Genotoxicity and physicochemical characteristics of traffic-related ambient particulate matter

Exposure to ambient particulate matter (PM) has been linked to several adverse health effects. Since vehicular traffic is a PM source of growing importance, we sampled total suspended particulate (TSP), PM(10), and PM(2.5) at six urban locations with pronounced differences in traffic intensity. The mutagenicity, DNA-adduct formation, and induction of oxidative DNA damage by the samples were studied as genotoxicological parameters, in relation to polycyclic aromatic hydrocarbon (PAH) levels, elemental composition, and radical-generating capacity (RGC) as chemical characteristics. We found pronounced differences in the genotoxicity and chemical characteristics of PM from the various locations, although we could not establish a correlation between traffic intensity and any of these characteristics for any of the PM size fractions. Therefore, the differences between locations may be due to local sources of PM, other than traffic. The concentration of total (carcinogenic) PAHs correlated positively with RGC, direct and S9-mediated mutagenicity, as well as the induction of DNA adducts and oxidative DNA damage. The interaction between total PAHs and transition metals correlated positively with DNA-adduct formation, particularly from the PM(2.5) fraction. RGC was not associated with one specific PM size fraction, but mutagenicity and DNA reactivity after metabolic activation were relatively high in PM(10) and PM(2.5), when compared with TSP. We conclude that the toxicological characteristics of urban PM samples show pronounced differences, even when PM concentrations at the sample sites are comparable. This implies that emission reduction strategies that take chemical and toxicological characteristics of PM into account may be useful for reducing the health risks associated with PM exposure.     

Increasing trend of Cesarean deliveries in HIV-infected women in the United States from 1994 to 2000

BACKGROUND: Meta-analysis and randomized clinical trial results reported in June 1998 indicated a significant reduction in perinatal HIV transmission rates among mothers undergoing a cesarean section (C-section). OBJECTIVE: The objective of this study was to examine recent trends in and factors associated with C-section deliveries among HIV-infected women in the United States. DESIGN: A multisite pediatric medical record review of a cohort of HIV-exposed and HIV-infected infants in the Pediatric Spectrum of HIV Disease (PSD) Cohort study (n = 6467) and the national Pediatric HIV/AIDS Reporting System (HARS) (n = 8,306) was conducted. SETTING/PATIENTS: All infants born between 1994 and 2000 to HIV-positive mothers referred to the PSD study or to a Pediatric HARS hospital or clinic site were enrolled. RESULTS: The proportion of deliveries by C-section was steady at about 20% from 1994 through June 1998. From July 1998 through December 2000, this proportion increased to 44% in the PSD study and to nearly 50% in the Pediatric HARS. On analysis by multiple logistic regression, delivery of infants by C-section was associated with the release of study results (OR = 2.83), delivery in four PSD sites in reference to Texas (OR: 2.02-1.43), having private medical care reimbursement (OR = 1.62), and having maternal prenatal care (OR = 1.43). CONCLUSIONS: The PSD and Pediatric HARS data demonstrate a sharp increase in C-section rates mainly among HIV-infected women in the United States after the release of the meta-analysis and randomized clinical trial results in 1998. This finding highlights the rapid impact of study results on obstetric practice. It underscores the critical role of prenatal care in offering perinatal interventions such as scheduled C-section when indicated to reduce the likelihood of HIV transmission.     

Selective inhibition by dactinomycin of NANC sensory bronchoconstriction and [125I]NKA binding due to NK-2 receptor antagonism.

