scholarly journals Assessment of heterogeneous airway constriction in dogs: a structure-function analysis

2009 ◽  
Vol 106 (2) ◽  
pp. 520-530 ◽  
Author(s):  
David W. Kaczka ◽  
Robert H. Brown ◽  
Wayne Mitzner
Keyword(s):  
Inverse Modeling ◽  
Function Analysis ◽  
Continuous Distribution ◽  
Structural Heterogeneity ◽  
Forced Oscillations ◽  
Computed Tomographic ◽  
Airway Constriction ◽  
Anesthetized Dogs ◽  
The Mean ◽  
System 1

Obstructive lung diseases are often characterized by heterogeneous patterns of bronchoconstriction, although specific relationships between structural heterogeneity and lung function have yet to be established. We measured respiratory input impedance (Zrs) in eight anesthetized dogs using broadband forced oscillations at baseline and during intravenous methacholine (MCh) infusion. We also obtained high-resolution computed tomographic (HRCT) scans in 4 dogs and identified 20–30 individual airway segments in each animal. The Zrs spectra and HRCT images were obtained before and 5 min following a deep inspiration (DI) to 35 cmH2O. Each Zrs spectrum was fitted with two different models of the respiratory system: 1) a lumped airways model consisting of a single airway compartment, and 2) a distributed airways model incorporating a continuous distribution of airway resistances. For the latter, we found that the mean level and spread of airway resistances increased with MCh dose. Whereas a DI had no effect on average airway resistance during MCh infusion, it did increase the level of airway heterogeneity. At baseline and low-to-moderate doses of MCh, the lumped airways model was statistically more appropriate to describe Zrs in the majority of dogs. At the highest doses of MCh, the distributed airways model provided a superior fit in half of the dogs. There was a significant correlation between heterogeneity assessed with inverse modeling and the standard deviation of airway diameters obtained from HRCT. These data demonstrate that increases in airway heterogeneity as assessed with forced oscillations and inverse modeling can be linked to specific structural alterations in airway diameters.

Observation of the Pulp Chamber of Maxillary First Premolars: A Micro-computed Tomographic Study

2020 ◽  
Vol 16 (3) ◽  
pp. 224-230
Author(s):  
Gozde Serindere ◽  
Ceren Aktuna Belgin ◽  
Kaan Orhan
Keyword(s):  
Root Canal ◽  
Age Groups ◽  
Slice Thickness ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Pulp Chamber ◽  
Anatomical Structures ◽  
Computed Tomographic ◽  
The Mean ◽  
Chamber Floor

Background: There are a few studies about the evaluation of maxillary first premolars internal structure with micro-computed tomography (micro-CT). The aim of this study was to assess morphological features of the pulp chamber in maxillary first premolar teeth using micro- CT. Methods: Extracted 15 maxillary first premolar teeth were selected from the patients who were in different age groups. The distance between the pulp orifices, the diameter of the pulp and the width of the pulp chamber floor were measured on the micro-CT images with the slice thickness of 13.6 µm. The number of root canal orifices and the presence of isthmus were evaluated. Results: The mean diameter of orifices was 0.73 mm on the buccal side while it was 0.61 mm on palatinal side. The mean distance between pulp orifices was 2.84 mm. The mean angle between pulp orifices was -21.53°. The mean height of pulp orifices on the buccal side was 4.32 mm while the mean height of pulp orifices on the palatinal side was 3.56 mm. The most observed shape of root canal orifices was flattened ribbon. No isthmus was found in specimens. Conclusion: Minor anatomical structures can be evaluated in more detail with micro-CT. The observation of the pulp cavity was analyzed using micro-CT.

scholarly journals Investigation of the Structural Heterogeneity and Corrosion Performance of the Annealed Fe-Based Metallic Glasses

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 929
Author(s):  
Dandan Liang ◽  
Jo-Chi Tseng ◽  
Xiaodi Liu ◽  
Yuanfei Cai ◽  
Gang Xu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Passive Film ◽  
Metallic Glasses ◽  
Function Analysis ◽  
Supercooled Liquid ◽  
Structural Heterogeneity ◽  
Coordination Shell ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Corrosion Performance

This study investigated the structural heterogeneity, mechanical property, electrochemical behavior, and passive film characteristics of Fe–Cr–Mo–W–C–B–Y metallic glasses (MGs), which were modified through annealing at different temperatures. Results showed that annealing MGs below the glass transition temperature enhanced corrosion resistance in HCl solution owing to a highly protective passive film formed, originating from the decreased free volume and the shrinkage of the first coordination shell, which was found by pair distribution function analysis. In contrast, the enlarged first coordination shell and nanoscale crystal-like clusters were identified for MGs annealed in the supercooled liquid region, which led to a destabilized passive film and thereby deteriorated corrosion resistance. This finding reveals the crucial role of structural heterogeneity in tuning the corrosion performance of MGs.

