributed into the infarct zone, with a lower density at its core. Electron paramagnetic resonance (EPR) oximetry showed that pO2 in the infarct recovered starting on day 2 post–myocardial infarction, concomitant with wall thinning and erythrocytes percolating through muscle microruptures. Paralleling this reoxygenation, increased generation of reactive oxygen/nitrogen species was detected at the infarct core. This process delineated a zone of diminished BMPC engraftment, and at 1 week infiltrating cells displayed immunoreactive 3‐nitrotyrosine and apoptosis. In vivo treatment with a superoxide dismutase mimetic significantly reduced reactive oxygen species formation and amplified BMPC accumulation. This treatment also salvaged wall thickness by 43% and left ventricular ejection fraction by 27%, with significantly increased animal survival. Conclusions BMPC engraftment in the infarct inversely mirrored the distribution of reactive oxygen/nitrogen species. Antioxidant treatment resulted in increased numbers of engrafted BMPCs, provided functional protection to the heart, and decreased the incidence of myocardial rupture and death. PMID:24419735

  14. A dynamic model of oxygen transport from capillaries to tissue with moving red blood cells.

    PubMed

    Lücker, Adrien; Weber, Bruno; Jenny, Patrick

    2015-02-01

    Most oxygen required to support the energy needs of vertebrate tissues is delivered by diffusion from microvessels. The presence of red blood cells (RBCs) makes blood flow in the microcirculation highly heterogeneous. Additionally, flow regulation mechanisms dynamically respond to changes in tissue energy demand. These spatiotemporal variations directly affect the supply of oxygen to parenchymal cells. Due to various limiting assumptions, current models of oxygen transport cannot fully capture the consequences of complex hemodynamic effects on tissue oxygenation and are often not suitable for studying unsteady phenomena. With our new approach based on moving RBCs, the impact of blood flow heterogeneity on oxygen partial pressure (Po2) in the tissue can be quantified. Oxygen transport was simulated using parachute-shaped solid RBCs flowing through a capillary. With the use of a conical tissue domain with radii 19 and 13 μm, respectively, our computations indicate that Po2 at the RBC membrane exceeds Po2 between RBCs by 30 mmHg on average and that the mean plasma Po2 decreases by 9 mmHg over 50 μm. These results reproduce well recent intravascular Po2 measurements in the rodent brain. We also demonstrate that instantaneous variations of capillary hematocrit cause associated fluctuations of tissue Po2. Furthermore, our results suggest that homogeneous tissue oxygenation requires capillary networks to be denser on venular side than on arteriolar side. Our new model for oxygen transport will make it possible to quantify in detail the effects of blood flow heterogeneity on tissue oxygenation in realistic capillary networks. PMID:25398979

  15. Blood risk factor metabolites associated with heart disease and myocardial fatty acids in copper-deficient male and female rats

    SciTech Connect

    Fields, M.; Lewis, C.; Beal, T. ); Berlin, E.; Kliman, P.G.; Peters, R.C. )

    1989-07-01

    Intact and castrated males and intact and ovariectomized female rats were fed a copper-deficient diet in order to establish whether the protection provided in females against cardiovascular pathology and mortality is due to endogenous sex hormones, and different levels of blood lipids and/or myocardial fatty acids. Seventy-three male and female rats were assigned to a copper-deficient diet (0.6 {mu}g of copper/g diet) containing 62% fructose for 8 weeks. Twelve of the male rats underwent castration and 12 of the females were ovariectomized. All animals exhibited high levels of plasma cholesterol, triglycerides, and uric acid, which were neither affected by the sex of the rat nor by the surgical treatment. The composition of fatty acids of the myocardium was similar in males and females. Except for those animals that were sacrificed by us, all other male rats died of heart pathology. In contrast, none of the female rats exhibited heart pathology and none died of the deficiency. It is suggested that heart pathology and mortality in copper deficiency are sex related and not due to high levels of plasma cholesterol, triglycerides, and uric acid or to differences in myocardial fatty acid composition.

  16. HEMORHEOLOGICAL IMPLICATIONS OF PERFLUOROCARBON BASED OXYGEN CARRIER INTERACTION WITH COLLOID PLASMA EXPANDERS AND BLOOD

    PubMed Central

    Vásquez, Diana M.; Ortiz, Daniel; Alvarez, Oscar A.; Briceño, Juan C.; Cabrales, Pedro

    2013-01-01

    Perfluorocarbon (PFC) emulsion based oxygen carriers lack colloid osmotic pressure (COP) and must be administered with colloid-based plasma expanders (PEs). Although PFC emulsions have been widely studied, there is limited information about PFC emulsion interaction with PEs and blood. Their interaction forms aggregates due to electrostatic and rheological phenomena, and change blood rheology and blood flow. This study analyzes the effects of the interaction between PFC emulsions with blood in the presence of clinically-used PEs. The rheological behavior of the mixtures was analyzed in parallel with in vivo analysis of blood flow in microvessels using intravital microscopy when administered in a clinically relevant scenario. The interaction between the PFC emulsion and PE with blood produced PFC droplets and red blood cell (RBCs) aggregation, and increased blood viscosity. The PFC droplets formed aggregates when mixed with PEs containing electrolytes, and the aggregation increased with the electrolyte concentration. Mixtures of PFC with PEs that produced PFC aggregates also induced RCBs aggregation when mixed with blood, increasing blood viscosity at low shear rates. The more viscous suspension at low shear rates produced a blunted blood flow velocity profile in vivo relative to non-aggregating mixtures of PFC and PEs. For the PEs evaluated, albumin produced minimal to undetectable aggregation. PFC and PEs interaction with blood can affect sections of the microcirculation with low shear rate (e.g. arterioles, venules, and pulmonary circulation) because aggregates could cause capillary occlusion, decrease perfusion, pulmonary emboli, or focal ischemia. PMID:23606592

  17. Oxygenated-Blood Colour Change Thresholds for Perceived Facial Redness, Health, and Attractiveness

    PubMed Central

    Re, Daniel E.; Whitehead, Ross D.; Xiao, Dengke; Perrett, David I.

    2011-01-01

    Blood oxygenation level is associated with cardiovascular fitness, and raising oxygenated blood colouration in human faces increases perceived health. The current study used a two-alternative forced choice (2AFC) psychophysics design to quantify the oxygenated blood colour (redness) change threshold required to affect perception of facial colour, health and attractiveness. Detection thresholds for colour judgments were lower than those for health and attractiveness, which did not differ. The results suggest redness preferences do not reflect a sensory bias, rather preferences may be based on accurate indications of health status. Furthermore, results suggest perceived health and attractiveness may be perceptually equivalent when they are assessed based on facial redness. Appearance-based motivation for lifestyle change can be effective; thus future studies could assess the degree to which cardiovascular fitness increases face redness and could quantify changes in aerobic exercise needed to increase facial attractiveness. PMID:21448270

  18. Intravascular ATP and the regulation of blood flow and oxygen delivery in humans.

    PubMed

    Crecelius, Anne R; Kirby, Brett S; Dinenno, Frank A

    2015-01-01

    Regulation of vascular tone is a complex response that integrates multiple signals that allow for blood flow and oxygen supply to match oxygen demand appropriately. Here, we discuss the potential role of intravascular adenosine triphosphate (ATP) as a primary factor in these responses and put forth the hypothesis that deficient ATP release contributes to impairments in vascular control exhibited in aged and diseased populations. PMID:25390296

  19. Activated platelet chemiluminescence and presence of CD45+ platelets in patients with acute myocardial infarction.

    PubMed

    Gabbasov, Zufar; Ivanova, Oxana; Kogan-Yasny, Victor; Ryzhkova, Evgeniya; Saburova, Olga; Vorobyeva, Inna; Vasilieva, Elena

    2014-01-01

    It has been found that in 15% of acute myocardial infarction patients' platelets generate reactive oxygen species that can be detected with luminol-enhanced chemiluminescence of platelet-rich plasma within 8-10 days after acute myocardial infarction. This increase in generate reactive oxygen species production coincides with the emergence of CD45(+) platelets. The ability of platelets to carry surface leukocyte antigen implies their participation in exchange of specific proteins in the course of acute myocardial infarction. Future studies of CD45(+) platelets in peripheral blood of acute myocardial infarction patients in association with generate reactive oxygen species production may provide a new insight into the complex mechanisms of cell-cell interactions associated with acute myocardial infarction. PMID:24102264

  20. Quantitative assessment of oscillatory components in blood circulation: classification of the effect of aging, diabetes, and acute myocardial infarction

    NASA Astrophysics Data System (ADS)

    Bernjak, Alan; Stefanovska, Aneta; Urbancic-Rovan, Vilma; Azman-Juvan, Katja

    2005-04-01

    The human cardiovascular system is a complex system with the pumping activity of the heart as the main generator of oscillations. Besides the heartbeat there are several other oscillatory components which determine its dynamics. Their nonlinear nature and a weak coupling between them both require special treatment while studying this system. A particular characteristic of the oscillatory components is their frequency fluctuations in time. Consequently, their interactions also fluctuate in time. Therefore the wavelet transform is applied to trace the oscillatory components in time, and specific quantitative measures are introduced to quantify the contribution of each of the oscillatory components involved on the time scale of up to three minutes. Oscillatory components are then analysed from signals obtained by simultaneous measurements of blood flow in the microcirculation, ECG, respiration and blood pressure. Based on quantitative evaluation of the oscillatory components related to (I) the heart beat (0.6-2Hz), (II) respiration (0.145-0.6Hz), (III) intrinsic myogenic activity (0.052-0.145Hz), (IV) sympathetic activity (0.021-0.052Hz), (V, VI) endothelial related activity (0.0095-0.021Hz, 0.005 - 0.0095 Hz), 30-minutes recording taken on 109 healthy subjects, 75 patients with diabetes, and 82 patients after acute myocardial infarction (AMI) were analysed. Classification of the effect of ageing, diabetes and AMI from blood flow signals simultaneously recorded in the skin of four extremities, the heart rate and heart rate variability from R-R intervals will be presented and discussed.

  1. Functional photoacoustic tomography for non-invasive imaging of cerebral blood oxygenation and blood volume in rat brain in vivo

    NASA Astrophysics Data System (ADS)

    Wang, Xueding; Xie, Xueyi; Ku, Geng; Stoica, George; Wang, Lihong V.

    2005-04-01

    Based on the multi-wavelength laser-based photoacoustic tomography, non-invasive in vivo imaging of functional parameters, including the hemoglobin oxygen saturation and the total concentration of hemoglobin, in small-animal brains was realized. The high sensitivity of this technique is based on the spectroscopic differences between oxy- and deoxy-hemoglobin while its spatial resolution is bandwidth-limited by the photoacoustic signals rather than by the optical diffusion as in optical imaging. The point-by-point distributions of blood oxygenation and blood volume in the cerebral cortical venous vessels, altered by systemic physiological modulations including hyperoxia, normoxia and hypoxia, were visualized successfully through the intact skin and skull. This technique, with its prominent intrinsic advantages, can potentially accelerate the progress in neuroscience and provide important new insights into cerebrovascular physiology and brain function that are of great significance to the neuroscience community.

  2. Endothelial ROS and Impaired Myocardial Oxygen Consumption in Sepsis-induced Cardiac Dysfunction

    PubMed Central

    Potz, Brittany A; Sellke, Frank W; Abid, M Ruhul

    2016-01-01

    Sepsis is known as the presence of a Systemic Inflammatory Response Syndrome (SIRS) in response to an infection. In the USA alone, 750,000 cases of severe sepsis are diagnosed annually. More than 70% of sepsis-related deaths occur due to organ failure and more than 50% of septic patients demonstrate cardiac dysfunction. Patients with sepsis who develop cardiac dysfunction have significantly higher mortality, and thus cardiac dysfunction serves as a predictor of survival in sepsis. We have very little understanding about the mechanisms that result in cardiac dysfunction in the setting of sepsis. At present, the factors involved in sepsis-related cardiac dysfunction are believed to include the following: persistent inflammatory changes in the vascular endothelium and endocardium leading to circulatory and micro vascular changes, increase in endothelial reactive oxygen species (ROS), abnormal endothelium-leukocyte interaction resulting in a feed-forward loop for inflammatory cytokines and ROS, contractile dysfunction of the heart due to autonomic dysregulation, metabolic changes in myocardium leading to impaired oxygen delivery and increased oxygen consumption, mitochondrial dysfunction, and persistent inflammatory signaling. In this review article, we will briefly discuss the clinical challenges and our current understanding of cardiac dysfunction in sepsis. Major focus will be on the pathological changes that occur in vascular endothelium, with an emphasis on endocardium, and how endothelial ROS, impaired endothelium-leukocyte interaction, and microcirculatory changes lead to cardiac dysfunction in sepsis. The importance of the ongoing quest for the clinical biomarkers for cardiac dysfunction will also be discussed. PMID:27135058

  3. The effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake.

    PubMed

    Oh, Deuk-Ja; Hong, Hyeon-Ok; Lee, Bo-Ae

    2016-02-01

    The purpose of this study is to investigate the effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake. To achieve the purpose of the study, a total of 30 subjects were selected, including 15 people who performed continued regular exercises and 15 people as the control group. With regard to data processing, the IBM SPSS Statistics ver. 21.0 was used to calculate the mean and standard deviation. The difference of mean change between groups was verified through an independent t-test. As a result, there were significant differences in resting heart rate, maximal heart rate, maximal systolic blood pressure, and maximal oxygen uptake. However, the maximal systolic blood pressure was found to be an exercise-induced high blood pressure. Thus, it is thought that a risk diagnosis for it through a regular exercise stress test is necessary. PMID:26933659

  4. The effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake

    PubMed Central

    Oh, Deuk-Ja; Hong, Hyeon-Ok; Lee, Bo-Ae

    2016-01-01

    The purpose of this study is to investigate the effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake. To achieve the purpose of the study, a total of 30 subjects were selected, including 15 people who performed continued regular exercises and 15 people as the control group. With regard to data processing, the IBM SPSS Statistics ver. 21.0 was used to calculate the mean and standard deviation. The difference of mean change between groups was verified through an independent t-test. As a result, there were significant differences in resting heart rate, maximal heart rate, maximal systolic blood pressure, and maximal oxygen uptake. However, the maximal systolic blood pressure was found to be an exercise-induced high blood pressure. Thus, it is thought that a risk diagnosis for it through a regular exercise stress test is necessary. PMID:26933659

  5. Noninvasive functional photoacoustic tomography of blood-oxygen saturation in the brain

    NASA Astrophysics Data System (ADS)

    Wang, Xueding; Ku, Geng; Xie, Xueyi; Wang, Yiwen; Stoica, George; Wang, Lihong V.

    2004-07-01

    Since optical contrast is sensitive to functional parameters, including the hemoglobin oxygen saturation and the total concentration of hemoglobin, imaging based on optical contrast has been widely employed for the real-time monitoring of tissue oxygen consumption and hemodynamics in biological tissues. However, due to the overwhelming scattering of light in tissues, traditional optical imaging modalities cannot provide satisfactory spatial resolution. Functional photoacoustic tomography is a novel technique that combines high optical contrast and high ultrasonic resolution. Here, we present our study of a laser-based photoacoustic technique that, for the first time to our knowledge, monitors blood oxygenation in the rat brain in vivo. The cerebral blood oxygenation in the rat brain was imaged by photoacoustic detection at two wavelengths. The change in the hemoglobin oxygen saturation in the brain vessels as a result of the alternation from hyperoxia status to hypoxia status was visualized successfully with satisfactory spatial resolution. This work demonstrates that photoacoustic technique, based on the spectroscopic absorption of oxy- and deoxy-hemoglobin, can provide accurate functional imaging of cerebral blood oxygenation in the small-animal brain non-invasively with the skin and skull intact.

  6. Relationship between blood oxygenation and lactate in human skeletal muscle revealed by near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Guodong; Luo, Qingming; Ge, Xinfa; Gong, Hui; Zeng, Shaoqun

    2002-04-01

    Near-infrared spectroscopy (NIRS) is a focus of attention in the research field of biomedical photonics. The concentration of HbO2 in human skeletal muscle has been measured noninvasive NIRS using a portable tissue oximeter continuously when the subjects did incremental exercises on a power bicycle. Blood lactate is one of traditional physical research subjects which is applied most widely. We study blood volume in the tissue of sportsmen when they are subjected by the incremental physical load, simultaneously detecting some parameters such as the heart rate, maximal oxygen absorption and the concentration of blood lactate. As the intensity of exercises was heightened, the concentration of blood lactate and blood volume in tissue increased, while the concentration of HbO2 decreased. Thus the rudimental characteristics of energy consumption and supply during hypoxia and aerobic exercises are investigated. By discovering the relationship between blood lactate in human skeletal muscle and blood oxygenation, a novel approach for measuring blood lactate noninvasively and assessing the sports ability could be provided. Furthermore, it is possible to assess the fatigue state with tissue oximeter to monitor the human sports intensity noninvasively and dynamically.

  7. Cardiovascular magnetic resonance of myocardial edema using a short inversion time inversion recovery (STIR) black-blood technique: Diagnostic accuracy of visual and semi-quantitative assessment

    PubMed Central

    2012-01-01

    Background The short inversion time inversion recovery (STIR) black-blood technique has been used to visualize myocardial edema, and thus to differentiate acute from chronic myocardial lesions. However, some cardiovascular magnetic resonance (CMR) groups have reported variable image quality, and hence the diagnostic value of STIR in routine clinical practice has been put into question. The aim of our study was to analyze image quality and diagnostic performance of STIR using a set of pulse sequence parameters dedicated to edema detection, and to discuss possible factors that influence image quality. We hypothesized that STIR imaging is an accurate and robust way of detecting myocardial edema in non-selected patients with acute myocardial infarction. Methods Forty-six consecutive patients with acute myocardial infarction underwent CMR (day 4.5, +/- 1.6) including STIR for the assessment of myocardial edema and late gadolinium enhancement (LGE) for quantification of myocardial necrosis. Thirty of these patients underwent a follow-up CMR at approximately six months (195 +/- 39 days). Both STIR and LGE images were evaluated separately on a segmental basis for image quality as well as for presence and extent of myocardial hyper-intensity, with both visual and semi-quantitative (threshold-based) analysis. LGE was used as a reference standard for localization and extent of myocardial necrosis (acute) or scar (chronic). Results Image quality of STIR images was rated as diagnostic in 99.5% of cases. At the acute stage, the sensitivity and specificity of STIR to detect infarcted segments on visual assessment was 95% and 78% respectively, and on semi-quantitative assessment was 99% and 83%, respectively. STIR differentiated acutely from chronically infarcted segments with a sensitivity of 95% by both methods and with a specificity of 99% by visual assessment and 97% by semi-quantitative assessment. The extent of hyper-intense areas on acute STIR images was 85% larger than

  8. The Preliminary Study Of Giant Magnetoresistance Sensor For Detection Of Oxygen In Human Blood

    NASA Astrophysics Data System (ADS)

    Ramli, Ramli; Muhtadi, Almas Hilman; Sahdan, Muhammad Fauzi; Haryanto, Freddy; Khairurrijal; Djamal, Mitra

    2010-12-01

    In recent years, there has been great progress for applications of nanomaterials in medicine field. Human body consists of many atoms and they can be treated like as nanomaterials. One of them is oxygen. Oxygen is always found in the human blood. Its concentration in human blood gives information about the metabolism in the body. The purpose of this study was to look for a possibility for developing tool to detect the concentration of oxygen in blood. In this study, the giant-magneto-resistance (GMR) sensor is implemented. The GMR sensor has many attractive features, for example: reduced size, low-power consumption, low price, as compared to other magnetic sensors and its electric and magnetic properties can be varied in very wide range. In this experiment, we developed the structure of GMR materials NiCoFe/Cu/NiCoFe sandwich as a GMR sensor. The NiCoFe/Cu/NiCoFe sandwiches were grown onto Si (111) substrates by the dc-opposed target magnetron sputtering (dc-OTMS) technique. The sputtering targets were NiCoFe and Cu. To achieve the aims of this study, the blood transports in human will be simulated using a simple experimental model. This model has some parameters representing those in blood transport. Furthermore, the nanomagnetic material will be made as a contaminant particle in blood. Using this material some properties of the transport will be investigated.

  9. The locus coeruleus-norepinephrine network optimizes coupling of cerebral blood volume with oxygen demand.

    PubMed

    Bekar, Lane K; Wei, Helen S; Nedergaard, Maiken

    2012-12-01

    Given the brain's uniquely high cell density and tissue oxygen levels bordering on hypoxia, the ability to rapidly and precisely match blood flow to constantly changing patterns in neural activity is an essential feature of cerebrovascular regulation. Locus coeruleus-norepinephrine (LC-NE) projections innervate the cerebral vasculature and can mediate vasoconstriction. However, function of the LC-mediated constriction in blood-flow regulation has never been addressed. Here, using intrinsic optical imaging coupled with an anesthesia regimen that only minimally interferes with LC activity, we show that NE enhances spatial and temporal aspects of functional hyperemia in the mouse somatosensory cortex. Increasing NE levels in the cortex using an α(2)-adrenergic receptor antagonist paradoxically reduces the extent of functional hyperemia while enhancing the surround blood-flow reduction. However, the NE-mediated vasoconstriction optimizes spatial and temporal focusing of the hyperemic response resulting in a sixfold decrease in the disparity between blood volume and oxygen demand. In addition, NE-mediated vasoconstriction accelerated redistribution to subsequently active regions, enhancing temporal synchronization of blood delivery. These observations show an important role for NE in optimizing neurovascular coupling. As LC neuron loss is prominent in Alzheimer and Parkinson diseases, the diminished ability to couple blood volume to oxygen demand may contribute to their pathogenesis. PMID:22872230

  10. Visualization of hypertrophied papillary muscle mimicking left ventricular mass on gated blood pool and T1-201 myocardial perfusion imaging

    SciTech Connect

    Bunko, H.; Nakajima, K.; Tonami, N.; Asanoi, H.; Hisada, K.

    1981-12-01

    A sixty-year old man with acute myocardial infarction was incidentally found to have a hypertrophied anterolateral papillary muscle (ALPPM) of the left ventricle on gated blood pool (GBP) and T1-201 myocardial perfusion images. Hypertrophy of the ALPPM was visualized as a movable defect in the lateral basal area on GBP imaging throughout the cardiac cycle and on the TI-201 study as a radionuclide accumulating structure, consistent with the defect in the GBP. A combination of these findings may suggest the presence of a hypertrophied papillary muscle of the left ventricle.

  11. Oxygen-implanted induced formation of oxide layer enhances blood compatibility on titanium for biomedical applications.

    PubMed

    Hung, Wei-Chiang; Chang, Fang-Mo; Yang, Tzu-Sen; Ou, Keng-Liang; Lin, Che-Tong; Peng, Pei-Wen

    2016-11-01

    Titanium dioxide (TiO2) layers were prepared on a Ti substrate by using oxygen plasma immersion ion implantation (oxygen PIII). The surface chemical states, structure, and morphology of the layers were studied using X-ray photoelectron spectroscopy, X-ray diffraction, Raman microscopy, atomic force microscopy and scanning electron microscope. The mechanical properties, such as the Young's modulus and hardness, of the layers were investigated using nanoindentation testing. The Ti(4+) chemical state was determined to be present on oxygen-PIII-treated surfaces, which consisted of nanocrystalline TiO2 with a rutile structure. Compared with Ti substrates, the oxygen-PIII-treated surfaces exhibited decreased Young's moduli and hardness. Parameters indicating the blood compatibility of the oxygen-PIII-treated surfaces, including the clotting time and platelet adhesion and activation, were studied in vitro. Clotting time assays indicated that the clotting time of oxygen-PIII-treated surfaces was longer than that of the Ti substrate, which was associated with decreased fibrinogen adsorption. In conclusion, the surface characteristics and the blood compatibility of Ti implants can be modified and improved using oxygen PIII. PMID:27524050

  12. Photoacoustic ultrasound spectroscopy for assessing red blood cell aggregation and oxygenation

    NASA Astrophysics Data System (ADS)

    Hysi, Eno; Saha, Ratan K.; Kolios, Michael C.

    2012-12-01

    Red blood cell (RBC) aggregation and oxygenation are important markers for a variety of blood disorders. No current technique is capable of simultaneously measuring aggregation/oxygenation levels noninvasively. We propose using photoacoustic ultrasound spectroscopy (PAUS) for assessing both phenomena. This technique relies on frequency-domain analysis of the PA signals by extracting parameters such as the ultrasound spectral slope and the midband fit. To investigate the effect of hematocrit, aggregation, and oxygenation levels on PAUS parameters, a Monte Carlo-based theoretical model and an experimental protocol using porcine RBCs were developed. The samples were illuminated at 750 and 1064 nm and changes in the PAUS parameters were compared to the oxygen-dependent optical absorption coefficients to assess the oxygenation level. Good agreement between the theoretical and experimental spectral parameters was obtained for the spectral slope of the nonaggregated spectra (˜0.3 dB/MHz). The experimental midband fit increased by ˜5 dB for the largest aggregate size. Based on the analysis of the PA signals, the oxygen saturation level of the most aggregated sample was >20% greater than the nonaggregated sample. The results provide a framework for using PA signals' spectroscopic parameters for monitoring the aggregation and oxygenation levels of RBCs.

  13. The study of synchronization of rhythms of microvascular blood flow and oxygen saturation during adaptive changes

    NASA Astrophysics Data System (ADS)

    Dunaev, Andrey V.; Sidorov, Victor V.; Krupatkin, Alexander I.; Rafailov, Ilya E.; Palmer, Scott G.; Sokolovski, Sergei G.; Stewart, Neil A.; Rafailov, Edik U.

    2014-02-01

    Multi-functional laser non-invasive diagnostic systems, such as "LAKK-M", allow the study of a number of microcirculatory parameters, including blood microcirculatory index (Im) (by laser Doppler flowmetry, LDF) and oxygen saturation (StO2) of skin tissue (by tissue reflectance oximetry, TRO). Such systems may provide significant information relevant to physiology and clinical medicine. The aim of this research was to use such a system to study the synchronization of microvascular blood flow and oxygen saturation rhythms under normal and adaptive change conditions. Studies were conducted with 8 healthy volunteers - 3 females and 5 males of 21-49 years. Each volunteer was subjected to basic 3 minute tests. The volunteers were observed for between 1-4 months each, totalling 422 basic tests. Measurements were performed on the palmar surface of the right middle finger and the forearm medial surface. Wavelet analysis was used to study rhythmic oscillations in LDF- and TRO-data. Tissue oxygen consumption (from arterial and venal blood oxygen saturation and nutritive flux volume) was calculated for all volunteers during "adaptive changes" as (617+/-123 AU) and (102+/-38 AU) with and without arteriovenous anastomoses (AVAs) respectively. This demonstrates increased consumption compared to normal (495+/-170 AU) and (69+/-40 AU) with and without AVAs respectively. Data analysis demonstrated the emergence of resonance and synchronization of rhythms of microvascular blood flow and oxygen saturation as an adaptive change in myogenic oscillation (vasomotion) resulting from exercise and potentially from psychoemotional stress. Synchronization of myogenic rhythms during adaptive changes suggest increased oxygen consumption resulting from increased microvascular blood flow velocity.

  14. A refined method for quantification of myocardial oxygen consumption rate using mean transit time with carbon-11-acetate and dynamic PET.

    PubMed

    Choi, Y; Huang, S C; Hawkins, R A; Hoh, C K; Krivokapich, J; Buxton, D B; Armbrecht, J J; Sun, K T; Phelps, M E; Schelbert, H R

    1993-11-01

    The utility of the mean transit time equation was investigated for estimation of the myocardial clearance rate constant of 11C-acetate, which is proportional to myocardial oxygen consumption rates. The mean transit time approach was also employed to generate parametric images of the clearance rate constant of 11C-acetate with dynamic PET imaging in 20 normal human studies. Input function delays and cutoff errors due to the truncation of the myocardial tissue time-activity curve at a finite time were corrected. The clearance rate constants estimated by mean transit time correlated well with the estimates by conventional monoexponential fitting (15 min (truncation time): Y = 0.01 + 0.94X, correlated coefficient (r) = 0.99; 16 min: Y = 0.03 + 0.94X, r = 0.98; 20 min: Y = 0.03 + 0.84X, r = 0.99). The clearance rate constants estimated by the mean transit time approach also correlated well (r = 0.94) with the measured rate-pressure products. The quality and noise level of parametric images of the clearance rate constants generated by mean transit time are improved over those generated by monoexponential fitting. Additional advantages of the mean transit time approach compared to the standard monoexponential fitting method for estimating myocardial clearance rate constant of 11C-acetate include ease of input function delay correction, less sensitivity to the shape of the input function and elimination of subjective data selection of the linear portion of the clearance data on a semilog plot. Thus, this approach is expected to facilitate objective quantitative analysis of indices of myocardial oxygen consumption. PMID:8229256

  15. Changes of some blood indices and myocardial electrolyte content during hypokinesia

    NASA Technical Reports Server (NTRS)

    Fedorov, B. M.; Krotov, V. P.; Zhuravleva, Y. N.

    1979-01-01

    Using special hypokinetic cages, the volume changes of circulating blood, its hematocrit and protein content, volume ratios between extra- and intracellular liquids in the body, as well as electrolyte content in the blood and myocardium during hypokinesia were investigated experimentally in rabbits.

  16. Increased fetal myocardial sensitivity to insulin-stimulated glucose metabolism during ovine fetal growth restriction.

    PubMed

    Barry, James S; Rozance, Paul J; Brown, Laura D; Anthony, Russell V; Thornburg, Kent L; Hay, William W

    2016-04-01

    Unlike other visceral organs, myocardial weight is maintained in relation to fetal body weight in intrauterine growth restriction (IUGR) fetal sheep despite hypoinsulinemia and global nutrient restriction. We designed experiments in fetal sheep with placental insufficiency and restricted growth to determine basal and insulin-stimulated myocardial glucose and oxygen metabolism and test the hypothesis that myocardial insulin sensitivity would be increased in the IUGR heart. IUGR was induced by maternal hyperthermia during gestation. Control (C) and IUGR fetal myocardial metabolism were measured at baseline and under acute hyperinsulinemic/euglycemic clamp conditions at 128-132 days gestation using fluorescent microspheres to determine myocardial blood flow. Fetal body and heart weights were reduced by 33% (P = 0.008) and 30% (P = 0.027), respectively. Heart weight to body weight ratios were not different. Basal left ventricular (LV) myocardial blood flow per gram of LV tissue was maintained in IUGR fetuses compared to controls. Insulin increased LV myocardial blood flow by ∼38% (P < 0.01), but insulin-stimulated LV myocardial blood flow in IUGR fetuses was 73% greater than controls. Similar to previous reports testing acute hypoxia, LV blood flow was inversely related to arterial oxygen concentration (r(2 )= 0.71) in both control and IUGR animals. Basal LV myocardial glucose delivery and uptake rates were not different between IUGR and control fetuses. Insulin increased LV myocardial glucose delivery (by 40%) and uptake (by 78%) (P < 0.01), but to a greater extent in the IUGR fetuses compared to controls. During basal and hyperinsulinemic-euglycemic clamp conditions LV myocardial oxygen delivery, oxygen uptake, and oxygen extraction efficiency were not different between groups. These novel results demonstrate that the fetal heart exposed to nutrient and oxygen deprivation from placental insufficiency appears to maintain myocardial energy supply

  17. Optical methods for correction of oxygen-transport characteristics of blood and their biomedical applications

    NASA Astrophysics Data System (ADS)

    Zalesskaya, G. A.; Akulich, N. V.; Marochkov, A. V.; Laskina, O. V.; Mit'kovskaya, N. P.

    2010-07-01

    We have carried out a comprehensive analysis of the spectral characteristics of blood and blood components, gas-exchange and oximetry parameters for venous and arterial blood, central hemodynamic parameters, and the results of a complete blood count and chemistry panel before and after extracorporeal UV irradiation of the blood (UBI, ultraviolet blood irradiation) or intravenous exposure of blood to low-intensity emission from an He-Ne laser (LBI, laser blood irradiation). We have demonstrated the possibility of correcting the oxygentransport characteristics of blood by laser optical methods based on photodissociation of blood oxyhemoglobin. We have shown that the therapeutic effects initiated both by UBI and LBI are based on a single mechanism: a change in the balance between production of active oxygen species and their inhibition by antioxidants. The data obtained are of interest not only for studying the primary (molecular) mechanisms of action for photohemotherapy and their effect on processes occurring in the living body, but also can provide a basis for designing next-generation laser optical instruments and for development of not yet existing methods for assessing the therapeutic efficacy of photohemotherapy.

  18. Blood biochemical and cellular changes during a decompression procedure involving eight hours of oxygen prebreathing

    NASA Technical Reports Server (NTRS)

    Jauchem, J. R.

    1989-01-01

    Chemical and cellular parameters were measured in human subjects before and after exposure to a decompression schedule involving 8 h of oxygen prebreathing. The exposure was designed to simulate space-flight extravehicular activity (EVA) for 6 h. Several statistically significant changes in blood parameters were observed following the exposure: increases in calcium, magnesium, osmolality, low-density lipoprotein cholesterol, monocytes, and prothrombin time, and decreases in chloride, creatine phosphokinase and eosinophils. The changes, however, were small in magnitude and blood factor levels remained within normal clinical ranges. Thus, the decompression profile used in this study is not likely to result in blood changes that would pose a threat to astronauts during EVA.

  19. Simultaneous high-resolution pH and spectrophotometric recordings of oxygen binding in blood microvolumes.

    PubMed

    Oellermann, Michael; Pörtner, Hans-O; Mark, Felix C

    2014-05-01

    Oxygen equilibrium curves have been widely used to understand oxygen transport in numerous organisms. A major challenge has been to monitor oxygen binding characteristics and concomitant pH changes as they occur in vivo, in limited sample volumes. Here we report a technique allowing highly resolved and simultaneous monitoring of pH and blood pigment saturation in minute blood volumes. We equipped a gas diffusion chamber with a broad-range fibre-optic spectrophotometer and a micro-pH optode and recorded changes of pigment oxygenation along oxygen partial pressure (PO2) and pH gradients to test the setup. Oxygen binding parameters derived from measurements in only 15 μl of haemolymph from the cephalopod Octopus vulgaris showed low instrumental error (0.93%) and good agreement with published data. Broad-range spectra, each resolving 2048 data points, provided detailed insight into the complex absorbance characteristics of diverse blood types. After consideration of photobleaching and intrinsic fluorescence, pH optodes yielded accurate recordings and resolved a sigmoidal shift of 0.03 pH units in response to changing PO2 from 0 to 21 kPa. Highly resolved continuous recordings along pH gradients conformed to stepwise measurements at low rates of pH changes. In this study we showed that a diffusion chamber upgraded with a broad-range spectrophotometer and an optical pH sensor accurately characterizes oxygen binding with minimal sample consumption and manipulation. We conclude that the modified diffusion chamber is highly suitable for experimental biologists who demand high flexibility, detailed insight into oxygen binding as well as experimental and biological accuracy combined in a single setup. PMID:24436387

  20. Effects of heme oxygenase-1 upregulation on blood pressure and cardiac function in an animal model of hypertensive myocardial infarction.

    PubMed

    Chen, Tian-Meng; Li, Jian; Liu, Lin; Fan, Li; Li, Xiao-Ying; Wang, Yu-Tang; Abraham, Nader G; Cao, Jian

    2013-01-01

    In this study, we evaluate the effect of HO-1 upregulation on blood pressure and cardiac function in the new model of infarct spontaneous hypertensive rats (ISHR). Male spontaneous hypertensive rats (SHR) at 13 weeks (n = 40) and age-matched male Wistar (WT) rats (n = 20) were divided into six groups: WT (sham + normal saline (NS)), WT (sham + Co(III) Protoporphyrin IX Chloride (CoPP)), SHR (myocardial infarction (MI) + NS), SHR (MI + CoPP), SHR (MI + CoPP + Tin Mesoporphyrin IX Dichloride (SnMP)), SHR (sham + NS); CoPP 4.5 mg/kg, SnMP 15 mg/kg, for six weeks, one/week, i.p., n = 10/group. At the sixth week, echocardiography (UCG) and hemodynamics were performed. Then, blood samples and heart tissue were collected. Copp treatment in the SHR (MI + CoPP) group lowered blood pressure, decreased infarcted area, restored cardiac function (left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), +dp/dt(max), (-dp/dt(max))/left ventricular systolic pressure (LVSP)), inhibited cardiac hypertrophy and ventricular enlargement (downregulating left ventricular end-systolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD) and heart weight/body weight (HW/BW)), lowered serum CRP, IL-6 and Glu levels and increased serum TB, NO and PGI2 levels. Western blot and immunohistochemistry showed that HO-1 expression was elevated in the SHR (MI + CoPP) group, while co-administration with SnMP suppressed the benefit functions mentioned above. In conclusion, HO-1 upregulation can lower blood pressure and improve post-infarct cardiac function in the ISHR model. These functions may be involved in the inhibition of inflammation and the ventricular remodeling process and in the amelioration of glucose metabolism and endothelial dysfunction. PMID:23358254

  1. Regional myocardial blood flow and coronary vascular reserve in unanesthetized ponies during pacing-induced ventricular tachycardia

    SciTech Connect

    Parks, C.; Manohar, M.; Lundeen, G.

    1983-08-01

    To examine the effects of tachycardia on coronary circulation, transmural distribution of myocardial blood flow (MBF, 15-micron diameter radionuclide-labeled microspheres) was studied in six healthy adult ponies at rest (heart rate . 60 +/- 7 beats . min-1), during ventricular pacing at 150 and 200 beats . min-1, as well as with ventricular pacing at 250 beats . min-1 before and during maximal coronary vasodilatation (iv adenosine infusion; 4 mumole . kg-1 . min-1). Mean aortic pressure and cardiac output were unchanged from control values with ventricular pacing. Whereas ventricular pacing at 150 and 200 beats . min-1 resulted in a progressive uniform increase in transmural MBF and well-maintained endo:epi perfusion ratio, pacing at 250 beats . min-1 did not result in a further increase in MBF compared to pacing at 200 beats . min-1 and the left ventricular (LV) subendocardial:subepicardial (endo:epi) perfusion ratio was significantly less than 1.00 (0.87 +/- 0.05). Blood flow to the LV papillary muscles and subendocardium was significantly less than that recorded at 200 beats . min-1. The LV endo:epi perfusion ratio with ventricular pacing at 250 beats . min-1 during adenosine infusion resulted in a decrease in mean aortic pressure (63% of control value) and a marked further reduction in blood flow to the LV papillary muscles as well as the LV subendocardium, while MBF increased dramatically in the LV subepicardium compared to values observed during ventricular pacing at 250 beats . min-1 alone. These data demonstrate that coronary vasomotion functions to maintain LV subendocardial blood flow in the pony myocardium at a heart rate of 200 beats . min-1, while at 250 beats . min-1 exhaustion of coronary vasodilator reserve in the deeper layers limits further increase in MBF.

  2. Predicting Blood Lactate Concentration and Oxygen Uptake from sEMG Data during Fatiguing Cycling Exercise.

    PubMed

    Ražanskas, Petras; Verikas, Antanas; Olsson, Charlotte; Viberg, Per-Arne

    2015-01-01

    This article presents a study of the relationship between electromyographic (EMG) signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the usual practice of picking one particular characteristic of the signal, e.g., the median or mean frequency, multiple variables were used to obtain a thorough characterization of EMG signals in the spectral domain. Based on these variables, linear and non-linear (random forest) models were built to predict blood lactate concentration and oxygen consumption. The results showed that mean and median frequencies are sub-optimal choices for predicting these physiological quantities in dynamic exercises, as they did not exhibit significant changes over the course of our protocol and only weakly correlated with blood lactate concentration or oxygen uptake. Instead, the root mean square of the original signal and backward difference, as well as parameters describing the tails of the EMG power distribution were the most important variables for these models. Coefficients of determination ranging from R(2) = 0:77 to R(2) = 0:98 (for blood lactate) and from R(2) = 0:81 to R(2) = 0:97 (for oxygen uptake) were obtained when using random forest regressors. PMID:26295396

  3. Predicting Blood Lactate Concentration and Oxygen Uptake from sEMG Data during Fatiguing Cycling Exercise

    PubMed Central

    Ražanskas, Petras; Verikas, Antanas; Olsson, Charlotte; Viberg, Per-Arne

    2015-01-01

    This article presents a study of the relationship between electromyographic (EMG) signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the usual practice of picking one particular characteristic of the signal, e.g., the median or mean frequency, multiple variables were used to obtain a thorough characterization of EMG signals in the spectral domain. Based on these variables, linear and non-linear (random forest) models were built to predict blood lactate concentration and oxygen consumption. The results showed that mean and median frequencies are sub-optimal choices for predicting these physiological quantities in dynamic exercises, as they did not exhibit significant changes over the course of our protocol and only weakly correlated with blood lactate concentration or oxygen uptake. Instead, the root mean square of the original signal and backward difference, as well as parameters describing the tails of the EMG power distribution were the most important variables for these models. Coefficients of determination ranging from R2=0.77 to R2=0.98 (for blood lactate) and from R2=0.81 to R2=0.97 (for oxygen uptake) were obtained when using random forest regressors. PMID:26295396

  4. Oxygenation in cervical cancer and normal uterine cervix assessed using blood oxygenation level-dependent (BOLD) MRI at 3T.

