Simulation on flexibility of the vascular stent and grey correlation analysis / 医用生物力学

Objective To analyze and compare the effects of structure parameters on synchronous motor ability between the blood vessel and stent after stent implantation by using finite element method and grey correlation theory. Methods The magnesium alloy stent of S closed-loop type was selected, and 9 models of such stents with different materials, numbers of support in circumferential direction, support lengths and initial diameters were established by using SolidWorks, and these stent models were meshed by using HyperMesh. The synchronous motor ability between the blood vessel and stent after stent implantation was simulated by using ABAQUS, and the influencing factors of different structure parameters on bending stiffness were investigated and compared by using grey correlation theory. Results The effect of materials on stent flexibility was obvious. The flexibility of magnesium alloy stent was the best, and the bending stiffness was 0.958 N•(rad•mm)-1; the best flexibility of stents were those with 5-support in circumferential direction, 1.0 mm-support length, and 1.4 mm-initial diameter, and their bending stiffness was 0.853,0.829 and 1.024 N•(rad•mm)-1, respectively. Conclusions The flexibility of magnesium alloy stent is the best, followed by stainless steel stent, and cobalt-chromium stent ranks last. With the increase of support numbers in circumferential direction, support length and initial diameter, the stent flexibility shows the decreasing tendency; the grey correlation analysis shows that the effect of materials on stent flexibility is the most significant, followed by support numbers in circumferential direction and support length, while initial diameter exerts the smallest influence. The analysis of structure parameter effects on stent flexibility will provide more scientific guidance for stent design and development as well as its intervention treatment in clinic.

Analysis on biomechanical properties and hemodynamics of the vena cava filters with different numbers of support bars / 医用生物力学

Objective To investigate the interaction between vessel and vena cava filter (VCF) with different numbers of support poles and the influence on blood flow during its implantation by using finite element method and computational fluid dynamics method, so as to provide more scientific guidance for intervention treatment and design & development of the filter. Methods Three kinds of VCF models with 4, 6, 8 support poles were established by using Solidworks, respectively. The stress distribution and radial support stiffness of the vessel and filter under working condition were then simulated and analyzed by using ABAQUS. The distributions of blood flow velocity, pressure and shear stress after VCF implantation were simulated by using Fluent. Results All the mechanical and fluid properties of the three kinds of VCFs were within the scope of security. The comprehensive mechanical performance of the 6-pole filter was better, while for the 8 pole-filter, it showed larger stress under working condition, larger support intensity, higher exit velocity, larger shear stress on the filter mesh, and the trail of the flow was changed from laminar to transition flow, which might cause some damage to the vessel wall. The 4 pole-filter under working condition had a larger stress on the vessel, while its exit velocity was lower, which could be likely to cause local damage on the vessel wall, and disadvantageous to accurately positioning the filter in diseased region of the vessel. Conclusions The 6 pole-filter has a superior hemodynamic effect and comprehensive mechanical properties, which reduces the potential possibility of damage to the vessel wall caused by implantation of the filter. The simulation analysis on VCF provides a good reference for design of the filter and its intervention treatment in clinic.

Observation on the fluid resuscitation and the change in blood sodium of severely burned patients in the early stage / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the necessary amount of fluid consisting of electrolyte and colloid, the ratio of electrolyte and colloid used, and the change of blood sodium during early resuscitation in severely burned patients.</p><p><b>METHODS</b>Sixty-seven patients with total burn surface area (TBSA) equal to or over 70% and full-thickness area equal to or over 50%TBSA, hospitalized from March 2004 to March 2009, were resuscitated with fluid. The infusion amount of electrolyte, colloid, and water, and urinary output of patients at post injury hour (PIH) 24, 48, and 72 were analyzed retrospectively. The variation in blood sodium and fluid infusion at different time points was recorded. Data were processed with SPSS 13.0 software.</p><p><b>RESULTS</b>Among the 67 patients, hyponatremia occurred in 9 cases, hypernatremia occurred in 5 cases, and 53 patients had normal blood sodium level. The urinary output of patients within PIH 72 was above 70 mL/h. K value was calculated through the formula: actual total infusion amount of electrolyte and colloid (mL) = burn area (%TBSA) x body weight (kg) x K. In the first 24 PIH, K value was about 1.7, and the ratio of electrolyte and colloid was 1.4. In the second 24 PIH, K value was about 1.3 with electrolyte and colloid ratio 1.6. K value in the third 24 PIH was about 0.9 with electrolyte and colloid ratio 2.0.</p><p><b>CONCLUSIONS</b>The actual amount of resuscitation fluid is slightly larger than that calculated from traditional formula during the early stage in severely burned patients. The amount of electrolytes and the proportion of electrolyte and colloid will influence blood sodium level of patients.</p>

Prevalence of dementia among rural elderly in Gushan township,Fuzhou / 中华流行病学杂志

Objective To study the prevalence of dementia and its related risk factors in people aged 65 years and older in Gushan township.Methods People aged 65 years or older in 22 villages of Gushan township were screened,from July 2007 to November 2007.Face to face interview with mini-mental state examination,and followed by clinical assessment.A series of neuropsychological examination was done on selected subjects based on the results of the screening tests.Clinical diagnosis on dementia was made according to the Diagnosis and Statistical Manual of Mentai Disorder Fourth Edition.Resuits Out of the 2913 people 2696 aged 65 years or older,were enrolled.Among the participants,197 were confirmed of having dementia,accounting for the overall rate as 7.3%.The prevalence rate of dementia was 5.1% in males and 8.9% in females.Prevalence of dementia in the highly educated intellectuals was 9.2%,followed by 5.2%,3.9% and 2.5% in those having received primary,junior high or senior high school education.Results from logistic regression analysis showed that the major risk factors which influencing the prevalence of dementia would include age,aetivies of daily living,marital status,monthly income,frequency in watching TV/movie/field show,poker player or tress and taking care of the family etc.Conclusion The prevalence rate of dementia went up along with age.Factors as watching TV/movie/field show or playing poker/chess more frequently,as well as taking good care on families tend tO help reduce or postpone the development of dementia.

Effects of hsf1 genotype on the constitutive expression of alphaB-crystallin in mice myocardium / 中国应用生理学杂志

<p><b>AIM</b>Try to clarify the effects of HSF1 gene on the constitutively expressed alphaBC.</p><p><b>METHODS</b>To investigate the levels of constitutively expressed alphaB-Crystallin (alphaBC) in hsf1 knockout (hsf1 -/-) and hsf1 wild type (hsf1 +/+) mice myocardium by Western blot and immunohistochemistry.</p><p><b>RESULTS</b>The alphaBC levels in hsf1 -/- and hsf1 +/+ were 68.42% +/- 4.16%, 100% +/- 7.58%, respectively (P < 0.05, cytosolic fraction), and 20.53% +/- 1.01%, 37.55% +/- 1.91%, respectively (P < 0.05, pellet fraction). The alphaBC signals decreased significantly in hsf1 -/- myocardium compared with hsf1 +/+ myocardium stained with fluorescence immunohistochemistry.</p><p><b>CONCLUSION</b>hsf1 is the important, but not the only factor, which mediates the constitutively expressed alphaBC.</p>