Myogenic response of rat femoral small arteries in relation to wall structure and [Ca2+]i

2002 ◽  
Vol 283 (1) ◽  
pp. H118-H125 ◽  
Author(s):  
Vladimir V. Matchkov ◽  
Olga S. Tarasova ◽  
Michael J. Mulvany ◽  
Holger Nilsson
Keyword(s):  
Intracellular Calcium ◽  
External Iliac Artery ◽  
Wall Stress ◽  
Calcium Sensitivity ◽  
Contralateral Side ◽  
Cross Sectional Area ◽  
Wall Structure ◽  
Sectional Area ◽  
Cross Sectional ◽  
Small Arteries

The present study investigated the influence of media thickness on myogenic tone and intracellular calcium concentration ([Ca2+]i) in rat skeletal muscle small arteries. A ligature was loosely tied around one external iliac artery of 5-wk-old spontaneously hypertensive rats. At 18 wk of age, femoral artery blood pressure was 102 ± 11 mmHg ( n = 15) on the ligated side and 164 ± 6 mmHg ( n = 15) on the contralateral side. Small arteries feeding the gracilis muscle had a reduced media cross-sectional area and a reduced media-to-lumen ratio on the ligated side, where also the range of myogenic constriction was shifted to lower pressures. However, when expressed as a function of wall stress, diameter responses were nearly identical. [Ca2+]i was higher in vessels from the ligated hindlimb at pressures above 10 mmHg, but vasoconstriction was not accompanied by changes in [Ca2+]i. Thus the myogenic constriction here seems due primarily to changes in intracellular calcium sensitivity, which are determined mainly by the force per cross-sectional area of the wall and therefore altered by changes in vascular structure.

Effect of hindlimb unloading on rat soleus fiber force, stiffness, and calcium sensitivity

1995 ◽  
Vol 79 (5) ◽  
pp. 1796-1802 ◽  
Author(s):  
K. S. McDonald ◽  
R. H. Fitts
Keyword(s):  
Time Course ◽  
Fiber Diameter ◽  
Isometric Force ◽  
Calcium Sensitivity ◽  
Cross Sectional Area ◽  
Hindlimb Unloading ◽  
Sectional Area ◽  
Cross Sectional ◽  
Control Value ◽  
Cross Bridges

The purpose of this study was to examine the time course of change in soleus muscle fiber peak force (N), tension (Po, kN/m2), elastic modulus (Eo), and force-pCa and stiffness-pCa relationships. After 1, 2, or 3 wk of hindlimb unloading (HU), single fibers were isolated and placed between a motor arm and a transducer, and fiber diameter, peak absolute force, Po, Eo, and force-pCa and stiffness-pCa relationships were characterized. One week of HU resulted in a significant reduction in fiber diameter (68 +/- 2 vs 57 +/- 1 microns), force (3.59 +/- 0.15 vs. 2.19 +/- 0.12 x 10(-4) N), Po (102 +/- 4 vs. 85 +/- 2 kN/m2), and Eo (1.96 +/- 0.12 vs. 1.37 +/- 0.13 x 10(7) N/m2), and 2 wk of HU caused a further decline in fiber diameter (45 +/- 1 microns), force (1.31 +/- 0.06 x 10(-4) N), and Eo (0.96 +/- 0.09 x 10(7) N/m2). Although the mean fiber diameter and absolute force continued to decline through 3 wk of HU, Po recovered to values not significantly different from control. The Po/Eo ratio was significantly increased after 1 (5.5 +/- 0.3 to 7.1 +/- 0.6), 2, and 3 wk of HU, and the 2-wk (9.5 +/- 0.4) and 3-wk (9.4 +/- 0.8) values were significantly greater than the 1-wk values. The force-pCa and stiffness-pCa curves were shifted rightward after 1, 2, and 3 wk of HU. At 1 wk of HU, the Ca2+ sensitivity of isometric force, assessed by Ca2+ concentration required for half-maximal force, was increased from the control value of 1.83 +/- 0.12 to 2.30 +/- 0.10 microM. In conclusion, after HU, the decrease in soleus fiber Po can be explained by a reduction in the number of myofibrillar cross bridges per cross-sectional area. Our working hypothesis is that the loss of contractile protein reduces the number of cross bridges per cross-sectional area and increases the filament lattice spacing. The increased spacing reduces cross-bridge force and stiffness, but Po/Eo increases because of a quantitatively greater effect on stiffness.

