Metabolomics study of rat tail vibration model / 环境与职业医学

Background The metabolites and metabolic pathways of hand-arm vibration syndrome have not yet been elucidated. Objective To investigate the effect of local vibration on endogenous metabolites in rat serum by metabolomic analysis, to preliminarily explore the potential metabolic pathway of endogenous metabolites, so as to provide evidence for further research on the mechanism of hand-arm vibration syndrome. Methods Thirty-two SPF male SD rats, (211.3±11.1) g, 7−8 weeks of age, were selected and randomly divided into three groups: control group (14 rats, without vibration), 7 d vibration group (9 rats, continuously vibration for 7 d), and 14 d vibration group (9 rats, continuous vibration for 14 d). The vibration rats were vibrated every day for 4 h, the frequency weighted acceleration was 4.9 m·s−2, the vibration frequency was 125 Hz, and the vibration direction was one-way vertical vibration. The control group had the same conditions except not contacting vibration. After the vibration exposure, the blood samples taken from the abnormal aorta of rats were collected, and the changes of rat serum metabolome were analyzed by ultra-performance liquid chromatography-tandem time-of-flight mass spectrometry. Principal components analysis (PCA) was used to explore changes in rat serum metabolic profile, and orthogonal partial least squares-discriminant analysis (OPLS-DA) was used to screen out differential metabolites. Combined with online databases, a metabolic pathway enrichment analysis of differential metabolites was performed. Results The PCA analysis showed that compared with the control group, the rat serum metabolic profiles in the 7 d group and the 14 d group were clearly differentiated, and the rat serum metabolic profiles in the 7 d group and the 14 d group partially overlapped. The OPLS-DA analysis showed significant differences between groups. The main parameters were: model interpretation rate R2Y=0.914, model predictive ability Q2=0.58. The OPLS-DA analysis screened out 26 and 119 differential metabolites from the 7 d group and the 14 d group respectively, and there were 24 common differential metabolites between the 7 d group and the 14 d group. The metabolomic pathway analysis showed that local vibration-induced changes in rat serum metabolism were mainly related to arachidonic acid metabolism in the 14 d group, among which the metabolites with significant effects were arachidonic acid, prostaglandin E2, and prostaglandin D2. Conclusion Local vibration could affect the normal metabolism in rats, and the metabolic pathway with significant influence is arachidonic acid metabolism after a 14 d exposure and the involved metabolites are arachidonic acid, prostaglandin E2, and prostaglandin D2.

Expression changes of prostacyclin and thromboxane in blood of rats with tail vibration / 环境与职业医学

