RENAL TUBULAR PEPTIDE CATABOLISM IN CHRONIC VASCULAR REJECTION

Chronic vascular rejection (CR) is the commonest cause of renal transplant loss, with few clues to etiology, but proteinuria is a common feature. In diseased native kidneys, proteinuria and progression to failure are linked. We proposed a pathogenic role for this excess protein at a tubular level in kidney diseases of dissimilar origin. We demonstrated in both nephrotic patients with normal function and in those with failing kidneys increased renal tubular catabolisman and turnover rates of a peptide marker, Aprotinin (Apr), linked to increased ammonia excretion and tubular injury. These potentially injurious processes were suppressed by reducing proteinuria with Lisinopril. Do similar mechanisms of renal injury and such a linkage also occur in proteinuric transplanted patients with CR, and if so, is Lisinopril then of beneficial value? We now examine these aspects in 11 patients with moderate/severe renal impairment (⁵¹CrEDTA clearance 26.2 ± 3.3 mL/min/1.73m²), proteinuria (6.1 ± 1.5 g/24 h) and biopsy proven CR. Lisinopril (10–40 mg) was given daily for 2 months in 7 patients. Four others were given oral sodium bicarbonate (Na HCO₃) for 2 months before adding Lisinopril. Renal tubular catabolism of intravenous ^99mTc-Apr (Apr^* 0.5 mg, 80 MBq), was measured before and after Lisinopril by γ-ray renal imaging and urinary radioactivity of the free radiolabel over 26 h. Fractional degradation was calculated from these data. Total 24 h urinary N-acetyl-β-glucoaminidase (NAG) and ammonia excretion in fresh timed urine collections were also measured every two weeks from two months before treatment. After Lisinopril proteinuria fell significantly (from 7.8 ± 2.2 to 3.4 ± 1.9 g/24 h, p < 0.05). This was associated with a reduction in metabolism of Apr^* over 26 h (from 0.5 ± 0.05 to 0.3 ± 0.005% dose/h, p < 0.02), and in fractional degradation (from 0.04 ± 0.009 to 0.02 ± 0.005/h, p <0.01). Urinary ammonia fell, but surprisingly not significantly and this was explained by the increased clinical acidosis after Lisinopril, (plasma bicarbonate fell from 19.1 ± 0.7 to 17.4 ± 0.8 mmol/L, p <0.01), an original observation. Total urinary NAG did fall significantly from a median of 2108 (range 1044–3816) to 1008 (76–2147) μmol/L, p < 0.05. There was no significant change in blood pressure or in measurements of glomerular hemodynamics. In the 4 patients who were given Na HCO₃ before adding Lisinopril, both acidosis (and hyperkalemia) were reversed and neither recurred after adding Lisinopril. These observations in proteinuric transplanted patients after Lisinopril treatment have not been previously described.     

A multicenter trial of the use of the proteolytic enzyme inhibitor aprotinin in colorectal surgery

Animal studies have demonstrated the value of the proteolytic enzyme inhibitor, aprotinin, in reducing collagen breakdown and improving the healing of experimental colonic anastomoses. A double-blind, multicenter, prospective trial has evaluated the use of aprotinin in the prevention of anastomic leakage in patients. Two hundred sixteen patients undergoing colonic resection and anastomosis were studied. Patients were randomized to receive either aprotinin or placebo intravenously, peroperatively, and for the first three postoperative days. Anastomotic integrity was assessed clinically and by Hypaque^® enema on the tenth postoperative day. Although the use of aprotinin was not associated with a significant overall decrease in anastomotic leakage rates, in 95 patients undergoing anterior resection, leakage rates in those receiving aprotinin (clinical 10.8 percent; radiologic 32.4 percent) were lower than in those receiving placebo (17.2 percent and 43.1 percent, respectively). An apparent adverse association was noted, however, in patients undergoing left hemicolectomy or sigmoid colectomy who received aprotinin.     

心脏手术中抗纤溶药物的临床应用进展

心脏手术中过度失血仍是心脏手术面临的的主要挑战之一,抗纤溶药物的临床应用为解决这一难题带来希望。由于抑肽酶可增加肾损伤、增加术后死亡率,赖氨酸类似物成为心脏手术中主要抗纤溶用药,其中氨甲环酸的应用最为广泛。无论是在体外循环心脏手术还是在非体外循环冠状动脉搭桥手术中,氨甲环酸的有效性经多项研究证实。而如今,不同出血风险的心脏手术中氨甲环酸的应用剂量仍未明确。在氨甲环酸广泛应用的同时,其安全性也引起大家质疑,其与术后谵妄的关系也引起大家高度注意,而有专家呼吁抑肽酶有必要再次进入临床。将来,抑肽酶是否会成为高危出血心脏手术中的主要抗纤溶用药,氨甲环酸的合理应用剂量最终怎样界定,对这些问题我们拭目以待。     

Aprotinin reduces oxidative stress induced by pneumoperitoneum in rats

Background

Ischemia–reperfusion injury induced by pneumoperitoneum is a well-studied entity, which increases oxidative stress during laparoscopic operations. The reported anti-inflammatory action of aprotinin was measured in a pneumoperitoneum model in rats for the first time in this study.

