Age-related changes in biomechanical properties of rabbit corneas / 医用生物力学

Objective To study the age-related changes in biomechanical properties of rabbit cornea by using the data from uniaxial extension testing on rabbit cornea strips. Methods To obtain the experiment data, the uniaxial extension test on rabbit cornea strips of both 3-month old and 7 to 8 month-old were performed. The exponential function model and power function model were used to fit the strain-stress curves, and two kinds of viscoelastic mechanical models were used to analyze the stress relaxation curves. Results The mechanical behavior of the rabbit cornea strip presented a nonlinear and viscoelastic property. Within the range of error permitting, the age was not an important factor to affect the stress-strain, as no significant difference was found in nonlinear stress-strain curve of rabbit cornea strips between different ages. The cornea strips of 7 to 8 month-old rabbit had a slightly bigger elastic modulus and a faster stress relaxation than those of 3 month-old one. Different stretching rates had no obvious influence on the nonlinear stress-strain of 3-month old rabbit cornea strips, but the cornea strips at high stretching rate could have a faster stress relaxation. Conclusions The tangent modulus of rabbit cornea increases slightly with age, but its relaxation properties would change greatly with age.

Effects of intraocular pressure drop for two kinds of aqueous humor drainage implant devices / 医用生物力学

Objective To observe and compare the effects of intraocular pressure (IOP) drop on using two kinds of aqueous drainage device implantation. Methods Forty healthy New Zealand white rabbits were chosen for the experiments. According to different implant devices, they were divided into NADI (new aqueous drainage implant) group and Ahmed group respectively, with 20 rabbits in each. Results Neither group appeared shallow anterior chamber after operation. At 8th week after operation, the postoperative IOP of NADI group and Ahmed group was decreased by 19.4% and 15.7%, respectively, as compared to the preoperative IOP. Statistical comparison showed that there were significant differences in IOP between two groups within 8 weeks (P＜0.05), and the IOP of NADI group was decreased more significantly than that of Ahmed group. Conclusions The IOP in NADI group was reduced more than that in Ahmed group, and such IOP drop was maintained for a longer period in NADI group, which means that NADI has an obvious IOP drop effect and good prospect in clinical application.

Three-dimensional reconstruction of rabbit eye vessels based on X-ray phase contrast imaging technique / 医用生物力学

Objective To establish a three-dimensional (3D) visualization model for the vessel system of rabbit eyes using X-ray phase contrast imaging（XPCI）technique, and observe the morphological characteristics of iris vessels of the rabbit eyes. Methods Angiography on vessels of the New Zealand rabbit eyes was conducted using Barium sulfate as the contrast medium. The projected images of in vitro rabbit eye samples with high precision were obtained by XPCI technique, and then converted to tomography images by filter back projection. The 3D reconstruction of the rabbit eyes was completed by commercial visualization software Amira 5.2.2. Results The main blood vessels of the rabbit eyes were clear and coherent in the projection images, and the distribution and trend of some small vessels could be observed, with the smallest distinguishable blood vessel diameter being about 10 μm. The 3D model for vessel network of the rabbit eyes was built after 3D reconstruction of CT scan images. The major arterial circle of the iris could be observed at level 4 branch structure of vessels in the fundus, and the minimum diameter of vessels that could be identified was 40 μm. Conclusions The vessels of the rabbit eyes can be clearly observed and 3D visualization of vessel network can be constructed by using XPCI technique, which would provide basis for the analysis on hemodynamics of blood vessels in the eye and reference for the clinical study of glaucoma.

