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Biomedical subjects

T Takatsu

Publications and source records attributed to T Takatsu.

At least 37 records · Page 2Linked to original sources
PubMed1994

Relationship between surface area for adhesion and tensile bond strength--evaluation of a micro-tensile bond test.

OBJECTIVES: The purpose of this study was to test the null hypothesis that there is no relationship between the bonded surface area of dentin and the tensile strength of adhesive materials. METHODS: The enamel was removed from the occlusal surface of extracted human third molars, and the entire flat surface was covered with resin composite bonded to the dentin to form a flat resin composite crown. Twenty-four hours later, the bonded specimens were sectioned parallel to the long axis of the tooth into 10-20 thin sections whose upper part was composed of resin composite with the lower half being dentin. These small sections were trimmed using a high speed diamond bur into an hourglass shape with the narrowest portion at the bonded interface. Surface area was varied by altering the specimen thickness and width. Tensile bond strength was measured using custom-made grips in a universal testing machine. RESULTS: Tensile bond strength was inversely related to bonded surface area. At surface areas below 0.4 mm2, the tensile bond strengths were about 55 MPa for Clearfil Liner Bond 2 (Kuraray Co., Ltd.), 38 MPa for Scotchbond MP (3M Dental Products), and 20 MPa for Vitremer (3M Dental Products). At these small surface areas all of the bond failures were adhesive in nature. SIGNIFICANCE: This new method permits measurement of high bond strengths without cohesive failure of dentin. It also permits multiple measurements to be made within a single tooth.

Composite Resins↗
PubMed1994

The influence of age and depth of dentin on bonding.

OBJECTIVES: The purpose of this study was to investigate what influence the two variables of dentin depth and age may have on the tensile bond strengths of three bonding systems. METHODS: Dentin discs prepared from human molars were divided into young and old, superficial and deep surfaces. Three bonding systems, Scotchbond Multi-purpose (3M Dental Products), Superbond D-liner (Sun Medical Co.), and Liner Bond II (Kuraray Co.) were the materials tested for tensile bond strength. In addition, the structural variation of the resin-impregnated, or hybrid, layer was compared among the two variables and three bonding systems. RESULTS: Tensile bond strengths exceeding 10 MPa were obtained for all materials. After ANOVA, an effect on tensile bond strength could be attributed to dentin age or depth for only Superbond D-liner used on deep-young dentin as compared with old-superficial dentin. All other group comparisons failed to show any variation between dentin depth or age. However, specimens bonded to deeper dentin showed slightly lower strengths. SEM observations showed thicker resin-impregnated layers for Scotchbond MP and Superbond D-liner compared with Liner Bond II. Liner Bond II exhibited a thinner and more diffuse resin-impregnated layer, believed to be due to the different dentin conditioning method. SIGNIFICANCE: Dentin age or depth may not show as great an influence on bond strengths with the newer type of bonding systems. The resin-impregnated layer quality, rather than thickness, is believed to be the most important factor for obtaining high tensile bond strengths.

Age Factors↗
PubMed1994

Long-term results of the anterior cervical spondylodesis.

From 1974 to 1992, anterior cervical spondylodesis was performed in 163 patients of cervical spondylotic myelopathy, cervical spondylotic radiculopathy, traumatic spinal injury, ossification of the posterior longitudinal ligament, or cervical spondylitis. Forty-five of these patients were followed for more than 4 years. To analyze the long-term results of anterior cervical spondylodesis, a radiological examination was performed in these 45 patients and magnetic resonance imaging was conducted in 41 of them. Postoperative spondylotic changes were observed radiologically in 23 (51.1%) of the 45 patients. Anterior bony spur was more frequently observed than posterior bony spur in these postoperative spondylotic changes. Postoperative canal stenosis caused by the bulging of the discs and the ligamentum flavum was frequently demonstrated with hypo- or isointense signal on T2-weighted images by magnetic resonance imaging in patients followed long term after surgery and in patients with malalignment of the cervical spine due to kyphosis of the fused vertebrae and multisegmental fusion. Neurological improvement was less in patients with bulge of the discs and the ligamentum flavum seen in magnetic resonance imaging than in patients without it. The bulge of the ligamentum flavum was histopathologically defined as hypertrophy of the ligament.

