[The clinical effect of ultrasonic bone curette-assisted "zoning" style laminectomy for the treatment of severe ossification of thoracic ligamentum flavum].

Objective: To investigate the safety and clinical efficacy of "zoning" style laminectomy by ultrasonic bone curette in patients with severe thoracic ossification of the ligamentum flavum(TOLF). Methods: The clinical data of 36 patients with severe TOLF treated by "zoning" style laminectomy at Department of Spinal Surgery,Zhengzhou Orthopaedic Hospital from October 2015 to October 2018 were respectively analyzed.There were 17 males and 19 females,aged(57.3±10.2)years(range:43 to 80 years).According to the anatomical characteristics of the thoracic ligamentum flavum and the pathological process of ossionization,each decompression segment was divided into the upper 1/3 area of the lamina,the bilateral area of the ossionum flavum,the transitional area,and the area of close contact between the ossionum flavum and the spinal cord.Different surgical strategies were used for decompression in turn.The modified Japanese Orthopedic Association (mJOA) was used to evaluate the neurological function status before and after surgery,to evaluate the surgical effect of patients,and to observe the surgical complications.Paired sample T test was used for data analysis. Results: All 36 patients successfully completed the operation,the operation time was (88.6±24.6) minutes(range:60 to 150 minutes).The intraoperative blood loss was (426.7±167.4) ml(range:250 to 800 ml).Follow-up time was (27.2±7.7) months(range:12 to 48 months).The mJOA score at the last follow-up was 9.0±1.5,which was statistically significant compared with the preoperative score 5.4±1.8 (t=13.59,P<0.01).The improvement rate of mJOA score was (65.7±22.1) %,of which 17 cases were excellent (47.2%),13 cases were good (36.1%),4 cases were normal (11.1%),2 cases were ineffective (5.6%).Ten patients had cerebrospinal fluid leakage during the separation or removal of dural ossification and were cured after a series of comprehensive conservative treatment.Two patients showed transient neurological deterioration,and the neurological function gradually recovered to the preoperative state after comprehensive treatment such as increasing the mean arterial pressure and using neurotrophic drugs.During the follow-up,no aggravation of neurological dysfunction and segmental kyphosis were found. Conclusions: The ultrasonic bone curette-assisted "zoning" style laminectomy for the treatment of severe TOLF can directly observed the position relationship between ossification of the ligamentum flavum and the spinal canal structure during the operation,and accurately guide the surgical decompression.It has the advantages of safe operation and complete decompression,which provides an important reference for the selection of clinical surgery.

Protease supplementation attenuates the intestinal health damage caused by low-protein diets in Pekin ducks.

The objective of this study was to investigate the effects of low-protein diets with low digestibility of feed ingredients on intestinal damage and to explore whether the protease supplementation can alleviate the damage in Pekin ducks. A total of 576 Pekin ducklings (6 replicate pens, 16 ducks/pen) were randomly assigned to 6 dietary treatments (3 × 2 factorial arrangement) in a randomized complete block design. Factors were CP levels (13.5%, 15.5%, and 17.5%) and protease (0 or 20,000U/kg). Compared with the diets containing 17.5% CP, low-protein diets (13.5% CP) showed suppressed (P < 0.05) growth performance and feed intake (FI); reduced (P < 0.05) serum-free arginine, isoleucine, leucine, methionine, phenylalanine, valine, and proline as well as the cecal acetate and propionate concentration; increased (P < 0.05) plasma and ileal mucosal tumor necrosis factor-α (TNF-α) concentration; and downregulated (P < 0.05) mRNA expression of TNF-α, nuclear transcription factor-κb, interferon gamma, and Occludin in ileal mucosa. Irrespective of the dietary CP levels, protease supplementation significantly increased (P < 0.05) the serum-free glutamic acid concentration while decreasing (P < 0.05) the plasma endotoxin, IL-6, and the cecal isovalerate concentration. A significant interactive effect was observed between low-protein diets and protease supplementation (P < 0.05) on serum-free arginine concentration, the ratio of ileal villus height to crypt depth, and the IL-6 concentration in ileal mucosa. These results indicated that low-protein diets could damage intestinal integrity to induce systemic inflammation response and at last to suppress growth performance. Protease supplementation could partly attenuate the negative effects on gut health caused by low-protein diets in Pekin ducks.

Effects of dietary protein levels and protease supplementation on growth performance, carcass traits, meat quality, and standardized ileal digestibility of amino acid in Pekin ducks fed a complex diet.