Efficacy analysis on type 2 diabetes mellitus treated with acupuncture in females / 中国针灸

<p><b>OBJECTIVE</b>To evaluate the efficacy and the relevant effect factors of acupuncture for type 2 diabetes mellitus (T2DM) in females.</p><p><b>METHODS</b>Of 83 female patients of T2DM, 49 cases were deficiency of kidney yin syndrome and 34 cases were yin and yang deficiency syndrome. Acupuncture was adopted and the acupoints were selected according to the syndrome differentiation. In kidney yin deficiency syndrome, Taixi (KI 3), Shenmen (HT 7), Taichong (LR 3) and Sanyinjiao (SP 6), etc. were selected. In yin and yang deficiency syndrome, Shenshu (BL 23), Pishu (BL 20), Yishu (Extra) and Jingmen (GB 25), etc. were selected. In 3 courses of treatment, the changes in fasting plasma glucose (FPG), fasting insulin (FINS), insulin sensitivity index (ISI), insulin resistace index (Homa-IR), index of islet beta-cell function (Homa-beta), total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) were compared before and after treatment between the two groups. The relationship of the efficacy was analyzed in terms of the syndrome differentiation, age, duration of sickness, obesity and hereditary factors.</p><p><b>RESULTS</b>After the treatment, the levels of FPG, FINS, Homa-IR, TC, TG and LDL-C were reduced obviously (all P < 0.01) and the levels of ISI, Homa-beta and HDL-C were increased apparently (all P < 0.01). The total clinical effective rate was 80.7% (67/83), in which, that of kidney yin deficiency syndrome was 83.7% (41/49) and that of yin and yang deficiency syndrome was 76.5% (26/34). The efficacy was not different significantly between the two syndromes. But, the younger the age was, the better the efficacy was.</p><p><b>CONCLUSION</b>Acupuncture positively regulates the glucose and lipid metabolism in the patients of T2DM. This therapy improves insulin resistance, enhances the body sensitivity to insulin and improves insulin beta-cell function. The efficacy is related to the patient's age.</p>

Efficacy observation of acupuncture and tapping therapy in the treatment of type 2 diabetes of yin deficiency pattern combined with stasis in the patients / 中国针灸

<p><b>OBJECTIVE</b>To explore the clinical efficacy and mechanism of acupuncture and tapping therapy in the treatment of type 2 diabetes of yin deficiency pattern combined with stasis in the patients.</p><p><b>METHODS</b>One hundred and twelve patients were treated with acupuncture, followed by tapping method. The reinforcing method with lifting, thrusting and rotating needle technique was used at Taixi (KI 3), Shenmen (HT 7), Taibai (SP 3), Taiyuan (LU 9), Sanyinjiao (SP 6) and Zusanli (ST 36); and the even-needling technique was used at Taichong (LR 3), Hegu (LI 4), Xuehai (SP 10) and Fenglong (ST 40). The needles were remained for 30 min. After needle removal, the tapping method with plum-blossom needle was applied to Geshu (BL 17), Yishu (EX-B 3), Ganshu (BL 18), Shenshu (BL 23) and Pishu (BL 20), once every two days. The treatment of 3 months was required. The changes were observed before and after treatment in the relevant indices of fat-islet axis such as fasting plasma glucose (FPG), fasting leptin (FLP), fasting insulin (FINS), insulin sensitivity index (ISI), insulin resistance (Homa IR), insulin secretion index (Homa-beta) and the indices of obesity and blood lipids in the patients.</p><p><b>RESULTS</b>After treatment, the total effective rate was 84.8% (95/112), in which the efficacy on the stasis predominated syndrome was better than that of yin deficiency predominated syndrome [92.9% (52/56) vs 76.8% (43/56), P < 0.05]. Before treatment, FPG, FLP, FINS, Homa-IR, total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), body mass, body mass index (BMI), fat percentage (F%) and obesity degree in the patients were higher obviously than those in the normal group (all P < 0.01); high-density lipoprotein cholesterol (HDL-C) and ISI were lower than those in the normal group (both P < 0.01). After treatment, FPG, FLP, FINS, Homa-IR, TC, TG, LDL-C, body mass, BMI, F% and obesity degree were all reduced obviously as compared with those before treatment (all P < 0.01). ISI and HDL-C were increased apparently (both P < 0.01). The efficacy on mild obesity was superior to that on moderate and severe obesity, and the efficacy in the young patients was better than that in the elderly, the efficacy in the males was better than that in the females, but the differences were not significant (all P > 0.05). The efficacy in the cases with 10 years duration of sickness was superior to those with over 10 years duration of sickness (P < 0. 01).</p><p><b>CONCLUSION</b>Acupuncture and tapping therapy achieves the significant efficacy on type 2 diabetes of yin deficiency pattern combined with stasis and its effect mechanism is related to the positive regulation of glucose, lipid metabolism and fat-islet axis.</p>