Optimization of High Concrete Retaining Wall Structure

2013 ◽  
Vol 357-360 ◽  
pp. 597-603
Author(s):  
Su Yang Gao ◽  
Yan Chen ◽  
Yao Feng Xie ◽  
Wen Dong Lei ◽  
Kai Yin
Keyword(s):  
Cross Section ◽  
Optimization Design ◽  
Retaining Wall ◽  
Cross Sectional Area ◽  
Wall Structure ◽  
Sectional Area ◽  
Cross Sectional ◽  
Structure Selection ◽  
Great Height ◽  
The Stability

The height of vertical pier retaining wall is relatively larger in regions with great height of water. As the retaining wall becomes higher, the cross-sectional area of ordinary gravity pier structure becomes larger and foundation strength needs to be larger, thus there are some restrictions for traditional structure form. This research focuses on new structure forms of high concrete retaining wall and its optimization design for piers in regions with great height of water. This study establishes a nonlinear constrained mathematical model of pier high retaining wall structures. The objective function is cross-sectional area of the pier retaining wall which is restricted by the stability, bearing capacity of foundation and strength of cross-section of retaining wall. This model is solved by fmincon function from Matlab and the results present an economically reasonable cross-section form. This new selection is greatly significant to improve the stability of high concrete retaining wall and reduce the project cost. The new structure is successfully used in a port of Huaihe River and it can be a solution to pier structure selection problem in regions with great height of water in the future.

scholarly journals Evaluation of Sacrum Morphology in Patient with Developmental Dysplasia of the Hip for Iliosacral Screw Fixation

2021 ◽  
Author(s):  
Nazım Karahan ◽  
Ahmet Oztermeli ◽  
Ahmet Aktan
Keyword(s):  
Contralateral Side ◽  
Developmental Dysplasia ◽  
Cross Sectional Area ◽  
Control Group ◽  
Iliosacral Screw ◽  
Sectional Area ◽  
Cross Sectional ◽  
Screw Length ◽  
Significant Difference ◽  
Dysplasia Of The Hip

Abstract Background: The purpose of this study was to evaluate the patients with developmental dysplasia of the hip (DDH) in terms of sacroiliac anatomy to proper placement of iliosacral screws. Methods: We retrospectively reviewed computed tomography (CT) records of 96 patients who were referred to our clinic. We mainly divided the patients into 2 groups; the iliosacral joint on the same side with DDH evaluated in the DDH group and on the contralateral side with DDH evaluated in the control group. The presence of the five qualitative characteristics of sacral dysplasia evaluated according to Route in both groups. The DDH group divided into three subgroups according to Hartofilakidis and Rout classifications. The cross-sectional area, length of the osseous corridor, coronal and vertical angulation evaluated in both groups. Results: Sacral dysplasia observed %87.5 in the DDH group,%83.3 in the control groups. The DDH group also exhibited a significantly lower S1 cross-sectional area and S1 iliosacral screw length than the control group (p:0.018,p:0,027; respectively). No statistically significant difference was observed according to Hartofilakidis(p>0.05). According to Rout, the S1 iliosacral screw length of the normal and transient groups were found to be significantly higher than those of the dysplastic groups (p: 0.004, p:0.0001; respectively). The transient group also exhibited a significantly lower S1 iliosacral screw length than the normal group (p:0.001). There were no significant differences in S1 and S2 axial and coronal angulation, S2 cross-sectional area, S2 iliosacral screw length in the DDH groups (p>0.05) Conclusion: When iliosacral screw is planned for patients with unilateral DDH, surgeons should consider that there are high rates of dysplastic sacral changes, differences in S1 cross sectional area and iliosacral screw length compared to the opposite side, and asymmetric sacral dysplastic changes in the upper sacrum.

Long-term persistence of enlarged motor units in partially denervated hindlimb muscles of cats

1990 ◽  
Vol 64 (4) ◽  
pp. 1261-1269 ◽  
Author(s):  
A. R. Luff ◽  
K. Torkko
Keyword(s):  
Motor Units ◽  
Contralateral Side ◽  
Cross Sectional Area ◽  
Type I ◽  
Sectional Area ◽  
Motor Axons ◽  
Cross Sectional ◽  
Single Motor Units ◽  
Slow Twitch ◽  
Fast Twitch

1. It was the aim of this study to determine the effect that regenerating motor axons would have on enlarged or sprouted motor units that had been established for a relatively long time. 2. The fast-twitch flexor digitorum longus (FDL) and slow-twitch soleus were partially denervated by unilateral section of the L7 ventral root in 12-wk-old kittens. After 200+ days single motor units were isolated, and their isometric contractile properties were determined. FDL units were also tested for their resistance to fatigue and categorized as fast-twitch-fatigable (FF), fast-twitch-fatigue-resistant (FR), and slow-twitch-fatigue-resistant (S). 3. It had been established previously that regenerating motor axons via L7 returned to the experimental muscles by approximately 100 days. Therefore from 100 to 200 days it was assumed that the sprouted units would be in competition with the regenerating axons. The extent of the original denervations was variable and was estimated from the contralateral side. In soleus most denervations ranged from 83 to 99%; in FDL, from 37 to 81%. 4. In both soleus and FDL there was no evidence that the motor units had sprouted to any less extent than found previously. Within some soleus muscles the largest motor units were developing substantially more force than was expected. However, determination of mean fiber cross-sectional area from muscles frozen, sectioned, and prepared for histochemical analysis showed that this was attributable to increased mean cross-sectional area of the type I fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Pelvic Canal Narrowing Caused by Triple Pelvic Osteotomy in the Dog

