Distribution of the [3H]-label from low doses of radioactive ochratoxin a ingested by rats,and evidence for DNA single-strand breaks caused in liver and kidneys

The distribution of a single low dose of [³H]ochratoxin A (OTA) in different tissues of male Wistar rats, after administration by intubation, was investigated after 5 h, 24 h and 48 h. This dose corresponds to concentrations encountered in naturally contaminated feed (4 ppm). The distribution of [³H]-label varied with the time elapsed after administration; at 5 h the highest specific label was found in the stomach contents and in decreasing order in: intestinal contents, lung, liver, kidney, heart, fat, intestine, testes, and the lowest in muscles, spleen and brain. With exception of brain, fat, stomach and lung, all tissues showed maximum levels at 24 h, after which time the label decreased steadily, whereas in fat it increased.After a 12-week feeding experiment, with doses of 288.8 g/kg corresponding to an intake of 4 ppm in feed each 48 h, the DNA in liver and kidneys was investigated for damage. By the alkaline elution method combined with micro-spectrofluorimetric determinations of DNA, evidence for DNA single-strand breaks was obtained. These findings support reports on the carcinogenic action of OTA.     

Optimum support properties for protein separations by high-performance size exclusion chromatography

Optimum chromatographic properties of high performance size exclusion chromatography (HPSEC) of proteins, such as resolution, molecular weight accuracy and recovery, are obtained on packings and columns with tailor-made physical and chemical structures, employed at properly adjusted eluent compositions and operation conditions. SEC-theory suggests that a broad molecular weight fractionation range and high linearity of the log-linear calibration plot can be achieved by the use of two packings (10- and 80-nm pore size, characterized by a pore-size distribution (psd) equal to or less than 1 decade and by equal internal column porosity (p)), rather than a single 30- to 50-nm pore-size packing with a wide psd. Favourably high-phase ratios of (p)/(o)/ 1.0 for HPSEC columns were accomplished with a minimum interstitial column porosity (o) and a high value for the internal column porosity (p) (the specific pore volume, nu(p), multiplied by the packing density, varrho(p).) Ligands such as diol, N-acetoxyamino and oligomeric ether with a propyl- or propoxy-spacer bonded to the silica at the highest density appear to provide high mass recovery and bioactivity as well as chemical stability. Such packings, available in 3-5 mum particle size ranges of narrow distribution, packed into columns 6 mm i.d. and 500 mm in length, offer the best compromise with respect to resolution, speed and pressure drop. More careful studies are required to explain the effects of protein conformational changes and interconversions during elution on HPSEC columns.     

Concentration andpH dependent steady-state volume of distribution of methotrexate estimated by a simple physiologically based method

The effects of plasma concentration and pH on the steady-state volume of distribution, V_ss,of methotrexate (MTX) were studied in five conditioned male beagle-mongrel dogs. Steady-state plasma MTX concentrations of approximately 1, 20, and 100g/ml were targeted for by i.v. bolus doses followed by i.v. infusions. An isotonic solution of sodium bicarbonate or ammonium chloride was simultaneously infused for the purpose of inducing plasma pH change, while the infusion of an isotonic solution of sodium chloride served as a control. Plasma and urine concentrations of MTX were quantitated by a sensitive high-performance liquid chromatographic method, and the V_ss of MTX was estimated by a recently reported physiologically based method of Chiou and Lam. Statistically significant (p<0.05) concentration and plasma pHdependent V_ss of MTX were observed. Concentration dependence of V_ss was noted in sodium chloride and ammonium chloride infused dogs, but not in bicarbonate treated dogs. There was an average 50.0 and 44.8% increase in V_ss at 1 g/ ml relative to the two higher concentrations (20 and 100 g/ ml) for dogs treated with ammonium and sodium chloride, respectively. However, V_ss of MTX at the targeted concentrations of 20 and 100 g/ml was relatively constant. Plasma pHdependence of V_ss was observed only at the plasma concentration of 1 g/ml, and on the average, ammonium chloride and sodium chloride treatments resulted in 50.0 and 31.3% higher V_ss,respectively, when compared with the bicarbonate treatment. These phenomena appear to be adequately explained by the reported tissue uptake kinetics of MTX.This research was supported in part by a grant from the National Cancer Institute, CA-29754.Abstracted from a dissertation submitted in 1984 by Chung Y. Lui to the Graduate College, University of Illinois at Chicago, in partial fulfillment of Doctor of Philosophy Degree requirements.     

SARS-CoV-2 Aerosol Exhaled by Experimentally Infected Cynomolgus Monkeys

We analyzed size of severe acute respiratory coronavirus 2 (SARS-CoV-2) aerosol particles shed by experimentally infected cynomolgus monkeys. Most exhaled particles were small, and virus was mainly released early during infection. By postinfection day 6, no virus was detected in breath, but air in the isolator contained large quantities of aerosolized virus.     

