Calcification during bone healing in a standardised rat calvarial defect assessed by micro-CT and SEM-EDX.

OBJECTIVE: The study was designed to investigate the process of calcification during bone healing in a standardized rat calvarial bone defect model, measured by bone mineral density and the concentrations and distributions of calcium, phosphorus and carbon in the bone matrix. MATERIALS AND METHODS: A standard defect was made on the parietal bone of 12-week-old rats under anaesthesia. The rats were fixed in weeks 1, 2, 4 and 8,and the calvaria were resected and examined with microcomputed tomography, then frozen and sectioned for histology and analysed with energy-dispersive X-ray spectroscopy (EDX). Parietal bone of 12-week-old control rats was processed similarly. RESULTS: The mineral density of healing bone increased with time. The healing bone became thicker and denser with time in histology. The distributions of Ca and P expanded over the bone matrix, whereas that of C became localised and complemented that of C and P. The Ca/P concentration ratio increased, whereas the C/Ca and C/P ratios decreased in the healing bone matrix. CONCLUSION: Healing bone is immaturely calcified initially and proceeds calcification gradually, that is, as the bone volume increases, mineral increases in density and matures in quality, while organic components decrease.

Temperature-controlled interaction of thermosensitive polymer-modified cationic liposomes with negatively charged phospholipid membranes.

To obtain cationic liposomes of which affinity to negatively charged membranes can be controlled by temperature, cationic liposomes consisting of 3beta-[N-(N', N'-dimethylaminoethane)carbamoyl]cholesterol and dioleoylphosphatidylethanolamine were modified with poly(N-acryloylpyrrolidine), which is a thermosensitive polymer exhibiting a lower critical solution temperature (LCST) at ca. 52 degrees C. The unmodified cationic liposomes did not change its zeta potential between 20-60 degrees C. The polymer-modified cationic liposomes revealed much lower zeta potential values below the LCST of the polymer than the unmodified cationic liposomes. However, their zeta potential increased significantly above this temperature. The unmodified cationic liposomes formed aggregates and fused intensively with anionic liposomes consisting of egg yolk phosphatidylcholine and phosphatidic acid in the region of 20-60 degrees C, due to the electrostatic interaction. In contrast, aggregation and fusion of the polymer-modified cationic liposomes with the anionic liposomes were strongly suppressed below the LCST. However, these interactions were enhanced remarkably above the LCST. In addition, the polymer-modified cationic liposomes did not cause leakage of calcein from the anionic liposomes below the LCST, but promoted the leakage above this temperature as the unmodified cationic liposomes did. Temperature-induced conformational change of the polymer chains from a hydrated coil to a dehydrated globule might affect the affinity of the polymer-modified cationic liposomes to the anionic liposomes.

Improvement of temperature-sensitivity of poly(N-isopropylacrylamide)-modified liposomes.

As a novel temperature-sensitive drug delivery system, we have designed liposomes coated with poly(N-isopropylacrylamide), which exhibits a coil-globule transition at 32-35 degrees C. In a previous study [ K. Kono, H. Hayashi, T. Takagishi, J. Control. Release 30 (1994) 69-75], it was shown that the release of contents from the polymer-coated liposomes is enhanced above the transition temperature of the polymer but the release is not controlled completely by the conformational change of the polymer. In this study, to improve temperature-sensitivity of the poly(N-isopropylacrylamide)-modified liposomes, the influence of lipid composition on the temperature-sensitivity of the liposomes was investigated. A copolymer of N-isopropylacrylamide and N, N-didodecylacrylamide was synthesized by free radical copolymerization. While the copolymer was insoluble in water, it exhibited a coil-globule transition around 28 degrees C when incorporated into an egg yolk phosphatidylcholine membrane. The copolymer-modified egg yolk phosphatidylcholine/dioleoylphosphatidylethanolamine liposomes were prepared by sonication or reverse phase evaporation. Release of calcein from the copolymer-modified liposomes was very slow below the transition temperature of the copolymer, whereas the release was enhanced above the transition temperature. Incorporation of dioleoylphosphatidylethanolamine into liposome membranes enhanced release greatly above the transition temperature of the copolymer. Fluorometric measurements using 8-anilino-1-naphthalenesulfonate and 1,6-diphenyl-1,3,5-hexatriene suggested that the copolymer decreases membrane fluidity of the liposomes near and above the transition temperature of the copolymer and that interaction between the copolymer and the liposome membranes is enhanced by inclusion of dioleoylphosphatidylethanolamine.

