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1

EFFECT OF VENTILATION AND PERFUSION IMBALANCE ON INERT GAS REBREATHING VARIABLES  

EPA Science Inventory

The effects of ventilation-to-perfusion (Va/Qc) maldistribution within the lungs on measured multiple gas rebreathing variables were studied in 14 dogs. The rebreathing method (using He, C18C, and C2H2) allows for measurements of pulmonary capillary blood flow (Qc), diffusing cap...

2

Ventilation-perfusion distribution in normal subjects.  

PubMed

Functional values of LogSD of the ventilation distribution (?(V)) have been reported previously, but functional values of LogSD of the perfusion distribution (?(q)) and the coefficient of correlation between ventilation and perfusion (?) have not been measured in humans. Here, we report values for ?(V), ?(q), and ? obtained from wash-in data for three gases, helium and two soluble gases, acetylene and dimethyl ether. Normal subjects inspired gas containing the test gases, and the concentrations of the gases at end-expiration during the first 10 breaths were measured with the subjects at rest and at increasing levels of exercise. The regional distribution of ventilation and perfusion was described by a bivariate log-normal distribution with parameters ?(V), ?(q), and ?, and these parameters were evaluated by matching the values of expired gas concentrations calculated for this distribution to the measured values. Values of cardiac output and LogSD ventilation/perfusion (Va/Q) were obtained. At rest, ?(q) is high (1.08 ± 0.12). With the onset of ventilation, ?(q) decreases to 0.85 ± 0.09 but remains higher than ?(V) (0.43 ± 0.09) at all exercise levels. Rho increases to 0.87 ± 0.07, and the value of LogSD Va/Q for light and moderate exercise is primarily the result of the difference between the magnitudes of ?(q) and ?(V). With known values for the parameters, the bivariate distribution describes the comprehensive distribution of ventilation and perfusion that underlies the distribution of the Va/Q ratio. PMID:22773767

Beck, Kenneth C; Johnson, Bruce D; Olson, Thomas P; Wilson, Theodore A

2012-09-01

3

Ventilation/perfusion lung scintigraphy. Multiple applications besides pulmonary embolism.  

PubMed

Ventilation/perfusion scintigraphy is the diagnostic tool of choice for detection and monitoring of pulmonary embolism. However, the knowledge on its value for other or concurrent pathologies is poor. In this review scintigraphic characteristics of the main pathologies, interpretation and artefacts are described. Together with the understanding of pathophysiology of the lung, the potential gain of information derived from ventilation/perfusion scintigraphy is much higher than generally believed. In conclusion, ventilation/perfusion scintigraphy not only in PE but also in other lung diseases is underused, its value and clinical potential underestimated. PMID:23529394

Sinzinger, Helmut; Rodrigues, Margarida; Kummer, Friedrich

2013-01-01

4

Inert gas analysis of ventilation-perfusion matching during hemodialysis.  

PubMed Central

The mechanism of hypoxemia during hemodialysis was investigated by the multiple inert gas elimination technique in anesthetized, paralyzed, mechanically ventilated dogs. Profound leukopenia occurred in the first hour of a 2-h hemodialysis with a cuprophan membrane and dialysate that contained acetate. Arterial partial pressure of O2 and CO2 and oxygen consumption remained unchanged during dialysis. Pulmonary carbon dioxide elimination and lung respiratory exchange ratio decreased with the initiation of dialysis, remained depressed throughout the duration of dialysis, and returned to predialysis levels after the cessation of dialysis. Cardiac output diminished during dialysis but did not return to base-line levels after dialysis. Multiple indices calculated from inert gas analysis revealed no ventilation-perfusion mismatching during dialysis. The shunt and perfusion to regions of low alveolar ventilation-to-perfusion ratio (VA/Q) were unchanged during dialysis. There was no change in the mean or standard deviation of the profile of the percentage of total perfusion to regions of the lung that had VA/Q near 1.0; nor was there any increase in the directly calculated arterial-alveolar partial pressure differences for the inert gases during dialysis. Dead space became mildly elevated during dialysis. These results show that during dialysis with controlled ventilation there is no ventilation-perfusion mismatching that leads to hypoxemia. During spontaneous ventilation any hypoxemia must occur due to hypoventilation secondary to the CO2 exchange by the dialyzer and subsequent reduction in pulmonary CO2 exchange.

Ralph, D D; Ott, S M; Sherrard, D J; Hlastala, M P

1984-01-01

5

Quantification of Regional Ventilation-Perfusion Ratios with PET  

Microsoft Academic Search

The topographic matching of alveolar ventilation (VA) and per- fusion (Q ? ) is the main determinant of gas exchange efficiency of the lung. However, no pulmonary functional imaging technique has been shown to predict whole-lung gas exchange in health and disease. This study aims to present a PET-based method to estimate regional alveolar ventilation-to-perfusion ratios (VA\\/Q ? ) predictive

Marcos F. Vidal Melo; Dominick Layfield; R. Scott Harris; Kevin O'Neill; Guido Musch; Torsten Richter; Tilo Winkler; Alan J. Fischman; Jose G. Venegas

2003-01-01

6

Teaching Ventilation/Perfusion Relationships in the Lung  

ERIC Educational Resources Information Center

This brief review is meant to serve as a refresher for faculty teaching respiratory physiology to medical students. The concepts of ventilation and perfusion matching are some of the most challenging ideas to learn and teach. Some strategies to consider in teaching these concepts are, first, to build from simple to more complex by starting with a…

Glenny, Robb W.

2008-01-01

7

Ventilation and perfusion magnetic resonance imaging of the lung  

PubMed Central

Summary A close interaction between the respiratory pump, pulmonary parenchyma and blood circulation is essential for a normal lung function. Many pulmonary diseases present, especially in their initial phase, a variable regional impairment of ventilation and perfusion. In the last decades various techniques have been established to measure the lung function. Besides the global pulmonary function tests (PFTs) imaging techniques gained increasing importance to detect local variations in lung function, especially for ventilation and perfusion assessment. Imaging modalities allow for a deeper regional insight into pathophysiological processes and enable improved planning of invasive procedures. In contrast to computed tomography (CT) and the nuclear medicine techniques, magnetic resonance imaging (MRI), as a radiation free imaging modality gained increasing importance since the early 1990 for the assessment of pulmonary function. The major inherent problems of lung tissue, namely the low proton density and the pulmonary and cardiac motion, were overcome in the last years by a constant progress in MR technology. Some MR techniques are still under development, a process which is driven by scientific questions regarding the physiology and pathophysiology of pulmonary diseases, as well as by the need for fast and robust clinically applicable imaging techniques as safe therapy monitoring tools. MRI can be considered a promising ionizing-free alternative to techniques like CT or nuclear medicine techniques for the evaluation of lung function. The goal of this article is to provide an overview on selected MRI techniques for the assessment of pulmonary ventilation and perfusion.

Bauman, Grzegorz; Eichinger, Monika

2012-01-01

8

Changes in distribution of lung perfusion and ventilation at rest and during maximal exercise  

SciTech Connect

A new method for evaluation of changes in the distribution of pulmonary perfusion and ventilation during exercise was applied to normal male volunteers. Ventilation and perfusion scans were done with the subjects seated on a bicycle ergometer. The resting studies utilized krypton 81 (/sup 81m/Kr) for ventilation and technetium /sup 99m/ (/sup 99m/Tc) macroaggregate albumin intravenously for perfusion. Exercise studies were done when 80 percent of maximum predicted heart rate was maintained for five minutes and utilized /sup 81m/Kr for ventilation and a tenfold dose of /sup 99m/Tc for perfusion. Higher dose of /sup 99m/Tc would minimize the effect of radioactivity left over from the resting study. This method allowed us to assess changes in ventilation and perfusion in normal subjects induced by exercise, but may also be applicable in a variety of cardiopulmonary conditions that affect pulmonary ventilation and perfusion or both.

Mohsenifar, Z.; Ross, M.D.; Waxman, A.; Goldbach, P.; Koerner, S.K.

1985-03-01

9

Idiopathic pulmonary fibrosis. A rare cause of scintigraphic ventilation-perfusion mismatch  

SciTech Connect

A case of idiopathic pulmonary fibrosis with multiple areas of mismatch on ventilation-perfusion lung imaging in the absence of pulmonary embolism is presented. Idiopathic pulmonary fibrosis is one of the few nonembolic diseases producing a pulmonary ventilation-perfusion mismatch. In this condition, chest radiographs may not detect the full extent of disease, and xenon-133 ventilation imaging may be relatively insensitive to morbid changes in small airways. Thus, when examining patients with idiopathic pulmonary fibrosis, one should be aware that abnormal perfusion imaging patterns without matching ventilation abnormalities are not always due to embolism. In this setting, contrast pulmonary angiography is often needed for accurate differential diagnosis.

Pochis, W.T.; Krasnow, A.Z.; Collier, B.D.; Mewissen, M.W.; Almagro, U.A.; Hellman, R.S.; Isitman, A.T. (Medical College of Wisconsin, Milwaukee (USA))

1990-05-01

10

Computed Tomography Studies of Lung Ventilation and Perfusion  

PubMed Central

With the emergence of multidetector-row computed tomography (CT) it is now possible to image both structure and function via use of a single imaging modality. Breath-hold spiral CT provides detail of the airway and vascular trees along with texture reflective of the state of the lung parenchyma. Use of stable xenon gas wash-in and/or wash-out methods using an axial mode of the CT scanner whereby images are acquired through gating to the respiratory cycle provide detailed images of regional ventilation with isotropic voxel dimensions now on the order of 0.4 mm. Axial scanning during a breath hold and gating to the electrocardiogram during the passage of a sharp bolus injection of iodinated contrast agent provide detailed images of regional pulmonary perfusion. These dynamic CT methods for the study of regional lung function are discussed in the context of other methods that have been used to study heterogeneity of lung function.

Hoffman, Eric A.; Chon, Deokiee

2005-01-01

11

The effect of omalizumab on ventilation and perfusion in adults with allergic asthma  

PubMed Central

Omalizumab promotes clinical improvement in patients with allergic asthma, but its effect on pulmonary function is unclear. One possibility is that omalizumab improves asthma symptoms through effects on the regional distributions of ventilation, perfusion, and ventilation/perfusion matching, metrics which can be assessed with Nitrogen-13-saline Position Emission Tomography (PET). Four adults with moderate to severe uncontrolled allergic asthma underwent symptom assessment, spirometry and functional pulmonary imaging with Nitrogen-13-saline PET before and after 4-5 months of treatment with omalizumab. PET imaging was used to determine ventilation/perfusion ratios, the heterogeneity (coefficient of variation, COV) of ventilation and perfusion, and lung regions with ventilation defects. There were no significant changes in spirometry values after omalizumab treatment, but there was a trend towards an improvement in symptom scores. There was little change in the matching of ventilation and perfusion. The COV of perfusion was similar before and after omalizumab treatment. The COV of ventilation was also similar before (0.57 (0.28)) and after (0.66 (0.13)) treatment, and it was similar to previously published values for healthy subjects. There was a non-significant trend towards an increase in the extent of ventilation defects after omalizumab treatment, from 5 (15)% to 12.8 (14.7)%. Treatment of moderate to severe uncontrolled allergic asthma with omalizumab did not result in a significant improvement in ventilation and perfusion metrics assessed with functional PET imaging. The normal COV of ventilation which was unaffected by treatment supports the hypothesis that omalizumab exerts its clinical effect on lung function during allergen exposure rather than in between exacerbations.

Kelmenson, Daniel A; Kelly, Vanessa J; Winkler, Tilo; Kone, Mamary T; Musch, Guido; Melo, Marcos F Vidal; Venegas, Jose G; Harris, R Scott

2013-01-01

12

The effect of omalizumab on ventilation and perfusion in adults with allergic asthma.  

PubMed

Omalizumab promotes clinical improvement in patients with allergic asthma, but its effect on pulmonary function is unclear. One possibility is that omalizumab improves asthma symptoms through effects on the regional distributions of ventilation, perfusion, and ventilation/perfusion matching, metrics which can be assessed with Nitrogen-13-saline Position Emission Tomography (PET). Four adults with moderate to severe uncontrolled allergic asthma underwent symptom assessment, spirometry and functional pulmonary imaging with Nitrogen-13-saline PET before and after 4-5 months of treatment with omalizumab. PET imaging was used to determine ventilation/perfusion ratios, the heterogeneity (coefficient of variation, COV) of ventilation and perfusion, and lung regions with ventilation defects. There were no significant changes in spirometry values after omalizumab treatment, but there was a trend towards an improvement in symptom scores. There was little change in the matching of ventilation and perfusion. The COV of perfusion was similar before and after omalizumab treatment. The COV of ventilation was also similar before (0.57 (0.28)) and after (0.66 (0.13)) treatment, and it was similar to previously published values for healthy subjects. There was a non-significant trend towards an increase in the extent of ventilation defects after omalizumab treatment, from 5 (15)% to 12.8 (14.7)%. Treatment of moderate to severe uncontrolled allergic asthma with omalizumab did not result in a significant improvement in ventilation and perfusion metrics assessed with functional PET imaging. The normal COV of ventilation which was unaffected by treatment supports the hypothesis that omalizumab exerts its clinical effect on lung function during allergen exposure rather than in between exacerbations. PMID:23901360

Kelmenson, Daniel A; Kelly, Vanessa J; Winkler, Tilo; Kone, Mamary T; Musch, Guido; Melo, Marcos F Vidal; Venegas, Jose G; Harris, R Scott

2013-01-01

13

Ventilation-perfusion scan in the acutely ill patient with unilateral hyperlucent lung  

SciTech Connect

A patient with a unilateral hyperlucent lung with acute respiratory complaints is presented. A ventilation-perfusion scan was performed to rule out pulmonary embolism. The perfusion scan ( (/sup 99m/TC)MAA) showed peripheral perfusion defects in the hyperlucent lung. The ventilation study (/sup 133/Xe) demonstrated peripheral ventilatory defects on the single breath image in the hyperlucent lung, the filling in of these on the equilibrium view, and diffusely delayed washout in the affected lung. These findings were suggestive of the Swyer-James syndrome and critical in excluding the numerous other causes of unilateral hyperlucent lung, which are discussed. The importance of the ventilation-perfusion study (and particularly the ventilation scan) in the patient with unilateral hyperlucent lung and acute respiratory symptoms is stressed. In addition, a discussion of the Swyer-James syndrome is included.

Miller, M.B.; Caride, V.J.

1988-01-01

14

Prediction of postoperative loss of lung function in patients with malignant lung mass. Quantitative regional ventilation-perfusion scanning  

SciTech Connect

The quantitative measurement of regional ventilation and perfusion distribution is simply and reliably accomplished by using routinely available radioactive gas and perfusion lung scanning agents, and a large field-of-view gamma camera with an on-line computer. The preoperative prediction of postsurgical loss in lung function can be made accurately by using the quantitative ventilation-perfusion lung scan technique. Either a regional ventilation study or perfusion study may be used for the prediction, but analysis of regional ventilation distribution appears to be a better parameter than that of perfusion distribution for the prediction of postoperative loss of FEV1. In the rare case of a patient with a marked ventilation-perfusion deficit, quantitative distribution of both ventilation and perfusion may be needed for an accurate assessment of postsurgical lung function. 18 references.

Ryo, U.Y. (Univ. of Kentucky College of Medicine, Lexington (USA))

1990-05-01

15

Apocynin attenuates ventilator-induced lung injury in an isolated and perfused rat lung model  

PubMed Central

Rationale Apocynin suppresses the generation of reactive oxygen species (ROS) that are implicated in ventilator-induced lung injury (VILI). We thus hypothesized that apocynin attenuates VILI. Methods VILI was induced by mechanical ventilation with tidal volume (Vt) of 15 ml/kg in isolated and perfused rat lung. Apocynin was administered in the perfusate at onset of mechanical ventilation. A group ventilated with low Vt of 5 ml/kg served as control. Hemodynamics, lung injury indices, inflammatory responses, and activation of apoptotic pathways were determined upon completion of mechanical ventilation. Results There was an increase in lung permeability and lung weight gain after mechanical ventilation with high Vt, compared with low Vt. Levels of inflammatory cytokines including interleukin-1b (IL-1b), tumor necrosis factor-alpha (TNF-a), and macrophage inflammatory protein-2 (MIP-2) increased in lung lavage fluids; concentrations of carbonyl, thiobarbituric acid reactive substances, and H2O2 were higher in perfusates and lung lavage fluids, and expression of myeloperoxidase, JNK, p38, and caspase-3 in lung tissue was greater in the high-Vt than in the low-Vt group. Administration of apocynin attenuated these inflammatory responses and lung permeability associated with decreased activation of nuclear factor-?B. Conclusions VILI is associated with inflammatory responses including generation of ROS, cytokines, and activation of mitogen-activated protein kinase cascades. Administration of apocynin at onset of mechanical ventilation attenuates inflammatory responses and VILI in the isolated, perfused rat lung model.

Lee, Tzong-Shyuan; Kou, Yu Ru; Zhang, Haibo

2014-01-01

16

Ventilation/Perfusion Scintigraphy in Children with Post-Infectious Bronchiolitis Obliterans: A Pilot Study  

PubMed Central

Purpose Childhood post-infectious bronchiolitis obliterans (BO) is an infrequent lung disease leading to narrowing and/or complete obliteration of small airways. Ventilation and perfusion (V/Q) scan can provide both regional and global pulmonary information. However, only few retrospective researches investigating post-infectious BO involved V/Q scan, the clinical value of this method is unknown. This preliminary prospective study was aimed to evaluate the correlation of V/Q scan with disease severity, pulmonary function test results, and prognosis in children with post-infectious BO. Methods Twenty-five post-infectious BO children (18 boys and 7 girls; mean age, 41 months) underwent V/Q scan and pulmonary function tests. Patients were followed after their inclusion. Ventilation index and perfusion index obtained from V/Q scan were used to measure pulmonary abnormalities. Spearman's rank correlation test of ventilation index and perfusion index on disease severity, lung function tests indices, and follow-up results were performed. Results The median follow-up period was 4.6 years (range, 2.2 to 5.0 years). Ventilation index and perfusion index were both correlated with disease severity (r?=?0.72, p<0.01 and r?=?0.73, p<0.01), but only ventilation index was related to pulmonary function tests results (all p<0.05). In addition, Spearman test yielded significant correlations between perfusion index and prognosis (r?=?0.77, p<0.01), and ventilation index and prognosis (r?=?0.63, p?=?0.01). Conclusions For children with post-infectious BO, the present study preliminarily indicated that the degree of ventilation and perfusion abnormalities evaluated by V/Q scan may be used to assess disease severity, and may be predictive of patient's outcome.

Xie, Bo-Qia; Wang, Wei; Zhang, Wen-Qian; Guo, Xin-Hua; Yang, Min-Fu; Wang, Li; He, Zuo-Xiang; Tian, Yue-Qin

2014-01-01

17

Dynamic chest radiography with a flat-panel detector (FPD): ventilation-perfusion study  

NASA Astrophysics Data System (ADS)

Pulmonary ventilation and blood flow are reflected in dynamic chest radiographs as changes in X-ray translucency, i.e., pixel values. This study was performed to investigate the feasibility of ventilation-perfusion (V/Q) study based on the changes in pixel value. Sequential chest radiographs of a patient with ventilation-perfusion mismatch were obtained during respiration using a dynamic flat-panel detector (FPD) system. The lung area was recognized and average pixel value was measured in each area, tracking and deforming the region of interest. Inter-frame differences were then calculated, and the absolute values were summed in each respiratory phase. The results were visualized as ventilation, blood flow, V/Q ratio distribution map and compared to distribution of radioactive counts on ventilation and perfusion scintigrams. In the results, abnormalities were appeared as a reduction of changes in pixel values, and a correlation was observed between the distribution of changes in pixel value and those of radioactivity counts (Ventilation; r=0.78, Perfusion; r=0.77). V/Q mismatch was also indicated as mismatch of changes in pixel value, and a correlation with V/Q calculated by radioactivity counts (r=0.78). These results indicated that the present method is potentially useful for V/Q study as an additional examination in conventional chest radiography.

Tanaka, R.; Sanada, S.; Fujimura, M.; Yasui, M.; Tsuji, S.; Hayashi, N.; Okamoto, H.; Nanbu, Y.; Matsui, O.

2011-03-01

18

Optimization of isolated perfused/ventilated mouse lung to study hypoxic pulmonary vasoconstriction.  

PubMed

Hypoxic pulmonary vasoconstriction (HPV) is a compensatory physiological mechanism in the lung that optimizes the matching of ventilation to perfusion and thereby maximizes gas exchange. Historically, HPV has been primarily studied in isolated perfused/ventilated lungs; however, the results of these studies have varied greatly due to different experimental conditions and species. Therefore, in the present study, we utilized the mouse isolated perfused/ventilated lung model for investigation of the role of extracellular Ca(2+) and caveolin-1 and endothelial nitric oxide synthase expression on HPV. We also compared HPV using different perfusate solutions: Physiological salt solution (PSS) with albumin, Ficoll, rat blood, fetal bovine serum (FBS), or Dulbecco's Modified Eagle Medium (DMEM). After stabilization of the pulmonary arterial pressure (PAP), hypoxic (1% O2) and normoxic (21% O2) gases were applied via a ventilator in five-minute intervals to measure HPV. The addition of albumin or Ficoll with PSS did not induce persistent and strong HPV with or without a pretone agent. DMEM with the inclusion of FBS in the perfusate induced strong HPV in the first hypoxic challenge, but the HPV was neither persistent nor repetitive. PSS with rat blood only induced a small increase in HPV amplitude. Persistent and repetitive HPV occurred with PSS with 20% FBS as perfusate. HPV was significantly decreased by the removal of extracellular Ca(2+) along with addition of 1 mM EGTA to chelate residual Ca(2+) and voltage-dependent Ca(2+) channel blocker (nifedipine 1 ?M). PAP was also reactive to contractile stimulation by high K(+) depolarization and U46619 (a stable analogue of thromboxane A2). In summary, optimal conditions for measuring HPV were established in the isolated perfused/ventilated mouse lung. Using this method, we further confirmed that HPV is dependent on Ca(2+) influx. PMID:24015341

Yoo, Hae Young; Zeifman, Amy; Ko, Eun A; Smith, Kimberly A; Chen, Jiwang; Machado, Roberto F; Zhao, You-Yang; Minshall, Richard D; Yuan, Jason X-J

2013-04-01

19

Unusual ventilation perfusion scintigram in a case of immunologic pulmonary edema clinically simulating pulmonary embolism  

SciTech Connect

A case of immunologic pulmonary edema secondary to hydrochlorothiazide allergy developed in a 55-year-old woman that clinically simulated pulmonary embolism. The patient had abnormal washin images with normal washout images on an Xe-133 ventilation study. On the perfusion study, large bilateral central and posterior perfusion defects were present that showed an unusual mirror image pattern on the lateral and posterior oblique views. Resolution of radiographic and scintigraphic abnormalities occurred over a 3-day period in conjunction with corticosteroid therapy.

Campeau, R.J.; Faust, J.M.; Ahmad, S.

1987-11-01

20

Interaction of formaldehyde with glutathione in the isolated/ventilated perfused lung and the isolated perfused liver  

SciTech Connect

The interaction of formaldehyde (CH/sub 2/O) with reduced glutathione (GSH) was evaluated in aqueous solution and in isolated perfused lungs and livers. Addition of CH/sub 2/O (0-4.9 mM) to a solution of 0.17 mM GSH in 2 mM EDTA, pH 7.4, resulted in a time- and concentration-dependent depletion of GSH. Perfusion of livers with fortified Krebs-Ringer bicarbonate buffer containing 0.3-4.9 mM CH/sub 2/O resulted in a dose-dependent depletion of GSH. Perfusion of isolated ventilated lungs with perfusate containing 4.9 mM CH/sub 2/O resulted in a depletion of GSH to 75% of controls. However, lower concentrations of CH/sub 2/O in the lung perfusate did not result in depletion of GSH. These results demonstrate that exposure ito CH/sub 2/O in aqueous solution or in the perfused lung and liver is capable of depleting endogenous GSH. However, the concentrations of CH/sub 2/O required to yield a significant depletion of endogenous GSH exceed those encountered in vivo. Thus it is unlikely that depletion of GSH by CH/sub 2/O is a causal factor in formaldehyde-induced toxicity.

Ayres, P.H.; Marshall, T.C.; Sun, J.D.; Bond, J.A.; Hobbs, C.H.

1985-01-01

21

A General Approach to the Evaluation of Ventilation-Perfusion Ratios in Normal and Abnormal Lungs  

ERIC Educational Resources Information Center

Outlines methods for manipulating multiple gas data so as to gain the greatest amount of insight into the properties of ventilation-perfusion distributions. Refers to data corresponding to normal and abnormal lungs. Uses a two-dimensional framework with the respiratory gases of oxygen and carbon dioxide. (CS)

Wagner, Peter D.

1977-01-01

22

Lung Ventilation\\/Perfusion SPECT: The Right Technique for Hard Times  

Microsoft Academic Search

One of the main problems encoun- tered in the analysis of ventilation\\/per- fusion (V\\/P) lung scans for the diag- nosis of pulmonary embolism (PE) is difficulty in assessing the size of the perfusion defect, which then influences the probabilistic classification de- scribed in the Prospective Investiga- tion of Pulmonary Embolism Diagno- sis (PIOPED) study (1). In the original study, high

Michel A. Meignan; Hôpital Henri Mondor

23

Evaluation of pulmonary perfusion in lung regions showing isolated xenon-133 ventilation washout defects  

SciTech Connect

Xenon-133 washout phase imaging is often used to help determine whether the etiology of a perfusion defect is embolic or due to pulmonary parenchymal pathology, such as chronic obstructive pulmonary disease. This study was designed to evaluate the pulmonary blood flow patterns associated with isolated defects on xenon washout images. Scintigraphic lung studies were reviewed until 100 cases with abnormal ventilation results were obtained. Ventilation abnormalities were compared with the corresponding perfusion scan results at the same anatomic site. Of the 208 individual lung regions with xenon abnormalities, 111 showed isolated washout defects (that is, with normal washin). Ninety-four of these 111 sites showed either normal perfusion or a small, nonsegmental corresponding perfusion defect. Three segmental perfusion defects were noted in association with isolated xenon retention. In each of these cases, however, the patient was felt actually to have pulmonary embolism. Thus, it is recommended that, for interpretation of scintigraphic images in the assessment of pulmonary embolism, lung pathology associated with isolated xenon retention not be considered a potential cause for large or segmental perfusion defects.

Bushnell, D.L.; Sood, K.B.; Shirazi, P.; Pal, I. (VA Hines Hospital, IL (USA))

1990-08-01

24

Myocardial perfusion as assessed by thallium-201 scintigraphy during the discontinuation of mechanical ventilation in ventilator-dependent patients  

SciTech Connect

Patients who cannot be separated from mechanical ventilation (MV) after an episode of acute respiratory failure often have coexisting coronary artery disease. The authors hypothesized that increased left ventricular (LV) wall stress during periods of spontaneous ventilation (SV) could alter myocardial perfusion in these patients. Using thallium-201 (201TI) myocardial scintigraphy, the authors studied the occurrence of myocardial perfusion abnormalities during periods of SV in 15 MV-dependent patients (nine women, six men; aged 71 {plus minus} 7 yr, mean {plus minus} SD). Fourteen of these patients were studied once with 201TI myocardial scintigraphy during intermittent mechanical ventilation (IMV) and again on another day, after at least 10 min of SV through a T-piece. One patient was studied during SV only. Thirteen of 14 of the patients (93%) studied during MV had abnormal patterns of initial myocardial 201TI uptake, but only 1 patient demonstrated redistribution of 201TI on delayed images. The remainder of the abnormalities observed during MV were fixed defects. SV produced significant alterations of myocardial 201TI distribution or transient LV dilation, or both, in 7 of the 15 patients (47%). Four patients demonstrated new regional decreases of LV myocardial thallium concentration with redistribution of the isotope on delayed images. The patient studied only during SV also had myocardial 201TI defects with redistribution. Five patients (3 also having areas of 201TI redistribution) had transient LV dilation during SV.

Hurford, W.E.; Lynch, K.E.; Strauss, H.W.; Lowenstein, E.; Zapol, W.M. (Department of Anesthesia, Harvard Medical School, Massachusetts General Hospital, Boston (USA))

1991-06-01

25

Electrical impedance tomography: the holy grail of ventilation and perfusion monitoring?  

PubMed

This review summarizes the state-of-the-art in electrical impedance tomography (EIT) for ventilation and perfusion imaging. EIT is a relatively new technology used to image regional impedance distributions in a cross-sectional area of the body. After the introduction, a brief overview of the recent history is provided followed by a review of the literature on regional ventilation monitoring using EIT. Several recently presented indices that are useful to extract information from EIT image streams are described. Selected experimental and clinical findings are discussed with respect to future routine applications in intensive care. Finally, past and ongoing research activities aimed at obtaining cardiac output and regional perfusion information from EIT image streams are summarized. PMID:22992946

Leonhardt, Steffen; Lachmann, Burkhard

2012-12-01

26

Reduction of mismatch of global ventilation and perfusion on exercise is related to exercise capacity in chronic heart failure  

Microsoft Academic Search

BACKGROUND--The inability to match lung perfusion to ventilation because of a reduced cardiac output on exercise contributes to reduced exercise capacity in chronic heart failure. OBJECTIVE--To quantify ventilation to perfusion matching at rest and at peak exercise in patients with chronic heart failure and relate this to haemodynamic and ventilatory variables of exercise capacity. DESIGN--Eight men in New York Heart

N G Uren; S W Davies; J E Agnew; A G Irwin; S L Jordan; A J Hilson; D P Lipkin

1993-01-01

27

Non-invasive assessment of shunt and ventilation\\/perfusion ratio in neonates with pulmonary failure  

Microsoft Academic Search

AIMSTo make non-invasive measurements of right to left (R-L) shunt and reduced ventilation\\/perfusion ratio (VA\\/Q) in neonates with pulmonary failure and to examine sequential changes in these variables after treatment.METHODSTwelve neonates with pulmonary failure were studied. They ranged in gestational age from 24 to 37 (median 27) weeks and were 1–39 (median 4) days old. Shunt and reduced VA\\/Q were

H L Smith; J G Jones

2001-01-01

28

Ventilation/Perfusion Imaging in a Rat Model of Airway Obstruction  

PubMed Central

The global increase in asthma, chronic obstructive pulmonary disease, and other pulmonary diseases has stimulated interest in rat models of pulmonary disease. Imaging methods for study of these models is particularly appealing, since the results can be translated to the clinical setting. Comprehensive understanding of lung function can be achieved by performing registered pulmonary ventilation and perfusion imaging studies in the same animal. While ventilation imaging has been addressed for small animals, quantitative pulmonary perfusion imaging has not been feasible until recently with our proposed technique for quantitative perfusion imaging using multiple contrast agent injections and a view-sharing radial imaging technique. Here, we combine the method with registered ventilation imaging using hyperpolarized 3He in an airway obstruction rodent model. To our knowledge, this is the first comprehensive quantitative assessment of lung function in small animals at high spatial resolution. Standard deviation of the Log (V/Q) is used as a quantitative biomarker to differentiate heterogeneity between the control and treatment group. The estimated value of the biomarker lies with the normal range of values reported in the literature. The biomarker that was extracted using the imaging technique described in this work showed statistically significant differences between the control rats and those with airway obstruction.

Mistry, Nilesh N.; Qi, Yi; Hedlund, Laurence W.; Johnson, G. Allan

2009-01-01

29

Ventilation-perfusion lung scanning in patients detected by a screening program for early lung carcinoma  

SciTech Connect

Ventilation-perfusion (V-P) lung scans obtained in 114 patients in a screening program for the early detection of lung cancer were reviewed, and abnormalities were correlated with radiographic and surgical findings. Eighty-seven patients eventually had a tissue diagnosis of carcinoma; 65 (75%) had a perfusion defect and 56 (67%) had a ventilation abnormality at the tumor site. Lobar or segmental perfusion abnormalities were present at the tumor site in two of 13 patients whose lung cancer could not be localized by chest radiographs. However, 12 of these 13 patients and 54% of those with radiographically visible lesions had perfusion abnormalities in other lung regions. Twenty-seven patients with suspected carcinoma who were subsequently proved to have benign lesions had V-P abnormalities similar to those in patients with lung cancer. Thus, no pattern of V-P abnormalities allowed lung cancer in this screened population to be reliably distinguished from coexisting airway disease or nonmalignant pulmonary masses. V-P lung studies have a limited role in the early detection of lung cancer.

Katz, R.D.; Alderson, P.O.; Tockman, M.S.

1981-10-01

30

Deep Hypothermic Circulatory Arrest with Lung Perfusion/Ventilation in a Patient with Acute Type A Aortic Dissection  

PubMed Central

A 50-year-old black male presented with acute type A aortic dissection. Surgical repair was performed under deep hypothermic circulatory arrest (DHCA) with lung perfusion/ventilation throughout the procedure. Details of the lung perfusion technique and its potential benefits and drawbacks are discussed.

Rodriguez-Blanco, Yiliam F.; Garcia, Lester; Brice, Tania; Ricci, Marco; Salerno, Tomas A.

2012-01-01

31

Ventilation-perfusion relationships in the lung during head-out water immersion  

NASA Technical Reports Server (NTRS)

Mechanisms of altered pulmonary gas exchange during water immersion were studied in 12 normal males: 6 young (aged 20-29) and 6 older (aged 40-45). It is concluded that, in young subjects with closing volume (CV) less than expiratory reserve volume (ERV), gas exchange was enhanced during immersion, because normal ventilation-perfusion relations were preserved, and by mass balance, the ventilation/O2 uptake changes elevated arterial P(O2). In older males with CV greater than ERV and 52 percent of tidal volume below CV, immersion-induced airways closure during tidal breathing was associated with minimally increased shunt that did not significantly impair gas exchange. It is suggested that airways closure of this degree is of little importance to gas exchange.

Derion, Toniann; Guy, Harold J. B.; Tsukimoto, Koichi; Schaffartzik, Walter; Prediletto, Renato; Poole, David C.; Knight, Douglas R.; Wagner, Peter D.

1992-01-01

32

Ventilation-perfusion scintigraphy in an adult with congenital unilateral hyperlucent lung  

SciTech Connect

A variety of congenital and acquired etiologies can give rise to the radiographic finding of a unilateral hyperlucent lung. An unusual case of congenital lobar emphysema diagnosed in a young adult following the initial discovery of a hyperexpanded, hyperlucent lung is reported. Although subsequent bronchoscopy and radiologic studies detailed extensive anatomic abnormalities, functional imaging also played an important role in arriving at this rare diagnosis. In particular, ventilation-perfusion scintigraphy identified the small contralateral lung as the functional lung and helped narrow the differential diagnosis to etiologies involving obstructive airway disorders.

Wegener, W.A.; Velchik, M.G. (Hospital of the University of Pennsylvania, Philadelphia (USA))

1990-10-01

33

Ventilation-perfusion heterogeneity and gas exchange variables in acute pulmonary embolism evaluated by two different computerized techniques.  

PubMed

The mechanisms by which the disturbances of gas exchange develop in human pulmonary embolism are unknown. We investigated whether the inequality of ventilation-perfusion ratio is associated with the abnormalities of pulmonary gas exchange as evaluated by two different computerized techniques. We measured the alveolar to arterial gradients of oxygen and carbon dioxide by means of a computer based system with a mass spectrometer and the ventilation-perfusion distributions by the multiple inert gas technique in 5 patients with acute pulmonary embolism. In these subjects there was a marked ventilation-perfusion inhomogeneity, as detected from inert gases and this finding was in agreement with the impairment of the alveolar to arterial gradients and of their derived indexes. Consideration on the responsible mechanisms for the disturbances of gas exchange are also reported. In conclusion these two computerized techniques provide a useful assessment of the ventilation-perfusion relationships in order to explain the disturbances of gas exchange in critically ill patients. PMID:3071566

Prediletto, R; Formichi, B; Begliomini, E; Fornai, E; Viegi, G; Ruschi, S; Paoletti, P; Giannella, A N; Santolicandro, A; Giuntini, C

1988-01-01

34

[Pulmonary perfusion, ventilation, and gas exchange during modified cobalt-60 teletherapy of operated on breast carcinomas].  

PubMed

Post ablationem mammae, 22 patients were exposed to a modified telecobalt-irradiation because of mammary carcinoma. (Tangential pendulum irradiation of the thoracic wall with deflection of the central beam off the pendulum axis, parasternal irradiation with pendulum fields, irradiation of the supraclavicular and axillar area with deflection of the central beam to lateral and cranial directions.) During radiation therapy and up to six months after its termination, periodical pulmonary function tests were accomplished, consisting in a radiogram of the thorax, in spirometric check-up and blood gas analysis, and in an examination of pulmonary perfusion and ventilation using radionuclide techniques. In one patient with metastases to the ribs, the spirographic and nulear-medical ventilatory results changed for the worse in the course of time, whereas the other 21 patients did not show any significantly abnormal alterations at follow-up examinations. PMID:1209678

Schlick, W; Imhof, H; Peloschek, P; Sabitzer, H; Czembirek, H; Mayrhofer, P

1975-12-01

35

Effects of carbonic anhydrase inhibition on ventilation-perfusion matching in the dog lung.  

PubMed Central

Lung carbonic anhydrase (CA) permits rapid pH responses when changes in regional ventilation or perfusion alter airway and alveolar PCO2. These pH changes affect airway and vascular resistances and lung compliance to optimize the balance of regional ventilation (VA) and perfusion (Q) in the lung. To test the hypothesis that these or other CA-dependent mechanisms contribute to VA/Q matching, we administered acetazolamide (25 mg/kg intravenously) to six anesthetized and paralyzed dogs and measured VA/Q relationships before and after CA inhibition by the multiple inert gas elimination technique. Four other groups of dogs were studied to control for possible confounding effects of time under anesthesia and nonselective CA inhibition by acetazolamide: (a) saline placebo as a control for duration of anesthesia, (b) 4% CO2 inhalation to mimic systemic CO2 retention, (c) 1 mg/kg benzolamide (a selective renal CA inhibitor) or 0.5 meq/kg HCl to mimic systemic metabolic acidosis, and (d) 500 mg/kg 4,4'-dinitrostilbene-2,2'-disulfonate (an inhibitor of red cell band 3 protein) to mimic the respiratory acidosis arising from an intracapillary block to rapid mobilization of plasma HCO3- in CO2 exchange. Acetazolamide increased VA/Q mismatch and reduced arterial PO2 measured at equilibrium but these did not occur in the control group. There was no deterioration in VA/Q matching when systemic respiratory acidosis produced either by CO2 inhalation or 4,4'-dinitrostilbene-2,2'-disulfonate or metabolic acidosis (benzolamide or HCl) were imposed to mimic the effects of acetazolamide apart from its inhibition of lung CA. These results support the concept that lung CA subserves VA/Q matching in the normal lung. Images

Swenson, E R; Robertson, H T; Hlastala, M P

1993-01-01

36

Validation of measurements of ventilation-to-perfusion ratio inequality in the lung from expired gas  

NASA Technical Reports Server (NTRS)

The analysis of the gas in a single expirate has long been used to estimate the degree of ventilation-perfusion (Va/Q) inequality in the lung. To further validate this estimate, we examined three measures of Va/Q inhomogeneity calculated from a single full exhalation in nine anesthetized mongrel dogs under control conditions and after exposure to aerosolized methacholine. These measurements were then compared with arterial blood gases and with measurements of Va/Q inhomogeneity obtained using the multiple inert gas elimination technique. The slope of the instantaneous respiratory exchange ratio (R slope) vs. expired volume was poorly correlated with independent measures, probably because of the curvilinear nature of the relationship due to continuing gas exchange. When R was converted to the intrabreath Va/Q (iV/Q), the best index was the slope of iV/Q vs. volume over phase III (iV/Q slope). This was strongly correlated with independent measures, especially those relating to inhomogeneity of perfusion. The correlations for iV/Q slope and R slope considerably improved when only the first half of phase III was considered. We conclude that a useful noninvasive measurement of Va/Q inhomogeneity can be derived from the intrabreath respiratory exchange ratio.

Prisk, G. Kim; Guy, Harold J B.; West, John B.; Reed, James W.

2003-01-01

37

Continuous Distributions of Ventilation-Perfusion Ratios in Normal Subjects Breathing Air and 100% O2  

PubMed Central

A new method has been developed for measuring virtually continuous distributions of ventilation-perfusion ratios (V?A/Q?) based on the steadystate elimination of six gases of different solubilities. The method is applied here to 12 normal subjects, aged 21—60. In nine, the distributions were compared breathing air and 100% oxygen, while in the remaining three, effects of changes in posture were examined. In four young semirecumbent subjects (ages 21—24) the distributions of blood flow and ventilation with respect to V?A/Q? were virtually log-normal with little dispersion (mean log standard deviations 0.43 and 0.35, respectively). The 95.5% range of both blood flow and ventilation was from V?A/Q? ratios of 0.3—2.1, and there was no intrapulmonary shunt (V?A/Q? of 0). On breathing oxygen, a shunt developed in three of these subjects, the mean value being 0.5% of the cardiac output. The five older subjects (ages 39—60) had broader distributions (mean log standard deviations, 0.76 and 0.44) containing areas with V?A/Q ratios in the range 0.01—0.1 in three subjects. As for the young subjects, there was no shunt breathing air, but all five developed a shunt breathing oxygen (mean value 3.2%), and in one the value was 10.7%. Postural changes were generally those expected from the known effects of gravity, with more ventilation to high VA/Q areas when the subjects were erect than supine. Measurements of the shunt while breathing oxygen, the Bohr CO2 dead space, and the alveolar-arterial oxygen difference were all consistent with the observed distributions. Since the method involves only a short infusion of dissolved inert gases, sampling of arterial blood and expired gas, and measurement of cardiac output and minute ventilation, we conclude that it is well suited to the investigation of pulmonary gas exchange in man.

Wagner, Peter D.; Laravuso, Raymond B.; Uhi, Richard R.; West, John B.

1974-01-01

38

Spatial correspondence of 4D CT ventilation and SPECT pulmonary perfusion defects in patients with malignant airway stenosis  

NASA Astrophysics Data System (ADS)

To determine the spatial overlap agreement between four-dimensional computed tomography (4D CT) ventilation and single photon emission computed tomography (SPECT) perfusion hypo-functioning pulmonary defect regions in a patient population with malignant airway stenosis. Treatment planning 4D CT images were obtained retrospectively for ten lung cancer patients with radiographically demonstrated airway obstruction due to gross tumor volume. Each patient also received a SPECT perfusion study within one week of the planning 4D CT, and prior to the initiation of treatment. Deformable image registration was used to map corresponding lung tissue elements between the extreme component phase images, from which quantitative three-dimensional (3D) images representing the local pulmonary specific ventilation were constructed. Semi-automated segmentation of the percentile perfusion distribution was performed to identify regional defects distal to the known obstructing lesion. Semi-automated segmentation was similarly performed by multiple observers to delineate corresponding defect regions depicted on 4D CT ventilation. Normalized Dice similarity coefficient (NDSC) indices were determined for each observer between SPECT perfusion and 4D CT ventilation defect regions to assess spatial overlap agreement. Tidal volumes determined from 4D CT ventilation were evaluated versus measurements obtained from lung parenchyma segmentation. Linear regression resulted in a linear fit with slope = 1.01 (R2 = 0.99). Respective values for the average DSC, NDSC1 mm and NDSC2 mm for all cases and multiple observers were 0.78, 0.88 and 0.99, indicating that, on average, spatial overlap agreement between ventilation and perfusion defect regions was comparable to the threshold for agreement within 1-2 mm uncertainty. Corresponding coefficients of variation for all metrics were similarly in the range: 0.10%-19%. This study is the first to quantitatively assess 3D spatial overlap agreement between clinically acquired SPECT perfusion and specific ventilation from 4D CT. Results suggest high correlation between methods within the sub-population of lung cancer patients with malignant airway stenosis.

Castillo, Richard; Castillo, Edward; McCurdy, Matthew; Gomez, Daniel R.; Block, Alec M.; Bergsma, Derek; Joy, Sarah; Guerrero, Thomas

2012-04-01

39

Platelet-activating factor causes ventilation-perfusion mismatch in humans.  

PubMed Central

We hypothesized that platelet-activating factor (PAF), a potent inflammatory mediator, could induce gas exchange abnormalities in normal humans. To this end, the effect of aerosolized PAF (2 mg/ml solution; 24 micrograms) on ventilation-perfusion (VA/Q) relationships, hemodynamics, and resistance of the respiratory system was studied in 14 healthy, nonatopic, and nonsmoking individuals (23 +/- 1 [SEM]yr) before and at 2, 4, 6, 8, 15, and 45 min after inhalation, and compared to that of inhaled lyso-PAF in 10 other healthy individuals (24 +/- 2 yr). PAF induced, compared to lyso-PAF, immediate leukopenia (P < 0.001) followed by a rebound leukocytosis (P < 0.002), increased minute ventilation (P < 0.05) and resistance of the respiratory system (P < 0.01), and decreased systemic arterial pressure (P < 0.05). Similarly, compared to lyso-PAF, PaO2 showed a trend to fall (by 12.2 +/- 4.3 mmHg, mean +/- SEM maximum change from baseline), and arterial-alveolar O2 gradient increased (by 16.7 +/- 4.3 mmHg) (P < 0.02) after PAF, because of VA/Q mismatch: the dispersion of pulmonary blood flow and that of ventilation increased by 0.45 +/- 0.1 (P < 0.01) and 0.29 +/- 0.1 (P < 0.04), respectively. We conclude that in normal subjects, inhaled PAF results in considerable immediate VA/Q inequality and gas exchange impairment. These results reinforce the notion that PAF may play a major role as a mediator of inflammation in the human lung. Images

Rodriguez-Roisin, R; Felez, M A; Chung, K F; Barbera, J A; Wagner, P D; Cobos, A; Barnes, P J; Roca, J

1994-01-01

40

Immunotargeting of the pulmonary endothelium via angiotensin-converting-enzyme in isolated ventilated and perfused human lung.  

PubMed

Vascular immunotargeting of catalase via angiotensin-converting-enzyme (ACE) attenuated lung ischemia reperfusion injury in the rat. As this might be a promising modality for extension of the viability of human lung grafts for transplantation we tested the hypothesis whether anti-ACE antibodies are suitable for human lung protection within the model of isolated perfused and ventilated human lung resections. Right after surgery for lung cancer, human lung specimens were isolated, ventilated and perfused under physiological conditions with 500 ?g of either mouse monoclonal antibodies (mAb) to human ACE (9B9, I2H5, 3G8) or non-immune mouse IgG (as a negative control) followed by wash-out perfusion. Perfusion pressure, pH and lung weight gain were measured before and during perfusion. After mAb perfusion and wash-out perfusion period lung tissue was tested for the uptake of mAbs by immunohistochemistry and by enzyme-capture technique. Furthermore, antibody concentration and ACE shedding were measured within the perfusate. We found that ACE activity in tumor and normal lung tissue did not differ between the groups perfused with different mAbs. However, ACE activity in normal lung tissue (17.0 ± 6.0 U/g) was significantly higher compared to tumor tissue (6.0 ± 3.0; p < 0.01). Absolute retaining of mAbs was with 1.3 ± 1.1% of injected dose per gram of tissue in normal lung tissue, 0.7 ± 0.7% of injected dose per gram of tumor tissue and was significantly higher compared to non-immune mouse IgG (0.1 ± 0.1%/g; p < 0.01). Anti-ACE mAbs concentration in the perfusate dropped significantly to 47 ± 11% (p < 0.001) at 40 min of perfusion. No significant difference between different anti-ACE mAbs in the depletion from perfusate has been observed. mAb 9B9 showed the most intense immunostaining (i.e., most significant lung uptake) after each experiment in normal and tumor lung tissue compared to mAbs i2H5 and 3G8 (p < 0.01). These results validate the possibility of immunotargeting of pulmonary endothelium in the human lung tissue by anti-ACE mAbs under in vivo conditions. Furthermore, the model might be useful to investigate targeted therapies in lung cancer without side effects for the patient. PMID:22836637

Nowak, Kai; Kölbel, Hans C; Metzger, Roman P; Hanusch, Christine; Frohnmeyer, Marc; Hohenberger, Peter; Danilov, Siergiej M

2013-01-01

41

N-acetylcysteine attenuates ventilator-induced lung injury in an isolated and perfused rat lung model.  

PubMed

N-acetylcysteine (NAC) suppresses the generation of reactive oxygen species (ROS) that are implicated in ventilator-induced lung injury (VILI). We thus hypothesised that NAC attenuates VILI. VILI was induced by mechanical ventilation with a tidal volume (Vt) of 15mlkg(-1) in isolated and perfused rat lung. NAC was administered in the perfusate prior to the onset of mechanical ventilation. A group ventilated with low Vt of 5mlkg(-1) served as control. Haemodynamics, lung injury indices, inflammatory responses and activation of apoptotic pathways were determined upon completion of the mechanical ventilation. There was an increase in lung permeability and lung weight gain after mechanical ventilation with high Vt, compared to low Vt. The levels of inflammatory cytokines including interleukin-1? (IL-1?), tumour necrosis factor-? (TNF-?) and macrophage inflammatory protein-2 (MIP-2) increased in lung lavage fluids; the concentrations of H(2)O(2) were higher in lung lavage fluids, and the expression of myeloperoxidase (MPO), JNK, P38, pAKT and caspase-3 in lung tissue was greater in the high Vt than in the low Vt group. The concentrations of glutathione (GSH) in lung tissue were higher in low Vt than those in high Vt. The administration of NAC increased GSH, attenuated ROS, cytokines, MPO, JNK, pAKT and caspase-3 and lung permeability associated with decreased activation of nuclear factor-?B. VILI is associated with inflammatory responses including the generation of ROS, cytokines and the activation of mitogen-activated protein kinase cascade. The administration of NAC attenuates the inflammatory responses, apoptosis and VILI in the isolated, perfused rat lung model. PMID:22336129

Chiang, Chi-Huei; Chuang, Chiao-Hui; Liu, Shiou-Ling; Chian, Chih-Feng; Zhang, Haibo; Ryu, Jay H

2012-08-01

42

Alveolar ventilation to perfusion heterogeneity and diffusion impairment in a mathematical model of gas exchange  

NASA Technical Reports Server (NTRS)

This study describes a two-compartment model of pulmonary gas exchange in which alveolar ventilation to perfusion (VA/Q) heterogeneity and impairment of pulmonary diffusing capacity (D) are simultaneously taken into account. The mathematical model uses as input data measurements usually obtained in the lung function laboratory. It consists of two compartments and an anatomical shunt. Each compartment receives fractions of alveolar ventilation and blood flow. Mass balance equations and integration of Fick's law of diffusion are used to compute alveolar and blood O2 and CO2 values compatible with input O2 uptake and CO2 elimination. Two applications are presented. The first is a method to partition O2 and CO2 alveolar-arterial gradients into VA/Q and D components. The technique is evaluated in data of patients with chronic obstructive pulmonary disease (COPD). The second is a theoretical analysis of the effects of blood flow variation in alveolar and blood O2 partial pressures. The results show the importance of simultaneous consideration of D to estimate VA/Q heterogeneity in patients with diffusion impairment. This factor plays an increasing role in gas alveolar-arterial gradients as severity of COPD increases. Association of VA/Q heterogeneity and D may produce an increase of O2 arterial pressure with decreasing QT which would not be observed if only D were considered. We conclude that the presented computer model is a useful tool for description and interpretation of data from COPD patients and for performing theoretical analysis of variables involved in the gas exchange process.

Vidal Melo, M. F.; Loeppky, J. A.; Caprihan, A.; Luft, U. C.

