[Characteristics at different frequencies of hearing loss in noise exposure workers of the automobile manufacturing industry]

Objective: To analyze the effects of noise exposure on the hearing at different frequencies in workers from the automobile manufacturing industry. Methods: A total of 4723 noise workers in a large automobile manufacturing company in Guangzhou were chosen as the research object by using judgment sampling method between April and July, 2018, and carried out 0.5, 1.0, 2.0, 3.0, 4.0 and 6.0 kHz pure tone audiometry threshold to analyze the characteristics of the status of hearing loss at different frequencies and its relationship with the noise exposure time. Results: The detection rate of hearing loss in noise-exposed workers was 29.8% (1406/4723) . Among them, the binaural hearing loss was 21.2% (999/4723) , and single unilateral hearing loss accounted for 8.6% (407/4723) . The hearing loss detection rate of right ear was higher than that of the left ear (P<0.05) , especially in the 6.0 kHz (P<0.001) . The detection rate of increased speech frequency hearing threshold was 1.9% (90/4723) , and the detection rate of increased high-frequency hearing threshold was 28.9% (1366/4723) . The detection rate of increased threshold in both the left and the right ear increased with the increase of frequency (P<0.001) , the increased hearing threshold was the highest at the frequency of 6.0 kHz. The auditory threshold of left ear in 0.5 kHz were higher than that of right ear at the same frequency (P<0.05) . The detection rate of hearing loss increased with the increase of noise exposure time (P<0.001) , and the increased threshold of 3.0, 4.0 and 6.0 kHz from workers increased with the increase of noise exposure time (P<0.001) . Conclusion: There is a significant increased threshold in workers exposed to noise frequency of 6.0 kHz, right ear is more easily damaged than left ear, there is a dose-response relationship for the noise exposure time and high-frequency hearing loss.

[Analysis of factors affecting the noise-induced high frequency hearing loss of male workers in a vehicle manufacturing enterprise]

Objective: To analyze the relationships between the exposure of occupational noise and the occurrence of noise-induced high frequency hearing loss in automobile manufacturing industry. Methods: From June to November 2017, 1579 male workers were selected for exposure to noise hazards in the automobile manufacturing industry in Guangzhou for more than one year (including one year) using the convenient sampling method. According to the hearing test results, 276 people in the high frequency hearing loss group and 1303 in the normal hearing group were surveyed, occupational health tests were conducted, and the noise intensity in the workplace was measured. The cumulative noise exposure (CNE) was calculated. The relationship between shift work and high frequency hearing loss of noise work is analyzed. Results: Compared with the normal hearing group, the noise exposure intensity, age, length of service, marital status, working system, and physical exercise of the high frequency hearing loss group were statistically significant (P<0.05). Through logistic regression analysis, after correcting the effects of organic solvent contact, marital status, and physical exercise, CNE, age, and shift operations (double-shift operations, three-shift operations) are the risk factors for high frequency hearing loss to occur. Conclusion: The risk of hearing loss of workers exposed to noise in the whole vehicle manufacturing industry may be related to CNE, age, and shift work. Two-shift and three-shift work are possible risk factors for noise-induced high frequency hearing loss.

[Analysis of the prevalence and related risk factors of prostate diseases in traffic policemen]

Objective: To investigate the prevalence and related risk factors of prostate diseases in traffic policemen. Methods: A total of 848 traffic policemen who took part in the physical examination among August and September in 2016 were selected as research subjects, and a questionnaire survey was conducted to collect their information including smoking, alcohol drinking, biological and physiological indicators, as well as prostate disease etc. The relationship between the prevalence of prostate diseases and related risk factors was analyzed by Non-conditional Logistic Regression. Results: The total prostate disease prevalence rate was 40.2% in the study subjects, and there is statistical significance (P<0.05) of differences between prostate disease group and non disease group in age, work age, smoking, drinking and field work. Single factor analysis showed that age, work age, smoking, and field work are independent risk factors of prostate disease (P<0.05) . Multivariate Logistic regression analysis showed that increasing age (OR 1.03) , smoking (OR 1.92) and field work time (OR 1.47) significantly increased the risk of prostate disease in male police after age, smoking, drinking, BMI, systolic blood pressure, diastolic blood pressure, fasting blood glucose, blood lipids and other indicators were adjusted. Conclusion: age, smoking and field work time are risk factors of prostate diseases in the traffic police. There is great significance in publicizing the harmful effects of smoking and reducing the duration of field work.

