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Biomedical subjects

A Okamoto

Publications and source records attributed to A Okamoto.

At least 145 records · Page 8Linked to original sources
PubMed1993

Pulpal response to a new light-activated fluoride releasing liner.

The purpose of this study was to investigate the degree of pulp irritation of a newly developed light-activated fluoride-releasing adhesive resin liner using canine teeth compared to the amount caused by a negative control, zinc oxide eugenol cement (ZOE), and a positive control, silicate cement (silicate). In the cases of unexposed pulp, this experimental liner showed none, slight or moderate pulpal changes at 3 d postoperatively. At 30 and 90 d, no pulpal response to the experimental liner was detected in almost all cases. These findings were similar to the ZOE and better than the silicate. There was less evidence of pulpal irritation produced by the experimental liner. This material seems to be safe to the pulp under the conditions of this study.

Analysis of Variance↗
PubMed1993

An analysis of failures in primary cervical anterior spinal cord decompression and fusion.

Recently, postoperative results of cervical spondylosis, disc herniation, and ossification of the posterior longitudinal ligament (OPLL) after anterior cervical surgeries have improved. However, occasional unsatisfactory cases needing a second operation remain. We analyzed and developed strategies for multioperated neck (MON) cases; all patients had two operations. From 1965 to 1988, 443 cervical anterior surgeries were performed in our hospitals; 53 (12.0%) of these patients needed second operations. These MON cases were classified by the following causes: pseudarthrosis, graft fracture, insufficient decompression, misdiagnosis, and adjacent disc problems. These groups were analyzed, and the resulting surgical strategies, including indications and techniques of anterior surgery, are described.

Adolescent↗
PubMed1993

Analysis of DNA fragmentation in human uterine cervix carcinoma HeLa S3 cells treated with duocarmycins or other antitumor agents by pulse field gel electrophoresis.

Pulse field gel electrophoresis using a contour-clamped homogeneous electric field was applied for the analysis of DNA-fragmenting activity of antitumor agents towards human uterine cervix carcinoma HeLa S3 cells. Duocarmycins (DUMs), novel antitumor antibiotics with ultrapotent cell growth-inhibitory activities, caused DNA fragmentation at 10 times their IC50 values at 2 h exposure. At 100 times their IC50 values, the size of the smallest fragments was about 245 kilobase pairs (kbp). DUMA, DUMB1 and DUMB2 exhibited similar DNA fragmentation patterns, suggesting similar action mechanisms. DNA fragmentation was also detected in cells treated with radical producers, intercalators and topoisomerase inhibitors. Two bands of about 1800 and 1500 kbp were commonly detected in the cells treated with DUMs and these agents. In addition, fragments of about 900 kbp were detected in the cells treated with a topoisomerase inhibitor, 4'-(9-acridinylamino)methane-sulfon-m-anisidine, and fragments in the broad size range between 700 and 245 kbp in the cells treated with radical producers, bleomycin and neocarzinostatin. DUMs showed a characteristic DNA fragmentation pattern, since both types of fragments induced by the topoisomerase inhibitor and the radical producers were simultaneously detected, suggesting a novel mode of interaction with DNA. DNA-crosslinking agents and mitotic inhibitors did not induce DNA fragmentation under these conditions. The pulse field gel electrophoresis is potentially useful for characterizing DNA-cleaving activity of various antitumor agents at the cellular level.

Antibiotics, Antineoplastic↗
PubMed1993

Maternal and child health in Indonesia.

AIIKU-HAN activity was initiated by the Imperial Gift Foundation BOSHI-AIIKU-KAI in Japan in 1936 and has been introduced and accepted to community-based maternal and child health development in Indonesia through the international cooperation project conducted by Japan International Cooperation Agency (JICA) in order to encourage community health activities carried out by Indonesian women volunteers. As AIIKU-HAN activity in Japan and Dasa Wisma health activity in Indonesia have much in common, transferring concepts, methods and experiences met less obstacles when Indonesian community health volunteers learned AIIKU-HAN activity. Experience gained while developed countries were less developed can be transferred by shifting the time-scale of history in developed countries.