1993-01-01

43

Ventilation-perfusion heterogeneity and gas exchange variables in acute pulmonary embolism evaluated by two different computerized techniques  

Microsoft Academic Search

Summary  The mechanisms by which the disturbances of gas exchange develop in human pulmonary embolism are unknown. We investigated\\u000a whether the inequality of ventilation-perfusion ratio is associated with the abnormalities of pulmonary gas exchange as evaluated\\u000a by two different computerized techniques. We measured the alveolar to arterial gradients of oxygen and carbon dioxide by means\\u000a of a computer based system with

R. Prediletto; B. Formichi; E. Begliomini; E. Fornai; G. Viegi; S. Ruschi; P. Paoletti; A. N. Giannella; A. Santolicandro; C. Giuntini

1988-01-01

44

Krypton 81m ventilation/perfusion ratios (V/Q) measured in lateral decubitus in pulmonary embolism (P. E. )  

SciTech Connect

In normal subjects lateral decubitis induces in both independent (lower) and nondependent lung (upper), major changes in perfusion, ventilation and V/Q ratios which can be studied with the short life radioisotope Krypton 81m. Regional V/Q are computed from ventilation and perfusion scans, successively obtained with a gamma camera linked to a computer by continuous inhalation or infusion of this gas during tidal breathing. They were displayed as a color coded functional image. To assess the effect of posture on V/Q in P.E. and other diseases which decrease the regional perfusion, 32 patients with unilateral lung diseases were studied in supine posture and both lateral decubitis: 8 with proved P.E., (3 out of them having radiological opacity matching the perfusion defect), 9 with bullous emphysema, 6 with bronchogenic carcinoma, 9 with acute bacterial pneumonia. V/Q were computed in the region of the perfusion defect. In P.E. the mean V/Q was high (1.92 +- 0.6 SD), and did not change whatever the posture. Conversely major changes of V/Q were induced with postural changes in bullous emphysema and lung carcinoma whatever the V/Q in patient supine. In pneumonia low V/Q were observed in supine posture (.73 +- .2). They decreased significantly when the pneumonia was dependent (.53 +- .2 p < 0.02) and increased in the controlateral decubitis (1.07 +- .3, p < 0.001). Since posture has no or little effect on regional V/Q in P.E., it can be used to discriminate P.E., even in the case of radiological opacity, from other unilateral disease inducing perfusion defect.

Meignan, M.; Cinotti, L.; Harf, A.; Oliveira, L.; Simonneau, G.

1984-01-01

45

A Short Period of Ventilation without Perfusion Seems to Reduce Atelectasis without Harming the Lungs during Ex Vivo Lung Perfusion  

PubMed Central

To evaluate the lung function of donors after circulatory deaths (DCDs), ex vivo lung perfusion (EVLP) has been shown to be a valuable method. We present modified EVLP where lung atelectasis is removed, while the lung perfusion is temporarily shut down. Twelve pigs were randomized into two groups: modified EVLP and conventional EVLP. When the lungs had reached 37°C in the EVLP circuit, lung perfusion was temporarily shut down in the modified EVLP group, and positive end-expiratory pressure (PEEP) was increased to 10?cm H2O for 10 minutes. In the conventional EVLP group, PEEP was increased to 10?cm H2O for 10 minutes with unchanged lung perfusion. In the modified EVLP group, the arterial oxygen partial pressure (PaO2) was 18.5 ± 7.0?kPa before and 64.5 ± 6.0?kPa after the maneuver (P < 0.001). In the conventional EVLP group, the PaO2 was 16.8 ± 3.1?kPa and 46.8 ± 2.7?kPa after the maneuver (P < 0.01; P < 0.01). In the modified EVLP group, the pulmonary graft weight was unchanged, while in the conventional EVLP group, the pulmonary graft weight was significantly increased. Modified EVLP with normoventilation of the lungs without ongoing lung perfusion for 10 minutes may eliminate atelectasis almost completely without harming the lungs.

Pierre, Leif

2013-01-01

46

Interaction of formaldehyde with glutathione in the isolated\\/ventilated perfused lung and the isolated perfused liver  

Microsoft Academic Search

The interaction of formaldehyde (CH2O) with reduced glutathione (GSH) was evaluated in aqueous solution and in isolated perfused lungs and livers. Addition of CH2O (0–4.9 mM) to a solution of 0.17 mM GSH in 2 mM EDTA, pH 7.4, resulted in a time? and concentration?dependent depletion of GSH. Perfusion of livers with fortified Krebs?Ringer bicarbonate buffer containing 0.3–4.9 mM CH2O

Paul H. Ayres; Thomas C. Marshall; James D. Sun; James A. Bond; Charles H. Hobbs

1985-01-01

47

[Pulmonary Blood Flow Measurement using Magnetic Resonance Imaging (MRI) without Contrast Medium;Comparison of Phase Contrast MRI and Perfusion-ventilation Scintigraphy].  

PubMed

To define the accuracy of pulmonary arterial blood flow (PA-flow) measured by phase contrast magnetic resonance imaging (PC-MRI), we compared the PA-flow data of PC-MRI with the data of perfusion-ventilation lung scintigraphy. Eighteen patients who preoperatively underwent PA-flow measurement using PC-MRI and perfusion-ventilation lung scintigraphy were evaluated. The PA-flow (cm3/sec) of MRI was calculated by multiplying maximum velocity (cm/sec) by region of interest (ROI) area (cm2) of measured main pulmonary artery using phase contrast method. The left to right ratio (R/L ratio) of PA-flow measured by PC-MRI was compared with the R/L ratios of the date of perfusion-ventilation lung scintigraphy. The R/L ratios of PC-MRI and perfusion lung scintigraphy were 1.43 ± 1.07 and 1.35 ± 0.82, respectively. Both ratios showed excellent correlation( y=-0.50+1.30x, r=0.99,p<0.001). The R/L ratios of PC-MRI also approximated to those of perfusion lung scintigraphy in the patients with a past history of lung resection, even if their R/L ratios of perfusion lung scintigraphy differed from those of ventilation lung scintigraphy. These results revealed that the PA-flow could be accurately measured by PC-MRI without contrast medium and nuclear medicine instruments. PMID:24743476

Yatsuyanagi, Eiji; Sato, Kazuhiro; Kikuchi, Keisuke; Saito, Hirotsugu

2014-02-01

48

The natural history of venous thromboembolism: impact on ventilation/perfusion scan reporting.  

PubMed

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are separate but related aspects of the same dynamic disease process known as venous thromboembolism (VTE). Recent community studies have shown that VTE is a major health issue for the developed world, with at least 201,000 new cases each year in the United States, comprising 107,000 with DVT and 94,000 with PE. A quarter of PE cases die within 7 days, some so rapidly that treatment or intervention is impossible. Despite the availability of heparin prophylaxis, the annual incidence of VTE has remained constant at 1 event per 1,000 person-years since 1979 but reaches 1 event per 100 person-years for the over-85-year-olds. The most important risk factors for VTE are hemostatic and environmental. The recent discoveries of factor V Leiden, prothrombin 20210A, and high concentrations of factor VIII have highlighted the increasing importance of a genetic predisposition to thrombophilia. Acquired hemostatic factors include pregnancy and the puerperium, oral contraception, hormone-replacement therapy, malignant tumors, and antiphospholipid syndromes. Important environmental risk factors include hospitalization with previous surgery or trauma, confinement in a care facility, neurologic disease or paraplegia after stroke, current or recent central venous catheter or transvenous pacemaker, and long airplane flights. Internists may be confused about the risk of PE after ventilation/perfusion (VQ) imaging. This may well arise from their use of the relative risk of PE after a low-probability category scan rather than the absolute risk obtained by incorporating the PE prevalence for their particular patient in the risk analysis. Ideally, personal communication with an experienced referring physician provides this clinical information for nuclear medicine. Diagnostic tools or checklists can be used as an alternative. A general knowledge of the natural history of VTE will encourage the nuclear medicine physician to provide an appropriate clinical signal to complement VQ categorical analysis. Combination of these 2 dynamic elements of the art and science of VQ scan reporting-the clinical pretest probability of PE and lung scan category-will permit an accurate prediction of the absolute risk of PE posttest. PMID:12105797

Gray, Henry W

2002-07-01

49

Measuring the weight of the isolated perfused rat lung during negative pressure ventilation  

Microsoft Academic Search

Weight measurement represents a means of quantitating edema formation in isolated lungs and following its time course. During ventilation by negative pressure measurements with commonly used weight transducers are impossible because the pressure changes inside the artificial thoracic chamber affect the weight reading. Therefore, we have developed a weight transducer that can be used during negative pressure ventilation. Its design

Stefan Uhlig; Ottmar Heiny

1995-01-01

50

Imaging of the three-dimensional alveolar structure and the alveolar mechanics of a ventilated and perfused isolated rabbit lung with Fourier domain optical coherence tomography  

Microsoft Academic Search

In this feasibility study, Fourier domain optical coherence tomography (FDOCT) is used for visualizing the 3-D structure of fixated lung parenchyma and to capture real-time cross sectional images of the subpleural alveolar mechanics in a ventilated and perfused isolated rabbit lung. The compact and modular setup of the FDOCT system allows us to image the first 500 µm of subpleural

Alexander Popp; Martina Wendel; Lilla Knels; Thea Koch; Edmund Koch

2006-01-01

51

Difference in the value of arterial and end-tidal carbon dioxide tension according to different surgical positions: Does it reliably reflect ventilation-perfusion mismatch?  

PubMed Central

Background Body posture, as a gravitational factor, has a clear impact on pulmonary ventilation and perfusion. In lung units with mismatched ventilation and perfusion, gas exchange and/or elimination of carbon dioxide can be impaired. In this situation, differences in the value of arterial and end-tidal carbon dioxide tension [?(PaCO2 - PETCO2)] are expected to increase. This study was conducted to observe how ?(PaCO2 - PETCO2) changed according to the 3 different surgical positions, and to determine whether ?(PaCO2 - PETCO2) is a reliable predictor of ventilation/perfusion mismatch when a patient is in different postural positions. Methods Fifty-nine patients were divided into either the chronic obstructive pulmonary disease (COPD) group (n = 29) or the non-COPD group (n = 30). PaCO2 and PETCO2 were measured during surgery in the supine, prone, and lateral decubitus positions after a 10 minute stabilization period. The ?(PaCO2 - PETCO2) were calculated and compared among positions. Results The ?(PaCO2 - PETCO2) decreased slightly in the prone position and increased significantly in the lateral decubitus position compared with the supine position in both groups. These patterns almost corresponded with the degree of ventilation/perfusion mismatch from the results of the radiological studies. The ?(PaCO2 - PETCO2) in the COPD group was significantly greater than that in the non-COPD group at all surgical positions. Conclusions Lateral decubitus position is associated with marked increase in ?(PaCO2 - PETCO2), especially in patients with COPD. The ?(PaCO2 - PETCO2) is a simple and reliable indicator to predict ventilation/perfusion mismatch at different surgical positions in patients with or without COPD.

Joo, Jin; Kim, Young Hee; Choi, Jong Ho

2012-01-01

52

The utility of the Wells clinical prediction model and ventilation-perfusion scanning for pulmonary embolism diagnosis in pregnancy.  

PubMed

Pulmonary embolism is one of the leading causes of mortality in pregnancy in the Western world. No clinical prediction models have been validated in pregnancy. As a result, any pregnant woman presenting with signs possibly consistent with pulmonary embolism is investigated radiologically. This study investigates whether using clinical prediction models for pulmonary embolism in pregnancy should be pursued in future prospective trials. The aim of this study was to retrospectively evaluate the Wells clinical prediction model and ventilation-perfusion scanning for pulmonary embolism in pregnancy. A retrospective study was performed on consecutive pregnant women who presented with suspected pulmonary emboli and underwent ventilation perfusion scanning at two tertiary institutions from 2007 until 2010. The clinical pretest probability was determined as likely or unlikely by two independent clinicians retrospectively using Wells-modified criteria. Scans were determined as normal, nondiagnostic or high probability for pulmonary emboli independently by two experienced radiologists. Disagreements were resolved by a third assessor independently. In 183 pregnant women, the pretest probability was determined as 'pulmonary emboli likely' in 76 (42%) and 'pulmonary emboli unlikely' in 107 (58%) of women. Scans were of high probability in four (2%), nondiagnostic in six (3%) and normal in 173 (95%) of women. This gives the pretest probability using Wells-modified criteria a sensitivity of 100% [95% confidence interval (CI) 0.4-1.0] and a negative predictive value of 100% (95% CI 0.96-1.0). A structured clinical model such as modified Wells criteria may be useful in pregnancy, but further prospective evaluation is required. PMID:24434350

Cutts, Briony A; Tran, Huyen A; Merriman, Eileen; Nandurkar, Dee; Soo, Gil; Dasgupta, Dhruba; Prassannan, Nita; Hunt, Beverley J

2014-06-01

53

Evaluation of pulmonary perfusion in lung regions showing isolated xenon-133 ventilation washout defects  

Microsoft Academic Search

Xenon-133 washout phase imaging is often used to help determine whether the etiology of a perfusion defect is embolic or due to pulmonary parenchymal pathology, such as chronic obstructive pulmonary disease. This study was designed to evaluate the pulmonary blood flow patterns associated with isolated defects on xenon washout images. Scintigraphic lung studies were reviewed until 100 cases with abnormal

DAVID L. BUSHNELL; KUL B. SOOD; PARVEZ SHIRAZI; INDRA PAL

1990-01-01

54

Lung ventilation- and perfusion-weighted Fourier decomposition magnetic resonance imaging: in vivo validation with hyperpolarized 3He and dynamic contrast-enhanced MRI.  

PubMed

The purpose of this work was to validate ventilation-weighted (VW) and perfusion-weighted (QW) Fourier decomposition (FD) magnetic resonance imaging (MRI) with hyperpolarized (3)He MRI and dynamic contrast-enhanced perfusion (DCE) MRI in a controlled animal experiment. Three healthy pigs were studied on 1.5-T MR scanner. For FD MRI, the VW and QW images were obtained by postprocessing of time-resolved lung image sets. DCE acquisitions were performed immediately after contrast agent injection. (3)He MRI data were acquired following the administration of hyperpolarized helium and nitrogen mixture. After baseline MR scans, pulmonary embolism was artificially produced. FD MRI and DCE MRI perfusion measurements were repeated. Subsequently, atelectasis and air trapping were induced, which followed with FD MRI and (3)He MRI ventilation measurements. Distributions of signal intensities in healthy and pathologic lung tissue were compared by statistical analysis. Images acquired using FD, (3)He, and DCE MRI in all animals before the interventional procedure showed homogeneous ventilation and perfusion. Functional defects were detected by all MRI techniques at identical anatomical locations. Signal intensity in VW and QW images was significantly lower in pathological than in healthy lung parenchyma. The study has shown usefulness of FD MRI as an alternative, noninvasive, and easily implementable technique for the assessment of acute changes in lung function. PMID:22392633

Bauman, Grzegorz; Scholz, Alexander; Rivoire, Julien; Terekhov, Maxim; Friedrich, Janet; de Oliveira, Andre; Semmler, Wolfhard; Schreiber, Laura Maria; Puderbach, Michael

2013-01-01

55

Non-invasive measurement of reduced ventilation:perfusion ratio and shunt in infants with bronchopulmonary dysplasia: a physiological definition of the disease  

Microsoft Academic Search

Background: An objective definition of bronchopulmonary dysplasia (BPD) is required to interpret trial outcomes and provide a baseline for prognostic studies. Current definitions do not quantify disease severity. The cardinal measures of impaired gas exchange are a reduced ventilation:perfusion ratio (VA:Q) and increased right to left shunt. These can be determined non-invasively by plotting arterial oxygen saturation (Spo2) against inspired

D Quine; C M Wong; E M Boyle; J G Jones; B J Stenson

2006-01-01

56

Role of spiral volumetric computed tomographic scanning in the assessment of patients with clinical suspicion of pulmonary embolism and an abnormal ventilation\\/perfusion lung scan  

Microsoft Academic Search

BACKGROUND: A study was carried out to evaluate the potential place of spiral volumetric computed tomography (SVCT) in the diagnostic strategy for pulmonary embolism. METHODS: In a prospective study 249 patients with clinical suspicion of pulmonary embolism were evaluated with various imaging techniques. In all patients a ventilation\\/perfusion (V\\/Q) scan was performed. Seventy seven patients with an abnormal V\\/Q scan

A. B. van Rossum; F. E. Treurniet; G. J. Kieft; S. J. Smith; R. Schepers-Bok

1996-01-01

57

Imaging of the three-dimensional alveolar structure and the alveolar mechanics of a ventilated and perfused isolated rabbit lung with Fourier domain optical coherence tomography  

NASA Astrophysics Data System (ADS)

In this feasibility study, Fourier domain optical coherence tomography (FDOCT) is used for visualizing the 3-D structure of fixated lung parenchyma and to capture real-time cross sectional images of the subpleural alveolar mechanics in a ventilated and perfused isolated rabbit lung. The compact and modular setup of the FDOCT system allows us to image the first 500 µm of subpleural lung parenchyma with a 3-D resolution of 16×16×8 µm (in air). During mechanical ventilation, real-time cross sectional FDOCT images visualize the inflation and deflation of alveoli and alveolar sacks (acini) in successive images of end-inspiratory and end-expiratory phase. The FDOCT imaging shows the relation of local alveolar mechanics to the setting of tidal volume (VT), peak airway pressure, and positive end-expiratory pressure (PEEP). Application of PEEP leads to persistent recruitment of alveoli and acini in the end-expiratory phase, compared to ventilation without PEEP where alveolar collapse and reinflation are observed. The imaging of alveolar mechanics by FDOCT will help to determine the amount of mechanical stress put on the alveolar walls during tidal ventilation, which is a key factor in understanding the development of ventilator induced lung injury (VILI).

Popp, Alexander; Wendel, Martina; Knels, Lilla; Koch, T.; Koch, Edmund

2006-01-01

58

Interactions among three classes of mediators explain antigen-induced bronchoconstriction in the isolated perfused and ventilated guinea pig lung.  

PubMed

Intravascular challenge of isolated perfused and ventilated guinea pig lung (IPL) from actively sensitized guinea pigs, with cumulatively increasing (10-10,000 microg) doses of ovalbumin (OVA), resulted in dose-dependent and reproducible reductions in lung conductance. The antihistamines mepyramine (1 microM) and metiamide (1 microM), the leukotriene antagonist zafirlukast (0.1 microM), or the cyclooxygenase enzyme (COX) inhibitor diclofenac (10 microM) each caused a parallel and rightward shift in the dose-response relation for OVA, providing evidence for contributions of histamine, cysteinyl-leukotrienes, and COX products to the OVA-induced bronchoconstriction in the IPL. Moreover, when all three drugs were combined there was a complete abolishment of the response to OVA. When two antagonists or inhibitors were combined, the results, however, were more complex. The 5-lipoxygenase inhibitor BAY x1005 (30 microM) and the thromboxane (TP) receptor antagonist BAY u3405 (1 microM) given as single treatment did not inhibit the response to OVA. However, combinations of different antagonists/inhibitors, including BAY x1005 and BAY u3405, caused pronounced inhibitions of the antigen responses, suggesting synergism in action. On the basis of these data it was concluded that although histamine and cysteinyl-leukotrienes mediate the major part of the bronchoconstriction, one or several prostanoids other than thromboxane contribute to the bronchoconstriction evoked by OVA. Moreover, the effect of diclofenac involved a dual action because it also made the IPL less sensitive to histamine and LTD4. The findings resemble and extend recent observations in clinical studies of patients with asthma and support the usefulness of this particular model in airway pharmacology. PMID:12954791

Sundström, Ewa; Låstbom, Lena; Ryrfeldt, Ake; Dahlén, Sven-Erik

2003-10-01

59

Changes in Global Function and Regional Ventilation and Perfusion on SPECT During the Course of Radiotherapy in Patients With Non-Small-Cell Lung Cancer  

SciTech Connect

Purpose: This study aimed to (1) examine changes in dyspnea, global pulmonary function test (PFT) results, and functional activity on ventilation (V)/perfusion (Q) single-photon emission computerized tomography (SPECT) scans during the course of radiation (RT), and (2) factors associated with the changes in patients with non-small-cell lung cancer (NSCLC). Methods and Materials: Fifty-six stage I to III NSCLC patients treated with definitive RT with or without chemotherapy were enrolled prospectively. Dyspnea was graded according to Common Terminology Criteria for Adverse Events version 3.0 prior to and weekly during RT. V/Q SPECT-computed tomography (CT) and PFTs were performed prior to and during RT at approximately 45 Gy. Functions of V and Q activities were assessed using a semiquantitative scoring of SPECT images. Results: Breathing improved significantly at the third week (mean dyspnea grade, 0.8 vs. 0.6; paired t-test p = 0.011) and worsened during the later course of RT (p > 0.05). Global PFT results did not change significantly, while regional lung function on V/Q SPECT improved significantly after {approx}45 Gy. The V defect score (DS) was 4.9 pre-RT versus 4.3 during RT (p = 0.01); Q DS was 4.3 pre-RT versus 4.0 during RT (p < 0.01). Improvements in V and Q functions were seen primarily in the ipsilateral lung (V DS, 1.9 pre-RT versus 1.4 during RT, p < 0.01; Q DS, 1.7 pre-RT versus 1.5 during RT, p < 0.01). Baseline primary tumor volume was significantly correlated with pre-RT V/Q DS (p < 0.01). Patients with central lung tumors had greater interval changes in V and Q than those with more peripheral tumors (p <0.05 for both V and Q DS). Conclusions: Regional ventilation and perfusion improved during RT at 45 Gy. This suggests that adaptive planning based on V/Q SPECT during RT may allow sparing of functionally recoverable lung tissue.

Yuan Shuanghu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Radiation Oncology, Shaexamndong Cancer Hospital and Institute, Jinan (China); Frey, Kirk A.; Gross, Milton D. [Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Hayman, James A. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Arenberg, Doug [Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (United States); Cai Xuwei [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Ramnath, Nithya; Hassan, Khaled [Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (United States); Moran, Jean; Eisbruch, Avraham; Ten Haken, Randall K. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Kong Fengming, E-mail: fengkong@med.umich.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Radiation Oncology, Veterans' Affairs Health Center, Ann Arbor, Michigan (United States)

2012-03-15

60

A compartment model of alveolar-capillary oxygen diffusion with ventilation-perfusion gradient and dynamics of air transport through the respiratory tract.  

PubMed

This paper presents a model of alveolar-capillary oxygen diffusion with dynamics of air transport through the respiratory tract. For this purpose electrical model representing the respiratory tract mechanics and differential equations representing oxygen membrane diffusion are combined. Relevant thermodynamic relations describing the mass of oxygen transported into the human body are proposed as the connection between these models, as well as the influence of ventilation-perfusion mismatch on the oxygen diffusion. The model is verified based on simulation results of varying exercise intensities and statistical calculations of the results obtained during various clinical trials. The benefit of the approach proposed is its application in simulation-based research aimed to generate quantitative data of normal and pathological conditions. Based on the model presented, taking into account many essential physiological processes and air transport dynamics, comprehensive and combined studies of the respiratory efficiency can be performed. The impact of physical exercise, precise changes in respiratory tract mechanics and alterations in breathing pattern can be analyzed together with the impact of various changes in alveolar-capillary oxygen diffusion. This may be useful in simulation of effects of many severe medical conditions and increased activity level. PMID:24950449

Jaworski, Jacek; Redlarski, Grzegorz

2014-08-01

61

Pulmonary delivery and tissue distribution of aerosolized antisense 2'-O-Methyl RNA containing nanoplexes in the isolated perfused and ventilated rat lung.  

PubMed

Pulmonary delivery of drugs, particularly in the treatment of lung cancer, is an attractive strategy for future targeted therapy. In this context, inhalation of nanoplexes might offer a new mode for drug delivery in gene therapy. However, limited data are currently available demonstrating pulmonary delivery, cellular uptake as well as local tolerability in lung tissue. The aim of this study was to elucidate the pulmonary delivery, tissue distribution and local tolerability of aerosolized chitosan-coated poly(lactide-co-glycolide) based nanoplexes containing antisense 2'-O-Methyl RNA (OMR). Therefore, an aerosol of OMR-nanoplexes or OMR alone was administered intra-tracheally using the model of the isolated perfused and ventilated rat lung. Localization of OMR in rat lung tissue was examined by immunohistochemistry. Administration of the OMR-nanoplex formulation resulted in significantly higher cellular OMR uptake of the respiratory epithelium in contrast to the administration of OMR alone, indicating that drug administration via aerosolized nanoplexes is able to target lung tissue. No prominent changes in lung physiology parameters were observed following inhalation, suggesting good local tolerability of OMR-nanoplex formulation. PMID:22565122

Dong, M; Mürdter, T E; Philippi, C; Loretz, B; Schaefer, U F; Lehr, C-M; Schwab, M; Ammon-Treiber, S

2012-08-01

62

Ventilation and ventilators.  

PubMed

The history of ventilation is reviewed briefly and recent developments in techniques of ventilation are discussed. Operating features of ventilators have changed in the past few years, partly as the result of clinical progress; yet, technology appears to have outstripped the clinician's ability to harness it most effectively. Clinical discipline and training of medical staff in the use of ventilators could be improved. The future is promising if clinician and designer can work together closely. Ergonomics of ventilators and their controls and the provision of alarms need special attention. Microprocessors are likely to feature prominently in the next generation of designs. PMID:6754938

Hayes, B

1982-01-01

63

Administration of hydrogen sulfide via extracorporeal membrane lung ventilation in sheep with partial cardiopulmonary bypass perfusion: a proof of concept study on metabolic and vasomotor effects  

PubMed Central

Introduction Although inhalation of 80 parts per million (ppm) of hydrogen sulfide (H2S) reduces metabolism in mice, doses higher than 200 ppm of H2S were required to depress metabolism in rats. We therefore hypothesized that higher concentrations of H2S are required to reduce metabolism in larger mammals and humans. To avoid the potential pulmonary toxicity of H2S inhalation at high concentrations, we investigated whether administering H2S via ventilation of an extracorporeal membrane lung (ECML) would provide means to manipulate the metabolic rate in sheep. Methods A partial venoarterial cardiopulmonary bypass was established in anesthetized, ventilated (fraction of inspired oxygen = 0.5) sheep. The ECML was alternately ventilated with air or air containing 100, 200, or 300 ppm H2S for intervals of 1 hour. Metabolic rate was estimated on the basis of total CO2 production (V?CO2) and O2 consumption (V?O2). Continuous hemodynamic monitoring was performed via indwelling femoral and pulmonary artery catheters. Results V?CO2, V?O2, and cardiac output ranged within normal physiological limits when the ECML was ventilated with air and did not change after administration of up to 300 ppm H2S. Administration of 100, 200 and 300 ppm H2S increased pulmonary vascular resistance by 46, 52 and 141 dyn·s/cm5, respectively (all P ? 0.05 for air vs. 100, 200 and 300 ppm H2S, respectively), and mean pulmonary artery pressure by 4 mmHg (P ? 0.05), 3 mmHg (n.s.) and 11 mmHg (P ? 0.05), respectively, without changing pulmonary capillary wedge pressure or cardiac output. Exposure to 300 ppm H2S decreased systemic vascular resistance from 1,561 ± 553 to 870 ± 138 dyn·s/cm5 (P ? 0.05) and mean arterial pressure from 121 ± 15 mmHg to 66 ± 11 mmHg (P ? 0.05). In addition, exposure to 300 ppm H2S impaired arterial oxygenation (PaO2 114 ± 36 mmHg with air vs. 83 ± 23 mmHg with H2S; P ? 0.05). Conclusions Administration of up to 300 ppm H2S via ventilation of an extracorporeal membrane lung does not reduce V?CO2 and V?O2, but causes dose-dependent pulmonary vasoconstriction and systemic vasodilation. These results suggest that administration of high concentrations of H2S in venoarterial cardiopulmonary bypass circulation does not reduce metabolism in anesthetized sheep but confers systemic and pulmonary vasomotor effects.

2011-01-01

64

Imbalance in the health workforce  

PubMed Central

Imbalance in the health workforce is a major concern in both developed and developing countries. It is a complex issue that encompasses a wide range of possible situations. This paper aims to contribute not only to a better understanding of the issues related to imbalance through a critical review of its definition and nature, but also to the development of an analytical framework. The framework emphasizes the number and types of factors affecting health workforce imbalances, and facilitates the development of policy tools and their assessment. Moreover, to facilitate comparisons between health workforce imbalances, a typology of imbalances is proposed that differentiates between profession/specialty imbalances, geographical imbalances, institutional and services imbalances and gender imbalances.

Zurn, Pascal; Dal Poz, Mario R; Stilwell, Barbara; Adams, Orvill

2004-01-01

65

Anaesthesia ventilators  

PubMed Central

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits.

Jain, Rajnish K; Swaminathan, Srinivasan

2013-01-01

66

Anaesthesia ventilators.  

PubMed

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits. PMID:24249886

Jain, Rajnish K; Swaminathan, Srinivasan

2013-09-01

67

Kinetics of Reversible-Sequestration of Leukocytes by the Isolated Perfused Rat Lung.  

National Technical Information Service (NTIS)

The kinetics and morphology of sequestration and margination of rat leukocytes were studied using an isolated perfused and ventilated rat lung preparation. Whole rat blood, bone marrow suspension, or leukocyte suspensions, were used to perfuse the isolate...

B. Goliaei

1980-01-01

68

Ventilation models  

NASA Astrophysics Data System (ADS)

Calculation procedures, used in the design of ventilating systems, which are especially suited for displacement ventilation in addition to linking it to mixing ventilation, are addressed. The two zone flow model is considered and the steady state and transient solutions are addressed. Different methods of supplying air are discussed, and different types of air flow are considered: piston flow, plane flow and radial flow. An evaluation model for ventilation systems is presented.

Skaaret, Eimund

69

Krypton-81m ventilation scanning: acute respiratory disease  

SciTech Connect

From experience with 700 patients undergoing ventilation and perfusion lung scanning with krypton-81m/technetium-99m technique, 34 patients suffering from nonembolic acute respiratory disease were selected for review. In 16 patients with pneumonia, all had defects of ventilation corresponding to, or larger than, the radiologic consolidation. In 13 patients there was some preservation of perfusion in the consolidated region. In two of the three patients with matched defects, the pneumonia was of long standing. In seven patients with collapse or atelectasis and in 11 patients with acute reversible bronchial obstruction and normal volume lungs, a similar pattern or ventillation and perfusion was observed.

Lavender, J.P. (Royal Postgraduate Medical School, London, England); Irving, H.; Armstrong, J.D. II

1981-02-01

70

Industrial ventilation  

NASA Astrophysics Data System (ADS)

Industrial ventilation design methodology, using computers and using fluid dynamic models, is considered. It is noted that the design of a ventilation system must be incorporated into the plant design and layout at the earliest conceptual stage of the project. A checklist of activities concerning the methodology for the design of a ventilation system for a new facility is given. A flow diagram of the computer ventilation model shows a typical input, the initialization and iteration loop, and the output. The application of the fluid dynamic modeling techniques include external and internal flow fields, and individual sources of heat and contaminants. Major activities for a ventilation field test program are also addressed.

Goodfellow, H. D.

71

Metabolism of environmental pollutants by the isolated perfused lung  

Microsoft Academic Search

An isolated perfused rabbit lung system was developed for the study of pulmonary metabolism of foreign compounds. The main features of the system include the use of autologous whole blood, constant pressure perfusion, subatmospheric ventilation, and measurement of a variety of physiological and biochemical parameters. Pulmonary metabolism of benzo-(a)pyrene has been investigated with this system. In addition to the 3-hydroxy

E. Bingham; R. Niemeier; W. Dalbey

1976-01-01

72

Ventilation Model  

SciTech Connect

The purpose of this analysis and model report (AMR) for the Ventilation Model is to analyze the effects of pre-closure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts and provide heat removal data to support EBS design. It will also provide input data (initial conditions, and time varying boundary conditions) for the EBS post-closure performance assessment and the EBS Water Distribution and Removal Process Model. The objective of the analysis is to develop, describe, and apply calculation methods and models that can be used to predict thermal conditions within emplacement drifts under forced ventilation during the pre-closure period. The scope of this analysis includes: (1) Provide a general description of effects and heat transfer process of emplacement drift ventilation. (2) Develop a modeling approach to simulate the impacts of pre-closure ventilation on the thermal conditions in emplacement drifts. (3) Identify and document inputs to be used for modeling emplacement ventilation. (4) Perform calculations of temperatures and heat removal in the emplacement drift. (5) Address general considerations of the effect of water/moisture removal by ventilation on the repository thermal conditions. The numerical modeling in this document will be limited to heat-only modeling and calculations. Only a preliminary assessment of the heat/moisture ventilation effects and modeling method will be performed in this revision. Modeling of moisture effects on heat removal and emplacement drift temperature may be performed in the future.

H. Yang

1999-11-04

73

Heterogeneity in ventilation during positive end-expiratory pressure  

Microsoft Academic Search

We read with interest the commentary ‘Can heterogeneity in ventilation be good’ [1] and the related article by Zhao and colleagues [2]. We agree with the comments that instead of incremental positive end-expiratory pressure (PEEP) levels, a decremented PEEP titration might be an attractive option for determining optimal PEEP [1,3]. However, we feel that physiological inhomogeneity in ventilation and perfusion

Mukesh Tripathi; Mamta Pandey

2010-01-01

74

Ventilation Model  

SciTech Connect

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their post-closure analyses. The Ventilation Model report was initially developed to analyze the effects of preclosure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts, and to provide heat removal data to support EBS design. Revision 00 of the Ventilation Model included documentation of the modeling results from the ANSYS-based heat transfer model. The purposes of Revision 01 of the Ventilation Model are: (1) To validate the conceptual model for preclosure ventilation of emplacement drifts and verify its numerical application in accordance with new procedural requirements as outlined in AP-SIII-10Q, Models (Section 7.0). (2) To satisfy technical issues posed in KTI agreement RDTME 3.14 (Reamer and Williams 2001a). Specifically to demonstrate, with respect to the ANSYS ventilation model, the adequacy of the discretization (Section 6.2.3.1), and the downstream applicability of the model results (i.e. wall heat fractions) to initialize post-closure thermal models (Section 6.6). (3) To satisfy the remainder of KTI agreement TEF 2.07 (Reamer and Williams 2001b). Specifically to provide the results of post-test ANSYS modeling of the Atlas Facility forced convection tests (Section 7.1.2). This portion of the model report also serves as a validation exercise per AP-SIII.10Q, Models, for the ANSYS ventilation model. (4) To further satisfy KTI agreements RDTME 3.01 and 3.14 (Reamer and Williams 2001a) by providing the source documentation referred to in the KTI Letter Report, ''Effect of Forced Ventilation on Thermal-Hydrologic Conditions in the Engineered Barrier System and Near Field Environment'' (Williams 2002). Specifically to provide the results of the MULTIFLUX model which simulates the coupled processes of heat and mass transfer in and around waste emplacement drifts during periods of forced ventilation. This portion of the model report is presented as an Alternative Conceptual Model with a numerical application, and also provides corroborative results used for model validation purposes (Section 6.3 and 6.4).

V. Chipman

2002-10-05

75

Liquid Ventilation  

PubMed Central

Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future.

Tawfic, Qutaiba A.; Kausalya, Rajini

2011-01-01

76

On the Class Imbalance Problem  

Microsoft Academic Search

The class imbalance problem has been recognized in many practical domains and a hot topic of machine learning in recent years. In such a problem, almost all the examples are labeled as one class, while far fewer examples are labeled as the other class, usually the more important class. In this case, standard machine learning algorithms tend to be overwhelmed

Xinjian Guo; Yilong Yin; Cailing Dong; Gongping Yang; Guangtong Zhou

2008-01-01

77

Dynamic chest image analysis: model-based pulmonary perfusion analysis with pyramid images  

NASA Astrophysics Data System (ADS)

The aim of the study 'Dynamic Chest Image Analysis' is to develop computer analysis and visualization methods for showing focal and general abnormalities of lung ventilation and perfusion based on a sequence of digital chest fluoroscopy frames collected at different phases of the respiratory/cardiac cycles in a short period of time. We have proposed a framework for ventilation study with an explicit ventilation model based on pyramid images. In this paper, we extend the framework to pulmonary perfusion study. A perfusion model and the truncated pyramid are introduced. The perfusion model aims at extracting accurate, geographic perfusion parameters, and the truncated pyramid helps in understanding perfusion at multiple resolutions and speeding up the convergence process in optimization. Three cases are included to illustrate the experimental results.

Liang, Jianming; Haapanen, Arto; Jaervi, Timo; Kiuru, Aaro J.; Kormano, Martti; Svedstrom, Erkki; Virkki, Raimo

1998-07-01

78

Simulation investigation of wind turbine imbalance faults  

Microsoft Academic Search

This paper investigates the use of simulations to study wind turbine imbalance faults. The dynamics of a model wind turbine generator (WTG) are simulated in a combined environment of TurbSim, FAST (Fatigue, Aerodynamics, Structures, Turbulence), and Simulink in three different scenarios, i.e., normal operating conditions, blade imbalance, and aerodynamic asymmetry. The blade imbalance is simulated by scaling the mass density

Xiang Gong; Wei Qiao

2010-01-01

79

Ventilation systems  

NASA Astrophysics Data System (ADS)

Two different types of ventilation systems and their components are addressed: general ventilation and local or process ventilation. Calculation of the flow rates used in the different systems is addressed. The many different types of flow calculations, how they are used, and some of the computer programs that could be used for these calculations are described. Some calculations start with assumptions regarding air flow rates in rooms and locals. The flow rates can be chosen from rule of thumb or regulations or standards. Thereafter the designer calculates necessary heat and cooling loads, pressure drops, fan effect, etc. The other type of calculation is not very common. By using demands on concentrations, temperatures or air velocities the flow rates are calculated. These calculations include contaminant source generation rates, use of models (physical and theoretical), and computational fluid dynamics. The latter are focused upon.

Olander, L.

80

Dijet imbalance in hadronic collisions  

SciTech Connect

The imbalance of dijets produced in hadronic collisions has been used to extract the average transverse momentum of partons inside the hadrons. In this paper we discuss new contributions to the dijet imbalance that could complicate or even hamper this extraction. They are due to polarization of initial state partons inside unpolarized hadrons that can arise in the presence of nonzero parton transverse momentum. Transversely polarized quarks and linearly polarized gluons produce specific azimuthal dependences of the two jets that in principle are not suppressed. Their effects cannot be isolated just by looking at the angular deviation from the back-to-back situation; rather they enter jet broadening observables. In this way they directly affect the extraction of the average transverse momentum of unpolarized partons that is thought to be extracted. We discuss appropriately weighted cross sections to isolate the additional contributions.

Boer, Danieel [Department of Physics and Astronomy, Vrije Universiteit Amsterdam, NL-1081 HV Amsterdam (Netherlands); Theory Group, KVI, University of Groningen, Zernikelaan 25, NL-9747 AA Groningen (Netherlands); Mulders, Piet J. [Department of Physics and Astronomy, Vrije Universiteit Amsterdam, NL-1081 HV Amsterdam (Netherlands); Pisano, Cristian [Department of Physics and Astronomy, Vrije Universiteit Amsterdam, NL-1081 HV Amsterdam (Netherlands); Dipartimento di Fisica, Universita di Cagliari, and INFN, Sezione di Cagliari, I-09042 Monserrato (Italy)

2009-11-01

81

Nasal ventilation.  

PubMed Central

Nasal intermittent positive pressure ventilation is likely to have an increasing role in the management of acute ventilatory failure, weaning, and chronic ventilatory problems. Further improvements in ventilator and mask design will be seen. Appropriate application is likely to reduce both mortality and admissions to intensive care, while domiciliary use can improve life expectancy and/or quality of life in chronic ventilatory disorders. As with any new technique, enthusiasm should not outweigh clear outcome information, and possible new indications should always be subject to careful assessment. Images Figure 2

Simonds, A. K.

1998-01-01

82

Fate of inhaled nitrogen dioxide in isolated perfused rat lung  

SciTech Connect

The fate of inhaled NO/sub 2/ was studied with isolated perfused rat lungs. The isolated lungs were exposed to 5 ppM NO/sub 2/ for 90 min at a ventilation rate of 45 ml/min. The NO/sub 2/ exposure had no adverse effects on the lungs as judged from their weights, glucose uptake, or lactate production compared to control lungs. Isolated lungs absorbed 36% of ventilated NO/sub 2/, which was detected in perfusate and lung tissue as NO/sub 2//sup -/ but not NO/sub 3//sup -/. The NO/sub 2//sup -/ concentration in perfusate increased linearly with time, and after 90 min of ventilation with NO/sub 2/ and perfusion with erythrocyte-free medium the NO/sub 2//sup -/ accumulation was 6.36 +- 0.39 ..mu..g. If perfusate contained 10% erythrocytes, the ventilated NO/sub 2/ product was mostly NO/sub 3//sup -/ in perfusate but NO/sub 2//sup -/ in lung tissue. Protein solutions absorbed NO/sub 2/ more effectively than simple salt solutions, but they all yielded mainly NO/sub 2//sup -/ unless erythrocytes were present, when the product was mostly NO/sub 3//sup -/. The results indicate that absorbed NO/sub 2/ in the lung is converted predominantly to NO/sub 2//sup -/, but after its diffusion into the vascular space it is oxidized to NO/sub 3//sup -/ by interactions with erythrocytes.

Postlethwait, E.M.; Mustafa, M.G.

1981-06-01

83

Microfluidic perfusion culture.  

PubMed

Microfluidic perfusion culture is a novel technique to culture animal cells in a small-scale microchamber with medium perfusion. Polydimethylsiloxane (PDMS) is the most popular material to fabricate a microfluidic perfusion culture chip. Photolithography and replica molding techniques are generally used for fabrication of a microfluidic perfusion culture chip. Pressure-driven perfusion culture system is convenient technique to carry out the perfusion culture of animal cells in a microfluidic device. Here, we describe a general theory on microfluid network design, microfabrication technique, and experimental technique for pressure-driven perfusion culture in an 8 × 8 microchamber array on a glass slide-sized microchip made out of PDMS. PMID:24297421

Hattori, Koji; Sugiura, Shinji; Kanamori, Toshiyuki

2014-01-01

84

Perfusion lung scan: an aid in detection of lymphangitic carcinomatosis  

SciTech Connect

Lymphangitic carcinomatosis is usually a late manifestation of metastatic disease. The patient usually presents with cough or dyspnea, and the chest radiograph is often nondiagnostic. Two patients are presented who developed symptoms while on adjuvant chemotherapy. Both had abnormal perfusion lung scans. One had matching ventilation defects; the other a normal ventilation study. Biopsy revealed metastatic carcinoma; in one case tumor was seen in both the pulmonary lymphatics and arterioles; in technique which can speed diagnosis and institution of therapy in lymphangitic carcinomatosis.

Bates, S.E.; Tranum, B.L.

1982-07-15

85

What is Imbalance of Nature?  

NASA Astrophysics Data System (ADS)

The Mother Nature is imbalanced at all. The Mother Nature is every moment new, never returns to previous condition. The gravity and magnetosphere are changeable and imbalanced. The Sun is changeable and imbalanced. The climate is changeable and imbalanced. The atmosphere is changeable and imbalanced. The ocean is changeable and imbalanced. The crust and deep interior are changeable and imbalanced. The cryosphere is changeable and imbalanced. The life is simultaneously as the creator and the result of the imbalance of Nature. The people society is changeable and imbalanced. All chemical, physical, social, and other phenomenons are changeable and imbalanced. It's just that each phenomenon of the Mother Nature has some personal time-scale: one change in a nanosecond, and looks like for us as instable, i.e. imbalanced; while others change over millions years and, therefore, to us looks like not changeable, i.e. balanced. The scientists who are studying the Nature have convinced that the real balance never exist in Nature. Sometimes we can see something that is stable, i.e. balanced. But on closer study it appears that we are witnessing is not eternal rest and balance, it is not eternal STOP, but it is the perpetual motion, changing, there are a lot of imbalances. The balance it can be some result of the temporary mutual compensation the imbalanced processes in opposite directions. The balance it can be also some result of the inaccurate measurement, misunderstanding of conception or even request from bosses. But if we start use more accurate measurements, improve the models and not fear the bosses, than usually we got some new details. These new details show thet under the balanced visibility in really is hiding the interaction of many imbalanced processes of different directions. The balanced logic usually answers to question: What is it? The balanced answers are approximate and it will be updated many times during the development of science and practice. The imbalanced logic usually answers to question: How and why it is happened in details? The imbalanced answers are approximate also, and they will also be updated many times during the development of science and practice. But the imbalanced logic allows us to overcome of the inertia of the balanced logic and much closer come up to understanding the essence of Nature. We try to answer the central question of humanity: How to get calm, i.e. balanced life if the everything around us is imbalanced, the people themselves are restless and not eternal? The study of the Imbalance of Nature is multi-disciplinary because Nature is one. It is our main advantage.

Kontar, V. A.

2012-12-01

86

Crankcase ventilator  

SciTech Connect

This patent describes a crankcase ventilator. It comprises: a conduct adapted to be attached to crankcase and a suction means for drawing air containing vapors from the crankcase through the conduit, a temperature sensitive element adapted to be placed in thermal contact with the crankcase, means for continuously varying the rate at which the suction means draws the air containing vapors from the crankcase according to temperature, and means connecting the varying means to the temperature sensitive element for causing the suction means to draw a greater volume of air from the crankcase when the crankcase is hot than when the crankcase is cold.

Pickering, J.J.

1989-11-14

87

Energy Imbalance Markets (Fact Sheet)  

SciTech Connect

The anticipated increase in variable renewable generation, such as wind and solar power, over the next several years has raised concerns about how system operators will maintain balance between electricity production and demand in the Western Interconnection, especially in its smaller balancing authority areas (BAAs). Given renewable portfolio standards in the West, it is possible that more than 50 gigawatts of wind capacity will be installed by 2020. Significant quantities of solar generation are likely to be added as well. Meanwhile, uncertainties about future load growth and challenges siting new transmission and generation resources may add additional stresses on the Western Interconnection of the future. One proposed method of addressing these challenges is an energy imbalance market (EIM). An EIM is a means of supplying and dispatching electricity to balance fluctuations in generation and load. It aggregates the variability of generation and load over multiple balancing areas (BAs).

Not Available

2012-09-01

88

Earth's Energy Imbalance and Implications  

NASA Astrophysics Data System (ADS)

Improving observations of ocean heat content show that Earth is absorbing more energy from the Sun than it is radiating to space as heat, even during the recent solar minimum. We update our analysis of Earth's observed energy imbalance through 2011 and compare this with climate simulations. Observed global surface temperature change and ocean heat gain together constrain the net climate forcing, implying existence of a large negative forcing by human-made aerosols. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We discuss implications of the trend of observed sea level rise in recent years, and its consistency with reported ice melt rates and ocean thermal expansion.

Hansen, J.; von Schuckmann, K.; Sato, M.; Kharecha, P.

2012-04-01

89

Shelter Ventilator Studies.  

National Technical Information Service (NTIS)

The report describes the research conducted to determine the applicability of several investigated shelter supplies: ventilator kits, both Kearny pump (KP) and pedal ventilator (PV); novel fantype ventilators; and a motor kit PV attachment. Military speci...

A. L. Kapil C. E. Rathmann

1971-01-01

90

Mechanical ventilator - infants  

MedlinePLUS

Ventilator - infants; Respirator - infants ... WHY IS A MECHANICAL VENTILATOR USED? A ventilator is used to provide breathing support for ill or immature babies. Sick or premature babies are often ...

91

Earth's Energy Imbalance and Ocean Heat Storage  

Microsoft Academic Search

The Earth's energy imbalance, i.e., the difference between solar energy absorbed and thermal energy emitted by the planet, is fundamental to global climate change, as it measures the net forcing acting on the climate system. The imbalance is now positive on decadal time scales, due to dominance of increasing greenhouse gas (GHG) forcing, and, with canonical climate sensitivity, it yields

J. Hansen; J. Willis; E. Leuliette; R. Bleck; K. Lo; R. Ruedy; M. Sato; S. Sun

2006-01-01

92

Pulmonary blood flow distribution in sheep: effects of anesthesia, mechanical ventilation, and change in posture  

NASA Technical Reports Server (NTRS)

BACKGROUND: Recent studies providing high-resolution images of pulmonary perfusion have questioned the classical zone model of pulmonary perfusion. Hence the present work was undertaken to provide detailed maps of regional pulmonary perfusion to examine the influence of anesthesia, mechanical ventilation, and posture. METHODS: Pulmonary perfusion was analyzed with intravenous fluorescent microspheres (15 microm) in six sheep studied in four conditions: prone and awake, prone with pentobarbital-anesthesia and breathing spontaneously, prone with anesthesia and mechanical ventilation, and supine with anesthesia and mechanical ventilation. Lungs were air dried at total lung capacity and sectioned into approximately 1,100 pieces (about 2 cm3) per animal. The pieces were weighed and assigned spatial coordinates. Fluorescence was read on a spectrophotometer, and signals were corrected for piece weight and normalized to mean flow. Pulmonary blood flow heterogeneity was assessed using the coefficient of variation of flow data. RESULTS: Pentobarbital anesthesia and mechanical ventilation did not influence perfusion heterogeneity, but heterogeneity increased when the animals were in the supine posture (P < 0.01). Gravitational flow gradients were absent in the prone position but present in the supine (P < 0.001 compared with zero). Pulmonary perfusion was distributed with a hilar-to-peripheral gradient in animals breathing spontaneously (P < 0.05). CONCLUSIONS: The influence of pentobarbital anesthesia and mechanical ventilation on pulmonary perfusion heterogeneity is small compared with the effect of changes in posture. Analysis of flow gradients indicate that gravity plays a small role in determining pulmonary blood flow distribution.

Walther, S. M.; Domino, K. B.; Glenny, R. W.; Hlastala, M. P.

1997-01-01

93

Hypercapnic acidosis modulates inflammation, lung mechanics, and edema in the isolated perfused lung  

Microsoft Academic Search

ObjectiveLow tidal volume (VT) ventilation strategies may be associated with permissive hypercapnia, which has been shown by ex vivo and in vivo studies to have protective effects. We hypothesized that hypercapnic acidosis may be synergistic with low VT ventilation; therefore, we studied the effects of hypercapnia and VT on unstimulated and lipopolysaccharide-stimulated isolated perfused lungs.

Hilde R. De Smet; Andrew D. Bersten; Heather A. Barr; Ian R. Doyle

2007-01-01

94

Earth's energy imbalance and implications  

NASA Astrophysics Data System (ADS)

Improving observations of ocean heat content show that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar minimum. The inferred planetary energy imbalance, 0.59 ± 0.15 W m-2 during the 6-year period 2005-2010, confirms the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain together constrain the net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too efficiently into the deep ocean and as a result underestimate the negative forcing by human-made aerosols. Aerosol climate forcing today is inferred to be -1.6 ± 0.3 W m-2, implying substantial aerosol indirect climate forcing via cloud changes. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We conclude that recent slowdown of ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum. Observed sea level rise during the Argo float era is readily accounted for by ice melt and ocean thermal expansion, but the ascendency of ice melt leads us to anticipate acceleration of the rate of sea level rise this decade. Humanity is potentially vulnerable to global temperature change, as discussed in the Intergovernmental Panel on Climate Change (IPCC, 2001, 2007) reports and by innumerable authors. Although climate change is driven by many climate forcing agents and the climate system also exhibits unforced (chaotic) variability, it is now widely agreed that the strong global warming trend of recent decades is caused predominantly by human-made changes of atmospheric composition (IPCC, 2007). The basic physics underlying this global warming, the greenhouse effect, is simple. An increase of gases such as CO2 makes the atmosphere more opaque at infrared wavelengths. This added opacity causes the planet's heat radiation to space to arise from higher, colder levels in the atmosphere, thus reducing emission of heat energy to space. The temporary imbalance between the energy absorbed from the sun and heat emission to space, causes the planet to warm until planetary energy balance is restored. The planetary energy imbalance caused by a change of atmospheric composition defines a climate forcing. Climate sensitivity, the eventual global temperature change per unit forcing, is known with good accuracy from Earth's paleoclimate history. However, two fundamental uncertainties limit our ability to predict global temperature change on decadal time scales. First, although climate forcing by human-made greenhouse gases (GHGs) is known accurately, climate forcing caused by changing human-made aerosols is practically unmeasured. Aerosols are fine particles suspended in the air, such as dust, sulfates, and black soot (Ramanathan et al., 2001). Aerosol climate forcing is complex, because aerosols both reflect solar radiation to space (a cooling effect) and absorb solar radiation (a warming effect). In addition, atmospheric aerosols can alter cloud cover and cloud properties. Therefore, precise composition-specific measurements of aerosols and their effects on clouds are needed to assess the aerosol role in climate change. Second, the rate at which Earth's surface temperature approaches a new equilibrium in response to a climate forcing depends on how efficiently heat perturbations are mixed into the deeper ocean. Ocean mixing is complex and not necessarily simulated well by climate models. Empirical data on ocean heat uptake are improving rapidly, but still suffer limitations. We summarize current understanding of this basic physics of global warming and note observations needed to narrow uncertainties. Appropriate measurements can quantify the major factors driving climate change, reveal how much additional global warming is already in the pipeline, and help define the reduction of climate forcing needed to stabilize climate.

Hansen, J.; Sato, M.; Kharecha, P.; von Schuckmann, K.

2011-09-01

95

Role of exercise ventilation in the limitation of functional capacity in patients with congestive heart failure  

Microsoft Academic Search

Patients with heart failure have, compared with normal subjects, an increased minute ventilation (VE) at matched workloads. This heightened ventilatory drive may contribute to their limitation of functional capacity through an increase in the work of breathing and further worsening in the lung ventilation-perfusion mismatch.

