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Biomedical subjects

T Sakae

Publications and source records attributed to T Sakae.

At least 19 recordsLinked to original sources
PubMed1995

Evaluation of jawbone calcification in osteopetrotic (op/op) mice using computed tomography.

The study was conducted to evaluate the degree of calcification in the jawbones of 3 pairs of 4-week-old male op/op mice and littermates using computed tomography (CT) numbers. The mean CT numbers for op/op mice (n = 3) were 251.3 HU (range, 226 to 278) in the maxillary bone and 353.7 HU (range, 320 to 398) in the mandibular bone. The mean CT numbers for littermates were 336.7 HU (range, 324 to 350) and 596.6 HU (range, 580 to 604), respectively. The CT numbers of littermates were higher than in op/op mice for both maxillary and mandibular bones. These results indicated that the degree of bony calcification in littermates was higher than that in 4-week-old op/op mice in both the maxillary and mandibular bones. CT is able to demonstrate the degree of bony calcification in the jawbones of op/op mice using CT numbers, and it is suggested that CT is an extremely effective tool for examining the conditions of bone in vivo. This study also shows that op/op mice are useful for investigation of bone calcification or maturation.

Aging↗
PubMed1995

Thermal stability of mineralized and demineralized dentin: a differential scanning calorimetric study.

The purpose of this study was to determine the difference, if any, in the thermal stability of collagen in mineralized and demineralized dentine compared to that in unmineralized tissues, using differential scanning calorimetry, DSC. Human tooth dentin blocks, about 1 x 1 x 2 mm in size, were used in this study. Some dentin blocks were demineralized using a Plank Rychlo solution; others, using EDTA solution. The mineralized dentin showed an exothermic peak at about 310 degrees C and the combustion of organic materials was completed at about 450 degrees C. For the demineralized dentin, the combustion was completed at higher temperature range and showed a strong exothermic peak at about 470 degrees C. An exotherm at the temperature between 450 degrees C and 470 degrees C was also observed in DSC pattern of native type I collagen from calf skin and rat tail tendon. DSC pattern of rat tail collagen showed a close similarity to that of the demineralized dentin. Statistically, the same heat flow value was obtained both from the mineralized dentin and the demineralized dentin and from the native type I collagen. These findings indicated that the thermal stability of collagen in dentin is lower than collagen in uncalcified connective tissue. It is suggested that in calcified collagen, the apatite crystallites may have intruded into spaces of the crosslinks of intra- and inter-fibrils, and in so doing, destroyed the crosslinks.

Animals↗
PubMed1995

Scanning electron microscopy and energy dispersive spectroscopy analysis of calciotraumatic lines in rat labial dentin after acute exposure to strontium chloride.

Rats were given strontium chloride (SrCl2) intraperitoneally at a dose of 500 mg/kg. The upper incisors were removed after injection of strontium. These incisors were studied by scanning electron microscopy-energy dispersive spectroscopy analysis (SEM-EDS) and light microscopy to examine the calciotraumatic lines of strontium in the rat incisor labial dentin. At 24 hours after injection of strontium, the calciotraumatic response was observed in the predentin using hematoxylin and eosin (H-E) staining. At 5 days, three layers of calciotraumatic lines were present in the labial dentin using an H-E staining and backscattered electron imaging in the SEM. The external layer consisted of unmineralized dentin, the intermediate layer of relatively unmineralized dentin, ane the internal layer of unmineralized dentin. By SEM-EDS analysis, strontium was detected in these layers. The elemental dot map showed that the external and internal unmineralized layers had a low calcium content. The magnesium concentration was higher in the internal unmineralized layer than the external unmineralized layer.

Animals↗
PubMed1995

[Orbital varix presenting orbital apex syndrome].

On 7 July 1993, a 61 year-old female presented a seven-day history of double vision and retro-ocular pain. Neurological examination on admission demonstrated right oculomotor palsy and pain in the right frontal nerve. Routine CT scan and MRI disclosed no abnormalities. Her symptoms deteriorated progressively and increased in severity, resulting in complete ptosis and visual disturbance in the right eye, for which she was hospitalized. Angiography also failed to demonstrate any lesion. Herrical CT scan demonstrated a small mass lesion at the right orbital apex. A frontotemporal extradural approach operation was performed on July 6, 1993. The anterior clinoid process and minor wing of the sphenoid were drilled to expose the optic canal and the superior orbital fissure. When the periorbita just beside the optic sheath was opened, a large vein was observed to be impinging on the optic nerve and nerves which pass through the superior orbital fissure. This vein was carefully dissected, coagulated and removed. The postoperative course was uneventful. Her severe retro-ocular pain completely disappeared immediately after the operation. Although complete remission of ptosis and return of eye movements to normal were noted, her visual acuity is at present limited to hand movement. Orbital varix is a common cause of unilateral intermittent proptosis. However, there has been no report in the literature of orbital varix with orbital apex syndrome as the initial clinical appearance. In this type of patient with orbital varix and retrobulbar hemorrhage or impairment of intraorbital nerves, surgical intervention using a transcranial approach to the lesion should be undertaken.

