Quantum-Chemical Consideration of Al2M2 Tetranuclear Metal Clusters (M–3d-Element): Molecular/Electronic Structures and Thermodynamics

Quantum-chemical calculation of most important parameters of molecular and electronic structures of tetra-nuclear (pd) metal clusters having Al₂M₂ composition, where M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn (bond lengths, bond and torsion angles), and HOMO and LUMO of these compounds by means of DFT OPBE/QZVP method, have been carried out. It has been found that, for each of these metal clusters, an existence of rather large amount of structural isomers different substantially in their total energy, occurs. It has been noticed that molecular structures of metal clusters of the given type differ significantly between them in terms of geometric parameters, as well as in geometric form, wherein the most stable modifications of metal clusters considered are similar between themselves in geometric form. In addition, the standard thermodynamic parameters of formation of metal clusters considered here, and namely standard enthalpy Δ_fH⁰(298 K), entropy S_f⁰(298 K), and Gibbs’ energy Δ_fG⁰(298 K) of formation for these metal clusters, were calculated.     

Chromium as an industrial carcinogen: Part I

Successive cohorts by year of hire at the same chromate plant (1931-1932, 1933-1934, 1935-1937) and the combined cohort (1931-1937) of 332 employees were followed through 1993. A total of 283 deaths (85%) of the total cohort were identified. In the combined cohort (1931-1937), 66 lung cancers were found, constituting 23.3% of all deaths and 64.7% of all cancers. The lung cancer mortality rates are shown over a span of decades, from 15 years to over 55 years, with progressive rise. Observations of lung cancer identified, employees not found, and cancer risk by age at hire are cited. Lung cancer death rates increased by gradient level of exposure to insoluble (trivalent) chromium and to soluble (hexavalent) chromium, with a pattern of increase by total chromium. Age-specific death rates for lung cancer according to the same gradient exposure range for total, insoluble, and soluble chromium are presented. The potential cancer risk extends to all forms of chromium and to total chromium. Am. J. Ind. Med. 31:129–139, 1997. © 1997 Wiley-Liss, Inc.     

Hexavalent chromium induced stress and metabolic responses in hybrid willows

Metabolic responses to hexavalent chromium (Cr⁶⁺) stress and the uptake and translocation of Cr⁶⁺ were investigated using pre-rooted hybrid willows (Salix matsudana Koidz × Salix alba L.) exposed to hydroponic solution spiked with K₂CrO₄ at 24.0 ± 1°C for 192 h. Various physiological parameters of the plants were monitored to determine toxicity from Cr⁶⁺ exposure. At Cr⁶⁺ treatments of ≤2.1 mg Cr/l, the transpiration rate of plants was > 50% higher than that of the non-treated control plants. As Cr concentrations were increased further, a slight increase in the transpiration rate was also observed compared with the controls. Negligible difference in the chlorophyll contents in leaves between the treated and the non-treated control plants was measured, except for willows exposed to 1.05 mg Cr/l. The response of soluble proteins in leaves of willows to Cr treatments was remarkable. Cr-induced toxicity appeared in all treatments resulting in reduced activities of catalase (CAT) and peroxidase (POD) compared to the controls. Superoxide dismutases (SOD) activity in the leaf cells showed a positive increase after Cr exposure. Of all selected parameters, soluble proteins in leaves were the most sensitive to Cr⁶⁺ doses, showing a significant linear correlation negatively (R ² = 0.931). Uptake of Cr⁶⁺ by willows grown in flasks was found to increase linearly with the added Cr⁶⁺ (a zero order kinetics), as indicated by the high R ² (0.9322). Recovery of Cr in different parts of plant materials varied significantly with roots being the dominant site of Cr accumulation. Although the translocation to shoots was detected, the amount of Cr translocated to shoots was considerably small. The capacity of willows to assimilate Cr⁶⁺ was also evaluated using detached leaves and roots in sealed glass vessels in vivo. Uptake of Cr by roots was mediated possibly through an active transport mechanism, whereas the cuticle of leaves was the major obstacle to uptake Cr from the hydroponic solution. In addition, both cysteine and ascorbic acid showed a remarkable potential to reduce Cr⁶⁺ at a neutral pH. Results indicated that the added Cr did not cause deleterious effects on plant physiological functions over a 192-h period of exposure. Significant removal of Cr from the hydroponic solution was observed in the presence of hybrid willows. The data also suggest that phytoremediation of Cr⁶⁺ is possible and ecologically safe due to the minor translocation of Cr to aerial tissues.     

镍铬合金烤瓷修复体拆除前后患牙龈下菌群的变化

背景：目前有关镍铬合金烤瓷修复体对龈下菌群影响的研究还较少。目的：探讨镍铬合金烤瓷修复体对龈下菌群构成比的影响。方法：选择因怀疑镍铬合金烤瓷修复体影响健康而要求拆除原修复体的烤瓷牙患者9例（患牙12颗）,于镍铬合金烤瓷烤瓷修复体拆除前、拆除后1个月、拆除后3个月时,采用变性梯度凝胶电泳法检测镍铬合金烤瓷修复体基牙及对侧同名天然牙的龈下菌斑。结果与结论：修复体拆除后1,3个月,患牙龈下菌斑的变性梯度凝胶电泳图谱与拆除前相比均发生了明显变化,而且拆后3个月与拆后1个月相比也发生了较明显变化;此外,选择在修复体拆除前龈下菌斑中经常出现而在拆除后消失或减弱的变性梯度凝胶电泳图像中一些特异性条带作16S rDNA片段的序列分析,结果显示这些特异条带的基因序列分别与啮蚀艾肯菌、直形弯曲菌和隐藏优杆菌有着较高的序列相似度。结果表明镍铬合金烤瓷修复体导致了修复基牙龈下菌群组成的变化,并且导致了部分牙周可疑致病菌构成比增加。     

