Effects of short-term xylene exposure on psychophysiological functions in Man

Summary Six male students were exposed to m-xylene at concentrations of 4.1–8.2 mol/1 (100–200 ppm) in an exposure chamber for several successive days, 6 h a day during two subsequent weeks to assess the effects of xylene on psychophysiological functions such as equilibrium, reaction time and critical flicker fusion. The influence on these functions by different exposure patterns constituting stable (4.1-8.2 mol/1) and periodically varying m-xylene concentrations (4.1–16.4 mol/l; 100–400 ppm) in inhaled air was also studied. During the study the subjects acted as their own controls. An inhalation exposure to m-xylene already at a concentration of 4.1 mo1/1 was observed to have a deleterious acute effect on the equilibrium and the reaction time performance of nonadapted human subjects. Adaptation to the test situation or tolerance seemed to develop against these effects over five subsequent exposure days, but the effects were again discernible in the following week, and were most pronounced when the exposure constituted peak concentrations which exceeded twofold any previous ones. In this study the effect of xylene seemed to be related to the level of xylene in the blood.     

Neurotoxicity induced by exposure to toluene

Summary The object of the present study was to evaluate, with the aid of electrophysiologic techniques, the alterations induced in the auditory nervous system by exposure to toluene in a group of rotogravure workers. From 300 workers who were apparently in good health but were professionally exposed to toluene, we selected a sample of 40 workers of normal hearing ability. They were examined with an adaptation test studied by the brainstem auditory evoked potential technique with 11 and 90 stimulus repetitions a second. The results were compared with those in a group of workers of the same age but not professionally exposed to solvents. Our study demonstrates that exposure to toluene is able to induce a statistically significant alteration in the electric responses with both 11 and 90 stimuli repetitions. This alteration can be explained as a toluene exposure-induced modification, of physiologic stimulus conduction mechanisms, even in the absence of any clinical sign of neuropathy. Furthermore, such a modification could be observed in the electric responses of the entire auditory system, from peripheral receptors to brainstem nuclei.     

Brainstem auditory evoked potentials in individuals exposed to long-term low concentrations of toluene

Brainstem auditory evoked potentials (BAEPs) were examined in 49 workers employed in a printing press, who were occupationally exposed to low concentrations of toluene for an average of 20.3 years, and in 59 subjects in a control group. In the group of exposed workers, a significant decrease was found in all wave amplitudes examined, a significant prolongation of PI wave latency, and an increased interval of interpeak latencies (P3–P5), indicating that the extramedullary and high medullary part of the auditory pathway are biologically most frequently affected by chronic exposure to low concentrations of toluene. The level of exposure to toluene in both groups was evaluated by defining the concentration of toluene in peripheral blood and the concentration of hippuric acid and ortho-cresol in urine. © 1996 Wiley-Liss, Inc.     

Cytogenetic effects of low-level exposure to toluene,xylene, and their mixture on human blood lymphocytes

Summary The present study was undertaken to investigate, both in vitro and in vivo, the genotoxic potential of short-term low-level exposure to toluene, xylene, and their mixture, for which information is limited at the present time. Five adult healthy white men were exposed for 7 consecutive hours per day over 3 consecutive days to 50 ppm toluene and 40 ppm xylene either alone or in combination in a controlled exposure chamber. Such an exposure was repeated three times at intervals of 2 weeks. Blood samples were taken before and after the termination of such exposure. Three different cytogenetic end-points were evaluated using peripheral blood lymphocytes: number of sister chromatid exchanges (SCEs), cell cycle delay, and cell mortality. No significant effects on SCEs, cell cycle delay, and cell mortality were observed following such exposure to toluene or xylene or their mixture. Similarly, exposure of human blood lymphocytes in vitro to either toluene (0–2.5 mM) or xylene (0–2 mM) or their mixture for 72 h did not result in any significant cytogenetic effects at lower concentrations, while at higher concentrations, only cell mortality was found to be significantly affected. Thus our present study indicates that simultaneous exposure to low levels (within the admissible limits) of toluene, xylene, or their mixture for a short period does not pose any potential mutagenic threat to humans.     