成年手术患者手术部位多重耐药菌感染及影响因素分析

目的 探讨手术部位多重耐药（MDRO）菌感染情况及危险因素,为手术部位感染的预防和治疗提供循证参考。方法 以2019—2020年焦作市某医院行手术治疗的成年患者作为研究对象,收集基本情况、疾病患者情况,从医院病历信息系统中调取患者手术及术前相关检测指标、用药情况等内容,对出现发热、切口红肿、引流液异常等疑似感染症状体征患者采集感染部位生物样本用于病原学培养及检测。采用描述流行病学分析方法对MDRO菌感染情况进行分析,并采用单、多因素分析方法对MDRO菌感染影响因素进行分析。结果 7 820例进行手术治疗患者共发生MDRO菌感染250例,感染率为3.20%,其中金黄色葡萄球菌感染6例,鲍曼不动杆菌感染14例,铜绿假单胞菌感染29例,肺炎克雷伯菌感染34例,大肠埃希菌感染167例。多因素Logistic回归分析显示,糖尿病（OR=3.578）、肿瘤（OR=4.135）、贫血（OR=4.701）、入住ICU（OR=5.045）、脏器穿孔（OR=2.414）、切口分类为Ⅱ或Ⅲ类（OR=2.284、3.013）、手术有风险（OR=5.135）、抗菌药物应用≥2种（OR=2.340）、抗菌药物疗程≥5 d（OR=4.759）、再手术（OR=2.036）是成年手术患者发生MDRO菌感染的危险因素。结论 成年手术患者手术部位MDRO菌感染较为常见,相关危险因素较多,临床可根据以上因素加强围手术管理,减少MDRO菌感染的发生。     

广州市大气PM2.5中多环芳烃的现状及分布情况

目的 了解广州市大气PM_2.5中多环芳烃在不同时间、不同地区内的分布特征。 方法 于2018年在广州市越秀区(市区),从化区(农村)和番禺区(市郊)采集PM_2.5有效样品252份,用高效液相色谱法测定样品中16种多环芳烃的浓度,以分析不同地区、不同时间及季节间的分布特征和变化趋势。结果 广州市大气PM_2.5中16种多环芳烃均有检出,但质量浓度处于较低水平,年均值为(4.907±3.642)ng/m³。PM_2.5及多环芳烃的质量浓度呈现明显的季节性波动,表现为冬春季较高,夏秋季较低,不同季节差异有统计学意义(F=3.624～72.439,均P<0.05)。市区为(54.321±35.106)μg/m³,农村地区为(46.298±25.933)μg/m³,市郊PM_2.5的质量浓度为(51.821±30.033)μg/m³,差异无统计学意义(F=1.513,P>0.05),多环芳烃中萘、苯并[a]芘、二苯并[a,h]蒽、茚并[1,2,3-cd]芘的污染水平在不同地区之间差异有统计学意义(F=4.428～6.422,P<0.05),农村高于市区和市郊。结论 广州市大气PM_2.5中多环芳烃污染水平较低,呈现明显的季节性波动和城乡差别。     

手术绝经对身体脂肪分布影响的研究

目的：探讨手术绝经对身体脂肪分布的影响。方法：手术绝经者32例,进行术前及术后6个月的自身比较。用双能X线吸收仪（DEXA）测定体脂肪量、躯干脂肪量及下肢脂肪量,并计算体脂肪率、躯干脂肪量／下肢脂肪量比（T／L）、上半身型的百分比。结果：手术绝经者术后6个月下肢脂肪量明显低于手术前（P＜0．05）,T／L明显高于手术前（P＜0．01）,手术前后的上半身型各占19．4％和36．6％。结论：手术绝经也可能会使身体脂肪分布向上半身型移行,且最初可能是下肢脂肪量的减少。上半身型脂肪分布会引起一系列代谢合并症,应引起高度重视。     

肝毒性中药及其与药性和有效成分的关系——对55种中药肝毒性文献资料的分析报告

目的 :研究有关文献资料中中药肝毒性的报告及其与四气、五味、归经、有效成分之间的关系。方法 :应用文献研究方法 ,对 55种具有肝毒性的中药进行统计归类分析研究。结果 :中药四气、五味、归经及其有效成分与肝毒性有一定相关性。肝毒性主要集中在寒、热类 ,苦、辛类 ,归肝、脾、肾经类和有效成分中碱、甙类药物方面。结论 :中药药性理论及有效成分均与肝毒性有一定的关系 ,应用归类分析的方法对文献资料进行分析研究是中药毒性研究中确实可行的方法。     

人类鱼际肌的肌纤维型分布

取 5例 (男 4 ,女 1) ,2 1～ 37岁 ,死亡后 12h内的人体两侧手鱼际肌组织 50块 ,用肌球蛋白ATP酶法 ,系统研究了各肌的肌纤维型分布。结果表明 :人类鱼际肌中I型 (慢缩 )纤维的平均百分率在 59%～ 67%之间 ,平均为 62 %显著高于上肢其它各肌群I型纤维的平均百分率 (P<0 0 5)。鱼际肌的深、浅层间 ,多数肌I型纤维百分率接近。左、右侧别比较 ,除拇收肌横头右侧者显著高于左侧外 ,其余肌均未见显著的I型纤维侧别差异 ,结合肌电图和拇指功能 ,对这些差异的意义进行了分析讨论     

我国男性青年人体质量的分布

目的　探讨我国男性青年人体质量的几何分布。方法　采用CT 图像分析法对 5 0例 18～ 2 3岁我国男性青年进行了全身CT横断层扫描、影像分析和测算。结果　获得了样本各环节的质量数据 ,与国外有关数据比较 ,整体质量最大绝对误差为 2 .94kg ,平均绝对误差为 0 .88kg ;最大相对误差为 5 .0 0 % ,平均相对误差为 0 .34 %。结论　为建立我国男性青年人体惯性参数模型奠定了基础。