Little is known about the precise mechanical stimuli that cells sense and respond to as they maintain or refashion the extracellular matrix in multiaxially loaded native or bioengineered tissues. Such information would benefit many areas of research involving soft tissues, including tissue morphogenesis, wound healing, and tissue engineering. A custom tissue culture device has been constructed that can impart well-defined biaxial stretches on cruciform-shaped, fibroblast-seeded collagen gels and be mounted on the stage of a nonlinear optical microscopy (NLOM) system for microscopic characterization of matrix organization. The cruciform geometry permitted direct comparison of matrix (re-)organization within regions of the collagen gel exposed to either uniaxial or biaxial boundary conditions and examination by NLOM for up to 6 days. In addition, sequential NLOM measurements of collagen fiber orientations within gels while stretched, unloaded, or decellularized delineated contributions of applied stretches, cell-mediated tractions, and matrix remodeling on the measured distributions. The integration of intravital NLOM with novel bioreactors enables visualization of dynamic tissue properties in culture.

Objective: To determine the prevalence and severity of impacted permanent mandibular second molars (MdM2s) in the general population of Taiwan as well as to evaluate treatment outcomes with an innovative method for impacted MdM2s. Materials and Methods: Dental records of 21,580 patients were retrospectively screened in this study. The impactions of MdM2s were registered. The chosen study population consisted of 96 patients with 125 impacted MdM2s who received orthodontic treatment in our clinics. Standardized periapical radiographs were taken to measure the angles and depths of the impacted MdM2s. In addition, the initial uprighting periods of the impacted MdM2s were recorded. Results: The prevalence of MdM2 impaction in the Taiwanese population was 0.65%. Most of the angles and depths of the MdM2s were 31–60° and 9–12 mm, respectively. The mean initial uprighting period of the impacted MdM2 was 3.6 months. There were no significant differences between genders in the initial uprighting period based on patient ages, impacted angles, or impacted depths ( P > .05). Correlation analysis revealed that the impacted depth was highly and positively correlated with the initial uprighting period ( r > .75). Conclusions: The prevalence of MdM2 impaction in this study was low but slightly higher than previous reports investigating whites. Although such impactions are rare, it is recommended to diagnose early for an optimal treatment time and reduction of complications. In addition, the effective molar uprighting appliance used in this study has displayed good treatment outcomes with natural improvement of the adjacent infrabony defects of the first molars.

Arteries undergo marked structural and functional changes in human and experimental hypertension that generally involve smooth muscle cell (SMC) hypertrophy/hyperplasia as well as abnormal extracellular matrix turnover. In this study we examined time courses of changes in SMC activity and matrix protein content in a novel mini-pig aortic coarctation model. Cell proliferation was evaluated by immunostaining of Ki-67, apoptosis was assessed by TUNEL, and phenotypic changes were monitored by immunostaining three SMC contractile markers (caldesmon, calponin, and smoothelin). Changes in medial collagen and elastin were examined by picrosirius red and Verhoeff–van Gieson staining, respectively. LabVIEW-based image analysis routines were developed to objectively and efficiently quantify the (immuno)histochemical results. We found that significant cell proliferation and matrix production occurred in the early stages of this coarctation model and then declined gradually; the SMCs also tended to exhibit a less contractile phenotype following these cellular and extracellular changes. Specifically, different aspects of the phenotypic changes associated with hypertension occurred at different rates: cell proliferation and collagen production occurred early and peaked by 2 weeks, whereas changes in contractile protein expression continued to decrease over the entire 8-week study period. Temporal changes found in this study emphasize the importance of simultaneously tracing time courses of SMC growth and differentiation as well as matrix protein production and content. SMCs are multifunctional, and caution must be used to not overdefine phenotype. This manuscript contains online supplemental material at http://www.jhc.org . Please visit this article online to view these materials.