Effect of simultaneous exposure to toluene and xylene on their respective biological exposure indices in humans

Summary Studies that specifically address the influence of controlled human exposure to a combination of solvents on the biological monitoring of exposure are limited in number. The present study was undertaken to investigate whether simultaneous exposure of human volunteers to toluene and xylene could modify the respective metabolic disposition of these solvents. Five adult Caucasian men were exposed for 7 consecutive h/day over 3 consecutive days to 50 ppm toluene and 40 ppm xylene either separately or in combination in a dynamic, controlled exposure chamber (low-level exposure). The experiment was repeated three times at intervals of 2 weeks. In another experiment, three subjects were exposed to 95 ppm toluene and 80 ppm xylene or a combination of both for 4h (high-level exposure). The concentration of unchanged solvents in blood (B) and in end-exhaled air (EA) as well as the urinary excretion of hippuric acid (HA) and methylhippuric acids (MHAs) were determined. Simultaneous exposure to the lowest level of solvents did not alter the concentration of unchanged solvents in blood or in exhaled air (average of 3-weekly means; single vs mixed exposure at 6.5 h exposure): B-toluene, 77.1 vs 78.1 g/100 ml; B-xylene, 67.6 vs 77.8 g/100 ml; EA-toluene, 9.9 vs 9.5 ppm; EA-xylene, 5.3 vs 4.8 ppm. Similarly, mixed exposure did not modify the excretion of urinary metabolites during the 3- to 7-h exposure period: HA, 1.11 vs 1.11 g/g creatinine; MHAs, 0.9 vs 0.87 g/g creatinine. However, simultaneous exposure to higher levels did affect the concentration of unchanged solvents in blood and in exhaled air as measured at 3.5 h exposure (mean value for three subjects ± SD): B-toluene, 135.7 ± 26.7 vs 215.7 ± 34.9 g/100 ml; B-xylene, 114 ± 19 vs 127.6 ± 22.1 g/100 ml; EA-toluene, 16.6 ± 0.4 vs 20.5 ± 2.8 ppm; EA-xylene, 9.9 ± 0.6 vs 12.3 ± 1.2 ppm. Such effects were accompanied by a significant delay in the urinary excretion of HA but not of MHAs. These data suggest that there is a threshold level below which metabolic interaction between toluene and xylene is not likely to occur in humans.     

Cholinergic role in alcohol's effects on evoked potentials in visual cortex of the albino rat

Photic evoked potentials were recorded from the visual cortex of chronically implanted albino rats. Since photic evoked potential components are representations of neural pathways which are activated during photic stimulation, study of the effects of alcohol on these components may help to trace pathways which are affected by alcohol. In the present study, evoked potentials were recorded at 5, 20, and 40 min following IP injections of saline, ethanol (2.0 g/kg), physostigmine (0.6 mg/kg) or atropine (15.0 mg/kg) on separate days. Ethanol depressed the amplitudes of most evoked potential components in comparison to saline administration. Component P2, however, was increased in amplitude. Physostigmine briefly reduced the amplitude of most components, including P2. In contrast, atropine increased the amplitudes of components P1 and P2, while decreasing components N1, N2 and N3 for varying durations of time. Physostigmine pretreatment augmented the depressant effect of alcohol on the early components P1 and N1, while attenuating alcohol's influence on components P2 and P3. Pretreatment with atropine likewise further reduced the amplitudes of components P1 and N1, and produced a similar effect on component N3. Atropine, either alone or in combination with alcohol, produced approximately the same degree of enhancement of component P2. In comparison to saline values, all three agents produced reliable increases in peak latency for most of the components, with only N3 showing no effects. The amplitude data from this study suggest that ethanol's augmentation of component P2 may result, at least in part, from alterations in cholinergic functions.     