This study aimed to investigate to the effects of dietary CP levels and protease supplementation on growth performance, carcass traits, meat quality, nutrients utilization, and standardized ileal digestibility of amino acid in Pekin ducks fed a complex diet. A total of 960 14-day-old male ducks were weighed and randomly allotted to a 2 × 5 factorial arrangement of 10 treatments with 6 replicate pens per treatment and 16 ducks per pen fed to 49 D of age. Experimental factors included five dietary CP levels ranging from 13.5 to 17.5% and with or without protease (200 mg/kg) supplementation. Between day 28 to 34, the digestible and metabolizable trials were performed. Significant CP × protease interactions (P < 0.05) on breast meat yield, DM, energy and nitrogen utilization, as well as standardized ileal digestibility values of 7 amino acids were observed. Regardless of protease supplementation, ducks fed 13.5, 14.5, and 15.5% CP had a poorer (P < 0.05) growth performance and breast meat yield than ducks fed with 16.5 and 17.5% CP. Ducks fed 13.5% CP had a positive effect (P < 0.05) on meat quality, dietary DM, energy and nitrogen utilization as well as standardized ileal digestibility of amino acids. Protease supplementation increased (P < 0.05) DM and phosphorus retention and decreased (P < 0.05) shear force of breast meat, regardless of CP level; when CP = 14.5%, protease significantly increased (P < 0.05) breast muscle yield. The optimal CP requirement without or with protease supplementation for BWG and FI were 17.02 or 16.53% and 16.64 or 16.75%, respectively, based on linear broken-line regression.

Development of Al-TiCN nanocomposites via ultrasonic assisted casting route.

This work provides a promising approach to achieve the uniform distribution of TiCN nanoparticles (NPs) in aluminum matrix via a combination of ultrasonic dispersion and fast cooling processing. Microstructure analysis demonstrates that as the cooling rate is increased, the NP distribution in the matrix varies from intergranular to intragranular at micro scale and the NP-matrix interface from incoherent to coherent at nano scale. An analytical model is proposed to unveil the effects of cooling rates on the behavior of NPs at the solidification front. The theoretical analysis reveals that the NP size and cooling rate are the two prominent factors determining the NP distribution during solidification of nanocomposites. The experimental results yield an insight into the understanding of NP-induced microstructural evolution and shed new light on the development of high-performance nanocomposites.

Endothelin in myocardial ischaemia and reperfusion.

Endothelin-1 (ET-1) is an extremely potent vasoconstrictor peptide derived from vascular endothelial cells. ET-1 can also be produced by other cell types such as smooth muscle cells and cardiomyocytes. Plasma levels of ET-1 are elevated during several different cardiovascular disorders like atherosclerosis, myocardial infarction and congestive heart failure. During and following myocardial ischaemia and reperfusion, the myocardial production and release of ET-1 is stimulated and the coronary constrictor response to ET-1 is enhanced. These findings all favour a pathophysiological role for ET-1 in the development of ischaemia/reperfusion injury. Accordingly, by using different pharmacological tools (monoclonal antibody, ET converting enzyme inhibitor or ET receptor antagonists) that block the biological actions of ET-1, myocardial ischaemia/reperfusion injury has been demonstrated to be reduced in experimental animal models, in terms of both reduction in final infarct size and improved recovery of myocardial performance and coronary flow. However, some studies have shown no cardioprotective effects of ET receptor antagonists. Possible explanations for these apparently conflicting results are differences in animal species used, route and timing of drug administration, experimental protocol and chemical nature of the antagonists. The potential mechanisms underlying the cardioprotective effects of ET antagonists are discussed and include prevention of no-reflow, inhibition of ET-induced neutrophil activation, abolishment of direct pro-ischaemic actions of ET on myocytes, and interruption of interference of ET with the renin-angiotensin system.

The endothelin A receptor antagonist LU 135252 protects the myocardium from neutrophil injury during ischaemia/reperfusion.

