scholarly journals Effects of long-term, high-altitude hypoxia on the capillarity of the ovine fetal heart

1999 ◽  
Vol 277 (2) ◽  
pp. H756-H762 ◽  
Author(s):  
A. M. Lewis ◽  
O. Mathieu-Costello ◽  
P. J. McMillan ◽  
R. D. Gilbert
Keyword(s):  
Right Ventricle ◽  
High Altitude ◽  
Capillary Density ◽  
Volume Density ◽  
Capillary Diameter ◽  
Sectional Area ◽  
Anisotropy Coefficient ◽  
Capillary Length ◽  
Cross Sectional ◽  
The Right

To determine the effect of chronic hypoxia on myocardial capillarity, we exposed pregnant ewes to an altitude of 3,820 m from day 30 to day 139 of gestation and compared the fetus to low-altitude (∼300 m) controls. We hypothesized that capillarity would increase in the hypoxic myocardium to optimize oxygen and metabolite flux to hypoxic tissues. Fetal hearts were fixed by retrograde aortic perfusion and processed for microscopy and stereological evaluation. Fiber cross-sectional area and capillary density were measured and standardized to sarcomere length. Capillary volume density and capillary diameter were measured, capillary-to-fiber ratio and capillary length density were calculated, and the capillary anisotropy coefficient was obtained from a table of known values. Capillary-to-fiber ratio, capillary volume density, and the capillary anisotropy coefficient were not different between hypoxia and control groups. Capillary diameter was significantly larger in the right compared with the left ventricle of hypoxic but not control hearts; fiber cross-sectional area tended to be larger in the right ventricle of both groups, but this was not significant. As a result of larger fiber size, capillary density and capillary length density were significantly smaller in the right ventricle of hypoxic but not control fetal hearts. Contrary to our hypothesis, the ovine fetus does not show morphological adaptation in the myocardium after ∼109 days of high-altitude hypoxic stress.

Ultrastructure of Aerobic Muscle in Antarctic Fishes may Contribute to Maintenance Of Diffusive Fluxes

1990 ◽  
Vol 150 (1) ◽  
pp. 205-220 ◽  
Author(s):  
RICHARD L. LONDRAVILLE ◽  
BRUCE D. SIDELL
Keyword(s):  
Muscle Metabolism ◽  
Antarctic Fish ◽  
Oxygen Demand ◽  
Capillary Density ◽  
Volume Density ◽  
Active Species ◽  
Published Data ◽  
Diffusion Distance ◽  
Capillary Length ◽  
Diffusive Fluxes

Quantitative ultrastructural analyses were performed on red (oxidative) and white (glycolytic) skeletal muscles from two species of antarctic fish to identify features of subcellular structure that may be related to muscle metabolism at cold body temperature. Trematomus newnesi (Boulenger) is an active pelagic species and Notothenia gibberifrons (Lönnberg) is a sluggish bottom-dweller. White fibres of both species are poorly vascularized [capillary density, NA(c,f), for T. newnesi 73.9±11.3mm−2; for N. gibberifrons is 76.0±14.1mm−2], and have low percentages of cell volume occupied by mitochondria [volume density, Vv(mit,f), for T. newnesi is 0.014±0.005; for N. gibberifrons is 0.006±0.003]. Ultrastructure of oxidative fibres in both species resembles that of cold-acclimated temperate-zone fishes. Mitochondrial volume densities of red fibres reflect differences in ecotype between species [Vv(mit,f) for T. newnesi is 0.348±0.012; for N. gibberifrons is 0.249±0.007]. The less clustered array of mitochondria in oxidative fibres of T. newnesi compared with N. gibberifrons may support an equivalent flux of aqueous metabolites between mitochondrial and cytoplasmic compartments, despite a greater mean intracellular diffusion distance (τh) between these compartments in T. newnesi than in N. gibberifrons (τh=1.05±0.07μm and 0.77±0.06μm, respectively). Although Vv(mit.)) is higher in red fibres of the active species, capillary supply is less extensive [capillary length density, Jv(c,f), for T. newnesi is 481.3±49.0mm mm−3; N. gibberifrons is 696.3±33.7mm mm−3] and the maximal diffusion-distance for oxygen is greater in T. newnesi than in N. gibberifrons (Krogh's radius, R=26.3±1.64μm and 21.5±0.51μm, respectively). A mismatch appears to exist between oxygen supply [Jv(c,f)] and oxygen demand [Vv(mit,f)] in T. newnesi red fibres in view of published data for other fishes. The twofold higher volume density of lipid [Vv(lip,f)] in T. newnesi compared with N. gibberifrons may resolve this paradox [Vv(lip,f) is 0.026±0.002 and 0.012±0.004, respectively]. Because oxygen is at least four times more soluble in lipid than in aqueous cytoplasm, lipid may enhance oxygen flux through oxidative muscle and play a role similar to myoglobin in these myoglobin-poor fishes.

