Structural, morphological and surface characteristics of two types of octacalcium phosphate-derived fluoride-containing apatitic calcium phosphates.

Octacalcium phosphate (OCP) has been reported to stimulate bone regeneration during hydrolysis into hydroxyapatite (HA). The present study was designed to characterize structural, morphological and surface properties of fluoride-containing apatitic calcium phosphates (CaP) obtained through OCP hydrolysis or direct precipitation of OCP in the presence of 12-230ppm of fluoride (F). The products were characterized by chemical analysis, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Fourier transform infrared spectroscopy (FTIR) as well as measurements of surface area, solubility, osteoblastic activities and bovine serum albumin (BSA) adsorption. XRD analysis re-confirmed that both preparations yielded more apatitic CaP with a higher concentration of F. However, the co-precipitated products (CF-CaP) maintained the properties of OCP, in particular the solubility, whereas the hydrolysis products (HF-CaP) had the characteristics of fluoridated apatite. The crystals of plate-like OCP were changed to the crystals of rod-like CF-CaP and small irregular HF-CaP with the advance of the hydrolysis. The SAED analysis detected both OCP and apatite crystals even in the most hydrolyzed CF-CaP. Mouse bone marrow stromal ST-2 cells grew better on CF-CaP compared with HF-CaP. BSA adsorption was inhibited on HF-CaP more than on CF-CaP. These results show that OCP produces physicochemically distinct apatitic fluoridated CaP during hydrolysis, regarding the structure, the crystal morphology and the protein adsorption, depending on the fluoride introduction route, which provides biologically interesting material.

Myelin-like structures seen intracellularly in renal tubule cells subjected to ischemia.

Renal cortex was studied during experimentally induced ischemia. A transient increase in anerobic glycolysis occurred with concomitant swelling of both the Golgi apparatus and mitochondria. These intracytoplasmic organelles underwent marked changes in their intracellular positions. Infolding of cytoplasmic membrane at the basal side of proximal tubule cells increased in complexity and proceeded to enclose various intracytoplasmic microorganelles such as mitochondria and the Golgi apparatus. Piling up in layers was particularly marked around mitochondria. This piling up appeared as myelin-like structures on the free surface of, and within, proximal tubule cells, and followed disruption of the brush border at the free surface. Histological examination of thin sections showed that the fused portions of this brush border were actually brush border cytoplasmic membrane piled up in layers giving the appearance of myelin-like structures. After two hours of ischemia, parts of the membrane of these myelin-like structures were disrupted. Large vacuoles developed and these were thought to be related to the large vacuoles seen during cell degeneration.

[In vivo distributions of 111In and/or 3H labeled lymphocyte in C3H/He mouse (author's transl)].

Although 99mTc and 51Cr have been used for lymphocyte labeling, these radionuclides have several disadvantages for study on immunological behaviour of lymphocyte; very high rate elution and low labeling efficiency for both radionuclides, and short half life for 99mTc. Indium-111 has quite suitable physical properties for clinical nuclear medicine, i.e. desirable photon energy (247,173 keV) and 2.8 day half life. 111In-oxine is lipid soluble and is known to pass through the cell membrane and attaches firmly to cytoplasmic component of the cell. On the other hand, 3H-thymidine is well known substance which incorporated to nucleic acid in the cell. In this study, distribution patterns of 111In-oxine and/or 3H-thymidine labeled lymphocyte in C3H/He mice were examined and the suitability of 111In-oxine labeled lymphocyte for radionuclide imaging in vivo was discussed. Thirty minutes after intravenous injection of 3H and/or 111In labeled lymphocyte, about 12% of lymphocyte were found in the lungs and rest of them were distributed mainly in the blood, kidneys and liver. After 24 hours the activity in the lung decreased markedly and the activity in the liver and kidneys increased with time. Between lymphocyte labeled with 111In-oxine and 3H-thymidine, there is not so much differences in terms of distribution patterns. From this study, it is concluded that the 111In-oxine labeled lymphocyte distributes in the same way as 3H labeled one, in spite of different labeling sites. This 111In-oxine labeling method can be used as a useful tool of radionuclide imaging in kinetic studies of lymphocyte in vivo.

Naloxone fails to antagonize halothane-induced depression of the longitudinal muscle of the guinea pig ileum.

The influence of halothane, or naloxone, or halothane followed by naloxone was investigated in the in vitro myenteric plexus longitudinal muscle preparation of the guinea pig ileum. Halothane alone in 1.5 to 2.0% (v/v) concentration caused about 50% depression of the twitch and decreased both spontaneous acetylcholine (ACh) release (p less than 0.02) and volley output of ACh (p less than 0.02). Very high concentrations (greater than 1 micron) of naloxone caused a nonspecific, postsynaptic depression of the twitch. Higher than 100 nM concentrations of naloxone increased spontaneous ACh release, but had no effect on the volley output of ACh. Over a wide concentration range, from 15 nM to 3 micron, naloxone did not antagonize in the longitudinal muscle preparation the effects of halothane on any of the parameters investigated. These findings indicate that the sites of action of halothane and naloxone in this preparation are not identical.