OBJECTIVE: Endothelin-1 (ET-1) is not only a potent vasoconstrictor but also a stimulator of polymorphonuclear leukocyte (PMN) aggregation and adhesion. The aim of this study was to investigate whether an ETA receptor antagonist attenuates the PMN-mediated contractile dysfunction following myocardial ischaemia. METHODS: Isolated rat hearts were perfused according to the Langendorff method. The hearts were subjected to global ischaemia and reperfused with buffer solution only, or human PMNs dissolved in rat plasma (HNRP). RESULTS: In an initial study, the ETA receptor antagonist LU 135252 (1 and 10 mumol/l) or ET-1 (1 and 10 nmol/l) did not significantly affect the recovery of left ventricular developed pressure (LVDP), end-diastolic pressure (LVEDP), the first derivative of left ventricular pressure (dP/dt) or the rate pressure product (RPP) during reperfusion with buffer solution only compared to a vehicle group. In a second study on hearts reperfused with HNRP, administration of LU 135252 (10 mumol/l) significantly enhanced the recovery of LVDP, dP/dt and RPP in hearts reperfused with HNRP. LVEDP was 20 mmHg lower in hearts given LU 135252 than vehicle in combination with HNRP (P < 0.05). The outflow of PMNs in the coronary effluent during reperfusion was 41 +/- 8% in hearts given LU 135252 compared to 9 +/- 5% in vehicle-treated hearts (P < 0.01). There was a significant correlation between the myocardial functional recovery and the outflow of PMNs. Administration of ET-1 (0.1 and 1 nmol/l) in combination with HNRP resulted in complete loss of contractile function and no outflow of PMNs during reperfusion. CONCLUSION: The ETA receptor antagonist LU 135252 protects from ischaemia/reperfusion injury in the isolated rat heart in the presence of PMNs. It is suggested that inhibition of PMN-induced injury during reperfusion is an important cardioprotective action of LU 135252.

Protective effects of non-peptide endothelin receptor antagonist bosentan on myocardial ischaemic and reperfusion injury in the pig.

OBJECTIVE: The aim was to investigate the effects of the non-peptide endothelin receptor antagonist bosentan (Ro 47-0203) on haemodynamic variables, infarct size, myocardial overflow, and tissue content of endothelin-like immunoreactivity (ET-LI) during ischaemia and reperfusion in anaesthetised pigs, and to study the inhibitory effect of bosentan on ET-1 induced coronary constriction in vitro. METHODS: Ischaemia was induced by ligation of the left anterior descending coronary artery for 45 min, followed by 4 h of reperfusion. Bosentan was given either intravenously (5 mg.kg-1) 15 min before ischaemia or as a 25 min local coronary venous retroinfusion (10(-4) M) starting at 30 min of ischaemia. ET-LI was analysed in myocardial tissue and in plasma from the anterior interventricular coronary vein and aorta. The effect of bosentan on endothelin-1 induced vasoconstriction was evaluated in isolated diagonal branches of left anterior descending coronary artery. RESULTS: Intravenous bosentan slightly reduced arterial blood pressure (P < 0.05) but did not affect basal coronary vascular resistance. Local retroinfusion of bosentan did not change blood pressure. Intravenous and retroinfused bosentan significantly reduced infarct size by 58% and 48% respectively (P < 0.01) and enhanced the recovery of coronary blood flow by 65-90% compared to vehicle treated controls at the end of 4 h reperfusion. The basal plasma levels of ET-LI and the myocardial overflow of ET-LI during reperfusion increased twofold after bosentan. A threefold increase in the concentration of ET-LI was observed in the ischaemic/reperfused myocardium and this enhancement was significantly attenuated by bosentan. Bosentan effectively antagonised the endothelin-1 induced but not the serotonin induced, contractions of isolated coronary arteries and reversed the established contraction induced by endothelin-1. CONCLUSIONS: The non-peptide endothelin receptor antagonist bosentan markedly protects the myocardium from ischaemia/reperfusion injury and improves blood flow to the reperfused area, indicating the involvement of endogenous endothelin-1 and the therapeutic value of bosentan in the treatment of ischaemia/reperfusion injury.

Antithrombotic activity of inogatran, a new low-molecular-weight inhibitor of thrombin, in a closed-chest porcine model of coronary artery thrombosis.

