Co and Cr accumulation in hair after metal-on-metal hip resurfacing arthroplasty

Background: Currently, it is unclear whether Co and Cr levels are persistently elevated in the body after hip resurfacing arthroplasty (HRA). This study aimed to evaluate Co and Cr levels in the body after HRA using hair as samples. Methods: Among 22 patients who had metal‐on‐metal HRA (m‐o‐m group) using the DePuy ASR system, scalp hair of 1.5 cm in length and 2 g in weight was collected before and at 6 and 12 months after surgery. Inductively coupled plasma‐mass spectrometry (ICP‐MS) was used to detect Co and Cr levels in the scalp hair. Another 22 patients with total hip replacements were randomly selected from a similar age range as controls (m‐o‐p group). Metal levels in hair were detected with multiple measurements and analysed by repeated measures analysis of variance. Results: Both Co and Cr levels were significantly increased in the m‐o‐m group after surgery compared with those in the m‐o‐p group (P < 0.01). Co levels at 6 months post‐operatively were 12‐fold those before surgery, and Co levels 12 months post‐operatively were lower than those at 6 months, but this difference was not significant (P= 0.0805) between the two time points in the m‐o‐m group. Cr levels were persistently elevated after surgery and were increased by 10‐fold compared with those at baseline in the m‐o‐m group. Conclusions: Co and Cr levels in scalp hair are ideal indicators for metal levels in the body after HRA. Co and Cr levels in the body were greatly increased after metal‐on‐metal HRA. Long‐term accumulation of these metals needs to be further investigated.     

Synthesis and Electrochemistry of Schiff Base Cobalt(III) Complexes and Their Catalytic Activity for Copolymerization of Epoxide and Carbon Dioxide

A series of cobalt complexes with N,N,O,O‐tetradentate Schiff base ligands were prepared. All the complexes were characterized by spectroscopy and electrochemical methods. An X‐ray crystal structure analysis revealed that L¹ ‐Co ^III ‐dnp was monomeric with a six‐coordinated central cobalt(III) atom in the solid state. The complexes were employed as catalysts for the alternating copolymerization of CO₂ and racemic propylene oxide. End group analysis of the resulting polymer provided strong evidence for a monomer insertion mechanism for the propagation step. The catalytic activity was interpreted using the redox potential of cobalt(II/III) for the L ‐Co ^III ‐dnp complexes, which offered a measure of the bond strength, or the degree of inertness of the axial ligand, to promote or suppress the monomer insertion.

     

Hypoxic preconditioning facilitates acclimatization to hypobaric hypoxia in rat heart

Objectives Acute systemic hypoxia induces delayed cardioprotection against ischaemia‐reperfusion injury in the heart. As cobalt chloride (CoCl₂) is known to elicit hypoxia‐like –responses, it was hypothesized that this chemical would mimic the preconditioning effect and facilitate acclimatization to hypobaric hypoxia in rat heart. Methods Male Sprague‐Dawley rats treated with distilled water or cobalt chloride (12.5 mg Co/kg for 7 days) were exposed to simulated altitude at 7622 m for different time periods (1, 2, 3 and 5 days). Key findings Hypoxic preconditioning with cobalt appreciably attenuated hypobaric hypoxia‐induced oxidative damage as observed by a decrease in free radical (reactive oxygen species) generation, oxidation of lipids and proteins. Interestingly, the observed effect was due to increased expression of the antioxidant proteins hemeoxygenase and metallothionein, as no significant change was observed in antioxidant enzyme activity. Hypoxic preconditioning with cobalt increased hypoxia‐inducible factor 1α (HIF‐1α) expression as well as HIF‐1 DNA binding activity, which further resulted in increased expression of HIF‐1 regulated genes such as erythropoietin, vascular endothelial growth factor and glucose transporter. A significant decrease was observed in lactate dehydrogenase activity and lactate levels in the heart of preconditioned animals compared with non‐preconditioned animals exposed to hypoxia. Conclusions The results showed that hypoxic preconditioning with cobalt induces acclimatization by up‐regulation of hemeoxygenase 1 and metallothionein 1 via HIF‐1 stabilization.     

Survivin在PC12细胞对抗化学性缺氧损伤中的作用

目的探讨存活素(survivin)在PC12细胞对抗氯化钴(CoCl2)诱导损伤中的作用。方法应用不同浓度的CoCl2处理PC12细胞不同时间,建立化学性缺氧诱导PC12细胞损伤的实验模型。应用CCK-8比色法检测细胞存活率;Western-blot法检测CoCl2诱导缺氧与survivin表达间的量效(200～1000μmol·L-1)和时效(0～48h)关系。结果CoCl2可明显抑制PC12细胞的存活率,且呈浓度和时间依赖性。应用不同浓度CoCl2处理PC12细胞24h,在200～600μmol·L-1浓度范围内,呈浓度依赖性地促进survivin表达,600μmol·L-1CoCl2诱导survivin表达达高峰,超过此浓度,则随着CoCl2浓度的增加,survivin表达逐渐下降,CoCl2浓度达1000μmol·L-1时,survivin基本不表达;应用600μmol·L-1CoCl2处理PC12细胞,在0～36h时间范围内,呈时间依赖性地促进PC12细胞survivin的表达,但随着处理时间的延长,survivin的表达逐渐下降;加入2μmol·L-1Hsp90抑制剂17-丙烯胺基-17-去甲氧基格尔德霉素(17-AAG),不仅可以降低600μmol·L-1 CoCl2诱导的survivin高表达,而且加重了600μmol·L-1 CoCl2对PC12细胞的损伤作用,使细胞存活率降低。结论survivin表达上调可能是PC12细胞对抗化学性缺氧损伤的内在防御机制之一。     

Cobalt release from inexpensive jewellery: has the use of cobalt replaced nickel following regulatory intervention?