Materials and methods

A total of 60 male Albino Wistar rats were used in our protocol. Prolonged pneumoperitoneum (4 h) was applied, causing splanchnic ischemia and a period of reperfusion with a duration of 60 or 180 min followed. Several cytokines and markers of oxidative stress were measured in liver, small intestine, and lungs to compare the aprotinin group with the control group. Tissue inflammation was also evaluated and compared between groups using a five-scaled histopathologic score.

Results

In aprotinin group values of biochemical markers (tumor necrosis factor α, interleukin 6, endothelin 1, C reactive protein, pro-oxidant–antioxidant balance, and carbonyl proteins) were lower in all tissues studied. Statistical significance was greater in liver and lungs (P < 0.05). Histopathologic examination revealed significant difference between control and aprotinin groups in all tissues examined. Aprotinin groups showed mild to moderate lesions, while in control groups severe to very severe inflammation was present. Aprotinin subgroup with prolonged reperfusion period (180 min) showed milder lesions in all tissues than the rest of the groups.

Conclusions

Aprotinin reduced inflammatory response and oxidative stress induced by pneumoperitoneum in liver, small intestine, and lungs.     

乌司他丁对婴幼儿体外循环心脏手术血小板功能的保护作用

目的 探讨乌司他丁在婴幼儿心肺转流(CPB)围术期对血小板功能的保护及止血作用.方法 45例3岁以下房间隔缺损(ASD)或室间隔缺损(VSD)患儿随机分为三组,每组15例,分别在预充液中一次性加入抑肽酶(A组)、乌司他丁(U组)或未用药(C)组;选取4个时间点采静脉血测定血小板膜糖蛋白受体GP Ⅰ b和GPⅡb/Ⅲ a及血小板计数;记录术后纵隔引流量及输血量.结果 GP Ⅰ b、GP Ⅱ b/Ⅲa组内及A、U组与C组之间比较有统计学意义(P<0.01),A组与U组间无统计学意义.血小板计数组间比较无统计学意义.A、U组术后纵隔引流量明显少于C组(P<0.05),U组与A组间无统计学意义.三组术后输血量无统计学意义.结论 乌司他丁在婴幼儿先心病围术期通过保护GP而对血小板功能有部分保护作用,从而减轻术后非外科性出血,减少输血量,可取代抑肽酶作为婴幼儿先心病手术的血液保护用药.     

抑肽酶对大鼠肝脏缺血再灌注损伤的保护作用

目的:探讨抑肽酶对大鼠肝脏缺血再灌注损伤的保护作用。方法:将48只Wastar大鼠随机分成假手术组、缺血再灌入组和预防性抑肽酶组,检测不同时间血浆或肝组织中谷丙转氨酶(ALT)、丙二醛(MDA)和超氧化物歧化酶(SOD)含量变化及肝组织病理变化。结果:用抑肽酶处理组大鼠血清ALT及肝组织中MDA含量明显低于缺血再灌注(P<0.01)而肝组织中SOD含量则高于缺血再灌注组(P<0.01)肝细胞形态学异常改变较缺血再灌注组也明显减轻。结论:抑肽酶对大鼠肝脏缺血再灌注损伤起保护作用。     

抑肽酶对手术应激反应影响的实验研究

目的:探讨抑肽酶对手术后猪应激激素的影响。方法:26头肝移植供体猪随机分为抑肽酶组与对照组,每组13头。抑肽酶组在气管插管前静注200万KIU抑肽酶,50万KIU/h术中维持。在气管插管前、开腹前、开腹后30min、全身肝素化前对静脉血中的促肾上腺皮质激素(ACTH)、皮质醇(COR)、胰高血糖素的浓度进行测定。结果:气管插管前各项指标无差异,随着手术的进展ACTH、COR、胰高血糖素浓度抑肽酶组均明显低于对照组(P<0.05)。结论:抑肽酶的应用能减轻机体创伤后应激激素的释放,减轻应激反应,有利于内环境的稳定。     

An improved (99m)Tc-aprotinin kit formulation: quality control analysis of radiotracer stability and cold kit shelf life