Adult↗
PubMed1993

Neutral endopeptidase (EC 3.4.24.11) modulates the contractile effects of neuropeptides on muscle cells from the guinea-pig stomach.

The objectives of this investigation were to characterize neuropeptide-degrading enzymes on the surface of gastric muscle cells and to determine their physiological function. Neutral endopeptidase (NEP, EC 3.4.24.11) activity was measured using the fluorogenic substrate glutaryl-Ala-Ala-Phe-4-methoxy-2-naphthylamine. The NEP inhibitors phosphoramidon and DL-thiorphan (1 microM) inhibited degradation of the substrate by gastric muscle membranes by 100% and by freshly dispersed gastric muscle cells by 55-60%. The phosphoramidon or DL-thiorphan-inhibitable activity, attributed to NEP, of membranes was 112 +/- 4.0 pmol h-1 (micrograms protein)-1 and of cells was 4.2 +/- 0.8 nmol h-1 (10(6) cells)-1. This activity was associated with membranes prepared from cells and was not detected in the cytoplasm or in the cell incubation solution. Gastric muscle membranes were fractionated by electrophoresis and analysed by Western blotting using two NEP antisera. Both antisera recognized a protein in membranes with an electrophoretic mobility identical to that of recombinant human NEP and an apparent molecular mass of approximately 95 kDa. Neuropeptides were degraded by membranes with specific activities in the order of [Leu5]enkephalin > [Met5]enkephalin > gastrin-releasing peptide-10 (GRP-10) > [D-Ala2][Leu5]enkephalin > somatostatin-14. Phosphoramidon and DL-thiorphan similarly inhibited the degradation of GRP-10 (mean of 35% inhibition), somatostatin-14 (57%) and the aminopeptidase-resistant analogue, [D-Ala2][Leu5]enkephalin (75%). When aminopeptidases were inhibited with amastatin (10 microM) phosphoramidon inhibited degradation of [Leu5]enkephalin (54%) and [Met5]enkephalin (100%). Phosphoramidon increased the potency of the contractile effects of neuropeptides on muscle cells by > 280-fold for somatostatin-14, 17-fold for GRP-10, 18-fold for [Met5]enkephalin and 14-fold for [Leu5]enkephalin. The results show that an NEP-like enzyme on the surface of gastric muscle cells degrades and inactivates enkephalins, GRP-10 and somatostatin-14 and acts in a manner analogous to that of acetylcholinesterase in the neuromuscular junction of skeletal muscle.

2-Naphthylamine↗
PubMed1993

Downregulation of neutral endopeptidase (EC 3.4.24.11) in the inflamed rat intestine.

Intestinal inflammation induced by the nematode Trichinella spiralis is accompanied by increased intestinal concentrations of substance P, a mediator of inflammation and a stimulant of smooth muscle contraction, and by intestinal hypermotility. The expression of neutral endopeptidase (NEP), a cell surface enzyme that degrades substance P in the extracellular fluid, was examined in the inflamed intestine. NEP enzymatic activity, measured by a fluorometric assay, was reduced by 84-fold in jejunal mucosa-circular muscle and by 12-fold in jejunal longitudinal muscle-myenteric plexus within 6 days after infection with T. spiralis. The downregulation was unaffected by treatment with betamethasone and was still observed in athymic animals. NEP protein levels, examined by Western blotting, confirmed the loss of NEP from inflamed tissue. The specific activity for degradation of substance P was reduced by sixfold in jejunal mucosa-circular muscle and by twofold in jejunal longitudinal muscle-myenteric plexus of rats infected with T. spiralis compared with uninfected controls. Thus the downregulation of NEP resulted in reduced substance P degradation, which may contribute to functional abnormalities of the inflamed intestine.

Analysis of Variance↗
PubMed1993

In vivo wear pattern of experimental composite resins based on different resin monomers.