Comparison of long-term clinical outcomes after the second-generation cobalt–chromium sirolimus-eluting stents implantation in diabetic versus non-diabetic patients: a subgroup analysis from the prospective FOCUS registry

Background: Diabetes mellitus (DM) was broadly acknowledged as a risk factor for adverse events after coronary stent implantation. However, the role of DM in patients treated with second-generation cobalt–chromium sirolimus-eluting stents (CoCr-SES) was less known. Methods: A total of 4720 patients available for 3-year follow-up in the prospective FOCUS registry were subdivided into the DM group and the non-DM group to assess the effect of DM on the clinical outcomes after CoCr-SES implantation both before and after propensity score matching. Results: The rates of major adverse cardiovascular event was low (<10%) in both DM and non-DM groups but significantly greater in the DM group after matching (9.6% versus 6.1%; p?=?0.005). Although the soft endpoints including target vessel revascularization (2.3% versus 2.3%; p?=?0.938) and target lesion revascularization (1.2% versus 1.1%; p?=?0.828) was not significantly different between two groups, the hard endpoints represented by cardiovascular death or myocardial infarction (7.3% versus 5.3%; p?=?0.012) demonstrated a significant increase in the DM group. Conclusions: This subgroup analysis demonstrated that DM significantly increased the risk of adverse events after implantation of CoCr-SES, but the general safety and efficacy performance of CoCr-SES in both diabetic and non-diabetic patients was satisfying and comparable with other types of new-generation drug-eluting stents.

• Key messages

• The overall rate of adverse clinical events in both diabetic and non-diabetic patients was <10%, indicating a satisfying long-term safety and efficacy performance of CoCr-SES, even in high–risk diabetic patients.

• DM significantly increased the risk of MACE (HR 1.3; 95% CI: 1.0–1.6) in patients undergoing CoCr-SES implantation.

     

动脉粥样硬化性脑梗死患者血清铬与胰岛素抵抗的关系

目的 探讨脑梗死患者体内血清铬与胰岛素抵抗的关系.方法 受试对象分为两组,动脉粥样硬化性脑梗死(ACI)组和正常对照组,每组30例;分别检测空腹和早餐后2 h血糖和血清胰岛素水平,并计算胰岛素抵抗指标(IRI);采用二苯碳酰二肼比色法测定血清铬含量.结果 两组患者体内铬含量、IRI均存在着显著性差异(P＜0.05,P＜0.001),这两指标呈负相关(r=-0.576),结论 ACI患者体内存在着胰岛素抵抗,微量元素铬的缺乏可引起ACI患者体内IR的发生.     

高效液相色谱法测定海福胶囊吡啶酸铬含量

目的 :建立高效液相色谱法测定海福胶囊中吡啶酸铬的含量。方法 :以甲醇 - 0 0 2mol·L-1磷酸二氢钾(15∶85 )为流动相 ,于 2 6 5nm波长处以外标法测定。结果 :线性范围 1～ 10 μg·mL-1。在此范围内 ,浓度与峰面积线性关系良好 (r=0 9995 )。吡啶酸铬的平均回收率为 99 1% ,RSD为 0 2 2 % (n =5 )。结论 :本法灵敏、准确、快速、简便     

Deaths and tumors among workers grinding stainless steel

This study examined a cohort of 1,164 males who, during the period 1927-1981, had been employed for 3 months or more in an industry that produced objects from stainless steel. These workers were exposed to the dust of grinding materials, grinding agents, and stainless steel. From 1975 to 1980, measurements of the total dust in the workroom air have shown levels of about one mg/m3 (consisting of chromium at about 0.1 mg/m3 and nickel at about 0.05 mg/m3) during grinding and several mg/m3 (chromium at about 0.01 mg/m3 and nickel at about 0.005 mg/m3) during polishing. Before 1950, the concentrations were probably considerably higher. Compared to a local reference population, a decrease in mortality (63 observed deaths, standardized mortality (SMR) = 0.79, 95% confidence limits CL = 0.61, 1.01) took place during the 1951-1983 observation period among 318 subjects who had been employed for at least five years, allowing a latency period of at least 20 years. Mortality from cancer of the colon/rectum increased (observed deaths = 6, SMR = 2.47, CL = 0.97, 5.58). The mortality from nonmalignant pulmonary disease did not increase (SMR = 0.29, CL = 0.01, 1.81). During the observation period (1958-1983), there was no significant overall excess of tumors (observed cases = 33, standardized morbidity [SMR] = 1.09, CL = 0.76, 1.54). However, tumor morbidity of the colon/rectum (observed 11, SMR = 2.83, CL = 1.47, 5.19) significantly increased. There were no cases of respiratory cancer (expected 4.7, CL = 0, 0.21). Thus, the results indicate an increased risk of intestinal cancer.(ABSTRACT TRUNCATED AT 250 WORDS)     

铬、鱼油对肥胖模型大鼠瘦素和胰岛素的影响

目的铬、鱼油参与并调节糖、脂肪代谢,选择铬、鱼油作为影响因素,观察其对饮食诱导肥胖大鼠的影响。方法将肥胖模型大鼠按体重随机分为4组,每组8只。分别为肥胖组、鱼油组、鱼油+铬组和铬组,另设基础对照组。在实验的第0周和第6周空腹采尾血,测定血清瘦素和胰岛素水平。结果3个实验组的胰岛素和瘦素水平在第0周时,与肥胖组差异无显著性(P>0.05),第6周时,显著低于肥胖组(P<0.05)。结论结果提示铬、鱼油有缓解肥胖大鼠高胰岛素和高瘦素水平的作用。