N,N-diethyldithiocarbamate produces copper accumulation, lipid peroxidation, and myelin injury in rat peripheral nerve.

Previous studies have demonstrated the ability of the dithiocarbamate, disulfiram, to produce a peripheral neuropathy in humans and experimental animals and have also provided evidence that N,N-diethyldithiocarbamate (DEDC) is a proximate toxic species of disulfiram. The ability of DEDC to elevate copper levels in the brain suggests that it may also elevate levels of copper in peripheral nerve, possibly leading to oxidative stress and lipid peroxidation from redox cycling of copper. The study presented here investigates the potential of DEDC to promote copper accumulation and lipid peroxidation in peripheral nerve. Rats were administered either DEDC or deionized water by ip osmotic pumps and fed a normal diet or diet containing elevated copper, and the levels of metals, isoprostanes, and the severity of lesions in peripheral nerve and brain were assessed by ICP-AES/AAS, GC/MS, and light microscopy, respectively. Copper was the only metal that demonstrated any significant compound-related elevations relative to controls, and total copper was increased in both brain and peripheral nerve in animals administered DEDC on both diets. In contrast, lesions and elevated F2-isoprostanes were significantly increased only in peripheral nerve for the rats administered DEDC on both diets. Autometallography staining of peripheral nerve was consistent with increased metal content along the myelin sheath, but in brain, focal densities were observed, and a periportal distribution occurred in liver. These data are consistent with the peripheral nervous system being more sensitive to DEDC-mediated demyelination and demonstrate the ability of DEDC to elevate copper levels in peripheral nerve. Additionally lipid peroxidation appears to either be a contributing event in the development of demyelination, possibly through an increase of redox active copper, or a consequence of the myelin injury.     

Protection against kainate neurotoxicity by pyrrolidine dithiocarbamate

The effect of pyrrolidine dithiocarbamate (PDTC) on kainate (KA)-induced neurotoxicity was examined in Sprague-Dawley rats. At 10 mg/kg, i.p., KA produced seizures accompanied by neuronal loss in the hippocampus and increased levels of malondialdehyde (MDA) and protein carbonyl. Pretreatment with PDTC (100 or 200 mg/kg, p.o., every 12 h x 5) blocked KA-induced neurotoxicities (seizures, increases in MDA and protein carbonyl and neuronal losses) in a dose-dependent manner. These effects were counteracted by the adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dimethylxanthine (25 or 50 micro g/kg, i.p.), but not by the A(2A) receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine (0.5 or 1 mg/kg, i.p.) or the A(2B) receptor antagonist alloxazine (1.5 or 3.0 mg/kg, i.p.). Our results suggest that the anticonvulsant and neuroprotective effects of PDTC are mediated, at least in part, via adenosine A(1) receptor stimulation.     

吡咯烷二硫代氨基甲酸盐下调基质金属蛋白酶9表达机制的研究

目的探讨TNF-α诱导的肺泡巨噬细胞(AM)性基质金属蛋白酶9(MMP-9)表达的信号通路以及吡咯烷二硫代氨基甲酸盐(PDTC)对MMP-9表达的影响机制。方法从慢性阻塞性肺疾病患者支气管肺泡灌洗液中分离与培养AM,以PDTC预处理AM,以TNF-α或IL-1刺激AM。半定量逆转录-聚合酶链反应法检测MMP-9 mRNA的表达;Western blot检测MMP-9蛋白的表达及TNF-α或IL-1诱导的IκBα磷酸化水平。凝胶阻滞分析实验检测NF-κB活性。结果TNF-α上调AM源性MMP-9 mRNA和蛋白的表达(P<0.05);PDTC抑制TNF-α诱导的MMP-9的表达(P<0.05)。PDTC对TNF-α或IL-1诱导的IκBα的磷酸化均无抑制作用(P>0.05)。PDTC对TNF-α或IL-1诱导的NF-κB的活化均有抑制作用(P<0.05);且PDTC不能在体外直接抑制NF-κB的DNA结合活性(P>0.05)。结论NF-κB在TNF-α诱导的AM源性MMP-9的表达中起着重要作用;PDTC可能通过抑制泛素化-蛋白酶小体途径来下调TNF-α诱导的AM源性MMP-9的表达。     