    PubMed

    Hallac, Rami R; Ding, Yao; Yuan, Qing; McColl, Roderick W; Lea, Jayanthi; Sims, Robert D; Weatherall, Paul T; Mason, Ralph P

    2012-12-01

    Hypoxia is reported to be a biomarker for poor prognosis in cervical cancer. However, a practical noninvasive method is needed for the routine clinical evaluation of tumor hypoxia. This study examined the potential use of blood oxygenation level-dependent (BOLD) contrast MRI as a noninvasive technique to assess tumor vascular oxygenation at 3T. Following Institutional Review Board-approved informed consent and in compliance with the Health Insurance Portability and Accountability Act, successful results were achieved in nine patients with locally advanced cervical cancer [International Federation of Gynecology and Obstetrics (FIGO) stage IIA to IVA] and three normal volunteers. In the first four patients, dynamic T₂*-weighted MRI was performed in the transaxial plane using a multi-shot echo planar imaging sequence whilst patients breathed room air followed by oxygen (15 dm³/min). Later, a multi-echo gradient echo examination was added to provide quantitative R₂* measurements. The baseline T₂*-weighted signal intensity was quite stable, but increased to various extents in tumors on initiation of oxygen breathing. The signal in normal uterus increased significantly, whereas that in the iliacus muscle did not change. R₂* responded significantly in healthy uterus, cervix and eight cervical tumors. This preliminary study demonstrates that BOLD MRI of cervical cancer at 3T is feasible. However, more patients must be evaluated and followed clinically before any prognostic value can be determined. PMID:22619091

  5. BLOOD SUBSTITUTES: EVOLUTION FROM NON-CARRYING TO OXYGEN AND GAS CARRYING FLUIDS

    PubMed Central

    Cabrales, Pedro; Intaglietta, Marcos

    2013-01-01

    The development of oxygen (O2) carrying blood substitutes has evolved from the goal of replicating blood O2 transports properties to that of preserving microvascular and organ function, reducing the inherent or potential toxicity of the material used to carry O2, and treating pathologies initiated by anemia and hypoxia. Furthermore, the emphasis has shifted from blood replacement fluid to “O2 therapeutics” that restore tissue oxygenation to specific tissues regions. This review covers the different alternatives, potential and limitations of hemoglobin based O2 carriers (HBOCs) and perfluorocarbon based O2 carriers (PFCOCs), with emphasis on the physiological conditions disturbed in the situation that they will be used. It describes how concepts learned from plasma expanders without O2 carrying capacity can be applied to maintain O2 delivery and summarizes the microvascular responses due to HBOCs and PFCOCs. This review also presents alternative applications of HBOCs and PFCOCs namely: 1) How HBOC O2 affinity can be engineered to target O2 delivery to hypoxic tissues; and 2) How the high gas solubility of PFCOCs provides new opportunities for carrying, dissolving and delivering gases with biological activity. It is concluded that current blood substitutes development has amplified their applications horizon by devising therapeutic functions for oxygen carriers requiring limited O2 delivery capacity restoration. Conversely, full, blood-like O2 carrying capacity re-establishment awaits control of O2 carrier toxicity. PMID:23820271

  6. Cerebral venous blood oxygenation monitoring during hyperventilation in healthy volunteers with a novel optoacoustic system

    NASA Astrophysics Data System (ADS)

    Petrov, Andrey; Prough, Donald S.; Petrov, Irene Y.; Petrov, Yuriy; Deyo, Donald J.; Henkel, Sheryl N.; Seeton, Roger; Esenaliev, Rinat O.

    2013-03-01

    Monitoring of cerebral venous oxygenation is useful to facilitate management of patients with severe or moderate traumatic brain injury (TBI). Prompt recognition of low cerebral venous oxygenation is a key to avoiding secondary brain injury associated with brain hypoxia. In specialized clinical research centers, jugular venous bulb catheters have been used for cerebral venous oxygenation monitoring and have demonstrated that oxygen saturation < 50% (normal range is 55-75%) correlates with poor clinical outcome. We developed an optoacoustic technique for noninvasive monitoring of cerebral venous oxygenation. Recently, we designed and built a novel, medical grade optoacoustic system operating in the near-infrared spectral range for continuous, real-time oxygenation monitoring in the superior sagittal sinus (SSS), a large central cerebral vein. In this work, we designed and built a novel SSS optoacoustic probe and developed a new algorithm for SSS oxygenation measurement. The SSS signals were measured in healthy volunteers during voluntary hyperventilation, which induced changes in SSS oxygenation. Simultaneously, we measured exhaled carbon dioxide concentration (EtCO2) using capnography. Good temporal correlation between decreases in optoacoustically measured SSS oxygenation and decreases in EtCO2 was obtained. Decreases in EtCO2 from normal values (35-45 mmHg) to 20-25 mmHg resulted in SSS oxygenation decreases by 3-10%. Intersubject variability of the responses may relate to nonspecific brain activation associated with voluntary hyperventilation. The obtained data demonstrate the capability of the optoacoustic system to detect in real time minor changes in the SSS blood oxygenation.

  7. Effect of nitric oxide on the transport and release of oxygen in fetal blood.

    PubMed

    Clementi, Maria Elisabetta; Orsini, Federica; Schininà, Maria Eugenia; Noia, Giuseppe; Giardina, Bruno

    2003-03-14

    It is well known that nitric oxide (NO), the most important vasodilator agent, plays an important role in lowering vascular resistance in the human umbilical-placental circulation and that its deficiency is related to the pathogenesis of pre-eclamptic disorder. Besides it has recently been demonstrated that human hemoglobin (HbA) is able to transport nitric oxide, as S-nitrosohemoglobin (SNO-Hb), from the arterial to the venous blood. In the present study we examine the functional properties of the adult and fetal nitrosated hemoglobins to see if the double transport of oxygen and NO may influence the fetal oxygenation and the relation between maternal and fetal blood. Our results show that S-nitrosation significantly increases the oxygen affinity of the adult Hb (HbA) with respect to native protein (no-nitrosated) while the functional properties of HbF are less influenced. The oxygen affinity modification, found for SNO-HbA, was ascribed to the nitrosation of cysteine beta 93: really, the same residue is also present in the gamma chains of fetal hemoglobin, while the increase of affinity is less evidenced; hence, it is probable that the 39 aminoacidic substitutions between beta and gamma chains allay the effects of S-nitrosation. As regards the physiological modulators (protons, chloride ions, 2,3-diphosphoglyceric acid, and temperature), they influence the oxygen affinity of the two hemoglobins S-nitrosated, in equal mode with respect to the native forms determining the same variation on the oxygen affinity. Hence, our results evidence the fact that the NO release by SNO-HbA "in vivo" would be limited to regions of extremely low oxygen tension (such as hypoxic regions), while in fetus, SNO-HbF would unload nitric oxide and oxygen at pressure values close to normal. PMID:12615064

  8. Method to obtain the high contrast images of blood vessel for oxygen saturation calculation

    NASA Astrophysics Data System (ADS)

    Tsai, Hsin-Yi; Chen, Yi-Ju; Chang, Han-Chao; Huang, Kuo-Cheng

    2013-06-01

    The skin illuminated of two lights at different wavelength can be applied to detect the oxygen saturation of human blood. Due to the absorption coefficient of oxy- (HbO2) and deoxy- (Hb) hemoglobin are different at the wavelength 660 nm and 890 nm, the transmitted and reflected light within the skin can be used to compute the oxygen saturation image of skin. However, the intensities of skin images illuminated by a 20 mW NIR-LED are too low to determine the position of blood vessel when acquired by the color CCD camera. In order to improve the disadvantages, a mono camera was used and the irradiated distance and angle between LED light and test hand were adjusted to acquire the higher resolution and contrast blood vessel images for the oxygen saturation calculation. In the experiment, we developed the suitable angle to irradiate NIR light is at 75 degrees because the reflected and scattered effect could be generated significantly from both vertical and horizontal direction. In addition, the best contrast vessel images can be obtained when the shutter time is set at 44.030 ms and the irradiated distance was at the range 140-160 mm due to the intensity ratio between tissue and vessel region is the highest and the intensities of image would not be saturated or become too low when these two parameters were adjusted slightly. In future, the proposed parameters and results can be applied to the oxygen saturation measurement in the clinical diagnosis.

  9. Membrane oxygenator heat exchanger failure detected by unique blood gas findings.

    PubMed

    Hawkins, Justin L

    2014-03-01

    Failure of components integrated into the cardiopulmonary bypass circuit, although rare, can bring about catastrophic results. One of these components is the heat exchanger of the membrane oxygenator. In this compartment, unsterile water from the heater cooler device is separated from the sterile blood by stainless steel, aluminum, or by polyurethane. These areas are glued or welded to keep the two compartments separate, maintaining sterility of the blood. Although quality control testing is performed by the manufacturer at the factory level, transport presents the real possibility for damage. Because of this, each manufacturer has included in the instructions for use a testing procedure for testing the integrity of the heat exchanger component. Water is circulated through the heat exchanger before priming and a visible check is made of the oxygenator bundle to check for leaks. If none are apparent, then priming of the oxygenator is performed. In this particular case, this procedure was not useful in detecting communication between the water and blood chambers of the oxygenator. PMID:24779125

  10. Blood oxygen transport and metabolism of the confined lugworm Arenicola marina (L.).

    PubMed

    Toulmond, A

    1975-12-01

    Oxygen consumption (MO2), haemoglobin oxygen saturation level (SVO2) and pH (pHv) in prebranchial blood were measured in lugworms experimentally confined in sea water at 15 degrees C. Total blood flow through the gills (Vb) was estimated. For sea water oxygen partial pressure (PwO2) between 120 and 150 Torr MO2, SVO2 and Vb were high and nearly constant. For PwO2 less than 120 Torr, Vb fell quickly, MO2 progressively dropped, and metabolism remained aerobic at the expense of the prebrancial blood oxygen store. For PwO2 less than 50 Torr, Vb and SvO2 values were extremely low, and the low pHv and the modified buffer power of the surrounding sea water showed that anaerobic metabolism was occurring. Changes in respiratory gas exchanges and metabolism during the tidal cycle are deduced from the comparison of these results with data obtained in the field. PMID:2646

  11. Measurement of oxygen saturation in venous blood by dynamic near IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Nitzan, Meir; Babchenko, Anatoly; Khanokh, Boris; Taitelbaum, Haim

    2000-04-01

    A method for the measurement of oxygen saturation in the venous blood, SvO2, based on optical measurements of light absorption in the infrared region is presented. The method consists of applying relatively low external pressure of 25 mm Hg on the forearm, thereby increasing the venous blood volume in the tissue, and comparing the light absorption before and after the external pressure application. SvO2 has been determined from light absorption measurements in two wavelengths, before and after the pressure application, using a formula derived for two adjacent wavelengths. The method has been applied to the hands and fingers of 17 healthy male subjects, using wavelengths of 767 and 811 nm. SaO2, the oxygen saturation for arterial blood, was also obtained from photoplethysmographic measurements in these two wavelengths (pulse oximetry) using the same formula. The mean (+/- SD) value of SaO2 was 94.5%(+/- 3.0). The mean value of SvO2 was 86.2%(+/- 4.1) for the finger and 80.0%(+/- 8.2) for the hand. These SvO2 values are reasonable for the finger and the hand where arterio-venous anastomoses exist. The method enables the measurement of SvO2 in the limbs, a parameter which is related to tissue blood flow and oxygen consumption.

  12. Investigating the impact of oxygen concentration and blood flow variation on photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Penjweini, Rozhin; Kim, Michele M.; Finlay, Jarod C.; Zhu, Timothy C.

    2016-03-01

    Type II photodynamic therapy (PDT) is used for cancer treatment based on the combined action of a photosensitizer, a special wavelength of light, oxygen (3O2) and generation of singlet oxygen (1O2). Intra-patient and inter-patient variability of oxygen concentration ([3O2]) before and after the treatment as well as photosensitizer concentration and hemodynamic parameters such as blood flow during PDT has been reported. Simulation of these variations is valuable, as it would be a means for the rapid assessment of treatment effect. A mathematical model has been previously developed to incorporate the diffusion equation for light transport in tissue and the macroscopic kinetic equations for simulation of [3O2], photosensitizers in ground and triplet states and concentration of the reacted singlet oxygen ([1O₂]rx) during PDT. In this study, the finite-element based calculation of the macroscopic kinetic equations is done for 2-(1- Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH)-mediated PDT by incorporating the information of the photosensitizer photochemical parameters as well as the tissue optical properties, photosensitizer concentration, initial oxygen concentration ([3O2]0), blood flow changes and Φ that have been measured in mice bearing radiation-induced fibrosarcoma (RIF) tumors. Then, [1O2]rx calculated by using the measured [3O2] during the PDT is compared with [1O2]rx calculated based on the simulated [3O₂]; both calculations showed a reasonably good agreement. Moreover, the impacts of the blood flow changes and [3O2]0 on [1O2]rx have been investigated, which showed no pronounced effect of the blood flow changes on the long-term 1O2 generation. When [3O2]0 becomes limiting, small changes in [3O₂] have large effects on [1O2]rx.

  13. Investigating the impact of oxygen concentration and blood flow variation on photodynamic therapy

    PubMed Central

    Penjweini, Rozhin; Kim, Michele M.; Finlay, Jarod C.; Zhu, Timothy C.

    2016-01-01

    Type II photodynamic therapy (PDT) is used for cancer treatment based on the combined action of a photosensitizer, a special wavelength of light, oxygen (3O2) and generation of singlet oxygen (1O2). Intra-patient and inter-patient variability of oxygen concentration ([3O2]) before and after the treatment as well as photosensitizer concentration and hemodynamic parameters such as blood flow during PDT has been reported. Simulation of these variations is valuable, as it would be a means for the rapid assessment of treatment effect. A mathematical model has been previously developed to incorporate the diffusion equation for light transport in tissue and the macroscopic kinetic equations for simulation of [3O2], photosensitizers in ground and triplet states and concentration of the reacted singlet oxygen ([1O2]rx) during PDT. In this study, the finite-element based calculation of the macroscopic kinetic equations is done for 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH)-mediated PDT by incorporating the information of the photosensitizer photochemical parameters as well as the tissue optical properties, photosensitizer concentration, initial oxygen concentration ([3O2]0), blood flow changes and ϕ that have been measured in mice bearing radiation-induced fibrosarcoma (RIF) tumors. Then, [1O2]rx calculated by using the measured [3O2] during the PDT is compared with [1O2]rx calculated based on the simulated [3O2]; both calculations showed a reasonably good agreement. Moreover, the impacts of the blood flow changes and [3O2]0 on [1O2]rx have been investigated, which showed no pronounced effect of the blood flow changes on the long-term 1O2 generation. When [3O2]0 becomes limiting, small changes in [3O2] have large effects on [1O2]rx. PMID:27453622

  14. Blood oxygen depletion during rest-associated apneas of northern elephant seals (Mirounga angustirostris).

    PubMed

    Stockard, T K; Levenson, D H; Berg, L; Fransioli, J R; Baranov, E A; Ponganis, P J

    2007-08-01

    Blood gases (P(O)2, P(CO)2, pH), oxygen content, hematocrit and hemoglobin concentration were measured during rest-associated apneas of nine juvenile northern elephant seals. In conjunction with blood volume determinations, these data were used to determine total blood oxygen stores, the rate and magnitude of blood O(2) depletion, the contribution of the blood O(2) store to apneic metabolic rate, and the degree of hypoxemia that occurs during these breath-holds. Mean body mass was 66+/-9.7 kg (+/- s.d.); blood volume was 196+/-20 ml kg(-1); and hemoglobin concentration was 23.5+/-1.5 g dl(-1). Rest apneas ranged in duration from 3.1 to 10.9 min. Arterial P(O)2 declined exponentially during apnea, ranging between a maximum of 108 mmHg and a minimum of 18 mmHg after a 9.1 min breath-hold. Venous P(O)2 values were indistinguishable from arterial values after the first minute of apnea; the lowest venous P(O)2 recorded was 15 mmHg after a 7.8 min apnea. O(2) contents were also similar between the arterial and venous systems, declining linearly at rates of 2.3 and 2.0 ml O(2) dl(-1) min(-1), respectively, from mean initial values of 27.2 and 26.0 ml O(2) dl(-1). These blood O(2) depletion rates are approximately twice the reported values during forced submersion and are consistent with maintenance of previously measured high cardiac outputs during rest-associated breath-holds. During a typical 7-min apnea, seals consumed, on average, 56% of the initial blood O(2) store of 52 ml O(2) kg(-1); this contributed 4.2 ml O(2) kg(-1) min(-1) to total body metabolic rate during the breath-hold. Extreme hypoxemic tolerance in these seals was demonstrated by arterial P(O)2 values during late apnea that were less than human thresholds for shallow-water blackout. Despite such low P(O)2s, there was no evidence of significant anaerobic metabolism, as changes in blood pH were minimal and attributable to increased P(CO)2. These findings and the previously reported lack of lactate

  15. Alteration of blood glucose levels in the rat following exposure to hyperbaric oxygen.

    PubMed

    Eynan, Mirit; Mullokandov, Michael; Krinsky, Nitzan; Biram, Adi; Arieli, Yehuda

    2015-09-01

    Findings regarding blood glucose level (BGL) on exposure to hyperbaric oxygen (HBO) are contradictory. We investigated the influence of HBO on BGL, and of BGL on latency to central nervous system oxygen toxicity (CNS-OT). The study was conducted on five groups of rats: Group 1, exposure to oxygen at 2.5 atmospheres absolute (ATA), 90 min/day for 7 days; Group 2, exposure to oxygen once a week from 2 to 6 ATA in increments of 1 ATA/wk, for a period of time calculated as 60% of the latency to CNS-OT (no convulsions); Group 3, exposure to 6 ATA breathing a gas mixture with a pO2 of 0.21; Group 4, received 10 U/kg insulin to induce hypoglycemia before exposure to HBO; Group 5, received 33% glucose to induce hyperglycemia before exposure to HBO. Blood samples were drawn before and after exposures for measurement of BGL. No change was observed in BGL after exposure to oxygen at 2.5 ATA, 90 min/day for 7 days. BGL was significantly elevated after exposure to oxygen at 6 ATA until the appearance of convulsions, and following exposure to 4, 5, and 6 ATA without convulsions (P < 0.01). No change was observed in BGL after exposure to 6 ATA breathing a gas mixture with a pO2 of 0.21. Hypoglycemia shortened latency to CNS oxygen toxicity, whereas hyperglycemia had no effect. Our results demonstrate an influence of HBO exposure on elevation of BGL, starting at 4 ATA. This implies that BGL may serve as a marker for the generation of CNS-OT. PMID:26183474

  16. Computational modeling of acute myocardial infarction.

    PubMed

    Sáez, P; Kuhl, E

    2016-01-01

    Myocardial infarction, commonly known as heart attack, is caused by reduced blood supply and damages the heart muscle because of a lack of oxygen. Myocardial infarction initiates a cascade of biochemical and mechanical events. In the early stages, cardiomyocytes death, wall thinning, collagen degradation, and ventricular dilation are the immediate consequences of myocardial infarction. In the later stages, collagenous scar formation in the infarcted zone and hypertrophy of the non-infarcted zone are auto-regulatory mechanisms to partly correct for these events. Here we propose a computational model for the short-term adaptation after myocardial infarction using the continuum theory of multiplicative growth. Our model captures the effects of cell death initiating wall thinning, and collagen degradation initiating ventricular dilation. Our simulations agree well with clinical observations in early myocardial infarction. They represent a first step toward simulating the progression of myocardial infarction with the ultimate goal to predict the propensity toward heart failure as a function of infarct intensity, location, and size. PMID:26583449

  17. Pionic carbon/oxygen capture ratios in blood and muscle tissue of pig.

    PubMed

    Yamaguchi, C; Mares, V; Blattmann, H

    1987-10-01

    The pionic carbon/oxygen capture ratio for the blood and muscle tissue of a pig was measured using an intrinsic Ge detector in order to investigate possible explanations for an enhanced lesion observed in the autopsy of pion-irradiated patients. Pure iron was also irradiated in order to determine the energies and intensities of pionic x-rays from iron. It was expected that some of them originated from haemoglobin and could be observed in the spectrum for a blood sample. TE plastic (Shonka A-150) and Lucite were also investigated for comparison with other work. PMID:3685101

  18. Energetic atomic and ionic oxygen textured optical surfaces for blood glucose monitoring

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A. (Inventor)

    2007-01-01

    Disclosed is a method and the resulting product thereof comprising a solid light-conducting fiber with a point of attachment and having a textured surface site consisting a textured distal end prepared by being placed in a vacuum and then subjected to directed hyperthermal beams comprising oxygen ions or atoms. The textured distal end comprises cones or pillars that are spaced upon from each other by less than 1 micron and are extremely suitable to prevent cellular components of blood from entering the valleys between the cones or pillars so as to effectively separate the cellular components in the blood from interfering with optical sensing of the glucose concentration for diabetic patients.

  19. Diagnostic Value of PET-Measured Heterogeneity in Myocardial Blood Flows during CPT for the Identification of Coronary Vasomotor Dysfunction

    PubMed Central

    Schindler, Thomas H.; Zhang, Xiao-Li; Vincenti, Gabriella; Mhiri, Leila; Nkoulou, Rene; Just, Hanjoerg; Ratib, Osman; Mach, Francois; Dahlbom, Magnus; Schelbert, Heinrich R

    2009-01-01

    Background To evaluate the diagnostic value of a PET-measured heterogeneity in longitudinal myocardial blood flow (MBF) during cold pressor testing (CPT) and global MBF response to CPT from rest (ΔMBF) for identification of coronary vasomotor dysfunction. Methods and Results In 35 patients, CPT-induced alterations in epicardial luminal area were determined with quantitative angiography as reference. MBF was assessed over the whole left ventricle as global MBF, and regionally in the mid and mid-distal myocardium as MBF difference or MBF heterogeneity with 13N-ammonia and PET. The sensitivity and specifity of a longitudinal MBF difference in the identification of epicardial vasomotor dysfunction was significantly higher than the global ΔMBF to CPT, respectively (88% vs. 79% and 82% vs. 64%, p<0.05). Combining both parameters resulted in an optimal sensitivity of 100% at the expense of an intermediate specifity of 73%. The diagnostic accuracy was highest for the combined analysis, than those for the MBF difference or global ΔMBF alone (91 vs. 86% and 74%, respectively, p<0.05). Conclusions The combined evaluation of a CPT-induced heterogeneity in longitudinal MBF and the change in global MBF from rest may emerge as a new promising analytic approach to further optimize the identification and characterization of coronary vasomotor dysfunction. PMID:17826322

  20. Blood flow and oxygenation in peritendinous tissue and calf muscle during dynamic exercise in humans

    PubMed Central

    Boushel, Robert; Langberg, Henning; Green, Simon; Skovgaard, Dorthe; Bülow, Jens; Kjær, Michael

    2000-01-01

    Circulation around tendons may act as a shunt for muscle during exercise. The perfusion and oxygenation of Achilles' peritendinous tissue was measured in parallel with that of calf muscle during exercise to determine (1) whether blood flow is restricted in peritendinous tissue during exercise, and (2) whether blood flow is coupled to oxidative metabolism. Seven individuals performed dynamic plantar flexion from 1 to 9 W. Radial artery and popliteal venous blood were sampled for O2, peritendinous blood flow was determined by 133Xe-washout, calf blood flow by plethysmography, cardiac output by dye dilution, arterial pressure by an arterial catheter-transducer, and muscle and peritendinous O2 saturation by spatially resolved spectroscopy (SRS). Calf blood flow rose 20-fold with exercise, reaching 44 ± 7 ml (100 g)−1 min−1 (mean ± s.e.m.) at 9 W, while Achilles' peritendinous flow increased (7-fold) to 14 ± 4 ml (100 g)−1 min−1, which was 18 % of the maximal flow established during reactive hyperaemia. SRS-O2 saturation fell both in muscle (from 66 ± 2 % at rest to 57 ± 3 %, P < 0.05) and in peritendinous regions (58 ± 4 to 52 ± 4 %, P < 0.05) during exercise along with a rise in leg vascular conductance and microvascular haemoglobin volume, despite elevated systemic vascular resistance. The parallel rise in calf muscle and peritendinous blood flow and fall in O2 saturation during exercise indicate that blood flow is coupled to oxidative metabolism in both tissue regions. Increased leg vascular conductance accompanied by elevated microvascular haemoglobin volume reflect vasodilatation in both muscle and peritendinous regions. However, peak exercise peritendinous blood flow reaches only ≈20 % of its maximal blood flow capacity. PMID:10747200

  1. Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues

    PubMed Central

    Tzoumas, Stratis; Nunes, Antonio; Olefir, Ivan; Stangl, Stefan; Symvoulidis, Panagiotis; Glasl, Sarah; Bayer, Christine; Multhoff, Gabriele; Ntziachristos, Vasilis

    2016-01-01

    Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation, an effect that causes spectral corruption. Spectral corruption has limited the quantification accuracy of optical and optoacoustic spectroscopic methods, and impeded the goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical goal for the assessment of oxygenation in physiological processes and disease. Here we describe light fluence in the spectral domain and introduce eigenspectra multispectral optoacoustic tomography (eMSOT) to account for wavelength-dependent light attenuation, and estimate blood sO2 within deep tissue. We validate eMSOT in simulations, phantoms and animal measurements and spatially resolve sO2 in muscle and tumours, validating our measurements with histology data. eMSOT shows substantial sO2 accuracy enhancement over previous optoacoustic methods, potentially serving as a valuable tool for imaging tissue pathophysiology. PMID:27358000

  2. Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues.

    PubMed

    Tzoumas, Stratis; Nunes, Antonio; Olefir, Ivan; Stangl, Stefan; Symvoulidis, Panagiotis; Glasl, Sarah; Bayer, Christine; Multhoff, Gabriele; Ntziachristos, Vasilis

    2016-01-01

    Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation, an effect that causes spectral corruption. Spectral corruption has limited the quantification accuracy of optical and optoacoustic spectroscopic methods, and impeded the goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical goal for the assessment of oxygenation in physiological processes and disease. Here we describe light fluence in the spectral domain and introduce eigenspectra multispectral optoacoustic tomography (eMSOT) to account for wavelength-dependent light attenuation, and estimate blood sO2 within deep tissue. We validate eMSOT in simulations, phantoms and animal measurements and spatially resolve sO2 in muscle and tumours, validating our measurements with histology data. eMSOT shows substantial sO2 accuracy enhancement over previous optoacoustic methods, potentially serving as a valuable tool for imaging tissue pathophysiology. PMID:27358000

  3. Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues

    NASA Astrophysics Data System (ADS)

    Tzoumas, Stratis; Nunes, Antonio; Olefir, Ivan; Stangl, Stefan; Symvoulidis, Panagiotis; Glasl, Sarah; Bayer, Christine; Multhoff, Gabriele; Ntziachristos, Vasilis

    2016-06-01

    Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation, an effect that causes spectral corruption. Spectral corruption has limited the quantification accuracy of optical and optoacoustic spectroscopic methods, and impeded the goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical goal for the assessment of oxygenation in physiological processes and disease. Here we describe light fluence in the spectral domain and introduce eigenspectra multispectral optoacoustic tomography (eMSOT) to account for wavelength-dependent light attenuation, and estimate blood sO2 within deep tissue. We validate eMSOT in simulations, phantoms and animal measurements and spatially resolve sO2 in muscle and tumours, validating our measurements with histology data. eMSOT shows substantial sO2 accuracy enhancement over previous optoacoustic methods, potentially serving as a valuable tool for imaging tissue pathophysiology.

  4. Acrolein-Induced Increases in Blood Pressure and Heart Rate Are Coupled with Decreased Blood Oxygen Levels During Exposure in Hypertensive Rats

    EPA Science Inventory

    Exposure to air pollution increases the risk of cardiovascular morbidity and mortality, especially in individuals with pre-existing cardiovascular disease. Recent studies link exposure to air pollution with reduced blood oxygen saturation suggesting that hypoxia is a potential me...

  5. A miniaturized extracorporeal membrane oxygenator with integrated rotary blood pump: preclinical in vivo testing.

    PubMed

    Kopp, Ruedger; Bensberg, Ralf; Arens, Jutta; Steinseifer, Ulrich; Schmitz-Rode, Thomas; Rossaint, Rolf; Henzler, Dietrich

    2011-01-01

    Extracorporeal membrane oxygenation can achieve sufficient gas exchange in severe acute respiratory distress syndrome. A highly integrated extracorporeal membrane oxygenator (HEXMO) was developed to reduce filling volume and simplify management. Six female pigs were connected to venovenous HEXMO with a total priming volume of 125 ml for 4 hours during hypoxemia induced by a hypoxic inspired gas mixture. Animals were anticoagulated with intravenous heparin. Gas exchange, hemodynamics, hemolysis, and coagulation activation were examined. One device failed at the magnetic motor coupling of the integrated diagonal pump. In the remaining five experiments, the oxygenation increased significantly (arterial oxygen saturation [SaO2] from 79 ± 5% before HEXMO to 92% ± 11% after 4 hours) facilitated by a mean oxygen transfer of 66 ± 29 ml/dl through the oxygenator. The CO2 elimination by the HEXMO reduced arterial PaCO2 only marginal. Extracorporeal blood flow was maintained at 32% ± 6% of cardiac output. Hemodynamic instability or hemolysis was not observed. The plasmatic coagulation was only mildly activated without significant platelet consumption. The HEXMO prototype provided sufficient gas exchange to prevent hypoxemia. This proof of concept study supports further development and design modifications to increase performance and to reduce coagulation activation for potential long-term application. PMID:21317635

  6. Investigation of oesophageal photoplethysmographic signals and blood oxygen saturation measurements in cardiothoracic surgery patients.

    PubMed

    Kyriacou, P A; Powell, S; Langford, R M; Jones, D P

    2002-08-01

    Pulse oximeter probes attached to the finger may fail to estimate blood oxygen saturation (SpO2) in patients with compromised peripheral perfusion (e.g. hypothermic cardiopulmonary bypass surgery). The measurement of SpO2 from a central organ such as the oesophagus is suggested as an alternative to overcome this problem. A reflectance oesophageal pulse oximeter probe and a processing system implemented in LabVIEW were developed. The system was evaluated in clinical measurements on 50 cardiothoracic surgery patients. Oesophageal photoplethysmographic (PPG) signals with large amplitudes and high signal-to-noise ratios were measured from various depths within the oesophagus from all the cardiothoracic patients. The oesophageal PPG amplitudes from these patients were in good agreement with previous oesophageal PPG amplitude measurements from healthy anaesthetized patients. The oesophageal pulse oximeter SpO2 results agreed well with the estimated arterial oxygen saturation (SaO2) values inferred from the oxygen tension obtained by blood gas analysis. The mean (+/- SD) of the differences between the oesophageal pulse oximeter SpO2 readings and those from blood gas analysis was 0.02 +/- 0.88%. Also, the oesophageal pulse oximeter was found to be reliable and accurate in five cases of poor peripheral perfusion when a commercial finger pulse oximeter probe failed to estimate oxygen saturation values for at least 10 min. These results suggest that the arterial blood circulation to the oesophagus is less subject to vasoconstriction and decreased PPG amplitudes than are the peripheral sites used for pulse oximetry such as the finger. It is concluded that oesophageal SPO2 monitoring may be of clinical value. PMID:12214761

  7. The importance of the negative blood-oxygenation-level-dependent (BOLD) response in the somatosensory cortex.

    PubMed

    Klingner, Carsten M; Brodoehl, Stefan; Witte, Otto W

    2015-01-01

    In recent years, multiple studies have shown task-induced negative blood-oxygenation-level-dependent responses (NBRs) in multiple brain regions in humans and animals. Converging evidence suggests that task-induced NBRs can be interpreted in terms of decreased neuronal activity. However, the vascular and metabolic dynamics and functional importance of the NBR are highly debated. Here, we review studies investigating the origin and functional importance of the NBR, with special attention to the somatosensory cortex. PMID:26057216

  8. Impaired cerebral blood flow and oxygenation during exercise in type 2 diabetic patients

    PubMed Central

    Kim, Yu-Sok; Seifert, Thomas; Brassard, Patrice; Rasmussen, Peter; Vaag, Allan; Nielsen, Henning B; Secher, Niels H; van Lieshout, Johannes J

    2015-01-01

    Endothelial vascular function and capacity to increase cardiac output during exercise are impaired in patients with type 2 diabetes (T2DM). We tested the hypothesis that the increase in cerebral blood flow (CBF) during exercise is also blunted and, therefore, that cerebral oxygenation becomes affected and perceived exertion increased in T2DM patients. We quantified cerebrovascular besides systemic hemodynamic responses to incremental ergometer cycling exercise in eight male T2DM and seven control subjects. CBF was assessed from the Fick equation and by transcranial Doppler-determined middle cerebral artery blood flow velocity. Cerebral oxygenation and metabolism were evaluated from the arterial-to-venous differences for oxygen, glucose, and lactate. Blood pressure was comparable during exercise between the two groups. However, the partial pressure of arterial carbon dioxide was lower at higher workloads in T2DM patients and their work capacity and increase in cardiac output were only ∽80% of that established in the control subjects. CBF and cerebral oxygenation were reduced during exercise in T2DM patients (P < 0.05), and they expressed a higher rating of perceived exertion (P < 0.05). In contrast, CBF increased ∽20% during exercise in the control group while the brain uptake of lactate and glucose was similar in the two groups. In conclusion, these results suggest that impaired CBF and oxygenation responses to exercise in T2DM patients may relate to limited ability to increase cardiac output and to reduced vasodilatory capacity and could contribute to their high perceived exertion. PMID:26109188

  9. Near-infrared spectroscopy determined cerebral oxygenation with eliminated skin blood flow in young males.

    PubMed

    Hirasawa, Ai; Kaneko, Takahito; Tanaka, Naoki; Funane, Tsukasa; Kiguchi, Masashi; Sørensen, Henrik; Secher, Niels H; Ogoh, Shigehiko

    2016-04-01

    We estimated cerebral oxygenation during handgrip exercise and a cognitive task using an algorithm that eliminates the influence of skin blood flow (SkBF) on the near-infrared spectroscopy (NIRS) signal. The algorithm involves a subtraction method to develop a correction factor for each subject. For twelve male volunteers (age 21 ± 1 yrs) +80 mmHg pressure was applied over the left temporal artery for 30 s by a custom-made headband cuff to calculate an individual correction factor. From the NIRS-determined ipsilateral cerebral oxyhemoglobin concentration (O2Hb) at two source-detector distances (15 and 30 mm) with the algorithm using the individual correction factor, we expressed cerebral oxygenation without influence from scalp and scull blood flow. Validity of the estimated cerebral oxygenation was verified during cerebral neural activation (handgrip exercise and cognitive task). With the use of both source-detector distances, handgrip exercise and a cognitive task increased O2Hb (P < 0.01) but O2Hb was reduced when SkBF became eliminated by pressure on the temporal artery for 5 s. However, when the estimation of cerebral oxygenation was based on the algorithm developed when pressure was applied to the temporal artery, estimated O2Hb was not affected by elimination of SkBF during handgrip exercise (P = 0.666) or the cognitive task (P = 0.105). These findings suggest that the algorithm with the individual correction factor allows for evaluation of changes in an accurate cerebral oxygenation without influence of extracranial blood flow by NIRS applied to the forehead. PMID:26018458

  10. Cerebral oxygen metabolism and blood flow in human cerebral ischemic infarction

    SciTech Connect

    Lenzi, G.L.; Frackowiak, R.S.; Jones, T.

    1982-09-01

    Fifteen patients with acute cerebral hemispheric infarcts have been studied with positron emission tomography and the /sup 15/O steady-state inhalation technique. Thirteen follow-up studies were also performed. The values of cerebral oxygen metabolism (CMRO/sub 2/), cerebral blood flow (CBF), and oxygen extraction ration (OER) have been calculated for the infarcted regions, their borders, the symmetrical regions in contralateral cerebral hemispheres, and the cerebellar hemispheres. This study demonstrates that in the completed stroke there are thresholds for regional CMRO/sub 2/ and regional CBF below which the general clinical outcome of the patients is usually poor. The ischaemic lesions invariably produce an uncoupling between the greatly decreased metabolic demand and the less affected blood supply, with very frequent instances of relative hyperperfusion. Remote effects of the hemispheric infarcts have been demonstrated, such as crossed cerebellar diaschisis and contralateral transhemispheric depression. The level of consciousness correlates with oxygen uptake and blood flow both in the posterior fossa and in the contralateral cerebral hemispheres. The follow-up studies of individual patients underline the high variability of metabolism-to-flow balance during the acute phase of the illness, and stress the need for more studies focused on repeated assessments of homogeneous patient populations.

  11. Simultaneous two-photon imaging of oxygen and blood flow in deep cerebral vessels.

    PubMed

    Lecoq, Jérôme; Parpaleix, Alexandre; Roussakis, Emmanuel; Ducros, Mathieu; Goulam Houssen, Yannick; Vinogradov, Sergei A; Charpak, Serge

    2011-07-01

    Uncovering principles that regulate energy metabolism in the brain requires mapping of partial pressure of oxygen (PO(2)) and blood flow with high spatial and temporal resolution. Using two-photon phosphorescence lifetime microscopy (2PLM) and the oxygen probe PtP-C343, we show that PO(2) can be accurately measured in the brain at depths up to 300 μm with micron-scale resolution. In addition, 2PLM allowed simultaneous measurements of blood flow and of PO(2) in capillaries with less than one-second temporal resolution. Using this approach, we detected erythrocyte-associated transients (EATs) in oxygen in the rat olfactory bulb and showed the existence of diffusion-based arterio-venous shunts. Sensory stimulation evoked functional hyperemia, accompanied by an increase in PO(2) in capillaries and by a biphasic PO(2) response in the neuropil, consisting of an 'initial dip' and a rebound. 2PLM of PO(2) opens new avenues for studies of brain metabolism and blood flow regulation. PMID:21642977

  12. Simultaneous two-photon imaging of oxygen and blood flow in deep cerebral vessels

    PubMed Central

    Lecoq, Jérôme; Parpaleix, Alexandre; Roussakis, Emmanuel; Ducros, Mathieu; Houssen, Yannick Goulam; Vinogradov, Sergei A; Charpak, Serge

    2012-01-01

    Uncovering principles that regulate energy metabolism in the brain requires mapping of partial pressure of oxygen (PO2) and blood flow with high spatial and temporal resolution. Using two-photon phosphorescence lifetime microscopy (2PLM) and the oxygen probe PtP-C343, we show that PO2 can be accurately measured in the brain at depths up to 300 μm with micron-scale resolution. In addition, 2PLM allowed simultaneous measurements of blood flow and of PO2 in capillaries with less than one-second temporal resolution. Using this approach, we detected erythrocyte-associated transients (EATs) in oxygen in the rat olfactory bulb and showed the existence of diffusion-based arterio-venous shunts. Sensory stimulation evoked functional hyperemia, accompanied by an increase in PO2 in capillaries and by a biphasic PO2 response in the neuropil, consisting of an ‘initial dip’ and a rebound. 2PLM of PO2 opens new avenues for studies of brain metabolism and blood flow regulation. PMID:21642977

  13. Regulation of brain blood flow and oxygen delivery in elite breath-hold divers.

    PubMed

    Willie, Christopher K; Ainslie, Philip N; Drvis, Ivan; MacLeod, David B; Bain, Anthony R; Madden, Dennis; Maslov, Petra Zubin; Dujic, Zeljko

    2015-01-01

    The roles of involuntary breathing movements (IBMs) and cerebral oxygen delivery in the tolerance to extreme hypoxemia displayed by elite breath-hold divers are unknown. Cerebral blood flow (CBF), arterial blood gases (ABGs), and cardiorespiratory metrics were measured during maximum dry apneas in elite breath-hold divers (n=17). To isolate the effects of apnea and IBM from the concurrent changes on ABG, end-tidal forcing ('clamp') was then used to replicate an identical temporal pattern of decreasing arterial PO2 (PaO2) and increasing arterial PCO2 (PaCO2) while breathing. End-apnea PaO2 ranged from 23 to 37 mm Hg (30 ± 7 mm Hg). Elevation in mean arterial pressure was greater during apnea than during clamp reaching +54 ± 24% versus 34 ± 26%, respectively; however, CBF increased similarly between apnea and clamp (93.6 ± 28% and 83.4 ± 38%, respectively). This latter observation indicates that during the overall apnea period IBM per se do not augment CBF and that the brain remains sufficiently protected against hypertension. Termination of apnea was not determined by reduced cerebral oxygen delivery; despite 40% to 50% reductions in arterial oxygen content, oxygen delivery was maintained by commensurately increased CBF. PMID:25370857

  14. Effects of dichloroacetate on myocardial substrate extraction, epicardial ST-segment elevation, and ventricular blood flow following coronary occlusion in dogs.