Marco Metra; L. Dei Cas

1996-01-01

96

FATE OF INHALED NITROGEN DIOXIDE IN ISOLATED PERFUSED RAT LUNG  

EPA Science Inventory

The fate of inhaled NO2 was studied with isolated perfused rat lungs. The isolated lungs were exposed to 5 ppm NO2 for 90 min at a ventilation rate of 45 ml/min. The NO2 exposure had no adverse effects on the lungs as judged from their weights, glucose uptake, or lactate producti...

97

Regional pulmonary perfusion following human heart-lung transplantation  

SciTech Connect

Ventilation and perfusion scans were obtained in six subjects who had undergone heart-lung transplantation with consequent denervation of the cardiopulmonary axis. Two of the subjects had developed obliterative bronchiolitis, which is believed to be a form of chronic rejection. Their pulmonary function tests demonstrated airflow obstruction and their scintigraphic studies were abnormal. In the remaining four subjects without obstructive airways disease, ventilation and planar perfusion scans were normal. Single photon emission computed tomography imaging of pulmonary perfusion in these patients revealed a layered distribution of blood flow indistinguishable from that of normal individuals. It is concluded that neurogenic mechanisms have little influence on the pattern of local pulmonary blood flow at rest.

Lisbona, R.; Hakim, T.S.; Dean, G.W.; Langleben, D.; Guerraty, A.; Levy, R.D. (Royal Victoria Hospital, Montreal, Quebec (Canada))

1989-08-01

98

State of art: clinical ex vivo lung perfusion: rationale, current status, and future directions.  

PubMed

In recent years, ex vivo lung perfusion has emerged as an effective tool for increasing the number of available lungs accepted for transplant. As ex vivo lung perfusion use becomes more widespread, questions have arisen regarding the metabolic activity of the donor lung during ex vivo lung perfusion, optimal perfusion-ventilation strategy, and which parameters best define organ improvement or deterioration. Answers to many of these questions can be found in the published experience with the isolated perfused lung in the study of lung mechanics, pulmonary metabolism, and the effects of various interventions on lung quality. The purpose of this review is to summarize past and present evidence and to provide important background for clinicians and investigators using the ex vivo lung perfusion/isolated perfused lung system. PMID:22423980

Sanchez, Pablo G; Bittle, Gregory J; Burdorf, Lars; Pierson, Richard N; Griffith, Bartley P

2012-04-01

99

Single perfusion defect and pulmonary embolism: Angiographic correlation  

SciTech Connect

One hundred and thirty-three ventilation-perfusion scans (V-P) with angiographic correlation were retrospectively reviewed to evaluate the frequency of pulmonary emboli (PE) in single perfusion defects (SPD), regardless of ventilation or radiographic findings. By angiography, 15 of 30 SPD cases had PE. Demographic data and clinical presentation were similar for PE and non-PE patients. However, 9 out of 15 patients with PE had recent surgery compared to none of the non-PE patients. SPD were seen in areas of ventilation and chest x-ray abnormalities in 12 of 15 PE and 11 of 19 non-PE cases. Size of the actual lesion was underestimated by scintigraphy in most cases. In 7 of 15 PE cases, the perfusion defect was larger than the corresponding ventilation abnormality. Most SPD were located at the bases. Twelve of 15 SPD in the PE group were at the posterior basilar segment. In the appropriate clinical setting, SPD carries at least a moderate probability for PE. When the clinical suspicion is high, a pulmonary angiography will be needed to confirm the diagnosis.

Catania, T.A.; Caride, V.J. (Hospital of Saint Raphael, New Haven, CT (USA))

1990-03-01

100

VENTILATION TECHNOLOGY SYSTEMS ANALYSIS  

EPA Science Inventory

The report gives results of a project to develop a systems analysis of ventilation technology and provide a state-of-the-art assessment of ventilation and indoor air quality (IAQ) research needs. (NOTE: Ventilation technology is defined as the hardware necessary to bring outdoor ...

101

Dynamic chest image analysis: model-based ventilation study with pyramid images  

NASA Astrophysics Data System (ADS)

The aim of the study 'dynamic chest image analysis' is to develop computing analysis and visualization methods for showing focal and general abnormalities of lung ventilation and perfusion based on a sequence of digital chest fluoroscopy frames collected at different phases of the respiratory/cardiac cycles. A multiresolutional method for ventilation study with an explicit ventilation model based on pyramid images is proposed in this paper. The ventilation model is sophisticated enough in coverage of both inhalation and exhalation phases, but also remains simple enough in model realization. This model plays a critical role in extracting accurate, geographic ventilation parameters; while the pyramid helps in understanding ventilation at multiple resolutions and speeding up the convergence process in optimization. A number of patients have been studied with a research prototype produced in MATLAB. The prototype has proven to be useful aid in dynamic pulmonary ventilation study. However, for clinical use, further work must be done in the future.

Liang, Jianming; Jarvi, Timo; Kiuru, Aaro J.; Kormano, Martti; Svedstrom, Erkki; Virkki, Raimo

1997-05-01

102

A rational framework for selecting modes of ventilation.  

PubMed

Mechanical ventilation is a life-saving intervention for respiratory failure and thus has become the cornerstone of the practice of critical care medicine. A mechanical ventilation mode describes the predetermined pattern of patient-ventilator interaction. In recent years there has been a dizzying proliferation of mechanical ventilation modes, driven by technological advances and market pressures, rather than clinical data. The comparison of these modes is hampered by the sheer number of combinations that need to be tested against one another, as well as the lack of a coherent, logical nomenclature that accurately describes a mode. In this paper we propose a logical nomenclature for mechanical ventilation modes, akin to biological taxonomy. Accordingly, the control variable, breath sequence, and targeting schemes for the primary and secondary breaths represent the order, family, genus, and species, respectively, for the described mode. To distinguish unique operational algorithms, a fifth level of distinction, termed variety, is utilized. We posit that such coherent ordering would facilitate comparison and understanding of modes. Next we suggest that the clinical goals of mechanical ventilation may be simplified into 3 broad categories: provision of safe gas exchange; provision of comfort; and promotion of liberation from mechanical ventilation. Safety is achieved via optimization of ventilation-perfusion matching and pressure-volume relationship of the lungs. Comfort is provided by fostering patient-ventilator synchrony. Liberation is promoted by optimization of the weaning experience. Then we follow a paradigm that matches the technological capacity of a particular mode to achieving a specific clinical goal. Finally, we provide the reader with a comparison of existing modes based on these principles. The status quo in mechanical ventilation mode nomenclature impedes communication and comparison of existing mechanical ventilation modes. The proposed model, utilizing a systematic nomenclature, provides a useful framework to address this unmet need. PMID:22710796

Mireles-Cabodevila, Eduardo; Hatipo?lu, Umur; Chatburn, Robert L

2013-02-01

103

Diabetic Autonomic Imbalance and Glycemic Variability  

PubMed Central

Diabetic autonomic neural imbalance is a severe complication of long-term diabetes patients and may progress to diabetic autonomic neuropathy (DAN). The prevalence of DAN is reported to be between 20 and 70%, depending on the studies. The pathogenesis of DAN remains unresolved. However, emerging evidence suggests that glycemic variability (GV) may be associated with autonomic imbalance in patients with both type 1 and type 2 diabetes. As symptoms are initially weak and uncharacteristic, the condition often remains undiagnosed until late manifestations present themselves. Predominant symptoms may include nausea, vomiting, gastroparesis, involuntary diarrhea, postural hypotension, voiding difficulties, and sexual dysfunction. Analyzing the patterns of heart rate variability carries the potential for detection of autonomic imbalance in the subclinical and asymptomatic stages. In this context, GV may affect the sympathovagal balance by increasing oxidative stress and proinflammatory cytokines. Establishing a GV risk profile could therefore be important in determining risk factors in diabetes patients. This review addresses the issues above and in particular the possible association between diabetic autonomic imbalance and GV.

Fleischer, Jesper

2012-01-01

104

Adaptive Imbalances Correction in LINC Transmitters  

Microsoft Academic Search

The LInear amplification using Nonlinear Components (LINC) technique is a well- known power amplifier linearization method to reduce adjacent channel interference in a nonconstant envelope modulation system. Its major drawback is the inherited sensitivity to gain and phase imbalances between the two amplifier branches. In this paper two novel adaptive full- digital base band methods are described which correct any

Paloma García; Jesús de Mingo; Antonio Valdovinos; Alfonso Ortega

105

Biased coin design with imbalance tolerance  

Microsoft Academic Search

One of the main aspects of a sampling procedure is to determine how to collect samples. A completely random sampling scheme is free of any bias and provides a basis for valid statistical inferences. A balanced sampling scheme strengthens efficiency in statistical inference procedures. This paper presents a sampling schemebiased coin design with imbalance tolerance, which enforces balance in treatment

Chen Yung-Pin

1999-01-01

106

Analysis of Levene's Test under Design Imbalance.  

ERIC Educational Resources Information Center

H. Levene (1960) proposed a heuristic test for heteroscedasticity in the case of a balanced two-way layout, based on analysis of variance of absolute residuals. Conditions under which design imbalance affects the test's characteristics are identified, and a simple correction involving leverage is proposed. (SLD)

Keyes, Tim K.; Levy, Martin S.

1997-01-01

107

Demographic transition and demographic imbalance in India  

Microsoft Academic Search

In the coming decades, there will be growing demographic disparity in India and, like economic disparity, this should be a matter of serious concern for our planners and policy-makers. This demographic disparity leading to demographic imbalance may cause considerable social turbulence and may even pose a threat to political stability. Demographers must look far beyond demographic statistics and anticipate the

Ashish Bose

108

Perfusion lung scan: an aid in detection of lymphangitic carcinomatosis  

SciTech Connect

Lymphangitic carcinomatosis is usually a late manifestation of metastatic disease. The patient usually presents with cough or dyspnea, and the chest radiograph is often nondiagnostic. Two patients are presented who developed symptoms while on adjuvant chemotherapy. Both had abnormal perfusion lung scans. One had matching ventilation defects; the other a normal ventilation study. Biopsy revealed metastatic carcinoma; in one case tumor was seen in both the pulmonary lymphatics and arterioles; in the other, tumor was identified but the site could not be specified. The radionuclide lung scan is a technique which can speed diagnosis and institution of therapy in lymphangitic carcinomatosis.

Bates, S.E.; Tranum, B.L.

1982-07-15

109

[Myocardial perfusion scintigraphy].  

PubMed

The aim of this review was to recall the relevance of the myocardial perfusion scintigraphy procedure in the diagnosis of coronary artery disease. Myocardial perfusion scintigraphy is undergone after treadmill exercise or pharmacological stress by infusion of Dipyridamole. Thallium-201, sestamibi-Tc99m and tetrofosmine-Tc99m are the most frequently used tracers. Gated single photon emission computed tomography provides a combined evaluation of both myocardial perfusion and function. Myocardial perfusion imaging is an accurate tool for the diagnosis of coronary artery disease with a high sensitivity 93% and good specificity 80%. Its prognostic value is now well established among patients with known coronary artery disease. In particular for risk stratification and patient management decisions. Thallium-201 SPECT is clinically accurate in assessing myocardial viability. As it is for assessment after myocardial revascularisation. Thus myocardial perfusion scintigraphy is a reliable and a cost-effective investigation for coronary artery disease. PMID:14534942

Hammami, Hatem; Ben Brahim, Habib; Mhiri, Aida; Letaief, Béchir; Kraeim, Tarek; Ben Slimene, M Faouzi

2003-06-01

110

Education in the imbalance of Nature  

NASA Astrophysics Data System (ADS)

There are two concepts understanding of the real Nature: balanced and imbalanced. The traditional balanced concept understanding of Nature was originated in prehistoric times to calm the frightened souls of prehistoric man and manage groups of people. The balanced concept presupposes that Nature is isotropic, balanced, etc. The balanced concept of understanding of Nature gradually has moved to science and technology. The balanced concept of understanding of Nature is dominating from the prehistoric time up to today. But always parallel and opposite was exists the concept imbalanced understanding of Nature, which presupposes that Nature is anisotropy, imbalanced, etc. The balanced concept is much simpler than Imbalanced. The balanced concept has given mankind a lot of rough description of Nature which helped to solve a lot of practical problems but with sufficient accuracy, i.e. approximately, but not with an absolute precision. While people were few, and a lot of resources, person could take from Nature only what Nature gave willingly. During this period, people feared and respected Nature and Nature was able easily compensate the activity of people. The high accuracy of the description of Nature was not needed when resources were plentiful and people were few. But now the situation is completely different. The population has become a very large and growing. Traditional resources are almost run out and the lack of resources escalates. People are not afraid of Nature and bravely try to take by force what Nature does not give voluntarily. People invaded into imbalance Nature, and Nature can no longer compensate activity of people. The era of global change is started, including those that man provokes. In the conditions of global changes is insufficiently of the approximate solutions of the traditional balanced concept. The balanced concept is exhausted, and increasingly misleads people. The balanced concept cannot solve the problems that arise in the global change. The Concept imbalance of Nature is more suitable to solve problems of global change. Many thousands of scientists and practical from around the world are working already in the field of imbalance of Nature. Now is a time when the concept imbalance of Nature should be included into the training programs at universities, colleges and schools. We have experts who can teach students in imbalance of Nature. We have a list of topics for Ph.D. dissertations in field of imbalance of Nature. Now we are preparing the fundamental scientific book on all major issues imbalance of Nature. On the basis of this fundamental scientific work will be prepared the textbooks for students of different levels, non-fiction books, will organized promotion of the imbalance of Nature in the media, social networks, etc. People need to understand the real Nature as it is. This new knowledge will help humanity make the right and safer decisions in the era of global change. We invite the universities, colleges, schools, community organizations, sponsors and just responsible people of any country in the world to take part in this noble and vital issue. Humanity has no choice. Or mankind will have time to learn how to live in the era of global change or perish. The concept imbalance of Nature gives humanity the chance to survive.

Shlafman, L. M.; Kontar, V. A.

2013-12-01

111

Ventilation Model Report  

SciTech Connect

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their post-closure analyses. The Ventilation Model report was initially developed to analyze the effects of preclosure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts, and to provide heat removal data to support EBS design. Revision 00 of the Ventilation Model included documentation of the modeling results from the ANSYS-based heat transfer model. Revision 01 ICN 01 included the results of the unqualified software code MULTIFLUX to assess the influence of moisture on the ventilation efficiency. The purposes of Revision 02 of the Ventilation Model are: (1) To validate the conceptual model for preclosure ventilation of emplacement drifts and verify its numerical application in accordance with new procedural requirements as outlined in AP-SIII-10Q, Models (Section 7.0). (2) To satisfy technical issues posed in KTI agreement RDTME 3.14 (Reamer and Williams 2001a). Specifically to demonstrate, with respect to the ANSYS ventilation model, the adequacy of the discretization (Section 6.2.3.1), and the downstream applicability of the model results (i.e. wall heat fractions) to initialize post-closure thermal models (Section 6.6). (3) To satisfy the remainder of KTI agreement TEF 2.07 (Reamer and Williams 2001b). Specifically to provide the results of post-test ANSYS modeling of the Atlas Facility forced convection tests (Section 7.1.2). This portion of the model report also serves as a validation exercise per AP-SIII.10Q, Models, for the ANSYS ventilation model. (4) To asses the impacts of moisture on the ventilation efficiency.

V. Chipman; J. Case

2002-12-20

112

Computed Tomography Studies of Lung Ventilation and Perfusion  

Microsoft Academic Search

With the emergence of multidetector-row computed tomography (CT) it is now possible to image both structure and function via use of a single imaging modality. Breath-hold spiral CT provides detail of the airway and vascular trees along with texture reflective of the state of the lung parenchyma. Use of stable xenon gas wash- in and\\/or wash-out methods using an axial

Eric A. Hoffman; Deokiee Chon

2005-01-01

113

Pulmonary effects of intravenous atropine induce ventilation perfusion mismatch.  

PubMed

Atropine is used for a number of medical conditions, predominantly for its cardiovascular effects. Cholinergic nerves that innervate pulmonary smooth muscle, glands, and vasculature may be affected by anticholinergic medications. We hypothesized that atropine causes alterations in pulmonary gas exchange. We conducted a prospective interventional study with detailed physiologic recordings in anesthetized, spontaneously breathing rats (n = 8). Animals breathing a normoxic gas mixture titrated to a partial arterial pressure of oxygen of 110-120 were exposed to an escalating dose of intravenous atropine (0.001, 0.01, 0.1, 5.0, and 20.0 mg/kg body mass). Arterial blood gas measurements were recorded every 2 min (×5) at baseline, and following each of the 5 doses of atropine. In addition, the animals regional pulmonary blood flow was measured using neutron-activated microspheres. Oxygenation decreased immediately following intravenous administration of atropine, despite a small increase in the volume of inspired air with no change in respiratory rate. Arterial blood gas analysis showed an increase in pulmonary dysfunction, characterized by a widening of the alveolar-arteriole gradient (p < 0.003 all groups except for the lowest dose of atropine). The microsphere data demonstrates an abrupt and marked heterogeneity of pulmonary blood flow following atropine treatment. In conclusion, atropine was found to decrease pulmonary gas exchange in a dose-dependent fashion in this rat model. PMID:24773405

Gaspari, Romolo J; Paydarfar, David

2014-05-01

114

Perfusion linearity and its applications in perfusion algorithm analysis.  

PubMed

Perfusion analysis computes blood flow parameters (blood volume, blood flow, and mean transit time) from the observed flow of a contrast agent passing through the patient's vascular system. Perfusion deconvolution has been widely accepted as the principal numerical tool for perfusion analysis, and is used routinely in clinical applications. The extensive use of perfusion in clinical decision-making makes numerical stability and robustness of perfusion computations vital for accurate diagnostics and patient safety. The main goal of this paper is to propose a novel approach for validating numerical properties of perfusion algorithms. The approach is based on the Perfusion Linearity Property (PLP), which is fundamental to virtually all perfusion data processing. PLP allows one to study perfusion values as weighted averages of the original imaging data. This, in turn, uncovers hidden problems with the existing perfusion techniques, and may be used to suggest more reliable computational approaches and methodology. PMID:21871781

Pianykh, Oleg S

2012-04-01

115

Proximate sources of population sex imbalance in india  

Microsoft Academic Search

There is a population sex imbalance in India. Despite a consensus that this imbalance is due to excess female mortality, the\\u000a specific source of this excess mortality remains poorly understood. I use microdata on child survival in India to analyze\\u000a the proximate sources of the sex imbalance. I address two questions: when in life does the sex imbalance arise, and

Emily Osters

2009-01-01

116

Ventilating the English Channel Tunnel  

SciTech Connect

This article describes a unique ventilation system design which ensures a supply of fresh air to 95 miles of tunnels under the English Channel. The topics of the article include a description of the tunnel, a description of the equipment cooling and ventilation systems including provisions for heating of the tunnel ventilation air, ventilation system operation, and ventilation control system.

Dodge, T.M. (Raxcrest Project Management Ltd., Birmingham (United Kingdom))

1993-10-01

117

Simulation studies on imbalance faults of wind turbines  

Microsoft Academic Search

This paper presents the use of simulations to study imbalance faults of wind turbines. The dynamics of a model wind turbine are simulated in three different scenarios, i.e., normal operating conditions, blade imbalance, and aerodynamic asymmetry, using TurbSim and FAST. Blade imbalance is simulated by scaling the mass density of one blade which created an uneven distribution of mass with

Derek J. Gardels; Wei Qiao; Xiang Gong

2010-01-01

118

1. GENERAL VIEW SHOWING VENTILATOR NO. 9. THIS VENTILATOR IS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. GENERAL VIEW SHOWING VENTILATOR NO. 9. THIS VENTILATOR IS SLIGHTLY MORE ORNATE THAN WAS GENERALLY USED BECAUSE OF ITS LOCATION. - Old Croton Aqueduct, Ventilator Number 9, Spring & Everett Streets, Ossining, Westchester County, NY

119

GENERAL VIEW SHOWING VENTILATOR NUMBER NINE. THIS VENTILATOR IS SLIGHTLY ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

GENERAL VIEW SHOWING VENTILATOR NUMBER NINE. THIS VENTILATOR IS SLIGHTLY MORE ORNATE THAN WAS GENERALLY USED BECAUSE OF ITS LOCATION - Old Croton Aqueduct, Ventilator Number 9, Spring & Everett Streets, Ossining, Westchester County, NY

120

Earth's Energy Imbalance: Confirmation and Implications  

Microsoft Academic Search

Our climate model, driven mainly by increasing human-made greenhouse gases and aerosols, among other forcings, calculates that Earth is now absorbing 0.85 +\\/- 0.15 watts per square meter more energy from the Sun than it is emitting to space. This imbalance is confirmed by precise measurements of increasing ocean heat content over the past 10 years. Implications include (i) the

James Hansen; Larissa Nazarenko; Reto Ruedy; Makiko Sato; Josh Willis; Anthony Del Genio; Dorothy Koch; Andrew Lacis; Ken Lo; Surabi Menon; Tica Novakov; Judith Perlwitz; Gary Russell; Gavin A. Schmidt; Nicholas Tausnev

2005-01-01

121

Earth's Energy Imbalance and Ocean Heat Storage  

NASA Astrophysics Data System (ADS)

The Earth's energy imbalance, i.e., the difference between solar energy absorbed and thermal energy emitted by the planet, is fundamental to global climate change, as it measures the net forcing acting on the climate system. The imbalance is now positive on decadal time scales, due to dominance of increasing greenhouse gas (GHG) forcing, and, with canonical climate sensitivity, it yields an estimate of the amount of global warming that remains "in the pipeline" due to GHGs already in the atmosphere. The ocean is the largest sink for excess incoming energy. Inference of information from the energy imbalance is affected by a trade-off between decreasing accuracy of earlier data and the added information from longer time scales. We use two atmosphere-ocean models, with ocean heat and sea level measurements, to study the roles of different climate forcings, unforced climate variability including ocean- cloud interactions, and limitations of data sampling. We find that observed decrease in ocean heat content in the upper 750m in 2004-2005 does not significantly alter the estimate of ~0.5C global warming still "in the pipeline". Continuation and refinement of measurements of ocean heat, sea level, and ice sheet mass balance have the potential to greatly refine understanding of global warming, its practical implications, and important climate processes, but to be most useful they need to be supplemented by better measurements of deep ocean heat content changes and precise measurements of changing climate forcings such as tropospheric aerosols.

Hansen, J.; Willis, J.; Leuliette, E.; Bleck, R.; Lo, K.; Ruedy, R.; Sato, M.; Sun, S.

2006-12-01

122

An Algorithm to Evaluate Imbalances of Quadrature Mixers  

NASA Astrophysics Data System (ADS)

It is essential, as bandwidths of wireless communications get wider, to evaluate the imbalances among quadrature mixer ports, in terms of carrier phase offset, IQ gain imbalance, and IQ skew. Because it is time consuming to separate skew, gain imbalance and carrier phase offset evaluation during test is often performed using a composite value, without separation of the imbalance factors. This paper describes an algorithm for enabling separation among quadrature mixer gain imbalance, carrier phase offset, and skew. Since the test time is reduced by the proposed method, it can be applied during high volume production testing.

Asami, Koji; Arai, Michiaki

123

Preparation for Organ Perfusion  

Microsoft Academic Search

\\u000a \\u000a Background: After thoracic and abdominal organ dissection, a preservation solution is chosen and preparation for organ perfusion is started.\\u000a Cold preservation solution is taken from the transport box or refrigerator and afterwards, the surgeon, together with the\\u000a transplant coordinator and the scrub nurse, prepares the abdominal aorta perfusion system and also, if necessary, the inferior\\u000a vena cava (IVC) decompression system.

Andrzej Baranski

124

Hypercapnic Acidosis Impairs Plasma Membrane Wound Resealing in Ventilator-injured Lungs  

Microsoft Academic Search

The objective of this study was to assess the effects of hypercapnic acidosis on lung cell injury and repair by confocal microscopy in a modelofventilator-inducedlunginjury.Threegroupsofnormocap- nic, hypocapnic, and hypercapnic rat lungs were perfused ex vivo, either during or after injurious ventilation, with a solution con- tainingthemembrane-impermeantlabelpropidiumiodide.Inlungs labeled during injurious ventilation, propidium iodide fluorescence identifies all cells with plasma membrane wounds,

Clinton H. Doerr; Ognjen Gajic; Jorge C. Berrios; Sean Caples; Matthew Abdel; James F. Lymp; Rolf D. Hubmayr

125

Learning about ventilators  

MedlinePLUS

... the ventilator to the trachea). Suctioning is a word you will hear a lot when your loved one is on a ventilator. A small thin tube will be inserted into the tube in their mouth or neck to vacuum out mucus that is ...

126

[Human resources and their mitigatable imbalances].  

PubMed

In this paper, the policy-sensitive imbalances in the health professional markets are discussed. In Spain, the current staffing levels are still the result of unforeseen demographic and socio-economic developments. In some specialties and areas, there are selective shortages which in all likelihood will become more serious in the coming years due to the objective causes analyzed in this text. We propose a gradual increase in the medical schools numerus clausus and in the number of residents positions, the use of a variety of incentives to attract professionals to specific positions and, particularly, to increase the standing and quality of primary care. PMID:16539972

González López-Valcárcel, Beatriz; Barber-Pérez, Patricia

2006-03-01

127

MR myocardial perfusion imaging.  

PubMed

Contrast material-enhanced myocardial perfusion imaging by using cardiac magnetic resonance (MR) imaging has, during the past decade, evolved into an accurate technique for diagnosing coronary artery disease, with excellent prognostic value. Advantages such as high spatial resolution; absence of ionizing radiation; and the ease of routine integration with an assessment of viability, wall motion, and cardiac anatomy are readily recognized. The need for training and technical expertise and the regulatory hurdles, which might prevent vendors from marketing cardiac MR perfusion imaging, may have hampered its progress. The current review considers both the technical developments and the clinical experience with cardiac MR perfusion imaging, which hopefully demonstrates that it has long passed the stage of a research technique. In fact, cardiac MR perfusion imaging is moving beyond traditional indications such as diagnosis of coronary disease to novel applications such as in congenital heart disease, where the imperatives of avoidance of ionizing radiation and achievement of high spatial resolution are of high priority. More wide use of cardiac MR perfusion imaging, and novel applications thereof, are aided by the progress in parallel imaging, high-field-strength cardiac MR imaging, and other technical advances discussed in this review. PMID:23431226

Coelho-Filho, Otavio R; Rickers, Carsten; Kwong, Raymond Y; Jerosch-Herold, Michael

2013-03-01

128

Influence of Altered O2 Tension on Substrate Metabolism in Perfused Rat Lung.  

National Technical Information Service (NTIS)

Effects of hypoxia (1.5 h) on glucose and palmitate metabolism were investigated in perfused lungs from normal rats and rats exposed for 24 h to hypobaric conditions (simulated altitude of 24,000 ft). Hypoxic lungs were ventilated with 5% O2-5% CO2 and co...

R. A. Rhoades M. E. Shaw M. L. Eskew

1975-01-01

129

Normothermic renal artery perfusion: A comparison of perfusates  

Microsoft Academic Search

Hypothermia and preservative perfusates have been used to decrease ischemic renal injury. This study was performed to identify the preservative function of perfusates independent of the effects of hypothermia. Rats underwent 45 minutes of renal ischemia. Rectal and renal parenchyma temperatures were monitored and maintained within 1° C of normal. Perfusates were University of Wisconsin solution (UW), Euro-Collins solution, normal

John D. Hughes; Changyi Chen; Samer G. Mattar; Ayten Someren; Beverly Noe; Carolyn R. Suwyn; Alan B. Lumsden

1996-01-01

130

DMD transcript imbalance determines dystrophin levels.  

PubMed

Duchenne and Becker muscular dystrophies are caused by out-of-frame and in-frame mutations, respectively, in the dystrophin encoding DMD gene. Molecular therapies targeting the precursor-mRNA are in clinical trials and show promising results. These approaches will depend on the stability and expression levels of dystrophin mRNA in skeletal muscles and heart. We report that the DMD gene is more highly expressed in heart than in skeletal muscles, in mice and humans. The transcript mutated in the mdx mouse model shows a 5' to 3' imbalance compared with that of its wild-type counterpart and reading frame restoration via antisense-mediated exon skipping does not correct this event. We also report significant transcript instability in 22 patients with Becker dystrophy, clarifying the fact that transcript imbalance is not caused by premature nonsense mutations. Finally, we demonstrate that transcript stability, rather than transcriptional rate, is an important determinant of dystrophin protein levels in patients with Becker dystrophy. We suggest that the availability of the complete transcript is a key factor to determine protein abundance and thus will influence the outcome of mRNA-targeting therapies. PMID:23975932

Spitali, Pietro; van den Bergen, Janneke C; Verhaart, Ingrid E C; Wokke, Beatrijs; Janson, Anneke A M; van den Eijnde, Rani; den Dunnen, Johan T; Laros, Jeroen F J; Verschuuren, Jan J G M; 't Hoen, Peter A C; Aartsma-Rus, Annemieke

2013-12-01

131

Colorado Tunnel Ventilation Study.  

National Technical Information Service (NTIS)

Mechanical ventilation of tunnels is costly because of the initial installation and the continued maintenance and operation. However, at some tunnel length corresponding to a particular altitude, traffic configuration and topography there is a need for th...

B. B. Gerhardt D. E. Donnelly R. G. Griffin R. F. LaForce J. L. Sheff

1973-01-01

132

Volume guarantee ventilation.  

PubMed

Recognition that volume, not pressure, is the key factor in ventilator-induced lung injury and the association of hypocarbia with neonatal brain injury demonstrate the importance of better control delivered tidal volume. New microprocessor-based ventilator modalities combine advantages of pressure-limited ventilation with the ability to deliver a more consistent tidal volume. This article discusses automatic weaning of peak inspiratory pressure in response to changing lung compliance and respiratory effort. More consistent tidal volume, fewer excessively large breaths, lower peak pressure, less hypocapnia, shorter duration of mechanical ventilation, and lower levels of inflammatory cytokines have been documented in short-term clinical trials. It remains to be seen if these short-term benefits ultimately lead to a reduced incidence of chronic lung disease. PMID:17394933

Keszler, Martin; Abubakar, Kabir M

2007-03-01

133

Reverse Flow Personal Ventilation.  

National Technical Information Service (NTIS)

The potential contribution of reverse flow personal ventilation for the relief of thermal stress in the aviation field is reviewed. Current evidence is discussed and recommendations are made for further research. (Author)

D. G. Robertson J. Morrison J. R. Allan

1971-01-01

134

What Is a Ventilator?  

MedlinePLUS

... hospitals. Ventilators: Get oxygen into the lungs. Remove carbon dioxide from the body. (Carbon dioxide is a waste gas that can be ... NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings ...

135

A Resonant Synchronous Vibration Based Approach for Rotor Imbalance Detection  

NASA Technical Reports Server (NTRS)

This paper presents a methodology of detecting rotor imbalances, such as mass imbalance and crack-induced imbalance, using shaft synchronous vibrations. An iterative scheme is developed to identify parameters from measured synchronous vibration data. A detection system is integrated by using state-of-the-art commercial analysis equipment. A laboratory rotor test rig is used to verify the system integration and algorithm validation. A real engine test has been carried out and the results are reported.

Luo, Huangeng; Rodriquez, Hector; Hallman, Darren; Lewicki, David G.

2006-01-01

136

Negative Pressure Ventilation  

Microsoft Academic Search

\\u000a In essence, the negative pressure ventilator comprises a rigid shell that partly or completely encloses the patient’s torso,\\u000a the pressure within which can be dropped by means of an attached pump.27 Air enters the lungs as a result of the fall in pleural pressure produced by expansion of the thoracic cage. Expiration is\\u000a passive. Negative pressure ventilators were introduced in

Ashfaq Hasan

137

Conventional mechanical ventilation  

PubMed Central

The provision of mechanical ventilation for the support of infants and children with respiratory failure or insufficiency is one of the most common techniques that are performed in the Pediatric Intensive Care Unit (PICU). Despite its widespread application in the PICUs of the 21st century, before the 1930s, respiratory failure was uniformly fatal due to the lack of equipment and techniques for airway management and ventilatory support. The operating rooms of the 1950s and 1960s provided the arena for the development of the manual skills and the refinement of the equipment needed for airway management, which subsequently led to the more widespread use of endotracheal intubation thereby ushering in the era of positive pressure ventilation. Although there seems to be an ever increasing complexity in the techniques of mechanical ventilation, its successful use in the PICU should be guided by the basic principles of gas exchange and the physiology of respiratory function. With an understanding of these key concepts and the use of basic concepts of mechanical ventilation, this technique can be successfully applied in both the PICU and the operating room. This article reviews the basic physiology of gas exchange, principles of pulmonary physiology, and the concepts of mechanical ventilation to provide an overview of the knowledge required for the provision of conventional mechanical ventilation in various clinical arenas.

Tobias, Joseph D.

2010-01-01

138

Overall Subsurface Ventilation Systems  

SciTech Connect

The purpose of this analysis is to provide a conceptual design for the Subsurface Ventilation System and address the construction, emplacement, monitoring, backfill, and closure ventilation phases. The design will be based on the recently established program requirements for transitioning to the Site Recommendation (SR) design as outlined by ''Approach to Implementing the Site Recommendation Baseline'' (Stroupe 2000) and the Monitored Geologic Repository Project Description Document (CRWMS M and O 1999d) (MGR). This analysis will summarize the ventilation concepts that have developed from the incorporation of recent changes to the Technical Baseline and describe changes to the conceptual ventilation design that have resulted from the thermal management requirements. Ventilation concepts presented in the Viability Assessment Design (VA Design) that have not changed are identified and included. The objective of this analysis is to provide a basis for the System Description Document (SDD) Section 2 that provides input to the SR Consideration Report. The scope of the analysis includes the following tasks: (1) Determine the number of primary shafts based on the emplacement airflow rate required to meet thermal goals and (2) Determine conceptual airflow networks for major repository phases including: Construction; Emplacement; Monitoring; and Closure. In addition evaluate: (1) Radon mitigation concerns and options; (2) Monitoring and control requirement changes needed to meet current guidelines; and (3) The impact on the ventilation system of a radiological release due to a potential subsurface fire involving a waste package.

Edward G. Thomas

2000-05-16

139

Advanced ventilator modes and techniques.  

PubMed

In addition to improving gas exchange by mechanical ventilation, minimizing iatrogenic lung injury and making the patient comfortable are important goals. This article reviews advanced ventilator modes and techniques that might help to accomplish these goals. Small tidal volumes (VT) and low ventilation pressure minimize ventilator-induced lung injury. Airway pressure release ventilation and high-frequency oscillatory ventilation may provide lung-protective ventilation in certain patients with refractory hypoxemia. Adaptive support ventilation (ASV) automatically adjusts VT and rate on the basis of the patient's respiratory mechanics to provide "safe" settings. When ventilator output does not match patient respiratory center timing, patient-ventilator asynchrony occurs. Proportional assist ventilation and neutrally adjusted ventilatory assist are unique modes of ventilation that provide ventilatory support in direct proportion to patient effort and therefore may be able to better match patient need and improve comfort. Weaning protocols reduce duration of ventilation and intensive care unit stay. Certain ventilator modes purport to automate part of the ventilator discontinuance process. The ASV progressively reduces support as the patient's lung condition improves, while SmartCare/pressure support (Dräger, Lübeck, Germany) reduces support and then initiates a spontaneous breathing trial. Further research is required to determine the proper place these new modes have in the intensive care unit. PMID:22157490

Haas, Carl F; Bauser, Kimberly A

2012-01-01

140

Sildenafil increases ocular perfusion  

Microsoft Academic Search

Purpose: Our goal was to determine whether visual system responses to sildenafil accompany shifts in ocular perfusion.The human choroid, which supports the metabolic functionof the outer retina, is an erectile tissue, analogous in many respects to the corpus cavenosum. Methods: Right eyes of 12 normal adults were evaluated before and 2 hafter 50 mg oral dose of sildenafil. Pulsatile ocular

Gianmarco Paris; William E. Sponsel; Sal S. Sandoval; W. Rowe Elliott; Yolanda Trigo; Donald K. Sanford; Joseph M. Harrison

2001-01-01

141

Clinical Impact of Proximal Autosomal Imbalances  

PubMed Central

Centromere-near gain of copy number can be induced by intra- or inter-chromosomal rearrangements or by the presence of a small supernumerary marker chromosome (sSMC). Interestingly, partial trisomy to hexasomy of euchromatic material may be present in clinically healthy or affected individuals, depending on origin and size of chromosomal material involved. Here we report the known minimal sizes of all centromere-near, i.e., proximal auto-somal regions in humans, which are tolerated; over 100 Mb of coding DNA are comprised in these regions. Additionally, we have summarized the typical symptoms for nine proximal autosomal regions including genes obviously sensitive to copy numbers. Overall, studying the carriers of specific chromosomal imbalances using genomics-based medicine, combined with single cell analysis can provide the genotype-phenotype correlations and can also give hints where copy-number-sensitive genes are located in the human genome.

Hamid, AB; Weise, A; Voigt, M; Bucksch, M; Kosyakova, N; Liehr, T; Klein, E

2012-01-01

142

Earth's Energy Imbalance: Confirmation and Implications  

NASA Astrophysics Data System (ADS)

Our climate model, driven mainly by increasing human-made greenhouse gases and aerosols, among other forcings, calculates that Earth is now absorbing 0.85 +/- 0.15 watts per square meter more energy from the Sun than it is emitting to space. This imbalance is confirmed by precise measurements of increasing ocean heat content over the past 10 years. Implications include (i) the expectation of additional global warming of about 0.6°C without further change of atmospheric composition; (ii) the confirmation of the climate system's lag in responding to forcings, implying the need for anticipatory actions to avoid any specified level of climate change; and (iii) the likelihood of acceleration of ice sheet disintegration and sea level rise.

Hansen, James; Nazarenko, Larissa; Ruedy, Reto; Sato, Makiko; Willis, Josh; Del Genio, Anthony; Koch, Dorothy; Lacis, Andrew; Lo, Ken; Menon, Surabi; Novakov, Tica; Perlwitz, Judith; Russell, Gary; Schmidt, Gavin A.; Tausnev, Nicholas

2005-06-01

143

Hindlimb unloading elicits anhedonia and sympathovagal imbalance.  

PubMed

The hindlimb-unloaded (HU) rat model elicits cardiovascular deconditioning and simulates the physiological adaptations to microgravity or prolonged bed rest in humans. Although psychological deficits have been documented following bed rest and spaceflight in humans, few studies have explored the psychological effects of cardiovascular deconditioning in animal models. Given the bidirectional link established between cardiac autonomic imbalance and psychological depression in both humans and in animal models, we hypothesized that hindlimb unloading would elicit an alteration in sympathovagal tone and behavioral indexes of psychological depression. Male, Sprague-Dawley rats confined to 14 days of HU displayed anhedonia (a core feature of human depression) compared with casted control (CC) animals evidenced by reduced sucrose preference (CC: 81 +/- 2.9% baseline vs. HU: 58 +/- 4.5% baseline) and reduced (rightward shift) operant responding for rewarding electrical brain stimulation (CC: 4.4 +/- 0.3 muA vs. 7.3 +/- 1.0 muA). Cardiac autonomic blockade revealed elevated sympathetic [CC: -54 +/- 14.1 change in (Delta) beats/min vs. HU: -118 +/- 7.6 Delta beats/min] and reduced parasympathetic (CC: 45 +/- 11.8 Delta beats/min vs. HU: 8 +/- 7.3 Delta beats/min) cardiac tone in HU rats. Heart rate variability was reduced (CC: 10 +/- 1.4 ms vs. HU: 7 +/- 0.7 ms), and spectral analysis of blood pressure indicated loss of total, low-, and high-frequency power, consistent with attenuated baroreflex function. These data indicate that cardiovascular deconditioning results in sympathovagal imbalance and behavioral signs consistent with psychological depression. These findings further elucidate the pathophysiological link between cardiovascular diseases and affective disorders. PMID:18635876

Moffitt, Julia A; Grippo, Angela J; Beltz, Terry G; Johnson, Alan Kim

2008-10-01

144

Imbalance of Water as an Example of Fundamental Imbalance of Nature.  

NASA Astrophysics Data System (ADS)

Water is one of the main attributes of the world around us. Turning into ice or water vapor it controls a wide range of natural phenomena. It is one of the most moving substances of Earth and in it as in a mirror all imbalance of the Nature reflects. The laws that govern the water are above all the laws of classical physics, laws of motion and conservation. They determine an equilibrium state and out of it when the balance of forces, flows and energy is disturbed. Volcanic eruption, earthquake, tsunami, hurricane or tornado formation are the extreme form of imbalance of Nature. Unfortunately they are involved in it as a genetic feature. Mass and energy flows pervade the natural world. The structure of the space makes them come into conflict. Internal stress increase, there is an imbalance resulting in the fast, catastrophic events. Whether it is possible to understand the reasons of similar imbalance and to find its critical conditions? The water in their states shows the most striking examples of imbalance of Nature. If the equilibrium of forces and flows is disturbed the nature of movement can fundamentally change. The dependence of the total flux I flowing through the structure of the pressure drop ?p causing this flow can serve as an important informative characteristic for the imbalance phenomena connected with water. This «flow - forcing» characteristic I(?p) qualitatively changes its form with changes of so-called bifurcation parameter. From monotonous it can become S- or N-shaped. The approach to the analysis of Nature imbalance phenomenon can be illustrated by geyser eruption mechanism which is theoretically described in (Nechayev, 2012). One-dimensional motion of water flow in the geyser conduit obeys the Navier-Stokes equation. The influx of masses of water vapor due to water boiling in an underground chamber creates increasing overpressure. Bifurcation parameter is the volume of this chamber. There is a critical value of this volume (as compared with the volume of conduit) when the acceleration of the flow becomes positive and the eruption starts. The steady-state characteristic I (?p) can become S-shaped. The process of the volcanic eruption development is probably similar. In our opinion the main driving power of volcanic eruption is a contact of deep water-bearing layers to the magmatic chamber. Thermal energy of magma is transferred to the overpressure of superheated water vapor in some porous zone which is isolated from the surface. Bifurcation parameter is the volume of this vapor area. The magnitude of this volume determines the power of eruption, the velocities of lava and pyroclastic material. For the hurricanes too it is possible to find the analogous characteristic I (?p) (Nechayev, Solovyev, 2011). It can be the dependence of a full vertical air flow of horizontal pressure drop. Bifurcation parameter is the saturation mixing ratio of the moist air in the lower troposphere. Thus, despite all complexity of natural phenomena, it is possible to propose a generalized approach to the analysis of imbalance states of Nature taking into account the integral characteristics and corresponding bifurcation parameters.

Nechayev, A.

2012-12-01

145

Volume-targeted ventilation.  

PubMed

Recognition that volume, not pressure, is the key factor in ventilator-induced lung injury and the association of hypocarbia and brain injury dictate the need to better control delivered tidal volume. Volume-controlled ventilation, though much improved, still suffers from loss of volume due to endotracheal tube leak and gas compression in the circuit. Recent microprocessor-based modifications of pressure-limited, time-cycled ventilators combine advantages of pressure-limited ventilation with the ability to deliver a more consistent tidal volume. Each of the modes has advantages and disadvantages, with limited data available to judge their effectiveness. The Volume Guarantee mode, studied most thoroughly, provides automatic weaning of peak pressure in response to improving lung compliance and respiratory effort. More consistent tidal volume, fewer excessively large breaths, lower peak pressure, less hypocarbia and lower levels of inflammatory cytokines have been documented. It remains to be seen if these short-term benefits translate into shorter duration of ventilation or reduced incidence of chronic lung disease. PMID:17069993

Keszler, Martin

2006-12-01

146

A microprocessor based feedback controller for mechanical ventilation.  

PubMed

A microcomputer feedback system has been developed which adjusts the inspired minute volume of a ventilator based on the patient's end-tidal CO2 concentration. The feedback controlled ventilator was evaluated in 6 dogs (18-20 kg). Arterial PCO2 was monitored continuously while end-tidal CO2 concentration was controlled by the micro-computer system and the following perturbations introduced: [1] NaHCO3 was infused IV, [2] a pulmonary artery was occluded, [3] one lumen of a double lumen endobronchial tube was occluded, and [4] an air embolism was given. The end-tidal PCO2 controller kept PaCO2 within 1.2 mm Hg of the desired value when CO2 production increased by as much as 44%. Changing the ventilation/perfusion ratios caused differences as large as 22 mm Hg between the arterial and end-tidal PCO2 and the controller was not effective in keeping PaCO2 at the desired level. Closed loop control of ventilation based on end-tidal PCO2 measurements successfully compensated for increases in CO2 production keeping PaCO2 constant. The controller did not, however, keep PaCO2 at the desired level when significant changes occurred in the distribution of blood flow to ventilation. PMID:6819792

Ohlson, K B; Westenskow, D R; Jordan, W S

1982-01-01

147

Respiratory dysfunction in ventilated patients: can inspiratory muscle training help?  

PubMed

Respiratory muscle dysfunction is associated with prolonged and difficult weaning from mechanical ventilation. This dysfunction in ventilator-dependent patients is multifactorial: there is evidence that inspiratory muscle weakness is partially explained by disuse atrophy secondary to ventilation, and positive end-expiratory pressure can further reduce muscle strength by negatively shifting the length-tension curve of the diaphragm. Polyneuropathy is also likely to contribute to apparent muscle weakness in critically ill patients, and nutritional and pharmaceutical effects may further compound muscle weakness. Moreover, psychological influences, including anxiety, may contribute to difficulty in weaning. There is recent evidence that inspiratory muscle training is safe and feasible in selected ventilator-dependent patients, and that this training can reduce the weaning period and improve overall weaning success rates. Extrapolating from evidence in sports medicine, as well as the known effects of inspiratory muscle training in chronic lung disease, a theoretical model is proposed to describe how inspiratory muscle training enhances weaning and recovery from mechanical ventilation. Possible mechanisms include increased protein synthesis (both Type 1 and Type 2 muscle fibres), enhanced limb perfusion via dampening of a sympathetically-mediated metaboreflex, reduced lactate levels and modulation of the perception of exertion, resulting in less dyspnoea and enhanced exercise capacity. PMID:22417017

Bissett, B; Leditschke, I A; Paratz, J D; Boots, R J

2012-03-01

148

The perfused swine uterus model: long-term perfusion  

PubMed Central

Background It has previously been shown that the viability of swine uteri can be maintained within the physiological range in an open perfusion model for up to 8 hours. The aim of this study was to assess medium- to long-term perfusion of swine uteri using a modified Krebs–Ringer bicarbonate buffer solution (KRBB) in the established open perfusion model. Methods In an experimental study at an infertility institute, 30 swine uteri were perfused: group 1: n?=?11, KRBB; group 2: n?=?8, modified KRBB with drainage of perfusate supernatant; group 3: n?=?11, modified KRBB with drainage of perfusate every 2 h and substitution with fresh medium. Modified and conventional KRBB were compared with regard to survival and contraction parameters: intrauterine pressure (IUP), area under the curve (AUC), and frequency of contractions (F). Results Modified KRBB showed significantly higher IUP, AUC, and F values than perfusion with conventional KRBB. In group 3, the organ survival time of up to 17 h, with a 98% rate of effective contraction time, differed significantly from group 1 (P?perfusate substitution improves the open model for perfusion of swine uteri with regard to survival time and quality of contraction parameters. This model can be used for medium- to long-term perfusion of swine uteri, allowing further metabolic ex vivo studies in a cost-effective way and with little logistic effort.

2012-01-01

149

Socially explosive minds: the triple imbalance hypothesis of reactive aggression.  

PubMed

The psychobiological basis of reactive aggression, a condition characterized by uncontrolled outbursts of socially violent behavior, is unclear. Nonetheless, several theoretical models have been proposed that may have complementary views about the psychobiological mechanisms involved. In this review, we attempt to unite these models and theorize further on the basis of recent data from psychological and neuroscientific research to propose a comprehensive neuro-evolutionary framework: The Triple Imbalance Hypothesis (TIH) of reactive aggression. According to this model, reactive aggression is essentially subcortically motivated by an imbalance in the levels of the steroid hormones cortisol and testosterone (Subcortical Imbalance Hypothesis). This imbalance not only sets a primal predisposition for social aggression, but also down-regulates cortical-subcortical communication (Cortical-Subcortical Imbalance Hypothesis), hence diminishing control by cortical regions that regulate socially aggressive inclinations. However, these bottom-up hormonally mediated imbalances can drive both instrumental and reactive social aggression. The TIH suggests that reactive aggression is differentiated from proactive aggression by low brain serotonergic function and that reactive aggression is associated with left-sided frontal brain asymmetry (Cortical Imbalance Hypothesis), especially observed when the individual is socially threatened or provoked. This triple biobehavioral imbalance mirrors an evolutionary relapse into violently aggressive motivational drives that are adaptive among many reptilian and mammalian species, but may have become socially maladaptive in modern humans. PMID:20433613

van Honk, Jack; Harmon-Jones, Eddie; Morgan, Barak E; Schutter, Dennis J L G

2010-02-01

150

THE ROLE OF IONORGANIC ION IMBALANCE IN AQUATIC TOXICITY TESTING  

EPA Science Inventory

This paper assessess the issue of ion imbalance, provides summary of applicable data, presents several successful technical tools to address toxicity resulting from salinity and ion imbalances, and discusses regulatory/compliance options to manage discharges with salinity/ion imb...

151

Covariate Imbalance and Precision in Measuring Treatment Effects  

ERIC Educational Resources Information Center

Covariate adjustment can increase the precision of estimates by removing unexplained variance from the error in randomized experiments, although chance covariate imbalance tends to counteract the improvement in precision. The author develops an easy measure to examine chance covariate imbalance in randomization by standardizing the average…

Liu, Xiaofeng Steven

2011-01-01

152

A Central Dilemma in the Mental Health Sector: Structural Imbalance  

ERIC Educational Resources Information Center

Mental health services provision is persistently criticised regarding resource inadequacy. Services are also subject to another dilemma, "structural imbalance". This study demonstrates the dimensions of structural imbalance in Australia's mental health sector by recourse to the 1997 Australian Bureau of Statistics national survey of mental health…

Doessel, Darrel P.; Williams, Ruth F. G.; Nolan, Patricia

2008-01-01

153

Ventilation technologies scoping study  

SciTech Connect

This document presents the findings of a scoping study commissioned by the Public Interest Energy Research (PIER) program of the California Energy Commission to determine what research is necessary to develop new residential ventilation requirements for California. This study is one of three companion efforts needed to complete the job of determining the needs of California, determining residential ventilation requirements, and determining appropriate ventilation technologies to meet these needs and requirements in an energy efficient manner. Rather than providing research results, this scoping study identifies important research questions along with the level of effort necessary to address these questions and the costs, risks, and benefits of pursuing alternative research questions. In approaching these questions and level of effort, feasibility and timing were important considerations. The Commission has specified Summer 2005 as the latest date for completing this research in time to update the 2008 version of California's Energy Code (Title 24).

Walker, Iain S.; Sherman, Max H.

2003-09-30

154

Ventilation flow: Submerged  

NASA Technical Reports Server (NTRS)

The ventilation system on a submarine is discussed. When the submarine is submerged. The ventilation system provides a conditioned atmosphere in the ship with complete isolation from the outside. A conditioned atmosphere includes not only filtration and temperature and humidity control, but also air purification (removal of potentially harmful quantities of impurities and comtaminants) and revitalization (addition of vital life support oxygen). Carbon dioxide removal, the oxygen system, air conditioning, carbon monoxide removal, hydrogen removal, and atmosphere monitoring systems are among the topics discussed.

Hutchinson, D.

1985-01-01

155

Bench performance of ventilators during simulated paediatric ventilation.  

PubMed

This study compares the accuracy and capabilities of various ventilators using a paediatric acute respiratory distress syndrome lung model. Various compliance settings and respiratory rate settings were used. The study was done in three parts: tidal volume and FiO2 accuracy; pressure control accuracy and positive end-expiratory pressure (PEEP) accuracy. The parameters set on the ventilator were compared with either or both of the measured parameters by the test lung and the ventilator. The results revealed that none of the ventilators could consistently deliver tidal volumes within 1 ml/kg of the set tidal volume, and the discrepancy between the delivered volume and the volume measured by the ventilator varied greatly. The target tidal volume was 8 ml/kg, but delivered tidal volumes ranged from 3.6-11.4 ml/kg and the volumes measured by the ventilator ranged from 4.1-20.6 ml/kg. All the ventilators maintained pressure within 20% of the set pressure, except one ventilator which delivered pressures of up to 27% higher than the set pressure. Two ventilators maintained PEEP within 10% of the prescribed PEEP. The majority of the readings were also within 10%. However, three ventilators delivered, at times, PEEPs over 20% higher. In conclusion, as lung compliance decreases, especially in paediatric patients, some ventilators perform better than others. This study highlights situations where ventilators may not be able to deliver, nor adequately measure, set tidal volumes, pressure, PEEP or FiO2. PMID:23659397

Park, M A J; Freebairn, R C; Gomersall, C D

2013-05-01

156

Physiological Effects of Localized Ventilation.  

