Factor Xa-activated whole blood clotting time (Xa-ACT) for bedside monitoring of dalteparin anticoagulation during haemodialysis.

BACKGROUND: Low molecular weight heparins (LMWH) like dalteparin are increasingly used for anticoagulation during haemodialysis (HD). The available laboratory tests for monitoring LMWH anticoagulation are time-consuming and expensive, and the suitability of the conventional activated clotting time (ACT) is controversial. A simple and cheap bedside test would be useful. METHODS: We studied the factor Xa-activated whole blood clotting time (Xa-ACT) in vitro and in vivo in nine patients undergoing chronic HD with i.v. dalteparin bolus anticoagulation and compared it with the conventional ACT. Plasma anti-factor Xa (antiXa) activity was determined with a chromogenic assay. Thrombin-antithrombin complexes were measured to detect coagulation activation. RESULTS: Xa-ACT and ACT were prolonged with rising dalteparin concentration. In vitro, both clotting times were strongly correlated with the antiXa levels (r = 0.94 and 0.89, respectively). Nevertheless, compared with the ACT, the Xa-ACT was considerably more sensitive to the LMWH in vitro (healthy blood: Xa-ACT 90 s/U vs ACT 26 s/U; uraemic blood: Xa-ACT 96 s/U vs ACT 31 s/U) as well as in vivo (Xa-ACT 81 s/U vs ACT 22 s/U) and reflected different intensities of anticoagulation. An initial dalteparin bolus of 80+/-11 U/kg body weight was able to prevent coagulation activation for up to 4 h of HD. CONCLUSION: For monitoring LMWH anticoagulation the Xa-ACT was superior to the conventional ACT in vitro as well as in vivo during HD. The Xa-ACT can be useful as a LMWH bedside test. The ACT was not sensitive enough to serve as a LMWH monitoring tool.     

草酸钙结石形成对肾组织bikunin和IαI表达的影响

目的研究肾草酸钙结石形成对肾组织bikunin基因和间α胰蛋白酶抑制物(IαI)蛋白表达的影响,探讨bikunin在尿结石形成中的意义。方法诱导实验性大鼠肾草酸钙结石模型,收集结石大鼠、正常大鼠、临床肾结石和非结石患者每组各8例的肾组织标本。采用免疫组化、逆转录聚合酶链反应(RT-PCR)和计算机图像分析技术分别检测所有大鼠和人肾组织中bikuninmRNA和IαI蛋白的表达水平。结果正常大鼠和非结石患者肾组织均存在bikuninmRNA和IαI蛋白的表达。肾草酸钙结石形成后,结石大鼠肾组织IαI蛋白的灰度值和bikuninmRNA的相对表达水平分别为198.43±15.17、0.70±0.14;肾结石患者肾组织IαI蛋白的灰度值和bikuninmRNA的相对表达水平分别为263.25±17.41、1.27±0.13,分别和对照组相比,均显著增加(P<0.05)。结论Bikunin作为构成IαI的轻链结构,在肾草酸钙结石形成后,bikuninmRNA的表达迅速增强,提示机体通过肾脏合成更多的bikunin来抑制肾草酸钙结石的形成。     

Thyrotrophin-Releasing Hormone Raises Cytosolic Free Calcium Concentration in Human Adenomatous Somatotrophs and Corticotrophs; Comparison with in vivo Responsiveness to Thyrotrophin-Releasing Hormone in Patients with Acromegaly or Cushing's Disease

The effect of thyrotrophin-releasing hormone (TRH) on intracellular free Ca²⁺ concentration, [Ca²⁺)i, was investigated with the fluorescent dye fura-2 in cell suspensions obtained from 13 human growth hormone-secreting adenomas and 6 adrenocorticotrophin-secreting adenomas. Preoperatively, 9 out of 13 acromegalic patients showed a positive growth hormone response to TRH administration while none of the 6 patients with Cushing's disease had a plasma adrenocorticotrophin increase after TRH injection. In all the growth hormone-secreting adenomas the addition of TRH (100 nM) caused a significant rise in [Ca²⁺]i (from a resting level of 133±40 (±SD) to a value of 284±119 nM at 100 nM TRH, n = 42; P<0.001). The transient induced by TRH was found to have a dual origin, one due to Ca²⁺ mobilization from intracellular stores which was maintained in presence of EGTA (3mM) and verapamil (10 μM) and a plateau phase due to Ca²⁺ influx from the extracellular media. Somatostatin (0.1 μM) lowered both resting [Ca²⁺]i and TRH-induced transients. The effect of gonadotrophin-releasing hormone on [Ca²⁺]i was evaluated on cell suspensions obtained from 6 growth hormone-secreting adenomas. Gonadotrophin-releasing hormone (100 nM) caused a marked rise in [Ca²⁺]i (from 179±25 to 283±15nM) on the cell suspension obtained from the only in vivo responsive adenoma while it was ineffective in the remaining 5. Although TRH was ineffective in modifying plasma adrenocorticotrophin levels in all patients with Cushing's disease, in 5 out of 6 tumors the addition of 100 nM TRH caused a significant rise in [Ca²⁺]i (from 102.5 ± 36 to 163±66 nM, n = 22; P < 0.005). However, the effect of TRH on [Ca²⁺]i was significantly lower than that caused by arginine vasopressin, a physiological stimulator of adrenocorticotrophin release ([Ca²⁺]i values; 145±78 nM at 100 nM TRH versus 300±140 at 10 nM arginine vasopressin, n = 15; P<0.05). Moreover, the effect of arginine vasopressin on [Ca²⁺]i was detectable at concentrations as low as 0.1 nM while TRH was effective at concentrations higher than 1 nM. By contrast, gonadotrophin-releasing hormone was ineffective in increasing [Ca²]i in all the adrenocorticotrophin-secreting adenomas studied. Collectively, these data indicate that sensitivity to TRH is present in almost all the growth hormone- and adrenocorticotrophin-secreting adenomas independently of the responsiveness of the individual patients to the peptide.     