Varietal reactions of Trifolium subterraneum L. to Phaseolus virus 2 Pierce.

1954 ◽  
Vol 5 (4) ◽  
pp. 598 ◽  
Author(s):  
EM Hutton ◽  
JW Peak
Keyword(s):  
Trypan Blue ◽  
Continuous Distribution ◽  
Systemic Infection ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Epidermal Cells ◽  
Severe Strain ◽  
Resistant Varieties ◽  
Lethal Reaction ◽  
The Mean

A number of varieties of subterranean clover (Trifolium subterraneum L.) were tested with a severe strain of Phaseolus virus 2 Pierce. Northam First Early, Dwalganup, and Pink Flowered gave lethal necrotic reactions while the rest developed mottles and chlorosis of different degrees of intensity. Reductions in the mean fresh weights of plants of five subterranean clover varieties ranged from 26.1 to 76.7 per cent. Epidermal cells of mottled leaves contained irregular aggregates of viroplasts stained by treatment with phloxine-trypan blue. Viroplasts in young tip leaves did not stain if the plants were held at temperatures below 44.6°F while those in mature basal leaves were not so affected. The lethal-reactors Northam First Early, Dwalganup, and Pink Flowered were resistant in the field to Phaseolus virus 2. With hand inoculation in the glass-house an average of 10 per cent. of plants of these varieties remained free from systemic infection, whereas all the plants of mottle-reacting varieties became systemically infected. The virus had a discontinous distribution in plants of lethal-reactors, compared with a continuous distribution in those of mottle-reactors such as Mount Barker. The lethal reaction is heritable in a dominant fashion in most crosses, so that the development of desirable new virus- resistant varieties is possible.

scholarly journals Probing airway conditions governing ventilation defects in asthma via hyperpolarized MRI image functional modeling

2009 ◽  
Vol 106 (4) ◽  
pp. 1293-1300 ◽  
Author(s):  
Lisa Campana ◽  
Jennifer Kenyon ◽  
Sanaz Zhalehdoust-Sani ◽  
Yang-Sheng Tzeng ◽  
Yanping Sun ◽  
...  
Keyword(s):  
Computational Models ◽  
Maximum Size ◽  
Measured Data ◽  
Lung Imaging ◽  
Small Airways ◽  
Functional Modeling ◽  
Airway Constriction ◽  
The Mean ◽  
Hyperpolarized Mri ◽  
Central Airway

Image functional modeling (IFM) has been introduced as a method to simultaneously synthesize imaging and mechanical data with computational models to determine the degree and location of airway constriction in asthma. Using lung imaging provided by hyperpolarized 3He MRI, we advanced our IFM method to require matching not only to ventilation defect location but to specific ventilation throughout the lung. Imaging and mechanical data were acquired for four healthy and four asthmatic subjects pre- and postbronchial challenge. After provocation, we first identified maximum-size airways leading exclusively to ventilation defects and highly constricted them. Constriction patterns were then found for the remaining airways to match mechanical data. Ventilation images were predicted for each pattern, and visual and statistical comparisons were done with measured data. Results showed that matching of ventilation defects requires severe constriction of small airways. The mean constriction of such airways leading to the ventilation defects needed to be 70–80% rather than fully closed. Also, central airway constriction alone could not account for dysfunction seen in asthma, so small airways must be involved.

scholarly journals 111In-oxine platelet survivals in thrombocytopenic infants

Blood ◽  
1987 ◽  
Vol 70 (3) ◽  
pp. 652-656
Author(s):  
V Castle ◽  
G Coates ◽  
JG Kelton ◽  
M Andrew
Keyword(s):  
Life Span ◽  
Function Analysis ◽  
Screening Tests ◽  
Severe Thrombocytopenia ◽  
Common Occurrence ◽  
Platelet Volume ◽  
Platelet Destruction ◽  
Percent Recovery ◽  
The Mean ◽  
Full Body

