Biomedical subjects

T Sasano

Publications and source records attributed to T Sasano.

41 records · Page 3Linked to original sources

PubMed1989

Arterial blood pressure regulation of pulpal blood flow as determined by laser Doppler.

Dynamic changes of pulpal blood flow (PBF) and gingival blood flow (GBF) induced by intra-venous injection of two kinds of vasoactive drugs were observed in dogs by means of Laser Doppler Velocimetry. Intra-venous injection of norepinephrine caused PBF to increase, corresponding to the blood pressure (BP) increase, while GBF decreased. Orciprenaline sulfate caused PBF to decrease parallel to the BP decrease, as compared with a GBF increase. The effects of these vasoactive drugs lasted longer on GBF than on PBF and BP. These results indicate that the regulation of blood flow in the dental pulp is more dependent on systemic blood pressure than on local vasoconstriction or vasodilation.

Animals↗

PubMed1989

Characterization of bacterial deposits formed in vivo on hydrogen-ion-sensitive field-effect transistor electrodes and enamel surfaces.

In order to clarify the bacteriological similarities of bacterial deposits formed on transistor pH electrodes (pH-ISFET) and enamel surfaces in vivo, bacteria were allowed to accumulate on indwelling electrodes in four human mouths, and the predominant bacteria were then isolated and characterized. Both the total number of bacteria accumulated per unit area and the population of predominant bacteria were similar for the electrodes and enamel surfaces, indicating that pH changes in the bacterial deposits formed on the electrodes can be representative of those occurring in natural dental plaque formed on enamel surfaces. Obligate anaerobes were predominant (68%) among the 346 isolates, and almost all the isolates were acidogenic. This may be a good reason why rapid pH-drop to pH 4 level was observed in every subject when 1% glucose or sucrose was applied to the bacterial deposits.

Adult↗

PubMed1989

Plaque pH recovery by mouth-rinses with water.

A transistor pH electrode (pH-ISFET electrode) was placed in each of four human mouths and bacteria were allowed to accumulate on it for 1, 2 or 3 days. Changes of plaque pH were measured in situ after application of sucrose solution (0.1, 1 or 3%) and, then, quick pH recovery by mouth-rinses with water was estimated. Although the acidic pH after application of 0.1% sucrose was easily and quickly recovered from by a few mouth-rinses with water, rather frequent mouth-rinses with water were required to recover from the acidic pH of 2- or 3-day-old plaque after the application of a 1 or 3% sucrose solution. For example, 15 (mean, n = 4) mouth-rinses with water were required for the 3 day-old plaque pH to recover after the application of 3% sucrose solution.

Colony Count, Microbial↗

PubMed1989

The blood flow in the periodontal ligament regulated by the sympathetic and sensory nerves in the cat.

This study was carried out to investigate the nervous control of the blood flow in the periodontal ligament measured by laser Doppler flowmeter. Ten adult cats were anesthetized with pentobarbital sodium (initial dose of 30 mg/kg, i.v. and maintenance dose of 5 mg/kg, i.v.). After enucleating the left eye ball, the superior alveolar nerve was exposed. The bone overlying the labial aspect of the left maxillary canine tooth root was pared away until a transparent layer of bone was left covering the periodontal ligament. A laser light from a probe of the flowmeter fixed at the tooth was beamed through the thinned bone. Three different patterns of responses were observed following the electrical stimulation of the distal end of the cut superior alveolar nerve: an increasing, a decreasing and a biphasic change of blood flow. The application of capsaicin onto the superior alveolar nerve reduced the response of blood flow increase but had no effect on the response of blood flow decrease. On the other hand, the response of blood flow decrease was completely inhibited by the pretreatment with phentolamine while the response of blood flow increase was not affected. The present results suggest that blood flow in the periodontal ligament of cats is controlled by sympathetic alpha-adrenergic fibers for vasoconstriction and by sensory fibers for vasodilation.

Animals↗

PubMedDate not supplied

Experimental study of nystagmus induced by injecting various solutions into the middle ear cavity.

Injecting of various solutions into the middle ear cavity of cats and rabbits provoked certain characteristic types of nystagmus which resembled caloric nystagmus or clinical cases of peripheral vestibular disorders. Solutions with different degrees of specific gravity, osmotic effect and ion composition were used in this study. Direction-changing positional nystagmus, irritative nystagmus, and paralytic nystagmus were elicited according to the physical or chemical properties of each solution. Histological findings showed mild changes in the perilymphatic space and/or in the endolymphatic space in the period with some characteristic types of nystagmus. Infiltration of the substances into the inner ear fluids from the middle ear cavity via a round window membrane were probably responsible for these types of nystagmus.

Animals↗