Search

BackgroundThe converter stations of high-voltage direct current (HVDC) transmission lines generate special total electric fields. At present, few investigations have been conducted on total electric fields in the workplace of converter stations from an perspective of occupational health. ObjectiveTo understand the current situation of total electric field strength in the workplace of converter stations. MethodsUsing purposive sampling, a calibrated HDEM-1 direct current (DC) total electric field strength measurement system was used to measure the total electric fields of 12 converter stations serving 6 DC lines in Southeast and Southwest China according to the Measurement method for total electric field strength and ion current density of the converter stations and DC transmission lines (DL/T 1089—2008). The results were evaluated according to occupational exposure limits recommended by The limits of electromagnetic environment at ±800 kV UHV DC converter station (DL/T 275—2012), the American Conference of Governmental Industrial Hygienists (ACGIH), and the International Commission on Non-Ionizing Radiation Protection (ICNIRP). ResultsA total of 615 check points were planned, the total electric field strength was 0.05-37.05 kV·m−1, and the median was 10.45 kV·m−1. The total electric field strength of 39 check points (6.3%) exceeded 25 kV·m−1 (the limits of ACGIH and ICNIRP), and the total electric field strength of 12 check points (2.0%) exceeded 30 kV·m−1 (the limit of DL/T 275—2012). There were statistically significant differences in the total electric field strength values and the proportions of exceeding 25 kV·m−1 between the neutral regions and the positive regions and between the neutral regions and the negative regions (P < 0.01). The proportion of total electric field strength exceeding 30 kV·m−1 in the negative regions was higher than that in the positive regions (P < 0.01). There were no significant differences in the total electric field strength of converter stations at different voltage levels and different altitudes (P > 0.05). There were no significant differences in the proportions of total electric field exceeding 25 kV·m−1 and exceeding 30 kV·m−1 in converter stations at different voltage levels and different altitudes (P > 0.05). ConclusionThe total electric field in some workplace of converter stations exceeds selected limits. Converter station operators may be exposed to high-strength total electric field for a short time.

Hydrogen production of biomass via microwaves is an efficient, rapid, and environmentally friendly chemical engineering technology. Lignin is the only renewable aromatic hydrocarbon resource in the nature, and thus, the lignin-based forest biomass, which has the advantages of low sulfur, is a good raw material for hydrogen production. However, the microwave hot spot effect restricts the industrial application of hydrogen production by microwave. In this study, the reactor was carried out based on the penetration depth of biomass under different microwave frequencies was designed by modeling. Orthogonal design simulation, CFD, and HYSYS were used to obtain the distribution of temperature field with different microwave power density, the radius of biomass particles, bulk density, and the coefficient of variation. Based on the results, the optimal microwave power density was 30 W·g–1, the optimal radius of biomass particles was 4 mm, and the optimal bulk density was 800 kg·m–3, at which a favorable uniform temperature field was achieved, and its coefficient of variation was only 0.009, less than the standard value of 0.01. Then, to reduce energy consumption and improve product economy, the Computational Fluid Dynamics (CFD) method was used to analyze the cloud image of hydrogen production with different height to diameter ratio of the reactor. It was found that when the height to diameter ratio of the reactor was 2.0, the hydrogen-flow could not only fully contact with the falling materials, but also achieve thermal energy circulation by using its own high temperature. Finally, the industrial process of hydrogen production of biomass via microwave was added into HYSYS, and the operating parameters of the maximum hydrogen yield of the 10000-ton industrial device were simulated and optimized. In the reforming reaction, by adding steam in the mid-piece and the end-piece, the production yield of hydrogen can be maximized and the temperature of the reactor can be maintained continuously after the heat energy of hydrogen was recovered. Under the conditions optimized, when the mid-piece and end-piece fluxes of steam were 290 and 1230 m3·h–1, respectively, a favorable hydrogen production of biomass was achieved. The output of hydrogen, the mole fraction and the yield of hydrogen production were 922.98 m3·h–1, 0.4781 and 82.49%, respectively. Moreover, the hydrogen product can reach the high standard of 6.592 g hydrogen/ 100 g biomass, which was far superior to the industry level.

