Monitoring of individual human exposure to aflatoxins (AF) and N-nitrosamines (NNO) by immunoassays

Highly sensitive immunoassays have been used to quantitate aflatoxins (AF) and N-nitrosamines (NNO) in human body fluids and tissues, respectively. This approach was taken in order to quantitate environmental exposure to these agents at an individual level to facilitate the investigation of their role in the etiology of human cancer. In order to analyse AF in human urine, an immunopurification step has been developed by using AF-specific antibody bound to AH-Sepharose 4B gel in a small (4-ml gel volume) affinity column prior to enzyme-linked immunosorbent assay (ELISA). The ELISA can be used to quantitate aflatoxin B1 (AFB1) over the range 0.01 ng/ml to 10 ng/ml and the assay system has been validated by using human urine samples spiked with AFB1 over this concentration range. In addition, 29 urine samples from the Philippines have been analysed and found to contain a range of levels from zero to 4.25 ng/ml AFB1 equivalent with a mean of 0.875 ng/ml. This compared with a mean of 0.066 ng/ml AFB1 equivalent in samples from France. Radioimmunoassay of O6-methyldeoxyguanosine (O6-medG) has been performed on human oesophageal and cardiac stomach mucosal DNA from tissue samples obtained during surgery in Linxian County, People's Republic of China, an area of high risk for both oesophageal and stomach cancer. Using the methodology described and having 1 mg of hydrolyzed DNA allows the detection of approximately 25 fmol O6medG per mg DNA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Methyl parathion increases neuronal activities in the rat locus coeruleus

Exposure to organophosphate insecticides induces undesirable behavioral changes in humans, including anxiety and irritability, depression, cognitive disturbances and sleep disorders. Little information currently exists concerning the neural mechanisms underlying such behavioral changes. The brain stem locus coeruleus (LC) could be a mediator of organophosphate insecticide-induced behavioral toxicities since it contains high levels of acetylcholinesterase and is involved in the regulation of the sleep-wake cycle, attention, arousal, memory, and pathological processes, including anxiety and depression. In the present study, using a multi-wire recording technique, we examined the effects of methyl parathion, a commonly used organophosphate insecticide, on the firing patterns of LC neurons in rats. Systemic administration of a single dose of methyl parathion (1 mg/kg, i.v.) increased the spontaneous firing rates of LC neurons by 240% but did not change the temporal relationships among the activities of multiple LC neurons. This dose of methyl parathion induced a 50% decrease in blood acetylcholinesterase activity and a 48% decrease in LC acetylcholinesterase activity. The methyl parathion-induced excitation of LC neurons was reversed by administration of atropine sulfate, a muscarinic receptor antagonist, indicating an involvement of muscarinic receptors. The methyl parathion-induced increase in LC neuronal activity returned to normal within 30 min while the blood acetylcholinesterase activity remained inhibited for over 1 h. These data indicate that methyl parathion treatment can elicit excitation of LC neurons. Such excitation could contribute to the neuronal basis of organophosphate insecticide-induced behavioral changes in human.     

氟监测植物的筛选及监测指标的研究

本文报道用开顶式熏气装置筛选大气氟监测植物,研究监测植物在氟污染情况下的反应,以确立监测指标和监测定量化。结果表明,梅、唐菖蒲、赤胫散、火炭母、水杉、金荞麦、雪松、苹果等植物是良好的氟监测植物,其中赤胫散、火炭母是国内筛选出来的监测植物,可用来监测大气氟污染。受害浓度(阈值)、症状出现时间、受害叶面积％和叶片含氟量可作为植物的监测指标,生理反应指标作为参考。     

The Ethical Conduct of Studies Involving Controlled Human Exposure to Environmental Pollutants

In recent years, the concern for human research subject protection has increased markedly in the United States. The nature of research subject participation in controlled-exposure environmental health research is such that the individual subject bears the risk of participation, while the benefits of such research accrue to society. Therefore, particular attention must be paid when designing studies to protect the health and safety of human research subject. This paper outlines principles for the appropriate selection of pollutants to which humans can be exposed, and the principles that should be used to protect the health and safety of human research subject.     

