实验性汞中毒时肾组织和尿中碱性磷酸酶活性的变化

本研究采用亚急性汞中毒肾损害的大鼠模型,探讨了汞中毒时血、肾和尿中碱性磷酸酶(ALP)活性的变化关系。结果表明,大鼠肾匀浆中 ALP活性明显低于对照组,尿 ALP活性则显著增加。ALP 活性降低的部位在肾近曲小管。体外实验未发现氯化汞对肾、尿ALP 具有直接抑制作用或激活作用。尿中ALP 活性的增高是汞引起的肾小管上皮细胞损伤所致。它可作为汞中毒肾损害的一个观察指标。     

氯化镉,顺铂肾毒性的比较研究

我们比较研究了氯化镉、顺铂的肾脏毒性。氯化镉和顺铂均可引起典型的中毒性肾损害，氯化镉引起的肾损害肾小管功能障碍早于肾小球病变；而顺铂引起的肾损害肾小球功能障碍早于肾小管障碍。染镉动物体内镉主要分布于肝脏，随染毒时间延长有逐渐向肾脏集中的趋势；顺铂则主要分布于肾脏。氯化镉可在肝、肾中诱导合成金属硫蛋白（ＭＴ），尿镉的排泄量与尿中ＭＴ含量密切相关；顺铂不能在肝、肾中诱导ＭＴ合成，尿铂的排泄与尿ＭＴ无关。     

镉中毒肾损害大鼠尿中不同分子量镉,锌结合物的研究

研究结果表明,肾功能受损以前,尿镉仅以小分子结合镉的形式排泄;当肾镉负荷超过其临界浓度并引起肾功能障碍后,尿镉排泄急剧增加,其绝大多数以金属硫蛋白结合镉的形式排泄,同时小分子结合镉也继续增多;随着肾损害的加重,尿中又相继出现中、高分子蛋白质结合镉。但是,尿金属硫蛋白结合镉是肾脏受损后尿镉的主要形式。正常动物尿锌主要以小分子结合锌形式存在,镉性肾损害严重时方有尿锌显著升高,且主要系高分子结合锌排泄增多。     

酸性鞘磷脂酶在镉性肾损害中的变化

目的 观察酸性鞘磷脂酶(ASMase)在镉性肾损害过程中的活性变化及规律,探讨ASMase活性变化与镉性肾损害的关系。方法 60只SD雄性大鼠随机分为对照组和实验组,实验组动物腹腔注射1mg/kg Cd2+,每天1次、每周5次,对照组注射等体积的生理盐水。染毒第0、1、3、5和7周末实验组、对照组每组各随机处死6只动物,收集血、尿及肾组织。ELISA法测尿β2微球蛋白的含量,高效液相色谱法测血、尿及肾组织中ASMase活性,制作病理切片观察肾组织病变情况。结果 随染毒时间的延长,肾组织有不同程度的病理改变。与对照组相比,实验组动物肾脏系数随染毒时间的延长而增加(P<0.05);尿β2微球蛋白含量随染毒时间的延长而增加(P<0.05);血、尿、肾组织匀浆上清液中ASMase活性从染毒第3周开始随染毒时间的延长而增加(P<0.05)。结论 镉性肾损害中ASMase活性随染毒时间的延长而增加。     

重复注射镉金属硫蛋白的肾脏毒性

本文给大鼠腹腔注射0.3mg Cd/kg的镉金属硫蛋白(Cd-Me),每周一次,连续5周。每次注射后收集24小时尿样后处死2～3只大鼠取血、肝、肾以供检查,为了观察肾损害的后果及可恢复性,一组动物保留观察到第6周,即停止任何处理后1周。 重复注射Cd-Mt可导致屡见于慢性镉盐中毒     

急性氟中毒大鼠肾损害及其机理研究

本研究以NaF 0、30、60,90mg/kg灌胃,观察大鼠48小时急性氟中毒尿氟排泄规律、肾损害情况及其与LPO的关系。结果发现:中毒大鼠尿氟浓度在中毒3小时显著升高,中毒6小时达高峰;肾损害指标尿AKP活性显著增强,峰值分别在12、24小时;尿蛋白含量显著升高,峰值在36小时;肾匀浆MDA含量显著升高,肾匀浆GSH含量显著降低,肾G—6—Pase活性显著下降,以上三指标均存在显著的剂量效应关系,肾SDHase活性显著降低。提示氟中毒可损害肾脏;其损害的机理之一是LPO;损害亚细胞部位可能在线粒体和微粒体。     

