Numerical Simulation and Experimental Study on Vascular Mechanical Properties of Coronary Degradable Stent Intervention / 医用生物力学

Objective To explore the effect of vascular stress changes on endothelial function recovery and vascular restenosis inhibition in dynamic degradation process of the degradable stent. Methods The material parameters of the hyper-elastic vascular constitutive relationship was fitted, and the stress distribution on the intima of the blood vessel before stent implantation and during dynamic degradation was calculated by numerical simulation. In vitro culture experiments were carried out, and the stretch ratios of the silicon chambers were 0%, 5%, 10% and 15%, respectively, to simulate the mechanical environment at different degradation stages, and to explore the effects of different stretch ratios on growth state of the endothelial cells （ECs）. Results After the stent was completely degraded, the circumferential intimal stress and strain of the vessel were restored to 0.137 MPa and 5.5%, which were close to the physiological parameters (0.122 MPa, 4.8%) before stent implantation. In vitro experiments showed that the survival rate of ECs was the highest under the condition of 0.1 MPa circumferential stress and 5% strain, and adhesion growth could be achieved. Conclusions With the occurrence of stent degradation process, the circumferential stress and strain of the intima were restored to a range close to physiological parameters, which promoted the growth of ECs. The recovery of intimal function could effectively inhibit the process of vascular restenosis. The results can provide the theoretical basis and experimental platform for studying coronary intervention for the treatment of vascular restenosis.

The effect of concentration ratio on tumor cell adhesion in shear flow / 医用生物力学

Objective To study the different effects from different concentration ratios of polymorphonuclear neutrophil (PMN) to tumor cell (TC) on the process of tumor cell adhesion to endothelial cell (EC) in shear flow. Methods PMNs and TCs with different concentration ratios (PMN-TC ratio) were added into the parallel plate flow chamber, and changes in the numbers of transient and accumulative adhered TCs on ECs at different shear rates (50 s-1，100 s-1，200 s-1) were analyzed. Results The transient and accumulative adhesion of TCs on ECs at PMN-TC ratio of 3︰1 significantly increased as compared to that at PMN-TC ratio of 1︰1, especially under high shear flow condition (100 s-1 and 200 s-1). Moreover, in the 5 minute-observation period, the effect of PMN-TC ratio on TC adhered to ECs occurred earlier when the shear rate increased. Conclusions The increase of PMN-TC concentration ratio can promote TC adhesion to ECs in shear flow, and the research findings provide significant references for studying TC metastasis in blood vessels and the target therapy of tumors.

TNF-α promotes the quantity and ICAM-1 expression of endothelial microparticles / 医用生物力学

Objective To study the role of cyclic strain-modulated tumor necrosis factor-α (TNF-α) played in the quantity and intercellular cell adhesion molecule-1(ICAM-1) expression of endothelial microparticles (EMPs). Methods The endothelial cells (ECs) primarily cultured from rat aorta were applied with 5% cyclic strain (to simulate normal physiological condition) and 18% cyclic strain (to simulate hyper-tension condition), respectively, by using FX-4000T cyclic stain loading system for 24 hours at the loading frequency of 1.25 Hz. The mRNA expression of TNF-α under different amplitudes of cyclic strain was determined by real time-PCR. The TNF-α was then used to stimulate the ECs from rat aorta, and the supernatants were collected and ultracentrifuged to get endothelial microparticles (EMPs), which were then identified by lipophilic styryl membrane staining and transmission electron microscope for morphological identification. The quantities of Annexin V positive EMPs under TNF-α stimulation were counted by flow cytometer and ICAM-1 expression on EMPs was detected as well. Results Compared with the 5% normal cyclic strain, under 18% high cyclic strain condition,the mRNA expression of TNF-α in ECs increased significantly. TNF-α could then significantly up-regulate the production of Annexin V positive EMPs and promote the expression of ICAM-1 on EMPs. Conclusions The over-expression of TNF-α in ECs under high cyclic strain might mediate the high production of EMPs and over-expression of ICAM-1 on EMPs. The research findings will provide new experiment evidence for further studying the role of EPCs in the mechanobiological mechanism of vascular remodeling.

