The Trend Towards Implementing the Precautionary Principle in us Regulation of Nanomaterials

The precautionary principle provides a framework for regulating emerging technologies in general and nanomaterials in particular. It counsels action in the presence of uncertainties about risk instead of assuming that nanomaterials are safe unless proven hazardous. Nanomaterials are regulated under different statutory programs depending on whether they are drugs, pesticides or other commercial chemicals. Recent developments in the regulation of nanomaterials that are not drugs or pesticides have demonstrated a trend towards application of the precautionary principle. This is a paradigm shift away from the requirement built into past interpretations of the Toxic Substances Control Act ("TSCA") that manufacturing, processing and use of chemical substances cannot be restricted unless the regulatory authority proves an unreasonable risk. This same paradigm shift is incorporated into recent legislative proposals to amend TSCA.     

腹腔镜与超声刀对小儿长段型先天性巨结肠的临床疗效观察

目的探讨腹腔镜与超声刀在治疗小儿先天性巨结肠的临床作用和安全性。方法毫州市人民医院普外二科2008年1月—2011年1月11例长段型先天性巨结肠患儿,所有患儿均使用全麻气管插管,在患儿腹壁做3个孔作为进镜孔以及腹腔镜的其他操作程序。在腹腔镜直视下使用超声刀将发生病变的直肠游离出来,同时游离近端直肠系膜到骨盆底部。转入会阴手术,在肛门齿状线上5mm处将直肠黏膜切开,逐渐将直肠黏膜向上分离直到腹膜反折处,然后继续将直肠肌鞘切断,将保留的直肠肌鞘后鞘切开,直肠分离至腹腔内直肠游离处,将正常的结肠取出与齿状线原切口上缘相缝合。结果11例患儿的手术时间115—235min。平均手术时间（175±18）min,术后所有患儿均顺利排气排便,无肠梗阻症状发生。结论腹腔镜与超声刀在治疗小儿先天性巨结肠的临床效果理想,创伤小、不良反应少,临床上建议进一步推广。     

Assessment of PCBs exposure in human hair using double focusing high resolution mass spectrometry and single quadrupole mass spectrometry

Polychlorinated biphenyls (PCBs) levels were assessed in human hair samples, originating from two main agricultural regions of Greece. The analysis was performed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-double focusing high resolution mass spectrometry (GC-DFHRMS). The main analytical procedure involved hair decontamination, solid-liquid extraction and cleanup steps. The recoveries of PCBs ranged from 71.2% to 101.6%, with accuracies greater than 87.5% and the between-run precisions (%RSD) lower than 25% for all analytes. Differences in the frequencies of detection and the median values of PCBs were detected between the examined regions and between the applied analytical techniques. All Peloponnesus' hair examined samples were found positive for each examined PCB, while the percentage of the total positive samples ranged from 86.1% (for PCB 138) to 94.4% (for PCB 28 and 153 congeners) using GC-DFHRMS. The Cretan hair samples were less contaminated (SUM PCBs=0.61 and 1.47pg/mg) unlike the Peloponnesus' samples (SUM PCBs=24.68 and 38.74pg/mg) measured by GC-DFHRMS and GC-MS, respectively. PCBs with high chlorination gave lower concentration values compared to low chlorination PCBs in both populations. No significant differences were observed between women and men. The GC-DFHRMS technique provided higher percentage of positive samples and low PCBs median values, due to higher sensitivity and interferences from isobaric ions in the GC-MS technique and is therefore considered as a powerful tool for such assessments in hair specimens.     

异甘草酸镁治疗中毒性肝炎疗效观察

目的 观察异甘草酸镁治疗中毒性肝炎的疗效.方法 160例临床确诊为中毒性肝炎住院患者完全随机分为观察组和对照组,各80例.2组均常规给予维生素及氨基酸类等药物治疗,观察组在此基础上给予异甘草酸镁注射液150 mg静脉滴注,对照组在此基础上给予还原型谷胱甘肽注射液1.8g静脉滴注,1次/d,疗程均为4周.观察2组患者的症状改善情况、肝功能及不良反应.1个月后治疗无效者换用其他治疗.结果 观察组乏力好转率95.0％(76例),好转时间10(5～15)d;对照组分别为86.2％(69例)、18(14 ～22)d.观察组消化道症状好转率93.8％(75例),好转时间12(8～16)d;对照组分别为83.8％(67例)、21(16 ～26)d.观察组ALT好转率97.5％(78例),好转时间15(10～20)d;对照组分别为88.8％(71例)、25(20 ～30)d.观察组血清总胆红素好转率96.2％(77例),好转时间14(9 ～ 19)d;对照组分别为87.5％(70例)、23(18 ～28)d.观察组乏力、消化道症状、ALT、总胆红素好转率和好转时间均明显优于对照组,差异均有统计学意义(均P ＜0.05).观察组显效58例(72.5％),有效18例(22.5％),总有效率95.0％(76例),对照组显效50例(62.5％),有效19例(23.8％),总有效率86.3％(69例).观察组总有效率明显高于对照组,差异有统计学意义(P＜0.05).2组均无明显不良反应.结论 异甘草酸镁治疗中毒性肝炎的疗效优于还原型谷胱甘肽.     