scholarly journals Sonographic Measurement of Cross-sectional Area of the Median Nerve in Academic Dentists Without Symptoms or Signs of Carpal Tunnel Syndrome

2018 ◽  
Vol 35 (2) ◽  
pp. 105-111
Author(s):  
Akram Asbeutah ◽  
Mohsen Dashti ◽  
Abdullah AlMajran ◽  
Aref Ghayyath
Keyword(s):  
Median Nerve ◽  
Statistical Significance ◽  
Working Hours ◽  
Cross Sectional Area ◽  
Dominant Hand ◽  
Sectional Area ◽  
Cross Sectional ◽  
Increased Risk ◽  
Bone Level ◽  
The Right

The objective was to evaluate the distribution of the cross-sectional area (CSA) and flattening ratio (FR) of the median nerve (MN) in asymptomatic academic dentists using ultrasonography (US). Fifty academic dentists underwent US of the MN in transverse section at the pisiform bone level and the CSA (mm2) and FR were measured bilaterally. A CSA of <10 mm2 was considered normal. Paired t-test showed no statistical significance between either hand for CSA and FR ( P> .05). Two independent t-tests showed significant statistical differences ( P= .023) between males and females in the right dominant hand for CSA. Linear correlation analysis showed no significant correlation between CSA and FR for number of years of experience or number of working hours per day in either hand ( P>.05). The CSA was abnormal in the right dominant hand in 20 (40%) of the subjects. These male academic dentists were at increased risk of having an enlarged MN without symptoms.

Sectional anatomy of the ventricular septal defect in double outlet right ventricle—correlation of magnetic resonance images from autopsied hearts with anatomic sections

1993 ◽  
Vol 3 (2) ◽  
pp. 118-123 ◽  
Author(s):  
Shi-Joon Yoo ◽  
Siew Yen Ho ◽  
Philip J. Kilner ◽  
Jeong-Wook Seo ◽  
Robert H. Anderson
Keyword(s):  
Ventricular Septal Defect ◽  
Right Ventricle ◽  
Septal Defect ◽  
Double Outlet Right Ventricle ◽  
Magnetic Resonance Images ◽  
Cross Sectional ◽  
Posterior Limb ◽  
Imaging Characteristics ◽  
Cross Sectional Imaging ◽  
The Right

AbstractA ventricular septal defect is, almost always, an integral part of double outlet right ventricle and has been classified into the subaortic, subpulmonary, doubly committed and non-committed varieties. This study was performed to correlate the cross-sectional imaging characteristics of such ventricular septal defect in double outlet right ventricles using pathological specimens. The extent and the orientation of the outlet septum were the most important in the differentiation of the four varieties of ventricular septal defect. In the subaortic variety, the outlet septum fused with the left anterior margin of the defect, this being marked by the anterior limb of the septomarginal trabeculation. In the subpulmonary variety, the outlet septum fused with the right posterior margin of the defect, this being the posterior limb of the septomarginal trabeculation. The outlet septum was vestigial in case with doubly committed defects. In those with non-committed defects, the defect was not shown in those images or sections which demonstrated the outlet septum.