National Technical Information Service (NTIS)

Localized ventilation was applied frontally to the head and neck of seated, clothed subjects, engaged in a central tracking and peripheral tasks, in a 95F and 50% RH environment. Eight different ventilating jet properties were tested. Thermal and comfort ...

H. C. Leung N. Z. Azer P. E. McNall

1971-01-01

157

Safety and Performance of Ventilators.  

National Technical Information Service (NTIS)

The lung ventilators covered by this study have a wide range of application. They have come into use because of the need for a device that provides patient ventilation or augments inadequate spontaneous breathing and oxygenation. There are many varieties ...

J. K. Mitchell

1978-01-01

158

Inverse Correspondence Between Hippocampal Perfusion and Verbal Memory Performance in Older Adults  

PubMed Central

Understanding physiological changes that precede irreversible tissue damage in age-related pathology is central to optimizing treatments that may prevent, or delay, cognitive decline. Cerebral perfusion is a tightly regulated physiological property, coupled to tissue metabolism and function, and abnormal (both elevated and reduced) hippocampal perfusion has been reported in a range of cognitive disorders. However, the size and location of the hippocampus complicates perfusion quantification, as many perfusion techniques acquire data with spatial resolution on the order of or beyond the size of the hippocampus, and are thus suboptimal in this region (especially in the presence of hippocampal atrophy and reduced flow scenarios). Here, the relationship between hippocampal perfusion and atrophy as a function of memory performance was examined in cognitively normal healthy older adults (n = 20; age=67 ± 7 yr) with varying genetic risk for dementia using a custom arterial spin labeling acquisition and analysis procedure. When controlling for hippocampal volume, it was found that hippocampal perfusion correlated inversely (P = 0.04) with memory performance despite absent hippocampal tissue atrophy or white matter disease. The hippocampal flow asymmetry (left hippocampus perfusion–right hippocampus perfusion) was significantly (P = 0.04) increased in APOE-?4 carriers relative to noncarriers. These findings demonstrate that perfusion correlates more strongly than tissue volume with memory performance in cognitively normal older adults, and furthermore that an inverse trend between these two parameters suggests that elevation of neuronal activity, possibly mediated by neuroinflammation and/or excitation/inhibition imbalance, may be closely associated with minor changes in memory performance.

Rane, Swati; Ally, Brandon A.; Hussey, Erin; Wilson, Tracy; Thornton-Wells, Tricia; Gore, John C.; Donahue, Manus J.

2013-01-01

159

MHD Turbulence: Intermittency, Imbalance and Residual Energy  

NASA Astrophysics Data System (ADS)

Currently available highest resolution numerical simulations of MHD turbulence exhibit puzzling lack of universality in its inertial range. While larger scales develop scale-dependent alignment and local imbalance, they saturate on scales about ten times smaller. Another deviation from universality is shown by the ratio of signed to unsigned third order moments. While the scaling of the sighed third order moment is linear, consistent with theoretical prediction, the unsigned third order moment shows mixed, scale-dependent scaling. This is relevant for the long-debated issue of intermittency and anomalous scaling exponents of MHD turbulence. We used a rigorous method of resolution study to show that higher order moments do not converge well even for resolutions up to 3072^2x1024 or 1536^3, doubting previous measurements of very anomalous scalings. Another interesting physical quantity is the residual energy, i.e. the difference between magnetic and kinetic energy. While truly universal strong turbulence should have scale-independent fraction of residual energy, it is usually observed to be scale dependent both in the solar wind measurements and simulations. Based on the trends observed in numerics we conjecture that such constant fraction will not be observed unless the inertial range is larger than three orders of magnitude in scale. The bottom line is that, while we expect -5/3 scaling for strong MHD turbulence, even in the solar wind, which covers several orders of magnitude in scale, the statistics will be affected by outer scale effects.

Beresnyak, A.

2012-12-01

160

Supercavitation Ventilation Control System.  

National Technical Information Service (NTIS)

A supercavitation ventilation control system is disclosed and includes a vehicle body having a fore end and an aft end. A cavitator is fit to the fore end of the vehicle body, the cavitator generating a gas cavity around the vehicle body. A cavity control...

R. Kuklinski

2002-01-01

161

Laboratory Ventilation and Safety.  

ERIC Educational Resources Information Center

In order to meet the needs of both safety and economy, laboratory ventilation systems must effectively remove air-borne toxic and flammable materials and at the same time exhaust a minimum volume of air. Laboratory hoods are the most commonly used means of removing gases, dusts, mists, vapors, and fumed from laboratory operations. To be effective,…

Steere, Norman V.

1965-01-01

162

Volume-targeted ventilation.  

PubMed

Recognition that volume, not pressure, is the key factor in ventilator-induced lung injury and awareness of the association of hypocarbia and brain injury foster the desire to better control delivered tidal volume. Recently, microprocessor-based modifications of pressure-limited, time-cycled ventilators were developed to combine advantages of pressure-limited ventilation with the ability to deliver a more consistent tidal volume. Each of the modes has advantages and disadvantages, with limited clinical data available to judge their effectiveness. The Volume Guarantee mode has been studied most thoroughly and is the only one that provides automatic weaning of peak pressure in response to improving lung compliance and patient respiratory effort. More consistent tidal volume, fewer excessively large breaths, lower peak pressure, less hypocarbia and lower levels of inflammatory cytokines have been documented. It remains to be seen if these short-term benefits will translate into shorter duration of ventilation or reduced incidence of chronic lung disease. PMID:15861164

Keszler, Martin

2005-05-01

163

Space station ventilation study  

NASA Technical Reports Server (NTRS)

A ventilation system design and selection method which is applicable to any manned vehicle were developed. The method was used to generate design options for the NASA 33-foot diameter space station, all of which meet the ventilation system design requirements. System characteristics such as weight, volume, and power were normalized to dollar costs for each option. Total system costs for the various options ranged from a worst case $8 million to a group of four which were all approximately $2 million. A system design was then chosen from the $2 million group and is presented in detail. A ventilation system layout was designed for the MSFC space station mockup which provided comfortable, efficient ventilation of the mockup. A conditioned air distribution system design for the 14-foot diameter modular space station, using the same techniques, is also presented. The tradeoff study resulted in the selection of a system which costs $1.9 million, as compared to the alternate configuration which would have cost $2.6 million.

Colombo, G. V.; Allen, G. E.

1972-01-01

164

Patient-ventilator dyssynchrony during assisted invasive mechanical ventilation.  

PubMed

Patient-ventilator dyssynchrony is common during mechanical ventilation. Dyssynchrony decreases comfort, prolongs mechanical ventilation and intensive care unit stays, and might lead to worse outcome. Dyssynchrony can occur during the triggering of the ventilator, the inspiration period after triggering, the transition from inspiration to expiration, and the expiratory phase. The most common dyssynchronies are delayed triggering, autotriggering, ineffective inspiratory efforts (which can occur at any point in the respiratory cycle), mismatch between the patient's and ventilator's inspiratory times, and double triggering. At present, the detection of dyssynchronies usually depends on healthcare staff observing ventilator waveforms; however, performance is suboptimal and many events go undetected. To date, technological complexity has made it impossible to evaluate patient-ventilator synchrony throughout the course of mechanical ventilation. Studies have shown that a high index of dyssynchrony may increase the duration of mechanical ventilation. Better training, better ventilatory modes, and/or computerized systems that permit better synchronization of patients' demands and ventilator outputs are necessary to improve patient-ventilator synchrony. PMID:23254162

Murias, G; Villagra, A; Blanch, L

2013-04-01

165

Imbalance on a Baroclinically Unstable Interior Front  

NASA Astrophysics Data System (ADS)

In rotating stratified flows of atmospheric and oceanic relevance, the balanced nature of turbulence at scales comparable to the Rossby deformation radius leads to a confinement of energy at the large scales---scales at which eddy and turbulent dissipative processes are ineffective. In the oceanic context, given that ocean circulation is forced mostly at the large scales, a fundamental question regarding the energetics of ocean circulation is as to how the ocean equilibrates. The forward energy cascade of small-scale, three dimensional turbulence is in contrast to the inverse cascade of energy that is characteristic of the above quasi-two-dimensional balanced turbulence. Consequently, the scales and phenomena that span these two asymptotic regimes of turbulence and the interactions of the flow with boundaries are expected to hold the answer to the ocean-equilibration question. In this context, a great amount of research effort in the recent past has focussed on surface and bottom boundary related processes. However, the bulk of the balanced energy resides in the vertical interior and there is the alternative (spatially) more local route to dissipation directly through the interior turbulent cascade (e.g., as pointed out in Molemaker et al., 2005). We study processes and phenomenology associated with such interior turbulent cascades by considering setups that span the range of scales from the deformation radius to scales where imbalance is possible. However, the nature of the turbulent cascades themselves determine as to whether the smaller of the resolved scales can effectively break balance and provide a route that dissipates balanced energy. Are any of the small scales imbalanced---i.e., are they effective in cascading energy down to small scales?

Nadiga, B. T.

2013-12-01

166

Perfusion Bioreactor Module  

NASA Technical Reports Server (NTRS)

Perfusion bioreactor module, self-contained, closed-loop cell-culture system that operates in microgravity or on Earth. Equipment supports growth or long-term maintenance of cultures of human or other fragile cells for experiments in basic cell biology or process technology. Designed to support proliferation (initially at exponential rates of growth) of cells in complex growth medium and to maintain confluent cells in defined medium under conditions optimized to permit or encourage selected functions of cells, including secretion of products of cells into medium.

Morrison, Dennis R.

1990-01-01

167

ASHRAE and residential ventilation  

SciTech Connect

In the last quarter of a century, the western world has become increasingly aware of environmental threats to health and safety. During this period, people psychologically retreated away from outdoors hazards such as pesticides, smog, lead, oil spills, and dioxin to the seeming security of their homes. However, the indoor environment may not be healthier than the outdoor environment, as has become more apparent over the past few years with issues such as mold, formaldehyde, and sick-building syndrome. While the built human environment has changed substantially over the past 10,000 years, human biology has not; poor indoor air quality creates health risks and can be uncomfortable. The human race has found, over time, that it is essential to manage the indoor environments of their homes. ASHRAE has long been in the business of ventilation, but most of the focus of that effort has been in the area of commercial and institutional buildings. Residential ventilation was traditionally not a major concern because it was felt that, between operable windows and envelope leakage, people were getting enough outside air in their homes. In the quarter of a century since the first oil shock, houses have gotten much more energy efficient. At the same time, the kinds of materials and functions in houses changed in character in response to people's needs. People became more environmentally conscious and aware not only about the resources they were consuming but about the environment in which they lived. All of these factors contributed to an increasing level of public concern about residential indoor air quality and ventilation. Where once there was an easy feeling about the residential indoor environment, there is now a desire to define levels of acceptability and performance. Many institutions--both public and private--have interests in Indoor Air Quality (IAQ), but ASHRAE, as the professional society that has had ventilation as part of its mission for over 100 years, is the logical place to provide leadership. This leadership has been demonstrated most recently by the publication of the first nationally recognized standard on ventilation in homes, ASHRAE Standard 62.2-2003, which builds on work that has been part of ASHRAE for many years and will presumably continue. Homeowners and occupants, which includes virtually all of us, will benefit from the application of Standard 62.2 and use of the top ten list. This activity is exactly the kind of benefit to society that the founders of ASHRAE envisioned and is consistent with ASHRAE's mission and vision. ASHRAE members should be proud of their Society for taking leadership in residential ventilation.

Sherman, Max H.

2003-10-01

168

Mitonuclear protein imbalance as a conserved longevity mechanism  

PubMed Central

Longevity is regulated by a network of intimately linked metabolic systems. We used a combination of mouse population genetics and RNAi in C. elegans to identify mitochondrial ribosomal protein S5 (Mrps5) and other mitochondrial ribosomal proteins (MRPs) as metabolic and longevity regulators. MRP knockdown triggers mitonuclear protein imbalance, reducing mitochondrial respiration and activating the mitochondrial unfolded protein response (UPRmt). Specific antibiotics targeting mitochondrial translation and ethidium bromide, which impairs mitochondrial DNA transcription, pharmacologically mimic mrp knockdown and extend lifespan by inducing mitonuclear protein imbalance, also in mammalian cells. In addition, resveratrol and rapamycin, longevity compounds acting on different molecular targets, similarly induced mitonuclear protein imbalance, UPRmt and lifespan extention in C. elegans. Collectively these data demonstrate that MRPs represent an evolutionary conserved protein family that ties the mitochondrial ribosome and mitonuclear protein imbalance to UPRmt, an overarching longevity pathway across multiple species.

Houtkooper, Riekelt H.; Mouchiroud, Laurent; Ryu, Dongryeol; Moullan, Norman; Katsyuba, Elena; Knott, Graham; Williams, Robert W.; Auwerx, Johan

2013-01-01

169

Tests Conditional on Imbalance with Biased Coin Designs.  

National Technical Information Service (NTIS)

Distributional properties of the treatment assignment variables T sub 1, ..., T sub n under Efron's (1971) biased coin design are derived. These properties are conditional on the terminal imbalance of the treatment allocation. Recursive procedures are pre...

M. Hollander E. Pena

1986-01-01

170

Three-Dimensional Mapping of Ozone-Induced Acute Cytotoxicity in Tracheobronchial Airways of Isolated Perfused Rat Lung  

Microsoft Academic Search

Acute lung injury induced by reactive oxygen gases such as ozone (O 3 ) is focal and site-selective. To de- fine patterns of acute epithelial injury along intrapulmonary airways, we developed a new analytic ap- proach incorporating labeling of permeable cells, airway microdissection, and laser scanning confocal mi- croscopy, and applied it to isolated perfused rat lungs where ventilation and

Edward M. Postlethwait; Jessie P. Joad; Dallas M. Hyde; Edward S. Schelegle; John M. Bric; Alison J. Weir; Leialoha F. Putney; Viviana J. Wong; Leonard W. Velsor; Charles G. Plopper

171

Lateral imbalance detection on a UAV based on multiple models  

Microsoft Academic Search

This paper addresses a multiple-model based lateral imbalance detection methodology for an uninhabited air vehicle (UAV). Two critical imbalance failures are considered that are the failure-induced left aileron stuck and the centre-of-gravity shift along the y-axis. A bank of LTI Kalman filters are designed to detect the above lateral failures and a flight control law based on the model predictive

Sajjad Fekri; Da-Wei Gu; Ian Postlethwaite

2009-01-01

172

Local laboratory ventilation devices  

SciTech Connect

This article is a discussion of the ``other`` laboratory ventilation devices described in OSHA`s laboratory standard that could be used in lieu of traditional chemical fume hoods. The reference ``local`` or ``other`` ventilation device is used with little or no information provided as to the type, design, or performance criteria appropriate for specific applications, as was done in excruciating detail for their fume hood cousins. Equally curious is the fact that no performance test criteria were established for this category of equipment. Therefore, great care must be taken by the designer to determine the specific application intended for each unit specified and confirm that its use is appropriate for the task. In light of these standards, manufacturers have responded with many new and innovative products.

Koenigsberg, J. [GPR Planners Collaborative, White Plains, NY (United States)

1995-10-01

173

DRIS analysis identifies a common potassium imbalance in sweetgum plantations.  

SciTech Connect

DRIS (Diagnosis and Recommendation Integrated System) analysis was applied to fast-growing sweetgum (Liquidambar styraciflua L.) plantations in the southeast United States as a tool for nutrient diagnosis and fertilizer recommendations. First, standard foliar nutrient ratios for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were established using high-yield stands from a region wide sweetgum fertilization study. DRIS indices were then calculated for the low-yield stands in the same study and stands from four other studies to evaluate foliar nutritional characteristics. Low-yield stands showed strong negative K imbalance, indicating insufficient K, but also showed strong positive Mg imbalance. Potassium imbalance was also observed in the other four data sets tested. DRIS analysis successfully identified the tendency for K insufficiency to increase from early to late in the growing season, probably due to K foliar leaching and low soil K supply. While insufficient N was common in all the stands tested, the DRIS analysis failed to identify any P imbalance. We recommend that K be applied in N:K ratios less than one to correct K imbalance problems in the studied sweetgum plantations. Supra-optimal Ca and Mg levels are expected to decline once insufficient N and K are corrected. DRIS analysis provides the means for diagnosing nutrient imbalance and a potential basis for prescribing corrective amendments in sweetgum plantations.

Coleman, M., D.; Chang, S., X.; Robison, D.J.

2003-01-01

174

Neutrophil passage through isolated perfused rabbit lungs.  

PubMed

Kinetics of polymorphonuclear leukocyte (PMN) lung passage were investigated in ex vivo isolated and ventilated left rabbit lungs, perfused with buffer solution at physiological flow rate. 111In-labeled PMNs of rabbit or human origin were injected into the pulmonary artery, and the first fraction of PMNs that rapidly passed the lung together with coinjected erythrocytes, was collected separately for external radioactivity counting. Washout of initially retained PMNs from the lung was monitored by use of a sodium-iodide detector. Recirculation of cells was avoided by insertion of a filter in the perfusion circuit. A fraction of 16.6 +/- 1.3% of rabbit PMNs rapidly passed the lung vasculature, followed by an exponential washout of initially retained PMNs [half-time (t50) of lung transit 8.1 +/- 0.6 min]. Slightly higher t50 (12.2 +/- 1.0 min) was obtained upon use of human PMNs. Reduction in flow by 50% caused a marked prolongation of PMN transit (t50 = 27.8 +/- 5.1 min), whereas increase in flow to 150% only insignificantly decreased t50. Rise in pulmonary venous pressure to 5 and 8 mmHg caused retardation of PMN lung transit (t50 = 15.3 +/- 0.6 and 31.6 +/- 3.6 min). Preincubation of PMNs with 2 ng/ml endotoxin for 1 h induced marked delay in PMN washout (t50 = 26.1 +/- 2.8 min). In conclusion, single-pass PMN kinetics in isolated lungs correspond to in vivo studies previously reported, thus allowing elucidation of PMN-endothelial interactions in an intact lung vasculature under standardized conditions. PMID:1928412

Schütte, H; Rosseau, S; Walmrath, D; Grimminger, F; Ernst, C; Seeger, W

1991-10-01

175

Attenuation of ischemia reperfusion-induced lung edema by prostaglandin I 2 analogue OP2507 in the isolated perfused rat lung  

Microsoft Academic Search

Using the physiological salt solution (PSS)\\/Ficollperfused rat lung, we studied the effect of prostaglandin I2 (PGI2) analogue, OP-2507, on ischemia-reperfusion lung injury. Ischemia was induced by stopping perfusion and ventilation. Reperfusion\\u000a after 90 min of normothermic ischemia increased mean pulmonary artery perfusion pressure (Ppa) and produced significant lung\\u000a edema. Pretreatment with OP-2507 (200 ng·ml?1 and 1000 ng·ml?1) equally attenuated the

Masahiro Okuda; Kazuhisa Furuhashi; Yasushi Nakai; Homare Amano; Mannosuke Muneyuki

1994-01-01

176

[Certain aspects of continuous ventilation].  

PubMed

The indication of mechanical ventilation is either a failing ventilatory function of the thorax or a failing gas exchange function of the lung. The ventilation affects every organ function in more or less degree. The starting point of long term ventilation is debated, arbitrary. Some ventilatory devices are simulating the natural intrapleural negative pressure principle, but most of them applies intermittent positive pressure into the lung. For improving oxygenation, a moderate level of positive end expiratory pressure, eventually inversed or 1:1 inspiratory:expiratory ratio can be applied. The computerized electronic ventilators offer a big selection of assisting and controlling ventilatory modes, according to the requirements of the patients. For routine use, in ventilatory failure, pressure cycled controlled ventilation, in gas exchange failure, the combination of synchronized intermittent mandatory ventilation, positive end-expiratory pressure and pressure support can be recommended. For special tasks there are existing special ventilatory or other supportive means. In most of the cases some sedation of the ventilated patients is appropriate, muscle paralysing is restricted to a few situations. It is important to humidify the inhaled air. The detailed monitoring of the patients is essential during ventilation. The weaning of the patients from the ventilator is a complex procedure, which involves ventilatory, nutritional, pharmacologic and psychologic interventions. PMID:8233460

Incze, F

1993-10-31

177

Cerebral perfusion pressure and cerebral tissue oxygen tension in a patient during cardiopulmonary resuscitation  

Microsoft Academic Search

Objective: To report on the effects of cardiopulmonary resuscitation (CPR) instituted immediately after a cardiac arrest on cerebral perfusion pressure (CPP) and cerebral tissue oxygen tension (PbrO2).Design: Case report.Setting: ICU of a university hospital.Patient: A head-injured 17-year-old man submitted to multimodal neurological monitoring underwent sudden cardiac arrest and successful CPR.Interventions: External chest compression, 100% oxygen ventilation, volume expansion and standard

Roberto Imberti; Guido Bellinzona; Francesca Riccardi; Michele Pagani; Martin Langer

2003-01-01

178

Ventilation heterogeneity in obesity.  

PubMed

Obesity is associated with important decrements in lung volumes. Despite this, ventilation remains normally or near normally distributed at least for moderate decrements in functional residual capacity (FRC). We tested the hypothesis that this is because maximum flow increases presumably as a result of an increased lung elastic recoil. Forced expiratory flows corrected for thoracic gas compression volume, lung volumes, and forced oscillation technique at 5-11-19 Hz were measured in 133 healthy subjects with a body mass index (BMI) ranging from 18 to 50 kg/m(2). Short-term temporal variability of ventilation heterogeneity was estimated from the interquartile range of the frequency distribution of the difference in inspiratory resistance between 5 and 19 Hz (R5-19_IQR). FRC % predicted negatively correlated with BMI (r = -0.72, P < 0.001) and with an increase in slope of either maximal (r = -0.34, P < 0.01) or partial flow-volume curves (r = -0.30, P < 0.01). Together with a slight decrease in residual volume, this suggests an increased lung elastic recoil. Regression analysis of R5-19_IQR against FRC % predicted and expiratory reserve volume (ERV) yielded significantly higher correlation coefficients by nonlinear than linear fitting models (r(2) = 0.40 vs. 0.30 for FRC % predicted and r(2) = 0.28 vs. 0.19 for ERV). In conclusion, temporal variability of ventilation heterogeneities increases in obesity only when FRC falls approximately below 65% of predicted or ERV below 0.6 liters. Above these thresholds distribution is quite well preserved presumably as a result of an increase in lung recoil. PMID:24651986

Pellegrino, Riccardo; Gobbi, Alessandro; Antonelli, Andrea; Torchio, Roberto; Gulotta, Carlo; Pellegrino, Giulia Michela; Dellacà, Raffaele; Hyatt, Robert E; Brusasco, Vito

2014-05-01

179

Laboratory and Industrial Ventilation  

NASA Technical Reports Server (NTRS)

This handbook supplements the Facilities Engineering Handbook (NHB 7320.1) and provides additional policies and criteria for uniform application to ventilation systems. It expands basic requirements, provides additional design and construction guidance, and places emphasis on those design considerations which will provide for greater effectiveness in the use of these systems. The provisions of this handbook are applicable to all NASA field installations and the Jet Propulsion Laboratory. Since supply of this handbook is limited, abstracts of the portion or portions applicable to a given requirement will be made for the individual specific needs encountered rather than supplying copies of the handbook as has been past practice.

1972-01-01

180

CT Perfusion of the Head  

MedlinePLUS

... Overview In computed tomography (CT) perfusion imaging, special computer software converts contrast enhanced CT images of the ... scanning combines special x-ray equipment with sophisticated computers to produce multiple images or pictures of the ...

181

Ocular perfusion pressure in glaucoma.  

PubMed

This review article discusses the relationship between ocular perfusion pressure and glaucoma, including its definition, factors that influence its calculation and epidemiological studies investigating the influence of ocular perfusion pressure on the prevalence, incidence and progression of glaucoma. We also list the possible mechanisms behind this association, and discuss whether it is secondary to changes in intraocular pressure, blood pressure or both. Finally, we describe the circadian variation of ocular perfusion pressure and the effects of systemic and topical medications on it. We believe that the balance between IOP and BP, influenced by the autoregulatory capacity of the eye, is part of what determines whether an individual will develop optic nerve damage. However, prospective, longitudinal studies are needed to better define the role of ocular perfusion pressure in the development and progression of glaucoma. PMID:24238296

Costa, Vital P; Harris, Alon; Anderson, Douglas; Stodtmeister, Richard; Cremasco, Fernanda; Kergoat, Helene; Lovasik, John; Stalmans, Ingborg; Zeitz, Oliver; Lanzl, Ines; Gugleta, Konstantin; Schmetterer, Leopold

2014-06-01

182

New Aspects in Mechanical Ventilation  

Microsoft Academic Search

We present a short overview on what is state of the art in mechanical ventilation with emphasis on acute lung injury and acute\\u000a respiratory distress syndrome as well as on some newer trends for weaning of the patients from mechanical ventilation.

Christoph Haberthür; Reto Stocker

2006-01-01

183

Evaluation of building ventilation systems  

SciTech Connect

Over the past several years, NIOSH has responded to health hazard evaluation requests from workers in dozens of office environments. Typically, the employees have complained of headache, eye and upper respiratory tract irritation, dizziness, lethargy and the inability to concentrate. Most often inadequate ventilation has been blamed for these complaints. Of paramount importance in the evaluation and correction of these problems is an effective evaluation of the building's ventilation system. Heating, ventilating and air-conditioning conditions that can cause worker stresses include: migration of odors or chemical hazards between building areas; reentrainment of exhaust from building fume hoods or through heat wheels; buildup of microorganisms in the HVAC system components; and poor odor or environmental control due to insufficient fresh outdoor air or system heating or cooling malfunction. The purpose of this paper is to provide an overview of building ventilation systems, the ventilation problems associated with poorly designed or operating systems, and the methodology for effectively evaluating system performance.

Hughes, R.T.; O'Brien, D.M.

1986-04-01

184

CAD of myocardial perfusion  

NASA Astrophysics Data System (ADS)

Our purpose is in the automated evaluation of the physiological relevance of lesions in coronary angiograms. We aim to extract as much as possible quantitative information about the physiological condition of the heart from standard angiographic image sequences. Coronary angiography is still the gold standard for evaluating and diagnosing coronary abnormalities as it is able to locate precisely the coronary artery lesions. The dimensions of the stenosis can be assessed nowadays successfully with image processing based Quantitative Coronary Angiography (QCA) techniques. Our purpose is to assess the clinical relevance of the pertinent stenosis. We therefore analyze the myocardial perfusion as revealed in standard angiographic image sequences. In a Region-of-Interest (ROI) on the angiogram (without an overlaying major blood vessel) the contrast is measured as a function of time (the so-called time-density curve). The required hyperemic state of exercise is induced artificially by the injection of a vasodilator drug e.g. papaverine. In order to minimize motion artifacts we select based on the recorded ECG signal end-diastolic images in both a basal and a hyperemic run in the same projection to position the ROI. We present the development of the algorithms together with results of a small study of 20 patients which have been catheterized following the standard protocol.

Storm, Corstiaan J.; Slump, Cornelis H.

2007-03-01

185

MR Perfusion Imaging in Acute Ischemic Stroke  

PubMed Central

MR perfusion imaging offers the potential for measuring brain perfusion in acute stroke patients, at a time when treatment decisions based upon these measurements may affect outcomes dramatically. Rapid advancements in both acute stroke therapy and perfusion imaging techniques have resulted in continuing redefinition of the role that perfusion imaging should play in patient management. This review first discusses the basic pathophysiology of acute stroke, with specific attention to alterations in the various perfusion-related parameters that can be studied by MR perfusion imaging. Although these parameters are sometimes treated as somewhat interchangeable, they reveal greatly different information about brain perfusion. Therefore, subsequent discussion of the utility of different kinds of perfusion images focuses on the differences between them, as well as important artifacts that can complicate their interpretation. Finally, research on the continually evolving role of MR perfusion imaging in acute stroke care is summarized.

Copen, William A.; Schaefer, Pamela W.; Wu, Ona

2011-01-01

186

46 CFR 153.312 - Ventilation system standards.  

Code of Federal Regulations, 2013 CFR

...ft) from openings into or ventilation intakes for, accommodation or service spaces. (b) A ventilation system must not recycle vapors from ventilation discharges. (c) Except for the space served by the ventilation duct, a ventilation duct...

2013-10-01

187

Digital Compensation of IQ Imbalance for Dual-Carrier Double Conversion Receivers  

NASA Astrophysics Data System (ADS)

A receiver architecture and a digital IQ imbalance compensation method for dual-carrier reception are newly proposed. The impact of IQ imbalance on the baseband signal is mathematically analyzed. Based on the analysis, IQ imbalance parameters are estimated and the coupling effect of IQ imbalance is compensated using digital baseband processing alone. Simulation results show that the proposed IQ imbalance compensation successfully removes IQ imbalance. The deviation from the ideal performance is less than 1dB when it is applied to the 3GPP-LTE carrier aggregation.

Park, Chester Sungchung; Park, Fitzgerald Sungkyung

188

Discursive imbalance and deficiency in intercultural news communication  

Microsoft Academic Search

Intercultural news communication has become increasingly common in our current era of globalization. But why are certain topics and certain modes of speech adopted in news making rather than others, leading to discursive imbalance? Why are alternative modes of communication often excluded when news travels from one culture to another, causing discursive deficiency? We take a constructivist approach in this

Bo Shan; Lijun Wan

2008-01-01

189

Do equilibrium constraints modulate postural reaction when viewing imbalance?  

PubMed

Action observation and action execution are tightly coupled on a neurophysiological and a behavioral level, such that visually perceiving an action can contaminate simultaneous and subsequent action execution. More specifically, observing a model in postural disequilibrium was shown to induce an increase in observers' body sway. Here we reciprocally questioned the role of observers' motor system in the contagion process by comparing participants' body sway when watching displays of antero-posterior vs. lateral imbalance. Indeed, during upright standing, biomechanical constraints differ along the antero-posterior (A-P) and medio-lateral (M-L) axes; hence an impact of observers' postural constraints on the contagion response would result in different reactions to both types of stimuli. In response to the displays, we recorded greater area of center of pressure (CoP) displacement when watching forward/backward compared to left/right imbalance. In addition, after normalizing A-P and M-L CoP displacements by a control condition (fixation cross), A-P CoP path length when viewing forward imbalance tended to be higher than M-L CoP path length when viewing imbalance to the left or right. These results indicate that postural contagion is promoted when the display is compatible with observers' motor stabilization strategy which is mainly oriented along the A-P axis. In terms of clinical application, this study brings new indications for adaptation of observational training devices in rehabilitation programs. PMID:22466502

Tia, Banty; Paizis, Christos; Mourey, France; Pozzo, Thierry

2012-07-01

190

THE ROLE OF INORGANIC ION IMBALANCE IN AQUATIC TOXICITY TESTING  

EPA Science Inventory

Effluent toxicity testing methods have been well defined, but to a large part have not attempted to segregate the effects of active ionic concentrations and ion imbalances upon test and species performances. The role that various total dissolved solids in effluents have on regula...

191

Analysis of imbalance response of the rotor test bed  

Microsoft Academic Search

The calculation of imbalance response plays an important role in the dynamical analysis of rotor-bearing system, the FEM is one of the methods that can calculate the dynamical response, and the ANSYS is a large finite element analysis software. This paper studies on the rotor test bed, and the supporting condition of the rotor-bearing is set in reason with the

Honghong Fan; Xiaodong Zhang

2008-01-01

192

Gender Imbalance in Accounting Academia: Past and Present  

ERIC Educational Resources Information Center

Studies conducted in the late 1980s and early 1990s reflected a gender imbalance in the accounting academy as the proportion of female professors fell far below the percentage of women accountants in practice. For a sample of doctoral-granting and nondoctoral-granting Association to Advance Collegiate Schools of Business (AACSB) institutions, the…

Jordan, Charles E.; Pate, Gwen R.; Clark, Stanley J.

2006-01-01

193

Prognostic Value of Allelic Imbalance in Prostate Biopsy.  

National Technical Information Service (NTIS)

Purpose: The novel Concept that is being tested in this project is that allelic imbalance (Al) in tissue obtained at prostate biopsy can serve as a sensitive and independent marker for staging and predicting disease recurrence in prostate cancer. Scope: T...

J. K. Griffith

2006-01-01

194

Prognostic Value of Allelic Imbalance in Prostate Biopsy.  

National Technical Information Service (NTIS)

The novel concept that is being tested in this project is that allelic imbalance (AI) in tissue obtained at prostate biopsy can serve as a sensitive and independent marker for staging and predicting disease recurrence in prostate cancer. The two aims of t...

J. K. Griffith

2005-01-01

195

Social skill imbalances in mood disorders and schizophrenia  

Microsoft Academic Search

Social skills traditionally have been conceptualized as a global construct with a linear relationship to clinical symptoms (i.e., more severe symptoms lead to greater social skill deficits). Using a multidimensional model of social skills, we define social skill imbalance as an extreme score (too high or too low) on any one or more dimensions in relation to the other social

John E. Perez; Ronald E. Riggio; Alex Kopelowicz

2007-01-01

196

Digital compensation of branches imbalance effects in LINC transmitters  

Microsoft Academic Search

A study of the branch complex gain imbalance effects, as a distortion source, in term of adjacent channel power ratio and signal dynamic range is carried out in this paper. Although a linearity improvement is achieved using a digital predistortion when considering the imbalanced LINC transmitter as a memoryless nonlinear system, this method suffers from a limited dynamic range restitution

M. Helaoui; S. Boumaizal; A. Ghazel; F. M. Ghannouchi

2004-01-01

197

An adaptive digital method of imbalances cancellation in LINC transmitters  

Microsoft Academic Search

The linear amplification using nonlinear components (LINC) technique is a well-known power amplifier linearization method to reduce adjacent channel interference in a nonconstant envelope modulation system. Its major drawback is the inherent sensitivity to gain and phase imbalances between the two amplifier branches. In this paper, a novel full-digital base band method is described which corrects any gain and phase

Paloma García; Jesús de Mingo; Antonio Valdovinos; Alfonso Ortega

2005-01-01

198

Ageing and Fiscal Imbalances Across Generations: Concepts of Measurement  

Microsoft Academic Search

In the literature, several approaches have been taken to measure the impact of demographic ageing on public pension schemes, with particular attention being paid to potential fiscal imbalances across the generations involved in demographic transition. In this paper, we review three of these measures - viz., “net pension liabilities” and “general government fiscal balances” as suggested by the OECD, as

Robert Fenge; Martin Werding

2003-01-01

199

Charge imbalance in superconductors in the low-temperature limit  

NASA Astrophysics Data System (ADS)

We explore charge imbalance in mesoscopic normal-metal/superconductor multiterminal structures at very low temperatures. The investigated samples, fabricated by e-beam lithography and shadow evaporation, consist of a superconducting aluminum bar with several copper wires forming tunnel contacts at different distances from each other. We have measured in detail the local and nonlocal conductance of these structures as a function of the applied bias voltage V , the applied magnetic field B , the temperature T , and the contact distance d . From these data the charge-imbalance relaxation length ?Q? is derived. The bias-resolved measurements show a transition from dominant elastic scattering close to the energy gap to an inelastic two-stage relaxation at higher bias. We observe a strong suppression of charge imbalance with magnetic field, which can be directly linked to the pair-breaking parameter. In contrast, practically no temperature dependence of the charge-imbalance signal was observed below 0.5 K. These results are relevant for the investigation of other nonlocal effects such as crossed Andreev reflection and spin diffusion.

Hübler, F.; Lemyre, J. Camirand; Beckmann, D.; v. Löhneysen, H.

2010-05-01

200

Chromosomal Imbalances in Lymphoid Tumors of the Orbit  

Microsoft Academic Search

PURPOSE. To identify chromosomal gains and losses in lymphoid tumors of the orbit and to examine whether such abnormalities are related to orbital presentation, disease severity, or risk for recurrent disease. METHODS. Biopsy specimens from 26 patients were examined by histomorphologic and immunohistochemical analysis. Lym- phomas were classified according to the Revised European- American Lymphoma Classification. Chromosomal imbalances were detected

Gro Oddveig Ness; Helle Lybæk; Jarle Arnes; Eyvind Rødahl

201

Clothing ventilation - update and applications.  

PubMed

The Environmental Ergonomics Unit at the P.O.W. provided a forum for the discussion and consolidation of ideas regarding the origins, current progress and the future development of the Clothing Ventilation Index. Crockford et al (1972) first developed the concept of clothing ventilation. The basic technique employs a trace gas dilution method for measuring the ventilation of the clothing microclimate. Ventilation is vital to the removal of sensible and insensible heat and, therefore, an important determinant of thermal comfort. Two techniques (Lotens and Havenith, 1986, 1988; Reischl et al, 1987) have subsequently been developed. The former method results in an average ventilation value for the total clothed-body surface area, whereas the latter method also takes into consideration regional changes in garment design as separate entities from the total ventilation, allowing for local modification in garment design. The Clothing Ventilation Index is a quantitative, relatively inexpensive, fast, reliable and repeatable technique. It can be used in context, in the working environment to predict the effectiveness, preference and suitability of garments and clothing assemblies; firstly, to ensure that protective clothing is worn and used correctly, and secondly, to improve performance by minimising heat strain, sweat retention and thermal discomfort. Further work on validating the techniques in terms of human responses to the thermal environment is required. Questions were also raised as to whether human beings or manikins should be used. The use of human beings in dynamic situations is of paramount importance; however, manikins could be used for purely physical measurements to test various assumptions in evaluating clothing ventilation. It is essential that body dimensions and posture are always specified. The seminar enabled researchers to identify with the proposed techniques, outline the advantages and importance of the Clothing Ventilation Index and focus future studies. PMID:15676838

Lumley, S H; Story, D L; Thomas, N T

1991-12-01

202

Strong magnetic fields of the solar photosphere and their imbalance  

NASA Astrophysics Data System (ADS)

Strong photospheric magnetic fields in the sunspot zone were studied on the basis of Kitt Peak synoptic maps (1976 - 2003). The fluxes of the positive and the negative magnetic fields for the Northern and for the Southern solar hemispheres were considered separately. Each of these four fluxes depending on its polarity can be interpreted as the magnetic flux of the leading or the following sunspots of one of the solar hemispheres. All the four fluxes change according to the 11 year solar cycle; nevertheless, there are certain differences in their time dependence. The aim of the present work is to study the regular features of these differences. Thus, we consider: 1) correlations between the above fluxes; 2) the imbalance between the positive and the negative fluxes of the same solar hemisphere; 3) imbalance between the positive and the negative fluxes associated only with the leading sunspots; 4) imbalance between the positive and the negative fluxes for the following sunspots only. The imbalance of the fluxes, associated with the leading sunspots in each of the hemispheres displays the following regular changes in the course of the solar cycle. For the ascending phase of the cycle (from the solar activity minimum to the Sun's global magnetic field inversion) the Northern hemisphere fluxes always play the dominating role, while for the descending phase (from the inversion to the minimum) the Southern hemisphere fluxes dominate. The imbalance of the fluxes of the following sunspots changes analogously. Thus, the North-South asymmetry of the magnetic fluxes results from the domination both of the leading and the following sunspot fluxes in one of the solar hemispheres. The sign of the North-South asymmetry of the magnetic flux remains unchanged (from the solar activity minimum to the global magnetic field inversion and from the inversion to the minimum). The imbalance between the positive and the negative fluxes for the whole equatorial region (heliolatitudes from -40° to +40°) changes in the same way as the imbalance of the leading sunspots. The sign of the imbalance does not change during 11 years from one inversion of the Sun's global magnetic field to the next one and always coincides with the sign of the global magnetic field in the Northern hemisphere. The sign of the North-South asymmetry and the sign of the magnetic flux imbalance are determined by the quarter of the 22-year magnetic cycle during which the magnetic configuration of the local and the global magnetic fields doesn't change (from the minimum, where the sunspots reverse their polarities according to Hale's law, to the inversion of the global magnetic field of the Sun, and from the inversion to the minimum). The sign of the North-South asymmetry depends only on the phase of the solar cycle (before or after the inversion). The sign of the magnetic flux imbalance is determined both by the phase of the solar cycle and by the parity of the solar cycle.

Vernova, Elena; Tyasto, Marta; Baranov, Dmitry

2013-04-01

203

Kinetics of reversible-sequestration of leukocytes by the isolated perfused rat lung  

SciTech Connect

The kinetics and morphology of sequestration and margination of rat leukocytes were studied using an isolated perfused and ventilated rat lung preparation. Whole rat blood, bone marrow suspension, or leukocyte suspensions, were used to perfuse the isolated rat lung. The lung was also perfused with latex particle suspensions and the passage of particles through the lung capillaries was studied. When a leukocyte suspension was perfused through the lung in the single-pass mode, the rate of sequestration decreased as more cells were perfused. In contrast, latex particles of a size comparable to that of leukocytes were totally stopped by the lung. When the leukocyte suspension was recirculated through the lung, cells were rapidly removed from circulation until a steady state was reached, after which no net removal of cells by the lung occurred. These results indicate that leukocytes are reversibly sequestered from circulation. The sequestered cells marginated and attached to the luminal surface of the endothelium of post-capillary venules and veins. A mathematical model was developed based on the assumption that the attachment and detachment of leukocytes to blood vessel walls follows first-order kinetics. The model correctly predicts the following characteristics of the system: (a) the kinetics of the sequestration of leukocytes by the lung; (b) the existence of a steady state when a suspension of leukocytes is recirculated through the lung; and (c) the independence of the fraction of cells remaining in circulation from the starting concentration for all values of starting concentration. (ERB)

Goliaei, B.

1980-08-01

204

Ventilation Criteria for Aeromedical Evacuation.  

National Technical Information Service (NTIS)

Air evacuation of patients requiring mechanical ventilation exposes these individuals to a barometric pressure that is approximately 25% less than normal. This limits the maximum inspired oxygen tension that can be provided as well as possibly altering ve...

R. A. Klocke A. T. Aquilina B. J. B. Grant A. R. Saltzman P. A. Land

1986-01-01

205

Mechanical ventilation in rural ICUs  

PubMed Central

Background: In recent years, rural hospitals have expanded their scope of specialized services, which has led to the development and staffing of rural intensive care units (ICUs). There is little information about the breadth, quality or outcomes of these services. This is particularly true for specialized ICU services such as mechanical ventilation, where little, if any, information exists specifically for rural hospitals. The long-term objectives of this project were to evaluate the quality of medical care provided to mechanically ventilated patients in rural ICUs and to improve patient care through an educational intervention. This paper reports baseline data on patient and hospital characteristics for both rural and rural referral hospitals. Results: Twenty Iowa hospitals were evaluated. Data collected on 224 patients demonstrated a mean age of 70 years and a mean ICU admission Acute Physiology and Chronic Health Evaluation (APACHE) II score of 22, with an associated 36% mortality. Mean length of ICU stay was 10 days, with 7.7 ventilated days. Significant differences were found in both institutional and patient variables between rural referral hospitals and rural hospitals with more limited resources. A subgroup of patients with diagnoses associated with complex ventilation had higher mortality rates than patients without these conditions. Patients who developed nosocomial events had longer mean ventilator and ICU days than patients without nosocomial events. This study also found ICU practices that frequently fell outside the guidelines recommended by a task force describing minimum standards of care for critically ill patients with acute respiratory failure on mechanical ventilation. Conclusions: Despite distinct differences in the available resources between rural referral and rural hospitals, overall mortality rates of ventilated patients are similar. Considering the higher mortality rates observed in patients with complicated medical conditions requiring complex ventilation management, the data may suggest that this subgroup could benefit from treatment at a tertiary center with greater resources and technology.

Fieselmann, John F; Bock, M Jeanne; Hendryx, Michael S; Wakefield, Douglas; Helms, Charles M; Bentler, Suzanne E

1999-01-01

206

Mechanical ventilation in rural ICUs.  

PubMed

BACKGROUND: In recent years, rural hospitals have expanded their scope of specialized services, which has led to the development and staffing of rural intensive care units (ICUs). There is little information about the breadth, quality or outcomes of these services. This is particularly true for specialized ICU services such as mechanical ventilation, where little, if any, information exists specifically for rural hospitals. The long-term objectives of this project were to evaluate the quality of medical care provided to mechanically ventilated patients in rural ICUs and to improve patient care through an educational intervention. This paper reports baseline data on patient and hospital characteristics for both rural and rural referral hospitals. RESULTS: Twenty Iowa hospitals were evaluated. Data collected on 224 patients demonstrated a mean age of 70 years and a mean ICU admission Acute Physiology and Chronic Health Evaluation (APACHE) II score of 22, with an associated 36% mortality. Mean length of ICU stay was 10 days, with 7.7 ventilated days. Significant differences were found in both institutional and patient variables between rural referral hospitals and rural hospitals with more limited resources. A subgroup of patients with diagnoses associated with complex ventilation had higher mortality rates than patients without these conditions. Patients who developed nosocomial events had longer mean ventilator and ICU days than patients without nosocomial events. This study also found ICU practices that frequently fell outside the guidelines recommended by a task force describing minimum standards of care for critically ill patients with acute respiratory failure on mechanical ventilation. CONCLUSIONS: Despite distinct differences in the available resources between rural referral and rural hospitals, overall mortality rates of ventilated patients are similar. Considering the higher mortality rates observed in patients with complicated medical conditions requiring complex ventilation management, the data may suggest that this subgroup could benefit from treatment at a tertiary center with greater resources and technology. PMID:11056720

Fieselmann; Bock; Hendryx; Wakefield; Helms; Bentler

1999-01-01

207

Controversies in patient-triggered ventilation.  

PubMed

Patient-triggered ventilation is a relatively recent development in neonatal mechanical ventilation. Advances in microprocessor-based technology, transducers, and monitoring have enabled patient-driven ventilator control and synchronization of mechanical ventilation with patient effort. The novelty of the newer ventilatory techniques has generated several controversies that remain to be resolved. Among these are signal detection and transduction, the optimal ventilatory modes, and weaning during patient-triggered ventilation. PMID:9523074

Donn, S M; Sinha, S K

1998-03-01

208

Ventilation Model and Analysis Report  

SciTech Connect

This model and analysis report develops, validates, and implements a conceptual model for heat transfer in and around a ventilated emplacement drift. This conceptual model includes thermal radiation between the waste package and the drift wall, convection from the waste package and drift wall surfaces into the flowing air, and conduction in the surrounding host rock. These heat transfer processes are coupled and vary both temporally and spatially, so numerical and analytical methods are used to implement the mathematical equations which describe the conceptual model. These numerical and analytical methods predict the transient response of the system, at the drift scale, in terms of spatially varying temperatures and ventilation efficiencies. The ventilation efficiency describes the effectiveness of the ventilation process in removing radionuclide decay heat from the drift environment. An alternative conceptual model is also developed which evaluates the influence of water and water vapor mass transport on the ventilation efficiency. These effects are described using analytical methods which bound the contribution of latent heat to the system, quantify the effects of varying degrees of host rock saturation (and hence host rock thermal conductivity) on the ventilation efficiency, and evaluate the effects of vapor and enhanced vapor diffusion on the host rock thermal conductivity.

V. Chipman

2003-07-18

209

Sensitivity analysis of voltage imbalance in distribution networks with rooftop PVs  

Microsoft Academic Search

A comprehensive voltage imbalance sensitivity analysis and stochastic evaluation based on the rating and location of single-phase grid-connected rooftop photovoltaic cells (PVs) in a residential low voltage distribution network are presented. The voltage imbalance at different locations along a feeder is investigated. In addition, the sensitivity analysis is performed for voltage imbalance in one feeder when PVs are installed in

Farhad Shahnia; Ritwik Majumder; Arindam Ghosh; Gerard Ledwich; Firuz Zare

2010-01-01

210

Spin imbalance effect on the Larkin-Ovchinnikov-Fulde-Ferrel state  

SciTech Connect

We study spin imbalance effects on the Larkin-Ovchinnikov-Fulde-Ferrel (LOFF) state relevant for superconductors under a strong magnetic field and spin polarized ultracold Fermi gas. We obtain the exact solution for the condensates with arbitrary spin imbalance and the fermion spectrum perturbatively in the presence of small spin imbalance. We also obtain fermion zero mode exactly without perturbation theory.

Yoshii, Ryosuke [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Tsuchiya, Shunji [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan); Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kanagawa 223-8521 (Japan); CREST (JST), 4-1-8 Honcho, Saitama 332-0012 (Japan); Marmorini, Giacomo [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan); Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kanagawa 223-8521 (Japan); Nitta, Muneto [Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kanagawa 223-8521 (Japan); Department of Physics, Keio University, 4-1-1 Hiyoshi, Kanagawa 223-8521 (Japan)

2011-07-01

211

Order imbalance and liquidity supply: Evidence from the bubble burst of Nasdaq stocks  

Microsoft Academic Search

In this study we analyze the effect of order imbalance on the quotation behavior of Nasdaq market makers. We find that Nasdaq market makers use both price and quantity quotes when dealing with order imbalances. However, order imbalance affects only price movement, not spreads. We also find that Nasdaq market makers quote more shares and compete more intensively on bid-side

Mingsheng Li; Timothy McCormick; Xin Zhao

2005-01-01

212

Causes of imbalance and abnormal gait that may be misdiagnosed.  

PubMed

Disorders of gait and balance are common in medicine and often lead to referral for neurologic evaluation. Because the maintenance of balance and normal gait are mediated by complex neurologic pathways as well as musculoskeletal, metabolic, and behavioral considerations, the list of possible contributing causes is very large. Much of the time, the history and neurologic examination reveal the underlying cause or causes. There are instances, however, when there are limited neurologic findings, as well as no structural abnormalities on brain or spine magnetic resonance imaging studies to explain the imbalance or gait difficulty. In this article, selected disorders that may be overlooked in the neurologic examination and imaging studies are reviewed. Possible causes of imbalance include occult drug-induced ataxia, autoimmune ataxia, ataxia associated with tremor, bilateral vestibular hypofunction, and spastic or dystonic gait disorders with normal imaging. PMID:24057830

Shill, Holly A; Fife, Terry D

2013-07-01

213

Vorticity imbalance and stability in relation to convection  

NASA Technical Reports Server (NTRS)

A complete synoptic-scale vorticity budget was related to convection storm development in the eastern two-thirds of the United States. The 3-h sounding interval permitted a study of time changes of the vorticity budget in areas of convective storms. Results of analyses revealed significant changes in values of terms in the vorticity equation at different stages of squall line development. Average budgets for all areas of convection indicate systematic imbalance in the terms in the vorticity equation. This imbalance resulted primarily from sub-grid scale processes. Potential instability in the lower troposphere was analyzed in relation to the development of convective activity. Instability was related to areas of convection; however, instability alone was inadequate for forecast purposes. Combinations of stability and terms in the vorticity equation in the form of indices succeeded in depicting areas of convection better than any one item separately.

Read, W. L.; Scoggins, J. R.

1977-01-01

214

Spinal pedicle subtraction osteotomy for fixed sagittal imbalance patients  

PubMed Central

In addressing spinal sagittal imbalance through a posterior approach, the surgeon now may choose from among a variety of osteotomy techniques. Posterior column osteotomies such as the facetectomy or Ponte or Smith-Petersen osteotomy provide the least correction, but can be used at multiple levels with minimal blood loss and a lower operative risk. Pedicle subtraction osteotomies provide nearly 3 times the per-level correction of Ponte/Smith-Petersen osteotomies; however, they carry increased technical demands, longer operative time, and greater blood loss and associated significant morbidity, including neurological injury. The literature focusing on pedicle subtraction osteotomy for fixed sagittal imbalance patients is reviewed. The long-term overall outcomes, surgical tips to reduce the complications and suggestions for their proper application are also provided.

Hyun, Seung-Jae; Kim, Yongjung J; Rhim, Seung-Chul

2013-01-01

215

Perfusion decellularization of whole organs.  

PubMed

The native extracellular matrix (ECM) outlines the architecture of organs and tissues. It provides a unique niche of composition and form, which serves as a foundational scaffold that supports organ-specific cell types and enables normal organ function. Here we describe a standard process for pressure-controlled perfusion decellularization of whole organs for generating acellular 3D scaffolds with preserved ECM protein content, architecture and perfusable vascular conduits. By applying antegrade perfusion of detergents and subsequent washes to arterial vasculature at low physiological pressures, successful decellularization of complex organs (i.e., hearts, lungs and kidneys) can be performed. By using appropriate modifications, pressure-controlled perfusion decellularization can be achieved in small-animal experimental models (rat organs, 4-5 d) and scaled to clinically relevant models (porcine and human organs, 12-14 d). Combining the unique structural and biochemical properties of native acellular scaffolds with subsequent recellularization techniques offers a novel platform for organ engineering and regeneration, for experimentation ex vivo and potential clinical application in vivo. PMID:24874812

Guyette, Jacques P; Gilpin, Sarah E; Charest, Jonathan M; Tapias, Luis F; Ren, Xi; Ott, Harald C

2014-06-01

216

Developing a tissue perfusion sensor.  

