[Further improvement of ergonomic applied studies in China].
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Ergonomics↗
Biomedical subjects
Lei Yang
Publications and source records attributed to Lei Yang.
[Maximum acceptable weight of lift for manual lifting tasks].
OBJECTIVE: To explore the maximum acceptable weight of lift (MAWL) in different lifting conditions and the suitable lifting equation for the stipulation of occupational health standard of manual lifting tasks in China. METHODS: The MAWL was investigated among the thirteen male and ten female students using psychophysical methodology and the recommended weight of limit (RWL) was compared. RESULTS: The MAWL of male and female subjects was decreased gradually with the increase of lifting height. Once the height of lifting was over shoulder, the MAWL was decreased dramatically. The RWL was greater than the MAWL at 25 cm horizontal distance in male subjects, but the RWL was smaller than the MAWL at the distance of 45 cm and 63 cm. The average MAWL of male subjects was 30.8% greater than that of female subjects. The MAWL was decreased gradually with increase of the horizontal distance at the same height of lifting. The result of the male subjects was consistent with that of the female subjects. For the asymmetric lifting tasks of the male subjects, the bigger the angle of rotation was, the less the MAWL became. The angle of rotation had negative correlation with the capability of lifting (r = -0.996 6, P < 0.01). When the subjects performed asymmetric lifting tasks, the RWL was smaller than the MAWL and the difference was significant. CONCLUSION: The revision is sufficient for the horizontal distance and asymmetric lifting in the NIOSH lifting equation, but it is not suitable for height, especially for the task of lifting over shoulder. The RWL for the task of lifting over shoulder should be lowered. The factor of gender should be taken into account in the lifting equation and the constant of gender S can be added. Then S = 1 for male while S = 0.692 for female.
Adult↗
[Evaluation of work load and related factors during asymmetric lifting with surface electromyography].
OBJECTIVE: To evaluate the work load and related factors for asymmetric lifting tasks using surface electromyography (EMG). METHODS: Thirteen male volunteers lifted loads of 6 and 13 kg at two speeds, in varying angles of trunk rotation, from floor to knuckle height, performing 16 lifting tasks. During lifting, surface electromyography signals from the erector spinae, bilaterally at level of T10 and L3, was continually recorded. The work load and related factors for asymmetric lifting tasks were evaluated by comparing the average amplitude of EMG signals. RESULTS: The EMG average amplitude when lifting the load of 13 kg (43.30% MVE) was significantly greater than that when lifting the load of 6 kg (37.70% MVE) (P < 0.01). The EMG average amplitude when lifting at the higher speed (41.80% MVE) was significantly greater than that at the lower speed (39.19% MVE) (P < 0.05). The EMG average amplitude was increased with the increase of the trunk rotation angle without significant difference (P > 0.05). At T10, the EMG average amplitude was greater on the right side than that on the left side (50.31% MVE and 25.88% MVE respectively) while at L3, it was on the contrary (45.60% MVE on the left and 40.22% MVE on the right respectively) (P < 0.01). Multiple stepwise regression analysis showed that the load of lifting was the factor contributing most to the EMG average amplitude followed by the lifting speed. CONCLUSION: The risk factors related to work load for asymmetric lifting tasks are mainly the load and the speed of lifting. The EMG activity between the right and left side of erector spinae is different during such lifting.
Adult↗
[Characteristics of surface electromyography and work load of the forearm extensors in repetitive wrist extending].