This study investigated the effects of various monomer systems on composite resin wear in vivo. Experimental light-cured composite resins were prepared employing four different monomer systems: (1) Bis-GMA type, (2) D-2. 6E type, (3) UDMA type, (4) UTMA type. The resin monomers consisted of 70wt% main monomer and 30wt% TEGDMA. These composites contained 80wt% fine quartz. The resins were placed in 2 mm diameter cylindrical cavities located in the occlusal contact area or the contact free area in cast crowns, temporarily set in a mouth. The crowns were removed at monthly intervals, for longitudinal SEM observation. Two months after setting, wear was analyzed, using an electron probe surface roughness analyzer. Microabrasion of the resin matrix and loss of filler particles were observed for all types of monomer systems. The effect of matrix resin systems on occlusal wear was smaller than that of filler systems.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1993

In vivo wear pattern of experimental light-cured hybrid composite resins.

This study evaluated the effect of various types of microfiller on the in vivo wear resistance of composite resins. Experimental light-cured composites with two different microfiller systems were prepared: (1) 56 wt % fine quartz filler, 21 wt% organic filler and 3 wt% colloidal silica filler (Hybrid type 1), and (2) 64 wt% fine quartz filler and 21 wt% colloidal silica filler (Hybrid type 2). The resin monomer consisted of 50 wt % Bis-GMA and 50 wt% TEGDMA. These materials were placed in 2 mm diameter cylindrical cavities located in the OCA (occlusal contact area) or the CFA (contact free area) in cast gold-silver-palladium alloy full coverage crowns, which were temporarily set in a volunteer patient's mouth. The crowns were removed at monthly intervals for SEM observation. Hybrid type 1, which contained organic fillers, showed bulk fractures in the OCA, by the second month of the experiment. However, reinforcement of the resin matrix by dispersion of microfiller provided Hybrid type 2 with superior wear resistance for up to two months.

Adult↗
PubMed1993

Direct observation of in vivo wear of composite resins.

This study developed a simple method for in vivo evaluation of wear on composite resins and examined the role of filler particles in this process. Experimental light-cured composite resins with two different filler systems were prepared: (1) 81 wt% fine quartz filler (Conventional type) and (2) 73 wt% organic filler (Microfilled type). The resin monomer consisted of 50 wt% Bis-GMA and 50 wt% TEGMA. These materials were placed in cylindrical cavities 2 mm in diameter located in the OCA (occlusal contact area) or the CFA (contact free area) in Au-Pd crowns, temporarily set in a volunteer's mouth. The crowns were removed at monthly intervals for longitudinal SEM observation. Results showed that the newly developed method was useful for observing the in vivo wear-patterns of composite resins. The two experimental composite resins with different filler systems showed quite different wear-patterns.

Adult↗
PubMed1992

Prolonged circulation time in vivo of large unilamellar liposomes composed of distearoyl phosphatidylcholine and cholesterol containing amphipathic poly(ethylene glycol).

The effect of poly(ethylene glycol) (PEG) on the circulation time of liposomes in mice was examined by employing amphipathic PEGs (phosphatidylethanolamine (PE) derivatives of PEG) with average molecular weights of 1000, 2000, 5000 and 12,000. The activity of dioleoyl phosphatidylethanolamine-PEG (DOPE-PEG) in prolonging the circulation time of egg phosphatidylcholine/cholesterol large unilamellar liposomes (ePC/CH LUVs) (200 nm) was proportional to the molecular weight of PEG, i.e., 12000 = 5000 greater than 2000 greater than 1000. On the other hand, inclusion of distearoylphosphatidylethanolamine-PEG (DSPE-PEG) or dipalmitoyl-phosphatidylethanolamine-PEG (DPPE-PEG) of low molecular weight such as 1000 and 2000 in distearoylphosphatidylcholine (DSPC)/CH LUVs or dipalmitoyl phosphatidylcholine (DPPC)/CH LUVs effectively increased their blood circulation time. At least 3 mol% of amphipathic PEG in liposomes was required for activity. Addition of CH, which has a bilayer-tightening effect, to DSPC/CH/DSPE-PEG2000 LUVs further increased the blood residence time. A size of less than 300 nm was essential for prolonging the residence time of amphipathic PEG-containing liposomes in blood. DSPC/CH/DSPE-PEG2000 LUVs (1:1:0.13, m/m) containing 6 mol% of PEG and 200 nm in diameter remained in the circulation for over 24 h after injection and may be clinically useful for sustained release of an entrapped drug in the bloodstream and for drug accumulation in solid tumors.

