Toxic effects of benzo[a]pyrene (Bap) and Aroclor1254 on embryogenesis, larval growth, survival and metamorphosis of the bivalve Meretrix meretrix

To assess the potential toxicity of polycyclic aromatic hydrocarbons and polychlorinated biphenyls on the early development of Meretrix meretrix, the effects of benzo[a]pyrene (Bap) and Aroclor1254 on embryogenesis and larval development were investigated using static laboratory toxicity tests at nominal concentrations of 6.25-1,600 μg/L. Even at 1,600 μg/L, Bap and Aroclor1254 only caused minor reductions in embryo development rates. The 96 h LC(50) values for D-shaped larvae were 156 μg/L for Bap and 132 μg/L for Aroclor1254, respectively. The most sensitive toxicity endpoint in this study was metamorphosis, with an EC(50) value of 20 μg/L for Bap and 35 μg/L for Aroclor1254. Aroclor1254 was more toxic than Bap to embryos and larvae. Our results indicate that Bap and Aroclor1254 do not show extreme toxicity to M. meretrix embryos and larvae. These data provide information for evaluating the toxicity of Bap and Aroclor1254 on bivalve embryos, especially over the entire larval stages.     

Combined toxicity of dissolved mercury with copper, lead and cadmium on embryogenesis and early larval growth of the Paracentrotus lividus sea-urchin

The individual and combined toxicity of dissolved mercury, copper, lead and cadmium has been investigated by using the Paracentrotus lividus sea-urchin embryo-larval bioassay. Embryogenesis success and early larval growth have been recorded after incubation of fertilised eggs in seawater, both with single metals and binary combinations of Hg with every other metal. For individual metals the ranking of toxicity was Hg > Cu > Pb > Cd, with EC₅₀ values of 21.9, 66.8, 509 and 9240g/l, respectively. Lowest observed effect concentrations (LOEC) for early larval growth were approximately three times lower than the EC₅₀ values for Hg, Cu and Pb, and more than two orders of magnitude lower for Cd, emphasizing the danger of underestimating toxicity when only lethal effects are recorded. Marking & Dawson's additive indices ranged from 0.10 to 0.19, indicating additive effects with a slight trend to synergism, which was statistically significant for the Hg–Pb combination only. Hayes' additive indices were within the margins considered acceptable to describe additive interactions.     

文蛤Meretrix meretrix化学成分研究

首次从文蛤中分离得到3个甾醇，通过MS，IR，NMR谱确定其结构为胆甾醇(1)、5α，8α—过氧胆甾6—烯—3β—醇(2)、和胆甾—4—烯—3β，6β—二醇(3)。     

Effects of lead,cadmium and mercury on brain adenylate cyclase

The effects of lead, cadmium and mercury ions on adenylate cyclase activity of rat cerebrum, cerebellum and brain stem were studied in vitro and in vivo. Adenylate cyclase activity in homogenates of cerebellum as well as cerebrum and brain stem was found to be inhibited by micromolar concentrations of these heavy metal ions in vitro. Administration of lead acetate trihydrate (25 mg/kg body wt i.v.) produced an initial increase of adenylate cyclase activity in the cerebellum and brain stem 1 h after injection, followed by a significant decrease of enzyme activity in cerebrum and cerebellum 4 h after the injection. Chronic lead treatment achieved by feeding lead containing diets, which generated blood lead levels of 31.3 ± 3.8, 68.8 ± 1.5 and 121.5 ± 8.6 μg Pb/100 g blood resp., produced a significant increase of brain lead levels and a 10–30% reduction of adenylate cyclase activity in cerebrum, cerebellum and brain stem. Phosphodiesterase activity was reduced under these conditions in the range of 10–20% in cerebellum and brain stem, but not in cerebrum.     

Gentamicin nephrotoxicity in cadmium, lead and mercury pretreated rats

The effect of a previous chronic exposure to cadmium, lead or inorganic mercury on the nephrotoxic potential of gentamicin was investigated in female Sprague-Dawley rats. A daily dose of 10 mg gentamicin/kg body weight/day was administered for 21 days to rats having a renal load of 168 micrograms Cd, 35 micrograms Pb or 129 micrograms Hg/g whole kidney. Urine analysis suggests an attenuation of the nephrotoxic potential of gentamicin while a microscopical examination of kidneys indicates a superimposition of the effects of the metals and the antibiotics. The only clear interaction observed consists in a reduction of gentamicin accumulation in the cortex of cadmium-treated animals. It is concluded that none of the metal pretreatments potentiates the nephrotoxic effects of gentamicin.     