N-乙酰半胱氨酸和亚硒酸钠对镉亚慢性毒性的影响

目的探讨N-乙酰半胱氨酸(N-acetyl cysteine,NAC)和亚硒酸钠(Na2SeO3)对亚慢性染镉大鼠肝肾毒性的影响及其机制。方法32只Wistart大鼠随机分为4组,每组8只,第1组为对照组,第2组为单位染镉组,第3、4组为干预组。大鼠连续6周皮下注射7μmol/kg氯化镉,然后干预组分别腹腔注射1 mmol/kg NAC和10μmol/kg Na2SeO3,共2周;测定大鼠尿N-乙酰-β-苷酶(NAG)、碱性磷酸酶活力(ALP)和肝、肾皮质谷胱甘肽(GSH)、丙二醛(MDA)含量及谷胱甘肽过氧化物酶(GSH-Px)活力。结果亚慢性染镉使大鼠肝、肾皮质和尿镉含量显著升高,尿ALP、NAG和蛋白含量显著升高,肝、肾皮质GSH含量显著升高,GSH-Px活力显著降低。与单纯染镉组比较,NAC处理组尿镉、NAG和蛋白含量显著下降,肝、肾皮质GSH显著降低;Na2SeO3处理组尿镉、ALP及肝、肾皮质GSH含量显著下降,GSH-Px活力显著升高。结论NAC和Na2SeO3对镉致肾损伤的恢复具有促进作用,其机制可能与NAC或Na2SeO3改变体内GSH含量和GSH-Px活力有关。     

氯丙嗪、尼莫地平对大鼠体内镉分布的影响

目的　利用亚急性镉 (Ｃｄ)中毒性肾损伤动物模型 ,观察钙调素抑制剂氯丙嗪 (ＣＰＺ)和钙离子通道阻断剂尼莫地平(Ｎｉｍｏ)对体内镉分布的影响。方法　镉组 :腹腔注射Ｃｄ2ｔ1 4ｍｇ ｋｇ(3次 周 ,共 6周 )、ＣＰＺ及Ｎｉｍｏ组染镉 (剂量同镉组 )前分别用ＣＰＺ 4ｍｇ ｋｇ或Ｎｉｍｏ 3ｍｇ ｋｇ预防处理动物。测定血、肝、肾镉含量及肝、肾金属硫蛋白 (ＭＴ)含量。结果　Ｎｉｍｏ组血镉和肝镉含量分别为 0 5 0 5 μｇ ｍｌ和 (4 4 0 7± 7 89)μｇ ｇ肝重 ,均显著低于镉组 (Ｐ <0 5 ) ,肾镉含量与镉组比较 ,差异无显著性 ;肝、肾ＭＴ含…     

褪黑素对糖尿病大鼠氧化抗氧化系统及Smac表达的影响

目的 探讨褪黑素(MT)对链脲佐菌素(STZ)诱导的糖尿病大鼠氧化抗氧化系统的调控及第二线粒体源半胱天冬氨酸蛋白酶激活物(Smac)表达的影响.方法 STZ诱导糖尿病大鼠模型后随机分为糖尿病组(DM组,10只)和MT干预组(MT组,10只),并以正常组(NC组,9只)作对照.干预8周后,检测大鼠心肝肾损伤相关指标肌酸激酶(CK)、乳酸脱氢酶(LDH)、天冬氨酸转氨酶(AST)、丙氨酸转氨酶(ALT)、总胆红素(TBil)、血尿素氮(BUN)、血肌酐(SCr)、尿蛋白排泄率(UAER)水平;观察心、肝、肾组织形态学变化;测定血清及心、肝、肾组织中丙二醛(MDA)的含量及超氧化物歧化酶(SOD)活性;免疫组化法分析心、肝、肾中Smac蛋白的表达.结果 MT显著改善糖尿病大鼠心肝肾损伤相关指标的水平及大鼠组织病理形态,明显降低血清及各组织中MDA的含量,增强SOD的活性,下调Smac的表达.结论 MT可能通过调节氧化抗氧化系统平衡,下调Smac的表达,发挥对糖尿病大鼠心脏、肝脏、肾脏功能的保护作用.     