OBJECTIVE: To evaluate the influence of the frequency, the weight and the motion angle on the stress and the fatigue of the forearm extensors in repetitive wrist extending at low force loading level with surface electromyography (SEMG). METHODS: Sixteen male college student volunteers were recruited for the experiment. Eight tasks of wrist extending were performed for 20 minutes respectively in given weight (1.96, 4.90 N), frequency (8.0, 33.3 moves/minute) and motion angle (45 degrees, 90 degrees). The static wrist extending at the level of 20% maximum voluntary contraction (MVC) were performed before and after each task for 2 up to 3 seconds, and the SEMG signals of extensor carpi ulnaris muscle (ECU) and extensor digitorum (ED) were recorded and analyzed. RESULTS: The weight loading level was approximately equal to 1.40% or 3.50% of the MVC force. The mean power frequency (MPF) and the median frequency (MF) were decreased with the increase of 3 kinds of loading levels. The decrease of MPF of the muscle ED was significant (P < 0.05 or P < 0.01). The MF was decreased with the increase of angle and weight loading levels (P < 0.05 or P < 0.01). The root mean square (RMS) value of SEMG could be divided into 3 or 4 groups with significant difference. All three kinds of loads had positive correlation with amplitude of SEMG according to the stepwise regression analysis. CONCLUSION: The fatigue level of ED is the highest. The primary load factor for the forearm extensors is the frequency followed by the weight and the angle. MF, MPF and RMS can be used as sensitive indexes for evaluating the stress and the fatigue of the forearm extensors during repetitive performance at lower force loading level.
Adolescent↗
[Expression and diagnostic application of C4.4A protein in squamous cell carcinoma and adenocarcinoma].
OBJECTIVE: To investigate the diagnostic utility of C4.4A gene expression in discriminating a squamous cell carcinoma (SCC) from an adenocarcinoma by immunohistochemistry. METHODS: Immunohistochemical staining was performed to detect the expression of C4.4A protein in 157 cases of SCC and 177 cases of adenocarcinoma of various organs. RESULTS: Overall, 141 of 157 cases of SCC strongly expressed C4.4A protein. In contrast, only 8 of 177 adenocarcinomas showed partial or scattered cell expression of C4.4A protein. The statistic difference between the two groups was highly significant (chi(2) = 244.93, P = 0.000), and also when the tumors were stratified according to the degree of differentiation (P = 0.000). CONCLUSION: C4.4A protein expression may serve as a valuable tumor marker in discriminating a squamous cell carcinoma from an adenocarcinoma, and therefore, may greatly facilitate the differential diagnosis of an epithelial malignancy.
Adenocarcinoma↗
[Effect of erythromycin on apoptosis of epithelial cell in nasal polyps].
OBJECTIVE: To study the effect of erythromycin on apoptosis and expression of Bax and Bcl-2 of epithelial cell in nasal polyps. METHODS: Epithelial cells from thirty nasal polyps and fifteen inferior turbinates were cultured in Dulbecco Eagle and Ham F12 (1:1) and divided into two groups (one group were treated with Erythromycin). Apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling and expression of Bcl-2 and Bax detected by immunohistochemistry at 1, 3, 5 days after culture. RESULTS: The apoptosis indexes (AI) of epithelial cell in nasal polyps after cultured for 1, 3, 5 days with erythromycin were (33.23 +/- 6.50)%, (38.21 +/- 7.22)% and (52.63 +/- 7.86)% respectively. The AI of epithelial cell in inferior turbinates were (31.02 +/- 5.60)%, (32.13 +/- 7.15)% and (39.64 +/- 7.48)% respectively. There was significant difference between two groups at 5 day after culture (P < 0.05). Expression of Bax and Bcl-2 of epithelial cell was significantly higher in nasal polyps than that in inferior turbinates (P < 0.01). Expression of Bax of epithelial cell cultured with erythromycin was significantly higher than that in the controls (P < 0.05). Apoptosis was clearly promoted after 5 day culture with Erythromycin (P < 0.05). CONCLUSIONS: Erythromycin promoted expression of Bax and apoptosis of epithelial cell in nasal polyps.
Adolescent↗
[Determination of three endogenous hormones in Catharanthus roseus (L.) G. Don using solid-phase extraction and high performance liquid chromatography].
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Catharanthus↗
[Research on chondrogenic differentiation and immunologic response of allogeneic mesenchymal stem cells implanted into joint cavity].