OBJECTIVE: To characterize the antithrombotic activity of inogatran per se in a porcine model of copper-coil-induced coronary artery thrombosis and to compare its effect with that of heparin and ASA. METHODS: Forty-eight pigs were assigned to one of the following groups: (1) saline; (2) heparin, (a) 75 and (b) 150 IU/kg/h; (3) acetylsalicylic acid (ASA), 12.5 mg/kg; (4) ASA 12.5 mg/kg + inogatran, 0.06 mg/kg/h; (5) ASA 12.5 mg/kg + inogatran, 0.30 mg/kg/h; (6) inogatran, 0.30 mg/kg/h; (7) inogatran, 0.60 mg/kg/h; (8) inogatran, 1.5 mg/kg/h. Computerized vectorcardiography was applied to monitor coronary occlusion and reperfusion. RESULTS: Cumulative time in which coronary arteries were patent, expressed as a percentage of the treatment time (i.e., 90 min) in heparin- and ASA-treated pigs, was 8 +/- 6 and 14 +/- 7%, respectively. This is not significantly different from placebo-treated pigs. Inogatran-treated pigs showed a dose-dependent antithrombotic effect, and the average patency rates were 34 +/- 39, 54 +/- 37 and 80 +/- 32%, in groups 6, 7 and 8, respectively. Combined treatment with inogatran and ASA did not significantly improve the antithrombotic effect. A partial antithrombotic effect of inogatran was maintained for, on average, at least 150 min after the end of treatment, as evidenced by patency rates of 31 +/- 43, 52 +/- 48 and 62% +/- 44, in groups 6, 7, and 8, respectively. CONCLUSION: Inogatran inhibits the formation of arterial thrombosis more effectively than heparin or ASA. Inhibition of clot-bound thrombin and thrombin-induced platelet activation may be the mechanisms behind this effect. Our findings also suggest that a thrombus formed in the presence of inogatran is more susceptible to spontaneous endogenous fibrinolysis.

Coronary venous drug infusion in the ischaemic-reperfused isolated rat heart.

OBJECTIVES: Coronary venous retroinfusion (CVR) has been used experimentally in large animals for selective drug delivery into ischaemic myocardium. It would be an advantage if CVR could also be used in isolated perfused rat heart models. The aim of the present paper is to develop a regional ischaemic model in the isolated perfused rat heart combined with CVR. METHOD: Pharmacokinetic study: The spatial distribution of retrogradely infused felodipine (used as a tracer) during regional myocardial ischaemia was investigated. Following occlusion of the left coronary artery, felodipine was administered over a period of 5 min by CVR. Ischaemia-reperfusion study: Following 30 min of stabilisation, 14 rat hearts were subjected to 60 min of regional ischaemia followed by 60 min of reperfusion. Felodipine (0.7 nmol/kg, n = 7) or vehicle (n = 7) was administered by means of CVR. The infusion was given during the last 5 min of ischaemia at a rate of 0.6 ml/min. RESULTS: Pharmacokinetic study: By means of CVR, the compound was distributed specifically into the ischaemic myocardium. The highest tissue concentration was obtained when the coronary vein was occluded during CVR. The maximal concentration in the ischaemic myocardium was 20-70 times that in the non-ischaemic areas. A transmyocardial gradient was noted with higher drug concentration in the subepicardial zone. Ischaemia-reperfusion study: At the end of reperfusion, the recovery of coronary flow, left ventricular developed pressure and double product (DP; LVDP x HR) was 101 +/- 7% (mean +/- s.e.m.), 99 +/- 8% and 98 +/- 4% of the pre-ischaemic values, respectively. This was significantly different from the vehicle group (78 +/- 5, P < 0.05, 74+/- 6, P < 0.01 and 78 +/- 3, P < 0.05). CONCLUSION: CVR could easily be accomplished in the isolated perfused rat heart. The drug was specifically delivered into the ischaemic myocardium. Felodipine exerted a myocardioprotective effect in isolated rat hearts subjected to 60 min of regional ischaemia followed by 60 min of reperfusion.

Local overflow and enhanced tissue content of endothelin following myocardial ischaemia and reperfusion in the pig: modulation by L-arginine.

OBJECTIVE: The local myocardial overflow and tissue content of endothelin-like immunoreactivity (ET-LI) during ischaemia and reperfusion as well as the coronary vascular effects of endothelin were characterised in anaesthetised pigs. METHODS: Ischaemia was induced by ligation of the left anterior descending coronary artery for 45 min followed by 4 h of reperfusion. ET-LI was analysed in plasma from the anterior interventricular coronary vein and aorta for estimation of local overflow and in myocardial tissue. Endothelin analogues were given in the coronary artery for determination of local vascular effects. RESULTS: During reperfusion, but not during ischaemia, the veno-arterial concentration difference of ET-LI increased, resulting in a significantly increased overflow at between 10 and 120 min of reperfusion. The tissue concentration of ET-LI in the left ventricle was seven times higher in the ischaemic/reperfused area than in the non-ischaemic area: 161(SEM 30.5) v 25.3(3.8) fmol.g-1, P < 0.05. The increase in myocardial ET-LI was attenuated by 70% (P < 0.01) by coronary venous retroinfusion of the nitric oxide substrate L-arginine, whereas the overflow was unaffected. Chromatographic characterisation of the myocardial ET-LI showed that it was similar to endothelin-1. Intracoronary administration of endothelin-1, endothelin-3, and the endothelin ETB receptor agonist [Ala1,3,11,15]ET-1 evoked dose dependent coronary vasoconstriction, and reductions in left ventricular dP/dt and arterial blood pressure. Endothelin-1 was two times more potent than endothelin-3 and 10 times more potent than [Ala1,3,11,15]ET-1. CONCLUSIONS: Myocardial ischaemia/reperfusion evokes enhanced local overflow of ET-LI during the reperfusion period combined with an increased tissue concentration of ET-LI which is is attenuated by L-arginine. Endothelin evokes potent coronary vasoconstriction via activation of both ETA and ETB receptors.