Interactions between vascular endothelial cells and smooth muscle cells under shear stress / 医用生物力学

Endothelial cells (ECs) and smooth muscle cells (SMCs) are the most crucial components of the vascular wall, and the interactions between them are essential for the maintenance of normal vascular physiology, as well as the initiation and development of cardiovascular diseases. Various typical co-culture models have been developed to simulate the location and growth situation of ECs and SMCs in vivo. In this review, the co-culture systems combined with the device applying fluid shear stress were introduced with discussion on the strengths and limitations of each system. The influences of ECs-SMCs interaction on the phenotype and alignment of ECs and SMCs, growth and migration of SMCs, and adhesion molecules expression of ECs under shear stress were briefly reviewed. The established evidence indicates that nitric oxide (NO), cytokines and microRNA are the most important signal molecules mediating the interactions between ECs and SMCs.

Effects of ghost red blood cells on tumor cell adhesion in shear flow / 医用生物力学

Objective To study the effect of ghost red blood cells (GRBCs) on white blood cell (WBC)-mediated adhesion of tumor cells (TCs) on endothelial cells (ECs) in shear flow. Methods GRBCs with hematocrit (Hct) of 20% were added in the parallel plate flow chamber to observe changes in the number of tethered WBCs on ECs, the collision between TCs and adhesive WBCs, and the number of firmly adhered TCs at different shear rates of 62.5, 100, 200 s-1, respectively. Results GRBCs could increase the number of adhered WBCs on ECs and the collision between TCs and adhesive WBCs, and finally enhance the adhesion of TCs on ECs, especially at high shear rate (200 s-1). However, the adhesion efficiency of TCs was not significantly influenced by GRBCs. Conclusions GRBCs in shear flow can promote TC adhesion on ECs, and the research finding will provide a theoretical basis for cancer therapy.

The role of microRNA-34a in low shear stress- induced proliferation of vascular smooth muscle cells / 医用生物力学

Objective To investigate the role of microRNA-34a (miR-34a) in the proliferation of vascular smooth muscle cells (VSMCs) induced by low shear stress (LowSS). Methods Using co-culture parallel plate flow chamber system, endothelial cells (ECs) and VSMCs were co-cultured and applied with normal shear stress (1.5 Pa) and LowSS (0.5 Pa) for 12 h. The expression of proliferating cell nuclear antigen (PCNA) in the co-cultured VSMCs was detected by Western blotting to determine the proliferation capacity of VSMCs. Real-time PCR was used to examine the miR levels of miR-34a in the co-cultured VSMCs. The target proteins of miR-34a were predicted by TargetScan, miRWalk and some other websites. Western blotting was used to detect expression of Forkhead box j2 (Foxj2) in the co-cultured VSMCs. Mimics and inhibitor were used to up-regulate or inhibit the expression of miR-34a, and then the expression of Foxj2 and PCNA was detected by Western blotting to verify the regulation relationship between miR 34a and Foxj2. Results Compared with NSS, LowSS promoted the PCNA expression and significantly up-regulated the miR-34a expression in the co-cultured VSMCs. Foxj2 was predicted to be the downstream target protein of miR-34a by TargetScan, miRWalk and some other websites. Foxj2 expression decreased significantly in the co-cultured VSMCs under LowSS application. Under static condition, the expression of Foxj2 obviously decreased and the expression of PCNA obviously increased by up-regulating miR-34a expression in VSMCs. While inhibiting the expression of miR-34a in VSMCs would result in a significant increase in the expression of Foxj2 and a significant decrease in the expression of PCNA. Conclusions LowSS can promote the proliferation of VSMCs by regulating miR-34a and target protein Foxj2 in the co-cultured VSMCs. This research finding will provide new mechanobiological experimental reference for further illustrating the pathogenesis of atherosclerosis and finding the therapeutic targets for drugs.

