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Biomedical subjects

Y X Liang

Publications and source records attributed to Y X Liang.

At least 19 recordsLinked to original sources
PubMed2004

Stress in expatriates.

With economic globalization, the rate and effects of culture shock stress in expatriates and their families are expected to increase. The stressor may occur from the micro-environment, the macro-environment, or the mega-environment. The effects of stress are frequently due to predictable reactions such as insecurity, distress, and homesickness. These symptoms can progress to more severe psychosomatic symptoms, including depressive reactions and overt psychopathic behavior. Cross-cultural training programs are currently the best preventive strategy for culture shock and subsequent stress; however, the true efficacy of these programs is not well characterized. Substance abuse is probably a significant underlying problem for international business travelers; however, the true magnitude and effects of this issue are not well characterized in the expatriate community. There are substantial opportunities for additional medical research in these areas.

Adaptation, Psychological↗
PubMed2001

Aluminum-induced apoptosis in cultured astrocytes and its effect on calcium homeostasis.

Aluminum exposure and apoptotic cell death has been implicated in several neurodegenerative conditions including Alzheimer's disease. In this study, we use cultured astrocytes to investigate the ability of aluminum to induce the apoptosis of astrocytes. The proportion of apoptotic cells and cell cycle distribution were determined by flow cytometric analysis. Our results showed that exposure to aluminum at low levels (100 and 200 microM) for up to 6 days did not result in the apoptosis of astrocytes, and a dramatic blockage of apoptotic cells was found at 200 microM aluminum. However, at 400 microM, aluminum markedly induced the apoptosis of astrocytes, which was associated with a significant change in cell cycle distribution characterized by increase of G2/M phase cells (128%). Measurements of intracellular Ca(2+) concentration using the fluorescent calcium indicator dye Fluo-3 demonstrated a significant increase in the levels of intracellular calcium after aluminum treatment. However, no differences were observed among aluminum-treated groups. These findings suggest that aluminum induce and block selectively the apoptosis of astrocytes, which depend upon the concentrations of aluminum. Increased intracellular Ca(2+) may not be the primary mechanism of aluminum-mediated apoptotic cell death.

Aluminum↗
PubMed2000

Fatal occupational injuries in a new development area in the People's Republic of China.

Fatal occupational injuries in a new development region in Shanghai in east China are described. All occupational deaths in the East Pujiang New Area during the period 1991 through 1997 were abstracted from multiple, overlapping source documents. There were 426 deaths and a crude mortality rate of 9.1 per 100,000 workers. The death rate was highest in 1995 (14.6%), when expansion in the area was most rapid. The construction sector accounted for 55% of the deaths, followed by manufacturing (23%) and transport, storage, and telecommunications (11%). Falls, collisions, struck by/against incidents, and electrocutions accounted for 80% of all deaths. Falls led all other causes of deaths (33%) and were particularly prevalent in the construction industry (46% of all deaths in construction). The development of ongoing, comprehensive injury surveillance systems in the People's Republic of China will be essential to target and evaluate injury prevention activities in the future.

Accidents, Occupational↗
PubMed2000

Lessons learned--15 years of the WHO-NCTB: a review.

Based on expert recommendations, the World Health Organization (WHO) recommended the Neurobehavioral Core Test Battery (NCTB) in 1983 to detect neurotoxicity in world-wide populations. The NCTB consists of 7 neurobehavioral tests (Digit Symbol, Digit Span, Benton visual memory test/recognition form, Santa Ana dexterity test, Simple Reaction Time, Pursuit Aiming II, and Profile of Mood States). Research with the NCTB provides the context for the results of a mini-symposium held in 1999 to discuss the lessons learned about using the NCTB in working populations. Speakers from Africa, Asia, Europe, and North America reviewed data from 94 studies using the NCTB, including 63 from China, 13 from Korea, 11 from Poland, three from South Africa, three from the USA, and one from Ecuador. Although a consensus was not sought in the symposium, the key lessons learned that emerged from the various presentations, were: * The NCTB is effective in testing adults with 12 or more years of formal education, but can not reliably test persons with less than 9 years of education. * People from cultures very different from those in Europe and North America (eg, aboriginal and African cultures) may not be tested effectively by the NCTB, although others such as at least some Asian populations, can be. To address this problem, the construct validity of the NCTB should be established in a wide range of countries. * The POMS measures of emotion proved to be very sensitive to neurotoxic exposures in several countries, but the POMS was the NCTB test most affected by cultural differences. The Digit Symbol or the Milan modification of that test was also highly sensitive to neurotoxic exposures. * Examiner drift following training to administer the NCTB is a significant problem in technically trained Examiners. Pursuit Aiming II is very difficult to score reliably.

