Biomedical subjects
Publications and source records attributed to H Tsuru.
Clinical and laboratory procedures used in a new telescopic system for removable partial dentures are discussed. This system uses 2-degree tapered inner and outer crowns with a horizontal pin soldered into the outer crown. The pin is easily adjusted to monitor the level of retention for the telescopic crown after long-term use of dentures.
A study was performed to evaluate the change of subgingival microflora with plaque accumulation around the single-crystal sapphire implant. Four implants were inserted into mandibular and maxillary edentulous regions, and the super-structure was inserted 1 month after implant insertion in each of nine monkeys. Plaque control was maintained for 3 months after insertion to establish the baseline. Plaque was allowed to accumulate on one side by placement of ligatures around the implants and natural teeth with no plaque control. On the other side plaque control was continued for 9 months. Both the implants and natural teeth on the ligature side showed significant increases in proportions of motile rods and spirochetes. No significant difference of microflora was detected between the implants and natural teeth. These findings indicate that plaque control is necessary to maintain the normal microflora around the implant.
Clinical and histologic evaluations of partially stabilized zirconia endosseous implants under unloaded and early loaded conditions in four beagle dogs were performed to examine the possibility of osseointegration of a newly developed one-stage zirconia implant during initial bone healing. No clear difference in clinical features was observed. Direct bone apposition to the implant was generally seen in both implants. However, loss of crestal bone height was quite evident around the loaded implants. These findings suggest that the initial unloaded condition is preferable to achieve osseointegration of one-stage zirconia implants.
The reproducibility of tooth tapping frequencies was measured in young and elderly dentate subjects. Six rates of tapping, i.e. 40, 60, 90, 120, 160 and 200 times per min, were practised to the accompaniment of a metronome for 15 s before recording. After a 15-s break, subjects were asked to reproduce the same rate of tapping without metronome accompaniment, and these movements were recorded. It was determined that the young subjects regulated tooth tapping frequencies by controlling velocity of mandibular movement. On the other hand, the elderly subjects regulated tooth tapping frequency by controlling opening width.
The present study was performed to confirm our previous proposal that the increase in neurotransmitter release is responsible for the supersensitivity of chronically decentralized artery to transmural nerve stimulation (TNS) in the rabbit. The ear artery was decentralized unilaterally by removing the preganglionic fiber proximal to the superior cervical ganglion (SCG), and the ear arteries and SCG were dissected 8 weeks after the operation. The increase in the tritium overflow induced by TNS from the chronically decentralized artery, which had been incubated with 3H-noradrenaline (NA) for 1 hr, was markedly increased at lower frequencies (0.1 and 0.2 Hz) than that from the control artery, whereas there was no difference at higher frequencies (> 0.5 Hz). No difference was observed in the neuronal uptake of 3H-NA during incubation for 1 hr between the control and decentralized arteries. There was also no change in the contents of catecholamines in both the artery and SCG after chronic decentralization, when assayed by a radioenzymatic procedure. In conclusion, the results obtained indicate that the supersensitivity to TNS after chronic decentralization is not due to the deranged catecholamine uptake and storage mechanisms in adrenergic nerve terminals and augmented transmitter biosynthesis, but due to the increased release of transmitter in response to low frequencies of TNS.
A study was made on the relatively immediate relaxant effect of cholera toxin (CTX) on the isolated ear artery, thoracic aorta and saphenous vein of the rabbit. Both preparations of CTX, containing sodium azide (NaN3) and azide-free, showed no effect on the non-precontracted artery, but CTX containing NaN3 relaxed the moderately precontracted blood vessels with methoxamine promptly, i.e., with a time course of min order. However, the immediate relaxation produced by CTX containing NaN3 was attributed mainly to NaN3. Azide-free CTX, on the other hand, at 1-10 micrograms/ml gradually produced concentration-dependent relaxation of the precontracted vessels. The relaxant effects of CTX on the vessels were slow and long-lasting, i.e., with a time course of 10 min order. The relaxation induced by CTX was not influenced by the removal of endothelium nor by pretreatment with 10 microM indomethacin, 3 microM atropine or 3 microM propranolol. Activation of protein kinase C by a phorbol ester inhibited the relaxant effect of CTX. These results indicate that CTX relaxes the blood vessels by directly acting on the smooth muscles, without mediation by known endogenous relaxing factor, such as endothelium-derived relaxing factor (EDRF = NO) or prostaglandin I2 (prostacyclin) and by muscarinic receptor or beta-adrenoceptor.
Horseradish peroxidase conjugated with wheat germ agglutinin (HRP-WGA) was injected into the trigeminal ganglion of adult rats to label the peripheral sensory receptors of the tongue. The conjugate was transported anterogradely to all the ipsilateral fungiform papillae and filiform papillae. Some labeled fibers crossed over to the contralateral papillae. In the intrinsic tongue muscle undulating nerve fibers along or across muscle fibers were often observed, and formed simple spiral endings.
Explore the source record for details and available documents.
To clarify the three-dimensional bone structure around a plasma-sprayed hydroxyapatite-coated endosseous dental implant, bone contact with the implant at 75 microns intervals was evaluated. Based on digitized data, three-dimensional graphics of the bone around the implant was clearly shown. These graphics provide adequate information on the bone-implant interface and also suggest development of a realistic finite element model.
