[Effects of individual factors and labor organization on neck pain in auto assembler].

Objective: To investigate the influence of individual factors and labor organization on the prevalence of neck pain (hereinafter referred to as neck pain) in automotive assemblers, and to provide a basis for enterprises to optimize neck pain interventions. Methods: A cluster random sampling method was taken in January 2021, at an automobile manufacturing plant in Shiyan, 656 assemblers with ≥1.0 years of service were selected, the "Musculoskeletal Disorder Questionnaire" was used to investigate the incidence and influencing factors of neck pain. Pearson χ(2) test or trend χ(2) test was used to compare the data rates. The influencing factors of neck pain were analyzed by multivariate logistic regression. Results: The prevalence rate of neck pain (hereinafter referred to as the prevalence rate of neck pain) of automobile assemblers within one year was 53.94% (342/634) . The prevalence of neck pain in women was higher than that in men (69.1% vs 48.6%, P<0.01) . The prevalence of neck pain was related to length of service, self-assessment of fatigue, working hours per week, working in the same workshop, rest days per shift, and accumulated rest time per shift (P<0.05) . Multivariate logistic regression analysis showed that the risk of neck pain in women was 2.434 times higher than that in men; The risk of neck pain increased by 18.9% for each hour of work per week; Rest during work was a protective factor for neck pain. The number of rest per shift increased and the risk of neck pain decreased (r=0.405, 0.311, 0.302, 95%CI=0.205~0.803, 0.169~0.572, 0.142~0.642, P<0.05) . Conclusion: The annual prevalence of neck pain was higher in automobile assemblers. Enterprises should fully consider the influencing factors such as gender, working hours per week and the number of breaks when arranging production.

[Investigation on high-frequency hearing loss of noise workers in an automobile factory].

Objective: To investigate the high-frequency hearing loss (HFHL) of workers in an automobile factory and its influencing factors, so as to provide a scientific basis for occupational health management of noise workers. Methods: From March to July 2019, 2647 workers from an automobile factory were selected as the research objects by cluster sampling method. The basic personal information (such as gender, age, education level, height, weight, etc.) , history of ear disease, the history of detonation, history of exposure to ototoxic drugs, history of exposure to occupational noise, etc., were investigated by questionnaire and occupational health examination. Chi-square test was used to compare the detection rates of HFHL in different populations, and multivariate logistic regression model was used to analyze the influencing factors of HFHL. Results: The noise level of 2647 individual workers ranged from 75.0 dB (A) to 92.0 dB (A) , with an average of (84.14±2.47) dB (A) . The detection rate of HFHL was 17.2% (456/2647) . There were significant differences in the the detection rate of HFHL among workers of different gender, age, educational level, working age, noise exposure level, diabetes history, detonation history, smoking and drinking workers (P<0.05) . Multivariate logistic regression analysis showed that male, age ≥30 years old, smoking and noise exposure were risk factors for HFHL (P<0.05) . Conclusion: The detection rate of HFHL in automobile factory workers is high. Gender, age, smoking and noise are the influencing factors of HFHL. It is necessary to strengthen the noise control in the workplace and guide workers to choose healthy lifestyle.

[Study on the effects of noise on hypertension and hyperglycemia among occupational workers].

Objective: To study the effect of noise on hypertension and hyperglycemia among occupational workers. Methods: Total 670 workers in an automobile manufacturing company were selected as the subjects of physical examination in 2017. According to the noise exposure or not, the subjects were divided into control group (no noise exposure) 143 and contact group (noise exposure) 527. Questionnaire survey and physical examination were conducted. The measurement data were analyzed by t-test, and the count data and grade data were analyzed by χ(2) test. The influence of noise on blood glucose, heart rate, blood pressure and other indicators was analyzed by logistic regression, and the OR and 95%CI of each risk factor were calculated. Results: The average age of the control group and the contact group was no significant difference (P>0.05) . There were 139 (20.7%) cases of high systolic pressure, 154 (23.0%) cases of high diastolic pressure, 63 (9.4%) cases of hyperglycemia, 29 (4.3%) cases of tachycardia. Compared with the control group, there were significant differences in systolic blood pressure, diastolic blood pressure and blood glucose in the contact group (P<0.05) . Compared with the control group, the systolic blood pressure, diastolic blood pressure and blood glucose of the subjects in the corresponding age contact group increased significantly (P<0.05) . The years of noise exposure were protective factors for systolic and diastolic blood pressure (OR=0.970, 0.973) . Conclusion: Noise exposure may increase blood pressure and blood sugar of occupational workers, but the effect on heart rate can not be determined.