七氟烷暴露新生儿术后早期脑干听觉诱发电位的变化

目的:观察七氟烷暴露新生儿术后早期脑干听觉诱发电位的变化.方法:行胃肠手术新生儿60例,胎龄37～42周,出生体重≥2 500 9,出生后1 min和5 min Apgar评分≥8分,ASA Ⅰ或Ⅱ级,按七氟烷暴露剂量,将患儿随机均分为3组(n=20):呼气末七氟烷浓度(CET-SEV)×吸入七氟烷时间(h)≤3.3％组(S1组)、3.3％＜CET-SEV×吸入七氟烷时间(h)＜6.6％组(S2组)、CET-SEV×吸入七氟烷时间(h)组≥6.6％(S3组),同期选取符合纳入标准、未接受手术的新生儿20例作为对照组(C组,n =20).实验组以4％七氟烷行吸入诱导,术中以七氟烷维持,采用气体监护仪监测呼气末七氟烷浓度.实验组在术后48 h和7天分别测试脑干听觉诱发电位(BAEP),对照组同期测试BAEP.结果:术后48 h时七氟烷暴露组BAEP异常率为45％,主要表现为V波分化不良或消失、V波潜伏期(PL)延长、Ⅰ-V波波间期(IPL)延长,与C组比较,S2组与S3组BAEP异常率及S3组Ⅰ-V波IPL差异有统计学意义(JP＜0.05);术后7天时七氟烷组BAEP主要表现为V波PL延长、Ⅰ-V波IPL延长,与C组比较,BAEP异常率、PL及IPL差异均无统计学意义(P＞0.05).结论:吸入较大剂量七氟烷新生儿术后早期出现一过性BAEP异常.     

Visual evoked potentials in workers with chronic solvent encephalopathy

Objectives Two promising variations of visual evoked potentials (VEPs) were studied in solvent-exposed workers: the effect of a low-contrast stimulus in comparison with the usually applied high contrast, and the ability of pattern-onset VEP to reveal damage to specific visual cortical areas. In addition, we studied disturbances of a visual event-related potential (P300).Methods Thirty male patients (48±9 years of age) with solvent-induced chronic encephalopathy, and 41 controls (46±8 years) without solvent exposure, participated. Pattern-reversal checkerboards with low (11%) contrast and with high (93%) contrast between the checks were used. For onset VEPs two dedicated stimulus patterns were used. P300 was elicited with an oddball paradigm.Results At low contrast the N75–P100 peak-to-peak amplitude in the controls was 9.6±4.9 V, i.e. 57% of the amplitude at high contrast (16.3±7.2 V). In the patients the response at low contrast was only 48% of that at high contrast; the corresponding amplitudes were 7.5±3.5 V and 15.8±4.9 V. For the pattern-onset VEPs no effect of exposure was found. With regard to the P300, the patients missed more targets (average 3.6%) than did the controls (average 0.5%). Patients had a smaller P300 amplitude (8.8±4.5 V) than the controls (11.5±5.3 V), and a longer latency (390±34 ms compared to 376±24 ms).Conclusion The results point to a physiological basis for the solvent-induced decrease of visual contrast sensitivity as found by others by means of psychophysical methods. The results also suggest that the neurophysiological examination of the visual system in persons who have undergone exposure to toxins might be benefited by the addition of low-contrast stimuli.     

视听诱发电位在正常婴幼儿中的检测分析

【目的】探讨6个月～3岁正常婴幼儿听性脑干反应（auditory brainstem response，ABR）和闪光视觉诱发电位（flash visual evoked potentials，FVEP）的特点及正常值范围。【方法】对144例听力学和视力学检查正常的婴幼儿进行ABR和FVEP检测。【结果】分别得到6个月～3岁婴幼儿ABR波Ⅰ、Ⅲ、Ⅴ波潜伏期和Ⅰ-Ⅲ、Ⅰ—Ⅴ、Ⅲ-Ⅴ波间期及FVEP波N1、P1、N2波潜伏期的正常值范围，发现ABR和FVEP各波潜伏期随年龄增长有缩短的趋势；无性别和左右侧差异（P〉0．05）；ABR于1．5岁、FVEP于1岁时逐渐发育成熟。【结论】ABR和FVEP检测应用于婴幼儿听功能和视功能检查是可行的，临床应用时。应参照不同年龄段的ABR和FVEP参考值进行判断。     