1994 ◽  
Vol 07 (03) ◽  
pp. 110-113 ◽  
Author(s):  
D. L. Holmberg ◽  
M. B. Hurtig ◽  
H. R. Sukhiani
Keyword(s):  
Postoperative Complications ◽  
Pelvic Osteotomy ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Canal Width ◽  
Operative Complications ◽  
Post Operative Complications

SummaryDuring a triple pelvic osteotomy, rotation of the free acetabular segment causes the pubic remnant on the acetabulum to rotate into the pelvic canal. The resulting narrowing may cause complications by impingement on the organs within the pelvic canal. Triple pelvic osteotomies were performed on ten cadaver pelves with pubic remnants equal to 0, 25, and 50% of the hemi-pubic length and angles of acetabular rotation of 20, 30, and 40 degrees. All combinations of pubic remnant lengths and angles of acetabular rotation caused a significant reduction in pelvic canal-width and cross-sectional area, when compared to the inact pelvis. Zero, 25, and 50% pubic remnants result in 15, 35, and 50% reductions in pelvic canal width respectively. Overrotation of the acetabulum should be avoided and the pubic remnant on the acetabular segment should be minimized to reduce postoperative complications due to pelvic canal narrowing.When performing triple pelvic osteotomies, the length of the pubic remnant on the acetabular segment and the angle of acetabular rotation both significantly narrow the pelvic canal. To reduce post-operative complications, due to narrowing of the pelvic canal, overrotation of the acetabulum should be avoided and the length of the pubic remnant should be minimized.

DETERMINATION OF THE FUNCTION OF THE ROD’S CROSS-SECTIONAL AREA USING VIBRATION EIGENFREQUENCIES

2020 ◽  
Vol 0 (4) ◽  
pp. 19-24
Author(s):  
I.M. UTYASHEV ◽  
◽  
A.A. AITBAEVA ◽  
A.A. YULMUKHAMETOV ◽  
◽  
...  
Keyword(s):  
Cross Sectional Area ◽  
Variable Cross ◽  
Sectional Area ◽  
Longitudinal Vibrations ◽  
Cross Sectional ◽  
Method Error ◽  
Various Boundary Conditions ◽  
Elastic Fixation ◽  
Crosssectional Area

The paper presents solutions to the direct and inverse problems on longitudinal vibrations of a rod with a variable cross-sectional area. The law of variation of the cross-sectional area is modeled as an exponential function of a polynomial of degree n . The method for reconstructing this function is based on representing the fundamental system of solutions of the direct problem in the form of a Maclaurin series in the variables x and λ. Examples of solutions for various section functions and various boundary conditions are given. It is shown that to recover n unknown coefficients of a polynomial, n eigenvalues are required, and the solution is dual. An unambiguous solution was obtained only for the case of elastic fixation at one of the rod’s ends. The numerical estimation of the method error was made using input data noise. It is shown that the error in finding the variable crosssectional area is less than 1% with the error in the eigenvalues of longitudinal vibrations not exceeding 0.0001.

Changes in the parameters of nasal breathing and parameters of the upper respiratory tract during orthognathic operations in patients with II and III skeletal class of jaw anomalies

2020 ◽  
pp. 22-27
Author(s):  
S.Sh. Gammadaeva ◽  
M.I. Misirkhanova ◽  
A.Yu. Drobyshev
Keyword(s):  
Respiratory Tract ◽  
Nasal Cavity ◽  
Nasal Septum ◽  
Cross Sectional Area ◽  
Upper Respiratory Tract ◽  
Sectional Area ◽  
Nasal Breathing ◽  
Cross Sectional ◽  
Skeletal Class ◽  
Upper Respiratory

The study analyzed the functional parameters of nasal breathing, linear parameters of the nasal aperture, nasal cavity and nasopharynx, volumetric parameters of the upper airways in patients with II and III skeletal class of jaw anomalies before and after orthognathic surgery. The respiratory function of the nose was assessed using a rhinomanometric complex. According to rhinoresistometry data, nasal resistance and hydraulic diameter were assessed. According to the data of acoustic rhinometry, the minimum cross-sectional area along the internal valve, the minimum cross-sectional area on the head of the inferior turbinate and nasal septum and related parameters were estimated. According to the CBCT data, the state of the nasal septum, the inferior turbinates, the nasal aperture, the state of the nasal cavity, and the linear values of the upper respiratory tract (nasopharynx) were analyzed. The patients were divided into 4 groups according to the classification of the patency of the nasal passages by

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