BackgroundWearing anti-vibration gloves is a simple and effective way to prevent hand-arm vibration disease. The requirements for vibration damping gloves are varied by types of operations exposed to vibration.ObjectiveTo study the vibration attenuation and dexterity of different types of protective gloves, and to provide reference for scientific wearing of vibration damping gloves for people working with vibration exposure.MethodsNine kinds of common protective gloves (A and B were dipping gloves; C, D, and E were rubber gloves; F and G were textile and fabric gloves; H was cotton gloves; I was leather gloves) used by workers exposed to vibration in 28 factories in Guangdong Province were selected as research objects by typical case sampling method, and the basic parameters of included protective gloves were investigated and measured. According to ISO 10819:2013, a glove vibration transmissibility (GVT) test system was used to detect the vibration transmissibility values and analyze vibration attenuation characteristics of the subjects wearing different protective gloves. The dexterity was tested by Minnesota Manual Dexterity Test. Pearson test was used to analyze the correlations among glove thickness, vibration transmissibility, dexterity score, and grip strength score.ResultsFor rubber gloves (C, D, and E), the associated average adjusted vibration transmissibility at middle and low frequencies \begin{document}$ {\overline T _{\text{M}}} $\end{document} and average adjusted vibration transmissibility at high frequency \begin{document}$ {\overline T _{\text{H}}} $\end{document} were lower than those of other gloves (0.89-0.91 and 0.59-0.80 respectively), the vibration transmissibility values of 50-200 Hz frequency band was 0.81-0.97, and the vibration transmissibility values of 315-1250 Hz frequency band decreased with the increase of frequency (the minimum value was 0.13). For other types of gloves (A, B, F, G, H, and I), the \begin{document}$ {\overline T _{\text{M}}} $\end{document} and \begin{document}$ {\overline T _{\text{H}}} $\end{document} were 0.95-0.98 and 1.03-1.11 respectively, the vibration transmissibility values of 50-200 Hz frequency band was 0.96-1.02, and the vibration transmissibility values of 400-1250 Hz frequency band increased (the maximum value was 1.29). The \begin{document}$ {\overline T _{\text{M}}} $\end{document}, \begin{document}$ {\overline T _{\text{H}}} $\end{document}, and vibration transmissibility values of 40-1250 Hz frequency band of rubber gloves with double-layer protective materials (C, D, and E) were significantly lower than those of gloves with single-layer protective materials. But the \begin{document}$ {\overline T _{\text{M}}} $\end{document} and \begin{document}$ {\overline T _{\text{H}}} $\end{document} of gloves of other types with double-layer materials (F, H, and I) were still greater than 0.9 and 1.0 respectively. Compared with single-layer protective materials, the gloves of other types with double-layer materials showed no significant changes in the vibration transmissibility values of 25-200 frequency band (0.91-1.06), and an increase in the vibration transmissibility values of 250-630 Hz frequency band (the maximum value was 1.22). The dexterity scores and grip strength scores of dipping gloves (A and B) were the lowest. Rubber gloves C had the highest dexterity score and grip strength score. The thickness of protective gloves was negatively correlated with the vibration transmissibility values, and positively correlated with the dexterity score and the grip strength score (P < 0.05). The vibration transmissibility value was negatively correlated with the dexterity score and the grip strength score (P < 0.05).ConclusionAmong the 9 kinds of gloves, cotton gloves and leather gloves have no damping effect. Rubber gloves have certain vibration reduction effect, and the vibration reduction effect on high frequency band is better than that on low frequency band. The thicker the damping material is, the better the damping effect is, but the less the dexterity is. Appropriate damping gloves should be selected according to actual vibration operations.