In the present study, dactinomycin (10(-5) M) inhibited the non-adrenergic, non-cholinergic bronchoconstriction upon antidromic vagal nerve stimulation (1 Hz for 1 min) in the isolated perfused guinea-pig lung by 84%. The release of calcitonin gene-related peptide was unchanged, however, suggesting a postjunctional action. Dactinomycin (10(-5), 5 x 10(-5) M) also reduced non-adrenergic non-cholinergic bronchial contractions (maximally by 75%) induced by electrical field stimulation or capsaicin, while the cholinergic component and non-adrenergic non-cholinergic relaxation remained intact. The neurokinin-2 receptor antagonist L-659,877 (10(-6) M) had a similar effect as dactinomycin, inhibiting the non-adrenergic non-cholinergic bronchial contractions by 69%, while the neurokinin-1 receptor antagonist CP-96,345 (10(-6) M) had no effect. The bronchoconstriction evoked by neurokinin A, the selective neurokinin-2 receptor agonist Nle10neurokinin A (4-10) and capsaicin was markedly inhibited by dactinomycin while the contraction induced by substance P (SP), the selective neurokinin-1 receptor agonist Sar9Met(O2)11SP, endothelin-1 and acetylcholine was not affected. In autoradiographic experiments on guinea-pig lung, [125I]neurokinin A-labelled sections showed dense binding in the bronchial smooth muscle layer. Dactinomycin inhibited the specific binding of [125I]neurokinin A in a concentration-dependent manner (IC50 = 6.3 x 10(-6) M) and 66% of [125I]neurokinin A total binding was inhibited by 10(-4) M dactinomycin. In the rat colon, [125I]neurokinin A binding to neurokinin-2 sites on circular smooth muscle was inhibited by dactinomycin with an IC50 value of 7.9 x 10(-6) M. Dactinomycin failed to reduce increased nerve-evoked contractions or those caused by Nle10neurokinin A (4-10) per se in the rat vas deferens, which are considered to be mediated by neurokinin-2 receptor activation. In the rat portal vein, dactinomycin did not influence the contractions caused by the neurokinin-3 selective agonist Pro7neurokinin B. In conclusion, dactinomycin selectively inhibited neurokinin-2 receptor activation in guinea-pig lung and rat colon, but not in rat vas deferens, which may depend on the existence of different neurokinin-2 receptor subtypes. Neurokinin A is most likely the main endogenous excitatory non-adrenergic non-cholinergic transmitter in guinea-pig bronchi.     

Detecting DNA repair capacity of peripheral lymphocytes from cancer patients with UVC challenge test and bleomycin challenge test

The objective of this study was to evaluate DNA repair capacity of cancer patients with the bleomycin (BLM) challenge test and the UVC challenge test. The human peripheral lymphocytes were collected from 33 patients with different kinds of cancers and 33 controls in the same hospital. The lymphocytes of each subject were divided into two groups: (1) In the BLM challenge test, the lymphocytes were treated with BLM (20 microgml(-1)) for 30 min, and repaired for 15 min. The DNA damage before and after BLM exposure was detected with comet assay to assess DNA repair capacity. (2) In the UVC challenge test, the lymphocytes were exposed to UVC (254 nm) at the dose of 1.5 Jm(-2). DNA damage of lymphocytes was measured before UVC exposure and at 90 and 240 min after UVC exposure using comet assay, then DNA repair percentage (DRP) was calculated. The results of this study indicate that the average DRPs of cancer patients were 75.63 +/- 3.11 and 68.98 +/- 4.19% calculated with tail length (TL) and tail moment (TM), respectively, in the BLM challenge test, which were significantly lower than those (91.11 +/- 1.09 and 88.19 +/- 1.71%) of controls (P < 0.01). Also, the mean DRPs of cancer patients were 49.19 +/- 3.47 and 58.27 +/- 3.64% calculated with TL and TM, respectively, in the UVC test, which were significantly lower than those (77.52 +/- 2.06 and 83.12 +/- 2.36%) of controls (P < 0.01). The correlation between the DRPs (%) drawn with TL and TM in the BLM test or between the DRPs (%) drawn with mean TL and mean TM in the UVC challenge test were significant (P < 0.05). The DNA repair capacity measured with the BLM and UVC challenge tests in 33 cancer patients was significantly lower than that in controls.     