Clinical observation on obesity and hyperlipidemia of liver qi stagnation and spleen deficiency pattern in female patients treated with combined therapy of acupuncture and tapping method / 中国针灸

<p><b>OBJECTIVE</b>To explore the efficacy and effect mechanism of the combined therapy of acupuncture and tapping method in the treatment of obesity and hyperlipidemia of liver qi stagnation and spleen deficiency pattern in the patients.</p><p><b>METHODS</b>One hundred and four female patients were randomized into a combined therapy of acupuncture and tapping (combined therapy group) group method and an acupuncture group, 52 cases in each group. In the acupuncture group, acupuncture was applied to Qimen (LR 14), Taichong (LR 3), Zhangmen (LR 13), Taibai (SP 3), Zusanli (ST 36), Geshu (BL 17), Ganshu (BL 18), Pishu (BL 20), etc. In the combined therapy group, on the basis of acupuncture treatment, the tapping method with plum blossom needle was used at each acupoint. The treatment was given once every two days, continuously for 3 months in the two groups. The indices were observed, including the obesity indices, such as body mass, body mass index (BMI), body fat percentage (F%) and obesity degree (A); the blood lipid levels such as total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL) and high density lipoprotein (HDL); the fat-islet axie relevant indices such as fasting plasma glucose (FBS), fasting leptin (FLP), fasting insulin (FINS), insulin sensitive index (ISI), insulin resistance in- dex (Homa IR), insulin secretion index (Homa-β) and autonomic nerve function index (Y value) before and after treatment in the patients of two groups. The efficacy was compared between the two groups.</p><p><b>RESULTS</b>The total effective rates were 96.2% (50/52) and 84.6% (44/52) in the combined therapy group and the acupuncture group respectively, without significant difference in comparison (P > 0.05). Obesity indices, blood lipid indices, fat-islet axie relevant indices and autonomic nerve function indices were all improved after treatment as compared with those before treatment in the two groups (P < 0.01, P < 0.05), and the improvements in the combined therapy group were much more significant (P < 0.01, P < 0.05).</p><p><b>CONCLUSION</b>The combined therapy of acupuncture and tapping method achieves the double effects of weight loss and lipid loss in the treatment of obesity combined with hyperlipidemia. The effect mechanism is possibly related to the positive regulations of blood glucose, lipid metabolism and fat-islet axie in the patients.</p>

Determining the number of preconditioning cycles by calculating the decay rate of strain energy in uniaxial tensile test on soft tissue / 医用生物力学

Objective To investigate a method determining the number of preconditioning cycles in uniaxial tensile test on soft tissues by calculating the decay rate of strain energy. Methods The abdominal skin of healthy New Zealand rabbits was selected as study object, from which strip specimens were obtained in directions parallel to linea alba (0°)and perpendicular to linea alba(90°). Then the uniaxial preconditioning tests with 15% preconditioning strain were performed on these specimens. Load displacement preconditioning data were obtained, and transformed into the stress strain data correspondingly. The preconditioning cycles (n values), at the decay rate of strain energy being 5% and 10%, respectively, were then calculated by MATLAB programme when n values satisfy the inequality η=Wn－Wn－1Wn－1×100%≤5% or≤10%（Wn signifies the strain energy loss in the nth preconditioning cycle）. Results When the decay rate of strain energy was 5%, the number of preconditioning cycles in 0° and 90° direction was 11.11 and 13.67, respectively. When the decay rate of strain energy was 10%, the number of preconditioning cycles in 0° and 90° direction was 6.67 and 7.78, respectively. Conclusions By calculating the decay rate of strain energy, the number of preconditioning cycles in uniaxial tensile on soft tissues can be quantified, which could help provide the research basis for standardization of biomechanical testing on soft tissues.