BackgroundHand arm vibration disease (HAVD) is one of the legal occupational diseases in China, and its pathogenesis is not clear. Operators exposed to electric vibration tools for a long time have an increased risk of HAVD.ObjectiveTo conduct a systematic evaluation of the effects of vibration operations on workers' upper limb nerves, blood vessels, and muscles.MethodsRelevant studies on the effects of hand-transmitted vibration on HAVD were searched and collected from the China Knowledge Infrastructure, Wanfang, and PubMed databases, and the literature was published from January 1974 to April 2021. The quality of cohort and case-control studies was assessed by the Newcastle-Ottawa Scale (NOS), and the quality of cross-sectional studies was by the evaluation criteria recommended by the Agency for Healthcare Quality and Research (AHRQ). Statistical analyses of outcome indicators (OR) in the included literature were performed using RevMan 5.4.1 software, effect sizes in the literature on vibration-induced white finger and neurosensory impairment were combined using a random-effect model, those that included carpal tunnel syndrome were combined using a fixed-effect model, and subgroup and publication bias analyses were also performed. To explore sources of study heterogeneity, meta-regression was performed using Stata 16.0 software, and sensitivity analyses were performed on the included literature.ResultsA total of 716 papers were retrieved from the databases, and 18 articles were retrieved by manual searching. A total of 34 papers were included after excluding those not meeting the criteria. Of the papers, 11004, 7270, and 1722 subjects related to vibration-induced white finger, neurosensory impairment, and carpal tunnel syndrome, respectively. The results of meta-analysis showed that compared with the control group, the combined ORs of hand-transmitted vibration exposure were 4.25 (95%CI: 2.72−6.65) for vibration-induced white finger, 4.03 (95%CI: 2.46−6.61) for neurosensory impairment, and 2.44 (95%CI: 1.61−3.71) for carpal tunnel syndrome. Heterogeneity was identified in the original studies related to vibration-induced white finger (I2=81%, P < 0.001) and neurosensory impairment (I2=90%, P < 0.001), except carpal tunnel syndrome (I2=23%, P < 0.001). The results of sensitivity analysis showed that the combined effect sizes (ORs) were stable and reliable. The results of meta-regression showed that the factors contributing to high heterogeneity of combined vibration-induced white finger and neurosensory impairment were time of publication (t=−2.10, P=0.049) and working age (t=−2.40, P=0.032), respectively.ConclusionHand-transmitted vibration is a risk factor for vibration-induced white finger, neurosensory impairment, and carpal tunnel syndrome in operators.

Carbon dots (CDs) have been applied to solid lighting because of their excellent fluorescent properties, good chemical stability, easy functionalization, and other advantages. However, the low thermal stability of most CDs limits the wide application of CDs as phosphors in laser illumination field. Aiming at CDs with high thermal stability and low cost, Y-CDs with fluorescent quantum yield of 49% were prepared by one-step hydrothermal method using citric acid and 2，7-dihydroxynaphthalene as raw materials and adjusting the concentration of reactants. The YG-CDs after annealing only lost 10% of weight at 250 ℃, while their thermal stability was greatly improved. The fluorescent films with good transmittance, fluorescent property, and thermal stability were obtained by combining the annealed YG-CDs with three film-forming agents (polymethyl methacrylate, polyvinyl alcohol, and silane coupling agent). This research provides a theoretical and practical basis for the application of CDs-based fluorescent films for laser illumination.

Aiming at the high computational complexity of the existing copy-move image forgery detection algorithm,a copy-move forgery detection algorithm based on group scale-invariant feature transform (SIFT) was proposed.Firstly,the simple linear iterative clustering (SLIC) was utilized to divide the input image into non-overlapping and irregular blocks.Secondly,the structure tensor was introduced to classify each block as flat blocks,edge blocks and corner blocks,and then the SIFT feature points extracted from the block were taken as the block features.Finally,the forgery was located by the inter-class matching of the block features.By means of inter-class matching and feature point matching,the time complexity of the proposed copy-move forgery detection algorithm in feature matching and locating forgery region was effectively reduced while guaranteeing the detection effect.The experimental results show that the accuracy of the proposed algorithm is 97.79%,the recall rate is 90.34%,and the F score is 93.59%,the detecting time for the image with size of 1024×768 is 12.72 s,and the detecting time for the image with size of 3000×2000 was 639.93 s.Compared with the existing copy-move algorithm,the proposed algorithm can locate the forgery region quickly and accurately,and has high robustness.

Fractional transform based image encryption methods have been widely studied in recent years.However,most of the existing fractional transform based image encryption methods are defined in the complex field.Thus,the encrypted images contain both phase and amplitude information,which is not conducive to transmission and storage.Moreover,some encryption methods that meet the requirements of reality-preserving have problems of relatively single keys,lacking of sensitivity and so on.An image encryption method was proposed based on multiple-order fractional discrete Tchebichef transform and generating sequence.The proposed method used randomly generated row and column vectors and generating sequence generated by Chaotic sequences as keys to encrypt images,which not only satisfied property of reality-preserving transmission but also greatly expanded the key space.The experimental results further demonstrate that the proposed encryption method can resist a variety of attacks,and decrypted images are almost non-distored,which indicate excellent encryption effect,sufficient security and robustness of the method.