Thrombocytopenia is a common occurrence (20%) in sick neonates, but the causes have not been well studied. In this report we demonstrate that thrombocytopenia in the neonate is characterized by increased platelet destruction as shown by shortened homologous 111In-oxine-labeled platelet life spans. Thirty-one prospectively studied thrombocytopenic neonates were investigated by measuring the 111In-labeled platelet life span, platelet-associated IgG (PAIgG), and coagulation screening tests. In every infant, the thrombocytopenia was shown to have a destructive component since the mean platelet life span was significantly shortened to 65 +/- 6 (mean +/- SEM) hours with a range of one to 128 hours compared with adult values (212 +/- 8; range, 140 to 260; gamma function analysis). The platelet survival was directly related to the lowest platelet count and inversely related to both the highest mean platelet volume and duration of the thrombocytopenia. In 22 infants the percent recovery of the radiolabeled platelets was less than 50%, which suggested that increased sequestration also contributed to the thrombocytopenia. Infants with laboratory evidence of disseminated intravascular coagulation (n = 8) or immune platelet destruction evidenced by elevated levels of PAIgG (n = 13) had even shorter platelet survivals and a more severe thrombocytopenia compared with the ten infants in whom an underlying cause for the thrombocytopenia was not apparent. Full-body scintigraphic images obtained in 11 infants showed an increased uptake in the spleen and liver, with a spleen-to- liver ratio of 3:1. This study indicates that thrombocytopenia in sick neonates is primarily destructive, with a subgroup having evidence of increased platelet sequestration.

scholarly journals DISTRIBUTION OF NONSTRUCTURAL VARIATION ALONG THREE CHROMOSOME ARMS BETWEEN WHEAT CULTIVARS CHINESE SPRING AND CHEYENNE

Genetics ◽  
1984 ◽  
Vol 106 (2) ◽  
pp. 309-324
Author(s):  
Anne Crossway ◽  
Jan Dvořák
Keyword(s):  
Chinese Spring ◽  
Continuous Distribution ◽  
Inbred Lines ◽  
Wheat Cultivars ◽  
Chromosome Variation ◽  
Homologous Chromosomes ◽  
Ring Bivalents ◽  
Chromosome Arm ◽  
Parental Inbred ◽  
The Mean

ABSTRACT Metaphase I (MI) pairing of wheat homologous chromosomes is usually reduced in hybrids between cultivars relative to the parental inbred lines. Previous work suggested that this phenomenon is caused by polymorphism in nucleotide sequences (nonstructural chromosome variation) among wheat cultivars. The present work investigated the distribution of this variation along three selected chromosome arms between cultivars Chinese Spring and Cheyenne. Chinese Spring ditelosomics 3Aq, 6Ap and 6Bp were crossed with disomic substitutions of Cheyenne chromosomes 3A, 6A and 6B in Chinese Spring, respectively. The resulting F1 plants, called substituted monotelodisomics, were crossed with the respective Chinese Spring monosomics, producing potentially "recombinant" substituted monosomics. When these "recombinant" chromosomes were combined with the parental Chinese Spring telosomes, marked reductions in mean telosome-pairing frequency were found compared with the corresponding Chinese Spring monotelodisomics. The mean pairing frequencies of the "recombinant" chromosomes showed a continuous distribution between those of the substituted and Chinese Spring monotelodisomics. The results suggest that the nonstructural variation that reduces MI pairing between chromosomes of different wheat cultivars is not localized in a specific site but distributed along each chromosome arm. Little variation was found among monotelodisomics for either the number of ring bivalents per cell or the number of univalents other than those constituting the heteromorphic pair. This implies that the reductions in MI pairing between the Cheyenne and Chinese Spring chromosomes are caused by something residing within these specific chromosomes that does not affect the pairing of the remaining Chinese Spring chromosomes in the same cell. Furthermore, the absence of parental types among the "recombinant"-substituted monotelodisomics suggests that the sequences involved in the variation studied here are capable of converting heterohomologous chromosomes to something intermediate in nature in the span of only a single generation.

Establishment of the Wake Behind a Disk

1964 ◽  
Vol 86 (4) ◽  
pp. 869-880 ◽  
Author(s):  
Thomas Carmody
Keyword(s):  
Shear Stress ◽  
Ambient Pressure ◽  
Continuous Distribution ◽  
Flow Characteristics ◽  
Graphical Form ◽  
Stress Distributions ◽  
Mean Velocity ◽  
Pressure Distributions ◽  
Energy Relationships ◽  
The Mean