Roberts铜盐法测定蔗汁葡聚糖含量的热效应——淀粉对受热蔗汁葡聚糖测定的影响

作者从研究中发现:用Roberts铜盐法测定蔗汁样本葡聚糖含量时,所得结果与蔗汁的受热有关,受热蔗汁的测定值高于真实值,作者将这种现象暂称为Roberts铜盐法测定蔗汁样本葡聚糖含量的热效应。研究表明:蔗汁中的淀粉是引起热效应的重要因素。本文最后提出了一种由淀粉引起的热效应的可行校正方法。     

实验性顺铂诱导急性肾功能衰竭动物模型的研究

1目的　建立顺铂 (cisplatin,CP)诱导的急性肾功能衰竭 (acute renal failure,ARF )大鼠模型 ,探讨 ARF的发病机制。2方法　 SD大鼠静脉一次性注射 CP 6 mg/ kg,动态观察大鼠血清肌酐 (Scr)、尿素氮 (BUN)变化以及肾组织形态学改变。 3结果　对照组不同时间 Scr、BUN差异不明显 (P>0 .0 5 ) ,肾组织形态学正常。模型组 Scr、BUN第 4d较第 1d明显升高 (P<0 .0 5 )。肾组织形态学显示 ,肾脏髓质外侧带大部分肾小管坏死 ,细胞核固缩、溶解、消失 ,管腔扩张 ,有坏死脱落碎屑。 4结论　 CP诱导的大鼠 ARF模型为一较为理想的 ARF模型     