This study aimed to clarify the oxidative damage in human skin fibroblasts (HSF) treated with trimethylamine oxide (TMAO) and to elucidate its pro-aging effect in skin cells in terms of antioxidant indicators, levels of inflammatory cytokines, levels of collagen and matrix metalloproteinases, and mRNA expression of related genes. The results showed that TMAO treatment significantly increased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and decreased the content of reduced glutathione, superoxide dismutase (SOD) activity, and total antioxidant capacity (TAC) in HSF cells (P < 0.05). TMAO treatment was found to significantly elevate the mRNA levels of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and matrix metalloproteinase-1 (MMP-1), and decrease the mRNA transcript levels of collagen synthesis-related genes and the inducible nitric oxide synthase (iNOS) gene by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA). Western blot analysis showed that the protein expression level of phosphorylated p65 (p-p65) significantly increased (P < 0.05). Vitamin C (VC) was able to protect against TMAO-induced oxidative stress in HSF cells, and reduce inflammation and collagen loss. These results indicated that TMAO can produce oxidative stress in HSF cells, which may activate the signaling pathway of nuclear factor kappa-B (NF-κB), promote NF-κB phosphorylation in HSF cells, induce inflammatory responses, reduce collagen synthesis, and accelerate collagen degradation, thus possibly promoting skin cell aging.

Salt is a seasoning widely used in the food industry and our daily diet. Excessive intake of salt, whose major component is sodium chloride, will increase the risks of multiple diseases such as hypertension, gastric cancer, and stroke. How to reduce the salt content of foods without affecting the flavor is a hot topic of current research. Structural and compositional optimization of solid sodium chloride, which constitutes an important part of daily dietary salt intake, is an effective way to develop low-salt foods. This article provides a detailed discussion on the mechanisms of salty taste perception and sodium absorption and metabolism in the body, and summarizes the salt reduction strategies developed based on structural regulation and compositional design of sodium chloride in recent years. The novel technologies for reducing the salt content without affecting the salty taste, such as regulating the physical structure (morphology and particle size) of sodium chloride, encapsulating sodium chloride, and adding sodium chloride substitutes (salty mineral salts, flavor enhancers and natural taste substances) are discussed. In the end, the salt reduction mechanisms, shortcomings and applicable scenarios of salt with different structures and components are analyzed. We hope that this review will provide theoretical evidence and technical support to design new salt products, develop low-salt foods, reduce the dietary salt intake of residents and improve human health in the future.

ObjectiveTo investigate the prevalence and influencing factors of subclinical infection of hepatitis E virus (HEV) in Shanghai community residents for providing evidences to comprehensive prevention and treatment of hepatitis E.MethodsWith multistage probability proportional-to-size random sampling, we conducted a seroepidemiological survey among 4 661 permanent residents (aged 1 – 69 years) in 32 urban communities/rural villages in 16 districts of Shanghai city during May – December 2018. The participants had face-to-face interviews with a self-designed questionnaire and detections of serum HEV immunoglobulin G (IgG) and immunoglobulin M (IgM) by enzyme-linked immunosorbent assay (ELISA). Binary multivariate logistic regression analysis was adopted to explore influencing factors of subclinical HEV infection.ResultsOf all the participants, 26.11% (1 217) were positive for HEV-IgG or HEV-IgM antibody. The results of regression analysis revealed that the risk factors of subclinical HEV infection included male gender, five years old and above, drinking unboiled water occasionally, being retired, having hepatitis related detection during past six months, and consuming fresh sashimi during past six months; the results also showed that with a non-local registered residence, being not sure about a history of having HEV vaccination, and washing hands before eating and after using bathroom were protective factors against HEV infection.ConclusionAmong urban and rural community residents of Shanghai city, the prevalence of HEV subclinical infection was relatively high and influenced mainly by gender, age, occupation, registered residence, whether drinking unboiled water, history of HEV vaccination, and the status of having hepatitis-related test/consuming fresh sashimi during past six months.

The traditional video passive forensics method using only the principle of similarity between adjacent frames will cause a lot of false detection for the video with severe motion.Aiming at this problem, a video tamper detection method combining spatial constraints and gradient structure information was proposed. Firstly, the low motion region and the high texture region were extracted by using spatial constraint criteria. The two regions were merged to obtain the robust quantitative correlation rich regions for extracting video optimal similarity features. Then improving the extraction and description methods of the original features, and using the similarity of the gradient structure in accordance with the characteristics of the human visual system to calculate the spatial constraint correlation value. Finally, the tampering points were located by the Chebyshev inequality. Experiments show that the proposed algorithm has lower false detection rate and higher accuracy.

