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Biomedical subjects

J Shimada

Publications and source records attributed to J Shimada.

At least 163 records · Page 9Linked to original sources
PubMed1989

Determination of 3,5,6-trichloro-2-pyridinol levels in the urine of termite control workers using chlorpyrifos.

Chlorpyrifos, an organophosphorus insecticide, has been used to control termites since regulatory measures against the use of chlordanes were taken in September, 1986. We developed an improved gas chromatographic (GC) method for the assay of 3,5,6-trichloro-2-pyridinol (TCP) in the urine to use in the biological monitoring of exposure to chlorpyrifos. Urinary TCP was separated and determined accurately (C.V., 4%) with high sensitivity (detection limit, 10 ng/ml) and recovery (recovery greater than 90%) using a wide bore capillary column (WBC column). The accuracy and precision of the present GC method are satisfactory. The time course of urinary excretion of TCP was followed in workers. The urinary TCP level was low in the off-season and high in the busy season. Variation in the urinary TCP level corresponded to the termite control season and the length of the working period. The urinary TCP level showed a change reciprocal to the variations in the plasma cholinesterase activity. From these results, it is surmised that the urinary TCP level represents the extent of exposure to chlorpyrifos. The decrease in the level of cholinesterase activity is suggested to be due to exposure to chlorpyrifos. Determination of the urinary TCP level by GC using a WBC column is useful in the biological monitoring of chlorpyrifos in termite control workers and potentially has practical application to health care.

Adult↗
PubMed1989

[Changes in the microvascular patterns during the osseous healing of the tooth extraction wounds].

Successive changes in the vascular pattern during the osseous healing of extraction wounds were investigated by studying microvascular casts under a scanning electron microscope. The casts were prepared utilizing the plastic injection method, after the extraction of the upper four incisors of the Japanese monkey (Macaca fuscata). Five days after extraction, vascular buds have sprouted from a pre-existing blood vessel on the alveolar wall into the blood clot, and leakage of the plastic injected was found from the tips of these buds. One week after extraction, newly-formed vessels have extended widely to the socket center, and dilated vessels have arborized towards the socket opening. Two weeks after extraction, the socket was filled with thick, newly-formed vessels. In the socket fundus, the woven bone was formed between irregular vascular networks, but was arranged different in the socket wall. Four weeks after extraction, the new bone forming on the socket wall became thickened and converted to a lamella-like bone. Inside it the woven bone was raised from the fundus, and blood vessels leaving it were decreased in their thickness and passed toward the socket center. Five weeks after extraction, the new bone structures came up to the level of the socket opening, the surface of which appeared as a shallow concavity (pivot), from which vascular bundles were directed to the socket opening. A beginning of the bone-remodeling was seen in osseous trabeculae in the socket fundus. Six weeks after extraction, almost all of the socket became filled with new trabeculae, between which, fine vascular networks were sorted out and communicated with the periosteal vascular network beyond the socket margin. The interalveolar septum between the extraction sockets was thickened by deposition of the lamella-like bone to be remodeled to a cancellous bone. It can be said that microvascular patterns formed through all stages of the osseous healing of the extraction wounds contributed to a woven bone formation and its development.

Alveolar Process↗
PubMed1989

Synthesis and antibacterial activity of novel 3-substituted carbacephems.

A series of novel 3-heterocyclothio substituted carbacephems having phenylglycyl side chain have been prepared starting from 3-H carbacephem. The compounds exhibit better chemical stability than the corresponding cephalosporin and strong activity against Gram-negative and Gram-positive organisms including Enterococcus faecalis.

Cephalosporins↗
PubMed1989

[Biomechanical study on the mechanism of the mandibular condylar fracture. 1].

The condylar process is one of the sites predisposed to fracture clinical and experimental studies on the fracture mechanism have so far been undertaken by a number of our predecessor. However, the difference in the fracture mechanisms of intracapsular and extracapsular fracture has not completely been determined yet. In a Japanese Journal of Oral and Maxillofacial Surgery: Vol.32, 1362-1381, 1986: Shimada have previously reported the strong possibility that the direction and extend of fracture lines in the fracture of condylar process were influenced by the morphological characteristics of the condylar head. In order to verify this postulation, stress distribution patterns by the cross-sectional morphology of various types of condylar heads were investigated by two-dimensional finite element method, using 15 Indian edentulous mandibles. In this analysis, loading was applied to three directions in the model of the mandibular body, and two directions in the model of the mandibular head. The results indicated the following something. 1) With the loading in the direction of condylar head from mandibular angle, compressed stress arose on the condylar head with the surface. And with the loading in the direction of condylar head from chin and mandibular body, tugged stress arose on the condylar neck. 2) With the loading in the direction of vertical, these were conjectured that comminuted fracture arose on convex type, sagittal fracture arose on concave type and a style midway fracture arose on straight type. 3) With the loading in the direction of lateral, these were conjectured that fracture of condylar neck arose on the three types, especially the tendency was remarkable on straight type.