镉致大鼠肾损害时尿酶变化及其意义

我们报道镉中毒大鼠尿液主要生化指标和肾皮质组织病理改变，结果表明，尿总蛋白、葡萄糖、ｒ－谷氨酰转移酶（ｒ－ＧＴ）、碱性磷酸酶（ＡＬＰ）和Ｎ－乙酰－Ｄ－氨基葡萄糖苷酶（ＮＡＧ）排泄均明显增加，光镜和电镜下见近曲小管细胞浊肿、水样变性，微绒毛稀疏脱落，线粒体肿胀变性及胞浆空泡形成。提示Ｃａ２＋是ＣｄＭＴ的毒作用形式，尿ｒ－ＧＴ、ＮＡＧ是镉性肾损害的理想监测指标。     

Significance of increase in urinary metallothionein of rats repeatedly exposed to cadmium

Cadmium chloride was injected subcutaneously (s.c.) into female Wistar rats at a dose of 1 mg Cd/kg body weight, 5 times a week up to 10 weeks. At specified intervals, 24-h urine was collected and the excreted amounts of metallothionein (MT), cadmium, copper, zinc and several indicators of renal damage were determined. Concentrations of cadmium and MT in the livers and kidneys of rats were also determined. Both cadmium and MT in the livers and kidneys were increased upon cadmium exposure. The urinary MT excretion started to increase within a week after the start of exposure. This increased excretion preceded those of enzymes and total protein as well as histopathological abnormalities in the proximal tubular cells. After the occurrence of tubular damage that disturbs reabsorption of MT, MT in urine was drastically increased. These results indicate that urinary MT levels may be an indicator not only of cadmium exposure but also of tubular damage.     

Measurement of cadmium-induced metallothionein in urine by ELISA and prevention of overestimation due to polymerization.

Urinary metallothionein (MT) is a biological marker of cadmium (Cd) exposure and Cd-induced renal dysfunction. The MT is prone to oxidation due to high cysteine content and forms polymers, which can result in overestimation of the protein by immunochemical methods. The objectives of the present study were to develop an enzyme-linked immunosorbent assay (ELISA) for the measurement of MT in urine and to find ways by which the protein could either be preserved in its monomeric form or converted to this form before analysis to avoid overestimation. Urine specimens analyzed were either from rats repeatedly injected with Cd or from individuals chronically exposed to cadmium through their diets. The MT in rat urine remained in the monomeric form if the urine was collected at 4 degrees C but did not if it was collected at room temperature. The MT was also polymerized if the urine was subjected to repeated freezing and thawing. Overestimation of MT in rat urine occurred (as much as 12-fold) if the MT was polymerized. Addition of 5mM mercaptoethanol to freshly collected rat urine retarded MT polymerization, and addition of 50mM mercaptoethanol converted the polymerized MT to its monomeric form. Analysis of MT in frozen human urine samples revealed that if the urines were not treated with mercaptoethanol, the estimates of MT concentration were up to 11-fold higher than in the treated samples. We conclude that the polymerization of MT in rat and human urines is a serious problem and results in overestimation of the protein by ELISA and that this problem could be overcome by the addition of mercaptoethanol to the urine samples prior to analysis.     

Sex differences in hepatic and renal cadmium accumulation and metallothionein induction. Role of estradiol

The role of estradiol in sex differences in hepatic and renal cadmium accumulation and metallothionein (MT) induction was investigated. Male and female rats and castrated males pretreated with estradiol were injected either i.v. or s.c. with 10 mumol CdCl2/kg. Sex differences in cadmium accumulation and MT induction were apparent after s.c. but not i.v. administration. The female rats accumulated a significantly greater concentration of cadmium in their liver than did the males, as early as 1 hr after the s.c. injection. The elevated levels of cadmium in the females were maintained for at least 10 days. Pretreatment of castrated males with estradiol caused a similarly greater accumulation of cadmium in the liver. Hepatic MT levels peaked in the females at 24 hr and in males 48-72 hr after the cadmium injection and then declined to lower levels. This superinduction of MT occurred only after the s.c. administration of cadmium. MT levels in both sexes plateaued 5 days after the s.c. injection to the levels that were similar to those seen in male and female rats 24 hr after an i.v. injection. In animals injected s.c. with cadmium the renal cadmium levels continued to rise for 5-10 days; however, in animals injected i.v. the levels stabilized within 2 hr. The renal MT levels in the females were significantly higher than in the males. Estradiol pretreatment induced renal MT but did not affect renal cadmium accumulation. Thus, the sex differences in hepatic cadmium accumulation and MT induction are affected by the route and time after the administration of cadmium. Furthermore, estradiol causes a more rapid uptake of cadmium by the liver and also an enhanced induction of MT in both the liver and kidney.     