Cranial Nerve Diseases↗
PubMed1993

Calcium phosphate in aspergillosis of the maxillary sinus.

The unique appearance of apatite in fungus balls of aspergillosis in the maxillary sinus was investigated using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray microdiffraction and Fourier transform infrared spectroscopy (FT-IR). Rod-shaped fragments with tubular structures, and globular vesicles covered with conidia were observed in the fungus balls. Massive fragments of a solid substance were demonstrated inside the fungus balls. Calcium and phosphate were detected in necrotic areas of the fungus balls by EDS. X-ray microdiffraction and FT-IR showed the presence of an apatite-like substance, but failed to demonstrate the presence of calcium oxalate crystals usually found in such fungus balls.

Aspergillosis↗
PubMed1992

Scanning electron microscopy-energy dispersive spectroscopy and X-ray diffraction analyses of human salivary stones.

Ten salivary stones in the human submandibular gland were investigated by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction analyses. The stones usually showed a lamellar pattern. SEM observations revealed cubical, plate-like, granular, small and large granules, polyhedral or globular structures in these stones. By X-ray powder diffraction analysis, the main constituents of salivary stones were found to be apatite and whitlockite. SEM-EDS analyses showed that Ca and P were the major elements, frequently accompanied by Mg and S, and less frequently by Na, Al, Si, Cl, K, Fe, Cu and Zn. Ca/P molar ratios ranged from 1.00 to 2.00 with the average of 1.53, showing two maxima of about 1.50 and 1.60. The Ca/P molar ratio of about 1.50 corresponded to the value of whitlockite. The Ca/P molar ratio of 1.60 corresponded approximately to the value of apatite.

Adolescent↗
PubMed1992

Infrared spectroscopic method for analysis of precipitates on a cell culture dish.

A new quick infrared spectroscopic method was developed and applied to analyze precipitates formed by cultured cells on a Petri dish. This IR method allows a dish to be placed directly on the sample beam window of a normal double beam IR spectrometer. Placing a blank dish on the reference beam window of the spectrometer compensates for the high background absorption due to the dish on the sample beam window and enables an identifiable spectrum to be obtained. Using this technique with a Petri dish, a high correlation factor of 0.998 was found between the PO4 peak absorbance and the weight of synthetic hydroxyapatite in the range of 0.5-2.5 mg/cm2. The IR pattern, however, showed a shift in the positions of the absorption band and the appearance of ghost peaks. Using a thin based Petriperm dish, these difficulties were overcome producing a correlation factor of 0.992 at the lower range of 0.05-1.45 mg/cm2. Application of this technique to the precipitates formed on a Petri dish by rat bone marrow derived cells showed the presence of collagen and apatite-like substance.

Absorption↗
PubMed1991

Acute spinal cord injury: magnetic resonance imaging correlated with myelopathy.

Thirty-one patients (29 males and two females, 13-87 years of age (mean, 46.7 years] with acute spinal cord injury were studied by MR (magnetic resonance) imaging and the results were correlated with neurological findings. Magnetic resonance images were obtained with a 0.5 T superconductive MR scanner (Phillips Gyroscan S5). Initial imaging was performed within 24 hours after trauma in 13 patients, 1-7 days in 13 patients and 7-14 days in five patients. Twenty-six patients underwent follow-up examinations with MR imaging. Cord abnormalities including cord compression (23 patients), cord swelling (seven patients), and abnormal signal intensities on either T1 or T2-weighted images (26 patients) were observed on initial examination. Multivariate analysis showed that cord compression and abnormal intensities on T1-weighted images were important prognostic indicators. Hyperintensity on T2-weighted images was non-specific but correlated well with clinical recovery. Magnetic resonance imaging is useful in predicting the prognosis and for planning treatment following spinal cord injuries.