Adult↗
PubMed1998

The antagonistic effects of L-dopa and eserine on Al-induced neurobehavioral deficits in rats.

The main goals of the study were to elucidate the mechanism of Al-induced behavioral toxicity and to explore the possible link between the changes in the metabolism of monoaminergic or cholinergic transmitters and neurobehavioral effects. Three groups (12 rats in each group) were fed with aluminum chloride in drinking water (1600 mg/l) ad libitum through a 90-day exposure period. The controls were fed with distilled water. From the 60th to 90th day of treatment, two of the three Al-treated groups were administered with L-dopa (220 mg/kg.bw) and eserine (0.4 mg/kg.bw) by gavage, respectively. A two-item neurobehavioral test battery consisting of step down test and Morris water maze task was used for rats after three months treatment. In the step-down test, markedly shortened the step-down latency (SDL) and the number of step-down (NSD) were observed in the Al-treated group (P < 0.05, vs. control). On the contrary, only slight changes were found in the rats treated with aluminum combined with L-dopa or eserine (P > 0.05, vs control). In eserine and L-dopa antagonized groups, the mean escape latencies of Morris water maze approached a level close to that of the controls (P > 0.05). The results showed that the Al-induced memory and learning impairment could be reduced by L-dopa or eserine. It is suggested that the depletion of dopaminergic and cholinergic transmitters in the central nervous system might play an important role in Al-induced neurotoxicity.

Aluminum↗
PubMed1997

The development of neurobehavioral toxicology in China: the 1994 Hänninen Lecture.

With the rapid growth of industrialization in China, occupational and environmental exposure to chemicals has increased in frequency and in types of chemical exposures. A growing number of Chinese researchers are showing a special interest in exploring the effects of chemicals on the central nervous system. This paper presents a comprehensive review of neurobehavioral toxicology in China. It describes research into the "reference values" of the Neurobehavioral Core Test Battery (NCTB) tests, the development and improvement of the computer-administered Chinese version of the Neurobehavioral Evaluation System (NES-C), and exploration of related biomarkers. On the basis of this research, baseline data for the reference values for six subtests of the NCTB were preliminarily recommended. The upgraded NES-C2 has proven to possess higher stability and validity compared with the previous version, NES-C. Biomarkers derived from the changes in levels of neurotransmitter metabolites might be used as supplementary biomarkers of Pb-induced neurotoxicity.

Adolescent↗
PubMed1995

Natural co-occurrence of Fusarium toxins and aflatoxin B1 in corn for feed in north Vietnam.

Natural occurrence of Fusarium mycotoxins (trichothecenes and fumonisins) and aflatoxin B1 (AFB1) were surveyed in 32 corn samples, harvested in 1993 and randomly sampled in 1994 in several districts of Hanoi, Vietnam. Corn samples were first milled into fine powder, extracted with methanol-water (3:1) and the crude extracts obtained from the same samples were used for the simultaneous analysis of the trichothecenes such as nivalenol (NIV), deoxynivalenol (DON), and T-2 toxin (T-2) by gas chromatography/mass spectrometry (GC/NS); fumonisins B1 (FB1), B2 (FB2), and B3 (FB3) by high-performance liquid chromatography (HPLC) with a flourescence detector; and AFB1 by and ELISA kit based on a monoclonal antibody. The data revealed that 14, 8, 4, 3, and 2 out of 15 corn kernel samples were positive for AFB1, FB1, FB2, FB3, and NIV with the average levels being 28, 1, 101, 276, 232, and 858 ppb, respectively, and neither DON nor T-2 were detected. As for the other 17 samples of corn powder, 13, 15, 12, 10, 4 and 2 were positive for AFB1, FB1, FB2, FB3, DON, and NIV with the average being 30, 780, 289, 176, 3, 170, and 1,365 ppb, respectively, and T-2 was not detected. Although their positive rates and levels fell in the ranges reported elsewhere, it was found for the first time that the Fusarium toxins (NIV, DON, and fumonisins) and an Aspergillus toxin (AFB1) were naturally co-contaminated in selected samples of corn produced in north Vietnam.

Aflatoxin B1↗
PubMed1995

The development of occupational exposure limits for chemical substances in China.

