No abstract

Abstract— The in vivo administration of a single dose of morphine produces a decrease of tissue calcium in the rat brain. This decrease is observed to be linear, dose‐dependent, time‐dependent and to occur to an equal degree in 8 discrete brain regions. This effect of morphine is blocked by naloxone and exhibits a high degree of sterospecificity. The reserpine induced decrease of brain calcium was not antagonized by naloxone. Differentiation of this response using reserpine and naloxone indicates the possibility of calcium pools in the central nervous system. The results are discussed in terms of a specific effect of opiate drugs and the role of calcium in opiatereceptor interactions.

The clinical success of dental implants is governed by implant surfaces and bone cell responses that promote rapid osseointegration and long-term stability. The specific objective of this study was to investigate osteoblast precursor cell responses to hydroxyapatite (HA) surfaces of different treatments. Since the nature of bone cell responses in vitro is influenced by the properties of HA ceramics, this study was divided into two components: a chemical and crystallographic characterization of the HA ceramics and an in vitro cell culture study. The sintered HA samples were observed to have the highest crystallite size as compared to the as-received HA and calcined HA samples. No differences in the surface roughness and chemical composition were observed among the sintered, calcined, and as-received HA surfaces. In concurrence with the X-ray diffraction, high resolution XPS resolution of Ca 2p also indicated a higher crystallinity on sintered HA samples as compared to the calcined and as-received HA samples. As indicated by increased alkaline phosphatase-specific activity, increased cell-surface and matrix-associated protein, and 1.25 (OH2) vitamin D3-stimulated osteocalcin production, a more differentiated osteoblast-like phenotype was observed on the sintered HA surfaces compared to the as-received HA and calcined HA surfaces. An increased osteoblast-like cell activity on the sintered HA surfaces suggested that the crystallite size of HA surfaces may play an important role in governing cellular response.

No abstract

No abstract