ObjectiveTo establish multidrugresistance cell substrain of human hepatocellular carcinoma and to investigate its characteristics.MethodsSMMC7721 cell strain was cultured in Adriamycin(ADM). The multidrugresistance cell substrain SMMC7721/ADM was harvested after a long period of culture by gradually increasing the concentration of ADM and its characteristics were investigated. Results①The drug resistance of SMMC7721/ADM to ADM increased by 33.3 times, to Vincristine 16.8 times, to Diamminedichloroplatinum 2.8 times. ②The drug resistance cell substrain had almost the same growth velocity as its parental generation. The doubling time was 32.0 hours and 30.5 hours respectively. They had the analogous growth curves. ③The obvious difference between the drug resistance cell substrain and its parental generation was that the former’s microvilli became thick, short and scattered by scanning and transmitting electron microscopy. ④The multidrug resistance cell substrain kept the characteristics of hepatocellular carcinoma, it could be transplanted into the subcutaneous tissue of nude mice. ⑤The drug resistance of the cell substrain reduced to 28.0% and 9.2%after removal of the drug for 1 month and 2 months respectively, its drug resistance could remain stable (35.4 times) after 2 months of culture in ADM (0.04 μg/ml).ConclusionThe SMMC7721/ADM cell substrain has the stable fundamental characteristics of a drug resistance cell strain.
Abstract： Objective To use tissue Doppler strain rate imaging to evaluate the impact of low dose dopamine and milrinone on systolic and diastolic function of the left ventricle of patients undergoing heart valve replacement. Methods Forty patients undergoing selective heart valve replacement in West China Hospital of Sichuan University between March and May 2011 were included in this study. All the patients were randomized into 2 groups with 20 patients in each group： milrione group and dopamine group. After anesthesia induction and before cardiopulmonary bypass setup， left ventricular ejection fraction （LVEF） was measured by echocardiography. Tissue Doppler strain rate imaging was used to measure the left ventricular lateral wall and midventricular segment from the four-chamber view， which was compared with Doppler parameters. Results LVEF， ratio of early-diastolic to end-diastolic velocity （E/A） of transmitral flow， ratio of mitral inflow velocity to early diastolic velocity in the annulus （E/Et） of both 2 groups were significantly different between before and after dopamine and milrinone administration （P＜0. 05）. In the milrinone group， 4 segments systolic peak velocity （Vs）， 1 segment early diastolic peak velocity （Ve）， 4 segments late diastolic peak velocity （Va）， 3 segments Ve/Va ratio， 2 segments systolic peak strain rate （SRs）， 2 segments late diastolic peak strain rate （SRa）， and 3 segments early diastolic peak strain rate SRe/SRa ratio after dopamine and milrinone administration were significantly higher than those before dopamine and milrinone administration （P＜0. 05）. In the dopamine group， 4 segments systolic peak velocity （Vs）， 1 segment Ve， 4 segments Va， 1 segment Ve/Va ratio， 2 segments SRs， 1 segment SRe， 1 segment SRa， and 1 segment SRe/SRa ratio after dopamine and milrinone administration were significantly higher than those before dopamine and milrinone administration （P＜0.05）. To compare the milrione group and dopamine group after medication administration， 2 segments Vs， 4 segments Va， 1 segment SRe， 1 segment SRa， 2 segments Ve/Va ratio， and 2 segments SRe/SRa ratio of the milrione group were significantly higher than those of the dopamine group （P＜0.05）， and 1 segment Vs， two segments SRs of the milrione group were significantly lower than those of the dopamine group （P＜0.05）. Conclusion Both milrinone and dopamine can improve left ventricular systolic function of perioperative patients undergoing heart valve replacement assessed by tissue Doppler strain rate imaging， while milrinone can improve the diastolic function of the left ventricle on the long axis more significantly.