    PubMed

    Mjos, O D; Miller, N E; Riemersma, R A; Oliver, M F

    1976-07-01

    Glucose metabolism in the healthy heart is stimulated by dichloroacetate (DCA). The possibility has been examined in dogs that DCA, by increasing glucose utilization, might limit the severity of acute myocardial ischaemic injury. Intravenous administration of DCA reduced the degree of epicardial ST-segment elevation induced by subsequent coronary occlusion, both under basal conditions and during isoprenaline infusion. A similar result was obtained when DCA was given during an established coronary occlusion. This effect could not be explained by changes in mean aortic blood pressure, heart rate, or regional myocardial blood flow as measured by radioactive microspheres. Measurements in arterial and coronary sinus blood demonstrated an increase in the extraction of glucose and a decrease in that of FFA by the heart. Glucose extraction also tended to be increased in the ischaemic zone, as shown by the differences in the concentrations of these substrates between arterial blood and blood obtained from the local vein draining that zone. Lactate release by the ischaemic zone was markedly reduced. PMID:947332

  15. Myocardial protection: what the anesthesiologist does.

    PubMed

    Merin, R G

    1990-09-01

    The role of the anesthesiologist in myocardial protection is to optimize myocardial oxygen balance during the perioperative period. Nonpharmacological steps that can be taken to achieve this revolve around maintaining a satisfactory hemoglobin concentration and oxyhemoglobin saturation through maximizing ventilation. In addition, alkalosis and hypothermia should be prevented since they cause a left shift of the oxyhemoglobin dissociation curve, thus interfering with tissue oxygen delivery. Hypocarbia increases coronary vascular resistance. Blood volume must be adequate with an optimal hemoglobin concentration. Pharmacological measures should also be used, and it is important to continue through the perioperative period any previously administered cardioactive drugs. Furthermore, in the prebypass period, tachycardia may not be controlled by anesthetics; unless the tachycardia is paroxysmal, beta blockers are the drugs of choice. Depending on the cause, diastolic hypotension also needs to be treated either with volume, vasoconstrictors, or inotropes. Likewise, major hypertension can produce increased demand and, again depending on the cause, either anesthetics, vasodilators, beta blockers, or calcium blockers may be useful. Finally, myocardial ischemia without obvious cause probably should be treated with nitroglycerin or calcium blockers. During surgery, the effect of the anesthetic drugs on myocardial oxygen balance is important. PMID:2133851

  16. Aminoguanidine effects on nerve blood flow, vascular permeability, electrophysiology, and oxygen free radicals

    SciTech Connect

    Kihara, Mikihiro; Schmelzer, J.D.; Poduslo, J.F.; Curran, G.L.; Nickander, K.K.; Low, P.A. )

    1991-07-15

    Since advanced glycosylation end products have been suggested to mediate hyperglycemia-induced microvascular atherogenesis and because aminoguanidine (AG) prevents their generation, the authors examined whether AG could prevent or ameliorate the physiologic and biochemical indices of streptozotocin (STZ)-induced experimental diabetic neuropathy. Four groups of adult Sprague-Dawley rats were studied: group I received STZ plus AG, group II received STZ plus AG, group III received STZ alone, and group IV was a control. They monitored conduction and action potential amplitudes serially in sciatic-tibial and caudal nerves, nerve blood flow, oxygen free radical activity (conjugated dienes and hydroperoxides), and the product of the permeability coefficient and surface area to {sup 125}I-labeled albumin. STZ-induced diabetes (group III) caused a 57% reduction in nerve blood flow and in abnormal nerve conduction and amplitudes and a 60% increase in conjugated dienes. Nerve blood flow was normalized by 8 weeks with AG (groups I and II) and conduction was significantly improved, in a dose-dependent manner, by 16 and 24 weeks in sciatic-tibial and caudal nerves, respectively. The permeability coefficient was not impaired, suggesting a normal blood-nerve barrier function for albumin, and the oxygen free-radical indices were not ameliorated by AG. They suggest that AG reverses nerve ischemia and more gradually improves their electrophysiology by an action on nerve microvessels. AG may have potential in the treatment of diabetic neuropathy.

  17. Severe blood loss anemia in a Jehovah's Witness treated with adjunctive hyperbaric oxygen therapy.

    PubMed

    Graffeo, Charles; Dishong, William

    2013-04-01

    We describe the case of a 39-year-old African-American woman who developed sudden onset, near-term placental abruption with severe blood loss anemia whose religious beliefs precluded her from receiving any blood products. The patient had lost most of her blood volume, with a reported hemoglobin level of 1.9 g/dL, developed multisystem failure, and disseminated intravascular coagulation with bilateral deep venous thrombosis. Adjunctive hyperbaric oxygenation (HBO) therapy was considered, and the patient was referred for treatment. The patient required ventilatory support as well as vasopressors and hemodialysis. HBO therapy occured in a monoplace chamber setting at 2.0 atmospheres absolute for 90 minutes per treatment up to twice daily depending on patients clinical status. The patient underwent a total of 30 HBO treatments and had sustained improvement in all hemodynamic parameters, red blood cell volume, renal and respiratory function. She was discharged to a rehabilitation facility on hospital day 29 and then to home, soon thereafter. The patient had no evidence of sustained physical or cognitive impairment at time of discharge, and there were no reported complications associated with HBO therapy. Adjunctive HBO therapy should be considered in the management of patients with exceptional severe blood loss anemia who refuse the use of blood products. PMID:23380087

  18. Kinetics of /sup 13/N-ammonia uptake in myocardial single cells indicating potential limitations in its applicability as a marker of myocardial blood flow

    SciTech Connect

    Rauch, B.; Helus, F.; Grunze, M.; Braunwell, E.; Mall, G.; Hasselbach, W.; Kuebler, W.

    1985-02-01

    To study kinetics and principles of cellular uptake of /sup 13/N-ammonia, a marker of coronary perfusion in myocardial scintigraphy, heart muscle cells of adult rats were isolated by perfusion with collagenase and hyaluronidase. Net uptake of /sup 13/N, measured by flow dialysis, reached equilibrium within 20 sec in the presence of sodium bicarbonate and carbon dioxide (pH 7.4, 37 degrees C). Total extraction, 80 sec after the reaction start, was 786 +/- 159 mumol/ml cell volume. Cells destroyed by calcium overload were unable to extract /sup 13/N-ammonia. Omission of bicarbonate and carbon dioxide reduced total extraction to 36% of control. /sup 13/N-Ammonia uptake could also be reduced by 50 muM 4,4' diisothiocyanostilbene 2,2' disulfonic acid, by 100 micrograms/ml 1-methionine sulfoximine, and by preincubation with 5 muM free oleic acid. These results indicate that in addition to metabolic trapping by glutamine synthetase, the extraction of /sup 13/N-ammonia by myocardial cells is influenced by cell membrane integrity, intracellular-extracellular pH gradient, and possibly an anion exchange system for bicarbonate. For this reason, the uptake of /sup 13/N-ammonia may not always provide a valid measurement of myocardial perfusion.

  19. Physiologic effects of transfusing red blood cells with high or low affinity for oxygen to passively hyperventilated, anemic baboons: systemic and cerebral oxygen extraction.

    PubMed Central

    Valeri, C R; Rorth, M; Zaroulis, C G; Jakubowski, M S; Vescera, S V

    1975-01-01

    Anemic, passively hyperventilated baboons were given preserved red blood cells either with increased or with slightly reduced affinity for oxygen to restore the red cell volume. In the high affinity group there was a 50% increase in cerebral blood flow immediately after the transfusion, but there was no significant change in the low affinity group. The cardiac output decreased slightly in the low affinity group, and increased slightly but insignificantly in the high affinity group. Two hours after transfusion the cerebral blood flow had returned to normal in the high affinity group. In both groups there was a decrease in arterial blood pH and an increase in Po2 in blood from the pulmonary artery and the jugular vein after transfusion. A 40% restoration of the 2,3 DPG level occurred within 4 hours of the transfusion of red cells with high affinity for oxygen, and this rapid increase was associated with increases in blood pH and inorganic phosphorus levels. Preserved red cells with high affinity for oxygen and low 2, 3 DPG levels significantly increased the cerebral circulation during the 2-hour posttransfusion period. These findings lend support to the recommendation that preserved red cells with normal or elevated 2,3 DPG levels be administered to patients in hemorrhagic or septic shock, and to patients subjected to extracorporeal circulation during cardiac surgery in order to lessen the demand for increased blood flow and to ensure adequate tissue oxygenation during the postoperative period. PMID:1119857

  20. Severe familial hypercholesterolemia impairs the regulation of coronary blood flow and oxygen supply during exercise.

    PubMed

    Bender, Shawn B; de Beer, Vincent J; Tharp, Darla L; Bowles, Douglas K; Laughlin, M Harold; Merkus, Daphne; Duncker, Dirk J

    2016-11-01

    Accelerated development of coronary atherosclerosis is a defining characteristic of familial hypercholesterolemia (FH). However, the recent data highlight a significant cardiovascular risk prior to the development of critical coronary stenosis. We, therefore, examined the hypothesis that FH produces coronary microvascular dysfunction and impairs coronary vascular control at rest and during exercise in a swine model of FH. Coronary vascular responses to drug infusions and exercise were examined in chronically instrumented control and FH swine. FH swine exhibited ~tenfold elevation of plasma cholesterol and diffuse coronary atherosclerosis (20-60 % plaque burden). Similar to our recent findings in the systemic vasculature in FH swine, coronary smooth muscle nitric oxide sensitivity was increased in vivo and in vitro with maintained endothelium-dependent vasodilation in vivo in FH. At rest and during exercise, FH swine exhibited increased myocardial O2 extraction resulting in reduced coronary venous SO2 and PO2 versus control. During exercise in FH swine, the transmural distribution of coronary blood flow was unchanged; however, a shift toward anaerobic cardiac metabolism was revealed by increased coronary arteriovenous H(+) concentration gradient. This shift was associated with a worsening of cardiac efficiency (relationship between cardiac work and O2 consumption) in FH during exercise owing, in part, to a generalized reduction in stroke volume which was associated with increased left atrial pressure in FH. Our data highlight a critical role for coronary microvascular dysfunction as a contributor to impaired myocardial O2 balance, cardiac ischemia, and impaired cardiac function prior to the development of critical coronary stenosis in FH. PMID:27624732

  1. Mitochondrial oxygen consumption in asexual and sexual blood stages of the human malarial parasite, Plasmodium falciparum.

    PubMed

    Krungkrai, J; Burat, D; Kudan, S; Krungkrai, S; Prapunwattana, P

    1999-12-01

    The two developmental stages of human malarial parasite Plasmodium falciparum, asexual and sexual blood stages, were continuously cultivated in vitro. Both asexual and sexual stages of the parasites were assayed for mitochondrial oxygen consumption by using a polarographic assay. The rate of oxygen consumption by both stages was found to be relatively low, and was not much different. Furthermore, the mitochondrial oxygen consumption by both stages was inhibited to various degrees by mammalian mitochondrial inhibitors that targeted each component of complexes I- IV of the respiratory system. The oxygen consumption by both stages was also affected by 5-fluoroorotate, a known inhibitor of enzyme dihydroorotate dehydrogenase of the pyrimidine pathway and by an antimalarial drug atovaquone that acted specifically on mitochondrial complex III of the parasite. Moreover, antimalarials primaquine and artemisinin had inhibitory effects on the oxygen consumption by both stages of the parasites. Our results suggest that P. falciparum in both developmental stages have functional mitochondria that operate a classical electron transport system, containing complexes I-IV, and linked to the pyrimidine biosynthetic pathway. PMID:10928353

  2. Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

    PubMed Central

    Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

    2016-01-01

    Objective The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. Methods The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Results Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). Conclusion In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin. PMID:27096671

  3. High-affinity hemoglobin and blood oxygen saturation in diving emperor penguins.

    PubMed

    Meir, Jessica U; Ponganis, Paul J

    2009-10-01

    The emperor penguin (Aptenodytes forsteri) thrives in the Antarctic underwater environment, diving to depths greater than 500 m and for durations longer than 23 min. To examine mechanisms underlying the exceptional diving ability of this species and further describe blood oxygen (O2) transport and depletion while diving, we characterized the O2-hemoglobin (Hb) dissociation curve of the emperor penguin in whole blood. This allowed us to (1) investigate the biochemical adaptation of Hb in this species, and (2) address blood O2 depletion during diving, by applying the dissociation curve to previously collected partial pressure of O2 (PO2) profiles to estimate in vivo Hb saturation (SO2) changes during dives. This investigation revealed enhanced Hb-O2 affinity (P50=28 mmHg, pH 7.5) in the emperor penguin, similar to high-altitude birds and other penguin species. This allows for increased O2 at low blood PO2 levels during diving and more complete depletion of the respiratory O2 store. SO2 profiles during diving demonstrated that arterial SO2 levels are maintained near 100% throughout much of the dive, not decreasing significantly until the final ascent phase. End-of-dive venous SO2 values were widely distributed and optimization of the venous blood O2 store resulted from arterialization and near complete depletion of venous blood O2 during longer dives. The estimated contribution of the blood O2 store to diving metabolic rate was low and highly variable. This pattern is due, in part, to the influx of O2 from the lungs into the blood during diving, and variable rates of tissue O2 uptake. PMID:19801437

  4. Microvascular experimental evidence on the relative significance of restoring oxygen carrying capacity vs. blood viscosity in shock resuscitation

    PubMed Central

    Salazar Vázquez, Beatriz Y.; Wettstein, Reto; Cabrales, Pedro; Tsai, Amy G.; Intaglietta, Marcos

    2010-01-01

    Summary The development of volume replacement fluids for resuscitation in hemorrhagic shock comprises oxygen carrying and non carrying fluids. Non oxygen carrying fluids or plasma expanders are used up to the transfusion trigger, and upon reaching this landmark either blood, and possibly in the near future oxygen carrying blood substitutes, are used. An experimental program in hemorrhagic shock using the hamster chamber window model allowed to compare the relative performance of most fluids proposed for shock resuscitation. This model allows investigating simultaneously the microcirculation and systemic reactions, in the awake condition, in a tissue isolated from the environment. Results from this program show that in general plasma expanders such as Ringer’s lactate and dextran 70 kDa do not sufficiently restore blood viscosity upon reaching the transfusion trigger, causing microvascular collapse. This is in part restored by a blood transfusion, independently of the oxygen carrying capacity of red blood cells. These results lead to the proposal that effective blood substitutes must be designed to prevent microvascular collapse, manifested in the decrease of functional capillary density. Achievement of this goal, in combination with the increase of oxygen affinity, significantly postpones the need for a blood transfusion, and lowers the total requirement of restoration of intrinsic oxygen carrying capacity. PMID:18502215

  5. An upgraded camera-based imaging system for mapping venous blood oxygenation in human skin tissue

    NASA Astrophysics Data System (ADS)

    Li, Jun; Zhang, Xiao; Qiu, Lina; Leotta, Daniel F.

    2016-07-01

    A camera-based imaging system was previously developed for mapping venous blood oxygenation in human skin. However, several limitations were realized in later applications, which could lead to either significant bias in the estimated oxygen saturation value or poor spatial resolution in the map of the oxygen saturation. To overcome these issues, an upgraded system was developed using improved modeling and image processing algorithms. In the modeling, Monte Carlo (MC) simulation was used to verify the effectiveness of the ratio-to-ratio method for semi-infinite and two-layer skin models, and then the relationship between the venous oxygen saturation and the ratio-to-ratio was determined. The improved image processing algorithms included surface curvature correction and motion compensation. The curvature correction is necessary when the imaged skin surface is uneven. The motion compensation is critical for the imaging system because surface motion is inevitable when the venous volume alteration is induced by cuff inflation. In addition to the modeling and image processing algorithms in the upgraded system, a ring light guide was used to achieve perpendicular and uniform incidence of light. Cross-polarization detection was also adopted to suppress surface specular reflection. The upgraded system was applied to mapping of venous oxygen saturation in the palm, opisthenar and forearm of human subjects. The spatial resolution of the oxygenation map achieved is much better than that of the original system. In addition, the mean values of the venous oxygen saturation for the three locations were verified with a commercial near-infrared spectroscopy system and were consistent with previously published data.

  6. Tissue blood flow and oxygen consumption measured with near-infrared frequency-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Paunescu, Lelia Adelina

    2001-12-01

    For decades, researchers have contributed with new ways of applying physics' principles to medicine. Moreover, researchers were involved in developing new, non-invasive instrumentation for medical applications. Recently, application of optical techniques in biology and medicine became an important field. Researchers found a non- invasive approach of using visible and near-infrared light as a probe for tissue investigation. Optical methods can contribute to medicine by offering the possibility of rapid, low-resolution, functional images and real-time devices. Near-infrared spectroscopy (NIRS) is a useful technique for the investigation of biological tissues because of the relatively low absorption of water and high absorption of oxy- and deoxy-hemoglobin in the near- infrared region of 750-900 nm. Due to these properties, the near-infrared light can penetrate biological tissues in the range of 0.5-2 cm, offering investigation possibility of deep tissues and differentiate among healthy and diseased tissues. This work represents the initial steps towards understanding and improving of the promising near- infrared frequency-domain technique. This instrument has a very important advantage: it can be used non-invasively to investigate many parts of the human body, including the brain. My research consists primarily of in vivo measurements of optical parameters such as absorption and reduced scattering coefficients and consequently, blood parameters such as oxy, deoxy, and total hemoglobin concentrations, tissue oxygen saturation, blood flow and oxygen consumption of skeletal muscle of healthy and diseased subjects. This research gives a solid background towards a ready- to-use instrument that can continuously, in real-time, measure blood parameters and especially blood oxygenation. This is a very important information in emergency medicine, for persons under intensive care, or undergoing surgery, organ transplant or other interventions.

  7. [Myocardial responses to ischemia].

    PubMed

    Borisenko, V G; Gubareva, E A; Kade, A Kh

    2010-01-01

    The paper details the types of a myocardial response to impaired blood flow, such as myocardial stunning, hibernation, ischemic preconditioning, warm-up phenomenon, ischemic postconditioning, remodeling, and infarction. According to the pathogenesis, the authors identify several types of myocardial dysfunction in transient ischemic attack--uptake, delivery; and a mixed one. It is concluded the myocardial response to damage depends on a combination of influencing factors, a number of pathophysiological processes starting in the acute phase of ischemia achieve its peak in the late period. PMID:20564927

  8. Effect of Post-Reconstruction Gaussian Filtering on Image Quality and Myocardial Blood Flow Measurement with N-13 Ammonia PET

    PubMed Central

    Kim, Hyeon Sik; Cho, Sang-Geon; Kim, Ju Han; Kwon, Seong Young; Lee, Byeong-il; Bom, Hee-Seung

    2014-01-01

    Objective(s): In order to evaluate the effect of post-reconstruction Gaussian filtering on image quality and myocardial blood flow (MBF) measurement by dynamic N-13 ammonia positron emission tomography (PET), we compared various reconstruction and filtering methods with image characteristics. Methods: Dynamic PET images of three patients with coronary artery disease (male-female ratio of 2:1; age: 57, 53, and 76 years) were reconstructed, using filtered back projection (FBP) and ordered subset expectation maximization (OSEM) methods. OSEM reconstruction consisted of OSEM_2I, OSEM_4I, and OSEM_6I with 2, 4, and 6 iterations, respectively. The images, reconstructed and filtered by Gaussian filters of 5, 10, and 15 mm, were obtained, as well as non-filtered images. Visual analysis of image quality (IQ) was performed using a 3-grade scoring system by 2 independent readers, blinded to the reconstruction and filtering methods of stress images. Then, signal-to-noise ratio (SNR) was calculated by noise and contrast recovery (CR). Stress and rest MBF and coronary flow reserve (CFR) were obtained for each method. IQ scores, stress and rest MBF, and CFR were compared between the methods, using Chi-square and Kruskal-Wallis tests. Results: In the visual analysis, IQ was significantly higher by 10 mm Gaussian filtering, compared to other sizes of filter (P<0.001 for both readers). However, no significant difference of IQ was found between FBP and various numbers of iteration in OSEM (P=0.923 and 0.855 for readers 1 and 2, respectively). SNR was significantly higher in 10 mm Gaussian filter. There was a significant difference in stress and rest MBF between several vascular territories. However CFR was not significantly different according to various filtering methods. Conclusion: Post-reconstruction Gaussian filtering with a filter size of 10 mm significantly enhances the IQ of N-13 ammonia PET-CT, without changing the results of CFR calculation. PMID:27408866

  9. Spatial mapping of blood flow and oxygen consumption in the human calf muscle using near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Fantini, Sergio; Hoimes, Matthew L.; Casavola, Claudia; Franceschini, Maria-Angela

    2001-05-01

    We have designed a new optical probe to perform spatially resolved measurements of blood flow and oxygen consumption over an area of about 4 x 4 cm2 of the lateral gastrocnemius muscle (calf muscle) of human subjects. The blood flow and the oxygen consumption were measured non- invasively with frequency-domain, near-infrared spectroscopy from the maximum rate of increase of the oxy- and deoxy- hemoglobin concentrations in the muscle during venous occlusion. In a preliminary test on one subject, involving measurements at rest and after exercise, we have found that the spatial variability of the measured blood flow and oxygen consumption is significantly greater than the variability of repeated measurements at a given tissue location. We have also observed a strong spatial dependence of the exercise-induced increase in blood flow and oxygen consumption.

  10. Validity of a theoretical model to examine blood oxygenation dependent optoacoustics

    NASA Astrophysics Data System (ADS)

    Saha, Ratan K.; Karmakar, Subhajit; Hysi, Eno; Roy, Madhusudan; Kolios, Michael C.

    2012-05-01

    A theoretical model investigating the dependence of optoacoustic (OA) signal on blood oxygen saturation (SO2) is discussed. The derivations for the nonbandlimited and bandlimited OA signals from many red blood cells (RBCs) are presented. The OA field generated by many RBCs was obtained by summing the OA field emitted by each RBC approximated as a fluid sphere. A Monte Carlo technique was employed generating the spatial organizations of RBCs in two-dimensional. The RBCs were assumed to have the same SO2 level in a simulated configuration. The fractional number of oxyhemoglobin molecules, confined in a cell, determined the cellular SO2 and also defined the blood SO2. For the nonbandlimited case, the OA signal amplitude decreased and increased linearly with blood SO2 when illuminated by 700 and 1000 nm radiations, respectively. The power spectra exhibited similar trends over the entire frequency range (MHz to GHz). For the bandlimited case, three acoustic receivers with 2, 10, and 50 MHz as the center frequencies were considered. The linear variations of the OA amplitude with blood SO2 were also observed for each receiver at those laser sources. The good agreement between simulated and published experimental results validates the model qualitatively.

  11. Influence of blood donation on oxygen uptake kinetics during moderate and heavy intensity cycle exercise.

    PubMed

    Gordon, D; Marshall, K; Connell, A; Barnes, R J

    2010-05-01

    The purpose of this study was to determine the effects of a reduced whole body blood volume on the kinetic response of VO(2) during moderate and heavy intensity exercise. Six males and four females (age, 21+/-2 yrs; height, 175.2+/-5.1 cm; weight, 66.4+/-2.8 kg; VO(2)max, 53.0+/-4.1 ml x kg (-1) x min(-1)), completed a square-wave cycling ramp test to determine ventilatory threshold (VT) and VO(2max). Kinetics trials were completed 24 h pre and post donation of 450 cm (3) of blood. The kinetics trials were moderate intensity (80%VT) and heavy intensity (Delta50% VT - VO(2max)). Breath-by-breath gas exchange, heart rate, blood pressure, haemoglobin O(2) saturation, and blood [lactate] were measured throughout the trials. Post-donation haemoglobin, haematocrit and erythrocyte count were all significantly reduced (pBlood donation caused a significant increase in resting heart rate (Por= 0.05), or in the amplitude of the slow component. The capacity of the cardiovascular system to meet the metabolic demands of skeletal muscle at the onset of exercise does not limit the oxygen uptake. PMID:20180178

  12. Quantitative BOLD: Mapping of Human Cerebral Deoxygenated Blood Volume and Oxygen Extraction Fraction: Default State

    PubMed Central

    He, Xiang; Yablonskiy, Dmitriy A.

    2014-01-01

    Since Ogawa et al. (Proc Natl Acad Sci USA 1990;87:9868–9872) made the fundamental discovery of blood oxygenation level-dependent (BOLD) contrast in MRI, most efforts have been directed toward the study of dynamic BOLD (i.e., temporal changes in the MRI signal during changes in brain activity). However, very little progress has been made in elucidating the nature of BOLD contrast during the resting or baseline state of the brain, which is important for understanding normal human performance because it accounts for most of the enormous energy budget of the brain. It is also crucial for deciphering the consequences of baseline-state impairment by cerebral vascular diseases. The objective of this study was to develop a BOLD MR-based method that allows quantitative evaluation of tissue hemodynamic parameters, such as the blood volume, deoxyhemoglobin concentration, and oxygen extraction fraction (OEF). The proposed method, which we have termed quantitative BOLD (qBOLD), is based on an MR signal model that incorporates prior knowledge about brain tissue composition and considers signals from gray matter (GM), white matter (WM), cerebrospinal fluid (CSF), and blood. A 2D gradient-echo sampling of spin-echo (GESSE) pulse sequence is used for the acquisition of the MRI signal. The method is applied to estimate the hemodynamic parameters of the normal human brain in the baseline state. PMID:17191227

  13. Simultaneous blood flow and blood oxygenation measurements using a combination of diffuse speckle contrast analysis and near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Seong, Myeongsu; Phillips, Zephaniah; Mai, Phuong Minh; Yeo, Chaebeom; Song, Cheol; Lee, Kijoon; Kim, Jae Gwan

    2016-02-01

    A combined diffuse speckle contrast analysis (DSCA)-near-infrared spectroscopy (NIRS) system is proposed to simultaneously measure qualitative blood flow and blood oxygenation changes in human tissue. The system employs an optical switch to alternate two laser sources at two different wavelengths and a CCD camera to capture the speckle image. Therefore, an optical density can be measured from two wavelengths for NIRS measurements and a speckle contrast can be calculated for DSCA measurements. In order to validate the system, a flow phantom test and an arm occlusion protocol for arterial and venous occlusion were performed. Shorter exposure times (<1 ms) show a higher drop (between 50% and 66%) and recovery of 1/KS2 values after occlusion (approximately 150%), but longer exposure time (3 ms) shows more consistent hemodynamic changes. For four subjects, the 1/KS2 values dropped to an average of 82.1±4.0% during the occlusion period and the average recovery of 1/KS2 values after occlusion was 109.1±0.8%. There was also an approximately equivalent amplitude change in oxyhemoglobin (OHb) and deoxyhemoglobin (RHb) during arterial occlusion (max RHb=0.0085±0.0024 mM/DPF, min OHb=-0.0057±0.0044 mM/DPF). The sensitivity of the system makes it a suitable modality to observe qualitative hemodynamic trends during induced physiological changes.

  14. Regulatory Effect of Low-Intensity Optical Radiation on Oxygenation of Blood Irradiated In Vivo and Metabolic Processes

    NASA Astrophysics Data System (ADS)

    Zalesskaya, G. A.; Laskina, O. V.

    2016-03-01

    For three series of blood samples, we have studied the effect of therapeutic doses of low-intensity optical radiation (LOR) on oxygenation parameters of blood irradiated in vivo, and also on the levels of some metabolites: lactate, glucose, cholesterol. The quality of blood oxygenation was assessed using three parameters: the partial pressure of oxygen pVO2, the oxygen saturation of hemoglobin SVO2, and the oxygen level in arterial and venous blood, varying under the influence of low-intensity optical radiation due to photodissociation of hemoglobin/ligand complexes. We have established that during photohemotherapy (PHT), including extracorporeal, supravascular, and intravenous blood irradiation, positive changes occur in the oxygenation parameters and the metabolite levels, while after the courses of PHT have been completed, the individual changes in such parameters in individual patients were both positive and negative. The regulatory effect of PHT was apparent in the tendency toward a decrease in high initial values and an increase in low initial values both for the oxygenation parameters and for the metabolites; but at the doses recommended for use, PHT had a regulatory but still not a normalizing effect.

  15. "Overshoot" of O₂ is required to maintain baseline tissue oxygenation at locations distal to blood vessels.

    PubMed

    Devor, Anna; Sakadzic, Sava; Saisan, Payam A; Yaseen, Mohammad A; Roussakis, Emmanuel; Srinivasan, Vivek J; Vinogradov, Sergei A; Rosen, Bruce R; Buxton, Richard B; Dale, Anders M; Boas, David A

    2011-09-21

    In vivo imaging of cerebral tissue oxygenation is important in defining healthy physiology and pathological departures associated with cerebral disease. We used a recently developed two-photon microscopy method, based on a novel phosphorescent nanoprobe, to image tissue oxygenation in the rat primary sensory cortex in response to sensory stimulation. Our measurements showed that a stimulus-evoked increase in tissue pO₂ depended on the baseline pO₂ level. In particular, during sustained stimulation, the steady-state pO₂ at low-baseline locations remained at the baseline, despite large pO₂ increases elsewhere. In contrast to the steady state, where pO₂ never decreased below the baseline, transient decreases occurred during the "initial dip" and "poststimulus undershoot." These results suggest that the increase in blood oxygenation during the hemodynamic response, which has been perceived as a paradox, may serve to prevent a sustained oxygenation drop at tissue locations that are remote from the vascular feeding sources. PMID:21940458

  16. Fiber optic spectroscopy of blood for oxygen saturation sensor development: hematocrit effect

    NASA Astrophysics Data System (ADS)

    Anderson, Charles D.; Wlodarczyk, Marek T.

    1993-05-01

    We present experimental results from fiberoptic spectroscopy apparatus measuring whole blood's optical attenuation over a continuous wavelength range of 0.6 - 1.0 micrometers . Relative optical density (OD) spectra at a number of hematocrit values and oxygenation levels is obtained. The role of hematocrit in affecting spectral shape is discussed based upon relatively simple relationships derived from experimental data. A specific partial differential equation emerges from the analysis. This equation relates scatter-dependent experimental OD to oxygen saturation, hematocrit and purely absorbing, nonscattering constituents--and is obeyed over an extended wavelength range. A three-wavelength algorithm using experimental absorbances at LED-compatible wavelengths accurately provides both hematocrit and oxygen saturation values, for hematocrit levels between 0.2 and 0.6 in the presence of oxygenated and reduced Hb species. Optical system comparison between spectroscopic data and modeled LED behavior indicates the algorithm can be mapped to the design and implementation of discrete components for clinical use.

  17. Simultaneous photoacoustic microscopy of microvascular anatomy, oxygen saturation, and blood flow.

    PubMed

    Ning, Bo; Kennedy, Matthew J; Dixon, Adam J; Sun, Naidi; Cao, Rui; Soetikno, Brian T; Chen, Ruimin; Zhou, Qifa; Kirk Shung, K; Hossack, John A; Hu, Song

    2015-03-15

    Capitalizing on the optical absorption of hemoglobin, photoacoustic microscopy (PAM) is uniquely capable of anatomical and functional characterization of the intact microcirculation in vivo. However, PAM of the metabolic rate of oxygen (MRO2) at the microscopic level remains an unmet challenge, mainly due to the inability to simultaneously quantify microvascular diameter, oxygen saturation of hemoglobin (sO2), and blood flow at the same spatial scale. To fill this technical gap, we have developed a multi-parametric PAM platform. By analyzing both the sO2-encoded spectral dependence and the flow-induced temporal decorrelation of photoacoustic signals generated by the raster-scanned mouse ear vasculature, we demonstrated-for the first time-simultaneous wide-field PAM of all three parameters down to the capillary level in vivo. PMID:25768144

  18. Modeling of a three-source perfusion and blood oxygenation sensor for transplant monitoring using multilayer Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Ibey, Bennett L.; Lee, Seungjoon; Ericson, M. Nance; Wilson, Mark A.; Cote, Gerard L.

    2004-06-01

    A Multi-Layer Monte Carlo (MLMC) model was developed to predict the results of in vivo blood perfusion and oxygenation measurement of transplanted organs as measured by an indwelling optical sensor. A sensor has been developed which uses three-source excitation in the red and infrared ranges (660, 810, 940 nm). In vitro data was taken using this sensor by changing the oxygenation state of whole blood and passing it through a single-tube pump system wrapped in bovine liver tissue. The collected data showed that the red signal increased as blood oxygenation increased and infrared signal decreased. The center wavelength of 810 nanometers was shown to be quite indifferent to blood oxygenation change. A model was developed using MLMC code that sampled the wavelength range from 600-1000 nanometers every 6 nanometers. Using scattering and absorption data for blood and liver tissue within this wavelength range, a five-layer model was developed (tissue, clear tubing, blood, clear tubing, tissue). The theoretical data generated from this model was compared to the in vitro data and showed good correlation with changing blood oxygenation.

  19. Blood oxygen affinity increases during digestion in the South American rattlesnake, Crotalus durissus terrificus.

    PubMed

    Bovo, Rafael P; Fuga, Adriana; Micheli-Campbell, Mariana A; Carvalho, José E; Andrade, Denis V

    2015-08-01

    Digesting snakes experience massive increases in metabolism that can last for many days and are accompanied by adjustments in the oxygen transport cascade. Accordingly, we examined the oxygen-binding properties of the blood in the South American rattlesnake (Crotalus durissus terrificus) during fasting and 24 and 48h after the snakes have ingested a rodent meal corresponding to 15% (±2%) of its own body mass. In general, oxygen-hemoglobin (Hb-O2) affinity was significantly increased 24h post-feeding, and then returned toward fasting values within 48h post-feeding. Content of organic phosphates ([NTP] and [NTP]/[Hb]), hemoglobin cooperativity (Hill's n), and Bohr Effect (ΔlogP50/ΔpH) were not affected by feeding. The postprandial increase in Hb-O2 affinity in the South American rattlesnake can be almost entirely ascribed by the moderate alkaline tide that follows meal ingestion. In general, digesting snakes were able to regulate blood metabolites at quite constant levels (e.g., plasma osmolality, lactate, glucose, and total protein levels). The level of circulating lipids, however, was considerably increased, which may be related to their mobilization, since lipids are known to be incorporated by the enterocytes after snakes have fed. In conclusion, our results indicate that the exceptional metabolic increment exhibited by C. d. terrificus during meal digestion is entirely supported by the aerobic pathways and that among the attending cardiorespiratory adjustments, pulmonary Hb-O2 loading is likely improved due to the increment in blood O2 affinity. PMID:25446935

  20. Peripheral venous blood oxygen saturation can be non-invasively estimated using photoplethysmography.

    PubMed

    Khan, Musabbir; Pretty, Christopher G; Amies, Alexander C; Elliott, Rodney B; Suhaimi, Fatanah M; Shaw, Geoffrey M; Chase, J Geoffrey

    2015-08-01

    Measurement of peripheral venous oxygen saturation (SvO2) is currently performed using invasive catheters or direct blood draw. The purpose of this study was to non-invasively determine SvO2 using a variation of pulse oximetry techniques. Artificial respiration-like modulations applied to the peripheral vascular system were used to infer regional SvO2 using photoplethysmography (PPG) sensors. To achieve this modulation, an artificial pulse generating system (APG) was developed to generate controlled, superficial perturbations on the finger using a pneumatic digit cuff. These low pressure and low frequency modulations affect blood volumes in veins to a much greater extent than arteries due to significant arterial-venous compliance differences. Ten healthy human volunteers were recruited for proof-ofconcept testing. The APG was set at a modulation frequency of 0.2 Hz (12 bpm) and 45-50 mmHg compression pressure. Initial analysis showed that induced blood volume changes in the venous compartment could be detected by PPG. Estimated arterial oxygen saturation (97% [IQR=96.1%-97.4%]) matches published values (95%-99%). Estimated venous oxygen saturation (93.2% [IQR=91.-93.9%]) agrees with reported ranges (92%-95%) measured in peripheral regions. The median difference between the two saturations was 3.6%, while the difference between paired measurements in each subject was statistically significant (p=0.002). These results demonstrate the feasibility of this method for real-time, low cost, non-invasive estimation of SvO2. Further validation of this method is warranted. PMID:26737758

  1. Measurement of changes in blood oxygenation using Multispectral Optoacoustic Tomography (MSOT) allows assessment of tumor development

    NASA Astrophysics Data System (ADS)

    Tomaszewski, Michal R.; Quiros-Gonzalez, Isabel; Joseph, James; Bohndiek, Sarah E.

    2016-03-01

    The ability to evaluate tumor oxygenation in the clinic could indicate prognosis and enable treatment monitoring, since oxygen deficient cancer cells are more resistant to chemotherapy and radiotherapy. MultiSpectral Optoacoustic Tomography (MSOT) is a hybrid technique combining the high contrast of optical imaging with the spatial resolution and penetration depth similar to ultrasound. We aim to demonstrate that MSOT can be used to monitor the development of tumor vasculature. To establish the relationship between MSOT derived imaging biomarkers and biological changes during tumor development, we performed MSOT on nude mice (n=10) bearing subcutaneous xenograft U87 glioblastoma tumors using a small animal optoacoustic tomography system. The mice were maintained under inhalation anesthesia during imaging and respired oxygen content was modified between 21% and 100%. The measurements from early (week 4) and late (week 7) stages of tumor development were compared. To further explore the functionality of the blood vessels, we examined the evolution of changes in the abundance of oxy- and deoxyhemoglobin in the tumors in response to a gas challenge. We found that the kinetics of the change in oxygen saturation (SO2) were significantly different between small tumors and the healthy blood vessels in nearby normal tissue (p=0.0054). Furthermore, we showed that there was a significant difference in the kinetics of the gas challenge between small and large tumors (p=0.0015). We also found that the tumor SO2 was significantly correlated (p=0.0057) with the tumor necrotic fraction as assessed by H&E staining in histology. In the future, this approach may be of use in the clinic as a method for tumor staging and assessment of treatment response.

  2. Resting-state blood oxygen level-dependent functional magnetic resonance imaging for presurgical planning.

    PubMed

    Kamran, Mudassar; Hacker, Carl D; Allen, Monica G; Mitchell, Timothy J; Leuthardt, Eric C; Snyder, Abraham Z; Shimony, Joshua S

    2014-11-01

    Resting-state functional MR imaging (rsfMR imaging) measures spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal and can be used to elucidate the brain's functional organization. It is used to simultaneously assess multiple distributed resting-state networks. Unlike task-based functional MR imaging, rsfMR imaging does not require task performance. This article presents a brief introduction of rsfMR imaging processing methods followed by a detailed discussion on the use of rsfMR imaging in presurgical planning. Example cases are provided to highlight the strengths and limitations of the technique. PMID:25441506

  3. Blood oxygenation level-dependent response to intragastric load of corn oil emulsion in conscious rats.

    PubMed

    Tsurugizawa, Tomokazu; Uematsu, Akira; Uneyama, Hisayuki; Torii, Kunio

    2009-12-01

    The postingestive actions after intragastric or oronasal stimulation of fat have been well investigated. The blood oxygenation level-dependent (BOLD) signal changes, however, after intragastric load of corn oil emulsion have yet to be elucidated. Here, using functional magnetic resonance imaging, we investigated the BOLD signal response to gut corn oil emulsion in nonanesthetized rats. Intragastrically infused 7% corn oil emulsion induced a BOLD signal increase in several brain regions, including the bilateral amygdala, hippocampus and the ventral tegmental area. These results indicate that the limbic system responds to gut corn oil emulsion and that activation of this system could promote the reinforcing action for food with high fat content. PMID:19918206

  4. Leakage of Oxygen from Blood and Water Samples Stored in Plastic and Glass Syringes

    PubMed Central

    Scott, Peter V.; Horton, J. N.; Mapleson, W. W.

    1971-01-01

    Theory and experiment showed that samples of blood and water stored in 2-ml and 5-ml syringes made of polypropylene, polystyrene, or S.A.N. co-polymer exchanged oxygen with their surroundings. In the first hour the exchange was due mainly to equilibration with the plastic of the syringe and only in small degree to permeation through the plastic. With high initial tension or with blood of low haemoglobin concentration the exchange can result in errors in Po2 of up to 6% in two minutes and 16% in 30 to 60 minutes. With all-glass syringes the exchange was much slower but, even so, after 24 hours was important in all but a few of 18 interchangeable glass syringes. Therefore unless analysis can be started immediately all-glass syringes are to be preferred, and for prolonged storage even these should be selected. PMID:5565518

  5. Protective coating and hyperthermal atomic oxygen texturing of optical fibers used for blood glucose monitoring

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A. (Inventor)

    2008-01-01

    Disclosed is a method of producing cones and pillars on polymethylmethacralate (PMMA) optical fibers for glucose monitoring. The method, in one embodiment, consists of using electron beam evaporation to deposit a non-contiguous thin film of aluminum on the distal ends of the PMMA fibers. The partial coverage of aluminum on the fibers is randomly, but rather uniformly distributed across the end of the optical fibers. After the aluminum deposition, the ends of the fibers are then exposed to hyperthermal atomic oxygen, which oxidizes the areas that are not protected by aluminum. The resulting PMMA fibers have a greatly increased surface area and the cones or pillars are sufficiently close together that the cellular components in blood are excluded from passing into the valleys between the cones and pillars. The optical fibers are then coated with appropriated surface chemistry so that they can optically sense the glucose level in the blood sample than that with conventional glucose monitoring.

  6. Direct imaging of singlet oxygen luminescence generated in blood vessels during photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Lin, Lisheng; Lin, Huiyun; Chen, Defu; Chen, Longchao; Wang, Min; Xie, Shusen; Gu, Ying; Wilson, Brian C.; Li, Buhong

    2014-05-01

    Singlet oxygen (1O2) is commonly recognized to be a major phototoxic component for inducing the biological damage during photodynamic therapy (PDT). In this study, a novel configuration of a thermoelectrically-cooled near-infrared sensitive InGaAs camera was developed for imaging of photodynamically-generated 1O2 luminescence. The validation of 1O2 luminescence images for solution samples was performed with the model photosensitizer Rose Bengal (RB). Images of 1O2 luminescence generated in blood vessels in vivo in a well-controlled dorsal skinfold window chamber model were also recorded during PDT. This study demonstrated the capacity of the newly-developed imaging system for imaging of 1O2 luminescence, and the first reported images of 1O2 luminescence in blood vessels in vivo. This system has potential for elucidating the mechanisms of vascular targeted PDT.

  7. Energetic Atomic and Ionic Oxygen Textured Optical Surfaces for Blood Glucose Monitoring

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A. (Inventor)

    2007-01-01

    Disclosed is a method and the resulting product thereof comprising a solid light-conducting fiber with a point of attachment and having a textured surface site consisting of a textured distal end prepared by being placed in a vacuum and then subjected to directed hyperthermal beams comprising oxygen ions or atoms. The textured distal end comprises cones or pillars that are spaced upon from each other by less than 1 micron and are extremely suitable to prevent cellular components of blood from entering the valleys between the cones or pillars so as to effectively separate the cellular components in the blood from interfering with optical sensing of the glucose concentration for diabetic patients.