Effects of aqueous humor drainage to different parts of rabbit eye on intraocular pressure drop / 医用生物力学

Objective To observe and compare the effects of intraocular pressure (IOP) drop when the aqueous humor was drained to limbus, ambitus and posterior segment of rabbit eye by implanting medical silicone tube. Methods Forty-five healthy New Zealand white rabbits were chosen for the experimental group, each with the medical silicone tube implanted in one eye. According to different implanting ways, the rabbits were divided into the limbus group, ambitus group and posterior segment group respectively, with 15 rabbits in each group. Results According to statistical comparison of preoperative and postoperative IOP values among the 3 groups within 4 weeks, the IOP of the posterior segment group was decreased most by 26.6%, and that of the ambitus group and limbal group was decreased by 16.2% and 1.2%, respectively. The differences between the preoperative and postoperative IOP in first, second and fourth week were statistically significant (P<0.01) for all three groups. The IOP of the posterior segment group after 4 weeks was decreased most, and there were significant differences in IOP values among three groups (P<0.01). Conclusions The greatest IOP drop occurred when the aqueous humor was drained to the posterior segment of the rabbit eye, and this result could provide some reference for the clinical surgery.

Experimental design on flow characteristics of aqueous humor based on PIV method / 医用生物力学

Objective To visualize the process of introcular flow caused by injection into the posterior chamber of the impermeable vitro eyeball with particle image velocimetry (PIV) technology, and calculate the flow fields at different moments, so as to investigate PIV experimental scheme for low-speed flow field measurement in the eye and provide basis for the in vivo measurement of aqueous humor flow under physiological status. Methods In an impermeable vitro eyeball, the introcular flow would be slow enough when the injection pump was driven at the rate of 0.2, 0.4, 0.6, 0.8, 1.0, 1.5 mL/min. Fluorescent particle solution, with a certain concentration and particle diameter of 10 μm, was injected into the posterior chamber of the vitro rabbit eye, and the sheet laser was projected to the medial frontal plane of the eye. Then clear particle images were captured by camera, and the velocity field was recorded and calculated by PIV system. Results The fluid into the posterior chamber first filled in the posterior chamber and the pupil, then passed the pupillary margin and flowed into the anterior chamber, which was consistent with the theoretical flow process of aqueous humor under physiological conditions. Based on analysis of the particle images, the velocity inside an impermeable eyeball was calculated at the magnitude of a few millimeters per second. Conclusions PIV method can be applied to low-speed flow field measurement, and the flow characteristics inside the eyeball can also be measured by PIV method, which contributes to the measurement of aqueous flow under both physical and pathological conditions, provides experimental verification for numerical simulations on aqueous humor field, and offers a new diagnostic and treatment perspective for shear force damage and destructions of corneal endothelial cells, the iris and lens under different flow fields.

Regularity on change of retinal nerve fiber layer thickness with acute high intraocular pressure / 医用生物力学

Objective To measure the rabbit retinal nerve fiber layer(RNFL) thickness in vivo under different intraocular pressures (IOP) and at different time intervals after acute high IOP, and to obtain the regularity on change of RNFL thickness with acute high IOP. Methods Four groups of acute high IOP model were formed by perfusing the saline water into the anterior chamber of rabbit eyes, then RNFL thickness under different IOPs was measured by optical coherence tomography with radial scanning mode whose center was optical papilla and diameter was 6 mm. Results The absolute change values of RNFL thickness were(-27.16±14.24), (-33.33±6.74), (-48.75±5.24), (-67.29±3.89) μm under different IOPs of (4.50±0.35), (6.07±0.31), (7.74±0.26), (10.71±0.07) kPa, respectively. The linear relationship was found between the relative change of RNFL thickness and IOP. IOP could return to the normal level within two days after acute high IOP, while the RNFL thickness could be restored at the second week, and it was easier to restore if the IOP was lower than 6.65 kPa. Conclusions The acute high IOP could cause RNFL thickness to decrease significantly with the increased acute high IOP, but it will be restored after some time.

