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Biomedical subjects

H Mishima

Publications and source records attributed to H Mishima.

At least 109 records · Page 6Linked to original sources
PubMed1991

[Effect of topical 8-hydroxy carteolol on intraocular pressure and melanin granules].

It was reported that 8-Hydroxycarteolol (8-OH CA), the major metabolite of carteolol hydroxychloride (CA), has a slightly different pharmacological effect from CA. We studied the reduction of intraocular pressure (IOP) on a single eyedrop application of 8-OH CA in albino and pigmented rabbit eyes. To determine the characteristic of 8-OH CA and CA, we investigated the binding ability of these drugs to synthetic melanin. In the present study, topically applied 2% CA did not significantly decrease IOP in albino and pigmented rabbit eyes. Topically applied 0.01, 0.05, 0.1 and 1.0% 8-OH CA significantly decreased the IOP of albino rabbit as did 0.1 and 1.0% 8-OH to pigmented rabbit eyes. The maximum reduction of IOP was 3.5 +/- 0.33 mmHg (mean +/- SEM) in albino rabbit and 3.0 +/- 0.45 mmHg (mean +/- SEM) in pigmented rabbit. Maximum IOP reduction was obtained after 30 min. from topical application in albino rabbit, but in pigmented rabbit after 1 hour or later. Our binding studies to melanin show that the melanin binding ability is less for 8-OH CA than for CA at any concentrations. These results may indicate that lower concentrations of topically applied 8-OH CA profoundly reduce IOP compared to CA, and 8-OH CA has less effect on melanin than CA.

Administration, Topical↗
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

Differential modes of action of fibronectin and epidermal growth factor on rabbit corneal epithelial migration.

In order to clarify the roles of fibronectin (FN) and epidermal growth factor (EGF) in corneal wound healing, we cultured blocks of excised rabbit cornea for 24 hours in media containing one of these agents, then measured the length of the path of the epithelial layer that had migrated down the side of the block. Both FN and EGF stimulated epithelial migration significantly in a dose-dependent fashion. Responses to EGF involved a time lag of at least 12 hours before stimulation could be observed, but there was no lag-time for FN-stimulated migration. FN was maximally effective only if it was continuously present. In contrast, exposure to EGF for 6 hours did not stimulate epithelial migration, but exposure for 9 hours resulted in the same stimulatory effects as were observed after 24 hours' continuous exposure. Anti-FN antibody inhibited the FN- and EGF-stimulated migration of corneal epithelium. But anti-EGF antibody inhibited only EGF-stimulated migration and had no effect on FN-stimulated migration. These results indicate that, unlike FN, EGF need not be present, once the epithelial cells have recognized its signal. Furthermore, the stimulatory effect of EGF depended on FN, while that of FN was independent of EGF. The effects of EGF on migration of corneal epithelium may, therefore, be mediated by FN.

Animals↗
PubMed1990

[Study on prototype cylindrical HAP].

Hydroxyapatite (HAP) is currently utilized as biomaterials for implantation or reconstruction of bone defect in dentistry. In order to obtain better physical properties and biocompatibility, we have developed cylindrical sintered porous HAP which has longitudinal internal tubules. We measured compressive strength and specific surface area of cylindrical HAP. In the results, compressive strength was more 300MPa on average and specific surface area was 1.7-2.4 folds as HAP ceramics commercially available. This result indicates new bone formation. Cylindrical HAP used was subsequently applied to lower premolars and molars of male beagle dogs (1.5 years). We have implanted cylindrical HAP to bone defect of postextraction of tooth followed to sacrifice six months after. Specimens of bone block were stained with Villanueva bone stain and observed with fluorescence microscope and scanning electron microscope. New tissue formation was observed invading into tubules of 27 microns diameter of cylindrical HAP particles. This new tissue was confirmed to be bone tissue because the proportion of Ca to P was 1.616 obtained by energy dispersive X-ray analyzer.

Alveolar Bone Loss↗
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↗
PubMed1990

[Double filtration plasmapheresis in case of Goodpasture's syndrome].