飞机噪声性听力损伤的脑干听觉诱发电位及电测听方法比较

目的 对飞机噪声暴露人群同时进行脑干听觉诱发电位(Brainstem auditory evoked potentials,BAEP)及电测听检查,比较两种方法检测听力损伤的价值。方法①对60名飞机维修保养人员及120名对照人群同时用脑干听觉诱发电位及电测听方法进行听力损伤检测。②用相关性分析及主成分分析等统计方法对该两种方法检测听力损伤的价值进行比较。结果 ①职业接触人群的BAEP潜伏期值与电测听1、2、4、6、8 KHz等频率及PTA、HPTA上的听觉阈值呈正相关,且与高频听觉阈值的相关性好。②用电测听4kHz频率上的听觉阈值与BAEP的Ⅰ～Ⅴ波的峰间潜伏期做主成分分析4kHz频率上的听觉阈值的贡献率为78.9％,BAEP的Ⅰ～Ⅴ波的峰间潜伏期的贡献率为21.1％。结论 电测听方法能反映主要的听力损伤状况,BAEP数据可预测飞机噪声对听力的早期影响,作为敏感性指标,对飞机噪声危害引起的听力损伤的早期发现具有较大价值。     

0～6个月足月儿和早产儿闪光视觉诱发电位研究

【目的】研究足月儿和早产儿的闪光视觉诱发电位(flash visual evoked potentials,FVEP)特点及临床应用。【方法】应用重庆康华公司的眼多功能检查仪对91名婴儿(足月儿61名,早产儿30名)进行FVEP检测。【结果】获得足月儿和早产儿FVEP波的潜伏期和振幅正常值,及其随月龄的改变而改变的趋势。足月儿0~2、2~4、4~6个月组足月儿P1波潜伏期均值分别为181.77、153.451、32.44 ms,早产儿为213.25、184.22、166.47 ms。组间潜伏期值差异有显著性(P<0.05);比较了早产儿与足月儿FVEP各波潜伏期值的差异及矫正月龄后各波潜伏期值差异,足月儿和早产儿的主波P1出波率相对其它波稳定,且早产儿P1波的潜伏期较足月儿延长,矫正月龄后早产儿的P1波潜伏期与足月儿差异无显著性。【结论】以FVEP波的主波P1潜伏期值为参考值对小婴儿的视功能检查具有可行性;在为早产儿作视功能检查时,建议检查矫正月龄后的潜伏期值是否在正常值范围内。     

正常眼与弱视眼视觉诱发电位波形的自动判别分析

提出了一种用于判别不同类型视觉诱发电位波形的频域判别分析法，并把此法用于正常眼和弱视眼视觉诱发电位波形的判别分析。它计算诱发电波形第一至第六次谐波的幅度和相位，把这十二个参数作为判别分析的自变量，再用31只正常眼和31只弱视眼的诱发电位波形数据建立判别分析系统。临床数据检验表明，本判别分析系统可较准确地判别正常眼和弱视眼的诱发电位波形。     

Otoacoustic emissions,auditory evoked potentials,and traits related to sex and sexual orientation

A number of trait measures, possibly reflective of prenatal hormonal effects, were obtained in studies of otoacoustic emissions (OAEs) and auditory evoked potentials (AEPs) carried out with male and female heterosexual and homosexual/bisexual college students. Most of the measures were from a self-report questionnaire; others were from experimenters' ratings or cognitive tests (Mental Rotation Test and Water Level Test). The questionnaire, test, and rating measures included physical characteristics (e.g., height, body type, eye color); spatial abilities; sex roles and sexual orientation; childhood gender nonconformity; and, in the OAE study, presence of homosexuality or bisexuality among relatives. Correlations with sexual orientation were most often consistent with the hypothesis that male homosexuals were undermasculinized and female homosexuals overmasculinized. Some correlations of the questionnaire, test, and rating measures with auditory measures were observed, but most of these were reduced or eliminated by statistically controlling for sex. In supplementary analyses, pigmentation measures appeared to be unrelated to OAEs, and data relevant to several hypotheses in the sexual orientation literature were briefly examined, including childhood gender nonconformity, X-linkage, handedness, and the tendency of homosexuality to run in families.     