Finite element modeling and mechanical analysis on supination-external rotation ankle injury / 医用生物力学

Objective To simulate the supination-external rotation ankle injury and establish a 3D finite element model of the ankle. Methods Based on CT images of the normal human ankle joint, the 3D model of the ankle with ligaments was established. The supination-external rotation ankle injuries with four different degrees of Lauge-Hanson were analyzed by finite element method. Distributions of the ankle joint stress and tibial articular surface pressure were obtained. Results The maximum stress was at the anterior tibiofibular ligament attachment point of the tibial under supination-external rotation loading. When the anterior tibiofibular ligament was ruptured, the maximum stress was at the interosseous membrane. After the interosseous membrane was ruptured, the high stress was at the posterior ligament of the ankle. When the posterior tibiofibular ligament was ruptured, the high stress was at the deltoid ligament. The high pressure was at the distal fibula or the rear of tibial articular surface. Conclusions The established ankle-foot 3D numerical model can be used for the mechanical analysis of supination-externalrotation ankle injury. The calculated distributions of the ankle stress and the tibial articular surface pressure were in agreement with the description of Lauge-Hanson classification.

Method to determine nonlinear mechanical properties of the blood vessel based on inflate experiment / 医用生物力学

Objective To propose an inverse method for determining nonlinear mechanical properties of the blood vessel based on the results of experimental data and numerical simulation.Methods Pressure loading was applied on the blood vessel to obtain the experimental data of in vitro holistic blood vessel by using the self-designed device. The finite element model of vessel inflation was established by supposing that material characteristics of the blood vessel were in corresponding with the hyperelastic Ogden model. Mechanical properties of the blood vessel were then computed by the reverse method based on these experimental data and simulated results .Results The first-order and second-order Ogden material parameters of the rabbit abdominal aorta were identified, in which α=10.86±1.98 for the first-order Ogden material model. The mechanical properties of the rabbit abdominal aorta could be characterized as the hyperelastic material. Conclusions The inverse method based on the experimental measurement and numerical simulation can be used to identify the nonlinear mechanical properties of the blood vessel.

Observation on the efficacy of female obesity complicated with climacteric syndrome treated by acupuncture and moxibustion / 中国针灸

<p><b>OBJECTIVE</b>To observe the efficacy of acupuncture and moxibustion on female obesity complicated with climacteric syndrome and its impact factors.</p><p><b>METHODS</b>One hundred and fifty-one cases of female obesity complicated with climacteric syndrome were treated according to the basic principle as "pattern/syndrome differentiation". Accordingly, the reinforcing or reducing technique was applied at Quchi (LI 11), Zhongwan (CV 12), Tianshu (ST 25), Daheng (SP 15), Zusanli (ST 36), Shangjuxu (ST 37), Sanyinjiao (SP 6), Neiting (ST 44), etc. The auricular point sticking was applied at Hunger Point, Ear-shenmen, Sympathetic Nerve, Endocrine and Stomach. The treatment was given once every two days. The duration of treatment was 3 months. The changes in the symptoms, physical signs, obesity index, Kupperman index, the vegetative equilibrium index (Value Y), estradiol (E2) and follicle stimulating hormone (FSH) were observed before and after treatment.</p><p><b>RESULTS</b>The obesity patients complicated with climacteric syndrome presented unusually high level of obesity index, Kupperman index and FSH levels and unusually low level of E2. After treatment, the obesity index, Kupperman index and FSH levels were all reduced significantly (all P < 0.01) while E2 level was increased significantly (P < 0.05).</p><p><b>CONCLUSION</b>Acupuncture and moxibustion achieve the significant efficacy on obesity complicated with climacteric syndrome, which is closely related with the pattern/syndrome of the disorder and obesity grade. For the effective and curative rate of obesity index, the efficacy of liver qi stagnation pattern/syndrome is better than that at liver stagnation and spleen deficiency pattern/syndrome than spleen and kidney yang deficiency pattern/syndrome than liver and kidney yin deficiency pattern/syndrome than yin and yang deficiency pattern/syndrome; the efficacy of mild obesity is better than that at moderate obesity than severe obesity.</p>