PubMed

The development of a electrochemical tissue perfusion sensor is presented. The sensor is a platinum/platinum ring-disc microelectrode that relies on the principle of collector-generator to monitor mass transport within its vicinity. Tissue perfusion is a mass transport mechanism that describes the movement of respiratory gases, nutrients and metabolites in tissue. The sensor's capability of detecting perfusion at the cellular level in a continuous fashion is unique. This sensor will provide insight into the way nutrients and metabolites are transported in tissue especially in cases were perfusion is low such as in wounds or ischemic tissue. We present experimental work for the development and testing of the sensors in vitro. Experimental flow recordings in free steam solutions as well as the flow through tissue-like media are shown. Tests on post operative human tissue are also presented. The sensor's feature such as the continuous recoding capacities, spatial resolution and the measurement range from ml/min to microl/min are highlighted. PMID:18002549

Harvey, S L R; Parker, K H; O'Hare, D

2007-01-01

217

Time domain IQ imbalance compensation for wideband wireless systems  

Microsoft Academic Search

A time domain IQ compensation approach is proposed for wideband application where the IQ imbalance is frequency dependent. The proposed approach relies on known signal such as preamble in orthogonal frequency-division multiplexing (OFDM) signal data frame and radar echoes. Signal correlation property is used for noise elimination and signal frequency spectrum is divided into several sub-bands to deal with frequency-dependent

Cun Feng Gu; Choi Look Law; Wen Wu

2010-01-01

218

Child Underreporting, Fertility, and Sex Ratio Imbalance in China  

Microsoft Academic Search

Child underreporting is often neglected in studies of fertility and sex ratio imbalance in China. To improve estimates of\\u000a these measures, I use intercensal comparisons to identify a rise in underreporting, which followed the increased enforcement\\u000a and penalization under the birth planning system in 1991. A new triangulation of evidence indicates that about 19% of children\\u000a at ages 0–4 were

Daniel Goodkind

2011-01-01

219

Allelic imbalance and biochemical outcome after radical prostatectomy  

Microsoft Academic Search

Objective:To compare the incidence of allelic imbalance (AI) in men with rapid disease progression with those who remained disease free after radical prostatectomy, with the aim of identifying genetic markers to predict prognosis and guide further treatment.Patients and methods:Tumour and normal DNA were extracted from two matched groups of 31 men with extracapsular node-negative (pT3N0) prostate cancer who had undergone

S R J Bott; J R W Masters; M C Parkinson; R S Kirby; M Feneley; J Hooper; M Williamson; SRJ Bott

2006-01-01

220

Flux emergence, flux imbalance, magnetic free energy and solar flares  

NASA Astrophysics Data System (ADS)

Emergence of complex magnetic flux in the solar active regions lead to several observational effects such as a change in sunspot area and flux embalance in photospheric magnetograms. The flux emergence also results in twisted magnetic field lines that add to free energy content. The magnetic field configuration of these active regions relax to near potential-field configuration after energy release through solar flares and coronal mass ejections. In this paper, we study the relation of flare productivity of active regions with their evolution of magnetic flux emergence, flux imbalance and free energy content. We use the sunspot area and number for flux emergence study as they contain most of the concentrated magnetic flux in the active region. The magnetic flux imbalance and the free energy are estimated using the HMI/SDO magnetograms and Virial theorem method. We find that the active regions that undergo large changes in sunspot area are most flare productive. The active regions become flary when the free energy content exceeds 50% of the total energy. Although, the flary active regions show magnetic flux imbalance, it is hard to predict flare activity based on this parameter alone.

Choudhary, Debi Prasad; Gosain, Sanjay; Gopalswamy, Nat; Manoharan, P. K.; Chandra, R.; Uddin, W.; Srivastava, A. K.; Yashiro, S.; Joshi, N. C.; Kayshap, P.; Dwivedi, V. C.; Mahalakshmi, K.; Elamathi, E.; Norris, Max; Awasthi, A. K.; Jain, R.

2013-10-01

221

Adventitial Perfusion and Intraplaque Hemorrhage  

PubMed Central

Background and Purpose Autopsy studies have suggested a relationship between intraplaque hemorrhage (IPH) and vasa vasorum, which arise primarily from the adventitia. Adventitial vasa vasorum can be characterized in the carotid arteries by estimating perfusion parameters via dynamic contrast-enhanced MRI. The purpose of this investigation was to use dynamic contrast-enhanced MRI to test in vivo in a clinical population whether adventitial perfusion, indicative of vasa vasorum microstructure, is associated with IPH. Methods Symptomatic patients with carotid plaque ipsilateral to the ischemic event underwent bilateral carotid artery MRI examination, which included multicontrast sequences for detecting IPH and a dynamic contrast-enhanced MRI sequence for characterizing adventitial perfusion. Kinetic modeling of the dynamic contrast-enhanced MRI time series was performed to estimate adventitial vp (fractional plasma volume, reflecting local blood supply) and Ktrans (transfer constant, reflecting vessel surface area, and permeability). Results From the 27 patients (22 men; 69±10 years of age) recruited, adventitial perfusion parameters were obtained in 50 arteries. The presence of IPH was associated with a significantly higher value in adventitial Ktrans (0.142±0.042 vs 0.112±0.029 min?1; P<0.001) but not in vp (0.163±0.064 vs 0.149±0.062; P=0.338). This relationship remained after adjusting for symptomatic status, degree of stenosis, and other confounding factors. Conclusions This study demonstrated an independent pathophysiological link between the adventitia and IPH and related it to the microstructure of adventitial vasa vasorum. Adventitial perfusion imaging may be useful in studying plaque pathogenesis, but further examination through prospective studies is needed.

Sun, Jie; Song, Yan; Chen, Huijun; Kerwin, William S.; Hippe, Daniel S.; Dong, Li; Chen, Min; Zhou, Cheng; Hatsukami, Thomas S.; Yuan, Chun

2014-01-01

222

ICA-based compensation for IQ imbalance in OFDM optical fiber communication  

NASA Astrophysics Data System (ADS)

A method based on the independent component analysis (ICA) is proposed to compensate the in-phase and quadrature-phase the (IQ) imbalance in orthogonal frequency division multiplexing (OFDM) optical fiber communication systems. The mathematical model of IQ imbalance system has been analyzed. Then, ICA algorithm is applied in the system to combat the mirror interference introduced by IQ imbalance. This algorithm can realize the joint compensation of both transmitter and receiver IQ imbalance with the optical channel that contains noise, attenuation and chromatic dispersion. The simulation shows that the performance degradation caused by IQ imbalance can be compensated by ICA algorithm effectively.

Jiang, Shan; Hu, Guijun; Li, Zhaoxi; Mu, Liping; Zhang, Jingdong

2014-01-01

223

Inspiratory work and response times of a modified pediatric volume ventilator during synchronized intermittent mandatory ventilation and pressure support ventilation.  

PubMed

Volume ventilation by demand flow ventilators significantly increases work of breathing during inspiration. Although various ventilator modifications and different modes of ventilation have been developed, there have been few studies regarding imposed work of breathing in infants and children. This study was designed to evaluate several modifications of a commercially available demand flow ventilator designed to shorten response time (tr) and decrease the imposed work (Wi) involved in opening the demand valve. Minimum withdrawal volume (Vmin), maximum negative pressure (P mneg), and tr were measured. Wi was defined as the product of Vmin and P mneg. Seven Siemens Servo 900C ventilators were tested under 16 different trial conditions with four variables: 1) mode of ventilation (synchronized intermittent mandatory ventilation [SIMV] vs. pressure support ventilation [PSV]); 2) caliber of circuit tubing (adult vs. pediatric); 3) location of airway pressure monitor (distal vs. proximal); and 4) ventilator trigger sensitivity (0 cm H2O--high vs. -2 cm H2O--low). Vmin, Pmneg, and Wi were all decreased (P less than .05) while tr was unaffected by changing ventilator trigger sensitivity from low to high. Wi was decreased by pediatric tubing and proximal airway pressure monitoring only when low trigger sensitivity was used. PSV and proximal airway monitoring shortened tr. The authors conclude that the use of pediatric circuit tubing and proximal airway pressure monitoring with a Siemens Servo 900C ventilator significantly improved ventilator performance. PMID:2589684

Martin, L D; Rafferty, J F; Wetzel, R C; Gioia, F R

1989-12-01

224

Residential ventilation standards scoping study  

SciTech Connect

The goals of this scoping study are to identify research needed to develop improved ventilation standards for California's Title 24 Building Energy Efficiency Standards. The 2008 Title 24 Standards are the primary target for the outcome of this research, but this scoping study is not limited to that timeframe. We prepared this scoping study to provide the California Energy Commission with broad and flexible options for developing a research plan to advance the standards. This document presents the findings of a scoping study commissioned by the Public Interest Energy Research (PIER) program of the California Energy Commission to determine what research is necessary to develop new residential ventilation requirements for California. This study is one of three companion efforts needed to complete the job of determining the ventilation needs of California residences, determining the bases for setting residential ventilation requirements, and determining appropriate ventilation technologies to meet these needs and requirements in an energy efficient manner. Rather than providing research results, this scoping study identifies important research questions along with the level of effort necessary to address these questions and the costs, risks, and benefits of pursuing alternative research questions. In approaching these questions and corresponding levels of effort, feasibility and timing were important considerations. The Commission has specified Summer 2005 as the latest date for completing this research in time to update the 2008 version of California's Energy Code (Title 24).

McKone, Thomas E.; Sherman, Max H.

2003-10-01

225

Cigarette smoke ventilation decreases prostaglandin inactivation in rat and hamster lungs  

SciTech Connect

The effects of cigarette smoke on the metabolism of exogenous PGE2 and PGF2 alpha were investigated in isolated rat and hamster lungs. When isolated lungs from animals were ventilated with cigarette smoke during pulmonary infusion of 100 nmol of PGE2 or PGF2 alpha, the amounts of the 15-keto-metabolites in the perfusion effluent were decreased. Pre-exposure of animals to cigarette smoke daily for 3 weeks did not change the metabolism of PGE2 when the lungs were ventilated with air. Cigarette smoke ventilation of lungs from pre-exposed animals caused, however, a similar decrease in the metabolism of PGE2 as in animals not previously exposed to smoke. After pulmonary injection of 10 nmol of /sup 14/C-PGE2 the radioactivity appeared more rapidly in the effluent during cigarette smoke ventilation suggesting inhibition of the PGE2 uptake mechanism. In rat lungs pulmonary vascular pressor responses to PGE2 and PGF2 alpha were inhibited by smoke ventilation.

Maennistoe, J.; Uotila, P.

1982-06-01

226

AICAR administration ameliorates hypertension and angiogenic imbalance in a model of preeclampsia in the rat  

PubMed Central

Previous studies suggest restoration of angiogenic balance can lower blood pressure and improve vascular endothelium function in models of preeclampsia. Our laboratory has recently reported exercise training mitigates hypertension in an animal model of preeclampsia, but the mechanisms are unknown. AMP-activated protein kinase (AMPK) is stimulated during exercise and has been shown to increase expression of VEGF. Therefore, the purpose of this study was to determine whether AICAR (5-aminoimidazole-4-carboxamide-3-ribonucleoside), a potent AMPK stimulator, would increase circulating VEGF, improve angiogenic potential, decrease oxidative stress, and abrogate placental ischemia-induced hypertension. In rats, reduced uteroplacental perfusion pressure (RUPP) was induced on day 14 of gestation by introducing silver clips on the inferior abdominal aorta and ovarian arteries. AICAR was administered intraperitoneally (50 mg/kg b.i.d.) days 14–18, and blood pressure and tissues were collected on day 19. RUPP-induced hypertension was ameliorated (P < 0.05) with AICAR versus RUPP. AICAR increased (P < 0.05) plasma VEGF and decreased (P < 0.05) plasma soluble VEGF receptor-1 in the RUPP + AICAR versus RUPP. Antioxidant capacity was restored (P < 0.05) by AICAR in RUPP placenta. Renal and placental catalase activity was decreased (P < 0.05) in RUPP + AICAR versus RUPP. Angiogenic potential was increased (P < 0.05) in RUPP + AICAR versus RUPP. Fetal and placental weights were unaffected by AICAR. Placental AMPK phosphorylation was increased (P < 0.05) in RUPP + AICAR versus normal pregnant and RUPP. These findings suggest AICAR may be useful to mitigate angiogenic imbalance, renal, and placental oxidative stress and increase in blood pressure associated with RUPP hypertension. Furthermore, placental AMPK phosphorylation was observed only in the setting of ischemia.

Banek, Christopher T.; Bauer, Ashley J.; Needham, Karen M.; Dreyer, Hans C.

2013-01-01

227

Air flow in snake ventilation.  

PubMed

Ventilation in resting, unrestrained Boa constrictor, Python regius and Thanmophis s. sirtalis was monitored using various combinations of a closed Kopfkappe (head chamber), intratracheal pressure catheters, strain gauges around the trunk, and a flow meter connected to one of the nostrils. Records of intratracheal pressure with and without closing the Kopfkappe show that the latter device induces artifacts in the normal ventilatory pattern. Flow meter readings from quiescent snakes indicate that ventilation is biphasic (outflow-inflow-pause) rather than triphasic (outflow-inflow-outflow-pause), while simultaneous pressure and strain gauge records are variably tri- or quadriphasic. PMID:644149

Clark, B D; Gans, C; Rosenberg, H I

1978-02-01

228

Fracture ventilation by surface winds  

NASA Astrophysics Data System (ADS)

Gas exchange between the Earth subsurface and the atmosphere is an important mechanism, affecting hydrological, agricultural and environmental processes. From a hydrological aspect, water vapor transport is the most important process related to Earth-atmosphere gas exchange. In respect to agriculture, gas transport in the upper soil profile is important for soil aeration. From an environmental aspect, emission of volatile radionuclides, such as 3H, 14C and Rd from radioactive waste disposal facilities; volatile organic components from industrial sources and Rn from natural sources, all found in the upper vadose zone, can greatly affect public health when emissions occur in populated areas. Thus, it is vital to better understand gas exchange processes between the Earth's upper crust and atmosphere. Four major mechanisms are known to transfer gases between ground surface and atmosphere: (1) Diffusion; (2) Pressure gradients between ground pores and atmosphere due to changes in barometric pressure; (3) Density-driven gas flow in respond to thermal gradients in the ground; and (4) Winds above the ground surface. Herein, the wind ventilation mechanism is studied. Whereas the wind's impact on ground ventilation was explored in several studies, the physical mechanisms governing this process were hardly quantified or characterized. In this work the physical properties of fracture ventilation due to wind blowing along land surface were explored and quantified. Both field measurements and Hele-Shaw experiments under controlled conditions in the laboratory were used to study this process. It was found that winds in the range of 0.3 m/s result in fracture ventilation down to a depth of 0.2 m. As wind velocity increases, the depth of the ventilation inside the fracture increases respectively, in a linear manner. In addition, the fracture aperture also affects the depth of ventilation, which grows as fracture aperture increases. For the maximal examined aperture of 2 cm and wind velocity of 1.25 m/s, fracture ventilation was deeper than 0.45 m. This study sheds new light on fracture ventilation, showing that moderate winds may increase evaporation and gas exchange between fractured media and the atmosphere. Even though wind impact is limited to the top 0.5 m below the ground surface, it is an important process as most of the biological activities, as well as important hydrological processes occur in this region. Wind effect should be considered when modeling mass and energy balances between the Earth upper crust and atmosphere.

Nachshon, U.; Dragila, M. I.; Weisbrod, N.

2011-12-01

229

Human versus Computer Controlled Selection of Ventilator Settings: An Evaluation of Adaptive Support Ventilation and Mid-Frequency Ventilation  

PubMed Central

Background. There are modes of mechanical ventilation that can select ventilator settings with computer controlled algorithms (targeting schemes). Two examples are adaptive support ventilation (ASV) and mid-frequency ventilation (MFV). We studied how different clinician-chosen ventilator settings are from these computer algorithms under different scenarios. Methods. A survey of critical care clinicians provided reference ventilator settings for a 70?kg paralyzed patient in five clinical/physiological scenarios. The survey-derived values for minute ventilation and minute alveolar ventilation were used as goals for ASV and MFV, respectively. A lung simulator programmed with each scenario's respiratory system characteristics was ventilated using the clinician, ASV, and MFV settings. Results. Tidal volumes ranged from 6.1 to 8.3?mL/kg for the clinician, 6.7 to 11.9?mL/kg for ASV, and 3.5 to 9.9?mL/kg for MFV. Inspiratory pressures were lower for ASV and MFV. Clinician-selected tidal volumes were similar to the ASV settings for all scenarios except for asthma, in which the tidal volumes were larger for ASV and MFV. MFV delivered the same alveolar minute ventilation with higher end expiratory and lower end inspiratory volumes. Conclusions. There are differences and similarities among initial ventilator settings selected by humans and computers for various clinical scenarios. The ventilation outcomes are the result of the lung physiological characteristics and their interaction with the targeting scheme.

Mireles-Cabodevila, Eduardo; Diaz-Guzman, Enrique; Arroliga, Alejandro C.; Chatburn, Robert L.

2012-01-01

230

Effect of carbon monoxide on the cytochrome P-450-mediated activation of 4-ipomeanol by the isolated perfused rabbit lung  

SciTech Connect

4-Ipomeanol is a naturally occurring toxin that induces lesions in the lung following its activation to an alkylating metabolite by the pulmonary cytochrome p-450 system. The aim of this study was to determine if an environmentally relevant concentration of carbon monoxide could inhibit the activation of 4-ipomeanol and prevent the associated toxic sequelae in the isolated perfused rabbit lung. The lungs of male New Zealand rabbits were removed and perfused with ({sup 14}C)-4-ipomeanol for 2 h starting with an initial concentration of 0.1 mM. Lungs were ventilated with either air (control) or 7.5% CO/20% O{sub 2}. 4-Ipomeanol-derived covalent binding was identical in the control and carbon monoxide treatment groups. Lungs perfused with 4-ipomeanol and ventilated with air or 7.5% CO/20% O{sub 2} both displayed alveolar type II cell hyperplasia and alveolar macrophage infiltration. Surprisingly, there was no histological evidence of Clara cell damage in any of the 4-ipomeanol-perfused lungs. These results suggest that the isozymes of pulmonary cytochrome p-450 that act in concert to metabolize 4-ipomeanol are relatively insensitive to inhibition by carbon monoxide.

Trela, B.A.; Carlson, G.P.; Turek, J.; Rebar, A. (Purdue Univ., West Lafayette, IN (USA)); Mathews, J.M. (Research Triangle Institute, Research Triangle Park, NC (USA))

1989-01-01

231

Compromised bone marrow perfusion in osteoporosis.  

PubMed

A link between bone blood flow and osteoporosis may exist. Outside of the spine, the proximal femur is the most common site of osteoporotic fracture and is also an area prone to avascular necrosis and fracture nonunion. This study of the proximal femur investigates the relationship between BMD, bone marrow fat content, bone perfusion, and muscle perfusion. One hundred twenty healthy female subjects (mean age, 74 yr; age range, 67-89 yr) underwent DXA examination of the hip, proton MR spectroscopy, and dynamic contrast-enhanced MR imaging of the right proximal femur, acetabulum, and adductor thigh muscle. In all bone areas examined (femoral head, femoral neck, femoral shaft, acetabulum), perfusion indices (maximum enhancement, enhancement slope) were significantly reduced in subjects with osteoporosis compared with subjects with osteopenia or normal BMD. Adductor muscle perfusion was not affected by change in BMD. As marrow perfusion decreased in the proximal femur, marrow fat increased (r = 0.827). This increase in fat content seemed to account for the decrease in marrow perfusion more than a reduction in BMD. For normal BMD subjects, perfusion parameters in the femoral head were one third of those in the femoral neck or shaft and one fifth of those in the acetabulum. Perfusion throughout the proximal femur is reduced in osteoporotic subjects compared with osteopenic and normal subjects. This reduction in perfusion only affects bone and not those tissues outside of bone with the same blood supply. As bone perfusion decreased, there was a corresponding increase in marrow fat. PMID:18302498

Griffith, James F; Yeung, David K W; Tsang, Polly H; Choi, Kai C; Kwok, Timothy C Y; Ahuja, Anil T; Leung, Kwok S; Leung, Ping C

2008-07-01

232

Pressure modes of invasive mechanical ventilation.  

PubMed

Pressure modes of invasive mechanical ventilation generate a tidal breath by delivering pressure over time. Pressure control ventilation (PC) is the prototypical pressure mode and is patient- or time-triggered, pressure-limited, and time-cycled. Other pressure modes include pressure support ventilation (PSV), pressure-regulated volume control (PRVC, also known as volume control plus [VC+]), airway pressure release ventilation (APRV), and biphasic ventilation (also known as BiLevel). Despite their complexity, modern ventilators respond to patient effort and respiratory system mechanics in a fairly predictable fashion. No single mode has consistently demonstrated superiority in clinical trials; however, empiric management with a pressure mode may achieve the goals of patient-ventilator synchrony, effective respiratory system support, adequate gas exchange, and limited ventilator-induced lung injury. PMID:21941160

Singer, Benjamin D; Corbridge, Thomas C

2011-10-01

233

Advanced Design of Local Ventilation Systems.  

National Technical Information Service (NTIS)

The aim of this study was to determine the applicability and limitations of more advanced fluid mechanical methods to the design and development of local ventilation systems. The most important factors affecting the performance of local ventilation system...

I. Kulmala

1997-01-01

234

33 CFR 175.201 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...Ventilation. No person may operate a boat built after July 31, 1980, that has a gasoline engine for electrical generation, mechanical power, or propulsion unless it is equipped with an operable ventilation system that meets the requirements...

2013-07-01

235

An Improved Heat Sterilizable Patient Ventilator.  

National Technical Information Service (NTIS)

A modified heat sterilizable patient ventilator is disclosed. The ventilator is characterized by a ported center body, a shell formed of heat sterilizable material mounted on the center body and defining a hermetically sealed reservoir for confining under...

A. S. Irons P. P. Muehter W. D. Kent

1974-01-01

236

Comparative Tests on Calves. Insulation - Ventilation - Heating.  

National Technical Information Service (NTIS)

Comparative tests have been carried out in 3 calf houses, of which one was insulated, mechanically ventilated and heated (KA-1), another was insulated and had an automatically regulated natural ventilation system without heating (KA-2), and the third hous...

K. Hansen

1984-01-01

237

The Imbalance of Water in Nature as System  

NASA Astrophysics Data System (ADS)

Consider some of the water-containing area. Choose some the factors which we consider important to the system. The system contains a system factors, and the external environment these factors doesn't contain. Between the system and the external environment must be some flows into the system, out of the system and along the border. If the flows into and out of the system are not equal, that means within the system exactly something is happening. But the equality of the flows into and out of the system does not mean that within the system nothing happens. It is extremely important to determine the time factor. Everything has a beginning and an end. Each factor has its own life from 0 to 1, as well as their watches. Thus that within the system and the environment at the same time are going a lot of the watches and each watch is going by their own pace. System-wide time is needed to describe the system as a whole and to be able to re-measure the individual time of each factor. It is also very important to identify each factor of the system, environment and border. Definition of each particular factor depends on the level of our knowledge. There are many examples where one factor was divided into several, and vice versa, several factors have combined in one or even disappear as a non-existent. Each factor is determined by specific people for reasons of convenience, the specific of tasks, the possible accuracy of measurement, available resources, etc. The development of the science and applications are going to the direction of the clearer separation of factors and the precision of their measurements. Now is extremely important to more clearly define the boundaries of systems, factors and the allowed accuracy of their measurements. With such a revision, many previously balanced situations become to the imbalance. There are many specific details for each case, but they do not change the basic approach described above. If not clearly resolved the questions listed above so will not be obtained any reliable results. For example, the real water arrival occurs in the modes of imbalances such as increasing or decreasing. Water departure also is some set of the several imbalance increase and decrease types. The processes with various orientations interact between each other and reinforce or depress the conjoint effect. This creates some unstable situation, which are not visible by the balanced approach. Therefore some natural disasters actually are coming as unexpected. But in really there are some consequences of the methodological blindness. The Nature is unstable. The imbalance is the main state of the Nature. But mankind does not yet have adequate tools to describing imbalance as it is. In generally now is used more or less successful extrapolation and interpolation of the balance logic. But this is not enough now. So we tried to sharpen here the importance of the works with the imbalance directly.

Kontar, V. A.; Imbalance of Water in Nature

2011-12-01

238

What is the Imbalance of Water in Nature?  

NASA Astrophysics Data System (ADS)

Look at any lake. Water comes into the lake from the atmosphere, from surface and groundwater sources. Water leaves the lake to the atmosphere, surface and underground drains, as well as for consumption by human society, wild plants and animals if they are within the boundaries of the lake's system. If quantity of water coming into the lake is equally of the quantity of water which flow from the lake, so the lake level has not changed and we have a state of equilibration or balance. The bookkeeper's book also has name "balance". But this is just a play on words. If the water is coming into the lake more than the water is coming away from lake, therefore the lake level will increase and we have a state of the imbalance of the increase type. If the water is coming into the lake less than the water is coming away from lake, therefore the lake level will decrease and we have a state of the imbalance of the decrease type. Everyone knows that the lake level rises or falls, for example during the year. Sometimes it is happened some balance. But the state of balance is rare and in of the short duration. The lake is of most the time in the conditions of the imbalance increases or the imbalance decreases type. The balance as a state of equilibrium, in the language of mathematics, is the point of the extremum between the periods of rise and fall. The balance is a special condition, which is existing very rare and a very short period of time. The people sometimes to do the great efforts for maintain the constant level of the lakes. But these facts don't change the situation. On the contrary, the human's struggle for maintain the lake in constant level just shows how difficult and expensive to go against the natural laws of Nature. When water was plentiful, these facts could be ignored. But now when the global water shortage is quickly growing, many previously ignored details are becoming crucial. There are very important to do the correct definitions of the borders and parameters of the system. The precise of the measurement of the parameters system have the decisive role. The systemic approach to addressing the imbalance, we will describe in another separate paper. Now in our case, the lake and its effective environment is one system. It is possible so roughly determine the system of lakes that will be always to do the report exact which wants the boss. It is happened quite often. For example, it was the time when the human's leaders have used the hypothesis that the Earth is flat and the Sky is hard. This dominant interpretation of the Nature was used by force a lot of centuries. Who were disagreed with these statements those were burned at the stake, etc. This situation was change only when the domestic recourses were exhausted. The new recourses were possible to get as expansion to other countries, continents, space etc. The flat Earth and the hard Sky not help more. Now the balance idea is in some similar situation. The balance is a convenient, relaxing hypothesis or model. This model gave a lot of opportunities for the development of science and practice in the past. But the humanity is in other conditions now. Rest we have only on the dream. The era of the balance is going to end. The era of the imbalance is coming now for future. The humanity must to learn to live in an era of great change or disappear.

Kontar, V. A.

2011-12-01

239

Intestinal perfusion monitoring using photoplethysmography  

NASA Astrophysics Data System (ADS)

In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed.

Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; Coté, Gerard L.

2013-08-01

240

Cocoa flavanols and brain perfusion.  

PubMed

Foods and beverages rich in flavonoids are being heralded as potential preventive agents for a range of pathologic conditions, ranging from hypertension to coronary heart disease to stroke and dementia. We and others have demonstrated that short-term ingestion of cocoa, particularly rich in the subclass of flavonoids known as flavanols, induced a consistent and striking peripheral vasodilation in healthy people, improving endothelial function in a nitric oxide-dependent manner. The vasodilator response was reversed by N-nitro-L-arginine methyl ester, an arginine analog that blocks nitric oxide synthesis. Flavanol-poor cocoa induced much smaller responses. Because impairment of endothelial function is a nearly universal accompaniment of the aging process, we examined the peripheral vasodilator response to flavanol-rich cocoa in healthy older subjects. Observations point to a favorable response among the older. Together with peripheral vascular disease, cerebrovascular disease is responsible for significant mortality with advancing age. An association of decreased cerebral perfusion with dementia has been recently highlighted. The prospect of increasing cerebral perfusion with cocoa flavanols is extremely promising. Our still preliminary data hold out the promise that the cerebral blood supply in the elderly participates in the vasodilator response. With the modalities of transcranial Doppler and MRI, we have the capabilities of analyzing the potential benefits of flavanols on brain perfusion and, subsequently, on cognition. PMID:16794460

Fisher, Naomi D L; Sorond, Farzaneh A; Hollenberg, Norman K

2006-01-01

241

Hyperventilation, cerebral perfusion, and syncope.  

PubMed

This review summarizes evidence in humans for an association between hyperventilation (HV)-induced hypocapnia and a reduction in cerebral perfusion leading to syncope defined as transient loss of consciousness (TLOC). The cerebral vasculature is sensitive to changes in both the arterial carbon dioxide (PaCO2) and oxygen (PaO2) partial pressures so that hypercapnia/hypoxia increases and hypocapnia/hyperoxia reduces global cerebral blood flow. Cerebral hypoperfusion and TLOC have been associated with hypocapnia related to HV. Notwithstanding pronounced cerebrovascular effects of PaCO2 the contribution of a low PaCO2 to the early postural reduction in middle cerebral artery blood velocity is transient. HV together with postural stress does not reduce cerebral perfusion to such an extent that TLOC develops. However when HV is combined with cardiovascular stressors like cold immersion or reduced cardiac output brain perfusion becomes jeopardized. Whether, in patients with cardiovascular disease and/or defect, cerebral blood flow cerebral control HV-induced hypocapnia elicits cerebral hypoperfusion, leading to TLOC, remains to be established. PMID:24265279

Immink, R V; Pott, F C; Secher, N H; van Lieshout, J J

2014-04-01

242

Intestinal perfusion monitoring using photoplethysmography.  

PubMed

In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed. PMID:23942635

Akl, Tony J; Wilson, Mark A; Ericson, M Nance; Coté, Gerard L

2013-08-01

243

Right axillary and femoral artery perfusion with mild hypothermia for aortic arch replacement  

PubMed Central

Objectives Aortic arch replacement is associated with increased mortality and morbidity especially in acute type-A aortic dissection. Although hypothermic circulatory arrest with selective antegrade cerebral perfusion has been widely used because of its excellent cerebral protection, its optimal perfusion characteristics are unknown. The present study investigates clinical results obtained after perfusion method modification and temperature management during cardiopulmonary bypass (CPB). Methods Between July 2010 and August 2012, 16 consecutive adult patients (mean age 50.0 yr?±?14.1 yr, range 25 yr to 73 yr, 12 males, 4 females) who presented with acute Stanford type-A aortic dissection underwent aortic arch replacement (total arch, n?=?11; hemiarch, n?=?5) under mild hypothermia (31.1°C?±?1.5°C) with right axillary and femoral artery perfusion. Results The mean CPB time was 201 min?±?53 min, and the mean myocardial ischemic time was 140 min?±?42 min. The mean selective cerebral perfusion time was 80 min?±?16 min, and the mean lower-body circulatory arrest time was 20 min?±?13 min. No patient death occurred within 30 post-operative days. The following details were observed: new post-operative permanent neurologic deficit in 1 patient (6.3%), temporary neurologic deficit in 2 patients (12.5%), acute renal dysfunction (creatinine level?>?230 umol/L) in 3 patients (18.8%) and mechanical ventilation?>?72 h in 5 patients (31.2%). Conclusions Aortic arch replacement for acute type-A aortic dissection under mild hypothermia with right axillary and femoral artery perfusion could be safely performed in the patient cohort.

2014-01-01

244

Quantitative pixelwise myocardial perfusion maps from first-pass perfusion MRI.  

PubMed

Objective: To calculate and evaluate absolute quantitative myocardial perfusion maps from rest first-pass perfusion MRI. Methods: 10 patients after revascularization of myocardial infarction underwent cardiac rest first-pass perfusion MRI. Additionally, perfusion examinations were performed in 12 healthy volunteers. Quantitative myocardial perfusion maps were calculated by using a deconvolution technique, and results were compared were the findings of a sector-based quantification. Results: Maps were typically calculated within 3?min per slice. For the volunteers, myocardial blood flow values of the maps were 0.51?±?0.16?ml?g(-1) per minute, whereas sector-based evaluation delivered 0.52?±?0.15?ml?g(-1) per minute. A t-test revealed no statistical difference between the two sets of values. For the patients, all perfusion defects visually detected in the dynamic perfusion series could be correctly reproduced in the maps. Conclusion: Calculation of quantitative perfusion maps from myocardial perfusion MRI examinations is feasible. The absolute quantitative maps provide additional information on the transmurality of perfusion defects compared with the visual evaluation of the perfusion series and offer a convenient way to present perfusion MRI findings. Advances in knowledge: Voxelwise analysis of myocardial perfusion helps clinicians to assess the degree of tissue damage, and the resulting maps are a good tool to present findings to patients. PMID:24827377

Weng, A M; Ritter, C O; Beer, M; Hahn, D; Köstler, H

2014-07-01

245

Comparison of muscle strength imbalance in powerlifters and jumpers.  

PubMed

The purpose of the study was to examine the bilateral and unilateral force production difference in powerlifters (bilateral) and field jumpers (unilateral) to determine the existence of leg dominance. Nineteen powerlifters (PL; n = 11) and field jumpers (J; n = 8) were included in the study. Five different no arm swing countermovement jumps were randomized for testing: (a) double-leg jump; (b) dominant leg-specified double-leg jump; (c) nondominant leg-specified double-leg jump; (d) dominant leg-specified single-leg jump; and (e) nondominant leg-specified single-leg jump. The force, velocity, and power were measured via a forceplate. The Limb Symmetry Index (LSI% = (1 - ND limb/D limb) × 100%) was calculated for force imbalance between the dominant (N) and nondominant (ND) limb between PL and J. Based on the analysis, PL (mean = 2.75 ± 2.45%) had a lower LSI (p < 0.05) than J (mean = 6.81 ± 5.16%). The single-leg jumps show a (p < 0.05) significantly higher force and power and a significantly lower velocity than double-leg jump for both D and ND leg than double-leg jump. Finally, the ratio between bilateral and unilateral exercise for PL and J is 2.36:1.36 and 2.38:1, respectively. In summary, sport-specific demands between PL and J may contribute to the occurrence of the imbalance force production between limbs. This phenomenon is important for the strength coach to acknowledge, to perform an appropriate strength balance test during the off-season, and to implement a training program to reduce the force disparity between limbs. Neglecting the development of force imbalance between limbs may predispose healthy players to injury. PMID:23591945

Luk, Hui-Ying; Winter, Christa; O'Neill, Elizabeth; Thompson, Brian A

2014-01-01

246

A tuning fork gyroscope with compensated imbalance signal  

NASA Astrophysics Data System (ADS)

This paper is presenting a robust gyroscope sensor with an electrical and mechanical self-test option and the ability to suppress the quadrature error. The presented sensor is based on a tuning-fork working principle. The mechanical part is assembled in bulk-technology produced with a wet etching process. The two detection elements are manufactured with a standard CMOS-process and the material of the two thin-film actuators is AlN (aluminium-nitrid). The two actuators can be controlled independently from each other. Two electronic PCB's were developed for actuating and measurement. One is including the analogue signal path; the second PCB is the digital electronics consisting of a FPGA and other peripherals. The tuning fork is actuated in a primary oscillation mode also called drive mode. For keeping the oscillation in resonance, a digital PLL is used in a forced feedback loop. To have a constant energy in the drive mode an Amplitude-Gain-Control (AGC) is implemented. An appearing angular rate causes the corriolis-force which is actuating secondary oscillation, also called detection mode. The amplitude of this oscillation is proportional to the angular rate. The signal has a component resulting from the mechanical imbalance. To separate these two signal parts from each other a synchronous demodulator followed by a digital filter chain has been developed. To achieve the maximum suppression of the imbalance signal a control-loop is used to shift the phases of the two actuation signals. This creates an additional force that compensates the movement as a result of the mechanical imbalance. With the implementation of this control loop the performance of the sensor was increased. An enhanced temperature stability over operation was achieved with the means of this compensation.

Arnold, E.; Nuscheler, F.

2007-06-01

247

Quantification of soft-tissue imbalance in condylar knee arthroplasty.  

PubMed

Soft-tissue balance has been debated in recent publications in connection with the long-term survival of the 'condylar-type' knee prostheses. Present methods of assessment have all assumed that the soft tissues around the knee are inelastic strings. The authors have developed two instruments to quantify soft-tissue imbalance, at the time of the operation, with the assumption that the soft tissues are viscoelastic structures. These two soft-tissue balancing devices were consequently used on 121 patients undergoing condylar knee arthroplasties at the Derbyshire Royal Infirmary and Bretby Hall Orthopaedic Hospital. The first instrument consisted of two flat plates separated by four standard compression springs and provided a qualitative measure of imbalance assuming that the soft tissues were viscoelastic. It was used on 55 patients before being replaced by the quantitative measure of the second instrument. The authors have redefined soft-tissue imbalance, to take into account the viscoelastic nature of the soft tissues, as the resultant trapezoidal geometry of the knee after the bony cuts have been made and when the knee is tensed by equal forces both medially and laterally. The second balancer eliminates the requirement to quantify the individual tensions in the medial and lateral structures by introducing to the system a low-friction, central pivot in the coronal plane. Once the pivot is situated at the centre of the knee, an equilibrium position is achieved where the clockwise and counter-clockwise moments are equal. The tensions exerted by soft tissues can be assumed to be equal and opposite as their moment arms are the same.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8361160

Sambatakakis, A; Attfield, S F; Newton, G

1993-07-01

248

Numerical model of crossed Andreev reflection and charge imbalance  

NASA Astrophysics Data System (ADS)

We present a numerical model of local and nonlocal transport properties in a lateral spin valve structure consisting of two magnetic electrodes in contact with a third perpendicular superconducting electrode. By considering the transport paths for a single electron incident at the local F/S interface—in terms of probabilities of crossed or local Andreev reflection, elastic cotunneling, or quasiparticle transport—we show that this leads to nonlocal charge imbalance. We compare this model with experimental data from an aluminum-permalloy (Al/Py) lateral spin valve geometry device and demonstrate the effectiveness of this simple approach in replicating experimental behavior.

Webb, J. L.; Hickey, B. J.; Burnell, G.

2012-08-01

249

Animal models of ex vivo lung perfusion as a platform for transplantation research.  

PubMed

Ex vivo lung perfusion (EVLP) is a powerful experimental model for isolated lung research. EVLP allows for the lungs to be manipulated and characterized in an external environment so that the effect of specific ventilation/perfusion variables can be studied independent of other confounding physiologic contributions. At the same time, EVLP allows for normal organ level function and real-time monitoring of pulmonary physiology and mechanics. As a result, this technique provides unique advantages over in vivo and in vitro models. Small and large animal models of EVLP have been developed and each of these models has their strengths and weaknesses. In this manuscript, we provide insight into the relative strengths of each model and describe how the development of advanced EVLP protocols is leading to a novel experimental platform that can be used to answer critical questions in pulmonary physiology and transplant medicine. PMID:24977117

Nelson, Kevin; Bobba, Christopher; Ghadiali, Samir; Jr, Don Hayes; Black, Sylvester M; Whitson, Bryan A

2014-05-20

250

Animal models of ex vivo lung perfusion as a platform for transplantation research  

PubMed Central

Ex vivo lung perfusion (EVLP) is a powerful experimental model for isolated lung research. EVLP allows for the lungs to be manipulated and characterized in an external environment so that the effect of specific ventilation/perfusion variables can be studied independent of other confounding physiologic contributions. At the same time, EVLP allows for normal organ level function and real-time monitoring of pulmonary physiology and mechanics. As a result, this technique provides unique advantages over in vivo and in vitro models. Small and large animal models of EVLP have been developed and each of these models has their strengths and weaknesses. In this manuscript, we provide insight into the relative strengths of each model and describe how the development of advanced EVLP protocols is leading to a novel experimental platform that can be used to answer critical questions in pulmonary physiology and transplant medicine.

Nelson, Kevin; Bobba, Christopher; Ghadiali, Samir; Jr, Don Hayes; Black, Sylvester M; Whitson, Bryan A

2014-01-01

251

[Mechanical ventilation in acute respiratory distress syndrome].  

PubMed

The goal of mechanically ventilating patients with acute respiratory distress syndrome (ARDS) is to ensure adequate oxygenation and minimal ventilator-associated lung injury. Non-invasive ventilation should be cautiously used in patients with ARDS. Protective ARDS mechanical ventilation strategies with low tidal volumes can reduce mortality. Driving pressure is the most reasonable parameter to optimize tidal volume. Available evidence does not support the routine use of higher positive end expiratory pressure (PEEP) in patients with ARDS. The optimal level of PEEP may be titrated by the inflection point obtained from static pressure-volume curve. Promising therapies include prone position ventilation, high frequency oscillatory ventilation and extracorporeal membrane oxygenation as salvage treatment. While mechanically ventilating, it is also important for ARDS patients to maintain spontaneous breathing via assisted ventilation mode such as bilevel positive airway pressure, pressure support ventilation and neurally adjusted ventilation assist. Exogenous surfactant, inhaled nitric oxide, bronchodilators, airway pressure release ventilation and partial liquid ventilation are not recommended therapies. PMID:23791070

Wang, Ya-Mei; Tao, Yu-Hong

2013-06-01

252

The fluid mechanics of natural ventilation  

Microsoft Academic Search

Natural ventilation of buildings is the flow generated by temperature differences and by the wind. Modern buildings have extreme designs with large, tall open plan spaces and large cooling requirements. Natural ventilation offers a means of cooling these buildings and providing good indoor air quality. The essential feature of ventilation is an exchange between an interior space and the external

Paul Linden

1999-01-01

253

Summary of human responses to ventilation  

Microsoft Academic Search

The effects of ventilation on indoor air quality and health is a complex issue. It is known that ventilation is necessary to remove indoor generated pollutants from indoor air or dilute their concentration to acceptable levels. But, as the limit values of all pollutants are not known, the exact determination of required ventilation rates based on pollutant concentrations and associated

Olli A. Seppanen; William J. Fisk

2004-01-01

254

Effect of oxygen-derived free radicals on arachidonic acid turnover in isolated perfused rat lung  

SciTech Connect

Turnover of arachidonic acid in lung was studied by perfusing an isolated and ventilated rat lung in the presence of (/sup 14/C)-arachidonic acid for 30 min. Oxygen-derived free radicals were generated within the pulmonary circulation by the action of xanthine oxidase (XO) (0.1 ..mu../ml) on hypoxanthine (0.1 ..mu..mol/ml). Lung was also preperfused in the presence or absence of superoxide dismutase (SOD) (5 ..mu..g/ml) and catalase (5 ..mu..g/ml) prior to the addition of radiolabeled arachidonic acid and free radical generating system. After the perfusion was over, several biopsies were obtained and phospholipids were extracted and separated from one of the biopsies. Individual phospholipids were compared with known standards and counted for radioactivity. An appreciable amount of radioactivity was found in total phospholipids and in phosphatidyl choline and phosphatidyl inositol fractions in control lungs. Some radioactivity was also noticed in phosphatidyl ethanolamine fraction. The isotopic incorporation was significantly inhibited when lung was perfused in the presence of hypoxanthine and XO. The incorporation of (/sup 14/C)-radioactivity was restored to the control levels when lung was preperfused with SOD and catalase. These results suggest that oxygen radicals inhibit the arachidonic acid turnover in isolated and perfused rat lung.

Jones, R.; Otani, H.; Das, D.K.

1986-05-01

255

Vasomotor tone does not affect perfusion heterogeneity and gas exchange in normal primate lungs during normoxia  

NASA Technical Reports Server (NTRS)

To determine whether vasoregulation is an important cause of pulmonary perfusion heterogeneity, we measured regional blood flow and gas exchange before and after giving prostacyclin (PGI(2)) to baboons. Four animals were anesthetized with ketamine and mechanically ventilated. Fluorescent microspheres were used to mark regional perfusion before and after PGI(2) infusion. The lungs were subsequently excised, dried inflated, and diced into approximately 2-cm(3) pieces (n = 1,208-1,629 per animal) with the spatial coordinates recorded for each piece. Blood flow to each piece was determined for each condition from the fluorescent signals. Blood flow heterogeneity did not change with PGI(2) infusion. Two other measures of spatial blood flow distribution, the fractal dimension and the spatial correlation, did not change with PGI(2) infusion. Alveolar-arterial O(2) differences did not change with PGI(2) infusion. We conclude that, in normal primate lungs during normoxia, vasomotor tone is not a significant cause of perfusion heterogeneity. Despite the heterogeneous distribution of blood flow, active regulation of regional perfusion is not required for efficient gas exchange.

Glenny, R. W.; Robertson, H. T.; Hlastala, M. P.

2000-01-01

256

AIR FLOW IN SNAKE VENTILATION  

Microsoft Academic Search

Ahstraet. Ventilation in resting, unrestrained Boa constrictor, Python regius and Thamnophi~ s. sirtalis was monitored using various combinations of a closed Kopfkappe (head chamber), intratracheal pressure catheters, strain gauges around the trunk, and a flow meter connected to one of the nostrils. Records of intratracheal pressure with and without closing the Koplkappe show that the latter device induces artifacts in

BRIAN D. CLARK; CARL GANS; H. I. ROSENBERG

1978-01-01

257

Novel modes of mechanical ventilation.  

PubMed

The overarching goal of positive pressure mechanical ventilation is to provide adequate gas exchange support while not causing harm. Indeed, positive pressure mechanical ventilators are only support technologies, not therapeutic technologies. As such they cannot be expected to "cure" disease; they can only "buy time" for other therapies (including the patient's own defenses) to work.Conventional approaches to positive pressure ventilation involve applying ventilatory patterns mimicking normal ones through either masks or artificial airways. This is usually done with modes of support incorporating assist/control breath-triggering mechanisms, gas delivery patterns governed by either a set flow or pressure, and breath cycling based on either a set volume, a set inspiratory time, or a set flow. Often this support includes positive end-expiratory pressure and supplemental oxygen. In recent decades several novel or unconventional approaches to providing mechanical ventilatory support have been introduced. For these to be considered of value, however, it would seem reasonable that they address important clinical challenges and be shown to improve important clinical outcomes (e.g., mortality, duration of ventilation, sedation needs, complications). This article focuses on challenges facing clinicians in providing mechanical ventilatory support and assesses several novel approaches introduced over the last 2 decades in the context of these challenges. PMID:23934718

Al-Hegelan, Mashael; MacIntyre, Neil R

2013-08-01

258

Review of Residential Ventilation Technologies  

SciTech Connect

This paper reviews current and potential ventilation technologies for residential buildings in North America and a few in Europe. The major technologies reviewed include a variety of mechanical systems, natural ventilation, and passive ventilation. Key parameters that are related to each system include operating costs, installation costs, ventilation rates, heat recovery potential. It also examines related issues such as infiltration, duct systems, filtration options, noise, and construction issues. This report describes a wide variety of systems currently on the market that can be used to meet ASHRAE standard 62.2. While these systems generally fall into the categories of supply, exhaust or balanced, the specifics of each system are driven by concerns that extend beyond those in the standard and are discussed. Some of these systems go beyond the current standard by providing additional features (such as air distribution or pressurization control). The market will decide the immediate value of such features, but ASHRAE may wish to consider modifications to the standard in the future.

Russell, Marion L.; Sherman, Max H.; Rudd, Armin

2005-03-01

259

To ventilate, oscillate, or cannulate?  

PubMed

Ventilatory management of acute respiratory distress syndrome has evolved significantly in the last few decades. The aims have shifted from optimal gas transfer without concern for iatrogenic risks to adequate gas transfer while minimizing lung injury. This change in focus, along with improved ventilator and multiorgan system management, has resulted in a significant improvement in patient outcomes. Despite this, a number of patients develop hypoxemic respiratory failure refractory to lung-protective ventilation (LPV). The intensivist then faces the dilemma of either persisting with LPV using adjuncts (neuromuscular blocking agents, prone positioning, recruitment maneuvers, inhaled nitric oxide, inhaled prostacyclin, steroids, and surfactant) or making a transition to rescue therapies such as high-frequency oscillatory ventilation (HFOV) and/or extracorporeal membrane oxygenation (ECMO) when both these modalities are at their disposal. The lack of quality evidence and potential harm reported in recent studies question the use of HFOV as a routine rescue option. Based on current literature, the role for venovenous (VV) ECMO is probably sequential as a salvage therapy to ensure ultraprotective ventilation in selected young patients with potentially reversible respiratory failure who fail LPV despite neuromuscular paralysis and prone ventilation. Given the risk profile and the economic impact, future research should identify the patients who benefit most from VV ECMO. These choices may be further influenced by the emerging novel extracorporeal carbon dioxide removal devices that can compliment LPV. Given the heterogeneity of acute respiratory distress syndrome, each of these modalities may play a role in an individual patient. Future studies comparing LPV, HFOV, and VV ECMO should not only focus on defining the patients who benefit most from each of these therapies but also consider long-term functional outcomes. PMID:23827735

Shekar, Kiran; Davies, Andrew R; Mullany, Daniel V; Tiruvoipati, Ravindranath; Fraser, John F

2013-10-01

260

Sustained Hypoxic Pulmonary Vasoconstriction in the Isolated Perfused Rat Lung: Effect of ?1-adrenergic Receptor Agonist.  

PubMed

Background: Alveolar hypoxia induces monophasic pulmonary vasoconstriction in vivo, biphasic vasoconstriction in the isolated pulmonary artery, and controversial responses in the isolated perfused lung. Pulmonary vascular responses to sustained alveolar hypoxia have not been addressed in the isolated perfused rat lung. In this study, we investigated the effect of sustained hypoxic ventilation on pulmonary artery pressure in the present of phenylephrine, an ?1-receptor agonist, under the above condition. Methods: We performed this study in the isolated perfused rat lung. After preparation, the lungs were divided randomly into five groups of normoxic-normocapnia, hypoxic-normocapnia, phenylephrine pre- or post-treated hypoxic-normocapnia and phenylephrine pre-treated normoxic-normocapnia. Pulmonary hemodynamic, airway pressure and lung weight were measured during 60 min of the experiment for each group. Results: In the phenylephrine-pre-treated hypoxic-normocapnia group we observed a gradual increase in pulmonary artery pressure which approximated the results seen in the phenylephrine-pre-treated normoxic-normocapnia group. In contrast, in the phenylephrine-post-treated hypoxic-normcapnic group, pulmonary artery pressure did not change during the first 3 min of hypoxic-normocapnia. However at 1.5 min after administration of phenylephrine, this pressure began to increase sharply and continued until the end of the experiment. This response was biphasic (0-10 min: acute phase, 10-60 min: sustained phase) with significantly higher pulmonary artery pressure compared to the other groups. Conclusion: This study, for the first time, showed biphasic hypoxic pulmonary vasoconstriction in the isolated perfused rat lung with the sole administration of phenylephrine after but not before hypoxic gas ventilation. This finding suggested a facilitative role of alveolar hypoxia on pulmonary vasoconstriction induced by an ?1-receptor agonist. PMID:24850985

Ketabchi, Farzaneh; Karimi, Zinab; S Moosavi, Seyed Mostafa

2014-05-01

261

Sustained Hypoxic Pulmonary Vasoconstriction in the Isolated Perfused Rat Lung: Effect of ?1-adrenergic Receptor Agonist  

PubMed Central

Background: Alveolar hypoxia induces monophasic pulmonary vasoconstriction in vivo, biphasic vasoconstriction in the isolated pulmonary artery, and controversial responses in the isolated perfused lung. Pulmonary vascular responses to sustained alveolar hypoxia have not been addressed in the isolated perfused rat lung. In this study, we investigated the effect of sustained hypoxic ventilation on pulmonary artery pressure in the present of phenylephrine, an ?1-receptor agonist, under the above condition. Methods: We performed this study in the isolated perfused rat lung. After preparation, the lungs were divided randomly into five groups of normoxic-normocapnia, hypoxic-normocapnia, phenylephrine pre- or post-treated hypoxic-normocapnia and phenylephrine pre-treated normoxic-normocapnia. Pulmonary hemodynamic, airway pressure and lung weight were measured during 60 min of the experiment for each group. Results: In the phenylephrine-pre-treated hypoxic-normocapnia group we observed a gradual increase in pulmonary artery pressure which approximated the results seen in the phenylephrine-pre-treated normoxic-normocapnia group. In contrast, in the phenylephrine-post-treated hypoxic-normcapnic group, pulmonary artery pressure did not change during the first 3 min of hypoxic-normocapnia. However at 1.5 min after administration of phenylephrine, this pressure began to increase sharply and continued until the end of the experiment. This response was biphasic (0-10 min: acute phase, 10-60 min: sustained phase) with significantly higher pulmonary artery pressure compared to the other groups. Conclusion: This study, for the first time, showed biphasic hypoxic pulmonary vasoconstriction in the isolated perfused rat lung with the sole administration of phenylephrine after but not before hypoxic gas ventilation. This finding suggested a facilitative role of alveolar hypoxia on pulmonary vasoconstriction induced by an ?1-receptor agonist.