文蛤多糖的提取及含量测定

目的确定文蛤多糖提取的最佳工艺,以苯酚-硫酸显色,分光光度法测定文蛤多糖含量。方法采用超声波提取,酸水解法进行处理;利用苯酚-硫酸显色,标准曲线在490nm处分光光度法测定。结果超声提取30min,提取2次,料水比1∶20为最佳工艺。曲线在4.848~24.242 mg.L-1范围内呈良好的线性关系,回归方程:C=28.69A 0.229(r=0.9992);平均回收率为100.67%,RSD为2.83%(n=6)。结论本实验文蛤多糖的提取及含量测定操作简便,结果准确,重现性好,可用于文蛤多糖的提取与含量测定。     

Bovine blood quality control material for cadmium, mercury, and lead

A protocol is elaborated for the preparation and characterization of a quality control material (QCM) containing intrinsic concentration of cadmium (Cd) (0.8 microgram/L) and lead (Pb) (13.4 micrograms/dL) from bovine blood and an elevated QCM containing Cd (5.0 micrograms/L), mercury (Hg) (11.2 micrograms/L), and Pb (34.5 micrograms/dL) from bovine blood spiked with aqueous spiking-solutions prepared with salts of Cd, Hg, and Pb. Borosilicate glass septum vials of 7-mL capacity were filled with 5 mL of blood, sealed with Teflon-silicone discs and plastic screw caps, and stored at -20 degrees C. Quality control, intervial and intravial, and storage stability values for Cd, Hg, and Pb were ascertained by analyzing the blood in randomly selected vials by an internal laboratory using modified published methods which were established for detection limit, accuracy, and precision. Validation of the protocol was demonstrated by intravial and intervial homogenity for Cd, Hg, and Pb and no change occurred in the concentrations of the elements in bovine blood containing EDTA at storage temperatures of 4 degrees C and -20 degrees C for 2 years.     

文蛤活性蛋白的分离及体外抗氧化作用

目的研究文蛤肉活性蛋白体外抗氧化作用。方法采用匀浆、硫酸铵分级沉淀、Sephadex G-150柱层析从文蛤肉中分离到3个蛋白峰P1,P2和P3,测定其超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性和抑制脂质过氧化(LPO)作用。结果P2的CAT活性最高,比活力为77.0 U.mg-1;P3的SOD活性最高,比活力为68.8 U.mg-1;P3抑制LPO作用最强,20μg蛋白的抑制率为50%。经SDS-PAGE结果P1以相对分子质量18.0 kD的组分为主;P2存在与对照CAT相对应的条带,其相对分子质量约为28.0 kD;P3存在与对照SOD相对应的条带,其相对分子质量约为16.0 kD。结论从文蛤肉中分离到的活性蛋白具有抗氧化作用。     

镉、铅、汞对苯巴比妥诱导肝微粒体药物代谢酶的影响

一次ip醋酸镉2.4mg/kg、醋酸铅100mg/kg或氯化汞 2.0 mg/kg均可抑制大鼠肝微粒体药物代谢酶。上述处理还可明显降低苯巴比妥对肝微粒’乙基吗啡N-脱甲基化酶、氨基比林N-脱甲基化酶、苯胺羟化酶和环己巴比妥羟化酶活力的诱导作用,降低苯巴比妥对细胞色素P450和细胞色素 b_5以及微粒体蛋白合成的诱导作用。结果提示镉、铅、汞可能通过降低微粒体酶的新生合成,抑制肝微粒体药物代谢酶。     

Toxicity of cadmium and lead on vascular cells that regulate fibrinolysis

Cadmium and lead are heavy metals that cause vascular lesions such as atherosclerosis and hypertension. Toxicity of cadmium and lead on the regulation of fibrinolysis by vascular-composing cells was investigated using a cell culture system. It was found that cadmium promotes the synthesis of plasminogen activator inhibitor-1 (PAI-1) whereas lead inhibits the synthesis of tissue plasminogen activator (t-PA) in vascular endothelial cells; consequently, both heavy metals reduced fibrinolytic activity in the liquid phase. The responses of endothelial cells to cadmium and lead were different from those to other heavy metals and the release of the fibrinolytic proteins from vascular smooth muscle cells and fibroblasts was perturbed by cadmium and lead in different manners. In conclusion, the present study showed that cadmium and lead exhibit their toxicity on fibrinolysis regulated by vascular cells in different manners among cell types and the individual cell types respond to cadmium and lead in different manners with respect to the release of fibrinolytic proteins.     

