Microstructure and Mechanical Behavior of Porous Ti–6Al–4V Processed by Spherical Powder Sintering

Reducing the stiffness of titanium is an important issue to improve the behavior of this material when working together with bone, which can be achieved by generating a porous structure. The aim of this research was to analyze the porosity and mechanical behavior of Ti–6Al–4V porous samples developed by spherical powder sintering. Four different microsphere sizes were sintered at temperatures ranging from 1300 to 1400 °C for 2, 4 and 8 h. An open, interconnected porosity was obtained, with mean pore sizes ranging from 54.6 to 140 µm. The stiffness of the samples diminished by as much as 40% when compared to that of solid material and the mechanical properties were affected mainly by powder particles size. Bending strengths ranging from 48 to 320 MPa and compressive strengths from 51 to 255 MPa were obtained.     

A new space of the face: The bucco‐mandibular space

Our previous studies based on intraoral dissection of fresh cadavers demonstrated the fissure and loose connective tissues behind the mucosa between the incisivus labii inferioris (ILI) and buccinator (BM) muscles. However, this raised new questions about the relationship among these muscles, the fissure and the buccal space. To our knowledge, no pathway to the oral cavity from the buccal space has been previously demonstrated, although such a pathway would better explain some routes of infection. Therefore, the aim of this study was to clarify the relationship among the mimetic muscles attached to the mandible, the fissure, and the buccal space. Twenty sides from 10 fresh frozen adult cadaveric Caucasian heads were used. The relationships among the ILI, BM, mandible, and buccal space were investigated with dissection and fluoroscopy. In all specimens, the fissure between the lateral border of the ILI and the anterior border of the BM formed the entrance of a space (here termed the bucco‐mandibular space), which corresponded to the buccal mucosa in the premolar region. The superior border of this space was formed by the platysma and associated fascia, which was continuous with the masseteric fascia. This fascia clearly separated this space from the buccal space, which was located lateral to the BM and superior to this space. Clin. Anat. 30:958–962, 2017. © 2017 Wiley Periodicals, Inc.     

Skeletal muscle growth defect in human growth hormone transgenic rat is accompanied by phenotypic changes in progenitor cells

Growth hormone (GH) is known to have a pivotal role in the maintenance of skeletal muscle mass. Sarcopenia, the loss of skeletal muscle mass, is a common phenomenon in aging, and it is widely accepted that sarcopenia is largely attributed to age-related decline in GH secretion. In the present study, we tested if human growth hormone transgenic rats (GH-TG rats) whose plasma GH levels are maintained relatively low could be an appropriate model for sarcopenia. Analyses of GH-TG rats revealed that they exhibit skeletal muscle growth defect as well as atrophy of myofibers. The number of myofibers in tibialis anterior muscle was comparable to that of WT rats, while the proportion of type I slow myofibers in tibialis anterior muscle was increased in GH-TG rats after 5 months. Neither increased expression of ubiquitin ligases, MuRF1 and MAFbx, nor indication of apoptotic cell death was observed. Notably, myogenic differentiation potential of skeletal muscle progenitor cells in GH-TG rats was lower than WT rats, and this was accompanied by increased adipogenic potential. These results indicate that GH-TG rats could be a useful model to elucidate the mechanism of sarcopenia induced by reduced GH action and raised the possibility that decreased GH action may cause an alteration of differentiation potential of skeletal muscle progenitor cells.