  8. Diving Related Changes in the Blood Oxygen Stores of Rehabilitating Harbor Seal Pups (Phoca vitulina).

    PubMed

    Thomas, Amber; Ono, Kathryn

    2015-01-01

    Harbor seal (Phoca vitulina) pups begin diving within hours of birth, stimulating the development of the blood oxygen (O2) stores necessary to sustain underwater aerobic metabolism. Since harbor seals experience a brief nursing period, the early-life development of these blood O2 stores is necessary for successful post-weaning foraging. If mothers and pups become prematurely separated, the pup may be transported to a wildlife rehabilitation center for care. Previous studies suggest that the shallow pools and lack of diving in rehabilitation facilities may lead to under-developed blood O2 stores, but diving behavior during rehabilitation has not been investigated. This study aimed to simultaneously study the diving behaviors and blood O2 store development of rehabilitating harbor seal pups. Standard hematology measurements (Hct, Hb, RBC, MCV, MCH, MCHC) were taken to investigate O2 storage capacity and pups were equipped with time-depth recorders to investigate natural diving behavior while in rehabilitation. Linear mixed models of the data indicate that all measured blood parameters changed with age; however, when compared to literature values for wild harbor seal pups, rehabilitating pups have smaller red blood cells (RBCs) that can store less hemoglobin (Hb) and subsequently, less O2, potentially limiting their diving capabilities. Wild pups completed longer dives at younger ages (maximum reported <25 days of age: 9 min) in previous studies than the captive pups in this study (maximum <25 days of age: 2.86 min). However, captivity may only affect the rate of development, as long duration dives were observed (maximum during rehabilitation: 13.6 min at 89 days of age). Further, this study suggests that there may be a positive relationship between RBC size and the frequency of long duration dives. Thus, rehabilitating harbor seal pups should be encouraged to make frequent, long duration dives to prepare themselves for post-release foraging. PMID:26061662

  9. Diving Related Changes in the Blood Oxygen Stores of Rehabilitating Harbor Seal Pups (Phoca vitulina)

    PubMed Central

    Thomas, Amber; Ono, Kathryn

    2015-01-01

    Harbor seal (Phoca vitulina) pups begin diving within hours of birth, stimulating the development of the blood oxygen (O2) stores necessary to sustain underwater aerobic metabolism. Since harbor seals experience a brief nursing period, the early-life development of these blood O2 stores is necessary for successful post-weaning foraging. If mothers and pups become prematurely separated, the pup may be transported to a wildlife rehabilitation center for care. Previous studies suggest that the shallow pools and lack of diving in rehabilitation facilities may lead to under-developed blood O2 stores, but diving behavior during rehabilitation has not been investigated. This study aimed to simultaneously study the diving behaviors and blood O2 store development of rehabilitating harbor seal pups. Standard hematology measurements (Hct, Hb, RBC, MCV, MCH, MCHC) were taken to investigate O2 storage capacity and pups were equipped with time-depth recorders to investigate natural diving behavior while in rehabilitation. Linear mixed models of the data indicate that all measured blood parameters changed with age; however, when compared to literature values for wild harbor seal pups, rehabilitating pups have smaller red blood cells (RBCs) that can store less hemoglobin (Hb) and subsequently, less O2, potentially limiting their diving capabilities. Wild pups completed longer dives at younger ages (maximum reported <25 days of age: 9 min) in previous studies than the captive pups in this study (maximum <25 days of age: 2.86 min). However, captivity may only affect the rate of development, as long duration dives were observed (maximum during rehabilitation: 13.6 min at 89 days of age). Further, this study suggests that there may be a positive relationship between RBC size and the frequency of long duration dives. Thus, rehabilitating harbor seal pups should be encouraged to make frequent, long duration dives to prepare themselves for post-release foraging. PMID:26061662

  10. A New Biomarkers Feature Pattern Consisting of TNF- α , IL-10, and IL-8 for Blood Stasis Syndrome with Myocardial Ischemia.

    PubMed

    Guo, Shuzhen; Chen, Jianxin; Chuo, Wenjing; Liu, Lei; Feng, Xuanchao; Lian, Hongjian; Zheng, Lei; Wang, Yong; Xie, Hua; Luo, Liangtao; Zheng, Chenglong; Fu, Bangze; Wang, Wei

    2013-01-01

    Objective. To explore new diagnostic patterns for syndromes to overcome the insufficiency of obtainable macrocharacteristics and specific biomarkers. Methods. Chinese miniswines were subjected to Ameroid constrictor, placed around the proximal left anterior descending branch. On the 4th week, macrocharacteristics, coronary angiography, echocardiography, and hemorheology indices were detected for diagnosis. IL-1, IL-6, IL-8, IL-10, TNF- α , and hsCRP in serum were detected, and Decision Tree was built. Results. According to current official-issued standard, model animals matched the diagnosis of blood stasis syndrome with myocardial ischemia based on findings, including >90% occlusion, attenuated left ventricular segmental motion, dark red or purple tongues, and higher blood viscosity. Significant decrease of IL-10 and increase of TNF- α were found in model animals. However, in the Decision Tree, besides IL-10 and TNF- α , IL-8 helped to increase the accuracy of classification to 86%. Conclusions. The Decision Tree building with TNF- α , IL-10, and IL-8 is helpful for the diagnosis of blood stasis syndrome in myocardial ischemia animals. What is more is that our data set up a new path to the differentiation of syndrome by feature patterns consisting of multiple biomarkers not only for animals but also for patients. We believe that it will contribute to the standardization and international application of syndromes. PMID:24371451

  11. A New Biomarkers Feature Pattern Consisting of TNF-α, IL-10, and IL-8 for Blood Stasis Syndrome with Myocardial Ischemia

    PubMed Central

    Chen, Jianxin; Chuo, Wenjing; Liu, Lei; Lian, Hongjian; Zheng, Lei; Wang, Yong; Xie, Hua; Luo, Liangtao; Zheng, Chenglong; Fu, Bangze; Wang, Wei

    2013-01-01

    Objective. To explore new diagnostic patterns for syndromes to overcome the insufficiency of obtainable macrocharacteristics and specific biomarkers. Methods. Chinese miniswines were subjected to Ameroid constrictor, placed around the proximal left anterior descending branch. On the 4th week, macrocharacteristics, coronary angiography, echocardiography, and hemorheology indices were detected for diagnosis. IL-1, IL-6, IL-8, IL-10, TNF-α, and hsCRP in serum were detected, and Decision Tree was built. Results. According to current official-issued standard, model animals matched the diagnosis of blood stasis syndrome with myocardial ischemia based on findings, including >90% occlusion, attenuated left ventricular segmental motion, dark red or purple tongues, and higher blood viscosity. Significant decrease of IL-10 and increase of TNF-α were found in model animals. However, in the Decision Tree, besides IL-10 and TNF-α, IL-8 helped to increase the accuracy of classification to 86%. Conclusions. The Decision Tree building with TNF-α, IL-10, and IL-8 is helpful for the diagnosis of blood stasis syndrome in myocardial ischemia animals. What is more is that our data set up a new path to the differentiation of syndrome by feature patterns consisting of multiple biomarkers not only for animals but also for patients. We believe that it will contribute to the standardization and international application of syndromes. PMID:24371451

  12. Role of Endothelial Cells in Myocardial Ischemia-Reperfusion Injury

    PubMed Central

    Singhal, Arun K.; Symons, J. David; Boudina, Sihem; Jaishy, Bharat; Shiu, Yan-Ting

    2014-01-01

    Minimizing myocardial ischemia-reperfusion injury has broad clinical implications and is a critical mediator of cardiac surgical outcomes. “Ischemic injury” results from a restriction in blood supply leading to a mismatch between oxygen supply and demand of a sufficient intensity and/or duration that leads to cell necrosis, whereas ischemia-reperfusion injury occurs when blood supply is restored after a period of ischemia and is usually associated with apoptosis (i.e. programmed cell death). Compared to vascular endothelial cells, cardiac myocytes are more sensitive to ischemic injury and have received the most attention in preventing myocardial ischemia-reperfusion injury. Many comprehensive reviews exist on various aspects of myocardial ischemia-reperfusion injury. The purpose of this review is to examine the role of vascular endothelial cells in myocardial ischemia-reperfusion injury, and to stimulate further research in this exciting and clinically relevant area. Two specific areas that are addressed include: 1) data suggesting that coronary endothelial cells are critical mediators of myocardial dysfunction after ischemia-reperfusion injury; and 2) the involvement of the mitochondrial permeability transition pore in endothelial cell death as a result of an ischemia-reperfusion insult. Elucidating the cellular signaling pathway(s) that leads to endothelial cell injury and/or death in response to ischemia-reperfusion is a key component to developing clinically applicable strategies that might minimize myocardial ischemia-reperfusion injury. PMID:25558187

  13. Long-term intake of edible oils benefits blood pressure and myocardial structure in spontaneously hypertensive rat (SHR) and streptozotocin diabetic SHR.

    PubMed

    Medeiros, Fernanda Jurema; Mothé, Cheila Gonçalves; Aguila, Márcia Barbosa; Mandarim-de-Lacerda, Carlos Alberto

    2005-12-01

    The beneficial effects of edible oils long-term supplementation in blood pressure (BP) and cardiac structure were investigated in spontaneously hypertensive rat (SHR) and streptozotocin diabetic (Db) SHR (45 mg/rat i.p.). Twenty-five 12-week old male SHR were divided into four SHR-Db groups and one SHR group, SHR-Db groups each receiving, respectively, olive oil, palm oil and fish oil, and another SHR-Db group with placebo by gavage on a daily basis for 6 weeks. Myocardial structures were analyzed through light microscopy and stereology. In SHR-Db, the BP and the myocardium were significantly altered by oil supplementation. The BP, the interstitial fibrosis and cardiomyocyte size showed a significant decrease in treated SHR-Db than in SHR or untreated SHR-Db. The myocardial microvasculature and number of cardiomyocytes were higher in all treated groups, especially in fish oil group. Long-term edible oil supplementation showed beneficial effects decreasing BP levels and offsetting adverse myocardial remodeling in diabetic SHR. PMID:16303619

  14. Widefield in vivo spectral and fluorescence imaging microscopy of microvessel blood supply and oxygenation

    NASA Astrophysics Data System (ADS)

    Lee, Jennifer; Kozikowski, Raymond; Wankhede, Mamta; Sorg, Brian S.

    2011-02-01

    Abnormal microvascular function and angiogenesis are key components of various diseases that can contribute to the perpetuation of the disease. Several skin diseases and ophthalmic pathologies are characterized by hypervascularity, and in cancer the microvasculature of tumors is structurally and functionally abnormal. Thus, the microvasculature can be an important target for treatment of diseases characterized by abnormal microvasculature. Motivated largely by cancer research, significant effort has been devoted to research on drugs that target the microvasculature. Several vascular targeting drugs for cancer therapy are in clinical trials and approved for clinical use, and several off-label uses of these drugs have been reported for non-cancer diseases. The ability to image and measure parameters related to microvessel function preclinically in laboratory animals can be useful for development and comparison of vascular targeting drugs. For example, blood supply time measurements give information related to microvessel morphology and can be measured with first-pass fluorescence imaging. Hemoglobin saturation measurements give an indication of microvessel oxygen transport and can be measured with spectral imaging. While each measurement individually gives some information regarding microvessel function, the measurements together may yield even more information since theoretically microvessel morphology can influence microvessel oxygenation, especially in metabolically active tissue like tumors. However, these measurements have not yet been combined. In this study, we report the combination of blood supply time imaging and hemoglobin saturation imaging of microvessel networks in tumors using widefield fluorescence and spectral imaging, respectively. The correlation between the measurements in a mouse mammary tumor is analyzed.

  15. Reduction in Cerebral Oxygenation After Prolonged Exercise in Hypoxia is Related to Changes in Blood Pressure.

    PubMed

    Horiuchi, Masahiro; Dobashi, Shohei; Kiuchi, Masataka; Endo, Junko; Koyama, Katsuhiro; Subudhi, Andrew W

    2016-01-01

    We investigated the relation between blood pressure and cerebral oxygenation (COX) immediately after exercise in ten healthy males. Subjects completed an exercise and recovery protocol while breathing either 21% (normoxia) or 14.1% (hypoxia) O2 in a randomized order. Each exercise session included four sets of cycling (30 min/set, 15 min rest) at 50% of altitude-adjusted peak oxygen uptake, followed by 60 min of recovery. After exercise, mean arterial pressure (MAP; 87±1 vs. 84±1 mmHg, average values across the recovery period) and COX (68±1% vs. 58±1%) were lower in hypoxia compared to normoxia (P<0.001). Changes in MAP and COX were correlated during the recovery period in hypoxia (r=0.568, P<0.001) but not during normoxia (r=0.028, not significant). These results demonstrate that reductions in blood pressure following exercise in hypoxia are (1) more pronounced than in normoxia, and (2) associated with reductions in COX. Together, these results suggest an impairment in cerebral autoregulation as COX followed changes in MAP more passively in hypoxia than in normoxia. These findings could help explain the increased risk for postexercise syncope at high altitude. PMID:26782200

  16. Effects of diving and oxygen on autonomic nervous system and cerebral blood flow.

    PubMed

    Winklewski, Pawel J; Kot, Jacek; Frydrychowski, Andrzej F; Nuckowska, Magdalena K; Tkachenko, Yurii

    2013-09-01

    Recreational scuba diving is a popular leisure activity with the number of divers reaching several millions worldwide. Scuba diving represents a huge challenge for integrative physiology. In mammalian evolution, physiological reflexes developed to deal with lack of oxygen, rather than with an excess, which makes adaptations to scuba diving more difficult to describe and understand than those associated with breath-hold diving. The underwater environment significantly limits the use of equipment to register the organism's functions, so, in most instances, scientific theories are built on experiments that model real diving to some extent, like hyperbaric exposures, dive reflexes or water immersion. The aim of this review is to summarise the current knowledge related to the influence exerted by physiological conditions specific to diving on the autonomic nervous system and cerebral blood flow. The main factors regulating cerebral blood flow during scuba diving are discussed as follows: 1) increased oxygen partial pressure; 2) immersion-related trigemino-cardiac reflexes and 3) exposure to cold, exercise and stress. Also discussed are the potential mechanisms associated with immersion pulmonary oedema. PMID:24122190

  17. Oximeter for reliable clinical determination of blood oxygen saturation in a fetus

    DOEpatents

    Robinson, Mark R.; Haaland, David M.; Ward, Kenneth J.

    1996-01-01

    With the crude instrumentation now in use to continuously monitor the status of the fetus at delivery, the obstetrician and labor room staff not only over-recognize the possibility of fetal distress with the resultant rise in operative deliveries, but at times do not identify fetal distress which may result in preventable fetal neurological harm. The invention, which addresses these two basic problems, comprises a method and apparatus for non-invasive determination of blood oxygen saturation in the fetus. The apparatus includes a multiple frequency light source which is coupled to an optical fiber. The output of the fiber is used to illuminate blood containing tissue of the fetus. In the preferred embodiment, the reflected light is transmitted back to the apparatus where the light intensities are simultaneously detected at multiple frequencies. The resulting spectrum is then analyzed for determination of oxygen saturation. The analysis method uses multivariate calibration techniques that compensate for nonlinear spectral response, model interfering spectral responses and detect outlier data with high sensitivity.

  18. Regional brain blood flow and cerebral hemispheric oxygen consumption during acute hypoxaemia in the llama fetus

    PubMed Central

    Llanos, Aníbal J; Riquelme, Raquel A; Sanhueza, Emilia M; Herrera, Emilio; Cabello, Gertrudis; Giussani, Dino A; Parer, Julian T

    2002-01-01

    Unlike fetal animals of lowland species, the llama fetus does not increase its cerebral blood flow during an episode of acute hypoxaemia. This study tested the hypothesis that the fetal llama brain maintains cerebral hemispheric O2 consumption by increasing cerebral O2 extraction rather than decreasing cerebral oxygen utilisation during acute hypoxaemia. Six llama fetuses were surgically instrumented under general anaesthesia at 217 days of gestation (term ca 350 days) with vascular and amniotic catheters in order to carry out cardiorespiratory studies. Following a control period of 1 h, the llama fetuses underwent 3 × 20 min episodes of progressive hypoxaemia, induced by maternal inhalational hypoxia. During basal conditions and during each of the 20 min of hypoxaemia, fetal cerebral blood flow was measured with radioactive microspheres, cerebral oxygen extraction was calculated, and fetal cerebral hemispheric O2 consumption was determined by the modified Fick principle. During hypoxaemia, fetal arterial O2 tension and fetal pH decreased progressively from 24 ± 1 to 20 ± 1 Torr and from 7.36 ± 0.01 to 7.33 ± 0.01, respectively, during the first 20 min episode, to 16 ± 1 Torr and 7.25 ± 0.05 during the second 20 min episode and to 14 ± 1 Torr and 7.21 ± 0.04 during the final 20 min episode. Fetal arterial partial pressure of CO2 (Pa,CO2, 42 ± 2 Torr) remained unaltered from baseline throughout the experiment. Fetal cerebral hemispheric blood flow and cerebral hemispheric oxygen extraction were unaltered from baseline during progressive hypoxaemia. In contrast, a progressive fall in fetal cerebral hemispheric oxygen consumption occurred during the hypoxaemic challenge. In conclusion, these data do not support the hypothesis that the fetal llama brain maintains cerebral hemispheric O2 consumption by increasing cerebral hemispheric O2 extraction. Rather, the data show that in the llama fetus, a reduction in cerebral hemispheric metabolism occurs during acute

  19. Effects of cardiopulmonary bypass on gut blood flow, oxygen utilization, and intramucosal pH.

    PubMed

    Ohri, S K; Becket, J; Brannan, J; Keogh, B E; Taylor, K M

    1994-05-01

    Studies documenting rises in endotoxin after cardiopulmonary bypass (CPB) have postulated gut mucosal hypoperfusion. We have investigated alterations in jejunal blood flow by laser Doppler flow measurement, intramucosal pH (pHi) by tonometry, and oxygen utilization in a canine model of hypothermic CPB (n = 11 dogs). After 10 minutes of hypothermic CPB, despite no major reduction in superior mesenteric artery flow, mucosal laser Doppler flow decreased to -38.2% +/- 9.3% of levels obtained before bypass (p = 0.008) and serosal laser Doppler flow, to -47.3% +/- 11.4% (p = 0.006). During the hypothermic phase, mesenteric oxygen consumption fell from 0.18 +/- 0.01 to 0.098 +/- 0.01 mL.min-1.kg-1 (p = 0.005), and mesenteric oxygen delivery fell from 1.97 +/- 0.39 to 1.14 +/- 0.12 mL.min-1.kg-1 (p = 0.05). There was no change in jejunal pHi. During the rewarming phase, there was a substantial increase in mucosal laser Doppler flow, peaking at +69.8% +/- 15.2% (p = 0.03), whereas serosal laser Doppler flow returned to values seen prior to CPB (-16.4% +/- 21.5%; p = 0.25). These changes coincided with a surge in oxygen consumption (0.33 +/- 0.042 mL.min-1.kg-1; p = 0.009), while mesenteric oxygen delivery remained depressed at 1.09 +/- 0.12 mL.min-1.kg-1 (p = 0.04). Jejunal pHi fell from a value of 7.36 +/- 0.04 before CPB to 7.12 +/- 0.07 (p = 0.02), thus indicating mucosal hypoxia. During the rewarming phase of hypothermic CPB, there is a disparity between mesenteric oxygen consumption and oxygen delivery with villus tip ischemia; these findings may explain the pathophysiology of endotoxemia during CPB. PMID:8179384

  20. Tissue gas and blood analyses of human subjects breathing 80% argon and 20% oxygen

    NASA Technical Reports Server (NTRS)

    Horrigan, D. J.; Wells, C. H.; Guest, M. M.; Hart, G. B.; Goodpasture, J. E.

    1979-01-01

    Eight human volunteers, individually studied in a hyperbaric chamber, breathed: (1) air at 1 ATA; (2) 80% argon and 20% oxygen at 1 ATA for 30 min; (3) air at 1 ATA for 30 min; (4) 100% O2 at 1 ATA for 30 min; (5) air at 1 ATA for 30 min; (6) 100% O2 at 2 ATA for 60 min; and (7) 80% argon and 20% oxygen at 1 ATA for 30 min. Oxygen, carbon dioxide, nitrogen, and argon tensions were measured in muscle and subcutaneous tissue by mass spectroscopic analyses. Venous blood obtained at regular intervals was analyzed for coagulation and fibrinolytic factors. Inert gas narcosis was not observed. After breathing argon for 30 min, muscle argon tensions were almost three times the subcutaneous tensions. Argon wash-in mirrored nitrogen wash-out. Argon wash-in and wash-out had no effect on tissue PO2 or PCO2. Coagulation and fibrinolytic changes usually associated with vascular bubbles were absent.

  1. Effect of wavelength selection on the accuracy of blood oxygen saturation estimates obtained from photoacoustic images

    NASA Astrophysics Data System (ADS)

    Hochuli, Roman; Beard, Paul C.; Cox, Ben

    2015-03-01

    In photoacoustic tomography (PAT) the image contrast is due to optical absorption, and because of this PAT images are sensitive to changes in blood oxygen saturation (sO2). However, this is not a linear relationship due to the presence of a non-uniform light fluence distribution. In this paper we systematically evaluate the conditions in which an approximate linear inversion scheme-which assumes the internal fluence distribution is unchanged when the absorption coefficient changes-can give accurate estimates of sO2. A numerical phantom of highly vascularised tissue is used to test this assumption. It is shown that using multiple wavelengths over a broad range of the near-infrared spectrum yields inaccurate estimates of oxygenation, while a careful selection of wavelengths in the 620-920nm range is likely to yield more accurate oxygenation values. We demonstrate that a 1D fluence correction obtained by fitting a linear function to the average decay rate in the image can further improve the estimates. However, opting to use these longer wavelengths involves sacrificing signal-to-noise ratio in the image, as the absorption of blood is low in this range. This results in an inherent trade-off between error in the sO2 estimates due to fluence variation and error due to noise. This study shows that the depth to which sO2 can be estimated accurately using a linear approximation is limited in vivo, even with idealised measurements, to at most 3mm. In practice, there will be even greater uncertainties affecting the estimates, e.g., due to bandlimited or partial-view acoustic detection.

  2. Blood flow mechanics and oxygen transport and delivery in the retinal microcirculation: multiscale mathematical modeling and numerical simulation.

    PubMed

    Causin, Paola; Guidoboni, Giovanna; Malgaroli, Francesca; Sacco, Riccardo; Harris, Alon

    2016-06-01

    The scientific community continues to accrue evidence that blood flow alterations and ischemic conditions in the retina play an important role in the pathogenesis of ocular diseases. Many factors influence retinal hemodynamics and tissue oxygenation, including blood pressure, blood rheology, oxygen arterial permeability and tissue metabolic demand. Since the influence of these factors on the retinal circulation is difficult to isolate in vivo, we propose here a novel mathematical and computational model describing the coupling between blood flow mechanics and oxygen ([Formula: see text]) transport in the retina. Albeit in a simplified manner, the model accounts for the three-dimensional anatomical structure of the retina, consisting in a layered tissue nourished by an arteriolar/venular network laying on the surface proximal to the vitreous. Capillary plexi, originating from terminal arterioles and converging into smaller venules, are embedded in two distinct tissue layers. Arteriolar and venular networks are represented by fractal trees, whereas capillary plexi are represented using a simplified lumped description. In the model, [Formula: see text] is transported along the vasculature and delivered to the tissue at a rate that depends on the metabolic demand of the various tissue layers. First, the model is validated against available experimental results to identify baseline conditions. Then, a sensitivity analysis is performed to quantify the influence of blood pressure, blood rheology, oxygen arterial permeability and tissue oxygen demand on the [Formula: see text] distribution within the blood vessels and in the tissue. This analysis shows that: (1) systemic arterial blood pressure has a strong influence on the [Formula: see text] profiles in both blood and tissue; (2) plasma viscosity and metabolic consumption rates have a strong influence on the [Formula: see text] tension at the level of the retinal ganglion cells; and (3) arterial [Formula: see text

  3. Pore-Scale Modeling of Non-Newtonian Shear-Thinning Fluids in Blood Oxygenator Design.

    PubMed

    Low, Kenny W Q; van Loon, Raoul; Rolland, Samuel A; Sienz, Johann

    2016-05-01

    This paper reviews and further develops pore-scale computational flow modeling techniques used for creeping flow through orthotropic fiber bundles used in blood oxygenators. Porous model significantly reduces geometrical complexity by taking a homogenization approach to model the fiber bundles. This significantly simplifies meshing and can avoid large time-consuming simulations. Analytical relationships between permeability and porosity exist for Newtonian flow through regular arrangements of fibers and are commonly used in macroscale porous models by introducing a Darcy viscous term in the flow momentum equations. To this extent, verification of analytical Newtonian permeability-porosity relationships has been conducted for parallel and transverse flow through square and staggered arrangements of fibers. Similar procedures are then used to determine the permeability-porosity relationship for non-Newtonian blood. The results demonstrate that modeling non-Newtonian shear-thinning fluids in porous media can be performed via a generalized Darcy equation with a porous medium viscosity decomposed into a constant term and a directional expression through least squares fitting. This concept is then investigated for various non-Newtonian blood viscosity models. The proposed methodology is conducted with two different porous model approaches, homogeneous and heterogeneous, and validated against a high-fidelity model. The results of the heterogeneous porous model approach yield improved pressure and velocity distribution which highlights the importance of wall effects. PMID:26902524

  4. A novel method to estimate oxygen saturation of the internal jugular vein blood

    NASA Astrophysics Data System (ADS)

    Li, Kai; Pan, Boan; Gao, Yuan; Ruan, Zhengshang; Li, Ting

    2016-03-01

    This article introduces a novel method to estimate oxygen saturation of the internal jugular vein blood (SjvO2) by using Near Infrared spectroscopy (NIRS). The different positions of patients can affect the cross-sectional area (CSA) of the internal jugular vein (IJV), in other words, it causes the sectional change of the IJV blood volume. When lying position of patients, the CSA is larger than that keeping upper body 80 degree, and the CSA can compute quantitatively by the use of ultrasound and digital image processing methods. The entire method consist of constructing different position of patient (upper body rotation 0 and 80 degree), comparing the light absorption changes. SjvO2 has been determined from light absorption measurements in two wavelength, before and after the position changes. The method has been applied to the vertical area over the IJV of 11 patients who were placed a central venous catheter into a large vein in the neck for medical uses, using wavelength of 735 and 850 nm. At last, comparing the SjvO2NIRS which measured by NIRS noninvasively with SjvO2IJVBG which was quantified using a whole blood gas analyzer, we found there were some certain relativity. The results were influenced by vascular depth greatly.

  5. Photoacoustic Imaging of Vascular Hemodynamics: Validation with Blood Oxygenation Level–Dependent MR Imaging

    PubMed Central

    Rich, Laurie J.

    2015-01-01

    Purpose To noninvasively assess vascular hemodynamics with photoacoustic imaging (PAI) and blood oxygenation level–dependent (BOLD) magnetic resonance (MR) imaging in phantoms and in an animal model. Materials and Methods In vivo studies were performed with institutional animal care and use committee approval. In vitro experiments were performed by using a tissue-mimicking phantom in multiple oxygenation conditions (n = 6) to compare PAI measurements and BOLD MR imaging measurements. PAI and T2-weighted spin-echo–based BOLD MR imaging were performed to assess tumor response to carbogen (95% O2, 5% CO2) in mice with head and neck tumors before (n = 11) and after (n = 9) treatment with a vascular disrupting agent (VDA). Two-tailed Pearson correlation analysis was performed to determine the correlation between the parameters measured with PAI and BOLD MR imaging in vitro. Two-tailed paired t tests were used to compare change in tumor hemoglobin oxygen saturation (sO2) levels and BOLD signal in response to carbogen. Changes in PAI and BOLD signal intensity before and after VDA treatment were analyzed for significance by using analysis of variance with repeated measures. Results Phantom measurements yielded good correlation between photoacoustically derived sO2 levels and BOLD signal intensity (r = 0.937, P = .005) and partial pressure of oxygen (r = 0.981, P = .005). In vivo hemodynamic response to carbogen was characterized by a significant increase in tumor sO2 levels (P = .003) and BOLD signal (P = .001). When compared with pretreatment estimates, treatment with VDA resulted in a significant reduction in the tumor hemodynamic response to carbogen at PAI (P = .030). Conclusion Carbogen-based functional imaging with PAI and BOLD MR imaging enables monitoring of early changes in tumor hemodynamics after vascular targeted therapy. © RSNA, 2014 Online supplemental material is available for this article. PMID:25423146

  6. Blood oxygen flux estimation with a combined photoacoustic and high-frequency ultrasound microscopy system: a phantom study

    NASA Astrophysics Data System (ADS)

    Jiang, Yan; Forbrich, Alex; Harrison, Tyler; Zemp, Roger J.

    2012-03-01

    The metabolic rate of oxygen consumption, an important indicator of tissue metabolism, can be expressed as the change of net blood oxygen flux into and out of a tissue region per 100 g of tissue. In this work, we propose a photoacoustic and Doppler ultrasound method for imaging local blood oxygen flux of a single vessel. An imaging system for combined photoacoustic and high-frequency ultrasound microscopy is presented. This system uses a swept-scan 25-MHz ultrasound transducer with confocal dark-field laser illumination optics. A pulse-sequencer enables ultrasonic and laser pulses to be interlaced so that photoacoustic and Doppler ultrasound images are co-registered. Since the mean flow speed can be measured by color Doppler ultrasound, the vessel cross-sectional area can be measured by power Doppler or structural photoacoustic imaging, and multi-wavelength photoacoustic methods can be used to estimate oxygen saturation (sO2) and total concentration of haemoglobin (CHb), all of the parameters necessary for oxygen flux estimation can be provided. The accuracy of the flow speed and sO2 estimation has been investigated. In vitro sheep blood phantom experiments have been performed at different sO2 levels and mean flow speeds. Blood oxygen flux has been estimated, and the uncertainty of the measurement has been quantified.

  7. [Blood flow patterns in the left ventricle in patients with myocardial infarction and ventricular aneurysm: evaluation using real-time two-dimensional Doppler echocardiography].

    PubMed

    Konishiike, A; Mihata, S; Matsumori, Y; Nishian, K; Ikeoka, K; Yasutomi, N; Tanimoto, M; Makihata, S; Yamamoto, T; Iwasaki, T

    1987-12-01

    To evaluate how the intraventricular blood flow is affected by the size of a left ventricular aneurysm and ventricular dysfunction, systolic left ventricular blood flow patterns were evaluated using two-dimensional Doppler flow images (real-time 2-D Doppler echo). The subjects consisted of 10 normal controls, 35 patients with anteroseptal infarction, two patients with inferior infarction and five patients with anteroseptal-inferior infarctions. The systolic period was divided into three subsets; early, mid- and end-systole. Forty-two patients with myocardial infarction were classified into three groups according to the left ventricular inflow patterns on real-time 2-D Doppler echo using the apical left ventricular long-axis approach; i.e., inflow signals confined to early systole (Group I), visualized up to mid-systole (Group II) and end-systole (Group III). Left ventricular end-diastolic dimension (LVDd), left ventricular end-systolic dimension (LVDs), and % non-contractile circumference (delta L) were calculated by the same echocardiographic approach. Ejection fraction (EF) was calculated by left ventricular cineangiography using the Simpson's method. The left ventricular inflow Doppler signals in the normal controls and Group I turned in the apex and then directed toward the left ventricular outflow tract during late diastole and early systole. Significant differences in EF were observed among the three groups. EF in Group I, II and III was 53 +/- 9%, 41 +/- 8% and 29 +/- 7%, respectively. However, LVDd, LVDs and delta L had the largest values in Group III and the smallest values in Group I. LVDd, LVDs and delta L were smallest in Group I and largest in Group III. In the normal controls, the left ventricular inflow signals proceeded to the apex and directed toward the left ventricular outflow tract in the early systolic period. Various changes in the inflow pattern were observed in patients with myocardial infarction and severe wall motion abnormalities

  8. Ultra-acute increase in blood glucose during prehospital phase is associated with worse short-term and long-term survival in ST-elevation myocardial infarction

    PubMed Central

    2014-01-01

    Background The current study was to investigate the blood glucose changes in ultra-acute phase in patients with ST-elevation myocardial infarction (STEMI) and its associations with patient outcome. Methods This study was a retrospective population-based observational study utilizing prospectively collected registry data complemented with laboratory data. All adult patients with STEMI treated by emergency medical services (EMS) in the city of Helsinki from January 2006 to December 2010 were included in the study. Both prehospital and hospital admission glucose values were available from 152 (32%) of all STEMI patients (n = 469). Results Change in blood glucose from prehospital phase to emergency department admission was significantly higher in non-survivors within 30 days compared to survivors (+1.2 ± 5.1 vs. -0.3 ± 2.4 mmol/l [mean ± SD], P = 0.03). Furthermore, the 3-year survival rate was significantly lower in patients with an evident (≥2 mmol/l) rise in blood glucose (P = 0.02). In patients with impaired left ventricle function (best ejection fraction < 40%), blood glucose increased more compared to patients without it (1.2 ± 2.9 vs. 0.4 ± 2.7 mmol/l, P = 0.01). Increase in glucose was correlated with peak myocardial creatinine kinase (r = 0.17, P = 0.04) as a marker of increased size of infarct, but not with glycosylated haemoglobin A1C as a marker of chronic hyperglycaemia (r = −0.12, P = 0.27). Conclusions In patients with STEMI, ultra-acute hyperglycaemia during prehospital phase is associated with increased mortality, impaired cardiac function and increased size of infarct. PMID:24886984

  9. Red blood cell transfusion increases cerebral oxygen delivery in anemic patients with subarachnoid hemorrhage

    PubMed Central

    Dhar, Rajat; Zazulia, Allyson R; Videen, Tom O; Zipfel, Gregory J; Derdeyn, Colin P; Diringer, Michael N

    2009-01-01

    Background Anemia is common after subarachnoid hemorrhage (SAH) and may exacerbate the reduction in oxygen delivery (DO2) underlying delayed cerebral ischemia (DCI). The association between lower hemoglobin and worse outcome, including more cerebral infarcts, supports a role for red blood cell (RBC) transfusion to correct anemia. However, the cerebral response to transfusion remains uncertain, as higher hemoglobin may increase viscosity and further impair cerebral blood flow (CBF) in the setting of vasospasm. Methods Eight patients with aneurysmal SAH and hemoglobin < 10 g/dl were studied with 15O-PET before and after transfusion of 1 unit of RBCs. Paired t-tests were used to analyze the change in global and regional CBF, oxygen extraction fraction (OEF), and oxygen metabolism (CMRO2) after transfusion. DO2 was calculated from CBF and arterial oxygen content (CaO2). CBF, CMRO2 and DO2 are reported in ml/100g/min. Results Transfusion resulted in a 15% rise in hemoglobin (8.7±0.8 to 10.0±1.0 g/dl) and CaO2 (11.8±1.0 to 13.6±1.1 ml/dL, both p < 0.001). Global CBF remained stable (40.5±8.1 to 41.6±9.9), resulting in an 18% rise in DO2 from 4.8±1.1 to 5.7±1.4 (p = 0.017). This was associated with a fall in OEF from 0.49±0.11 to 0.41±0.11 (p = 0.11) and stable CMRO2. Rise in DO2 was greater (28%) in regions with oligemia (low DO2 and OEF≥0.5) at baseline, but was attenuated (10%) within territories exhibiting angiographic vasospasm, where CBF fell 7%. Conclusions Transfusion of RBCs to anemic patients with SAH resulted in a significant rise in cerebral DO2 without lowering global CBF. This was associated with reduced OEF, which may improve tolerance of vulnerable brain regions to further impairments of CBF. Further studies are needed to confirm the benefit of transfusion on DCI and balance this against potential systemic and cerebral risks. PMID:19628806

  10. The effect of prolonged perfusion with a membrane oxygenator (PPMO) on white blood cells.

    PubMed

    Bergman, P; Belboul, A; Friberg, L G; al-Khaja, N; Mellgren, G; Roberts, D

    1994-01-01

    Preserving the rheological properties of whole blood cells is vital for their smooth passage in the capillaries without causing blockage and disturbances in the microcirculation. To evaluate the effect of mechanical trauma on the rheology of white blood cells during prolonged perfusion with membrane oxygenation (PPMO), 16 in vitro experiments were conducted for 72 hours. The St George Carrimed Filtrometer was used to estimate the plasma white cell filtration rates (P-WFR). Also an in vitro estimation of the ability of individual cells to pass through capillaries, the white blood cell clogging rate (WBC-CR), the number of clogging particles (WBC-CP), the total white blood cell count (T-WBC) and two in vitro estimations to assess the effect of aggregates and stiff cells in blocking the microcirculation were performed. The traumatized white cells reduced their mean P-WFR by 37% +/- 9, 72% +/- 2 and 76% +/- 2 at 24, 48 and 72 hours respectively (p < 0.001). The mean WBC-CR was increased to 15.2 +/- 1.5, 32.6 +/- 2.2 and 40.3 +/- 8.3 x 10(2)%/ml at 24, 48 and 72 hours respectively (p < 0.001). The mean WBC-CP was increased to 6.6 +/- 1.5, 9.7 +/- 1.2 and 13.9 +/- 2.1 x 10(6)/ml at 24 hours (p < 0.05), 48 and 72 hours respectively (p < 0.001). The T-WBC was decreased to 55% +/- 0.3, 23% +/- 0.2 and 14% +/- 0.1 and 14% +/- 0.1 at 24, 48 and 72 hours respectively (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8161866

  11. Myocardial Infarction: Symptoms and Treatments.

    PubMed

    Lu, Lei; Liu, Min; Sun, RongRong; Zheng, Yi; Zhang, Peiying

    2015-07-01

    Myocardial infarction (MI) is a term used for an event of heart attack which is due to formation of plaques in the interior walls of the arteries resulting in reduced blood flow to the heart and injuring heart muscles because of lack of oxygen supply. The symptoms of MI include chest pain, which travels from left arm to neck, shortness of breath, sweating, nausea, vomiting, abnormal heart beating, anxiety, fatigue, weakness, stress, depression, and other factors. The immediate treatment of MI include, taking aspirin, which prevents blood from clotting, and nitro-glycerin to treat chest pain and oxygen. The heart attack can be prevented by taking an earlier action to lower those risks by controlling diet, fat, cholesterol, salt, smoking, nicotine, alcohol, drugs, monitoring of blood pressure every week, doing exercise every day, and loosing body weight. The treatment of MI includes, aspirin tablets, and to dissolve arterial blockage injection of thrombolytic or clot dissolving drugs such as tissue plasminogen activator, streptokinase or urokinase in blood within 3 h of the onset of a heart attack. The painkillers such as morphine or meperidine can be administered to relieve pain. Nitroglycerin and antihypertensive drugs such as beta-blockers, ACE inhibitors or calcium channel blockers may also be used to lower blood pressure and to improve the oxygen demand of heart. The ECG, coronary angiography and X-ray of heart and blood vessels can be performed to observe the narrowing of coronary arteries. In this article the causes, symptoms and treatments of MI are described. PMID:25638347

  12. Extraction of water labeled with oxygen 15 during single-capillary transit. Influence of blood pressure, osmolarity, and blood-brain barrier damage

    SciTech Connect

    Go, K.G.; Lammertsma, A.A.; Paans, A.M.; Vaalburg, W.; Woldring, M.G.

    1981-09-01

    By external detection, the influence of arterial blood pressure (BP), osmolarity, and cold-induced blood-brain barrier damage was assessed on the extraction of water labeled with oxygen 15 during single-capillary transit in the rat. There was an inverse relation between arterial BP and extraction that was attributable to the influence of arterial BP on cerebral blood flow (CBF) and the relation between CBF and extraction. Neither arterial BP nor osmolarity of the injected bolus had any direct effect on extraction of water 15O, signifying that the diffusional exchange component (determined by blood flow) of extraction greatly surpasses the convection flow contribution by hydrostatic or osmotic forces. Damage to the blood-brain barrier did not change its permeability to water.

  13. Design a Wearable Device for Blood Oxygen Concentration and Temporal Heart Beat Rate

    NASA Astrophysics Data System (ADS)

    Myint, Cho Zin; Barsoum, Nader; Ing, Wong Kiing

    2010-06-01

    The wireless network technology is increasingly important in healthcare as a result of the aging population and the tendency to acquire chronic disease such as heart attack, high blood pressure amongst the elderly. A wireless sensor network system that has the capability to monitor physiological sign such as SpO2 (Saturation of Arterial Oxygen) and heart beat rate in real-time from the human's body is highlighted in this study. This research is to design a prototype sensor network hardware, which consists of microcontroller PIC18F series and transceiver unit. The sensor is corporate into a wearable body sensor network which is small in size and easy to use. The sensor allows a non invasive, real time method to provide information regarding the health of the body. This enables a more efficient and economical means for managing the health care of the population.

  14. Highly Stable Operation of Metal Oxide Nanowire Transistors in Ambient Humidity, Water, Blood, and Oxygen.

    PubMed

    Lim, Taekyung; Bong, Jihye; Mills, Edmund M; Kim, Sangtae; Ju, Sanghyun

    2015-08-01

    The capability for robust operation of nanoscale transistors under harsh environments is equally important as their operating parameters such as high on-currents, high mobility, and high sensing selectivity. For electronic/biomedical applications, in particular, transistor operation must be stable under diverse conditions including ambient humidity, water, blood, and oxygen. Here we demonstrate the use of a self-assembled monolayer of octadecylphosphonic acid (OD-PA) to passivate a functionalized nanowire transistor, allowing the device to operate consistently in such environments. In contrast, without passivation, the characteristics (especially the threshold voltage) of identical nanowire transistors were dramatically altered under these conditions. Furthermore, the OD-PA-passivated transistor shows no signs of long-term stability deterioration and maintains equally high sensing selectivity to light under the harsh environments because of OD-PA's optical transparency. These results demonstrate the suitability of OD-PA passivation methods for fabricating commercial nanoelectronics. PMID:26200320

  15. Successful hyperbaric oxygen therapy for refractory BK virus-associated hemorrhagic cystitis after cord blood transplantation.