Chelation in metal intoxication: influence of cysteine or N-acetyl cysteine on the efficacy of 2,3-dimercaptopropane-1-sulphonate in the treatment of cadmium toxicity.

The influence of cysteine or N-acetyl cysteine administration on the efficacy of 2,3-dimercaptopropane-1-sulphonate (DMPS) in the treatment of cadmium intoxication was investigated in cadmium-pre-exposed rats. Cysteine, N-acetyl cysteine, DMPS, DMPS + cysteine or DMPS + N-acetyl cysteine were about equal in effectiveness in mobilizing hepatic cadmium mainly from its supernatant cytosolic fraction (SCF) and both of the combinations were more effective than either of them alone in mobilizing cadmium from its nuclear mitochondrial fraction (NMF). The DMPS was apparently more effective than cysteine or N-acetyl cysteine in mobilizing renal cadmium from its SCF or NMF and it was more effective than even their combinations in mobilizing cadmium from renal SCF. The treatment with cysteine or N-acetyl cysteine reduced cadmium-induced hepatic and renal metallothionein (MT) and the treatment with DMPS reduced renal MT only, probably due to removal of hepatic and renal SCF cadmium by these agents. However, MT levels were high in animals treated with DMPS + cysteine or DMPS + N-acetyl cysteine, despite lowering of cadmium in these tissues, suggesting a contribution of MT induced by cysteine or N-acetyl cysteine itself. The cadmium exposure increased hepatic and renal zinc and renal copper levels, probably as a result of cadmium-induced MT, and some of the levels were normalized considerably by the subsequent treatment with cysteine, DMPS or to a lesser extent N-acetyl cysteine and their combinations, showing their protective effects against cadmium toxicity. The increase in blood cadmium and the decrease in blood zinc and copper levels due to cadmium exposure also were reversed appreciably by some of these treatments. The results have shown a limited benefit of cysteine or N-acetyl cysteine administration on the efficacy of DMPS in the treatment of cadmium intoxication.     

Increased levels of metallothionein in placenta of smokers

Experiments were designed to evaluate and compare metallothionein (MT), zinc and cadmium levels in human placentas of smoking and non-smoking women. Smoking was assessed by self-reported cigarette consumption and urine cotinine levels before delivery. Smoking pregnant women with urine cotinine levels higher than 130 ng/ml were included in the smoking group. Determination of placental MT was performed by western blot analysis after tissue homogenization and saturation with cadmium chloride (1000 ppm). Metallothionein was analyzed with a monoclonal antibody raised against MT-1 and MT-2 and with a second anti mouse antibody conjugated to alkaline phosphatase. Zinc and cadmium were determined by neutron activation analysis and atomic absorption spectrometry respectively. Smokers showed higher placental MT and cadmium levels, together with decreased newborn birth weights, as compared to non-smokers. The semi-quantitative analysis of western blots by band densitometry indicated that darker bands corresponded to MT present in smokers' samples. This study confirms that cigarette smoking increases cadmium accumulation in placental tissue and suggests that this element has a stimulatory effect on placental MT production.     