Reaction kinetics for the solid state synthesis of the AlH3/MgCl2 nano-composite by mechanical milling

The process of mechanical milling has been proved to be a cost-effective way to synthesize the AlH3/MgCl2 nano-composite by using MgH2 and AlCl3 as reagents. However, so far there is no comprehensive knowledge of the kinetics of this process. In an effort to predict the reaction progress and optimize the milling parameters, the kinetics of the synthesis of the AlH3/MgCl2 nano-composite by mechanical milling of MgH2 and AlCl3 is experimentally investigated in the present work. The reaction progress or the transformation fraction upon milling for different times is evaluated using the isothermal hydrogen desorption test of the as-milled samples at 220 °C, which is much lower than the threshold temperature for the de-hydriding of the reagent MgH2 but enough for the de-hydriding of the as-synthesized nano-sized AlH3. The effects of milling parameters on the reaction kinetics as well as the underlying mechanism are discussed by referring to the mechanical energy input intensity, the vial temperature and the Gibbs free energy change for the reaction. Furthermore, it is found that the Johnson-Mehl-Avrami (JMA) model can well describe the kinetics theoretically. By fitting the experimental data with the JMA expression, the theoretical kinetics expressions, the equation parameters, and the activation energy are obtained.

HIF-1α downregulates miR-17/20a directly targeting p21 and STAT3: a role in myeloid leukemic cell differentiation

Hypoxia-inducible factor 1 (HIF-1) is a crucial transcription factor for the cellular adaptive response to hypoxia, which contributes to multiple events in cancer biology. MicroRNAs (miRNAs) are involved in almost all cellular activities such as differentiation, proliferation, and apoptosis. In this work, we use miRNA microarrays to profile miRNA expression in acute myeloid leukemia (AML) cells with inducible HIF-1α expression, and identify 19 differentially expressed miRNAs. Our study shows that HIF-1α represses the expression of miR-17 and miR-20a by downregulating c-Myc expression. These two miRNAs alleviate hypoxia and HIF-1α-induced differentiation of AML cells. More intriguingly, miR-17 and miR-20a directly inhibit the p21 and STAT3 (signal transducer and activator of transcription 3) expression, both of which can reverse miR-17/miR-20a-mediated abrogation of HIF-1α-induced differentiation. Moreover, we show in vivo that miR-20a contributes to HIF-1α-induced differentiation of leukemic cells. Taken together, our results suggest that HIF-1α regulates the miRNA network to interfere with AML cell differentiation, representing a novel molecular mechanism for HIF-1-mediated anti-leukemic action.

[Calcium distribution changes during epididymal maturation of mouse and guinea pig sperms]

Calcium was localized by in situ precipitation with potassium antimonate during epididymal maturation of the mouse and guinea pig sperms. In caput epididymis the calcium in mouse sperm head was mainly localized on the inner surface of tha outer acrosomal membrane (OAM) in preacrosomal region. During the passage from the caput epididymis to the cauda epididymis the calcium amount of mouse sperm did not undergo apparent changes. In comparison with mouse sperm, there were a few fine calcium deposite granules on the inner surface of the guinea pig sperm OAM on the abdomen side at the caput epididymis stage, but these granules disappeared at the cauda epididymis stage. The microvilli of columnar cell in columnar epithlium lining the epididymal duct are probably involved in regultion of Ca2+ concentration of the intraluminal fluid. The calcium precipitation granules distributing in the microvilli were observed. An abundance of Ca2+ were present in the intraluminal fluid of the corpus epididymis and they might have some important functions during the process of sperm maturation. Calcium in sperm tail was mainly distributed in the mitochondria. Compared with the mouse sperm, the mitochondria of guinea pig sperm possessed more calcium.

Study on in vitro sperm capacitation and egg-penetration of giant panda

A preliminary report on in vitro sperm capacitation and egg-penetration of giant panda is briefly presented. The panda spermatozoon consists of head, neck and tail, just like the spermatozoa of other animals. Before capacitation sperm heads clustered together and dispersed after capacitation. They were then able to swim straight forward. During the time of in vitro capacitation the plasma membrane of the sperm head was first expanded to various degrees, then disintegrated, and finally became detached. The electro-dense material in the acrosome appeared in small clumps with high density. Extensive vesiculation occurred between the bi-layered acrosome membranes and thus led to disintegration. Vesiculation in panda sperm differs from that reported in hamsters. When the capacitated panda spermatozoa came into contact with the hamster eggs, the region between the acrosome collar and postacrosome cap first fused with the egg membrane followed by the penetration of the nucleus into the cortex of the egg. Some of the penetrating sperm nuclei became decondensed and some did not. The success of in vitro sperm capacitation and egg-penetration of giant panda is of great significance, suggesting that it is possible to carry out in vitro fertilization and embryo transplantation in this endangered species.