静脉滴注联合不同口服药物治疗糖尿病周围神经病变的疗效及安全性

目的:探讨糖尿病周围神经病变(diabetic peripheral neuropathy,DPN)在静脉给药治疗联合不同口服药物的疗效维持时间及安全性.方法:将180例DPN病人予静脉滴注甲钴胺、前列地尔、α-硫辛酸治疗15d后,按性别分层随机分为5个口服药物组(A～ E)和1个对照组(F),每组30例.口服药物组分别给予甲钴胺(A)、通心络胶囊(B)、西洛他唑(C)、贝前列素钠(D)、舒洛地特(E)3个月.分别在静脉滴注治疗前、静脉滴注治疗后15d,口服药物后30、60、90 d对各组行症状评分[(total symptom scores(TSS)和number,severity,change(NSC)];静脉滴注治疗前、静脉滴注治疗后15d、口服药物后90 d记录各组运动、感觉神经传导速度,并观察有无不良反应.结果:在口服药物治疗60 d后,与对照组相比,贝前列素钠和舒洛地特组TSS评分改善有统计学意义(P＜0.05);口服药物治疗90 d后,与对照组相比,通心络、贝前列素钠和舒洛地特组TSS评分改善,差异有统计学意义(P＜0.01).口服药物90 d后,所有口服药物组与对照组相比,NSC评分、正中神经运动和感觉传导速度差异均有统计学意义(P＜0.05).结论:治疗DPN,静脉给药联合口服药物,特别是通心络胶囊、贝前列素钠、舒洛地特对静脉给药后的疗效维持效果显著,且安全性良好.     

降糖保健品致汞砷中毒性周围神经病3例报道

目的：分析3例汞砷中毒性周围神经病的临床特点,总结重金属中毒周围神经病的诊疗经验。方法：回顾3例口服同一种降糖保健品（汞砷超标）引起中毒性周围神经病患者的临床诊疗情况。结果：3例患者发病前口服摩柯复合片数月,亚急性起病,病情进行性加重,以四肢末梢型感觉和运动障碍为主要表现,神经电生理检查均提示多发性运动和（或）感觉周围神经损害,轴索损害为主。1例呼吸困难者应用激素和丙种球蛋白后疗效差,其他2例应用激素后均有缓解。结论：激素和丙种球蛋白对重金属中毒所致周围神经病的疗效有差异,临床需重视既往药物和保健品的使用史。     

Developmental toxicity of the dithiocarbamate pesticide sodium metam in zebrafish.

Sodium metam (NaM), a dithiocarbamate, is a general agricultural biocide applied prior to planting for the elimination of nematodes, soil pathogens, and weeds. There is a remarkable paucity of information about the mechanism of action and the risk that dithiocarbamates may pose to developing vertebrates. We have characterized NaM toxicity during early life stage exposure in zebrafish. Zebrafish embryos are most sensitive to NaM exposure during gastrulation and early segmentation (4-14 hours post fertilization, hpf). For mortality, the dose response curve is steep with an LC(50) estimate of 1.95 microM (248 ppb) at 48 hpf. The most notable malformation among surviving embryos was a severely twisted notochord, which became evident by 24 hpf. Surprisingly, this notochord defect was not immediately lethal and the animals continued to grow despite delays in hatching, apparent paralysis, and an inability to feed. We have characterized the notochord malformation using histological and in situ hybridization techniques. collagen 2a1 mRNA expression is normally localized to the notochord sheath cells at 24 hpf, whereas in NaM-exposed embryos it is misexpressed in the notochord cells. Histological staining and myoD expression indicate that the myotomes of the NaM-exposed embryos are less defined, compacted and block-shaped compared to controls. The degradation product of NaM, methyl isothiocyanate (MITC), causes similar malformations at similar concentrations as NaM, suggesting that MITC or another common product may be the active toxicant. Our results indicate that developing zebrafish are sensitive to NaM and MITC and we believe that this model is ideal to elucidate the molecular mechanism(s) and etiology of NaM toxicity in vertebrates.     