Research on pressure-volume relations for the rabbit eye in vivo / 医用生物力学

Objective To obtain pressure-volume relatioship for the rabbit eye in vivo. Method Physiological salt solution was injected with the rate of 20 μL/min through the limbus to the anterior chamber of the rabbit eye for 100 min and the intraocular pressure (IOP) was recorded. Results The relationship between IOP and injection time could be fitted to a segmented function with a characteristic point called IOPg. The ocular rigidity coefficients before and after this IOPg were (4.02±0.86) mmH2O/μL and (2.43±0.94) mmH2O/μL, respectively (1 mmH2O=9.8 Pa), showing significant difference. Conclusions IOPg existed in all curves of IOP and injection time and the ocular rigidity coefficients were dependent on the injection rate and position of IOPg. Parameters of the fit function between IOP and injection time have definite physiological significance.

Finite element analysis of interface pressure over the above knee residual limb at mid stance with pre-stress / 医用生物力学

Objective To investigate the interface pressure on above knee residual limb at mid stance during walking，so as to provide basis for the establishment of measurement and evaluation system for the above-knee socket. Methods Based on CT images of the femur, soft tissue and above knee socket of the patient with residual limb, the three-dimensional model was first built, and then to assemble them according to changes of the hip joint in a gait cycle. The finite element model was then established to simulate the loading conditions at mid stance during a gait cycle, and the effect of pre-stress was investigated by nonlinear large deformation analysis. Results If considering the effects such as joint changes and pre-stress, the maximum value by calculation for normal interface pressure distributed on the terminal of stump was 257.66 kPa, which could better match the maximum stress actually measured by the Mflex Sensor Distributing System as 258.9 kPa. Conclusions The three-dimensional finite element model with considering the factors such as hip joint change, pre-stress and friction could effectively simulate the stress condition of patient with residual limb during walking.

Mechanical evaluation of load distribution on human shoulder and dorsal muscles during traditional Chinese Gongfu stance / 医用生物力学

Objective To study the load distribution of muscles for those having long period stance training during traditional chinese Gongfu stance, and evaluate the effectiveness of such stance. Method Seven traditional Chinese Gongfu stance trainers and seven normal adults for the control were enrolled in the experiment. The sEMG (surface electromyography) signals of five muscles (brachioradialis, triceps brachii, deltoid, latissimus dorsi, triceps surae) were tested by Flexcomp Infiniti 10 channel sEMG collector. The value of IEMG (integral electromyography) were processed. Results With the increase of load, the ratio between deltoid IEMG and latissimus dorsi IEMG for the stance trained group stabilized in the range from (0.372±0.258) to (0.257±0.146), while that of the control was in the range from (1.313±0.698) to (0.800±0.405). Conclusions When the traditional Chinese Gongfu stance is processed with or without load, the trained group distributed major load on the dorsal muscle, while the control on the shoulder.

