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Biomedical subjects

M Chiba

Publications and source records attributed to M Chiba.

At least 361 records · Page 20Linked to original sources
PubMed1983

The effect of a microfilament-disrupting drug, cytochalasin B, on 6-hourly and daily eruption rates of the rat mandibular incisor.

The drug did not affect 6-hourly and daily eruption rates of the unimpeded mandibular incisor of the rat. It is suggested that the tooth eruption is not inhibited by the disruption of microfilaments because the disruption was not associated with the motility of the cells and/or that the motility of the cells is not associated with the motive force of tooth eruption. Further studies may be necessary to confirm that the effects of cytochalasin B are on both microfilaments and motility of the periodontal fibroblasts.

Animals↗
PubMed1983

Noninvasive assessment of the autonomic nervous tone in angina pectoris: an application of digital plethysmography with auditory stimuli.

To assess the relationship between autonomic nerve activity and the anginal attack, we examined the daily variation of the autonomic tones employing digital plethysmography with auditory stimuli, and also tested the daily variation of exercise capacity. Thirteen of 45 cases (28.9%) of spontaneous angina, excluding Prinzmetal's angina, complained of typical chest discomfort or pain especially in the morning. They manifested an augmented level of the autonomic nerve activity and positive stress testing. The remainder did not demonstrate these abnormal findings in the morning. For the 13 cases, calcium antagonists were given orally immediately after awakening. This resulted in the complete relief from chest discomfort or pain. These findings suggest that an autonomic imbalance plays an important role in the pathogenesis of this type of anginal attack. Thus, the estimation of the daily variation of autonomic nervous tone would be valuable for the diagnosis and treatment of angina pectoris.

Acoustic Stimulation↗
PubMed1983

Stimulation of rat autologous mixed lymphocyte reaction with xenogeneic sera and their protein preparations.

Autologous mixed lymphocyte cultures were set up from nylon non-adherent T-enriched lymphocytes and mitomycin C-treated spleen cells of individual ACI/N rats and the effect on the reaction (AMLR) of sera in the culture medium was studied with regard to the xenogeneic nature of the sera. Not only foetal calf serum, but also sera of adult human, horse and swine stimulated the AMLR response, but autologous or rat serum did not. Albumin fractions of these sera were also effective in inducing the AMLR response. Furthermore, the presence of xenogeneic serum in the culture medium was also required for the blastogenic response of AMLR-primed lymphocytes against the secondary stimulation with syngeneic spleen cells. Both autologous and xenogeneic sera, however, supported the Con-A response of the same responder cell population as used in the AMLR. These results substantiated our previous finding (Endho & Hashimoto, 1981) and suggest that two signals, one from autologous non-T cells and another from the xenogeneic factor in culture medium, are required to cause AMLR, at least in the rat system.

Animals↗
PubMed1983

[Neurogenic gastrointestinal hemorrhage in hypertensive cerebral hemorrhage].

The purpose of this paper is to obtain the correlation between CT scan findings and neurogenic gastrointestinal bleeding in hypertensive intracerebral hemorrhage. Fifty patients with hypertensive intracerebral hemorrhage were operated upon during past nearly 3 years in our clinic. Of these, 27 patients (54%) showed macroscopic gastrointestinal bleeding (GI-bleeding) demonstrated by stomach catheter after the onset of hypertensive intracerebral hemorrhage. GI-bleeding was about 46% in the survived patients and about 77% in the expired ones. Most patients revealed neurogenic GI-bleeding within 9 days (85.2%) and more than half of the cases (51.9%) in 4 to 6 days after the onset. Neurogenic GI-bleeding was frequently complicated in patients with disturbed consciousness, over 60 gram hematoma (particularly 60-80 gram hematomas), severe ventricular hemorrhage and right-sided hematomas. It was also exclusively observed in patients with extension of hemorrhage into the midbrain and recurring hypertensive intracerebral hemorrhage.

Adult↗
PubMed1982

Effect of experimental tooth movement on the mechanical strength of the periodontium in the rat mandibular first molar.

A 474 microns thick latex elastic band was inserted between the mandibular first and second molars to cause tooth movement. The mechanical strength of the periodontium was measured by extracting the first molar from the socket in the dissected jaw. From the 1st to the 4th day, the ultimate extraction loads decreased markedly, while the inter-dental spaces remained about 300 microns. About 5 min after the elastic insertion, the ultimate load was not significantly changed and the inter-dental space was 61 microns. Restoration of the mechanical strength of the periodontium occurred gradually after the removal of the band. On the 4th day, recovery was complete. Restoration of the original inter-dental space was most marked in the initial 24 h. The forces exerted on the teeth by the bands were of the order of several tens of newtons initially and became reduced to a few newtons after the tooth movements. It is suggested that decreases in the ultimate extraction loads were caused by changes in constitution of the periodontal collagen, by the disorganization of the periodontium and by the loosening of the attachment of the periodontal fibres to the bone.

