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Biomedical subjects

S Ohtani

Publications and source records attributed to S Ohtani.

At least 127 records · Page 7Linked to original sources
PubMed1991

Histologic findings of apatite-titanium complex dental implants in the jaws of dogs.

This study concerns the histologic examination of apatite-titanium complex dental implants (two-piece, cylindrical type) in dogs. There was no plaque control. One to 3 months after implantation, the surface of the apatite root was directly bound to newly formed, woven bone. Seven-and-a-half months to 1 year after implantation, the apatite root was directly bound to the newly formed lamellar bone, which provided strong bone bonding (apatite-bone bonding). There appear to be two types of mechanisms for the resorption of apatite ceramics: first, cellular-type resorption by both multinuclear and mononuclear macrophages; and second, a noncellular, fluid mechanism (dissolution). The gingival sulcus around implants and downward growth of the epithelial cells could be observed in almost all of the implants. There was no cellular inflammation in the tissue around the implants, in the nasal cavity, or in the maxillary sinus. From this study we concluded that clinical application of this dental implant system would be practical.

Animals↗
PubMed1991

Age estimation by amino acid racemization in teeth--a comparison of aspartic acid with glutamic acid and alanine as indicators.

On the age estimation by the amino acid racemization analysis of dentine, besides the utilization of aspartic acid (Asp) as described in earlier reports, we further studied relationships between the D/L ratios based on glutamic acid (Glu) as well as alanine (Ala) and actual ages. The study was followed up by comparing racemization velocities of the three amino acids under some heating experiments. At four steps (6, 24, 48 and 72 hours) of hydrolysis, the coefficient values of D/L ratio of each amino acid and actual age were calculated as 0.986 to 0.994 for Asp, 0.522 to 0.806 for Glu, and 0.577 to 0.737 for Ala. The data indicate that Asp gives an extremely good result. Glu and Ala do provide reliable D/L ratios, however they are not in proportion to actual ages. Consequently, Glu and Ala seem to be much less suitable for utilization in age estimation. Reaction rate constants (k.yr-1) of racemization of Asp, Glu and Ala in antemortem teeth were 5.3825 X 10(-4), 5.1000 X 10(-5) and 2.3875 X 10(-5), respectively. Those in teeth left drying at 15 degrees C were 2.4850 X 10(-8), 1.9119 X 10(-9), and 1.1450 X 10(-9), respectively. Assuming that the reaction velocity of Asp be 1 in both living and dried states, that of Glu were calculated as 0.09 and 0.08, that of Ala, 0.04 and 0.05, indicating very similar rates. The result confirmed that both Glu and Ala gave considerably slow racemization velocities as compared with Asp.

Age Determination by Teeth↗
PubMed1991

Statistical analysis of the ability of police dental surgeons in identification of dental filling materials.

The subjects, 77 police dental surgeons at 50 police stations in Kanagawa prefecture, were asked to identify either gold foil filling, gold inlay, palladium alloy inlay, silver alloy inlay, which had been filled in 5 human skulls. We conducted a statistical analysis of the dispersion of agreement rates in identifying the filling materials according to their clinical career. The results showed that the rates for gold inlay and gold foil filling were higher than those for silver alloy inlay and palladium alloy inlay. However, it was concluded that caution is necessary in identifying elaborately-finished fresh filling materials.

Adult↗
PubMed1991

Age estimation using the racemization of amino acid in human dentin.

This study was made to improve the validity of age estimation from teeth using amino acid racemization. The correlation between actual age and the D/L ratio of aspartic acid was investigated by analyzing not only the total amino acid but also its fractionated substances, insoluble collagen and soluble peptide. The coefficient values of correlation between the D/L ratio and actual age in adult lower central incisors were 0.996 (sigma = +/- 1.0 year) for the total amino acid, 0.988 (sigma = +/- 1.8 years) for insoluble collagen, and 0.997 (sigma = +/- 0.9 years) for soluble peptide. The corresponding figures in adult first premolars were 0.991 (sigma = +/- 1.6 years), 0.988 (sigma = +/- 1.9 years), and 0.994 (sigma = +/- 1.4 years), respectively. The reactive velocity of aspartic acid racemization was highest for soluble peptide in both the lower central incisors and first premolars and approximately three times as rapid as that for total amino acid. As a result, age estimated from the analysis of soluble peptide was most accurate. The velocity for insoluble collagen was slightly lower than that for total amino acid. Age estimation was attempted from the teeth of an unknown body. These results suggest that the analyses, not only of total amino acid in dentin but also of its fractionated and extracted substances, can lead to higher reliability in age estimation. Soluble peptide, in particular, has been found to be most effective.

