Continuous ambulatory electrocardiography among workers exposed to methylmethacrylate

Summary Methylmethacrylate (MMA), a widely used monomer in the manufacture of acrylic polymers, has been reported to cause cardiac troubles in industrial workers. The effects of MMA on the heart was assessed by continuous ambulatory electrocardiographic records. The study was performed in 22 occupationally exposed workers and in 18 healthy controls. Our study did not support the hypothesis that MMA is responsible for cardiomyodystrophy. However, supraventricular and ventricular ectopic beats were significantly more frequent among exposed workers versus controls (P < 0.01). Moreover, repolarization changes such as large T waves were noted only in exposed workers (eight cases against none in the control group). Although there was no clear connection between MMA exposure and the recorded cardiac changes in the exposed group, the role of MMA cannot be totally excluded.     

Encapsulation of aluminium hydroxide fillers with polymethyl-methacrylate

A process was developed for the microencapsulation of inorganic filler particles with poly-methyl-methacrylate, to increase the interaction between the hydrophilic filler particles and a polymer matrix. The filler utilised was aluminium hydroxide with an average diameter of 1.9 µm and a specific surface area of 5 m2/g. The process comprised a surface modification, in which a monolayer of isopropoxy titanium isostearate was chemically bound to the surface to render it hydrophobic and to ensure a chemical bond between the filler and the organic phase. Then, an encapsulation reaction was carried out by means of an emulsion-like polymerization process at monomer starved conditions. The modified particles were stabilized in water with sodium-dodecyl-sulphate. A redox system consisting of cumene-hydroperoxide in combination with sodium-formaldehyde-sulphoxylate and iron(II) salt was applied for the initiation of the polymerization. Besides surface polymer, free polymer particles were also formed. The parameters which varied were the filler concentration, the concentration of the initiator components and the surfactant concentration. At optimum conditions, ~50% of the added monomer polymerized at the modified filler surface, thus forming encapsulated filler particles. SEM together with TGA analysis indicated that a smooth polymer layer had been formed on the filler surface. At high filler loading, however, coagulation occurred.     

无重复吸入通气防治骨水泥反应的临床研究

目的探讨无重复吸入通气对骨水泥反应的防治作用。方法将30例在全麻下行人工股骨头置换术的老年病人随机分为处理组和对照组,处理组在研究期内实施无重复吸入通气,而对照组施行紧闭通气,记录填充骨水泥前、后BP、HR、PaO2和PaCO2等的数值和发生心律失常、血压下降(收缩压低于基础值的20%)的例数。结果处理组PaCO2和血压下降的例数少于对照组,其余指标两组间比较无显著性差异。结论无重复吸入通气对骨水泥反应有一定的防治作用。     

甲基丙烯酸甲酯单体对A549肺癌细胞的不良反应

目的 观察甲基丙烯酸甲酯(MMA)单体对A549肺癌细胞的不良反应.方法 设置实验组(5个单体浓度组:1、10、40、80、120 mg/L)及阴性对照组,用噻唑蓝(MTT)比色法测定单体与A549肺癌细胞接触后30 min、1、3、5d细胞吸光度(A)值.用膜联蛋白V/碘化丙锭(Annexin V/PI)双染法检测接触单体1d后细胞凋亡、坏死百分比.结果 10mg/L组5 d以及40、80、120 mg/L组1、3、5d的A值与对照组比较差异均有统计学意义(P＜0.05).10、40、80、120 mg/L组细胞凋亡百分比分别为(1.78±0.09)％、(3.97±0.22)％、(4.58±0.36)％、(5.27±0.14)％,坏死百分比分别为(3.43±0.08)％、(6.70 ±0.21)％、(7.93±0.40)％、(9.51±0.64)％,较对照组凋亡及坏死百分比(1.14±0.08)％、(1.24±0.09)％差异有统计学意义(P＜0.05).结论 MMA单体对A549肺癌细胞有毒性作用.     

Cardiac effects of methylmethacrylate in the rat heart-lung preparation with or without volatile anesthetics