The relevance of animal models in multiple sclerosis research

Multiple Sclerosis (MS) is a complex disease with an unknown etiology and no effective cure, despite decades of extensive research that led to the development of several partially effective treatments. Researchers have only limited access to early and immunologically active MS tissue samples, and the modification of experimental circumstances is much more restricted in human studies compared to studies in animal models. For these reasons, animal models are needed to clarify the underlying immune-pathological mechanisms and test novel therapeutic and reparative approaches. It is not possible for a single mouse model to capture and adequately incorporate all clinical, radiological, pathological and genetic features of MS. The three most commonly studied major categories of animal models of MS include: (1) the purely autoimmune experimental autoimmune/allergic encephalomyelitis (EAE); (2) the virally induced chronic demyelinating disease models, with the main model of Theiler's Murine Encephalomyelitis Virus (TMEV) infection and (3) toxin-induced models of demyelination, including the cuprizone model and focal demyelination induced by lyso-phosphatidyl choline (lyso-lecithine). EAE has been enormously helpful over the past several decades in our overall understanding of CNS inflammation, immune surveillance and immune-mediated tissue injury. Furthermore, EAE has directly led to the development of three approved medications for treatment in multiple sclerosis, glatiramer acetate, mitoxantrone and natalizumab. On the other hand, numerous therapeutical approaches that showed promising results in EAE turned out to be either ineffective or in some cases harmful in MS. The TMEV model features a chronic-progressive disease course that lasts for the entire lifespan in susceptible mice. Several features of MS, including the role and significance of axonal injury and repair, the partial independence of disability from demyelination, epitope spread from viral to myelin epitopes, the significance of remyelination has all been demonstrated in this model. TMEV based MS models also feature several MRI findings of the human disease. Toxin-induced demyelination models has been mainly used to study focal demyelination and remyelination. None of the three main animal models described in this review can be considered superior; rather, they are best viewed as complementary to one another. Despite their limitations, the rational utilization and application of these models to address specific research questions will remain one of the most useful tools in studies of human demyelinating diseases.     

两种回流灌肠法治疗先天性巨结肠的对比研究

目的:评价先天性巨结肠(Hirschsprung disease,HD)患儿术前采用全自动灌肠机回流灌肠的安全性、有效性及舒适性,并与传统的回流灌肠法相比较,为该法广泛应用于儿科临床提供理论依据.方法:将56例先天性巨结肠(常见型)患儿随机分为试验组(全自动灌肠机行回流灌肠)和对照组(传统回流灌肠法);检测首末次灌肠后患儿血电解质、血渗透压、体重及血浆蛋白变化,收集灌肠液计数大便菌落,大年龄患儿评价灌肠舒适度,术中评价灌肠效果,统计灌肠时间、术后排便时间、住院天数及并发症发生率.结果:(1)实验组灌肠后,患儿体重及血浆白蛋白显著增加(P<0.05),灌肠液中大便菌落数显著下降(P<0.05);(2)实验组灌肠前后,患儿血电解质及渗透压无显著改变(P>0.05);(3)两组患儿在术前灌肠时间、术后自主排便时间及术后并发症发生率等方面没有显著差异(P>0.05);但实验组患儿的灌肠舒适度及术中灌肠效果明显提高,住院时间明显缩短(P<0.05 ).结论:采用全自动灌肠机行先天性巨结肠术前回流灌肠,不但操作简便,省时省力,而且舒适,安全性高,灌肠效果好,可替代传统回流灌肠法并广泛应用于儿科临床.     