    PubMed

    Hosokawa, K; Yamazaki, H; Nakamura, T; Yoroidaka, T; Imi, T; Shima, Y; Ohata, K; Takamatsu, H; Kotani, T; Kondo, Y; Takami, A; Nakao, S

    2014-10-01

    BK virus-associated hemorrhagic cystitis (BKV-HC) is a common and major cause of morbidity in recipients of allogeneic hematopoietic stem cell transplantation. A 32-year-old woman developed severe BKV-HC on day 24 after cord blood transplantation (CBT). Despite supportive therapies - such as hyperhydration, forced diuresis, and urinary catheterization - macroscopic hematuria and bladder irritation persisted for over a month. Hyperbaric oxygen (HBO) therapy at 2.1 atmospheres for 90 min per day was started on day 64 after CBT. Macroscopic hematuria resolved within a week, and microscopic hematuria was no longer detectable within 2 weeks. Hematuria did not recur after 11 sessions of HBO therapy, and no significant side effects were observed during or after treatment. HBO therapy could thus be useful in controlling refractory BKV-HC after CBT. PMID:25040402

  16. The oxygen status algorithm: a computer program for calculating and displaying pH and blood gas data.

    PubMed

    Siggaard-Andersen, O; Siggaard-Andersen, M

    1990-01-01

    Input parameters for the program are the arterial pH, pCO2, and pO2 (measured by a blood gas analyzer), oxygen saturation, carboxy-, met-, and total hemoglobin (measured by a multi-wavelength spectrometer), supplemented by patient age, sex, temperature, inspired oxygen fraction, fraction of fetal hemoglobin, and ambient pressure. Output parameters are the inspired and alveolar oxygen partial pressures, pH,pCO2 and pO2 referring to the actual patient temperature, estimated shunt fraction, half-saturation tension, estimated 2,3-diphosphoglycerate concentration, oxygen content and oxygen capacity, extracellular base excess, and plasma bicarbonate concentration. Three parameters related to the blood oxygen availability are calculated: the oxygen extraction tension, concentration of extractable oxygen, and oxygen compensation factor. Calculations of the 'reverse' type may also be performed so that the effect of therapeutic measures on the oxygen status or the acid-base status can be predicted. The user may choose among several different units of measurement and two different conventions for symbols. The results are presented in a data display screen comprising all quantities together with age, sex, and temperature adjusted reference values. The program generates a 'laboratory diagnosis' of the oxygen status and the acid-base status and three graphs illustrating the oxygen status and the acid-base status of the patient: the oxygen graph, the acid-base chart and the blood gas map. A printed summary in one A4 page including a graphical display can be produced with an Epson or HP Laser compatible printer. The program is primarily intended for routine laboratories with a blood gas analyzer combined with a multi-wavelength spectrometer. Calculating the derived quantities may enhance the usefulness of the analyzers and improve patient care. The program may also be used as a teaching aid in acid-base and respiratory physiology. The program requires an IBM PC, XT, AT or similar

  17. Regulation of nitrite transport in red blood cells by hemoglobin oxygen fractional saturation.

    PubMed

    Vitturi, Dario A; Teng, Xinjun; Toledo, José C; Matalon, Sadis; Lancaster, Jack R; Patel, Rakesh P

    2009-05-01

    Allosteric regulation of nitrite reduction by deoxyhemoglobin has been proposed to mediate nitric oxide (NO) formation during hypoxia. Nitrite is predominantly an anion at physiological pH, raising questions about the mechanism by which it enters the red blood cell (RBC) and whether this is regulated and coupled to deoxyhemoglobin-mediated reduction. We tested the hypothesis that nitrite transport by RBCs is regulated by fractional saturation. Using human RBCs, nitrite consumption was faster at lower fractional saturations, consistent with faster reactions with deoxyheme. A membrane-based regulation was suggested by slower nitrite consumption with intact versus lysed RBCs. Interestingly, upon nitrite addition, intracellular nitrite concentrations attained a steady state that, despite increased rates of consumption, did not change with decreasing oxygen tensions, suggesting a deoxygenation-sensitive step that either increases nitrite import or decreases the rate of nitrite export. A role for anion exchanger (AE)-1 in the control of nitrite export was suggested by increased intracellular nitrite concentrations in RBCs treated with DIDS. Moreover, deoxygenation decreased steady-state levels of intracellular nitrite in AE-1-inhibited RBCs. Based on these data, we propose a model in which deoxyhemoglobin binding to AE-1 inhibits nitrite export under low oxygen tensions allowing for the coupling between deoxygenation and nitrite reduction to NO along the arterial-to-venous gradient. PMID:19286940

  18. Role of hemoglobin from blood clam Scapharca kagoshimensis beyond oxygen transport.

    PubMed

    Xu, Bin; Zhao, Jun; Jing, Zhao; Zhang, Yanan; Shi, Ying; Fan, Tingjun

    2015-05-01

    The evolutionary race between hosts and pathogens has led to a variety of adaptations. Little is known about the immunological role of hemoglobin (Hb) in antimicrobial immune responses. Results showed that a 31.2 kDa monodimer Hb (skHbI) and a 57.8 kDa heterotetramer Hb (skHbII) from the blood clam, Scapharca kagoshimensis, had phenoloxidase (PO)-like activities and antimicrobial activities. Both were found capable of oxidizing l-DOPA, catechol and hydroquinone. Their PO-like activities were visibly greatly inhibited by oxidase inhibitors, EDTA, and divalent metal ions, and greatly enhanced by isopropanol and Fe(2+), indicating that they have the properties of a metalloenzyme and a catecholase-type PO as well. They also showed obvious anti-bacterial activities against gram-positive bacteria but not against either gram-negative bacteria nor fungi. The anti-bacterial activities levels were a result of the generation of reactive oxygen species (ROS) of superoxide anions. These results indicate that skHbI and skHbII, not only function as iron-containing oxygen carriers, but also exert anti-bacterial activities and catecholase-type oxidizing activities. The fact that skHbII exerts high level of PO-like activity indicates different roles in the innate immunodefense system. These results may improve understanding of the multiple functions of invertebrate Hbs beyond serving as oxygen carriers and may provide insight into how the fundamental and universal mode of the innate immune system has persisted in respiratory proteins throughout the course of evolution. PMID:25700784

  19. Preparation, characterization and in vivo investigation of blood-compatible hemoglobin-loaded nanoparticles as oxygen carriers.

    PubMed

    Lu, Mingzi; Zhao, Caiyan; Wang, Quan; You, Guoxing; Wang, Ying; Deng, Hongzhang; Chen, Gan; Xia, Sha; Zhao, Jingxiang; Wang, Bo; Li, Xianlei; Shao, Leihou; Wu, Yan; Zhao, Lian; Zhou, Hong

    2016-03-01

    Although many attempts have been made to design advanced hemoglobin-based oxygen carriers (HBOCs), no clinically viable product has been widely approved, because they do not perform normal blood functions, such as coagulation, hematologic reactions and stability. Additionally, the in vivo oxygenation of hemoglobin-loaded nanoparticles (HbPs) encapsulated with polymers has seldom been proved. Herein, HbPs of approximately 200nm with good stability were successfully fabricated and exhibited oxygen-carrying capacity. The HbPs preserve the biological and structure features of hemoglobin according to UV-vis spectrophotometry, Fourier transform infrared (FTIR) spectroscopy and circular dichroism (CD) spectral analysis. In vitro, the HbPs showed a viscosity comparable to that of blood with no obvious effects on red blood cell aggregation. At the same time, blood compatibility was characterized in terms of platelet function, clot strength, speed of clot formation, degree of fibrin cross-linking and hemolysis rate. After intravenous administration of HbPs to mice with controlled hemorrhages, blood flow recovery and maintenance of systemic oxygenation were observed. PMID:26708138

  20. Ligation of Glycophorin A Generates Reactive Oxygen Species Leading to Decreased Red Blood Cell Function

    PubMed Central

    Khoory, Joseph; Estanislau, Jessica; Elkhal, Abdallah; Lazaar, Asmae; Melhorn, Mark I.; Brodsky, Abigail; Illigens, Ben; Hamachi, Itaru; Kurishita, Yasutaka; Ivanov, Alexander R.; Shevkoplyas, Sergey; Shapiro, Nathan I.; Ghiran, Ionita C.

    2016-01-01

    Acute, inflammatory conditions associated with dysregulated complement activation are characterized by significant increases in blood concentration of reactive oxygen species (ROS) and ATP. The mechanisms by which these molecules arise are not fully understood. In this study, using luminometric- and fluorescence-based methods, we show that ligation of glycophorin A (GPA) on human red blood cells (RBCs) results in a 2.1-fold, NADPH-oxidase-dependent increase in intracellular ROS that, in turn, trigger multiple downstream cascades leading to caspase-3 activation, ATP release, and increased band 3 phosphorylation. Functionally, using 2D microchannels to assess membrane deformability, GPS-ligated RBCs travel 33% slower than control RBCs, and lipid mobility was hindered by 10% using fluorescence recovery after photobleaching (FRAP). These outcomes were preventable by pretreating RBCs with cell-permeable ROS scavenger glutathione monoethyl ester (GSH-ME). Our results obtained in vitro using anti-GPA antibodies were validated using complement-altered RBCs isolated from control and septic patients. Our results suggest that during inflammatory conditions, circulating RBCs significantly contribute to capillary flow dysfunctions, and constitute an important but overlooked source of intravascular ROS and ATP, both critical mediators responsible for endothelial cell activation, microcirculation impairment, platelet activation, as well as long-term dysregulated adaptive and innate immune responses. PMID:26784696

  1. Effect of intermittent hypoxia and exercise on blood rheology and oxygen transport in trained rats.

    PubMed

    Núñez-Espinosa, Cristian; Douziech, Anne; Ríos-Kristjánsson, Juan Gabriel; Rizo, David; Torrella, Joan Ramon; Pagès, Teresa; Viscor, Ginés

    2014-02-01

    Intermittent hypobaric hypoxia (IHH) exposure, accompanied or not with active recovery, can help to skeletal muscle repair. However, the erythropoietic response elicited can disturb blood rheology and thus alter the oxygen delivery to tissues. Male Sprague-Dawley rats were studied in two basal states: untrained and trained and compared with early (1-3 days) and late (7-14 days) stages of damage recovery in three groups of trained rats that had suffered skeletal muscle injury: Control, passive recovery rats; HYP, rats exposed to IHH after muscle damage; and EHYP, trained rats that performed light aerobic exercise sessions in addition to IHH. Hematocrit, RBC count and hemoglobin were only elevated in the late stage of recovery in HYP (13%; 14% and 8%) and EHYP (18%; 13% and 15%) groups. Blood viscosity increased about double for EHYP rats. It is concluded that intermittent exposure to hypobaric hypoxia in combination with light aerobic exercise in normoxia has an erythropoietic effect, but also provides advantageous hemorheological conditions for the perfusion of damaged muscle. PMID:24373840

  2. Comparative analysis of sensitivity of different light-scattering techniques to blood oxygenation on the basis of multilayer tissue model

    NASA Astrophysics Data System (ADS)

    Kirillin, Mikhail Yu.; Priezzhev, Alexander V.; Myllylä, Risto

    2006-08-01

    This paper compares sensitivity to blood oxygenation of different schemes of detecting light scattered from or transmitted through a slab of tissue considered in the frames of a multilayer model. Comparison is made from the viewpoint of the sensitivity to oxygen saturation of certain blood volume confined within lower layers of different average thicknesses mimicking the upper and lower plexuses of skin, dermis and hypodermis. The model also includes upper layers, mimicking stratum corneum and epidermis, consisting of prickle and basal cell layers. The following signals were simulated with Monte Carlo technique and compared: diffuse scattering indicatrice, OCT signal, spatially resolved diffuse reflectance, time-of-flight and spectrophotometry signals. The optical parameters of the layers were chosen within the ranges corresponding to experimental data published in literature and our own OCT measurements. Heyney-Greenstein function was used as a phase function for all considered layers with anisotropy factor value varying for various layers. Blood fractions of different layers were chosen according to available data for diastolic state. We considered two wavelengths of 660 and 890 nm, located at different sides of the isobestic point of 805 nm, where the absorption coefficients of oxygenated and deoxygenated hemoglobin are equal. These wavelengths are used in pulse oximetry. Our simulation results show, that the highest sensitivity to changes in oxygen content in blood is at the wavelength of 660 nm, where the difference between absorption coefficient values is significant. For this wavelength all the techniques except OCT show good sensitivity to blood oxygenation in the model tissue. For the second wavelength goniophotometry, spatially resolved diffuse reflectance, and spectorphotometry exhibit sensitivity to oxygenation, but it is lower than for 660 nm due to a smaller absorption coefficient mismatch.

  3. Mechanical indentation improves cerebral blood oxygenation signal quality of functional near-infrared spectroscopy (fNIRS) during breath holding

    NASA Astrophysics Data System (ADS)

    Vogt, William C.; Romero, Edwin; LaConte, Stephen M.; Rylander, Christopher G.

    2013-03-01

    Functional near-infrared spectroscopy (fNIRS) is a well-known technique for non-invasively measuring cerebral blood oxygenation, and many studies have demonstrated that fNIRS signals can be related to cognitive function. However, the fNIRS signal is attenuated by the skin, while scalp blood content has been reported to influence cerebral oxygenation measurements. Mechanical indentation has been shown to increase light transmission through soft tissues by causing interstitial water and blood flow away from the compressed region. To study the effects of indentation on fNIRS, a commercial fNIRS system with 16 emitter/detector pairs was used to measure cerebral blood oxygenation at 2 Hz. This device used diffuse reflectance at 730 nm and 850 nm to calculate deoxy- and oxy-hemoglobin concentrations. A borosilicate glass hemisphere was epoxied over each sensor to function as both an indenter and a lens. After placing the indenter/sensor assembly on the forehead, a pair of plastic bands was placed on top of the fNIRS headband and strapped to the head to provide uniform pressure and tightened to approx. 15 N per strap. Cerebral blood oxygenation was recorded during a breath holding regime (15 second hold, 15 second rest, 6 cycles) in 4 human subjects both with and without the indenter array. Results showed that indentation increased raw signal intensity by 85 +/- 35%, and that indentation increased amplitude of hemoglobin changes during breath cycles by 313% +/- 105%. These results suggest that indentation improves sensing of cerebral blood oxygenation, and may potentially enable sensing of deeper brain tissues.

  4. Cerebral blood flow, arteriovenous oxygen difference, and outcome in head injured patients.

    PubMed Central

    Robertson, C S; Contant, C F; Gokaslan, Z L; Narayan, R K; Grossman, R G

    1992-01-01

    Cerebral blood flow (CBF) and other physiological variables were measured repeatedly for up to 10 days after severe head injury in 102 patients, and CBF levels were related to outcome. Twenty five of the patients had a reduced CBF [mean (SD) 0.29 (0.05) ml/g/min]; 47 had a normal CBF, (0.41 (0.10) ml/g/min); and 30 had a raised CBF (0.62 (0.14) ml/g/min). Cerebral arteriovenous oxygen differences were inversely related to CBF and averaged 2.1 (0.7) mumol/ml in the group with reduced CBF, 1.9 (0.5) mumol/ml in the group with normal CBF, and 1.6 (0.4) mumol/ml in the group with raised CBF. Patients with a reduced CBF had a poorer outcome than patients with a normal or raised CBF. Mortality was highest in patients with a reduced CBF, and was 32% at three months after injury, whereas only 21% of the patients with a normal CBF and 20% of the patients with a raised CBF died. There were no differences in the type of injury, initial score on the Glasgow Coma Scale, mean intracranial pressure (ICP), highest ICP, or the amount of medical treatment required to keep the ICP less than 20 mm Hg in each group. Systemic factors did not significantly contribute to the differences in CBF among the three groups. A logistic regression model of the effect of CBF on neurological outcome was developed. When adjusted for variables which were found to be significant confounders, including age, initial Glasgow Coma Score, haemoglobin concentration, cerebral perfusion pressure and cerebral metabolic rate of oxygen, a reduced CBF remained significantly associated with an unfavourable neurological outcome. PMID:1640238

  5. Simultaneous measurement of deep tissue blood flow and oxygenation using noncontact diffuse correlation spectroscopy flow-oximeter

    PubMed Central

    Li, Ting; Lin, Yu; Shang, Yu; He, Lian; Huang, Chong; Szabunio, Margaret; Yu, Guoqiang

    2013-01-01

    We report a novel noncontact diffuse correlation spectroscopy flow-oximeter for simultaneous quantification of relative changes in tissue blood flow (rBF) and oxygenation (Δ[oxygenation]). The noncontact probe was compared against a contact probe in tissue-like phantoms and forearm muscles (n = 10), and the dynamic trends in both rBF and Δ[oxygenation] were found to be highly correlated. However, the magnitudes of Δ[oxygenation] measured by the two probes were significantly different. Monte Carlo simulations and phantom experiments revealed that the arm curvature resulted in a significant underestimation (~−20%) for the noncontact measurements in Δ[oxygenation], but not in rBF. Other factors that may cause the residual discrepancies between the contact and noncontact measurements were discussed, and further comparisons with other established technologies are needed to identify/quantify these factors. Our research paves the way for noncontact and simultaneous monitoring of blood flow and oxygenation in soft and vulnerable tissues without distorting tissue hemodynamics. PMID:23446991

  6. Effects of dipyridamole and aminophylline on hemodynamics, regional myocardial blood flow and thallium-201 washout in the setting of a critical coronary stenosis

    SciTech Connect

    Granato, J.E.; Watson, D.D.; Belardinelli, L.; Cannon, J.M.; Beller, G.A. )

    1990-12-01

    Experiments were performed to characterize the interaction of intravenous dipyridamole and aminophylline on thallium-201 transport kinetics, regional myocardial blood flow and systemic hemodynamics in the presence of a critical coronary artery stenosis. In 12 dogs with a critical left anterior descending coronary artery stenosis, arterial pressure decreased from a mean value (+/- SEM) of 107 +/- 6 to 94 +/- 3 mm Hg and distal left anterior descending artery pressure decreased from 70 +/- 7 to 55 +/- 4 mm Hg after intravenous administration of dipyridamole. In the left anterior descending perfusion zone, the endocardial/epicardial flow ratio decreased from 0.70 to 0.36 and the intrinsic thallium washout rate was significantly prolonged. Intravenous aminophylline reversed the dipyridamole-induced systemic hypotension and transmural coronary steal and restored the thallium washout rate to baseline values. In six other dogs, aminophylline alone resulted in no alterations in systemic and coronary hemodynamics or regional myocardial blood flow. As expected, dipyridamole-induced vasodilation and coronary steal were prevented by aminophylline pretreatment. These data show that in a canine model of partial coronary stenosis, systemic hypotension, adverse regional flow effects and prolonged thallium-201 washout consequent to intravenously administered dipyridamole are promptly reversed by intravenous aminophylline administration. Aminophylline alone had no significant hemodynamic and coronary flow effects. This study provides further insight into the altered thallium kinetics occurring as a consequence of dipyridamole-induced vasodilation and suggests that the prompt reversal of symptoms and signs of ischemia with aminophylline in patients receiving intravenous dipyridamole for clinical imaging studies probably reflects the reversal of transmural coronary steal.

  7. Alveolar gas exchange and tissue oxygenation during incremental treadmill exercise, and their associations with blood O2 carrying capacity

    PubMed Central

    Rissanen, Antti-Pekka E.; Tikkanen, Heikki O.; Koponen, Anne S.; Aho, Jyrki M.; Hägglund, Harriet; Lindholm, Harri; Peltonen, Juha E.

    2012-01-01

    The magnitude and timing of oxygenation responses in highly active leg muscle, less active arm muscle, and cerebral tissue, have not been studied with simultaneous alveolar gas exchange measurement during incremental treadmill exercise. Nor is it known, if blood O2 carrying capacity affects the tissue-specific oxygenation responses. Thus, we investigated alveolar gas exchange and tissue (m. vastus lateralis, m. biceps brachii, cerebral cortex) oxygenation during incremental treadmill exercise until volitional fatigue, and their associations with blood O2 carrying capacity in 22 healthy men. Alveolar gas exchange was measured, and near-infrared spectroscopy (NIRS) was used to monitor relative concentration changes in oxy- (Δ[O2Hb]), deoxy- (Δ[HHb]) and total hemoglobin (Δ[tHb]), and tissue saturation index (TSI). NIRS inflection points (NIP), reflecting changes in tissue-specific oxygenation, were determined and their coincidence with ventilatory thresholds [anaerobic threshold (AT), respiratory compensation point (RC); V-slope method] was examined. Blood O2 carrying capacity [total hemoglobin mass (tHb-mass)] was determined with the CO-rebreathing method. In all tissues, NIPs coincided with AT, whereas RC was followed by NIPs. High tHb-mass associated with leg muscle deoxygenation at peak exercise (e.g., Δ[HHb] from baseline walking to peak exercise vs. tHb-mass: r = 0.64, p < 0.01), but not with arm muscle- or cerebral deoxygenation. In conclusion, regional tissue oxygenation was characterized by inflection points, and tissue oxygenation in relation to alveolar gas exchange during incremental treadmill exercise resembled previous findings made during incremental cycling. It was also found out, that O2 delivery to less active m. biceps brachii may be limited by an accelerated increase in ventilation at high running intensities. In addition, high capacity for blood O2 carrying was associated with a high level of m. vastus lateralis deoxygenation at peak exercise

  8. Production of active oxygen species by blood phagocytes of pregnant women and their newborns with intrauterine infection.

    PubMed

    Safronova, V G; Matveeva, N K; Lomova, N A; Belyaeva, A S; Vanko, L V

    2013-09-01

    We studied the relationship between changes in the maternal and newborn granulocyte functions under conditions of infection risk and realization. Women with normal gestation and their healthy newborns, pregnant women with a high risk of infection and their newborns, healthy or with intrauterine infection, were examined. Changes in the active oxygen species-dependent phagocytosis system were found in the blood of risk group patients. An inverse relationship between the parameters venous and umbilical cord blood was detected indicating a relationship between changes in functional activities of maternal and newborn granulocytes. The percentage of CD11b(+)cells in venous and umbilical cord blood strictly correlated with the percent of cells that phagocytosed FITC-labeled E. coli. Deviations in the generation of active oxygen species in phagocytosis seemed to be related to the expression of surface receptors in the risk groups. PMID:24288724

  9. Oxygen and carbon dioxide transport in time-dependent blood flow past fiber rectangular arrays

    NASA Astrophysics Data System (ADS)

    Zierenberg, Jennifer R.; Fujioka, Hideki; Hirschl, Ronald B.; Bartlett, Robert H.; Grotberg, James B.

    2009-03-01

    The influence of time-dependent flows on oxygen and carbon dioxide transport for blood flow past fiber arrays arranged in in-line and staggered configurations was computationally investigated as a model for an artificial lung. Both a pulsatile flow, which mimics the flow leaving the right heart and passing through a compliance chamber before entering the artificial lung, and a right ventricular flow, which mimics flow leaving the right heart and directly entering the artificial lung, were considered in addition to a steady flow. The pulsatile flow was modeled as a sinusoidal perturbation superimposed on a steady flow while the right ventricular flow was modeled to accurately depict the period of flow acceleration (increasing flow) and deceleration (decreasing flow) during systole followed by zero flow during diastole. It was observed that the pulsatile flow yielded similar gas transport as compared to the steady flow, while the right ventricular flow resulted in smaller gas transport, with the decrease increasing with Re. The pressure drop across the fiber array (a measure of the resistance), work (an indicator of the work required of the right heart), and shear stress (a measure of potential blood cell activation and damage) are lowest for steady flow, followed by pulsatile flow, and then right ventricular flow. The pressure drop, work, shear stress, and Sherwood numbers (a measure of the gas transport efficiency) decrease with increasing porosity and are smaller for AR <1 as compared to AR >1 (AR is the distance between fibers in the flow direction/distance between fibers in direction perpendicular to flow), although for small porosities the Sherwood numbers are of similar magnitude. In general, for any fiber array geometry, high pressure drop, work, and shear stresses correlate with high Sherwood numbers, and low pressure drop, work, and shear stresses correlate with low Sherwood numbers creating a need for a compromise between pressure drop/work/shear stresses

  10. Can We Better Estimate Resting Oxygen Consumption by Incorporating Arterial Blood Gases and Spirometric Determinations?

    PubMed Central

    Tonelli, Adriano R; Wang, Xiao-Feng; Abbay, Anara; Zhang, Qi; Ramos, José; McCarthy, Kevin

    2016-01-01

    BACKGROUND We hypothesize that oxygen consumption (V̇O2) estimation in patients with respiratory symptoms is inaccurate and can be improved by considering arterial blood gases or spirometric variables. METHODS For this retrospective study, we included consecutive subjects who underwent cardiopulmonary exercise testing. Resting V̇O2 was determined using breath-by-breath testing methodology. Using a training cohort (n = 336), we developed 3 models to predict V̇O2. In a validation group (n = 114), we compared our models with 7 available formulae. RESULTS Our first model (V̇O2 = −184.99 + 189.64 × body surface area [BSA, m2] + 1.49 × heart rate [beats/min] + 51.51 × FIO2 [21% = 0; 30% = 1] + 30.62 × gender [male = 1; female = 0]) showed an R2 of 0.5. Our second model (V̇O2 = −208.06 + 188.67 × BSA + 1.38 × heart rate + 35.6 × gender + 2.06 × breathing frequency [breaths/min]) showed an R2 of 0.49. The best R2 (0.68) was obtained with our last model, which included minute ventilation (V̇O2 = −142.92 + 0.52 × heart rate + 126.84 × BSA + 14.68 × minute ventilation [L]). In the validation cohort, these 3 models performed better than other available equations, but had wide limits of agreement, particularly in older individuals with shorter stature, higher heart rate, and lower maximum voluntary ventilation. CONCLUSIONS We developed more accurate formulae to predict resting V̇O2 in subjects with respiratory symptoms; however, equations had wide limits of agreement, particularly in certain groups of subjects. Arterial blood gases and spirometric variables did not significantly improve the predictive equations. PMID:25516992

  11. Analgesic effect of He-Ne laser irradiation of blood in acute myocardial infarction: possible neuro-humoral mechanisms

    NASA Astrophysics Data System (ADS)

    Khotiaintsev, Sergei N.; Doger-Guerrero, E.; Zemlink, A.; Sirenko, Yuri; Sychov, O.; Bogomolov, N.

    1996-01-01

    Statistically significant results on positive effects of low-energy intercardiac blood irradiation, based on observation of 354 patients suffering from Q-MI, are presented. The He-Ne laser and a catheterized flexible fiber-optic lightguide were used to perform the blood irradiation. The data obtained make it possible to draw a conclusion that the positive clinical effect of the laser blood irradiation is realized via stress-limiting mechanisms.

  12. The study of pain with blood oxygen level dependent functional magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Ibinson, James W.

    Using blood oxygen level dependent functional magnetic resonance imaging (BOLD FMRI), the brain areas activated by pain were studied. These initial studies led to interesting new findings about the body's response to pain and to the refinement of one method used in FMRI analysis for correction of physiologic noise (signal fluctuations caused by the cyclic and non-cyclic changes in the cardiovascular and respiratory status of the body). In the first study, evidence was provided suggesting that the multiple painful stimulations used in typical pain FMRI block designs may cause attenuation over time of the BOLD signal within activated areas. The effect this may have on pain investigations using multiple tasks has not been previously investigated. The demonstrated BOLD attenuation seems unique to pain studies. Several possible explanations exist, but two of the most likely are neural activity modulation by descending pain inhibitory mechanisms and changing hemodynamics caused by a physiologic response to pain. The second study began the investigation of hemodynamics by monitoring the physiologic response to pain for eight subjects in two phases. Phase one used a combination of standard operating suite monitors and research equipment to characterizing the physiologic response to pain. Phase two collected magnetic resonance quantitative flow images during painful nerve stimulation to test for changes in global cerebral blood flow. It is well established that changes in respiration and global blood flow can affect the BOLD response, leading to the final investigation of this dissertation. The brain activation induced by pain for the same eight subjects used in the physiologic response experiments described above was then studied by BOLD FMRI. By including the respiration signal and end-tidal carbon dioxide levels in the analysis of the images, the quantification and removal of image intensity variations correlated to breathing and end-tidal carbon dioxide changes could be

  13. Simultaneous myocardial strain and dark-blood perfusion imaging using a displacement-encoded MRI pulse sequence.

    PubMed

    Le, Yuan; Stein, Ashley; Berry, Colin; Kellman, Peter; Bennett, Eric E; Taylor, Joni; Lucas, Katherine; Kopace, Rael; Chefd'Hotel, Christophe; Lorenz, Christine H; Croisille, Pierre; Wen, Han

    2010-09-01

    The purpose of this study is to develop and evaluate a displacement-encoded pulse sequence for simultaneous perfusion and strain imaging. Displacement-encoded images in two to three myocardial slices were repeatedly acquired using a single-shot pulse sequence for 3 to 4 min, which covers a bolus infusion of Gadolinium contrast. The magnitudes of the images were T(1) weighted and provided quantitative measures of perfusion, while the phase maps yielded strain measurements. In an acute coronary occlusion swine protocol (n = 9), segmental perfusion measurements were validated against microsphere reference standard with a linear regression (slope 0.986, R(2) = 0.765, Bland-Altman standard deviation = 0.15 mL/min/g). In a group of ST-elevation myocardial infarction patients (n = 11), the scan success rate was 76%. Short-term contrast washout rate and perfusion are highly correlated (R(2) = 0.72), and the pixelwise relationship between circumferential strain and perfusion was better described with a sigmoidal Hill curve than linear functions. This study demonstrates the feasibility of measuring strain and perfusion from a single set of images. PMID:20544714

  14. The measurement of sequential changes in cerebral blood flow and oxygen metabolism by positron computed tomography with continuous inhalation of oxygen-15 labeled gases

    SciTech Connect

    Tanada, S.; Yonekura, Y.; Senda, M.; Nishimura, K.; Tamaki, N.; Saji, H.; Fujita, T.; Kobayashi, A.; Taki, W.; Ishikawa, M.

    1984-01-01

    The use of continuous inhalation of oxygen-15 labeled gases is a widely accepted method to measure regional cerebral blood flow (CBF) and oxygen metabolism (CMRO/sub 2/) with positron computed tomography (PCT). The purpose of this study is to evaluate the feasibility to measure sequential changes in CBF and CMRO/sub 2/ by PCT. The functional images of CBF, oxygen extraction fraction (OEF), and CMRO/sub 2/ were obtained using continuous inhalation of oxygen-15 labeled carbon dioxide and oxygen. The effects of spinal drainage in CBF and CMRO/sub 2/ were studied in patients with hydrocephalus following subarachnoid hemorrhage due to the rupture of intracranial aneurysm. Following the measurement in control state, 20 ml of cerebrospinal fluid (CSF) were withdrawn gradually through lumbar puncture, and sequential PCT scans were performed. CBF and CMRO/sub 2/ were markedly depressed in the case with hydrocephalus. The drainage of CSF significantly improved OEF and CMRO/sub 2/, whereas CBF remained depressed. In patients with chronic cerebrovascular disease, the changes in CBF were studied with inhalation of 5% carbon dioxide (CO/sub 2/). CO/sub 2/ loading demonstrated the increase in CBF, while poor regional increase was observed in ''moyamoya'' disease, which permitted the assessment of vascular response to the elevation of plasma CO/sub 2/. The authors preliminary work indicated the potential usefulness of sequential PCT to study the changes in CBF and CMRO/sub 2/ with various interventions.

  15. Abnormal White Matter Blood-Oxygen-Level-Dependent Signals in Chronic Mild Traumatic Brain Injury.

    PubMed

    Astafiev, Serguei V; Shulman, Gordon L; Metcalf, Nicholas V; Rengachary, Jennifer; MacDonald, Christine L; Harrington, Deborah L; Maruta, Jun; Shimony, Joshua S; Ghajar, Jamshid; Diwakar, Mithun; Huang, Ming-Xiong; Lee, Roland R; Corbetta, Maurizio

    2015-08-15

    Concussion, or mild traumatic brain injury (mTBI), can cause persistent behavioral symptoms and cognitive impairment, but it is unclear if this condition is associated with detectable structural or functional brain changes. At two sites, chronic mTBI human subjects with persistent post-concussive symptoms (three months to five years after injury) and age- and education-matched healthy human control subjects underwent extensive neuropsychological and visual tracking eye movement tests. At one site, patients and controls also performed the visual tracking tasks while blood-oxygen-level-dependent (BOLD) signals were measured with functional magnetic resonance imaging. Although neither neuropsychological nor visual tracking measures distinguished patients from controls at the level of individual subjects, abnormal BOLD signals were reliably detected in patients. The most consistent changes were localized in white matter regions: anterior internal capsule and superior longitudinal fasciculus. In contrast, BOLD signals were normal in cortical regions, such as the frontal eye field and intraparietal sulcus, that mediate oculomotor and attention functions necessary for visual tracking. The abnormal BOLD signals accurately differentiated chronic mTBI patients from healthy controls at the single-subject level, although they did not correlate with symptoms or neuropsychological performance. We conclude that subjects with persistent post-concussive symptoms can be identified years after their TBI using fMRI and an eye movement task despite showing normal structural MRI and DTI. PMID:25758167

  16. Blood Oxygen Level-Dependent Activation of the Primary Visual Cortex Predicts Size Adaptation Illusion

    PubMed Central

    Pooresmaeili, Arezoo; Arrighi, Roberto; Biagi, Laura; Morrone, Maria Concetta

    2016-01-01

    In natural scenes, objects rarely occur in isolation but appear within a spatiotemporal context. Here, we show that the perceived size of a stimulus is significantly affected by the context of the scene: brief previous presentation of larger or smaller adapting stimuli at the same region of space changes the perceived size of a test stimulus, with larger adapting stimuli causing the test to appear smaller than veridical and vice versa. In a human fMRI study, we measured the blood oxygen level-dependent activation (BOLD) responses of the primary visual cortex (V1) to the contours of large-diameter stimuli and found that activation closely matched the perceptual rather than the retinal stimulus size: the activated area of V1 increased or decreased, depending on the size of the preceding stimulus. A model based on local inhibitory V1 mechanisms simulated the inward or outward shifts of the stimulus contours and hence the perceptual effects. Our findings suggest that area V1 is actively involved in reshaping our perception to match the short-term statistics of the visual scene. PMID:24089504

  17. Deciphering phonemes from syllables in blood oxygenation level-dependent signals in human superior temporal gyrus.

    PubMed

    Zhang, Qingtian; Hu, Xiaolin; Luo, Huan; Li, Jianmin; Zhang, Xiaolu; Zhang, Bo

    2016-03-01

    Linguistic units such as phonemes and syllables are important for speech perception. How the brain encodes these units is not well understood. Many neuroimaging studies have found distinct representations of consonant-vowel syllables that shared one phoneme and differed in the other phoneme (e.g. /ba/ and /da/), but it is unclear whether this discrimination ability is due to the neural coding of phonemes or syllables. We combined functional magnetic resonance imaging with multivariate pattern analysis to explore this question. Subjects listened to nine Mandarin syllables in a consonant-vowel form. We successfully decoded phonemes from the syllables based on the blood oxygenation level-dependent signals in the superior temporal gyrus (STG). Specifically, a classifier trained on the cortical patterns elicited by a set of syllables, which contained two phonemes, could distinguish the cortical patterns elicited by other syllables that contained the two phonemes. The results indicated that phonemes have unique representations in the STG. In addition, there was a categorical effect, i.e. the cortical patterns of consonants were similar, and so were the cortical patterns of vowels. Further analysis showed that phonemes exhibited stronger encoding specificity in the mid-STG than in the anterior STG. PMID:26751256

  18. Darcy Permeability of Hollow Fiber Bundles Used in Blood Oxygenation Devices

    PubMed Central

    Pacella, Heather E.; Eash, Heidi J.; Federspiel, William J.

    2011-01-01

    Many industrial and biomedical devices (e.g. blood oxygenators and artificial lungs) use bundles of hollow fiber membranes for separation processes. Analyses of flow and mass transport within the shell-side of the fiber bundles most often model the bundle for simplicity as a packed bed or porous media, using a Darcy permeability coefficient estimated from the Blake-Kozeny equation to account for viscous drag from the fibers. In this study, we developed a simple method for measuring the Darcy permeability of hollow fiber membrane bundles and evaluated how well the Blake-Kozeny (BK) equation predicted the Darcy permeability for these bundles. Fiber bundles were fabricated from commercially available Celgard® ×30-240 fiber fabric (300 μm outer diameter fibers @ 35 and 54 fibers/inch) and from a fiber fabric with 193 μm fibers (61 fibers/inch). The fiber bundles were mounted to the bottom of an acrylic tube and Darcy permeability was determined by measuring the elapsed time for a column of glycerol solution to flow through a fiber bundle. The ratio of the measured Darcy permeability to that predicted from the BK equation varied from 1.09 to 0.56. A comprehensive literature review suggested a modified BK equation with the “constant” correlated to porosity. This modification improved the predictions of the BK equation, with the ratio of measured to predicted permeability varying from 1.13 to 0.84. PMID:22927706

  19. Noncontact Monitoring of Blood Oxygen Saturation Using Camera and Dual-Wavelength Imaging System.

    PubMed

    Shao, Dangdang; Liu, Chenbin; Tsow, Francis; Yang, Yuting; Du, Zijian; Iriya, Rafael; Yu, Hui; Tao, Nongjian

    2016-06-01

    We present a noncontact method to monitor blood oxygen saturation (SpO2). The method uses a CMOS camera with a trigger control to allow recording of photoplethysmography (PPG) signals alternatively at two particular wavelengths, and determines the SpO2 from the measured ratios of the pulsatile to the nonpulsatile components of the PPG signals at these wavelengths. The signal-to-noise ratio (SNR) of the SpO2 value depends on the choice of the wavelengths. We found that the combination of orange (λ = 611 nm) and near infrared (λ = 880 nm) provides the best SNR for the noncontact video-based detection method. This combination is different from that used in traditional contact-based SpO 2 measurement since the PPG signal strengths and camera quantum efficiencies at these wavelengths are more amenable to SpO2 measurement using a noncontact method. We also conducted a small pilot study to validate the noncontact method over an SpO2 range of 83%-98%. This study results are consistent with those measured using a reference contact SpO2 device ( r = 0.936, ). The presented method is particularly suitable for tracking one's health and wellness at home under free-living conditions, and for those who cannot use traditional contact-based PPG devices. PMID:26415199

  20. High-frequency photoacoustic imaging of erythrocyte aggregation and oxygen saturation: probing hemodynamic relations under pulsatile blood flow

    NASA Astrophysics Data System (ADS)

    Bok, Tae-Hoon; Hysi, Eno; Kolios, Michael C.

    2015-03-01

    In this paper, we investigate the feasibility of high-frequency photoacoustic (PA) imaging to study the shear rate dependent relationship between red blood cell (RBC) aggregation and oxygen saturation (SO2) in a simulated blood flow system. The PA signal amplitude increased during the formation of aggregates and cyclically varied at intervals corresponding to the beat rate (30, 60, 120, 180 and 240 bpm) for all optical wavelengths of illumination (750 and 850 nm).The SO2 also cyclically varied in phase with the PA signal amplitude for all beat rates. In addition, the mean blood flow velocity cyclically varied at the same interval of beat rate, and the shear rate (i.e. the radial gradient of flow velocity) also cyclically varied. On the other hand, the phase of the cyclic variation in the shear rate was reversed compared to that in the PA signal amplitude. This study indicates that RBC aggregation induced by periodic changes in the shear rate can be correlated with the SO2 under pulsatile blood flow. Furthermore, PA imaging of flowing blood may be capable of providing a new biomarker for the clinical application in terms of monitoring blood viscosity, oxygen delivery and their correlation.

  1. Myocardial performance and perfusion during exercise in patients with coronary artery disease caused by Kawasaki disease

    SciTech Connect

    Paridon, S.M.; Ross, R.D.; Kuhns, L.R.; Pinsky, W.W. )

    1990-01-01

    For a study of the natural history of coronary artery lesions after Kawasaki disease and their effect on myocardial blood flow reserve with exercise, five such patients underwent exercise testing on a bicycle. Oxygen consumption, carbon dioxide production, minute ventilation, and electrocardiograms were monitored continuously. Thallium-201 scintigraphy was performed for all patients. One patient stopped exercise before exhaustion of cardiovascular reserve but had no evidence of myocardial perfusion abnormalities. Four patients terminated exercise because of exhaustion of cardiovascular reserve; one had normal cardiovascular reserve and thallium scintiscans, but the remaining patients had diminished cardiovascular reserve. Thallium scintigrams showed myocardial ischemia in two and infarction in one. No patient had exercise-induced electrocardiographic changes. These results indicate that patients with residual coronary artery lesions after Kawasaki disease frequently have reduced cardiovascular reserve during exercise. The addition of thallium scintigraphy and metabolic measurements to exercise testing improved the detection of exercise-induced abnormalities of myocardial perfusion.

  2. Forearm oxygenation and blood flow kinetics during a sustained contraction in multiple ability groups of rock climbers.