Influences of physical conditioning and deconditioning on coronary vasculature of dogs

1978 ◽  
Vol 45 (4) ◽  
pp. 619-625 ◽  
Author(s):  
H. L. Wyatt ◽  
J. Mitchell
Keyword(s):  
Basement Membrane ◽  
Capillary Density ◽  
Cross Sectional Area ◽  
Membrane Thickness ◽  
Physical Conditioning ◽  
Sectional Area ◽  
Circumflex Artery ◽  
Cross Sectional ◽  
Coronary Vasculature ◽  
Basement Membrane Thickness

To investigate the effects of physical conditioning and deconditioning on the coronary vasculature, eight dogs were exercised by treadmill running. Five dogs were deconditioned by confinement in cages following the conditioning period. A technique was developed and validated for measuring circumflex coronary artery diameter from magnified projections of standardized coronary angiograms. Myocardial capillary density, perimeter, and basement membrane thickness were determined from electron microscopy of serial ventricular septal biopsy samples. Physical conditioning caused a small but statistically significant increase in cross-sectional area of the circumflex artery. Although physical conditioning caused no statistically significant changes in the myocardial capillaries, trends were apparent for increases in density and perimeter of myocardial capillaries and a decrease in basement membrane thickness. Physical deconditioning caused statistically significant reductions in cross-sectional area of the circumflex artery and in myocardial capillary density but little change in perimeter or basement membrane thickness of myocardial capillaries. The results suggest that physical conditioning may be associated with an improvement in coronary vascular capacity which may regress rapidly with deconditioning.

Pulmonary atresia with intact ventricular septum in the fetus

1992 ◽  
Vol 2 (4) ◽  
pp. 367-376 ◽  
Author(s):  
Lindsey D. Allan ◽  
Andrew Cook
Keyword(s):  
Right Ventricle ◽  
Poor Prognosis ◽  
Pulmonary Atresia ◽  
Ventricular Septum ◽  
Fetal Life ◽  
Intact Ventricular Septum ◽  
Cross Sectional ◽  
The One ◽  
The Right ◽  
Echocardiographic Findings

AbstractThe objective of this study was to review the echocardiographic findings and autopsy correlates of pulmonary atresia with an intact ventricular septum when diagnosed during fetal life. All cases with this lesion (nearly 60) seen in the Perinatal Cardiology unit of Guy's Hospital since 1983 are part of this study. More than half of the cases were detected within the last two years, and all bar three were referred because of suspicion of a cardiac malformation detected on routine obstetric scanning. The cases were divided into two distinct groups. On the one hand were those with dilatation of the chambers of the right heart. These had a uniformly poor prognosis. Severe regurgitation of the tricuspid valve was a characteristic feature. On the other hand were the cases with cavitary hypoplasia due to mural overgrowth. Direct measurements of pressure in one such case revealed suprasystemic values in the right ventricle. Although contemplated, fetal intervention proved impossible. Autopsy revealed cases with either valvar or infundibular atresia. In most cases diagnosed prior to 24 weeks of gestation, mothers opted for termination of pregnancy. All cases with dilatation of the right ventricle died. Of pregnancies which continued, only 30% of children are still alive, all but one being less than two years of age at present. The use of cross-sectional and Doppler echocardiography permits the accurate diagnosis of pulmonary atresia with an intact ventricular septum during fetal life. Autopsied cases showed strong correlation with the echocardiographic findings. The poor prognosis in most cases warrants consideration in the future of intervention during fetal life.

scholarly journals Influence of malformation of right coronary artery originating from the left sinus on the hemodynamic environment

2020 ◽  
Author(s):  
Mengyang Cong ◽  
Xingming Xu ◽  
Jianfeng Qiu ◽  
Shun Dai ◽  
Chuanzhi Chen ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Coronary Arteries ◽  
Right Coronary Artery ◽  
Clinical Symptoms ◽  
Element Model ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
The Cross ◽  
The Right