Adolescent↗
PubMed1993

Tensile bond strength and curing gap formation of a dentin bonding resin.

Tensile bond strength and contraction gap tests were carried out using a new dentin bonding resin in association with various dentin conditioning and priming materials in vitro. For the tensile bond test, significant differences were found between the nonconditioned and conditioned dentin, and the primed and non-primed dentin surfaces. The strongest bond was obtained using a combination of phosphoric acid conditioning and priming with HEMA in glutaraldehyde at 151.3 kgf/cm2. Gap test results showed the presence of gaps in all of the test groups, but with variation in the extent of gap formation. A not significant, inverse correlation was determined between the tensile bond strength and gap tests (R = -0.65). The new bonding resin obtained good bond strengths in all cases, but high bond strengths can only be obtained with a combination of etching and priming. Similarly, the smallest gaps were associated with the etched and primed groups.

Animals↗
PubMed1993

Effect of aging on dentin bonding.

The purpose of this paper was to evaluate the effect of aging of dentin on the tensile bond strengths of four dentin bonding systems using proximal dentin of premolars extracted from young (aged from 9-21 years) and old (aged from 42-64 years) patients. Clearfil Linerbond System and Super Bond D-Liner showed higher bond strengths to both young and old teeth than those of Clearfil Photo Bond and Resto Bond 3. However, similar bond strengths to both young and old teeth for all four products were obtained despite the effects of aging. Furthermore, a SEM study of the site of bond failure revealed the persistence of the resin impregnated layer on the dentin surface, in spite of the difference of bonding system and dentin, indicating that adhesive failure tended to occur at the interface between the bonding resin and the resin impregnated layer.

Adolescent↗
PubMed1992

Redundant nerve roots of the cauda equina caused by lumbar spinal canal stenosis.

To investigate pathogenesis of redundant nerve roots of the cauda equina, which were concomitant with severe lumbar spinal canal stenosis, six cadavers were examined anatomically and histopathologically, and quantitative analysis of nerve fibers was performed. In this anatomic study, it was observed that all the redundant nerve roots passed through the constriction of the spinal canal. No significant pathologic change was detected in the spinal ganglia and in the spinal cords except for the posterior column, in which dorsal redundant roots were entering. Redundant nerve roots of unequal length also were observed in the anatomic study. The spatial distribution of redundant nerve roots and the extent of degeneration of nerve fibers in them were established by these histopathologic and quantitative studies. These facts indicated a close causal relationship between redundant nerve roots and constriction of the spinal canal, and that the pathogenesis of redundant nerve roots was a squeezing force acting on the nerve roots at the area of spinal canal constriction.

Cauda Equina↗
PubMed1990

Aladapcin, a new microbial metabolite that enhances host resistance against bacterial infection. Production, isolation, physico-chemical properties and biological activities.

We have constructed a new screening system for detecting microbial products that enhance host resistance against bacterial infection. It was found that a new compound with such activity is produced by a soil isolate classified as Nocardia sp. SANK 60484. The compound was isolated from the culture filtrate of the organism and named aladapcin after its amino acid composition. Aladapcin was obtained as an amphoteric white amorphous powder with the molecular formula, C13H25N5O5. It consists of 2 mol of D-alanine and 1 mol of meso-diaminopimelic acid. From the analysis of IR, 1H NMR and FAB-MS spectra, the structure was assigned to be a tripeptide. Aladapcin enhanced host resistance against an experimental Escherichia coli infection in mice at doses ranging between 1 and 100 micrograms/kg.

Adjuvants, Immunologic↗
PubMed1990

[Clinical trial of 111In-antimyosin antibody imaging: (4). Effect of reperfusion in acute myocardial infarction].

