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Biomedical subjects

M Yamaga

Publications and source records attributed to M Yamaga.

36 records · Page 2Linked to original sources
PubMed1996

Acute stretching of peripheral nerves inhibits retrograde axonal transport.

The conjugation of horseradish peroxidase with wheat germ agglutinin was used to identify the effect on retrograde axonal transport of stretching the rat sciatic nerve indirectly by 10% and 20% femoral lengthening with a unilateral external fixator. To investigate the relationship between retrograde axonal transport and blood flow in the stretched nerve, nerve blood flow in the sciatic nerve was measured by a hydrogen washout technique. At 11% strain (20% femoral lengthening), the numbers of horseradish peroxidase-labelled motor neuron cells and nerve blood flow had decreased by 43% and 50%, respectively. Histological examination demonstrated ischaemic changes, but not mechanical damage. However, at 6% strain (10% femoral lengthening) there were no significant abnormalities. These findings suggest that the inhibition of retrograde axonal transport can be induced by acute stretching of the peripheral nerve and that circulatory disturbance is the main cause of the inhibition of retrograde axonal transport at the low strain.

Animals↗
PubMed1994

Fluorine uptake and crystallinity of dentin treated with glass ionomer cement containing tannin-fluoride preparation.

We investigated the fluorine uptake in various layers of bovine dentin treated with glass ionomer cement (GIC) where a tannin-fluoride preparation (HY agent) was incorporated in the cement powder at ratios of 0% (HY0), 1.5% (HY1.5), 5% (HY5), and 10% (HY10) by weight. The crystallinity of the dentin treated with the HY0 and HY10 cements was also investigated. The higher the ratio of incorporated HY agent, the deeper the penetration of fluorine in the dentin, and the greater the amount of fluorine taken up that bonded with the apatite. Compared with total fluorine uptake, more time is needed for fluorine to form a stable bond with apatite. It is also suggested that the crystallinity of dentin is enhanced when exposed to GIC containing the HY agent.

Animals↗
PubMed1993

Adhesiveness of glass ionomer cement containing tannin-fluoride preparation (HY agent) to dentin--an evaluation of adding various ratios of HY agent and combination with application diammine silver fluoride.

We bonded a glass ionomer cement (GIC) containing various amounts of incorporated tannin-fluoride preparation (HY agent) to bovine dentin and investigated the effect of the ratio of incorporated preparations and the changes in bond strength over time. HY agent was incorporated into the powder at 0% (HY0), 1.5% (HY1.5), 5.0% (HY5), and 10.0% (HY10) by weight. The shear bond strength and percent of the cohesive failure were measured. Similar tests were performed on samples where diammine silver fluoride was applied to the dentin prior to placing the cement. It was found that the bond strength on the first day was increased by incorporating 1.5% of the HY agent in the GIC. The combined use of diammine silver fluoride increased the bond strength of the GIC.

Adhesiveness↗
PubMed1993

Obturation of dentinal tubules with tannin-fluoride preparation (HY agent) incorporated into glass ionomer cement.

The degree of obturation of dentinal tubules as well as the dentinal uptake of F, Zn and Sr was investigated after placement of glass ionomer cement (GIC) containing variable proportions of the tannin-fluoride preparation, HY agent, into freshly prepared cavities. It was found that when HY agent was incorporated into the cement powder, there was both increase in electrical resistance in the dentinal floor of the GIC-restored cavity in addition to inhibition of dye penetration. Further, these changes were directly proportional to the concentration of HY agent. Electron probe microanalysis of the principal constituents of HY agent (F, Zn and Sr) revealed that the penetration depth for F and Zn was also directly proportional to the relative amount of incorporated HY agent, whereas Sr could not be detected regardless of HY concentration. Results clearly demonstrated that the higher the concentration of HY agent incorporated into GIC, the greater the degree of dentinal tubular obturation.

Animals↗
PubMed1992

Alveolar bone remodeling in the early stage of experimental apical periodontitis in the rat mandible.

Apical periodontitis was surgically induced in the mandibular first molar of rats and chronological changes in the periapical bone tissue were observed by histochemistry and electron microscopy. On the second postoperative day (Day 2), tartrateresistant acid phosphatase (TRACPase)-positive cells emerged on the bone surface facing the inferior alveolar nerve, whereas alkaline phosphatase (ALPase)-positive cells proliferated on the bone marrow surface of the mandibular canal wall. On Day 3, the active resorption of the mandibular canal wall appeared on the surface facing the inferior alveolar nerve. The bone of the upper wall of the canal was completely resorbed. On Day 4, however, numerous ALPase-positive cells emerged over the bone surface facing the inferior alveolar nerve intermingled with TRACPase-positive cells. On Day 5, repair of the upper wall of the mandibular canal by new bone progressed. Bone formation was also observed on the bone surface facing the inferior alveolar nerve. On Day 6, the upper wall of the mandibular canal was remodeled by the new bone, whereas TRACPase-positive cells had already migrated over the bone surface in the vicinity of ALPase-positive cells. From Days 2 to 5, active trabecular bone formation continued in the bone marrow cavity close to the mandibular canal, while TRACPase-positive cells were found only on Day 6. These demonstrate that inflammatory stimuli activate bone formation coupled with bone resorption, as well as direct trabecular bone formation without a bone resorption phase. A rapid bone turnover in the early stage of apical periodontitis is also suggested. We conclude that bone defects in apical periodontitis are not the result of sole bone resorption but rather, active bone remodeling.