Fibronectin inhibits endocytosis of calcium oxalate crystals by renal tubular cells

BACKGROUND: Fibronectin (FN; 230 kDa) is a multifunctional alpha2-glycoprotein distributed throughout the extracellular matrix and body fluids. We recently reported that FN has a protective effect against injury of renal tubular cells by exposure to oxalate and calcium oxalate (CaOX) crystals and inhibits the adhesion of CaOX crystals to renal tubular cells. In the study presented here, we investigated whether FN has inhibitory effect on crystal endocytosis by renal tubular cells. METHODS: The inhibitory effect of FN on endocytosis of CaOX crystals by MDCK cells was examined by using a radioactivity uptake assay. Also, crystal endocytosis by cells was morphologically assessed by means of transmission electron microscopy (TEM). RESULTS: FN had inhibitory effects on CaOX crystal endocytosis by MDCK cells. The morphological TEM study showed that few crystals were taken into cells when FN was added compared to the number of crystals when FN was not added. CONCLUSION: We found that FN had the inhibitory effects on the interaction between crystals and renal tubular cells, including the adhesion or endocytosis of crystals by cells.     

As_2O_3诱导人肝癌细胞凋亡及对Fas表达和钙含量的影响

化疗在原发性肝癌的综合治疗中占重要地位.为寻找肝癌治疗新的有效药物,我们观察了As2O3对人肝癌细胞株BEL7402的生物学效应,以期为As2O3临床治疗肝癌提供实验依据.     

早产儿静脉补钙的护理体会

目的:探讨早产儿静脉补钙的护理。方法:回顾性分析总结38例早产儿静脉补钙的临床观察和护理体会。结果:38例早产儿静脉补钙均未发生皮下组织的坏死与钙化灶。结论:高度认真负责,细心观察和护理,早预防,早发现,早期干预,及时有效处理,是避免钙剂外渗,促进好转的关键。     

Blood pressure lowering effect of the aqueous extract of the stem of Ipomoea acanthocarpa (convolvulaceae) in spontaneously and salt-loaded hypertensive rats

Spontaneously hypertensive (SHR) and salt-loaded hypertensive rats (SLHR) were submitted to a daily treatment by gavage of 2 mL/100 g body weight of the aqueous extract of the stem of Ipomoea acanthocarpa (30 mg/mL stock solution). A fall in blood pressure of nearly 13% was observed after two successive administrations of the aqueous extract. After 14 days of treatment, the blood pressure fell by more than 30±8%. The hypotensive effect might be due to a direct vascular smooth muscle effect or to its already observed high diuretic effects or might be acting by some other mechanism.     

The effects of changes to action potential duration on the calcium content of the sarcoplasmic reticulum in isolated guinea-pig ventricular myocytes

. We have estimated sarcoplasmic reticulum calcium content using rapid application of caffeine on voltage clamped, isolated guinea-pig ventricular myocytes. Caffeine induces the release of calcium from the sarcoplasmic reticulum and this calcium is extruded from the cells by the sarcolemmal Na/Ca exchange. Integrating the inward Na/Ca exchange current thus allows estimations of sarcoplasmic reticulum calcium content. Ventricular myocytes were stimulated to reach new steady-states by action potential voltage clamps of varying duration. Once contractile steady-state had been reached caffeine was rapidly applied in place of the next action potential and sarcoplasmic reticulum calcium content measured. Prolonging the action potential duration increased sarcoplasmic reticulum calcium content and vice-versa. This calcium loading may underlie the positive inotropic effect of increased action potential duration. Received: 11 July 1996 / Received after revision: 15 October 1996 / Accepted: 26 November 1996     

异搏定对胰腺腺泡细胞内游离钙离子浓度的影响

目的:探讨细胞内钙超负荷在急性胰腺炎(AP)发生发展中的作用.方法:使用140只SD大白鼠胆胰管逆行加压注射4.5%牛磺胆酸钠制成AP模型,用荧光指示剂Fura-2/Am测定游离胰腺腺泡细胞内游离钙离子浓度([Ca~(2 )]i).结果:注射后2小时和3小时胰腺呈急性出血坏死性炎症早期改变,制AP模型后AP组[Ca~(2 )]i较对照组明显增高(P<0.001),AP组胰腺腺泡细胞内[Ca~(2 )]i增高值与胰腺病理变化程度呈正相关关系(r_s=0.9727,P<0.001),异搏定治疗可明显提高病鼠生存率和改善胰腺组织出血坏死程度和腺泡细胞超微结构损害.结论:胰腺腺泡细胞内钙超负荷在胆汁性急性水肿性胰腺炎向出血坏死性胰腺炎转变中起明显作用,钙通道阻滞剂异搏定可明显阻止胰腺细胞内钙离子超负荷,是其治疗急性胰腺炎的主要机理之一.     

五味子酚对大鼠嗜中性白细胞功能与形态的作用(英文)

目的:探讨五味子酚(Sal)对大鼠嗜中性白细胞(Neu)功能的调节作用.结果:Sal 1,10,100μmol·L~(-1)剂量依赖性抑制Neu功能,Sal 100μmol·L~(-1)使Neu表面伪足和皱褶消失,并可降低细胞内钙离子浓度、升高细胞内cAMP水平.结论:Sal可通过影响细胞内钙离子浓度、cAMP水平及细胞表面形态抑制Neu的功能.