In ovo administration of human recombinant leptin shows dose dependent angiogenic effect on chicken chorioallantoic membrane

BACKGROUND: Leptin, the cytokine produced by white adipose tissue is known to regulate food energy homeostasis through its hypothalamic receptor. In vitro studies have demonstrated that leptin plays a major role in angiogenesis through binding to the receptor Ob-R present on ECs by stimulating and initiating new capillary like structures from ECs. Various in vivo studies indicate that leptin has diverse effect on angiogenesis. A few reports have showed that leptin exerts pro angiogenic effects while some suggested that it has antiangiogenic potential. It is theoretically highly important to understand the effect of leptin on angiogenesis to use as a therapeutic molecule in various angiogenesis related pathological conditions. Chicken chorio allantoic membrane (CAM) on 9th day of incubation was incubated with 1, 3 and 5 µg concentration of HRL for 72 h using gelatin sponge. Images where taken after every 24 h of incubation and analysed with Angioguant software. The treated area was observed under microscope and histological evaluation was performed for the same. Tissue thickness was calculated morphometrically from haematoxylin and eosin stained cross sections. Reverse transcriptase PCR and immunohistochemistry were also performed to study the gene and protein level expression of angiogenic molecules. RESULTS: HRL has the ability to induce new vessel formation at the treated area and growth of the newly formed vessels and cellular morphological changes occur in a dose dependent manner. Increase in the tissue thickness at the treated area is suggestive of initiation of new capillary like structures. Elevated mRNA and protein level expression of VEGF165 and MMP2 along with the activation of ECs as demonstrated by the presence of CD34 expression supports the neovascularization potential of HRL. CONCLUSION: Angiogenic potential of HRL depends on the concentration and time of incubation and is involved in the activation of ECs along with the major interaction of VEGF 165 and MMP2. It is also observed that 3 µg of HRL exhibits maximum angiogenic potential at 72 h of incubation. Thus our data suggest that dose dependent angiogenic potential HRL could provide a novel role in angiogenic dependent therapeutics such as ischemia and wound healing conditions.

Application of situational teaching based on ECS in medical nursing teaching / 中国实用护理杂志

Objective To study on the effect of situational teaching based on ECS in medical nursing teaching.Methods 93 nursing students were divided into the experimental group (45 cases) and the control group (48 cases).The experimental group adopted ECS in the medical nursing situational teaching,while the control group used conventional teaching method.The teaching results between the two groups were compared between two groups.Results Two groups had significant differences in the medical nursing theory test and the operation skills examination.The students in the experimental group had higher recognition on the situational teaching based on ECS,especially in the learning initiative and interest,pathology observation ability and the unity cooperation ability,the differences showed statistical difference.Conclusions The application of ECS in the medical nursing situational teaching can stimulate the learning interest of the nursing students,help the cultivation of clinical thinking ability,relieve the contradiction of resources strain in nurses clinical probation and promoting the improvement of medical nursing teaching.

Preliminary study of cervical lymph node extracapsular spread direction of oral squamous cell carcinoma / 实用口腔医学杂志

Objective:To study the direction of cervical node extracapsular spread(ECS)of oral squamous cell carcinoma(OSCC). Methods:57 cases of OSCC were treated by combined radical operation.The relationship between ECS and T stage,tumor thick-ness,differentiation degree of OSCC,lymph node size and the ECS direction in each lymph node level were statistically analysed. Results:ECS was found in 30 of the 57 cases,and in 78 of the 174 metastasis positive lymph nodes.29 ECS nodes in levelⅠ,the frequency of the shallow side was 26,the deep side 13(P=0.000 3).But the difference in other levels was not statistically signifi-cant(P>0.05).It was not statistically significant between the incidence of ECS and T stage;it was statistically significant between the incidence of ECS and tumor thickness(P<0.05),tumor differentiation degree(P<0.05)and the lymph node size(P<0.01). Conclusion:ECS of OSCC on the shallow side is more than that in the deep side of lymph nodes in levelⅠ.ECS is positively corre-lated with the tumor thickness of OSCC,metastasied lymph node size;negatively related to the differentiation degree of OSCC.