Background Long-term exposure to hand-transmitted vibration can lead to hand-arm vibration syndrome, one manifestation of which is impaired peripheral blood circulation in the arms. Altered expressions of prostacyclin I2 (PGI2) and thromboxane A2 (TXA2) in blood may be one of the important mechanisms of vibration-induced hand-arm vibration syndrome. Objective To reveal the effects of rat tail vibration on the expressions of PGI2 and TXA2 in plasma, and to establish the correlation between the change of rat plasma PGI2 to TXA2 ratio and rat tail vibration. Methods Fifty SPF-grade male SD rats were randomly divided into five groups: control group, 1 d exposure group, 3 d exposure group, 7 d exposure group, and 14 d exposure group, with 10 rats in each group. The rats were placed in rat immobilizes on a immobilization table, and the rats' tails were connected to a shaker and fixed with medical tape. There was no overlap between the immobilizes and between the rats' tails by no contact between the immobilization table and the shaker. The exposure dose was 125 Hz, 5.9 m·s−2, 4 h·d−1, and the vibration direction was linear vertical vibration. Abdominal aortic blood was taken at the end of vibration exposure, and the expressions of PGI2, TXA2, and their hydrolysates 6-keto-prostaglandin F1α (6-keto-PGF1α) and thromboxane B2 (TXB2) were measured by enzyme-linked immunosorbent assay, and the 6-keto-PGF1α/TXB2 values were calculated. Spearman rank correlation was used to analyze whether the expression of vascular factors correlated with the accumulated time of vibration. Results The expression levels of plasma 6-keto-PGF1α were (896.12±124.37), (1068.13±119.41), (1215.26±122.64), and (1317.94±106.54) ng·L−1 in the 1 d, 3 d, 7 d, and 14 d groups of rats, respectively, which were higher than that in the control group, (830.60±109.47) ng·L−1 (P<0.001). The PGI2 expression levels were (86.49±2.40), (107.90±2.65), (114.02±2.16), and (126.95±1.94) ng·L−1 in the 1 d, 3 d, 7 d, and 14 d groups of rats, respectively, all higher than (60.09±2.11) ng·L−1 in the control group (P＜0.001). The expression levels of TXB2 were (132.14±4.10), (145.52±4.09), (179.91±4.98), and (204.10±3.22) ng·L−1 in the 1 d, 3 d, 7 d, and 14 d groups of rats, respectively, which were higher than that in the control group, (106.08±3.26) ng·L−1 (P<0.001). The expression levels of plasma TXA2 were (211.99±3.24), (236.33±3.88), and (245.45±4.23) ng·L−1 in rats in the 3 d, 7 d, and 14 d groups, respectively, which were all elevated compared with (174.79±4.19) ng·L−1 in the control group (P<0.001). Compared with the control group, the 6-keto-PGF1α/TXB2 values were decreased in the 7 d and 14 d groups (P<0.05). The 6-keto-PGF1α, PGI2, TXB2, and TXA2 expressions were positively correlated with vibration accumulation time (r=0.84, 0.84, 0.80, 0.84, P<0.001) and the 6-keto-PGF1α/TXB2 values were negatively correlated with vibration accumulation time (r=-0.24, P=0.003). Conclusion Local exposure of rat tail to vibration could increase the expressions of PGI2 and TXA2 in blood, and the elevated expressions show a dose-effect relationship with the duration of vibration exposure, but the PGI2/TXA2 tends to decrease with the accumulation of vibration exposure.

Effects of vibration on expressions of vascular endothelial inflammatory factors and IncRNA MEG3 in vitro / 环境与职业医学

Background Prolonged exposure to vibration can cause vascular endothelial injury, and inflammatory response plays an important role in vascular endothelial injury. Studies have shown that long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) is involved in regulating the expression of inflammatory injury of endothelial cells. Objective To investigate the effects of vibration on the secretion of inflammatory factors and the expression of IncRNA MEG3 by vascular endothelial cells in vitro. Methods Human umbilical vein endothelial cells (HUVEC) were divided into two categories: vibration and control. The vibration exposure included 63 Hz (6.76 m·s−2), 200 Hz (5.08 m·s−2), and 250 Hz (4.56 m·s−2) frequency bands, and 1 and 2 d exposure time with 1 to 4 h of daily vibration. The control treatment was the same as the vibration category except that they were not exposed to vibration. CCK-8 was used to detect the effects of different vibration frequencies and time on the viability of HUVEC. The expression levels of tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8), interleukin-4 (IL-4), and interleukin-10 (IL-10) in the cells and supernatants were detected by enzyme-linked immunosorbent assay. The expression levels of IncRNA MEG3 were detected by real-time fluorescence quantitative PCR. Results Compared with the cells with the control treatment, the cell viability of the 1-day exposure group increased after 1.5 h and 3 h of vibration at 63 Hz, while decreased after 2 h and 2.5 h; the cell viability of the 2-day exposure group increased at the frequency of 63 Hz for 1.5 h, but decreased at 2 h and 2.5 h. At the frequency of 200 Hz, the cell viability of the 1-day exposure group increased at 2 h and 4 h, but decreased at 2.5 h and 3 h; the cell viability of the 2-day exposure group increased at 1.5 h and decreased at 2.5 h. For the vibration exposure at frequency of 250 Hz, the cell viability of the 1-day exposure group increased at 1.5 h and 2.5 h, but decreased at 3 h; of the 2-day exposure group, the cell viability increased at 1.5 h and decreased at 3 h. For the exposure settings of 63 and 200 Hz vibration for 2.5 h and 250 Hz vibration for 3 h, and with the control treatment as reference, the expression levels of TNF-α, IL-8, IL-4, and IL-10 in cells and supernatants were increased in the 1 d and 2 d exposures; the expression level of lncRNA MEG3 decreased in the 1 d exposure group; however, for the 2 d exposure, the expression level of lncRNA MEG3 decreased only in the 63 Hz vibration exposure. All of these results were statistically significant (P<0.05). Conclusion Vibration could induce an increase in the levels of inflammatory factors TNF-α, IL-8, IL-4, and IL-10 and a decrease in the expression level of lncRNA MEG3 in vascular endothelial cells in vitro.