The lipid peroxidation inhibitor indenoindole H290/51 protects myocardium at risk of injury induced by ischemia-reperfusion.

Lipid peroxidation contributes to myocardial reperfusion injury. The indenoindole H290/51, a lipid peroxidation inhibitor with balanced lipophilicity and a considerably higher antioxidative capacity than that of vitamin E, was tested for its myocardioprotective effect against reperfusion injury. Coronary-ligated pigs were subjected to 45 min of myocardial ischemia followed by 240 min of reperfusion. Starting five minutes prior to reperfusion, H290/51 (n = 6) or vehicle (n = 6) was retrogradely infused via a coronary vein for 30 min. The total dose of H290/51 was 1 microM in 300 ml fluid (10 ml/min). In addition to the hemodynamics, left ventricular (LV) wall segment shortening (%SS) was measured by sonomicrometry. The LV area at risk and infarct size were measured by means of Evans blue and triphenyl tetrazolium chloride staining. The hemodynamics did not change significantly during the study, and no differences were found between the two groups. In the H 290/51-treated pigs, %SS of the ischemic area recovered from 1.9% at the end of ischemia to 9.1% after 120 min (p < .05) and to 16.2% at 240 min (p < .01). There was no significant recovery in the vehicle group. The LV area at risk was approximately 20% of LV. Infarct size as a percentage of LV and of the area at risk was significantly smaller in the H290/51 group (9+/-3% and 46+/-11%) than in the control group (18+/-6%; p < .05 and 83+/-5%; p < .01). H290/51 effectively protected the myocardium at risk in the setting of myocardial ischemia followed by reperfusion. This effect was reflected by diminished infarct size and improved functional recovery.

Effects of the insurmountable angiotensin AT1 receptor antagonist candesartan and the surmountable antagonist losartan on ischemia/reperfusion injury in rat hearts.

Two angiotensin AT1 receptor antagonists with different receptor binding characteristics, candesartan (insurmountable antagonism) and losartan (surmountable antagonism), were compared as regards their effects on angiotensin II-induced vasoconstriction and on myocardial ischemia/reperfusion injury. In isolated rat hearts perfused under constant flow, it was found that at equipotent concentrations candesartan (10 nM) and losartan (3 microM) almost completely inhibited the angiotensin II-induced increase in coronary perfusion pressure. However, if a washout period was introduced before the angiotensin II challenge, the effect of losartan quickly vanished, while that of candesartan remained. In hearts subjected to 25 min of global ischemia and 45 min of reperfusion, pre-treatment with candesartan (10 nM) or losartan (3 microM) immediately prior to ischemia improved the recovery of left ventricular developed pressure as compared to the effect of vehicle (69 +/- 3.2 and 64 +/- 2.3 vs. 44 +/- 6.2%, respectively; mean +/- S.E.M, P < 0.05). When ischemia was initiated following 30 min of washout after drug administration, the recovery of left ventricular developed pressure was higher in the candesartan group (73 +/- 3.2%, P < 0.05), but not in the losartan group (63 +/- 2.8%), than in the vehicle group (58 +/- 4.8%). The cumulative creatine kinase release during the first 30 min of reperfusion in the washout experiments was lower in the candesartan group (28.5 +/- 2.30 U, P < 0.05), but not in the losartan (40.8 +/- 6.73 U) group, than in the vehicle group (48.1 +/- 4.35 U). No significant difference between groups in left ventricular end-diastolic pressure and coronary perfusion pressure was found. The present results demonstrate that angiotensin AT1 receptor antagonists at equipotent concentrations could differ in their cardioprotective effects in hearts subjected to ischemia/reperfusion. It is suggested that the insurmountable AT1 receptor characteristics of candesartan could provide more persistent cardioprotection than the surmountable receptor characteristics of losartan.