We have assessed the deleterious effects of methylmethacrylate (MMA) on cardiac function and metabolism in the isolated heart-lung preparation with or without volatile anesthetics. Wistar rats were prepared for the heart-lung model. They were randomly divided into 5 groups as follows. (1) Control (C) group. (2) Cement (M) group; they received MMA. (3) Halothane (H) group; they received MMA and 1% halothane. (4) Isoflurane (I) group; they received MMA and 1.5% isoflurane. (5) Sevoflurane (S) group; they received MMA and 2.5% sevoflurane. MMA 1000 μg/ml was administered 7 min after the start of perfusion except in the C group. At the end of the experimental period, the hearts were freeze-clamped and then myocardial high energy phosphates, lactate and glycogen were measured. Cardiac output in all groups but C group decreased significantly. PO₂ of the perfusion blood in the M, H, I and S groups was significantly lower than that in the C group. Myocardial ATP in the M, H, I and S groups was significantly lower than that in the C group. ADP and AMP in the M, H, I and S groups were higher than those in the C group. There were no significant differences in lactate and glycogen levels between the 5 groups. MMA 1000 μg/ml is much higher than the blood level (0.05–31.89 μg/ml) which was reported in clinical patients who had femoral prosthesis. Therefore, the direct contribution of MMA itself to cardiac depression may be less than the other factors such as embolism in clinical situations. Volatile anesthetics did not influence the deleterious effects of MMA on cardiac function and metabolism.     

Renal dysfunction after total knee replacement is not aggravated by bone cement

Background : Total knee replacement (TKR) has been associated with postoperative renal dysfunction. The use of monomeric methylmethacrylate (MMA) bone cement causes hypotension by several mechanisms.
Methods : In 30 patients undergoing TKR with (n=16), or without (n = 14) bone cement , serum levels of creatinine, cystatin C and creatine kinase (CK) and urinary levels of creatinine and markers for glomerular (albumin, IgG) and tubular (protein HC) function were recorded preoperatively and on days 1, 2, 4 and 8 postoperatively.
Results : There were no changes in serum creatinine. Both groups had a transient, 5-fold rise in CK and a continuous increase in cystatin C. The urinary concentration of proteins increased postoperatively with a peak in the glomerular markers on day 1 and in the tubular marker on day 2. There were no significant differences in proteinuria between the groups. The 95% CIs for the difference in the means of the AUCs of the logarithmically transformed values for the proteins were never more than 19%. On day 8 all proteins had returned to their preoperative levels.
Conclusion : Postoperatively, there was a transient increased leakage of proteins, indicating glomerular and tubular dysfunction. This was not influenced by the use of MMA bone cement.     

甲基丙烯酸甲酯对酿酒酵母D61.M的遗传毒性

甲基丙烯酸甲酯(MMA)是合成有机玻璃的单体,对人体有一定的毒性。我们对酿酒酵母D61.M 菌株按冰浴测试程序测定了MMA 的遗传毒性,结果表明,MMA 可以诱发酵母有丝分裂过程中的染色体丢失。但在同样条件下,它对有丝分裂过程中的染色体交换却没有明显作用。说明MMA是染色体畸变诱导剂,并可能有神经毒性。     

骨粘固剂在骨科临床的应用

本文报告自1983年以来应用TJ骨粘固剂作为内固定的增强剂对31例包括五种不同类型的损伤或疾病的治疗经验。其中有股骨颈骨折12例,胸腰椎骨折伴截瘫10例,髌骨骨折1例及骨肿瘤和脊柱结核各4例。有关手术名称摘列于表2。这种固定方法简便易行,固定可靠。所有病人除1例外,均达到了减轻疼痛、方便护理和有利于早期离床活动等目的。并且避免了由于病人长期卧床所引起的一系列并发症。     

甲基丙烯酸甲酯对蟾蜍神经动作电位传导的影响

目的研究甲基丙烯酸甲酯溶液对蟾蜍离体坐骨神经动作电位传导的影响。方法制备蟾蜍离体坐骨神经标本,随机将标本分为4组:任氏液对照组,0.01%、0.1%和1%甲基丙烯酸甲酯溶液组。采用BL-420生物信号采集系统记录标本动作电位的振幅和传导速度。结果蟾蜍坐骨神经动作电位振幅为(5.28±0.16)m V,传导速度为(15.63±0.47)m/s。给药后0.01%组的振幅在第3~15分钟时出现"高台期",最终降至(2.53±0.21)m V,传导速度在第10分钟开始下降,实验结束时为(8.06±0.77)m/s。0.1%组在第1~15分钟为"高台期",但最终降至(1.88±0.14)m V,传导速度在第5分钟下降,实验结束时为(2.81±0.51)m/s。1%组在试验结束时振幅为(1.37±0.12)m V,传导速度在第2分钟下降,实验末为(2.73±0.43)m/s。结论甲基丙烯酸甲酯溶液可以降低神经动作电位振幅及传导速度。中低浓度的甲基丙烯酸甲酯可以在短时间内提高动作电位振幅,但长时间作用于神经仍会减弱振幅,高浓度溶液则不会出现振幅升高的现象。甲基丙烯酸甲酯对神经传导的影响可能是经皮椎体成形术(PVP)手术止痛的原因之一。