This study was performed to evaluate clinical changes of the gingiva with plaque accumulation around the single-crystal sapphire implant. Four implants were inserted into mandibular and maxillary edentulous regions, and the superstructure was inserted 1 month after insertion of the implants in each of nine monkeys. Plaque control was maintained for 3 months after insertion to set up the baseline. Plaque was allowed to accumulate on one side by placing the ligature around the implant and natural teeth without any plaque control, and on the other side plaque control was continued for 9 months. Both the implant and natural teeth on the ligature side showed a significant increase in the clinical parameters of plaque index, gingival index, and probing depth. No significant difference was obtained between the implant and natural teeth. These findings indicate that plaque control is of great importance for maintaining the health of peri-implant gingiva.
Tissue reaction and stability of partially stabilized zirconia ceramic in vivo was evaluated with the use of the subcutaneous implantation test. During the experimental period, zirconia ceramic was completely encapsulated by a thin fibrous connective tissue with less than 80 microns thickness. No changes of weight and 3-point bending strength were detected after 12 months of implantation. The result suggests that zirconia ceramic is biocompatible and no degradation of zirconia ceramic occurred.
Explore the source record for details and available documents.
Sodium fluoride (NaF) produced concentration-dependent relaxation of isolated rabbit ear artery precontracted with norepinephrine. In contrast, an arterial preparation with the endothelium rubbed off did not relax, but contracted in response to NaF. NaF-induced relaxation was not influenced by indomethacin but was inhibited by methylene blue or NG-monomethyl-L-arginine. The results indicate that NaF relaxes the artery by releasing a so-called EDRF.
Stimulation of muscarinic cholinergic, alpha-adrenergic and beta-adrenergic receptors elicited mucin release from dispersed dog submandibular cells. The secretory response to acetylcholine was much more pronounced than to adrenergic agonists, and largely dependent on the presence of extracellular Ca2+, but the dependency on extracellular Na+ was slight. Ionomycin also stimulated mucin release. In rat submandibular cells, neither muscarinic cholinergic agonists nor ionomycin were as effective mucosecretagogues as beta-adrenergic agonists. alpha-Adrenoceptor-mediated release was decreased by chelating extracellular Ca2+ with EGTA. The beta-adrenoceptor-mediated response was diminished by extensive exposure of cells to EGTA, due at least in part to the requirement of Ca2+ for beta-adrenoceptor stimulation of cAMP formation. 8-br-cAMP stimulated 45Ca2+ release from cells preloaded with 45Ca2+. The 8-br-cAMP-induced mucin release was eliminated in ionomycin-pretreated cells, but not inhibited by chelating extracellular Ca2+ and by the treatment of the cells with TMB-8 or in the cells loaded with BAPTA. These results suggest that not only the adrenergic system but also the muscarinic cholinergic system may participate in the regulation of mucin release in dog submandibular gland, and also provide the possibility that, in addition to a cAMP-mediated mechanism, Ca(2+)-dependent mechanisms may be involved in mucosecretion in dog submandibular acini.
Anterior disk displacement without reduction, called "closed locking," is a serious stage of the internal derangement of the temporomandibular joint. Many types of conservative and surgical treatments have been applied to this problem. A new manipulation technique to release "closed locking" of the temporomandibular joint and the clinical results on 35 patients are reported in this study. Voluntary maximal mouth opening of the patients were measured as interincisal distance before and after the application of the manipulation technique. The voluntary maximal mouth opening of 14 of 17 patients (82%) who were younger than 30 years was improved to more than 40 mm after the application of the manipulation technique. Contrariwise, the voluntary maximal mouth opening of only 5 of 18 patients (28%) who were older than 30 years was improved to more than 40 mm.
Mandibular reaction time was measured in young and elderly volunteers. Each subject was instructed to open the jaw from the closed position and to close the jaw from the open position as quickly as possible after perceiving an auditory or visual signal. The reaction time of the elderly subjects to both signals was significantly slower than that of the young subjects. This was due almost entirely to prolongation of the premotor time component. There was no difference in the maximum velocity of the jaw movement between the two groups of subjects.
We investigated the effects of several antibiotics on the adherence of Staphylococcus aureus FDA 209P to polymorphonuclear leukocytes. Sublethal concentrations of aminoglycosides enhanced staphylococcal adherence to polymorphonuclear leukocytes, whereas beta-lactams, minocycline, ofloxacin and clindamycin decreased the adherence. Chloramphenicol and rokitamycin had no effect. It is likely that the adherence following antibiotic treatment is related to cell surface hydrophobicity determined by the measurement of the contact angle of 1-bromonaphthalene on a monolayer of staphylococcal cells.
The present study was undertaken to clarify whether there is a deficiency in the relaxation mediated by the adenylate cyclase-cyclic AMP (cAMP) system in the portal vein as compared to the saphenous vein. Longitudinal strips of the portal vein and helical preparations of the saphenous vein were used. The relaxation response to various agents was examined under conditions such that the venous preparations were previously contracted by methoxamine in equipotent concentrations (EC80), i.e., 10(-6) M for portal vein and 10(-5) M for saphenous vein. The saphenous vein relaxed fully in response to isoproterenol but the portal vein relaxed only to 29% of the maximum relaxation induced by papaverine 10(-4) M. However, dibutyryl cAMP and 8-bromo-cAMP, membrane permeable derivatives of cAMP, 3-isobutyl-1-methylxanthine and papaverine, phosphodiesterase inhibitors, and forskolin, a direct stimulator of adenylate cyclase, relaxed portal and saphenous veins similarly though with quantitative differences. The results suggest that there is no profound deficiency in the adenylate cyclase-cAMP system but there may be a deficiency in the coupling between surface beta-adrenoceptors and adenylate cyclase or there may be a low density of beta-adrenoceptors in the portal vein.