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Biomedical subjects

H Tsuru

Publications and source records attributed to H Tsuru.

At least 19 recordsLinked to original sources
PubMed1992

Trigeminal nerve endings of lingual mucosa and musculature of the rat.

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.

Animals↗
PubMed1992

The three-dimensional bone interface of an osseointegrated implant: a method for study.

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.

Animals↗
PubMed1992

Clinical evaluation of the gingiva around single-crystal sapphire endosseous implant after experimental ligature-induced plaque accumulation in monkeys.

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.

Aluminum Oxide↗
PubMed1992

Tissue compatibility and stability of a new zirconia ceramic in vivo.

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.

Aluminum Oxide↗
PubMed1991

Endothelium-dependent relaxation induced by sodium fluoride in the rabbit ear artery.

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.

Animals↗
PubMed1991

Calcium dependency of adrenergic and muscarinic cholinergic stimulation of mucin release from dog submandibular gland cells.

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.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

A manipulation technique for treatment of anterior disk displacement without reduction.

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.

Adolescent↗
PubMed1991

Mandibular reaction time to auditory and visual signals in young and elderly subjects.

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.

Acoustic Stimulation↗
PubMed1991

Effects of antibiotics on nonopsonized adherence of Staphylococcus aureus to human polymorphonuclear leukocytes.

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.

Aminoglycosides↗
PubMed1990

Relaxation response of isolated canine veins to agents that act on the adenylate cyclase-cyclic AMP system: further investigation.

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.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Antifungal drugs affect adherence of Candida albicans to acrylic surfaces by changing the zeta-potential of fungal cells.

The effect of sub-inhibitory concentrations of antifungal drugs on the adherence of Candida albicans to acrylic surfaces was investigated. Among five antifungals tested, azalomycin F and aculeacin A significantly enhanced the adherence. The zeta-potential of fungal cells was affected by antifungal drugs, whereas no significant change in cell surface hydrophobicity was observed. The relationship obtained between the change in the adherence and that in zeta-potential suggests that the enhanced adherence was caused by decreased electric repulsive forces.

Acrylates↗
PubMed1990

Two types of jaw-muscle spindle afferents in the cat as demonstrated by intra-axonal staining with HRP.

Intra-axonal records and horseradish peroxidase (HRP) injection techniques were employed to define the response properties of the jaw-closing muscle spindle afferents in the trigeminal mesencephalic nucleus (Vmes) and their morphological characteristics. The axonal trajectories of 9 spindle afferents from the masseter and 4 afferents from the temporalis were recovered for detailed analyses. Of 13 afferents, 6 cell bodies were stained and they were located at the rostrocaudal mid-levels of the Vmes. The central courses of the stem fibers were organized in a similar manner to the Vmes periodontal afferent nerves with the exception that peripheral (P) fibers of all spindle afferents passed through the trigeminal motor tract and root. On the basis of collateral terminal arborizations, the Vmes spindle afferents could be classified into two types: type I (n = 6) and type II (n = 7). Type I afferents sent their collaterals into the trigeminal motor nucleus (Vmo), intertrigeminal region (Vint) and juxtatrigeminal region (Vjux), but collaterals from the two neurons also projected to Vmes and the nucleus oralis (Vo). The collaterals from type II afferents formed their terminal arbors in the supratrigeminal nucleus (Vsup) in addition to the Vmo, Vint and Vjux, but collaterals from one neuron also projected to the Vo. In type I afferents, terminal arbors encompassed the whole Vmo including jaw-closing motoneurons. In contrast, boutons from type II afferents were restricted to a few small portions within the Vmo in proximity to its lateral and dorsal boundaries. The diameters of the united (U), central (C) and peripheral (P), fibers were larger in type I than type II afferents; those of the U fibers were statistically significant. Any differences between the two distinct types were not found in the response pattern to the sustained jaw opening. These results suggest that the difference of primary and secondary muscle-spindle afferent nerves is reflected in a distinctive morphology in the terminal arborizations and in the diameters of united fibers rather than the response patterns in deeply anesthetized cats.

Action Potentials↗
PubMed1990

Prevention of acquired immunodeficiency syndrome and hepatitis B. Part III: Disinfection of hydrophilic silicone rubber impression materials.

The effect of glutaraldehyde solution, an effective disinfectant for viruses, on the dimensional stability of hydrophilic silicone rubber impression materials was evaluated in this study. Disinfection with 2% glutaraldehyde solution showed a slight expanding effect on the dimensional stability of the hydrophilic silicone rubber impression materials (less than 0.03%). It was revealed that glutaraldehyde can be used for the disinfection of hydrophilic silicone rubber impression materials. Attention should be paid, however, to the conditions for investment or casting to eliminate the expanding effect of this disinfecting procedure.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Initial interface between submerged hydroxyapatite-coated titanium alloy implant and mandibular bone after nontapping and tapping insertions in monkeys.

To clarify whether direct bone interface of submerged plasma-sprayed hydroxyapatite-coated implants could be achieved by nontapping insertion, histologic and histometric studies were made on the structure of the interface between the implant and the mandible in two monkeys. All hydroxyapatite-coated implants, whether by nontapping or tapping insertions, were healed with direct bone apposition. No histologic and histometric difference of interface structure was observed between nontapping and tapping insertions.

Alloys↗
PubMed1990

Prevention of acquired immunodeficiency syndrome and hepatitis B. Part IV: The effect of impression material on glutaraldehyde solution.

Immersion of dental impressions in 2% glutaraldehyde has been shown to be an effective disinfection procedure for viral contamination. This study compared the effect of immersing impression materials on the concentrations of glutaraldehyde. Contamination with saliva slightly affected the concentration of glutaraldehyde. Irreversible hydrocolloid impression material markedly decreased the concentration of glutaraldehyde, whereas the immersion of silicone rubber impression material only slightly affected the concentration of glutaraldehyde. Attention should be paid to the concentration of glutaraldehyde solution when irreversible hydrocolloid impression material is immersed in the disinfectant.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Changes in retention of various telescope crown assemblies over long-term use.

An investigation was done on the effect of crown height, angle (one-half taper) and number of removals on the retention of telescope crowns. Assemblies of inner and outer crowns were constructed on master dies. Crown heights of 4 mm, 5 mm, and 6 mm were used. Cone angles of 0, 2, 4, and 6 degrees were used for each of the three heights. The inner crowns were fixed to the dies with an adhesive agent. the outer crowns were set over them and placed in a clamp. Separation forces were tested with an Instron machine (Instron Corp., Canton, Mass.). They were measured initially and after numerous 100 insertion/separation cycles up to 1000 cycles and numerous 500 insertion/separation cycles up to 10,000 cycles. The results demonstrated that the cone angle of the inner crown was more important than its height for maximum retention. Retention is rapidly lost after the cone angle exceeds 2 degrees. It was also shown that an accessory device is necessary to maintain retention capabilities after long-term use.

Analysis of Variance↗
PubMed1990

Finite element analysis of the relationship between clasp dimensions and flexibility.

A parameter study with use of the finite element method was conducted for examination of the relationships between the shape parameters of a clasp (width and thickness at the base and tip of the clasp) and its displacement or stress. By synthesis of these relationships, a simple formula defining the clasp tip displacement in terms of clasp dimensions ("displacement formula") was obtained. A stiffness parameter "Fd" (the load producing a 1-mm displacement of the clasp tip) was proposed, and a formula defining Fd in terms of shape parameters was derived from the displacement formula. Fd would be a practical parameter for the definition of clasp retention, and the present formulae appear to be useful tools for investigation of the retention of removable partial dentures.

Chromium Alloys↗