Acid Phosphatase↗
PubMed1991

[Fluoride uptake from fluoride releasing resin as an orthodontic adhesive on human enamel].

FluoroBond is one kind of fluoride releasing, visible light-activated bonding system for orthodontic bracket placement. The first aim of this study was to investigate the fluoride release from FluoroBond. The second aim of this study was to determine the fluoride uptake by human enamel which was immersed in distilled water for 30 days in contact with FluoroBond. The third aim of this study was to demonstrate the fluoride uptake by human enamel adjacent to the bracket as well as by the human enamel beneath the bracket which was placed using FluoroBond, and immersed for 30 days in distilled water. The results obtained were as follows. 1) A great amount of fluoride was released from FluoroBond immediately after immersion. The fluoride released weakend rapidly over the first 10 days. However, the fluoride released became stable after the 10th day. 2) The uptake of fluoride from FluoroBond was large both on the surface and the subsurface enamel in contact with it. 3) When FluoroBond was used as a bracket bonding material, fluoride was absorbed from FluoroBond by the enamel not only under the bracket but also adjacent to the bracket.

Delayed-Action Preparations↗
PubMed1989

[A study of autonomic nerve dysfunction in patients with thoracic outlet syndrome].

The function of the autonomic nerve system in sixty-seven patients with thoracic outlet syndrome was examined by a non-invasive and quantitative technique assessing the mean (M) and coefficient of variation (CV) or R-R interval in ECG. The first group of patients (28 cases) with autonomic nervous disorder and complaints of general discomfort showed a significantly shorter M and smaller CV. The second group (39 cases), those without general discomfort, exhibited a normal range of M and CV. In four of the first group with the diagnosis of schizophrenia and anxiety neurosis, furthermore, M and CV were nearly the same as those in the second group. In eight of the first group undergoing decompression operation, their complaints decreased or disappeared after surgery, with recovery of M and CV almost to the normal level. According to these results, this method appears to be useful in differentiating between autonomic nervous disorders and psychological disorders, facilitating disappearance of general discomfort due to autonomic nervous disorders.

Adolescent↗
PubMed1987

Management of thoracic outlet syndrome.

The experience with transaxillary first-rib resection and scalenotomy reported herein shows these to be safe and effective treatments for patients with thoracic outlet syndrome (TOS). The former operation usually offers the best possibility for complete resection of the first rib and all anomalous congenital bands, and is curative in most cases, regardless of the mechanism of the compression. Scalenotomy, or Powers' operation, is also helpful, in particular for cases of TOS with a vertebral arterial insufficiency. Accurate diagnosis of TOS and selection for surgery after a detailed history and proper physical examination will result in gratifying relief of symptoms in almost all patients with TOS.

Adult↗
PubMed1986

A new, modified operation for funnel chest using the Zimmer osteosynthetic plate.

A corrective operation for funnel chest using a Zimmer osteosynthetic plate, which can be bent to any configuration desired, is described. This operative method can be employed for any type of chest deformity in adults and adolescents. A physiologically normal and perfectly stabilized anterior chest wall is obtained with this plate system, and no relapse occurs even after removal of the plate.

Adolescent↗
PubMedDate not supplied

Brachial plexus stretching injuries: microcirculation of the brachial plexus.

This study was undertaken to investigate the pathogenesis of brachial plexus stretching injuries at an intensity level not severe enough to cause avulsion injury. While we performed traction on 64 forelegs of 32 rats, we evaluated changes in the blood flow in the extrinsic and intrinsic microvascular systems of the brachial plexus. While we laterally stretched the brachial plexus during 80 degree shoulder abduction, we measured the blood flow at the bifurcation of the brachial plexus and at the median nerve with the hydrogen washout technique. During weak traction the blood flow decreased markedly in the extrinsic system, causing an imbalance in the two systems. In the median nerve, however, no such imbalance occurred. On histologic examination the axon and myelin in the brachial plexus and the median nerve showed no morphologic change. However, in parts of the brachial plexus we noted hypertrophic connective tissue or granulomatous inflammation in tissue surrounding the extrinsic system. The extrinsic system's apparent susceptibility to injury by acute traction may be a factor in the pathogenesis of the brachial plexus stretching injuries.

Animals↗
PubMedDate not supplied

Apophysitis of the acromion.

We treated three patients with apophysitis of the acromion. These patients were two male athletes 12 and 14 years of age, respectively, and one female athlete 13 years of age. They reported pain at the top of the shoulder during and after shoulder movement while playing sports but had no rest pain or disturbance of daily activities. Physical examination demonstrated marked local tenderness at the acromion and slight warmth. X-ray films showed sclerosis and irregularity of the secondary ossification center of the acromion. Bone scintigraphy carried out on one patient demonstrated increased uptake in that region. Conservative treatment was used for these patients. Recovery was gradual but satisfactory.

Acromion↗