Objective By observation of the diameter, progression rate, wall thickness, and the opening angle of the abnormal aortic of abdominal aortic aneurysm (AAA) in rats, to observe the effect of saturated hydrogen saline on residual strain of AAA rats, and to investigate its inhibition effect on AAA formation. Methods Twenty healthy male Sprague Dawley rats (weighing, 200-220 g) were randomly divided into 2 groups, which was made the AAA model by infiltration of the abdominal arota with 0.5 mol/L calcium chloride. Saturated hydrogen saline (5 mL/kg) or saline (5 mL/kg) was injected intraperitoneally in the experimental group or control group respectively, every day for 28 days. At 28 days, the diameter, progression rate, wall thickness, and opening angle of the abnormal aorta were mearsured. The aortic tissue was harvested for histological examination (HE staining and aldehyde-fuchsin staining). Results At 28 days after operation, the diameter of abnormal aorta in 2 groups were significantly higher than preoperative ones (P lt; 0.05), the progression rate in experimental group (65% ± 15%) was significantly lower than that in control group (128% ± 54%) (t=3.611, P=0.005). The opening angle and the wall thickness in experimental group were (88.78 ± 29.20)° and (0.14 ± 0.03) mm respectively, had significant differences when compared with the values in control group [(44.23 ± 28.52)° and (0.36 ± 0.05) mm respectively] (P lt; 0.01). The integrity and continuity of the aortic wall in experimental group were superior to that in the control group. Compared with the control group, the injury of elastic fiber in aortic wall and the infiltration of inflammation were all reduced. Conclusion Saturated hydrogen saline can maintain good mechanical properties and reduce dilatation of the aorta by increasing residual strain and reducing the remodeling of it.
Objective To investigate whether the biomechanical effect of mushroom shaped surface prosthesis on femoral neck is in the scope of safety after the replacement. Methods Four donated fresh-adult specimens of upper femur under the age of 55 years old were used. The strains of detecting points A (lateral) and B (medial) on the narrow place of femoral neck in the standing position were simulated for three stages before or after the prosthesis replacement, namely the pre-replacement, the initial stage during which the interspace of the prosthesis was filled with cancellous bone, and laterstage during which the interspace of the prosthesis was filled with bone cement. Then they were compared by using l inear regression analysis in Excel and rel iabil ity analysis. Results The regression analysis showed that the values of correlation coefficient r were all more than 99% at the different stages, indicating the strain of femoral neck’s cortical bone was proportional to the load and there was no occurrence of the plastic deformation of the femoral neck. For point A, the slope of the trend l ine of strain was 0.671 9 at the pre-replacement stage. The value of the initial stage after replacement was 0.619 2 and its change rate was —7.8%; while corresponding value was 0.662 7 and —1.4% at the later stage after replacement. For point B, the slope of the trend l ine of strain was —1.056 1 at the pre-replacement stage. The value of the initial stage after replacement was — 1.129 2 and its change rate was 6.9%; while corresponding value was —1.085 1 and 2.7% at the later stage after replacement. Conclusion The mechanical strength of femoral neck is in the scope of safety after surface replacement of the femoral head. The change rate of strain at the later stage is smaller than the initial stage.
Objective To set up the experimemtal model with superior segmentalbone defect in acetabulum and implant the three-fin acetabular component, and examine the Von Mises stresses of pelvis bone with simulating single leg position in vitro using rosette strain gages method(RSGD). Methods Four kinds of three-fin components were made based on measurement of diameter, depth and roof thickness of acetabular specimens. These kinds of threefin acetabular components based on spreaded degrees of lateral fins(0,36,45 and 60°). The superiorsegmental bone defect of acetabulum in 4 cadaver pelvis specimens was made,then simulated the actual position to place implant into acetabular bone.A blank control group was set up.After being fit up the 7 sets of rosette strain gages,then specimen to test the pelvic Von Mises stresses simulating the static load of single leg on the mechanic machine.Progressive load was graded into 150, 300,450, 600, 750 and 900 N.We obtained the strains informations about loaded andun-loaded pelvis bone. Results Based on computed the strains informations,we were informed the Von Mises stresses about pelvis bone.The maximal Von Mises stresses of selected local position was 6.93 MPa and the minimal Von Mises stresses of selected local position was 1.08 MPa. Conclusion Providing the data about the mainpart of threefin acetabular component to optimize spreaded degrees of lateral fins.
By using Urist s method four types of BMG from the long bones of the rabbit、 pig、sheep、 and human being were prepared. Each of them was implanted into the pectoralis and thigh muscles in 25 adult rats, respectiely. Two-eight weeks after implantation, the unoreaction and inductive osteogensis potential in the tissues were observed under mieroscope. The result showed that aBMG had inductive osteogenesis potential. However, rejection in varying digree existed around aBMG. It was important to further decrease the antingenicity digree exised around a BMG . and enhance its osteogennic potential before the possibility of its clinical application.