Acute Disease↗
PubMed1991

Morphological study of calcospherites in rat and rabbit incisor dentin.

Calcospherites from incisors of rats and rabbits were studied, by means of secondary and backscattered electron images, using scanning electron microscopy. Part of each incisor specimen was made anorganic to allow observation of the surface of the mineralization front by scanning electron microscopy; the other part was ground on one side for observation by scanning electron microscopy with a backscattered electron image detector. In both species the labial mineralization front was wavy and the image showed fused calcospherites, whereas the lingual mineralization front appeared to consist of a combination of linear and globular forms. In rat labial dentin the calcospherites were large and globular form, but they did not develop in the lingual dentin and were small and oval. The shape and size of rabbit incisor calcospherites varied from the pulp horn to the root apex. There were great differences between rats and rabbits with respect to the size and shape of the calcospherites at the mineralization front. This may be due to species differences and possibly the differing rates of dentinogenesis in rats and rabbits.

Animals↗
PubMed1990

Chronic injuries of the spinal cord: assessment with MR imaging.

Seventy-six patients with persistent myelopathy secondary to chronic spinal cord injuries underwent examination with magnetic resonance (MR) imaging, the results of which were correlated with neurologic findings. Twenty-one patients received follow-up study during and after the acute stage; 55 patients were examined only at a chronic stage. Spinal cord abnormalities were seen in 48 patients according to five patterns: (a) normal signal intensity on T1- and T2-weighted images (pattern N/N, n = 28), (b) normal signal intensity on T1-weighted and hyperintensity on T2-weighted images (pattern N/Hi, n = 18), (c) hypointensity on T1-weighted and hyperintensity on T2-weighted images (pattern Lo/Hi, n = 17), (d) cord atrophy (n = 5), and (e) longitudinal syrinx formation with hypointensity on T1- and hyperintensity or isointensity on T2-weighted images (n = 8). Patients with pattern N/N had only slight neurologic damage and an excellent prognosis. Patients with pattern N/Hi had mild neurologic impairment, frequently associated with cord compression. Patients with pattern Lo/Hi had the worst prognosis. Atrophy was observed in patients with a long history of myelopathy.

Adult↗
PubMed1990

X-ray crystallography of incisor enamel from red kangaroo.

X-ray powder diffraction of red kangaroo (Macropus rufus) dental enamel, with a relative density greater than 2.60, showed a longer a-axis length of the apatite unit cell, a = 9.462 A, a shorter c-axis length, c = 6.877 A, and a smaller crystallite size, ca. 185 A, than those of human dental enamel. The a-axis of red kangaroo dental enamel was one of the longest among the values reported previously, whereas the c-axis was one of the shortest. The crystallite size was almost equal to that of dentin crystallites. It is suggested that the chemical composition of the dental enamel apatite of the red kangaroo is markedly substituted, resulting in lattice distortion.

Animals↗
PubMed1989

Cleidocranial dysplasia: a light microscope, electron microscope, and crystallographic study.

An unusual case of cleidocranial dysplasia associated with more than 60 unerupted teeth is presented and examined with light and scanning electron microscopes and crystallographic techniques. The present case revealed pseudoprognathism with facial asymmetry, the right side being larger than the left. The extracted teeth showed enamel hypoplasia in light and scanning electron microscopy, yet the crystalline composition did not differ from that of the normal teeth. The potential causes of lack of eruption and supernumerary tooth formation in cleidocranial dysplasia are discussed.

Adult↗
PubMed1989

Crystallographic properties of a series of synthetic hydroxyapatites.

The crystallographic properties of hydroxyapatites synthesized at temperatures of 200 degrees C, 500 degrees C, 900 degrees C and 1250 degrees C, designated HAP200, HAP500, HAP900 and HAP1250, respectively, were studied using X-ray powder diffraction. Values of a-axis length for the hydroxyapatites ranged from 9.406 A to 9.416 A, which were smaller than the corresponding value for stoichimetric hydroxyapatite, a = 9.418 A. Generally, the a-axis length decreased with the synthesis temperature, except for HAP500 which showed the smallest value. Crystallinity of the hydroxyapatites, measured by X-ray diffraction peak broadening as full width at the half-maximum value (FWHM), increased with the synthesis temperature, although HAP500 showed a decrease. These results suggest that the synthetic hydroxyapatites contained some carbonate ions, probably at the A-site of the apatite structure, and that the structure was depleted of carbonate ions at about 500 degrees C.

Crystallography↗
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

[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↗