基于中国临床证据的前列地尔对DPN患者神经传导速度作用的Meta分析

目的 系统评价前列地尔(Alprostadil)防治糖尿病性周围神经病变(DPN)患者临床疗效的有效性,为临床应用该药防治DPN提供证据.方法 运用系统评价的方法,计算机全面检索Cochrane图书馆临床对照试验资料库、Pubme数据库、中国知网期刊全文数据库等相关资料,检索时限均为从建库至2013年12月.按照Cochrane系统评价的方法分析纳入试验的质量,提取本研究观察的有效资料,采用RevMan 5.2软件对纳入研究的资料进行Meta分析.结果 按照相关要求,共纳入11篇前列地尔对DPN患者神经传导速度作用随机对照试验,包括935例试验研究对象.结果数据表明,与研究中的对照组相比,Alprostadi组可提高腓总神经、正中神经的运动神经传导速度[MD=-5.87,95％ CI(-6.31,-5.43),P＜0.01],[MD=-5.63,95％ CI(-6.05,-5.20),P＜0.01];提高腓总神经、正中神经的感觉神经传导速度[MD=-4.91,95％ CI(-5.35,-4.48),P＜0.01],[MD=-5.51,95％ CI(-5.96,-5.06),P＜0.01].结论 现有证据表明,Alprostadi对DPN患者临床疗效是确定的,主要通过改善神经传导速度.     

Reversal of behavioural and electrophysiological correlates of experimental peripheral neuropathy by the NK1 receptor antagonist GR205171 in rats

In adult rats response latencies to innocuous mechanical stimuli were found to be reduced and, in electrophysiological studies, the receptive fields of dorsal horn neurones were enlarged 7–14 days after chronic constriction injury of the sciatic nerve. The NK₁ receptor antagonist GR205171 at 3 mg kg⁻¹ blocked responses to NK₁ agonist evoked activity and reversed the mechanical hypersensitivity following nerve ligation in behavioural assays. GR205171 also reversed the receptive field expansion of spinal dorsal horn neurones caused by loose ligation of the sciatic nerve in an electrophysiological assay in anaesthetised rats. The less active enantiomer L-796,325 did not block NK₁ agonist evoked activity at up to 10 mg kg⁻¹ and had no effect on behavioural or electrophysiological changes following nerve injury, indicating that the effects of GR205171 were attributable to selective NK₁ receptor blockade. These data suggest that NK₁ receptor antagonists may be useful for the treatment of certain types of neuropathic pain.     

Imaging the peripheral benzodiazepine receptor response in central nervous system demyelination and remyelination.

We used a rodent model of cuprizone-induced demyelination to examine the peripheral benzodiazepine receptor (PBR) response during remyelination. C57BL/6J mice were fed a 0.2% cuprizone-containing or control diet for 3 weeks and then removed to allow for remyelination. Quantitative autoradiography of 3H-(R)-PK11195 binding to PBR in the corpus callosum showed increased levels at 3 weeks of demyelination and gradually decreased as a function of remyelination. PBR levels were associated with the degree of remyelination and activation of microglia and astrocytes. However, the temporal pattern suggests that the PBR signal during the late stages of remyelination was primarily associated with astrocytes. We also used small-animal positron-emission tomography (PET) imaging to determine if this technique could be used to monitor PBR levels in the brain of living mice. The results indicate that 11C-(R)-PK11195 levels are significantly elevated in the mouse brain during cuprizone-induced demyelination and normalize at a time in which remyelination is complete. These findings support the notion that PBR is a sensitive marker for the visualization and quantification of brain injury and recovery. Further, the in vivo imaging of the PBR response is now possible in the living rodent brain.     

丹参多酚酸盐治疗糖尿病周围神经病变的临床疗效及对血清炎性细胞因子、血管内皮功能的影响

目的 探讨丹参多酚酸盐治疗糖尿病周围神经病变(DPN)的临床效果及对血清炎性细胞因子、血管内皮功能的影响.方法 按照随机数字表法将116例DPN病人分为观察组和对照组,对照组给予甲钴胺治疗,观察组在此基础上给予丹参多酚酸盐治疗,观察两组治疗效果.结果 两组病人治疗后空腹血糖、糖化血红蛋白水平对比,差异无统计学意义(P>0.05);观察组病人疗程结束后总有效率明显高于对照组,差异有统计学意义(P<0.05);观察组病人治疗后白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)下降幅度均显著高于对照组,差异有统计学意义(P<0.05);观察组病人治疗后一氧化氮(NO)升高幅度,可溶性细胞间黏附分子-1(sICAM-1)、内皮素-1(ET-1)下降幅度均显著高于对照组,差异有统计学意义(P<0.05);观察组病人治疗后超氧化物歧化酶(SOD)升高幅度、同型半胱氨酸(HCY)下降幅度均显著高于对照组,差异有统计学意义(P<0.05).结论 在甲钴胺基础上加用丹参多酚酸盐能够有效提高DPN治疗效果,改善病人血清炎性细胞因子水平和血管内皮功能,应用价值较高.     