Ketabchi, Farzaneh; Karimi, Zinab; S. Moosavi, Seyed Mostafa

2014-01-01

262

The basis and basics of mechanical ventilation.  

PubMed

The development of mechanical ventilators and the procedures for their application began with the simple foot pump developed by Fell O'Dwyer in 1888. Ventilators have progressed through three generations, beginning with intermittent positive pressure breathing units such as the Bird and Bennett device in the 1960s. These were followed by second-generation units--represented by the Bennett MA-2 ventilator--in the 1970s, and the third-generation microprocessor-controlled units of today. During this evolutionary process clinicians recognized Types I and II respiratory failure as being indicators for mechanical ventilatory support. More recently investigators have expanded, clarified, and clinically applied the physiology of the work of breathing (described by Julius Comroe and other pioneers) to muscle fatigue, requiring ventilatory support. A ventilator classification system can help the clinician understand how ventilators function and under what conditions they may fail to operate as desired. Pressure-support ventilation is an example of how industry has responded to a clinical need--that is, to unload the work of breathing. All positive pressure ventilators generate tidal volumes by using power sources such as medical gas cylinders, air compressors, electrically driven turbines, or piston driven motors. Positive end-expiratory pressures, synchronized intermittent mandatory ventilation, pressure support ventilation, pressure release ventilation, and mandatory minute ventilation, are examples of the special functions available on modern ventilators. Modern third-generation ventilators use microprocessors to control operational functions and monitors. Because these units have incorporated the experience learned from earlier ventilators, it is imperative that clinicians understand basic ventilator operation and application in order to most effectively prescribe and assess their use. PMID:2036934

Bone, R C; Eubanks, D H

1991-06-01

263

Perfusion Patterns of Ischemic Stroke on Computed Tomography Perfusion  

PubMed Central

CT perfusion (CTP) has been applied increasingly in research of ischemic stroke. However, in clinical practice, it is still a relatively new technology. For neurologists and radiologists, the challenge is to interpret CTP results properly in the context of the clinical presentation. In this article, we will illustrate common CTP patterns in acute ischemic stroke using a case-based approach. The aim is to get clinicians more familiar with the information provided by CTP with a view towards inspiring them to incorporate CTP in their routine imaging workup of acute stroke patients.

Lin, Longting; Bivard, Andrew

2013-01-01

264

Earth's Radiation Imbalance from a Constellation of 66 Iridium Satellites  

NASA Astrophysics Data System (ADS)

The Earth Radiation Imbalance (ERI) at the top of the atmosphere is the primary driving force for climate change. If ERI is not zero, then Earth's temperature, both oceanic and atmospheric, will change gradually over time, tending toward a new steady state. The best estimates of current ERI from climate models range from 0.4 to 0.9 W/m2 (the imbalance being caused mainly by increasing CO2), but current satellite systems do not have the accuracy to measure ERI to even one significant digit. In this paper, we will describe a proposed constellation of 66 Earth radiation budget instruments, to be hosted on Iridium satellites. This system represents a quantum leap over current systems in several ways, in particular in providing ERI to at least one significant digit, thus enabling a crucial test of climate models. Because of its 24/7 coverage, the system will also provide ERI at three-hourly time scales without requiring extrapolations from narrowband geostationary instruments. This would allow studies of ERI's response to fast-evolving phenomena like dust storms and hurricanes. This offers a new, synoptic view of Earth radiation budget that will transform it from a monthly average into a dynamical variable alongside standard meteorological variables like temperature and pressure.

Chiu, J. C.; Wiscombe, W. J.

2012-04-01

265

Quantification of the effect of energy imbalance on bodyweight  

PubMed Central

Obesity interventions can result in weight loss, but accurate prediction of the bodyweight time course requires properly accounting for dynamic energy imbalances. In this report, we describe a mathematical modelling approach to adult human metabolism that simulates energy expenditure adaptations during weight loss. We also present a web-based simulator for prediction of weight change dynamics. We show that the bodyweight response to a change of energy intake is slow, with half times of about 1 year. Furthermore, adults with greater adiposity have a larger expected weight loss for the same change of energy intake, and to reach their steady-state weight will take longer than it would for those with less initial body fat. Using a population-averaged model, we calculated the energy-balance dynamics corresponding to the development of the US adult obesity epidemic. A small persistent average daily energy imbalance gap between intake and expenditure of about 30 kJ per day underlies the observed average weight gain. However, energy intake must have risen to keep pace with increased expenditure associated with increased weight. The average increase of energy intake needed to sustain the increased weight (the maintenance energy gap) has amounted to about 0·9 MJ per day and quantifies the public health challenge to reverse the obesity epidemic.

Hall, Kevin D; Sacks, Gary; Chandramohan, Dhruva; Chow, Carson C; Wang, Y Claire; Gortmaker, Steven L; Swinburn, Boyd A

2013-01-01

266

Quantification of the effect of energy imbalance on bodyweight.  

PubMed

Obesity interventions can result in weight loss, but accurate prediction of the bodyweight time course requires properly accounting for dynamic energy imbalances. In this report, we describe a mathematical modelling approach to adult human metabolism that simulates energy expenditure adaptations during weight loss. We also present a web-based simulator for prediction of weight change dynamics. We show that the bodyweight response to a change of energy intake is slow, with half times of about 1 year. Furthermore, adults with greater adiposity have a larger expected weight loss for the same change of energy intake, and to reach their steady-state weight will take longer than it would for those with less initial body fat. Using a population-averaged model, we calculated the energy-balance dynamics corresponding to the development of the US adult obesity epidemic. A small persistent average daily energy imbalance gap between intake and expenditure of about 30 kJ per day underlies the observed average weight gain. However, energy intake must have risen to keep pace with increased expenditure associated with increased weight. The average increase of energy intake needed to sustain the increased weight (the maintenance energy gap) has amounted to about 0·9 MJ per day and quantifies the public health challenge to reverse the obesity epidemic. PMID:21872751

Hall, Kevin D; Sacks, Gary; Chandramohan, Dhruva; Chow, Carson C; Wang, Y Claire; Gortmaker, Steven L; Swinburn, Boyd A

2011-08-27

267

Shoulder pain in wheelchair athletes. The role of muscle imbalance.  

PubMed

Shoulder rotator cuff impingement syndrome is a common and disabling problem for the wheelchair athlete. In this study we investigated the role of shoulder strength imbalance as a factor for the development of this syndrome. Nineteen paraplegic male athletes underwent clinical and isokinetic examination of both shoulders with peak torque values measured in abduction, adduction, and internal and external rotation. Twenty athletic, able-bodied men without shoulder problems were tested as controls. Ten (26%) of the paraplegic athletes had rotator cuff impingement syndrome. The results of the isokinetic testing demonstrated that 1) the paraplegics' shoulders were stronger than the controls in all directions (P < 0.05); 2) the strength ratio of abduction: adduction was higher for paraplegic athletes (P < 0.05); 3) paraplegics' shoulders with rotator cuff impingement syndrome were weaker in adduction and external and internal rotation than the paraplegic athletes without impingement syndrome (P < 0.05); and 4) paraplegics' shoulders with rotator cuff impingement syndrome had higher abduction:adduction and abduction:internal rotation strength ratios than the shoulders of paraplegics without impingement syndrome (P < 0.05). We concluded that shoulder muscle imbalance, with comparative weakness of the humeral head depressors (rotators and adductors), may be a factor in the development and perpetuation of rotator cuff impingement syndrome in wheelchair athletes. PMID:8465919

Burnham, R S; May, L; Nelson, E; Steadward, R; Reid, D C

1993-01-01

268

Compensation schemes and performance analysis of IQ imbalances in OFDM receivers  

Microsoft Academic Search

The implementation of orthogonal frequency division multiplexing (OFDM)-based physical layers suffers from the effect of In-phase and Quadrature-phase (IQ) imbalances in the front-end analog processing. The IQ imbalances can severely limit the achievable operating signal-to-noise ratio (SNR) at the receiver and, consequently, the supported constellation sizes and data rates. In this paper, the effect of IQ imbalances on OFDM receivers

Alireza Tarighat; Rahim Bagheri; Ali H. Sayed

2005-01-01

269

Impact of NMOS\\/PMOS imbalance in Ultra-Low Voltage CMOS standard cells  

Microsoft Academic Search

In this paper, the impact of the NMOS\\/PMOS imbalance on Ultra-Low Voltage (ULV) circuits and their design is discussed within a unitary framework for the first time. Variations are shown to dramatically affect imbalance due to the long-tailed probability density and high variability. The impact of the imbalance on the minimum supply voltage VDD,min ensuring correct gate switching is studied

Massimo Alioto

2011-01-01

270

The mechanical ventilator: past, present, and future.  

PubMed

The use of ventilatory assistance can be traced back to biblical times. However, mechanical ventilators, in the form of negative-pressure ventilation, first appeared in the early 1800s. Positive-pressure devices started to become available around 1900 and today's typical intensive care unit (ICU) ventilator did not begin to be developed until the 1940s. From the original 1940s ventilators until today, 4 distinct generations of ICU ventilators have existed, each with features different from that of the previous generation. All of the advancements in ICU ventilator design over these generations provide the basis for speculation on the future. ICU ventilators of the future will be able to integrate electronically with other bedside technology; they will be able to effectively ventilate all patients in all settings, invasively and noninvasively; ventilator management protocols will be incorporated into the basic operation of the ventilator; organized information will be presented instead of rows of unrelated data; alarm systems will be smart; closed-loop control will be present on most aspects of ventilatory support; and decision support will be available. The key term that will be used to identify these future ventilators will be smart! PMID:21801579

Kacmarek, Robert M

2011-08-01

271

Ventilation and anesthetic approaches for rigid bronchoscopy.  

PubMed

Due to growing interest in management of central airway obstruction, rigid bronchoscopy is undergoing a resurgence in popularity among pulmonologists. Performing rigid bronchoscopy requires use of deep sedation or general anesthesia to achieve adequate patient comfort, whereas maintaining oxygenation and ventilation via an uncuffed and often open rigid bronchoscope requires use of ventilation strategies that may be unfamiliar to most pulmonologists. Available approaches include apneic oxygenation, spontaneous assisted ventilation, controlled ventilation, manual jet, and high-frequency jet ventilation. Anesthetic technique is partially dictated by the selected ventilation strategy but most often relies on a total intravenous anesthetic approach using ultra-short-acting sedatives and hypnotics for a rapid offset of action in this patient population with underlying respiratory compromise. Gas anesthetic may be used with the rigid bronchoscope, minimizing leaks with fenestrated caps placed over the ports, although persistent circuit leaks can make this approach challenging. Jet ventilation, the most commonly used ventilatory approach, may be delivered manually using a Sanders valve or via an automated ventilator at supraphysiologic respiratory rates, allowing for an open rigid bronchoscope to facilitate ease of moving tools in and out of the airway. Despite a patient population that often suffers from significant respiratory compromise, major complications with rigid bronchoscopy are uncommon and are similar among modern ventilation approaches. Choice of ventilation technique should be determined by local expertise and equipment availability. Appropriate patient selection and recognition of limitations associated with a given ventilation strategy are critical to avoid procedural-related complications. PMID:24635585

Pathak, Vikas; Welsby, Ian; Mahmood, Kamran; Wahidi, Momen; MacIntyre, Neil; Shofer, Scott

2014-05-01

272

Clinical review: Liberation from mechanical ventilation  

PubMed Central

Mechanical ventilation is the defining event of intensive care unit (ICU) management. Although it is a life saving intervention in patients with acute respiratory failure and other disease entities, a major goal of critical care clinicians should be to liberate patients from mechanical ventilation as early as possible to avoid the multitude of complications and risks associated with prolonged unnecessary mechanical ventilation, including ventilator induced lung injury, ventilator associated pneumonia, increased length of ICU and hospital stay, and increased cost of care delivery. This review highlights the recent developments in assessing and testing for readiness of liberation from mechanical ventilation, the etiology of weaning failure, the value of weaning protocols, and a simple practical approach for liberation from mechanical ventilation.

El-Khatib, Mohamad F; Bou-Khalil, Pierre

2008-01-01

273

Summary of human responses to ventilation  

SciTech Connect

The effects of ventilation on indoor air quality and health is a complex issue. It is known that ventilation is necessary to remove indoor generated pollutants from indoor air or dilute their concentration to acceptable levels. But, as the limit values of all pollutants are not known, the exact determination of required ventilation rates based on pollutant concentrations and associated risks is seldom possible. The selection of ventilation rates has to be based also on epidemiological research (e.g. Seppanen et al., 1999), laboratory and field experiments (e.g. CEN 1996, Wargocki et al., 2002a) and experience (e.g. ECA 2003). Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated as summarized by Seppdnen (2003). Ventilation may bring indoors harmful substances that deteriorate the indoor environment. Ventilation also affects air and moisture flow through the building envelope and may lead to moisture problems that deteriorate the structures of the building. Ventilation changes the pressure differences over the structures of building and may cause or prevent the infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. Ventilation can be implemented with various methods which may also affect health (e.g. Seppdnen and Fisk, 2002, Wargocki et al., 2002a). In non residential buildings and hot climates, ventilation is often integrated with air-conditioning which makes the operation of ventilation system more complex. As ventilation is used for many purposes its health effects are also various and complex. This paper summarizes the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus of the paper is on office-type working environment and residential buildings. In the industrial premises the problems of air quality are usually more complex and case specific. They are subject to occupational safety legislation and not discussed here.

Seppanen, Olli A.; Fisk, William J.

2004-06-01

274

Poloxamer 188 Facilitates the Repair of Alveolus Resident Cells in Ventilator-injured Lungs  

PubMed Central

Rationale: Wounded alveolus resident cells are identified in human and experimental acute respiratory distress syndrome models. Poloxamer 188 (P188) is an amphiphilic macromolecule shown to have plasma membrane–sealing properties in various cell types. Objectives: To investigate whether P188 (1) protects alveolus resident cells from necrosis and (2) is associated with reduced ventilator-induced lung injury in live rats, isolated perfused rat lungs, and scratch and stretch–wounded alveolar epithelial cells. Methods: Seventy-four live rats and 18 isolated perfused rat lungs were ventilated with injurious or protective strategies while infused with P188 or control solution. Alveolar epithelial cell monolayers were subjected to scratch or stretch wounding in the presence or absence of P188. Measurements and Main Results: P188 was associated with fewer mortally wounded alveolar cells in live rats and isolated perfused lungs. In vitro, P188 reduced the number of injured and necrotic cells, suggesting that P188 promotes cell repair and renders plasma membranes more resilient to deforming stress. The enhanced cell survival was accompanied by improvement in conventional measures of lung injury (peak airway pressure, wet-to-dry weight ratio) only in the ex vivo–perfused lung preparation and not in the live animal model. Conclusions: P188 facilitates plasma membrane repair in alveolus resident cells, but has no salutary effects on lung mechanics or vascular barrier properties in live animals. This discordance may have pathophysiological significance for the interdependence of different injury mechanisms and therapeutic implications regarding the benefits of prolonging the life of stress-activated cells.

Plataki, Maria; Lee, Yang D.; Rasmussen, Deborah L.

2011-01-01

275

Poloxamer 188 facilitates the repair of alveolus resident cells in ventilator-injured lungs.  

PubMed

Rationale: Wounded alveolus resident cells are identified in human and experimental acute respiratory distress syndrome models. Poloxamer 188 (P188) is an amphiphilic macromolecule shown to have plasma membrane-sealing properties in various cell types. Objectives: To investigate whether P188 (1) protects alveolus resident cells from necrosis and (2) is associated with reduced ventilator-induced lung injury in live rats, isolated perfused rat lungs, and scratch and stretch-wounded alveolar epithelial cells. Methods: Seventy-four live rats and 18 isolated perfused rat lungs were ventilated with injurious or protective strategies while infused with P188 or control solution. Alveolar epithelial cell monolayers were subjected to scratch or stretch wounding in the presence or absence of P188. Measurements and Main Results: P188 was associated with fewer mortally wounded alveolar cells in live rats and isolated perfused lungs. In vitro, P188 reduced the number of injured and necrotic cells, suggesting that P188 promotes cell repair and renders plasma membranes more resilient to deforming stress. The enhanced cell survival was accompanied by improvement in conventional measures of lung injury (peak airway pressure, wet-to-dry weight ratio) only in the ex vivo-perfused lung preparation and not in the live animal model. Conclusions: P188 facilitates plasma membrane repair in alveolus resident cells, but has no salutary effects on lung mechanics or vascular barrier properties in live animals. This discordance may have pathophysiological significance for the interdependence of different injury mechanisms and therapeutic implications regarding the benefits of prolonging the life of stress-activated cells. PMID:21778295

Plataki, Maria; Lee, Yang D; Rasmussen, Deborah L; Hubmayr, Rolf D

2011-10-15

276

T2-*weighted perfusion MRI.  

PubMed

T2*-weighted perfusion MRI is based on the so-called "first passage" approach: the modifications in the T2-weighted MRI signal are followed during the first passage of a bolus of contrast agent. The pixel-by-pixel analysis of the curves is used to obtain parametric maps (time of arrival, time of the peak, mean transit time, relative volume and blood flow). Further analysis, with deconvolution by arterial input function (concentration of contrast agent in the blood), helps improve the quantification. It is possible to pre-inject a small dose of contrast agent to limit the impact of the extravasation of the contrast agent. PMID:23845414

Barbier, E L

2013-12-01

277

Functional imaging of cerebral perfusion.  

PubMed

The functional imaging of perfusion enables the study of its properties such as the vasoreactivity to circulating gases, the autoregulation and the neurovascular coupling. Downstream from arterial stenosis, this imaging can estimate the vascular reserve and the risk of ischemia in order to adapt the therapeutic strategy. This method reveals the hemodynamic disorders in patients suffering from Alzheimer's disease or with arteriovenous malformations revealed by epilepsy. Functional MRI of the vasoreactivity also helps to better interpret the functional MRI activation in practice and in clinical research. PMID:24011870

Krainik, A; Villien, M; Troprès, I; Attyé, A; Lamalle, L; Bouvier, J; Pietras, J; Grand, S; Le Bas, J-F; Warnking, J

2013-12-01

278

Diffusion and perfusion MRI: basic physics  

Microsoft Academic Search

Diffusion and perfusion MR imaging are now being used increasingly in neuro-vascular clinical applications. While diffusion weighted magnetic resonance imaging exploits the translational mobility of water molecules to obtain information on the microscopic behaviour of the tissues (presence of macromolecules, presence and permeability of membranes, equilibrium intracellular–extracellular water,…), perfusion weighted imaging makes use of endogenous and exogenous tracers for monitoring

R Luypaert; S Boujraf; S Sourbron; M Osteaux

2001-01-01

279

Wet cupping therapy restores sympathovagal imbalances in cardiac rhythm.  

PubMed

Abstract Objectives: A recent study showed that cupping had therapeutic effects in rats with myocardial infarction and cardiac arrhythmias. The current studyaimed to investigate the possible useful effects of cupping therapy on cardiac rhythm in terms of heart rate variability (HRV). Materials and methods: Forty healthy participants were included. Classic wet cupping therapy was applied on five points of the back. Recording electrocardiography (to determine HRV) was applied 1 hour before and 1 hour after cupping therapy. Results: All HRV parameters increased after cupping therapy compared with before cupping therapy in healthy persons. Conclusions: These results indicate for the first time in humans that cupping might be cardioprotective. In this study, cupping therapy restored sympathovagal imbalances by stimulating the peripheral nervous system. PMID:24520978

Arslan, Müzeyyen; Ye?ilçam, Nesibe; Aydin, Duygu; Yüksel, Ramazan; Dane, Senol

2014-04-01

280

Depersonalization disorder may be related to glutamate receptor activation imbalance.  

PubMed

Low-dose ketamine administration mimics, both clinically and on gross neuroimaging, depersonalization disorder. The perceptual effects of ketamine may be due to secondary stimulation of glutamate release and lamotrigine, possibly by inhibited glutamate release, may reduce some of ketamine's so-called dissociative effects. However, lamotrigine does not seem to be useful in the treatment of depersonalization disorder. Glutamate release in prefrontal cortex is increased by subanaesthetic doses of ketamine, resulting in increased inhibition, possibly via intercalated GABAerg cells, of projections from amygdala, affecting structures critically involved in depersonalization. I speculate that, in depersonalization disorder, the increased glutamate activity in prefrontal cortex is due to intrinsic imbalance, resulting in long-term potentiation, at the postsynaptic glutamate receptors on the GABAerg interneurons while the same receptor abnormality at the synapses on the intercalated GABAerg cells of the amygdala result in long-term depression in the case of either normal or high glutamate release. PMID:21742442

Pikwer, Andreas

2011-10-01

281

Development of a Residential Integrated Ventilation Controller  

SciTech Connect

The goal of this study was to develop a Residential Integrated Ventilation Controller (RIVEC) to reduce the energy impact of required mechanical ventilation by 20percent, maintain or improve indoor air quality and provide demand response benefits. This represents potential energy savings of about 140 GWh of electricity and 83 million therms of natural gas as well as proportional peak savings in California. The RIVEC controller is intended to meet the 2008 Title 24 requirements for residential ventilation as well as taking into account the issues of outdoor conditions, other ventilation devices (including economizers), peak demand concerns and occupant preferences. The controller is designed to manage all the residential ventilation systems that are currently available. A key innovation in this controller is the ability to implement the concept of efficacy and intermittent ventilation which allows time shifting of ventilation. Using this approach ventilation can be shifted away from times of high cost or high outdoor pollution towards times when it is cheaper and more effective. Simulations, based on the ones used to develop the new residential ventilation requirements for the California Buildings Energy code, were used to further define the specific criteria and strategies needed for the controller. These simulations provide estimates of the energy, peak power and contaminant improvement possible for different California climates for the various ventilation systems. Results from a field test of the prototype controller corroborate the predicted performance.

Staff Scientist; Walker, Iain; Sherman, Max; Dickerhoff, Darryl

2011-12-01

282

Passive ventilation for residential air quality control  

SciTech Connect

Infiltration has long served the residential ventilation needs in North America. In Northern Europe it has been augmented by purpose-provided natural ventilation systems--so-called passive ventilation systems--to better control moisture problems in dwellings smaller than their North American counterparts and in a generally wetter climate. The growing concern for energy consumption, and the environmental impacts associated with it, has however led to tighter residential construction standards on both continents and as a result problems associated with insufficient background ventilation have surfaced. Can European passive ventilation systems be adapted for use in North American dwellings to provide general background ventilation for air quality control? This paper attempts to answer this question. The configuration, specifications and performance of the preferred European passive ventilation system--the passive stack ventilation (PSV) system--will be reviewed; innovative components and system design strategies recently developed to improve the traditional PSV system performance will be outlined; and alternative system configurations will be presented that may better serve the climatic extremes and more urban contexts of North America. While these innovative and alternative passive ventilation systems hold great promise for the future, a rational method to size the components of these systems to achieve the control and precision needed to meet the conflicting constraints of new ventilation and air tightness standards has not been forthcoming. Such a method will be introduced in this paper and an application of this method will be presented.

Axley, J.

1999-07-01

283

"Molecular rulers" for calibrating phenotypic effects of telomere imbalance.  

PubMed

As a result of the increasing use of genome wide telomere screening, it has become evident that a significant proportion of people with idiopathic mental retardation have subtle abnormalities involving the telomeres of human chromosomes. However, during the course of these studies, there have also been telomeric imbalances identified in normal people that are not associated with any apparent phenotype. We have begun to scrutinize cases from both of these groups by determining the extent of the duplication or deletion associated with the imbalance. Five cases were examined where the telomere rearrangement resulted in trisomy for the 16p telomere. The size of the trisomic segment ranged from approximately 4-7 Mb and the phenotype included mental and growth retardation, brain malformations, heart defects, cleft palate, pancreatic insufficiency, genitourinary abnormalities, and dysmorphic features. Three cases with telomeric deletions without apparent phenotypic effects were also examined, one from 10q and two from 17p. All three deletions were inherited from a phenotypically normal parent carrying the same deletion, thus without apparent phenotypic effect. The largest deletion among these cases was approximately 600 kb on 17p. Similar studies are necessary for all telomeric regions to differentiate between those telomeric rearrangements that are pathogenic and those that are benign variants. Towards this goal, we are developing "molecular rulers" that incorporate multiple clones at each telomere that span the most distal 5 Mb region. While telomere screening has enabled the identification of telomere rearrangements, the use of molecular rulers will allow better phenotype prediction and prognosis related to these findings. PMID:12362030

Martin, C L; Waggoner, D J; Wong, A; Uhrig, S; Roseberry, J A; Hedrick, J F; Pack, S D; Russell, K; Zackai, E; Dobyns, W B; Ledbetter, D H

2002-10-01

284

"Molecular rulers" for calibrating phenotypic effects of telomere imbalance  

PubMed Central

As a result of the increasing use of genome wide telomere screening, it has become evident that a significant proportion of people with idiopathic mental retardation have subtle abnormalities involving the telomeres of human chromosomes. However, during the course of these studies, there have also been telomeric imbalances identified in normal people that are not associated with any apparent phenotype. We have begun to scrutinise cases from both of these groups by determining the extent of the duplication or deletion associated with the imbalance. Five cases were examined where the telomere rearrangement resulted in trisomy for the 16p telomere. The size of the trisomic segment ranged from ?4-7 Mb and the phenotype included mental and growth retardation, brain malformations, heart defects, cleft palate, pancreatic insufficiency, genitourinary abnormalities, and dysmorphic features. Three cases with telomeric deletions without apparent phenotypic effects were also examined, one from 10q and two from 17p. All three deletions were inherited from a phenotypically normal parent carrying the same deletion, thus without apparent phenotypic effect. The largest deletion among these cases was ?600 kb on 17p. Similar studies are necessary for all telomeric regions to differentiate between those telomeric rearrangements that are pathogenic and those that are benign variants. Towards this goal, we are developing "molecular rulers" that incorporate multiple clones at each telomere that span the most distal 5 Mb region. While telomere screening has enabled the identification of telomere rearrangements, the use of molecular rulers will allow better phenotype prediction and prognosis related to these findings.

Martin, C; Waggoner, D; Wong, A; Uhrig, S; Roseberry, J; Hedrick, J; Pack, S; Russell, K; Zackai, E; Dobyns, W; Ledbetter, D

2002-01-01

285

Particle deposition in ventilation ducts  

SciTech Connect

Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 {micro}m were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the experimental measurements was applied to evaluate particle losses in supply and return duct runs. Model results suggest that duct losses are negligible for particle sizes less than 1 {micro}m and complete for particle sizes greater than 50 {micro}m. Deposition to insulated ducts, horizontal duct floors and bends are predicted to control losses in duct systems. When combined with models for HVAC filtration and deposition to indoor surfaces to predict the ultimate fates of particles within buildings, these results suggest that ventilation ducts play only a small role in determining indoor particle concentrations, especially when HVAC filtration is present. However, the measured and modeled particle deposition rates are expected to be important for ventilation system contamination.

Sippola, Mark R.

2002-09-01

286

Imbalance between neuroexcitatory and neuroinhibitory amino acids causes craving for ethanol  

Microsoft Academic Search

Long-term exposure to ethanol leads to an imbalance in different excitatory and inhibitory amino acids. When ethanol consumption is reduced or completely stopped, these imbalances in different amino acids and neurotransmitters are behaviorally expressed in the form of ethanol withdrawal. Glutamate, a major excitatory amino acid, and GABA, a major inhibitory amino acid, are responsible, at least partly, for ethanol

Philippe De Witte

2004-01-01

287

Wife Beating in South Africa: An Imbalance Theory of Resources and Power  

ERIC Educational Resources Information Center

This article develops an imbalance theory to explain physical violence against women in intimate relationships in South Africa. The theory proposes four typologies: dependence, compensation, submission, and transgression, through which imbalances in resource contribution and power distribution between spouses are hypothesized to contribute to…

Choi, Susanne Y. P.; Ting, Kwok-Fai

2008-01-01

288

Joint Tx and Rx IQ Imbalance Compensation of OFDM Transceiver in Mesh Network  

Microsoft Academic Search

The direct conversion is an attractive architecture, as compared to the traditional heterodyne approach, for both transmitter and receiver design. In spite of its great advantages in hardware implementation, direct conversion results in several negative effects, such as IQ imbalance, flicker noise, DC offset, etc. In this paper, we study the IQ imbalance problems occur at both transmitter and receiver

Chia-horng Liu

2008-01-01

289

On the k-NN performance in a challenging scenario of imbalance and overlapping  

Microsoft Academic Search

A two-class data set is said to be imbalanced when one (minority) class is heavily under-represented with respect to the other (majority) class. In the presence of a significant overlapping, the task of learning from imbalanced data can be a very difficult problem. Addi- tionally, if the overall imbalance ratio is different from local imbalance ratios in overlap regions, the

Vicente García; Ramón Alberto Mollineda; José Salvador Sánchez

2008-01-01

290

Nontraditional modes of mechanical ventilation: progress or distraction?  

PubMed

As technology continues to develop, a wide range of novel and nontraditional modes of mechanical ventilation have become available for the management of critically ill patients. Proportional assist ventilation, neurally adjusted ventilatory assist and adaptive support ventilation are three novel modes of ventilation, which attempt to optimize patient-ventilator synchrony. Improved interactions between patient and ventilator may be important in improving clinical outcomes. Another important priority for mechanically ventilated patients is lung protection, and nontraditional modes of ventilation that may be implemented to minimize ventilator-associated lung injury include airway pressure release ventilation and high-frequency ventilation. Novel and nontraditional modes of ventilation may represent important tools in the critical care environment; however, continued investigation is needed to determine the overall impact of these various approaches on outcomes for mechanically ventilated patients. PMID:22788942

Turner, David A; Rehder, Kyle J; Cheifetz, Ira M

2012-06-01

291

Assessment of regional lung ventilation by electrical impedance tomography in a patient with unilateral bronchial stenosis and a history of tuberculosis*  

PubMed Central

Bronchial stenosis can impair regional lung ventilation by causing abnormal, asymmetric airflow limitation. Electrical impedance tomography (EIT) is an imaging technique that allows the assessment of regional lung ventilation and therefore complements the functional assessment of the lungs. We report the case of a patient with left unilateral bronchial stenosis and a history of tuberculosis, in whom regional lung ventilation was assessed by EIT. The EIT results were compared with those obtained by ventilation/perfusion radionuclide imaging. The patient was using nasal continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea syndrome. Therefore, we studied the effects of postural changes and of the use of nasal CPAP. The EIT revealed heterogeneous distribution of regional lung ventilation, the ventilation being higher in the right lung, and this distribution was influenced by postural changes and CPAP use. The EIT assessment of regional lung ventilation produced results similar to those obtained with the radionuclide imaging technique and had the advantage of providing a dynamic evaluation without radiation exposure.

Marinho, Liegina Silveira; de Sousa, Nathalia Parente; Barros, Carlos Augusto Barbosa da Silveira; Matias, Marcelo Silveira; Monteiro, Luana Torres; Beraldo, Marcelo do Amaral; Costa, Eduardo Leite Vieira; Amato, Marcelo Britto Passos; Holanda, Marcelo Alcantara

2013-01-01

292

Mechanisms of ventilation-perfusion mismatch and hemodynamic alterations in acute and chronic pulmonary embolism  

Microsoft Academic Search

Summary Studies on gas exchange in pulmonary embolism are not numerous. A few of them have been performed in experimental animals [4]. The methods employed comprise the determination of gas exchange parameters [14], including the physiologic dead space [1], and the multiple inert gas elimination technique [2, 8, 10]. Furthermore, not much effort has been made to relate topographical alterations

C. Giuntini; A. Santolicandro; R. Prediletto; P. Paoletti; B. Formichi; E. Fornai; E. Begliomini; R. Puntoni; A. Perissinotto; A. Giannella Neto

2000-01-01

293

Effects of a chemical imbalance causal explanation on individuals' perceptions of their depressive symptoms.  

PubMed

Although the chemical imbalance theory is the dominant causal explanation of depression in the United States, little is known about the effects of this explanation on depressed individuals. This experiment examined the impact of chemical imbalance test feedback on perceptions of stigma, prognosis, negative mood regulation expectancies, and treatment credibility and expectancy. Participants endorsing a past or current depressive episode received results of a bogus but credible biological test demonstrating their depressive symptoms to be caused, or not caused, by a chemical imbalance in the brain. Results showed that chemical imbalance test feedback failed to reduce self-blame, elicited worse prognostic pessimism and negative mood regulation expectancies, and led participants to view pharmacotherapy as more credible and effective than psychotherapy. The present findings add to a growing literature highlighting the unhelpful and potentially iatrogenic effects of attributing depressive symptoms to a chemical imbalance. Clinical and societal implications of these findings are discussed. PMID:24657311

Kemp, Joshua J; Lickel, James J; Deacon, Brett J

2014-05-01

294

Effects of surfactant depletion on regional pulmonary metabolic activity during mechanical ventilation  

PubMed Central

Inflammation during mechanical ventilation is thought to depend on regional mechanical stress. This can be produced by concentration of stresses and cyclic recruitment in low-aeration dependent lung. Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) allows for noninvasive assessment of regional metabolic activity, an index of neutrophilic inflammation. We tested the hypothesis that, during mechanical ventilation, surfactant-depleted low-aeration lung regions present increased regional 18F-FDG uptake suggestive of in vivo increased regional metabolic activity and inflammation. Sheep underwent unilateral saline lung lavage and were ventilated supine for 4 h (positive end-expiratory pressure = 10 cmH2O, tidal volume adjusted to plateau pressure = 30 cmH2O). We used PET scans of injected 13N-nitrogen to compute regional perfusion and ventilation and injected 18F-FDG to calculate 18F-FDG uptake rate. Regional aeration was quantified with transmission scans. Whole lung 18F-FDG uptake was approximately two times higher in lavaged than in nonlavaged lungs (2.9 ± 0.6 vs. 1.5 ± 0.3 10?3/min; P < 0.05). The increased 18F-FDG uptake was topographically heterogeneous and highest in dependent low-aeration regions (gas fraction 10–50%, P < 0.001), even after correction for lung density and wet-to-dry lung ratios. 18F-FDG uptake in low-aeration regions of lavaged lungs was higher than that in low-aeration regions of nonlavaged lungs (P < 0.05). This occurred despite lower perfusion and ventilation to dependent regions in lavaged than nonlavaged lungs (P < 0.001). In contrast, 18F-FDG uptake in normally aerated regions was low and similar between lungs. Surfactant depletion produces increased and heterogeneously distributed pulmonary 18F-FDG uptake after 4 h of supine mechanical ventilation. Metabolic activity is highest in poorly aerated dependent regions, suggesting local increased inflammation.

de Prost, Nicolas; Costa, Eduardo L.; Wellman, Tyler; Musch, Guido; Winkler, Tilo; Tucci, Mauro R.; Harris, R. Scott; Venegas, Jose G.

2011-01-01

295

A continuous perfusion microplate for cell culture.  

PubMed

We describe a 96-well microplate with fluidically connected wells that enables the continuous fluid perfusion between wells without the need for external pumping. A single unit in such a perfusion microplate consists of three wells: a source well, a sample (cell culture) well in the middle and a waste well. Fluid perfusion is achieved using a combination of the hydrostatic pressure generated by different liquid levels in the wells and the fluid wicking through narrow strips of a cellulose membrane connecting the wells. There is an excellent correspondence between the observed perfusion flow dynamics and the flow simulations based on Darcy's Law. Hepatocytes (C3A cells) cultured for 4 days in the perfusion microplate with no media exchange in the cell culture well had the same viability as hepatocytes exposed to a daily exchange of media. EOC 20 cells that require media conditioned by LADMAC cells were shown to be equally viable in the adjacent cell culture well of the perfusion microplate with LADMAC cells cultured in the source well. Tegafur, a prodrug, when added to primary human hepatocytes in the source well, was metabolized into a cytotoxic metabolite that kills colon cancer cells (HCT 116) cultured in the adjacent cell culture well; no toxicity was observed when only medium was in the source well. These results suggest that the perfusion microplate is a useful tool for a variety of cell culture applications with benefits ranging from labor savings to enabling in vivo-like toxicity studies. PMID:23344077

Goral, Vasiliy N; Zhou, Chunfeng; Lai, Fang; Yuen, Po Ki

2013-03-21

296

Status of pediatric perfusion education: 2000 survey.  

PubMed

In recent years, studies have raised questions about pediatric perfusion training, minimum proficiency requirements, and specialization. To understand these questions better, a survey was undertaken to investigate the status of pediatric/neonatal perfusion training in the United States. Three groups were surveyed: program directors (PD), recent graduates of perfusion programs (RG), and pediatric cardiac anesthesiologists (PCA). Program directors and recent graduates were queried about didactic curriculum and clinical experiences. All three groups were asked core questions regarding minimum proficiency, specialization, and need for a postgraduate style program. Didactically, 65% of program directors believed that perfusion programs provided a solid introductory knowledge base in infant perfusion. Clinically, students performed an average of 124 +/- 42.5 adult and 17 +/- 12.9 pediatric cases during their education. Program directors cited numerous limitations to clinical pediatric education, including access to pediatric cases and allocation of resources. The PD (69%) and RG (96%) both believed graduates were less prepared to perform infant/pediatric cardio-pulmonary bypass (CPB) at graduation as compared to adult CPB. The opinions of all three groups were divided when asked whether the essentials and guidelines requirement for minimum pediatric caseload is too low (yes response: PD 52%, RG 73%, PCA 47%). The PD and RG were against pediatric subspecialization/certification (87%, 57% respectively); whereas, the PCA were unanimously in favor (100%) of pediatric subspecialization/certification for perfusionist. All three groups felt a postgraduate-style program in infant perfusion would benefit the community (78%, 82%, 100%). Finally, 64% of RG said that, if available, they would have considered entering a training program in pediatric/neonatal perfusion after graduation. Our results indicate that there are still limitations to pediatric perfusion education. A postgraduate-style program in infant perfusion is one possible solution to this problem. PMID:11806435

Angona, R; Searles, B; Nasrallah, F; Darling, E

2001-12-01

297

Gastroesophageal reflux in mechanically ventilated pediatric patients and its relation to ventilator-associated pneumonia  

Microsoft Academic Search

ABSTRACT: INTRODUCTION: The objective was to determine the frequency of gastroesophageal reflux (GER) in mechanically ventilated pediatric patients and its role as a risk factor for ventilator-associated pneumonia (VAP), which may be enhanced among those patients. METHODS: The study is a prospective cohort study of mechanically ventilated pediatric patients in the pediatric intensive care unit (PICU) of Ain Shams University

Tarek A Abdel-Gawad; Mostafa A El-Hodhod; Hanan M Ibrahim; Yousef W Michael

2009-01-01

298

Carbon Dioxide and Oxygen Levels in Disposable Individually Ventilated Cages after Removal from Mechanical Ventilation  

PubMed Central

Disposable individually ventilated cages have lids that restrict air exchange when the cage is not mechanically ventilated. This design feature may cause intracage CO2 to increase and O2 to decrease (hypercapnic and hypoxic conditions, respectively) when the electrical supply to the ventilated rack fails, the ventilated rack malfunctions, cages are docked in the rack incorrectly, or cages are removed from the ventilated rack for extended periods of time. We investigated how quickly hypercapnic and hypoxic conditions developed within disposable individually ventilated cages after removal from mechanical ventilation and compared the data with nondisposable static cages, disposable static cages, and unventilated nondisposable individually ventilated cages. When disposable individually ventilated cages with 5 adult mice per cage were removed from mechanical ventilation, CO2 concentrations increased from less than 1% at 0 h to approximately 5% at 3 h and O2 levels dropped from more than 20% at 0 h to 11.7% at 6 h. The breathing pattern of the mice showed a prominent abdominal component (hyperventilation). Changes were similar for 4 adult mice per cage, reaching at least 5% CO2 at 4 h and 13.0% O2 at 6 h. For 3 or 2 mice per cage, values were 4.6% CO2 and 14.7% O2 and 3.04% CO2 and 17.1% O2, respectively, at 6 h. These results document that within disposable individually ventilated cages, a hypercapnic and hypoxic microenvironment develops within hours in the absence of mechanical ventilation.

Nagamine, Claude M; Long, C Tyler; McKeon, Gabriel P; Felt, Stephen A

2012-01-01

299

Airway pressure release ventilation in morbidly obese surgical patients with acute lung injury and acute respiratory distress syndrome.  

PubMed

Morbidly obese patients with body mass index greater than 40 kg/m(2) and respiratory failure requiring critical care services are increasingly seen in trauma and acute care surgical centers. Baseline respiratory pathophysiology including decreased pulmonary compliance with dependent atelectasis and abnormal ventilation-perfusion relationships predisposes these patients to acute lung injury (ALI) and adult respiratory distress syndrome (ARDS) as well as prolonged stays in the intensive care unit. Airway pressure release ventilation (APRV) is an increasingly used alternative mode for salvage therapy in patients with hypoxemic respiratory failure that also provides lung protection from ventilator-induced lung injury. APRV provides the conceptual advantage of an "open lung" approach to ventilation that may be extended to the morbidly obese patient population with ALI and ARDS. We discuss the theoretical benefits and a recent clinical experience of APRV ventilation in the morbidly obese patient with respiratory failure at a Level I trauma, surgical critical care, and acute care surgery center. PMID:23461947

Testerman, George M; Breitman, Igal; Hensley, Sarah

2013-03-01

300

Studies on the 'Ventilation Effectiveness' and Modification of the Ventilation System in the Waiting Hall of a Railway Station  

Microsoft Academic Search

The concept of ventilation effectiveness for mechanical ventilation of an air space is reviewed and associated parameters for describing the performance of ventilation systems are described. The idea is applied to a study of the thermal environment in the waiting hall of a railway station. Two ventilation schemes: one with a ventilation system only and the other with an air-conditioning

W. K. Chow; W. Y. Fung

1996-01-01

301

High-frequency ventilation and conventional mechanical ventilation in newborn babies with respiratory distress syndrome: A prospective, randomized trial  

Microsoft Academic Search

Objective. Morbidity and mortality remain high amongst babies ventilated for a respiratory distress syndrome (RDS). Whether newly developed ventilators allowing high frequency ventilation such as high frequen- cy flow interrupted ventilation (HFFIV) could decrease the morbidity and the mortality was investigated in a ran- domized study. Design: Preterm babies weighing < 1800 g suffering from RDS and ventilated by conventional

A. Pardou; D. Vermeylen; M. F. Muller; D. Detemmerman

1993-01-01

302

Brain perfusion monitoring with frequency-domain and continuous-wave near-infrared spectroscopy: a cross-correlation study in newborn piglets  

Microsoft Academic Search

The newborn piglet brain model was used to correlate continuous-wave (CW) and frequency-domain (FD) near-infrared spectroscopy. Six ventilated and instrumented newborn piglets were subjected to a series of manipulations in blood oxygenation with the effects on brain perfusion known to be associated with brain hypoxia-ischaemia. An excellent agreement between the CW and FD was demonstrated. This agreement improved when the

G. Zhang; A. Katz; R. R. Alfano; A. D. Kofinas; D. A. Kofinas; P. G. Stubblefield; W. Rosenfeld; D. Beyer; D. Maulik; M. R. Stankovic

2000-01-01

303

Comparative evaluation of the effects of indomethacin and ibuprofen on cerebral perfusion and oxygenation in preterm infants with patent ductus arteriosus  

Microsoft Academic Search

Objective: To compare the effects on cerebral perfusion and oxygenation of intravenous ibuprofen and indomethacin as treatment for patent ductus arteriosus in preterm infants.Study design: Sixteen infants receiving mechanical ventilation (< 31 weeks gestation) with patent ductus arteriosus received either 0.2 mg\\/kg indomethacin ( n = 8) or 10 mg\\/kg ibuprofen ( n = 8) infused over 1 minute. Near-infrared

Fabio Mosca; Milena Bray; Maria Lattanzio; Monica Fumagalli; Camillo Tosetto

1997-01-01

304

The man-made creators of the imbalance of water in Nature  

NASA Astrophysics Data System (ADS)

At 2011 we have described the imbalance of water in Nature as the system [1]. At 2012 we have described water and carbon and the glaciers [2], [3] as creators of the imbalance of Nature. Now we are describing some man-made creators of the imbalance of Nature. The photosynthesis is a powerful creator of the imbalance of Nature. The photosynthesis significantly increases the complexity of the structures and reduces the entropy. Earth's hydrosphere contains water less than it was flowed via photosynthesis. This is an example of the imbalance of involving when the return of water has delayed because water is involved into the processes of life and other processes. People widely use photosynthesis and create not only an additional man-made imbalance of water in Nature, but also the man-made changing the albedo, and a lot of other important parameters of the planet of Earth. All of these processes are significantly imbalanced. The fossil hydrocarbons have accumulated during millions of years, but now are burned. This is an example of the imbalance delay by time. The man-made burning of the hydrocarbons is creating the imbalances of impact or explosive type, because of the burning processes is in millions of times faster than the accumulation processes. Please pay attention to the imbalance of redeployment by places. For example, oil and gas are extracted in one places, and burned in others. During combustion is standing out not only water, but energy, and other components. The temperature in the centers of big cities is always higher and there is dominating the rising air. It pollutes the environment, changes circulations, create greenhouse effect, etc. Other examples of the imbalance of relocation are shown in the production and consumption of food. The irrigation systems transfer water from one place to another. This transfer of water creates a lot of imbalances in change climate, ecosystems, etc in places where water was took and where the water was brought. Usually these are different places where the water taken, where the water used to grow crops, where the crop had eaten and where waste throw out. It creates a lot of the man-made imbalances of redeployment, which generate the new chains of different types of the man-made imbalances of water, other components and processes. The waste is one of the most important man-made creators of the imbalance of Nature. Some of water from the waste comes back into circulation in the clean or dirty conditions. Another part of water from waste will join into numerous water-based or water-use components of Nature, and fall out of the hydrological cycle for a long time. The quantity and diversity of waste are rising much faster than the recycles industries and it is creating a lot of dangerous imbalances of Nature. The wastes are is the time bombs, which man made, and which will soon explode. The traditional balanced science and practice are not prepared to deal with the waste problem. The concept of the imbalance of Nature can help prevent this catastrophic explosion. People are creating a lot of the man-made imbalances of Nature which bring the dangerous 'unexpected surprises'. The concept of the imbalance of Nature give possibilities to create the man-made imbalances of Nature with the predictable parameters and it can help do Mother Nature to be friendlier to humanity.

Shlafman, L. M.; Kontar, V. A.

2013-12-01

305

Analytic one dimensional transient conduction into a living perfuse/non-perfuse two layer composite system  

NASA Astrophysics Data System (ADS)

This study considers a two layer composite system in which transport within one layer is governed by pure diffusion and transport within the second layer is governed by both perfusion and diffusion. Previous solutions to this situation have approximated the layer without perfusion by using a small non-zero value of the perfusion coefficient. This study provides an exact one dimensional solution to a two layer composite system in which one layer has a high perfusion rate and the adjacent layer has a zero perfusion value. During the solution development, which uses the separation of variables method, the parametric constants and the perfusion term are coupled directly to the transient component of the governing equation. This is done to isolate the spatially diffusive term. The non-dimensional solution is developed symbolically and an example test case is provided to show the transient behavior of the solution using the first 20 terms of the series.

Becker, Sid

2012-02-01

306

High-volume hemofiltration and prone ventilation in subarachnoid hemorrhage complicated by severe acute respiratory distress syndrome and refractory septic shock  

PubMed Central

We report the successful treatment of two patients with aneurismal subarachnoid hemorrhage complicated by severe respiratory failure and refractory septic shock using simultaneous prone position ventilation and high-volume hemofiltration. These rescue therapies allowed the patients to overcome the critical situation without associated complications and with no detrimental effects on the intracranial and cerebral perfusion pressures. Prone position ventilation is now an accepted therapy for severe acute respiratory distress syndrome, and high-volume hemofiltration is a non-conventional hemodynamic support that has several potential mechanisms for improving septic shock. In this manuscript, we briefly review these therapies and the related evidence. When other conventional treatments are insufficient for providing safe limits of oxygenation and perfusion as part of basic neuroprotective care in subarachnoid hemorrhage patients, these rescue therapies should be considered on a case-by-case basis by an experienced critical care team.

Cornejo, Rodrigo; Romero, Carlos; Ugalde, Diego; Bustos, Patricio; Diaz, Gonzalo; Galvez, Ricardo; Llanos, Osvaldo; Tobar, Eduardo

2014-01-01

307

Ex vivo lung perfusion: a comprehensive review of the development and exploration of future trends.  

PubMed

There is a critical mismatch between the number of donor lungs available and the demand for lungs for transplantation. This has created unacceptably high waiting-list mortality for lung transplant recipients. Currently (2012) in the United Kingdom, there are 216 patients on the lung transplant waiting list and 17 on heart and lung transplant list. The waiting times for suitable lungs average 412 days, with an increasing mortality and morbidity among the patients on the lung transplant list. Ex vivo lung perfusion (EVLP) has emerged as a technique for the assessment, resuscitation, and potential repair of suboptimal donor lungs. This is a rapidly developing field with significant clinical implications. In this review article, we critically appraise the background developments that have led to our current clinical practice. In particular, we focus on the human and animal experience, the different perfusion-ventilation strategies, and the impact of different perfusates and leukocyte filters. Finally, we examine EVLP as a potential research tool. This will provide insight into EVLP and its future development in the field of clinical lung transplantation. PMID:23694953

Roman, Marius A; Nair, Sukumaran; Tsui, Steven; Dunning, John; Parmar, Jasvir S

2013-09-01

308

Effect of carbon monoxide on xenobiotic metabolism in the isolated perfused rabbit lung  

SciTech Connect

It was the aim of this study to determine the level and duration of CO exposure necessary to alter mixed function oxidase-mediated activity in the intact lung and to determine the magnitude of this effect. The effect of CO on the mixed function oxidase-mediated activities of aminopyrine, aniline, 4-ipomeanol and p-nitroanisole in isolated perfused rabbit lungs (IPRL) was investigated. Several concentrations of CO were evaluated for their effect on cytochrome P-450-mediated activity in the lung. Both artificial medium and whole blood were utilized as recirculating perfusates. Monomethyl-4-aminoantipyrine was the major metabolite of aminopyrine produced by in vitro hepatic and pulmonary preparations and by the intact lung. Ventilation of isolated rabbit lungs with 7.5% CO for 2.5 hours caused a 40% decrease in the rates of metabolism of both aminopyrine and p-nitroanisole. This level of CO exposure did not alter the cytochrome P-450-mediated metabolism of aniline nor 4-ipomeanol in the intact lung. Aminopyrine metabolism in isolated rabbit lungs perfused with whole blood was also decreased following the administration of 7.5% CO suggesting that the hemoglobin in whole blood affords no protection against CO-induced inhibition of mixed function oxidase activity in the intact lung. The isozyme of cytochrome P-450 which preferentially metabolizes aminopyrine and p-nitroanisole may be more sensitive to CO-induced inhibition than the form(s) which metabolize aniline and 4-ipomeanol.

Trela, B.A.

1988-01-01

309

Cyclooxygenase blockade (COB) attenuates ethanol-induced pulmonary vasoconstriction in perfused rat lungs  

SciTech Connect

Ethanol causes pulmonary vasoconstriction and vascular leak by obscure mechanisms. In lambs, COB with indomethacin (Indo) or meclofenamate (Meclo) block ethanol's circulatory effects. To test for these effects in rats, in-situ, ventilated, Krebs-Henselheit perfused (constant flow) lungs were studied in 6 groups: ethanol (ETOH) and perfusate controls; ETOH/Meclo, 0.5 and 1 mg/kg, IV; ETOH/Indo, 0.5 and 1 mg/kg, IV, given 30 minutes before study. They measured mean pulmonary arterial pressure (PAP), peak inspiratory pressure (PIP) and edema, indexed by reservoir weight change (RW), then by tracheal froth ( death'). ETOH doses (0.5, 1.3 and 2.2gm) were infused into the perfusate (60 ml). Data were analyzed by ANOVA and X{sup 2}; n = 9 in each group. PAP differed by treatment, by drug/dose, and by dose/treatment interactions; PIP, RW change, and death' were attenuated. Data show that COB lessens the vascular and edema effects of moderate dose ETOH, which larger ETOH doses override.

