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Biomedical subjects

M Sakuda

Publications and source records attributed to M Sakuda.

At least 163 records · Page 9Linked to original sources
PubMed1988

Decrease in analgesic effect of nifedipine following chronic morphine administration.

The analgesic effect of nifedipine, a calcium antagonist, was compared in the acetic acid-induced writhing test with control and morphine-tolerant mice. Nifedipine inhibited the writhing syndrome less effectively in mice made tolerant to morphine. The results support the notion that inhibition of the calcium influx is one of the causes of the analgesic action of morphine and that its chronic administration causes an increase of calcium entry.

Acetates↗
PubMed1988

Hydrocortisone stimulation of proliferation and glycosaminoglycan synthesis in rabbit craniofacial chondrocytes in vitro.

Hydrocortisone stimulated glycosaminoglycan (GAG) synthesis, a cartilage phenotype, in chondrocytes from mandibular condylar cartilage (MCC), nasal septal cartilage (NSC) and sphenooccipital synchondrosis (SOS). These stimulations were dose- and time-dependent, being maximal 27 h after addition of 10(-7) M hydrocortisone. The maximal induced increase of GAG synthesis was about 100%, 50% and 20% that of non-stimulated MCC, SOS and NSC chondrocytes, respectively. When stained with toluidine blue, all three types of cortisone-treated chondrocytes showed stronger metachromasia than non-treated controls. DNA synthesis was also increased by hydrocortisone, reaching a maximum 20 h after the addition; stimulation was also dose-dependent and maximal at a concentration of 10(-6) M. The maximal increase in DNA synthesis was 200% in NSC chondrocytes, 90% in SOS chondrocytes, and slight in MCC chondrocytes. However, there was no stimulation of DNA synthesis in serum-free medium, in contrast to that of GAG synthesis. These observations suggest that hydrocortisone regulates craniofacial growth by controlling the differentiation of these chondrocytes directly and their proliferation indirectly, and that the difference in their responses to hydrocortisone may reflect different responses in vivo.

Animals↗
PubMed1988

Three-dimensional model of the human craniofacial skeleton: method and preliminary results using finite element analysis.

The purpose of this study was to develop a three-dimensional finite element model of the craniofacial skeleton using a dry human skull. The model consisted of 2918 nodes and 1776 solid elements, and was used to investigate the biomechanical effect of a distally directed orthopaedic force on the craniofacial complex. The force was applied at the level of the maxillary first molar. The results indicated that in response to the force system applied: the nasomaxillary complex displaces in a backward and downward direction and rotates in clockwise sense; the nasomaxillary complex, including the zygomatic bone, experiences high stress levels in comparison with those at the remaining bones; the stress distribution in the maxillary basal bone area is relatively uniform; and the stress distribution across the opposing surface of the bony margins of the sutures is non-uniform.

Biomechanical Phenomena↗
PubMed1988

Unoperated adult cleft lip and palate: changes in form and function after operation.

This report describes the occlusion and craniofacial morphology--together with changes in tongue activity during swallowing before and after surgical correction--in a 26-year-old female patient with unilateral cleft lip and palate. Cross-bites were not observed before or after repair. Lateral cephalometric findings revealed a convex profile with a normal anterior cranial base length, a flat mandibular plane, and a short lower-anterior face height. Preoperative cineradiographic appraisal showed atypical tongue activity during swallowing. The dorsum of the tongue remained high to seal the cleft. The bolus was kept on the floor of the mouth and passed along the lateral margins of the tongue. The swallow duration, as determined by EMG of the tongue, was extremely long when compared with infant-operated cleft lip and palate patients and to noncleft subjects. Postoperatively, tongue function was similar to that in both cleft patients in whom closure was performed in infancy and to noncleft controls.

Adult↗
PubMed1987

Three-dimensional finite element analysis for stress in the periodontal tissue by orthodontic forces.

This study was designed to investigate the stress levels induced in the periodontal tissue by orthodontic forces using the three-dimensional finite element method. The three-dimensional finite element model of the lower first premolar was constructed on the basis of average anatomic morphology and consisted of 240 isoparametric elements. Principal stresses were determined at the root, alveolar bone, and periodontal ligament (PDL). In all loading cases for the buccolingually directed forces, three principal stresses in the PDL were very similar. At the surface of the root and the alveolar bone, large bending stresses acting almost in parallel to the root were generally observed. During tipping movement, stresses nonuniformly varied with a large difference from the cervix to the apex of the root. On the other hand, in case of movement approaching translation, the stresses induced were either tensile or compressive at all occlusogingival levels with some difference of the stress from the cervix to the apex. The pattern and magnitude of stresses in the periodontium from a given magnitude of force were markedly different, depending on the center of rotation of the tooth.

Alveolar Process↗