以口服马法兰为主的预处理外周血干细胞移植治疗恶性血液病的临床观察

目的观察以口服马法兰为主的预处理方案外周血干细胞移植治疗恶性血液病的疗效及毒副反应。方法对笔者所在医院收治的10例以口服马法兰为主的预处理外周血干细胞移植治疗的恶性血液病患者的临床资料进行分析,临床观察药物的毒副反应并评估造血重建速度及患者预后。结果所有患者中,5例出现胃肠道不适,心前区不适及口腔炎等毒副反应,经对症治疗好转。口服马法兰无明显的毒副作用,预处理总有效率为70%,不同剂量对疗效无差别。结论口服马法兰为主的预处理方案用于外周血干细胞移植治疗恶性血液病是安全有效的;黏膜炎及胃肠道反应是静脉马法兰应用后最常见的副反应。     

Interactions of copper and manganese: A mechanism by which manganese alleviates copper toxicity to the marine diatom, Nitzschia closterium (Ehrenberg) W. Smith

The mechanism by which manganese (4.2 and 42 μg Mn·1^?1) ameliorates the toxicity of copper (0–60 μg Cu·1^?1) to the marine diatom, Nitzschia closterium (Ehrenberg) W. Smith, was investigated using unsupplemented sea water for growth rate experiments. Speciation of manganese associated with the cellls, intracellular and extracellular manganese and copper concentrations, and competitive binding between copper and manganese were studied using ultrafiltration, anodic stripping voltammetry and radiochemical techniques.Cells cultured before the sea-water assay and in the absence of manganese accumulated high intracellular copper, and their growth rate was more sensitive to copper than cells cultured in the presence of manganese. Manganese associated with the cells was present as manganese (II) and/or (III) hydroxides, rather than as the fully oxidized MnO₂. It is proposed that manganese (III) hydroxide, like iron (III) hydroxide and cobalt (III) hydroxide, adsorbs copper very effectively on the membrane surface and prevents its penetration into the cell. Competitive interactions between manganese and copper occurred at the cell surface, but copper had no effect on intracellular manganese. Only 4 μg Mn·1^?1 was required to alleviate copper toxicity, compared to 790 μg Fe·1^?1. In the presence of algae, copper ions had a greater affinity for manganese in sea water than iron at similar concentrations, which may partially account for the relative effectiveness of manganese as a protective agent. In addition, manganese can scavenge the toxic superoxide radical (O₂^?), catalyzing its dismutation to H₂O₂ and O₂.Manganese was unable to reverse copper toxicity, nor did it inhibit the toxicity of lipid-soluble copper complexes, such as copper oxinate, to N. closterium.     

Identification of genes involved in the toxic response of Saccharomyces cerevisiae against iron and copper overload by parallel analysis of deletion mutants.

Iron and copper are essential nutrients for life as they are required for the function of many proteins but can be toxic if present in excess. Accumulation of these metals in the human body as a consequence of overload disorders and/or high environmental exposures has detrimental effects on health. The budding yeast Saccharomyces cerevisiae is an accepted cellular model for iron and copper metabolism in humans primarily because of the high degree of conservation between pathways and proteins involved. Here we report a systematic screen using yeast deletion mutants to identify genes involved in the toxic response to growth-inhibitory concentrations of iron and copper sulfate. We aimed to understand the cellular responses to toxic concentrations of these two metals by analyzing the different subnetworks and biological processes significantly enriched with these genes. Our results indicate the presence of two different detoxification pathways for iron and copper that converge toward the vacuole. The product of several of the identified genes in these pathways form molecular complexes that are conserved in mammals and include the retromer, endosomal sorting complex required for transport (ESCRT) and AP-3 complexes, suggesting that the mechanisms involved can be extrapolated to humans. Our data also suggest a disruption in ion homeostasis and, in particular, of iron after copper exposure. Moreover, the identification of treatment-specific genes associated with biological processes such as DNA double-strand break repair for iron and tryptophan biosynthesis for copper suggests differences in the mechanisms by which these two metals are toxic at high concentrations.     