This article describes a case of Goodpasture's syndrome controlled by double filtration plasmapheresis (DFPP) combined with steroid and immunosuppressant therapy. A 48-year-old male, clerk, complaining of fever, dry cough and macroscopic hematuria, was admitted to our hospital. Microscopic hematuria was first pointed out at age 40 on an annual check up. His laboratory data on admission revealed severe anemia, azothemia, macroscopic hematuria and proteinuria. His chest radiograph and CT revealed diffuse nodular densities in bilateral lung fields. Specimens obtained by transbronchial lung biopsy and open renal biopsy revealed linear deposition of IgG by direct immunofluorescent antibody methods. Circulating antiglomerular basement membrane antibody level determined with radioimmunoassay was 1.8% on admission, but one week later it elevated to 5.6% with progression of dyspnea, hypoxemia, and renal failure. Steroid pulse therapy and a total of 6 double filtration plasmaphereses were performed in the first month. Subsequently hypoxemia and dyspnea disappeared, and the chest radiograph of the 40th hospital day showed no abnormal shadows. Two months later recurrence of pulmonary hemorrhage was noticed. Immunosuppressant administration (Cyclophosphamide 100 mg/day) and a total of 10 DFPP procedures were performed with success. By DFPP, circulating anti-GBM antibody fell rapidly to within normal ranges, and anti-GBM antibody level elevated in removed plasma. We think DFPP is effective to remove circulating anti-GBM antibody in Goodpasture's syndrome.

Anti-Glomerular Basement Membrane Disease↗
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↗
PubMed1989

[Energy dispersive X-ray analysis of human deciduous teeth dentin].

Human deciduous molars were ground and polished in order to be examined by an analytical electron microscopy. An energy dispersive X-ray analysis system attached with a scanning electron microscope was used to analyze the teeth dentin both qualitatively and quantitatively. Calcium and phosphorus and also magnesium could be detected in the intertubular dentin of their teeth. The calcium content of the interglobular dentin was lower than those of the other part of dentin. The magnesium content was almost 4% (atomic %). The magnesium content in the dentin was higher than those in the enamel and cementum of the same specimen. It was suggested that some magnesium was contained in the dentin crystal structure.

Calcium↗
PubMed1989

[An early stage case of pulmonary lymphangiomyomatosis].

A 35-year-old unmarried woman was admitted to our hospital because of right pneumothorax. Pulmonary lymphangiomyomatosis was suspected from CT and transbronchial lung biopsy findings. The diagnosis was confirmed histologically by open lung biopsy. As her biopsy specimen showed positive findings for both estrogen and progesterone receptor, tamoxifen administration was started. The CT revealed multiple cystic lesions (5-10 mm in diameter) but otherwise normal vascular structures and normal lung density. The plain chest radiograph showed no abnormalities. CT is very useful for the early detection of pulmonary lymphangiomyomatosis.

Adult↗
PubMed1988

Leukemic involvement of the optic nerve.

We studied five cases of leukemia with invasion of the optic disk and optic nerve. Two patients had acute lymphoblastic leukemia and three had acute myelogenous leukemia. All patients received intrathecal injections of chemotherapeutic drugs including methotrexate, cytarabine, and prednisolone. Three patients underwent irradiation therapy of the whole brain and optic nerve. While initial improvement in the ophthalmic abnormalities, such as optic disk edema, flame-shaped retinal hemorrhages, and dilation of the retinal vein, was noted, optic atrophy was later found in all eyes.

Adolescent↗
PubMed1988

Dexamethasone inhibition of phagocytosis by corneal keratocytes in culture.

To investigate the effect of steroid hormone on phagocytosis by keratocytes, we investigated the phagocytic activities for latex beads by rabbit corneal keratocytes cultured in the presence and absence of dexamethasone. Culturing the corneal keratocytes with dexamethasone inhibited the phagocytic activity for latex beads in a dose-dependent fashion. The inhibitory effects depended on the duration of the incubation period of the cells with dexamethasone.

Animals↗
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↗