Upregulation of Cx43 Expression Under Stretch Condition is Mediated by TGF Beta1 and Cytoskeletal Network

Many physiological and pathophysiological processes in cells or tissues are involving mechanical stretch, which is inducing gap junction gene expression and cytokine TGF beta changes. However, the underlying mechanisms of gap junction gene expression changes remain unknown. Here, we showed that the expression of Cx43 at mRNA and protein level in Human umbilical-vein endothelial cells (HUVECs) is significantly increased after 24 h stretch stimulation, and TGF beta1, but not TGF beta2 expression is also upregulated. Administration of TGF betal into HUVECs without stretch also induced upregulation of Cx43 mRNA and protein expression. While simultaneously administration of TGF beta1 with SB431542, a specific inhibitor of TGF beta1 receptor, blocked the Cx43 protein upregulation by TGF beta1. Further, the increase of Cx43 protein expression under stretch condition can be partially blocked by SB431542; moreover, it also can be partially blocked by simultaneously administration of anti-TGF beta1 monoclonal neutralization antibody. Importantly, the stretch induced upregulation of Cx43 can be blocked by administration of actin and microtubule inhibitors, while NEDD4, a key element in mediating Cx43 protein ubiquitination and degradation, is not changed under stretch condition. Therefore, we conclude that upregulation of Cx43 expression under 24 h stretch condition is mediated by TGF beta1 via TGF beta1 receptor signaling pathway, and it also involves the actin and microtubule cytoskeletal network.

3D Finite Element Analysis of Marine Diesel Engine Connecting Rod

In this paper, with the ANSYS, stress distribution and safety factor of marine diesel engine connecting rod were analyzed by using 3D finite element method. The results show that the position of maximum principal stress is transition location of small end and connecting rod shank at maximum stretch condition. The value of stress is 24.69 MPa in dangerous position. The position of maximum principal stress is transition location of small end and connecting rod shank at maximum stretch condition. The value of stress is 198.65 MPa in dangerous position. Safety factor is 2.51.

Finite Element Analysis and Structural Improvement of S195 Diesel Engine Connecting Rod

In this paper, with the ANSYS, stress distribution and safety factor of connecting rod were analyzed by using 3D finite element method. The results show that the oil-hole of small end and medial surface of connecting rod shank are the exposed destructive positions at maximum compression condition. Maximum stress value is 214 MPa. Safety factor is 1.64. The oil-hole of small end and the transition location of small end are the exposed destructive positions at maximum stretch condition. Maximum stress value is 97.2MPa. Safety factor is 3.63. Based on the analysis, the structure of connecting rod is improved. Safety factor of connecting rod increase.

Stretch Exercises Increase Tolerance to Stretch in Patients With Chronic Musculoskeletal Pain: A Randomized Controlled Trial

Background: Stretch is commonly prescribed as part of physical rehabilitation in pain management programs, yet little is known about its effectiveness.Objective: A randomized controlled trial was conducted to investigate the effects of a 3-week stretch program on muscle extensibility and stretch tolerance in patients with chronic musculoskeletal pain.Design: A within-subject design was used, with one leg of each participant randomly allocated to an experimental (stretch) condition and the other leg randomly allocated to a control (no-stretch) condition.Patients and Setting: Thirty adults with pain of musculoskeletal origin persisting for at least 3 months were recruited from patients enrolled in a multidisciplinary pain management program at a hospital in Sydney, Australia.Intervention: The hamstring muscles of the experimental leg were stretched daily for 1 minute over 3 weeks; the control leg was not stretched. This intervention was embedded within a pain management program and supervised by physical therapists.Measurements: Primary outcomes were muscle extensibility and stretch tolerance, which were reflected by passive hip flexion angles measured with standardized and nonstandardized torques, respectively. Initial measurements were taken before the first stretch on day 1, and final measurements were taken 1 to 2 days after the last stretch. A blinded assessor was used for testing.Results: Stretch did not increase muscle extensibility (mean between-group difference in hip flexion was 1°, 95% confidence interval=−2° to 4°), but it did improve stretch tolerance (mean between-group difference in hip flexion was 8°, 95% confidence interval=5° to 10°).Conclusion: Three weeks of stretch increases tolerance to the discomfort associated with stretch but does not change muscle extensibility in patients with chronic musculoskeletal pain.

Effect of Proprioceptive Neuromuscular Facilitation Stretch Techniques on Trained and Untrained Older Adults

The effects of proprioceptive neuromuscular facilitation (PNF) on joint range of motion (ROM) for older adults are unknown, and few studies have investigated changes in joint ROM associated with age. This study examined PNF stretch techniques' effects on knee-joint ROM in trained (T) and untrained (UT) older adults. Knee-joint ROM was tested in T and UT adults age 45–55 and 65–75 years using 3 PNF stretch techniques: static stretch (SS), contract-relax (CR). and agonist contract-relax (ACR). The 45–55 UT group achieved significantly more ROM than did the 65–75 UT group, suggesting an age-related decline in ROM. The 65–75 T group achieved significantly greater knee-extension ROM than did their UT counterparts, indicating a training-related response to PNF stretch techniques and that lifetime training might counteract age-related declines in joint ROM. The ACR-PNF stretch condition produced 4–6° more ROM than did CR and SS for all groups except the 65–75 UT group, possibly as a result of lack of neuromuscular control or muscle strength.

Flammability Measurements of Difluoromethane

Difluoromethane (CH2F2, or R-32) is a candidate to replace ozone-depleting chlorofluorocarbon refrigerants. Because CH2F2 is flammable, it is necessary to assess the hazard posed by a leak in a refrigeration machine. The currently accepted method for determining flammability, ASTM E 681 has difficulty discerning the flammability boundary for weak fuels such as CH2F2. This article describes an alternative approach to identify the limits of flammability, using a twin, premixed counterflow flame. By using the extinction of an already established flame, the point dividing flammable from nonflammable becomes unambiguous. The limiting extinction mixture changes with stretch rate, so it is convenient to report the flammability limit as the value extrapolated to a zero stretch condition. In the burner, contoured nozzles with outlet diameters of 12 mm are aligned counter to each other and spaced 12 mm apart. The lean flammability limit of CH2F2 in dry air at room temperature was previously reported by the authors to be a mole fraction of 0.14, using the twin counterflow flame method. In the current study, relative humidity was not found to affect the lean limit. Increasing the temperature of the premixed fuel and air to 100°C is shown to extend the flammability limit in the lean direction to 0.13. The rich limit of CH2F2 found using the counterflow method is around 0.27. The uncertainties of the measurements are presented and the results compared to data in the literature. [S0022-1481(00)02501-9]