Plasma fractionation by dead-end membrane filtration: effects of membrane properties and plasma flux.

Plasma fractionation by membrane filtration permits the reinfusion of the patient with his own albumin. In this study, the influence of membrane nature and plasma flux on plasma fractionation in dead-end mode is investigated with acetate hollow fiber filters. It is found that transmembrane pressure TMP rises exponentially with time, the rate of increase being proportional to plasma flux. The faster TMP rises, the faster the drop in sieving coefficient SC. It is also found that albumin SC is a function of TMP and not of plasma flux. Theoretical analysis of the dead-end filtration was performed. This theoretical model indicates that the observed variation of TMP with time is consistent with the assumptions that pore volume decreases proportionally to the filtrate plasma volume.

Modelling of plasma-separation through microporous membranes.

Available mathematical models of ultrafiltration have been used to predict changes in maximum plasma filtration rate with wall shear rate for given filters and blood properties. We have done many plasmapheresis experiments in vitro, using hollow-fiber filters (500-1000 cm2) and fresh bovine blood collected on ACD or heparin. The comparison between predicted and experimentally obtained filtration rates was good for models based on the concentration polarization theory and lift velocity theory. In other experiments with pulsatile inlet flow we found that plasma filtration rate increased by 20 to 50% compared to non-pulsatile conditions. These results are in good agreement with the modified model of ultrafiltration incorporating pulsating flow. This paper presents relationships between plasma filtration velocity (steady and pulsating flow) and hemolysis limit as a function of wall shear rate and filter size.

Comparison of polyamide and polypropylene membranes for plasma separation.

Plasma separation experiments were made with polyamide experimental prototype hollow-fiber plasma filters with surface areas between 0.025 m2 and 0.1090 m2 using bovine blood collected in acid citrate dextrose (ACD). The maximum filtration velocity rose with the wall shear rate gamma w as gamma w 0.72 +/- 0.02 and decreased with the length of fiber L as L-0.41 with a correlation coefficient of 0.97 +/- 0.02. The results were similar to those with polypropylene fibers. We also investigated the occurrence of hemolysis as a function of shear rate and transmembrane pressure. The free hemoglobin concentration of filtered plasma was checked using a U.V. spectrophotometer. It was concluded that polyamide membrane filters can be safely used for plasma separation from blood.

Hemolysis reduction in plasmapheresis by module design: operating with pulsed flow filtration enhancement.

This study is an investigation into the effects of module design on hemolysis levels during the filtration enhancement of plasmapheresis using pulsed blood flow. Two polypropylene hollow fiber modules (F1 and F2) were compared under steady and pulsed flow conditions. The fiber lengths and membrane areas of the respective filters were 136 mm, 0.1 m2 and 226 mm, 0.25 m2 and were used at wall shear rates of 400 and 600 s-1. Fresh citrated bovine blood was circulated at 90 ml/min through their fibers with permate and retentate being recirculated. Plasma samples were analysed by the Cripps method to obtain the mean free hemoglobin concentration. A comparison of the average hemoglobin released with time per fiber, and per unit length allowed an assessment of the effects of fiber length and shear rate on hemolysis levels. It was concluded that a reduction in area and fiber length would reduce hemolysis levels and design equations are suggested to find the optimum length.

Repression of NFAT3 transcriptional activity by estrogen receptors.

Nuclear factor of activated T cells 3 (NFAT3) activities have been implicated in many biological processes, such as breast cancer, cardiac hypertrophy, learning and memory, and adipocyte differentiation. However, how protein factors regulate NFAT3 transcriptional activity is poorly understood. Here, we report that regardless of estrogen, overexpression of estrogen receptor alpha and beta (ERalpha and ERbeta) suppresses NFAT3 transcriptional activity, whereas knockdown of endogenous ERalpha and ERbeta enhances the activity. Estrogen further enhances ER inhibition of NFAT3-dependent transcription. ERalpha and ERbeta interact with NFAT3 independently of the NFAT agonists phorbol myristate acetate (PMA) and ionomycin, and ERalpha is recruited to an NFAT3 target gene promoter. Phosphorylation of ERalpha at different sites differentially affects ERalpha modulation of NFAT3 transcriptional activity. These results suggest that ER may play a critical role in regulation of NFAT3 transcriptional activity.