Visual evoked potentials in rubber factory workers

Pattern reversal visual evoked potentials (pVEP) were studiedin 39 male rubber factory workers in the age range of 18–55years and 20 control subjects (aged 18–46 years) not exposedto the rubber factory environment. Results revealed that 20(51%) rubber factory workers had abnormal latencies of waveP₁ (dominant component of pVEP) as per accepted criteria of99% tolerance limit set for the control group (i.e. any valueabove mean + 3 SD of control was considered abnormal). The section-wiseper cent distribution of abnormalities was vulcanization (83%),tubing (75%), calendering (60%), loading (38%) and mixing (14%).This study provides electrophysiological evidence that rubberfactory environments affect the conduction processes in opticalpathways from their origin in the retina to striate cortex.However, this study has its limitations in not identifying thespecific chemical(s) causing these changes in VEP.     

高压氧暴露诱导小鼠低氧耐受状态变化

目的探讨高压氧暴露后小鼠低氧耐受状态的变化。方法昆明种小白鼠123只随机均分为高压氧暴露(HBO)组、高压空气对照(HBA)组、空白对照(NBA)组,经过5 d处理后每组取25只检测动物在低氧条件下的存活时间,另外每组16只进行力竭游泳耐受时间检测。结果HBO组中位生存时间(108 m in)较NBA组(57 m in)明显延长,HBO与NBA两条生存曲线的差异有统计学意义(Log-rank检验,P<0.01)。HBO组低氧力竭游泳耐受时间[(45.19±17.27)m in]较NBA组[(20.96±11.30)m in]明显延长(P<0.01)。结论高压氧暴露可改善小鼠低氧耐受状态。     

1~36月龄早产儿闪光视觉诱发电位随访研究

目的 探究1~36月龄早产儿闪光视觉诱发电位(flash visual evoked potential,FVEP)发育进程,比较其与同龄足月儿的差异,为实施针对性早期干预提供依据。 方法 依据出生体重不同,将早产儿分为极低出生体重(very low birth weight,VLBW)组、低出生体重(low birth weight,LBW)组以及对照组,应用美国Viking-Ⅳ诱发电位仪,纵向记录三组儿童在1、3、6、9、12、18、24、36月龄(早产儿按矫正月龄)FVEP主波P2波潜伏期、振幅值。 结果 三组儿童FVEP发育轨迹大致相似,随月龄增长P2潜伏期呈下降趋势,6月龄内下降幅度最大;VLBW组与对照组相比,在1~24月龄均显示P2波潜伏期显著延迟,36月龄差异无统计学意义;LBW组与对照组相比,仅在1、3、6月龄段显示P2波潜伏期显著延迟。 结论 早产、低出生体重对婴幼儿的视觉系统发育有明显的不良影响,尤其对VLBW早产儿的影响更加显著,应加强对这类儿童在学龄前期的视功能状态的随访评估。     

