[Tumor necrosis factor-alpha regulates the proliferation and syndecan-4 expression of human umbilical vein endothelial-like cells cultured in vitro].

OBJECTIVE: To investigate the effects of tumor necrosis factor-alpha(TNF-alpha) on syndecan-4 protein expression and proliferation of cultured human umbilical vein endothelial-like cells (HUVECs) in vitro. METHODS: HUVECs exposed to different concentrations of TNF-alpha(100, 20, 10, and 1 ng/ml) were cultured for 24 h and 36 h to observe their proliferation in comparison with the control group. The cell proliferation rate was determined by non-radioactive MTS/PES assay. The expression of syndecan-4 protein was evaluated by immunoblotting technique using anti-syndecan-4 antibody. Results The proliferation rate of the endothelial-like cells was 1.956-/+0.214 in the control group, and 2.154-/+0.250, 2.260-/+0.151, 2.118-/+0.205 and 2.106-/+0.136 in TNF-alpha-treated groups corresponding to TNF-alpha concentrations of 100, 20, 10 and 1 ng/ml at 24 h, respectively. It was shown that TNF-alpha significantly stimulated cell proliferation at the concentration above 1 ng/ml (P<0.05) as compared with the control group (P<0.05). The proliferation rate of the endothelial-like cell was 1.915-/+0.236 in the control group, and 2.067-/+0.328, 2.207-/+0.150, 2.052-/+0.126 and 2.051-/+0.180 in TNF-alpha-treated groups corresponding to TNF-alphaconcentrations of 100, 20, 10 and 1 ng/ml at 36 h, respectively. The expression of syndecan-4 protein was significantly enhanced by TNF-alpha. CONCLUSIONS: TNF-alpha can stimulate HUVEC proliferation, and expression of syndean-4 may represent an additional component of the pro-inflammatory, growth-stimulating pathways that are activated in response to changes in the vascular wall.

[Experimental study of the characteristics of renal blood flow with contrast ultrasound].

OBJECTIVE: To study the characteristics of renal blood flow with contrast ultrasound. METHODS: The examination of the renal ultrasonography was performed in 10 dogs after intravenous injection of Quanfuxian (a contrast agent consisting of C3F8 microbubbles). RESULTS: Contrast visualization appeared in the renal cortex and then in the outer to inner medulla at the baseline level after administration of the contrast agent. Notable differences in the values of microvascular volume (A, which was 120.3 in the corted vs 110.8 in the medulla, P>0.05), microcirculatory flow velocity (beta, which was 1.39 in the corted vs 0.54 in the medulla, P<0.05), and microcirculatory flow rate (A x beta, 167.4 in the corted vs 59.5 in the medulla, P<0.05) were found between the corted and the medulla, with also marked difference between the the corted-to-the medulla ratios of beta and A (0.612 vs 0.078, P<0.05). CONCLUSION: Contrast ultrasound of the kidney provides a useful means of renal circulatory flow study.

[An experimental study on renal microvascular perfusion in dogs with acute cardiac insufficiency].

OBJECTIVE: To investigate the changes and the effects of captopril on the renal blood flow and microvascular perfusion in dogs with acute cardiac insufficiency. METHODS: Acute cardial insufficiency was induced by combining occlusion of the left anterior descending artery with right ventricular pacing in 12 mongrel dogs. The ascending aorta and left kidney were dissected and ultrasonic flow probes were placed on ascending aorta and renal artery to monitor cardiac output (CO) and renal blood flow (RBF). Contrast-enhanced ultrasound of the kidney was performed as CO was reduced to 25% (LCO25%) and 50% (LCO50%) from the basic measurement and microvascular flow velocity (beta), microvascular volume (A) and microvascular blood flow (renal cortex) were observed. After CO reduced to 50%, captopril 1 mg/kg and 2 mg/kg were injected successively and contrast-enhanced ultrasound of the kidney were performed again before and after injection. RESULTS: At baseline, CO, RBF, CXbeta (beta of renal cortex), A and A x beta were (1.46 +/- 0.16) ml/min, (107.5 +/- 35.7) ml/min, 1.39 +/- 0.14, 120.3 +/- 14.8 and 167.4 +/- 25.0, respectively. After the LCO25% was reached, RAF, CXbeta, A and A x beta decreased to (72.50 +/- 32.4) ml/min, 0.87 +/- 0.082, 117.6 +/- 13.1, and 102.6 +/- 15.5, respectively. The corresponding values after the LCO50% was reached were (44.1 +/- 17.2) ml/min, 0.61 +/- 0.039, 106.9 +/- 12.0, and 64.7 +/- 8.83, respectively. It is suggested that the volume of the renal microvasculature remained stable until the LCO50% was reached. When captopril 1 mg/kg and 2 mg/kg were injected successively at LCO50%, MAP decreased from (85.4 +/- 7.8) mm Hg to (78.7 +/- 7.3) mm Hg and to (69.1 +/- 6.3) mm Hg (P < 0.05), respectively, while CO increased from 0.73 +/- 0.084 to 0.83 +/- 0.065 and to 0.9 +/- 0.054 (P < 0.05), respectively. RBF increased from (44.1 +/- 17.2) ml/min to 60.3 +/- 17.8 and to 79.4 +/- 17.8 (P < 0.05), respectively. After captopril 1 mg/kg and 2 mg/kg were injected, the increased flow ratios with CO were 0.15 +/- 0.084 and 0.31 +/- 0.011, respectively, and with RBF were 0.29 +/- 089 and 0.522 +/- 0.040, respectively. The increased renal blood flow ratio was higher than that of CO after captopril was used. The corresponding increases were from 0.61 +/- 0.039 to 0.75 +/- 0.020 and to 0.86 +/- 0.027 for CX beta, from 106.9 +/- 11.9 to 115.4 +/- 11.1 and to 116.6 +/- 8.9 for A, from 64.7 +/- 8.83 to 87.0 +/- 8.6 and to 100.6 +/- 8.9 for A x beta, respectively. CONCLUSION: The renal microvasculature plays a role by keeping its volume stable in the protection against renal ischemia when acute cardiac output decreases slightly. The role of captopril to improve renal microvascular perfusion is independent of increased total cardiac output or increased systemic blood pressure.

