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Biomedical subjects

F Miura

Publications and source records attributed to F Miura.

17 recordsLinked to original sources
PubMed1992

[Responses of antidiuretic hormone (ADH) and atrial natriuretic polypeptide (ANP) to hypertonic saline infusion in essential hypertensive patients and normotensive subjects].

The demonstration that exogenous atrial natriuretic polypeptide (ANP) has markedly lowered plasma antidiuretic hormone (ADH) suggests a possible negative control of endogenous ANP on the secretion of ADH from the posterior hypophysis. To test this possibility and to clarify the role of ADH and ANP in the pathophysiology of essential hypertension (EHT), the responses of ADH and ANP to a hypertonic saline infusion were investigated in EHT patients and normotensive subjects (NT). Twenty inpatients with EHT (10 males and 10 females; 50.5 +/- 6.5y) and 10 NT subjects (5 males and 5 females; 50.6 +/- 7.8y) underwent a 20 min intravenous infusion of hypertonic saline (2.5% NaCl; 0.25ml/kg/min) in a fasting state. Blood samples were drawn before and 10, 20, 30, 45 and 60 min after the infusion and analyzed for ADH and ANP as well as plasma osmolarity (Posm), Na and albumin. Basal levels of ADH and ANP were not significantly different between NT and EHT. ADH was rapidly increased by the infusion in both groups; however, its percent increase was much higher in EHT than in NT during and after the infusion. Surprisingly, a highly significant negative correlation between ADH and ANP was found before and after the infusion in both groups. Although blood pressure was not changed significantly, the enhanced response of ADH to a sodium and volume load may play a role in part in the pathophysiology of EHT. In addition, it has been suggested that a possible suppression by ANP on the secretion of ADH may be one of the mechanisms of the diuretic action of ANP.

Adult↗
PubMed1992

Effect of 4-MET on bond strength and penetration of monomers into enamel.

The effect of 4-[2-(methacryloyloxy)ethoxycarbonyl]phthalic acid (4-MET) in self-curing acrylic resin initiated by BPO-amine on the bond strength to etched enamel was studied. Scanning electron microscopic (SEM) observations of resin-enamel interfaces were carried out to elucidate the bonding mechanism and the effect of 4-MET on the adhesion. 4-MET, which has both hydrophilic and hydrophobic groups, increased the bond strength of self-curing acrylic resin to etched enamel and improved the bonding stability. SEM pictures strongly suggested that 4-MET promoted interpenetration of monomers into enamel prism peripheries and their polymerization therein resulted in excellent adhesion to etched enamel.

Acid Etching, Dental↗
PubMed1992

Changes in the microvasculature after mechanical pressure on the hamster cheek pouch.

The reaction of the microvasculature in the periodontal ligament to mechanical pressure is considered a very important phenomenon with respect to the biological background to orthodontic tooth movement. For clarification of the microvascular reaction to mechanical pressure, an experimental model that incorporated a hamster cheek pouch was established. This in vivo model solves some of the problems of other experimental models of the microvasculature of the periodontal ligament. Blood plasma permeation in this model was examined by means of a blue dye (pontamine sky blue), and histological observation was performed by light and transmission electron microscopy. Increased vascular permeability was observed within 30 min after removal of the mechanical stimulation. The threshold weight resulting in dye leakage was between 1 and 5 g applied for 60 min. From the histological observations, some large gaps between the endothelial cells in venules were found, while most basement membranes remained undisturbed. These observations suggest that the plasma leakage was due to mild traumatic injury to the endothelial cells. Both leukocytes and platelets were observed in the gaps between the endothelial cells in the venule. These types of microvascular reactions to mechanical pressure could initiate tissue changes in the periodontal ligament during orthodontic tooth movement.

Animals↗
PubMed1992

Super-elasticity and thermal behavior of Ni-Ti alloy orthodontic arch wires.

Bending properties and thermal behavior of twenty commercial Ni-Ti alloy orthodontic arch wires were investigated quantitatively to characterize their suitability for clinical use. There was substantial difference among the load-deflection curves obtained by a three-point bending test. Some wires exhibited super-elasticity; load decreased little with decreasing deflection. Others showed good spring-back properties only; load was nearly proportional to deflection. Thermal behavior due to phase transformation of the alloy was examined by differential scanning calorimetry (DSC). Some of the wires did not have the correct transformation temperatures to exhibit super-elasticity at body temperature. Moreover, thermal behavior was closely related to super-elasticity. There were clear thermal peaks in the DSC curves of the super-elastic wires. However, wires without super-elasticity had no peak in the DSC curves.

Dental Alloys↗
PubMed1992

[A dental anthropological study of Chinese in Taiwan (3). Dental trait].

Models of the upper and lower dental arches of 125 Chinese children in Taiwan with acceptable normal permanent dentition were surveyed in order to understand the developmental grades of dental traits from the viewpoint of dental anthropology. Developmental grades of dental traits were classified, calculated, statistically analysed by x2 test and results were summarized. Upper anterior teeth showed high frequency of shovel form; upper lateral incisors showed less tendency of regression. Interstitial cusp, lingual cusp, paracusp, central prominence and occlusal groove of lower premolars developed prominently. Upper molars showed low frequency of Carabelli cusps. Hypocone of upper second molars showed strong tendency of regression, but metacone had low regression tendency and a strong degree of compression. Compared to Japanese, Central American and South American Indians and Caucasians, the development of dental traits of Chinese in Taiwan was more similar to that of Japanese than to others. The characteristics of dental trait of Chinese in Taiwan and Japanese also showed greater similarity to Central and South American Indians than to Caucasians.

Anthropology, Physical↗
PubMed1975

[Acute subdural hygroma in the posterior fossa (author's transl)].

Four cases of acute or subacute subdural hygromas in the posterior fossa were reported. All showed suboccipital skull fractures radiologically. Two cases of acute subdural hygromas were encounteded during the fiscal year from 1972 to 1973 at Toritsu Toshima Hospital. In the same period 254 patients with head injuries were admitted here and 106 demonstrated skull fractures. Among these 24 exhibited fractures in the suboccipital region. Among these 24 cases 8 showed signs and symptoms of space-occupying lesions in the posterior fossa and were confirmed later surgically (7 cases) or by autopsy (1 case), namely; three extradural hematomas, two acute subdural hygromas as mentioned above, three subdural hematomas with cerebellar contusions. Preoperative courses in these three acute subdural hygomas as well as three subdural hematomas were summarized as follows:lucid interval was followed by severe nuchal pain and rapid downhill course and finally by coma and panea. Retrograde brachial angiographies were performed in cases. The findings were not contributary to locate mass lesions, in three cases, partly because of delayed or faint filling of vessels caused by compression with hematoma or acute subdural hygroma. In short, differential diagnosis between subdural hematoma and subdural hygroma was difficult preoperating. Postoperatively, courses of subdural hematomas were poor or even fatal. On the contrary, patients of acute subdural hygromas showed rapid clinical improvement after evacuation of xanthochromic fluid. The authors stressed that suboccipital craniectomy should be performed as soon as possible to the patients with sugoccipital fractures when vital signs became progressively worse even if little findings were obtained by carotid angiographies. Subdural hygromas in the posterior fossa may have been present in those fatal cases where autopsy finds neither contusion nor hemorrhage but only brain edema or swelling.

Accidents, Traffic↗