A new rat model of glaucoma induced by intracameral injection of silicone oil and electrocoagulation of limbal vessels / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>A satisfied glaucoma model is absent now. The aim of this study was to evaluate the effect of a combination of intracameral injection of silicone oil and electrocoagulation of corneal limbal vessels and episcleral veins in the rats to establish glaucoma model.</p><p><b>METHODS</b>Operation was performed in each of the left eyes of 90 adult male rats. Right eyes were used as controls. Measurement of intraocular pressure (IOP) was performed with an applanation tonometer (Tono-Pen). Retinal ganglion cells (RGCs) were retrogradely labeled by applying FluoroGold onto the bilateral superior colliculus.</p><p><b>RESULTS</b>During the follow-up (24 weeks), the IOP of the study eyes was significantly higher (P < 0.05) than the control eyes (at final examination, IOP of control eyes was (13.4 ± 1.0) mmHg and IOP of study eyes was (16.1 ± 1.8) mmHg). Correspondingly, at 24 weeks after operation, the RGCs density of the study eyes (2286.11 ± 290.45/mm(2)) was significantly lower than the control eyes (2626.46 ± 164.85/mm(2), P < 0.01). In the operated eyes, histological examination showed excavation of optic disc and increased neuroglial cells in the optic nerve, reduced thickness of retina and diminution of retinal ganglion cells, and atrophy of ciliary body and iris. Notably, the anterior chamber angle of the operated eye remained open.</p><p><b>CONCLUSIONS</b>A combination of intracameral injection of silicone oil and electrocoagulation of corneal limbal vessels and episcleral veins may establish a reliable glaucoma model for further research.</p>

Hemodynamic effects of stenting on wide-necked intracranial aneurysms / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Stent placement has been widely used to assist coiling in cerebral aneurysm treatments. The present study aimed to investigate the hemodynamic effects of stenting on wide-necked intracranial aneurysms.</p><p><b>METHODS</b>Three idealized plexiglass aneurismal models with different geometries before and after stenting were created, and their three-dimensional computational models were constructed. Flow dynamics in stented and unstented aneurismal models were studied using in vitro flow visualization and computational fluid dynamics (CFD) simulations. In addition, effects of stenting on flow dynamics in a patient-specific aneurysm model were also analyzed by CFD.</p><p><b>RESULTS</b>The results of flow visualization were consistent with those obtained with CFD simulations. Stent deployment reduced vortex inside the aneurysm and its impact on the aneurysm sac, and decreased wall shear stress on the sac. Different aneurysm geometries dictated fundamentally different hemodynamic patterns and outcomes of stenting.</p><p><b>CONCLUSIONS</b>Stenting across the neck of aneurysms improves local blood flow profiles. This may facilitate thrombus formation in aneurysms and decrease the chance of recanalization.</p>

Effect of ocular hypertension on the function of retina of glaucoma / 医用生物力学

Objective To explore the effect of elevated intraocular pressure (IOP) on retina's function of rat. Method Chronic glaucoma rat models were built and IOP were measured persistently. Flash electroretinogram (F ERG) and histological status were measured before and after surgery. ResultsThe maximal IOP in rats without anesthesia is (3.07±1.10) kPa in 1 day after surgery. From 1 w to 6 w after surgery, the model eye IOPs are （2.84±0.90） kPa，（2.86±0.54） kPa，（2.76±0.52） kPa，（2.70±0.51） kPa，（2.39±0.27） kPa and（2.09±0.39） kPa, respectively, which are significant higher than that of the fellow eye. A series of main parameters including the amplitudes of a wave, b wave and oscillatory potentials(OPs) all dramatically decreased in model eyes at 6 weeks and 3 weeks postoperatively . No obvious changes were observed by routine HE staining among the eyes before and after surgery. Conclusions The chronic high intraocular pressure could induce the retinal dysfunction before any morphological change occurred, and what's more, the damage showed itself a progressive one.

Measuring iris elastic modulus based on holistic iris deformation experiment / 医用生物力学

Objective To measure the iris elastic modulus. Method Using the self designed device, the information of in vitro holistic iris deformation of rabbits were obtained with the load pressure increasing gradually from 0 Pa to 600 Pa, and the heights of such iris were computed. The corresponding model based on experimental data was established and analyzed by ANSYS finite element software, and the iris elastic modulus was computed by a reverse method. Results The elastic modulus is 6.1 kPa at 100 Pa load pressure. ConclusionsThe iris material can be considered as linear elastic model when the pressure difference between the anterior chamber and posterior chamber is low.