OBJECTIVE: To evaluate the cartilage formation ability of allogeneic mesenchymal stem cells implanted into sheep joint cavity without the use of immunosuppressive therapy. METHODS: Allogeneic mesenchymal stem cells (MSCs) loaded onto porous beta-tricalcium phosphate ceramic (beta-TCP) were implanted into normal sheep joint cavity. A complete mismatch between donor stem cells and recipient sheep was confirmed by mixed lymphocyte reaction assays prior to implantation. Eight weeks after implantation, the implants were taken out for histological and immunohistochemical analysis. The histological results were compared with data derived from joint cavity implantation of autologous MSCs-ceramic composites and cell-free ceramics. The systemic immune response was evaluated by the analysis of recipient serum for production of antibodies against allogeneic cells. RESULTS: For implantation with allogeneic MSCs, no sign of adverse immune response was detected. Histologically, few inflammation cells infiltration occurred and no antibodies against allogeneic cells were detected. Neocartilage formation in implants loaded with either allogeneic or autologous mesenchymal stem cells was revealed by histochemical and immunohistochemical analysis. In implants without stem cells, no cartilage formation was detected. CONCLUSIONS: Allogeneic mesenchymal stem cells are capable of forming cartilage under the effect of joint cavity environment. Without the use of immunosuppressive therapy, allogeneic MSCs do not provoke an adverse immune response in vivo.
Animals↗
Synchronization on Erdös-Rényi networks.
In this Brief Report, by analyzing the spectral properties of the Laplacian matrix of Erdös-Rényi networks, we obtained the critical coupling strength of the complete synchronization analytically. In particular, for any size of the networks, when the average degree is greater than a threshold and the coupling strength is large enough, the networks can synchronize. Here, the threshold is determined by the value of the maximal Lyapunov exponent of each dynamical unit.
Journal Article↗
Origin and evolution of new exons in rodents.
Gene number difference among organisms demonstrates that new gene origination is a fundamental biological process in evolution. Exon shuffling has been universally observed in the formation of new genes. Yet to be learned are the ways new exons originate and evolve, and how often new exons appear. To address these questions, we identified 2695 newly evolved exons in the mouse and rat by comparing the expressed sequences of 12,419 orthologous genes between human and mouse, using 743,856 pig ESTs as the outgroup. The new exon origination rate is about 2.71 x 10(-3) per gene per million years. These new exons have markedly accelerated rates both of nonsynonymous substitutions and of insertions/deletions (indels). A much higher proportion of new exons have K(a)/K(s) ratios >1 (where K(a) is the nonsynonymous substitution rate and K(s) is the synonymous substitution rate) than do the old exons shared by human and mouse, implying a role of positive selection in the rapid evolution. The majority of these new exons have sequences unique in the genome, suggesting that most new exons might originate through "exonization" of intronic sequences. Most of the new exons appear to be alternative exons that are expressed at low levels.
Alternative Splicing↗
Comment on "Normal heat conductivity of the one-dimensional lattice with periodic potential of nearest-neighbor interaction".
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Journal Article↗
T-box genes coordinate regional rates of proliferation and regional specification during cardiogenesis.
Mutations in T-box genes are the cause of several congenital diseases and are implicated in cancer. Tbx20-null mice exhibit severely hypoplastic hearts and express Tbx2, which is normally restricted to outflow tract and atrioventricular canal, throughout the heart. Tbx20 mutant hearts closely resemble those seen in mice overexpressing Tbx2 in myocardium, suggesting that upregulation of Tbx2 can largely account for the cardiac phenotype in Tbx20-null mice. We provide evidence that Tbx2 is a direct target for repression by Tbx20 in developing heart. We have also found that Tbx2 directly binds to the Nmyc1 promoter in developing heart, and can repress expression of the Nmyc1 promoter in transient transfection studies. Repression of Nmyc1 (N-myc) by aberrantly regulated Tbx2 can account in part for the observed cardiac hypoplasia in Tbx20 mutants. Nmyc1 is required for growth and development of multiple organs, including the heart, and overexpression of Nmyc1 is associated with childhood tumors. Despite its clinical relevance, the factors that regulate Nmyc1 expression during development are unknown. Our data present a paradigm by which T-box proteins regulate regional differences in Nmyc1 expression and proliferation to effect organ morphogenesis. We present a model whereby Tbx2 directly represses Nmyc1 in outflow tract and atrioventricular canal of the developing heart, resulting in relatively low proliferation. In chamber myocardium, Tbx20 represses Tbx2, preventing repression of Nmyc1 and resulting in relatively high proliferation. In addition to its role in regulating regional proliferation, we have found that Tbx20 regulates expression of a number of genes that specify regional identity within the heart, thereby coordinating these two important aspects of organ development.