Abstract Background: The Anomalous origin of the Right Coronary Artery (RCA) from the Left Coronary artery sinus(AORL) is one of the abnormal origins of the coronary arteries. Most of these issues seldom have effects on human health, but some individuals may have symptoms such as myocardial ischaemia or even sudden death. Recently, researchers are studying AORL through clinical cases, but study based on computational fluid dynamics (CFD) is rarely seen. In this study, haemodynamic changes between normal origin of the RCA and AORL are compared according to numerical simulation results.Methods: Realistic three-dimensional models of 16 normal right coronary arteries and 26 abnormal origins of the right coronary arteries were reconstructed, respectively. The blood flow was numerically simulated using software ANSYS. This study involves one-way fluid-solid coupling finite element model in which the blood is assumed to be incompressible Newtonian fluid, and the vessel is assumed to be isotropic, linear elastic material.Results: The differences of the cross-sectional area at the inlet between the normal group and the abnormal group was significant ( P <0.0001). There were significant differences in the volumetric flow ( P <0.0001) and the pressure ( P =0.0001). There were positive correlations with the ratio of the cross-sectional area of the RCA to the inlet area of the ascending aorta (AAO) and the ratio of the inlet volumetric flow of the RCA to the volumetric flow of the AAO, in both the normal ( P =0.0001, r=0.8198) and abnormal ( P =0.0199, r=0.4925) group.Conclusion: This study shows that the cross-sectional area of the inlet of AORL may cause ischaemia symptoms, and the results may contribute to the further understanding of the clinical symptoms of AORL based on the haemodynamics.

scholarly journals Analysis of Flame Propagation in Small Adiabatic Tubes Characterized by Different Degrees of the End Opening

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Artur N. Gutkowski ◽  
Zbigniew Cebulski
Keyword(s):  
Thermal Expansion ◽  
Pressure Gradient ◽  
Flame Propagation ◽  
Propagation Speed ◽  
Flame Speed ◽  
Exponential Dependence ◽  
Sectional Area ◽  
Cross Sectional ◽  
Frictional Forces ◽  
The Right

Abstract In the present work, we study numerically freely propagating flame in the stoichiometric propane-air mixture. The adiabatic small tubes with one end fully open and the second one characterized by different degrees of opening are examined. The degree of opening of the tubes was equal to: 0% (completely closed), 25%, 50%, 75% and 100% (fully opened) of the tube cross-sectional area. Several mechanisms, such as thermal expansion of the burned gas that can leave the tube freely (fully opened left end of the tube), frictional forces and movement of the unburned mixture generated by a pressure gradient, occur simultaneously during flame propagation. As a result, a nearly-exponential dependence of flame propagation speed as a function of time is observed. For fully open right end (100%), normalized flame speed reaches about 75–80 at the end of the tubes. By partially closing the right end, this effect is delayed and reduced – for 25% of the opening normalized flame speed is about 20 for all tube diameters.

Capillary growth and geometry during long-term hypertension and myocardial hypertrophy in dogs

1991 ◽  
Vol 261 (4) ◽  
pp. H1011-H1018 ◽  
Author(s):  
R. J. Tomanek ◽  
T. J. Wessel ◽  
D. G. Harrison
Keyword(s):  
Volume Density ◽  
Left Ventricular ◽  
Capillary Length ◽  
Cross Sectional ◽  
Orientation Degree ◽  
Capillary Growth ◽  
Lv Mass ◽  
Intercapillary Distance ◽  
Capillary Bed

Angiogenic response of the myocardial capillary bed to long-term (7 mo) renovascular hypertension (one-kidney, one-clip) was assessed in eight mongrel dogs and compared with seven control dogs. Image analyses of histological sections from four transmural specimen sites of left ventricular (LV) free wall were performed. While mean cross-sectional cardiocyte area increased in all transmural layers (epi-endo) in dogs with LV hypertrophy (LVH), the greatest increases occurred in the inner layers. Although capillary length density was significantly lower in two of the four transmural regions of LVH dogs, these decrements were much less than the lateral expansion of cardiocytes as indicated by cross-sectional areas. Calculations of total capillary length indicate that approximately one-fifth of the capillary bed in LVH dogs was formed during the 7-mo period of hypertension in hypertrophied hearts. Capillary volume and surface densities in LVH dogs decreased to a greater extent due to a larger population of capillaries with lumen diameters less than 4 microns. Capillary volume density in LVH dogs was remarkably similar across the wall despite large transmural differences in cardiocyte hypertrophy. LVH did not alter the log SD of capillary domains, a measure of the heterogeneity of spacing, or capillary orientation (degree or anisotropy). These data support several important conclusions regarding long-term hypertension-induced LVH in dogs. First, although capillary growth does not fully compensate for the increase in LV mass, a myriad of new capillaries are formed as indicated by a substantial increase in total capillary length. This growth minimizes the increase in intercapillary distance characteristic of LVH.(ABSTRACT TRUNCATED AT 250 WORDS)