Animals↗
PubMed1992

Purification and characterization of 3-mercaptolactic acid S-conjugate oxidases.

Two enzymes catalysing the oxidative formation of 3-mercaptopyruvic acid S-conjugates from L-3-mercaptolactic acid S-conjugates were purified to apparent homogeneity from rat liver cytosol. The two enzymes, tentatively designated MLO-I and MLO-II, showed a molecular mass of 160 and 250 kDa and were composed of four and six subunits of 41 and 39 kDa, respectively. Both enzymes possessed flavin mononucleotide as prosthetic group and oxidized several aromatic and aliphatic S-substituted L-3-mercaptolactic acids as well as alpha-hydroxy acids such as L-3-phenyllactic acid and L-2-hydroxyisocaproic acid. Glycolic acid and 3-(4-hydroxyphenyl)-lactic acid were the specific substrates for MLO-I and MLO-II, respectively. Neither of the enzymes oxidized beta- and gamma-hydroxy acids such as 3- and 4-hydroxybutyric acid. 2-Hydroxyisobutyric acid, ethyl-2-hydroxybutyrate, malic acid, 1-butanol, benzyl alcohol and L-leucine did not act as substrates for the enzymes. MLO-I and MLO-II exerted their maximum activities around pH 5.5 with Km of 0.5 and 0.25 mM and Vmax of 0.9 and 0.2 mumol/min/mg, respectively, when S-(4-bromophenyl)-3-thiolactic acid was used as substrate. MLO-I was inhibited by sulphydryl-modifying agents, while MLO-II was not. Both enzymes were strongly inhibited by divalent metal ions. These results indicate that MLO-I and MLO-II are different from L-amino acid oxidase (EC 1.4.3.2), malate oxidase (EC 1.1.3.3), L-alpha-hydroxy acid oxidase (EC 1.1.3.15) and glycolate oxidase (EC 1.1.3.1). The present enzymes are likely to be involved in the formation of cysteine conjugates from L-3-mercaptolactic acid S-conjugates in conjunction with cysteine conjugate aminotransferases.

Animals↗
PubMed1992

Synthesis of sulfonate analogs of bile acids.

Sulfonate analogs of C23 and C24 bile acids were synthesized from norcholic, norchenodeoxycholic, norursodeoxycholic, nordeoxycholic, norhyodeoxycholic, cholic, deoxycholic, hyodeoxycholic, and lithocholic acids. The principal reactions used were (1) reduction of the bile acids with NaBH4 to the corresponding bile alcohols, (2) selective tosylation of the terminal hydroxyl group, (3) iodination of the tosyl esters with NaI, and (4) treatment of the iodides with Na2SO3 to form the sulfonate analogs of the bile acids. The sulfonate analogs showed polarity similar to that of taurine-conjugated bile acids on thin-layer chromatography. The carbon 13 nuclear magnetic resonance spectral data for the sulfonate analogs were tabulated.

Bile Acids and Salts↗
PubMed1992

Anticellular and antitumor activity of duocarmycins, novel antitumor antibiotics.