医用臭氧对大鼠体外星形胶质细胞的毒性

目的 评价医用臭氧对大鼠体外星形胶质细胞的毒性.方法 Wistar大鼠12只,日龄1～2 d,麻醉下取脑,分离、培养星形胶质细胞,接种入24孔培养板,每孔1 ml,细胞浓度7 × 105/ml,分为4组(n=7):正常对照组(C组)加入无任何干预的完全培养基400 μl;不同浓度医用臭氧组(O2-O340组、O2-O360组、O2-O380组)分别加入经40、60、80 μg/ml医用臭氧干预的完全培养基400 μl,于孵育2 h(T1)、4 h(T2)时观察细胞形态,测定星形胶质细胞超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量及乳酸脱氢酶(LDH)漏出率.结果 O2-O360组与O2-O380组胞体肥大、肿胀、突起增多,胞浆内出现黑色变性颗粒及空泡样改变,核固缩细胞增多,O2-O380组更明显.与C组比较,T1时O2-O340组SOD活性和MDA含量升高,LDH漏出率降低,O2-O360组SOD活性和MDA含量升高,O2-O380组SOD活性和MDA含量升高,LDH漏出率升高,T2时O2-O340组SOD活性升高,MDA含量和LDH漏出率降低,O2-O360组SOD活性和LDH漏出率升高,O2-O380组MDA含量和LDH漏出率升高(P<0.01);O2-O340组、O2-O360组和O2-O380组T1时MDA含量和LDH漏出率依次升高,T2时SOD活性依次降低,MDA含量和LDH漏出率依次升高(P<0.01);与T1时比较,T2时O2-O340组、O2-O360组和O2-O380组SOD活性和MDA含量降低,O2-O360组和O2-O380组LDH漏出率升高(P<0.05).结论 医用臭氧对大鼠体外星形胶质细胞的毒性作用与其浓度和作用时间有关.     

Isolation and pharmacological effects of leptoxin, a novel proteic toxin from Leptodactylus pentadactylus skin secretion

The in vivo and in vitro pharmacological effects of leptoxin, one of the most lethal protein toxins known at present date (LD₅₀ 0.5 ± 0.03 μg/kg i.v., mice) isolated from Leptodactylus pentadactylus skin secretion, were studied. In rats, leptoxin (1.0 μg/kg, i.v.) induced cardiorespiratory collapse with abundant tracheal secretion followed by sudden death. The cardiovascular shock, pulmonary edema and mortality were not prevented by pretreating the animals with effective doses of pharmacological blockers, i.e., atropine with or without bilateral vagotomy, phentolamine, propranolol, hexamethonium, captopril, dexamethasone, indomethacin, L-NAME, promethazine, Ginkgolide BN-52021 or tezosentan. Pulmonary macroscopic examination revealed increased tracheobronchial secretion, hemorrhagic areas and edema. Microscopic examination showed intense vascular congestion, alveolar and septal interstitial hemorrhage and alveolar edema, without infiltrated inflammatory cells. Leptoxin increased pulmonary index (0.67 ± 0.09 vs. 1.55 ± 0.24; p < 0.05) and the Evans blue concentration in the bronchoalveolar fluid (1.24 ± 0.17 vs. 4.17 ± 1.47 μg/μL; p < 0.01) and in the lung parenchyma (40.73 ± 3.27 vs. 65.33 ± 4.51 μg/μL; p < 0.03). Leptoxin increased the pulmonary perfusion pressure from 13.7 ± 5.3 to 54.0 ± 6.3 mmHg. It also induced a vasoconstrictor effect in the perfused mesenteric vascular bed that could be explained by a hyperreactivity to phenylephrine. Thus, the results suggest that leptoxin-induced death occurs by acute pulmonary edema due to increased microvascular pulmonary pressure evoked by direct vasoconstriction. Despite its strong toxicity, the role of leptoxin in L. pentadactylus skin remains unknown.     

Glial fibrillary acidic protein and S-100 colocalization in the enteroglial cells in dilated and nondilated portions of colon from chagasic patients

After acute immunoreactive infestation with the Chagas' disease parasite, Trypanosoma cruzi, some patients develop chronic megacolon, whereas others remain asymptomatic. Chronic chagasic patients with gastrointestinal involvement exhibit inflammation and degeneration of enteric neurons. Our hypothesis is that enteric glial cells may be involved in the modulation of enteric inflammatory responses or even control the colon's dilatation. The aims of this study were to characterize the phenotype of enteric glial cells according to the expression of S-100 and glial fibrillary acidic protein and to look for correlation between these data and the neuronal loss in the colon of chagasic patients. We studied both dilated and nondilated portions of chagasic megacolon. We used a pan-enteric glial cell marker (anti-S-100), a subpopulation enteric glial cell marker (anti-glial fibrillary acidic protein), and a pan-neuronal marker (anti-Human protein C and protein D) with double-labeled sheets using a confocal microscope. Our results demonstrate that neuronal loss is similar in dilated and nondilated portions of chagasic megacolon. Moreover, the results indicate that neuronal destruction present in chagasic megacolon is preceded by glial component loss. The nondilated portion of chagasic megacolon exhibited increased expression of glial fibrillary acidic protein comparable with the dilated portion and also to the noninfected group. Our results suggest that glial fibrillary acidic protein enteric glial cells prevent dilatation of the organ and protect the enteric nervous system against the inflammatory process and neuronal destruction, preventing the destruction from expanding to unaffected areas of the colon.