新生儿重症监护病房早产儿视觉诱发电位检查及其相关因素分析

目的探讨闪光视觉诱发电位(flash visual evoked potentials,FVEP)在新生儿重症监护病房的应用及相关因素分析,为早产儿视功能诊断提供科学依据。方法收集新生儿重症监护病房早产儿30例作为实验组,该组患儿常合并两种或多种高危因素,普通新生儿病房足月新生儿30例作为对照组,均排除致脑损伤高危因素的普通病种住院患儿。两组患儿均在入院后1~2周行FVEP检查,对异常者,在生后3个月、6个月进行了随访。结果胎龄与P100潜伏期密切相关,表现为胎龄越小,P100潜伏期越延长,差异有高度统计学意义(P<0.001),而引起P100主波缺失的主要高危因素是高胆红素血症、窒息、甲状腺功能减退。对FVEP异常者随访发现,在16例(26眼)早产儿FVEP异常者中,有8例早产儿恢复正常,1例无改变,7例失访。足月儿组中,FVEP4例(6眼)异常,6个月后随访,P100潜伏期均已恢复同龄参考水平。结论 FVEP检查为早产儿视功能状态提供一种准确、灵敏、重复性好的客观检测方法。高胆红素血症、窒息、甲状腺功能减退等是引起早产儿脑损伤不可忽视的高危因素。     

精细运动发育落后幼儿视觉运动整合与视诱发电位关系探讨

目的 研究精细运动发育落后幼儿其视觉运动整合能力与视诱发电位潜伏期之间的相关性,为发育落后患儿的早期诊断和干预提供科学依据。方法 2015年1月-2016年12月选择71例经PDMS-Ⅱ测试精细运动发育落后并符合纳入标准的患儿,同时进行闪光视觉诱发电位检测,将闪光视诱发电位P100潜伏期(LP100)均值分别与视觉-运动整合能力(VMI)和精细运动发育商(FMQ)均值进行统计学检验及相关性分析。结果 精细运动发育落后幼儿视诱发电位潜伏期与视觉-运动整合及精细运动发育商存在相关关系(r=-0.859和-0.844,P<0.001),潜伏期越延迟,其视觉-运动整合标准分及精细运动发育商越低。结论 视知觉功能可影响精细运动发育落后幼儿视觉运动整合能力,视诱发电位可作为早期诊断、早期干预提供重要线索和电生理依据。     

Neurotoxicity induced by lead levels: an electrophysiological study

The object of the present study was to evaluate, with the aid of visual evoked potentials (VEPs), modifications induced in the optic nerve by lead, and to investigate the relationship between blood lead levels (PbB) and modification of the VEP. We studied a sample of 300 men with PbB values between 17 and 60 g/100 ml. Our study demonstrates that alterations in the latency of the VEP are dependent on PbB levels, though there is not a directly proportional relationship.     

锑短期暴露对大鼠健康效应的影响

目的 针对饮水中短期暴露锑所致健康风险开展动物实验研究。方法 选择健康SD大鼠60只（雌雄各半）随机分为6组,实验组大鼠经口给予酒石酸锑钾,锑浓度分别为0.06、0.35、0.6、6和60 mg/kg,阴性对照为超纯水,连续灌胃14 d。染毒期间,每周称量大鼠体重,于染毒后d14腹主动脉取血检测血生化指标,处死大鼠后取肝、肾、脾、胸腺、甲状腺称重并进行病理学检查。结果 最高剂量组（60 mg/kg）与阴性对照组相比,雄性大鼠体重明显降低(P＜0.05)、肝脏体比升高(P＜0.01)、血清总胆固醇（TC）浓度降低 (P＜0.01);雄性大鼠碱性磷酸酶（ALP）随染毒剂量增加浓度逐渐上升,在0.6 mg/kg组中达到最高值(P＜0.05),随后ALP浓度逐渐减低,在最高剂量组（60 mg/kg）出现显著性降低(P＜0.01);0.6 mg/kg组葡萄糖（GLU）浓度降低 (P＜0.05);雄性大鼠血清T4浓度自6 mg/kg组开始逐渐降低(P＜0.05);雌性大鼠血清FT4浓度从6 mg/kg组开始逐渐升高(P＜0.05),而FT3的浓度逐渐降低 (P＜0.05);雄性血清FT3浓度、雌性血清T4浓度则仅在0.6 mg/kg组下降（P＜0.05）。结论 锑短期经口暴露能够显著引起大鼠代谢功能异常。