Correlation between hand-arm vibration disease and vasoactive factors / 环境与职业医学

Background Hand-arm vibration disease (HAVD) is a chronic progressive disease caused by long-term exposure to hand-transmitted vibration, but the mechanism by which vibration affects peripheral vascular function of fingers is not completely clear. Objective To study the association between vasoactive factors and HAVD, and to screen specific indicators for its early diagnosis and prevention. Methods Judgmental sampling method was used to select workers with (HAVD group) and without HAVD (vibration contact group), and non-hand-transmitted vibration operation workers (control group), with 60 workers in each group. The levels of leukotriene B4 (LTB4), vascular endothelial growth factor (VEGF), 5-hydroxy tryptamine (5-HT), interleukin-1β (IL-1β), and calcitonin gene-related peptide (CGRP) in plasma of the three groups were measured by enzyme-linked immunosorbent assay. The association between vasoactive factors and HAVD was analyzed using logistic regression, and the diagnostic HAVD indicators were screened by receiver operator characteristic (ROC) curve of a multivariate model indicator \begin{document}$ \widehat{Y} $\end{document}. Results The hand symptom rates of the HAVD group, the vibration contact group, and the control group were 26.7%, 66.7%, and 96.7% respectively, with a significant difference (P<0.05). The levels of LTB4, 5-HT, IL-1β, and CGRP in the HAVD group were the highest followed by the vibration contact group, and lowest levels were in the control group (P<0.05). There was no significant difference in the VEGF level among the three groups (P>0.05). The logistic regression results showed that higher levels of LTB4 (OR=1.048, 95%CI: 1.022-1.076), 5-HT (OR=1.011, 95%CI: 1.004-1.018), IL-1β (OR=1.148, 95%CI: 1.071-1.230), and CGRP (OR=1.055, 95%CI: 1.008-1.104) were associated with a higher risk of HAVD (P<0.05). The order of the potential indicators' area under the ROC curve from high to low was:\begin{document}$ \widehat{Y} $\end{document} (0.969) > IL-1β (0.907) > LTB4 (0.876) > 5-HT (0.858) > CGRP (0.836). Conclusion The expression levels of LTB4, 5-HT, IL-1β, and CGRP are altered with occupational exposure in hand-transmitted vibration operations and may be associated with HAVD; VEGF is not found to be associated with HAVD. The accuracy of early screening for HAVD can be improved by combining the monitoring of various biochemical indicators.

Peripheral circulation and peripheral nerve injury in workers exposed to vibration at two different frequencies / 环境与职业医学