文蛤糖肽(MGP0405)的抗肿瘤活性及稳定性研究

从海洋帘蛤科动物文蛤中提取所得糖肽MGP0405（Meretrix meretrix GlycoPeptide）的体内外抗肿瘤活性研究。文蛤粗提液经超滤、大孔吸附层析和凝胶过滤层析等方法提取纯化得到相对分子质量为9672的MGP0405。以溴化二苯偶氮盐（MTT）比色法考察MGP0405对体外培养的癌细胞的抑制作用和稳定性研究。结果表明，MGP0405在30℃以下以及中性环境中活性保持稳定。MGP0405对体外培养的8种肿瘤细胞有不同程度的抑制作用，其中对人鼻咽癌细胞（KB）的抑制作用最强，并呈量效关系。此外，MGP0405具有抑制肿瘤细胞与基底膜成分的黏附作用，对S180荷瘤鼠具有很好的体内抗肿瘤活性。     

镉、铅、汞、砷和铬致肾损伤机制的研究进展

重金属镉、铅、汞、砷和铬是最常见的环境和职业危害因素。不同的重金属对人体损伤的表现不尽相同,但都具有肾损伤特性。多年来,国内外学者对这些重金属的肾损伤机制进行了较多的研究。本文综述了其氧化应激、细胞凋亡、金属硫蛋白、生物膜损伤和细胞内Ca²⁺平衡失调的几种肾损伤机制。     

Monoamine oxidase activity in placenta in relation to manganese,cadmium, lead,and mercury at delivery

BackgroundEnvironmental prenatal exposure to potentially neurotoxic metals poses a particular challenge with regard to the study of early toxic effects. Monoamine oxidase activity, shown to be influenced by metals in experimental studies, could be a useful biomarker in humans.ObjectiveTo examine the relationship between blood metal concentrations at delivery and placenta MAO activity.MethodsThe study was performed in 163 pregnancies. Maternal and cord blood samples were obtained for manganese (Mn), lead (Pb), and cadmium (Cd) determination. Mercury (Hg) was also analysed in maternal hair. Placental samples were stored immediately after expulsion and total MAO activity was measured.ResultsMAO activity was significantly positively correlated with maternal and cord blood Mn concentrations in subjects with high MAO activity. In subjects with low MAO activity, maternal hair Hg was negatively correlated with MAO.ConclusionOur results suggest the use of placental MAO as a potential surrogate marker of Mn toxicity in the newborn and its correlation with psychomotor development should be further investigated.     

In vitro effects of lead, mercury and cadmium on the enzymic activity of red-blood cell pyrimidine 5'-nucleotidase

The decrease of pyrimidine 5'-nucleotidase (P5N) in human erythrocytes, detected in persons occupationally exposed to lead (Pb), is not an in vitro artefact resulting from the release of lead during erythrocyte hemolysis but is a true reflection of the enzyme activity in vivo. Like Pb, mercury (Hg) and cadmium (Cd) ions exhibit an important in vitro inhibitory action on the P5N enzymic activity. However, when the metals are preincubated as metallothionein complexes with P5N preparations, their inhibitory power disappears.     

Effects of environmental levels of cadmium,lead and mercury on human renal function evaluated by structural equation modeling

A relationship between exposure to heavy metals, including lead and cadmium, and renal dysfunction has long been suggested. However, modeling of the potential additive, or synergistic, impact of metals on renal dysfunction has proven to be challenging. In these studies, we used structural equation modeling (SEM), to investigate the relationship between heavy metal burden (serum and urine levels of lead, cadmium and mercury) and renal function using data from the NHANES database. We were able to generate a model with goodness of fit indices consistent with a well-fitting model. This model demonstrated that lead and cadmium had a negative relationship with renal function, while mercury did not contribute to renal dysfunction. Interestingly, a linear relationship between lead and loss of renal function was observed, while the maximal impact of cadmium occurred at or above serum cadmium levels of 0.8 μg/L. The interaction of lead and cadmium in loss of renal function was also observed in the model. These data highlight the use of SEM to model interaction between environmental contaminants and pathophysiology, which has important implications in mechanistic and regulatory toxicology.     