Background: Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure. Objectives: The aim was to study 354 consumer items using the cobalt spot test. Cobalt release was assessed to obtain a risk estimate of cobalt allergy and dermatitis in consumers who would wear the jewellery. Methods: The cobalt spot test was used to assess cobalt release from all items. Microstructural characterization was made using scanning electron microscope (SEM) and energy‐dispersive spectroscopy (EDS). Results: Cobalt release was found in 4 (1.1%) of 354 items. All these had a dark appearance. SEM/EDS was performed on the four dark appearing items which showed tin–cobalt plating on these. Conclusions: This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future. Industries may not be fully aware of the potential cobalt allergy problem.     

Review of cobalt toxicokinetics following oral dosing: Implications for health risk assessments and metal-on-metal hip implant patients

Abstract

Cobalt (Co) can stimulate erythropoietin production in individuals at doses exceeding 25 mg CoCl₂/day. Co has also been shown to exert effects on the thyroid gland, heart and nervous system at sufficient doses. The biological activity of Co is dictated by the concentration of free (unbound) ionic Co²⁺. Blood concentrations, as well as, urinary excretion rates of Co are reliable biomarkers for systemic Co exposure. A recent series of human volunteer Co-supplement studies simultaneously measured Co blood and urine concentrations, as well as, Co speciation in serum, and a number of biochemical and clinical parameters. It was found in these studies that peak Co whole blood concentration as high as 117 μg/L were not associated with changes in hematological parameters such as increased red blood cell (RBC) count, hemoglobin (Hgb) or hematocrit (Hct) levels, nor with changes in cardiac, neurological or, thyroid function. Using a Co biokinetic model, the estimated Co systemic tissue concentrations (e.g., liver, kidney, and heart) following 90-days of Co-dietary supplementation with ～1 mg Co/day were found to be similar to estimated tissue concentrations in implant patients after 10 years of exposure at continuous steady state Co blood concentration of ～10 μg/L. This study is the first to present modeled Co tissue concentrations at various doses following sub-chronic and chronic exposure. The modeled steady state tissue Co concentrations in combination with the data on adverse health effects in humans should help in the characterization of potential hazards associated with increased blood Co concentrations due to exposure to dietary supplements or cobalt-chromium (Co-Cr) containing implants.     

Manganese–Cobalt Based Spinel Coatings Processed by Electrophoretic Deposition Method: The Influence of Sintering on Degradation Issues of Solid Oxide Cell Oxygen Electrodes at 750 °C

This paper seeks to examine how the Mn–Co spinel interconnect coating microstructure can influence Cr contamination in an oxygen electrode of intermediate temperature solid oxide cells, at an operating temperature of 750 °C. A Mn–Co spinel coating is processed on Crofer 22 APU substrates by electrophoretic deposition, and subsequently sintered, following both the one-step and two-step sintering, in order to obtain significantly different densification levels. The electrochemical characterization is performed on anode-supported cells with an LSCF cathode. The cells were aged prior to the electrochemical characterization in contact with the spinel-coated Crofer 22 APU at 750 °C for 250 h. Current–voltage and impedance spectra of the cells were measured after the exposure with the interconnect. Post-mortem analysis of the interconnect and the cell was carried out, in order to assess the Cr retention capability of coatings with different microstructures.     

益气通络疏肝汤治疗带状疱疹后遗神经痛随机平行对照研究

[目的]观察益气通络疏肝汤治疗带状疱疹后遗神经痛疗效。[方法]使用随机平行对照方法,将43例门诊患者按抽签法简单随机分为两组。对照组20例阿米替林,50~100mg/次,3次/d;甲钴胺,0.5mg/次,3次/d;维生素B1,20mg/次,2次/d。治疗组23例益气通络疏肝汤(桃仁、红花各10g,当归15g,柴胡10g,白芍20g,生黄芪30g,栀子15g,蜈蚣2条,山药20g,延胡索25g,甘草6g),1剂/d,水煎200mL,早晚饭后温服。连续治疗10d为1疗程。观测临床症状、VAS评分、皮损、不良反应。连续治疗2疗程,判定疗效。[结果]治疗组痊愈16例,显效2例,有效4例,无效1例,总有效率95.65%。对照组痊愈7例,显效6例,有效2例,无效5例,总有效率75.00%。治疗组疗效优于对照组(P0.05)。VAS评分两组均有明显降低(P0.05),治疗组降低优于对照组(P0.05)。[结论]益气通络疏肝汤治疗带状疱疹后遗神经痛效果显著,值得推广。