The purpose of this paper is to systematically summarize the gene polymorphisms associated with osteoporosis(OP)susceptibility in Zhuang ethnic group in Guangxi.These genes mainly encode vitamin D receptor,estrogen receptor,calcitonin receptor,and adiponectin.The genotype and allele distribution frequency were compared between Zhuang ethnic group and other ethnic groups,which can clarify the existing genes and the potential gene polymorphism associated with OP in Zhuang ethnic group.The findings provide a representative solution for the subsequent research on the genes associated with OP susceptibility in ethnic minorities.

Objectives: To determine the effects of Huoxue Dingxuan Capsule on vertebral artery blood flow,plasma plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) in rats with cervical spondylosis of vertebral artery type (CSA)., Methods: Ninety healthy male Wistar rats were equally and randomly divided into control,model and treatment groups.The rats in the model and treatment groups were subject to composite modeling manufacturing CSA.The treatment group was given six-week interventions with Huoxue Dingxuan capsule 4 weeks after the modeling.Vertebral artery blood flow,plasma PAI,and t-PA contents were detected before modeling,prior to the interventions,and post interventions., Results: Before the interventions,the rats in the model and treatment groups had significantly lower blood flow of vertebral artery than the controls ( P <0.05).The model rats also had increased serum PAI and t-PA contents ( P <0.01).After the interventions,significantly higher vertebral blood flow was found in the treatment group compared with the controls ( P <0.05).After the interventions,increased serum PAI and t-PA contents were observed in the rats in the model group ( P <0.01);whereas,decreased serum PAI and t-PA contents were observed in the rats in the treatment group ( P <0.01).The treatment group had lower levels of serum PAI and t-PA contents than the model group ( P <0.01)., Conclusions: Huoxue Dingxuan Capsule glare can improve the blood flow of vertebral artery and reduce serum PAI and t-PA contents.

Objective: To develop and evaluate the application of the facial minimally invasive fat granules injection device with controlled pressure and quantity., Methods: Due to the requirement of facial fat grafting (small volume, precision, high pressure), we developed the integrated device with handheld controller and motor. From Nov. 2013 to Mar. 2015, 50 cases who underwent facial fat transplantation were selected to receive facial fat grafting with the device on the right side and with conventional syringe on the left side as control. The clinical effect was assessed by patients, surgeon and one from the third party. The intraoperative pain, injection difficulty, postoperative swelling and hruising, complications and overall satisfactory were recorded. Pain intensity was assessed using digital classification method ( NRS). Therapeutic effect was evaluated using Likert 5 points scoring method. Chi-square test, Wilcoxon test and one-way ANOVA were used for statistical analysis., Results: The device has the advantages of minimal designed and easily handling. The injection speed is 7.2 mm/s with the fat injection volume as precise as 0.04 ml/s (0.0056 m/mm). Among the 50 cases, the excellent and good effect were achieved in 90% (45/50) on the right face, and 78% (39/50) on the left face (Z = -4.285, P < 0.01). Local nodes happened in 7 cases on left face, while none on the right face (χ² = 6.57, P < 0.05). Petechiae occurred in 21 cases on right face and 45 cases on left face (χ² = 5.37, P < 0.05). Pain was assessed as 3.7 ± 1.1 points on the right sides, and 5.2 ± 0.7 points on the left sides (F = 17.405, P < 0.01)., Conclusions: The facial minimally invasive fat granules injection device with controlled pressure and quantity has the advantages of easily handling, precisely controlled quantity with hotter effect, less pain and complication.

Objective: To investigate the effects of chlorophyllin on the regulations of proteins related to cell cycle in vitro in human bronchial epithelial cell line 16HBE transformed by trans-benzo(a) pyrene-trans-7, 8-dihydrodiol-9, 10-epoxide (trans-BPDE)., Methods: RT-PCR and fluoroimmunocytochemistry methods were used to detect the expression of E-cadherin, in mRNA and protein levels, among untreated control cells, malignant transformed cells induced by trans-BPDE and anti-transformed cells treated with chlorophyllin. The expression of cyclins such as Cyclin D1 and Cyclin E was also detected by fluoroimmunocytochemistry method., Results: The loss of E-cadherin expression was found in mRNA and protein levels after being transformed by trans-BPDE, while its expression existed normally after being anti-transformed by chlorophyllin. Cyclin D1 and Cyclin E had no expression in control 16HBE, but expressions of the proteins were enhanced obviously in malignant transformed cell line while those were inhibited significantly in the anti-transformed cells treated with 100pmol/L chlorophyllin., Conclusion: The ability of chlorophyllin to anti-malignant transformants 16HBE cells exposed to trans-BPDE is correlated with arrest the loss of E-cadherin expression. Chlorophyllin has a significant effect on expressions of Cyclin Dl and Cyclin E during the course of anti-malignant transformation.

