Biomedical subjects

Y Kozawa

Publications and source records attributed to Y Kozawa.

At least 37 records · Page 2Linked to original sources

PubMed1991

Microprobe analyses of the potassium-calcium distribution relationship in predentine.

Apex regions of continuously growing incisors of Wistar rats were quickly dissected, shock-frozen in liquid nitrogen-cooled propane, freeze-dried at -80 degrees C and infiltrated with Spurr's resin. 400nm thick dry sections were cut with a diamond knife on an ultramicrotome. Relatively flat sections were transferred with an eye lash onto collodium coated aluminum grids. They were flattened with a glass stick and by placing another collodium coated aluminum grid just on top of the first one, exerting a uniform pressure. After carbon coating the sections were observed using the backscattered and secondary electron signals in a scanning microscope. The predentine was analyzed for calcium and potassium with an energy dispersive x-ray analysis system. The x-ray spectra revealed in the predentine regions with beginning dentine formation, near the apex, an uneven K-distribution with very low as well as more prominent x-ray peaks. The K peaks were always lower than those of calcium. In areas with advanced dentine formation, prominent K-peaks were always observed. They were normally higher than the Ca-peaks up to a distance of 5-10 microns from the dentine border. Closer to the dentine border the K concentration decreased while the Ca-peak increased. This might indicate that (besides Na) K is used to balance the negative charges of the macromolecules till K is replaced by Ca at the onset of apatite crystal formation.

Animals↗

PubMed1990

Granular cell tumor of the tongue: an electron microscopical and immunohistochemical study.

Granular cell tumor of the tongue in a 29-year-old woman is reported including details of studies using electron microscopy and immunohistochemistry. Immunohistochemically, the tumor cells showed moderate positivity for S-100 protein. Electron microscopically, basal lamina, angulate bodies, myelin-like figures and axon-like structures were observed in the tumor. These findings may indicate that this tumor is a lesion of Schwann cell origin. The Japanese literature on oral granular cell tumor is also reviewed and discussed.

Adult↗

PubMed1990

[The relationship between the reduced form tooth and the structures. The conical shaped upper lateral incisor].

The tooth structure of conical shaped incisor is observed with ground sections by light microscope. The Hunter-Schreger bands runs slightly convexed to the cervical from the dentino-enamel junction to the enamel surface. Enamel prisms arrange alternately and form almost arched type. Enamel spindles are observed remarkably. Many globular and interglobular structures are observed in the dentine. These structures are almost similar that of molar teeth expect some special types of enamel prisms. It is concluded that the conical shape did not cause of the reduced pattern of teeth structures.

Dental Enamel↗

PubMed1989

Intrahepatic delivery of glutathione by conjugation to dextran.

Glutathione was covalently attached to dextran (T-40) by the CNBr activation method. The compound obtained was a water-soluble powder containing 10 (w/w%) glutathione, which was gradually released from the conjugate in aqueous media. Mice depleted of glutathione by treatment with buthionine sulfoximine, a potent inhibitor of gamma-glutamylcysteine synthetase, exhibited a significant increase in hepatic glutathione level after intravenous injection of the conjugate. In mice given a lethal dose of acetaminophen, the survival rate increased progressively with coadministration of the conjugate, whereas little improvement was found when free glutathione was given. The conjugate maintained the serum transaminase activities at lower level after acetaminophen administration. These findings suggest that the dextran conjugate of glutathione is transported into hepatic cells and is intracellularly hydrolyzed to free form, which protects mice from hepatotoxicity due to acetaminophen.

Acetaminophen↗

PubMed1989

Effects of glutathione, as the dextran conjugate, on acetaminophen-induced hepatotoxicity.

Glutathione was covalently attached to dextran (T-40) by the CNBr activation method. In mice given a lethal dose of acetaminophen, the 30-d survival rate increased progressively with coadministration of the conjugate, whereas little improvement was found when free glutathione was given. The dextran conjugate of glutathione maintained the serum transaminase activities at lower levels after acetaminophen administration, giving effective protection against acetaminophen hepatotoxicity.

Acetaminophen↗

PubMed1989

[Intranuclear rodlet in the odontoblast].

Lower incisors of 6 rabbits (about 3.5 kg, Japanese white, male) were observed by the electron microscopy. The life cycle of rabbit incisor odontoblast is classified into 4 stages by the dentine structure; 1st is outer, 2nd is middle, 3rd is inner and the 4th layer, that is the secondary dentine filling in the center of pulp. Fibrous intranuclear rodlets were observed in the odontoblast of late 2nd and 3rd stages, which forms thick inner half dentine. The odontoblasts of 2nd stage were tall and matrix formation cells, containing well developed golgi apparatus, many RER and secretory granules. The 3rd stage odontoblasts were short and formed the vaso-dentine in the lingual side. Intranuclear rodlets, about 5 nm thick, consisted of 5-20 fibrous or tubular structures. The arrangement of rodlets had no relation to the cell axis. These intranuclear rodlets might be observed only in the last stage odontoblast in the rat incisor. The morphological observations show 1) the term of life cycle of rabbit odontoblast may be more longer than the rat, 2) the intranuclear rodlets may be caused by the stress on the odontoblastic function such as the heat-shock treated fibroblasts.

Animals↗

PubMed1989

[Root fracture after crown prosthesis--observation and analysis with EDS].