Effects of reperfusion by intra-coronary thrombolysis (ICT) or percutaneous transluminal coronary angioplasty (PTCA) on the myocardial imaging using 111In-labeled antimyosin monoclonal antibody Fab (In-AM) were studied. Reperfusion by ICT or PTCA was done in 16 patients (reperfusion group) and recanalization was seen in 14. Positive images were obtained in 28 of 30 patients (93%) with acute myocardial infarction (onset to imaging: 9.9 +/- 9.8 days). Among the reperfusion group, one patient in whom PTCA was done early after the onset of chest pain and CPK did not elevate showed no significant uptake of radioactivity at cardiac region, while other 15 patients with elevation of CPK demonstrated positive images. Planar images (anterior, left anterior oblique 45 degrees, left lateral) were divided into 15 segments and infarct size (antimyosin-segment) was determined by sum of positive segments on each image. There were no significance between the infarct size in the reperfusion group (7.2 +/- 2.9) and that in the non-reperfusion group (6.9 +/- 3.4). Intensity of the accumulation of radioactivity in each image was classified into 5 grades by comparison with uptake of the liver (antimyosin-score). Reperfusion group demonstrated high intensity compared with non-reperfusion group (2.6 +/- 0.7 vs. 2.0 +/- 0.4; p less than 0.05). Thus, In-AM imaging may be influenced by coronary blood flow, which should be taken into consideration in the interpretation of In-AM imaging.

Adult↗
PubMed1988

Effect of preanesthetic famotidine on gastric volume and pH.

The effect of preanesthetic 20 mg of famotidine on gastric fluid volume and pH were studied in patients scheduled for elective surgery. One hundred and twenty-eight patients were divided into four groups-control, intravenous, intramuscular and oral with 32 patients in each group. Patients in placebo group received no famotidine and served as control. Patients in the intravenous and intramuscular groups were administered famotidine one hour before surgery. Patients in the oral group were administered famotidine the night before and on the morning of surgery. Gastric volume in the control group was 19.1 +/- 10.8 ml; in the intravenous group, 7.4 +/- 6.4 ml; in the intramuscular group, 7.3 +/- 6.9 ml; and in the oral group, 7.1 +/- 6.9 ml. Gastric pH was 3.4 +/- 2.3, 6.8 +/- 1.1, 6.9 +/- 1.6, and 6.7 +/- 1.2 in groups one through four, respectively. When compared to the control group, famotidine significantly decreased gastric volume and increased gastric pH. There were no statistical differences among the different modes of administration. No adverse effects were observed in this study. It is concluded that preanesthetic management of 20 mg of famotidine reduced the risk of acid aspiration pneumonitis.

Clinical Trial↗
PubMed1987

Effects of captopril on cardiorenal hemodynamics in patients with severe chronic congestive heart failure.

The effects of captopril on cardiorenal function were studied in patients with chronic congestive heart failure. A single oral dose of captopril in 16 patients significantly increased cardiac indices and decreased total systemic vascular resistance. These changes were greater in subjects with higher baseline plasma renin activity (PRA). The increase in PRA and decrease in plasma aldosterone were also greater in this group. During 7 days of captopril therapy, renal plasma flow distinctly increased in 10 patients in whom renal function was followed. The increase in renal blood flow was greater in subjects with higher PRA. Simultaneous infusion of aprotinin in eight of these subjects did not affect the captopril-induced increase in renal plasma flow: these responses were the same in both PRA subgroups. The results suggest that captopril reduces total systemic vascular resistance in patients with chronic congestive heart failure through the inhibition of the renin-angiotensin system and the preferential renal vasodilating effect of captopril seems exclusively to be the sole result of this inhibition, with the kallikrein-kinin system or kinin-mediated prostaglandins not playing a major role.

Blood Pressure↗
PubMed1987

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. I. Taxonomy of producing organism.

Strain SANK 60983, an actinomycete isolated from a soil sample, was found to produce the new glycopeptide antibiotics, chloropolysporins A, B and C. Short chains of spores occur in the both aerial and substrate hyphae. meso-Diaminopimelic acid is present in the cell wall and galactose and arabinose in the whole-cell hydrolysate. Mycolic acid is absent. On the basis of the morphological, cultural and physiological characteristics, this strain was determined to be a new species of Faenia designated Faenia interjecta sp. nov. The type strain of F. interjecta Okazaki and Enokita is SANK 60983.