Differential gene expression in human peripheral blood mononuclear cells induced by cigarette smoke and its constituents.

In current molecular epidemiology studies, a wide range of methods are used to monitor early biological effects after exposure to xenobiotic agents. Gene expression profiling is considered a promising tool that may provide more sensitive, mechanism-based biomarkers. As a first step toward obtaining information on the applicability of gene expression profiles as a biomarker for early biological effects of carcinogen exposure, we conducted in vitro studies on human peripheral blood mononuclear cells (PBMC). We used cigarette smoke condensate (CSC) and a selection of its genotoxic constituents as model agents, applying cDNA microarray technology to investigate modulated gene expression. In independent experiments using cells from several donors, quiescent PBMC were exposed for 18 h, followed by gene expression analyses on a microarray containing 600 toxicologically relevant genes. The search for candidate biomarker genes was binomial: first we looked for genes responding similarly to all agents; second, for agent-specific genes. Many genes were significantly deregulated by all compounds, but as the direction of deregulation frequently differed per agent, they are not useful as generic biomarkers. Cigarette smoke condensate modulated the expression of many more genes than any of its constituents, with the largest effect in SERPINB2. The affected genes are involved in immune or stress responses, but surprisingly no genes involved in DNA damage response were modulated, and only a few in DNA repair. In conclusion, several genes have been identified as potential biomarkers for population studies on early biological effects caused by cigarette smoke exposure, but no genes were identified that represent a generic biomarker.     

Characterizing the influence of structure and route of exposure on the disposition of dithiocarbamates using toluene-3,4-dithiol analysis of blood and urinary carbon disulfide metabolites.

Differences in the toxicities observed for dithiocarbamates have been proposed to result from the influence of nitrogen substitution, oxidation state, and route of exposure. To better characterize the fate of dithiocarbmates in vivoas a function of structure and route of exposure, rats were administered equimolar doses of carbon disulfide (CS2), N-methyldithiocarbamate, pyrrolidine dithiocarbamate, N,N-diethyldithiocarbamate, or disulfiram daily for five days, either po or ip, and sequential blood samples obtained. Protein dithiocarbamates formed by the in vivo release of CS2, parent dithiocarbamate, and protein-bound mixed disulfides were assessed in plasma and hemolysate by measuring toluene trithiocarbonate generated upon treatment with toluene-3, 4-dithiol (TdT). To aid in determining the bioavailability of CS2 from the administered dithiocarbamates, the urinary CS2 metabolites, 2-thiothiazolidine-4-carboxylic acid (TTCA) and 2-thiothiazolidin-4-ylcarbonylglycine (TTCG), were also determined. The levels of TdT-reactive moieties detected depended upon both the compound administered and the route of exposure. Parent dithiocarbamates, with the exception of disulfiram, were eliminated from blood within 24 h; but protein associated TdT-reactive moieties persisted and accumulated with repeated exposure, regardless of the route of exposure. N-Methyldithiocarbamate demonstrated the greatest potential to produce intracellular globin modifications, presumably through its unique ability to generate a methylisothiocyanate metabolite. Urinary excretion of TTCA and TTCG was more sensitive than TdT analysis for detecting dithiocarbamate exposure, but TdT analysis appeared to be a better indicator of in vivo release of CS2 by dithiocarbamates than were urinary CS2 metabolites. These data suggest that CS2 is a more important metabolite, following oral exposure, than are other routes of exposure, e.g., inhalation or dermal. In addition, data also suggest that acid stability, nitrogen substitution, and route of exposure are important factors governing the toxicity observed for a particular dithiocarbamate.     

Dietary exposure to aroclor 1254 alters central and peripheral vasopressin release in response to dehydration in the rat.

