兰尼定对大鼠平滑肌细胞的肾上腺素能作用(英文)

电场刺激后释放的内源性去甲肾上腺素可引起大鼠输精管的双相收缩。初始的短暂收缩可被30μmol/L兰尼定和2μmol/L硝苯啶减弱,而后继的收缩部分可被2μmol/L硝苯啶消除,但被30μmol/L兰尼定增强。 外加的去甲肾上腺素也可产生输精管的双相收缩,这两相都能被2 μmol/L硝苯啶抑制,兰尼定30μmol/L可使两个相的收缩都减弱50％。我们推测兰尼定的结合位点在输精管的内质网。兰尼定对α-肾上腺素能刺激的不同相的作用不一致,表明对α-肾上腺素能的刺激一收缩偶合有两种方式。     

Association of interleukin-18 promoter polymorphism and atherosclerotic diseases in Chinese patients with diabetic nephropathy

Aim: Interleukin‐18 (IL‐18) is a pro‐inflammatory cytokine and possibly plays an important role in the pathogenesis of cardiovascular disease. The relationship between two IL‐18 gene polymorphisms, namely C‐607A and G‐137C, and cardiovascular disease in patients with diabetic nephropathy was examined. Methods: Two hundred and twenty patients (91 male) with diabetic nephropathy were studied. The IL‐18 promoter genotypes were determined. All patients were then prospectively followed for the cardiovascular events. Cardiovascular mortality and all‐cause mortality were also compared. Results: Mean age was 64.3 ± 10.6 years; average follow up was 73.9 ± 33.6 months. The frequencies of CC, CA and AA genotypes of the C‐607A polymorphism were 25.5%, 48.2% and 26.8%, respectively; GG, GC and CC genotypes of the G‐137C polymorphism were 71.8%, 25.0% and 3.2%, respectively. Neither of the polymorphisms were associated with the development of primary cardiovascular end‐point. Cardiovascular survival was 84.8% and 70.6% at 60 months for GG and GC/CC genotypes of the G‐137C polymorphism, respectively (P = 0.027); the corresponding actuarial survival was 69.0% and 54.8%, respectively (P = 0.053). However, the G‐137C genotype was not an independent predictor of cardiovascular or actuarial survival after adjusting for confounders by multivariate analysis with the Cox model. The C‐607A polymorphism had no significant effect on cardiovascular or actuarial survival. Conclusion: The G‐137C polymorphism of the IL‐18 promoter is associated with the cardiovascular mortality, and a trend of association with all‐cause mortality, in patients with diabetic nephropathy. The association, however, becomes insignificant after adjusting for confounding factors. Further studies are needed to test other genetic determinants of the association between systemic inflammation and cardiovascular disease in renal failure patients.     

Noise Mode Response at Peak Exercise in a DDD Pacemaker

The noise sampling period has been recognized as a cause of apparent sensing malfunction in demand pacemakers. Physiologic signals as well as external electromagnetic interference can cause certain demand pacemakers to remain refractory and escape asynchronously at a specified rate. In this case, noise mode reversion pacing at the programmed lower rate limit of a Cordis 415A DDD pacemaker was observed during exercise when P-waves fell within the noise sampling period.     

Contradictory Shear Stress Distribution Prevents Restenosis after Provisional Stenting for Bifurcation Lesions

