Circadian Disruption Accelerates Tumor Growth and Angio/Stromagenesis through a Wnt Signaling Pathway

Epidemiologic studies show a high incidence of cancer in shift workers, suggesting a possible relationship between circadian rhythms and tumorigenesis. However, the precise molecular mechanism played by circadian rhythms in tumor progression is not known. To identify the possible mechanisms underlying tumor progression related to circadian rhythms, we set up nude mouse xenograft models. HeLa cells were injected in nude mice and nude mice were moved to two different cases, one case is exposed to a 24-hour light cycle (L/L), the other is a more “normal” 12-hour light/dark cycle (L/D). We found a significant increase in tumor volume in the L/L group compared with the L/D group. In addition, tumor microvessels and stroma were strongly increased in L/L mice. Although there was a hypervascularization in L/L tumors, there was no associated increase in the production of vascular endothelial cell growth factor (VEGF). DNA microarray analysis showed enhanced expression of WNT10A, and our subsequent study revealed that WNT10A stimulates the growth of both microvascular endothelial cells and fibroblasts in tumors from light-stressed mice, along with marked increases in angio/stromagenesis. Only the tumor stroma stained positive for WNT10A and WNT10A is also highly expressed in keloid dermal fibroblasts but not in normal dermal fibroblasts indicated that WNT10A may be a novel angio/stromagenic growth factor. These findings suggest that circadian disruption induces the progression of malignant tumors via a Wnt signaling pathway

Characterization and modelling the mechanical behaviour of poly (l-lactic acid) for the manufacture of bioresorbable vascular scaffolds by stretch blow moulding

Bioresorbable Vascular Scaffolds (BVS) manufactured from poly (l-lactic acid) (PLLA) offer an alternative to metal scaffolds for the treatment of coronary heart disease. One of the key steps in the manufacture of these scaffolds is the stretch blow moulding process where the PLLA is biaxially stretched above glass transition temperature (Tg), inducing biaxial orientation and thus increasing ductility, strength and stiffness. To optimise the manufacture and performance of these scaffolds it is important to understand the influence of temperature and strain rate on the constitutive behaviour of PLLA in the blow moulding process. Experiments have been performed on samples of PLLA on a custom built biaxial stretch testing machine to replicate conditions typically experienced during blow moulding i.e. in a temperature range from 70 °C to 100 °C and at strain rates of 1 s−1, 4 s−1 and 16 s−1 respectively. The data is subsequently used to calibrate a nonlinear viscoelastic material model to represent the deformation behaviour of PLLA in the blow moulding process. The results highlight the significance of temperature and strain rate on the yielding and strain hardening behaviour of PLLA and the ability of the selected model to capture it

Lamellar Thickening Growth of an Isolated Extended Chain Single Crystal of PE

A newly recognized mode of growth of polyethylene (PE) has been studied using in-situ optical microscopy and transmission electron microscopy. When PE was crystd. from the melt into the mobile hexagonal phase, an isolated extended-chain single crystal (ESCS) was formed via a folded chain single crystal by growing into two directions simultaneously, namely perpendicular and parallel to the chain axis. This indicates two different growth mechanisms; one is the well-known lateral growth and the other the newly recognized growth mode one which the authors termed \"lamellar thickening growth\". Lamellar thickness of an isolated ESCS increased linearly with time and the \"lamellar thickening growth rate derived therefrom increased linearly with increase of the degree of supercooling. [on SciFinder (R)

Lamellar Thickening Growth of an Isolated Extended Chain Single Crystal of PE

A newly recognized mode of growth of polyethylene (PE) has been studied using in-situ optical microscopy and transmission electron microscopy. When PE was crystd. from the melt into the mobile hexagonal phase, an isolated extended-chain single crystal (ESCS) was formed via a folded chain single crystal by growing into two directions simultaneously, namely perpendicular and parallel to the chain axis. This indicates two different growth mechanisms; one is the well-known lateral growth and the other the newly recognized growth mode one which the authors termed \"lamellar thickening growth\". Lamellar thickness of an isolated ESCS increased linearly with time and the \"lamellar thickening growth rate derived therefrom increased linearly with increase of the degree of supercooling. [on SciFinder (R)