Neurothekeoma. Report of a case with immunohistochemical and ultrastructural studies.

A case of neurothekeoma in a 52-year-old woman is reported. The tumor developed on the medial aspect of the right nostril as a well-demarcated, dome-shaped, erythematous nodule of rubbery consistency. Microscopically, it consisted of numerous nests and cords of spindle-shaped cells in the dermis. Some of the tumor cell nests appeared epithelial-like, while the other areas showed a myxomatous appearence with various amount of mucinous matrix in the intercellular space. Neurothekeoma is a benign cutaneous tumor, and is considered to be of schwann cell origin. In the present case, the tumor cells did not stain positively for S-100 protein, despite the light microscopic suggestion of peripheral nerve origin. Ultrastructurally, most tumor cells contained a large number of myelinoid figures. This ultrastructural finding appears to be a useful diagnostic characteristics of neurothekeomas.

Karyometric analysis of liver cell dysplasia and hepatocellular carcinoma. Evidence against precancerous nature of liver cell dysplasia.

Karyometric analysis was performed with respect to anisonucleosis, nuclear deformity and DNA content in cases of liver cell dysplasia (LCD) and hepatocellular carcinoma (HCC). Presence or absence of iron deposition in foci of LCD and HCC was also evaluated in siderotic livers. All LCDs showed marked anisonucleosis and marked increases in DNA content but slight increases in nuclear deformity. A tendency was noted in which the nuclear deformity was increased as the nuclei became larger. In contrast, HCCs showed wide ranges of anisonucleosis, nuclear deformity and DNA content. Hepatocellular carcinomas having marked anisonucleosis similar to that of LCD showed markedly increased nuclear deformity. However, unlike LCD, this increase was independent of their nuclear size. In the siderotic livers iron deposition was noted in the foci of LCD but not in the foci of HCC. These findings do not support the notion of LCD being precancerous.

Localization of hepatitis B surface antigen in the human parotid gland.

Localization of hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) in the human parotid gland and liver was studied by an immunohistochemical method in four cases with seropositive HBsAg. Neither HBsAg nor HBcAg could be detected in the parenchymal cells of the parotid gland in any of the cases. However, one of four cases, which had the highest titer of serum HBsAg, showed HBsAg immunoreactivity in the vascular wall and luminal fluid of the parotid gland. In liver, HBsAg was detected in three and HBcAg in two of the four cases, respectively. HBsAg was localized in the cytoplasm of hepatocytes, while HBcAg was localized mainly in their nuclei. The detection of HBsAg in the parotid gland and liver was correlated with the serum titer of the antigen. The results indicate that the HB virus does not have an affinity for or a replicate in the parotid gland. Also, it is suggested that the HBsAg found in saliva is derived from HBsAg circulating through the oral mucosa by capillary leakage and not from secretion into the mouth by the salivary gland.

[Tumor of the pineal region in three brothers].

Occurrence of tumor of pineal region in three brothers was presented and previously reported cases of familial occurrence of primary intracranial tumor were reviewed. Two cases were diagnosed as germinoma clinically. The other case was diagnosed as embryonal carcinoma by pathohistological examination. All cases were of germ cell tumor. Reports of pineal tumors occurring in siblings are extremely rare. There have been three reports in the literature but no case of familial occurrence of histologically verified germ cell tumor in the pineal region in three siblings has been reported. Genetic aspects of primary intracranial tumors have been discussed but there has not been established a close relationship between heredity and oncogenecity. This case is a very interesting case because it is not only a rare case of familial occurrence of pineal tumor but it suggests the propriety of the theorum dealing with germ cell origin tumor.