Adult↗
PubMed1991

Estimation of ages from racemization of an amino acid in teeth--assessment of errors under various experimental conditions.

In order to estimate ages of corpses more accurately from racemization of an amino acid (aspartic acid) in the dentine of teeth, errors resulting from various experimental conditions were assessed. The factors included for evaluation were: the sample weight, time and temperature of hydrolysis, concentration of hydrochloric acid, and the volume of the hydrochloric acid solution, each of which might have effect on resulting errors. This study revealed that alteration of the sample weight did not change the D/L ratio and that the estimated age remained constant as long as the sample weight was within the range of 3 mg and 50 mg. However, with the remaining factors, the D/L ratio changed with the alteration of conditions. The correlation can be represented by a straight line in a graph, which is a sign of the first order reaction. The coefficients of correlation were between 0.972 and 0.999, indicating their extremely high correlation with the D/L ratio. The errors expressed in estimated age values per unit of variables were: 0.02 years/min. for a time (min.) of hydrolysis; 1.5 years/degrees C for temperature of hydrolysis; 0.5 years/0.1 N (normal) for concentration of hydrochloric acid; and 0.6 years/ml for the volume of hydrochloric acid solution. Consequently, the temperature of hydrolysis was found the most influential. Alteration of values of the other four factors did not largely affect the estimation.

Age Determination by Teeth↗
PubMed1990

Separation of high-molecular mass RNAs by high-performance liquid chromatography on hydroxyapatite.

High-molecular-mass RNAs [transfer-(t-), 5S-, 18S- and 28S-RNA] in 25 mM sodium acetate buffer (pH 6.0) were separated by high-performance liquid chromatography (HPLC) on hydroxyapatite using a linear gradient (120 min-duration) from 0.03 to 0.147 M of phosphate buffer (pH 7.0) containing 0.3 M potassium chloride and 1 mM sodium azide with a slope of 2 mM/ml at a flow-rate of 0.5 ml/min. When the RNAs were dissolved in 4 M guanidine isothiocyanate-25 mM sodium acetate buffer (pH 6.0)-0.1 M beta-mercaptoethanol (4 M GIT), t-, 5S- and 18S- or 28S-RNAs but not 18S- and 28S-RNAs were separated. RNAs extracted from rat superior cervical ganglia with 4 M GIT could be separated. Thus, HPLC on hydroxyapatite is a rapid and accurate means of quantifying and/or preparing high-molecular-mass RNAs such as t- and ribosomal RNAs.

Animals↗
PubMed1990

Leachability of denture-base acrylic resins in artificial saliva.

We studied the influence of salivary acidity on leachability of denture-base acrylic resins with etiological interest in denture stomatitis because denture surfaces are frequently exposed to acidic conditions in the oral cavities. Auto-, heat-, and microwave-polymerized resins were immersed in artificial saliva with pH ranging from 4.0 to 6.8 at 37 degrees C, and leachables were pursued quantitatively with time. Methyl methacrylate, methacrylic acid, and benzoic acid leached from all resins. Their concentrations in the saliva were markedly high for auto-polymerized resins, while leachability of heat- and microwave-polymerized resins was so low that quantitative analysis of leachables was impossible. Lower pH showed higher concentrations of methyl methacrylate, although no apparent association was confirmed between salivary acidity and its own leachability. The concentrations of methacrylic acid increased remarkably with an increase in pH, which was probably due to hydrolysis of methyl methacrylate. These results suggest that chemotoxic actions of auto-polymerized resins are potentially ascribable to methyl methacrylate under more acidic conditions and to methacrylic acid under less acidic conditions.

Acrylic Resins↗
PubMed1990

[Possible mechanisms of the anti-inflammatory action of polyamines].

Carrageenin paw edema of rats was inhibited in a dose-dependent manner by subcutaneous administration of polyamines. The latter had to be administered at least 2 hr before carrageenin challenge to achieve such inhibition. Moreover, inhibition was blocked by the simultaneous injection of actinomycin D. Polyamines also inhibited local bluing reactions to histamine in rats and similarly had to be administered 3 hr previously to achieve inhibition. Polyamines were shown to be glucocorticoid-type anti-inflammatory drugs, and may be glucocorticoids mediators of the synthesis of the postulated vascular permeability inhibitory protein that do not inhibit phospholipase A2 activity. Neutrophil chemotaxis was inhibited by polyamines in a concentration-dependent manner. In contrast to the experience with carrageenin paw edema, simultaneous addition to actinomycin D did not block the inhibitory action of polyamines on neutrophil chemotaxis. These results suggest that polyamines possess at least 2 different anti-inflammatory mechanisms. The first is mediated by the synthesis of an anti-inflammatory protein, and the second consist of direct action on leukocytes.