Drummond, W.H.; Lyles, D. (Univ. of Florida, Gainesville (United States))

1990-02-26

310

Site of pulmonary vasodilation by inhaled nitric oxide in the perfused lung  

SciTech Connect

Site of pulmonary vasodilation by inhaled nitric oxide in the perfused lung. To determine the site of inhaled nitric oxide (NO)-induced pulmonary vasodilation, a double vascular occlusion technique was used with rabbit lungs ventilated and perfused at 20 ml/min with Krebs solution containing 3% dextran and 30 {mu}M indomethacin. Inhaled NO (120 ppm for 3% min) reduced pulmonary vasoconstriction produced by U-46619 infusion (0.5 -1.2 nmol/min), significantly decreasing total resistance (RT) [1,080 {plus_minus} 51 (SE) vs. 1,545 {plus_minus} 109 mmHg-min/l; P < 0.01]. Acetylcholine infusion (ACh; 2-5 nmol/min) and nitroglycerin (NTG; 0.35 {mu}mol) likewise decreased RT. Arterial resistance (Ra) was also significantly less with inhaled NO, ACh, and NTG compared with U-46619 alone. Venous resistance (Rv), however, was unchanged. When the direction of perfusion was reversed in the lung, inhaled NO, ACh, and NTG significantly decreased RT compared with U-46619 alone, and Rv was also reduced by all three agents. After electrolysis-induced acute lung injury, inhaled NO significantly reduced both RT and Ra compared with U-46619 alone, whereas Rv was unaffected. Our results demonstrate that inhaled NO gas affects primarily the arterial (precapillary) component of the pulmonary circulation but, under conditions of extreme venous constriction, may dilate the postcapillary component as well. 25 refs., 4 figs.

Rimar, S.; Gillis, C.N. [Yale Univ. School of Medicine, New Haven, CT (United States)

1995-05-01

311

46 CFR 92.15-10 - Ventilation for closed spaces.  

Code of Federal Regulations, 2010 CFR

...VESSELS CONSTRUCTION AND ARRANGEMENT Ventilation § 92.15-10 Ventilation for closed spaces. (a) Except as...Means shall be provided for stopping all fans in ventilation systems serving machinery and cargo...

2009-10-01

312

46 CFR 72.15-15 - Ventilation for closed spaces.  

Code of Federal Regulations, 2010 CFR

...VESSELS CONSTRUCTION AND ARRANGEMENT Ventilation § 72.15-15 Ventilation for closed spaces. (a) All enclosed...Means shall be provided for stopping all fans in ventilation systems serving machinery and cargo...

2009-10-01

313

46 CFR 190.15-10 - Ventilation for closed spaces.  

Code of Federal Regulations, 2013 CFR

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...storerooms, and machinery spaces and for closing all doorways, ventilators, and annular spaces around funnels and other openings...

2013-10-01

314

Mechanical Ventilation and the Kidney  

PubMed Central

Acute lung injury (ALI) and acute kidney injury (AKI) are complications often encountered in the setting of critical illness. Both forms of end-organ injury commonly occur in similar settings of systemic inflammatory response syndrome, shock, and evolving multiple organ dysfunction. Recent elucidation of the pathobiology of critical illness has led to a more basic mechanistic understanding of the complex interplay between injured organs in patients with multiple organ dysfunction syndrome; this has been aptly called ‘the slippery slope of critical illness’ [Kidney Int Suppl 1998;66:S25–S33]. Distant organ effects of apparently isolated injuries to the lungs, gut, and kidneys have all been discovered in recent years. In this article, we will review the harmful bidirectional interaction between ALI and AKI, which appears to be a common clinical syndrome with routine clinical implications. We will review the current understanding of lung-kidney interactions from both perspectives, including the renal effects of ALI and mechanical ventilation, and the pulmonary sequelae of AKI. In this review of the emerging evidence of deleterious bidirectional organ cross talk between lung and kidney, we will focus on the role of ventilator-induced kidney injury in the pathogenesis of AKI in patients with ALI.

Koyner, Jay L.; Murray, Patrick T.

2010-01-01

315

Soluble guanylyl cyclase contributes to ventilator-induced lung injury in mice  

PubMed Central

High tidal volume (HVT) ventilation causes pulmonary endothelial barrier dysfunction. HVT ventilation also increases lung nitric oxide (NO) and cGMP. NO contributes to HVT lung injury, but the role of cGMP is unknown. In the current study, ventilation of isolated C57BL/6 mouse lungs increased perfusate cGMP as a function of VT. Ventilation with 20 ml/kg VT for 80 min increased the filtration coefficient (Kf), an index of vascular permeability. The increased cGMP and Kf caused by HVT were attenuated by nitric oxide synthase (NOS) inhibition and in lungs from endothelial NOS knockout mice. Inhibition of soluble guanylyl cyclase (sGC) in wild-type lungs (10 ?M ODQ) also blocked cGMP generation and inhibited the increase in Kf, suggesting an injurious role for sGC-derived cGMP. sGC inhibition also attenuated lung Evans blue dye albumin extravasation and wet-to-dry weight ratio in an anesthetized mouse model of HVT injury. Additional activation of sGC (1.5 ?M BAY 41-2272) in isolated lungs at 40 min increased cGMP production and Kf in lungs ventilated with 15 ml/kg VT. HVT endothelial barrier dysfunction was attenuated with a nonspecific phosphodiesterase (PDE) inhibitor (100 ?M IBMX) as well as an inhibitor (10 ?M BAY 60-7550) specific for the cGMP-stimulated PDE2A. Concordantly, we found a VT-dependent increase in lung cAMP hydrolytic activity and PDE2A protein expression with a decrease in lung cAMP concentration that was blocked by BAY 60-7550. We conclude that HVT-induced endothelial barrier dysfunction resulted from a simultaneous increase in NO/sGC-derived cGMP and PDE2A expression causing decreased cAMP.

Schmidt, Eric P.; Damarla, Mahendra; Rentsendorj, Otgonchimeg; Servinsky, Laura E.; Zhu, Bing; Moldobaeva, Aigul; Gonzalez, Alfredo; Hassoun, Paul M.; Pearse, David B.

2008-01-01

316

Allelic imbalance in selected chromosomal regions in ovarian cancer.  

PubMed

Ovarian cancer (OC) is often asymptomatic at the initial stage. When diagnosed, up to 75% of the patients present grade III or IV tumors with metastasis in nearby organs of the abdomen. Genetic imbalance is abundant in OC, and allelic loss (AL) of specific chromosomal regions is considered an early event. To establish association between genetic markers for early diagnosis/prognosis of OC, our target was to define narrow specific regions of AL. We analyzed 65 ovarian carcinomas by using 19 microsatellite markers located in three different chromosomes. First, a 7.6-Mb region containing the estrogen receptor (ESR1) and the tumor suppressor gene LATS1 was analyzed. Several chromosomal breakpoints flanking ESR1 affecting the region harboring LATS1 were found. Second, we found chromosomal breakpoints on 13q13.1 approximately q13.3 that defined two narrow regions flanking the BRCA2 locus. Third, our ovarian tumors exhibited a very high frequency of AL on 16q and chromosomal breakpoints defining two narrow regions within 16q22.2 approximately q24.3. In this article, we report three new polymorphic microsatellite markers and strong evidence of AL of narrow well-defined regions in hot spots on 6q, 13q, and 16q in ovarian tumors. PMID:12547149

Hansen, Lise Lotte; Jensen, Lise Lind; Dimitrakakis, Constantine; Michalas, Stylianos; Gilbert, Fred; Barber, Hugh R K; Overgaard, Jens; Arzimanoglou, Iordanis I

2002-11-01

317

Does Observation of Postural Imbalance Induce a Postural Reaction?  

PubMed Central

Background Several studies bring evidence that action observation elicits contagious responses during social interactions. However automatic imitative tendencies are generally inhibited and it remains unclear in which conditions mere action observation triggers motor behaviours. In this study, we addressed the question of contagious postural responses when observing human imbalance. Methodology/Principal Findings We recorded participants' body sway while they observed a fixation cross (control condition), an upright point-light display of a gymnast balancing on a rope, and the same point-light display presented upside down. Our results showed that, when the upright stimulus was displayed prior to the inverted one, centre of pressure area and antero-posterior path length were significantly greater in the upright condition compared to the control and upside down conditions. Conclusions/Significance These results demonstrate a contagious postural reaction suggesting a partial inefficiency of inhibitory processes. Further, kinematic information was sufficient to trigger this reaction. The difference recorded between the upright and upside down conditions indicates that the contagion effect was dependent on the integration of gravity constraints by body kinematics. Interestingly, the postural response was sensitive to habituation, and seemed to disappear when the observer was previously shown an inverted display. The motor contagion recorded here is consistent with previous work showing vegetative output during observation of an effortful movement and could indicate that lower level control facilitates contagion effects.

Tia, Banty; Saimpont, Arnaud; Paizis, Christos; Mourey, France; Fadiga, Luciano; Pozzo, Thierry

2011-01-01

318

Imbalance of the Earth System in Terms of Entropy  

NASA Astrophysics Data System (ADS)

The Earth system consists of many interacting geospheres (e.g., atmosphere, hydrosphere, biosphere, lithosphere, pedosphere, cryosphere), each of which is further composed of interacting subsystems over a wide range of scales. The mainstream approach to tackle this complex system relies on earth system modeling (ESM) that is based on various conservation principles (e.g., conservation of energy, mass and momentum), breaks the Earth system into ever smaller units, and includes ever more processes. Despite the great progress over the last few decades, the bottom-up ESM approach still suffers from many deficiencies such as highly uncertain climate sensitivity and cloud feedbacks. This study explores a new theoretical framework that treats the Earth system as a whole and seeks entropy-based principles in addition to those conservation principles (e.g., energy conservation). In particular, we show that even at steady state, radiation entropy is highly imbalanced with the outgoing longwave radiation carrying much more radiation entropy than the incoming solar radiation, and that the Earth system as a whole works to maximize the radiation entropy imbalance by building close connection between incoming shortwave and outgoing longwave radiation. The entropy-based theory provides a possible explanation of why the Earth albedo varies around 0.3 during the Holocene.

Liu, Y.; Wu, W.; Wiscombe, W. J.

2012-12-01

319

Child underreporting, fertility, and sex ratio imbalance in China.  

PubMed

Child underreporting is often neglected in studies of fertility and sex ratio imbalance in China. To improve estimates of these measures, I use intercensal comparisons to identify a rise in underreporting, which followed the increased enforcement and penalization under the birth planning system in 1991. A new triangulation of evidence indicates that about 19% of children at ages 0-4 were unreported in the 2000 census, more than double that of the 1990 census. This evidence contradicts assumptions underlying the fertility estimates of most recent studies. Yet, the analysis also suggests that China's fertility in the late 1990s (and perhaps beyond) was below officially adjusted levels. I then conduct a similar intercensal analysis of sex ratios of births and children, which are the world's highest primarily because of prenatal sex selection. However, given excess underreporting of young daughters, especially pronounced just after 1990, estimated ratios are lower than reported ratios. Sex ratios in areas with a "1.5-child" policy are especially distorted because of excess daughter underreporting, as well as sex-linked stopping rules and other factors, although it is unclear whether such policies increase use of prenatal sex selection. China's sex ratio at birth, once it is standardized by birth order, fell between 2000 and 2005 and showed a continuing excess in urban China, not rural China. PMID:21336689

Goodkind, Daniel

2011-02-01

320

Mnesic imbalance: a cognitive theory about autism spectrum disorders  

PubMed Central

Autism is characterized by impairments in social interaction, communicative capacity and behavioral flexibility. Some cognitive theories can be useful for finding a relationship between these irregularities and the biological mechanisms that may give rise to this disorder. Among such theories are mentalizing deficit, weak central coherence and executive dysfunction, but none of them has been able to explain all three diagnostic symptoms of autism. These cognitive disorders may be related among themselves by faulty learning, since several research studies have shown that the brains of autistic individuals have abnormalities in the cerebellum, which plays a role in procedural learning. In keeping with this view, one may postulate the possibility that declarative memory replaces faulty procedural memory in some of its functions, which implies making conscious efforts in order to perform actions that are normally automatic. This may disturb cognitive development, resulting in autism symptoms. Furthermore, this mnesic imbalance is probably involved in all autism spectrum disorders. In the present work, this theory is expounded, including preliminary supporting evidence.

Romero-Munguia, Miguel Angel

2008-01-01

321

Association of Sympathovagal Imbalance with Cardiovascular Risks in Overt Hypothyroidism  

PubMed Central

Background: Cardiovascular morbidities have been reported in hypothyroidism. Aims: The objective of this study is to investigate the link of sympathovagal imbalance (SVI) to cardiovascular risks (CVRs) and the plausible mechanisms of CVR in hypothyroidism. Materials and Methods: Age-matched 104 females (50 controls, 54 hypothyroids) were recruited and their body mass index (BMI), cardiovascular parameters, autonomic function tests by spectral analysis of heart rate variability (HRV), heart rate response to standing, deep breathing and blood pressure response to isometric handgrip were studied. Thyroid profile, lipid profile, immunological and inflammatory markers were estimated and their association with low-frequency to the high-frequency ratio (LF-HF) of HRV, the marker of SVI was assessed by multivariate regression. Results: Increased diastolic pressure, decreased HRV, increased LF-HF, dyslipidemia and increased high-sensitive C-reactive protein (hsCRP) were observed in hypothyroid patients and all these parameters had significant correlation with LF-HF. BMI had no significant association with LF-HF. Atherogenic index (? 1.144, P = 0.001) and hsCRP (b 0.578, P = 0.009) had independent contribution to LF-HF. LF-HF could significantly predict hypertension status (odds ratio 2.05, confidence interval 1.110-5.352, P = 0.008) in hypothyroid subjects. Conclusions: SVI due to sympathetic activation and vagal withdrawal occurs in hypothyroidism. Dyslipidemia and low-grade inflammation, but not obesity contribute to SVI and SVI contributes to cardiovascular risks.

Syamsunder, Avupati Naga; Pal, Gopal Krushna; Pal, Pravati; Kamalanathan, Chandrakasan Sadishkumar; Parija, Subhash Chandra; Nanda, Nivedita

2013-01-01

322

Microcirculation perfusion monitor on the back of the health volunteers.  

PubMed

Objective. To observe the dermal microcirculation blood perfusion characterization of meridians channels (acupoints). Methods. 20 healthy human subjects were monitored using Pericam Perfusion Speckle Imager (PSI) for the changes in dermal microcirculation blood perfusion on governor meridian and other respective dermal regions as a control. Result. The microcirculation blood perfusion on Governor Meridian is higher than its control area. Conclusion. The dermal microcirculation blood perfusion on certain parts of Governor Meridian of healthy human subjects showed specifics. PMID:24371463

Li, Yanqi; Li, Xiaomei; Zhou, Dan; Wang, Kang; Liu, Yangyang; Guo, Yi; Qiu, Shuang; Zhai, Tianchen; Liu, Shuang; Liu, Jingjing; Ming, Dong

2013-01-01

323

Volume-controlled ventilation. Variations on a theme.  

PubMed

Development of sophisticated transducers and microprocessor-based ventilators now enables the performance of volume-controlled ventilation of newborn infants. Volume-controlled modes include standard intermittent or synchronized intermittent mandatory ventilation; assist-control ventilation; and hybrid modes, such as pressure-support ventilation, pressure-regulated volume-control ventilation, volume-assured pressure support, and volume guarantee. This article describes the concepts and clinical applications of these ventilatory modes. PMID:11570154

Sinha, S K; Donn, S M

2001-09-01

324

Performance of Ventilation Systems in Residential Buildings.  

National Technical Information Service (NTIS)

The aim of the study was to gather information on the performance of ventilation systems in residential buildings. The effect of the ventilation on health, comfort and satisfaction was also studied. Data was also collected of the fullfilment of National B...

R. Roennberg R. Ruotsalainen A. Majanen

1989-01-01

325

IMPACT OF DOUBLE VENTILATED FACADES IN BUILDINGS  

Microsoft Academic Search

Double ventilated façades are becoming quite common in buildings in Europe. The new IEA ECBCS Annex 44 entitled 'Integrating environmentally responsive elements in buildings' will among other elements consider the double ventilated façades. The use of this kind of façades has an impact on several aspects of the building in the design phase as in the exploitation phase of the

Xavier Loncour; Peter Wouters; Marcelo Blasco

326

NUMERICAL EVALUATION OF HYBRID VENTILATION CONTROL STRATEGIES  

Microsoft Academic Search

This paper deals with the development and the evaluation of hybrid ventilation control strategies, using both natural and mechanical modes, in residential buildings using a graphical simulation tool. The description of a library of airflow components and macroscopic pollutants models used to simulate the demand controlled ventilation based on indoor pollutant concentrations is provided. The paper discusses the issue of

David Jreijiry; Ahmad Husaunndee; Christian Inard

2005-01-01

327

46 CFR 116.610 - Ventilation ducts.  

Code of Federal Regulations, 2013 CFR

...minimized. (f) A ventilation duct penetrating an A-Class or...requirements: (1) A ventilation duct must meet the same requirements...to the passage of smoke and flame as the fire control boundary penetrated; (2) A steel duct penetrating an A-Class...

2013-10-01

328

46 CFR 116.610 - Ventilation ducts.  

Code of Federal Regulations, 2010 CFR

...minimized. (f) A ventilation duct penetrating an A-Class or...requirements: (1) A ventilation duct must meet the same requirements...to the passage of smoke and flame as the fire control boundary penetrated; (2) A steel duct penetrating an A-Class...

2010-10-01

329

46 CFR 116.610 - Ventilation ducts.  

Code of Federal Regulations, 2010 CFR

...minimized. (f) A ventilation duct penetrating an A-Class or...requirements: (1) A ventilation duct must meet the same requirements...to the passage of smoke and flame as the fire control boundary penetrated; (2) A steel duct penetrating an A-Class...

2009-10-01

330

Energy recovery using ventilated double glazing  

Microsoft Academic Search

In a heated building, the outflow of some heat energy through windows is inevitable and can be a waste. It is possible to recover some of this heat loss by directing ventilation fresh air along the surface of the window. A modified double glazing unit with ventilation passage has been used to investigate the reduced heat losses with various flow

Raymond Smyth

1981-01-01

331

Increasing energy efficiency of mine ventilation systems  

SciTech Connect

Every year the US mining industry spends millions of dollars on underground ventilation systems. Potential motor-driven system energy savings can be realized by using mature, proven, and cost-effective technologies. Improved energy efficiency also leads to reduced environmental emissions. This paper promotes a systems approach to increase the energy efficiency in mine ventilation.

Papar, Riyaz; Szady, A.; Huffer, W.D.; Martin V.; McKane, A.T.

1999-06-01

332

Preoperational test report, primary ventilation system  

SciTech Connect

This represents a preoperational test report for Primary Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides vapor space filtered venting of tanks AY101, AY102, AZ101, AZ102. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

Clifton, F.T.

1997-11-04

333

46 CFR 194.10-25 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...inch mesh. Metal watertight closures shall be provided for use when the ventilation system is not in operation. A 2-inch IPS bypass with check valve shall be provided in parallel with at least one of the ventilation closures to prevent pressure...

2009-10-01

334

46 CFR 194.10-25 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...inch mesh. Metal watertight closures shall be provided for use when the ventilation system is not in operation. A 2-inch IPS bypass with check valve shall be provided in parallel with at least one of the ventilation closures to prevent pressure...

2013-10-01

335

Spontaneous breathing during mechanical ventilation in ARDS  

Microsoft Academic Search

The objective of mechanical ventilation used in the management of Acute Respiratory Distress Syn- drome (ARDS) is to ensure adequate tissue oxygen- ation and alveolar ventilation while limiting the pa- tients' work of breathing and preventing further dam- age to the lungs. Although the \\

Ross Freebairn; Keith Hickling

2005-01-01

336

Update on modalities of mechanical ventilators  

Microsoft Academic Search

Recent advances in ventilator technology have often not been confirmed by randomised trials and instead serious shortcomings have been highlighted. Ventilation modes should only be introduced into routine clinical practice when proved efficacious in appropriately designed studies and no adverse outcomes identified by long term follow up.

A Greenough

2002-01-01

337

Development of Two Types of Ventilators.  

National Technical Information Service (NTIS)

The objective of this program was to evaluate two types of ventilator kits for maximum cost effectiveness. The kits shown on the following page are: (1) Pedal Ventilator Kit, and (2) the Kearny Pump Kit. The two units were previously developed by GARD in ...

J. M. Buday R. J. Klima

1979-01-01

338

Characterization and measurement of ventilator performance  

NASA Astrophysics Data System (ADS)

The work of the ISO in drawing up ventilator norms is reviewed, and the scientific and technical difficulties encountered when investigating ventilators are summarized. Difficulties arise from the many forms of energy transfered to the fluid, the diversity of gases used, compressibility effects, the wide variety of equipment size and performance, the different functions required, and the heterogeneity of test methods.

Judetlelacombe, A.

339

Assisted ventilation in severe acute asthma  

Microsoft Academic Search

During the period 1973-85 assisted ventilation was used for the treatment of severe asthma on 48 occasions in 18 patients (one patient was ventilated 29 times). On each occasion arterial blood gas abnormalities were restored to normal as quickly as possible irrespective of peak inflation pressures. One patient was thought to be brain dead on transfer from another hospital but

B Higgins; A P Greening; G K Crompton

1986-01-01

340

Sensor-based demand controlled ventilation.  

National Technical Information Service (NTIS)

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pol...

A. T. De Almeida W. J. Fisk

1997-01-01

341

The basics of industrial ventilation design  

Microsoft Academic Search

HVAC in the industrial environment assumes many roles from general ventilation to process related applications. Because of the variety of applications and the documentation available for the design of each, it is not the intent of this article to review each one. However, industrial clients often have misconceptions that lead to misapplications of ventilation design and equipment. One of the

1996-01-01

342

Insulin degradation products from perfused rat kidney  

Microsoft Academic Search

The kidney is a major site for insulin metabolism, but the enzymes involved and the products generated have not been established. To examine the products, we have perfused rat kidneys with insulin specifically iodinated on either the A14 or the B26 tyrosine. Labeled material from both the perfusate and kidney extract was examined by Sephadex G50 and high-performance liquid chromatography

W. C. Duckworth; F. G. Hamel; J. Liepnieks; D. Peavy; B. Frank; R. Rabkin

1989-01-01

343

Vicarious audiovisual learning in perfusion education.  

PubMed

Perfusion technology is a mechanical and visual science traditionally taught with didactic instruction combined with clinical experience. It is difficult to provide perfusion students the opportunity to experience difficult clinical situations, set up complex perfusion equipment, or observe corrective measures taken during catastrophic events because of patient safety concerns. Although high fidelity simulators offer exciting opportunities for future perfusion training, we explore the use of a less costly low fidelity form of simulation instruction, vicarious audiovisual learning. Two low fidelity modes of instruction; description with text and a vicarious, first person audiovisual production depicting the same content were compared. Students (n = 37) sampled from five North American perfusion schools were prospectively randomized to one of two online learning modules, text or video.These modules described the setup and operation of the MAQUET ROTAFLOW stand-alone centrifugal console and pump. Using a 10 question multiple-choice test, students were assessed immediately after viewing the module (test #1) and then again 2 weeks later (test #2) to determine cognition and recall of the module content. In addition, students completed a questionnaire assessing the learning preferences of today's perfusion student. Mean test scores from test #1 for video learners (n = 18) were significantly higher (88.89%) than for text learners (n = 19) (74.74%), (p < .05). The same was true for test #2 where video learners (n = 10) had an average score of 77% while text learners (n = 9) scored 60% (p < .05). Survey results indicated video learners were more satisfied with their learning module than text learners. Vicarious audiovisual learning modules may be an efficacious, low cost means of delivering perfusion training on subjects such as equipment setup and operation. Video learning appears to improve cognition and retention of learned content and may play an important role in how we teach perfusion in the future, as simulation technology becomes more prevalent. PMID:21313929

Rath, Thomas E; Holt, David W

2010-12-01

344

Improved exercise myocardial perfusion during lidoflazine therapy  

SciTech Connect

Lidoflazine is a synthetic drug with calcium-channel blocking effects. In a study of 6 patients with severe classic angina pectoris, single-blind administration of lidoflazine was associated with improved myocardial perfusion during exercise as determined by thallium-201 stress scintigraphy. These studies demonstrate that lidoflazine therapy is associated with relief of angina, an increased physical work capacity, and improved regional myocardial perfusion during exercise.

Shapiro, W.; Narahara, K.A.; Park, J.

1983-11-01

345

Mine ventilation and air conditioning. 3. edition  

SciTech Connect

This revised edition presents an engineering design approach to ventilation and air conditioning as part of the comprehensive environmental control of the mine atmosphere. It provides an in-depth look, for practitioners who design and operate mines, into the health and safety aspects of environmental conditions in the underground workplace. The contents include: Environmental control of the mine atmosphere; Properties and behavior of air; Mine air-quality control; Mine gases; Dusts and other mine aerosols; Mine ventilation; Airflow through mine openings and ducts; Mine ventilation circuits and networks; Natural ventilation; Fan application to mines; Auxiliary ventilation and controlled recirculation; Economics of airflow; Control of mine fires and explosions; Mine air conditioning; Heat sources and effect in mines; Mine air conditioning systems; Appendices; References; Answers to selected problems; and Index.

Hartman, H.L. [Univ. of Alabama, University, AL (United States); Mutmansky, J.M.; Ramani, R.V. [Pennsylvania State Univ., University Park, PA (United States); Wang, Y.J. [West Virginia Univ., Morgantown, WV (United States)

1998-12-31

346

The basics of industrial ventilation design  

SciTech Connect

HVAC in the industrial environment assumes many roles from general ventilation to process related applications. Because of the variety of applications and the documentation available for the design of each, it is not the intent of this article to review each one. However, industrial clients often have misconceptions that lead to misapplications of ventilation design and equipment. One of the more common misconceptions is that ventilation equipment should be sized based on volumetric air changes, regardless of the application. This article will review a generalized approach to ventilation calculations, the fallacy of air changes, and the role of HVAC engineers to provide the industrial client a properly applied ventilation design and thorough knowledge of its operational parameters.

Parks, R.L. [McKim and Creed, Raleigh, NC (United States)

1996-11-01

347

Insulin degradation products from perfused rat kidney  

SciTech Connect

The kidney is a major site for insulin metabolism, but the enzymes involved and the products generated have not been established. To examine the products, we have perfused rat kidneys with insulin specifically iodinated on either the A14 or the B26 tyrosine. Labeled material from both the perfusate and kidney extract was examined by Sephadex G50 and high-performance liquid chromatography (HPLC). In perfusate from a filtering kidney, 22% of the insulin-sized material was not intact insulin on HPLC. With the nonfiltering kidney, 10.6% was not intact insulin. Labeled material from HPLC was sulfitolyzed and reinjected on HPLC. By use of /sup 125/I-iodo(A14)-insulin, almost all the degradation products contained an intact A-chain. By use of /sup 125/I-iodo(B26)-insulin, several different B-chain-cleaved products were obtained. The material extracted from the perfused kidney was different from perfusate products but similar to intracellular products from hepatocytes, suggesting that cellular metabolism by kidney and liver are similar. The major intracellular product had characteristics consistent with a cleavage between the B16 and B17 amino acids. This product and several of the perfusate products are also produced by insulin protease suggesting that this enzyme is involved in the degradation of insulin by kidney.

Duckworth, W.C.; Hamel, F.G.; Liepnieks, J.; Peavy, D.; Frank, B.; Rabkin, R.

1989-02-01

348

Insulin degradation products from perfused rat kidney.  

PubMed

The kidney is a major site for insulin metabolism, but the enzymes involved and the products generated have not been established. To examine the products, we have perfused rat kidneys with insulin specifically iodinated on either the A14 or the B26 tyrosine. Labeled material from both the perfusate and kidney extract was examined by Sephadex G50 and high-performance liquid chromatography (HPLC). In perfusate from a filtering kidney, 22% of the insulin-sized material was not intact insulin on HPLC. With the nonfiltering kidney, 10.6% was not intact insulin. Labeled material from HPLC was sulfitolyzed and reinjected on HPLC. By use of 125I-iodo(A14)-insulin, almost all the degradation products contained an intact A-chain. By use of 125I-iodo(B26)-insulin, several different B-chain-cleaved products were obtained. The material extracted from the perfused kidney was different from perfusate products but similar to intracellular products from hepatocytes, suggesting that cellular metabolism by kidney and liver are similar. The major intracellular product had characteristics consistent with a cleavage between the B16 and B17 amino acids. This product and several of the perfusate products are also produced by insulin protease suggesting that this enzyme is involved in the degradation of insulin by kidney. PMID:2645781

Duckworth, W C; Hamel, F G; Liepnieks, J; Peavy, D; Frank, B; Rabkin, R

1989-02-01

349

Perfusion visualization and analysis for pulmonary embolism  

NASA Astrophysics Data System (ADS)

Given the nature of pulmonary embolism (PE), timely and accurate diagnosis is critical. Contrast enhanced high-resolution CT images allow physicians to accurately identify segmental and sub-segmental emboli. However, it is also important to assess the effect of such emboli on the blood flow in the lungs. Expanding upon previous research, we propose a method for 3D visualization of lung perfusion. The proposed method allows users to examine perfusion throughout the entire lung volume at a single glance, with areas of diminished perfusion highlighted so that they are visible independent of the viewing location. This may be particularly valuable for better accuracy in assessing the extent of hemodynamic alterations resulting from pulmonary emboli. The method also facilitates user interaction and may help identify small peripheral sub-segmental emboli otherwise overlooked. 19 patients referred for possible PE were evaluated by CT following the administration of IV contrast media. An experienced thoracic radiologist assessed the 19 datasets with 17 diagnosed as being positive for PE with multiple emboli. Since anomalies in lung perfusion due to PE can alter the distribution of parenchymal densities, we analyzed features collected from histograms of the computed perfusion maps and demonstrate their potential usefulness as a preliminary test to suggest the presence of PE. These histogram features also offer the possibility of distinguishing distinct patterns associated with chronic PE and may even be useful for further characterization of changes in perfusion or overall density resulting from associated conditions such as pneumonia or diffuse lung disease.

Vaz, Michael S.; Kiraly, Atilla P.; Naidich, David P.; Novak, Carol L.

2005-04-01

350

The effect of CO sub 2 on pulmonary artery pressure (P sub pa ) over time in the isolated perfused rabbit lung  

SciTech Connect

The isolated perfused rabbit lung model is used in studies of pulmonary hemodynamics, structure, and function under conditions closely resembling those which occur in living animals. The purpose of this study is to observe changes in P{sub pa} in response to differing concentrations of CO{sub 2} over time. After rapid exsanguination a tracheostomy was performed. Cannulas were secured in the main pulmonary artery and the left atrium. The lungs were perfused with Krebs-Henseleit buffer mixed with blood at a rate of 120 ml/min with recirculation. The temperature of the perfusate was maintained between 35 and 38C. The lungs were then ventilated with 5% CO{sub 2} in air with a tidal volume of 10 ml/kg at 20 breaths/min. CO{sub 2} was altered randomly by ventilating the lungs 2, 5 or 10% CO{sub 2} in air. Metabolic acidosis was corrected with NaHCO{sub 3}. In the first two hour period after lung perfusion was begun, the model was allowed to stabilize at each CO{sub 2} concentration, and pH, pCO{sub 2}, pO{sub 2}, and base excess were determined at each P{sub pa}. All measurements were repeated in the second period beginning two hours after lung perfusion was started. P{sub pa} was plotted against pH for each animal in both early and late phases, and simple regression analysis was performed. The slopes and the y intercepts for the data sets in both groups were compared using one factor ANOVA, and were found to be significantly different, implying a statistical difference between regression lines. In the early phase this model behaves like the in vivo lung, i.e. hypercarbia appears to increase, while hypocarbia decreases, P{sub pa}. During the late phase of lung perfusion the opposite occurs.

Reynolds, P.; Shayevitz, J. (Univ. of Michigan, Ann Arbor (United States))

1991-03-11

351

Effects of ventilation strategy on distribution of lung inflammatory cell activity  

PubMed Central

Introduction Leukocyte infiltration is central to the development of acute lung injury, but it is not known how mechanical ventilation strategy alters the distribution or activation of inflammatory cells. We explored how protective (vs. injurious) ventilation alters the magnitude and distribution of lung leukocyte activation following systemic endotoxin administration. Methods Anesthetized sheep received intravenous endotoxin (10 ng/kg/min) followed by 2 h of either injurious or protective mechanical ventilation (n = 6 per group). We used positron emission tomography to obtain images of regional perfusion and shunting with infused 13N[nitrogen]-saline and images of neutrophilic inflammation with 18F-fluorodeoxyglucose (18F-FDG). The Sokoloff model was used to quantify 18F-FDG uptake (Ki), as well as its components: the phosphorylation rate (k3, a surrogate of hexokinase activity) and the distribution volume of 18F-FDG (Fe) as a fraction of lung volume (Ki = Fe × k3). Regional gas fractions (fgas) were assessed by examining transmission scans. Results Before endotoxin administration, protective (vs. injurious) ventilation was associated with a higher ratio of partial pressure of oxygen in arterial blood to fraction of inspired oxygen (PaO2/FiO2) (351 ± 117 vs. 255 ± 74 mmHg; P < 0.01) and higher whole-lung fgas (0.71 ± 0.12 vs. 0.48 ± 0.08; P = 0.004), as well as, in dependent regions, lower shunt fractions. Following 2 h of endotoxemia, PaO2/FiO2 ratios decreased in both groups, but more so with injurious ventilation, which also increased the shunt fraction in dependent lung. Protective ventilation resulted in less nonaerated lung (20-fold; P < 0.01) and more normally aerated lung (14-fold; P < 0.01). Ki was lower during protective (vs. injurious) ventilation, especially in dependent lung regions (0.0075 ± 0.0043/min vs. 0.0157 ± 0.0072/min; P < 0.01). 18F-FDG phosphorylation rate (k3) was twofold higher with injurious ventilation and accounted for most of the between-group difference in Ki. Dependent regions of the protective ventilation group exhibited lower k3 values per neutrophil than those in the injurious ventilation group (P = 0.01). In contrast, Fe was not affected by ventilation strategy (P = 0.52). Lung neutrophil counts were not different between groups, even when regional inflation was accounted for. Conclusions During systemic endotoxemia, protective ventilation may reduce the magnitude and heterogeneity of pulmonary inflammatory cell metabolic activity in early lung injury and may improve gas exchange through its effects predominantly in dependent lung regions. Such effects are likely related to a reduction in the metabolic activity, but not in the number, of lung-infiltrating neutrophils.

2013-01-01

352

Venular valves and retrograde perfusion.  

PubMed

Forced retrograde perfusion through the venous system with arterial blood can provide adequate oxygen to peripheral tissues at rest through veno-capillary networks which is the basis for surgical restoration of blood flow by distal vein arterialization (DVA). To be successful such surgery requires disruption of valve leaflets in the veins, which can be accomplished easily in the larger vessels. However, the smallest veins (venules) of less than 100 ?m in diameter, also possess valves, are distributed widely throughout all tissues and are too fine for any effective surgical interference. Thus venular valves cannot be disrupted or dissected with presently available technology. Nevertheless, clinical observations suggest that retrograde peripheral blood flow is rapidly established after DVA surgery. There is as yet no rational explanation for this phenomenon. In the present study, using Laplace's law, we attempt to elucidate the mechanical properties of venules and their valves. We speculate that the remarkably thin venular walls (and especially those of the smaller vessels which have the thinnest walls), are capable of considerable, rapid distension when subjected to increased hemostatic pressure. The increase in diameter of venules in response to the increased blood pressure renders their valve leaflets incompetent, so that the valves themselves cannot close the vessel lumen. In addition, the thin bicuspid leaflets may also be forced open retrogradely by the increased blood pressure. PMID:24729249

Koyama, Tomiyasu; Sugihara-Seki, Masako; Sasajima, Tadahiro; Kikuchi, Sinsuke

2014-01-01

353

Pulmonary Perfusion and Xenon Gas Exchange in Rats: MR Imaging with Intravenous Injection of Hyperpolarized 129Xe1  

PubMed Central

Purpose: To develop and demonstrate a method for regional evaluation of pulmonary perfusion and gas exchange based on intravenous injection of hyperpolarized xenon 129 (129Xe) and subsequent magnetic resonance (MR) imaging of the gas-phase 129Xe emerging in the alveolar airspaces. Materials and Methods: Five Fischer 344 rats that weighed 200—425 g were prepared for imaging according to an institutional animal care and use committee—approved protocol. Rats were ventilated, and a 3-F catheter was placed in the jugular (n = 1) or a 24-gauge catheter in the tail (n = 4) vein. Imaging and spectroscopy of gas-phase 129Xe were performed after injecting 5 mL of half-normal saline saturated with 129Xe hyperpolarized to 12%. Corresponding ventilation images were obtained during conventional inhalation delivery of hyperpolarized 129Xe. Results: Injections of 129Xe-saturated saline were well tolerated and produced a strong gas-phase 129Xe signal in the airspaces that resulted from 129Xe transport through the pulmonary circulation and diffusion across the blood-gas barrier. After a single injection, the emerging 129Xe gas could be detected separately from 129Xe remaining in the blood and was imaged with an in-plane resolution of 1 × 1 mm and a signal-to-noise ratio of 25. Images in one rat revealed a matched ventilation-perfusion deficit, while images in another rat showed that xenon gas exchange was temporarily impaired after saline overload, with recovery of function 1 hour later. Conclusion: MR imaging of gas-phase 129Xe emerging in the pulmonary airspaces after intravenous injection has the potential to become a sensitive and minimally invasive new tool for regional evaluation of pulmonary perfusion and gas exchange. Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/2513081550/DC1

Driehuys, Bastiaan; Moller, Harald E.; Cleveland, Zackary I.; Pollaro, James; Hedlund, Laurence W.

2009-01-01

354

In Vivo MR Imaging of Pulmonary Perfusion and Gas Exchange in Rats via Continuous Extracorporeal Infusion of Hyperpolarized 129Xe  

PubMed Central

Background Hyperpolarized (HP) 129Xe magnetic resonance imaging (MRI) permits high resolution, regional visualization of pulmonary ventilation. Additionally, its reasonably high solubility (>10%) and large chemical shift range (>200 ppm) in tissues allow HP 129Xe to serve as a regional probe of pulmonary perfusion and gas transport, when introduced directly into the vasculature. In earlier work, vascular delivery was accomplished in rats by first dissolving HP 129Xe in a biologically compatible carrier solution, injecting the solution into the vasculature, and then detecting HP 129Xe as it emerged into the alveolar airspaces. Although easily implemented, this approach was constrained by the tolerable injection volume and the duration of the HP 129Xe signal. Methods and Principal Findings Here, we overcome the volume and temporal constraints imposed by injection, by using hydrophobic, microporous, gas-exchange membranes to directly and continuously infuse 129Xe into the arterial blood of live rats with an extracorporeal (EC) circuit. The resulting gas-phase 129Xe signal is sufficient to generate diffusive gas exchange- and pulmonary perfusion-dependent, 3D MR images with a nominal resolution of 2×2×2 mm3. We also show that the 129Xe signal dynamics during EC infusion are well described by an analytical model that incorporates both mass transport into the blood and longitudinal relaxation. Conclusions Extracorporeal infusion of HP 129Xe enables rapid, 3D MR imaging of rat lungs and, when combined with ventilation imaging, will permit spatially resolved studies of the ventilation-perfusion ratio in small animals. Moreover, EC infusion should allow 129Xe to be delivered elsewhere in the body and make possible functional and molecular imaging approaches that are currently not feasible using inhaled HP 129Xe.

Cleveland, Zackary I.; Moller, Harald E.; Hedlund, Laurence W.; Nouls, John C.; Freeman, Matthew S.; Qi, Yi; Driehuys, Bastiaan

2012-01-01

355

Quantitative assessment of acute kidney injury by noninvasive arterial spin labeling perfusion MRI: a pilot study.  

PubMed

The kidneys are essential for maintaining homeostasis, are responsible for the reabsorption of water, glucose and amino acids, and filter the blood by removing waste. Acute kidney injury (AKI) is a syndrome characterized by the rapid loss of renal excretory function and the accumulation of end metabolic products of urea and creatinine. AKI is associated with the later development of chronic kidney disease and end-stage kidney disease, and may eventually be fatal. Early diagnosis of AKI and assessments of the effects of treatment, however, are challenging. The pathophysiological mechanism of AKI is thought to be the imbalance between oxygen supply and demand in the kidneys. We have assessed the ability of arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI), without the administration of contrast media, to quantify renal blood flow (RBF) non-invasively. We found that RBF was significantly lower in AKI patients than in healthy volunteers. These results suggest that ASL perfusion MRI, a noninvasive measurement of RBF, may be useful in the early diagnosis of AKI. PMID:23740361

Dong, Jian; Yang, Li; Su, Tao; Yang, XueDong; Chen, Bin; Zhang, Jue; Wang, XiaoYing; Jiang, XueXiang

2013-08-01

356

Assessment of infantile mineral imbalances in autism spectrum disorders (ASDs).  

PubMed

The interactions between genes and the environment are now regarded as the most probable explanation for autism. In this review, we summarize the results of a metallomics study in which scalp hair concentrations of 26 trace elements were examined for 1,967 autistic children (1,553 males and 414 females aged 0-15 years-old), and discuss recent advances in our understanding of epigenetic roles of infantile mineral imbalances in the pathogenesis of autism. In the 1,967 subjects, 584 (29.7%) and 347 (17.6%) were found deficient in zinc and magnesium, respectively, and the incidence rate of zinc deficiency was estimated at 43.5% in male and 52.5% in female infantile subjects aged 0-3 years-old. In contrast, 339 (17.2%), 168 (8.5%) and 94 (4.8%) individuals were found to suffer from high burdens of aluminum, cadmium and lead, respectively, and 2.8% or less from mercury and arsenic. High toxic metal burdens were more frequently observed in the infants aged 0-3 years-old, whose incidence rates were 20.6%, 12.1%, 7.5%, 3.2% and 2.3% for aluminum, cadmium, lead, arsenic and mercury, respectively. These findings suggest that infantile zinc- and magnesium-deficiency and/or toxic metal burdens may be critical and induce epigenetic alterations in the genes and genetic regulation mechanisms of neurodevelopment in the autistic children, and demonstrate that a time factor "infantile window" is also critical for neurodevelopment and probably for therapy. Thus, early metallomics analysis may lead to early screening/estimation and treatment/prevention for the autistic neurodevelopment disorders. PMID:24284360

Yasuda, Hiroshi; Tsutsui, Toyoharu

2013-11-01

357

[Introspection of oxidant/antioxidant imbalance in the inner ear].  

PubMed

Free radicals are atoms, molecules or ions with unpaired electrons. In biological systems, free radicals can have a dual role, being beneficial in some situations and deleterious in others. Free radicals are required for normal cellular metabolism, but they lead to cellular degeneration if overproduced. To prevent the excessive buildup of free radicals, cells have developed an elaborate series of antioxidant enzymes that counteract oxidative stress and protect cells by maintaining the proper balance of oxidation and anti-oxidation. Therefore, when there is an oxidant/anti-oxidant imbalance, no matter what direction, cells are likely to be damaged. Numerous reports in the literature indicate that free radicals play important roles in diseases of the inner ear as a result of noise exposure, ototoxic drugs, aging, and other pathological conditions. Therefore, there have been many attempts to employ antioxidants treat inner ear damage. However, antioxidant therapy could be harmful if the improper compound or dose is employed. Effective antioxidant therapy requires prior knowledge of the type(s) of oxidative stress occurring in real time in the inner ear. Since most techniques for detecting free radicals in the inner ear are not clinically feasible, systemic anti-oxidant therapy is generally performed "blindly" and therefore likely to disrupt normal antioxidant levels in the inner ear or elsewhere in the body. If only a single anti-oxidant is used to treat a disease, it may disturb subsequent steps the oxidative/anti-oxidative chain reaction. An alternative approach, hydrogen therapy represents a promising therapeutic tool because it can selectively scavenge the strongest oxidant species, the hydroxyl radical and peroxynitrite anion, without disturbing normal oxidant/anti-oxidant cellular processes. In addition, hydrogen has no cytotoxic effects to cells so that it provides a near ideal therapy to eliminate toxic free radicals. PMID:24358804

Wang, Lu; Ding, Dalian; Sun, Hong

2013-09-01

358

Copper imbalances in ruminants and humans: unexpected common ground.  

PubMed

Ruminants are more vulnerable to copper deficiency than humans because rumen sulfide generation lowers copper availability from forage, increasing the risk of conditions such as swayback in lambs. Molybdenum-rich pastures promote thiomolybdate (TM) synthesis and formation of unabsorbable Cu-TM complexes, turning risk to clinical reality (hypocuprosis). Selection pressures created ruminant species with tolerance of deficiency but vulnerability to copper toxicity in alien environments, such as specific pathogen-free units. By contrast, cases of copper imbalance in humans seemed confined to rare genetic aberrations of copper metabolism. Recent descriptions of human swayback and the exploratory use of TM for the treatment of Wilson's disease, tumor growth, inflammatory diseases, and Alzheimer's disease have created unexpected common ground. The incidence of pre-hemolytic copper poisoning in specific pathogen-free lambs was reduced by an infection with Mycobacterium avium that left them more responsive to treatment with TM but vulnerable to long-term copper depletion. Copper requirements in ruminants and humans may need an extra allowance for the "copper cost" of immunity to infection. Residual cuproenzyme inhibition in TM-treated lambs and anomalies in plasma copper composition that appeared to depend on liver copper status raise this question "can chelating capacity be harnessed without inducing copper-deficiency in ruminants or humans?" A model of equilibria between exogenous (TM) and endogenous chelators (e.g., albumin, metallothionein) is used to predict risk of exposure and hypocuprosis; although risk of natural exposure in humans is remote, vulnerability to TM-induced copper deficiency may be high. Biomarkers of TM impact are needed, and copper chaperones for inhibited cuproenzymes are prime candidates. PMID:22983845

Suttle, Neville F

2012-01-01

359

High-frequency perfusion fluorometry: a new technique to assess bronchial mucosa blood perfusion  

NASA Astrophysics Data System (ADS)

A new method to estimate airway mucosa blood perfusion is proposed based on the fluorescein perfusion fluorometry principles, which allows both high temporal resolution and high sensitivity measurements to be performed. Preliminary results were obtained on different conditions of rat trachea vascularization, which provide interesting perspectives for an application to the bronchial ischemia problems in lung transplantation.

Bottiroli, Giovanni F.; Ramponi, Roberta; Croce, Anna C.; Rescigno, Giuseppe; Nazari, Stefano; Zonta, Aris

1992-05-01

360

Codigestion of manure and industrial organic waste at centralized biogas plants: process imbalances and limitations.  

PubMed

The present study focuses on process imbalances in Danish centralized biogas plants treating manure in combination with industrial waste. Collection of process data from various full-scale plants along with a number of interviews showed that imbalances occur frequently. High concentrations of ammonia or long chain fatty acids is in most cases expected to be the cause of microbial inhibitions/imbalances while foaming in the prestorage tanks and digesters is the most important practical process problem at the plants. A correlation between increased residual biogas production (suboptimal process conditions) and high fractions of industrial waste in the feedstock was also observed. The process imbalances and suboptimal conditions are mainly allowed to occur due to 1) inadequate knowledge about the waste composition, 2) inadequate knowledge about the waste degradation characteristics, 3) inadequate process surveillance, especially with regard to volatile fatty acids, and 4) insufficient pre-storage capacity causing inexpedient mixing and hindering exact dosing of the different waste products. PMID:18957768

Nielsen, H B; Angelidaki, I

2008-01-01

361

Reverse knowledge and technology transfer: imbalances caused by cognitive barriers in asymmetric relationships  

Microsoft Academic Search

An imbalance exists in almost any type of knowledge and technology transfer due to the information asymmetry of the relationship. However, this is especially the case for reverse technology and knowledge transfer which is epitomised for us by \\

Carla C. J. M. Millar; Chong Ju Choi

2009-01-01

362

Optimization on Emergency Longitudinal Ventilation Design  

NASA Astrophysics Data System (ADS)

Emergency ventilation design in longitudinally ventilated vehicular tunnels is vital to provide safe egress route for tunnel user under fire situations. In this study, the influences of the location of active fan groups on the upstream velocity are investigated using Computational Fluid Dynamics (CFD) techniques. The numeric model was firstly validated again the experimental data from Memorial Tunnel Fire Ventilation Test Program (MTFVTP). Based on the validated model, parametric studies were then preformed attempting to establish a semi-empirical correlation between the location of fan groups and the upstream velocity. In the presence of solid fire, it was found that the buoyant force by the fire source and inertial force by the fans interact with each other and resulted in a ``leveling-off'' characteristic when the inertial force is no longer dominating. Such interaction re-distributed the ventilation flow direction and sequentially reduces the magnitude of the upstream velocity. In other word, the industrial practice of activating furthest fan group may not be able to prevent the backlayering as a consequence of solid fires. Fans closer to the fire source are recommended to be activated for preventing the hazard of backlayering. Furthermore, through the parametric study, location of ventilation fans is found to have significant effect on the upstream velocity. Such finding suggests that other geometrical parameters could also impose adverse effects to the ventilation system. Existing empirical equation could be insufficient to cover all possible ventilation design scenarios.

Se, Camby M. K.; Yuen, Richard K. K.; Cheung, Sherman C. P.; Tu, Jiyuan

2010-05-01

363

GPU-accelerated voxelwise hepatic perfusion quantification  

NASA Astrophysics Data System (ADS)

Voxelwise quantification of hepatic perfusion parameters from dynamic contrast enhanced (DCE) imaging greatly contributes to assessment of liver function in response to radiation therapy. However, the efficiency of the estimation of hepatic perfusion parameters voxel-by-voxel in the whole liver using a dual-input single-compartment model requires substantial improvement for routine clinical applications. In this paper, we utilize the parallel computation power of a graphics processing unit (GPU) to accelerate the computation, while maintaining the same accuracy as the conventional method. Using compute unified device architecture-GPU, the hepatic perfusion computations over multiple voxels are run across the GPU blocks concurrently but independently. At each voxel, nonlinear least-squares fitting the time series of the liver DCE data to the compartmental model is distributed to multiple threads in a block, and the computations of different time points are performed simultaneously and synchronically. An efficient fast Fourier transform in a block is also developed for the convolution computation in the model. The GPU computations of the voxel-by-voxel hepatic perfusion images are compared with ones by the CPU using the simulated DCE data and the experimental DCE MR images from patients. The computation speed is improved by 30 times using a NVIDIA Tesla C2050 GPU compared to a 2.67 GHz Intel Xeon CPU processor. To obtain liver perfusion maps with 626 400 voxels in a patient's liver, it takes 0.9 min with the GPU-accelerated voxelwise computation, compared to 110 min with the CPU, while both methods result in perfusion parameters differences less than 10-6. The method will be useful for generating liver perfusion images in clinical settings.

Wang, H.; Cao, Y.

2012-09-01

364

Examination of Potential Benefits of an Energy Imbalance Market in the Western Interconnection  

SciTech Connect

In the Western Interconnection, there is significant interest in improving approaches to wide-area coordinated operations of the bulk electric power system, in part because of the increasing penetration of variable generation. One proposed solution is an energy imbalance market. This study focused on that approach alone, with the goal of identifying the potential benefits of an energy imbalance market in the year 2020.

Milligan, M.; Clark, K.; King, J.; Kirby, B.; Guo, T.; Liu, G.

2013-03-01

365

A Model-based estimator of engine cylinder pressure imbalance for combustion feedback control applications  

Microsoft Academic Search

One of the principal issues of low-temperature combustion modes is caused by the imbalances in the dis- tribution of air and EGR across the cylinders, which affects the combustion process. Cylinder to cylinder variations lead to imbalances in the cylinder pressure, indicated torque, exhaust gas thermodynamic conditions and emissions. In principle, a cylinder-by-cylinder control approach could compensate for air, residuals

Ahmed Al-Durra; Lisa Fiorentini; Marcello Canova; Stephen Yurkovich

2011-01-01

366

Prism adaptation to rightward optical deviation improves postural imbalance in left-hemiparetic patients  

Microsoft Academic Search

Left-hemiparetic patients show predominant postural imbalance as compared to right-hemiparetic patients. The right hemisphere is crucial for generating internal maps used for perceptual and premotor processing of spatial information. Predominant postural imbalance with right-brain damage could thus result from a distortion of an internal postural map. Well-known manifestations of distorted internal maps due to right-hemisphere lesions, such as hemineglect, may

Caroline Tilikete; Gilles Rode; Yves Rossetti; Jacques Pichon; Ling Li; Dominique Boisson

2001-01-01

367

Characteristics of coal mine ventilation air flows.  