This paper presents a comprehensive review of the occupational exposure limits (OELs) of chemical substances in China. It provides historical background on the development of OELs in this country, with a complete list of traditionally adopted and newly developed OELs for chemicals in workplaces. The philosophical thoughts, the administrative system, the scientific protocols for setting and amending health standards, with emphasis on making health a basic criterion for setting health standards, strengthening epidemiological studies of the human population, integrating epidemiological and toxicological studies, considering technological and economical feasibilities, and making full use of literature information sources are discussed. Further perspectives with respect to practical issues of maximum allowable concentration and time-weighted average, selection of safety factors, and establishment of biological exposure limits are also considered, with the authors' contributions to a discussion on these topics.

Air Pollutants, Occupational↗
PubMed1995

Alterations of monoamine metabolites and neurobehavioral function in lead-exposed workers.

Neurobehavioral and neurochemical effects of occupational lead exposure were investigated by WHO Neurobehavioral Core Test Battery (NCTB) testing and a series of monoamine neurotransmitters and their metabolites analyzing in workers from lead smeltery and storage-battery manufacturing factory and matched controls. Indicators of lead exposure, the blood lead (PbB) and zinc protophorphyrin (ZPP) levels were found significantly higher in the exposed group compared with that of the controls (70.55 micrograms/dL vs 3.67 micrograms/dL; and 294.92 micrograms/dL vs 38.32 micrograms/dL, respectively). Furthermore, elevated urinary homovanillic acid (HVA) and impairment of certain neurobehavioral performances were also found in the lead exposed workers; the latter included attention/response speed, manual dexterity, perceptual-motor speed, visual perception/memory, and motor speed/steadiness. Positive or negative correlations were observed between certain parameters. Thus, homovanillic acid (HVA) is positively correlated with PbB and ZPP; dopamine (DA) negatively correlated with Benton visual retention (BVR); and HVA negatively correlated with digit symbol (DSy), BVR, and pursuit aiming (PA). It is suggested that the alterations of dopamine and its metabolites HVA in urine associated with impairment of neurobehavioral function might be served as biomarkers of lead-induced neurotoxicity.

Adult↗
PubMed1994

Effects of low level lead exposure on behavior of young rats.

Dam rats were given Pb (0.58, 1.76, and 5.27 mmol.L-1), containing water ad lib from d 16 of gestation to weaning of the offspring on d 21 postpartum. The pups continued drinking the same water till the postnatal d 30. The neurobehavioral function of pups was tested. The second step-down latencies (SDL2) were shortened and the number of step-downs in 5 min (NSD) were increased in step-down test. The prolongation of the lapse of time in passing through the whole course (LTPWC) and the increase in number of entries into the blind alley (NEBA) were measured in water maze test. The number of ambulations and rearings were increased in locomotor activity. The results indicated that Pb exerts adverse effects on the learning ability and memory function, and induces hyperactivity in young rats.

Animals↗
PubMed1994

[Meta-analysis in neurobehavioral toxicological studies].

Meta-analysis was used to deal with the data collected in neurobehavioral toxicological studies to synthesize their findings quantitatively. Results revealed neurotoxic chemicals could cause changes in cognitive abilities, psychomotor function and emotion of persons exposed. However, each toxicant had its distinct effects on neurobehavior, for example, lead mainly impairs touch sense, memory, emotion and cognitive abilities, mercury does intelligence, concentration and motor stability, and carbon disulfide does eye-hand coordination. It suggested meta-analysis could be directive to selecting the best combination of neurobehavioral tests.

Carbon Disulfide↗
PubMed1994

[Neuropsychological effects of lead exposure].

Neuropsychological effects of lead exposure were studied with WHO recommended Neurobehavioral Core Test Battery (NCTB) and factor analysis in 78 workers occupationally exposed to lead and 76 nonexposed controls with mean blood lead levels of 2.14 mumol/L and 0.20 mumol/L, respectively. Except for the length of employment and average monthly income, there was no significant difference in other aspects of both groups. Lead-exposed workers with blood lead level or more than 2.72 mumol/L showed mild impairment to their motor coordination and memory functions. It also showed a dose-response tendency between blood lead levels and scores of five relevant factors.

Factor Analysis, Statistical↗
PubMed1993

Psychological effects of low exposure to mercury vapor: application of a computer-administered neurobehavioral evaluation system.

A computer-administered neurobehavioral evaluation system in a Chinese language version (NES-C) and a mood inventory of the profile of mood states (POMS) were applied to assess the psychological effects of low-level exposure to mercury vapor in a group of 88 workers (19 males and 69 females, with mean age of 34.2 years) exposed to mercury vapor (average duration of exposure 10.4 years). The well-matched group of 97 nonexposed workers was treated as the control. The intensity of current mercury vapor was relatively mild as reflected by the average level of mercury in the air of the workplace (0.033 mg/m3) and in urine (0.025 mg/liter). The results indicated that the profile of mood states posed was moving to the negative side in Hg-exposed group and most of the NES-C performances, in particular, the mental arithmetic, two-digit search, switching attention, visual choice reaction time, and finger tapping, were also significantly affected compared with those obtained from controls (P < 0.05-0.01). The present study and the previous study on the validation of the system suggest that the NES-C we developed is valid for the neurotoxicity screening among the working population exposed to neurotoxic agents.

