Elasticity Estimates from Images of Crawling Waves Generated by Miniature Surface Sources

We describe a surface-based approach to the generation of shear wave interference patterns, called crawling waves (CrW), within a medium and derive local estimates of biomechanical properties of tissue. In previous experiments, elongated bars operating as vibration sources were used to generate CrW propagation in samples. In the present study, however, a pair of miniature circular vibration sources was applied to the overlying skin to generate the CrW within the medium. The shape and position of the miniature sources make this configuration more applicable for in vivo implementation. A modified ultrasound imaging system is used to display the CrW propagation. A shear speed mapping algorithm is developed using a detailed analysis of the CrW. The proposed setup is applied to several biomaterials including a homogeneous phantom, an inhomogeneous phantom and an ex vivo human liver. The data are analyzed using the mapping algorithm to reveal the biomechanical properties of the biomaterials.     

Cultured Human Periosteal-Derived Cells Have Inducible Adipogenic Activity and Can Also Differentiate Into Osteoblasts in a Perioxisome Proliferator-Activated Receptor-Mediated Fashion

We investigated the adipogenic activity of cultured human periosteal-derived cells and studied perioxisome proliferator-activated receptor (PPAR) ligand-mediated differentiation of cultured human periosteal-derived cells into osteoblasts. Periosteal-derived cells expressed adipogenic markers, including CCAAT/enhancer binding protein α (C/EBP- α), C/EBP-δ, aP2, leptin, LPL, and PPARγ. Lipid vesicles were formed in the cytoplasm of periosteal-derived cells. Thus, periosteal-derived cells have potential adipogenic activity. The PPARα and PPARγ agonists, WY14643 and pioglitazone, respectively, did not modulate alkaline phosphatase (ALP) activity in periosteal-derived cells during induced osteoblastic differentiation, however, the PPARα and PPARγ antagonists, GW6471 and T0070907, respectively, both decreased ALP activity in these cells. WY14643 did not affect, whereas pioglitazone enhanced, alizarin red-positive mineralization and calcium content in the periosteal-derived cells. GW6471 and T0070907 both decreased mineralization and calcium content. By RT-PCR, pioglitazone significantly increased ALP expression in periosteal-derived cells between culture day 3 and 2 weeks. Pioglitazone increased Runx2 expression after 3 days, which declined thereafter, but did not alter osteocalcin expression. Both of GW6471 and T0070907 decreased ALP mRNA expression. These results suggest that pioglitazone enhances osteoblastic differentiation of periosteal-derived cells by increasing Runx2 and ALP mRNA expression, and increasing mineralization. GW6471 and T0070907 inhibit osteoblastic differentiation of the periosteal-derived cells by decreasing ALP expression and mineralization in the periosteal-derived cells.In conclusion, although further study will be needed to clarify the mechanisms of PPAR-regulated osteogenesis, our results suggest that PPARγ agonist stimulates osteoblastic differentiation of cultured human periosteal-derived cells and PPARα and PPARγ antagonists inhibit osteoblastic differentiation in these cells.     

Cardiorespiratory fitness and incident metabolic syndrome in middle-aged Korean men

This study investigated the relationship of cardiorespiratory fitness (CRF) with incident metabolic syndrome in 810 middle aged Korean men. All subjects were free of metabolic syndrome at baseline examination. The metabolic syndrome was defined by NCEP criteria and CRF was directly measured by peak oxygen uptake during a treadmill test. During an average of 3.3 years of follow-up, 155 (19.1%) men developed the metabolic syndrome. The incidence of metabolic syndrome was inversely associated with CRF quartiles (p?相似文献   

Monte Carlo calculation of response functions to gamma-ray point sources for a spherical NaI(Tl) detector

Response functions of a 7.62 cm-diameter spherical NaI(Tl) detector to gamma-ray point sources in the energy range up to 1.5 MeV were calculated by means of the Monte Carlo method using PENELOPE-2006 (Salvat et al., 2006). The detector materials and dimensions were modeled realistically. The calculated response functions agreed well with the experimental spectra.