Animals↗
PubMed1990

Age estimation of two unidentified bodies by amino acid racemization in their teeth.

In order to obtain more accurate and reliable information for estimating the age from the teeth by amino acid racemization, we examined the D/L ratios not only of the total amino acids, but also of insoluble collagen and soluble peptides, prepared by fractionation of tooth protein. We, thereby, attempted to estimate the age by examining tooth samples from two unidentified bodies. In both cases, we were able to estimate almost accurately the age from the total amino acids and also from the insoluble collagen as well as the soluble peptides (+/- 0 to +4 years). Age estimation from the average of the D/L ratios of 3 fractions was as accurate as +/- 3 years. Therefore, a differential examination of amino acid fractions seemed to increase information dramatically for age estimation by racemization of amino acids. As a result, we were able to expect more reliable results.

Adolescent↗
PubMed1990

Morphological changes in human and animal enamel rods with heating--especially limits in temperature allowing discrimination between human and animal teeth.

Little has been revealed about making discrimination between human and animal using a piece of tooth found in a burned cadaver. From the viewpoint of forensic dental medicine, it is a theme no less valuable. This experimental study was attempted for this reason. Teeth from an individual body of human, monkey, dog, rabbit and rat were heated in turn on the muffle furnace. The heating temperatures were from 200 degrees C to 1,000 degrees C in time spans of 5, 30 and 60 minutes. After heating, each tooth and its control were observed by a scanning electron microscope (magnifying power: 3,500 x or 3,600 x). At heating temperature of 500 degrees C or 600 degrees C, enamel starts to come off in lumps and cracks appear in the enamel rods. The arcaded form in human and monkey, hexagon in dog, elongated chain in rabbit, rows of short, diagonal parallel lines equally directed at every other row in rat--these basic morphological features of the enamel rods--are retained till the heat reaches 700 degrees C. The enamel rods in monkey yield to heat more easily than those in human. At 600 degrees C many cracks appear and deformation of the arcaded form starts. With heating of 5 minutes at 800 degrees C the outline of the pattern is obscured. Human and animal teeth get varied forms of cracks in the enamel rods with heating more than 5 minutes at 800 degrees C. The structure of the enamel rods is broken and morphological characteristics are lost. This makes discrimination of human and animal quite difficult.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Estimating age through the amino acid racemization of acid-soluble dentinal peptides.

We studied the possibility of estimating age through the amino acid racemization of acid-soluble dentinal peptide (SP). The correlation of the D/L ratio of aspartic acid and the actual age was the highest in the SP extracted with 1 M HCl (r = 0.996, sigma = +/- 0.8), followed by the total amino acids (TAA:r = 0.995, sigma = +/- 1.0), and the SP extracted with 2 M HCl (r = 0.980, sigma = +/- 1.9) and then SP extracted with 5 M HCl (r = 0.951, sigma = +/- 2.7). The rate of the racemization reaction decreased in the order of SP extracted with 1 M HCl, 2 M HCl, 5 M HCl and the total amino acids (TAA). Consequently, an extraction with 1 M HCl seemed best for estimating the age from SP to serve actual cases.

Age Determination by Teeth↗
PubMed1990

Racemization velocity of aspartic acid in dentine.

To investigate the racemization of dentinal amino acids furthermore, and thereby to estimate age more accurately, fundamental heating experiments dealing with aspartic acid in dentine were carried out. The racemization velocity was determined and compared not only for the total amino acids (TAA), but for insoluble collagen (IC) as well as soluble peptide (SP) fractions. In TAA and IC, with the passage of time, their racemization deviated from the mode of the primary reaction, whereas in the SP, an extremely stable increase in D/L ratio was maintained for a longer time, fulfilling the mode of the primary reaction. When samples are left drying, the racemization velocity was greatest in the IC but considerably less in the SP, indicating results opposite to those found in the living state.

Age Determination by Teeth↗
PubMed1990

[Right ventricular outflow tract reconstruction with monocusp patch].

Two kinds of monocusp patch were used for reconstruction of right ventricular outflow tract in patients with a variety of congenital heart defects. A bovine pericardial patch with monocusp (MVOP) was used in 11 patients (group M), and a separate transannular outflow patch (STOP) with turned-down equine pericardial monocusp was used in 10 patients (group S). Mean age at operation was 9 years 5 months in group M, and 7 years 9 months in group S. There was one operative death in group M. Survivors have completed a mean follow-up of 19 months. There were no late deaths. In early postoperative period, mean peak systolic pressure gradient between right ventricle and main pulmonary artery was 21 +/- 11 mmHg in group M and 21 +/- 11 mmHg in group S, which were not statistically significant. During follow-up period, no significant increase of peak systolic pressure gradient was noted in both groups. In late postoperative period, pulmonary regurgitation was moderate in 7 and severe in 1 in group M, while it was non-significant in 1, mild in 6 and moderate in 2 in group S. The difference between two groups was significant (p < 0.005). In conclusion, both types of patches equally relieved right ventricular outflow obstruction, but STOP prevented postoperative pulmonary regurgitation more effectively.