[Quantification of renal medullary perfusion with contrast-enhanced ultrasound: an experimental study].

OBJECTIVE: To quantitatively evaluate the effects of dopamine (DA) and noradrenaline (NE) on renal medullary perfusion and the differences in perfusion in the outer and inner medulla using contrast-enhanced ultrasound. METHODS AND RESULTS: Contrast-enhanced ultrasound was performed in 10 dogs with simultaneous renal artery flow (RAF) measurement at the baseline level and during application of 3 different doses of DA and NE. During treatment with the 3 doses of DA, the changes of ultrasound-derived parameters (A, beta and A*beta) in the medulla were similar to the changes in the cortex. As compared with the baseline level, the ratios between the cortex and medulla exhibited no significant difference in A, beta and A*beta during DA treatment (P>0.05). No significant difference in ultrasound-derived medullar parameters was noted in dogs with NE treatment from the baseline level (P>0.05). However, a progressive decrease in the ratios of A, beta and A*beta between the cortex and medulla was noted during NE treatment in comparison with the baseline level (P<0.05). The velocity (beta) and perfusion (A*beta) of blood flow in the medulla decreased progressively from the outer medulla to the inner medulla at baseline (P<0.05), while the blood volume (A) remained unchanged (P<0.05). CONCLUSIONS: The changes of blood flow in both the cortex and medulla are identical during DA treatment but different in the presence of NE. The progressive decrease in perfusion from the outer medulla to the inner medulla is attributed to the decrease in the velocity of blood flow.

[Targeted adhesion of platelet receptor-specific microbubble agent to thrombus in vitro].

OBJECTIVE: To examine the thrombus-targeting effect of platelet receptor-specific lipid microbubbles. METHODS: The targeted microbubbles were prepared by coupling Arg-Gly-Asp-Ser (RGDS) with the lipid microbubbles, which were added to the microthrombus generated by platelet aggregation. The effects of the targeted microbubbles on the ultrasonic signal was observed in an artificial thrombus model. RESULTS: The targeted microbubbles were adhesive to the microthrombus, while the non-targeted microbubbles did not possess this property. The ultrasonic signal of the thrombus border was enhanced significantly after the addition of the targeted microbubbles. CONCLUSIONS: Platelet receptor-specific microbubbles possess significant adhesive property to the thrombus and can improve signal-to-noise ratio of the thrombus, suggesting the potential value of the targeted microbubbles for clinical application in the diagnosis and treatment of thrombus.

[Quantitative evaluation of canine renal blood flow with contrast-enhanced ultrasound].

OBJECTIVE: To evaluate the accuracy of contrast-enhanced ultrasound (CEU) in renal blood flow quantification. METHODS: Regional renal perfusion was quantified with CEU in 10 dogs at the baseline level and after treatment with 3 doses of dopamine (3, 8 and 16 mg.kg(-1).min(-1)), and renal arterial flow (RAF) was measured with ultrasonic flow probes deployed directly on the renal artery simultaneously. Normalized RAF was calculated as RAF divided by renal weight (ml.min(-1).g(-1)). RESULTS: Compared with the baseline level, a progressive increase in RAF was induced by dopamine treatment at the doses of 3 and 8 mg.kg(-1).min(-1) (P<0.05), but at a higher dose of 16 mg.kg(-1).min(-1), the increment in RAF was reduced in comparison with that with the two lower doses (P<0.05). The same changes in cortical nutrient blood flow derived from CEU were observed. Significant positive correlation was found between normalized RAF and CEU-derived cortical nutrient blood flow (y=39.8x + 44.3, r=0.88, P<0.001). CONCLUSION: CEU can be used to accurately quantify renal blood flow in dogs.