Shear stress modulates the proliferation of vascular smooth muscle cells via receptor for activated C kinase 1 / 医用生物力学

Objective To investigate the role of receptor for activated C kinase 1 (RACK1) in vascular smooth muscle cells (VSMCs) proliferation modulated by co-cultured endothelial cells (ECs) and shear stress. Methods Using EC/VSMC co-cultured parallel plate flow chamber system, two levels of shear stress, i.e. low shear stress (LowSS, 0.5 Pa) and normal shear stress (NSS, 1.5 Pa), were applied for 12 h. BrdU ELISA was used to detect the proliferation of VSMCs, and Western blot was used to detect the protein expressions of RACK1 and phosphor-Akt. Under the static condition, RNA interference was used to suppress the expression of RACK1 in VSMCs, and then the proliferation of VSMCs and expressions of RACK1 and phosphor-Akt were detected. By using co-culture model (ECs/VSMCs) and separated culture model (ECs//VSMCs), the effect of ECs on expressions of RACK1 and phosphor-Akt in VSMCs was further analyzed. Results Comparative proteomic analysis revealed that LowSS increased the expression of RACK1 in rat aorta. In vitro experiments showed that LowSS induced the proliferation, expressions of RACK1 and phospho Akt in VSMCs co-cultured with ECs. Target RNA interference of RACK1 significantly decreased the proliferation of VSMCs, and the phosphorylation of Akt. In comparison with ECs//VSMCs (separated culture) group, the expression of RACK1 and phosphor-Akt were both up-regulated in the VSMCs co-cultured with ECs (ECs/VSMCs group). Conclusions The expression of RACK1 in VSMCs was modulated by shear stress and neighboring ECs, which might induce cellular proliferation via PI3K/Akt pathway. The investigation on VSMC proliferation and the involved biomechanical mechanism will contribute to understanding and help preventing the pathogenesis and progress of atherosclerosis.

Role of focal adhesion kinases in adhesion and migration of endothelial cells / 医用生物力学

Objective To investigate the effect of focal adhesion kinases (FAK) inhibitor with different concentration on the adhesion and migration of endothelial cells (ECs) and the expression of downstream Rac1 protein, and to explore the role of FAK in adhesion and migration of ECs by using FAK inhibitor to inhibit the phosphorylation of Y397 site of FAK. Method Scratch wound migration assay was performed to examine the effect of FAK inhibitor with different concentration (from 0 nmol/mL to 250 nmol/mL) on ECs migration at 2, 4, 8 and 24 h, respectively. Western blot combined with immunofluorescence analysis were performed to determine the effect of FAK inhibitor with different concentration on distribution and expression of Rac1 protein. Results With the concentration of FAK inhibitor increased, ECs migration distance and the Rac1 protein expression decreased. Conclusions The inhibition of FAK phosphorylation could inhibit cell adhesion and migration with the decrease in downstream Rac1 protein, and ECs adhesion/migration was related to FAK Rho GTPases signaling pathways.

Effect from different pore sizes of co-culture inserts on the permeability of platelet derived growth factor / 医用生物力学

Objective To investigate the effect from different pore sizes of co culture inserts on the permeability of biomacromolecules through polyethylene terephthalate (PET) membrane so as to solve the key technology problem in mechanobiology experiment on vascular cells. Methods Inserts with 0.4 μm and 1.0 μm pores on the PET membrane were studied using flow chamber system. Low shear stress was subjected to the co-cultured system of endothelial cell (EC)/vascular smooth muscle cell (VSMC) and the concentration of platelet-derived growth factor BB (PDGF-BB) was detected by ELISA. Under the static condition, vascular cells were cultured on the plate (with no cell on PET membrane), on the outer side of PET membrane, and on the both sides of PET membrane, respectively. Then the recombinants PDGF-BB (rPDGF-BB) were added on the different sides of PET membrane. Western blotting was used to detect the change in expressions of p-ERK1/2, p-Akt and Lamin after cells were stimulated by rPGDF BB. Results After low shear stress subjection for 12 h, the concentration of PDGF-BB in the medium from VSMC side was significantly higher than that from EC-side. rPDGF-BB passed through 0.4 μm and 1.0 μm pores on the PET membrane and modulated expressions of p-ERK1/2, p-Akt and Lamin A in cells cultured on the opposite side of PET membrane and cells cultured on the plate separately. When cells were cultured on the both sides of PET membrane, rPDGF-BB only stimulated cells cultured on the same side of 0.4 μm pores on PET membrane, but had no specific effect on cells cultured on the opposite side. Conclusions PET membrane with both 0.4 μm and 1.0 μm pores was permeable to PDGF-BB, and cells cultured on the membrane could affect the permeability. The efficiency of PDGF BB passing through 0.4 μm pores was significantly repressed with cells cultured on the both sides, which was more similar to that in vivo.