Bioprosthesis↗
PubMed1989

Detection of dystrophin on two-dimensional gel electrophoresis.

A protein with MW approximately 350 k daltons and pI approximately 5.5, which was deleted in the dystrophic mouse (C57BL/10ScSn-mdx), was detected on two-dimensional gel electrophoresis with silver staining. Deletion of this protein was uniformly observed in the dystrophic mouse extensor digitus longus, soleus and cardiac muscle. This protein specifically reacted with the monoclonal antibody against the chemically synthesized N-terminal fragment of human dystrophin. The protein reacting with this monoclonal antibody was also detected in rabbit back-muscle, rat extensor digitus longus and human skeletal muscle at the same position as the mouse muscle protein, on the two-dimensional gel electrophoresis. Our results show that dystrophin is solubilized in 8M guanidine HCl and that the modified two-dimensional gel electrophoresis can be applied to separate dystrophin.

Animals↗
PubMed1989

High performance liquid chromatographic analysis of time-dependent changes in urinary excretion of indoleamines following tryptophan administration.

Analytical conditions of prepurification extraction and HPLC separation were optimized for determination of urinary serotonin and tryptamine. Under optimal conditions, serotonin, tryptamine and an internal standard were extracted with 15% v/v n-propanol in diethyl ether from urine samples alkalized with a phosphate buffer (0.75 mol/L, pH 10.0), and then they were re-extracted into an HCl solution (0.1 mol/L). Purified indoleamines were simultaneously separated by reversed-phase ion-pair HPLC with native fluorescence detection. Urinary serotonin and tryptamine were selectively determined within about 45 min per sample for the whole procedure. Analytical recovery, reproducibility and detection sensitivity were satisfactory for pursuing time-dependent changes in indoleamine levels. Urinary excretion profiles of serotonin and tryptamine in subjects dosed with L-tryptophan were successfully analyzed by our method.

Adult↗
PubMed1989

[A case of effusive-constrictive epicarditis found by electrocardiogram at a school health examination].

An effusive-constrictive pericarditis confined to the epicardium is extremely rare in childhood. We report case of a 7-year-old boy with such a condition. During an annual school health examination, he was found to have low voltage activities on electrocardiogram. On admission, physical examination showed markedly distended abdomen due to ascites and hepatomegaly. Two-dimensional echocardiography revealed small ventricular cavities, extremely dilated inferior vena-cava, and a moderate amount of pericardial fluids. Pericardial and epicardial thickening were also suspected. Retrospectively, epicardial thickening was suspected on computed tomogram as well. Cardiac catheterization showed a typical diastolic dip and plateau pattern on the right ventricular pressure tracing, and deep x and y descents on that of the right atrium, suggesting that not pericardial effusion, but pericardial thickening mainly contributed to the cardiac dysfunction. Pericardiocentesis did not improve the clinical symptoms and high central venous pressure. On thoracotomy, we unexpectedly found intact pericardium and fibrotic epicardium covering the whole heart, so epicardiectomy was performed. Despite the fact that most of the fibrotic epicardium was removed, there were no immediate responses such as decrease in central venous pressure within the first 5 days after the surgery. Furthermore, it was not until two months later that all symptoms and hemodynamic parameters returned to normal levels. There have been several case reports of isolated epicardial constriction associated with pericardial effusion in English literature. However, we are unaware of such a report n Japanese. We concluded that it is important to evaluate the hemodynamics before and after pericardiocentesis, and to detect peri-and/or epicardial thickening by serial echocardiography and CT scan.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

[A histological study of striated muscle and nerve fiber in the human caused by a high voltage electric current].

A case of an electrocution is reported, involving a 37-year-old man who while engaged in an electrical work, received an electric shock by touching an electric wire of 11,000 volts. Both of his arms had to be amputated. A piece of muscle tissue was removed from the amputated arm to be examined by light and electron microscopy. Under light microscopy, the muscle tissue, after myoglobin staining, showed a particular pattern that closely resembled the pattern on the skin of a python. Thus the author has named the pattern seen in this case as the "Python-pattern". The electron microscopy inspection revealed on myoglobin staining excessive stretching and fragmentation of the myofibrils where the myoglobin staining was negative in the slide.

Adult↗