Biochemical performance of tapercut cardiovascular needles

Standardized reproducible tests have been developed to determine the biomechanical performance of cardiovascular needles. The parameters used to assess performance were: 1) sharpness, 2) resistance to bending, and 3) ductility. Four comparable groups of tapercut and taper point cardiovascular needles were selected from different manufacturers for these biochemical studies. The results of this testing demonstrated that needle geometry, needle composition, and the manufacturer were important determinants of needle performance. When comparable needles were evaluated, the biochemical performance of cardiovascular needles manufactured by Ethicon, Inc. (Somerville, NJ) were superior to needles produced by other manufacturers. The superior performance characteristics of the cardiovascular needles produced by Ethicon, Inc. were related to their unique stainless steel alloy, American Society for Testing Materials 45500, which has greater yield and tensile strengths than the alloy used by the other manufacturers. This stainless steel alloy was ideal for the production of tapercut needles, which combined some of the features of a reverse cutting edge needle and taper point needle. Its very short cutting edges allowed it to penetrate the membrane at considerably lower penetration forces than were encountered with comparable taper point needles. In addition, the investigation indicated that the trocar point cardiovascular needles produced a large triangular defect whose diameter was much larger than that of the needle body. For this reason, the use of the trochar point needle is not recommended in cardiovascular surgery.     

Reducing postischemic paraplegia using conjugated superoxide dismutase

Paraplegia after thoracic aortic aneurysm repair has an incidence of 2.2% to 24%. Oxygen-derived free radicals after reperfusion of an ischemic spinal cord may be partly responsible for neuronal destruction. We studied the effects of polyethylene glycol-conjugated superoxide dismutase (PEG-SOD), a free radical scavenger, as a way of increasing spinal cord tolerance to ischemia. Thirty rabbits underwent 40 minutes of aortic occlusion (a known model of paraplegia). Ten of these animals received 25,000 U/kg of PEG-SOD 24 hours before aortic occlusion and two additional doses of 10,000 U/kg, one before and one subsequent to spinal ischemia. Ten animals received superoxide dismutase in the same dosages as those receiving PEG-SOD. Ten control animals received placebo. All animals were studied for 96 hours, at which time a final neurological examination was performed and the results were recorded. Of the 10 animals treated with PEG-SOD, 2 were completely paralyzed whereas 8 had less (7) or no (1) neurological impairment. Eight of the 10 control animals and 9 of the 10 animals receiving superoxide dismutase were completely paralyzed. None of the control animals or animals receiving superoxide dismutase had a normal neurological examination (p less than or equal to 0.05). Treatment with PEG-SOD before and during occlusion increased the rabbit spinal cord tolerance to a 40-minute ischemic insult. Scavenging free radicals may lessen experimental spinal cord injury.     

Systematic preclinical study on the therapeutic properties of recombinant human interleukin 2 for the treatment of metastatic disease

The availability of recombinant human interleukin 2 (rH IL 2) has resulted in its clinical utilization both as a single agent and in combination with lymphokine-activated killer cells. In this report, we discuss the effects of rH IL 2, administered by various routes, on effector cell function, pharmacokinetics and bioavailability, and therapeutic activity. Studies of the pharmacokinetics of in vitro natural killer (NK) cell augmentation by rH IL 2 revealed that a short exposure to high levels of rH IL 2 can augment NK cell activity; however, a prolonged exposure (greater than 12 h) was required to augment NK cell activity at lower doses of rH IL 2. These observations suggested that chronic administration of rH IL 2 might improve immunomodulatory and therapeutic activity. This hypothesis was supported by the results of studies in which we treated experimental and spontaneous metastasis, which revealed that the daily i.p. administration of rH IL 2 resulted in significantly greater therapeutic activity than administration three times/week. The therapeutic protocol for daily i.p. administration had a biphasic dosage optimum, such that low dose therapeutic activity was observed at approximately 100-1000 units/animal in the treatment of experimental metastases or 10 to 100 units/animal in the treatment of spontaneous metastases. There was a second dosage optimum at greater than or equal to 100,000 units/animal rH IL 2 delivered i.p. on a daily basis. Intermediate doses had no significant therapeutic activity. Additional studies revealed that low dose therapeutic activity was not observed in nude mice. In contrast, therapeutic activity was observed in nude mice at high doses of rH IL 2 suggesting that low dose activity was associated with a T-cell-mediated effect, whereas high dose activity may have been mediated by NK or lymphokine-activated killer-like cells. This observation was in agreement with the dose response for T-cell adjuvant activity supporting the hypothesis that low dose therapeutic activity was T-cell associated, because adjuvant activity was observed when rH IL 2 was given daily at approximately 100 units/animal for 3 days, and higher doses had no activity or had a suppressive effect. Because we were concerned about the pharmacological aspects of rH IL 2 treatment, we also examined its therapeutic properties after continuous administration i.p. by osmotic pumps. Under these conditions, therapeutic activity was observed after administration of 600 units/h, whereas lower or higher doses did not have significant therapeutic activity.     

Familial amyloidotic patients' experience of the disease and of liver transplantation

Liver transplantation is a new treatment for familial amyloidotic polyneuropathy (FAP). No qualitative study examining these patients' experiences of the disease and the treatment has been published. The purpose of this study was to explore and describe the experience of the disease and the liver transplantation from the FAP patient's perspective. In-depth interviews with 11 liver transplant FAP patients were performed. The process of the FAP disease and a liver transplantation was found to involve the following categories: going downhill, defence and denial, a chance of surviving, the decision — no choice, waiting powerless and uncertain, the first few steps after surgery, freed from the death sentence, still disabled, mastering up strength to recover, and the need for support and help.     

肝移植患者术后白蛋白的应用

目的:低白蛋白血症是肝移植患者的常见并发症,也是患者预后的重要影响因素。肝移植术后选择合理的白蛋白应用方案将有益于提高肝移植患者术后近远期疗效。方法:选择2000-10/2005-06于北京大学第三医院行肝移植并且随访时间大于6个月的患者80例,对治疗方案均知情同意。医院自2003年8月开始改变了肝移植术后白蛋白的输入方案:①方案改变之前患者即白蛋白输入方案未改变组(n=50),术后早期常规输入白蛋白剂量大于60g/d。②方案改变之后患者即白蛋白输入方案改变组(n=30),适当减少术后早期白蛋白输入的常规剂量至0￣20g/d。统计分析两组患者的一般情况、术后白蛋白使用情况、预后情况及住院费用。另外,对于两组中术后存在低白蛋白相关严重并发症的患者进行进一步的比较分析。结果:80例患者全部进入结果分析。①两组患者术前及术中一般情况差异无显著性意义(P>0.05)。②白蛋白输入方案改变组术后早期白蛋白的使用量及其费用/总住院费用比例显著低于白蛋白输入方案未改变组(P<0.01)。但两组患者术后第3天肝功能情况、白蛋白水平、早期并发症发生率、早期死亡率、半年生存率及呼吸机时间等情况差异均无显著性意义(P>0.05)。③两组中术后出现低白蛋白相关严重并发症患者术后第3天肝功能情况、白蛋白水平、早期死亡率、半年生存率及呼吸机应用时间等情况差异均无显著性意义(P>0.05)。结论:肝移植术后过多输入白蛋白不能改善患者预后;适当减少术后白蛋白的常规输入剂量,同时根据血白蛋白水平及并发症情况随时调整白蛋白的输入量能够减少白蛋白的用量,对患者预后因素亦无明显影响。