Anti-Bacterial Agents↗
PubMed1987

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. II. Fermentation, isolation and physico-chemical characterization.

New antibiotics, chloropolysporins A, B and C, were found in the culture broth of an actinomycete identified as Faenia interjecta sp. nov. They were isolated from the culture filtrate by column chromatography on various resinous adsorbents, followed by preparative reverse phase HPLC. Chloropolysporins A, B and C possessed all the same new aglycone composed of actinoidic acid, 3-chloro-4-hydroxyphenylglycine, N-methyl-p-hydroxyphenylglycine and vancomycinic acid. From elementary analyses and mass spectroscopic measurements, the molecular formulae of chloropolysporins A, B and C appear to be C89H99O39N8Cl3 (MW 2,008), C83H89O34N8Cl3 (MW 1,846) and C77H79O30N8Cl3 (MW 1,700), respectively. Their physico-chemical characterizations including molecular formulae revealed that chloropolysporins A, B and C were new members of glycopeptide antibiotics.

Anti-Bacterial Agents↗
PubMed1987

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. III. Structure elucidation of chloropolysporins.

Structure elucidations of chloropolysporins A, B and C were achieved mainly by chemical degradation studies. These components possessed the same pseudoaglycone in common and their structures were closely related to that of beta-avoparcin. The structures of chloropolysporins differ from that of beta-avoparcin in the presence of vancomycinic acid moiety instead of monodechlorovancomycinic acid moiety and glucose, not ristosaminylglucose, in its side chain. Chloropolysporin C was identified as derhamnosylchloropolysporin B based on its 1H NMR and mass spectral analysis and degradation studies. Two minor components, chloropolysporins D and E, were identified as the epimers of each of chloropolysporins B and C, respectively, based on their Cotton effects and retention times on reverse phase HPLC.

Anti-Bacterial Agents↗
PubMed1987

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. IV. Partially deglycosylated derivatives.

Chloropolysporins A, B and C, new members of the glycopeptide antibiotic family, were enzymatically and chemically converted to their partially deglycosylated derivatives. The alpha- and beta-avoparcins were also deglycosylated by the same method. The conversions were achieved by treatments with rhamnosidase (Naringinase) and alpha-mannosidase, and by mild acid hydrolysis.

Anti-Bacterial Agents↗
PubMed1987

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. V. Comparative studies of the biological properties.

Chloropolysporins A, B and C, as well as derivatives prepared from this group and alpha- and beta-avoparcins by enzymatic and mild acid hydrolysis, were active against Gram-positive bacteria including clinically isolated methicillin-resistant Staphylococci (MIC 0.39-6.25 micrograms/ml) and anaerobic enterobacteria (MIC 0.10-1.56 micrograms/ml). Derhamnosyl and demannosyl derivatives from both groups of antibiotics showed stronger activities than the parent compounds. The MIC and MBC values against Staphylococci were similar and were not effected by the presence of serum. Moreover, chloropolysporin C exhibited very strong synergistic effects with various beta-lactam antibiotics against methicillin-resistant strains of Staphylococcus aureus. Some of these compounds also protected mice from experimental infection with S. aureus. Acute toxicities of chloropolysporin by intravenous administration ranged from 215-290 mg/kg in mice. Chloropolysporin B as well as other glycopeptide antibiotics, showed distinctive growth promoting activity in broiler chickens.

Anti-Bacterial Agents↗
PubMed1985

A varnish to prevent etching unrestored enamel.

The prognosis of acid-etched enamel was investigated in both laboratory and clinical experiments. Acid etching produced irregularities even on the prismless layer that covers prism enamel. The irregularities produced by etching are not remineralized in vivo but are filled with organic debris. Brushing reduced the depth of the irregularities but did not eliminate them. A protective varnish against acid etching was developed. The varnish also serves as a guide to facilitate removal of excess resin beyond the cavosurface margin.

Acid Etching, Dental↗