^99mTc-aprotinin scintigraphy has been demonstrated to be a useful noninvasive imaging technique for amyloid deposits located in extraabdominal regions of patients. The aim of this study was to develop an improved aprotinin cold kit formulation, to validate the kit for long-term stability, as well as to assess the radiotracer stability by novel quality control methods. The aprotinin cold kit formulation of Trasylol, pyrophosphate (PYP)-chelated stannous reductant and an alkaline buffer, was dispensed into nitrogen-filled vials and aliquots frozen at −20°C. After 0, 1, 2, 3 and 6 months of storage, three samples were reconstituted with 750–850 MBq of ^99mTc-pertechnetate, followed by quality control analyses by paper chromatography methods at 25, 85 and 265 min postreconstitution (pr). Cation-exchange cartridge quality control methods were also investigated. The cold kits proved to be stable to long-term storage for up to 6 months, and the radiotracer was stable for at least 4 h pr. ^99mTc-aprotinin was formed at greater than 95% efficiency at all time points tested with ^99mTcO₂ present as the major impurity (1–4%) and ^99mTc-pertechnetate and ^99mTc-PYP present in trace amounts. An alternative, rapid, safe and reliable method was found in Oasis MCX–BSA-treated cartridges using saline as the eluting solution to assay for ^99mTc-aprotinin.     

In vivo biological performance of composites combining micro-macroporous biphasic calcium phosphate granules and fibrin sealant

Introduction Fibrin glues are currently used by surgeons and can facilitate the handling of biomaterials. Combining fibrin glue with calcium phosphate bioceramics gives a mouldable composite that cements the granules into the implantation site. In addition to the mechanical aspect of the composite, it has been suggested that the mixture also promotes wound healing. These human blood derivatives contain natural (aprotinin) or synthetic (tranexamic acid) antifibrinolytic substances. We compared the bioactivity of two composites combining calcium phosphate granules with two different types of fibrin glue, one with aprotinin and the other with tranexamic acid.Materials and methods The composite was composed of fibrin glue (Tissucol) and 1 to 2 mm granules of biphasic calcium phosphate granules (MBCP) with a volume ratio of 1 for 2. Bone cavities were drilled in 12 New Zealand rabbits and filled with a composite with aprotinin-fibrin glue on the right condyle and one with tranexamic acid-fibrin glue on the left condyle. The rabbits were randomized into two groups: 3 and 6 weeks of delay. Light microscopy, scanning electron microscopy and image analysis were performed.Results No adverse reactions were observed in either sample. Bony ingrowth associated with bioceramic resorption by osteoclastic TRAP-positive cells was noted. No significant difference was observed between the two composites. The bony ingrowth and ceramic resorption were qualitatively and quantitatively similar with both composites.Conclusion This study demonstrated that the choice of a natural (aprotinin) or synthetic (tranexamic acid) antifibrinolytic agent in the fibrin sealant associated with calcium phosphate granules and used as a bone substitute had no effect on the bioactivity of the composite. It remained efficient in bone reconstruction, no adverse effects were observed, and the bony ingrowth was qualitatively and quantitatively equivalent with the two types of fibrin sealant.     

乌司他丁和抑肽酶对心肌缺血再灌注损伤保护作用的对比研究

目的评价乌司他丁和抑肽酶对小儿心内直视术围体外循环(CPB)期心肌缺血再灌注损伤的保护作用。方法按入选标准筛选2004-01—2005-08在温州医学院附属第二医院治疗的90例先天性心脏病患儿,随机双盲法分成6组:对照组(A组),小剂量乌司他丁组(10000U/kg,B组),大剂量乌司他丁组(20000U/kg,C组),小剂量抑肽酶组(75000kIU/kg,D组),大剂量抑肽酶组(150000kIU/kg,E组),小剂量乌司他丁 小剂量抑肽酶组(F组),每组15例。于CPB前(T1)、升主动脉开放后5min(T2)、CPB结束后30min(T3)、4h(T4)、24h(T5)5个时间点抽取桡动脉血,行血浆心肌肌钙蛋白I(cTnI)浓度及肌酸磷酸激酶(CK)、肌酸磷酸激酶同工酶(CK-MB)活性测定。术中定时监测激活全血凝固时间(ACT),红细胞压积(HCT);同时记录主动脉阻断(ACC)时间、总转流时间、心脏复跳情况及围术期血管活性药物使用情况。结果C、E、F组cTnI、CK、CK-MB明显低于A组(P<0.05);在T5点,B、D组cTnI明显低于A组(P<0.05)。与F组比较,A、B、D组cTnI、CK-MB,A组CK浓度明显升高(P<0.05)。B组与C组、D组与E组比较,cTnI、CK-MB浓度明显升高(P<0.05)。F组自动复跳率较A组增高,血管活性药物使用率较A组降低(P<0.05)。结论围CPB期单次使用乌司他丁和抑肽酶都能减轻心肌缺血再灌注损伤,药效呈剂量依赖性,但两者的保护作用差异无显著性;使用小剂量乌司他丁加小剂量抑肽酶减轻心肌损伤较为合理。