Background Hand-arm vibration disease is harmful to human body, but there are no effective diagnosis and treatment so far, and current occupational exposure limits underestimate the health damage caused by high-frequency vibration exposure. Objective To evaluate and compare the damage to workers' peripheral circulation and peripheral nerve caused by different frequencies of vibration operation. Methods Drilling workers (n=187) from a mining company in Shandong Province and golf club head grinding workers (n=228) from a sports equipment factory in Guangdong Province were selected as study subjects. Hand symptoms were investigated. SV106 vibration meter was used to measure the target operation-associated vibration frequency spectrum. The 8 h energy-equivalent frequency weighted acceleration, cumulative vibration exposure level (CVEL), and the working age related to causing white finger in 10% of an exposed group were calculated. Result The study subjects were all male. More grinding workers reported hand symptoms than the drilling workers, e.g. peripheral circulation injury (52.6% vs 19.3%), peripheral nerve injury (71.5% vs 23.0%), hand stiffness (64.0% vs 7.0%), and deformed fingers (69.7% vs 4.3%) (all P<0.001). The main vibration frequencies of grinding operation (500-800 Hz) were much higher than those of drilling operation (125~160 Hz). CVEL and working age of vibration exposure showed a linear rising relationship with the cumulative prevalence rate of peripheral circulation and peripheral never injury, the fitting lines all showed good fitting effects (R2=0.812-0.988), and the slope of the fitting line of the grinding workers was larger than that of the drilling workers. The working age of vibration exposure associated with 10% cumulative prevalence of white finger was shorter in the grinding workers than in the drilling workers (6.81 years vs 10.27 years). According to the ISO prediction formula, the working age of vibration exposure was associated with 10% white finger prevalence shorter in the drilling workers than in the grinding workers (3.12 years vs 8.23 years). Conclusion Both the vibration exposure level and the prevalence of hand symptoms are high in two groups of workers with different vibration frequencies, and vibration exposure at a higher frequency tends to have severer damage to workers' hands.

Application and effect of aerobic exercise of pulmonary rehabilitation in patients with chronic obstructive pulmonary disease / 中国医师进修杂志

Objective To investigate the application and effect of aerobic exercise of pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD).Methods Ninety-four hospitalized patients with COPD from June 2011 to June 2012 were enrolled.The clinical curative effect and safety of aerobic exercise of pulmonary rehabilitation in patients with COPD were observed and compared.Results After 3 months treatment,first second forced expiratory volume (FEV1) and forced vital capacity (FVC) were increased compared with those before treatment [(3.25 ± 0.49) L vs.(2.59 ± 0.55) L,(1.95 ± 0.41) L vs.(1.44 ± 0.48) L],and there were significant differences (P ＜ 0.05).There was no significant difference in FEV1/FVC before and after treatment (P ＞ 0.05).After 3 months treatment,arterial partial pressure of oxygen and arterial oxygen saturation were increased compared with those before treatment [(87.61 ± 8.56) mm Hg(1 mm Hg =0.133 kPa) vs.(63.88 ± 8.79) mm Hg,0.9648 ±0.0449 vs.0.7632 ± 0.0477],partial pressure of arterial carbon dioxide was decreased compared with that before treatment [(30.57 ± 9.47) mm Hg vs.(49.23 ± 9.54) mm Hg],and there were significant differences (P ＜ 0.05).There was no signifi.cant difference in blood pressure and heart rate before and after treatment (P＞ 0.05).No obvious adverse reactions were observed.Conclusions The aerobic exercise of pulmonary rehabilitation can improve significantly lung function.It is safe and rehable,and has less adverse reaction in patients with COPD.It is worthy of promotion and use.

An improved adaptive spectral clustering for image segmentation / 南方医科大学学报

<p><b>OBJECTIVE</b>To propose an improved adaptive spectral clustering method for image segmentation to allow automatic selection of the optimal scaling parameters and enhance the accuracy of spectral clustering.</p><p><b>METHODS</b>Using constrain conditions for optimizing the criterion function and determining the optimal scaling parameters by iteration, the final image segmentation was achieved through spectral clustering based on Nystrom approximation. We chose suit weight functions for different texture images, and used the proposed method for image segmentation. The k-means algorithm and the method of spectral clustering after pre-segmentation by manually choosing the scaling parameter were compared with the proposed method.</p><p><b>RESULTS</b>The improved spectral clustering algorithm with automatic selection of the optimal scaling parameters achieved better results of image segmentation than the other two methods.</p><p><b>CONCLUSION</b>The proposed algorithm can improve the accuracy of spectral clustering for image segmentation.</p>