锌金属硫蛋白对镉中毒小鼠肾损伤的修复作用

目的：研究锌金属硫蛋白（Zn-MT）对镉中毒小鼠肾损伤的修复作用。方法：以昆明种小鼠作为研究对象，染镉14d建立亚急性镉中毒模型，随后经口给予Zn-MT。收集24h尿液，测定尿N－乙酰－β－D－氨基葡萄糖苷酶（NAG酶）活性作为衡量肾脏损伤程度的一项指标，同时电镜观察肾组织形态学变化；测定并分析肾组织上清液中脂质过氧化代谢产物一丙二醛（MDA）水平、超氧化物歧化酶（SOD）、谷胱甘肽过氧化酶（GSH－Px)活性。结果：Zn-MT可明显降低肾组织中MDA水平，使肾组织中SOD、GSH－Px活力有一定程度的恢复，此时尿NAG酶活性降低表明肾损伤程度减轻，且上述作用呈明显的剂量－反应关系；电镜下观察到给予Zn-MT后肾组织形态学病变有所减轻。结论：Zn-MT可对镉中毒小鼠肾组织脂质过氧化损伤起到一定的修复作用。     

Occupational exposure to cadmium: effect on metallothionein and other biological indices of exposure and renal function

The effect of duration of employment at a North American cadmium smelter on urinary metallothionein (MT), total protein, ₂-microglobulin (2-MG), glucose, cadmium, copper and zinc of 53 men was studied. The levels of all urinary parameters increased with the duration of employment. Smoking history did not affect any of the above parameters studied. Although age was responsible for some of the changes noted in protein, glucose and ₂-MG levels, its effect on MT and cadmium was insignificant. All urinary parameters were significantly related with each other. The relationship of elevated urinary MT levels with respect to renal dysfunction was also examined. Subjects with abnormal renal function excreted significantly higher amounts of MT than did those with normal renal function. The results confirm not only that occupational exposure to cadmium over long periods results in renal dysfunction but also that urinary MT could be used to monitor exposure and ultimately the appearance of the renal dysfunction.     

The relationships of urinary metallothionein with other indicators of renal dysfunction in people living in a cadmium-polluted area in Japan

An epidemiologic investigation was carried out to study the significance of urinary excretion of metallothionein (MT) in people aged 50 years and over living in a cadmium (Cd)-polluted area in Japan. The urinary level of MT was compared with various parameters (age, urinary alpha 1-microglobulin (alpha 1-MG), beta 2-microglobulin (beta 2-MG), total protein, Cd, copper (Cu), and zinc (Zn), and relative clearances to creatinine of alpha 1-MG, beta 2-MG, phosphate and uric acid). It was found that the urinary excretion of MT is closely associated with Cd and the indices of renal dysfunction listed above. This observation was more remarkable in women than men. When subjects with signs of renal dysfunction were compared as a group to those with normal renal functions, the excreted amount of MT in the former is significantly greater. The results support the notion that the urinary excretion of MT reflects not only Cd exposure levels but also renal dysfunction caused by long-term Cd exposure.     

An evaluation of tissue metallothionein and genetic resistance to cadmium toxicity in mice

The role of metallothionein or metallothionein-like proteins (MT) in genetic resistance to the testicular and hepatic toxicity of cadmium was examined in inbred strains of mice. Mice of two strains resistant (AJ and C3H/HEJ) or susceptible (129J and DBA/2J) to cadmium-induced testicular necrosis were administered sc 30 mumol CdCl2/kg. The uptake of cadmium and the induction of MT in tissues were determined after 6 hr. The results showed that accumulation of cadmium in liver and kidney tissues of the four strains was very similar. MT levels were elevated up to 20-fold in the liver and up to almost 8-fold in the kidney, resulting in cadmium to MT molar ratios of 6.7 to 10.0 in the liver and 1.2 to 1.9 in the kidney. The greatest increase in hepatic MT as well as the cadmium to MT ratio was in the C3H/HEJ strain which is susceptible to cadmium-induced hepatotoxicity. Testicular cadmium levels were significantly elevated in the two susceptible strains. The basal levels of MT-like protein in the testis were generally higher than those in the kidney. Although, only the testis of 129J (susceptible) showed an increase in this protein after 6 hr, both susceptible strains injected with cadmium had significantly higher levels of the protein as compared to the resistant strains. The 30,000-Da cadmium-binding protein in AJ and CD-1 (susceptible) mouse strains was found to cross-react with the anti-MT-serum. Necrotic changes were visible in the testes of the susceptible strains as a result of cadmium administration. Immunohistochemically, there were no significant differences in the localization of MT in the liver, kidney or testis among the four strains. MT or an MT-like protein was concentrated mainly in the interstitial tissue of the mouse testis, but was also detected in the seminiferous tubules. It is concluded that the strain differences in acute toxicity of cadmium are probably not due to low MT concentration in tissues of the susceptible strains.