Adult↗
PubMed1993

Comparison of performance from three continents on the WHO-Recommended Neurobehavioral Core Test Battery.

To address the need for standardized test batteries, an expert group convened by the World Health Organization (WHO) and the U.S. National Institute for Occupational Safety and Health during 1983 proposed the Neurobehavioral Core Test Battery (NCTB) to identify nervous system effects of chemical exposures in human populations worldwide. To determine the feasibility of using the NCTB in varied cultures, a cross-cultural assessment was conducted under WHO auspices. Data were collected in 10 countries of Europe, North and Central America, and Asia from over 2300 males and females who were not exposed to chemicals at work, within five age ranges between 16 and 65. Results suggest that performance on two NCTB tests (Simple Reaction Time, Benton Visual Retention) is very similar in a broad range of countries and that performance on four other NCTB tests (Santa Ana, Digit Symbol, Digit Span, Aiming) is relatively more variable from country to country, in both males and females. However, data collected from very poorly educated males in one country revealed very low performance levels suggesting that the NCTB may not provide an adequate reference group for identifying (behavioral) neurotoxic effects in such populations. More research is thus needed on evaluating neurotoxicity in poorly educated subjects.

Adult↗
PubMed1993

Studies on the toxicity and maximum allowable concentration of chloroform.

Chloroform has obvious hepato-, nephro-toxicity and carcinogenicity. In order to get necessary data for recommendation of maximum allowable concentration of chloroform in workplace, a series of studies were carried out. The results showed that exposed workers mainly distributed in the industries of perspex processing, production of refrigerants, drugs and pesticides. The exposure level ranged 4.27-147.91 mg/m3 in 119 air samples collected from 3 representative worksites, with 45.4% air samples below 20 mg/m3. The workers exposed to chloroform at 29.51 mg/m3 had slight liver damage indicated by the higher rates of abnormal serum prealbumin and transferrin levels than those of control workers. The neurobehavioral functions of these workers were also obviously affected, manifested as increases in scores of passive mood states and dose-related negative changes in neurobehavioral testing. The observed effect threshold concentration of subacute inhalation in rats was 592 mg/m3 according to the observation on the biochemical changes in liver tissue and abnormal activities of serum enzymes. Mainly based on the above results, we recommended 20 mg/m3 as the Maximum Allowable Concentration in workplace in China at present.

Adult↗
PubMed1992

An occupational hygiene survey in a Chinese viscose rayon factory.

The retinopathy (microaneurysm/small dot hemorrhage) is an early and specific biological indicator to quantitatively evaluate the CS2 exposure. The appearance of retinal lesions was observed among Yugoslavian, German and American workers exposed to CS2. However, among Finnish CS2 workers a positive result was not obtained. We suggested a different response to CS2 exposure between two ethnic populations. We had an opportunity to do a cross-sectional medical and occupational hygiene survey in a Chinese rayon staple plant. Cross-sectional medical examinations failed to show any chronic CS2 effects on the Chinese workers.

Adult↗
PubMed1991

The current status of hygiene standard setting for chemical substances in workplaces in China.

The hygiene standard setting for occupational hazards was started in the mid 1950s in China. Three documents on exposure limits for chemical substances in the work environment and some other documents related to exposure limits for physical agents have been published since then. The latest documentation on "Hygiene Standards for the Design of Industrial Premises" (Standard TJ 36-79) was promulgated in 1979. It contains a MAC list of 134 toxin agents and dusts which are most frequently used and encountered in China. However, a more sophisticated system of scientific research on hygiene standard setting has been created since the establishment of the National Scientific Commission of Hygiene Standard Setting in 1980. This system emphasizes health as a basic criterion, it strengthens epidemiological study of the human population, it integrates domestic and international information sources and it periodically reappraises the recommended standards. Based on these principles, more than forty new standards have been set for both chemicals and dusts since the founding of the committee. These new MACs are now in the process of being promulgated and are expected to take effect as the additional part of the MAC list published in 1979. In addition, further considerations of hygiene standard setting related to the conceptual renewal, selection of safety factor, legislation and enforcement of the hygiene standard, recommendations of exposure limits for occupational carcinogens, and speeding up the pace of hygiene standard setting are proposed in this paper.

Carcinogens↗