    PubMed

    Fryer, Simon; Stoner, Lee; Scarrott, Carl; Lucero, Adam; Witter, Trevor; Love, Richard; Dickson, Tabitha; Draper, Nick

    2015-01-01

    Currently, the physiological mechanisms that allow elite level climbers to maintain intense isometric contractions for prolonged periods of time are unknown. Furthermore, it is unclear whether blood flow or muscle oxidative capacity best governs performance. This study aimed to determine the haemodynamic kinetics of 2 forearm flexor muscles in 3 ability groups of rock climbers. Thirty-eight male participants performed a sustained contraction at 40% of maximal voluntary contraction (MVC) until volitional fatigue. Oxygen saturation and blood flow was assessed using near infrared spectroscopy and Doppler ultrasound. Compared to control, intermediate, and advanced groups, the elite climbers had a significantly (P < 0.05) higher strength-to-weight ratio (MVC/N), de-oxygenated the flexor digitorum profundus significantly (P < 0.05) more (32, 34.3, and 42.8 vs. 63% O2, respectively), and at a greater rate (0.32, 0.27, and 0.34 vs. 0.77 O2%·s(-1), respectively). Furthermore, elite climbers de-oxygenated the flexor carpi radialis significantly (P < 0.05) more and at a greater rate than the intermediate group (36.5 vs. 14.6% O2 and 0.43 vs. 0.1O2%·s(-1), respectively). However, there were no significant differences in total forearm ∆ blood flow. An increased MVC/N is not associated with greater blood flow occlusion in elite climbers; therefore, oxidative capacity may be more important for governing performance. PMID:25311579

  3. The role of cerebral oxygenation and regional cerebral blood flow on tolerance to central hypovolemia.

    PubMed

    Kay, Victoria L; Rickards, Caroline A

    2016-02-15

    Tolerance to central hypovolemia is highly variable, and accumulating evidence suggests that protection of anterior cerebral blood flow (CBF) is not an underlying mechanism. We hypothesized that individuals with high tolerance to central hypovolemia would exhibit protection of cerebral oxygenation (ScO2), and prolonged preservation of CBF in the posterior vs. anterior cerebral circulation. Eighteen subjects (7 male/11 female) completed a presyncope-limited lower body negative pressure (LBNP) protocol (3 mmHg/min onset rate). ScO2 (via near-infrared spectroscopy), middle cerebral artery velocity (MCAv), posterior cerebral artery velocity (PCAv) (both via transcranial Doppler ultrasound), and arterial pressure (via finger photoplethysmography) were measured continuously. Subjects who completed ≥70 mmHg LBNP were classified as high tolerant (HT; n = 7) and low tolerant (LT; n = 11) if they completed ≤60 mmHg LBNP. The minimum difference in LBNP tolerance between groups was 193 s (LT = 1,243 ± 185 s vs. HT = 1,996 ± 212 s; P < 0.001; Cohen's d = 3.8). Despite similar reductions in mean MCAv in both groups, ScO2 decreased in LT subjects from -15 mmHg LBNP (P = 0.002; Cohen's d=1.8), but was maintained at baseline values until -75 mmHg LBNP in HT subjects (P < 0.001; Cohen's d = 2.2); ScO2 was lower at -30 and -45 mmHg LBNP in LT subjects (P ≤ 0.02; Cohen's d ≥ 1.1). Similarly, mean PCAv decreased below baseline from -30 mmHg LBNP in LT subjects (P = 0.004; Cohen's d = 1.0), but remained unchanged from baseline in HT subjects until -75 mmHg (P = 0.006; Cohen's d = 2.0); PCAv was lower at -30 and -45 mmHg LBNP in LT subjects (P ≤ 0.01; Cohen's d ≥ 0.94). Individuals with higher tolerance to central hypovolemia exhibit prolonged preservation of CBF in the posterior cerebral circulation and sustained cerebral tissue oxygenation, both associated with a delay in the onset of presyncope. PMID:26676249

  4. Investigating oxygen-14 water and carbon-10 carbon dioxide as cerebral blood flow tracers in PET

    NASA Astrophysics Data System (ADS)

    Schueller, Michael John

    2001-10-01

    Functional brain mapping with positron emission tomography (PET) is limited largely by exam time, mainly waiting between subsequent injections for the prior dose to decay. This time can be reduced by using a shorter- lived isotope than the commonly used oxygen-15 (β+, 122 second half life). Two alternative isotopes have been developed. These isotopes, oxygen-14 (β+, 2314 kev γ, 71 second half life) and carbon-10 ((β+, 719 kev γ, 19 second half life), hold the promise of increasing study repetition rate by a factor of 2-5. Production targetry for 10C and 14O were developed for an 11.4 MeV, 6-8 mm FWHM proton beam from the UW cyclotron. 14O is produced via the 14N(p,n)14O reaction in a 99.5% N2 0.5% O2 flow through target, and 10C is produced by bombarding enriched 10B 2O3 via the 10B(p.n)10C reaction. Extraction of the 10C from the boric oxide melt is strongly temperature dependent, and evidence is presented indicating that this extraction is greatly aided by convection. Both isotopes were converted to CO2 in high-speed flow-through chemistry, and the radiochemical purity of the final product was measured. The dosimetry of these short lived blood flow tracers was calculated with computer simulation. Where possible the calculated results were compared to measured and calculated values in the literature, and show good agreement. This study shows that both 14O and 10C suffer dosimetrically from their gamma rays, but this is offset by their greater study repetition rates. The effects of the prompt gamma rays of 14O and 10C on image degradation were explored on a variety of PET scanners, in both 2D and 3D phantom studies. These data show minimal effect in the final image quality. This is born out by human imaging, performed at the Rigshospitalet in Copenhagen, Denmark.

  5. Simultaneous assessment of red blood cell aggregation and oxygen saturation under pulsatile flow using high-frequency photoacoustics

    PubMed Central

    Bok, Tae-Hoon; Hysi, Eno; Kolios, Michael C.

    2016-01-01

    We investigate the feasibility of photoacoustic (PA) imaging for assessing the correlation between red blood cell (RBC) aggregation and the oxygen saturation (sO2) in a simulated pulsatile blood flow system. For the 750 and 850 nm illuminations, the PA amplitude (PAA) increased and decreased as the mean blood flow velocity decreased and increased, respectively, at all beat rates (60, 120 and 180 bpm). The sO2 also cyclically varied, in phase with the PAA for all beat rates. However, the linear correlation between the sO2 and the PAA at 850 nm was stronger than that at 750 nm. These results suggest that the sO2 can be correlated with RBC aggregation induced by decreased mean shear rate in pulsatile flow, and that the correlation is dependent on the optical wavelength. The hemodynamic properties of blood flow assessed by PA imaging may be used to provide a new biomarker for simultaneous monitoring blood viscosity related to RBC aggregation, oxygen delivery related to the sO2 and their clinical correlation. PMID:27446705

  6. A venous outflow method for measurement of rapid changes of the cerebral blood flow and oxygen consumption in the rat.

    PubMed

    Nilsson, B; Siesjö, B K

    1983-01-01

    A technique for continuous measurement of cerebral venous outflow in the rat is described. The method involves cannulation of one retroglenoid vein close to its exit from the skull, and diversion of cerebral venous blood through a closed extracorporal circuit with a drop recording device, the blood being returned to the central venous circulation via a catheter in the external jugular vein. Occlusion of the contralateral retroglenoid vein increases measured flow and minimizes extracerebral contamination of the diverted cerebral venous blood. The venous outflow system is not further isolated from cerebral or potential extracerebral collaterals. Thus, the mass of tissue drained cannot be exactly defined anatomically. However, the experiments involving changes of PP, arterial CO2 tension, and induction of epileptic seizure activity, and simultaneous indirect measurements with radioactive tracer technique, indicate that significant extracerebral contamination does not occur and that in short term measurements the venous outflow represents cerebral blood flow (CBF) in a constant mass of (dorsal and central, mainly forebrain) cerebral tissue. Measurement of arterial blood pressure and pressure in the cisterna magna allows calculation of cerebral perfusion pressure (PP). By simultaneous measurement of arterial and cerebral venous oxygen content changes in cerebral oxygen consumption (CMRO2) can be calculated. The method has been applied to document several situations of transient CBF and CMRO2 changes. PMID:6658967

  7. Simultaneous assessment of red blood cell aggregation and oxygen saturation under pulsatile flow using high-frequency photoacoustics.

    PubMed

    Bok, Tae-Hoon; Hysi, Eno; Kolios, Michael C

    2016-07-01

    We investigate the feasibility of photoacoustic (PA) imaging for assessing the correlation between red blood cell (RBC) aggregation and the oxygen saturation (sO2) in a simulated pulsatile blood flow system. For the 750 and 850 nm illuminations, the PA amplitude (PAA) increased and decreased as the mean blood flow velocity decreased and increased, respectively, at all beat rates (60, 120 and 180 bpm). The sO2 also cyclically varied, in phase with the PAA for all beat rates. However, the linear correlation between the sO2 and the PAA at 850 nm was stronger than that at 750 nm. These results suggest that the sO2 can be correlated with RBC aggregation induced by decreased mean shear rate in pulsatile flow, and that the correlation is dependent on the optical wavelength. The hemodynamic properties of blood flow assessed by PA imaging may be used to provide a new biomarker for simultaneous monitoring blood viscosity related to RBC aggregation, oxygen delivery related to the sO2 and their clinical correlation. PMID:27446705

  8. Maternal hypoxia decreases capillary supply and increases metabolic inefficiency leading to divergence in myocardial oxygen supply and demand.

    PubMed

    Hauton, David; Al-Shammari, Abdullah; Gaffney, Eamonn A; Egginton, Stuart

    2015-01-01

    Maternal hypoxia is associated with a decrease in left ventricular capillary density while cardiac performance is preserved, implying a mismatch between metabolism and diffusive exchange. We hypothesised this requires a switch in substrate metabolism to maximise efficiency of ATP production from limited oxygen availability. Rat pups from pregnant females exposed to hypoxia (FIO2=0.12) at days 10-20 of pregnancy were grown to adulthood and working hearts perfused ex vivo. 14C-labelled glucose and 3H-palmitate were provided as substrates and metabolism quantified from recovery of 14CO2 and 3H2O, respectively. Hearts of male offspring subjected to Maternal Hypoxia showed a 20% decrease in cardiac output (P<0.05), despite recording a 2-fold increase in glucose oxidation (P<0.01) and 2.5-fold increase (P<0.01) in palmitate oxidation. Addition of insulin to Maternal Hypoxic hearts, further increased glucose oxidation (P<0.01) and suppressed palmitate oxidation (P<0.05), suggesting preservation in insulin signalling in the heart. In vitro enzyme activity measurements showed that Maternal Hypoxia increased both total and the active component of cardiac pyruvate dehydrogenase (both P<0.01), although pyruvate dehydrogenase sensitivity to insulin was lost (NS), while citrate synthase activity declined by 30% (P<0.001) and acetyl-CoA carboxylase activity was unchanged by Maternal Hypoxia, indicating realignment of the metabolic machinery to optimise oxygen utilisation. Capillary density was quantified and oxygen diffusion characteristics examined, with calculated capillary domain area increased by 30% (P<0.001). Calculated metabolic efficiency decreased 4-fold (P<0.01) for Maternal Hypoxia hearts. Paradoxically, the decline in citrate synthase activity and increased metabolism suggest that the scope of individual mitochondria had declined, rendering the myocardium potentially more sensitive to metabolic stress. However, decreasing citrate synthase may be essential to preserve

  9. Maternal Hypoxia Decreases Capillary Supply and Increases Metabolic Inefficiency Leading to Divergence in Myocardial Oxygen Supply and Demand

    PubMed Central

    Hauton, David; Al-Shammari, Abdullah; Gaffney, Eamonn A.; Egginton, Stuart

    2015-01-01

    Maternal hypoxia is associated with a decrease in left ventricular capillary density while cardiac performance is preserved, implying a mismatch between metabolism and diffusive exchange. We hypothesised this requires a switch in substrate metabolism to maximise efficiency of ATP production from limited oxygen availability. Rat pups from pregnant females exposed to hypoxia (FIO2=0.12) at days 10-20 of pregnancy were grown to adulthood and working hearts perfused ex vivo. 14C-labelled glucose and 3H-palmitate were provided as substrates and metabolism quantified from recovery of 14CO2 and 3H2O, respectively. Hearts of male offspring subjected to Maternal Hypoxia showed a 20% decrease in cardiac output (P<0.05), despite recording a 2-fold increase in glucose oxidation (P<0.01) and 2.5-fold increase (P<0.01) in palmitate oxidation. Addition of insulin to Maternal Hypoxic hearts, further increased glucose oxidation (P<0.01) and suppressed palmitate oxidation (P<0.05), suggesting preservation in insulin signalling in the heart. In vitro enzyme activity measurements showed that Maternal Hypoxia increased both total and the active component of cardiac pyruvate dehydrogenase (both P<0.01), although pyruvate dehydrogenase sensitivity to insulin was lost (NS), while citrate synthase activity declined by 30% (P<0.001) and acetyl-CoA carboxylase activity was unchanged by Maternal Hypoxia, indicating realignment of the metabolic machinery to optimise oxygen utilisation. Capillary density was quantified and oxygen diffusion characteristics examined, with calculated capillary domain area increased by 30% (P<0.001). Calculated metabolic efficiency decreased 4-fold (P<0.01) for Maternal Hypoxia hearts. Paradoxically, the decline in citrate synthase activity and increased metabolism suggest that the scope of individual mitochondria had declined, rendering the myocardium potentially more sensitive to metabolic stress. However, decreasing citrate synthase may be essential to preserve

  10. The neural basis of the blood-oxygen-level-dependent functional magnetic resonance imaging signal.

    PubMed Central

    Logothetis, Nikos K

    2002-01-01

    Magnetic resonance imaging (MRI) has rapidly become an important tool in clinical medicine and biological research. Its functional variant (functional magnetic resonance imaging; fMRI) is currently the most widely used method for brain mapping and studying the neural basis of human cognition. While the method is widespread, there is insufficient knowledge of the physiological basis of the fMRI signal to interpret the data confidently with respect to neural activity. This paper reviews the basic principles of MRI and fMRI, and subsequently discusses in some detail the relationship between the blood-oxygen-level-dependent (BOLD) fMRI signal and the neural activity elicited during sensory stimulation. To examine this relationship, we conducted the first simultaneous intracortical recordings of neural signals and BOLD responses. Depending on the temporal characteristics of the stimulus, a moderate to strong correlation was found between the neural activity measured with microelectrodes and the BOLD signal averaged over a small area around the microelectrode tips. However, the BOLD signal had significantly higher variability than the neural activity, indicating that human fMRI combined with traditional statistical methods underestimates the reliability of the neuronal activity. To understand the relative contribution of several types of neuronal signals to the haemodynamic response, we compared local field potentials (LFPs), single- and multi-unit activity (MUA) with high spatio-temporal fMRI responses recorded simultaneously in monkey visual cortex. At recording sites characterized by transient responses, only the LFP signal was significantly correlated with the haemodynamic response. Furthermore, the LFPs had the largest magnitude signal and linear systems analysis showed that the LFPs were better than the MUAs at predicting the fMRI responses. These findings, together with an analysis of the neural signals, indicate that the BOLD signal primarily measures the input

  11. RSI: oxygen consumption, blood flow, and reoxygenation in patients suffering RSI measured by noninvasive optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Thijssen, Dick H. J.; van Uden, Caro J. T.; Krijgsman, Hans; Colier, Willy N. J. M.

    2003-07-01

    Background: Repetitive Strain Injury (RSI) is a major problem in nowadays health care and creates high financial costs and personal distress. Average prevalence rates in the Netherlands vary from 20-40% of the working population. Insight into the patho-physiological mechanism of RSI is important in order to establish adequate treatment and prevention programs. Objective: The aim of this study was to gain insight in muscle oxygen consumption (mVO2), blood flow (BF), and reoxygenation (ReOx) in the forearm of computer workers with stage III Repetitive Strain Injury (RSI). Method: We have used continuous wave infrared spectroscopy (NIRS) to measure these variables. Measurements were conducted on the extensor and flexor muscle in both arms as well in RSI-patients (n=10) as in control subjects (n=21). A protocol of increased isometric repetitive contraction in a handgrip ergonometer was used with increasing levels of strength. Results: mVO2 in the extensor muscle in RSI-subjects (dominant side) was increased compared to control subjects and compared to the non-dominant side (p<0.05). ReOx was not increased in RSI (dominant side-extensor muscle). However, there was a tendency towards statistical significance (p=0.065). BF in rest was equal in both groups, however after exercise it tended to be increased. Half-time recovery (T ») was measured during only one part of the protocol and it was significantly increased (p<0.05). Conclusion: mVO2 in RSI is impaired. BF and ReOx did not show difference between both groups. Future research should aim at a microvascular dysfunction in RSI.

  12. Segregation analysis of blood oxygen saturation in broilers suggests a major gene influence on ascites.

    PubMed

    Navarro, P; Visscher, P M; Chatziplis, D; Koerhuis, A N M; Haley, C S

    2006-12-01

    1. Blood oxygen saturation (SaO) is a potential indicator trait for resistance to ascites in chickens. 2. The objective of the study was to investigate the genetic architecture of SaO in a meat-type chicken line reared in commercial conditions. 3. Data were collected over 15 generations of selection and were divided into two data sets on the basis of a change in recording age from 6 to 5 weeks of age, approximately halfway through the period. The resulting pedigrees comprised in excess of 90,000 birds each and, on average, 12% of these birds had SaO records. 4. Segregation analyses of SaO were carried out assuming a mixed inheritance model that included a major locus segregating in a polygenic background. 5. The analyses suggest that a major gene is involved in the genetic control of SaO in this line. The putative gene acts in a dominant fashion and has an additive effect of around 0.90 sigma(p), equivalent to a predicted difference in SaO between the two homozygous classes of more than 10%. The frequency of the allele that increases SaO changed from 0.53 to 0.65 from the first to the second set of data, consistent with selection on SaO scores. 6. Using estimated genotype probabilities at the putative major locus, we inferred that it acts in an overdominant fashion on body weight and fleshing score. If the low SaO allele leads to susceptibility to ascites, its combined effects are consistent with it being maintained in the population by a balance of natural selection on fitness nad artificial selection on growth and carcase traits. 7. Even with selection on both SaO and growth traits, the combined genotypic effects would make it difficult to remove the unfavourable low-SaO allele by means of traditional selection without the use of genetic markers. PMID:17190674

  13. Longitudinal decrease in blood oxygenation level dependent response in cerebral amyloid angiopathy

    PubMed Central

    Switzer, Aaron R.; McCreary, Cheryl; Batool, Saima; Stafford, Randall B.; Frayne, Richard; Goodyear, Bradley G.; Smith, Eric E.

    2016-01-01

    Lower blood oxygenation level dependent (BOLD) signal changes in response to a visual stimulus in functional magnetic resonance imaging (fMRI) have been observed in cross-sectional studies of cerebral amyloid angiopathy (CAA), and are presumed to reflect impaired vascular reactivity. We used fMRI to detect a longitudinal change in BOLD responses to a visual stimulus in CAA, and to determine any correlations between these changes and other established biomarkers of CAA progression. Data were acquired from 22 patients diagnosed with probable CAA (using the Boston Criteria) and 16 healthy controls at baseline and one year. BOLD data were generated from the 200 most active voxels of the primary visual cortex during the fMRI visual stimulus (passively viewing an alternating checkerboard pattern). In general, BOLD amplitudes were lower at one year compared to baseline in patients with CAA (p = 0.01) but were unchanged in controls (p = 0.18). The longitudinal difference in BOLD amplitudes was significantly lower in CAA compared to controls (p < 0.001). White matter hyperintensity (WMH) volumes and number of cerebral microbleeds, both presumed to reflect CAA-mediated vascular injury, increased over time in CAA (p = 0.007 and p = 0.001, respectively). Longitudinal increases in WMH (rs = 0.04, p = 0.86) or cerebral microbleeds (rs = − 0.18, p = 0.45) were not associated with the longitudinal decrease in BOLD amplitudes. PMID:27104140

  14. Evaluation of Intrarenal Oxygenation in Iodinated Contrast-Induced Acute Kidney Injury–Susceptible Rats by Blood Oxygen Level–Dependent Magnetic Resonance Imaging

    PubMed Central

    Li, Lu-Ping; Lu, Jing; Zhou, Ying; Papadopoulou, Maria V.; Franklin, Tammy; Bokhary, Ujala; Solomon, Richard; Sen, Anindya; Prasad, Pottumarthi V.

    2016-01-01

    Objectives The objectives of this study were to evaluate differences in intrarenal oxygenation as assessed by blood oxygen level–dependent (BOLD) magnetic resonance imaging in contrast-induced acute kidney injury (CIAKI)–susceptible rats when using 4 contrast media with different physicochemical properties and to demonstrate the feasibility of acquiring urinary neutrophil gelatinase–associated lipocalin (NGAL) levels as a marker of CIAKI in this model. Materials and Methods Our institutional animal care and use committee approved the study. Sixty-six Sprague-Dawley rats were divided into CIAKI-susceptible groups (received nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester [10 mg/kg] and cycloxygenase inhibitor indomethacin [10mg/kg]) and control groups (received saline instead). One of the 4 iodinated contrast agents (iothalamate, iohexol, ioxaglate, or iodixanol) was then administered (1600-mg organic iodine per kilogram of body weight). Multiple blood oxygen level–dependent magnetic resonance images were acquired on a Siemens 3.0-T scanner using a multiple gradient recalled echo sequence at baseline, after N-nitro-L-arginine methyl ester (or saline), indomethacin (or saline), and iodinated contrast agent (or placebo). R2* (R2* = 1/T2*) maps were generated inline on the scanner. A mixed-effects growth curve model with first-order autoregressive variance-covariance was used to analyze the temporal data. Urinary NGAL, a marker of kidney injury (unlike serum creatinine), was measured 4 hours after contrast injection in the 2 subgroups. Results Differences in blood oxygen level–dependent magnetic resonance imaging results between the contrast media were observed in all 4 renal regions. However, the inner stripe of the outer medulla (ISOM) showed the most pronounced changes in the CIAKI-susceptible group and R2* increased significantly (P < 0.01) over time with all 4 contrast media. In the control groups, only iodixanol showed an increase in R2

  15. Achilles tendon suture deteriorates tendon capillary blood flow with sustained tissue oxygen saturation – an animal study

    PubMed Central

    Kraemer, Robert; Lorenzen, Johan; Rotter, Robert; Vogt, Peter M; Knobloch, Karsten

    2009-01-01

    Background Treatment of ruptured Achilles tendons currently constitutes of conservative early functional treatment or surgical treatment either by open or minimal invasive techniques. We hypothesize that an experimental Achilles tendon suture in an animal model significantly deteriorates Achilles tendon microcirculation immediately following suturing. Methods Fifteen Achilles tendons of eight male Wistar rats (275–325 g) were included. After preparation of the Achilles tendon with a medial paratendinous approach, Achilles tendon microcirculation was assessed using combined Laser-Doppler and spectrophotometry (Oxygen-to-see) regarding: - tendinous capillary blood flow [arbitrary units AU] - tendinous tissue oxygen saturation [%] - tendinous venous filling pressure [rAU] The main body of the Achilles tendon was measured in the center of the suture with 50 Hz. 10 minutes after Achilles tendon suture (6-0 Prolene), a second assessment of microcirculatory parameters was performed. Results Achilles tendon capillary blood flow decreased by 57% following the suture (70 ± 30 AU vs. 31 ± 16 AU; p < 0.001). Tendinous tissue oxygen saturation remained at the same level before and after suture (78 ± 17% vs. 77 ± 22%; p = 0.904). Tendinous venous filling pressure increased by 33% (54 ± 16 AU vs. 72 ± 20 AU; p = 0.019) after suture. Conclusion Achilles tendon suture in anaesthetised rats causes an acute loss of capillary perfusion and increases postcapillary venous filling pressures indicating venous stasis. The primary hypothesis of this study was confirmed. In contrast, tendinous tissue oxygen saturation remains unchanged excluding acute intratendinous hypoxia within the first 10 minutes after suture. Further changes of oxygen saturation remain unclear. Furthermore, it remains to be determined to what extent reduced capillary blood flow as well as increased postcapillary stasis might influence tendon healing from a microcirculatory point of view in this animal setting

  16. Adaptation of cerebral oxygen metabolism and blood flow and modulation of neurovascular coupling with prolonged stimulation in human visual cortex

    PubMed Central

    Moradi, Farshad; Buxton, Richard B

    2013-01-01

    Prolonged visual stimulation results in neurophysiologic and hemodynamic adaptation. However, the hemodynamic adaptation appears to be small compared to neural adaptation. It is not clear how the cerebral metabolic rate of oxygen (CMRO2) is affected by adaptation. We measured cerebral blood flow (CBF) and CMRO2 change in responses to peripheral stimulation either continuously, or intermittently (on/off cycles). A linear system’s response to the continuous input should be equal to the sum of the original response to the intermittent input and a version of that response shifted by half a cycle. The CMRO2 response showed a large non-linearity consistent with adaptation, the CBF response adapted to a lesser degree, and the blood oxygenation level dependent (BOLD) response was nearly linear. The metabolic response was coupled with a larger flow in the continuous condition than in the intermittent condition. Our results suggest that contrast adaptation improves energy economy of visual processing. However BOLD modulations may not accurately represent the underlying metabolic nonlinearity due to modulation of the coupling of blood flow and oxygen metabolism changes. PMID:23732885

  17. Intra-subject variability of snoring sounds in relation to body position, sleep stage, and blood oxygen level.

    PubMed

    Azarbarzin, Ali; Moussavi, Zahra

    2013-04-01

    In a multidimensional feature space, the snoring sounds can extend from a very compact cluster to highly distinct clusters. In this study, we investigated the cause of snoring sound's variation within the snorers. It is known that a change in body position and sleep stage can affect snoring during sleep but it is unclear whether positional, sleep state, and blood oxygen level variations cause the snoring sounds to have different characteristics, and if it does how significant that effect would be. We extracted 12 characteristic features from snoring sound segments of 57 snorers and transformed them into a 4-D feature space using principal component analysis (PCA). Then, they were grouped based on the body position (side, supine, and prone), sleep stage (NREM, REM, and Arousal), and blood oxygen level (Normal and Desaturation). The probability density function of the transformed features was calculated for each class of categorical variables. The distance between the class-densities were calculated to determine which of these parameters affects the snoring sounds significantly. Analysis of Variance (ANOVA) was run for each categorical variable. The results show that the positional change has the highest effect on the snoring sounds; it results in forming distinct clusters of snoring sounds. Also, sleep state and blood oxygen level variation have been found to moderately affect the snoring sounds. PMID:23269579

  18. [Studies of the blood antioxidant system and oxygen-transporting properties of human erythrocytes during 105-day isolation].

    PubMed

    Brazhe, N A; Baĭzhumanov, A A; Parshina, E Iu; Iusipovich, A I; Akhalaia, M Ia; Iarlykova, Iu V; Labetskaia, O I; Ivanova, S M; Morukov, B V; Maksimov, G V

    2011-01-01

    Effects of strict 105-d isolation on blood antioxidant status, erythrocyte membrane processes and oxygen-binding properties of hemoglobin were studied in 6 male volunteers (25 to 40 y.o.) in ground-based simulation of a mission to Mars (experiment Mars-105). The parameters were measured using venous blood samples collected during BDC, on days 35, 70 and 105 of the experiment and on days 7 and 14-15 after its completion. Methods of biochemistry (determination of enzyme activity and thin-layer chromatography) and biophysical (laser interference microscopy, Raman spectroscopy) showed changes in relative content of lipid and phospholipid fractions suggesting growth of membrane microviscosity and increase in TBA-AP (active products of lipids peroxidation interacting with thiobarbituric acid). A significant increase in glucose-6-phosphate dehydrogenase and superoxide dismutase activities against reduction of catalase activity points to both reparative processes in erythrocytes and disbalance between the number of evolving active forms of oxygen and antioxidant protection mechanisms in cells. Hemoglobin sensitivity of oxygen and blood level of oxyhemoglobin were found to increase, too. It is presumed that adaptation of organism to stresses experienced during and after the experiment may destroy balance of the antioxidant protection systems which is conducive to oxidation of membrane phospholipids, alteration of their content, increase of membrane microviscosity and eventual failure of the gas-exchange function of erythrocytes. PMID:21675192

  19. Investigation of source-detector separation optimization for an implantable perfusion and oxygenation sensor for liver blood vessels

    NASA Astrophysics Data System (ADS)

    Baba, J. S.; Akl, T. J.; Coté, G. L.; Wilson, M. A.; Ericson, M. N.

    2011-03-01

    An implanted system is being developed to monitor transplanted liver health during the critical 7-10 day period posttransplantation. The unit will monitor organ perfusion and oxygen consumption using optically-based probes placed on both the inflow and outflow blood vessels, and on the liver parenchymal surface. Sensing probes are based on a 3- wavelength LED source and a photodiode detector. Sample diffuse reflectance is measured at 735, 805, and 940 nm. To ascertain optimal source-to-photodetector spacing for perfusion measurement in blood vessels, an ex vivo study was conducted. In this work, a dye mixture simulating 80% blood oxygen saturation was developed and perfused through excised porcine arteries while collecting data for various preset probe source-to-photodetector spacings. The results from this study demonstrate a decrease in the optical signal with decreasing LED drive current and a reduction in perfusion index signal with increasing probe spacing. They also reveal a 2- to 4-mm optimal range for blood vessel perfusion probe source-to-photodetector spacing that allows for sufficient perfusion signal modulation depth with maximized signal to noise ratio (SNR). These findings are currently being applied to guide electronic configuration and probe placement for in vivo liver perfusion porcine model studies.

  20. The influence of nanodiamond on the oxygenation states and micro rheological properties of human red blood cells in vitro

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Chung; Tsai, Lin-Wei; Perevedentseva, Elena; Chang, Hsin-Hou; Lin, Ching-Hui; Sun, Der-Shan; Lugovtsov, Andrei E.; Priezzhev, Alexander; Mona, Jani; Cheng, Chia-Liang

    2012-10-01

    Nanodiamond has been proven to be biocompatible and proposed for various biomedical applications. Recently, nanometer-sized diamonds have been demonstrated as an effective Raman/fluorescence probe for bio-labeling, as well as, for drug delivery. Bio-labeling/drug delivery can be extended to the human blood system, provided one understands the interaction between nanodiamonds and the blood system. Here, the interaction of nanodiamonds (5 and 100 nm) with human red blood cells (RBC) in vitro is discussed. Measurements have been facilitated using Raman spectroscopy, laser scanning fluorescence spectroscopy, and laser diffractometry (ektacytometry). Data on cell viability and hemolytic analysis are also presented. Results indicate that the nanodiamonds in the studied condition do not cause hemolysis, and the cell viability is not affected. Importantly, the oxygenation/deoxygenation process was not found to be altered when nanodiamonds interacted with the RBC. However, the nanodiamond can affect some RBC properties such as deformability and aggregation in a concentration dependent manner. These results suggest that the nanodiamond can be used as an effective bio-labeling and drug delivery tool in ambient conditions, without complicating the blood's physiological conditions. However, controlling the blood properties including deformability of RBCs and rheological properties of blood is necessary during treatment.

  1. Adenosine enhances myocardial glucose uptake only in the presence of insulin.

    PubMed

    Law, W R; McLane, M P

    1991-09-01

    Better understood in other tissues, the effects of adenosine on insulin-stimulated glucose uptake in the heart are poorly understood. Under pentobarbital anesthesia, we instrumented mongrel dogs to obtain general hemodynamics (blood pressure and heart rate), and arterial and coronary sinus blood samples for measuring oxygen and glucose concentrations. An electromagnetic blood flow probe around the circumflex coronary artery allowed determinations of blood flow, and calculation of substrate uptake by the heart (Fick principle). Somatostatin (SRIF) was infused intravenously (0.8 micrograms/kg/min) along with 0, 0.5, 1.0, 5.0, or 10 mU/kg/min regular insulin, and variable quantities of glucose to maintain euglycemia. Concomitant with the SRIF, insulin, and glucose infusions, adenosine was infused in logarithmically increasing rates (0, 0.01, 0.1, 1.0, 10 or 100 mumol/min) for 30 minutes each into the main left coronary arteries. Insulin infusions increased myocardial glucose uptake in a dose-dependent manner. The heart displayed exquisite sensitivity to insulin, with an ED50 of approximately 14 microU/mL (serum insulin). Adenosine infusions in the absence of insulin (SRIF infusion) increased coronary blood flow, but did not alter myocardial glucose uptake. In the presence of insulin, adenosine increased the maximal value for glucose uptake without changing sensitivity to insulin. These results indicate that adenosine enhances myocardial responsiveness to insulin, with respect to glucose uptake, independent of changes in blood flow. Since glucose can be used for anaerobic metabolism, and adenosine levels are known to increase under situations in which myocardial oxygenation is inadequate, these data have serious implications for conditions such as myocardial ischemia or hypoxia, when glycolytic substrate availability is vital. PMID:1680214

  2. Blood

    MedlinePlus

    ... fight infection and are part of your body's defense system. Platelets help blood to clot when you have a cut or wound. Bone marrow, the spongy material inside your bones, makes new blood cells. Blood cells ...

  3. Transient myocardial ischaemia after acute myocardial infarction.

    PubMed Central

    Currie, P; Saltissi, S

    1990-01-01

    The prevalence and characteristics of transient myocardial ischaemia were studied in 203 patients with recent acute myocardial infarction by both early (6.4 days) and late (38 days) ambulatory monitoring of the ST segment. Transient ST segment depression was much commoner during late (32% patients) than early (14%) monitoring. Most transient ischaemia (greater than 85% episodes) was silent and 80% of patients had only silent episodes. During late monitoring painful ST depression was accompanied by greater ST depression and tended to occur at a higher heart rate. Late transient ischaemia showed a diurnal distribution, occurred at a higher initial heart rate, and was more often accompanied by a further increase in heart rate than early ischaemia. Thus in the first 2 months after myocardial infarction transient ischaemia became increasingly common and more closely associated with increased myocardial oxygen demand. Because transient ischaemic episodes during early and late ambulatory monitoring have dissimilar characteristics they may also have different pathophysiologies and prognostic implications. PMID:2245108

  4. Leptin Integrates Vertebrate Evolution: from Oxygen to the Blood-Gas Barrier

    PubMed Central

    Torday, J.S.; Powell, F.L.; Farmer, C.G.; Orgeig, S.; Nielsen, H.C.; Hall, A.J.

    2014-01-01

    The following are the proceedings of a symposium held at the Second International Congress for Respiratory Science in Bad Honnef, Germany. The goals of the symposium were to delineate the blood-gas barrier phenotype across vertebrate species; to delineate the interrelationship between the evolution of the blood-gas barrier, locomotion and metabolism; to introduce the selection pressures for the evolution of the surfactant system as a key to understanding the physiology of the blood-gas barrier; to introduce the lung lipofibroblast and its product, leptin, which coordinately regulates pulmonary surfactant, type IV collagen in the basement membrane and host defense, as the cell-molecular site of selection pressure for the blood-gas barrier; to drill down to the gene regulatory network(s) involved in leptin signaling and the blood-gas barrier phenotype; to extend the relationship between leptin and the blood-gas-barrier to diving mammals. PMID:20096383

  5. Associations among hemorheological factors and maximal oxygen consumption. Is there a role for blood viscosity in explaining athletic performance?

    PubMed

    Smith, Michael M; Lucas, Alexander R; Hamlin, Robert L; Devor, Steven T

    2015-01-01

    This study examined the relationship between hematocrit, blood viscosity, plasma viscosity, erythrocyte deformability, and fibrinogen concentration during maximal oxygen uptake in aerobically trained (AT) and resistance trained (RT) athletes. Maximal oxygen uptake was assessed using a Bruce graded exercise treadmill test to exhaustion, and blood samples were collected at rest and immediately following exercise using a venous catheter. Viscometric analyses were performed using a cone and plate viscometer at varying shear rates. Hematocrit was measured as the fraction of erythrocytes suspended in plasma following centrifugation. Erythrocyte rigidity was estimated using the Dintenfass index of red blood cell rigidity. Following maximal treadmill exercise, an increase of blood viscosity at varying shear rates (22.50, 45.00, 90.00, and 225.00 s- 1; P <  0.05) was observed in RT athletes only. Plasma viscosity @ 225.00 s- 1 (1.88 ± 0.09 vs. 1.78 ± 0.03 mPa.s; P <  0.05), erythrocyte rigidity (0.52 ± 0.08 vs. 0.40 ± 0.09; P <  0.05), and plasma fibrinogen (434 ± 7 vs. 295 ± 25 mg/dL; P <  0.01) were all significantly greater in RT than AT athletes following maximal exercise. In summary, AT, but not RT, is associated with a hemorheological profile that promotes both oxygen transport and delivery. The results indicate that hematocrit alone should not be the focus of training and ergogenic supplementation to increase aerobic performance. PMID:23514971

  6. Synergy between shear-induced migration and secondary flows on red blood cells transport in arteries: considerations on oxygen transport.

    PubMed

    Biasetti, Jacopo; Spazzini, Pier Giorgio; Hedin, Ulf; Gasser, T Christian

    2014-08-01

    Shear-induced migration of red blood cells (RBCs) is a well-known phenomenon characterizing blood flow in the small vessels (micrometre to millimetre size) of the cardiovascular system. In large vessels, like the abdominal aorta and the carotid artery (millimetre to centimetre size), the extent of this migration and its interaction with secondary flows has not been fully elucidated. RBC migration exerts its influence primarily on platelet concentration, oxygen transport and oxygen availability at the luminal surface, which could influence vessel wall disease processes in and adjacent to the intima. Phillips' shear-induced particle migration model, coupled to the Quemada viscosity model, was employed to simulate the macroscopic behaviour of RBCs in four patient-specific geometries: a normal abdominal aorta, an abdominal aortic aneurysm (AAA), a normal carotid bifurcation and a stenotic carotid bifurcation. Simulations show a migration of RBCs from the near-wall region with a lowering of wall haematocrit (volume fraction of RBCs) on the posterior side of the normal aorta and on the lateral-external side of the iliac arteries. A marked migration is observed on the outer wall of the carotid sinus, along the common carotid artery and in the carotid stenosis. No significant migration is observed in the AAA. The spatial and temporal patterns of wall haematocrit are correlated with the near-wall shear layer and with the secondary flows induced by the vessel curvature. In particular, secondary flows accentuate the initial lowering in RBC near-wall concentration by convecting RBCs from the inner curvature side to the outer curvature side. The results reinforce data in literature showing a decrease in oxygen partial pressure on the inner curvature wall of the carotid sinus induced by the presence of secondary flows. The lowering of wall haematocrit is postulated to induce a decrease in oxygen availability at the luminal surface through a diminished concentration of

  7. Synergy between shear-induced migration and secondary flows on red blood cells transport in arteries: considerations on oxygen transport

    PubMed Central

    Biasetti, Jacopo; Spazzini, Pier Giorgio; Hedin, Ulf; Gasser, T. Christian

    2014-01-01

    Shear-induced migration of red blood cells (RBCs) is a well-known phenomenon characterizing blood flow in the small vessels (micrometre to millimetre size) of the cardiovascular system. In large vessels, like the abdominal aorta and the carotid artery (millimetre to centimetre size), the extent of this migration and its interaction with secondary flows has not been fully elucidated. RBC migration exerts its influence primarily on platelet concentration, oxygen transport and oxygen availability at the luminal surface, which could influence vessel wall disease processes in and adjacent to the intima. Phillips' shear-induced particle migration model, coupled to the Quemada viscosity model, was employed to simulate the macroscopic behaviour of RBCs in four patient-specific geometries: a normal abdominal aorta, an abdominal aortic aneurysm (AAA), a normal carotid bifurcation and a stenotic carotid bifurcation. Simulations show a migration of RBCs from the near-wall region with a lowering of wall haematocrit (volume fraction of RBCs) on the posterior side of the normal aorta and on the lateral-external side of the iliac arteries. A marked migration is observed on the outer wall of the carotid sinus, along the common carotid artery and in the carotid stenosis. No significant migration is observed in the AAA. The spatial and temporal patterns of wall haematocrit are correlated with the near-wall shear layer and with the secondary flows induced by the vessel curvature. In particular, secondary flows accentuate the initial lowering in RBC near-wall concentration by convecting RBCs from the inner curvature side to the outer curvature side. The results reinforce data in literature showing a decrease in oxygen partial pressure on the inner curvature wall of the carotid sinus induced by the presence of secondary flows. The lowering of wall haematocrit is postulated to induce a decrease in oxygen availability at the luminal surface through a diminished concentration of

  8. Myocardial blood flow measurement with a conventional dual-head SPECT/CT with spatiotemporal iterative reconstructions - a clinical feasibility study

    PubMed Central

    Alhassen, Fares; Nguyen, Nhan; Bains, Sukhkarn; Gould, Robert G; Seo, Youngho; Bacharach, Stephen L; Song, Xiyun; Shao, Lingxiong; Gullberg, Grant T; Aparici, Carina Mari

    2014-01-01

    Cardiac single photon emission computed tomography (SPECT) cameras typically rotate too slowly around a patient to capture changes in the blood pool activity distribution and provide accurate kinetic parameters. A spatiotemporal iterative reconstruction method to overcome these limitations was investigated. Dynamic rest/stress 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) SPECT/CT was performed along with reference standard rest/stress dynamic positron emission tomography (PET/CT) 13N-NH3 in five patients. The SPECT data were reconstructed using conventional and spatiotemporal iterative reconstruction methods. The spatiotemporal reconstruction yielded improved image quality, defined here as a statistically significant (p<0.01) 50% contrast enhancement. We did not observe a statistically significant difference between the correlations of the conventional and spatiotemporal SPECT myocardial uptake K 1 values with PET K 1 values (r=0.25, 0.88, respectively) (p<0.17). These results indicate the clinical feasibility of quantitative, dynamic SPECT/CT using 99mTc-MIBI and warrant further investigation. Spatiotemporal reconstruction clearly provides an advantage over a conventional reconstruction in computing K 1. PMID:24380045

  9. Cerebral blood flow and oxygenation in ovine fetus: responses to superimposed hypoxia at both low and high altitude

    PubMed Central

    Peňa, Jorge Pereyra; Tomimatsu, Takuji; Hatran, Douglas P; McGill, Lisa L; Longo, Lawrence D

    2007-01-01

    For the fetus, although the roles of arterial blood gases are recognized to be critical in the regulation of cerebral blood flow (CBF) and cerebral oxygenation, the relation of CBF, cortical tissue PO2 (t PO2), sagittal sinus PO2, and related indices of cerebral oxygenation to arterial blood gases are not well defined. This is particularly true for that fetus subjected to long-term hypoxia (LTH). In an effort to elucidate these interrelations, we tested the hypothesis that in the fetus acclimatized to high altitude, cerebral oxygenation is not compromised relative to that at low altitude. By use of a laser Doppler flowmeter with a fluorescent O2 probe, in near-term fetal sheep at low altitude (n = 8) and those acclimatized to high altitude hypoxia (3801 m for 90 ± 5 days; n = 6), we measured laser Doppler CBF (LD-CBF), t PO2, and related variables in response to 40 min superimposed hypoxia. At both altitudes, fetal LD-CBF, cerebral O2 delivery, t PO2, and several other variables including sagittal sinus PO2, correlated highly with arterial PO2 (Pa,O2). In response to superimposed hypoxia (Pa,O2 = 11 ± 1 Torr), LD-CBF was significantly blunted at high altitude, as compared with that at low altitude. In the two altitude groups fetal cerebral oxygenation was similar under both control conditions and with superimposed hypoxia, cortical t PO2 decreasing from 8 ± 1 and 6 ± 1 Torr, respectively, to 2 ± 1 Torr. Also, for these conditions sagittal sinus PO2 and [HbO2] values were similar. In response to superimposed hypoxia, cerebral metabolic rate for O2 decreased ∼50% in each group (P < 0.05). For both the fetus at low altitude and that acclimatized to high altitude LTH, we present the first dose–response data on the relation of LD-CBF, cortical t PO2, and sagittal sinus blood gas values to Pa,O2. In addition, despite differences in several variables, the fetus at high altitude showed evidence of successful acclimatization, supporting the hypothesis that such

  10. Coupling of cerebral blood flow and oxygen metabolism is conserved for chromatic and luminance stimuli in human visual cortex.