Animals↗
Clinical experience of 153 patients with posterior circulation aneurysms.
OBJECTIVE: To study the morbidity and mortality of patients with aneurysms of the posterior circulation (basilar-vertebral system) and investigate the natural history of these aneurysms without surgical intervention. METHODS: Of 1232 patients with intracranial aneurysms admitted to Tiantan Hospital from January 1990 to October 2001, 153 (12.4%) had aneurysms of the posterior circulation. Their clinical and angiographic data were reviewed retrospectively. Additionally, to June 2002, 38 of the cases managed without surgery have been followed by telephone and correspondence. For these patients, the annual aneurysm rupture rate was estimated in "person-years". RESULTS: Patients were aged 4-69 years (mean 40.8). The peak incidence was in the 5th decade. There were 88 males and 65 females. One hundred and two patients (66.7%) were treated surgically, and of these, 60 (58.8%) had an excellent outcome, 10 (9.8%) a good outcome, 29 (28.4%) a fair outcome and 3 (2.9%) died. The other 51 (33.3%) patients were treated conservatively for various reasons. Of these, 13 died of ruptured aneurysm in hospital. Ten of these patients had had a previous subarachnoid haemorrhage and 3 had not. The other 38 surviving, conservatively managed patients were followed for 5-95 months (mean 23). Of them, 3 (17.6%) died of aneurysmal rupture, giving an annual rupture rate of 9.2%, or 3/32.47 patient years. CONCLUSIONS: To prevent death and disability due to aneurysmal rupture, posterior circulation aneurysms should be treated aggressively.
Adolescent↗
SCF(beta-TrCP1) controls Smad4 protein stability in pancreatic cancer cells.
Smad4, also known as deleted in pancreatic carcinoma locus 4 (DPC4), is a critical co-factor in signal transduction pathways activated by transforming growth factor (TGF)-beta-related ligands that regulate cell growth and differentiation. Mutations in Smad4/DPC4 have been identified in approximately 50% of pancreatic adenocarcinomas. Here we report that SCF(beta-TrCP1), a ubiquitin (E3) ligase, is a critical determinant for Smad4 protein degradation in pancreatic cancer cells. We found that F-box protein beta-TrCP1 in this E3 ligase interacted with Smad4 and that SCF(beta-TrCP1) inhibited TGF-beta biological activity in pancreatic cancer cells by decreasing Smad4 stability. Very low Smad4 protein levels in human pancreatic ductal adenocarcinoma cells were observed by immunohistochemistry. By analyzing pancreatic tumor-derived Smad4 mutants, we found that most point-mutated Smad4 proteins, except those within or very close to a mutation cluster region, exhibited higher interaction affinity with beta-TrCP1 and significantly elevated protein ubiquitination by SCF(beta-TrCP1). Furthermore, AsPC-1 and Caco-2, two cancer cell lines harboring Smad4 point mutations, exhibited rapid Smad4 protein degradation due to the effect of SCF(beta-TrCP1). Both Smad4 levels and TGF-beta signaling were elevated by retrovirus-delivered beta-TrCP1 siRNA in pancreatic cancer cells. Therefore, inhibition of Smad4-specific E3 ligase might be a target for therapeutic intervention in pancreatic cancer.