Beneficial effects of the endothelin receptor antagonist bosentan on myocardial and endothelial injury following ischaemia/reperfusion in the rat.

The effects of bosentan, a nonpeptide endothelin receptor antagonist, on endothelin-induced changes in coronary flow and myocardial ischaemic and reperfusion injury were investigated in the Langendorff perfused rat isolated heart. Endothelin-1 (0.012-0.4 nmol) evoked dose-dependent reduction in coronary flow, which was attenuated by bosentan (1.0-10 microM) in a concentration-related fashion. The inhibitory effect of bosentan lasted more than 30 min. The endothelin ETB receptor agonist Suc-[Glu9,Ala11,15]endothelin-1-(8-21) (IRL 1620) increased coronary flow in the absence but not in the presence of bosentan. In hearts subjected to 30 min of global ischaemia followed by 30 min of reperfusion, the recoveries of the left ventricular developed pressure, dP/dtmax, and coronary flow were significantly larger in a group given bosentan 10 microM at the start of ischaemia (92 +/- 7%, 98 +/- 8% and 83 +/- 5%, respectively) than in a vehicle-treated group (70 +/- 4%, 70 +/- 6% and 42 +/- 2%, respectively) at the end of the reperfusion period. During the reperfusion period, left ventricular end diastolic pressure was significantly lower in the bosentan group than in the vehicle group. The area of no-reflow in the bosentan group was 7 +/- 3% of left ventricle compared to 21 +/- 2% in the vehicle group (P < 0.01). Acetylcholine-induced endothelium-dependent vasodilatation was significantly reduced after ischaemia and reperfusion in the vehicle group but not in the bosentan group. It is concluded that bosentan attenuates the coronary vasoconstrictor effect elicited by endothelin and reduces ischaemia/reperfusion-induced myocardial and endothelial injury in the rat isolated heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of endothelin-1-induced vascular effects in the rat heart by using endothelin receptor antagonists.

The coronary vasoconstrictor effect of endothelin-1 was characterized in the isolated rat heart by using the endothelin ETA receptor antagonist D-Asp-L-Pro-D-Val-L-Leu-D-Trp (BQ-123) and the endothelin ETB receptor antagonist [Cys11-Cys15]endothelin-1-(11-21) (IRL 1038). In addition, the involvement of nitric oxide and cyclooxygenase products was investigated. Endothelin-1 (0.012-0.4 nmol) dose dependently reduced coronary flow, which reached a maximum reduction of 83% at 0.4 nmol. BQ-123 (1 microM) attenuated the responses to all doses of endothelin-1, whereas a lower concentration of BQ-123 (0.1 microM) only reduced the vasoconstriction due to the lower doses of endothelin-1 (0.012-0.12 nmol). In contrast, IRL 1038, which markedly antagonized the vasodilator response to the endothelin ETB receptor agonist Suc-[Glu9,Ala11,15]endothelin-1-(8-21) (IRL 1620), significantly enhanced the endothelin-1-evoked coronary vasoconstriction. Endothelin-1 (0.04 nmol) reduced coronary flow by 61% in the presence of IRL 1038 as compared to 30% in the absence of the endothelin ETB receptor antagonist. The endothelin-1-evoked reduction in coronary flow was also significantly enhanced by the nitric oxide synthesis inhibitor NG-nitro-L-arginine but was unaffected by the cyclooxygenase inhibitor diclofenac. IRL 1038 did not affect the response to endothelin-1 after blockade of nitric oxide synthesis. These results demonstrate that the coronary vasoconstriction induced by endothelin-1 in the isolated rat heart is a net effect of the stimulation of both endothelin ETA and endothelin ETB receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac inotropic vs. chronotropic selectivity of isradipine, nifedipine and clevidipine, a new ultrashort-acting dihydropyridine.