The anticellular and antitumor activities of novel antitumor antibiotics, duocarmycins (DUMs), were examined against human and murine tumor cells. DUMs consist of five compounds, A, B1, B2, C1 and C2, which possess a pharmacophore similar to that of CC-1065, a previously isolated antibiotic. Among them, DUMA exhibited ultrapotent growth-inhibitory activity with an IC50 value of 6 pM against human uterine cervix carcinoma HeLa S3 cells. DUMA and DUMB1 also inhibited the growth of adriamycin (ADM)-resistant lines of human nasopharynx carcinoma KB cells and breast carcinoma MCF-7 cells as well as their sensitive lines. DUMs inhibited the growth of s.c.-inoculated murine tumors such as B16 melanoma, sarcoma 180, M5076 sarcoma and colon 26. DUMs were also significantly effective in increasing the lifespan of i.p.-inoculated B16 melanoma-bearing mice, although their effect was marginal against other i.p.-inoculated tumors. As a whole, DUMB1 exhibited superior activity to the other four compounds. DUMB1 rapidly inhibited the incorporation of [3H]-TdR into macromolecules of HeLa S3 cells as compared with that of [3H]UR or [3H]leucine. DNA strand breaks were detected in DUMB1-treated HeLa S3 cells by agarose gel electrophoresis with a contour-clamped homogeneous electric field apparatus. These results indicate that DUMs possess interesting biological activities as DNA-targeting antitumor antibiotics.

Animals↗
PubMed1992

Interaction between polyethylene films and bromhexine HCl in solid dosage form. IV. Prevention of the sorption by addition of magnesium aluminum silicate.

The effects of magnesium aluminum silicate (MAS) addition on the sorption of bromhexine HCl to polyethylene film in tablets were studied. The addition of MAS prevented the sorption of bromhexine HCl to polyethylene film. In order to investigate the mechanism, the interaction between bromhexine HCl and MAS was studied by the powder X-ray diffraction method. It was observed that bromhexine HCl was preferentially adsorbed to the surface of MAS rather than to polyethylene film. The adsorption was accelerated at high temperature and reduced pressure conditions. The sorption of bromhexine base and bromhexine HCl to packaging material were compared using tablet dosage forms. The sorption of bromhexine base to polyethylene film was greater than that of bromhexine HCl.

Aluminum Compounds↗
PubMed1992

Effects of frequency and intensity of sound on cochlear blood flow.

Laser Doppler flowmetry demonstrates that loud sound induces a decrease of blood flow in the cochlea of the guinea pig. In this experiment, we observed the effects of frequency and intensity of sound on cochlear blood flow using 15 guinea pigs. In the first 5 guinea pigs, a Doppler probe was attached to the basal turn of the cochlea and sounds of 6, 7, 8, 9 and 10 kHz were delivered to the ear serially from lower to higher frequency, i.e. from 6 kHz to 10 kHz. In the next 5 guinea pigs, the sound was delivered from higher to lower frequency, i.e. from 10 kHz to 6 kHz. The sound intensity delivered to the ear was changed from lower to higher intensity (80 to 120 dB SPL by 10 dB width) at each frequency. In the last 5 guinea pigs, the blood flow in the basal, second, third, and fourth turns of the cochlea was measured at 120 dB SPL of 10 kHz. No change of blood flow was seen in the cochlear basal turn at 6 and 7 kHz up to 120 dB SPL, but a decrease of blood flow was found at 110 and 120 dB SPL at 8, 9, and 10 kHz. On the other hand, the sound of 120 dB SPL at 10 kHz induced a decrease of blood flow only in the basal turn of the cochlea. Our results suggest that there is a corresponding blood flow area which is sensitive to specific frequency in the cochlea.

Animals↗
PubMed1992

The effects of various clinical factors on marginal enamel micro-cracks produced around composite restoration.

In this study, enamel micro-cracks produced around composite restorations were observed on surfaces and vertical sections, using a stereomicroscope and a scanning electron microscope (SEM). The effects of various clinical factors, i.e. the curing system, the marginal form and the polishing period after filling, on the incidence of marginal enamel micro-cracks were examined. Enamel micro-cracks were observed on all of the class 1 and 5 composite restorations when the cavity had no marginal bevel and the restorations were polished immediately after filling. Enamel micro-cracks distributed approximately parallel to the cavity margin and located 0.01-0.3 mm from the restored cavity margin. The occurrence of enamel micro-cracks was higher in light-cured composite resin restorations than in chemical-cured ones, for non-beveled cavities when polished 10 min or 24 hours after filling. The occurrence of micro-cracks was reduced by marginal beveling and delayed polishing.

Composite Resins↗