适形切除保肛术与经括约肌间切除术治疗低位直肠癌的临床疗效

目的探讨适形切除保肛术(CSPO)与经括约肌间切除术(ISR)治疗低位直肠癌的临床疗效。方法采用回顾性队列研究方法。收集2011年8月至2020年4月2家医学中心收治的183例(海军军医大学附属长海医院117例、复旦大学附属华山医院66例)低位直肠癌病人的临床病理资料;男110例,女73例;年龄为(57±11)岁。183例病人中,117例行CSPO设为CSPO组,66例行ISR设为ISR组。观察指标:(1)两组低位直肠癌病人手术情况。(2)两组低位直肠癌病人术后并发症情况。(3)随访情况。(4)影响低位直肠癌病人预后因素分析。(5)影响低位直肠癌病人肛门满意度因素分析。采用门诊、问卷和电话方式进行随访,了解病人肿瘤局部复发及远处转移、病人生存、造口还纳、肛门满意度评分情况。正态分布的计量资料以x±s表示,组间比较采用t检验;偏态分布的计量资料以M(范围)表示。计数资料以绝对数或百分比表示,组间比较采用χ²检验。等级资料比较采用秩和检验。采用Kaplan-Meier法绘制生存曲线,采用寿命表法计算生存率,采用Log-rank检验进行生存情况分析。单因素分析采用线性回归,将单因素线性回归分析中P<0.10的变量纳入多因素分析。多因素分析采用COX逐步回归分析模型和线性回归分析。结果(1)两组低位直肠癌病人手术情况:CSPO组和ISR组病人腹腔镜手术例数、手术时间、术中出血量、肿瘤远切缘、术后化疗、术后住院时间分别为44例和55例、(165±54)min和(268±101)min、(142±101)mL和(91±85)mL、(0.6±0.4)cm和(1.9±0.6)cm、76例和9例、(6.6±2.5)d和(7.9±4.7)d,两组病人上述指标比较,差异均有统计学意义(χ²=35.531,t=8.995、-3.437、-3.088,χ²=44.681,t=2.267,P<0.05)。(2)两组低位直肠癌病人术后并发症情况:CSPO组术后19例病人发生并发症,其中Ⅰ级并发症6例,Ⅱ级并发症12例,Ⅲb级并发症1例。ISR组术后14例病人发生并发症,其中Ⅰ级并发症4例,Ⅱ级并发症7例,Ⅲa级并发症1例,Ⅲb级并发症2例。两组病人术后总体并发症发生情况比较,差异无统计学意义(χ²=0.706,P>0.05)。两组病人并发症经对症支持治疗后均好转。两组病人均无围术期(术后30 d内)死亡病例。(3)随访情况:183例病人均获得随访,CSPO组和ISR组随访时间分别为(41±27)个月和(37±19)个月,两组病人比较,差异无统计学意义(t=-1.104,P>0.05)。CSPO组和ISR组病人中,肿瘤局部复发分别为2例和3例、肿瘤远处转移分别为9例和4例,两组病人上述指标比较,差异均无统计学意义(χ²=1.277、0.170,P>0.05)。CSPO组和ISR组病人3年无病生存率分别为84.0%和88.6%,3年总体生存率分别为99.0%和92.8%,两组病人无病生存情况和总体生存情况比较,差异均无统计学意义(χ²=0.218、0.002,P>0.05)。CSPO组和ISR组分别有102例和66例病人随访至CSPO或ISR术后12个月,其造口还纳率分别为92.16%(94/102)和96.97%(64/66),两组病人比较,差异无统计学意义(χ²=1.658,P>0.05)。CSPO组8例造口未还纳病人中,2例因高龄、4例主观拒绝还纳、2例因放疗致瘢痕无法还纳。ISR组2例造口未还纳病人中,术后因肝转移和主观拒绝还纳各1例。CSPO组和ISR组分别有92例和61例病人随访至造口还纳术后12个月,其中CSPO组75例和ISR组38例完成肛门功能满意度调查。CSPO组和ISR组病人肛门功能满意度评分分别为(6.8±2.8)分、(5.4±3.0)分,两组病人比较,差异有统计学意义(t=-2.542,P<0.05)。CSPO组和ISR组病人肛门功能满意度评分>5分分别为54例和21例,两组病人比较,差异无统计学意义(χ²=3.165,P>0.05)。(4)影响低位直肠癌病人预后因素分析:COX逐步回归分析结果为性别、肿瘤pT分期是影响低位直肠癌病人无病生存率的独立影响因素(风险比=2.883,1.963,95%可信区间为1.090~7.622,1.129~3.413,P<0.05);性别、肿瘤pT分期是影响低位直肠癌病人总体生存率的独立影响因素(风险比=10.963,3.187,95%可信区间为1.292~93.063,1.240~8.188,P<0.05)。(5)影响低位直肠癌病人肛门满意度因素分析:单因素分析结果显示手术方式和肿瘤分化程度是影响低位直肠癌病人肛门满意度的影响因素(偏回归系数=1.464,-1.580,95%可信区间为0.323~2.605,-2.950~-0.209,P<0.05)。多因素分析结果显示:手术方式、肿瘤分化程度、术前放疗是影响低位直肠癌病人肛门满意度的独立影响因素(偏回归系数=1.637,-1.456,-1.668,95%可信区间为0.485~2.788,-2.796~-0.116,-2.888~-0.447,P<0.05)。结论与ISR比较,低位直肠癌施行CSPO同样可实现超低位保肛,不增加术后并发症发生率,保障肿瘤学安全性,改善肛门功能,提升病人术后肛门功能满意度。     

Cr Migration Potential and Species Properties in the Soil Profile from a Chromate Production Site in the Groundwater Depression Cone Area

The relationship between the migration process and speciation distribution of Cr is important for the risk assessment in the underground environment. In this work, soil columns were collected from the chromate production site, with a 40-year operation, in the groundwater depression cone area of North China plain. The relationship between chromium pollution features and the geochemical properties of soil was established, and the migration risk of Cr(VI) was assessed based on the Nemerow composite index and Hydrus-1D model. The maximum total Cr concentration in the chromium slag dumping site reached 907 mg/kg, and that in the chromate production workshop was more than 200 mg/kg across the depth. The migration of Cr might be accelerated in the soil with abundant Mn (236–1461 mg/kg) but scarce organic matters (<?0.45%). The Hydrus simulation indicated that Cr(VI) would reach a cumulative flux of 300–729 mg/cm² after 50 years.