Central vasopressin (VP) release from magnocellular neuroendocrine cells (MNCs) in the supraoptic nucleus (SON) occurs from their somata and dendrites within the SON several hours after acute dehydration, and is an important autoregulatory mechanism influencing the systemic release of VP from MNC terminals in the posterior pituitary. To begin to explore the impact of polychlorinated biphenyls (PCBs) on brain mechanisms of body fluid regulation, both central and systemic VP release in response to acute dehydration were assessed in adult male rats fed the commercial PCB mixture Aroclor 1254 (30 mg/kg/day) for 15 days. Water intake and body weight were recorded daily, and on day 15 rats were dehydrated by intraperitoneal injection of 3.5 M saline (controls received physiological saline) and sacrificed 4-6 h later. Intranuclear VP release was measured in SON tissue punches in vitro, and systemic VP release was measured in the same rats. SON prepared from dehydrated PCB-naive rats released significantly more VP than did SON from control rats (4.9 +/- 0.8 vs. 2.7 +/- 0.4 pg/ml/microg). In contrast, while Aroclor 1254 exposure had no effect on baseline water intake, weight gain, or plasma osmolality responses to dehydration in PCB-fed rats, the SON failed to respond with increased VP release during dehydration. Consistent with previous studies showing an inhibitory effect of central VP on plasma VP output, dehydrated PCB-fed rats had an exaggerated 863% increase in plasma VP over basal levels, compared to a 241% increase in PCB-naive rats, suggesting that the MNC system is subtly disrupted.     

海洋来源链霉菌FIM090041产生的神经氨酸酶抑制剂

目的筛选神经氨酸酶抑制剂,发现潜在的抗流感药物先导化合物。方法利用神经氨酸酶抑制剂高通量筛选方法,从海洋微生物菌库中筛选产生神经氨酸酶抑制剂的菌株,采用多种色谱技术分离纯化获得活性化合物,通过紫外、质谱、核磁共振等现代波谱学方法鉴定其结构。结果分离到两个吲哚生物碱类活性化合物1和化合物2,结构解析确定它们分别与SF2583 A和SF2583 B同质,对神经氨酸酶的IC50为67.8μmol/L和122.8μmol/L,Ki为13.5μmol/L和21.6μmol/L。结论本文首次报道该化学结构类型化合物对神经氨酸酶具有一定的抑制作用。     

Salicylate enhances necrosis and apoptosis mediated by the mitochondrial permeability transition.

Onset of the mitochondrial permeability transition (MPT) causes both necrotic and apoptotic cell death in cultured hepatocytes. Salicylate lowers the threshold for onset of the MPT. In this study, our aim was to determine whether nontoxic concentrations of salicylate potentiate MPT-mediated cell killing. In necrotic killing models to rat hepatocytes, salicylate (1 mM) enhanced calcium ionophore (Br-A23187)- and tert-butylhydroperoxide (t-BuOOH)-induced cell death, which was blocked or delayed by cyclosporin A (CsA, 2 microM), a specific inhibitor of the MPT. In hepatocyte apoptosis induced by tumor necrosis factor-alpha (TNF-alpha), salicylate accelerated cell killing after low-dose TNF-alpha (1 ng/ml), which by itself induced little apoptosis. Salicylate enhancement of apoptosis was associated with onset of the MPT and accelerated caspase 3 activation. Salicylate also augmented killing of MCF-7 human breast tumor cells by etoposide and PLC/PRF/5 human hepatoma cells by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). In conclusion, salicylate potentiates both necrotic and apoptotic cell killing by promoting onset of the MPT. Enhancement by salicylate of MPT-dependent apoptosis may play a role in protection by aspirin and other nonsteroidal anti-inflammatory drugs against colon, lung, and breast cancer.     

海洋链霉菌211726代谢产物的研究

目的对来自海洋环境的链霉菌211726(Streptomyces sp.211726)的代谢产物进行分离鉴定。方法采用大孔吸附树脂和硅胶柱色谱对链霉菌211726(Streptomyces sp.211726)的代谢产物进行分离,并通过理化性质及波谱学手段对所得化合物进行结构鉴定。结果与结论分离并鉴定了2个化合物:Nocardamine(1)及其铁络合物Ferrioxamine E(2),化合物2为首次从链霉菌中分得,化合物1、2为首次同时从同一微生物中分离获得。