Adenocarcinoma↗
Heat conduction in the Frenkel-Kontorova model.
Heat conduction is an old yet important problem. Since Fourier introduced the law bearing his name almost 200 years ago, a first-principle derivation of this simple law from statistical mechanics is still lacking. Worse still, the validity of this law in low dimensions, and the necessary and sufficient conditions for its validity are far from clear. In this paper we will review recent works on heat conduction in a simple nonintegrable model called the Frenkel-Kontorova model. The thermal conductivity of this model has been found to be finite. We will study the dependence of the thermal conductivity on the temperature and other parameters of the model such as the strength and the periodicity of the external potential. We will also discuss other related problems such as phase transitions and finite-size effects. The study of heat conduction is not only of theoretical interest but also of practical interest. We will show various recent designs of thermal rectifiers and thermal diodes by coupling nonlinear chains together. The study of heat conduction in low dimensions is also important to the understanding of the thermal properties of carbon nanotubes.
Electronics↗
[Effect of prostaglandin E2 and the tumor necrosis factor-alpha on second messenger of lung fibroblast].
OBJECTIVE: To Study the effect of prostaglandin E(2) (PGE(2)) combined with tumor necrosis factor-alpha (TNF-alpha) on the second messenger of mouse lung fibroblast in order to research new target point for cytokine to treatment of pneumoconiosis. METHODS: The lung fibroblasts of breed mouse were primarily cultured. 10 ng/ml TNF-alpha and 10 ng/ml TNF-alpha combined with PGE(2) of different doses were added to culture medium of fibroblasts. The gamma value and CPM value were respectively measured for second messenger of cAMP, cGMP and IP(3) of fibroblast by immune-radio assay at different observation time. RESULTS: When treated with 10 ng/ml TNF-alpha + 1,000 pg/ml PGE(2) at 120 s time points, the CPM value of IP(3) of fibroblast was the maximal value [(76.33 +/- 7.10) CPM]; when cAMP/cGMP ratio declined to 4.29 at 24 h time point, the effect of fibroblast proliferation was the strongest; when 10 ng/ml TNF-alpha + 500 pg/ml PGE(2), and 2 000 pg/ml PGE(2), the CPM value of IP(3) of fibroblast were 27.00 +/- 3.00 and 61.00 +/- 2.65 respectively at 120 s time point, cAMP/cGMP value were 3.50 and 9.83 respectively at 24 h, the effect on fibroblast proliferation were obviously lower. CONCLUSION: Certain dose of PGE(2) could raise the ratio of cAMP/cGMP of fibroblast, and antagonize the proliferation effect of TNF-alpha on fibroblast.
Animals↗
[Application of heart rate variability in evaluation of mental workload].
OBJECTIVE: To investigate if heart rate variability (HRV) can be used to evaluate mental workload. METHODS: Forty-six volunteers were selected to simulate mental work by inputting the random number through keyboards. ECG was recorded by Holter 8800 during the performance and transferred into digital signal. Total power (TP), low frequency (LF), high frequency (HF) were analysed by Holter software. RESULTS: Along with time, the inputting speed increased but accuracy decreased, and was positively correlated with TP, LF (r = 0.851 and 0.827 respectively, P < 0.05), showing a distinct dose-effect relationship. HRV values at rest were higher than during mental work [TP: (2 745.4 +/- 1 301.6) vs (686.2 +/- 420.7) ms(2)/Hz; HF: (670.6 +/- 393.8) vs (202.6 +/- 171.7) ms(2)/Hz; LF: (870.5 +/- 553.7) vs (206.0 +/- 187.9) ms(2)/Hz] indicating that they were decreased remarkably as the mental work started. Then, they were gradually increased with the workload (intensity and time) increased, but still at lower level. CONCLUSION: HRV may be used as a parameter to evaluate mental workload but the change pattern of HRV needs to study further.
Adult↗
[Study on biomarkers of silicosis and silica-exposed group].
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Adult↗