[Establishment of a modified canine model of acute cardiac insufficiency].

OBJECTIVE: To establish a canine model of acute cardiac insufficiency (ACI) by coronary artery occlusion and right ventricular pacing. METHODS: Twelve dogs were subjected to rapid ventricular pacing after ligation of the left anterior descending coronary artery (LAD), to induce the cardiac output (CO) to reduce by 25%; and 50%; from the basal level. The arterial pressure (AP), arterial oxygen saturation (SaO(2)), mean right atrial pressure (mRAP), mean pulmonary capillary wedge pressure (mPCWP), and systemic vascular resistance (SVR) were measured in the dogs according to different CO conditions. Echocardiography was used to measure the cardiac size and left ventricular ejection fraction (LVEF). RESULTS: CO was decreased by 25%; and 50%; steadily from the basal level after right ventricular pacing following ligation of the LAD. AP and SaO(2) decreased while mRAP, mPCWP, and SVR increased significantly following CO reduction. The cardiac cavity became larger while LVEF decreased after CO was decreased by 25% and 50%. CONCLUSION: Canine model of ACI can be successfully established by right ventricular pacing following ligation of the LAD.

[Effects of a novel recombinant polypeptide from the sea anemone Anthopleura sp. on left ventricular function in dogs with acute cardiac insufficiency].

OBJECTIVE: To observe the effects of recombinant hk2a, a novel neurotoxin from the sea anemone Anthopleura sp., on left ventricular function of dogs with acute cardiac insufficiency. METHODS: Canine models of acute cardiac insufficiency were established by rapid ventricular pacing, in which the left ventricular ejection fraction (LVEF) was measured by Acuson ultrasound systems (Sequoia 512) at 0, 5, 15, 30 and 60 min, respectively, after intravenous injection of 30 microg/kg recombinant hk2a. The response of the canine models to hk2a treatments was observed in comparison with that of the dogs treated with Cedilanid (as positive control) and saline (as negative control). RESULTS: Intravenous injection of recombinant hk2a caused an immediate and significant increase in LVEF in the canine models of acute cardiac insufficiency (P<0.05), and the effect maintained for more than 30 min without significant effect on heart rate. Recombinant hk2a possessed such merits as quicker onset and greater potency in comparison with Cedilanid. CONCLUSION: Recombinant hk2a may significantly increase LVEF of the dogs with acute cardiac insufficiency.

[Ultrasound microbubbles promote thrombolysis of rabbit femoral artery thrombus].

OBJECTIVE: To evaluate the efficacy of intravenous ultrasound microbubbles for thrombolysis of arterial thrombus without using thrombolytic drugs. METHODS: Twelve rabbit models of acute bilateral femoral artery thrombosis were established and 6 of them received transcutaneous ultrasound and intravenous albumin microbubble treatment for thrombosis on one side while only microbubble treatment for the other side. The other 6 rabbits received ultrasound treatment on one side but no treatment on the other to serve as the control group. RESULTS: None of the 6 arteries treated with microbubbles alone and only 2 arteries treated with ultrasound alone in the 6 control rabbits were recanalized. All the 6 femoral arteries treated with microbubbles together with ultrasound were recanalized (P=0.014), with significantly shorter patent time and smaller residual thrombus cross-sectional area than those of the arteries with only ultrasound treatment (P=0.004 and P=0.003, respectively). CONCLUSION: Treatment with intravenous microbubbles assisted by transcutaneous ultrasound effectively promotes arterial thrombolysis in vivo, and this technique can be of significance in clinical treatment of acute thrombotic occlusions.

[Conditions of contrast ultrasound that affect the proliferation of rat smooth muscle cells].

OBJECTIVE: To investigate the effect of an echo-contrast agent on the proliferation of rat smooth muscle cells under different ultrasound conditions. METHODS: The vascular smooth muscle cells of rats were cultured with echo-contrast agent in 96-well plates, followed by exposure to ultrasound of different conditions. Trypan blue staining was performed 48 h later, and the proliferation of the cells observed by MTT assay. RESULTS: No cytotoxicity was found by trypan blue staining when the mechanical index of ultrasound was below 0.75. Compared with the control cells, the proliferation of the smooth muscle cells was decreased following the exposure as the mechanical index of ultrasound increased. The most obvious inhibition of cell proliferation was resulted when the microbubble concentration was 20% for a 60-second exposure. CONCLUSIONS: The inhibition of the vascular smooth muscle cell proliferation by echo-contrast agent destruction is correlated with the mechanical index of the ultrasound, concentration of the echo-contrast agent, and exposure time of ultrasound.