Root fractures in the teeth under or after the crown prosthetic treatment after occur intra-alveolary. In the many cases, these teeth will be diagnosed to be extracted. Therefore, root fracture is one of the clinical problems for clinicians. There are many clinical and descriptive reports on root fractures after crown prosthesis. But more fundamental studies should be done for the prevention of root fractures. We observed the sampled tooth with scanning electron microscopy and analytical electron microscopy. The tooth with root fractures after the treatment of crown prosthesis was used in this study. The following were the results of this investigations: 1) The cohesional substances, which are regarded as oral bacteria and organic materials, were observed in the definite section on the surface of fracture. 2) The line of the root fracture ran parallel with the canaliculus dentalis. 3) The cracks were observed to run through the face of crosscutting of canaliculus dentalis. 4) Ca and P on the surface of the fracture is 32.75 and 27.70 (atomic %), respectively (Ca/P 1.18). These values are lower than these of control group. In the same surface of the root fractures, the values of Ca and P in the middle parts were less than those of the outside. Reversely, the more deep parts have a little higher values than those of the middle parts. 5) The values of Zn increased on the surface of the fracture than those of the control. 6) The values of S was not detected on the control surface. On the other hand, S was detected in the relatively higher density (15.04) on the surfaces of the root fractures.

Crowns↗

PubMed1989

[Demonstration of crystal orientation in rat incisor dentin by a PSPC-MDG system].

A PSPC (Position Sensitive Proportional Counter)-MDG (Micro Diffract Goniometer) system was applied to show the crystal orientation in the rat linugal dentin. The X-ray diffraction from a specimen was recorded by usual chart recorder instead of the classical film method. Specimens were about 150 microns wide and 100 microns thick of pillar form with the long axis of specimen parallel to the dentinal tubules. When the X-ray was irradiated in the labiolingual dicection, the peak intensity of (002) was stronger than that of the combined peak of (211) and (112). The more it rotated from the first position along the long axis of specimen, the more the peak intensity of (002) weakened, and after it rotated at 90 degrees the peak of (002) completely disappeared. The results indicated that the crystals were well-oriented in the lingual dentin. The axis of crystal orientation was almost parallel to the tooth axis, but swayed within the range of about 30 degrees.

Animals↗

PubMed1989

Morphology and chemical composition of dental calculi mainly composed of whitlockite.

The morphology and chemical composition of two subgingival calculus samples, which were composed of magnesium-whitlockite with a Mg/Ca molar ratio of approximately 0.1 as shown by X-ray powder diffraction, were analyzed semiquantitatively using energy-dispersive spectroscopy (EDS) combined with scanning electron microscopy (SEM). The Ca/P molar ratio values for 33 EDS-analyzed materials ranged from 1.24 to 2.03 with an average of 1.49, and the (Mg+Ca)/P molar ratio values ranged from 1.43 to 2.28 with an average of 1.63. The average Mg/Ca molar ratio was 0.10, a value very close to that obtained by X-ray diffraction analysis. The EDS-analyzed materials were grouped morphologically into three types; Type A materials were typical rhombohedral crystals, Type B were crystals of ill-defined form or small crystallite aggregations and Type C materials had a small granular structure or were amorphous. The values of (Mg+Ca)/P molar ratio for Type A ranged from 1.57 to 2.28 and averaged 1.81, those for Type B ranged from 1.43 to 1.56 and averaged 1.48, and those for Type C ranged from 1.46 to 2.06 and averaged 1.62. Type A crystals had higher molar ratios while Type B crystallites had values similar to that of whitlockite. Type C materials covered the ranges of both Type A and Type B. These results show that the materials resembling whitlockite morphologically did not have the (Mg+Ca)/P ratio of whitlockite and vice versa. This suggests that whitlockite crystals may substitute some ions for PO4 as well as Mg for Ca to a larger extent than thought previously, and that care is needed in the identification of these materials.

Adult↗

PubMed1988

Electron-microscopic and microprobe analyses on the pigmented and unpigmented enamel of Sorex (Insectivora).

Sorex belongs to the Insectivora and has a pigmented tooth enamel due to iron. The pigmented enamel (PE) has a mean Ca/P weight ratio, analyzed by quantitative electronprobe X-ray microanalysis, of about 1.9 (mean molar Ca/P ratio 1.46), and the unpigmented enamel (UE) a Ca/P weight ratio of about 2.0 (mean molar Ca/P ratio 1.59). The PE has a higher iron content (with a value of about 8%) than the UE, as shown by microanalysis of ultrathin sections. Laser microprobe mass analysis (LAMMA) has shown that the carbonate content in the UE is higher than in the PE. In the LAMMA spectrum of the negatively charged ions the carbonate lines could be compared directly with those of negatively charged iron ions. The pigmentation is associated with a low Ca/P ratio but may transfer mechanical strength and acid resistance strength to the PE.

Animals↗

PubMed1988

Changes in bovine dentin mineral with sodium hypochlorite treatment.

Dentin powders from bovine incisors were treated with 10% NaClO solution. Differential thermal analysis (DTA) indicated the removal of organic material from the dentin sample following the treatment, since the exothermic reaction at 320 degrees C had disappeared. X-ray diffraction studies revealed a change in the crystallinity of the dentin crystals and the formation of calcite after the treatment. Infrared absorption analysis showed that the band due to carbonate ions was weakened after the treatment, while atomic absorption spectroscopic analysis showed that magnesium ions had been dissolved from the dentin sample. The a-axis lengths of treated and heated dentin samples differed from those of untreated and heated samples. Whitlockite was always found in the untreated/heated samples, whereas it was absent in the treated/heated samples. The unit cell dimensions of the whitlockite indicated the partial substitution of magnesium for calcium. Magnesium ions seemed to be more effective than carbonate ions in forming whitlockite. These results showed that some magnesium and carbonate ions were removed from the dentin crystal structure upon NaClO treatment, while at the same time organic materials were removed from the dentin sample. It was suggested that crystals in the NaClO-treated dentin were similar to enamel crystals from a crystallographic viewpoint.

Animals↗

PubMed1988