    PubMed

    Leontiev, Oleg; Buracas, Giedrius T; Liang, Christine; Ances, Beau M; Perthen, Joanna E; Shmuel, Amir; Buxton, Richard B

    2013-03-01

    The ratio of the changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO(2)) during brain activation is a critical determinant of the magnitude of the blood oxygenation level dependent (BOLD) response measured with functional magnetic resonance imaging (fMRI). Cytochrome oxidase (CO), a key component of oxidative metabolism in the mitochondria, is non-uniformly distributed in visual area V1 in distinct blob and interblob regions, suggesting significant spatial variation in the capacity for oxygen metabolism. The goal of this study was to test whether CBF/CMRO(2) coupling differed when these subpopulations of neurons were preferentially stimulated, using chromatic and luminance stimuli to preferentially stimulate either the blob or interblob regions. A dual-echo spiral arterial spin labeling (ASL) technique was used to measure CBF and BOLD responses simultaneously in 7 healthy human subjects. When the stimulus contrast levels were adjusted to evoke similar CBF responses (mean 65.4% ± 19.0% and 64.6% ± 19.9%, respectively for chromatic and luminance contrast), the BOLD responses were remarkably similar (1.57% ± 0.39% and 1.59% ± 0.35%) for both types of stimuli. We conclude that CBF-CMRO(2) coupling is conserved for the chromatic and luminance stimuli used, suggesting a consistent coupling for blob and inter-blob neuronal populations despite the difference in CO concentration. PMID:23238435

  11. The effect of in-plane arterial curvature on blood flow and oxygen transport in arterio-venous fistulae

    PubMed Central

    Iori, F.; Grechy, L.; Gedroyc, W.; Duncan, N.; Caro, C. G.; Vincent, P. E.

    2015-01-01

    Arterio-Venous Fistulae (AVF) are the preferred method of vascular access for patients with end stage renal disease who need hemodialysis. In this study, simulations of blood flow and oxygen transport were undertaken in various idealized AVF configurations. The objective of the study was to understand how arterial curvature affects blood flow and oxygen transport patterns within AVF, with a focus on how curvature alters metrics known to correlate with vascular pathology such as Intimal Hyperplasia (IH). If one subscribes to the hypothesis that unsteady flow causes IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto the outer-curvature of a curved artery. However, if one subscribes to the hypothesis that low wall shear stress and/or low lumen-to-wall oxygen flux (leading to wall hypoxia) cause IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto a straight artery, or the inner-curvature of a curved artery. We note that the recommendations are incompatible—highlighting the importance of ascertaining the exact mechanisms underlying development of IH in AVF. Nonetheless, the results clearly illustrate the important role played by arterial curvature in determining AVF hemodynamics, which to our knowledge has been overlooked in all previous studies. PMID:25829837

  12. Effects of growth, diving history, and high altitude on blood oxygen capacity in harbor seals

    NASA Technical Reports Server (NTRS)

    Kodama, A. M.; Elsner, R.; Pace, N.

    1977-01-01

    Blood volume and body composition for diving and nondiving harbor seals were measured at six-week intervals during a 10-month period of captitivity. Whole body hematocrit, red cell volume per kg of lean body mass, and total circulating hemoglobin per kg lean body mass were significantly higher in the diving group, but relatively large blood volumes expressed in terms of body weight (11-12%) were found in both groups. A pair of harbor seals exposed to high altitude for about three months registered significant increases in red cell volume, blood hemoglobin levels, and blood volume expressed in terms of body weight; results of alveolar gas analyses indicate that hyperventilation also occurred. These typical mammalian responses to hypoxia suggest that the harbor seal's large blood volume and high hemoglobin content are an expression of phylogenetic control, and that in spite of its adaptability to apnea during its diving life, the animal cannot be considered preacclimatized to high altitude.

  13. COMPARATIVE ANALYSIS OF REACTIVE OXYGEN SPECIES IN HUMAN PLASMA AND BLOOD

    EPA Science Inventory

    Reactive oxygen species (ROS) are commonly associated with diseased states (including asthma, cardiovascular disease, cancer) infections, and exposure to various toxicants in humans. It is of interest in epidemiology studies to characterize the association of oxidative stress in...

  14. Skin blood flow differentially affects near-infrared spectroscopy-derived measures of muscle oxygen saturation and blood volume at rest and during dynamic leg exercise.

    PubMed

    Tew, Garry A; Ruddock, Alan D; Saxton, John M

    2010-11-01

    The impact of skin blood flow changes on near-infrared spectroscopy (NIRS)-derived measures of muscle oxygen saturation (SmO(2)) and blood volume has not been fully established. We measured SmO(2) and total hemoglobin concentration ([tHb]) responses of the right vastus lateralis during rest and dynamic knee extension exercise in ten young, healthy males. The protocol was repeated four times: twice without thigh heating for reliability, and twice with different grades of thigh heating for assessing the impact of cutaneous vasodilation on SmO(2) and Δ[tHb]. The reliability of our SmO(2) and [tHb] measurements was good. Thigh heating at 37 and 42°C caused marked increases in cutaneous vascular conductance (CVC) during rest and exercise (P < 0.001 between each condition), and small increases in SmO(2) during rest (from 69 ± 8% to 71 ± 7% and 73 ± 6%, respectively; P < 0.05 between each condition), but not during exercise (e.g. 1 min exercise: 51 ± 11% vs. 51 ± 11% and 52 ± 11%, respectively; P > 0.05 at all time points). In contrast, heating-induced increases in %CVC(peak) were accompanied by increases in [tHb] at rest and during exercise and a decrease in Δ[tHb] during exercise (all P < 0.05). Our findings suggest that NIRS-derived measures of SmO(2) and blood volume are differentially affected by skin blood flow at rest and during exercise. The findings from this study should be considered in NIRS experiments where skin blood flow can change markedly (e.g. high-intensity and/or prolonged exercise). PMID:20700602

  15. Influence of passive stretch on muscle blood flow, oxygenation and central cardiovascular responses in healthy young males.

    PubMed

    Kruse, Nicholas T; Silette, Christopher R; Scheuermann, Barry W

    2016-05-01

    The aim of this study was to examine the effect of skeletal muscle stretching on peripheral, central, and autonomic cardiovascular responses in humans. Twelve healthy males completed a controlled passive stretch of the plantar flexors for 4 min at three different intensities. Doppler ultrasound velocimetry and imaging techniques assessed mean leg blood flow (MLBF), antegrade blood flow, and retrograde blood flow of the popliteal artery. Near-infrared spectroscopy assessed the concentration of deoxygenated hemoglobin + myoglobin ([HHb]) and the sum of its deoxygenated and oxygenated forms [i.e., blood volume ([Hbtot])]. Heart rate (HR) and mean arterial pressure were measured simultaneously to peripheral hemodynamic responses. During stretch there was an increase (P < 0.05) in antegrade and retrograde blood flow along with [HHb] and [Hbtot] relative to baseline, whereas MLBF was not altered. HR increased (P < 0.01) in a stretch intensity- and time-dependent manner, suggesting a threshold tension must be met that results in a mechanoreflex-mediated increase in HR. After stretch there was an increase (P < 0.05) in [Hbtot] and MLBF in each condition, suggesting that stretch creates a poststretch hyperemic response. Furthermore, retrograde blood flow was decreased (P < 0.05) after stretch in each stretch condition. Mean arterial pressure was decreased (P < 0.05) after moderate-intensity stretching. Collectively, our data provide novel mechanistic evidence on cardiovascular responses to skeletal muscle stretching in humans. Moreover, the reductions in MAP and retrograde blood flow suggest that stretch transiently reduces myogenic vascular tone in a poststretch resting period. PMID:26945077

  16. Relationship of efficiency indices with performance, heart rate, oxygen consumption, blood parameters, and estimated heat production in Nellore steers.

    PubMed

    Chaves, A S; Nascimento, M L; Tullio, R R; Rosa, A N; Alencar, M M; Lanna, D P

    2015-10-01

    The objective of this study was to examine the relationship of efficiency indices with performance, heart rate, oxygen consumption, blood parameters, and estimated heat production (EHP) in Nellore steers. Eighteen steers were individually lot-fed diets of 2.7 Mcal ME/kg DM for 84 d. Estimated heat production was determined using oxygen pulse (OP) methodology, in which heart rate (HR) was monitored for 4 consecutive days. Oxygen pulse was obtained by simultaneously measuring HR and oxygen consumption during a 10- to 15-min period. Efficiency traits studied were feed efficiency (G:F) and residual feed intake (RFI) obtained by regression of DMI in relation to ADG and midtest metabolic BW (RFI). Alternatively, RFI was also obtained based on equations reported by the NRC's to estimate individual requirement and DMI (RFI calculated by the NRC [1996] equation [RFI]). The slope of the regression equation and its significance was used to evaluate the effect of efficiency indices (RFI, RFI, or G:F) on the traits studied. A mixed model was used considering RFI, RFI, or G:F and pen type as fixed effects and initial age as a covariate. For HR and EHP variables, day was included as a random effect. There was no relationship between efficiency indices and back fat depth measured by ultrasound or daily HR and EHP ( > 0.05). Because G:F is obtained in relation to BW, the slope of G:F was positive and significant ( < 0.05). Regardless of the method used, efficient steers had lower DMI ( < 0.05). The initial LM area was indirectly related to RFI and RFI ( < 0.05); however, the final muscle area was related to only RFI. Oxygen consumption per beat was not related to G:F; however, it was lower for RFI- and RFI-efficient steers, and consequently, oxygen volume (mL·min·kg) and OP (μL O·beat·kg) were also lower ( < 0.05). Blood parameters were not related to RFI and RFI ( > 0.05); however, G:F-efficient steers showed lower hematocrit and hemoglobin concentrations ( < 0

  17. Activity-induced tissue oxygenation changes in rat cerebellar cortex: interplay of postsynaptic activation and blood flow

    PubMed Central

    Offenhauser, Nikolas; Thomsen, Kirsten; Caesar, Kirsten; Lauritzen, Martin

    2005-01-01

    Functional neuroimaging relies on the robust coupling between neuronal activity, metabolism and cerebral blood flow (CBF), but the physiological basis of the neuroimaging signals is still poorly understood. We examined the mechanisms of activity-dependent changes in tissue oxygenation in relation to variations in CBF responses and postsynaptic activity in rat cerebellar cortex. To increase synaptic activity we stimulated the monosynaptic, glutamatergic climbing fibres that excite Purkinje cells via AMPA receptors. We used local field potentials to indicate synaptic activity, and recorded tissue oxygen partial pressure (Ptiss,O2) by polarographic microelectrodes, and CBF using laser-Doppler flowmetry. The disappearance rate of oxygen in the tissue increased linearly with synaptic activity. This indicated that, without a threshold, oxygen consumption increased as a linear function of synaptic activity. The reduction in Ptiss,O2 preceded the rise in CBF. The time integral (area) of the negative Ptiss,O2 response increased non-linearly showing saturation at high levels of synaptic activity, concomitant with a steep rise in CBF. This was accompanied by a positive change in Ptiss,O2. Neuronal nitric oxide synthase inhibition enhanced the initial negative Ptiss,O2 response (‘dip’), while attenuating the evoked CBF increase and positive Ptiss,O2 response equally. This indicates that increases in CBF counteract activity-induced reductions in Ptiss,O2, and suggests the presence of a tissue oxygen reserve. The changes in Ptiss,O2 and CBF were strongly attenuated by AMPA receptor blockade. Our findings suggest an inverse relationship between negative Ptiss,O2 and CBF responses, and provide direct in vivo evidence for a tight coupling between activity in postsynaptic AMPA receptors and cerebellar oxygen consumption. PMID:15774524

  18. In vivo differentiation of human amniotic epithelial cells into cardiomyocyte-like cells and cell transplantation effect on myocardial infarction in rats: comparison with cord blood and adipose tissue-derived mesenchymal stem cells.

    PubMed

    Fang, Cheng-Hu; Jin, Jiyong; Joe, Jun-Ho; Song, Yi-Sun; So, Byung-Im; Lim, Sang Moo; Cheon, Gi Jeong; Woo, Sang-Keun; Ra, Jeong-Chan; Lee, Young-Yiul; Kim, Kyung-Soo

    2012-01-01

    Human amniotic epithelial cells (h-AECs), which have various merits as a cell source for cell therapy, are known to differentiate into cardiomyocytes in vitro. However, the ability of h-AECs to differentiate into cardiomyocytes in vivo and their cell transplantation effects on myocardial infarction are still unknown. In this study, we assessed whether h-AECs could differentiate into cardiomyocytes in vivo and whether h-AECs transplantation can decrease infarct size and improve cardiac function, in comparison to transplantation of cord blood-derived mesenchymal stem cells (MSCs) or adipose tissue-derived MSCs. For our study, we injected h-AECs, cord blood-derived MSCs, adipose tissue-derived MSCs, and saline into areas of myocardial infarction in athymic nude rats. After 4 weeks, 3% of the surviving h-AECs expressed myosin heavy chain, a marker specific to the myocardium. Compared with the saline group, all cell-implanted groups showed a higher ejection fraction, lower infarct area by positron emission tomography and histology, and more abundant myocardial gene and protein expression in the infarct area. We showed that h-AECs can differentiate into cardiomyocyte-like cells, decrease infarct size, and improve cardiac function in vivo. The beneficial effects of h-AECs were comparable to those of cord blood and adipose tissue-derived MSCs. These results support the need for further studies of h-AECs as a cell source for myocardial regeneration due to their plentiful availability, low immunity, and lack of ethical issues related to their use. PMID:22776022

  19. High impact of uranyl ions on carrying-releasing oxygen capability of hemoglobin-based blood substitutes.

    PubMed

    Duan, Li; Du, Lili; Jia, Yi; Liu, Wenyuan; Liu, Zhichao; Li, Junbai

    2015-01-01

    The effect of radioactive UO2 (2+) on the oxygen-transporting capability of hemoglobin-based oxygen carriers has been investigated in vitro. The hemoglobin (Hb) microspheres fabricated by the porous template covalent layer-by-layer (LbL) assembly were utilized as artificial oxygen carriers and blood substitutes. Magnetic nanoparticles of iron oxide (Fe3 O4 ) were loaded in porous CaCO3 particles for magnetically assisted chemical separation (MACS). Through the adsorption spectrum of magnetic Hb microspheres after adsorbing UO2 (2+) , it was found that UO2 (2+) was highly loaded in the magnetic Hb microspheres, and it shows that the presence of UO2 (2+) in vivo destroys the structure and oxygen-transporting capability of Hb microspheres. In view of the high adsorption capacity of UO2 (2+) , the as-assembled magnetic Hb microspheres can be considered as a novel, highly effective adsorbent for removing metal toxins from radiation-contaminated bodies, or from nuclear-power reactor effluent before discharge into the environment. PMID:25418690

  20. Effects of Antioxidant Supplements (BioPQQ™) on Cerebral Blood Flow and Oxygen Metabolism in the Prefrontal Cortex.

    PubMed

    Nakano, Masahiko; Murayama, Yuta; Hu, Lizhen; Ikemoto, Kazuto; Uetake, Tatsuo; Sakatani, Kaoru

    2016-01-01

    Pyrroloquinoline quinone (PQQ) is a quinone compound originally identified in methanol-utilizing bacteria and is a cofactor for redox enzymes. At the Meeting of the International Society on Oxygen Transport to Tissue (ISOTT) 2014, we reported that PQQ disodium salt (BioPQQ™) improved cognitive function in humans, as assessed by the Stroop test. However, the physiological mechanism of PQQ remains unclear. In the present study, we measured regional cerebral blood flow (rCBF) and oxygen metabolism in prefrontal cortex (PFC), before and after administration of PQQ, using time-resolved near-infrared spectroscopy (tNIRS). A total of 20 healthy subjects between 50 and 70 years of age were administered BioPQQ™ (20 mg) or placebo orally once daily for 12 weeks. Hemoglobin (Hb) concentration and absolute tissue oxygen saturation (SO2) in the bilateral PFC were evaluated under resting conditions using tNIRS. We found that baseline concentrations of hemoglobin and total hemoglobin in the right PFC significantly increased after administration of PQQ (p < 0.05). In addition, decreases in SO2 level in the PFC were more pronounced in the PQQ group than in the placebo group (p < 0.05). These results suggest that PQQ causes increased activity in the right PFC associated with increases in rCBF and oxygen metabolism, resulting in enhanced cognitive function. PMID:27526146

  1. “Overshoot” of O2 is required to maintain baseline tissue oxygenation at locations distal to blood vessels

    PubMed Central

    Devor, Anna; Sakadžić, Sava; Saisan, Payam A.; Yaseen, Mohammad A.; Roussakis, Emmanuel; Srinivasan, Vivek J.; Vinogradov, Sergei A.; Rosen, Bruce R.; Buxton, Richard B.; Dale, Anders M.; Boas, David A.

    2011-01-01

    In vivo imaging of cerebral tissue oxygenation is of key importance in defining healthy physiology and pathological departures associated with cerebral disease. We used a recently developed two-photon microscopy method, based on a novel phosphorescent nanoprobe, to image tissue oxygenation in the rat primary sensory cortex (SI) in response to sensory stimulation. Our measurements showed that a stimulus-evoked increase in tissue pO2 depended on the baseline pO2 level. In particular, during sustained stimulation, the steady-state pO2 at low-baseline locations remained at the baseline, despite large pO2 increases elsewhere. In contrast to the steady state, where pO2 never decreased below the baseline, transient decreases occurred during the “initial dip” and “post-stimulus undershoot.” These results suggest that the increase in blood oxygenation during the hemodynamic response, which has been perceived as a paradox, may serve to prevent a sustained oxygenation drop at tissue locations remote from the vascular feeding sources. PMID:21940458

  2. Megalophallus as a sequela of priapism in sickle cell anemia: use of blood oxygen level-dependent magnetic resonance imaging.

    PubMed

    Kassim, A A; Umans, H; Nagel, R L; Fabry, M E

    2000-09-01

    Priapism is a common complication of sickle cell anemia. We report a little known sequela of priapism: painless megalophallus, with significant penile enlargement. The patient had had an intense episode of priapism 9 years previously and his penis remained enlarged. Blood oxygen level-dependent magnetic resonance imaging revealed enlarged, hypoxic corpora cavernosa. Megalophallus probably resulted from permanent loss of elasticity of the tunica albuginea due to severe engorgement during the episode of priapism. This sequela needs to be recognized by physicians because no intervention is necessary and sexual function seems to remain intact. PMID:10962334

  3. Skeletal muscle blood flow and oxygen uptake at rest and during exercise in humans: a pet study with nitric oxide and cyclooxygenase inhibition.

    PubMed

    Heinonen, Ilkka; Ilkka, Heinonen; Saltin, Bengt; Bengt, Saltin; Kemppainen, Jukka; Jukka, Kemppainen; Sipilä, Hannu T; Oikonen, Vesa; Vesa, Oikonen; Nuutila, Pirjo; Pirjo, Nuutila; Knuuti, Juhani; Juhani, Knuuti; Kalliokoski, Kari; Kari, Kalliokoski; Hellsten, Ylva; Ylva, Hellsten

    2011-04-01

    The aim of the present study was to determine the effect of nitric oxide and prostanoids on microcirculation and oxygen uptake, specifically in the active skeletal muscle by use of positron emission tomography (PET). Healthy males performed three 5-min bouts of light knee-extensor exercise. Skeletal muscle blood flow and oxygen uptake were measured at rest and during the exercise using PET with H(2)O(15) and (15)O(2) during: 1) control conditions; 2) nitric oxide synthase (NOS) inhibition by arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA), and 3) combined NOS and cyclooxygenase (COX) inhibition by arterial infusion of L-NMMA and indomethacin. At rest, inhibition of NOS alone and in combination with indomethacin reduced (P < 0.05) muscle blood flow. NOS inhibition increased (P < 0.05) limb oxygen extraction fraction (OEF) more than the reduction in muscle blood flow, resulting in an ∼20% increase (P < 0.05) in resting muscle oxygen consumption. During exercise, muscle blood flow and oxygen uptake were not altered with NOS inhibition, whereas muscle OEF was increased (P < 0.05). NOS and COX inhibition reduced (P < 0.05) blood flow in working quadriceps femoris muscle by 13%, whereas muscle OEF and oxygen uptake were enhanced by 51 and 30%, respectively. In conclusion, by specifically measuring blood flow and oxygen uptake by the use of PET instead of whole limb measurements, the present study shows for the first time in humans that inhibition of NO formation enhances resting muscle oxygen uptake and that combined inhibition of NOS and COX during exercise increases muscle oxygen uptake. PMID:21257921

  4. Specificity of Compensatory Reserve and Tissue Oxygenation as Early Predictors of Tolerance to Progressive Reductions in Central Blood Volume.

    PubMed

    Howard, Jeffrey T; Janak, Jud C; Hinojosa-Laborde, Carmen; Convertino, Victor A

    2016-09-01

    We previously reported that measurements of muscle oxygen saturation (SmO2) and the compensatory reserve index (CRI) provided earlier indication of reduced central blood volume than standard vital signs (e.g., blood pressure, heart rate, arterial oxygen saturation). In the present study, we hypothesized that the CRI would provide greater sensitivity and specificity to detect progressive decrease in central circulating blood volume compared with SmO2. Continuous noninvasive measures of CRI (calculated from feature changes in the photoplethysmographic arterial waveforms) were collected from 55 healthy volunteer subjects before and during stepwise lower body negative pressure (LBNP) to the onset of hemodynamic decompensation. Near infrared spectroscopy was used on the forearm to obtain deep SmO2, hydrogen ion concentration ([H]), and hemoglobin volume (HbT; decreases reflect vasoconstriction). CRI decreased by 97% in a linear fashion across progressive blood volume loss, with no clinically significant alterations in vital signs. The receiver operating characteristic (ROC) area under the curve (AUC) for the CRI was 0.91, with a sensitivity of 0.87 and specificity of 0.80, when predicting decompensation at progressive levels of LBNP. In comparison, SmO2, [H], and HbT had significantly lower ROC AUC, sensitivity and specificity values for detecting the same outcome. Consistent with our hypothesis, CRI detected central hypovolemia with significantly greater specificity than measures of tissue metabolism. Single measurement of CRI may enable more accurate triage, while CRI monitoring may allow for earlier detection of casualty deterioration. PMID:27058052

  5. Acute supplementation of N-acetylcysteine does not affect muscle blood flow and oxygenation characteristics during handgrip exercise.

    PubMed

    Smith, Joshua R; Broxterman, Ryan M; Ade, Carl J; Evans, Kara K; Kurti, Stephanie P; Hammer, Shane M; Barstow, Thomas J; Harms, Craig A

    2016-04-01

    N-acetylcysteine (NAC; antioxidant and thiol donor) supplementation has improved exercise performance and delayed fatigue, but the underlying mechanisms are unknown. One possibility isNACsupplementation increases limb blood flow during severe-intensity exercise. The purpose was to determine ifNACsupplementation affected exercising arm blood flow and muscle oxygenation characteristics. We hypothesized thatNACwould lead to higher limb blood flow and lower muscle deoxygenation characteristics during severe-intensity exercise. Eight healthy nonendurance trained men (21.8 ± 1.2 years) were recruited and completed two constant power handgrip exercise tests at 80% peak power until exhaustion. Subjects orally consumed either placebo (PLA) orNAC(70 mg/kg) 60 min prior to handgrip exercise. Immediately prior to exercise, venous blood samples were collected for determination of plasma redox balance. Brachial artery blood flow (BABF) was measured via Doppler ultrasound and flexor digitorum superficialis oxygenation characteristics were measured via near-infrared spectroscopy. FollowingNACsupplementaiton, plasma cysteine (NAC: 47.2 ± 20.3 μmol/L vs.PLA: 9.6 ± 1.2 μmol/L;P = 0.001) and total cysteine (NAC: 156.2 ± 33.9 μmol/L vs.PLA: 132.2 ± 16.3 μmol/L;P = 0.048) increased. Time to exhaustion was not significantly different (P = 0.55) betweenNAC(473.0 ± 62.1 sec) andPLA(438.7 ± 58.1 sec). RestingBABFwas not different (P = 0.79) withNAC(99.3 ± 31.1 mL/min) andPLA(108.3 ± 46.0 mL/min).BABFwas not different (P = 0.42) during exercise or at end-exercise (NAC: 413 ± 109 mL/min;PLA: 445 ± 147 mL/min). Deoxy-[hemoglobin+myoglobin] and total-[hemoglobin+myoglobin] were not significantly different (P = 0.73 andP = 0.54, respectively) at rest or during exercise between conditions. We conclude that acuteNACsupplementation does not alter oxygen delivery during exercise in men. PMID:27044854

  6. Blood oxygen depletion is independent of dive function in a deep diving vertebrate, the northern elephant seal.

    PubMed

    Meir, Jessica U; Robinson, Patrick W; Vilchis, L Ignacio; Kooyman, Gerald L; Costa, Daniel P; Ponganis, Paul J

    2013-01-01

    Although energetics is fundamental to animal ecology, traditional methods of determining metabolic rate are neither direct nor instantaneous. Recently, continuous blood oxygen (O2) measurements were used to assess energy expenditure in diving elephant seals (Mirounga angustirostris), demonstrating that an exceptional hypoxemic tolerance and exquisite management of blood O2 stores underlie the extraordinary diving capability of this consummate diver. As the detailed relationship of energy expenditure and dive behavior remains unknown, we integrated behavior, ecology, and physiology to characterize the costs of different types of dives of elephant seals. Elephant seal dive profiles were analyzed and O2 utilization was classified according to dive type (overall function of dive: transit, foraging, food processing/rest). This is the first account linking behavior at this level with in vivo blood O2 measurements in an animal freely diving at sea, allowing us to assess patterns of O2 utilization and energy expenditure between various behaviors and activities in an animal in the wild. In routine dives of elephant seals, the blood O2 store was significantly depleted to a similar range irrespective of dive function, suggesting that all dive types have equal costs in terms of blood O2 depletion. Here, we present the first physiological evidence that all dive types have similarly high blood O2 demands, supporting an energy balance strategy achieved by devoting one major task to a given dive, thereby separating dive functions into distinct dive types. This strategy may optimize O2 store utilization and recovery, consequently maximizing time underwater and allowing these animals to take full advantage of their underwater resources. This approach may be important to optimizing energy expenditure throughout a dive bout or at-sea foraging trip and is well suited to the lifestyle of an elephant seal, which spends > 90% of its time at sea submerged making diving its most "natural

  7. Blood Oxygen Depletion Is Independent of Dive Function in a Deep Diving Vertebrate, the Northern Elephant Seal

    PubMed Central

    Meir, Jessica U.; Robinson, Patrick W.; Vilchis, L. Ignacio; Kooyman, Gerald L.; Costa, Daniel P.; Ponganis, Paul J.

    2013-01-01

    Although energetics is fundamental to animal ecology, traditional methods of determining metabolic rate are neither direct nor instantaneous. Recently, continuous blood oxygen (O2) measurements were used to assess energy expenditure in diving elephant seals (Mirounga angustirostris), demonstrating that an exceptional hypoxemic tolerance and exquisite management of blood O2 stores underlie the extraordinary diving capability of this consummate diver. As the detailed relationship of energy expenditure and dive behavior remains unknown, we integrated behavior, ecology, and physiology to characterize the costs of different types of dives of elephant seals. Elephant seal dive profiles were analyzed and O2 utilization was classified according to dive type (overall function of dive: transit, foraging, food processing/rest). This is the first account linking behavior at this level with in vivo blood O2 measurements in an animal freely diving at sea, allowing us to assess patterns of O2 utilization and energy expenditure between various behaviors and activities in an animal in the wild. In routine dives of elephant seals, the blood O2 store was significantly depleted to a similar range irrespective of dive function, suggesting that all dive types have equal costs in terms of blood O2 depletion. Here, we present the first physiological evidence that all dive types have similarly high blood O2 demands, supporting an energy balance strategy achieved by devoting one major task to a given dive, thereby separating dive functions into distinct dive types. This strategy may optimize O2 store utilization and recovery, consequently maximizing time underwater and allowing these animals to take full advantage of their underwater resources. This approach may be important to optimizing energy expenditure throughout a dive bout or at-sea foraging trip and is well suited to the lifestyle of an elephant seal, which spends > 90% of its time at sea submerged making diving its most

  8. Theoretical considerations to optimize transabdominal monitoring of fetal arterial blood oxygenation using pulse oximetry

    NASA Astrophysics Data System (ADS)

    Zourabian, Anna; Boas, David A.

    2001-06-01

    Pulse oximetry (oxygen saturation monitoring) has markedly improved medical care in many fields, including anesthesiology, intensive care, and newborn intensive care. In obstetrics, fetal heart rate monitoring remains the standard for intrapartum assessment of fetal well being. Fetal oxygen saturation monitoring is a new technique currently under development. It is potentially superior to electronic fetal heart rate monitoring (cardiotocography) because it allows direct assessment of both fetal oxygen status and fetal tissue perfusion. Here we present the analysis for determining the most optimal wavelength selection for pulse oximetry. The wavelengths we chose as the most optimal are: the first in the range of 670-720nm and the second in the range of 825-925nm. Further we discuss the possible systematic errors during our measurements, and their contribution to the obtained saturation results.

  9. Multiple taxon multiple locality approach to providing oxygen isotope evidence for warm-blooded theropod dinosaurs

    NASA Astrophysics Data System (ADS)

    Fricke, Henry C.; Rogers, Raymond R.

    2000-09-01

    Oxygen isotope ratios of fossil remains of coexisting taxa from several different localities can be used to help investigate dinosaur thermoregulation. Focusing on the Late Cretaceous, oxygen isotope ratios of crocodile tooth enamel from four separate localities exhibit less of a decrease with latitude than do ratios of tooth enamel from coexisting theropod dinosaurs. A shallower latitudinal gradient for crocodiles is consistent with how oxygen isotope ratios should vary for heterothermic animals having body temperatures coupled with their environments (“cold blooded”), while a steeper gradient for theropods is consistent with how these ratios should vary for homeothermic animals having constant body temperatures independent of their environments (“warm blooded”). This inferred homoethermy in theropods is likely due to higher rates of metabolic heat production relative to crocodiles and is not an artifact of body size.

  10. Blood oxygen- and carbon dioxide-carrying properties in captive penguins: effects of moulting and inter-specific comparison.

    PubMed

    Maxime, Valérie; Hassani, Sami

    2014-02-01

    Venous blood gas-carrying properties were compared in the three captive species of penguins (king, gentoo and rockhopper) at Océanopolis (France). Captivity permitted to control environmental influences. Given their different ecology and diving behaviour in the wild, it was wondered whether milder conditions and dive privation have repercussions on parameters determining oxygen storage and acid-base status of these birds. In addition, this work provided the opportunity to study the effects of moulting in king penguins. This annual event that imposes deep metabolic adjustments is liable to affect blood gas levels. Because of the regular food supply and probably also of the blood sampling conditions, the blood pH of captive penguins was low. This effect was increased in moulting penguins and supposedly due to both the decreased energetic metabolism and the production of uric acid resulting from new feather synthesis. The decrease in the anion gap also revealed the use of plasmatic albumin for this synthesis. The elevated venous PO2 in all birds is not likely due to stress caused by sampling conditions. The other data, in accordance with those in the literature, show neither major influence of captivity nor fundamental interspecific differences, despite potential diving aptitude. PMID:24231467

  11. Automated measurement of blood flow velocity and direction and hemoglobin oxygen saturation in the rat lung using intravital microscopy.

    PubMed

    Hanna, Gabi; Fontanella, Andrew; Palmer, Gregory; Shan, Siqing; Radiloff, Daniel R; Zhao, Yulin; Irwin, David; Hamilton, Karyn; Boico, Alina; Piantadosi, Claude A; Blueschke, Gert; Dewhirst, Mark; McMahon, Timothy; Schroeder, Thies

    2013-01-15

    Intravital microscopy of the pulmonary microcirculation in research animals is of great scientific interest for its utility in identifying regional changes in pulmonary microcirculatory blood flow. Although feasibility studies have been reported, the pulmonary window can be further refined into a practical tool for pharmaceutical research and drug development. We have established a method to visualize and quantify dynamic changes in three key features of lung function: microvascular red blood cell velocity, flow direction, and hemoglobin saturation. These physiological parameters were measured in an acute closed-chest pulmonary window, which allows real-time images to be captured by fluorescence and multispectral absorption microscopy; images were subsequently quantified using computerized analysis. We validated the model by quantifying changes in microcirculatory blood flow and hemoglobin saturation in two ways: 1) after changes in inspired oxygen content and 2) after pharmacological reduction of pulmonary blood flow via treatment with the β1 adrenergic receptor blocker metoprolol. This robust and relatively simple system facilitates pulmonary intravital microscopy in laboratory rats for pharmacological and physiological research. PMID:23161885

  12. [EFFICACY OF STANDARD TWO-YEAR COMPREHENSIVE THERAPY TO ACHIEVE TARGET BLOOD PRESSURE AND REGRESSION DEGREES OF REMODELING OF THE LEFT VENTRICULAR HYPERTROPHY IN PATIENTS AFTER ACUTE MYOCARDIAL INFARCTION WITH COMORBID HYPERTENSION].

    PubMed

    Denesiuk, E V

    2015-01-01

    The study involved 23 men after acute myocardial infarction (AMI) with comorbid arterial hypertension (AH). Mean age of patients was 56.7 years. Recurrent myocardial infarction was determined in 38.4%, cardiac failure I-III functional classes--100% of the cases. All patients underwent clinical examination, electrocardiography and echocardiography, blood lipid profile. Standard comprehensive treatment for two years included an perindopril 5-10 mg/day, beta-blocker bisoprolol--5-10 mg/day, antisclerotic drug atorvastatin--20 mg/day and aspirin--75 mg/day. The patients after treatment was determined by a gradual increase towards the target of AT at 3, 6 and 12 to 24 months. Concentric left ventricular hypertrophy (LVH) before treatment was determined in 47.8%, eccentric--in 52.2% of patients. In the study of degrees of LVH I (initial) the extent to treatment was determined by 4.3%, II (moderate)--26.1%, III (large)--at 69.6%, indicating the development of cardiac remodeling. After the treatment was determined by marked reduction III (large) degree and transfer it in the II (moderate) and I (small) degree of left ventricular hypertrophy due to more or less pronounced changes remodeling left ventricular. The obtained data allow a more detailed and adequately assess the structural and functional outcome variables and determine the regression of myocardial hypertrophy in the background to achieve target blood pressure, which is important in practical cardiology. PMID:27491146

  13. A modelling study of atrial septostomy for pulmonary arterial hypertension, and its effect on the state of tissue oxygenation and systemic blood flow.

    PubMed

    Diller, Gerhard-Paul; Lammers, Astrid E; Haworth, Sheila G; Dimopoulos, Konstantinos; Derrick, Graham; Bonhoeffer, Philipp; Gatzoulis, Michael A; Francis, Darrel P

    2010-02-01

    Atrial septostomy is performed in patients with severe pulmonary arterial hypertension, and has been shown to improve symptoms, quality of life and survival. Despite recognized clinical benefits, the underlying pathophysiologic mechanisms are poorly understood. We aimed to assess the effects of right-to-left shunting on arterial delivery of oxygen, mixed venous content of oxygen, and systemic cardiac output in patients with pulmonary arterial hypertension and a fixed flow of blood to the lungs. We formulated equations defining the mandatory relationship between physiologic variables and delivery of oxygen in patients with right-to-left shunting. Using calculus and computer modelling, we considered the simultaneous effects of right-to-left shunting on physiologies with different pulmonary flows, total metabolic rates, and capacities for carrying oxygen. Our study indicates that, when the flow of blood to the lungs is fixed, increasing right-to-left shunting improves systemic cardiac output, arterial blood pressure, and arterial delivery of oxygen. In contrast, the mixed venous content of oxygen, which mirrors the average state of tissue oxygenation, remains unchanged. Our model suggests that increasing the volume of right-to-left shunting cannot compensate for right ventricular failure. Atrial septostomy in the setting of pulmonary arterial hypertension, therefore, increases the arterial delivery of oxygen, but the mixed systemic saturation of oxygen, arguably the most important index of tissue oxygenation, stays constant. Our data suggest that the clinically observed beneficial effects of atrial septostomy are the result of improved flow of blood rather than augmented tissue oxygenation, provided that right ventricular function is adequate. PMID:20144254

  14. Red blood cell pH, the Bohr effect, and other oxygenation-linked phenomena in blood O2 and CO2 transport.

    PubMed

    Jensen, F B

    2004-11-01

    The discovery of the S-shaped O2 equilibrium curve and the Bohr effect in 1904 stimulated a fertile and continued research into respiratory functions of blood and allosteric mechanisms in haemoglobin (Hb). The Bohr effect (influence of pH/CO2 on Hb O2 affinity) and the reciprocal Haldane effect (influence of HbO2 saturation on H+/CO2 binding) originate in the Hb oxy-deoxy conformational change and allosteric interactions between O2 and H+/CO2 binding sites. In steady state, H+ is passively distributed across the vertebrate red blood cell (RBC) membrane, and intracellular pH (pHi) changes are related to changes in extracellular pH, Hb-O2 saturation and RBC organic phosphate content. As the Hb molecule shifts between the oxy and deoxy conformation in arterial-venous gas transport, it delivers O2 and takes up CO2 and H+ in tissue capillaries (elegantly aided by the Bohr effect). Concomitantly, the RBC may sense local O2 demand via the degree of Hb deoxygenation and release vasodilatory agents to match local blood flow with requirements. Three recent hypotheses suggest (1) release of NO from S-nitroso-Hb upon deoxygenation, (2) reduction of nitrite to vasoactive NO by deoxy haems, and (3) release of ATP. Inside RBCs, carbonic anhydrase (CA) provides fast hydration of metabolic CO2 and ensures that the Bohr shift occurs during capillary transit. The formed H+ is bound to Hb (Haldane effect) while HCO3- is shifted to plasma via the anion exchanger (AE1). The magnitude of the oxylabile H+ binding shows characteristic differences among vertebrates. Alternative strategies for CO2 transport include direct HCO3- binding to deoxyHb in crocodilians, and high intracellular free [HCO3-] (due to high pHi) in lampreys. At the RBC membrane, CA, AE1 and other proteins may associate into what appears to be an integrated gas exchange metabolon. Oxygenation-linked binding of Hb to the membrane may regulate glycolysis in mammals and perhaps also oxygen-sensitive ion transport involved in

  15. Trans-abdominal monitoring of fetal arterial blood oxygenation using pulse oximetry

    NASA Astrophysics Data System (ADS)

    Zourabian, Anna; Siegel, Andrew M.; Chance, Britton; Ramanujam, Nirmala; Rode, Martha; Boas, David A.

    2000-10-01

    Pulse oximetry (oxygen saturation monitoring) has markedly improved medical care in many fields, including anesthesiology, intensive care, and newborn intensive care. In obstetrics, fetal heart rate monitoring remains the standard for intrapartum assessment of fetal well being. Fetal oxygen saturation monitoring is a new technique currently under development. It is potentially superior to electronic fetal heart rate monitoring (cardiotocography) because it allows direct assessment of both the fetal oxygen status and fetal tissue perfusion. Here we present the analysis for determining the most optimal wavelength selection for pulse oximetry. The wavelengths we chose as the most optimal are the first in the range of 670 - 720 nm and the second in the range of 825 - 925 nm. Further, we discuss the possible systematic errors during our measurements and their contribution to the obtained saturation results. We present feasibility studies for fetal pulse oximetry, monitored noninvasively through the maternal abdomen. Our preliminary experiments show that the fetal pulse can be discriminated from the maternal pulse and thus, in principle, the fetal arterial oxygen saturation can be obtained. We present the methodology for obtaining these data, and discuss the dependence of our measurements on the fetal position with respect to the optode assembly.