Urinary metallothionein and tissue metal levels of rats injected with cadmium, mercury, lead, copper or zinc

Since Cd exposure results in a dose dependent increase in metallothionein level in urine, the present investigation was conducted to examine whether exposure to other divalent cations would also cause an elevation in urinary metallothionein. Female Sprague-Dawley rats were injected subcutaneously with either saline, 5 mumol/kg/day of CdCl2, HgCl2, Pb(C2H3O2)2, CuSO4 or ZnCl2 for 5 days. Significant increases in hepatic Cu levels in rats treated with not only Cu, but also Zn, Cd, or Hg, and in hepatic Zn levels in rats treated with Zn or Cd were noted. Similarly, renal Cu and Zn levels were elevated significantly in all groups except the Pb-injected group. These increases in tissue metal levels were presumably due to induction of metallothionein. The urinary metallothionein level in control rats on day 0, determined by radioimmunoassay, was 0.85 +/- 0.17 mg/g creatinine. There was no significant change in urinary metallothionein level in rats given up to 5 injections of saline or Pb. Hg-injected rats showed 25-fold increase in urinary metallothionein after 5 injections, whereas Cd-injected rats had 9-fold increase. There were also 2- and 3-fold increases of urinary metallothionein by Cu and Zn treatments for 5 days, respectively. Thus, urinary metallothionein levels were elevated in response to Cd, Hg, Cu and Zn, but not Pb; Hg had the most profound effect at equimolar doses.     

Content and daily intake of copper, zinc, lead, cadmium, and mercury from dietary supplements in Mexico.

This study investigates the presence of Cu, Zn, Cd, Pb, and Hg in 24 dietary supplements purchased in different health stores across the city of Hermosillo, located in the northwest of Mexico. Analysis of metals was done by microwave digestion and atomic absorption spectroscopy. The most abundant elements in dietary supplements were Cu (<0.19-137.85 microg/g) and Zn (<2.83-4785.71 microg/g), followed by Pb (<0.003-66.32 microg/g), Cd (<0.001-2.90 microg/g), and Hg (<0.24-0.85 microg/g). The estimated daily intakes of metals were below those recommended by WHO and the Institute of Medicine, showing that little risk from heavy metals is associated with the consumption of the dietary supplements analyzed. However, some products presented more than 10% of the tolerable daily intake of Pb, indicating that production processes should be improved.     

In vitro and in vivo effect of mercury, lead and cadmium on the generation of chemiluminescence by human whole blood

A method based on the use of the luminogenic substance, luminol, was developed for measuring the respiratory burst induced by phorbolmyristate acetate in 4 microliters of human whole blood. In vitro, the three cations, Hg2+, Pb2+ and Cd2+, inhibit the peak luminescence response at concentrations higher than those usually found in blood of subjects exposed to these metals. Cadmium metallothionein, however, in a concentration range similar to that found in whole blood of workers exposed to cadmium strikingly reduces the respiratory oxidative burst. In workers exposed to inorganic lead or mercury vapour, no reduction of the chemiluminescence response of whole blood was observed while a slight but statistically significant reduction was found in whole blood from cadmium exposed workers. If a similar effect occurs in lung macrophages, it might decrease the respiratory tract resistance to infection.     

Concentrations of arsenic, cadmium, copper, lead, mercury, and zinc in human placentas from two cities in Ukraine

Ukraine is a highly industrialized country with major environmental problems and deteriorating reproductive health. Heavy metals are known reproductive toxins; a study was undertaken to determine whether they were present at sufficient concentrations to be playing a major role in these health problems. Placental concentrations of arsenic, cadmium, copper, lead, mercury, and zinc were determined in 200 women from the general population of two urban areas of Ukraine, Kyiv and Dniprodzerzhinsk. Arsenic was detected in only 5% of the samples, lead in 22%, and mercury in 28%. Cadmium was detected in almost all samples, with a median of 5.2 ng/g. Concentrations of lead, mercury, and cadmium were low compared to those reported elsewhere, while zinc and copper concentrations were comparable.     

Effects of depleted uranium on survival, growth, and metamorphosis in the African clawed frog (Xenopus laevis)

Embryos (stage 8-47, Nieuwkoop and Faber) of the African clawed frog (Xenopus laevis) were subjected to water-borne depleted uranium (DU) concentrations that ranged from 4.8 to 77.7 mg/L using an acute 96-h frog embryo teratogenesis assay-Xenopus (FETAX). In a chronic 64-d assay, X. laevis (from embryo through metamorphosis; stages 8-66) were subjected to concentrations of DU that ranged from 6.2 to 54.3 mg/L. Our results indicate DU is a non teratogenic metal. No effects on mortality, malformations, or growth were observed in the 96-h FETAX with concentrations of DU that ranged from 4.8 to 77.7 mg/L. From stage 8 to stage 47, X. laevis tadpoles do not actively feed and the gills are not well developed. Thus, uptake of DU was reduced despite exposure to elevated concentrations. The 64-d assay resulted in no concentration response for either mortality or malformations; however, a delay in metamorphosis was observed in tadpoles subjected to elevated DU concentrations (from 13.1 to 54.3 mg/L) compared to tadpoles in both the well-water control and reference. The delay in metamorphosis was likely due to increasing body burden of DU that ranged from 0.98 to 2.82 mg/kg.