Compensated coronary microvascular growth in senescent rats with thyroxine-induced cardiac hypertrophy

1995 ◽  
Vol 268 (1) ◽  
pp. H419-H425 ◽  
Author(s):  
R. J. Tomanek ◽  
P. M. Connell ◽  
C. A. Butters ◽  
R. J. Torry
Keyword(s):  
Young Adult ◽  
Cardiac Hypertrophy ◽  
Coronary Vessels ◽  
Weight Ratio ◽  
Volume Density ◽  
Heart Weight ◽  
Age Group ◽  
Capillary Length ◽  
Adult Rats ◽  
Cross Sectional

We tested the hypothesis that coronary angiogenesis in response to chronic thyroxine (T4) treatment is not limited by age. Male Fischer 344 rats aged either 8 (young adult) or 24 (senescent) mo were studied after receiving either L-thyroxine (0.2 mg/kg sc) or vehicle for 2 mo. Heart weight-to-body weight ratio, compared with age-matched controls, increased by 47 and 44% in 8- and 24-mo T4 groups, respectively. Maximal myocardial perfusion per unit mass, measured in diastole-arrested, maximally dilated, isolated hearts, was similar in T4 rats and their age group controls; however, flow tended to be lower in senescent than in young adult rats. Thus the cross-sectional area of the coronary vessels grew in proportion to the increase in cardiac mass. Morphometric analyses, based on image analysis, showed that capillary length density was slightly lower in the midmyocardium but not the epimyocardium of the 24-mo T4 group compared with their age group controls. However, volume density, surface density, and intercapillary distance were not influenced by T4 treatment and the presence of cardiac hypertrophy. We conclude that in this model of cardiac hypertrophy 1) coronary vessel growth parallels the increase in ventricular mass, 2) capillaries grow by proliferation and an increase in diameter, and 3) vascular growth is not notably compromised during senescence.

scholarly journals Structural and functional alterations of the tracheobronchial tree after left upper pulmonary lobectomy for lung cancer

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Qingtao Gu ◽  
Shouliang Qi ◽  
Yong Yue ◽  
Jing Shen ◽  
Baihua Zhang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Main Bronchus ◽  
Tracheobronchial Tree ◽  
Sectional Area ◽  
Pulmonary Lobectomy ◽  
Airflow Velocity ◽  
Cross Sectional ◽  
Lobar Bronchus ◽  
Cfd Method ◽  
The Right

Abstract Background Pulmonary lobectomy has been a well-established curative treatment method for localized lung cancer. After left upper pulmonary lobectomy, the upward displacement of remaining lower lobe causes the distortion or kink of bronchus, which is associated with intractable cough and breathless. However, the quantitative study on structural and functional alterations of the tracheobronchial tree after lobectomy has not been reported. We sought to investigate these alterations using CT imaging analysis and computational fluid dynamics (CFD) method. Methods Both preoperative and postoperative CT images of 18 patients who underwent left upper pulmonary lobectomy are collected. After the tracheobronchial tree models are extracted, the angles between trachea and bronchi, the surface area and volume of the tree, and the cross-sectional area of left lower lobar bronchus are investigated. CFD method is further used to describe the airflow characteristics by the wall pressure, airflow velocity, lobar flow rate, etc. Results It is found that the angle between the trachea and the right main bronchus increases after operation, but the angle with the left main bronchus decreases. No significant alteration is observed for the surface area or volume of the tree between pre-operation and post-operation. After left upper pulmonary lobectomy, the cross-sectional area of left lower lobar bronchus is reduced for most of the patients (15/18) by 15–75%, especially for 4 patients by more than 50%. The wall pressure, airflow velocity and pressure drop significantly increase after the operation. The flow rate to the right lung increases significantly by 2–30% (but there is no significant difference between each lobe), and the flow rate to the left lung drops accordingly. Many vortices are found in various places with severe distortions. Conclusions The favorable and unfavorable adaptive alterations of tracheobronchial tree will occur after left upper pulmonary lobectomy, and these alterations can be clarified through CT imaging and CFD analysis. The severe distortions at left lower lobar bronchus might exacerbate postoperative shortness of breath.

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