Animals↗
PubMed1982

The effect of hypofunction on the mechanical properties of the periodontium in the rat mandibular first molar.

The right maxillary molars of male rats were removed under ether anaesthesia to eliminate occlusal contact with the mandibular molars. Groups of rats were killed at 1, 2, 4, 8 and 16 days after the experimental procedure. The dissected mandibles were radiographed and length of erupted portion of the tooth, height of alveolar crest and length of tooth were measured. The tensile strength of the periodontal ligament was measured by extracting the first molar from its socket. A marked and progressive decrease of the load required to extract the tooth was found in the first few days after the removal of the opposing teeth. No significant difference in extracting loads was found between the 8- and 16-day groups. Radiography showed that the teeth had erupted, that the height of alveolar crest had decreased and that the length of the root had increased during the experimental period. These changes were detectable only on the 8th or 16th day following the experimental procedure. It is suggested that the reduction in the mechanical strength of the hypofunctional rat molar periodontal ligament is closely associated with the progressive atrophy of the periodontal ligament and that normal functional activity of the teeth is important not only for maintenance of the structural integrity of the periodontal ligament but also to maintain the mechanical strength of the supporting tissues.

Animals↗
PubMed1982

Effects of storage of jaws in saline and of velocity of loading on the force required to extract the rat mandibular first molar.

Storage of jaws in cold saline for up to 32 h did not cause significant changes in the ultimate loads required to extract the rat mandibular first molar. The mean ultimate loads were 33.05, 34.91 and 36.38 newtons at the extension rates 1, 5 and 25 mm/min respectively, though the differences were not significant between groups. The force required to extract the tooth would be fairly constant even after the storage of the dissected jaws in cold saline for longer periods of time. Changes in the force required were not detectable within the range of the velocities of loading employed.

Animals↗
PubMed1982

Characterization of structural properties for morphological differentiation of melanosomes: II. Electron microscopic and SDS-PAGE comparison of melanosomal matrix proteins in B16 and Harding Passey melanomas.

This study compared the qualitative and quantitative differences of the melanosomal matrix proteins between the ellipsoidal-lamellar melanosomes of B16 melanoma and the spherical-granular melanosomes of Harding Passey (HP) melanoma by electron microscopy and SDS (sodium dodecyl sulfate)-PAGE (polyacrylamide gel electrophoresis). The purity of the melanosomes at each step of the sample preparations was assayed by % distribution of cytoplasmic marker enzymes and proteins. Characterization of the melanosomal matrix was carried out in material purified by the 2 steps of sucrose density gradient ultracentrifugation and membrane dissociation with BRIJ-35. Eighty-three percent of the matrix proteins were solubilized from both B16 and HP by guanidine HCl (GH), which also caused marked ultrastructural changes in different ways. The inner matrix of HP completely disintegrated into fine grains whereas the matrix of B16 showed a great loss in electron density and was degraded, though its basic framework remained unchanged. Under SDS-PAGE, the melanosomal matrix was dissociated into 14 polypeptide bands with respect to size and charge density, 10 of which (63-85% of total proteins solubilized by GH) were common to both B16 and HP. A significant quantitative difference was noted in the relative amounts of these common proteins. The remaining 4 were unique in molecular weight to each form of melanosome though their relative amounts were low. It is suggested that these chemical differences, i.e., quantitative and qualitative, of the matrix proteins are responsible for the ultrastructural differentiation of melanosomes.

Animals↗
PubMed1982

Electron microscopic identification of Langerhans cells in the dermal infiltrates of mycosis fungoides.

The importance of the physical interaction between epidermal Langerhans cells and malignant cells in mycosis fungoides (MF) has been stressed recently. To further evaluate this concept, electron microscopic study was carried out to identify whether or not Langerhans cells are also present in the dermal infiltrates of MF. The cells with characteristic Langerhans cell-granules were found in the dermal infiltrates, from early patch to tumor lesions of MF. No vacuolous change suggestive of cell degeneration was found in these cells. These Langerhans cells revealed only a small number of specific granules, and nuclear cleavage and chromatin pattern similar to those of malignant lymphoid cells, thus hardly differentiating 2 cell types in a low power view. Similar to epidermal MF lesions, however, a close apposition of dermal Langerhans cells with malignant lymphoid cells was seen. In one occasion, one Langerhans cell was present at the epidermodermal junction, appearing as being in the process of crossing over the basal lamina. Inasmuch as malignant cells in MF have been shown to possess the functional properties of helper T cells and receptors for Ia (immune associated antigen), expressed in the epidermis solely on Langerhans cells, our findings may further suggest that these malignant T cells bind to Langerhans cells through a "lock and key" mechanism involving membrane-bound Ia.

Cytoplasmic Granules↗