Cardiac effects of clevidipine, a new ultrashort-acting dihydropyridine Ca2+ channel antagonist were investigated in Langendorff-perfused rat hearts and compared to those of nifedipine and isradipine. The aim was to determine and compare the negative inotropic vs. chronotropic potency of these drugs. The hearts were perfused with oxygenated Krebs-Henseleit buffer at a perfusion pressure of 90 cm H2O. After stabilization, one concentration of each drug was administered for 45 min followed by a higher concentration for an additional 45 min. The concentrations of each drug in this study were 10(-9), 3 x 10(-9), 10(-8), 10(-7), 10(-6.5) and 10(-6) M for clevidipine and nifedipine, and 10(-10), 3 x 10(-10), 10(-9), 10(-8), 10(-7.5) and 10(-7) M for isradipine. Each concentration of each drug was tested in six hearts. Coronary flow, left ventricular dP/dt max, left ventricular systolic pressure and heart rate were recorded when the hearts were beating spontaneously and during pacing at a constant rate for 1 min. Spontaneous heart rate and atrio-ventricular conduction were not affected by clevidipine at any of the concentrations studied, while nifedipine and isradipine caused a concentration-dependent decrease. These two drugs caused atrio-ventricular block at high concentrations. All three compounds reduced cardiac contractility in a concentration-dependent manner. When isradipine was administered, at a given concentration, heart rate and contractility decreased proportionately. When clevidipine or nifedipine was given, at a given concentration, the proportionate reduction in left ventricular dP/dt max was greater than that in heart rate, resulting in a high inotropic vs. chronotropic selectivity. It is concluded that in contrast to nifedipine and isradipine, clevidipine does not impair atrio-ventricular conduction. Like nifedipine, clevidipine is selective for inotropic vs. chronotropic cardiac effects.

Sensitization of human colon cancer cells to TRAIL-mediated apoptosis.

TNF-related apoptosis-inducing ligand (TRAIL), a novel member of the tumor necrosis factor (TNF) family, is thought to induce apoptosis preferentially in cancer cells; however, increasing evidence suggests that a number of cancers are resistant to TRAIL treatment. FLICE-like inhibitory protein (FLIP), which structurally resembles caspase-8, can act as an inhibitor of apoptosis when expressed at high levels in certain cancer cells. The purpose of our present study was to determine whether human colon cancer cells are sensitive to TRAIL treatment and, if not, to identify potential mechanisms of resistance. Colon cancer cells of different metastatic potential (KM12C, KML4A, and KM20) were found to be resistant to the effects of TRAIL when used as a single agent. FLIP expression levels were increased in all three KM cell lines. Treatment with either actinomycin D (Act D;10 :g/ml) or cycloheximide (CHX; 10 :g/ml) decreased FLIP expression levels in all three cell lines. The decrease in cellular levels of FLIP was associated with sensitization to TRAIL-mediated apoptosis, as demonstrated by enhanced cell death and caspase-3 activity compared with either Act D or CHX alone. Our findings suggest that reduction of FLIP levels by Act D or CHX renders TRAIL-resistant human colon cancer cells sensitive to TRAIL-mediated apoptosis. The combination of TRAIL along with agents such as Act D or CHX, which target proteins that prevent cell death, may provide a more effective and less toxic regimen for treatment of resistant colon cancers.

Coronary thrombosis/thrombolysis in pigs: effects of heparin, ASA, and the thrombin inhibitor inogatran.

UNLABELLED: The aim of the present study was to develop a coronary thrombolysis model using the copper coil technique in closed-chest pigs. The first goal (protocol I) was to obtain a reproducible size of myocardial infarction by controlling the coronary occlusion period, a prerequisite for evaluation of myocardioprotective interventions. The second goal (protocol II) was to study if thrombin and platelet aggregation inhibitors influence the rate of thrombolysis, the degree of reocclusion, and the time of coronary patency when added to a thrombolytic regimen (recombinant tissue-type plasminogen activator, rt-PA). Coronary thrombosis was produced by insertion of a thrombogenic copper coil into the LAD of 40 anesthetized pigs. The animals were divided into six groups as follows: Protocol I, group 1: Open-chest, lysis initiated with intracoronary rt-PA (50 mg) concomitant with intravenous heparin and acetylsalicylic acid (ASA) (n=6). Group 2: Closed-chest, lysis initiated with intracoronary rt-PA concomitant with intravenous heparin and ASA (n=10). Protocol II, group 3: Closed-chest, lysis initiated with intravenous rt-PA (n=6). Group 4: Closed-chest, lysis initiated with intravenous rt-PA concomitant with heparin (n=6). Group 5: Closed-chest, lysis initiated with intravenous rt-PA concomitant with inogatran, a low molecular weight thrombin inhibitor (n=6). Group 6: Closed-chest, lysis initiated with intravenous rt-PA immediately after intravenous administration of ASA (n=6). Protocol 1; Reperfusion was achieved in all closed- and open-chest pigs. The time to thrombolysis was 5+/-1.6 and 6+/-3.0 min (mean+/-SD) for closed- and open-chest pigs, respectively. Reocclusions were rare (one in group 1). The size of the ischemic myocardial area was 21+/-11% of the left ventricular area in group 1 and 22+/-6% in group 2. The corresponding values for infarct size as a proportion of the ischemic area were 58+/-10% and 68+/-14%, respectively. The closed-chest model was subsequently used to study the effect of the thrombin and platelet aggregation inhibitors (inogatran, heparin, and ASA) as conjunctive agents to rt-PA-induced thrombolysis (groups 3-6). To mimic its clinical use, rt-PA was administered intravenously. Time to lysis after rt-PA only (group 3) was 33+/-24 min. Concomitant treatment with heparin (group 4), inogatran (group 5), and ASA (group 6) did not significantly influence time to lysis. All adjunctive compounds did, however, prolong the time to reocclusion, which occurred in 100%, 75%, 67%, and 20% of the animals in groups 3, 4, 5, and 6. Thus, concomitant treatment with heparin and inogatran did not shorten time to lysis or reduce the reocclusion rate, and ASA turned out to be the only effective adjunct to rt-PA, significantly reducing both time to and frequency of reocclusion (p < 0.05). CONCLUSION: The described closed-chest pig model was feasible as regards the induction and lysis of a thrombus in the left coronary artery, giving reproducible areas of myocardial ischemia and infarction. This model was useful for the evaluation of pharmacological interventions in the thrombolysis process.