Background: Endothelial shear stress is one of the local hemodynamic factors suspected in the development of coronary atherosclerosis in bifurcation lesions. In patients with provisional stenting, the endothelial shear stress (SS) distribution is unknown. Objective: The aim of this study was to investigate the magnitude and distribution of the SS of coronary bifurcation lesions stenting by the provisional approach. Methods: Ten consecutive patients were included in this study. Quantitative coronary analysis, flow study, and three‐dimensional computational analysis with the aid of the commercial software CD STAR‐CCM+ were done before and after the provisional stenting procedure and also 8 months later. Results: Clinical and angiographic follow‐up were available in all patients. No patient had a side branch (SB) stent. At the 8‐month follow‐up, no major adverse cardiac event (MACE) occurred. There was also no clinical and angiographic restenosis. Before PCI, the distal main vessel (MV)‐lateral, and the SB‐lateral subsegments had relative nonsignificant lower SS value (4.08 ± 2.78 Pa and 4.35 ± 5.04 Pa, respectively) when compared to other segments. After 8‐month follow‐up, sustained decreased SS value was shown in the distal MV‐lateral segment (4.08 ± 2.78–1.68 ± 1.65 Pa), when compared with significantly increased SS value in the SB‐lateral subsegment 4.35 ± 5.04–16.50 ± 40.45 Pa). The explanation is that after stenting in the MV, the flow was redistributed immediately after percutaneous coronary intervention (PCI) and reversed back to its original 8 months later. However, the growth of the fibrous tissue causing in‐stent restenosis (ISR) is prohibited by sirolimus on the stent struts. In contrast, in a branch opened up by plain old balloon angioplasty (POBA), the flow did not change much, the flow could even be worse because it is shifted to the MV after the cross‐sectional area of the MV improved by stenting. However, thanks to POBA, there is increased fibrous tissue formation, enough to increase the SS and prevent further accumulation of cell and cholesterol needed for more restenosis. Conclusion: In the provisional approach, low endothelial SS correlated with no restenosis for patients who underwent stenting of the MV, while a contradictory combination of high SS and no restenosis was seen in the SB after only POBA. The mechanism of prevention of restenosis in the SB is by increasing the SS while in the MV, the mechanism of prevention of ISR is secondary to sirolimus on the stents struts. (J Interven Cardiol 2010;23:319–329)     

Cardiac Resynchronization Therapy: Double Cannulation Approach to Coronary Venous Lead Placement via a Prominent Thebesian Valve

We report identification of a prominent Thebesian valve by cardiovascular computed tomography (CT) angiography impeding cannulation of the coronary sinus, with subsequent successful coronary venous lead placement with cannulation of the coronary sinus ostium via a transvenous femoral vein approach and subsequent cannulation of the ostium with the coronary venous lead with a left subclavian approach. A 57‐year‐old man with nonischemic dilated cardiomyopathy, New York Heart Association Class III heart failure, left bundle branch block, and an ejection fraction of 15%, underwent an attempted cardiac resynchronization therapy implantable cardiac defibrillator (ICD). As the coronary sinus ostium could not be cannulated, a dual chamber ICD was placed. The patient subsequently underwent cardiovascular CT angiography, which identified a prominent Thebesian valve at the coronary sinus ostium as the anatomic obstacle to cannulation. Reattempted transvenous cardiac resynchronization therapy was accomplished successfully with a double cannulation approach: cannulation of the coronary sinus ostium with a catheter via a transvenous femoral vein approach and subsequent cannulation with the coronary venous lead via a left subclavian approach. When a prominent Thebesian valve is identified as an obstacle to transvenous left ventricular lead placement, cannulation of the coronary sinus by an alternate venous approach may allow for a coronary venous route rather than necessitate an epicardial approach.     

Protected amino acid tetrafluorophenyl esters for peptide synthesis

New 2,3,5,6-tetrafluorophenyl active esters of protected amino acids useful for peptide synthesis were prepared in high yield. For certain amino acid derivatives such as Boc-Pro-OH, Boc-Ile-OH, and Boc-Val-OH, their tetrafluorophenyl esters have significantly higher melting points than the corresponding pentafluorophenyl esters. Kinetic studies were carried out to compare the racemization rate constants (with triethylamine) and coupling rate constants (with valine methyl ester) of the tetrafluorophenyl and pentafluorophenyl esters of protected histidine and tyrosine. Results of the second-order kinetics showed similarly large k_coupling/k_racemization ratios for both tetra- and pentafluorophenyl esters. In particular, the use of 2,3,5,6-tetrafluorophenyl or pentafluorophenyl ester prevents extensive racemization of the N-tert.-butyloxycarbonyl-N^im-benzyl-histidine.