An air-tunnel study of the establishment of the wake behind a disk at a Reynolds number of approximately 7 × 104 was undertaken. On the basis of the measured data, such a wake is fully established, that is, similarity profiles of the flow characteristics are formed, within 15 diameters of the disk, and approximately 95 percent of the transfer of energy from the mean motion to the turbulence motion takes place within 3 diameters of the disk, in the region of the mean standing eddy. The measured mean ambient-pressure and mean total-pressure distributions, mean velocity distributions, turbulence-intensity and shear-stress distributions, and the mean streamline pattern are presented in graphical form, as are the quantitative balances of the integrated momentum and mean-energy relationships. A stream function consisting of a continuous distribution of doublets is introduced to extend the radial limit of understanding of the flow characteristics to a very large if not infinite radius. Considerable attention is given to the problem of obtaining and interpreting turbulence shear-stress data immediately downstream from the point of flow separation. The applicability of a local diffusion coefficient or virtual viscosity of the Boussinesq or Prandtl type for relating the turbulence shear stress to the radial gradient of mean axial velocity is discussed. The Bernoulli sum and the energy changes along individual streamlines investigated in an associated study are incorporated herein to obtain a quantitative estimate of the local errors involved in the turbulence-shear-stress measurements.

Use of the Vertical Profunda Artery Perforator Flap to Capture the Dominant Perforator: A Cadaver Dissection and Imaging Study

2021 ◽  
Author(s):  
Jourdain D. Artz ◽  
Elisa K. Atamian ◽  
Clairissa Mulloy ◽  
Mark W. Stalder ◽  
Jamie Zampell ◽  
...  
Keyword(s):  
Donor Site ◽  
Perforator Flap ◽  
Imaging Study ◽  
Vessel Diameter ◽  
Pubic Tubercle ◽  
Computed Tomographic ◽  
Flap Design ◽  
Preoperative Magnetic Resonance ◽  
The Mean ◽  
Artery Perforator

Abstract Introduction While the originally described transverse profunda artery perforator (tPAP) flap is designed to capture the first profunda perforator, our group hypothesized the dominant perforator may not always be captured in this configuration. This study maps the location of dominant profunda perforators using imaging and cadaveric dissections to determine the probability of capturing dominant perforators with the transverse flap design versus the vertical PAP (vPAP) variant. Methods Fifty preoperative magnetic resonance angiogram or computed tomographic angiogram scans (100 total extremities) were examined from autologous breast reconstruction patients between 2015 and 2019. Profunda perforator characteristics that were examined included the distance from the pubic tubercle to the infragluteal fold (IGF), the distance of the perforators from the IGF, distance posterior to the gracilis, the diameter of the perforator at fascial exit, and total number of perforators present. Profunda perforator dissection was performed in 18 cadaveric extremities. Analysis included mean distance from pubic tubercle, distance posterior to the gracilis, diameter at fascial exit, and total number of perforators. Results In imaging analysis, the mean distance from the IGF to the fascial exit of all dominant perforators was 7.04 cm. The mean diameter of the dominant perforator at the fascial exit was 2.61 mm. Twenty-six thighs (26%) demonstrated dominant perforators that exited the fascia greater than 8 cm below the IGF. In cadaver dissections, the mean distance from the pubic tubercle to the fascial exit of all the dominant perforators was 10.17 cm. Nine cadaver specimens (50%) demonstrated perforators that exited the fascia greater than 8 cm below the estimated IGF. Conclusion The dominant perforator can often be missed in the traditional tPAP design. The vPAP incorporates multiple perforators with a long pedicle, excellent vessel diameter, and favorable donor-site.

Changes in brain surface pH during acute isocapnic metabolic acidosis and alkalosis

1981 ◽  
Vol 51 (2) ◽  
pp. 276-281 ◽  
Author(s):  
S. Javaheri ◽  
A. Clendening ◽  
N. Papadakis ◽  
J. S. Brody
Keyword(s):  
Cerebrospinal Fluid ◽  
Metabolic Acidosis ◽  
Interstitial Fluid ◽  
Acid Base ◽  
Surface Ph ◽  
Brain Surface ◽  
Arterial Blood ◽  
Anesthetized Dogs ◽  
The Mean ◽  
The Brain

It has been thought that the blood-brain barrier is relatively impermeable to changes in arterial blood H+ and OH- concentrations. We have measured the brain surface pH during 30 min of isocapnic metabolic acidosis or alkalosis induced by intravenous infusion of 0.2 N HCl or NaOH in anesthetized dogs. The mean brain surface pH fell significantly by 0.06 and rose by 0.04 pH units during HCl or NaOH infusion, respectively. Respective changes were also observed in the calculated cerebral interstitial fluid [HCO-3]. There were no significant changes in cisternal cerebrospinal fluid acid-base variables. It is concluded that changes in arterial blood H+ and OH- concentrations are reflected in brain surface pH relatively quickly. Such changes may contribute to acute respiratory adaptations in metabolic acidosis and alkalosis.

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