Sustained Expression of Neuritin mRNA After Repeated Electroconvulsive Stimulations in the Rat Hippocampal Formation

In the present study, we compared the expression patterns of neuritin mRNA in the dentate gyrus of hippocampal formation following single (1xECS) or repeated elctroconvulsive seizures (8xECS) treatments to the rat. The expression of neuritin mRNA was transiently increased, and returned to basal level within 12 hours after 1xECS. Whereas initial induction of neuritin mRNA was similarly seen, these increased mRNA level was maintained for 24 hours in 8xECS group. In contrast, induction profile of BDNF was similar following 1x and 8xECS. These results suggest that regulation of neuritin expression may be plastically changed by repeated ECS treatment.

Changes of AP-1 Binding Activities in Rat Brain by Electroconvulsive Shock / 신경정신의학

OBJECTIVES: ECS could have therapeutic effects on psychiatric illnesses by inducing IEGs, which in turn regulates expression of their target genes. We observed AP-1 binding activity and identified AP-1 binding proteins in NMDAR1, late response gene of IEGs, which considered as the candidate gene for schizophrenia. METHODS: By gel shift assay and supershift assay, we observed binding activities and AP-1 binding proteins in NMDAR1. Because IEGs are induced rapidly but transiently by external stimuli, there is a possibility that the expression of IEGs is negatively feedbacked by their own products via their AP-1 binding sites. For that purpose, we also observed AP-1 binding activity of c-fos and c-jun via gel shift and supershift assay. RESULTS: ECS increased AP-1 binding activities of NMDAR1 gene, contributed by c-Fos and its related proteins. Peak of the increased binding was 60 minutes in both hippocampus and cerebellum. Though expression of c-Fos and c-Jun were increased by ECS, there were no changes in AP-1 binding activities after ECS. AP-1 sites of IEGs were binded by CREB, regardless of ECS. CONCLUSION: There is a possibility that ECS induced IEG expression, and then incresed expression of NMDR1 by binding of expressed IEGs to the AP-1 site of NMDAR1. ECS did not increase AP-1 binding activities of IEGs. This suggests that the regulation of IEGs' expression can not be influenced mainly by AP-1 site.

Application of emergency care simulator teaching in"shock"during clinical bed side teaching / 中华医学教育探索杂志

To explore the teaching model and effect of emergency care simulator(ECS) teaching in "Shock"during clinical bed side teaching,fifty-six students were randomly divided into two groups, receiving model and traditional teaching model respectively. After one semester,the students’examination results and general effect were evaluated. The students’ex-amination results,clinical theory and clinical skills in ECS teaching group were significantly better than traditional teaching group.

Effect of Panax ginseng on latency of passive avoidance response and neuronal damage of hippocampus

The effects of crude saponin (SAP) and alkaloid (ALK) fractions of Panax ginseng C.A. Meyer on the detrimental effects of electroconvulsive shock (ECS) and scopolamine on passive avoidance response (PAR) were studied in male Sprague-Dawley rats, referring their effects on the neuronal injury and plasticity of hippocampus in response to electrolytic lesion of left entorhinal cortex (ECL). The detrimental ECS effect on PAR was attenuated by pre- and post-treatments with SAP and ALK, respectively, or by pretreatment with aminoguanidine (AG), an inhibitor of diamine oxidase and NO synthase. And the detrimental scopolamine effect on PAR was also inhibited by pretreatment with ALK or AG, and by posttreatment with SAP or ALK, respectively. On the 7th day after ECL, the brain sections stained by cresyl violet and by acetylcholinesterase (AChE) histochemistry, respectively, showed the chromatolysis and numeral decrease of neurons and the reduction of AChE reactivity in the hippocampus CA1 area and to a lesser extent, in the dentate gyrus. The neuronal cell death of the CA1 area was significantly reduced by SAP, ALK, or AG, and the reduction of AChE reactivity was significantly attenuated by SAP or ALK and to a lesser extent by AG. These results suggests that the protective effect of ginseng SAP and ALK fractions on ECS- or scopolamine-induced impairment of PAR may be ascribed in part to preservation of hippocampal neurons, particularly cholinergic neurons.