High shear rate hemofiltration: influence of fiber dimensions and shear rates.

The variation of ultrafiltration flow rate (QF) at high transmembrane pressure with inlet wall shear rate (gamma w) was found to be proportional to gamma wn, with n ranging from 0.45 to 0.55, when gamma w increases up to 4,500 s-1. To test whether long filters operated at high shear rates were more efficient than shorter ones for the same inlet blood flow, we made experiments with 10- and 20-cm filters with same number of fibers (550) at various shear rates from 700 to 3,000 s-1. The filtration rates provided by the 20-cm filter were found to be 5-15% larger than those provided by two 10-cm filters arranged in parallel and 10-20% smaller than those provided by two 10-cm filters arranged in a series. The explanation lies in the rapid decay of QF with distance from the inlet due to the developing concentration boundary layer. When pulsations are imposed on the inlet blood flow, the filtration rate was seen to increase by 10-20%, and the effect of plugging was seen to decrease in small-area hemofilters.

Simultaneous convective and diffusive mass transfers in a hemodialyser.

The mass transfer in a hemodialyser in the presence of combined dialysis and ultrafiltration has been calculated by integration of mass fluxes across the boundary layers in blood and dialysate phase taking into account the partial rejection of solute as well as changes in local blood flow and ultrafiltration flux along the membrane. Clearances of creatinin, vitamin B12, and myoglobin have been calculated as a function of blood and ultrafiltrate flow rate and were found to be in good agreement with in vitro measurements. The data suggest the following empirical correlation for the hemodiafiltration clearance.

Effect of membrane characteristics on the performance of Couette rotating plasma separation devices.

The concept of a cylindrical membrane rotating at high speed inside a concentric cylinder (Couette flow device) has proved to be very efficient for plasma separation from whole blood. The authors show that its high filtration velocity (about 0.5-0.6 cm/min) is due to the presence of Taylor vortices in the blood-filled annular gap, which greatly increase the shear rates, but not radial migration of formed elements under centrifugal forces. The variation of filtrate velocity with transmembrane pressure (ptm) markedly depends upon the type of membrane. With a 0.8 micron polycarbonate membrane and bovine blood at 40% hematocrit, the filtration velocity reaches a peak equal to 0.6 cm/min at 3,000 rpm, then decreases to 80 mmHg, reaching a plateau of 0.35 cm/min independent of ptm. With a nylon membrane of 0.5 micron pores under the same conditions, the filtration velocity does not present a peak, but rises continuously to reach a 90 mmHg plateau equal to 0.5 cm/min. Similar behavior, but with lower plateaus, is also obtained with polycarbonate membranes at pore sizes below 0.4 microns. At 3,000 rpm, hemolysis occurs if ptm exceeds 750 mmHg, far above the operating range.

Rationale of filtration enhancement in membrane plasmapheresis by pulsatile blood flow.

It has been demonstrated in our laboratory that blood flow pulsations enhance plasma filtration rate by 30-60 per cent. The increase in plasmafiltration over the steady flow value is found to be a function of the parameter F. delta V'/QB where F denotes the pulsation frequency, delta V' the volume amplitude of pulsed blood in the filter and QB is the time mean blood flow. The increment in plasma filtration may be related to the increase in time-mean absolute value of shear rate.

Microfiltration and ultrafiltration of polysaccharides produced by fermentation using a rotating disk dynamic filtration system.