Determination of free and total S-phenylmercapturic acid by HPLC/MS/MS in the biological monitoring of benzene exposure

Urinary S-phenylmercapturic acid (SPMA) is a biomarker suggested by the American Conference of Governmental Industrial Hygienists (ACGIH) for assessing occupational exposure to benzene. A possible cause of the miscorrelation between environmental monitoring and biological monitoring for benzene exposure, which many authors complain about, is the existence of a urinary metabolite that turns into SPMA by acid hydrolysis. Forty urine samples were tested to determine which concentration value would correspond to the ACGIH Biological Exposure Index (BEI) of 25 µg g^-1 creatinine if exposure assessment was based on the determination of SPMA after quantitative hydrolysis of its precursor. An aliquot of each sample was hydrolysed with 9 M H₂SO₄, a second one was brought to pH 2 and a third one was used as it was (free SPMA). SPMA was determined by high-performance liquid chromatography/tandem mass spectrometric technique (HPLC/MS/MS) using an internal standard. The analytical method was validated in the range 0.5-50 µg l^-1. The average SPMA in pH 2 samples is 45-60% of the total, while free SPMA varies from 1% to 66%. The hydrolysis of pre-SPMA reduces the likelihood of variability in the results by reducing pH differences in urine samples and increasing the amount of measured SPMA. The BEI limit value would be about 50 µg g^-1 creatinine.     

人类演化中的

解剖学意义上的现代人的出现和扩散是人类演化史的关键性事件;备受国际学术界瞩目。“现代人”从与其姐妹种群共存到脱颖而出;成功扩散到了沙漠、热带雨林、高海拔山区等全球多样的生态环境之中;其“前所未有”的行为复杂化和适应能力被认为在其中起到了关键性作用。基于非洲、西亚和欧洲考古学材料;国际学术界建立起对一系列复杂化行为表征的基础认识;并不断探讨如何从“行为现代性”革命最终稳定呈现“现代人行为”。尽管对于东亚地区“现代人行为”发展演化的研究还处于初步探索阶段;但近年来的新研究也不断揭示着其本身丰富的内涵和多样性。纵观“现代人行为”的发展过程;可见其伴随人类体质的发展得到放大和增强;但其本身又在整个人类演化史中以不断累进的方式发展;这种积累甚至一直持续到今天。     

Effect of unilateral load carriage on postures and gait symmetry in ground reaction force during walking

Unilateral load carriage is more hazardous to the musculoskeletal system than bilateral load. The purpose of this study was to examine the effect of such asymmetric carriage on postures and gait symmetry in ground reaction force (GRF) during walking. Kinematics and GRF of 19 adults were recorded while they walked under five load conditions: no load, dumbbell (10 and 20% body weight) held in right and left hand, respectively. After loading, the trunk bent towards the loaded or unloaded side in right- and left-hand trials and under different load weight conditions. The amplitude of trunk bend increased with load, accompanied by decreased stride width, progressively inclined legs towards unloaded side and higher level of asymmetry in medial/lateral GRF (GRFm/l) and free vertical moment GRF (GRFm). The findings indicate the postural adjustment is likely related to the characteristics of load and the task experience and handedness of subject and the unilateral load increases the gait asymmetry in GRFm/l and GRFm.     

A neural basis for gyroscopic force measurement in the halteres of <Emphasis Type=Italic>Holorusia</Emphasis>

Dipteran flight requires rapid acquisition of mechanosensory information provided by modified hindwings known as halteres. Halteres experience torques resulting from Coriolis forces that arise during body rotations. Although biomechanical and behavioral data indicate that halteres detect Coriolis forces, there are scant data regarding neural encoding of these or any other forces. Coriolis forces arise on the haltere as it oscillates in one plane while rotating in another, and occur at oscillation frequency and twice the oscillation frequency. Using single-fiber recordings of haltere primary afferent responses to mechanical stimuli, we show that spike rate increases linearly with stimulation frequency up to 150 Hz, much higher than twice the natural oscillation frequency of 40 Hz. Furthermore, spike-timing precision is extremely high throughout the frequency range tested. These characteristics indicate that afferents respond with high speed and high precision, neural features that are useful for detecting Coriolis forces. Additionally, we found that neurons respond preferentially to specific stimulus directions, with most responding more strongly to stimulation in the orthogonal plane. Directional sensitivity, coupled with precise, high-speed encoding, suggests that haltere afferents are capable of providing information about forces occurring at the haltere base, including Coriolis forces.