Objective: To evaluate and screen the specific RNAi fragments which can effectively inhibit Aryl hydrocarbon receptor(AHR) gene mRNA expression in human bronchial epithelial cell line (16HBE)., Methods: AHR mRNA of 16HBE cells transfected 4 different AHR gene interfere sites were determined quantitatively with the quantitative competitive RT-PCR by using self-prepared internal standard as competitive templates, and the RNA interfere effect wasevaluated., Results: AHR mRNA average expression per 40ng total RNA of 16HBE cells transfected 4 different AHR gene interfere fragments were 5.65fg, 14.78fg, 3.14fg and 0.68fg respectively, the average rates of inhibition were 61.6%, -0.5%, 78.6% and 95.4% respectively., Conclusion: AHR gene specific effective RNA interfere sequence ware screened by quantitative competitive RT-PCR which could accurately quantify gene mRNA level, and offered condition for studying the gene function of AHR.

Background & Objective: Oxidative DNA damage plays an important role in carcinogens-induced carcinogenesis. 8-hydoxy-2deoxy-guanosine (8-OH-dG), a biomarker of oxidative DNA damage, plays important roles in initiation, progression, and prognosis of lung cancer, and closely relates with mutations of k-ras and p53 genes in carcinogenesis of lung tissue. This study was to detect protein expressions of 8-OH-dG, k-ras, and p53 genes in lung cancer tissues, and to analyze their values in distinguished diagnosis of lung cancer., Methods: Protein levels of 8-OH-dG, k-ras, and p53 in pleural effusion cells from 53 patients with lung cancer, and 53 patients with other benign lung diseases were detected by immunocytochemistry., Results: Positive rates of 8-OH-dG, k-ras, and p53 protein in cancer group were significantly higher than those in benign disease group [75.5% (40/53) vs. 15.1% (8/53), P < 0.01; 64.2% (34/53) vs. 3.8% (2/53), P < 0.01; and 69.8% (37/53) vs. 18.9% (10/53), P < 0.01; respectively]. Protein levels of 8-OH-dG, k-ras, and p53 protein in cancer group were 1.68+/-1.21, 1.32+/-1.06, and 1.57+/-1.15,respectively. Rank correlation analysis showed that protein expression of 8-OH-dG positively correlated with those of k-ras (RS=0.643, P < 0.01), and p53 (RS=0.827, P < 0.01)u protein expression of k-ras positively correlated with that of p53 (RS=0.897, P < 0.01)., Conclusions: Protein expressions of 8-OH-dG, k-ras, and p53 are up-regulated in pleural effusion cells of lung cancer, and have mutual relations. They may be used as reference markers in diagnosing and screening for lung cancer.

Objective: To study the role of O(6)-methylguanine-DNA methyltransferase (hMGMT) in the development of human lung cancer., Methods: Reverse transcription-polymerase chain reaction (RT-PCR) method was applied to measure hMGMT mRNA expression in 150 lung cancer specimens, 40 normal lung tissues, and in the peripheral mononuclear blood cells from 50 lung cancer cases and 50 normal controls. The protein expressions of p53, C-MYC and K-RAS were assessed by immuno-histochemistry. The effects of some exposure factors on the expression of hMGMT gene were analyzed. The relationships between hMGMT gene and cancer related genes p53, C-MYC and K-RAS were investigated., Results: The mRNA of hMGMT was low or absent in 49 of 150 (32.7%) lung cancer specimens, whereas 2 of 40 (5%) normal lung tissues had reduced the levels of hMGMT mRNA. The low expression of hMGMT seemed to be a risk factor of lung cancer, with a OR of 9.22 (2.05-57.65). Reduced expression levels of hMGMT mRNA were observed in 10 of 50 (20%) lung cancer patients' peripheral mononuclear blood cells, and 2 of 50 (4%) blood cells among normal controls. When investigating the exposure factors which affecting the expression of hMGMT gene, we noticed that smoking was suppressing the expression of hMGMT gene. Interestingly, over-expression of K-RAS oncogene was significantly correlated with low expression of hMGMT (P < 0.05). However, the expressions of p53 and C-myc were not correlated with the status of hMGMT gene., Conclusion: hMGMT might play an important role in the development of human lung cancer. Low expression of hMGMT gene seemed to be a risk factor for lung cancer which could be used as a valuable biomarker on susceptibility of human lung cancers.