  16. The effect of light chloralose and pentobarbitone anaesthesia on the acid—base state and oxygenation of arterial blood in dogs

    PubMed Central

    Ledsome, J. R.; Linden, R. J.; Norman, J.

    1971-01-01

    1. The effects of light anaesthesia of approximately 8 hr duration using either pentobarbitone or chloralose on the acid—base balance and oxygenation of arterial blood were determined in dogs breathing spontaneously. 2. With pentobarbitone anaesthesia there was a slight initial respiratory acidaemia. 3. With chloralose there was a non-respiratory acidaemia which was probably the result of using an unbuffered solvent. 4. Changes in the acid—base balance and the oxygen concentration of the arterial blood over the course of each experiment were minimal. 5. In one animal a pH of 7·07 was recorded; in others the oxygen tension on occasion was between 50 and 60 mm Hg. The value of monitoring the acid—base state and the oxygenation of blood in experimental preparations is discussed. PMID:5557063

  17. Inhibition of Mas G-protein signaling improves coronary blood flow, reduces myocardial infarct size, and provides long-term cardioprotection.

    PubMed

    Zhang, Tong; Li, Zhuangjie; Dang, Huong; Chen, Ruoping; Liaw, Chen; Tran, Thuy-Anh; Boatman, P Douglas; Connolly, Daniel T; Adams, John W

    2012-01-01

    The Mas receptor is a class I G-protein-coupled receptor that is expressed in brain, testis, heart, and kidney. The intracellular signaling pathways activated downstream of Mas are still largely unknown. In the present study, we examined the expression pattern and signaling of Mas in the heart and assessed the participation of Mas in cardiac ischemia-reperfusion injury. Mas mRNA and protein were present in all chambers of human hearts, with cardiomyocytes and coronary arteries being sites of enriched expression. Expression of Mas in either HEK293 cells or cardiac myocytes resulted in constitutive coupling to the G(q) protein, which in turn activated phospholipase C and caused inositol phosphate accumulation. To generate chemical tools for use in probing the function of Mas, we performed a library screen and chemistry optimization program to identify potent and selective nonpeptide agonists and inverse agonists. Mas agonists activated G(q) signaling in a dose-dependent manner and reduced coronary blood flow in isolated mouse and rat hearts. Conversely, treatment of isolated rat hearts with Mas inverse agonists improved coronary flow, reduced arrhythmias, and provided cardioprotection from ischemia-reperfusion injury, an effect that was due, at least in part, to decreased cardiomyocyte apoptosis. Participation of Mas in ischemia-reperfusion injury was confirmed in Mas knockout mice, which had reduced infarct size relative to mice with normal Mas expression. These results suggest that activation of Mas during myocardial infarction contributes to ischemia-reperfusion injury and further suggest that inhibition of Mas-G(q) signaling may provide a new therapeutic strategy directed at cardioprotection. PMID:22003054

  18. Assessment of the effects of dobutamine on myocardial blood flow and oxidative metabolism in normal human subjects using nitrogen-13 ammonia and carbon-11 acetate.

    PubMed

    Krivokapich, J; Huang, S C; Schelbert, H R

    1993-06-01

    The dual purposes of this study with positron emission tomography were to measure the effects of dobutamine on myocardial blood flow and oxidative metabolism, and to compare carbon-11 (C-11) acetate versus nitrogen-13 (N-13) ammonia in quantitating flow in normal subjects. Flow was quantitated with N-13 ammonia at rest and at peak dobutamine infusion (40 micrograms/kg/min) in 21 subjects. In 11 subjects, oxidative metabolism was also estimated at rest and peak dobutamine infusion using the clearance rate of C-11 acetate, k mono (min-1). A 2-compartment kinetic model was applied to the early phase of the C-11 acetate data to estimate flow. The rest and peak dobutamine rate-pressure products were 7,318 +/- 1,102 and 19,937 +/- 3,964 beats/min/mm Hg, respectively, and correlated well (r = 0.77) with rest and peak dobutamine flows of 0.77 +/- 0.14 and 2.25 ml/min/g determined using N-13 ammonia as a flow tracer. Rest and dobutamine flows estimated with C-11 acetate were highly correlated with those determined with N-13 ammonia (r = 0.92). k mono increased from 0.05 +/- 0.01 to 0.18 +/- 0.02 min-1, and correlated highly with the increase in flows (r = 0.91) and rate-pressure products (r = 0.94). Thus, the increase in cardiac demand associated with dobutamine is highly correlated with an increase in supply and oxidative metabolism. C-11 acetate is a unique tracer that can be used to image both flow and metabolism simultaneously. PMID:8498380

  19. Near-infrared diffuse optical monitoring of cerebral blood flow and oxygenation for the prediction of vasovagal syncope

    NASA Astrophysics Data System (ADS)

    Cheng, Ran; Shang, Yu; Wang, Siqi; Evans, Joyce M.; Rayapati, Abner; Randall, David C.; Yu, Guoqiang

    2014-01-01

    Significant drops in arterial blood pressure and cerebral hemodynamics have been previously observed during vasovagal syncope (VVS). Continuous and simultaneous monitoring of these physiological variables during VVS is rare, but critical for determining which variable is the most sensitive parameter to predict VVS. The present study used a novel custom-designed diffuse correlation spectroscopy flow-oximeter and a finger plethysmograph to simultaneously monitor relative changes of cerebral blood flow (rCBF), cerebral oxygenation (i.e., oxygenated/deoxygenated/total hemoglobin concentration: r[HbO2]/r[Hb]/rTHC), and mean arterial pressure (rMAP) during 70 deg head-up tilt (HUT) in 14 healthy adults. Six subjects developed presyncope during HUT. Two-stage physiological responses during HUT were observed in the presyncopal group: slow and small changes in measured variables (i.e., Stage I), followed by rapid and dramatic decreases in rMAP, rCBF, r[HbO2], and rTHC (i.e., Stage II). Compared to other physiological variables, rCBF reached its breakpoint between the two stages earliest and had the largest decrease (76±8%) during presyncope. Our results suggest that rCBF has the best sensitivity for the assessment of VVS. Most importantly, a threshold of ˜50% rCBF decline completely separated the subjects from those without presyncope, suggesting its potential for predicting VVS.

  20. Near-infrared diffuse optical monitoring of cerebral blood flow and oxygenation for the prediction of vasovagal syncope

    PubMed Central

    Cheng, Ran; Shang, Yu; Wang, Siqi; Evans, Joyce M.; Rayapati, Abner; Randall, David C.; Yu, Guoqiang

    2014-01-01

    Abstract. Significant drops in arterial blood pressure and cerebral hemodynamics have been previously observed during vasovagal syncope (VVS). Continuous and simultaneous monitoring of these physiological variables during VVS is rare, but critical for determining which variable is the most sensitive parameter to predict VVS. The present study used a novel custom-designed diffuse correlation spectroscopy flow-oximeter and a finger plethysmograph to simultaneously monitor relative changes of cerebral blood flow (rCBF), cerebral oxygenation (i.e., oxygenated/deoxygenated/total hemoglobin concentration: r[HbO2]/r[Hb]/rTHC), and mean arterial pressure (rMAP) during 70 deg head-up tilt (HUT) in 14 healthy adults. Six subjects developed presyncope during HUT. Two-stage physiological responses during HUT were observed in the presyncopal group: slow and small changes in measured variables (i.e., Stage I), followed by rapid and dramatic decreases in rMAP, rCBF, r[HbO2], and rTHC (i.e., Stage II). Compared to other physiological variables, rCBF reached its breakpoint between the two stages earliest and had the largest decrease (76±8%) during presyncope. Our results suggest that rCBF has the best sensitivity for the assessment of VVS. Most importantly, a threshold of ∼50% rCBF decline completely separated the subjects from those without presyncope, suggesting its potential for predicting VVS. PMID:24402372

  1. Effects of race and sex on cerebral hemodynamics, oxygen delivery and blood flow distribution in response to high altitude.

    PubMed

    Liu, Jie; Liu, Yang; Ren, Li-Hua; Li, Li; Wang, Zhen; Liu, Shan-Shan; Li, Su-Zhi; Cao, Tie-Sheng

    2016-01-01

    To assess racial, sexual, and regional differences in cerebral hemodynamic response to high altitude (HA, 3658 m). We performed cross-sectional comparisons on total cerebral blood flow (TCBF = sum of bilateral internal carotid and vertebral arterial blood flows = QICA + QVA), total cerebrovascular resistance (TCVR), total cerebral oxygen delivery (TCOD) and QVA/TCBF (%), among six groups of young healthy subjects: Tibetans (2-year staying) and Han (Han Chinese) at sea level, Han (2-day, 1-year and 5-year) and Tibetans at HA. Bilateral ICA and VA diameters and flow velocities were derived from duplex ultrasonography; and simultaneous measurements of arterial pressure, oxygen saturation, and hemoglobin concentration were conducted. Neither acute (2-day) nor chronic (>1 year) responses showed sex differences in Han, except that women showed lower TCOD compared with men. Tibetans and Han exhibited different chronic responses (percentage alteration relative to the sea-level counterpart value) in TCBF (-17% vs. 0%), TCVR (22% vs. 12%), TCOD (0% vs. 10%) and QVA/TCBF (0% vs. 2.4%, absolute increase), with lower resting TCOD found in SL- and HA-Tibetans. Our findings indicate racial but not sex differences in cerebral hemodynamic adaptations to HA, with Tibetans (but not Han) demonstrating an altitude-related change of CBF distribution. PMID:27503416

  2. Vasorelaxation by red blood cells and impairment in diabetes: reduced nitric oxide and oxygen delivery by glycated hemoglobin.

    PubMed

    James, Philip E; Lang, Derek; Tufnell-Barret, Timothy; Milsom, Alex B; Frenneaux, Michael P

    2004-04-16

    Vascular dysfunction in diabetes is attributed to lack of bioavailable nitric oxide (NO) and is postulated as a primary cause of small vessel complications as a result of poor glycemic control. Although it has been proposed that NO is bound by red blood cells (RBCs) and can induce relaxation of blood vessels distal to its site of production in the normal circulation, the effect of RBC glycation on NO binding and relaxation of hypoxic vessels is unknown. We confirm RBC-induced vessel relaxation is inversely related to tissue oxygenation and is proportional to RBC S-nitrosohemoglobin (HbSNO) content (but not nitrosylhemoglobin content). We show more total NO bound inside highly glycated RBCs (0.0134 versus 0.0119 NO/Hb, respectively; P<0.05) although proportionally less HbSNO (0.0053 versus 0.0088 NO/Hb, respectively; P<0.05). We also show glycosylation impairs the vasodilator function of RBCs within a physiological range of tissue oxygenation. These findings may represent an important contribution to reduced NO bioavailability in the microvasculature in diabetes. PMID:14963010

  3. Reduced cerebral blood flow and oxygen metabolism in extremely preterm neonates with low-grade germinal matrix- intraventricular hemorrhage

    NASA Astrophysics Data System (ADS)

    Lin, Pei-Yi; Hagan, Katherine; Fenoglio, Angela; Grant, P. Ellen; Franceschini, Maria Angela

    2016-05-01

    Low-grade germinal matrix-intraventricular hemorrhage (GM-IVH) is the most common complication in extremely premature neonates. The occurrence of GM-IVH is highly associated with hemodynamic instability in the premature brain, yet the long-term impact of low-grade GM-IVH on cerebral blood flow and neuronal health have not been fully investigated. We used an innovative combination of frequency-domain near infrared spectroscopy and diffuse correlation spectroscopy (FDNIRS-DCS) to measure cerebral oxygen saturation (SO2) and an index of cerebral blood flow (CBFi) at the infant’s bedside and compute an index of cerebral oxygen metabolism (CMRO2i). We enrolled twenty extremely low gestational age (ELGA) neonates (seven with low-grade GM-IVH) and monitored them weekly until they reached full-term equivalent age. During their hospital stay, we observed consistently lower CBFi and CMRO2i in ELGA neonates with low-grade GM-IVH compared to neonates without hemorrhages. Furthermore, lower CBFi and CMRO2i in the former group persists even after the resolution of the hemorrhage. In contrast, SO2 does not differ between groups. Thus, CBFi and CMRO2i may have better sensitivity than SO2 in detecting GM-IVH-related effects on infant brain development. FDNIRS-DCS methods may have clinical benefit for monitoring the evolution of GM-IVH, evaluating treatment response, and potentially predicting neurodevelopmental outcome.

  4. Effects of race and sex on cerebral hemodynamics, oxygen delivery and blood flow distribution in response to high altitude

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Liu, Yang; Ren, Li-Hua; Li, Li; Wang, Zhen; Liu, Shan-Shan; Li, Su-Zhi; Cao, Tie-Sheng

    2016-08-01

    To assess racial, sexual, and regional differences in cerebral hemodynamic response to high altitude (HA, 3658 m). We performed cross-sectional comparisons on total cerebral blood flow (TCBF = sum of bilateral internal carotid and vertebral arterial blood flows = QICA + QVA), total cerebrovascular resistance (TCVR), total cerebral oxygen delivery (TCOD) and QVA/TCBF (%), among six groups of young healthy subjects: Tibetans (2-year staying) and Han (Han Chinese) at sea level, Han (2-day, 1-year and 5-year) and Tibetans at HA. Bilateral ICA and VA diameters and flow velocities were derived from duplex ultrasonography; and simultaneous measurements of arterial pressure, oxygen saturation, and hemoglobin concentration were conducted. Neither acute (2-day) nor chronic (>1 year) responses showed sex differences in Han, except that women showed lower TCOD compared with men. Tibetans and Han exhibited different chronic responses (percentage alteration relative to the sea-level counterpart value) in TCBF (‑17% vs. 0%), TCVR (22% vs. 12%), TCOD (0% vs. 10%) and QVA/TCBF (0% vs. 2.4%, absolute increase), with lower resting TCOD found in SL- and HA-Tibetans. Our findings indicate racial but not sex differences in cerebral hemodynamic adaptations to HA, with Tibetans (but not Han) demonstrating an altitude-related change of CBF distribution.

  5. Reduced cerebral blood flow and oxygen metabolism in extremely preterm neonates with low-grade germinal matrix- intraventricular hemorrhage.

    PubMed

    Lin, Pei-Yi; Hagan, Katherine; Fenoglio, Angela; Grant, P Ellen; Franceschini, Maria Angela

    2016-01-01

    Low-grade germinal matrix-intraventricular hemorrhage (GM-IVH) is the most common complication in extremely premature neonates. The occurrence of GM-IVH is highly associated with hemodynamic instability in the premature brain, yet the long-term impact of low-grade GM-IVH on cerebral blood flow and neuronal health have not been fully investigated. We used an innovative combination of frequency-domain near infrared spectroscopy and diffuse correlation spectroscopy (FDNIRS-DCS) to measure cerebral oxygen saturation (SO2) and an index of cerebral blood flow (CBFi) at the infant's bedside and compute an index of cerebral oxygen metabolism (CMRO2i). We enrolled twenty extremely low gestational age (ELGA) neonates (seven with low-grade GM-IVH) and monitored them weekly until they reached full-term equivalent age. During their hospital stay, we observed consistently lower CBFi and CMRO2i in ELGA neonates with low-grade GM-IVH compared to neonates without hemorrhages. Furthermore, lower CBFi and CMRO2i in the former group persists even after the resolution of the hemorrhage. In contrast, SO2 does not differ between groups. Thus, CBFi and CMRO2i may have better sensitivity than SO2 in detecting GM-IVH-related effects on infant brain development. FDNIRS-DCS methods may have clinical benefit for monitoring the evolution of GM-IVH, evaluating treatment response, and potentially predicting neurodevelopmental outcome. PMID:27181339

  6. Blood flow and oxygenation changes due to low-frequency repetitive transcranial magnetic stimulation of the cerebral cortex

    NASA Astrophysics Data System (ADS)

    Mesquita, Rickson C.; Faseyitan, Olufunsho K.; Turkeltaub, Peter E.; Buckley, Erin M.; Thomas, Amy; Kim, Meeri N.; Durduran, Turgut; Greenberg, Joel H.; Detre, John A.; Yodh, Arjun G.; Hamilton, Roy H.

    2013-06-01

    Transcranial magnetic stimulation (TMS) modulates processing in the human brain and is therefore of interest as a treatment modality for neurologic conditions. During TMS administration, an electric current passing through a coil on the scalp creates a rapidly varying magnetic field that induces currents in the cerebral cortex. The effects of low-frequency (1 Hz), repetitive TMS (rTMS) on motor cortex cerebral blood flow (CBF) and tissue oxygenation in seven healthy adults, during/after 20 min stimulation, is reported. Noninvasive optical methods are employed: diffuse correlation spectroscopy (DCS) for blood flow and diffuse optical spectroscopy (DOS) for hemoglobin concentrations. A significant increase in median CBF (33%) on the side ipsilateral to stimulation was observed during rTMS and persisted after discontinuation. The measured hemodynamic parameter variations enabled computation of relative changes in cerebral metabolic rate of oxygen consumption during rTMS, which increased significantly (28%) in the stimulated hemisphere. By contrast, hemodynamic changes from baseline were not observed contralateral to rTMS administration (all parameters, p>0.29). In total, these findings provide new information about hemodynamic/metabolic responses to low-frequency rTMS and, importantly, demonstrate the feasibility of DCS/DOS for noninvasive monitoring of TMS-induced physiologic effects.

  7. Reduced cerebral blood flow and oxygen metabolism in extremely preterm neonates with low-grade germinal matrix- intraventricular hemorrhage

    PubMed Central

    Lin, Pei-Yi; Hagan, Katherine; Fenoglio, Angela; Grant, P. Ellen; Franceschini, Maria Angela

    2016-01-01

    Low-grade germinal matrix-intraventricular hemorrhage (GM-IVH) is the most common complication in extremely premature neonates. The occurrence of GM-IVH is highly associated with hemodynamic instability in the premature brain, yet the long-term impact of low-grade GM-IVH on cerebral blood flow and neuronal health have not been fully investigated. We used an innovative combination of frequency-domain near infrared spectroscopy and diffuse correlation spectroscopy (FDNIRS-DCS) to measure cerebral oxygen saturation (SO2) and an index of cerebral blood flow (CBFi) at the infant’s bedside and compute an index of cerebral oxygen metabolism (CMRO2i). We enrolled twenty extremely low gestational age (ELGA) neonates (seven with low-grade GM-IVH) and monitored them weekly until they reached full-term equivalent age. During their hospital stay, we observed consistently lower CBFi and CMRO2i in ELGA neonates with low-grade GM-IVH compared to neonates without hemorrhages. Furthermore, lower CBFi and CMRO2i in the former group persists even after the resolution of the hemorrhage. In contrast, SO2 does not differ between groups. Thus, CBFi and CMRO2i may have better sensitivity than SO2 in detecting GM-IVH-related effects on infant brain development. FDNIRS-DCS methods may have clinical benefit for monitoring the evolution of GM-IVH, evaluating treatment response, and potentially predicting neurodevelopmental outcome. PMID:27181339

  8. Effects of race and sex on cerebral hemodynamics, oxygen delivery and blood flow distribution in response to high altitude

    PubMed Central

    Liu, Jie; Liu, Yang; Ren, Li-hua; Li, Li; Wang, Zhen; Liu, Shan-shan; Li, Su-zhi; Cao, Tie-sheng

    2016-01-01

    To assess racial, sexual, and regional differences in cerebral hemodynamic response to high altitude (HA, 3658 m). We performed cross-sectional comparisons on total cerebral blood flow (TCBF = sum of bilateral internal carotid and vertebral arterial blood flows = QICA + QVA), total cerebrovascular resistance (TCVR), total cerebral oxygen delivery (TCOD) and QVA/TCBF (%), among six groups of young healthy subjects: Tibetans (2-year staying) and Han (Han Chinese) at sea level, Han (2-day, 1-year and 5-year) and Tibetans at HA. Bilateral ICA and VA diameters and flow velocities were derived from duplex ultrasonography; and simultaneous measurements of arterial pressure, oxygen saturation, and hemoglobin concentration were conducted. Neither acute (2-day) nor chronic (>1 year) responses showed sex differences in Han, except that women showed lower TCOD compared with men. Tibetans and Han exhibited different chronic responses (percentage alteration relative to the sea-level counterpart value) in TCBF (−17% vs. 0%), TCVR (22% vs. 12%), TCOD (0% vs. 10%) and QVA/TCBF (0% vs. 2.4%, absolute increase), with lower resting TCOD found in SL- and HA-Tibetans. Our findings indicate racial but not sex differences in cerebral hemodynamic adaptations to HA, with Tibetans (but not Han) demonstrating an altitude-related change of CBF distribution. PMID:27503416

  9. Serum estrogen levels in men with acute myocardial infarction.

    PubMed

    Klaiber, E L; Broverman, D M; Haffajee, C I; Hochman, J S; Sacks, G M; Dalen, J E

    1982-12-01

    Serum estradiol and serum estrone levels were assessed in 29 men in 14 men in whom myocardial infarction was ruled out; in 12 men without apparent coronary heart disease but hospitalized in an intensive care unit; and in 28 men who were not hospitalized and who acted as control subjects. (The 12 men who were hospitalized but who did not have coronary heart disease were included to control for physical and emotional stress of a severe medical illness.) Ages ranged from 21 to 56 years. Age, height, and weight did not differ significantly among groups. Blood samples were obtained in the patient groups on each of the first three days of hospitalization. The serum estrone level was significantly elevated in all four patient groups when compared with that in the control group. Estrone level, then, did not differentiate patients with and without coronary heart disease. Serum estradiol levels were significantly elevated in the groups with myocardial infarction, unstable angina, and in the group in whom myocardial infarction was ruled out. However, estradiol levels were not significantly elevated in the group in the intensive care unit without coronary heart disease when compared to the level in the normal control group. Serum estradiol levels, then, were elevated in men with confirmed or suspected coronary heart disease but were not elevated in men without coronary heart disease even under the stressful conditions found in an intensive care unit. Serum estradiol levels were significantly and positively correlated (p less than 0.03) with serum total creatine phosphokinase levels in the patients with myocardial infarction. The five patients with myocardial infarction who died within 10 days of admission had markedly elevated serum estradiol levels. The potential significance of these serum estradiol elevations is discussed in terms of estradiol's ability to enhance adrenergic neural activity and the resultant increase in myocardial oxygen demand. PMID:7148879

  10. Replacing the Transfusion of 1–2 Units of Blood with Plasma Expanders that Increase Oxygen Delivery Capacity: Evidence from Experimental Studies

    PubMed Central

    Tsai, Amy G.; Salazar Vázquez, Beatriz Y.; Cabrales, Pedro; Kistler, Erik B.; Tartakovsky, Daniel M.; Subramaniam, Shankar; Acharya, Seetharama A.; Intaglietta, Marcos

    2014-01-01

    At least a third of the blood supply in the world is used to transfuse 1–2 units of packed red blood cells for each intervention and most clinical trials of blood substitutes have been carried out at this level of oxygen carrying capacity (OCC) restoration. However, the increase of oxygenation achieved is marginal or none at all for molecular hemoglobin (Hb) products, due to their lingering vasoactivity. This has provided the impetus for the development of “oxygen therapeutics” using Hb-based molecules that have high oxygen affinity and target delivery of oxygen to anoxic areas. However it is still unclear how these oxygen carriers counteract or mitigate the functional effects of anemia due to obstruction, vasoconstriction and under-perfusion. Indeed, they are administered as a low dosage/low volume therapeutic Hb (subsequently further diluted in the circulatory pool) and hence induce extremely small OCC changes. Hyperviscous plasma expanders provide an alternative to oxygen therapeutics by increasing the oxygen delivery capacity (ODC); in anemia they induce supra-perfusion and increase tissue perfusion (flow) by as much as 50%. Polyethylene glycol conjugate albumin (PEG-Alb) accomplishes this by enhancing the shear thinning behavior of diluted blood, which increases microvascular endothelial shear stress, causes vasodilation and lowering peripheral vascular resistance thus facilitating cardiac function. Induction of supra-perfusion takes advantage of the fact that ODC is the product of OCC and blood flow and hence can be maintained by increasing either or both. Animal studies suggest that this approach may save a considerable fraction of the blood supply. It has an additional benefit of enhancing tissue clearance of toxic metabolites. PMID:25350267

  11. A new reference method for the determination of the oxygen content of blood.

    PubMed

    Dijkhuizen, P; Kwant, G; Zijlstra, W G

    1976-04-01

    To be able to determine the slight differences between the theoretical and the actual O2-binding capacity of human haemoglobin, a highly accurate method has been developed for measuring the O2 content of blood samples. It is an adaptation of an established O2 determination in organic microanalysis. The bound O2 of the blood is set free by conversion of HbO2 to Hi, and the O2 stripped from the blood is converted to CO by contact with granular carbon at 1120 degrees C. The CO is then converted to CO2 using CuO at 300 degrees C and the CO2 titrated in a solution of BaCl2, using NaOH of known strength. The measuring system was checked by analysis of 36 samples of air, yielding an O2 content of 20.93 +/- 0.06%. The coefficient of variation calculated from 62 duplicate determinations of samples of human blood was 0.65%. PMID:1261055

  12. Assessment of myocardial metabolic flexibility and work efficiency in human type 2 diabetes using 16-[18F]fluoro-4-thiapalmitate, a novel PET fatty acid tracer.

    PubMed

    Mather, K J; Hutchins, G D; Perry, K; Territo, W; Chisholm, R; Acton, A; Glick-Wilson, B; Considine, R V; Moberly, S; DeGrado, T R

    2016-03-15

    Altered myocardial fuel selection likely underlies cardiac disease risk in diabetes, affecting oxygen demand and myocardial metabolic flexibility. We investigated myocardial fuel selection and metabolic flexibility in human type 2 diabetes mellitus (T2DM), using positron emission tomography to measure rates of myocardial fatty acid oxidation {16-[(18)F]fluoro-4-thia-palmitate (FTP)} and myocardial perfusion and total oxidation ([(11)C]acetate). Participants underwent paired studies under fasting conditions, comparing 3-h insulin + glucose euglycemic clamp conditions (120 mU·m(-2)·min(-1)) to 3-h saline infusion. Lean controls (n = 10) were compared with glycemically controlled volunteers with T2DM (n = 8). Insulin augmented heart rate, blood pressure, and stroke index in both groups (all P < 0.01) and significantly increased myocardial oxygen consumption (P = 0.04) and perfusion (P = 0.01) in both groups. Insulin suppressed available nonesterified fatty acids (P < 0.0001), but fatty acid concentrations were higher in T2DM under both conditions (P < 0.001). Insulin-induced suppression of fatty acid oxidation was seen in both groups (P < 0.0001). However, fatty acid oxidation rates were higher under both conditions in T2DM (P = 0.003). Myocardial work efficiency was lower in T2DM (P = 0.006) and decreased in both groups with the insulin-induced increase in work and shift in fuel utilization (P = 0.01). Augmented fatty acid oxidation is present under baseline and insulin-treated conditions in T2DM, with impaired insulin-induced shifts away from fatty acid oxidation. This is accompanied by reduced work efficiency, possibly due to greater oxygen consumption with fatty acid metabolism. These observations suggest that improved fatty acid suppression, or reductions in myocardial fatty acid uptake and retention, could be therapeutic targets to improve myocardial ischemia tolerance in T2DM. PMID:26732686

  13. Reactive oxygen species (ROS) production in human peripheral blood neutrophils exposed in vitro to static magnetic field.

    PubMed

    Poniedziałek, Barbara; Rzymski, Piotr; Karczewski, Jacek; Jaroszyk, Feliks; Wiktorowicz, Krzysztof

    2013-12-01

    The aim of this study was to determine the effect of gradient static magnetic field (SMF) on reactive oxygen species (ROS) production in human neutrophils in peripheral blood in vitro. Blood samples collected from healthy individuals were incubated in an inhomogeneous SMF (in a south or north pole of the field) for 15, 30 or 45 minutes. The maximum value of induction (B max) amounted to ≈ 60 mT. To determine the strength of the ROS production, dihydrorhodamine (123DHR) as fluorophore and phorbol 12-myristate 13-acetate (PMA) as respiratory burst stimulator were used. 123DHR oxidation by ROS was measured by flow cytometry. The exposure of blood samples to SMF induced statistically significant changes in ROS production in unstimulated and PMA-stimulated neutrophils. The observed effects were highly correlated with the exposure time and depended on the orientation of the field. Although intracellular mechanisms underlying such interactions are not thoroughly understood, it could be presumed that SMF affects ROS metabolic oscillations and their formation and inactivation. This study emphasizes the importance of proper adjustment of exposure time to SMF for any potential therapeutic applications. PMID:23631724

  14. Myocardial Bridge

    MedlinePlus

    ... artery. See also on this site: Ask a Texas Heart Institute Doctor: Search "myocardial bridge" Updated August ... comments. Terms of Use and Privacy Policy © Copyright Texas Heart Institute All rights reserved.

  15. Renal Blood Oxygenation Level-dependent Imaging in Longitudinal Follow-up of Donated and Remaining Kidneys.

    PubMed

    Seif, Maryam; Eisenberger, Ute; Binser, Tobias; Thoeny, Harriet C; Krauer, Fabienne; Rusch, Aurelia; Boesch, Chris; Vogt, Bruno; Vermathen, Peter

    2016-06-01

    Purpose To determine renal oxygenation changes associated with uninephrectomy and transplantation in both native donor kidneys and transplanted kidneys by using blood oxygenation level-dependent (BOLD) MR imaging. Materials and Methods The study protocol was approved by the local ethics committee. Thirteen healthy kidney donors and their corresponding recipients underwent kidney BOLD MR imaging with a 3-T imager. Written informed consent was obtained from each subject. BOLD MR imaging was performed in donors before uninephrectomy and in donors and recipients 8 days, 3 months, and 12 months after transplantation. R2* values, which are inversely related to tissue partial pressure of oxygen, were determined in the cortex and medulla. Longitudinal R2* changes were statistically analyzed by using repeated measures one-way analysis of variance with post hoc pair-wise comparisons. Results R2* values in the remaining kidneys significantly decreased early after uninephrectomy in both the medulla and cortex (P < .003), from 28.9 sec(-1) ± 2.3 to 26.4 sec(-1) ± 2.5 in the medulla and from 18.3 sec(-1) ± 1.5 to 16.3 sec(-1) ± 1.0 in the cortex, indicating increased oxygen content. In donors, R2* remained significantly decreased in both the medulla and cortex at 3 (P < .01) and 12 (P < .01) months. In transplanted kidneys, R2* remained stable during the first year after transplantation, with no significant change. Among donors, cortical R2* was found to be negatively correlated with estimated glomerular filtration rate (R = -0.47, P < .001). Conclusion The results suggest that BOLD MR imaging may potentially be used to monitor renal functional changes in both remaining and corresponding transplanted kidneys. (©) RSNA, 2016. PMID:26744926

  16. Detecting gas‐induced vasomotor changes via blood oxygenation level‐dependent contrast in healthy breast parenchyma and breast carcinoma

    PubMed Central

    Wallace, Tess E.; Patterson, Andrew J.; Abeyakoon, Oshaani; Bedair, Reem; Manavaki, Roido; McLean, Mary A.; O'Connor, James P.B.; Graves, Martin J.

    2016-01-01

    Purpose To evaluate blood oxygenation level‐dependent (BOLD) contrast changes in healthy breast parenchyma and breast carcinoma during administration of vasoactive gas stimuli. Materials and Methods Magnetic resonance imaging (MRI) was performed at 3T in 19 healthy premenopausal female volunteers using a single‐shot fast spin echo sequence to acquire dynamic T 2‐weighted images. 2% (n = 9) and 5% (n = 10) carbogen gas mixtures were interleaved with either medical air or oxygen in 2‐minute blocks, for four complete cycles. A 12‐minute medical air breathing period was used to determine background physiological modulation. Pixel‐wise correlation analysis was applied to evaluate response to the stimuli in breast parenchyma and these results were compared to the all‐air control. The relative BOLD effect size was compared between two groups of volunteers scanned in different phases of the menstrual cycle. The optimal stimulus design was evaluated in five breast cancer patients. Results Of the four stimulus combinations tested, oxygen vs. 5% carbogen produced a response that was significantly stronger (P < 0.05) than air‐only breathing in volunteers. Subjects imaged during the follicular phase of their cycle when estrogen levels typically peak exhibited a significantly smaller BOLD response (P = 0.01). Results in malignant tissue were variable, with three out of five lesions exhibiting a diminished response to the gas stimulus. Conclusion Oxygen vs. 5% carbogen is the most robust stimulus for inducing BOLD contrast, consistent with the opposing vasomotor effects of these two gases. Measurements may be confounded by background physiological fluctuations and menstrual cycle changes. J. Magn. Reson. Imaging 2016;44:335–345. PMID:26898173

  17. Influence of low-intensity laser radiation on degree of oxygenation and speed microcirculation of blood

    NASA Astrophysics Data System (ADS)

    Korolevich, Alexander N.; Dubina, Natali S.; Vecherinski, Sergei I.

    2000-11-01

    The paper investigated in vivo the influence of low-intensity laser radiation (he-Ne laser with wavelength 0,63 nm) on the mean velocity of their movement. It is known that characteristic of cardiovascular diseases (CVD) are microcirculation disturbances and disorder in rheological properties of blood. Therefore these investigations were carried out on cardiac ischemia patients. The blood perfusion valve and the mean velocity were measured by the method of photon correlation spectroscopy with the use of fiber optic cables. As the radiation source, a semiconductor laser with wavelength 780 nm (0,8 mW) was used. It has been found that, between the erythrocytes and the mean velocity of their movement there is an inverse dependence on the time of irradiation of patients.

  18. Myocardial Noncompaction Presenting With Myocardial Bridge

    PubMed Central

    Shen, Yuechun; Li, Xinchun; Lu, Dongfeng; Xiao, Aiyi; Li, Jun

    2015-01-01

    Abstract Myocardial noncompaction, namly isolated noncompaction of the left ventricular myocardium (NVM), is a rare congenital disease. It can be either seen in the absence of other cardiac anomalies, or associated with other congenital cardiac defects, mostly stenotic lesions of the left ventricular outflow tract. A myocardial bridge (MB) is thought being associated with coronary heart disease, such as coronary spasm, arrhythmia, and so on. The significance of MB in association with other congenital cardiac conditions is unknown. We report a novel case who was presented NVM and MB. A 34-year-old man complained of chest prickling-like pain and dizzy for 1 year. His blood pressure was 110/70 mm Hg. Echocardiograph revealed increased trabeculations below the level of papillary muscle of left ventricle (LV); deep intertrabecular recesses in the endocardial wall of LV particularly in apex free wall; and LV ejection fraction of 57%. A coronary computerized tomography scan showed that part, 38.9 cm, of left descending artery tunnel was surrounding by cardiac muscles rather than resting on top of the myocardium. The therapeutics interventions included lifestyle cares, agents of anti-ischemia and improvement myocardial cell metabolism. The patient was followed up for 2.6 years, and his general condition was stable. This case indicates that NVM can be developed with MB, and the complete diagnosis of NVM and MB should be made by different image studies. PMID:26356695

  19. Exercise with hypoventilation induces lower muscle oxygenation and higher blood lactate concentration: role of hypoxia and hypercapnia.

    PubMed

    Woorons, Xavier; Bourdillon, Nicolas; Vandewalle, Henri; Lamberto, Christine; Mollard, Pascal; Richalet, Jean-Paul; Pichon, Aurélien

    2010-09-01

    Eight men performed three series of 5-min exercise on a cycle ergometer at 65% of normoxic maximal O(2) consumption in four conditions: (1) voluntary hypoventilation (VH) in normoxia (VH(0.21)), (2) VH in hyperoxia (inducing hypercapnia) (inspired oxygen fraction [F(I)O(2)] = 0.29; VH(0.29)), (3) normal breathing (NB) in hypoxia (F(I)O(2) = 0.157; NB(0.157)), (4) NB in normoxia (NB(0.21)). Using near-infrared spectroscopy, changes in concentration of oxy-(Delta[O(2)Hb]) and deoxyhemoglobin (Delta[HHb]) were measured in the vastus lateralis muscle. Delta[O(2)Hb - HHb] and Delta[O(2)Hb + HHb] were calculated and used as oxygenation index and change in regional blood volume, respectively. Earlobe blood samples were taken throughout the exercise. Both VH(0.21) and NB(0.157) induced a severe and similar hypoxemia (arterial oxygen saturation [SaO(2)] < 88%) whereas SaO(2) remained above 94% and was not different between VH(0.29) and NB(0.21). Arterialized O(2) and CO(2) pressures as well as P50 were higher and pH lower in VH(0.21) than in NB(0.157), and in VH(0.29) than in NB(0.21). Delta[O(2)Hb] and Delta[O(2)Hb - HHb] were lower and Delta[HHb] higher at the end of each series in both VH(0.21) and NB(0.157) than in NB(0.21) and VH(0.29). There was no difference in Delta[O(2)Hb + HHb] between testing conditions. [La] in VH(0.21) was greater than both in NB(0.21) and VH(0.29) but not different from NB(0.157). This study demonstrated that exercise with VH induced a lower tissue oxygenation and a higher [La] than exercise with NB. This was caused by a severe arterial O(2) desaturation induced by both hypoxic and hypercapnic effects. PMID:20503056

  20. Increased regional homogeneity of blood oxygen level-dependent signals in occipital cortex of early blind individuals.

    PubMed

    Liu, Chong; Liu, Yong; Li, Weilan; Wang, Dawei; Jiang, Tianzi; Zhang, Yunting; Yu, Chunshui

    2011-03-01

    Although resting-state functional magnetic resonance imaging has shown altered functional connectivity between visual and other brain areas in the early blind individuals, it cannot answer which brain area's local activities are changed. In this study, regional homogeneity, a measure of the homogeneity of the local blood oxygen level-dependent signals, was used for the first time to investigate the changes in the resting-state brain activity in the early blind individuals. Compared with age-matched and sex-matched sighted individuals, the early blind individuals showed increased regional homogeneity only in the occipital areas, which might be explained by the abnormal cortical development and/or experience-dependent plasticity, resulted from an early visual deprivation. PMID:21304328

  1. Imaging and Modeling of Myocardial Metabolism

    PubMed Central

    Jamshidi, Neema; Karimi, Afshin; Birgersdotter-Green, Ulrika; Hoh, Carl

    2010-01-01

    Current imaging methods have focused on evaluation of myocardial anatomy and function. However, since myocardial metabolism and function are interrelated, metabolic myocardial imaging techniques, such as positron emission tomography, single photon emission tomography, and magnetic resonance spectroscopy present novel opportunities for probing myocardial pathology and developing new therapeutic approaches. Potential clinical applications of metabolic imaging include hypertensive and ischemic heart disease, heart failure, cardiac transplantation, as well as cardiomyopathies. Furthermore, response to therapeutic intervention can be monitored using metabolic imaging. Analysis of metabolic data in the past has been limited, focusing primarily on isolated metabolites. Models of myocardial metabolism, however, such as the oxygen transport and cellular energetics model and constraint-based metabolic network modeling, offer opportunities for evaluation interactions between greater numbers of metabolites in the heart. In this review, the roles of metabolic myocardial imaging and analysis of metabolic data using modeling methods for expanding our understanding of cardiac pathology are discussed. PMID:20559785

  2. Myocardial perfusion imaging using contrast echocardiography.

    PubMed

    Pathan, Faraz; Marwick, Thomas H

    2015-01-01

    Microbubbles are an excellent intravascular tracer, and both the rate of myocardial opacification (analogous to coronary microvascular perfusion) and contrast intensity (analogous to myocardial blood volume) provide unique insights into myocardial perfusion. A strong evidence base has been accumulated to show comparability with nuclear perfusion imaging and incremental diagnostic and prognostic value relative to wall motion analysis. This technique also provides the possibility to measure myocardial perfusion at the bedside. Despite all of these advantages, the technique is complicated, technically challenging, and has failed to scale legislative and financial hurdles. The development of targeted imaging and therapeutic interventions will hopefully rekindle interest in this interesting modality. PMID:25817740

  3. Dependence of light fluence on treated depth with photosensitization reaction shortly after photosensitizer injection in rabbit myocardial tissue in vivo

    NASA Astrophysics Data System (ADS)

    Suenari, T.; Matsuo, H.; Ito, A.; Miyoshi, S.; Arai, T.

    2010-02-01

    We investigated experimentally dependence of light fluence on treated depth with photosensitization reaction shortly after photosensitizer injection in rabbit myocardial tissue in vivo. In this particular photosensitization reaction scheme, the photosensitizer accumulation characteristics for target region are not available. Meanwhile, the photosensitizer dose and hospitalization period under restricted light circumstance might be reduced. Since both photosensitizer and oxygen supply are governed by blood flow, this photosensitization reaction is influenced significantly by blood flow variation in particular blood vessel occlusion. We employed the myocardial tissue to keep tissue blood flow during the photosensitization reaction because vessel blood flow speed in myocardial tissue is fast to resist vascular occlusion. Surgically exposed rabbits myocardial tissues were irradiated with the light fluence ranging 25-100 J/cm2 by a 663 nm diode laser 30 min after the injection of 2 mg/kg water soluble chlorin photosensitizer, Talaporfin sodium. Two weeks after the irradiation, the rabbits were sacrificed and the histological specimens of the irradiated area were made to measure scar layer thickness. The scar layer tissue thickness of 0.2-3.0 mm was observed microscopically by the light fluence ranging 25-100 J/cm2. The scarring threshold in the deposit light fluence was estimated to 15-25 J/cm3 based on the above mentioned relation assuming constant and uniform myocardial effective attenuation coefficient of 0.72 mm-1. The estimated scarring threshold in the deposit light fluence was lower than the threshold of conventional PDT. Large variation of the estimated threshold value might be attributed to unconsidered PDT parameter such as flow rate inhomogeneity in the myocardial tissue. These results suggested that the photosensitization reaction investigated in this study would be available to apply arrhythmia therapy such as atrial fibrillation.