Biomechanical Phenomena↗
PubMed1989

[Measurement of oral and facial blood flow with a laser Doppler flowmeter. 4. Alteration of oral blood flow by position change].

The laser doppler flowmeter was developed by Stern in 1975 and applied for practical use by Nilsson et al. in 1980. Since then, it has been used in various fields of medicine. The primary advantages of this device an that it is noninvasive and can monitor the blood flow continuously and rapidly. We used a Laser doppler flowmeter to continuously monitor the change in the oral peripheral blood flow due to changes in the body position of patients in a dental chair, since such changes are unavoidable during the course of dental treatment. A change from the sitting position to the supine position caused an increase in oral blood flow in 19 of 20 patients. In terms of the mean value per minute, oral blood flow was 23% greater in the supine position.

Blood Flow Velocity↗
PubMed1989

[Two cases of Frey's syndrome].

During the taking of meals, complex symptoms such as perspiration, rubor, and febrile sensation can appear on the skin overlying the temporal area or the parotid gland after the passage of some time after an operation in the parotid area or trauma inflicted to this area. This phenomenon is usually called Frey's syndrome. We recently encountered two cases of this syndrome. The patients were a 16-year-old boy who developed this syndrome following open reduction of the fractured left temporomandibular articular process and a 72-year-old man who developed it following left hemimandibulectomy and left radical neck dissection performed for the treatment of left mandibular gingival cancer. Frey's syndrome is a relatively rare surgery-associated complication. However, it may be advisable to inform the patient of this possibility prior to an operation, because patients may be severely afflicted by heavy perspiration if this syndrome develops over an extensive area.

Adolescent↗
PubMed1989

[Mechanical study on the stability of multiform mini-plates. I. Double-T-type plate (90, regular, 6-holes) in mandibular body fracture].

In this present paper, we reported the stability of osteosynthesis using a special type of mini-plate for mandibular fractures as evaluated from a mechanical study with static loading. The materials used in this study were fifteen bars made of acrylic resin, each divided at the center of its length into two parts to simulate a condition of mandibular body fracture. Following the fixation of these materials with mini-plates firmly attached between their cut ends, the bars were secured in a vice at one end and a static load was applied from the vertical direction at the other end. The amount of displacement of the loaded end was investigated with a displacement-measuring device, and the strains on mini-plates and test bars were measured with strain gauges. A comparative study was conducted on three kinds of mini-plates: 1) Group S, fixed with one Champy mini-plate, 2) Group W, fixed with two Champy mini plates, 3) Group T, fixed with one double-T-type mini-plate. The following results were obtained: 1) The amount of displacement was largest in the vertical direction and smallest in the horizontal direction in the three groups. Especially in group T, it was smaller the longitudinal and horizontal axes than in the other two groups. 2) Longitudinal strain of the plate was smallest in group W. However, the strain on the test bar was smallest group S. Especially , in group T, the largest compressive strain was observed at the lower portion of the synthesized ends.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Plates↗
PubMed1989

[Plastic operation of alveolar process by visor osteotomy].

Extraction of teeth from the lower jaw often results in atrophy of the alveolar process and mandibular body, and sometimes the atrophy progresses so severely as to seriously affect the fitness of the denture, especially the full denture. If the alveolar ridge is markedly resorbed, patients are not satisfied, unless the alveolar process is surgically heightened and the fitness of the denture is regained. Plastic operation of the alveolar process by visor osteotomy and grafting of the iliac bone was performed on a 54-year-old woman who presented at our Department with a complaint of unfitness of the full denture because of marked atrophy of the mandibular alveolar process. As a result of this operation, a functionally well-fitting denture could be fitted to the satisfaction of this patient. This paper describes the outline of the surgical procedure.

Alveolar Ridge Augmentation↗
PubMed1988

[Combined immuno-radio-chemotherapy of head and neck non-Hodgkin's lymphoma].

Twenty-one previously untreated cases, who underwent the same protocol at our department from January 1984 until December 1986, were investigated. The following results were obtained. Non-Hodgkin's lymphoma accounted for 10.5% of all the head and neck malignant tumors at our department. The age range was from 23 to 76 years of age and had a peak in the forties. Fourteen were male and seven were female. According to the stage distribution, six cases were stage I (28.6%), nine were stage II (42.9%), four were stage III (19.0%) and two were stage IV (9.5%). Stage I and II accounted for 71.4%. By site grouping, palatine tonsil and nasal cavity accounted for 38.1%, respectively. Surgical therapy was presumably useful for a solitary lesion which resisted all conservative therapies. By combined therapy with radiotherapy, VAPE-Chemotherapy and OK-432-immunotherapy, the survival rates were 100% (stage I), 77.8% (Stage II), 50% (stage III) and 50% (stage IV). The mean survival rate was 76.2%.

Adult↗