Toyohiko Minami

Effects of Various Inflammatory Mediators on Eustachian Tube Patency

The effects of several inflammatory mediators on the patency of the Eustachian tube were evaluated in 15 mongrel dogs. Histamine, leukotriene C4(LTC4) and D4(LTD4), and platelet activating factor (PAF) were perfused through the Eustachian tube of anesthetized dogs at concentrations detected in human middle ear effusion of patients with otitis media. The patency of the Eustachian tube was then evaluated by perfusion pressure and opening pressure. Histamine at concentrations of more than 10(-5) M caused increased tubal resistance and opening pressure rapidly. LTC4 and LTD4 caused a rapid increase of tubal resistance and opening pressure at far lower concentrations, i.e. 10(-12) M. Doses of PAF over 10(-9) M may cause an increase in the opening pressure. These results indicate that various inflammatory mediators are capable of affecting the Eustachian tube function.

Head and Neck Reconstruction with Microvascular Tissue Transfer and its Surgical Indications: Our Experiences: A review

Microvascular tissue transfer has facilitated the primary closure of various complex defects after radical ablation of head and neck cancers. Recently, we have begun to use the forearm flap, osteocutaneous scapular flap, rectus abdominis myocutaneous flap, latissimus dorsi myocutaneous flap and jejunal autografts for reconstruction of the head and neck region following cancer ablation and have recognized further evidence of the versatility of free grafts. In this paper, we describe the results of 69 cases between 1987 and 1991 and the operative indication for microvascular tissue transfer in the head and neck region.

Histamine and Acetylcholine Regulation of Sympathetic Nerve Activity in Guinea-pig Nasal Mucosa

The regulating effects of histamine and acetylcholine (Ach) in norepinephrine (NE) transmission in nasal mucosa were investigated by analyzing 3H-NE release from isolated guinea-pig tissues. In addition, localization of the histamine H1 receptor and the muscarinic acetylcholine receptor on the sympathetic nerve in the guinea-pig nasal mucosa were examined by quantitatively evaluating these receptors after the unilateral removal of the superior cervical ganglion. Ach inhibited electrically-stimulated 3H-NE release in a concentration-dependent manner, and this effect was blocked by atropine. Histamine inhibited electrically-induced 3H-NE release at a concentration of 10(-5) M but enhanced it in concentration of 10(-3) M. Histamine increased the spontaneous release of 3H-NE in a dose-dependent manner, which was inhibited by pyrilamine (H1 antagonist) and excess Ach, but was not altered by cimetidine (H2 antagonist). These results suggest the following: 1) Local regulation of NE transmission in nasal mucosa involved excitatory H1 receptors, inhibitory H2 receptors and inhibitory muscarine receptors which can be facilitated by sensory stimulation with histamine. 2) Histamine regulation may vary with a balance between the excitatory and inhibitory effects. 3) Histamine in the high concentrations seen in cases of nasal allergy, may shift this balance causing increased NE release; at low concentrations, NE release is inhibited. In the second series of this study, we were unable to demonstrate a decreased number of either H1 or muscarine receptors on the side affected by unilateral cervical ganglia sympathectomy.

Enhanced Parasympathetic Nerve Activities in Experimentally-induced Nasal Hypersensitivity

In order to verify the role of cholinergic nerves in nasal allergy and nonspecific nasal hypersensitivity we have evaluated the muscarinic acetylcholine receptors and the activity of choline acetyltransferase in nasal mucosa of TDI-sensitized guinea-pigs at specific points in time during a pre-determined sensitization period. The density of muscarinic receptors was significantly elevated in animals sensitized for 8 and/or 12 weeks as well as in the group which received 12 weeks of sensitization followed by a 4 week rest period. Choline acetyltransferase activity was also enhanced at 4-, 8- and 12 weeks. These observations provide biochemical evidence of the hyperactivity of cholinergic nerves in nasal allergy which has been suggested by clinical and pharmacological studies, and lead to the speculation that enhanced parasympathetic nerve function is implicated in causing and maintaining hypersensitivity and hypersecretion in nasal allergy.

Regional blood flow volume in the eustachian tube.

Measurements of regional blood flow around the pharyngeal orifice of the Eustachian tube were carried out after topical administration of various inflammatory mediators in 14 mongrel dogs by the hydrogen clearance method. Histamine and platelet-activating factor (PAF) resulted in a significant alteration of blood flow volume. Histamine was found to induce a dose-response related increase, whereas blood flow volume tended to decrease in each concentration range in the series of PAF administration. There was no significant difference in blood flow between topical application of leukotriene C4 and leukotriene D4. It is likely that in upper respiratory tract inflammation, such as in otitis media and in nasal allergy, activated histamine and PAF affect the microcirculation of the tubal orifice. These results suggest that disturbance of the microcirculatory system in the Eustachian tube mucosa could be involved in the pathogenesis of chronic otitis media with effusion.

Clinical Studies of Oral Cancer.

Seventy-three cases of oral cancer (tongue: 47, oral floor: 10, buccal mucosa: 10, gingiva: 4, hard palate: 2) treatedinitially from 1985 to 1995 were reviewed retrospectively. The cumulative five year survival rate was 71.4% for all of the patients, and 75.8% for carcinomas of the tongue, 88.9% for carcinomas of the buccal mucosa and 42.2% for carcinomas of the oral floor. Further strategies are required in advanced cases with T4 staging in order to improve the survival rate and quality of life of oral cancer patients.