ObjectiveTo explore the distribution of multidrug resistant organism in neonates admitted to the hospital through various ways, and analyze the risk factors in order to avoid cross infection of multidrug resistant organism in neonatology department. MethodsA total of 2 124 neonates were monitored from January 2012 to July 2013, among which 1 119 were admitted from outpatient department (outpatient group), 782 were transferred from other departments (other department group), and 223 were from other hospitals (other hospital group). We analyzed their hospital stays, weight, average length of stay, and drug-resistant strains, and their relationship with nosocomial infection. ResultsAmong the 105 drug-resistant strains, there were 57 from the outpatient group, 27 from the other department group, and 21 from the other hospital group. The positive rate in the patients transferred from other hospitals was the highest (9.42%). Neonates with the hospital stay of more than 14 days and weighing 1 500 g or less were the high-risk groups of drug-resistant strains in nosocomial infection. Drug-resistant strains of nosocomial infection detected in the patients admitted through different ways were basically identical. ConclusionWe should strengthen screening, isolation, prevention and control work in the outpatient neonate. At the same time, we can't ignore the prevention and control of the infection in neonates from other departments or hospitals, especially the prevention and control work in neonates with the hospital stay of more than 14 days and weighing 1 500 g or less to reduce the occurrence of multiple drug-resistant strains cross infection.
Bone marrow-derived mesenchymal stem cells (BMSCs) are multipotent stem cells that differentiate into a variety of cell types and widely used in tissue regeneration engineering. The purpose of this study is to investigate whether the cyclic biaxial stretching strain could promote the rat BMSCs (rBMSCs) to differentiate into cardiomyocyte-like cells in vitro. The second or third generation of rBMSCs were randomly divided into the cyclic stretching stain group, the control group and the blank group. Those rBMSCs in the cyclic stretching strain group were seeded on a silicone membrane with complete medium were exposed to biaxial stretching strain of 10% of membrane at a frequency of 1 Hz lasting for 6 h, 12 h and 24 h. Those in the control group were seeded on silicone membrane with complete medium. Those in the blank group were seeded in the 6-wells plates with complete medium. The mRNA expression of GATA4 and myocyte-specific enhancer factor 2C (MEF-2C) were detected by the real-time fluorescent quantification PCR and the protein expression of connexin 43 (Cx43) was detected by using the Western blot method. The results showed that the mRNA expression level of the GATA4 and MEF-2C, and the protein expression level of Cx43 were significantly higher in the cyclic stretching strain groups, compared with those in the relative control groups (P<0.05). It suggests that cyclic biaxial stretching strain could play a part in the induction of rBMSCs to differentiate into cardiomyocyte-like cells in vitro, but the differentiation mechanism is still unclear.
To evaluate the fatigue behavior of nitinol stents, we used the finite element method to simulate the manufacture processes of nitinol stents, including expanding, annealing, crimping, and releasing procedure in applications of the clinical treatments. Meanwhile, we also studied the effect of the crown area dimension of stent on strain distribution. We then applied a fatigue diagram to investigate the fatigue characteristics of nitinol stents. The results showed that the maximum strain of all three stent structures, which had different crown area dimensions under vessel loads, located at the transition area between the crown and the strut, but comparable deformation appeared at the inner side of the crown area center. The cause of these results was that the difference of the area moment of inertia determined by the crown dimension induced the difference of strain distribution in stent structure. Moreover, it can be drawn from the fatigue diagrams that the fatigue performance got the best result when the crown area dimension equaled to the intermediate value. The above results proved that the fatigue property of nitinol stent had a close relationship with the dimension of stent crown area, but there was no positive correlation.
Intravascular ultrasound (IVUS) is widely used in coronary artery examination. Ultrasonic elastography combined with IVUS is very conspicuous in identifying plaque component and in detecting plaque vulnerability degree. In this study, a simulation model of the blood vessel based on finite element analysis (FEA) was established. The vessel walls generally have radial changes caused by different intravascular pressure. The signals at lower pressures were used as the pre-deformation data and the signals at higher pressure were used as the post-deformation data. Displacement distribution was constructed using the time-domain cross-correlation method, and then strain images. By comparison of elastograms under different pressures, we obtained the optimal pressure step. Furthermore, on the basis of the obtained optimize pressure step, the simulation results showed that this method could effectively distinguish characteristics between different component plaques, and could guide the later experiments and clinical applications.