The recovery of exopolysaccharides (EPS) produced by Sinorhizobium meliloti bacteria by dynamic microfiltration was investigated using a rotating disk device designed in our laboratory, equipped with a 0.2 microm nylon membrane. This system differs from commercially available systems by the presence of vanes on the disk which produce a very important increase in permeate flux while yielding excellent EPS transmission. For polymers produced under standard fermentation conditions (70 h at 30 degrees C), the mass flux rose to 650 g h(-1) m(-2) using a disk equipped with 2 mm vanes rotating at 2000 rpm against 380 g h(-1) m(-2) with a smooth disk at the same speed. The maximum flux observed was 1560 g h(-1) m(-2) with a 6-mm vanes disk rotating at 3000 rpm and a 36 degrees C broth. An interesting finding was that the permeate flux J(f) for various disks can be correlated by the same function of the mean shear stress at the membrane tau(wm) according to J(f) = 4.6 tau(wm) (0.717) for a 30 degrees C broth, showing that the effect of vanes is merely to increase the shear stress by raising the fluid core velocity between the membrane and the disk. With 6-mm vanes the core angular velocity was found to be 84% of disk velocity vs. 45% for a smooth disk. When the fermentation temperature was increased to 36 degrees C to produce a lower molecular weight polymer, the permeate flux rose by about 250%, much more than what could be expected from the reduction in permeate viscosity and followed the same power law with membrane shear stress as for 30 degrees C. The same device was equipped with a PES 50 kDa membrane to concentrate EPS by ultrafiltration. Permeate fluxes were of the order of 160 L h(-1) m(-2) at 2000 rpm and 30 degrees C with nearly complete EPS rejection. Finally, the net electrical power consumed by the disk was measured by subtracting the power consumed without fluid from the power during filtration at the same speed. This power increases with speed and with the presence of vanes, but since the gain provided by the vanes is very high, the specific energy per m(3) of permeate is minimal with the highest vanes tested (6 mm) and maximal for smooth disks.

A speedy method to detect inserted DNA fragment in cell lines transfected with retroviral vectors.

Cells transfected by retroviral vectors are brought in agene of particular interest and are very useful in avariety of experiments. It is essential to testify that theDNA fragment was successfully introduced into the cellstogether with the retroviral vectors. Polymerase chainreaction is believed to be a fast and convenient method forthis purpose when using primers flanking the cloning siteof the inserted DNA. Unfortunately, a single PCR reactionoften fails to amplify the targeted fragment because of theexistence of endogenous virus DNA in cell genome. However,in this study we conducted a procedure for a single PCR,using vector-specific primers as well as a nested PCR, andsuccessfully detected the DNA fragments cloned in MFGretroviral vectors in 22 transfected cell lines. We alsoproved that real time quantitative PCR in combination withMFG-specific primer is useful to determine copy number ofthe retroviral vector in murine producer cell lines.

Membrane plasma separation through small-area, hollow-fiber filters.

The filtration capabilities of small polypropylene hollow-fiber plasma filters with membrane areas ranging from 100 to 1,000 cm2 have been investigated. It is found that the filtration flux per unit membrane area is approximately proportional to the wall shear rate gamma w at least up to gamma w = 7,500 s-1. As a result, the total filtration flow rate increases very little when the number of fibers is increased as the increase in membrane area is offset by the decrease in shear rate, but it increases with the fiber length L as L 2/3. Hemolysis occurs when the transmembrane pressure exceeds a certain threshold, but this threshold is itself an increasing function of shear rate. As a result, it is possible to circulate high blood flow rates even in very small filters (100 cm2) without hemolysis, provided the fiber length is below a critical value.

Effects of naloxone on tissue oxygen supply and somatosensory evoked potentials in cat brain during focal cerebral ischemia.

The effects of naloxone on local tissue oxygen partial pressure (pO2) and on the somatosensory evoked potentials (SEP) were studied in the brain of cat during focal cerebral ischemia. Ischemia, produced by clamping of the middle cerebral artery (MCA) by a transorbital approach, was performed in two series of cats for 3 h. In one group of cats (n = 5), naloxone 5 mg.kg-1 was injected i.v. 0.5 h after clamping. The pO2 was continuously recorded on different depths (0-5000 microns) of the median gyrus by a polarographic oxygen microelectrode. After MCA clamping, pO2 (depth of 0-1000 microns) decreased markedly and hypoxia occurred in the ischemic area. But in the deeper brain (1001-5000 microns) pO2 did not change significantly. The amplitude of SEP decreased after MCA clamping, while the conduction time of SEP did not significantly decrease. The mean pO2 values in the ischemic area were increased as compared to the control group after naloxone, especially at the depths of 0-1000 microns, and the hypoxia was improved. The amplitude of SEP was increased after naloxone in comparison to the situation of ischemia without naloxone. The conduction time of SEP was not improved significantly. We conclude that naloxone can improve the oxygen supply and the electrical activity of neurons in the ischemic region of the brain.