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At least 847 records · Page 47Linked to original sources
PubMed2005

[An experimental study on destruction of K562 and HL60 induced by 5-aminolaevulinic acid-based photodynamic therapy].

This experiment was designed to explore the pattern of K562 and HL60 leukemia cells death, the effects on their cell cycle and the cytoplasmic free calcium concentration ([Ca2+]i) induced by 5-aminolaevulinic acid-based photodynamic therapy (ALA-PDT). Under the transmission electron microscope (TEM), two kinds of leukemia cells' ultrastructure were observed. Flow cytometry combined with Annexin V-FITC/PI labeling was used to detect the pattern of K562 and HL60 cells' death induced by ALA-PDT. Flow cytometry combined with PI labeling was used to analyze the change in the cell cycle induced by ALA-PDT, and confocal laser scanning microscopy (CLSM) combining with calcium fluorescence probe was used to detect the change in the cytoplasmic free calcium concentration ([Ca2+]i). Immediately after irradiation, many typical apoptotic bodies were seen in the cells treated. Most of the cells treated were necrotic at 24 hours following irradiation. Flow cytometry analysis suggested that the main patterns of the cells' death were apoptosis immediately after irradiation and necrosis post-apoptosis at 24 hours post irradiation. Immediately and 24 hours after irradiation, the proportion of S phase of K562 was 57. 67% +/- 1.13% and 84.77% +/- 6.20% respectively, and the proportion of S phase of HL60 was 74.60% +/- 7.27% and 84.60% 1.74% respectively. Both [Ca+]i of the treated K562 and HL60 were increased obviously. In the best experiment condition, the initial pattern of the K562 and HL60 leukemia cells' death induced by PDT was apoptosis and the main pattern was necrosis post apoptosis. The two kinds of cells were arrested at S phase by ALA-PDT. During the death of the leukemia cells, the increase in intracellular free calcium concentration could be responsible for the ALA photodynamically induced damage to K562 and HL60 cells.

Aminolevulinic Acid↗
PubMed1990

Biocompatibility of zirconia dispersed hydroxyapatite ceramics.

Because of the lack of adequate strength and toughness, hydroxyapatite (HA) ceramic can not be used for a substitute for a bone and joint despite its excellent affinity for the bone. The present authors have succeeded in producing a new type of HA ceramic containing zirconia. This new ceramic material is superior to ordinary HA ceramic in quality and exceeds compact bone in bending strength and fracture toughness. The Young's modulus was about 3-4 times greater than that of compact bone. The new ceramic material contained either 1.6 or 50% of zirconia by volume and was produced using a special technique to disperse the metal dioxide. In order to assess their affinity for the bone, the new ceramic materials were implanted into rabbit femurs. Sections of the bones removed at different times after operation were prepared without decalcification and subjected to optical microscopy, scanning electronmicroscopy (SEM), and electron-probe X-ray microanalyser (EPMA). The formation of direct chemical bonds with the bone was seen without intervening membrane. Thus, the new ceramic material was shown to have an excellent affinity for the bone, comparable to that of ordinary HA ceramic.

Animals↗
PubMed1990

Shark tooth morphogenesis. An SEM and EDX analysis of enameloid and dentin development in various shark species.

The study provides a survey of shark tooth morphogenesis based on SEM and EDX analyses of whole tooth families in six shark species. The teeth, demonstrating different stages of development, were acid-etched and coated with palladium. Calcium content was determined semi-quantitatively by using the palladium coating as an internal standard. Due to the rapid development of the enameloid, all major events took place in the two or three youngest teeth of a tooth family. Enameloid appeared to develop as a transformation of the peripheral part of the dental papilla. Mineralization started immediately. Based on morphological criteria the middle zone of the enameloid was established at an early stage, excluding the possibility of an unambiguous centrifugal or centripetal direction of growth. Substantial mineral increase first occurred in the middle zone, spreading from the tooth tip toward the base. Dentin formed after the enameloid was completely established. Dentin formation started basally as a direct prolongation of the enameloid cap, then spreading toward the tooth tip, first along the edges. It is concluded that shark enameloid has a mesenchymal background, but a role played by the inner dental epithelium can not be excluded.

Amelogenesis↗
PubMed1990

[Monocrystalline aluminum dental implants in animals: a study of the peri-implant tissue].

After the extraction of two molars in a dog's jaw, a single crystal alumina screw was implanted. Monthly radiographs were taken and analyzed by means of a video display computer (VDC) to obtain densitometric informations about the interface. After one year implantation, the bone segment containing the prosthesis was fixed in 4% paraformaldehyde, embedded in methacrylate and sectioned by a microtome saw. The results in light microscopy with ordinary and polarized light, in SEM and X-ray microanalysis, show the presence of a thick connective tissue layer interposed between the screw and the bone. The histological findings confirm the results obtained through the VDC analysis of the radiographic images.

Absorptiometry, Photon↗
PubMed1981

The effect of monobasic sodium phosphate on statolith synthesis in aurelia.

The effect of monobasic sodium phosphate on statolith synthesis in Aurelia metamorphosing in artificial sea water (ASW) and in low sulfate ASW was determined. Phosphate enhances statolith synthesis in organisms metamorphosing in ASW and restores statolith numbers to normal or above in organisms developing in low sulfate ASW. A small amount of sulfate must be present in the medium along with phosphate during the time period of statolith synthesis for normal statolith formation. Apparently, neither sulfate nor phosphate is stored in the organisms during early strobilation for later use in statolith synthesis because pre-treatment of either ion in early strobilation followed by treatment with the other ion does not result in statolith formation. Calcifying vesicles of the rhopalia of organisms from low sulfate ASW are normal in number, acid phosphatase activity, and in ability to initiate mineralization (by forming minute statoliths). While phosphate is not incorporated directly into the statoliths, it contributes to an efficient uptake of calcium and sulfur into the cells and/or calcifying vesicles, stimulating growth of calcium sulfate dihydrate statoliths. The high efficiency of the phosphate effect in enhancing statolith synthesis intracellularly demonstrates that phosphate acts at the cellular level in the jellyfish calcification process and emphasizes that phosphate probably plays multiple roles in the calcification of higher organisms.

Animals↗
PubMed1983

Electron probe X-ray microanalysis of K, Rb, Cs, and T1 in cryosections of striated muscle.

Muscles containing the normal amount of K+ or loaded with Rb+, Cs+, or T1+ were cryofixed, cryosectioned and analysed by electron probe X-ray microanalysis. Previously reported results obtained with independent methods were confirmed: The alkali-metals and T1 are mainly localized in the A bands and at Z lines of the striated muscle. The results are in accordance with the association-induction hypothesis and the concept that K+ is physically adsorbed onto beta- and gamma-carboxyl side chains of myosin and other proteins.

Animals↗
PubMed1993

Aluminium in rat cerebellar neural cultures.

A systematic microchemical analysis of unstained and uncoated neurone cultures was performed with synchrotron radiation photoemission spectromicroscopy after exposure to an aluminium solution. Clear evidence was found for localized aluminium uptake in a few cells. Their possible identification based on morphology is discussed.

Aluminum↗