Effect of Astragulas membranaceus on natural killer cell activity and induction of alpha- and gamma-interferon in patients with Coxsackie B viral myocarditis.

The patients suffering from Coxsackie B viral myocarditis with depressed natural killer (NK) activity were treated with Astragulas membranaceus (AM) intramuscularly for 3-4 months. After the treatment, the NK activity was increased significantly from 11.5 +/- 11.9% before therapy to 44.9 +/- 15.0%. Another 6 patients of Coxsackie B viral myocarditis with depressed NK activity were treated with conventional therapy. The NK activity remained unchanged in 12.9 +/- 6%. The general condition and symptoms improved in all patients with AM therapy, while the titers of neutralizing antibody remained at the same level. Two days after AM treatment, the mean titers of alpha- and gamma-interferon (IFN) markedly increased in comparison with those before therapy and 3 weeks after AM therapy in 16 patients with Coxsackie B viral myocarditis, with left ventricular ejection fraction (LVEF) less than 65% and/or weak ventricular wall motion assayed by radionuclide angiocardiography. Whereas, in 12 patients treated with conventional therapy, there was no statistical difference among the results before and 2 days and 3 weeks after treatment. The results indicate that AM could partly regulate the lost of control of cellular immunity in patients with viral myocarditis.

[Natural killer cell activity of the peripheral blood in patients with hepatocellular carcinoma].

Using 125IudR labeled K562 cells as target cells, peripheral blood of 56 patients with hepatocellular carcinoma (HCC) was studied for natural killer cell (NK cell) activity. The results show that the NK cell activity is in normal range of 53.97 +/- 4.42% and 50.85 +/- 3.55% in stages I and II of HCC but in stage III, the NK cell activity is markedly depressed, only 31.63 +/- 5.55%. The NK cell activity is much lower in HCC patients with metastasis than without metastasis (33.67 +/- 5.37% versus 50.22 +/- 2.79%). So is it in patients with high concentration than with low concentration of AFP except patients with advanced lesion and low concentration of AFP. After effective treatment, the NK cell activity increased in 10 of 11 patients treated with radical and palliative resection and in 6 of 9 after immunotherapy with BCG, mixed bacterial vaccine or interferon.

[The correlation between multidrug resistance and glutathione (GSH) in EAC, EAC/ADR and EAC/ADR(R) cell lines].

Determination of GSH was performed by a modified fluorometric method. The experiments showed that the GSH content in resistant cell line (EAC/ADR) was 4 fold higher than that in sensitive cell line (EAC), being 1.25 +/- 0.35 microgram/10(6) cells in EAC/ADR and 0.31 +/- 0.12 microgram/10(6) cells in EAC. When the drug treatment was discontinued for 36 weeks, the sensitivity was partially recovered and the GSH level in EAC/ADR(R) cell parallelly decreased. In addition, vincristine, mitomycin C, actinomycin D and VP-16 showed no effect on the GSH content in the EAC/ADR cell.