PubMed

Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. Underground coal mining is by far the most important source of fugitive methane emissions, and approximately 70% of all coal mining related methane is emitted to the atmosphere through mine ventilation air. Therefore, research and development on mine methane mitigation and utilisation now focuses on methane emitted from underground coal mines, in particular ventilation air methane (VAM) capture and utilisation. To date, most work has focused on the oxidation of very low concentration methane. These processes may be classified based on their combustion kinetic mechanisms into thermal oxidation and catalytic oxidation. VAM mitigation/utilisation technologies are generally divided into two basic categories: ancillary uses and principal uses. However, it is possible that the characteristics of ventilation air flows, for example the variations in methane concentration and the presence of certain compounds, which have not been reported so far, could make some potential VAM mitigation and utilisation technologies unfeasible if they cannot cope with the characteristics of mine site ventilation air flows. Therefore, it is important to understand the characteristics of mine ventilation air flows. Moreover, dust, hydrogen sulphide, sulphur dioxide, and other possible compounds emitted through mine ventilation air into the atmosphere are also pollutants. Therefore, this paper presents mine-site experimental results on the characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size, mineral matter of the dust, and other compounds in the ventilation air flows. The paper also discusses possible correlations between ventilation air characteristics and underground mining activities. PMID:17239518

Su, Shi; Chen, Hongwei; Teakle, Philip; Xue, Sheng

2008-01-01

368

The Relation Between Perfusion Pattern of Hepatic Artery Perfusion Scintigraphy and Response to Y-90 Microsphere Therapy  

PubMed Central

Objective: Hepatic artery perfusion scintigraphy is a routine procedure for patient evaluation before Y-90 radiomicrosphere therapy and mostly used for prediction of extrahepatic leakage. Moreover, it also displays perfusion pattern of tumours, which is an important parameter on success of the therapy. The aim of this study is to assess the relation between the perfusion pattern on hepatic artery perfusion scintigraphy and radiomicrosphere therapy response. Methods: A total of 99 radiomicrosphere therapy applications were carried out in 80 patients (M/F: 55/25). Results: Heterogeneous and diffuse perfusion patterns were observed in 47 patients and 52 patients, respectively. The patients with diffuse perfusion pattern had better therapy response both on FDG PET/CT (p= 0.04) and CT (p=0.008) when compared to those with heterogenous perfusion pattern. Conclusion: Perfusion pattern observed on hepatic artery perfusion scintigraphy may be a successful predictor of early response to radiomicrosphere therapy. Conflict of interest:None declared.

Volkan-Salanc?, Bilge; Bozkurt, Murat Fani; Peynircioglu, Bora; Cil, Barbaros; Ugur, Omer

2013-01-01

369

Neonatal ventilators: how do they differ?  

PubMed

Remarkable technological advances over the past two decades have brought dramatic changes to the neonatal intensive care unit. Microprocessor-based mechanical ventilation has replaced time-cycled, pressure-limited, intermittent mandatory ventilation with almost limitless options for the management of respiratory failure in the prematurely born infant. Unfortunately, much of the infusion of technology occurred before the establishment of a convincing evidence base. This review focuses on the basic principles of mechanical ventilation, nomenclature and the characteristics of both conventional and high-frequency devices. PMID:19399015

Donn, S M

2009-05-01

370

Differences in regional myocardial perfusion, metabolism, MVO2, and edema after coronary sinus machine perfusion preservation of canine hearts.  

PubMed

Machine perfusion improves solid organ preservation for transplantation. We have demonstrated that antegrade perfusion preservation of hearts is superior to cold storage but may be limited by aortic valve incompetence. We hypothesized that retrograde perfusion (RP) through the coronary sinus may provide more reliable perfusate delivery to the heart. This study was designed to determine the optimal perfusion parameters and evaluate regional flow after RP of canine hearts. After donor cardiectomy, canine hearts (n = 6) were established in a perfusion device (LifeCradle, Organ Transport Systems, Inc., Frisco, TX) through a coronary sinus catheter. Hearts were perfused at 5°C over flow rates from 10 to 35 ml/100 g myocardium/min for 20 minutes at each flow rate. Colored microspheres were used to quantify tissue perfusion. Oxygen consumption (MVO(2)) and perfusion parameters were measured. At end-perfusion, tissue was collected for proton magnetic resonance spectroscopy ((1)H MRS), microsphere analysis, and determination of myocardial edema. MVO(2) increased up to flow rates of 20 ml/100 g/min. Right ventricular (RV) perfusion was reduced at all flow rates. Increased lactate/alanine ratios by (1)H MRS and reduced myocardial water content were noted in RV samples. RP results in excellent left ventricular (LV) perfusion. RV perfusion is reduced and oxidative metabolism in the right ventricle may not be maintained by RP. Further studies to evaluate effects of reduced RV perfusion by RP on functional recovery after transplantation are warranted. PMID:22036719

Cobert, Michael L; Merritt, Matthew E; West, LaShondra M; Jessen, Michael E; Peltz, Matthias

2011-01-01

371

Effect of oral high frequency ventilation by jet or oscillator on minute ventilation in normal subjects.  

PubMed Central

Normal subjects were asked to breathe through an open ended tube while high frequency oscillations were superimposed on tidal breathing via a side arm, either an eight inch (20 cm) loudspeaker or a jet ventilator being used. Both systems were comfortable and well tolerated. Spontaneous minute ventilation fell by 19-46% at frequencies up to 33 Hz without a rise in transcutaneous PCO2. Maximum ventilatory savings occurred at 1.6 Hz with the jet ventilator (p less than 0.01) and at a frequency corresponding to respiratory system resonance with the loudspeaker. This suggests that during oral high frequency ventilation pulmonary gas exchange is improved and leads to more efficient carbon dioxide excretion for a given minute ventilation. This technique provides a practical and simple method of supplementing breathing in conscious subjects, and it may also have application in the management of patients with acute or chronic respiratory failure, where intubation and conventional ventilation might be avoided.

George, R J; Winter, R J; Johnson, M A; Slee, I P; Geddes, D M

1985-01-01

372

Common-path Fourier domain optical coherence tomography of irradiated human skin and ventilated isolated rabbit lungs  

NASA Astrophysics Data System (ADS)

A compact common path Fourier domain optical coherence tomography (FD-OCT) system based on a broadband superluminescence diode is used for biomedical imaging. The epidermal thickening of human skin after exposure to ultraviolet radiation is measured to proof the feasibility of FD-OCT for future substitution of invasive biopsies in a long term study on natural UV skin protection. The FD-OCT system is also used for imaging lung parenchyma. FD-OCT images of a formalin fixated lung show the same alveolar structure as scanning electron microscopy images. In the ventilated and blood-free perfused isolated rabbit lung FD-OCT is used for real-time cross-sectional image capture of alveolar mechanics throughout tidal ventilation. The alveolar mechanics changing from alternating recruitment-derecruitment at zero positive end-expiratory pressure (PEEP) to persistent recruitment after applying a PEEP of 5 cm H2O is observed in the OCT images.

Popp, A.; Wendel, M.; Knels, L.; Knuschke, P.; Mehner, M.; Koch, T.; Boller, D.; Koch, P.; Koch, E.

2005-08-01

373

Imbalance of Hsp70 family variants fosters tau accumulation  

PubMed Central

Dysfunctional tau accumulation is a major contributing factor in tauopathies, and the heat-shock protein 70 (Hsp70) seems to play an important role in this accumulation. Several reports suggest that Hsp70 proteins can cause tau degradation to be accelerated or slowed, but how these opposing activities are controlled is unclear. Here we demonstrate that highly homologous variants in the Hsp70 family can have opposing effects on tau clearance kinetics. When overexpressed in a tetracycline (Tet)-based protein chase model, constitutive heat shock cognate 70 (Hsc70) and inducible Hsp72 slowed or accelerated tau clearance, respectively. Tau synergized with Hsc70, but not Hsp72, to promote microtubule assembly at nearly twice the rate of either Hsp70 homologue in reconstituted, ATP-regenerating Xenopus extracts supplemented with rhodamine-labeled tubulin and human recombinant Hsp72 and Hsc70. Nuclear magnetic resonance spectroscopy with human recombinant protein revealed that Hsp72 had greater affinity for tau than Hsc70 (I/I0 ratio difference of 0.3), but Hsc70 was 30 times more abundant than Hsp72 in human and mouse brain tissue. This indicates that the predominant Hsp70 variant in the brain is Hsc70, suggesting that the brain environment primarily supports slower tau clearance. Despite its capacity to clear tau, Hsp72 was not induced in the Alzheimer's disease brain, suggesting a mechanism for age-associated onset of the disease. Through the use of chimeras that blended the domains of Hsp72 and Hsc70, we determined that the reason for these differences between Hsc70 and Hsp72 with regard to tau clearance kinetics lies within their C-terminal domains, which are essential for their interactions with substrates and cochaperones. Hsp72 but not Hsc70 in the presence of tau was able to recruit the cochaperone ubiquitin ligase CHIP, which is known to facilitate the ubiquitination of tau, describing a possible mechanism of how the C-termini of these homologous Hsp70 variants can differentially regulate tau triage. Thus, efforts to promote Hsp72 expression and inhibit Hsc70 could be therapeutically relevant for tauopathies.—Jinwal, U. K., Akoury, E., Abisambra, J. F., O'Leary, J. C., III, Thompson, A. D., Blair, L. J., Jin, Y., Bacon, J., Nordhues, B. A., Cockman, M., Zhang, J., Li, P., Zhang, B., Borysov, S., Uversky, V. N., Biernat, J., Mandelkow, E., Gestwicki, J. E., Zweckstetter, M., Dickey, C. A. Imbalance of Hsp70 family variants fosters tau accumulation.

Jinwal, Umesh K.; Akoury, Elias; Abisambra, Jose F.; O'Leary, John C.; Thompson, Andrea D.; Blair, Laura J.; Jin, Ying; Bacon, Justin; Nordhues, Bryce A.; Cockman, Matthew; Zhang, Juan; Li, Pengfei; Zhang, Bo; Borysov, Sergiy; Uversky, Vladimir N.; Biernat, Jacek; Mandelkow, Eckhard; Gestwicki, Jason E.; Zweckstetter, Markus; Dickey, Chad A.

2013-01-01

374

Pravastatin attenuates hypertension, oxidative stress and angiogenic imbalance in rat model of placental ischemia-induced hypertension  

PubMed Central

Preeclampsia is a pregnancy-specific condition characterized by an imbalance of circulating angiogenic factors and new-onset hypertension. Although current treatment options are limited, recent studies suggest pravastatin may improve angiogenic profile and reduce blood pressure in preeclampsia. We hypothesized pravastatin would restore angiogenic balance and reduce mean arterial pressure (MAP) in rats with reduced utero-placental perfusion pressure (RUPP)-induced hypertension. Pravastatin was administered i.p. (1 mg/kg/day) in RUPP (RUPP+P) and normal pregnant rats (NP+P) from day 14-19 of pregnancy. On day 19, MAP was measured via catheter, conceptus data was recorded and tissues collected. MAP was increased (p<0.05) in RUPP compared to NP dams and pravastatin ameliorated this difference. Pravastatin attenuated decreased fetal weight and plasma VEGF and the RUPP-induced increased sFlt-1 when compared to NP dams. Pravastatin treatment did not improve angiogenic potential in RUPP serum and decreased (P<0.05) endothelial tube formation in NP rats. RUPP rats presented with indices of oxidative stress such as increased placental catalase activity and plasma TBARS along with decreased plasma total antioxidant capacity compared to NP controls and pravastatin attenuated these effects. MAP, fetal weight, plasma VEGF, and plasma sFlt-1 were unchanged in NP+P compared to NP controls. The present data indicate that treatment with pravastatin attenuates oxidative stress and lowers MAP in placental ischemia-induced hypertension, but may have negative effects on circulating angiogenic potential during pregnancy. Further studies are needed to determine if there are long-term deleterious effects on maternal or fetal health following pravastatin treatment during pregnancy-induced hypertension or preeclampsia.

Bauer, Ashley J; Banek, Christopher T; Needham, Karen; Gillham, Haley; Capoccia, Susan; Regal, Jean F; Gilbert, Jeffrey S

2013-01-01

375

Principles of mechanical ventilation--a critical review.  

PubMed

This article is the first of a two-part review focusing on mechanical ventilation, with particular emphasis on non-invasive ventilation when managing patients suffering from respiratory failure. This article explores the principles underpinning artificial ventilation, explains the difference between positive and negative pressure ventilation, and differentiates between invasive and non-invasive modes of ventilation. Finally it examines the various operational features, flexibility in use and limitations that artificial ventilation therapy presents. Optimum ventilatory practice requires knowledge to ensure the choosing of the 'right' ventilator. It ensures informed practice and maintains optimum patient safety. PMID:19717989

Pertab, Dhanishwar

376

Evaluation of pulmonary dysfunctions and acid-base imbalances induced by Chlamydia psittaci in a bovine model of respiratory infection  

PubMed Central

Background Chlamydia psittaci (Cp) is a respiratory pathogen capable of inducing acute pulmonary zoonotic disease (psittacosis) or persistent infection. To elucidate the pathogenesis of this infection, a translational large animal model was recently introduced by our group. This study aims at quantifying and differentiating pulmonary dysfunction and acid–base imbalances induced by Cp. Methods Forty-two calves were grouped in (i) animals inoculated with Cp (n?=?21) and (ii) controls sham-inoculated with uninfected cell culture (n?=?21). For pulmonary function testing, impulse oscillometry, capnography, and FRC (functional residual capacity) measurement were applied to spontaneously breathing animals. Variables of acid–base status were assessed in venous blood using both (i) traditional Henderson-Hasselbalch and (ii) strong ion approach. Results Both obstructive and restrictive pulmonary disorders were induced in calves experimentally inoculated with Cp. Although disorders in respiratory mechanics lasted for 8–11 days, the pattern of spontaneous breathing was mainly altered in the period of acute illness (until 4 days post inoculation, dpi). Expiration was more impaired than inspiration, resulting in elevated FRC. Ventilation was characterised by a reduction in tidal volume (?25%) combined with an increased percentage of dead space volume and a significant reduction of alveolar volume by 10%. Minute ventilation increased significantly (+50%) due to a compensatory doubling of respiratory rate. Hyperventilatory hypocapnia at 2–3 dpi resulted in slightly increased blood pH at 2 dpi. However, the acid–base equilibrium was additionally influenced by metabolic components, i.e. the systemic inflammatory response, all of which were detected with help of the strong ion theory. Decreased concentrations of albumin (2–10 dpi), a negative acute-phase marker, resulted in a decrease in the sum of non-volatile weak acids (Atot), revealing an alkalotic effect. This was counterbalanced by acidic effects of decreased strong ion difference (SID), mediated by the interplay between hypochloraemia (alkalotic effect) and hyponatraemia (acidic effect). Conclusions This bovine model was found to be suitable for studying pathophysiology of respiratory Cp infection and may help elucidating functional host-pathogen interactions in the mammalian lung.

2014-01-01

377

Demand Controlled Ventilating Systems: Sensor Tests.  

National Technical Information Service (NTIS)

A test program has been designed to evaluate the performance characteristics of sensors for the automatic control of ventilation rates. The test program consists of two main parts, one being the evaluation of sensor performance in laboratory tests and the...

P. Fahlen H. Andersson S. Ruud

1992-01-01

378

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...shall be of watertight construction. (3) Inlets to exhaust ducts shall be provided and located at points where concentration...of vapor ignition. Terminals shall be fitted with acceptable flame screens. (4) The control for the power ventilation...

2013-10-01

379

Waste tank ventilation system waste material accumulations  

Microsoft Academic Search

This paper calculates the amount of material that accumulates in the ventilation systems of various Tank Waste Remediation System facilities and estimates the amount of material that could be released due to a rapid pressurization.

Van Vleet; Westinghouse Hanford

1996-01-01

380

46 CFR 194.15-5 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS HANDLING, USE, AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-5 Ventilation. (a) Operations, reactions or...

2013-10-01

381

EVALUATION OF VENTILATION PERFORMANCE FOR INDOOR SPACE  

EPA Science Inventory

The paper discusses a personal-computer-based application of computational fluid dynamics that can be used to determine the turbulent flow field and time-dependent/steady-state contaminant concentration distributions within isothermal indoor space. (NOTE: Ventilation performance ...

382

Shelter Occupancy Studies of Ventilator Utilization.  

National Technical Information Service (NTIS)

The report describes three shelter occupancy experiments designed to investigate shelter management problems involving shelteree needs and responses, control of the shelter environment, shelter organization, and the operation of shelter ventilation equipm...

A. G. Jago J. A. Anderson R. C. Friedman

1970-01-01

383

[The choice of a pediatric anesthesia ventilator].  

PubMed

The technology of anesthesia ventilators has substantially progressed during last years. The choice of a pediatric anesthesia ventilator needs to be led by multiple parameters: requirement, technical (pneumatic performance, velocity of halogenated or oxygen delivery), cost (purchase, in operation, preventive and curative maintenance), reliability, ergonomy, upgradability, and compatibility. The demonstration of the interest of pressure support mode during maintenance of spontaneous ventilation anesthesia makes this mode essential in pediatrics. In contrast, the financial impact of target controlled inhalation of halogenated has not be studied in pediatrics. Paradoxically, complex and various available technologies had not been much prospectively studied. Anesthesia ventilators performances in pediatrics need to be clarified in further clinical and bench test studies. PMID:24209991

Kern, D; Larcher, C; Cottron, N; Ait Aissa, D; Fesseau, R; Alacoque, X; Delort, F; Masquère, P; Agnès, E; Visnadi, G; Fourcade, O

2013-12-01

384

30 CFR 75.333 - Ventilation controls.  

Code of Federal Regulations, 2013 CFR

...for the construction of overcasts, undercasts, shaft partitions, permanent stoppings, and regulators include concrete, concrete block, brick, cinder block, tile, or steel. No ventilation controls installed after November 15, 1992,...

2013-07-01

385

[Cerebral kinetics of brain perfusion agents].  

PubMed

Radiotracers called chemical microsphere are widely accepted as brain perfusion agents. Following the intravenous administration, these drugs are transported via the artery to the brain, cross the intact blood-brain barrier, and enter the brain tissue. Once the tracer flows into the brain, the efflux of the tracer is prevented by some trapping mechanism, resulting in prolonged retention. Because the distribution of the accumulated tracer remains approximately consistent with regional cerebral blood flow for a relatively long period, high-quality SPECT images reflecting the distribution pattern of cerebral blood flow can be acquired. However, unlike true microsphere, cerebral kinetics of the brain perfusion agents is complicated, and various causes may produce discrepancy between the distributions of the tracer and blood flow. In this review, cerebral kinetics of the brain perfusion agents used commonly is discussed. The knowledge of the mechanism of brain accumulation appears to be essential to appropriately determine the tracer of choice and interpret the obtained images. PMID:9567034

Inoue, Y

1998-02-01

386

Cardiac tissue engineering using perfusion bioreactor systems  

PubMed Central

This protocol describes tissue engineering of synchronously contractile cardiac constructs by culturing cardiac cell populations on porous scaffolds (in some cases with an array of channels) and bioreactors with perfusion of culture medium (in some cases supplemented with an oxygen carrier). The overall approach is ‘biomimetic’ in nature as it tends to provide in vivo-like oxygen supply to cultured cells and thereby overcome inherent limitations of diffusional transport in conventional culture systems. In order to mimic the capillary network, cells are cultured on channeled elastomer scaffolds that are perfused with culture medium that can contain oxygen carriers. The overall protocol takes 2–4 weeks, including assembly of the perfusion systems, preparation of scaffolds, cell seeding and cultivation, and on-line and end-point assessment methods. This model is well suited for a wide range of cardiac tissue engineering applications, including the use of human stem cells, and high-fidelity models for biological research.

Radisic, Milica; Marsano, Anna; Maidhof, Robert; Wang, Yadong; Vunjak-Novakovic, Gordana

2009-01-01

387

[A study on hepatic perfusion parameter calculation].  

PubMed

Hepatic perfusion parameters play an important role in detecting and diagnosing diffusion diseases of liver. Based on a hemodynamic model. In this study, we described a fast and accurate method to calculate the perfusion parameters. First, we used a dual-input one-compartment kinetics model to illustrate the distribution of the contrast agent concentration among the body. Then, we used the Gaussian function to fit the scatter concentration data of portal vein and aorta, to obtain a liver agent concentration on function of time. Finally, we solved the model parameters by using Levenberg-Marquardt algorithm, and calculated the perfusion parameters. The results showed that the method proposed in this study could calculate the parameters precisely, and had a prosperous future application possibility. PMID:24645606

Peng, Fan; Shen, Bixian; Liao, Zhenhua; Liu, Weiqiang

2013-12-01

388

Sensor-based demand controlled ventilation  

SciTech Connect

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pollutant generation. In other words, SBDCV involves the application of sensing, feedback and control to modulate ventilation. Compared to ventilation without feedback, SBDCV offers two potential advantages: (1) better control of indoor pollutant concentrations; and (2) lower energy use and peak energy demand. SBDCV has the potential to improve indoor air quality by increasing the rate of ventilation when indoor pollutant generation rates are high and occupants are present. SBDCV can also save energy by decreasing the rate of ventilation when indoor pollutant generation rates are low or occupants are absent. After providing background information on indoor air quality and ventilation, this report provides a relatively comprehensive discussion of SBDCV. Topics covered in the report include basic principles of SBDCV, sensor technologies, technologies for controlling air flow rates, case studies of SBDCV, application of SBDCV to laboratory buildings, and research needs. SBDCV appears to be an increasingly attractive technology option. Based on the review of literature and theoretical considerations, the application of SBDCV has the potential to be cost-effective in applications with the following characteristics: (a) a single or small number of dominant pollutants, so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy.

De Almeida, A.T. [Universidade de Coimbra (Portugal). Dep. Eng. Electrotecnica; Fisk, W.J. [Lawrence Berkeley National Lab., CA (United States)

1997-07-01

389

Iatrogenic pneumothorax related to mechanical ventilation  

PubMed Central

Pneumothorax is a potentially lethal complication associated with mechanical ventilation. Most of the patients with pneumothorax from mechanical ventilation have underlying lung diseases; pneumothorax is rare in intubated patients with normal lungs. Tension pneumothorax is more common in ventilated patients with prompt recognition and treatment of pneumothorax being important to minimize morbidity and mortality. Underlying lung diseases are associated with ventilator-related pneumothorax with pneumothoraces occurring most commonly during the early phase of mechanical ventilation. The diagnosis of pneumothorax in critical illness is established from the patients’ history, physical examination and radiological investigation, although the appearances of a pneumothorax on a supine radiograph may be different from the classic appearance on an erect radiograph. For this reason, ultrasonography is beneficial for excluding the diagnosis of pneumothorax. Respiration-dependent movement of the visceral pleura and lung surface with respect to the parietal pleura and chest wall can be easily visualized with transthoracic sonography given that the presence of air in the pleural space prevents sonographic visualization of visceral pleura movements. Mechanically ventilated patients with a pneumothorax require tube thoracostomy placement because of the high risk of tension pneumothorax. Small-bore catheters are now preferred in the majority of ventilated patients. Furthermore, if there are clinical signs of a tension pneumothorax, emergency needle decompression followed by tube thoracostomy is widely advocated. Patients with pneumothorax related to mechanical ventilation who have tension pneumothorax, a higher acute physiology and chronic health evaluation?II?score or PaO2/FiO2 < 200 mmHg were found to have higher mortality.

Hsu, Chien-Wei; Sun, Shu-Fen

2014-01-01

390

Iatrogenic pneumothorax related to mechanical ventilation.  

PubMed

Pneumothorax is a potentially lethal complication associated with mechanical ventilation. Most of the patients with pneumothorax from mechanical ventilation have underlying lung diseases; pneumothorax is rare in intubated patients with normal lungs. Tension pneumothorax is more common in ventilated patients with prompt recognition and treatment of pneumothorax being important to minimize morbidity and mortality. Underlying lung diseases are associated with ventilator-related pneumothorax with pneumothoraces occurring most commonly during the early phase of mechanical ventilation. The diagnosis of pneumothorax in critical illness is established from the patients' history, physical examination and radiological investigation, although the appearances of a pneumothorax on a supine radiograph may be different from the classic appearance on an erect radiograph. For this reason, ultrasonography is beneficial for excluding the diagnosis of pneumothorax. Respiration-dependent movement of the visceral pleura and lung surface with respect to the parietal pleura and chest wall can be easily visualized with transthoracic sonography given that the presence of air in the pleural space prevents sonographic visualization of visceral pleura movements. Mechanically ventilated patients with a pneumothorax require tube thoracostomy placement because of the high risk of tension pneumothorax. Small-bore catheters are now preferred in the majority of ventilated patients. Furthermore, if there are clinical signs of a tension pneumothorax, emergency needle decompression followed by tube thoracostomy is widely advocated. Patients with pneumothorax related to mechanical ventilation who have tension pneumothorax, a higher acute physiology and chronic health evaluation?II?score or PaO2/FiO2 < 200 mmHg were found to have higher mortality. PMID:24834397

Hsu, Chien-Wei; Sun, Shu-Fen

2014-02-01

391

Cerebral perfusion changes in chronic subdural hematoma.  

PubMed

Abstract Chronic subdural hematoma is a frequent disorder in the elderly. Although intensively investigated, numerous aspects, including the pathophysiology of clinical symptoms, remain unclear. Perfusion deficits are likely to induce the transient neurologic symptoms seen in chronic subdural hematoma (cSDH). The aim of the present study was to quantify cerebral perfusion impairment in cSDH. Before surgery, 34 patients were examined neurologically using the National Institutes of Health Stroke Scale (NIHSS) score and investigated by CT perfusion imaging. Hematoma volume, localization, and hematoma configuration were recorded. Clinical and radiological data were correlated. Mean hematoma volume was 91.8?cm(3) (16.2-241.6?cm(3), standard deviation [SD] 49.5). Whole brain mean transit time (MTT) was slightly elevated (mean 36.6?sec, SD 5.8). Hematoma volume and cerebral blood volume (CBV) in the underlying hemisphere correlated marginally but not significantly (p=0.067). Perfusion parameters determined in the area below the hematoma (ABH) and the corresponding contralateral cortex (MAC) were highly significantly different regarding cerebral blood flow (CBF) (mean 88.8 vs. 70.4, p<0.01) and CBV (mean 29.4 vs. 22.5, p<0.01). On the other hand, MTT and Tmax were almost equal between these areas (MTT means 35.0 vs. 34.8, (p)=0.914; tMax means 16.0 vs. 15.4, p=0.587). We conclude that local brain perfusion autoregulation is active in the cortical area below cSDH. CBV and CBF are significantly upregulated in the cortical area below cSDH indicating the effect of autoregulation in tissue at risk of ischemia. Cerebral autoregulation is intact in cSDH. Neurologic deficits are likely induced by borderline perfusion. PMID:23227943

Slotty, Philipp Jörg; Kamp, Marcel Alexander; Steiger, Steiger Hans-Jakob; Cornelius, Jan Frederick; Macht, Stephan; Stummer, Walter; Turowski, Bernd

2013-03-01

392

Construction of Prediction Module for Successful Ventilator Weaning  

Microsoft Academic Search

Ventilator weaning is the process of discontinuing mechanical ventilation from patients with respiratory failure. Previous\\u000a investigations reported that 39%-40% of the intensive care unit (ICU) patients need mechanical ventilator for sustaining their\\u000a lives. Among them, 90% of the patients can be weaned from the ventilator in several days while other 5%-15% of the patients\\u000a need longer ventilator support. Modern mechanical

Jiin-chyr Hsu; Yung-fu Chen; Hsuan-hung Lin; Chi-hsiang Li; Xiaoyi Jiang

2007-01-01

393

Tracer dating and ocean ventilation  

SciTech Connect

The interpretation of transient tracer observations depends on difficult to obtain information on the evolution in time of the tracer boundary conditions and interior distributions. Recent studies have attempted to circumvent this problem by making use of a derived quantity, age, based on the simultaneous distribution of two complementary tracers, such as tritium and its daughter, helium 3. The age is defined with reference to the surface such that the boundary condition takes on a constant value of zero. The authors use a two-dimensional model to explore the circumstances under which such a combination of conservation equations for two complementary tracers can lead to a cancellation of the time derivative terms. An interesting aspect of this approach is that mixing can serve as a source or sink of tracer based age. The authors define an idealized ventilation age tracer that is conservative with respect to mixing, and they explore how its behavior compares with that of the tracer-based ages over a range of advective and diffusive parameters.

Thiele, G.; Sarmiento, J.L. (Princeton Univ., NJ (United States))

1990-06-15

394

Seismic qualification of ventilation stack  

SciTech Connect

This paper describes the method to be used to qualify the 105 K ventilation stack at the U.S. Department of Energy`s Hanford Site, near Richland, Washington, under seismic and wind loadings. The stack stands at 175 ft (53.34 m), with a diameter tapering from 22 ft (6.71 m) at the foundation to 12.83 ft (3.91 m) at the top. Although the stack is classified as Safety Class 3 (low hazard), it is treated as a Safety Class 1 (high hazard) component, as failure could damage a Safety Class 1 facility (the irradiated fuel storage basin). The evaluation used U.S. Department of Energy criteria specified in UCRL 15910 (1990). The seismic responses of the stack under earthquake loading were obtained from modal analyses with response spectrum input that used the ANSYS (1989) finite-element computer code. The moments and shear forces from the results of seismic analysis were used to qualify the reinforcement capacity of the stack structure by the ultimate-strength method. The wind forces acting on the stack in both along-wind and crosswind directions were also calculated. Presented are evaluations of the soil bearing pressure, the moment, and the shear capacity of the stack foundation.

Chen, W.W.; Huang, S.N.; Lindquist, M.R.

1993-10-01

395

A novel microthermal probe for the measurement of perfusion  

NASA Astrophysics Data System (ADS)

Using micro-fabrication techniques a micro thermal probe has been developed in our laboratory to measure the thermal conductivity of biological tissues. This paper presents our latest experimental results which demonstrate the usefulness of the micro thermal probe in mapping the complicated perfusion field inside biological tissues. A perfused pig liver model has been constructed to simulate in vivo conditions. The portal vein and hepatic artery of a porcine liver were intubated and connected to a perfusion circuit. Saline water was perfused through the liver driven by a peristaltic pump. By varying the pumping rate of the perfused model, we measured the effective thermal conductivity at different perfusion rates in different locations. The results show that the effective thermal conductivity varies with the square root of the perfusion rate. Also, by rotating the micro probes, we observed a strong directional dependence of the effective thermal conductivity, revealing that perfusion is not a scalar but a vector field.

Yi, Ming; Kausik, Aditya; Podhajsky, Ronald J.; Mahajan, Roop L.

2009-02-01

396

An Apparatus for the Pulsating Perfusion of Whole Organs.  

National Technical Information Service (NTIS)

An organ perfusion system is presented which is simple in design, economical in construction, and easily adaptable to various laboratory requirements. The principle of operation is based on two perfusate-containing flexible plastic bags immersed in liquid...

C. A. Lindbergh V. P. Perry T. I. Malinin G. H. Mouer

1966-01-01

397

Clinical review: Long-term noninvasive ventilation  

PubMed Central

Noninvasive positive ventilation has undergone a remarkable evolution over the past decades and is assuming an important role in the management of both acute and chronic respiratory failure. Long-term ventilatory support should be considered a standard of care to treat selected patients following an intensive care unit (ICU) stay. In this setting, appropriate use of noninvasive ventilation can be expected to improve patient outcomes, reduce ICU admission, enhance patient comfort, and increase the efficiency of health care resource utilization. Current literature indicates that noninvasive ventilation improves and stabilizes the clinical course of many patients with chronic ventilatory failure. Noninvasive ventilation also permits long-term mechanical ventilation to be an acceptable option for patients who otherwise would not have been treated if tracheostomy were the only alternative. Nevertheless, these results appear to be better in patients with neuromuscular/-parietal disorders than in chronic obstructive pulmonary disease. This clinical review will address the use of noninvasive ventilation (not including continuous positive airway pressure) mainly in diseases responsible for chronic hypoventilation (that is, restrictive disorders, including neuromuscular disease and lung disease) and incidentally in others such as obstructive sleep apnea or problems of central drive.

Robert, Dominique; Argaud, Laurent

2007-01-01

398

Protective ventilation using electrical impedance tomography.  

PubMed

Dynamic thoracic EIT is capable of detecting changes of the ventilation distribution in the lung. Nevertheless, it has yet to become an established clinical tool. Therefore, it is necessary to consider application scenarios wherein fast and distinct changes of the tissue conductivities are to be found and also have a clear diagnostic significance. One such a scenario is the artificial ventilation of patients suffering from the acute respiratory distress syndrome (ARDS). New protective ventilation strategies involving recruitment manoeuvres are associated with noticeable shifts of body fluids and regional ventilation, which can quite easily be detected by EIT. The bedside assessment of these recruitment manoeuvres will help the attending physician to optimize treatment. Hence, we performed an animal study of lavage-induced lung failure and investigated if EIT is capable of qualitatively as well as quantitatively monitoring lung recruitment during a stepwise PEEP trial. Additionally, we integrated EIT into a fuzzy controller-based ventilation system which allows one to perform automated recruitment manoeuvres (open lung concept) based on online PaO2 measurements. We found that EIT is a useful tool to titrate the proper PEEP level after fully recruiting the lung. Furthermore, EIT seems to be able to determine the status of recruitment when combining it with other physiological parameters. These results suggest that EIT may play an important role in the individualization of protective ventilation strategies. PMID:17664639

Luepschen, H; Meier, T; Grossherr, M; Leibecke, T; Karsten, J; Leonhardt, S

2007-07-01

399

Dynamic perfusion patterns in temporal lobe epilepsy  

Microsoft Academic Search

Purpose  To investigate dynamic ictal perfusion changes during temporal lobe epilepsy (TLE).\\u000a \\u000a \\u000a \\u000a Methods  We investigated 37 patients with TLE by ictal and interictal SPECT. All ictal injections were performed within 60 s of seizure\\u000a onset. Statistical parametric mapping was used to analyse brain perfusion changes and temporal relationships with injection\\u000a time and seizure duration as covariates.\\u000a \\u000a \\u000a \\u000a Results  The analysis revealed significant ictal hyperperfusion in

Patrick Dupont; John J. Zaknun; Alex Maes; Supatporn Tepmongkol; Silvia Vasquez; C. S. Bal; Wim Van Paesschen; Silvina Carpintiero; Chaichon Locharernkul; Maurizio Dondi

2009-01-01

400

Blood leakage and melphalan leakage from the perfusion circuit during regional hyperthermic perfusion for malignant melanoma  

SciTech Connect

In regional hyperthermic perfusion with melphalan for patients with malignant melanoma of the leg, plasma leakage between the perfusion circuit and the systemic circulation was 4-7 ml X min-1. The melphalan concentration in the perfusate was biphasic, with half-lives of 8-12 mins for the initial phase and 19-28 mins for the second phase, after the first dose. After a second dose, the corresponding values were 11-13 and 26-34 mins. The highest concentration in general circulation was 0.38 micrograms X ml-1.

Hafstroem, L.; Hugander, A.; Joensson, P.E.; Westling, H.; Ehrsson, H.

1984-06-01

401

Value of perfusion lung scan in the diagnosis of pulmonary embolism: results of the Prospective Investigative Study of Acute Pulmonary Embolism Diagnosis (PISA-PED).  

PubMed

To assess the value of perfusion lung scan in the diagnosis of pulmonary embolism, we prospectively evaluated 890 consecutive patients with suspected pulmonary embolism. Prior to lung scanning, each patient was assigned a clinical probability of pulmonary embolism (very likely, possible, unlikely). Perfusion scans were independently classified as follows: (1) normal, (2) near-normal, (3) abnormal compatible with pulmonary embolism (PE+: single or multiple wedge-shaped perfusion defects), or (4) abnormal not compatible with pulmonary embolism (PE-: perfusion defects other than wedge-shaped). The study design required pulmonary angiography and clinical and scintigraphic follow-up in all patients with abnormal scans. Of 890 scans, 220 were classified as normal/or near-normal and 670 as abnormal. A definitive diagnosis was established in 563 (84%) patients with abnormal scans. The overall prevalence of pulmonary embolism was 39%. Most patients with angiographically proven pulmonary embolism had PE+ scans (sensitivity: 92%). Conversely, most patients without emboli on angiography had PE- scans (specificity: 87%). A PE+ scan associated with a very likely or possible clinical presentation of pulmonary embolism had positive predictive values of 99 and 92%, respectively. A PE- scan paired with an unlikely clinical presentation had a negative predictive value of 97%. Clinical assessment combined with perfusion-scan evaluation established or excluded pulmonary embolism in the majority of patients with abnormal scans. Our data indicate that accurate diagnosis of pulmonary embolism is possible by perfusion scanning alone, without ventilation imaging. Combining perfusion scanning with clinical assessment helps to restrict the need for angiography to a minority of patients with suspected pulmonary embolism. PMID:8912753

Miniati, M; Pistolesi, M; Marini, C; Di Ricco, G; Formichi, B; Prediletto, R; Allescia, G; Tonelli, L; Sostman, H D; Giuntini, C

1996-11-01

402

Perfusion MRI: The Five Most Frequently Asked Clinical Questions  

PubMed Central

OBJECTIVE This article addresses questions that radiologists frequently ask when planning, performing, processing, and interpreting MRI perfusion studies in CNS imaging. CONCLUSION Perfusion MRI is a promising tool in assessing stroke, brain tumors, and neurodegenerative diseases. Most of the impediments that have limited the use of perfusion MRI can be overcome to allow integration of these methods into modern neuroimaging protocols.

Essig, Marco; Nguyen, Thanh Binh; Shiroishi, Mark S.; Saake, Marc; Provenzale, James M.; Enterline, David S.; Anzalone, Nicoletta; Dorfler, Arnd; Rovira, Alex; Wintermark, Max; Law, Meng

2013-01-01

403

A laser speckle imaging technique for measuring tissue perfusion  

Microsoft Academic Search

Laser Doppler imaging (LDI) has become a standard method for optical measurement of tissue perfusion, but is limited by low resolution and long measurement times. We have developed an analysis technique based on a laser speckle imaging method that generates rapid, high-resolution perfusion images. We have called it laser speckle perfusion imaging (LSPI). This paper investigates LSPI output and compares

Kevin R. Forrester; J. Tulip; C. Leonard; C. Stewart; Robert C. Bray

2004-01-01

404

Airway pressure release ventilation: an alternative mode of mechanical ventilation in acute respiratory distress syndrome.  

PubMed

Acute respiratory distress syndrome (ARDS) results in collapse of alveoli and therefore poor oxygenation. In this article, we review airway pressure release ventilation (APRV), a mode of mechanical ventilation that may be useful when, owing to ARDS, areas of the lungs are collapsed and need to be reinflated ("recruited"), avoiding cyclic alveolar collapse and reopening. PMID:21285342

Modrykamien, Ariel; Chatburn, Robert L; Ashton, Rendell W

2011-02-01

405

Normal binocular rivalry in autism: implications for the excitation/inhibition imbalance hypothesis.  

PubMed

Autism is characterized by disruption in multiple dimensions of perception, emotion, language and social cognition. Many hypotheses for the underlying neurophysiological basis have been proposed. Among these is the excitation/inhibition (E/I) imbalance hypothesis, which states that levels of cortical excitation and inhibition are disrupted in autism. We tested this theory in the visual system, because vision is one of the better understood systems in neuroscience, and because the E/I imbalance theory has been proposed to explain hypersensitivity to sensory stimuli in autism. We conducted two experiments on binocular rivalry, a well-studied psychophysical phenomenon that depends critically on excitation and inhibition levels in cortex. Using a computational model, we made specific predictions about how imbalances in excitation and inhibition levels would affect perception during two aspects of binocular rivalry: mixed perception (Experiment 1) and traveling waves (Experiment 2). We found no significant differences in either of these phenomena between high-functioning adults with autism and controls, and no evidence for a relationship between these measurements and the severity of autism. These results do not conclusively rule out an excitation/inhibition imbalance in the visual system of those with autism, but they suggest that such an imbalance, if it exists, is likely to be small in magnitude. PMID:23200868

Said, Christopher P; Egan, Ryan D; Minshew, Nancy J; Behrmann, Marlene; Heeger, David J

2013-01-25

406

Hydrostatic Hyperbaric Chamber Ventilation System  

NASA Technical Reports Server (NTRS)

The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy (HBOT) available in the developing world for the treatment of a variety of medical conditions. Specifically, HBOT is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. HBOT is simply too expensive and too dangerous to implement in the developing world using standard equipment. The HHC technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system to provide controlled pressurization and adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the patient and operating personnel, and physiological considerations. The simple schematic, comprised of easily acquired commercial hardware, supports sustainability.

Sarguisingh, Miriam J.

2012-01-01

407

Functional and morphologic changes caused by acute ozone exposure in the isolated and perfused rat lung  

SciTech Connect

Ozone has been shown to increase airway resistance and/or airway reactivity in vivo in animals and humans. Because of the complexities inherent in studying this phenomenon in whole animals, we developed a model of ozone-induced effects on airway physiology using the isolated perfused rat lung. Rat lungs were suspended in an airtight chamber and perfused via the pulmonary circulation with a modified Krebs-Henseleit buffer containing 4.5% bovine albumin. Ventilation of the lungs was achieved by generating a fluctuating negative pressure within the chamber (-2 to -7 cm H2O) at a rate of 60 breaths/min. The lungs were ventilated with humidified 95% air and 5% CO2 alone (control condition) or mixed with ozone at 1.0 or 2.0 ppm. Transpulmonary pressure, flow rate, and tidal volume were recorded at 0, 1, 2, and 3 hours, and pulmonary resistance (RL) and dynamic compliance (Cdyn) were calculated. There was no significant difference in lung weight/total body weight ratios between the three groups at the end of the 3-h period. RL increased and Cdyn decreased in a time- and dose-dependent manner with ozone exposure. The percent increase above baseline in RL +/- SEM at 3 h was 9.4 +/- 4.1% for control lungs, 21.0 +/- 3.2% for 1.0 ppm ozone-exposed lungs, and 63.6 +/- 13.5% for 2.0 ppm ozone-exposed lungs. The percent decrease below baseline in Cdyn +/- SEM at 3 h was 27.4 +/- 2.1% for control lungs, 37.1 +/- 2.7% for 1.0 ppm ozone-exposed lungs, and 55.2 +/- 7.3% for 2.0 ppm ozone-exposed lungs.(ABSTRACT TRUNCATED AT 250 WORDS)

Pino, M.V.; McDonald, R.J.; Berry, J.D.; Joad, J.P.; Tarkington, B.K.; Hyde, D.M. (California Primate Research Center, University of California, Davis (United States))

1992-04-01

408

Perfusion CT in Colorectal Cancer: Comparison of Perfusion Parameters with Tumor Grade and Microvessel Density  

PubMed Central

Objective The purpose of this study was to prospectively compare pre-operative computed tomography (CT) perfusion parameters with tumor grade from colorectal adenocarcinoma (CRC) and to correlate pre-operative CT perfusion parameters with microvessel density (MVD) to evaluate angiogenesis in CRC. Materials and Methods Pre-operative perfusion CTs were performed with a 64-channel multidetector row CT in 27 patients (17 women and 10 men; age range 32-82 years) who were diagnosed with CRC involving the sigmoid and rectum between August 2006 and November 2007. All patients underwent surgery without pre-operative chemotherapy or radiation therapy. Dynamic perfusion CTs were performed for 65 seconds after intravenous injection of contrast medium (100 mL, 300 mg of iodine per mL, 5 mL/sec). Before surgery, blood flow (BF), blood volume, mean transit time (MTT), and permeability-surface area product were measured in the tumor. After surgery, one gastrointestinal pathologist evaluated tumor grade and performed immunohistochemical staining using CD 34 to determine MVD in each tumor. The Kruskal-Wallis test was used to compare CT perfusion parameters with tumor grade, and Pearson's correlation analysis was used to correlate CT perfusion parameters with MVD. Results In 27 patients with CRC, tumor grading was as follows: well differentiated (n = 8); moderately differentiated (n = 15); and poorly differentiated (n = 4). BF was higher in moderately differentiated CRC than well differentiated and poorly differentiated CRCs (p = 0.14). MTT was shorter in moderately differentiated than well differentiated and poorly differentiated CRCs (p = 0.039). The MVD was greater in poorly differentiated than well differentiated and moderately differentiated CRCs (p = 0.034). There was no significant correlation between other perfusion parameters and tumor grade. There was no significant correlation between CT perfusion parameters and MVD. Conclusion BF and MTT measurement by perfusion CT is effective in predicting moderately differentiated CRCs. However, perfusion CT is limited in distinguishing well differentiated and poorly differentiated CRCs. Pre-operative perfusion CT does not reflect the MVD of CRCs.

Kim, Jin Woong; Chang, Nam Kyu; Heo, Suk Hee; Shin, Sang Soo; Lee, Jae Hyuk; Hur, Young Hoe; Kang, Heoung Keun

2012-01-01

409

Regenerative Blower for EVA Suit Ventilation Fan  

NASA Technical Reports Server (NTRS)

Portable life support systems in future space suits will include a ventilation subsystem driven by a dedicated fan. This ventilation fan must meet challenging requirements for pressure rise, flow rate, efficiency, size, safety, and reliability. This paper describes research and development that showed the feasibility of a regenerative blower that is uniquely suited to meet these requirements. We proved feasibility through component tests, blower tests, and design analysis. Based on the requirements for the Constellation Space Suit Element (CSSE) Portable Life Support System (PLSS) ventilation fan, we designed the critical elements of the blower. We measured the effects of key design parameters on blower performance using separate effects tests, and used the results of these tests to design a regenerative blower that will meet the ventilation fan requirements. We assembled a proof-of-concept blower and measured its performance at sub-atmospheric pressures that simulate a PLSS ventilation loop environment. Head/flow performance and maximum efficiency point data were used to specify the design and operating conditions for the ventilation fan. We identified materials for the blower that will enhance safety for operation in a lunar environment, and produced a solid model that illustrates the final design. The proof-of-concept blower produced the flow rate and pressure rise needed for the CSSE ventilation subsystem while running at 5400 rpm, consuming only 9 W of electric power using a non-optimized, commercial motor and controller and inefficient bearings. Scaling the test results to a complete design shows that a lightweight, compact, reliable, and low power regenerative blower can meet the performance requirements for future space suit life support systems.

Izenson, Michael G.; Chen, Weibo; Paul, Heather L.

2010-01-01

410

Myocardial perfusion imaging using contrast echocardiography  

Microsoft Academic Search

A program for objective automatic mapping of myocardial perfusion was developed. The program acquires a sequence of end-diastolic ultrasound images, using automatic echocardiography gating. Each image is divided into multiple regions of interest. The division is done either manually tracing the endocardial and epicardial borders, or automatically, using a running square window which covers the entire image. The analysis is

Menachem Halmann; Shimon Reisner; Rafael Beyar

1990-01-01

411

A reappraisal of retrograde cerebral perfusion  

PubMed Central

Brain protection during aortic arch surgery by perfusing cold oxygenated blood into the superior vena cava was first reported by Lemole et al. In 1990 Ueda and associates first described the routine use of continuous retrograde cerebral perfusion (RCP) in thoracic aortic surgery for the purpose of cerebral protection during the interval of obligatory interruption of anterograde cerebral flow. The beneficial effects of RCP may be its ability to sustain brain hypothermia during hypothermic circulatory arrest (HCA) and removal of embolic material from the arterial circulation of the brain. RCP can offer effective brain protection during HCA for about 40 to 60 minutes. Animal experiments revealed that RCP provided inadequate cerebral perfusion and that neurological recovery was improved with selective antegrade cerebral perfusion (ACP), however, both RCP and ACP provide comparable clinical outcomes regarding both the mortality and stroke rates by risk-adjusted and case-matched comparative study. RCP still remains a valuable adjunct for brain protection during aortic arch repair in particular pathologies and patients.

2013-01-01

412

Asynchronicity of Facial Blood Perfusion in Migraine  

PubMed Central

Asymmetrical changes in blood perfusion and asynchronous blood supply to head tissues likely contribute to migraine pathophysiology. Imaging was widely used in order to understand hemodynamic variations in migraine. However, mapping of blood pulsations in the face of migraineurs has not been performed so far. We used the Blood Pulsation Imaging (BPI) technique, which was recently developed in our group, to establish whether 2D-imaging of blood pulsations parameters can reveal new biomarkers of migraine. BPI characteristics were measured in migraineurs during the attack-free interval and compared to healthy subjects with and without a family history of migraine. We found a novel phenomenon of transverse waves of facial blood perfusion in migraineurs in contrast to healthy subjects who showed synchronous blood delivery to both sides of the face. Moreover, the amplitude of blood pulsations was symmetrically distributed over the face of healthy subjects, but asymmetrically in migraineurs and subjects with a family history of migraine. In the migraine patients we found a remarkable correlation between the side of unilateral headache and the direction of the blood perfusion wave. Our data suggest that migraine is associated with lateralization of blood perfusion and asynchronous blood pulsations in the facial area, which could be due to essential dysfunction of the autonomic vascular control in the face. These findings may further enhance our understanding of migraine pathophysiology and suggest new easily available biomarkers of this pathology.

Zaproudina, Nina; Teplov, Victor; Nippolainen, Ervin; Lipponen, Jukka A.; Kamshilin, Alexei A.; Narhi, Matti; Karjalainen, Pasi A.; Giniatullin, Rashid

2013-01-01

413

Correlation of Early Dynamic CT Perfusion Imaging with Whole-Brain MR Diffusion and Perfusion Imaging in Acute Hemispheric Stroke  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Compared with MR imaging, dynamic CT perfusion imag- ing covers only a fraction of the whole brain. An important assumption is that CT perfusion abnormalities correlate with total ischemic volume. The purpose of our study was to measure the degree of correlation between abnormalities seen on CT perfusion scans and the volumes of abnormality seen on MR

James D. Eastwood; Michael H. Lev; Max Wintermark; Clemens Fitzek; Daniel P. Barboriak; David M. Delong; Ting-Yim Lee; Tarek Azhari; Michael Herzau; Vani R. Chilukuri; James M. Provenzale

414

A Porcine Model for Initial Surge Mechanical Ventilator Assessment and Evaluation of Two Limited Function Ventilators  

PubMed Central

Objective To adapt an animal model of acute lung injury for use as a standard protocol for a screening, initial evaluation of limited function, or “surge,” ventilators for use in mass casualty scenarios. Design Prospective, experimental animal study. Setting University research laboratory. Subjects 12 adult pigs. Interventions 12 spontaneously breathing pigs (6 in each group) were subjected to acute lung injury/acute respiratory distress syndrome (ALI/ARDS) via pulmonary artery infusion of oleic acid. Following development of respiratory failure, animals were mechanically ventilated with a limited function ventilator (Simplified Automatic Ventilator [SAVe] I or II; Automedx) for one hour or until the ventilator could not support the animal. The limited function ventilator was then exchanged for a full function ventilator (Servo 900C; Siemens). Measurements and Main Results Reliable and reproducible levels of ALI/ARDS were induced. The SAVe I was unable to adequately oxygenate 5 animals, with PaO2 (52.0 ± 11.1 torr) compared to the Servo (106.0 ± 25.6 torr; p=0.002). The SAVe II was able to oxygenate and ventilate all 6 animals for one hour with no difference in PaO2 (141.8 ± 169.3 torr) compared to the Servo (158.3 ± 167.7 torr). Conclusions We describe a novel in vivo model of ALI/ARDS that can be used to initially screen limited function ventilators considered for mass respiratory failure stockpiles, and is intended to be combined with additional studies to defintively assess appropriateness for mass respiratory failure. Specifically, during this study we demonstrate that the SAVe I ventilator is unable to provide sufficient gas exchange, while the SAVe II, with several more functions, was able to support the same level of hypoxemic respiratory failure secondary to ALI/ARDS for one hour.

Dickson, Robert P; Hotchkin, David L; Lamm, Wayne JE; Hinkson, Carl; Pierson, David J; Glenny, Robb W; Rubinson, Lewis

2013-01-01

415

WASTE TREATMENT BUILDING VENTILATION SYSTEM DESCRIPTION DOCUMENT  

SciTech Connect

The Waste Treatment Building Ventilation System provides heating, ventilation, and air conditioning (HVAC) for the contaminated, potentially contaminated, and uncontaminated areas of the Monitored Geologic Repository's (MGR) Waste Treatment Building (WTB). In the uncontaminated areas, the non-confinement area ventilation system maintains the proper environmental conditions for equipment operation and personnel comfort. In the contaminated and potentially contaminated areas, in addition to maintaining